JP2008290738A - Packaging container for microwave cooking - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging container for by microwave cooking in which a projecting part is formed over the entire periphery of a flange part of the packaging container, a lid body is heat-sealed to the projecting part, any positional deviation of an inwardly projecting part forming an automatic opening part generated when heat-sealing the lid body is eliminated, melting of the flange part inward of the container of the projecting part and forming of any resin pool are prevented, the taste of a content is enhanced by the steaming effect during the heat-cooking by the microwave oven, and the lid body is reliably and automatically opened from the projecting part by the increase of the pressure in the container. <P>SOLUTION: In the packaging container for by microwave cooking in which the projecting part is formed over the entire periphery of the flange part of a synthetic resin-made container body, and the lid body is heat-sealed to the projecting part, the projecting part inward of the container is formed on the heat-sealed part, and the seal width of the projecting part is larger than the seal width of a peripheral edge other than the projecting part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  2. Description of the Related Art Conventionally, various types of packaging containers for microwave cooking are known in which retort foods, frozen foods, and the like are stored in a synthetic resin sealed container and cooked in a microwave oven when eating. However, when these packaging containers are heated in a microwave oven, the internal pressure of the packaging container rises due to water vapor generated from the food, the packaging container ruptures and the food is scattered, and the inside of the microwave oven is soiled or damaged by the human body. There is a risk of injury such as burns.

For this reason, before cooking such a packaging container in a microwave oven, the packaging container is partially opened beforehand, or water vapor generated in the packaging container is discharged to the outside by opening a hole in the packaging container. The method of preventing the rupture of the packaging container is taken.
However, such a method is time-consuming for general consumers, and since steam generated by microwave heating is immediately discharged out of the packaging container, the steaming effect by steam is reduced and the taste is reduced. There is a drawback of falling.

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. Proposing various types of packaging containers for microwave oven cooking by automatically opening the protrusions by increasing the internal pressure in the container and preventing the packaging container from bursting when cooking in a microwave oven Has been. (For example, see Patent Documents 1 to 3)
A microwave cooking packaging bag is also proposed in which an opening sealing portion that automatically opens when cooking with a microwave oven is provided at the peripheral seal portion of the packaging bag. (For example, see Patent Documents 4 and 5)
JP-A-62-235080 JP-A-11-171261 JP 2000-62858 A JP-A-11-29181 JP 2004-168430 A

  However, in the packaging containers described in Patent Documents 1 to 3, when filling the contents such as cooked rice and hermetically sealing to form the automatic opening, the sealing tool and the container are displaced, and the protrusion May deviate from a predetermined position. As a result, stress generated inside the container when cooking with a microwave oven is less likely to concentrate on the protruding portion, opening from a seal portion other than the protruding portion, or opening earlier than a predetermined time, There was a problem that the effect of improving the taste of the contents was reduced by the steaming effect.

  As a method for solving such problems caused by misalignment, a protruding portion is provided on the flange portion of the packaging container, and the lid is heat-sealed to the protruding portion, thereby forming a peripheral seal portion or an automatic opening portion. It is conceivable to form a protruding portion. However, when such a method is adopted, when the lid is heat sealed to the protrusion provided on the flange portion, the resin formed by melting the flange portion on the inner side of the container of the heat seal portion A pool may be formed, and the sealing strength of the heat seal portion is increased. As a result, the sealing strength at the inward protruding portion that becomes the automatic opening during cooking with a microwave oven becomes too high and the automatic opening performance decreases, opening from a place other than this protruding portion, or a smooth opening There is a problem that the contents of the container are scattered by explosive opening without being performed.

  Therefore, the present invention eliminates the problems peculiar to a microwave cooking packaging container in which a protrusion is formed over the entire circumference of the flange portion of such a packaging container, and a lid is heat sealed to the protrusion. In addition, the position of the protruding portion inward that becomes an automatic opening generated when the lid is heat sealed is eliminated, and the flange portion melts on the inner side of the container of the protruding portion to form a resin pool. When cooking with a microwave oven, the taste of the contents is improved by the steaming effect, and a microwave cooking packaging container in which the lid automatically opens from the protruding part due to the pressure rise in the container, It aims to provide at low cost.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by making the seal width of the protruding portion wider than the peripheral seal width other than the protruding portion. In a conventional microwave cooking packaging container, the heat seal width of the portion that automatically opens when cooking with a microwave oven is the same width or narrow as other peripheral seal portions in order to facilitate automatic opening. (See, for example, Patent Documents 4 and 5), but the present invention has been completed based on a completely different concept from the conventional container.

