JP2019147586A - Packaging bag for microwave heating and packaged food - Google Patents

Abstract

To provide a packaging bag which, while using on printed layers of laminated film ink whose lamination strength weakens due to microwave heating, smoothly discharges heating steam inside, and packaged food.SOLUTION: A packaging bag 101 is manufactured by heat-sealing sheets 1A, 1B, 1C made of laminated film so that a storage space 2 that stores food F is formed on the inner side of the packaging bag and has a peelable projecting seal part 3a formed for releasing steam V inside the storage space 2 during microwave heating. The laminated film has on the inner side of the packaging bag a sealant layer made of non-oriented polypropylene film, and has on further outside of the packaging bag than the sealant layer a printed layer made of ink that reduces the lamination strength due to microwave heating, and the non-oriented polypropylene film satisfies the conditional expression: (I1/I2)×100≤20 (%) at the projecting seal part 3a (I1, I2: seal strength under the environment at 100°C, and under the environment at room temperature (N/15 mm)).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a microwave oven heating packaging bag and packaged food, and more specifically, a microwave oven heating packaging bag made of a heat-sealed laminated film, and an electronic device in which food is sealed and packaged in the packaging bag. The present invention relates to a packaged food for range heating.

  As a packaging bag for heating a microwave oven, Patent Document 1 proposes a packaging bag equipped with a steam venting mechanism for releasing steam in the packaging bag during microwave oven heating. This packaging bag is made of a laminated film having a sealant layer as an inner layer, and is formed on a projecting seal portion formed so as to project inward from a seal portion on the periphery of the packaging bag and an unsealed portion in the projecting seal portion. A steam venting mechanism is constituted by the notch portion.

  In the packaging bag, when the internal pressure of the packaging bag rises due to microwave heating, the protruding seal part peels off, and the vapor in the packaging bag is discharged out of the packaging bag through the notch. An unstretched polypropylene (CPP) film is generally used for the sealant layer of such a microwaveable packaging bag. The unstretched polypropylene film has a feature that the projecting seal portion is easily peeled off when heated in a microwave oven because the seal strength under a high temperature environment is lower than the seal strength under a room temperature environment.

JP 2004-168429 A

  However, when a packaging bag as described in Patent Document 1 is composed of a laminated film having a print layer, depending on the ink constituting the print layer, peeling of the protruding seal portion during microwave heating is less likely to occur. There is. For example, if high density white ink, light-shielding ink, gold ink / silver ink, etc., such as metallic ink using aluminum paste, pearl ink, etc. are used for the printing layer, the laminate strength in the printing layer will be reduced when microwave oven is heated. . This is because if the pigment content is high or the pigment particle size is large, the binder content of the ink is low.

  When the laminate strength in the printed layer is reduced as described above, delamination occurs between the printed layer and the adjacent layer (intermediate layer or sealant layer), and the delamination causes smooth peeling of the protruding seal portion. It will be disturbed. That is, when delamination occurs in the projecting seal portion, the layer including the sealant layer inside the packaging bag extends further and peeling of the projecting seal portion does not proceed. As a result, it is difficult to discharge steam from the inside of the packaging bag to the outside of the packaging bag, and the packaging bag may swell and break the bag. In addition, the packaging bag swells even at a seal portion other than the projecting seal portion, and delamination occurs at a wrinkle portion or the like caused by the sacking portion, resulting in deterioration of the appearance of the packaging bag.

  The present invention has been made in view of such circumstances, and its purpose is to smoothly discharge the internal heating steam while using an ink whose laminate strength is reduced by microwave heating for the printed layer of the laminated film. It is to provide a packaging bag and a packaged food.

In order to achieve the above object, the microwave oven heating packaging bag of the first invention is manufactured by heat-sealing the laminated film so that an accommodation space for accommodating contents is formed inside the packaging bag. A microwaveable heating packaging bag formed with a peelable seal portion for escaping vapor in the accommodation space during microwave heating,
The laminated film has a sealant layer made of an unstretched polypropylene film on the inner side of the packaging bag, and has a printing layer made of ink whose laminate strength is reduced by microwave heating on the outer side of the packaging bag than the sealant layer,
The unstretched polypropylene film satisfies the following conditional expression (1) in the seal portion.
(I1 / I2) × 100 ≦ 20 (%) (1)
However,
I1: Seal strength in a 100 ° C. environment (N / 15 mm),
I2: Seal strength at room temperature (N / 15mm),
It is.

  The packaging bag for heating a microwave oven according to the second aspect of the present invention is the above first aspect of the invention, when the bag is made with a continuous bag making machine that manufactures an actual product, under a sealing temperature condition that does not impair the properties and functions of the product. The heat sealing is performed.

