JP3339559B2 - Food packaging for microwave oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a food package for a microwave oven. More specifically, the present invention can selectively release the water vapor to the outside when the water vapor pressure generated in the package reaches a certain value when heated in a microwave oven, thereby preventing the entire package from bursting. In addition, the present invention relates to a food package for a microwave oven in which the package expands so as to become self-supporting as the internal pressure of the package increases and the lower portion forms a ship bottom type (container shape).

[0002]

2. Description of the Related Art When a food is heated using a microwave oven with food placed in a sealed package, the contents are warmed and water vapor is generated, the package sealed with the food expands, and finally the package is ruptured. Contents may be scattered. Various proposals have been made to prevent the rupture of the package by such water vapor. For example, when a small hole is made in the package and stored, the hole is closed with a sealing member, and when heating with a microwave oven, the seal is peeled off and the steam generated by heating is removed from this hole. There is a method of releasing, a method of forming a special shape of the package so that the tensile stress due to the internal water vapor pressure is concentrated at a predetermined location (for example, JP-A-8-119343, JP-A-7-257662, JP-A-2-84908, JP-A-6-84908
No. 3,131,926, JP-A-63-218079 and JP-A-3-60239.

[0003] However, in these methods, it is necessary to make a hole in a package that originally requires hermeticity, and the airtightness of the container may be impaired. In addition, a package having a special shape is manufactured. And a special heat sealing device for concentrating the internal water vapor pressure at a predetermined location. In addition, as shown in FIG.
Although it is conceivable to provide the pressure-reducing portion 55 in 4, when the packaged object 60 contains a large amount of liquid, when the pressure-reducing portion 55 is opened by the pressurization by heating and the pressure is reduced, the packaged material 60 is formed. The liquid leaks out of the package.

Further, as shown in FIG. 10, there is also known a package (back-attached bag or double-sided bag) in which a heat seal portion 53 is formed at the center of the back surface. It is also conceivable to provide a pressure-reducing portion 55 in the heat seal portion 53 to be provided. As described above, the package having the pressure-reducing portion 55 formed in the heat-seal portion 53 in the center of the back surface has an increased internal pressure and expands, and then the heat-seal portion formed in the center of the back portion has an opening. Then, since the internal pressure is rapidly reduced, the expanded package is crushed.
Therefore, a food 60 having a large amount of liquid can be obtained by using such a package.
Even after packaging, the outflow of the liquid from the opening cannot be prevented.

[0005]

An object of the present invention is to provide a food package for a microwave oven in which water vapor generated when food is heated using a microwave oven is extracted from a predetermined heat sealing portion by a water vapor pressure in a container. It is intended to provide.
More specifically, the present invention relates to a food package in which water vapor is automatically discharged from a predetermined heat seal portion so that the container is not ruptured by water vapor generated inside the container when heated using a microwave oven. Another object of the present invention is to provide a food package for a microwave oven that can be easily manufactured without using a special device or the like.

[0006] The present invention also relates to an oden, a Japanese radish,
For seasoned cooked foods that contain a lot of raw or raw fish soup or boiled juice, the pressure can be released without leaking the boiled juice, and it can be easily opened without leaking liquid when opening after microwave oven heating. It is an object of the present invention to provide a food package for a microwave oven in which a body can be used like a tray.

[0007]

SUMMARY OF THE INVENTION A package for a microwave oven according to the present invention has one end seal portion (top heat seal portion), the other end seal portion (bottom end heat seal portion) and a back heat seal portion. N is the length from the virtual center line to the edge on the left and right of the virtual center line imagined at the center of the back part, and m is the length from the virtual center line to the back heat seal part.
In this case, two rear heat seal portions are provided substantially parallel to the virtual center line so that the value of m / n is in the range of 1/20 to 19/20. In the vicinity of the center in the length direction of the portion, 1/4 to 3/3 of the heat seal width from the outer edge of the back heat seal portion toward the inside.
It has a non-seal portion having a width of 4 and the heat-seal portion on the back surface is configured to be depressurized.

[0008] In the packaging bag for a microwave oven of the present invention, it is preferable that both end seal portions are strong heat seal portions and the rear heat seal portion is a weak heat seal portion.
As described above, the food package of the present invention is a so-called back-attached bag or a double-sided bag, but is provided with two back heat-seal portions on the back except for a virtual center line imagined at the center of the back. Therefore, when the internal pressure is increased by heating in a microwave oven, the rear heat seal portion rises and expands, and the raised rear heat seal portion acts like a keel to release the internal pressure of the food package. Even when it comes out of the mouth, the food package of the present invention maintains an expanded form. That is, the food package of the present invention expands by heating in a microwave oven to have a boat-like shape, and maintains this boat-like shape even when the pressure-reducing port is opened and the internal pressure decreases. Is done.
Therefore, by using the food package of the present invention, even a food with a large amount of liquid can be heated in a microwave oven without causing juice leakage.