That is, in the present invention, the following configurations 1 to 8 are adopted.
1. In a microwave cooking packaging container in which a protrusion is formed over the entire circumference of the flange portion of the synthetic resin container body, and a lid is heat-sealed to the protrusion to seal the container, the heat-sealing portion is directed inward of the container. A microwave oven cooking packaging container characterized in that a projecting portion is formed and a seal width of the projecting portion is wider than a peripheral seal width other than the projecting portion.
2. The packaging container for microwave oven cooking according to 1, wherein a seal width of the protruding portion is 1.2 to 3 times a peripheral seal width other than the protruding portion.
3. 3. The microwave cooking packaging container according to 1 or 2, wherein the protruding portion is formed in a V shape or a U shape.
4). The packaging container for microwave oven cooking according to any one of claims 1 to 3, wherein there is no resin reservoir formed by melting the flange part on the inner side of the container of the heat seal part in the protruding part.
5. The packaging container for microwave oven cooking according to any one of claims 1 to 4, wherein an opening portion that protrudes further toward the outer side of the container is formed on the peripheral seal portion of the packaging container for microwave oven cooking.
6). The microwave oven cooking packaging container according to any one of 1 to 5, wherein the synthetic resin container body is a rectangular container, and the protruding portion and the opening portion are formed at a corner portion of the container.
7). The packaging container for cooking a microwave oven according to 6, wherein the shape of the opening portion is V-shaped.
8). The microwave oven cooking packaging container according to any one of claims 1 to 7, wherein a sealing strength at the protruding portion formed in the heat seal portion is 5 to 30 N / 15 mm.

  ADVANTAGE OF THE INVENTION According to this invention, the position shift | offset | difference of the protrusion part to the inner side used as an automatic opening part at the time of heat cooking which generate | occur | produces when heat-sealing a cover body to a flange part can be prevented reliably. In addition, when the lid is heat-sealed to the protrusion formed on the entire circumference of the flange, the flange is prevented from melting and forming a resin pool on the inner side of the container of the protruding portion. Prevents the heat seal strength of the protrusion that becomes the opening from becoming higher than necessary, improves the taste of the contents due to the steaming effect when cooking with a microwave oven, and the lid reliably protrudes due to the pressure increase in the container It becomes possible to provide the packaging container for microwave oven cooking opened automatically from a part at low cost.

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 polyesters; polyamides such as 6-nylon, 12-nylon and metaxylylenediamine (MX) nylon; various polycarbonates; fluororesins; thermoplastic resins such as polyacetals such as polyoxymethylene Can be mentioned. These thermoplastic resins can be used alone or in combination of two or more, and various additives may be used in combination.

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 films co-deposited on base films such as polyester films and nylon films, nylon 6 / metaxylylenediamine nylon co-extruded films, polypropylene / ethylene-vinyl alcohol copolymer co-extruded films, and polyvinyl alcohol coated polypropylene films , 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 Examples thereof include a coating film, and a hybrid coating material made of an organic resin material and an inorganic material 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) the resin itself uses a resin having an oxygen-absorbing property, or (2) a resin composition in which an oxygen-absorbing agent is blended in a thermoplastic resin having or not having an oxygen-absorbing 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 resin composition (2), when the resin itself has an oxygen-absorbing property or an oxygen-barrier property, oxygen in the container is combined with the oxygen absorbing effect by the oxygen absorbent. This is preferable because it can effectively prevent the intrusion of.