  A packaging bag for heating a microwave oven according to a third invention is the above-described first or second invention, wherein the ink is a metallic ink using an aluminum paste, such as high-concentration white ink, shading ink, gold ink / silver ink, It is at least one of pearl inks.

  A packaging bag for heating a microwave oven according to a fourth aspect of the present invention is the base material layer according to any one of the first to third aspects, wherein the laminated film is formed adjacent to the outer side of the packaging bag of the printing layer. And an intermediate layer formed between the printed layer and the sealant layer.

The microwave oven heating packaging bag according to a fifth aspect of the present invention is that, in any one of the first to fourth aspects, the unstretched polypropylene film satisfies the following conditional expression (1a) in the seal portion. Features.
(I1 / I2) × 100 ≦ 13 (%) (1a)
However,
I1: Seal strength in a 100 ° C. environment (N / 15 mm),
I2: Seal strength at room temperature (N / 15mm),
It is.

In the microwave oven packaging bag according to a sixth aspect of the present invention, in the first to fifth aspects of the invention, the unstretched polypropylene film satisfies the following conditional expression (2) in the seal portion. Features.
3 (%) ≦ (I1 / I2) × 100 (2)
However,
I1: Seal strength in a 100 ° C. environment (N / 15 mm),
I2: Seal strength at room temperature (N / 15mm),
It is.

  A packaged food for heating a microwave oven according to a seventh aspect of the invention is hermetically packaged in the packaging bag according to any one of the first to sixth aspects of the invention, with the food as the contents being contained in the accommodation space. It is characterized by.

  According to the present invention, since the unstretched polypropylene film constituting the sealant layer has physical properties satisfying predetermined conditions with respect to the seal strength, an ink whose laminate strength is reduced by microwave heating is applied to the printed layer of the laminated film. It is possible to realize a packaging bag and packaged food from which the internal heating steam is smoothly discharged while being used in the above.

The external view which shows one Embodiment of the packaging bag for microwave oven heating, and packaged food. Sectional drawing which shows the specific example of the laminated | multilayer film which comprises the packaging bag of FIG. The graph which shows the physical property of the unstretched polypropylene film which comprises a sealant layer in the laminated | multilayer film of FIG.

  Hereinafter, packaging bags, packaged foods, and the like according to embodiments of the present invention will be described with reference to the drawings. Note that the same or corresponding parts in the embodiments and specific examples are denoted by the same reference numerals, and redundant description is omitted as appropriate.

  In FIG. 1, the external appearance structure of the packaging bag 101 which concerns on embodiment, and the packaged food 201 is shown typically. 1A is a plan view showing a stand-type packaging bag 101 in a folded state, and FIG. 1B is a front view showing a packaged food 201 in which food F is sealed in the packaging bag 101. . The packaging bag 101 is composed of three sheets of a front sheet 1A, a back sheet 1B, and a bottom sheet 1C, all of which are made of a laminated film. And it is bag-made by the heat seal (thermal bonding) of a laminated | multilayer film so that the accommodation space 2 which accommodates the food F as a content is formed inside a packaging bag. This heat sealing is performed under a sealing temperature condition in a range that does not impair the properties and functions of the product at the time of bag making with a continuous bag making machine for producing an actual product. In addition, the specific structure (FIG. 2) of a laminated film is demonstrated later.

  The front sheet 1A and the back sheet 1B are heat-sealed at the left and right edges when they are overlapped, and the bottom sheet 1C folded in half is heat-sealed at the edges at the lower ends of the front sheet 1A and the back sheet 1B. ing. However, the upper ends of the front sheet 1A and the back sheet 1B are not sealed. That is, in the packaging bag 101, the body seal portion 4 formed by heat sealing between the front sheet 1A and the back sheet 1B, and the bottom seal formed by heat sealing each of the front sheet 1A, the back sheet 1B, and the bottom sheet 1C. A housing space 2 is formed with the portion 5, and an opening 6 h is formed above the housing space 2. In addition, a linear cut 4n serving as a starting point at the time of opening is formed on the left and right peripheral edges above the trunk seal portion 4. The shape of the cut 4n is not limited to a linear shape, and may be a V shape, a U shape, or the like.

  The accommodation space 2 is filled with the food F through the opening 6h, and as shown in FIG. 1B, the front sheet 1A and the back sheet 1B are heat-sealed at the upper end to form the top seal part 6. When processing such as retort heating is performed as necessary, a packaged food 201 for heating a microwave oven is obtained, which is hermetically packaged in a state where the food F is stored in the storage space 2. The use of the packaging bag 101 is not limited to retort use. Depending on the specific sterilization treatment, distribution mode, etc., for boil sterilization at a lower temperature (100 ° C or less) than for retort, for hot packs that sterilize the inner surface of the packaging bag only by increasing the contents, distribute without heat treatment Applications include refrigeration and the like.

