JPH06329142A - Deeply narrowed tray-type food container and frozen food package thereof - Google Patents

Abstract

PURPOSE:To provide a water-resistant food container and its frozen food package having hygroscopicity and air permeability wherein contained frozen food can be thawed and heated in a microwave oven. CONSTITUTION:A water-resistant food container and a frozen food package with frozen food put and packaged in the container is provided, wherein a porous structure made of a material mainly containing natural paper pulp fibers is provided, olefin resin is uniformly dispersed among the paper pulp fibers, a wrinkled wall face is provided, a deep tray-shaped food housing is provided whose part along the upper end is a flange, preferably a heat-sealable lid is provided at a part aligning with the flange. Since the container thus has hygroscopicity and air permeability, it can be handled similarly to a paper container. Since it has also water resistance, the contained frozen food can be thawed or heated in a microwave oven.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-resistant deep-drawing tray type food container having hygroscopicity and breathability, and a frozen food package filled and packed with frozen food. Specifically, a food filling section having a deep tray shape and a fine wrinkled wall surface,
And a food made of a moisture-resistant and breathable water-resistant material containing natural or regenerated fibers as a main component, which is composed of a lid body that can be heat-sealed at a flange portion on the upper surface, more preferably at a portion of the flange portion that mates with the flange surface. The present invention relates to a container and a frozen food package in which food is packed.

[0002]

2. Description of the Related Art In the recent development of paper containers, a composite carton occupying the most important position is a bag in carton (bag-
in-carton) or lined carton (li
It is said to be a "red carton" and has a flexible bag inside when the carton is molded.
This is a method of incorporating g). This bag has
Polycelo, polyethylene-coated paper, polyethylene-coated aluminum foil, etc. are used. This type has the advantages of a flexible package and a carton package, and does not need to be packed twice in a carton with only one filling, and the contents are not bulged and difficult to put in the carton. There is also a container formed by molding a laminated body of a synthetic resin film and paper, but since the stretchability during molding is poor, the shape that can be molded is limited to the shallow type.

These paper containers are made of synthetic resin such as polyethylene as the material of the portion which comes into contact with the contents, and like the containers made of synthetic resin, they have water resistance but not hygroscopicity, and have normal air permeability. I don't have a case. That is, moisture resistance,
It can have various features such as waterproof and oil resistance, but naturally, it is not required to have the moisture absorption property, which is the opposite property to the moisture proof property.

A paper material is a representative food container material having both hygroscopicity and air permeability. Paper containers have been used as food containers for a long time, but they have poor water resistance,
Limited to being used for short-term storage of rice ball boxes or moisture-free items.

Since the constituent material of the container made of synthetic resin is an impermeable material that does not allow water or oil to pass through, when food is filled and hermetically packaged, it is heated when reheated and eaten in a microwave oven. At this time, there is a drawback that the internal pressure becomes high due to the steam generated inside and the container is damaged, or the generated steam is condensed and accumulates at the bottom of the container.

During heating, even if a part of the water vapor generated inside is released to the outside, part of it is cooled and condensed. In that case, in the case of a hygroscopic paper container, Since water is absorbed in the container, the condensed water drops do not come into contact with food. However, in the case of synthetic resin,
It is not hygroscopic, and the water droplets that condense on it adhere to foods, causing part of the foods to become damp and spoiling the flavor.

In a container made of such a water resistant material, the structure of the container is changed so as to prevent the condensed water from coming into contact with food, a water absorbing component is inserted, or the seal portion is peeled off. Must be devised so that condensation does not occur.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water resistant food container having hygroscopicity and air permeability. It is an object of the present invention to provide a water-resistant food container having hygroscopicity and breathability, which can thaw or heat a frozen food having a hermetically sealed content in a microwave oven.

[0009]

[Means for Solving the Problems] If it is assumed that a water-resistant container has hygroscopicity, it is natural to try to solve it by the structure of the container or inserting hygroscopic parts as described above. The inventor first thought of improving the water resistance by selecting a material, that is, by mixing a hygroscopic natural or recycled fiber with a synthetic resin.

