JP2009248970A - Package for microwave oven cooking - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package for microwave oven cooking which is capable of completely preventing a container from being deformed due to closure of an opened steam vent sealing part by a lid body by completely releasing the steam vent sealing part of the package for microwave oven cooking to the side part when the package for microwave oven cooking with the steam vent sealing part is cooked in a microwave oven. <P>SOLUTION: In the package for microwave oven cooking made by filling a content in a container body having a flange part made of a synthetic resin and heat-sealing the peripheral edge part of the lid body on the flange part to seal it, the steam vent sealing part is formed by providing a projecting part toward the inside direction of the container on the peripheral edge heat seal part, and the seal width t<SB>1</SB>of the peripheral edge seal part, the seal width t<SB>2</SB>of the side part of the projecting part and the seal width t<SB>3</SB>of the tip part of the projecting part satisfy formula (1) t<SB>3</SB>>t<SB>2</SB>and formula (2) t<SB>1</SB>≥t<SB>2</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a microwave oven cooking package in which a synthetic resin container body having a flange portion is filled with food such as cooked rice, and a lid body is heat-sealed and sealed to the flange portion.

  2. Description of the Related Art Various types of packaging for microwave oven cooking are known in which retort food, frozen food, and the like are stored in a synthetic resin sealed container and cooked in a microwave oven when eating. However, when these packages are heated in a microwave oven, the thermal expansion of water vapor generated from food stored in the container or air (hereinafter referred to as “water vapor”) present in the space (head space) in the container. As a result, the internal pressure of the package increases and the package may burst. As a result, food may be scattered, causing the inside of the microwave oven to be soiled or causing injury such as burns to the human body.

For this reason, before cooking such a package in a microwave oven, the package is partially opened in advance, or steam generated in the package is discharged outside by opening a hole in the package, A method for preventing the package from bursting is used. However, such a method is troublesome for general consumers. Moreover, since water vapor generated by microwave heating is immediately discharged out of the package, there is a disadvantage that the steaming effect of the food by the water vapor is reduced and the taste is lowered.
In order to eliminate such drawbacks, when a plastic resin container having a flange portion is filled with food, and the lid is heat sealed to the flange portion, the heat seal portion protrudes inward of the container. Various microwave oven packaging bodies in which protruding portions (steam vent seal portions) are formed have been proposed (see, for example, Patent Documents 1 and 2). In these microwave oven packaging bodies, when cooking with a microwave oven, the protrusions are automatically opened due to an increase in internal pressure in the container, thereby preventing the package from bursting.
JP-A-62-235080 JP-A-11-171261

  In the microwave oven cooking package described in these patent documents, the tip of the steam release seal portion protruding toward the inside of the container by cooking with a microwave oven is partially opened, the opening Cooking is completed when the thermally expanded water vapor or the like inside the container is released to the outside from the section. When the package after completion of cooking is taken out of the microwave oven, the volume of the thermally expanded water vapor shrinks as the temperature in the container decreases, and the pressure inside the container decreases. At that time, if the open steam release seal portion is closed by the lid, the inside of the sealed container is in a reduced pressure state, causing a problem that the container is deformed. When such deformation of the container occurs, the appearance deteriorates and the commercial value decreases, and it becomes difficult to take out the cooked food.

In order to eliminate the problem of container deformation in such a microwave cooking package, a means for preventing the container from being deformed by re-sealing the steam vent seal portion opened by cooking with a microwave oven by the lid. There has also been proposed a microwave oven packaging body provided with (see Patent Documents 3 and 4). However, in these microwave oven packaging bodies, the side portion of the steam vent seal portion (the seal portion facing inward from the peripheral seal portion) formed during cooking by the microwave oven remains without peeling. It has been difficult to completely prevent the lid from being closed and the container from being deformed.
JP 2000-62858 A JP 2001-315863 A

  Therefore, when the microwave oven cooking packaging body having a steam vent seal portion is cooked in a microwave oven, the steam vent seal portion of the microwave cooking packaging body is completely peeled to the side to open the present invention. An object of the present invention is to provide a microwave cooking packaging that can completely prevent the steam vent seal portion from being blocked by the lid and deforming the container.

