JP7809543B2 - Heat treatment packaging - Google Patents

Description

The present invention relates to a package that heat-treats the contents.

Conventionally, packaged foods available on the market consist of cooked or semi-cooked food packed into heat-resistant plastic packaging, which is then heated in a microwave oven just before eating. However, when such packaged foods are heated in a microwave oven, the internal pressure increases due to the thermal expansion of the water vapor and air inside the packaging, which can cause the packaging to burst, scattering the contents and contaminating the microwave oven.

A method of preventing the package from bursting is to pierce a small hole in the package before cooking in a microwave oven to prevent the internal pressure from increasing. However, this method causes the generated steam to immediately escape the package, reducing the steaming effect and potentially drying out the food inside the package, resulting in a deterioration in taste. For this reason, packages with easy-peel sections are known that allow steam to pass through and release pressure when the internal pressure of the package increases.

Patent Document 1 describes a package for heat treatment in which the same sides of plastic films are abutted against each other and a first joint is formed that joins the films together in a gabled shape using a heat seal of a specified width, sealing the contents for heat treatment inside. The first joint is positioned to one side of the package, and is an easy-to-open seal that allows pressure to escape when the internal pressure of the package increases due to heating.

Patent Document 2 describes a packaging bag for use in a microwave oven, which is made of a composite film with at least one surface made of a sealant layer. The lower member has the sealant surface on the upper surface, and the sealant surfaces are placed face to face to form wing sections with at least the sides sealed. The upper member has the sealant surface on the lower surface, which are then overlapped and the periphery of the resulting bag sealed as a main seal. In this packaging bag for microwave ovens, a point seal section is formed in the central region of the wing section, connecting with the upper edge seal section or the folded section, and at least one vapor-permeable means is provided within this point seal section.

Patent Document 3 describes a package for heat-treating contents, which has a seam seal portion formed to protrude outward from the top of the package, and a steam-passing area formed in the center of the seam seal portion through which steam passes when the contents are heated and internal pressure increases. The steam-passing area has a first non-sealed area that opens to the exterior side of the package from the seam seal portion. The first non-sealed area has a first area with a constant opening width toward the interior of the package from the seam seal portion, and a second area formed contiguous with the first area and whose opening width gradually decreases toward the interior of the package, the opening width of the first area being 20 to 40 mm. One side of this package for heat treatment has a zipper seal portion, allowing consumers to insert contents such as food ingredients through the zipper seal portion and seal it.

Consumers can purchase these pre-packaged foods, which are sold with the contents already filled in the packaging, and simply heat them, making them extremely convenient.

Japanese Patent Application Publication No. 9-150864 Japanese Patent Application Laid-Open No. 2003-182779 Japanese Patent Application Laid-Open No. 2021-104813

The packages in Patent Documents 1 and 2 are designed with the assumption that the manufacturer will fill them with the contents and seal them, and consumers cannot fill the packages themselves. Some consumers want to reduce the burden of cooking but still want to make their own food, so the provision of a zip-lock seal (zipper) on the package has been considered, and packages such as those in Patent Document 3 are actually available commercially. However, it was necessary to prevent the zip-lock seal from opening first when the internal pressure increases, thereby reducing the steaming effect of the food.

The present invention aims to provide a heat-processing package that suppresses fluctuations in internal pressure due to water vapor and thermal expansion of the internal air, and prevents the zipper seal from opening when internal pressure increases, allowing for efficient heat processing of contents such as food ingredients.

The heat treatment package according to the present invention is a package for heat treating contents,
The bag includes a bag body made of a packaging film, a zipper seal part that seals the contents when the contents are placed inside the bag body, and a joint seal part that releases pressure when the internal pressure increases due to heat treatment of the contents,
the zipper seal portion has a male zipper and a female zipper joined to the bag body,
one of the male zipper and the female zipper has a non-bonded region that is not bonded to the bag body from an end of a contact surface that contacts the bag body on the bag body inner side toward an outside of the bag body,
On the front and back surfaces of the bag body, when viewed from a direction perpendicular to the front and back surfaces of the bag body, a fold is formed along an edge of the non-bonded region on the bag body inner side, or at a distance not exceeding 15 mm from the edge of the non-bonded region on the bag body inner side, the fold being approximately parallel to the zipper seal portion;
The fold is a valley fold on the side where the non-bonded region is formed.