  When eating the food F, the packaged food 201 is set in a microwave oven in a stand state and heated. And when the heating in a microwave oven is complete | finished, the upper part of the packaging bag 101 will be cut | disconnected from the cut 4n, the packaged food 201 will be opened, and the food F in the storage space 2 will be moved to tableware. In addition, regarding MD direction (Machine Direction: flow direction of the film) and TD direction (Transverse Direction: width direction of the film) in FIG. 1, the MD direction is the straight easy tearing direction (from the cut 4n) of the sheets 1A and 1B. It is set so as to coincide with the breaking direction.

  The packaging bag 101 is an internal pressure unsealing type pouch provided with a vapor venting mechanism 3 for escaping the vapor V in the accommodation space 2 during microwave heating. The steam release mechanism 3 is located on the upper side of the packaging bag 101, and has a steaming hole formation scheduled part 3h as a steaming part that communicates with the housing space 2 by microwave heating. That is, in this steam release mechanism 3, the protruding seal portion 3 a connected to the trunk seal portion 4 is provided so as to protrude inside the packaging bag to form the steaming hole formation scheduled portion 3 h. Examples of other steam venting mechanisms 3 that can be used for the packaging bag 101 include a vent chamber that does not contain the contents (food F), a point seal portion that surrounds the vent chamber and isolates it from the containing space 2, and The thing provided with the hole or the notch | incision part formed in the front sheet | seat 1A and the back sheet | seat 1B inside the point seal | sticker part is mentioned.

  In the steam venting mechanism 3 of the packaging bag 101, the front sheet 1A and the rear sheet 1B are heat-sealed on both sides so that the protruding seal part 3a is connected to the trunk seal part 4 to form a U-shape. In the packaging bag 101, the heat seal between the projecting seal portion 3 a and the body seal portion 4 is performed simultaneously, and the width of the projecting seal portion 3 a is narrower than the width of the body seal portion 4.

  In the steam venting mechanism 3 of the packaging bag 101, a steam hole formation scheduled portion 3h is provided between the front sheet 1A and the back sheet 1B inside the projecting seal portion 3a. In this steam release mechanism 3, a steam hole formation scheduled part 3 h is formed by an unsealed part 4 a provided inside the protruding seal part 3 a, and the steam hole formation scheduled part 3 h is packaged from the trunk seal part 4. It is configured to open toward the side of the bag. In addition, you may form the steaming hole formation scheduled part 3h of the packaging bag 101 in a U shape by cutting off the unsealed part 4a of the packaging bag 101 from the front sheet 1A and the back sheet 1B.

  In the packaging bag 101, the unsealed part 4b is formed in the same height position as the steam hole formation scheduled part 3h in the trunk seal part 4 on the side where the steam release mechanism 3 is not provided. Thereby, in the manufacturing process of the packaging bag 101, when cutting between the packaging bags 101 adjacent to each other in the MD direction along the side seal part 4 extending in the vertical direction (TD direction), the cutting position is determined depending on the processing accuracy. Even in the case of misalignment, the steam hole formation scheduled portion 3h can be reliably formed.

  When the packaged food 201 is heated in a microwave oven and steam V is generated from the food F, the internal pressure of the accommodation space 2 increases. The protruding seal portion 3a of the steam release mechanism 3 is formed with a width that is most applied to the seal when the pouch swells and is narrower than the width of the trunk seal portion 4. Due to the internal pressure of 2, the protruding seal portion 3a is peeled off before the trunk seal portion 4. As a result, in the steam venting mechanism 3 of the packaging bag 101, the housing space 2 and the unsealed portion 4a communicate with each other, and high-pressure steam flows from the housing space 2 into the hole 3H, and from the hole 3H to the outside of the packaging bag 101. And exhausted. Since the steam release mechanism 3 is disposed in the upper part of the accommodation space 2, when the steam V is exhausted from the hole 3H, the leakage of the food F from the hole 3H is prevented.

  In the steam venting mechanism 3 of the packaging bag 101, as described above, the protruding seal portion 3a having a width smaller than that of the trunk seal portion 4 is provided so as to form the hole portion 3H that communicates with the outside. The steam release mechanism 3 that exhausts the steam V by allowing the storage space 2 to pass outside the packaging bag by the ascending can be easily realized.

