JP4924613B2 - Packaging for microwave oven cooking - Google Patents

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 internal pressure of the packages may increase due to water vapor generated from food stored in the container, and the packages 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 to 3). 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 JP 2000-62858 A

On the other hand, when the lid is heat-sealed to the flange portion of the synthetic resin container filled with the contents, after performing a heat seal for sealing, a so-called knurled seal is provided over the entire circumference of the flange portion including the heat seal portion. It is widely performed to prevent the heat-sealed lid outer end from being turned up (see, for example, Patent Document 4).
JP-A-3-29769

  As shown in FIG. 13, even in the microwave oven cooking package in which the steam release seal portion is formed, it has been attempted to provide a knurled seal in addition to a heat seal for sealing. However, when cooking with a microwave oven, the steam generated from the contents passes between the flange part and the lid and automatically opens a steam release seal part. When applied, the automatic opening property of the steam vent seal is hindered. As a result, there is a problem that an automatic opening from a predetermined part is not performed at the time of cooking by a microwave oven or an abnormality such as an explosive opening occurs.

  Therefore, according to the present invention, when the lid is heat-sealed to the flange portion described above, a steam release seal portion is formed by providing a protrusion portion projecting inward of the container in the heat seal portion, and a knurled seal is further applied. It aims at solving the problem peculiar to the package for microwave oven cooking. In other words, the present invention prevents a roll-up of the outer end of the lid heat-sealed to the flange portion, and the microwave oven packaging in which the lid automatically opens due to an increase in pressure in the container during microwave cooking. The purpose is to provide the body at low cost.

In the present invention, the following configurations 1 to 7 are employed to solve the above-described problems.
1. In a microwave oven cooking package in which a synthetic resin container body having a flange portion is filled with contents, and a lid body is heat-sealed and sealed to the flange portion, steam is heated at a part of the flange portion when the microwave oven is heated. Providing a concave portion on the inside and outside of the heat seal portion in the portion that becomes the vent seal portion to provide a protruding portion toward the inner side of the container to form a steam vent seal portion, from the steam vent seal portion to the outer end of the container At least one auxiliary seal part is provided by heat-sealing the flange part and the lid body at a part reaching the part, and a knurled seal is applied to regions other than the outer part and the inner part of the steam release seal part. Features a microwave oven packaging.
2. 2. The microwave oven cooking package according to 1 , wherein at least one auxiliary convex portion is provided in the concave portion, and an auxiliary seal portion is formed by heat sealing the auxiliary convex portion and the lid .
3. 3. The microwave oven cooking package according to 1 or 2, wherein the auxiliary seal portion is formed as a spot-like spot seal .
4). 4. The microwave oven cooking package according to any one of 1 to 3, wherein at least one auxiliary seal portion is provided also on an inner portion of the steam release seal portion .
5. The package for microwave oven cooking according to any one of claims 1 to 4, wherein the protruding portion is formed in a U-shape or a V-shape .
6). The electronic device according to any one of 1 to 5, wherein an opening portion protruding toward the outer side of the container is formed at a position facing the steam release seal portion of the heat seal portion of the packaging for microwave oven cooking. Package for cooking range.
7). The package for microwave oven cooking according to 6, wherein the shape of the opening portion is V-shaped .

In this invention, an auxiliary | assistant seal | sticker part is a seal | sticker part which does not participate in the sealing seal of the content accommodated in a container. The knurled seal is a seal in which the seal mark has a grid pattern, and the area ratio of the seal part to the non-seal part in the knurled part is about 1/9 to 6/4. Usually, it is preferable that the length of one side of the grid is about 0.3 to 1 mm and the pitch is about 0.7 to 1.0 mm. The knurled seal is applied under such a condition that the seal portion is sealed to such an extent that it does not peel off. For example, using a sealing tool as shown in FIG. 8, heat sealing is performed at 170 to 240 ° C. for 1 to 3 seconds at a sealing surface pressure of about 10 to 40 kg / cm ² .

  According to the present invention, after the container body having the flange portion is filled with the contents, the lid body is heat-sealed and sealed to prevent the outer end of the lid body from turning up, It is possible to prevent foreign matters from being mixed between the lid and the flange portion in the sales process. In addition, when cooking with a microwave oven, the lid can surely automatically open from the steam vent seal portion due to the pressure increase in the container, and smooth discharge of steam via the steam vent seal portion can be realized.