  Examples of the resin itself having oxygen absorptivity include those utilizing an oxidation reaction of the resin. Oxidizing organic materials such as polybutadiene, polyisoprene, polypropylene, ethylene carbon monoxide copolymer, polyamides such as 6-nylon, 12-nylon, metaxylylenediamine (MX) nylon, cobalt as an oxidation catalyst Organic acid salts containing transition metals such as rhodium and copper, and those added with photosensitizers such as benzophenone, acetophenone and chloroketones can be used. 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 of the oxygen absorbents conventionally used for this kind of application can be used, but generally those which are reducible and substantially insoluble in water are preferable. Suitable examples thereof 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 iron carbide, Examples of the main component include one or a combination of two or more of 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. And iron that is electrolytically deposited from an aqueous iron chloride solution obtained in the pickling step, and reduced iron that has been subjected to finish reduction after pulverization can be used.
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 preferably 50 μm or less, particularly 30 μm or less. When transparent or translucent is required, the average particle size is 10 μm or less, particularly 5 μm or less. It preferably has a diameter. 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 oxygen-absorbing resin layers 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 suitable 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 Linear low density polyethylene (LLDPE); vapor-deposited polyethylene terephthalate (PET) / NY / PP-based / PE-based composite material; lidded PET / NY / LLDPE; vapor-deposited PET / NY / polybutylene terephthalate (PBT) -based resin It is done.

Below, based on drawing, the specific example of the packaging container for microwave oven cooking of this invention is demonstrated in detail.
1-5 is a figure which shows one example of the packaging container for microwave oven cooking of this invention, FIG. 1 is a top view of a packaging container, FIG. 2 is a front view of a packaging container, and FIG. It is a partial expansion schematic diagram explaining the process of heat-sealing a cover body to the projection part formed in the flange part. 4 is a schematic cross-sectional view when the packaging container is cooked in a microwave oven, (A) shows a schematic cross-sectional view taken along line AA in FIG. 1, and (B) is a schematic cross-sectional view taken along line BB in FIG. Represents the figure. Further, FIG. 5 is an enlarged schematic diagram for explaining a state in which internal pressure is applied to the resin reservoir formed on the inner side of the heat seal portion when the lid is heat sealed to the protrusion formed on the flange portion.

In this microwave cooking packaging container 1, a rectangular container body 3 having a flange portion 2 is filled with contents (not shown) such as cooked rice, and the lid 4 is heat sealed to the flange portion 2. is there. The flange portion 2 is provided with a protrusion 5 over the entire circumference, and the lid 4 is heat-sealed by the seal head 6 to form the peripheral seal portion 7 (see FIG. 3).
At one corner portion of the packaging container 1, when the packaging container 1 filled with the contents and sealed is heated and cooked in a microwave oven by projecting the peripheral seal portion 7 in a V shape toward the inside of the container. Protrusions 8 that automatically open are provided. Further, an opening 9 is formed at the corner facing the protruding portion 8 by projecting the peripheral seal portion 7 in a V shape toward the outer side.

When a projecting portion 5 is provided on the entire circumference of the flange portion 2 and the sealing portion is formed by heat-sealing the lid body 4 on the projecting portion 5, as shown in FIG. On the other side, the lid body 4 and the flange portion 2 may be melted to form the resin pool 11.
When the resin pool 11 is formed, the internal pressure due to water vapor generated from the contents when the packaging container 1 is heated in the microwave oven acts in a direction perpendicular to the resin pool 11 as shown by the arrows in FIG. As a result, the peel strength of the seal portion is significantly increased. Therefore, when the resin pool 11 is generated, the automatic opening property at the protruding portion 8 is lowered. In the present invention, the formation of the resin reservoir 11 is prevented by making the seal width a of the protruding portion 8 wider than the seal width b of the peripheral seal portion 7 other than the protruding portion 8.

  In a conventional microwave cooking packaging container, the heat seal width of the portion that automatically opens when cooking with a microwave oven is the same width or narrow as other peripheral seal portions in order to facilitate automatic opening. (See, for example, Patent Documents 4 and 5). Contrary to the conventional container, the present inventors have made the resin reservoir 11 by making the seal width a of the protruding portion 8 serving as the automatic opening portion wider than the seal width b of the peripheral seal portion 7 other than the protruding portion 8. The present invention has been completed by finding that the formation of can be prevented.

The seal width a of the protruding portion 8 is preferably about 1.2 to 3 times, particularly about 1.2 to 2 times the seal width b of the other peripheral seal portion 7. By setting the seal width a of the protruding portion 8 in such a range, it is possible to prevent the resin pool 11 from being formed. When the seal width a is smaller than 1.2 times the seal width b, the occurrence of the resin pool 11 cannot be prevented. On the other hand, if it exceeds 3 times, the formation of the resin reservoir can be prevented, but the seal width becomes too wide and the resistance increases, and the automatic opening property of the protruding portion 8 decreases.
The seal strength at the protruding portion 8 is 5 in order to prevent leakage of the contents from the protruding portion 8 during distribution or storage of the packaging container 1 and to ensure automatic opening during cooking by a microwave oven. It is preferable to be about 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.