  In FIG. 2, as a specific example of the three sheets 1A to 1C constituting the packaging bag 101 (FIG. 1), laminated films 1a, 1b, and 1c are shown in a laminated section. The laminated film 1a shown in FIG. 2 (A), the laminated film 1b shown in FIG. 2 (B), and the laminated film 1c shown in FIG. 2 (C) have the same configuration except that the arrangement of the printing layers 12 is different. ing. That is, in the laminated film composed of the base material layer 11, the intermediate layer 14, and the sealant layer 15, the printed layer 12 is formed on the base material layer 11 or the intermediate layer 14. The intermediate layer 14 may be omitted, and in the laminated film composed of two layers of the base material layer 11 and the sealant layer 15, the laminated film in which the printing layer 12 is formed on the base material layer 11 may be used as a sheet.

  The laminated film 1a (FIG. 2 (A)) includes a base material layer 11, a printing layer 12, an adhesive layer 13, an intermediate layer 14, an adhesive layer 13, and a sealant layer in order from the outer side of the packaging bag to the inner side of the packaging bag. 15. The laminated film 1b (FIG. 2B) includes a base material layer 11, an adhesive layer 13, a printed layer 12, an intermediate layer 14, an adhesive layer 13, and a sealant layer in order from the outer side of the packaging bag to the inner side of the packaging bag. 15. The laminated film 1c (FIG. 2C) includes a base material layer 11, an adhesive layer 13, an intermediate layer 14, a printed layer 12, an adhesive layer 13, and a sealant layer in order from the outer side of the packaging bag to the inner side of the packaging bag. 15.

  The base material layer 11 is made of a polyester film. Specific examples thereof include a polyethylene terephthalate (PET) film and a polybutylene terephthalate (PBT) film. 1-20 micrometers is preferable and, as for the thickness of the base material layer 11, 12-16 micrometers is still more preferable. If the thickness of the base material layer 11 is 1 μm or more, more excellent dimensional stability, heat resistance and the like can be obtained, and if it is 20 μm or less, more excellent bending resistance can be obtained. Moreover, even if it does not comprise the base material layer 11 with a special film (coextruded film etc.), cost reduction is attained by making it the single layer structure which consists only of a polyester-type film. Further, the base layer 11 may be formed by forming a biaxially stretched transparent vapor-deposited polyethylene terephthalate film having a thickness of about 12 μm in which the silica vapor-deposited layer functions as a barrier layer for preventing permeation of water vapor, oxygen and the like.

  The intermediate layer 14 is made of a polyamide film, and specific examples thereof include biaxially stretched nylon. By including a polyamide-based film in the laminated films 1a to 1c, it is possible to obtain excellent resistance to punctures received from the corners of other packaging bags during transportation, impacts transmitted to the packaging bags, and bending associated with the impacts. Is possible. Further, silica or the like may be deposited on a biaxially stretched nylon film having a thickness of about 15 μm to form the intermediate layer 14 to prevent permeation of water vapor, oxygen and the like.

  As described above, it is preferable to form a barrier layer for preventing permeation of water vapor, oxygen and the like on the base material layer 11 or the intermediate layer 14. The packaging bag 101 is a pouch suitable for filling the food F as a content. For this reason, in order to be able to preserve the food F while preventing the deterioration of the food F due to oxidation or the like (effect of extending the shelf life, etc.), it prevents the permeation of water vapor and the permeation of gas such as oxygen gas. It is preferable to form a barrier layer having an oxygen barrier property to prevent. Although a barrier layer will not be specifically limited if it is a layer which satisfy | fills said function, As the specific example, the transparent vapor deposition film formed by vapor-depositing an inorganic substance to the base material layer 11 or the intermediate | middle layer 14 is mentioned. By comprising a barrier layer with a vapor deposition film, the outstanding water vapor | steam barrier property and oxygen barrier property can be provided to laminated | multilayer film 1a-1c.

  As a method for depositing an inorganic substance on the base material layer 11 or the intermediate layer 14, a vacuum vapor deposition method (PVD method) for depositing an inorganic substance evaporated under reduced pressure, and a deposition gas containing an inorganic substance is irradiated with plasma under a reduced pressure. Examples thereof include a plasma chemical vapor deposition method (CVD method) in which the inorganic material is deposited on the base material layer 11 or the like. As the inorganic material to be deposited, for example, metal oxides such as silicon oxide (silica), aluminum oxide (alumina), and magnesium oxide can be used. For example, silica (chemical vapor deposition: CVD), alumina (physical vapor deposition: PVD), PVA (polyvinyl alcohol) -based barrier resin coating agent, or the like can be used as the transparent vapor deposition material of the transparent vapor deposition PET film.