When the food package for a microwave oven of the present invention is heated in a microwave oven, the food is heated with its back face up. Therefore, in the present invention, the back surface means the opposite side of the surface of the bag for the sake of convenience, and it goes without saying that the back surface may be the front surface.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Next, the food package for a microwave oven according to the present invention will be described in detail. FIG. 2 is a diagram schematically illustrating an example of a food package for a microwave oven according to the present invention. FIG. 1 is a reference diagram schematically showing a packaging bag provided with one back heat seal portion.

As shown in FIG. 2, the food package 1 for a microwave oven according to the present invention has one end seal portion (in the present invention, it may be referred to as "upper heat seal portion" for convenience).
1, a heat-sealing portion 12 (also referred to as a “bottom-end heat-sealing portion” for convenience in the present invention) and rear heat-sealing portions 13a and 13b. In addition, before encapsulating food, either the upper end heat seal part 11 or the bottom end heat seal part 12, usually the upper end heat seal part 11 is open. The upper end heat seal portion is a portion to be heat sealed, and is not heat sealed.

The food package for a microwave oven according to the present invention has
The back heat seal part of the book is formed, and FIG.
An aspect in which two rear heat seal portions 13a and 13b are formed is shown. FIG. 1, which is a reference drawing, shows a package in which one back heat seal portion 13a is formed. The back heat seal portions 13a and 13b are formed not at the center line 10 imagined on the back surface of the food package of the present invention, but at positions shifted from the imaginary center line 10 toward the edges 14a and 14b. I have. By forming the rear heat seal portions 13a, 13b so as to be shifted toward the edges 14a, 14b from the imaginary center line 10, the food package of the present invention stands up when expanded, as shown in FIG. A substantially triangular shape 1 is formed by the back heat seal portions 13a, 13b and the edges 14a, 14b.
5, 15 are formed, and even after depressurization, the raised rear heat seal portions 13a, 13b act like a keel on the bottom of the ship, and the shape of the substantially triangular portions 15, 15 is maintained. The expanded form of the food package of the present invention is maintained even after depressurization. Therefore, the rear heat seal portion 13
Even if the non-seal portions 16a and 16b (heated to be pressure-reducing ports) formed on the a and 13b are opened due to an increase in internal pressure due to heating, the shape of the food package is maintained in an expanded state. Therefore, it is difficult for juice to leak from the opened pressure-reducing port.

In the food package 1 of the present invention, the rear heat seal portions 13a and 13b are not located on the virtual center line 10, but are provided on the edges 14a and 14b side of the virtual center line. Edges 14a, 14b from this virtual center line 10
If the length from the virtual center line 10 to the rear heat seal portions 13a and 13b is m,
Usually, the rear heat seal portions 13a and 13b are provided so that the value of m / n is in the range of 1/20 to 19/20, and preferably provided in the range of 5/20 to 17/20. Further, it is particularly preferable to provide the back heat seal portions 13a and 13b so as to be 8/20 to 14/20.
By providing the rear heat seal portions 13a and 13b at such positions, the food package of the present invention can easily maintain its expanded state even when the pressure-reducing port is opened. In the case where the rear heat seal portion 13a and the rear heat seal portion 13b are provided as shown in FIG. 2, the value of m / n that defines the attachment position of the rear heat seal portion 13a and the rear heat seal portion 13b is the same. May be different.

The back heat seal portions 13a and 13b are
When the internal pressure is increased by the heating, the internal pressure is opened to reduce the internal pressure of the package. More specifically, non-seal portions 16a and 16b are formed in the rear heat seal portions 13a and 13b in the vicinity of the longitudinal center of each heat seal portion. Then, the non-seal portions 16a and 16b open to reduce the internal pressure.