In the present invention, the following configurations 1 to 5 are employed to solve the above-described problems.
1. A packaging body for microwave oven cooking in which a synthetic resin container body having a flange portion is filled with contents, and the peripheral edge portion of the lid is heat sealed to the flange portion, and the peripheral heat seal portion is placed inside the container. A steam vent seal portion is formed by providing a projecting portion directed in the direction, and the seal width t ₁ of the peripheral seal portion, the seal width t ₂ of the side portion of the projecting portion, and the seal width t ₃ of the tip portion of the projecting portion are A microwave cooking package characterized by satisfying the following formulas (1) and (2):
t ₃ > t ₂ (1)
t ₁ ≧ t ₂ (2)
2. _2. The microwave oven packaging for packaging according to 1, wherein the seal width t _{2 at} the side of the protrusion and the seal width t ₃ at the tip of the protrusion satisfy the following formula (3): :
_{t 2 / t 3 = 0.6~0.9 (} 3)
3. The package for microwave oven cooking according to 1 or 2, wherein the protruding portion is formed in a U-shape or a V-shape.
4). Furthermore, the opening part which protruded toward the outer side direction of a container was formed in the peripheral seal part of the packaging body for microwave oven cooking, The packaging body for microwave oven cooking in any one of 1-3 characterized by the above-mentioned.
5. The package for microwave oven cooking according to 4, wherein the opening portion is formed in a V shape.
The peripheral seal part of the packaging for microwave oven cooking of the present invention can be formed by providing a convex part on the entire circumference of the flange part of the container body and heat-sealing the lid on the convex part. Moreover, you may form a peripheral seal part by heat-sealing a cover body, without providing a convex part in a flange part.

According to the present invention, when cooking with a microwave oven, an opening is formed in which the entire steam vent seal portion is opened by completely peeling to the side of the steam vent seal portion of the microwave oven cooking package. The following remarkable effects can be achieved.
1) At the time of cooking with a microwave oven, it is possible to prevent the package from rupturing and foods from being scattered, thereby contaminating the inside of the microwave oven or causing harm such as burns to the human body.
2) Since the steaming effect of the food stored in the package is obtained by water vapor generated by microwave heating, the taste of the food is improved.
3) Since an opening is formed in which the entire vapor vent seal portion is opened, it is possible to reliably prevent the opening from being blocked by the lid and the container from being deformed.
4) The appearance of the package after cooking is excellent, and the food can be easily taken out from the package, so that the practical value of the package can be greatly increased.

In the present invention, a plastic material having heat sealability, which is usually used for manufacturing a packaging container, is used as the material constituting the container body and lid of the microwave cooking package. As such a plastic material, for example, a single layer film or sheet made of a thermoplastic resin having heat sealability, a multilayer film or sheet in which a thermoplastic resin having heat sealability is laminated with another thermoplastic resin, or the like Etc.
Examples of such a plastic material having heat sealability include known low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, propylene-ethylene copolymer, ethylene-vinyl acetate copolymer. Olefin resins such as olefin resins graft-modified with an ethylene unsaturated carboxylic acid or an anhydride thereof; polyamides or copolyamide resins having a relatively low melting point or a low softening point; polyesters or copolyester resins; polycarbonate resins, etc. used.

