JPH0519171U - Food packaging - Google Patents

Abstract

(57) [Summary] [Objective] To provide a food package in which water vapor generated when heated in a microwave oven does not adhere to food even if dew condensation occurs, and does not expand or burst when heated. [Structure] A food package in which an air-impermeable sheet is used as an outer layer, a water-absorbent fiber sheet is used as an intermediate layer, and a hydrophobic sheet having an air permeability of 10 cc / cm ² / sec. It is a body and is generated by forming a portion where substantially only the surface layer is bonded between the impermeable sheet and the water absorbing fiber sheet and / or between the water absorbing fiber sheet and the hydrophobic sheet in the sealed portion. A part of water vapor is easily discharged from the seal part.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a food package such as a hamburger or okonomiyaki that can be heated directly by a microwave oven.

[0002]

[Prior Art]

 In recent years, due to the diversification of foods, fast foods that can be easily eaten, especially foods such as hamburgers, hot dogs, and okonomiyaki, have become widespread. Recently, most of these foods are hermetically sealed with an impermeable sheet such as a film that does not pass water or oil, and are eaten by reheating in a microwave oven. Due to the generated steam, the internal pressure increases and the food package expands and bursts. For this reason, there has been proposed a device (described in Japanese Patent Laid-Open No. 3-148473) in which the sealing strength of the heat-sealed portion of the package is reduced to some extent and the sealed portion is peeled off when the internal pressure of the package is increased to some extent. ing.

[0003]

[Problems to be solved by the device]

 However, since the seal part of the above-mentioned part peels off all at once, sauce and ketchup, etc. may squirt.In addition, freshly cooked warm hamburgers, etc. may be wrapped in an impermeable sheet or placed in a microwave oven. When heated, the generated water vapor is cooled by the outside air and condenses inside. Depending on the type of food, condensed water droplets may adhere to the flavor and change the shape. Some of the packaging materials also use a water-absorbent sheet on the inner surface. In this case as well, the water droplets that condense are retained on the water-absorbent sheet, but the same results are obtained because the food comes into contact with the wet sheet. The inventors of the present invention have completed the present invention as a result of intensive studies to solve the above problems.

[0004]

[Means and Actions for Solving the Problems]

The present invention is a food package in which a food is packaged by hermetically sealing an impermeable sheet as an outer layer, a water-absorbent fiber sheet as an intermediate layer, and a hydrophobic sheet as an inner layer in contact with the food, and the hydrophobic sheet is 10 cc / cm 2. ^It has an air permeability of ² / sec. Or more, and at the seal portion, the air-impermeable sheet and the water-absorbent fiber sheet and / or the water-absorbent fiber sheet and the water-phobic sheet are bonded substantially only by the surface layer. The food package is characterized in that the formed portion is formed.

[0005] Packaging materials for use in the present invention is made of at least three layers, with the inner layer in contact with food, air permeability JIS L-1096 A method at 10cc / cm ² / sec. Or more, preferably 20 cc / cm ² A / sec. Hydrophobic sheet is used. If the air permeability is less than this value, the water vapor generated by the food cannot be sufficiently diffused to the side of the water-absorbent fiber, which not only makes it difficult to peel off the seal portion as described later, but also makes the food surface wet. Will be things. The water-repellent sheet has a water resistance of JIS L-109 2 A in order to prevent water absorbed by the water-absorbent fiber sheet as the intermediate layer from returning to the inside of the hydrophobic sheet and wetting the food surface. It should be 5 cm or more, preferably 10 cm or more by the method. Further, an impermeable sheet is used as the outer layer. The use of this impermeable sheet prevents the food from drying out abnormally and prevents the juices such as sauces, ketchup and butter from seeping outside.

The hydrophobic sheet used as the inner layer may be made of any material as long as it satisfies the air permeability (and also the water resistance), but from the viewpoint of food safety, no additives or treatment agents are used. basis weight 3 to 50 g / m ² average fiber diameter that can satisfy the water resistance and air permeability at 10μ or less, preferably melt blown nonwoven polyolefin down resins such as polyethylene and polypropylene 5 to 30 g / m ² is preferably used. When heating in a microwave oven, polypropylene having a high melting point is more preferable from the viewpoint of heat resistance. Basis weight hardly be obtained if sufficient water resistance of ² hereinafter 3 g / m, a basis weight of 50 g / m ² or more is not economical with transparent steam reduced. Further, the hydrophobic sheet may be a microporous film. Such a film can be produced by, for example, stretching a film containing fine particles to form fine holes.