The shapes of the non-seal portions 16a and 16b can be various shapes, for example, as shown in FIGS. 4, 5 and 6 (a) to (e). FIG. 4 and FIG. 5 show the rear heat-sealing portion of the rectangular package body on which the mountain-shaped non-sealing portions 16a and 16b are formed. The width D1 of the back heat seal portions 13a, 13b is usually 0.5 to 2.0 cm, preferably 0.8 to 1.0 cm, and the width D ₁ of the non-seal portions 16a, 16b in the present invention. ₂ or D ₃ is towards the inside direction from the outer edge of the rear heat-sealed portion the heat seal width D ₁ of the 1 / 4-3 / 4 of the width, so that preferably is the width of 1/3 to 2/3 Is formed. In FIG. 4, the width D ₂ of the non-seal portion 15 is
Rear heat-sealed portion 13a, and aspects are shown is 3/4 of the width D ₁ of the 13b, the non-sealing portion 16a, 16b width D of
₃ is _１ ／ of the width D ₁ of the rear heat seal portions 13a and 13b.
Is shown. By setting the width of the non-seal portions 16a and 16b within the above-mentioned range with respect to the width of the back heat seal portions 13a and 13b, the food, which is the content during storage, does not leak, and the microwave is used. The back heat seal portions 16a and 16b are peeled off by the internal pressure due to the water vapor generated in the container due to the heating, so that a pressure relief port can be reliably formed between the back seal portions 16a and 16b and the non-seal portions 16a and 16b.

Further, the non-sealing portion 16a, 16b includes a rear heat-sealed portion 13a, longer than the non-sealing length L ₁ is the length of the non-sealing portion of the inside 2 of the food package 1 of the outer edge portion of 13b (broadly It is preferable that the tips of the non-seal portions 16a and 16b in the container direction are formed in a V-shape or a wedge shape at a predetermined angle. That is, for example, the angle of the tip is seen for the non-sealing portion 16a-1 which is a theta _1, non-sealing portion 16a-1 of the wedge is the L ₂ length of the outer edge portion, and the L ₂ and base , The shape of an isosceles triangle whose vertex angle is θ ₁ . In addition, for example, regarding the non-seal portions 16b-1 and 16c-1 whose tip angles are θ ₂ and θ ₂ , respectively, the wedge-shaped non-seal portions 16b-1 and 16c-1 as a whole are , The lengths of the outer edges are L ₃ and L ₄ , respectively, and these L ₃ and L ₄ are bases,
It has a triangular shape whose vertices are at angles θ ₂ and θ ₃ . The numbers 16a-1, 16b-1 and 16c-1
Non-sealing portion 16a but in complex, 16b are length L ₁ of the outer edge portion, the non-sealing portion 16a, the length L ₁ of 16b is
The length of the heat seal portion 19 becomes shorter toward the inside 2 of the food package 1. Further, the tip portions 16a-1, 16b-1, of the non-seal portions 16a, 16b,
16c-1 are formed at angles of θ ₁ , θ ₂ , and θ ₃ , respectively. Here, the non-seal portion 16 represented by θ ₁ , θ ₂ , θ ₃
The angle of the tip of a, 16b is usually 10 to 160 degrees, preferably 45 to 140 degrees, particularly preferably 60 to 1 degrees.
20 degrees. By forming the tips of the non-seal portions 16a and 16b at the above-described angles in this manner, when the back heat seal portions 13a and 13b are separated from the inside 2 of the food package 1 due to the steam pressure in the container, Non-seal part 1
The size of the pressure-reducing port formed between 6a and 16b becomes the minimum required size, so that the contents do not leak and the water vapor generated in the inside 2 of the food package 1 is efficiently released. be able to.

As shown in FIG. 2, the non-seal portions 16a and 16b are preferably provided near the center in the longitudinal direction of the back heat seal portions 13a and 13b. This is because the pressure due to the water vapor generated in the inside 2 of the food package 1 tends to concentrate on this portion. The non-seal portions 16a, 16a
The ratio between the length of b and the lengths of the back heat-seal portions 13a and 13b can be set arbitrarily, but the length L _{1 of the} non-seal portions 16a and 16b is longer than the length of the back heat-seal portions 13a and 13b. It is preferably at least 5%. When the package of the present invention is opened using the non-seal portion as a release portion, the length is preferably a length that can be peeled off with a fingertip, specifically, 0.5 cm or more, more preferably 1 cm or more. Further, the non-seal portions 16a and 16b can be formed over the entire rear heat seal portions 16a and 16b.
It can also be formed on either the 3a or the back heat seal portion 13b.

As shown in FIG. 2, the food package 1 for a microwave oven according to the present invention, after the bottom heat seal portion 12 and the rear heat seal portions 13a and 13b are heat-sealed in advance and filled with food 3, The bag is deaerated as required, and the upper end heat seal portion 11 serving as a food filling port is heat-sealed and sealed. The heat seal portions 11, 12, 13a, 13b of the food package 1 for a microwave oven according to the present invention desirably have an easy-peeling property, and the rear heat seal portions 13a, 13a, in which the non-seal portions 16a, 16b are formed.
It is desirable that the sealing strength of 13b is lower than that of the other heat sealing portions 11 and 12. In the present invention,
Easy peel is a heat seal having a seal strength of 800 g / 15 mm or less.