In addition, as other plastic materials to be laminated with the plastic material having heat sealability, thermoplastic resins with or without heat sealability, various barrier films, and oxygen-absorbing resins can be used.
Examples of such thermoplastic resins include crystalline polypropylene, crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly-4-methylpentene-1, low-, medium-, or high-density polyethylene, Polyolefins such as ethylene-vinyl acetate copolymer (EVA), EVA saponified product, ethylene-ethyl acrylate copolymer (EEA), ion-crosslinked olefin copolymer (ionomer); polystyrene, styrene-butadiene copolymer, etc. Aromatic vinyl copolymers; vinyl halide polymers such as polyvinyl chloride and vinylidene chloride resins; polyacrylic resins; nitrile polymers such as acrylonitrile-styrene copolymers, acrylonitrile-styrene-butadiene copolymers; polyethylene Terephthalate, polytetramethylene terephthalate Polyesters such as 6-nylon, 12-nylon, polyamides such as metaxylylenediamine (MX) nylon; various polycarbonates; fluororesins; thermoplastic resins such as polyacetals such as polyoxymethylene be able to. These thermoplastic resins can be used alone or in combination of two or more, and various additives may be blended and used.

As the barrier film, any film composed of a known thermoplastic resin having an oxygen barrier property can be used. Examples of such resins include ethylene-vinyl alcohol copolymers, polyamides, polyvinylidene chloride resins, polyvinyl alcohol, fluororesins, and the like, but do not contain chlorine that does not generate harmful gases during incineration. It is preferable to use a resin.
A particularly preferred oxygen barrier resin is an ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%, and a saponification degree of 96 mol% or more, particularly 99 mol% or more. A saponified copolymer obtained by saponification to be
Other preferred oxygen barrier resins include polyamides in which the number of amide groups per 100 carbon atoms is in the range of 5 to 50, especially 6 to 20; for example, nylon 6, nylon 6,6, nylon 6 / 6,6 copolymer, metaxylylene adipamide (MX6), nylon 6,10, nylon 11, nylon 12, nylon 13 and the like.

Other barrier films include silica-deposited polyester film, alumina-deposited polyester film, silica-deposited nylon film, alumina-deposited nylon film, alumina-deposited polypropylene film, carbon film-deposited polyester film, carbon film-deposited nylon film; and alumina and silica. Binary vapor-deposited film co-deposited on base film such as polyester film and nylon film; nylon 6 / metaxylylenediamine nylon co-extruded film, polypropylene / ethylene-vinyl alcohol copolymer co-extruded film; and polyvinyl alcohol-coated polypropylene film , Polyvinyl alcohol coated polyester film, Polyvinyl alcohol coated nylon film, Polyacrylic resin Organic resins such as polyester film, polyacrylic acid resin coated nylon film, polyacrylic acid resin coated polypropylene film, polyglycolic acid resin coated polyester film, polyglycolic acid resin coated nylon film, polyglycolic acid resin coated polypropylene film Coat film; Further, a hybrid coat material made of an organic resin material and an inorganic material may be coated on a base film such as a polyester film, a nylon film, or a polypropylene film.
These barrier films can be used alone or in combination of two or more.

  As the oxygen-absorbing resin, (1) a resin having an oxygen-absorbing property can be used. Moreover, (2) The resin composition which mix | blended the oxygen absorber in the thermoplastic resin which has or does not have oxygen absorptivity can be used. There is no restriction | limiting in particular as a thermoplastic resin which comprises an oxygen absorptive resin composition (2), Both the thermoplastic resin which has oxygen barrier property, and the thermoplastic resin which does not have oxygen barrier property can be used. As the thermoplastic resin constituting the oxygen-absorbing resin composition (2), when the resin itself has an oxygen-absorbing property or an oxygen-barrier property, the container has a synergistic effect with the oxygen-absorbing effect by the oxygen absorbent. It is preferable because oxygen can be effectively prevented from entering the inside.

  Examples of the resin itself having oxygen absorptivity include those utilizing an oxidation reaction of the resin. For example, polybutadiene, polyisoprene, polypropylene, ethylene carbon monoxide copolymer; oxidation catalysts such as polyamides such as 6-nylon, 12-nylon, metaxylylenediamine (MX) nylon, and oxidation catalyst. And organic acid salts containing transition metals such as cobalt, rhodium and copper; and those added with photosensitizers such as benzophenone, acetophenone and chloroketones. When these oxygen-absorbing materials are used, further effects can be exhibited by irradiating with high energy rays such as ultraviolet rays and electron beams.