  At the corner portion facing the projecting portion 8 of the packaging container 1, the peripheral seal portion 7 is projected outward in a V shape, the packaging container 1 automatically opens from the projecting portion 8, and cooking by a microwave oven is performed. After completion, an opening 9 is formed to open the container 1. What is necessary is just to make the seal width in this opening part 9 comparable as the seal width of the peripheral seal part 7. FIG. The shape can be selected as appropriate.

  When the microwave cooking packaging container 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 (see FIG. 4). 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 a U-shape thru | or V shape toward the inner side of a container, but in other parts, the periphery seal part 7 of Peeling does not occur, the internal pressure in the container is maintained, and food such as cooked rice filled in the container is sufficiently steamed to improve the taste.

  When the internal pressure in 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, high-temperature steam blows out from the opening, and the internal pressure decreases and the contents Cooking is complete. The packaging container after cooking is taken out of the microwave oven and can be eaten as it is by opening the lid 4 by hand from the opening portion 9 provided at the corner portion facing the protruding portion 8. At this time, high-temperature water vapor is blown out from the projecting portion 8 that is opened, but since this water vapor blows out in the direction opposite to the opening portion 9, the lid 4 can be safely opened. Moreover, since the internal pressure in the container can be maintained to some extent even after the heat seal portion automatically opens in the protruding portion 8 until the internal pressure decreases, a sufficient steaming effect can be given to the contents.

FIG. 6 is a view showing another example of the microwave cooking packaging container of the present invention, in which (A) is a plan view of the packaging container and (B) is a front view of the packaging container.
The microwave cooking packaging container 21 is filled with a food (not shown) such as cooked rice in a cup-shaped container main body 3 having a flange portion 2 and having a circular cross section, and the lid 4 is heat sealed to the flange portion 2. And seal it. The flange portion 2 is provided with a pair of wide portions 22 and 23 at opposite positions, and one wide portion 22 is formed with a V-shaped protruding portion 8 toward the inner side of the container. Moreover, in the wide part 23 which opposes, the peripheral seal part 7 is protruded in the V shape toward the container outer side direction, and the opening part 9 is formed.

FIG. 7 is a plan view showing still another example of the microwave cooking packaging container of the present invention.
This microwave-cooking packaging container 31 has a peripheral seal portion 7 facing the outer side of the pair of wide portions 22 and 23 provided at positions facing the flange portions in the packaging container 21 of FIG. The opening parts 9 and 9 are formed by projecting in a letter shape. The peripheral seal portion 7 sandwiched between the opening portions 9 and 9 is formed with V-shaped protruding portions 8 and 8 that are wider than the other portions of the peripheral seal portion 7 and go inward of the container. . The other structure of the packaging container 31 is the same as that of the packaging container 21 of FIG.

FIG. 8 is a plan view showing still another example of the microwave cooking packaging container of the present invention.
This microwave cooking packaging container 41 has a V-shape which is wider than the other part of the peripheral seal portion 7 and extends toward the inner side of the pair of opposing corner portions in the rectangular packaging container 1 of FIGS. Protrusions 8 and 8 made of a shaped seal portion are formed. Further, at the other pair of opposite corner portions, the peripheral seal portion 7 is projected in a V shape toward the outer side of the container to form the opening portions 9 and 9. The other structure of the packaging container 41 is the same as that of the packaging container 1 of FIGS.

In each of the above examples, the description has been given of the microwave oven cooking packaging container whose shape of the container main body is a square type and a cup type, but the shape of the container main body or the lid can be appropriately changed, for example, to be oval. It is. Of course, the dimensions can also be set arbitrarily.
The container body and the lid can be manufactured by a conventional method. For example, vacuum forming, pressure forming, vacuum / pressure forming, injection molding, or the like can be adopted as a method for forming the container body.