The film capable of forming such an easy-peeling heat-sealed portion may be a single-layer film made of a polyolefin such as polyethylene or polypropylene.
-A multilayer film using a saponified vinyl acetate copolymer (EVOH) or the like is preferred. Examples of such multilayer films include PP / EVOH / PP, PP / KNy / EVA, PP
/ EVOH / Ny / PE, PP / Ny / EVOH / Ny
/ EVOH / ION, Ny / EVOH / LLDPE, N
y / EVOH / EVA, EVOH / Ny / PE, and the like. Where "PE" is polyethylene, "P"
“P” is polypropylene, “Ny” is nylon, “KN”
"y" is vinylidene chloride-coated nylon, and "ION" is an ionomer. The layer described on the right side in the configuration of the multilayer film exemplified above is a sealant layer.

In particular, in the present invention, a laminated film in which a surface base layer having heat resistance and barrier properties and a polyolefin-based sealant film having heat resistance and releasability are composited using an adhesive comprising a polyisocyanate compound is preferable. . In such a laminated film, since the polyolefin-based sealant film has an easy peel property, the heat seal surface can have an easy peel property.

It is necessary to use a film as described above to have an easy peel property and to form a portion having a high heat seal strength and a portion having a low heat seal strength. Generally, when heat-sealing the sides parallel to the flow direction of the film formed when manufacturing a heat-sealing film having easy peelability, the sides perpendicular to the flow direction of the film are heat-sealed. Comparing the heat seal strengths in the cases, the seal strength when the parallel sides are heat-sealed is higher.

[0022]

[Table 1]

Note) In Table 1 above, "TD" is the seal strength when heat-sealing in the direction parallel to the film flow, and "MD" is the seal strength when heat-sealing in the direction perpendicular to the film flow. The heat seal temperature is 150 ° C. The heat seal pressure is 2 kg / cm ^{2 The} heat seal time is 1 second The number of heat seals is one.

However, in this case, the heat sealing conditions (temperature, pressure, time, number of times) are the same. It is also possible to form the strength of the sealing strength by interposing an adhesive or ink. In this case, a method of changing the kind of the adhesive or the like may be adopted, but the method of applying the film to the sealing layer may be adopted. This increases the number of steps such as printing or printing.

In the present invention, by changing the heat sealing conditions (temperature, pressure, time, number of times), the back heat seal portion (parallel to the film flow), which originally has a strong heat seal strength, is made to have a weak heat seal strength. The upper and lower end heat seal portions having weak heat seal strength are defined as strong heat seal strength, and the difference in the strength is utilized.

[0026]

[Table 2]

Note) In Table 2 above, “TD” is the heat sealing strength when heat sealing is performed in the direction parallel to the film flow. The heat sealing conditions are as follows: heat sealing temperature = 150 ° C. heat sealing pressure = 2 kg / cm ² Heat sealing time = 1 second The number of heat sealing = 1 time, "MD" is the heat sealing strength when heat sealing in the direction perpendicular to the film flow, and the heat sealing conditions are as follows: Heat sealing temperature = 180 ° C Heat seal pressure = 3 kg / cm ² Heat seal time = 2 seconds The number of heat seals = 1.

When a rectangular bag is manufactured, the longer side of the rectangle has a smaller resistance to expansion than the shorter side of the rectangle, and the stress for peeling off the heat-sealed portion of the film becomes larger. The long (wide) rear heat-sealed part peels off first. Therefore, the water vapor pressure generated by heating using a microwave oven has the greatest effect on the center of the rear heat seal portion which forms a weak heat seal portion and has the same seal length as the long side of the bag. Will have an effect.

As shown in FIG. 2, in the food packaging bag 1, the flow direction of the film when the film forming the bag is manufactured is the direction indicated by the arrow 5, so that the back heat seal portions 13a and 13b The top heat seal portion 11 and the bottom heat seal portion 12 are parallel to the flow direction of the film, and are perpendicular to the flow direction of the film. The rear heat seal portions 13a and 13b are heat-sealed under the conditions of a temperature of 150 ° C., a pressure of 2 kg / cm ² , a time of 1 second, and a single operation.
Since the heat sealing was performed under the conditions of a temperature of 180 ° C., a pressure of 3 kg / cm ² , a time of 2 seconds, and a single operation, the heat sealing portion 11 was used.
12 has higher sealing strength.