As the oxygen absorbent to be blended in the thermoplastic resin, all oxygen absorbents conventionally used for this kind of application can be used. In general, oxygen absorbers that are reducible and substantially insoluble in water are preferred. Suitable examples of oxygen absorbers include reducing metal powders such as reducing iron, reducing zinc, reducing tin powders; metal lower oxides such as FeO, Fe ₃ O ₄ ; reducing metal compounds such as The main component is a combination of one or more of iron carbide, silicon iron, iron carbonyl, ferrous hydroxide and the like. As a particularly preferred oxygen absorbent, reducing iron, for example, iron oxide obtained in the steel production process is reduced with coke, and the resulting sponge iron is pulverized and then subjected to finish reduction in hydrogen gas or decomposed ammonia gas. Reducing iron: reduced iron obtained by electrolytically depositing iron from an aqueous solution of iron chloride obtained in the pickling process of steel, and then performing final reduction after pulverization.
These oxygen absorbers can be used as required in alkali metal, alkaline earth metal hydroxides, carbonates, sulfites, thiosulfates, tertiary phosphates, secondary phosphates, organic acid salts, halogens. It can also be used in combination with an oxidation accelerator composed of an electrolyte such as a chemical compound, and further an auxiliary agent such as activated carbon, activated alumina, activated clay. Particularly preferred oxidation promoters include sodium chloride, calcium chloride, or combinations thereof.
When reducing iron and an oxidation accelerator are used in combination, the blending ratio of both is 99 to 80 parts by weight of reducing iron and 1 to 20 parts by weight of an oxidation accelerator, with the total amount being 100 parts by weight. It is preferable to use 98 to 90 parts by weight of reducing iron and 2 to 10 parts by weight of an oxidation accelerator.

Other oxygen absorbers include polymer compounds having a polyhydric phenol in the skeleton, such as polyhydric phenol-containing phenol / aldehyde resins. Furthermore, ascorbic acid, erythorbic acid, tocopherols and salts thereof, which are water-soluble substances, can be suitably used. Of these oxygen-absorbing substances, reducing iron and ascorbic acid compounds are particularly preferable.
Moreover, you may mix | blend the resin in which said resin itself has oxygen absorptivity in a thermoplastic resin as an oxygen absorber.
These oxygen absorbents generally have an average particle size of 50 μm or less, particularly 30 μm or less. When the oxygen absorbent needs to be transparent or translucent, it preferably has an average particle size of 10 μm or less, particularly 5 μm or less. The oxygen absorbent is preferably blended in the above resin in a proportion of 1 to 70% by weight, particularly 5 to 30% by weight.

  Contents such as cooked rice filled in the container in the present invention are easily deteriorated by various germs, fungi and oxygen, and the flavor tends to be lowered. Therefore, in the present invention, it is preferable to use a multilayer structure including various barrier films and an oxygen-absorbing resin layer as the constituent material of the container body and the lid. An adhesive layer can be interposed between the layers constituting the laminate as necessary. Such an adhesive is not particularly limited, and for example, a polyolefin adhesive modified with an acid anhydride such as maleic anhydride, a polyurethane adhesive, and the like, which are usually used as adhesives for laminates Either can be used.

  As a preferred layer structure of the laminate constituting the container body, for example, a gas barrier resin such as polypropylene (PP) / adhesive / ethylene vinyl acetate copolymer saponified product (EVOH) is sequentially formed from the outer layer side of the container. / Adhesive / PP; PP / adhesive / EVOH / adhesive / oxygen-absorbing resin layer (for example, polyolefin containing reducing iron and oxidation accelerator) / PP.

  Moreover, as a suitable layer structure of the laminated body constituting the cover material, for example, in order from the outer layer side of the cover body, nylon (NY) / EVOH / PP-based / polyethylene (PE) -based composite material; NY / EVOH / straight Examples include linear low density polyethylene (LLDPE); vapor-deposited polyethylene terephthalate (PET) / NY / PP-based / PE-based composite materials; vapor-deposited PET / NY / LLDPE; vapor-deposited PET / NY / polybutylene terephthalate (PBT) -based resins. .