FIG. 1 is a plan view showing an example of a microwave oven cooking package according to the present invention. FIG. 2 is a front view of the package of FIG. FIG. 3 is a partially enlarged view of the protruding portion of the heat seal portion formed on the flange portion of the package of FIG. 4 is a schematic cross-sectional view taken along line AA of FIG. 3 when the package of FIG. 1 is cooked with a microwave oven. FIG. 5 is a schematic cross-sectional view taken along line BB in FIG. 3 when the package of FIG. 1 is cooked with a microwave oven. FIG. 6 is a partially enlarged view of a flange portion that forms a steam release seal portion before heat-sealing the lid body in the package of FIG. 1. FIG. 7 is a partially enlarged view of a sealing tool used when heat-sealing the lid body to the flange portion of the container body. FIG. 8 is a partially enlarged view of a sealing tool used when a knurled seal is applied to the flange portion of the microwave oven cooking package of the present invention. FIG. 9 is a partially enlarged view of a steam release seal part of the package, showing another example of the microwave oven package of the present invention. FIG. 10: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention. FIG. 11: is the elements on larger scale of the steam-release seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention. FIG. 12: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention. FIG. 13 is a plan view showing an example of a conventional microwave cooking package. FIG. 14: is a top view which shows the other example of the microwave oven cooking package of this invention. FIG. 15 is a front view of the package of FIG. FIG. 16: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention. FIG. 17: is the elements on larger scale of the steam-release seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention. FIG. 18: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention.

Explanation of symbols

1, 11, 21, 31, 41, 51, 61, 71, 81, 91 Packaging for microwave oven cooking 2 Flange 3 Container body 4 Lid 5 Heat seal part 6, 7 Recess 8 Protrusion 9 Auxiliary seal 10 , 18 Seal tool 13 Knurled seal 20 Convex parts 32, 33 Wide part

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; halogenated vinyl 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; 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 absorption property 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.
1-7 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, FIG. 2 is a front view of the package, and FIG. 3 is a partially enlarged view of the protrusion of the heat seal portion formed on the flange of the package. Moreover, FIG. 4 represents the cross-sectional schematic diagram in the AA line | wire of FIG. 3 at the time of heat-cooking a package body with a microwave oven. FIG. 5 is a schematic cross-sectional view taken along line BB in FIG. 3 when the package is cooked with a microwave oven. Furthermore, FIG. 6 represents the elements on larger scale of the flange part which forms the protrusion part of the steam removal seal | sticker part before heat-sealing a cover body. FIG. 7 shows a partially enlarged view of a sealing tool used when heat-sealing the lid to the flange portion. FIG. 8 is a partially enlarged view of a sealing surface of a sealing tool used when a knurled seal is applied to the flange portion where the lid is heat-sealed.

In this microwave cooking packaging 1, a rectangular container body 3 having a flange portion 2 is filled with food (not shown) such as cooked rice, and a lid 4 is heat sealed to the flange portion 2 and sealed. It is.
And in one corner part of a container, the heat seal part 5 is pinched | interposed into a part of flange part, and the recessed part 6 and 7 which were respectively independent inside the heat seal part 5 are provided in the heat seal part 5 A V-shaped projecting portion 8 directed toward the inner side of the container is formed as a steam vent seal portion. Further, in the concave portion 7 outside the steam release seal portion 8, one circular spot seal 9 is formed as an auxiliary seal portion by heat-sealing the flange portion 2 and the lid body 4 in a dot shape.

Moreover, in the corner part which opposes this steam removal seal part 8, the heat seal part 5 is protruded in the V shape toward the container outer side direction, and the opening part 12 for opening the cover body 4 after cooking by a microwave oven Is forming.
Then, the knurled seals 13 and 13 are applied to the inner and outer sides of the heat seal portion 5 other than the outer concave portion 7 and the inner concave portion 6 of the steam release seal portion 8 to prevent the lid body 4 from turning up. ing. The knurled seal 13 is not provided in the portion 14 from the opening 12 to the outer end of the container in order to make it easier to open the lid 4 from the opening 12 after cooking with a microwave oven.