When a synthetic resin is mixed, the moldability can be improved and a deep tray can be formed even though it is a material containing natural or recycled fibers as a main component. Then, I realized that how to balance hygroscopicity, water resistance and moldability is important.

Various compositions were prepared by considering the combination of recycled fiber and synthetic resin to improve hygroscopicity first, water resistance second, and moldability third. In addition, air permeability was also considered. When molded into a deep-drawing type tray using the prepared composition, molding wrinkles may be generated on the wall surface of the container, and the present invention is advanced in order to contribute to the hygroscopicity of the wrinkles. It came to completion.

The types and proportions of recycled fiber and synthetic resin, and the shape of the food filling portion are important requirements for finely generating fine wrinkles on the wall surface. A small amount of fine wrinkles are also generated on the flange surface of the flange portion on the upper surface, and the heat sealability with the lid is deteriorated. Regarding the lid, it is necessary to improve the heat-sealing property of at least the portion that is fitted to the flange surface.

The material containing natural or regenerated fiber as a main component is composed of 95 to 60% by weight of natural or regenerated fiber and 5 to 40% by weight of olefin resin. When 5 to 40% by weight of the olefin resin is contained in fibers such as pulp, the paper sheet has properties such as curability, water resistance, oil resistance, sealability and stretchability, and as a result, container moldability, for example, 100 m.
It becomes possible to mold to a depth of m or to a complicated shape.

If the olefin resin is not contained in an amount of 5% or more, the paper sheet is hardened so that the shape of the container cannot be sufficiently retained, and water resistance against water and other liquids, oil resistance, and deep drawing are possible. Stretchability cannot be imparted.

Further, ethylene as the olefin resin,
A polymer such as propylene or a copolymer is used. Ethylene polymers are preferred and high density polyethylene is most preferred. Polyethylene has different hardness, elongation and curability depending on the polymerization method and crystallinity, but polyethylene having a specific gravity of 0.935 or more, high crystallinity and high density is preferable. Specific gravity is 0.9
When it is about 35 to 0.95, the elongation is large and the above requirements can be sufficiently satisfied.

The food container of the present invention is prepared by mixing 5-40% by weight of an olefinic resin with pulp or other natural or regenerated fiber and forming it into a sheet shape in advance, and then forming the paper sheet into a desired container shape. Manufactured. When this material is molded into a deep-drawn molded body, particularly in the shape of a deep tray, fine wrinkle-like molded wrinkles are formed on the wall surface of the container. Formed wrinkles are concentrated around the four corners of the container. If the molding wrinkles are uneven and large, the water resistance and the sealing property are poor. Therefore, the conditions for forming the wrinkles uniformly and minutely are adopted.

Since uniform and minute forming wrinkles have minute irregularities, it goes without saying that the filled food product is a lump.
Even if it is a granular material such as cooked rice, it forms an effective rough surface on the wall surface of the container so that it does not stick firmly. Moreover, it promotes water absorption against dew condensation when the frozen food is heated by the microwave oven.

Formed creases are formed on the flange portion, although they are slight. Although the flange surface is small, it becomes a rough surface, so the heat sealability of this surface is slightly degraded. When completely sealing the opening of the food container, it is necessary to improve the heat-sealing property of the portion of the lid body that mates with the flange surface of the flange portion of the lid body. Further, the lid body is also required to have a property capable of being heated in a microwave oven, and is also required to have peeling property.

In the case where the opening of the food container is simply sealed, the internal pressure is somewhat increased by the steam generated inside the package when the microwave oven is heated by utilizing the deterioration of the heat sealing property due to the slightly rough surface of the flange surface. It can be peeled off when the temperature rises.

The lid is of the same quality as the container, a laminated body of paper and plastic film, a polypropylene film, a plastic film such as a laminated film of polypropylene of a vinyl acetate polymer, polyethylene, etc., these plastic films and an aluminum foil. The material such as the laminated film can be adopted.

For example, in the case of the same quality, it is preferable to increase the mixing ratio of the olefin resin, use a heat-sealable adhesive, coat with polyethylene or laminate to improve the heat-sealability. Further, in the case of a laminate of paper and a plastic film, it is preferable to use a laminate of olefin resins mixed with natural or recycled fibers, especially plastic films of the same resin.