EXAMPLES Hereinafter, although the Example demonstrates the microwave oven packaging container of this invention further, the following specific examples do not limit this invention.
(Example 1)
In order from the outer layer, polypropylene resin outer layer (thickness 310 μm) with titanium white pigment added to polypropylene with melt index (MI) 0.5 / adhesive layer (thickness 20 μm) made of maleic anhydride-modified polypropylene / ethylene vinyl alcohol Barrier layer made of polymer (thickness 40 μm) / adhesive layer (thickness 20 μm) same as above / polypropylene resin inner layer (thickness 310 μm) of MI = 5, 3 types, 5 layers, total thickness 0.7 mm A multilayer sheet was prepared by ordinary extrusion molding.
Using this multilayer sheet, a flanged square container having a shape shown in FIG. 1 having a container outer dimension of 156 mm × 133 mm and a height of 29 mm (inner volume of about 340 ml) was produced by a normal vacuum / pressure forming machine ( (Flange width: straight portion 8 mm, corner portion maximum 17 mm).

At that time, a protrusion 5 for hermetically sealing the lid 4 is formed over the entire circumference of the flange 2 of the container body, and is opposed to the V-shaped protrusion 8 facing the inner side of the container as shown in FIG. The opening part 9 which protrudes toward the outer side of a container was provided in the corner part to perform. The protrusion width of the peripheral edge seal portion (including the opening portion) was 1.0 mm, and the protrusion width (inner dimension) of the protrusion 8 was 1.2 mm. (Protrusion height: 0.7 mm)

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 ethylene-propylene composite material (inner layer) are used. Then, a polyurethane-based adhesive was interposed between the various resin layers, and a laminated body constituting the lid material by dry lamination was formed by the following procedure.
First, an adhesive is applied to the outer layer material by a gravure roll, etc., the solvent is evaporated and dried in a drying oven at a temperature of 80 to 100 ° C., and the adhesive layer and the intermediate layer material that are in a sticky state are bonded together and heated. After pressure-bonding with the metal roll and the rubber roll, the cooling metal roll is passed and wound. In the same procedure, an inner layer material was bonded to this laminate, and cut into a desired small size to form a lid.
Using a normal aseptic packaging and filling line, after filling the container with 200 g of sterile cooked rice, the lid 4 was heat-sealed on the flange portion 2 of the container at 200 ° C., 1.0 second, 180 kg, and sealed. .

(Example 2)
In Example 1 above, except that the protrusion width of the protruding portion 8 is 1.8 mm, the rectangular container shown in FIG. 1 is produced in the same manner as in Example 1, and 200 g of sterile cooked rice is filled in the same procedure. After that, it was sealed.

(Example 3)
In Example 1 above, except that the protrusion width of the protrusion 8 is set to 3.0 mm, the rectangular container shown in FIG. 1 is produced in the same manner as in Example 1, and 200 g of sterile cooked rice is filled in the same procedure. After that, it was sealed.

(Comparative Example 1)
In Example 1 above, except that the protrusion width of the protruding portion 8 is 1.0 mm, the rectangular container shown in FIG. 1 is produced in the same manner as in Example 1, and 200 g of sterile cooked rice is filled in the same procedure. After that, it was sealed.

(Comparative Example 2)
In Example 1 above, except that the protrusion width a of the protrusion 8 is 3.5 mm, the rectangular container shown in FIG. 1 is produced in the same manner as in Example 1, and 200 g of sterile cooked rice is put in the container in the same procedure. Sealed after filling.

Table 1 shows the results of heating and cooking each of 10 packaging containers filled and sealed with sterile cooked rice obtained in Examples 1 to 3 and Comparative Examples 1 and 2 in a microwave oven with an output of 600 W.
In addition, about the container of Examples 1-3, the seal | sticker strength (average value) which measured the V-shaped protrusion part 8 from the container inner side as follows was the range of 5-30 N / 15mm. On the other hand, the sealing strength of the containers of Comparative Examples 1 and 2 was in the range of 11 to 40 N / 15 mm, and a delamination phenomenon in which the lid member peeled between the layers during the measurement was observed.
(Seal strength)
Fix the container to the container holder, cut the cover material to 15 mm width on both sides of the seal part, fix the cover material on the inner part of the container to the chuck of the tensile tester, and pull upward in the 90 ° direction at a speed of 300 mm / min. Maximum load was measured.