Below, based on drawing, the specific example of the packaging body for microwave oven cooking of this invention is demonstrated in detail.
1-5 is a figure which shows one example of the packaging body for microwave oven cooking of this invention. FIG. 1 is a plan view of the package, and FIG. 2 is a front sectional view of the package. And FIG. 3 is the elements on larger scale of the protrusion part (steam removal seal | sticker part) of the heat seal part formed in the flange part of a package. Moreover, FIG. 4 represents the cross-sectional schematic diagram in the XX line of FIG. 1 at the time of heat-cooking a package body with a microwave oven. Furthermore, FIG. 5 represents the cross-sectional schematic diagram which shows a mode that the pressure in a container reduces by the fall of the temperature in a container, after cooking a package body with a microwave oven.

In this microwave cooking packaging 1, a container body 3 having a flange portion 2 having a circular cross-sectional shape is filled with food such as cooked rice (F in FIG. 5), and the lid 4 is heat sealed to the flange portion 2. And sealed. The flange portion 2 of the container is provided with a convex portion 5 over the entire circumference, and a peripheral seal portion 6 is formed by heat-sealing the lid 4 on the convex portion 5 (see FIG. 4). . The peripheral seal portion 6 is provided with a substantially V-shaped protruding portion 7 directed inward of the container to form a steam release seal portion 8.
In this package 1, the seal width t ₁ of the peripheral seal portion 6, the seal width t ₂ of the side of the protrusion 7, and the seal width t ₃ of the tip of the protrusion 7 are expressed by the following equations (1) and (2) (See FIG. 3).
t ₃ > t ₂ (1)
t ₁ ≧ t ₂ (2)

Further, the seal width t _{2 at} the side of the protrusion and the seal width t ₃ at the tip of the protrusion are configured to satisfy the following expression (3).
_{t 2 / t 3 = 0.6~0.9 (} 3)
And the peripheral seal part which opposes this steam release seal part 8 is for opening the cover body 4 after cooking by a microwave oven by projecting the peripheral seal part 6 in a V shape toward the container outer side direction. An opening portion 12 is formed.

When the microwave oven cooking package 1 is cooked in a microwave oven, water such as water vapor generated from food such as cooked rice filled in the container or air such as air present in the head space (S in FIG. 5) in the container is heated. By expanding, the internal pressure of the container rises, and the lid 4 expands outward (see FIG. 4).
In the microwave oven cooking package in which the steam seal part is formed by projecting the peripheral seal part inward of the container, peeling of the heat seal part starts from the tip part of the protruding part 7, and this peeling is the protruding part 7. When the outer edge of the front end heat seal part is reached, the front end heat seal part is partially opened, high-temperature steam blows out from the opening part, and the internal pressure is lowered to complete cooking of the contents. When the package 1 after cooking is taken out from the microwave oven, the volume of the thermally expanded water vapor shrinks as the temperature in the container decreases, and the pressure inside the container decreases (see FIG. 5). . At that time, since the side portion of the protruding portion 7 is left without being peeled off, the steam vent seal portion is blocked by the lid, and the sealed container is in a reduced pressure state and the container is deformed. was there. When such deformation of the container occurs, there are disadvantages that the appearance is deteriorated and the commercial value is lowered, and it is difficult to take out the cooked food.