The present invention is a food container made of a material satisfying the properties such as moldability, waterproofness, hygroscopicity, breathability, water resistance, heat resistance, sealing property, easy peeling property, and thermal conductivity. The frozen food can be thawed or heated in a microwave oven. The food is not particularly limited, and may be a processed food, a cooked food, or the like, which has been heated. The food package can be heated in a microwave oven for eating, or can be stored in a heat-retaining room under a heated atmosphere and warmed for eating.

The food package can be provided for a vending machine with a built-in microwave oven. The structure of the paper sheet that constitutes the container consists of a structure in which fibrous olefinic resin is uniformly dispersed and intervened between pulp fibers, and the main component is paper pulp fibers, and it has the same porosity as ordinary paper. Since the quality structure is retained, when the frozen food package of the present invention is heated and eaten, it is heated to an appropriate temperature like a paper container and at the same time, it is easy to hold without being too hot when held by hand. It has excellent steam suitability.

[0024]

EXAMPLES The present invention will be described in detail with reference to Examples. EXAMPLE A paper sheet consisting of 10% by weight of natural paper pulp fibers and 90% by weight of polyethylene with a specific gravity of 0.95 was deep-drawn by a female male die to form a deep sheet having a 5 mm flange edge along the circumference of the upper edge. A 40 mm tray type container was prepared. The inner surface of the four corners of this container, whose strength was reinforced by the integral formation of the flange edge, was formed with concentrated drawing stripes, etc.
A molded product having a uniform paper surface was obtained.

Although the bottom of the food storage portion for storing food can be made flat, in order to reinforce the strength of the bottom,
A protruding trapezoidal portion having a height of less than 1.0 mm may be formed on the bottom surface. Further, a shoulder portion may be formed on the inclined wall surface of the food storage unit to increase the strength of the inclined wall surface. The results of the residue inspection of this molded product were n-heptane 14 ppm, 20% ethanol 22 ppm, and distilled water 20 ppm. next,
This molded product was used as a food packaging container.

The food storage section was filled with fried rice, the lid of the laminate of paper and polyethylene film was placed on the food container with the polyethylene film layer facing down, and the flange surface of the flange portion and the lid were heated. The opening of the food container was completely sealed by sealing. Immediately, the completely sealed package was rapidly frozen and stored frozen. One month later, when the frozen food package was completely sealed and heated in a microwave oven, water vapor from the frozen cooked rice was absorbed in the container, and fresh fried rice in a container was obtained. The food container was heated to an appropriate temperature like the paper container, and was not too hot when held by hand, and was in a state that it was easy to hold.

[0027]

EFFECT OF THE INVENTION It is possible to provide a water-resistant food container having hygroscopicity and breathability that can be handled like a paper container. It is possible to provide a water-resistant food container having hygroscopicity and breathability, which can thaw or heat the frozen food of the contents in a microwave oven.

Claims (6)

[Claims] 1. A material composed mainly of natural paper pulp fibers, having the same porous structure as paper in which an olefin resin is uniformly dispersed between paper pulp fibers, and having wrinkled wall surfaces. And a water-tight food container having hygroscopicity and breathability, which has a deep tray-shaped food filling portion in which a portion along the upper edge is a flange. 2. A material composed mainly of natural paper pulp fibers, having the same porous structure as paper in which an olefin resin is uniformly dispersed between paper pulp fibers, and having wrinkled wall surfaces. That it has a deep tray type food filling part where the part along the upper edge is a flange, and that it has a lid that can be heat-sealed at the part that fits with the flange, hygroscopicity and breathability A water resistant food container having: 3. A material mainly composed of natural paper pulp fibers is a material composed of 95 to 60% by weight of natural and / or recycled fibers and 5 to 40% by weight of an olefin resin.
Alternatively, a water-resistant food container having hygroscopicity and breathability according to claim 2. 4. The water-resistant food container having hygroscopicity and air permeability according to claim 1, 2 or 3, wherein the food filling portion is a frozen food filling portion. 5. A frozen food package in which the food filling portion of the food container according to claim 1, 2, or 3 is filled with frozen food and the opening is completely sealed. 6. The frozen food package according to claim 4, wherein the frozen food is frozen cooked rice.