  The printing layer 12 is made of ink whose laminate strength is reduced by heating in a microwave oven. Specific examples of such ink include high-density white ink, light-shielding ink, gold ink / silver ink, metallic ink using aluminum paste, pearl ink, and the like. The “high density” of the white ink referred to here indicates a state where the print density (OD value) of the printed material is 0.2 or more. High-density white ink and light-shielding ink have a high pigment content. In addition, metallic ink using an aluminum paste, such as gold / silver ink, is an aluminum-containing ink, and pearl ink is a mica-containing ink, so the particle size of the pigment is large. When the pigment content is high or the particle size of the pigment is large, the laminate strength is reduced by microwave heating as a result of the low binder content of the ink.

  The printing layer 12 is a printing method (gravure printing, offset printing, letterpress printing) using at least one of high density white ink, shading ink, gold ink / silver ink, metallic ink using aluminum paste, and pearl ink. Printing, screen printing, transfer printing, flexographic printing, etc.) by printing a desired printing pattern (characters, figures, symbols, patterns, etc.) on the back surface of the base material layer 11 or one surface of the intermediate layer 14 to obtain a desired thickness. (For example, 1 to 5 μm). These inks may contain one or more additives (plasticizers, stabilizers, antioxidants, light stabilizers, UV absorbers, curing agents, cross-linking agents, lubricants, antistatic agents as required. , Filler, etc.) are optionally added, and further, colorants such as dyes and pigments are added, and the mixture is sufficiently kneaded using a solvent, a diluent and the like.

  The adhesive layer 13 is formed of, for example, an adhesive generally used in a dry laminating method. Specific examples of adhesives include polyvinyl acetate adhesives, polyacrylate ester adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives, cellulose adhesives, polyester adhesives, polyamide adhesives Amino resin adhesives, epoxy adhesives, polyurethane adhesives, and the like. The thickness of the adhesive layer 13 is preferably 0.5 to 5 μm, and more preferably 0.5 to 2.5 μm. If the thickness of the adhesive layer is 0.5 μm or more, it is easy to control the film thickness, and if it is 5 μm or less, it is easy to suppress production costs while providing sufficient adhesive strength.

  The sealant layer 15 is a heat-fusible resin layer made of a heat-adhesive polypropylene film, and by laminating two laminated films 1a to 1c and heat-sealing the opposing sealant layers 15 at the periphery, It is provided for pasting and sealing. Therefore, when the bag is made, it is positioned most inside the packaging bag.

  Specific examples of the sealant layer 15 include a CPP layer made of an unstretched polypropylene (CPP) film. Since the CPP film is excellent in heat resistance, it can cope with a case where a food product that becomes high temperature by heating in a microwave oven is stored in the packaging bag 101. Further, the thickness of the sealant layer 15 is preferably 40 to 200 μm, and more preferably 50 to 80 μm. The sealant layer 15 having a thickness set in these ranges is excellent in impact resistance against dropping that may occur in the distribution process of the packaged food 201, and handling properties such as ease of filling the contents and ease of taking out the contents. Also excellent.

  As described above, the internal pressure opening type packaging bag 101 corresponding to the microwave heating is packaged in the accommodation space 2 for accommodating the contents (food F) by heat sealing of the laminated films 1a to 1c (sheets 1A to 1C). The bag is formed so as to be formed on the inner side of the bag, and has a structure in which a peelable projecting seal portion 3a for releasing the vapor V in the accommodation space 2 when the microwave oven is heated is formed. The laminated films 1a to 1c have a sealant layer 15 made of an unstretched polypropylene film on the inner side of the packaging bag, and printing made of ink whose laminate strength is lowered by heating in the microwave oven outside of the sealant layer 15 on the outer side of the packaging bag. It has a layer 12.

  Examples of the ink whose laminate strength is reduced by heating in a microwave oven include high-density white ink, light-shielding ink, gold ink / silver ink, metallic ink using aluminum paste, pearl ink, and the like. Since these ink types have a low binder content, the laminate strength in the printed layer is lowered during microwave heating. When at least one of these inks is used in the printing layer 12, the lamination strength in the printing layer 12 is reduced, and the printing layer 12 and the layer adjacent to the printing layer 12 (intermediate layer 14 or sealant layer 15) are depleted. Lamination occurs. Even if delamination occurs in the projecting seal portion 3a, the inside and outside of the packaging bag 101 are not connected, so that the discharge of the vapor V from the inside of the packaging bag to the outside of the packaging bag does not occur.