In the microwave oven packaging body of the present invention, the seal width t ₁ of the peripheral seal portion 6, the seal width t ₂ of the side of the protruding portion 7, and the seal width t ₃ of the tip of the protruding portion 7 are expressed by the above formula (1 ) And (2), when the internal pressure of the container rises, the projecting portion 7 constituting the steam vent seal portion 8 is completely peeled to the side, and the entire steam vent seal portion 8 is Opened openings are formed. Therefore, when the package 1 after cooking is taken out from the microwave oven and the temperature is lowered, it is possible to prevent the opening from being blocked by the lid 4 and the container from being deformed.
Further, by making the side seal width t ₂ narrower than the tip seal width t ₃ (Equation (1)), the side peel strength is relatively lower than the tip, so the tip is peeled off. When the peeling reaches the side with the internal pressure increased to a sufficient level, the entire side can be peeled off at once. However, if the seal width t ₂ of the sides thicker than the peripheral sealing section t ₁ [not satisfy Expression (2)], the release of at the sides for absolute peel strength is greater does not proceed sufficiently.
Then, proceed the peeling of the side more smoothly, be configured seal width t ₂ of the sides of the _protrusions, the seal width t ₃ of the tip portion of the protruding portion so as to satisfy the equation (3) above Is preferred.

After the cooking is completed, the packaging body 1 which has been taken out of the microwave oven and lowered in temperature to some extent can be eaten as it is by opening the lid body 4 by hand from the opening portion 12 provided on the peripheral seal portion facing the protruding portion 7. it can. At this time, the peripheral portion may become hot due to the high temperature steam blown out from the projecting portion 8 that has opened, but since this steam blows out in the direction opposite to the opening portion 12, the lid 4 is opened. Can be opened safely.
In the microwave oven cooking packaging body 1 of the present invention, since the container does not deform, the appearance of the packaging body 1 after cooking is excellent, and the food can be easily taken out from the packaging body 1. The practical value of 1 can be greatly increased.

  In the above example, the steam release seal portion 8 is formed by providing the peripheral seal portion 6 with the V-shaped protrusion 7 facing inward of the container. This protrusion 7 can be seen in FIG. It may be formed in a U shape.

  FIG. 7: is a top view which shows the other example of the packaging body for microwave oven cooking of this invention. In this microwave cooking packaging 11, by providing V-shaped projecting portions 7 and 7 directed inward of the container at two locations on the peripheral seal portion 6, the steam release seal portions 8 and 8 are formed, Unsealed portions 12 and 12 are formed by projecting two portions of the peripheral seal portion 6 in a V shape toward the outside of the container. The other structure of the package 11 is the same as that of the package 1 of FIG.

  FIG. 8: is a top view which shows the other example of the packaging body for microwave oven cooking of this invention. In this microwave cooking packaging 21, by providing V-shaped projecting portions 7, 7 facing inward of the container at two locations on the peripheral seal portion 6, the steam release seal portions 8, 8 are formed, The opening part 12 is formed by projecting one part of the peripheral seal part 6 in a V shape toward the outside of the container. The other structure of the package 21 is the same as that of the package 1 of FIG.

9 and 10 are views showing another example of the microwave oven cooking package according to the present invention, FIG. 9 is a plan view, and FIG. 10 is a front view.
In this microwave cooking packaging 31, a rectangular container body 3 having a flange portion 2 is filled with food (not shown) such as cooked rice, and the lid 4 is heat sealed to the flange portion 2 and sealed. Is. The flange part 2 of this container is provided with a convex part (not shown) over the entire circumference in the same manner as the container of FIGS. 1 to 5, and the lid 4 is heat-sealed on this convex part. A peripheral seal portion 6 is formed. A steam vent seal portion 8 is formed at one corner portion of the container by projecting the peripheral seal portion 6 in a substantially V shape toward the inside of the container. Moreover, the opening part 12 is provided in the corner part which opposes by making the peripheral seal part 6 protrude in the V shape toward the outer side of a container.

  FIG. 11: is a top view which shows the other example of the packaging body for microwave oven cooking of this invention. In the microwave oven cooking packaging 41, the steam seal 8 is not provided at the corner, but the peripheral seal 6 is substantially inward of the short side and the long side of the rectangular container toward the inside of the container. The steam vent seal portions 8 and 8 are formed by projecting in a V shape. The other structure of the package 41 is the same as that of the package 31 of FIG.