This invention provides a heat-processing package that can efficiently heat-process contents such as food ingredients by suppressing fluctuations in internal pressure due to water vapor or thermal expansion of the internal air inside the package and preventing the zipper seal from opening when internal pressure increases.

1 is a schematic diagram showing an example of the configuration of a package for heat treatment according to the present invention. 2 is a schematic cross-sectional view showing an example of the configuration of the vicinity of the zipper seal portion of the package for heat treatment shown in FIG. 1. [0023]FIG. 2 is a schematic diagram showing the state of the zipper seal portion when the package for heat treatment shown in FIG. 1 is expanded. FIG.

One embodiment of a heat-treatment package according to the present invention will be described with reference to the drawings. The heat-treatment package according to the present invention is suitable for use when heat-treating contents in a microwave oven, and is also suitable for use when heat-treating food ingredients.

Figure 1 shows an example of the configuration of a heat treatment package according to the present invention. The heat treatment package 1 shown in Figure 1 is composed of a bag 2, a zipper seal 10 provided on one side of the bag 2, and a seam seal 20 that releases internal pressure when the contents are heated and the pressure increases. This configuration allows consumers to insert contents such as food ingredients through the zipper seal and seal the bag. The bag 2 is composed of, for example, two sheets of packaging film 22, and has a peripheral seal 5 where three sides of the two sheets of packaging film 22 are sealed.

Considering that the packaging film 22 will be heated in a microwave oven, it is preferable that it be made of a plastic material that is heat-resistant 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 polymethyl(meth)acrylate, polyethyl(meth)acrylate, and polybutyl(meth)acrylate; and copolymers of the monomers that form these. Note that "(meth)acrylic" refers to either methacrylic or acrylic.

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

The packaging film 22 may be a single layer, or may be laminated with two or more layers by co-extrusion or other methods. For example, the packaging film 22 preferably consists of a base layer and a sealant layer, and may further have other layers between the base layer and the sealant layer.

The base layer of the packaging film 22 can be made of, for example, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide, or polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate. The sealant layer can be made of, for example, polyolefins such as polyethylene and polypropylene. Furthermore, the intermediate layer provided between the base layer and the sealant layer can be made of, for example, the above-mentioned polyamides or polyesters.

If the packaging film 22 is made up of multiple layers, it is preferable that at least one of the layers be made of polyester, and more preferably polybutylene terephthalate. This makes it easier to achieve an appropriate hardness for the packaging bag film 22 while also improving the heat resistance of the packaging bag film 22.

The packaging film 22 may also be a gas-barrier composite film provided with a thin inorganic oxide film such as aluminum oxide or silicon oxide. This composite film can be obtained by heating and vaporizing aluminum oxide or silicon oxide alone or in a mixture under vacuum, and depositing the vapor onto the surface of the above-mentioned film. Furthermore, the packaging film 22 may also have an adhesive layer with gas-barrier properties, such as one based on polyepoxy resin, or a layer with gas-barrier properties, such as a polyvinyl alcohol-based polymer resin, cellulose, or urethane-based resin.

The heat treatment package 1 can take any shape as long as it can be sealed after the contents are placed inside. That is, the bag 2 can be three-sided sealed as shown in Figure 1, or it can be four-sided sealed, stick-shaped, pillow-shaped, gusseted, envelope-sealed, standing, or gable-sealed. The shape of the outer edge of the heat treatment package 1 can be polygonal (e.g., triangular, rectangular, pentagonal), circular, elliptical, or a combination of these, but is typically rectangular.