  When delamination occurs in the protruding seal portion 3a, the layer including the sealant layer 15 inside the packaging bag extends more than that and the peeling of the protruding seal portion 3a does not proceed. That is, smooth delamination of the protruding seal portion 3a is hindered by delamination. This is because the balance between the laminate strength and the seal strength cannot be achieved due to the relatively small decrease in the seal strength between the heat of the sealant layer 15.

  If smooth peeling does not occur at the protruding seal portion 3a as described above, it is difficult to discharge the vapor V from the inside of the packaging bag to the outside of the packaging bag, and the packaging bag 101 swells, and the trunk seal portion 4, the top seal portion 6 There is a risk that the bag breaks such that the vapor V leaks from the air. In addition, the packaging bag 101 swells even at a seal portion other than the projecting seal portion 3a, and delamination occurs at a wrinkle portion or the like generated by the sachet, resulting in deterioration of the appearance of the packaging bag 101.

  Even if the sealant layer 15 has a high seal strength in a high temperature environment, if the laminate strength is set high so that the laminate in the printing layer 12 is firmly held, the protruding seal portion 3a Peeling occurs. In other words, if the seal strength of the sealant layer 15 in a high temperature environment is low, peeling at the protruding seal portion 3a occurs even if the laminate strength of the printing layer 12 is low. Accordingly, the lower the seal strength of the sealant layer 15 in a high temperature environment, the easier the peeling of the protruding seal portion 3a is. Therefore, regardless of whether delamination has occurred, the vapor V from the protruding seal portion 3a. Discharge becomes easier. However, since the seal strength in the room temperature environment must be greater than or equal to a predetermined magnitude, the seal strength of the sealant layer 15 in the high temperature environment can be reduced while suppressing the decrease in the seal strength in the room temperature environment of the sealant layer 15. It needs to be lowered.

While maintaining the seal strength of the sealant layer 15 in a room temperature environment, the seal strength of the sealant layer 15 in a high temperature environment should be set low so that the protruding seal portion 3a is peeled off before delamination occurs. In this case, since delamination does not occur, an effect that the smooth peeling of the protruding seal portion 3a is not hindered can be obtained. The following conditional expression (1) regulates the balance between the laminate strength and the seal strength. That is, the unstretched polypropylene film constituting the sealant layer 15 is configured to satisfy the following conditional expression (1) in the projecting seal portion 3a.
(I1 / I2) × 100 ≦ 20 (%) (1)
However,
I1: Seal strength in a 100 ° C. environment (N / 15 mm),
I2: Seal strength at room temperature (N / 15mm),
It is.

  Conditional expression (1) indicates that the unstretched polypropylene film of the sealant layer 15 has physical properties (strength ratio of seal strength) that the seal strength in a 100 ° C. environment decreases to 20% or less of the seal strength in a room temperature environment. It is shown that. Note that the room temperature assumed here is 23 ° C., which corresponds to the general distribution process of the packaged food 201.

  FIG. 3 shows an outline of physical properties of an unstretched polypropylene film that satisfies the conditional expression (1). In FIG. 3, the solid line is the seal strength I1 in an environment of 100 ° C., the dotted line is the seal strength I2 in a room temperature (23 ° C.) environment, and the alternate long and short dash line is the strength ratio (I1 / I2) × 100. As can be seen from FIG. 3, the seal strengths I1 and I2 increase as the seal temperature increases, but the seal strength I1 in a high temperature environment is kept relatively low even when the seal temperature is high. When the seal strength I1 under such high temperature conditions is set low so as to satisfy the conditional expression (1), an ink (high density white ink or the like) whose laminate strength is lowered by microwave heating is laminated film 1a to Even in the case of 1c, since the projecting seal portion 3a is smoothly peeled before delamination between the films sandwiching the printing layer 12 occurs, the steam V is easily discharged through the inside and outside of the packaging bag 101.

  Therefore, as can be seen from FIG. 3, when the sealant layer 15 is composed of an unstretched polypropylene film having physical properties satisfying the conditional expression (1) with respect to the seal strengths I1 and I2, an ink whose laminate strength is lowered by microwave heating is laminated. While being used for the printed layer 12 of the film, it is possible to realize the packaging bag 101 and the packaged food 201 from which the internal heating steam is smoothly discharged.

The unstretched polypropylene film constituting the sealant layer 15 preferably satisfies the following conditional expression (1a) in the protruding seal portion 3a.
(I1 / I2) × 100 ≦ 13 (%) (1a)
The conditional expression (1a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (1). Therefore, preferably, by satisfying conditional expression (1a), the above-described operation becomes more reliable, and the above-described effect can be further increased. In FIG. 3, the strength ratio (I1 / I2) × 100 = 13 (%) at the seal temperature = 250 ° C. (I1 = 8.5 N / 15 mm, I2 = 65.5 N / 15 mm).