  FIG. 12 is a plan view showing another example of the microwave oven cooking package of the present invention. In this microwave cooking packaging 51, steam seals 8 and 8 are formed by projecting the peripheral seal 6 in a substantially V shape toward the inside of the container at the opposite corner of the container. ing. Moreover, the opening parts 12 and 12 are provided in the other opposing corner part by making the peripheral seal part 6 protrude in the V shape toward the outer side of a container. The other structure of the package 51 is the same as that of the package 31 of FIG.

FIG.13 and FIG.14 is a figure which shows the other example of the packaging body for microwave oven cooking of this invention, FIG. 13 is a top view, and FIG. 14 is a front view.
This microwave cooking packaging body 61 is obtained by heat-sealing the lid 4 on the flange portion 2 of the container main body provided with two rectangular storage chambers 13 and 14 adjacent to each other. Steam release seal portions 8 and 8 are formed at the corner portions of the storage chambers 13 and 14 by projecting the peripheral seal portion 6 in a substantially V shape toward the inside of the container. In addition, opening portions 12 and 12 are provided at the other corner portions by projecting the peripheral seal portion 6 in a V shape toward the outside of the container. The other structure of the package 61 is the same as that of the package 31 of FIG.

The container main body and the lid which constitute the microwave oven cooking package of the present invention can be manufactured by a conventional method. For example, vacuum forming, pressure forming, vacuum pressure forming, injection molding, etc. can be adopted as a method for forming the container body.
Further, when the seal portion is constituted by the convex portion 5 of the flange portion 2, it can be molded by a mold simultaneously with the molding of the container. And the flange part 2 can be made flat and the protrusion of the shape corresponding to a heat seal bar can be provided, and a seal part can also be formed at the time of heat sealing of a cover body.

Hereinafter, although the Example further demonstrates the microwave oven cooking package of this invention, the following specific examples do not limit this invention.
Example 1
In order from the outer layer, polypropylene resin outer layer (thickness 310 μm) obtained by adding titanium white pigment to polypropylene having a melt index (MI) 0.5 / adhesive layer (thickness 20 μm) made of maleic anhydride-modified polypropylene / ethylene-vinyl alcohol A total thickness of 0.005 in a three-layered five-layer structure comprising a barrier layer made of a copolymer (thickness 40 μm) / the same adhesive layer (thickness 20 μm) as described above / MI = 5 polypropylene resin inner layer (thickness 310 μm) A 7 mm multilayer sheet was produced by conventional coextrusion molding.
Using this multilayer sheet, a flanged round container having the shape shown in FIG. 1 having a container outer diameter of 134 mm and a height of 44 mm (inner volume of about 325 ml) was produced by a normal vacuum / pressure forming machine (flange). Width 14 mm). At that time, a convex portion 5 for hermetically sealing the entire flange portion of the container body is formed (the convex height is 0.7 mm), and as shown in FIG. 7 and an opening 12 that protrudes toward the outside of the container is provided at a position facing this. About the width | variety (internal dimension) of the protrusion part 7, the various things shown in Table 1 were produced.

(Preparation of lid material)
On the other hand, a 12 μm thick biaxially stretched polyester film (outer layer), a 15 μm thick biaxially stretched nylon film (intermediate layer), and a 50 μm thick polypropylene-based composite film (inner layer) are used. Then, a polyurethane-based adhesive was interposed between the resin layers, and a laminated body constituting the lid material was formed by ordinary dry lamination, and cut into predetermined dimensions to produce a lid body. .

(Production of packaging containers)
Using an aseptic packaging and filling line, 200 g of aseptic cooked rice was filled into the container, and then the lid was heat sealed to the flange portion of the container and sealed.
(Evaluation of sealing performance)
The burst strength of each of the packaging containers filled and sealed with the obtained aseptic cooked rice was measured in accordance with JIS Z 0238 “Testing method of heat-sealing flexible packaging bags and semi-rigid containers / Burning strength test of containers” and averaged. Values with a value of 20 kPa or more are shown in Table 1, and those with a value of less than 20 kPa and 10 kPa or more are shown in Table 1. During this evaluation, there was nothing that did not reach 10 kPa.
In addition, about the packaging container of Example 2, they were seal strength 23N / 15mm, opening strength 15N / cup, and burst strength 25kPa.