This steam release seal portion 8 has a lid 4 placed on the container body 3 provided with recesses 6 and 7 in the corner portion of the flange portion 2 shown in FIG. 6, and is heated using a seal tool 10 shown in FIG. It can be formed by sealing. When forming the outer recess 7 in the corner portion, the auxiliary seal portion 9 leaves a spot-like portion that is not partially recessed, and uses the sealing tool 10 with a flat sealing surface to remove the steam release seal portion 8. It can be provided simultaneously with the formation. Further, the recess 7 is entirely processed without leaving a portion corresponding to the auxiliary seal portion 9 in the recess 7, and the portion corresponding to the auxiliary seal portion 9 of the sealing tool 10 is partially raised and heat sealed. The auxiliary seal portion 9 may be formed.
At that time, the cover 4 is sandwiched between the portion (heat seal planned portion) sandwiched between the recesses 6 and 7 of the flange portion and the sealing tool 10 and heat sealed, so that the protrusion 8 and the auxiliary are provided in the heat seal portion 5. The seal portion 9 is formed at the same time. Therefore, unlike the conventional microwave oven cooking package, it is possible to reliably form the protrusion 8 without misalignment without requiring accurate alignment when forming the protrusion.

The depths of the recesses 6 and 7 provided in the flange portion 2 may be the same depth or different depths. The depth of the recess is usually about 0.05 to 3 mm, particularly preferably about 0.1 to 0.5 mm.
The seal width of the protruding portion 8 can be configured to be the same as or narrower than that of the peripheral heat seal portion 5, and is usually about 0.5 to 5 mm, particularly preferably about 1 to 3 mm. The seal strength of the protrusion 8 is preferably about 5 to 30 N / 15 mm. In this case, the seal strength means a value obtained by converting the seal width of the protrusion 8 into a width of 15 mm.

The auxiliary seal part 9 can be provided not only on the outer part 7 of the steam release seal part 8 but also on the inner part 6 of the steam release seal part 8 in order to improve the sealing performance of the package or improve the appearance. . When the auxiliary seal portion 9 is provided on the inner portion 6, it is preferable to minimize the size and number of seals so as not to hinder the discharge of steam.
The size of the auxiliary seal portion 9 can be appropriately selected according to the size of the container. When the auxiliary seal portion is formed as a spot-like spot seal, for example, the diameter can be 5 mm or less, usually about 0.3 to 2 mm. Moreover, the number is about 1-10 in total, Preferably it is 5 or less. There is no restriction | limiting in particular in the shape and arrangement | sequence of an auxiliary | assistant seal | sticker part, A round shape, a triangle, a square shape, an oval shape, etc. can be selected arbitrarily.
Further, for example, as shown in FIG. 16, the auxiliary seal portion may be formed as a seal portion having a certain area, and in this case, a seal form similar to the knurled seal portion may be employed.

The knurled seal 13 provided on the microwave oven packaging body is sealed by heat-sealing the flange portion 2 and the lid body 4 of the container body, and further, a plurality of convex portions 20 arranged in a grid pattern on the sealing surface. It can be formed using a sealing tool 18 having the same (see FIG. 8). The size of the convex portion 20 can be appropriately selected according to the size of the container, but usually one side of the convex portion is about 0.3 to 1 mm and the pitch is about 0.7 to 1.0 mm. It is preferable to do. The position where the knurled seal 13 is provided is usually provided on the entire surface of the flange portion 2, that is, on the inner side and the outer side including the peripheral heat seal portion 5. At that time, the knurled seal may be applied to the entire surface of the flange portion 2 including the heat seal portion 5, or the knurled seal may be applied in a form in which the heat seal portion 5 is omitted. Further, a knurled seal may be provided only on the outside of the heat seal portion 5.
By providing the knurled seal 13, the outer end of the lid body of the microwave cooking packaging 1 in which the lid body 4 is heat-sealed and sealed to the flange portion 2 is prevented from turning up. As a result, it is possible to prevent foreign matters from being mixed between the lid 4 and the flange portion 2 in the distribution / sales process.

  When the microwave oven cooking package 1 is cooked in a microwave oven, the internal pressure of the container rises due to water vapor generated from food such as cooked rice filled in the container, and the lid 4 expands outward. And in the protrusion part 8 provided in the corner part, peeling of a heat seal part starts from the front-end | tip part which protrudes in U shape or V shape toward the inner side of a container (refer FIG. 4). In that case, peeling of the heat seal part does not occur in other parts of the heat seal part 5, the internal pressure of the container is maintained, and food such as cooked rice filled in the container receives a sufficient steaming effect to improve the taste. .