  As can be seen from FIG. 3, the lower the seal temperature, the lower the seal strengths I1 and I2. However, the degree of decrease in the seal strength I2 in the room temperature environment increases with the seal temperature of about 210 ° C. as a boundary. For example, the seal strength I2 obtained at a seal temperature of 195 ° C. is 50 N / 15 mm, and the seal strength I2 obtained at a seal temperature of 190 ° C. is 42 N / 15 mm. That is, a slight decrease in the seal temperature greatly reduces the seal strength I2 in a room temperature environment. Therefore, in order to ensure the seal strength I2 in a room temperature environment, it is necessary to raise the seal temperature to some extent.

From the above viewpoint, the unstretched polypropylene film constituting the sealant layer 15 preferably satisfies the following conditional expression (2) in the protruding seal portion 3a, and more preferably satisfies the following conditional expression (2a).
3 (%) ≦ (I1 / I2) × 100 (2)
5 (%) ≦ (I1 / I2) × 100 (2a)
In FIG. 3, the strength ratio (I1 / I2) × 100 = 3 (%) at seal temperature = 190 ° C. (I1 = 1.3 N / 15 mm, I2 = 42 N / 15 mm), and seal temperature = 195 The intensity ratio at 11 ° C. (I1 / I2) × 100 = 5 (%) (I1 = 2.5 N / 15 mm, I2 = 50 N / 15 mm).

  For the intermediate layer 14, a polyamide film such as nylon is often used. Therefore, when the printing layer 12 is laminated on the intermediate layer 14 as shown in FIGS. 2B and 2C, when printing is performed on the intermediate layer 14 made of nylon, the tension is applied to the intermediate layer 14 for drying. The printing pitch may become unstable due to the elongation of the intermediate layer 14. The same applies to the laminated film 1c. Therefore, as in the laminated film 1a shown in FIG. 2 (A), it is formed between the base material layer 11 formed so as to be adjacent to the outer side of the packaging bag of the printed layer 12, and the printed layer 12 and the sealant layer 15. It is preferable to have a laminated structure including the intermediate layer 14.

  Although the packaging bag 101 is a stand type, the structure of the steam release mechanism 3 and the laminated films 1a, 1b, and 1c described above is not limited to this type, and can be applied to other types of packaging bags. For example, in a flat pouch type packaging bag (for example, a three-side seal type packaging bag) or the like, the same effect can be obtained by using the steam release mechanism 3 or the laminated films 1a, 1b, and 1c.

Hereinafter, the packaging bag, packaged food, etc. which implemented this invention are demonstrated more concretely, giving an Example and a comparative example. From the outer side of the packaging bag to the inner side of the packaging bag, the base layer / printing layer (printing) / adhesive layer (DL) / intermediate layer is formed from the outer side of the packaging bag to the inner side of the packaging bag. It is shown below in the form of / adhesive layer (DL) / sealant layer. However, the position of the vapor deposition film of the base material layer is the surface on the printed layer side.
Example: Transparent vapor deposition PET12 / printing / DL / ONY15 / DL / CPP70 (A type)
Comparative example: Transparent vapor deposition PET12 / printing / DL / ONY15 / DL / CPP70 (B type)

Details of each layer in the schematic laminated structure are shown below.
Transparent vapor-deposited PET12 ... Transparent vapor-deposited polyethylene terephthalate (PET) film, thickness 12 μm, Dai Nippon Printing Co., Ltd. IBPET
ONY15: Biaxially stretched nylon, thickness 15μm, manufactured by Unitika Ltd. ONMB
CPP70: Unstretched polypropylene (CPP) film, thickness 70μm, A type and B type printing ... Printing ink: Silver ink, "Ramic SR120R silver" manufactured by Dainichi Seika Kogyo Co., Ltd.
DL: Adhesive: General dry laminate adhesive (ester), manufactured by Rock Paint Co., Ltd. Main agent RU-004 / Hardening agent H-1

  In the laminated film 1a of the example, an A-type CPP is laminated as a non-stretched polypropylene film to form a sealant layer 15, and in the laminated film 1a of a comparative example, a B-type CPP is laminated as a non-stretched polypropylene film. It was. The packaging bag 101 is a stand type (standing pouch shown in FIG. 1) having an outer size of 160 mm width × 147 mm height × 46 mm gusset width, and a protruding seal portion 3a for discharging steam is formed on one side upper portion of the trunk seal portion 4 (FIG. 1). The side seal bar temperature at the time of forming the projecting seal portion 3a and the trunk seal portion 4 was set in increments of 10 ° C between 210 ° C and 240 ° C.