As shown in Table 1, when the protrusion width of the protruding portion 8 in Examples 1 to 3 is wider than the protrusion width of the peripheral edge seal portion 7, no resin pool is formed in the seal portion of the protruding portion 8, and the microwave oven In the heating test, as the internal pressure increased, the seal portion of the projecting portion 8 gradually retreated, and all the steam smoothly escaped from a predetermined position within a predetermined time.
In the comparative example 1 in which the protrusion width of the protrusion 8 is the same as the protrusion width of the peripheral edge seal portion 7, there is a case where a resin reservoir is formed inside the seal portion of the protrusion 8. Some steam escaped from locations other than the protrusions 8 and opened explosively. In the comparative example 2 in which the protrusion width of the protrusion 8 is 3.5 times the protrusion width of the peripheral seal portion, no resin reservoir was formed in the seal portion of the protrusion 8, but the protrusion 8 Some of the seal widths were too wide to increase the resistance, and some steam could not escape from the protrusions 8.
And, compared to the conventional product, the container of the present invention can maintain the sealing property of the container until the protruding part 8 peels off and the steam escapes, compared to the one heated by microwave oven after peeling off the lid. The steaming effect improved the taste of cooked rice.

Example 4
In order from the outer layer, a polypropylene resin outer layer (thickness: 430 μm) in which a titanium white pigment is added to polypropylene having a melt index (MI) of 0.5 / adhesive layer (thickness: 20 μm) made of maleic anhydride-modified polypropylene / ethylene vinyl alcohol Barrier layer made of polymer (thickness: 100 μm) / adhesive layer (thickness: 20 μm) same as above / polypropylene resin inner layer (thickness: 430 μm) of MI = 5, total thickness 1.0 mm A multilayer sheet was prepared by ordinary extrusion molding.
Using this multilayer sheet, a handle having the shape shown in FIG. 6 and having a container outer diameter of 140 mm (handle portion: 165 mm), a height of 45 mm, a flange width of 12 mm, and an internal volume of about 340 ml, using a normal vacuum / pressure forming machine. A round container 21 was produced.

In that case, the projection part 5 for sealingly sealing the cover body 4 was formed over the perimeter of the flange part 2 of a container main body. One wide portion (grip) 22 of the flange portion 2 was provided with a V-shaped projecting portion 8 directed inward of the container, and an opposing wide portion 23 was provided with an opening portion 9 projecting toward the outside of the container. The protrusion width of the peripheral seal portion (including the opening portion) was 1.3 mm, and the protrusion width of the protrusion 8 was 1.6 mm. (Protrusion height: 0.8 mm).
The lid 4 was prepared in the same manner as in Example 1, and after the container 21 was filled with 200 g of curry, the lid 4 was heat sealed on the flange 2 of the container 21 under the conditions of 180 ° C., 1.3 seconds, and 160 kg. And sealed. This curry filled container was retort sterilized at 120 ° C.

(Example 5)
A round container 21 with a handle shown in FIG. 6 was prepared in the same manner as in Example 4 except that the protrusion width of the protrusion 8 was set to 2.5 mm in Example 4, and the container was curled in a similar procedure by 200 g. Was sealed after filling. And the retort sterilization process was performed on the same conditions as Example 4.

(Example 6)
A round container 21 with a handle shown in FIG. 6 was produced in the same manner as in Example 4 except that the protrusion width of the protruding portion 8 was set to 3.9 mm in Example 4, and the curry was placed in the container in a similar procedure by 200 g. After filling, it was sealed. And the retort sterilization process was performed on the same conditions as Example 4.

(Comparative Example 3)
A round container 21 with a handle shown in FIG. 6 was produced in the same manner as in Example 4 except that the protrusion width of the protruding portion 8 was 1.3 mm in Example 4, and the curry was placed in the container in a similar procedure. Was sealed after filling. And the retort sterilization process was performed on the same conditions as Example 4.

(Comparative Example 4)
A round container 21 with a handle shown in FIG. 6 was prepared in the same manner as in Example 4 except that the protrusion width of the protrusion 8 was set to 5.0 mm in Example 4, and the container was curled in the same procedure as in the case of 200 g. Was sealed after filling. And the retort sterilization process was performed on the same conditions as Example 4.