Therefore, as shown in Table 1, in general, when heat-sealed under the same conditions, TD / TD
Shows a higher value of the sealing strength of MD / MD and a lower value of the sealing strength of MD / MD. However, as shown in Table 2, in the present invention, by changing the heat sealing conditions, the general heat sealing strength is reduced. By controlling and reversing the difference independently, an artificial seal strength difference of 120 g /
It uses 15mm to selectively remove water vapor.

Further, in the food packaging bag as shown in FIG. 2, the center of the weak heat seal portions 13a, 13b and the strong heat seal portions 11, 1 when the heat seal width is the same.
Table 3 shows an example of the seal strength (180 ° peel strength) of No. 2.

[0032]

[Table 3]

As is clear from the above table, in the microwave oven package of the present invention, the weak heat seal portions 13a, 13a,
The sealing strength of 13b is lower than the central portions of the strong heat sealing portions 11 and 12 at the bottom end and the top end. In the food package for a microwave oven according to the present invention, a portion that is not heat-sealed, that is, a non-sealed portion 1 is added to the weak heat-sealed portion as described above.
5 are formed.

When the microwave oven package 1 of the present invention in which the food 20 is filled in the interior 2 is heated, the steam pressure generated in the interior 2 is changed from the interior 2 of the food package to the heat seal portions 11, 12, and 13a. , 13b, but the heat seal portions 11 and 12 are strong heat seal portions, and the strong heat seal portions 11 and 12 are not peeled off.
As shown in FIG. 5 (a), steam pressure is applied to the rear heat seal portions 13 a and 13 b from the inside 2 of the package 1, and the weak heat seal portions 13 a and 13 b are separated from the inside 2. FIG.
In the figure, reference numeral 21 denotes a weak heat seal portion peeled in an arc shape by the steam pressure. In other words, the sealed packaged food absorbs the microwave energy of the microwave oven to generate heat, and at the same time, the temperature of the food rises, the movement of water molecules contained in the food becomes intense, and at the same time, for the purpose of flavoring and the like. A part of the moisture of the cooking liquid is vaporized to become steam, and the internal pressure in the container is increased. When the water vapor pressure in the inside 2 further increases, the peeling 21 of the backside heat-sealed portion further deepens, and finally the top 1 of the non-sealed portion formed from the outer edges of the backside heat-sealed portions 13a, 13b toward the inside 2 direction.
6a-1, and as shown in FIG. 5 (b), a pressure-reducing port 23a is formed, from which the water vapor in the interior 2 is discharged. If the internal water vapor pressure is still high even when the water vapor is released from the pressure relief port 23a in this manner, the peeling of the back heat seal portion further proceeds, and the non-sealed portion vertex 16b-1 or 16c-1 which is shallower than the non-sealed portion 16a-1. , And a new pressure release port 23b is formed.

At the same time, as shown in FIG. 3, when the package expands, the film forming the package separates from the sealing surface in the width direction, and the heat seal portions 13a, 13a,
13b is lifted, and the back heat seal portion 13
a, 13b stand up. The rear heat-sealed portions 13a and 13b standing up in this manner act like keels in this package to form a triangle indicated by 15 in FIG. 3, and steam is released from the non-sealed portions 16a and 16b. Even after this, the shapes of the triangles 15, 15 are maintained by the raised rear heat seal portions 13a, 13b, so that even if the internal pressure is reduced, the package 1 of the present invention becomes independent like a molded container. Does not collapse.

By heating the food package of the present invention in a microwave oven with the back face up, the back heat seal portions 13a, 13b are erected, and then provided on the back heat seal portions 13a, 13b. Non-seal part 16a,
A pressure relief port is formed in 16b, and the steam generated inside is released. Although the internal pressure is reduced due to the release of water vapor from the pressure-reducing port in this manner, the rear heat seal portions 13a and 13b that have once risen continue to rise. The pressure relief ports are provided on the back heat seal portions 13a, 13a.
Since it is formed in b, no juice leaks from this decompression port. Also, even if you remove the film on the back part,
Since the food package of the present invention continues to form an expanded shape, that is, a boat shape even after heating, the food package from which the back surface portion has been removed functions as if it were a molded container. Therefore,
Even if the food contains a lot of liquid, it can be directly heated in a microwave without leaking juice, and after heating, the film on the back part can be removed and the package can be used as it is as a container. .