  200 ml of water was sealed in the packaging bag 101 (bag making product) of the example and the comparative example, and a retort treatment at 120 ° C. for 30 minutes was performed. The seal strength of the protruding seal part 3a of the retort-treated product was measured under a room temperature (23 ° C.) environment and a 100 ° C. environment. At that time, a 15 mm wide section was collected from the protruding seal portion 3a to be measured, and the seal strength was measured under each environment using a tensile tester. Table 1 shows seal strengths I1, I2 [N / 15 mm] and strength ratio (I1 / I2) × 100 (%) at each seal temperature (° C.) as the measurement results. As can be seen from the measurement results in Table 1, in the example of the packaging bag 101, the seal strength under the environment of 100 ° C. decreased to about 10% of the seal strength under the room temperature environment.

  Next, a range test was performed. 200 ml of water is sealed in the packaging bag 101 (bag-making product) of the example and the comparative example, and heated until it is vaporized in a microwave oven (output 500 W), within 2 minutes from the appearance of the protruding seal part 3a and the start of the range heating. We confirmed the presence or absence of steaming. Table 1 shows the presence or absence of steaming within 2 minutes from the start of range heating.

  In the packaging bag 101 of the example, the protrusion seal part 3a was peeled off within 2 minutes from the start of the range heating, and no delamination occurred. On the other hand, in the packaging bag 101 of the comparative example, it took 2 minutes or more to vaporize by peeling off the protruding seal portion 3a, and delamination occurred in the protruding seal portion 3a. Because of this difference, even when ink having a laminate strength that decreases due to microwave heating is used for the printing layer 12, if the sealant layer 15 is composed of CPP films having different physical properties, vapor can be smoothly discharged before delamination occurs. I found it complete.

1a, 1b, 1c Laminated film 1A Front sheet (Laminated film)
1B Back sheet (laminated film)
1C Bottom sheet (laminated film)
2 Housing space 3 Vapor venting mechanism 3a Protruding seal part (seal part)
3h Steaming hole formation scheduled portion 3H Hole portion 4 Body seal portion 4a, 4b Unsealed portion 4n Cut 5 Bottom seal portion 6 Top seal portion 6h Opening portion 11 Base layer 12 Print layer 13 Adhesive layer 14 Intermediate layer 15 Sealant layer 101 Packaging bag 201 Packaged food F Food (contents)
V steam

Claims (7)

The laminated film is heat-sealed so that a storage space for storing contents is formed inside the packaging bag, and a peelable seal portion for releasing vapor in the storage space during microwave heating is provided. A formed microwave heating packaging bag,
The laminated film has a sealant layer made of an unstretched polypropylene film on the inner side of the packaging bag, and has a printing layer made of ink whose laminate strength is reduced by microwave heating on the outer side of the packaging bag than the sealant layer,
The unstretched polypropylene film satisfies the following conditional expression (1) in the seal portion;
(I1 / I2) × 100 ≦ 20 (%) (1)
However,
I1: Seal strength in a 100 ° C. environment (N / 15 mm),
I2: Seal strength at room temperature (N / 15mm),
It is.   The packaging bag according to claim 1, wherein the heat sealing is performed under a sealing temperature condition in a range that does not impair the properties and functions of the product at the time of bag making by a continuous bag making machine that manufactures an actual product.   The packaging according to claim 1 or 2, wherein the ink is at least one of metallic ink using aluminum paste, pearl ink, such as high-concentration white ink, light-shielding ink, gold ink and silver ink. bag.   The laminated film has a laminated structure including a base material layer formed so as to be adjacent to an outer side of the packaging bag of the printed layer, and an intermediate layer formed between the printed layer and the sealant layer. The packaging bag of any one of Claims 1-3 characterized by these. The packaging bag according to any one of claims 1 to 4, wherein the unstretched polypropylene film satisfies the following conditional expression (1a) in the seal portion;
(I1 / I2) × 100 ≦ 13 (%) (1a)
However,
I1: Seal strength in a 100 ° C. environment (N / 15 mm),
I2: Seal strength at room temperature (N / 15mm),
It is. The packaging bag according to any one of claims 1 to 5, wherein the unstretched polypropylene film satisfies the following conditional expression (2) in the seal portion;
3 (%) ≦ (I1 / I2) × 100 (2)
However,
I1: Seal strength in a 100 ° C. environment (N / 15 mm),
I2: Seal strength at room temperature (N / 15mm),
It is.   It is packaged food for microwave oven heating, Comprising: Food packaging is carried out by the packaging bag of any one of Claims 1-6 in the state accommodated in the said accommodation space as the said content. Characteristic packaged food.

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