The seal width of the peripheral seal 5 formed on the sides and bottom of the heat treatment package 1 (bag 2) is preferably 3 to 15 mm, more preferably 5 to 12 mm, and even more preferably 7 to 10 mm. The peripheral seal 5 may be V-shaped, with the seal formed on the side sloping inward toward the bottom, or U-shaped, with the seal formed at the corners of the sides and bottom being rounded. A V- or U-shape effectively prevents the seal formed at the bottom from receding or slipping out when filling the heat treatment package 1 with contents such as foodstuffs. It also makes it less likely for the contents to remain in the corners of the sides and bottom, preventing the contents from burning when heated.

The peripheral seal portion 5 may be completely sealed at room temperature and at 90°C, but it may also be easy to open as long as it has a stronger seal strength than the zipper seal portion 10 and the gable seal portion 20. When the peripheral seal portion 5 is easy to open, its seal strength at room temperature and at 90°C is preferably 10 to 50 N/15 mm, and more preferably 12 to 45 N/15 mm. The seal strength at room temperature and at 90°C is measured at room temperature and at 90°C, respectively, in accordance with JIS Z0238, "Test Methods for Sealed Flexible Packaging Bags."

The zipper seal portion 10 has a male zipper 11 and a female zipper 12, an example of which is shown in Figure 2. The male zipper 11 and female zipper 12 are each joined to the bag body 2 (packaging film 22), and can be sealed (hermetically sealed) by fitting the convex portion of the male zipper 11 into the concave portion of the female zipper 12. There may be multiple male zippers and female zippers as long as they fit together.

In this embodiment, the male zipper 11 has a contact surface 13 that comes into contact with the bag body 2, and is heat-sealed at two locations on the inside of the bag body 2 (the lower side in Figure 1, the right side in Figure 2) and the outside of the bag body 2 (the upper side in Figure 1, the left side in Figure 2) to form a joint 15. It is also possible to form the joint 15 over the entire contact surface 13.

In contrast, the female zipper 12 has a heat-sealed joint 16 formed at only one location on the outer side of the bag 2 (upper side in Figure 1, left side in Figure 2) on the contact surface 14 that comes into contact with the bag 2. In other words, a non-bonded region 17 that is not bonded to the bag 2 is formed from the end of the contact surface 14 that comes into contact with the bag 2 on the inner side of the bag 2 (lower side in Figure 1, right side in Figure 2) toward the outside of the bag.

The bag body 2 has a fold 3 formed that is approximately parallel to the zipper seal portion 10. As shown in Figure 2, this fold 3 forms a valley fold on the side where the non-bonded region 17 is formed. With this configuration, when the heat treatment package 1 expands, internal pressure is concentrated at the bonded portion 16 on the side where the non-bonded region 17 is formed, as shown by the arrow in Figure 3. As a result, it is possible to prevent the expansion pressure from concentrating on the mating portion of the male zipper 11 and female zipper 12. Note that "approximately parallel" does not only mean that the two are completely parallel, but also includes cases where the purpose is achieved even if there is a slight tilt, for example, when one side is tilted relative to the other side at an angle of -10° to +10°.

When viewed from a direction perpendicular to the front and back surfaces of the bag body 2 (the front or back side in FIG. 1 , the top or bottom side in FIG. 2 ), the fold 3 is formed along the end 18 of the non-bonded region 17 on the inside side of the bag body 2 (D _F = 0 mm), or at a distance not exceeding 20 mm (D _F ≦ 20 mm) from the end 18 of the non-bonded region 17 on the inside side of the bag body 2. If the fold is too far from the end 18 of the non-bonded region 17 on the inside side of the bag body 2, the effect of forming the fold 3 is not easily achieved. Note that in FIGS. 1 to 3 , the fold 3 is formed at a distance not exceeding 20 mm from the end 18 of the non-bonded region 17 on the inside side of the bag body 2 in the direction opposite to the zipper seal portion 10, but conversely, the fold 3 may be formed at a distance not exceeding 20 mm from the end 18 of the non-bonded region 17 on the inside side of the bag body 2 in the direction of the zipper seal portion 10. However, since forming such a fold 3 makes the manufacturing process (particularly the process of forming the zipper seal portion 10) difficult, it is preferable that the fold 3 be formed at a distance of no more than 20 mm in the direction opposite the zipper seal portion 10 from the end 18 on the inside side of the bag body 2 of the non-bonded region 17.