  When the internal pressure of the container further rises and the peeling at the tip of the protruding portion 8 reaches the outer edge of the heat seal portion, the heat seal portion opens. And high temperature steam blows out from this opening part, the internal pressure in a container falls and cooking of the content is completed. After the cooking is completed, the package body can be taken out from the microwave oven, and the lid 4 can be opened by hand from the opening portion 12 provided at the corner portion facing the protruding portion 8, and the contents can be eaten as it is. At this time, high-temperature water vapor is blown out from the projecting portion 8 opened. However, since this water vapor blows out in the direction opposite to the opening 12, the lid 4 can be safely opened. Moreover, the packaging body for microwave oven cooking of this invention can maintain the internal pressure of a container to some extent also in the protrusion part 8 until the internal pressure of a container falls after a heat seal part opens automatically. A sufficient steaming effect can be given to things.

FIG. 9 is a partially enlarged view of a steam release seal part of the package, showing another example of the microwave oven package of the present invention.
In this microwave oven cooking packaging 11, two spot-like auxiliary seal portions 9, 9 are provided in the concave portion 7 outside the steam release seal portion 8. The other structure of the package 11 is the same as that of the package 1 of FIG.

FIG. 10: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention.
In the microwave oven cooking packaging body 21, a total of ten small spot-like auxiliary seal portions 9 are provided in the concave portion 7 outside the steam release seal portion 8. The other structure of the package 21 is the same as that of the package 1 of FIG.

FIG. 11: is the elements on larger scale of the steam-release seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention.
In this microwave oven cooking packaging 31, one slightly deformed oval auxiliary seal portion 9 is provided in the concave portion 7 outside the steam release seal portion 8. The other structure of the package 31 is the same as that of the package 1 of FIG.

FIG. 12: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention.
In the microwave oven cooking packaging 41, one elliptical auxiliary seal portion 9 is provided in the concave portion 7 outside the steam vent seal portion 8, and two elliptical shapes are also provided in the concave portion 6 inside the steam vent seal portion 8. Auxiliary seal portions 9 and 9 are provided. The other structure of the package 41 is the same as that of the package 1 of FIG.

FIG. 13 is a plan view showing an example of a conventional microwave cooking package. In this package 51, a V-shaped protruding portion 8 directed toward the inner side of the container is formed in the heat seal portion 5 at one corner portion of the container to form a steam release seal portion. Moreover, in the corner part which opposes this steam removal seal part 8, the heat seal part 5 is protruded in the V shape toward the container outer side direction, and the opening part 12 for opening the cover body 4 after cooking by a microwave oven Is forming.
And the knurling seals 13 and 13 are given to the inner side and the outer side of the heat seal part 5 over the entire circumference, thereby preventing the lid 4 from turning up. This knurled seal 13 is provided in a region 14 from the opening 12 to the outer end of the container in order to make it easy to open the lid 4 from the opening 12 after cooking the package 51 in a microwave oven. Not provided.

FIG.14 and FIG.15 is a figure which shows the other example of the packaging body for microwave oven cooking of this invention. FIG. 14 is a plan view of the package, and FIG. 15 is a front view of the package.
This microwave oven cooking packaging body 61 has a cup-shaped container body 3 having a flange portion 2 with a circular cross section filled with food (not shown) such as cooked rice, and the lid 4 is heat sealed to the flange portion 2. And sealed. The flange portion 2 is provided with a pair of wide portions 32 and 33 at opposing positions. One wide portion 32 is provided with recesses 6 and 7 with the heat seal portion 5 interposed therebetween, thereby providing the heat seal portion 5 with a V-shaped projecting portion 8 toward the inside of the container to provide the steam release seal portion 8. Forming. A circular auxiliary seal portion 9 is provided in the concave portion 7 outside the steam release seal portion 8.
Moreover, in the wide part 33 which opposes, the heat seal part 5 is protruded in the V shape toward the container outer side direction, and the opening part 12 for opening the cover body 4 is formed.

FIG. 16: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention.
In the microwave oven cooking packaging 71, one substantially triangular auxiliary seal portion 9 is provided in the recessed portion 7 outside the steam release seal portion 8 in a state separated from the heat seal portion 5 and the knurled seal portion 13. is there. The other structure of the package 71 is the same as that of the package 1 of FIG.
In this packaging body 71, when the internal pressure of the container rises due to microwave heating, and the peeling that starts from the tip of the protruding portion 8 of the heat seal portion 5 reaches the outer edge of the heat seal portion 5, the heat seal portion 5 opens. . High-temperature water vapor blows out from the opening, and is discharged outside the container through the recess 7 as a passage. The auxiliary seal portion 9 can be formed simultaneously with the knurled seal portion 13. The shape and size of the auxiliary seal portion 9 can be appropriately selected according to the size of the container.