The food package for a microwave oven according to the present invention can be manufactured, for example, as shown in FIG. For example, the food package 1 for a microwave oven has a single film 30.
The heat sealing surface is located on the inside,
The rear end heat-sealed portion 13a is formed by bending the end portion around the sailor plate 32 and forming the back heat-sealed portion 13a by heat-pressing with a heat seal bar 33, and then heat-pressing the bottom end heat-sealed portion to form a. It can be manufactured by the following.

In the food package 1 for a microwave oven according to the present invention shown in FIG. 2, a single film 30 is formed in the same manner as described above so that the heat bonding surface is located on the inside and the rear heat seal portion 13a is formed. While bending the end, a bent portion is formed in the middle of the film 30 so as to form the rear heat seal portion 13b, and the rear heat seal portions 13a, 13b are formed using two heat seal bars 33a, 33b. After heat-pressing, the end 31 of the portion corresponding to the rear heat seal portion 13b is cut off, and then the bottom end heat seal portion is heat-pressed to be manufactured.

As shown in FIG. 8, the film 30 is folded into a sectional shape as shown in FIGS. 7A and 7B using a film former 35, and a heat seal bar 33 for the back surface is used. Then, the rear heat seal portion is heat sealed. In FIG. 7A, a rear heat seal bar 33 is used to heat seal the rear surface, and in FIG. 7B, a roller heat seal bar 33c is used. Non-heating portions are formed in the heat seal bars 33 and 33c, for example, by forming a mountain-shaped groove to form a non-heel portion. When the back heat seal bar 33 shown in FIG. 7A is used, if the feeding length of the film 30 is made longer than the length of the back heat seal bar 33, a portion that is not heat sealed on the back surface is formed. This portion can be used as a release portion, which is advantageous in that the operation becomes less complicated than when the release portion is formed using the roller heat seal bar 33c shown in FIG. 8B. When the back heat seal bar is heat-sealed with the back heat seal bar, a sailor plate is provided inside the folded film.

After the rear heat seal portion 13a is formed as described above, the bottom heat seal portion 12 is formed by heat sealing at right angles to the film flow direction with an end seal bar 36, and then the cutting blade 34 By cutting the film at right angles to the flow direction of the film, the package 1 of the present invention can be obtained. By forming a non-heated portion (or a non-pressed portion) having a shape corresponding to the shape of the non-seal portions 16a and 16b on the heat seal bar used here, the rear heat-seal portions 13a and 13b are formed.
The non-seal portions 16a and 16b can be formed on the second portion. The non-seal portions 16a and 16b can also function as release portions after heating.

FIG. 7 (a) shows an example of manufacturing a package in which the back heat seal portion is formed in one place. In the case where the back heat seal portion is formed in two places, FIG. The package of the present invention can be manufactured by folding the film as shown in FIG.

As described above, the rear heat seal portions 13a, 13
After forming the b and bottom end heat seal portions 12, filling foods and degassing as required, the upper end heat seal portions 11 are heat sealed. The food package for a microwave oven according to the present invention has the above-described configuration, but is further provided at any position of the rear heat seal portions 13a and 13b, preferably at the tip portion more than the upper end heat seal portion 11. It is preferable to provide a release portion 17 at the bottom.
The release portion 17 is usually provided on the rear heat seal portion 1.
It can be formed by not heat-sealing the front end portions of the upper heat-sealed portions of 3a and 13b. By providing the release portion 17 in this manner, the film 18 forming the back surface can be easily removed after heating by the microwave oven.

The above description relates to a square or rectangular bag-shaped package using one film. The food package of the present invention is, for example, as shown in FIG. It can also be manufactured using two films 30 and 34, and can be made into a polygon other than a quadrangle using two films. In this case, the edge 14
Heat seal a and / or 14b. Further, in the present invention, the surface on which the back heat seal portions 13a and 13b are not provided, that is, the area of the film forming the front surface can be made larger than the area of the film forming the back surface.

The food package for a microwave oven according to the present invention includes root products such as pilaf, white rice, hamburger, lunch, sweet potatoes and potatoes, marine products such as bamboo shoots and fried potatoes, pasty food products, and processed meat products such as eggs and sausages. It is used for packaging foods that are heated by a microwave oven, such as other cooked foods in general, and contains a lot of soups and broths, such as oden, Japanese radish, raw squid and raw fish, which were conventionally difficult to heat directly with a microwave. For seasoned cooked foods,
It can be heated directly using a microwave without leaking the broth. Further, the package of the present invention can be used as a package for foods other than foods, such as towels heated by using a microwave oven, hot compresses for medicine, and the like.