Furthermore, in this embodiment, as shown in Figures 2 and 3, it is preferable that the size of the contact surface 14 of the female zipper 12 provided with the non-bonding region 17 that comes into contact with the bag body 2 is longer toward the interior of the bag body 2 (the lower side in Figure 1) than the size of the contact surface 13 of the male zipper 11 that comes into contact with the bag body 2. This more effectively prevents expansion pressure (internal pressure) from concentrating on the mating portion of the male zipper 11 and female zipper 12. Note that the contact surface 13 and the contact surface 14 may be the same size. Also, it is sufficient that the size of the contact surface 14 of the female zipper 12 provided with the non-bonding region 17 that comes into contact with the bag body 2 is longer, at least in part, toward the interior of the bag body 2 (the lower side in Figure 1) than the size of the contact surface 13 of the male zipper 11 that comes into contact with the bag body 2.

In the above explanation, the non-bonding region 17 is provided on the female chuck 12 side, but the non-bonding region 17 may also be provided on the male chuck 11 side.

In the present invention, one of the packaging films 22 constituting the bag 2 has a palm-seamed seal 20 formed by joining the inner surfaces of the films together with each other. This allows the pressure to escape through the palm-seamed seal 20 when the contents are heated and the internal pressure of the heat treatment package 1 increases. The palm-seamed seal 20 is formed so as to protrude outward from the top of the heat treatment package 1 (bag 2).

The palm-seamed seal portion 20 is formed so that it is positioned on the top surface of the contents when the contents are heated, and is formed to have easy-to-open properties that allow pressure to escape when the internal pressure of the heat treatment package 1 increases due to the heat treatment. The palm-seamed seal portion 20 can be formed by aligning the inner surfaces of the portions of the packaging film 22 that make up the palm-seamed seal portion 20 facing each other and sandwiching an easy-to-open film (not shown) between them as needed.

It is important that the seam seal portion 20 has weaker ease of opening in a 90°C atmosphere than the peripheral seal portion 5 and zipper seal portion 10. This allows the seam seal portion 20 to open before the peripheral seal portion 5 and zipper seal portion 10 open when the contents are heated and the internal pressure of the heat treatment package 1 increases, allowing the pressure to escape from the seam seal portion 20.

The heat seal strength of the palm-seamed seal portion 20 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 palm-seamed seal portion 20 in a 90°C atmosphere may be 0 N/15 mm, but is preferably 1 N/15 mm or more. The palm-seamed seal portion 20 may be completely sealed at room temperature, or may have easy-open properties. When the palm-seamed seal portion 20 has easy-open properties, the seal strength at room temperature is preferably 0.5 to 30 N/15 mm, and more preferably 1 to 25 N/15 mm.

The palm-seamed seal portion 20, which provides a complete seal at room temperature and a heat seal strength of 12 N/15 mm or less in a 90°C atmosphere, can be achieved by using a polyolefin (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 a blend of these resins as the easy-to-open film. The melting point is measured in accordance with ASTM 2117.

In the present invention, as shown in Figure 1, it is preferable to form a steam-passing area 21 in the center of the grommet seal 20, through which steam passes when the contents are heated and the internal pressure increases. This results in a heat-treatment package 1 that allows pressure to escape and prevents bursting even when the internal pressure increases.

Furthermore, as shown in FIG. 1, the hem seal portion 20 is preferably formed approximately parallel to one side of the package for heat treatment 1, and the zipper seal portion 10 is preferably formed approximately parallel between the hem seal portion 20 and one side of the package for heat treatment 1. The distance H (see FIG. 1, the length of the package for heat treatment 1) from one side of the package for heat treatment 1 on which the zipper seal portion 10 and the hem seal portion 20 are formed in parallel to the opposite side is preferably 100 to 500 mm, more preferably 125 to 400 mm, and even more preferably 150 to 300 mm.