FIG. 17: is the elements on larger scale of the steam-release seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention.
In this microwave cooking packaging 81, two auxiliary seal portions 9, 9 are connected to the heat seal portion 5 in the concave portion 7 outside the steam release seal portion 8. The other structure of the package 81 is the same as that of the package 1 of FIG.

FIG. 18: is the elements on larger scale of the steam removal seal | sticker part of a package which shows the other example of the package for microwave oven cooking of this invention.
In this microwave cooking packaging 91, two auxiliary seal parts 9, 9 are connected to the heat seal part 5 and the outer knurled seal part 13 in the recess 7 outside the steam release seal part 8. . The other structure of the package 81 is the same as that of the package 1 of FIG.

In each of the above examples, a microwave oven packaging body in which a protruding portion (steam vent seal portion) toward the inside of the container is formed by providing independent recesses on the inside and outside of the flange portion serving as the steam vent seal portion. Explained. The shape of the container main body or the lid is not limited to a square shape or a cup shape, and can be changed as appropriate, for example, an oval shape. Moreover, it cannot be overemphasized that the dimension can also be set arbitrarily.
A container main body and a cover body 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.

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 350 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 barrier layer (thickness: 60 μm) made of a copolymer / adhesive layer (thickness: 20 μm) same as the above / polypropylene resin inner layer (thickness: 350 μm) of MI = 0.5, total thickness in three types of five layers A multilayer sheet having a thickness of 0.8 mm was produced by ordinary coextrusion molding.
Using this multilayer sheet, a rectangular container with a flange having a shape shown in FIG. 1 and having an outer dimension of 156 mm × 133 mm and a height of 29 mm (inner volume of about 340 ml) was formed by a normal vacuum / pressure forming machine (flange). Width: straight part 8mm, corner part 17mm at maximum). In the flange portion 2 at the corner portion of the container, independent recesses 6 and 7 having a depth of 0.5 mm were formed on the inner side and the outer side across the portion corresponding to the heat seal portion with the lid at the time of molding. At that time, a circular spot-like portion having a diameter of 3 mm, which was not partially recessed, was left in the outer recessed portion 7.

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 member by dry lamination was formed by the following procedure.
First, an adhesive was applied to the outer layer material by a gravure roll or the like, and the solvent was evaporated and dried in a drying oven at a temperature of 80 to 100 ° C. Next, the adhesive layer and the intermediate layer material that are in a sticky state are bonded together, and after crimping with a heated metal roll and a rubber roll, the cooled metal roll is passed and wound. In the same procedure, the inner layer material was bonded to this laminate and cut into a desired size to form a lid.

Using a sterile packaging and filling line, 200 g of sterile cooked rice was filled in the container. Next, by using the sealing tool 10 of FIG. 7 and heat-sealing the lid 4 to the flange portion 2 of the container in the first step, the peripheral seal portion 5 having a seal width of 3 mm, and the peripheral portion A steam vent seal portion comprising a V-shaped projecting portion 8 projecting inward from the seal portion 5 by about 5 mm, and a spot-like auxiliary seal portion 9 were formed outside the steam vent seal portion 8. In addition, as shown in FIG. 1, the peripheral seal portion 5 is protruded outward from the container to form a V-shaped corner portion at the other corner portion to form an opening portion 12.
Next, using the sealing tool 18 of FIG. 8, the entire circumference of the flange portion 2 is removed in the second step except for the inner and outer concave portions 6 and 7 of the steam release seal portion 8 and the outer portion 14 of the opening portion 12. A microwave oven packaging body was obtained by applying a knurled seal.

(Example 2)
In Example 1, as shown in FIG. 12, except that a total of three spot-like auxiliary seal portions 9 are provided on the outer side 7 and the inner side 6 of the steam release seal portion 8 to form a square container, Similarly, 200 g of sterile cooked rice was filled and sealed in a container to obtain a microwave oven packaging.

(Example 3)
In Example 1, as shown in FIG. 16, a square container was formed by providing one substantially triangular auxiliary seal part 9 in the outer recessed part 7 of the steam release seal part 8. The container was filled with 200 g of sterile cooked rice and sealed to obtain a package for microwave cooking.