[0045]

According to the food package for microwave oven of the present invention, the back heat seal provided on the back of the package by the steam generated by filling and sealing the food etc. and heating the package together with the microwave. The upright portion raises the shape of the package into a boat shape, and water vapor can be selectively discharged from the non-seal portion provided in the upright rear heat seal portion. It can also be heated directly using a microwave oven.

Further, by appropriately increasing the internal pressure of the bag until the pressure-reducing port is formed, the same effect as that obtained by cooking under pressure (the core of the food can be heated) can be obtained. Moreover, the food is completely sealed before being microwave-heated in a microwave oven, so that the food can be hygienically maintained and stored.

Further, since the seal has been peeled off from the portion where the water vapor has been discharged from the unsealed portion by heating, the film can be peeled off from this portion, and this peeled off portion is formed on a conventional package. It has the same action as the release part.

[0048]

EXAMPLES Next, the food package for a microwave oven according to the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0049]

REFERENCE EXAMPLE 1 The food packaging bag shown in FIG. 1 was filled with seasoned raw (uncooked) (individual weight 170 g, liquid weight 100 g) and sealed. This food packaging bag is formed from one composite plastic film, and the packaging bag is formed with a bottom heat seal portion 12 and a back heat seal portion 13a having a non-seal portion 16a. After filling the food in the packaging bag, the upper end (food filling port) 11 was heat-sealed.

The heat sealing condition of 13a is as follows. Temperature = 150 ° C. Pressure = 2 kg / cm ² Hours = 1 second Number of times = 1 Heat seal width D ₁ = 10 mm Position where rear heat seal portion 13a is provided m / n = 14/20 Width D of high non-seal portion of mountain shape ₂ = 5 mm Width of the low unsealed portion of the chevron D ₃ = 3 mm Angle of the top of the high non-seal portion of the chevron θ ₁ = 130 degrees Angles of the top of the low non-sealed portion of the mountain shape θ ₂ , θ ₃ = 115 The heat sealing conditions for the upper and lower ends 11 and 12 are as follows.

Temperature = 180 ° C. Pressure = 2 kg / cm ² Time = 2 seconds Number of times = 1 Once, the seal strength of the rear heat seal portion 13a is 730 g.
The heat seal strength of the bottom heat seal part 12 and the top heat seal part 11, which are strong heat seal parts, is 850 g / 15 mm, and the difference between the two seal strengths is 1
It was 20 g / 15 mm.

This seasoned raw squid (uncooked) (initial temperature 2
C., 270 g of filling amount) is placed in a microwave oven (ER-240, manufactured by TOSHIBA Corp.) and microwave heating is started, and moisture in the contents is vaporized. In 40 to 60 seconds, steam was generated, the food packaging bag began to swell, and the rear heat seal portion 13a began to rise. 90 ~
After a lapse of 120 seconds, the temperature of the contents reaches 70 to 80 ° C., and the food packaging bag expands to tear off the non-seal portion 16a formed on the back heat seal portion 13a by the generated steam pressure. A force was generated in the bag, and as a result, the seal began to be peeled off from the vicinity of the center of the back heat seal portion 13a.

After 150 to 210 seconds after the heating, the peeling of the heat seal started near the center of the rear heat seal portion was caused by the peak of the mountain-shaped non-seal portion 16a formed at the center of the rear heat seal portion 13a. , A pressure-reducing port is formed, from which steam in the interior 2 of the food packaging bag 1 is discharged,
Interior 2 was stepped down. These pressure relief ports were formed at the three vertices of the mountain-shaped non-seal portion, and the pressure gradually decreased.

Even after the water vapor was discharged in this manner, the back heat seal portion 13a was kept upright, the whole package was deformed into a boat shape, and no leakage of the broth was observed.

[0055]

Example 1 Seasoned oden (cooked) (individual weight: 180 g, liquid weight: 100 g) was filled and sealed in the package shown in FIG. 2 and subjected to microwave heating in the same manner as in Reference Example 1.
This package has back heat seal portions 13a and 13
b is provided. The heat sealing conditions of 13a and 13b are as follows.

Temperature = 150 ° C. Pressure = 2 kg / cm ² Time = 1 second Number of times = 1 Heat seal width D ₁ = 8 mm Position where rear heat seal portion 13a is provided m / n = 12/20 Position where rear heat seal portion 13b is provided Position m / n = 12/20 Width D ₂ of the high non-sealed portion of the mountain shape D 5 = 5 mm Width D ₃ of the low non-sealed portion of the mountain shape = 5 mm Angle θ ₁ = 120 degrees of the top of the high non-sealed portion of the mountain shape The angle θ ₂ , θ ₃ = 100 degrees at the top of the lower non-sealed portion of the mountain shape is as follows.