The distance _HP (see FIG. 1) between one side of the package for heat treatment 1 and the hand-seamed seal portion 20 is preferably 10 to 60%, more preferably 25 to 50%, and even more preferably 30 to 40% of the distance H from one side to the opposite side of the package for heat treatment 1. Within this range, the burst strength of the package for heat treatment 1 is low, and steam can easily pass through even with a weak force.

The distance H _J (see Figure 1) between one side of the package for heat treatment 1 and the zipper seal portion 10 is preferably 10 to 80% of the distance H _P between one side of the package for heat treatment 1 and the hem seal portion 20, more preferably 20 to 60%, and even more preferably 40 to 50%.

With this type of heat-treatment package 1, consumers can fill the contents, such as food ingredients, through the zipper seal portion 10 and seal it. The sealed contents can then be efficiently heated in a microwave oven or similar device. Furthermore, the inclusion of the grommet seal portion 20 can suppress fluctuations in the pressure inside the package due to water vapor inside the package or thermal expansion of the internal air. Furthermore, by configuring the zipper seal portion 10 as described above and forming the specified fold 3, it is possible to effectively prevent the zipper seal portion 10 from opening when the internal pressure increases.

After the heat treatment is complete, the consumer can remove the contents by, for example, opening the hem seal 20. The opening may be at the zipper seal 10, or by tearing the heat treatment package 1 from the peripheral seal 5. A tear notch may be formed in the peripheral seal 5 to make the heat treatment package 1 easier to tear.

The above describes a preferred embodiment of the heat treatment packaging of the present invention, but the present invention is not limited to this.

Example 1
A heat treatment package (235 mm long x 200 mm wide) having the configuration shown in FIG. 1 was produced. The package film used was composed of polyethylene terephthalate (PET #12) / nylon (Ny #15) / unstretched polypropylene (CPP #50). The palm-seamed seal was formed by inserting and heat-sealing a PP-based easy-open tape (H _p = 80 mm, H _J = 40 mm). As shown in FIG. 2, the size of the contact surface 14 of the female zipper 12 with the bag body 2 on the back side (the side on which the palm-seamed seal is not formed) in FIG. 1 is longer toward the inside of the bag body 2 than the contact surface 13 of the opposing male zipper 11 with the bag body 2, and a non-bonded region 17 was formed on the contact surface 14 side. Then, a fold 3 was formed in the bag body 2 along the end 18 of the non-bonded region 17 on the inner side of the bag body 2 (D _F =0 mm), parallel to the zipper seal portion 10, with a valley fold on the side where the non-bonded region 17 was formed (the back side in Figure 1).

Example 2
A heat treatment package was prepared in the same manner as in Example 1, except that the fold 3 was formed at a position 5 mm away from the end of the non-bonded region 17 on the inner side of the bag body 2 (D _F = 5 mm).

Example 3
A heat treatment package was produced in the same manner as in Example 1, except that the fold 3 was formed at a position 10 mm away from the end of the non-bonded region 17 on the inner side of the bag body 2 (D _F = 10 mm).

Example 4
A heat treatment package was produced in the same manner as in Example 1, except that the fold 3 was formed at a position 15 mm away from the end of the non-bonded region 17 on the inner side of the bag body 2 (D _F = 15 mm).

<Comparative Example 1>
A package for heat treatment was produced in the same manner as in Example 1, except that the fold 3 was not formed.

<Comparative Example 2>
A heat treatment package was produced in the same manner as in Example 1, except that the fold 3 was formed at a position 30 mm away from the end of the non-bonded region 17 on the inner side of the bag body 2 (D _F = 30 mm).