The water-absorbent fiber sheet is for absorbing the water vapor generated by food passing through the hydrophobic sheet of the inner layer and being cooled on the inner surface of the outer layer to cause dew condensation to form water droplets. It is possible to use synthetic fibers that have been hydrophilized as long as they have a certain amount of properties, but from the viewpoint of safety when used in food products, they do not contain additives or treatments, and are themselves water-absorbing and hygroscopic. A nonwoven fabric produced by a dry method or a wet method of cellulose fibers such as pulp fibers having high water retention and regenerated cellulose fibers is preferable. As long as the amount is small, heat-fusible synthetic fibers may be mixed and used for reinforcement as long as water absorption is not impaired. The basis weight of the non-woven fabric is preferably 5 to 50 g / m ² . If the basis weight is less than 5 g / m ² , sufficient water absorption capacity cannot be obtained. If the basis weight is greater than 50 g / m ^2, there is no problem with water absorption capacity, but the entire sheet becomes too thick and the heat sealability is poor. Become.

The impermeable sheet used for the outer layer is a sheet that does not exude water or oil to the outside, and is made by thinly laminating polyethylene or polypropylene on paper such as thin paper, or by itself or by laminating polyethylene, polypropylene or polyester. A film or the like is used, but a film obtained by laminating polyethylene or polypropylene on a paper such as thin paper is preferably used from the viewpoints of ease of printing on the surface, heat sealability and the like. Although a sheet laminated with aluminum foil is impermeable, it cannot be heated in a microwave oven, which is not preferable, but it may be partially used as a design in a small area. In this case, it is necessary to consider the position and size so that the food inside does not become a heat spot.

In the packaging material used in the present invention, the hydrophobic sheet, the water-absorbent fiber sheet and the air-impermeable sheet may be simply laminated, or may be laminated and integrated. For example, each sheet can be separately fed to a bag-making machine to package and seal food at the same time as bag-making. However, when the packaging material is processed into a bag beforehand and the food is put in the bag and sealed, at least the area around the opening of the bag should be dotted, linear, etc. for ease of handling. It is preferable that the shape is adhered and integrated by a method such as heat embossing or ultrasonic welding. Bonding only around the opening of the bag complicates the structure of the bag making machine, so it is easy to combine and integrate the entire sheet.

In the composite integration of the respective sheets, it is preferable that the impermeable sheet and the water-absorbent fiber sheet are not in intimate contact with each other over the entire surface from the viewpoint of preventing dew condensation on the inner surface of the hydrophobic sheet. It is preferable to partially adhere in the form of dots, lines, or intermittent lines by a method such as sonic welding. In this case, the water-absorbent fiber sheet and the hydrophobic sheet may be previously lightly bonded to each other by a flat calendering treatment within a range not impairing air permeability and water absorption. In the case of partial bonding, the area of the bonded part is generally in the range of 1 to 30% in terms of balancing water absorption, air permeability, strength, etc., but it is different depending on the basis weight of each sheet and limited to this range. However, it is preferable that the distance between the adhesive parts is wide as long as it does not hinder the handling. In any case, it is preferable that both sheets are joined only by the surface layers that are in contact with each other, and if the melt of the hydrophobic sheet enters even inside the water-absorbent fiber sheet, peeling of the sealing portion described below will occur. Hateful.

Then, the composite sheet is cut into a square or rectangular shape into a sheet shape, a bag shape with two or three sides closed, or a box shape using a cardboard laminated to the outer layer to form a hamburger. Foods such as hot dogs, fried chicken, french fries, okonomiyaki, takoyaki and yakisoba are packed and hermetically sealed. The bag can be gusseted if necessary. In the case of a box-shaped container, a foldable type is more preferable because it has a small storage space when not in use and can be stacked and stored when food is packaged, which makes it easy to handle.

In the present invention, as shown in FIG. 1, at least a part of the portion 5 to be heat-sealed is provided between the outer layer impermeable sheet 1 and the water absorbent fiber sheet 2 and between the water absorbent fiber sheet 2 and the hydrophobic sheet. It is necessary that only the surface layers 6 and 6'which are in contact with each other during the period 3 are in contact with each other. To this end, when forming the laminated sheet as described above and when joining the impermeable sheet of the outer layer and the laminated sheet, it is essential that the respective sheets are joined substantially only by the surface layer. In addition to the necessity, under the condition that an excessive pressure is not applied when the food 7 is put in and heat-sealed, and the melted and softened product of the impermeable sheet 1 and the hydrophobic sheet 3 does not enter the water absorbent fiber sheet 2. It is necessary to form a heat-sealed part. This condition is appropriately determined depending on the material and thickness of each sheet. The heat-sealing structure does not have to exist entirely, and may be partial.