Temperature = 180 ° C. Pressure = 3 kg / cm ² Time = 2 seconds Number of times = 1 Once the back heat seal portions 13a and 13b have a seal strength of 700 g / 15 mm, and the bottom end heat seal portion is a strong heat seal portion. The seal strength of the part 12 and the upper heat seal part 12 is 860 g / 15 mm, and the difference between the two seal strengths is 1
It was 60 g / 15 mm.

When microwave heating is started, the initial temperature becomes 3
The moisture in the contents at ℃ begins to evaporate, and after heating starts,
Water vapor is generated in 50 seconds, and the rear heat seal portions 13a, 1
3b has begun to stand. The temperature of the contents reached 70 to 80 ° C. 80 to 100 seconds after the start of heating, and the seal began to peel off from the vicinity of the center of the back heat seal portions 13a and 13b due to the generated steam pressure.

120 to 150 seconds after the heating, the peeling of the heat seal which started near the center of the rear heat-sealed portion was caused by the mountain-shaped unsealed portion formed at the center of the rear heat-sealed portions 13a and 13b. At the top, a pressure-reducing port was formed, from which steam in the interior 2 of the package 1 was discharged, and the pressure in the interior 2 was reduced. These pressure relief ports were formed at the three vertices of the mountain-shaped non-seal portion, and the pressure gradually decreased.

Even after the steam was discharged in this manner, the rear heat seal portions 13a and 13b remained in an upright state, the entire package was deformed into a boat shape, and no leakage of the broth occurred. Further, the film forming the back surface was peeled off from the release portion 17 formed at the tip of the upper heat seal portions of the back heat seal portions 13a and 13b. Could be used as container.

[Brief description of the drawings]

FIG. 1 is a reference diagram for explaining an example of a package of the present invention by showing an example of a food package for a microwave oven having one back heat seal portion.

FIG. 2 is an explanatory view showing an example of a food package for a microwave oven according to the present invention in which two back heat seal portions are formed.

FIG. 3 is a diagram schematically showing changes that occur when the food package for a microwave oven of the present invention is heated.

FIG. 4 is an explanatory diagram illustrating an example of a non-sealing portion.

FIG. 5 is an explanatory diagram showing a change in a state of a non-sealing portion according to a change in water vapor pressure.

FIG. 6 is a view showing an example of a shape of a non-sealed portion formed on the package of the present invention.

FIG. 7 is a diagram showing a production example of the package of the present invention.

FIG. 8 is a view showing a continuous production example of the package of the present invention.

FIG. 9 is a diagram in which a non-sealing portion is provided in a conventional package.

FIG. 10 is a diagram in which a non-sealing portion is provided in a conventional package.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Food package for microwave ovens 2 ... Inside of package 10 ... Virtual center line 11 ... One end seal part (upper end heat seal part) 12 ... The other end seal part ( 13a, 13b: Back heat seal portion 16a, 16b: Non-sealed portion 17: Release portion 20: Food 21: Peeling portion 30: Film (1) 31 ... cut-off part 32 ... sailor plate 33 ... heat seal bar 34 ... film (2)

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyasu Watanabe 14-6, Odenmacho, Nihonbashi, Chuo-ku, Tokyo Inside the East Cellophane Co., Ltd. (56) References JP-A-5-51013 (JP, A) Sho-62-105166 (JP, U) Sho-sho 60-169156 (JP, U) Sho-sho 56-107335 (JP, U) Sho-sho 59-147043 (JP, U) Sho-sho 6-15161 (JP) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65D 81/34 A47J 27/00

Claims (3)

(57) [Claims] 1. A package having one end seal portion, the other end seal portion, and a back heat seal portion, and a left and right edge of a virtual center line imagined at a center portion of a back portion of the package from the virtual center line. When the length from the virtual center line to the rear heat seal portion is m, the virtual center line is set such that the value of m / n falls within the range of 1/20 to 19/20. Two rear heat seal portions are provided substantially in parallel with each other. Near the center in the longitudinal direction of the rear heat seal portion, 1/1 of the heat seal width from the outer edge of the rear heat seal portion toward the inside. Having a non-seal portion with a width of 4 to 3/4,
A food package for a microwave oven, wherein the back heat seal portion is configured to be depressurized. 2. The food package for a microwave oven according to claim 1, wherein said both end seal portions are strong heat seal portions, and said rear heat seal portion is a weak heat seal portion. 3. The package for a microwave oven according to claim 1, wherein a release portion is provided at an end of said backside heat seal portion.