<Rating 1>
Meat (250 g) and seasoning liquid (50 g) were placed into the zipper seal side of the heat treatment packages obtained in Example 1 and Comparative Example 1, and 85 samples of each were closed with the zipper seal. These samples were heated in a microwave oven and the presence or absence of openings in the zipper seal of each heat treatment package was examined. The results are shown in Table 1.

In Comparative Example 1, where no folds 3 were formed, the zipper seal 10 opened in one sample. In contrast, in Example 1, where the specified folds 3 were formed, steam passed through the steam passage area 21 of the joint seal portion 20 in all samples, and the zipper seal 10 did not open.

<Rating 2>
100 ml of water was poured into the zipper seal side of the heat treatment packages obtained in Examples 1 to 4 and Comparative Examples 1 and 2, and samples with the zipper seals closed (100 samples for Example 1 and Comparative Example 1, and 10 samples for Examples 2 to 4 and Comparative Example 2) were prepared and heated in a microwave oven, and the presence or absence of openings in the zipper seal of each heat treatment package was examined. The results are shown in Table 2.

In Comparative Example 1, where no folds 3 were formed, the zipper seals 10 opened in more than half (57 samples). This shows that the conditions in Evaluation 2 were more severe than those in Evaluation 1. Nevertheless, in Example 1, where the specified folds 3 were formed, steam passed through the steam passage area 21 of the joint seal portion 20 in all samples, and the zipper seals 10 did not open.

In Example 2, where the fold 3 was formed 5 mm from the edge of the non-bonded region 17 on the inside of the bag body 2, steam passed through the steam passage region 21 of the grommet seal portion 20 in all samples, and the zipper seal 10 did not open. As the fold 3 was formed farther away from the edge of the non-bonded region 17 on the inside of the bag body 2, some samples had openings in the zipper seal 10. However, when the distance was 20 mm or less (Examples 1 to 4), the non-opening rate was higher than in Comparative Example 1, demonstrating the effectiveness of forming the fold 3. However, in Comparative Example 2, where the fold 3 was formed 30 mm from the edge of the non-bonded region 17 on the inside of the bag body 2, the zipper seal 10 opened at a rate roughly equivalent to that of Comparative Example 1, where no fold 3 was formed.

REFERENCE SIGNS LIST 1 Heat treatment packaging body 2 Bag body 3 Fold 5 Peripheral seal portion 10 Zipper seal portion 11 Male zipper 12 Female zipper 13 Contact surface 14 Contact surface 15 Joint portion 16 Joint portion 17 Non-jointed region 18 End 20 Sealed joint portion 21 Steam passage region 22 Packaging film

Claims (4)

A package for heat-treating contents,
The bag includes a bag body made of a packaging film, a zipper seal part that seals the contents when the contents are placed inside the bag body, and a joint seal part that releases pressure when the internal pressure increases due to heat treatment of the contents,
the zipper seal portion has a male zipper and a female zipper joined to the bag body,
one of the male zipper and the female zipper has a non-bonded region that is not bonded to the bag body from an end of a contact surface that contacts the bag body on the bag body inner side toward an outside of the bag body,
On the front and back surfaces of the bag body, when viewed from a direction perpendicular to the front and back surfaces of the bag body, a fold is formed along an edge of the non-bonded region on the bag body inner side, or at a distance not exceeding 15 mm from the edge of the non-bonded region on the bag body inner side, the fold being approximately parallel to the zipper seal portion;
The fold is a valley fold on the side where the non-bonded region is formed. 2. The heat treatment package according to claim 1, wherein the size of each contact surface of the male zipper and the female zipper that contacts the bag body is such that the contact surface where the non-bonded region is provided is longer toward the inside of the bag body. The joint seal portion is formed so as to protrude outward from above the bag body,
3. The package for heat treatment according to claim 1, wherein a steam-passing area is formed in the center of the seam-seated portion, through which steam passes when the contents are heated and internal pressure increases. The packaging film is composed of a plurality of layers,
4. The package for heat treatment according to claim 1, wherein at least one of the plurality of layers is made of polybutylene terephthalate.