(Microwave oven test)
Five packaging containers each filled and sealed with the obtained aseptic cooked rice were cooked for 2 minutes in a microwave oven with an output of 600 W. After the heating was completed, the mixture was left until it fell to room temperature, and the state of container deformation during that time was visually observed. Table 1 shows the case where no deformation was observed, and ○ shows the case where the deformation occurred.

Example 9
A packaging container filled with sterile cooked rice was produced in the same manner as in Example 2 except that the shape of the protruding portion 7 was U-shaped. The sealing property of this container was 20 kPa or more, and no deformation of the container was observed in the microwave oven test.

As seen in each of the above examples, according to the present invention, when the microwave oven cooking package having a steam vent seal portion is cooked in a microwave oven, the steam vent seal portion completely peels to the side. Accordingly, a microwave cooking packaging body that can completely prevent the open steam release seal portion from being blocked by the lid and deforming the container is obtained.
Suitable contents of the microwave oven cooking package of the present invention include foods with high moisture content such as porridge, risotto, curry, stew, and soup, in addition to cooked rice.

It is a top view which shows one example of the package for microwave oven cooking of this invention. It is front sectional drawing of the package of FIG. It is the elements on larger scale of the protrusion part of the package of FIG. It is a cross-sectional schematic diagram at the time of heat-cooking the package of FIG. 1 with a microwave oven. It is a cross-sectional schematic diagram after heat-cooking the package of FIG. 1 with a microwave oven. It is the elements on larger scale of the protrusion part which shows the other example of the packaging body for microwave oven cooking of this invention. It is a top view which shows the other example of the package for microwave oven cooking of this invention. It is a top view which shows the other example of the package for microwave oven cooking of this invention. It is a top view which shows the other example of the package for microwave oven cooking of this invention. It is a front view of the package of FIG. It is a top view which shows the other example of the package for microwave oven cooking of this invention. It is a top view which shows the other example of the package for microwave oven cooking of this invention. It is a top view which shows the other example of the package for microwave oven cooking of this invention. It is a front view of the package of FIG.

Explanation of symbols

1, 11, 21, 31, 41, 51, 61 Microwave cooking packaging 2 Flange 3 Container body 4 Lid 5 Convex 6 Peripheral seal 7 Projection 8 Steam vent seal 12 Opening 13 and 14 Storage room

Claims (5)

A packaging body for microwave oven cooking in which a synthetic resin container body having a flange portion is filled with contents, and the peripheral edge portion of the lid is heat sealed to the flange portion, and the peripheral heat seal portion is placed inside the container. A steam vent seal portion is formed by providing a projecting portion directed in the direction, and the seal width t ₁ of the peripheral seal portion, the seal width t ₂ of the side portion of the projecting portion, and the seal width t ₃ of the tip portion of the projecting portion are A microwave cooking package characterized by satisfying the following formulas (1) and (2):
t ₃ > t ₂ (1)
t ₁ ≧ t ₂ (2) Moreover, microwave cooking according to claim 1 in which the seal width t ₂ of the sides of the _protrusions, the seal width t ₃ of the tip portion of the protruding portion, characterized in that a satisfies the following equation (3) Package:
_{t 2 / t 3 = 0.6~0.9 (} 3)   The package for microwave oven cooking according to claim 1 or 2, wherein the protruding portion is formed in a U-shape or a V-shape.   Furthermore, the opening part which protruded toward the outer side direction of a container was formed in the peripheral seal part of the packaging body for microwave oven cooking, The packaging body for microwave oven cooking in any one of Claims 1-3 characterized by the above-mentioned. The package for microwave oven cooking according to claim 4, wherein the shape of the opening portion is formed in a V shape.

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