[0013]

[Action]

 According to the structure of the present invention, when the food package is heated, the water vapor generated inside passes through the hydrophobic sheet and is transferred to the water-absorbent fiber sheet and is retained as water droplets, which causes inconvenience due to dew condensation inside the package. Further, as shown in FIG. 2, a part of the water vapor is gradually discharged to the outside through the water absorbent fiber sheet 2 of the seal portion 5, and the water absorbent fiber sheet 2 absorbs a certain amount of water or more. Upon absorption, the surface layer 6 or 6'between the water-absorbent fiber sheet 2 and the impermeable sheet 1 or the hydrophobic sheet 3 at the seal portion is easily partly peeled off, and this portion is opened and vaporized. Escape. Therefore, the package expands to some extent when heated, but does not burst. The contents are completely sealed by the hydrophobic sheet 3 and never come out of the packaging bag.

[0014]

【Example】

Further, the present invention will be described with reference to specific embodiments. Example 1 An ultrafine fiber nonwoven fabric having an average fiber diameter of 3μ obtained by melt-blowing polypropylene, a basis weight of 10 g / m ² , an air permeability of 25 cc / cm ² / sec., And a water pressure resistance of 10 cm, and a basis weight of wood pulp processed by a papermaking method. A laminated sheet was prepared by laminating 20 g / m ² of non-woven fabric and performing pinpoint embossing. The area of the bonded part by embossing was about 25%. This laminated sheet and thin paper laminated with polyethylene with a thickness of about 10μ are placed on top of each other so that the non-woven fabric side and the polyethylene side are in contact, and folded in two so that the side of the melt-blown non-woven fabric is on the inside. Then, both sides were heat-sealed to form a bag, and a freshly cooked hamburger was placed in this bag and the opening was heat-sealed to seal the food.

When the bag is made or sealed after food is sealed, the heat seal condition of one place (one side) is from standard condition of seal temperature of 270 ° C., speed of 35 m / min (contact time of 1 second) to seal temperature of 250 ° C. , The speed was changed to 35 m / min (contact time 1 second), and the melt of the impermeable sheet or hydrophobic sheet did not penetrate into the absorbent fiber sheet, and only the surface sheet was used to join the sheets. I was doing it. At this time, the peel strength of the heat-sealed portion was 0.5 kg / 5 cm under the standard conditions, whereas it was 20 g / 5 cm under the mild conditions.

When this hamburger package was placed in a microwave oven and heated, it expanded to some extent after the start of heating, but after that, some peeling was observed at the part of the water-absorbent fiber sheet layer of the heat seal part, and the package did not burst. It was However, the hamburger was sealed with a hydrophobic sheet and there was no leakage of ketchup.

[0017]

[Effect of the device]

 The food package of the present invention has the following advantages. The packaging bag does not burst during microwave heating. Warm freshly cooked hamburgers and other foods do not cause condensation inside the package and do not wet the surface of the bread to reduce the flavor. The sauce, ketchup, butter, etc. will not seep outside and stain your hands and clothes. When the food is cooled, even if it is reheated by a microwave oven, the steam generated does not condense, and it is possible to obtain a warmed food with a good flavor. Since it has a non-woven fabric layer, it has high heat retention and can keep food warm for a long time. Furthermore, by using cardboard to form a box, it is possible to stack and store the food without deforming it.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a food package according to the present invention.

FIG. 2 is an enlarged end view of the seal part during heating.

FIG. 3 is a sectional view (partial view) taken along the line AA ′ of FIG.

[Explanation of symbols]

 1 Impermeable Sheet 2 Water-Absorbent Fiber Sheet 3 Hydrophobic Sheet 4 Laminated Sheet 5 Sealing Part 6 Bonding Surface Layer of Impermeable Sheet and Water-Absorbing Fiber Sheet 6'Jainting Surface Layer of Water-Absorbing Fiber Sheet and Hydrophobic Sheet 6 " Bonding layer of hydrophobic sheet

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Nobuo Hatta 1-2-1 Kaigandori, Okayama-shi Kuraray Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A food package in which a food is packaged and hermetically sealed by using an impermeable sheet as an outer layer, a water absorbent fiber sheet as an intermediate layer, and a hydrophobic sheet as an inner layer in contact with the food, wherein the hydrophobic sheet is 10 cc / It has an air permeability of cm ² / sec. or more, and substantially only a surface layer is provided between the impermeable sheet and the water absorbing fiber sheet and / or between the water absorbing fiber sheet and the hydrophobic sheet in the seal portion. A food package, wherein a joined portion is formed.