Example 4
In Example 1, as shown in FIG. 17, except that a rectangular container is formed by providing two auxiliary seal portions 9, 9 connected to the heat seal portion 5 in the concave portion 7 outside the steam release seal portion 8. In the same manner as in Example 1, 200 g of sterile cooked rice was filled and sealed in a container to obtain a microwave cooking packaging.

(Comparative Example 1)
As shown in FIG. 13, the lid 4 is heat-sealed to the flange portion 2 without forming the auxiliary seal portion outside the steam release seal portion 8, and then the outer portion 14 of the opening portion 12 is removed to remove the flange portion 2. A microwave oven cooking package in which 200 g of sterile cooked rice was filled and sealed in a container was obtained in the same manner as in Example 1 except that knurling was performed over the entire circumference.

Results obtained by cooking 20 each of the packaging bodies filled with sterile cooked rice obtained in each of the above examples in a microwave oven of 600 W and confirming whether steam escapes from the steam vent seal part within a predetermined time Is shown in Table 1.
In addition, Table 10 shows the results of confirming the presence or absence of breakage of the seal portion by dropping each of the 10 packaging bodies upside down and dropping 10 times continuously from a height of 120 cm in a 5 ° C. atmosphere.

For these containers, the seal strength (average value) measured from the inside of the peripheral seal portion 5 by the following method was 18 N / 15 mm. The unsealing strength (average value) measured from the outside of the unsealing seal portion 12 was 12 N / cup.
(Seal strength)
The container was fixed to the container holder, and the lid material was cut into a width of 15 mm on both sides of the seal part. Subsequently, the lid material inside the container was fixed to a chuck of a tensile tester, and the maximum load was measured by pulling upward in the 90 ° direction at a speed of 300 mm / min.
(Opening strength)
The sealing surface of the container was tilted by 45 ° and fixed to the container holder, the lid of the outer protrusion corresponding to the opening was fixed to the chuck, and the maximum load was measured by pulling upward at the same speed as described above.

As shown in Table 1, in the microwave oven cooking package of the present invention, the protruding portion that becomes the steam release portion gradually recedes with the increase of the internal pressure due to microwave heating, and it is very smooth and reliable within a predetermined time. The steam was removed. At this time, since the steam escape state was good, the container deformation was also kept small. In the drop test, the seal portion was not retracted or damaged.
Moreover, in the microwave oven cooking package of the present invention, the sealing property can be maintained until the steam is removed, compared to the conventional microwave oven heating after peeling off the lid material, so that the taste of cooked rice is improved by the steaming effect. Improved.
On the other hand, the package of Comparative Example 1 does not provide the auxiliary seal part at least outside the steam release seal part, and the knurled seal is provided over the entire circumference inside and outside the peripheral heat seal part including the inside and outside of the steam release seal part. It has been applied. In this package, there was a package in which steam escaped from a position other than the steam vent seal part by microwave heating, or steam did not escape within a predetermined time. Moreover, since the steam escape was slow, the deformation of the container was difficult to return.

Claims (7)

In a microwave oven cooking package in which a synthetic resin container body having a flange portion is filled with contents, and a lid body is heat-sealed and sealed to the flange portion, steam is heated at a part of the flange portion when the microwave oven is heated. Providing a concave portion on the inside and outside of the heat seal portion in the portion that becomes the vent seal portion to provide a protruding portion toward the inner side of the container to form a steam vent seal portion, from the steam vent seal portion to the outer end of the container At least one auxiliary seal part is provided by heat-sealing the flange part and the lid body at a part reaching the part, and a knurled seal is applied to regions other than the outer part and the inner part of the steam release seal part. Features a microwave oven packaging. The package for microwave oven cooking according to claim 1 , wherein at least one auxiliary convex portion is provided in the concave portion, and the auxiliary convex portion and the lid are heat sealed to form an auxiliary seal portion . The package for microwave oven cooking according to claim 1 or 2, wherein the auxiliary seal portion is formed as a spot-like spot seal . The package for microwave oven cooking according to any one of claims 1 to 3, wherein at least one auxiliary seal portion is also provided in an inner portion of the steam release seal portion . The package for microwave oven cooking according to any one of claims 1 to 4, wherein the protruding portion is formed in a U-shape or a V-shape . The opening part which protrudes toward the outer side direction of a container was formed in the position which opposes the steam removal seal part of the heat seal part of the packaging body for microwave oven cooking. Packaging for microwave oven cooking. The package for microwave oven cooking according to claim 6, wherein the shape of the opening portion is formed in a V shape .

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