Table 2 shows the results of heating and cooking each of 10 packaging containers filled and sealed with the curries obtained in Examples 4 to 6 and Comparative Examples 3 and 4 in a microwave oven with an output of 600 W.
In addition, about the container of Examples 4-6, the seal strength (average value) which measured the V-shaped protrusion part 8 from the container inner side was in the range of 7-30 N / 15mm. On the other hand, the containers of Comparative Examples 3 and 4 were in the range of 9 to 43 N / 15 mm, and a delamination phenomenon was observed in which the lid material peeled between the layers during measurement.

As shown in Table 2, when the protrusion width of the protrusion 8 in Examples 4 to 6 is wider than the protrusion width of the peripheral seal portion, no resin pool is formed in the seal portion of the protrusion 8, and microwave heating In the test, as the internal pressure increased, the seal portion of the projecting portion 8 gradually retreated, and the steam was smoothly released from the predetermined position within a predetermined time.
In the comparative example 3 where the protrusion width of the protrusion 8 is the same as that of the peripheral seal part, a resin pool is formed inside the seal part of the protrusion 8, and other than the protrusion 8 in the microwave heating test. Some of the contents were blown out of the place. In the comparative example 4 in which the protrusion width of the protrusion 8 is 3.8 times that of the peripheral seal portion, a resin reservoir is not formed, but the seal width of the protrusion 8 is too wide and the resistance increases, and the protrusion Some of the steam did not escape from the part 8.

It is a top view which shows one example of the packaging container for microwave oven cooking of this invention. It is a front view of the packaging container of FIG. It is a partial expansion schematic diagram explaining the process of heat-sealing a cover body to the projection part formed in the flange part of the packaging container of FIG. It is a cross-sectional schematic diagram at the time of cooking the packaging container of FIG. 1 with a microwave oven, (A) represents the cross-sectional schematic diagram in the AA line of FIG. 1, (B) is the cross-sectional schematic diagram in the BB line of FIG. To express. When cooking the packaging container of FIG. 1 with a microwave oven, the enlarged schematic diagram explaining the state to which an internal pressure is applied to the resin reservoir formed in the inner side of the heat seal part is represented. It is a figure which shows the other example of the packaging container for microwave oven cooking of this invention. It is a top view which shows the other example of the packaging container for microwave oven cooking of this invention. It is a top view which shows the other example of the packaging container for microwave oven cooking of this invention.

Explanation of symbols

1, 21, 31, 41 Microwave cooking packaging container 2 Flange part 3 Container body 4 Lid 5 Protrusion part 6 Seal head 7 Peripheral seal part 8 Protrusion part 9 Opening part 11 Resin reservoir 22, 23 Wide part

Claims (8)

  In a microwave cooking packaging container in which a protrusion is formed over the entire circumference of the flange portion of the synthetic resin container body, and a lid is heat-sealed to the protrusion to seal the container, the heat-sealing portion is directed inward of the container. A microwave oven cooking packaging container characterized in that a projecting portion is formed and a seal width of the projecting portion is wider than a peripheral seal width other than the projecting portion.   The packaging container for microwave oven cooking according to claim 1, wherein a sealing width of the protruding portion is 1.2 to 3 times a peripheral sealing width other than the protruding portion.   The packaging container for microwave oven cooking according to claim 1 or 2, wherein the protrusion is formed in a V shape or a U shape.   The packaging for microwave oven cooking according to any one of claims 1 to 3, wherein there is no resin reservoir formed by melting the flange portion on the inner side of the container of the heat seal portion in the protruding portion. container.   The packaging container for microwave oven cooking according to any one of claims 1 to 4, wherein an opening portion that protrudes further toward the outer side of the container is formed on the peripheral seal portion of the packaging container for microwave oven cooking.   The packaging container for microwave oven cooking according to any one of claims 1 to 5, wherein the container body made of a synthetic resin is a rectangular container, and the protruding portion and the opening portion are formed at a corner portion of the container.   The packaging container for microwave oven cooking according to claim 6, wherein the shape of the opening portion is formed in a V shape. The microwave oven cooking packaging container according to any one of claims 1 to 7, wherein a seal strength at the protruding portion formed in the heat seal portion is 5 to 30 N / 15 mm.

Images