JPH0237555Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a food container for heating and cooking which is mainly made of a synthetic resin foam sheet, and particularly to a food container suitable for heating and cooking in a microwave oven.

BACKGROUND ART Recently, food storage containers that can be directly cooked (including heating treatment) in a microwave oven have been put on the market as packaging containers for various foods. The performances normally desired for such food containers are: (a) heat resistance that does not substantially cause dimensional changes or deformation even when heated while storing food;

(b) It must have enough rigidity to be held by holding one end when food is stored.

(c) It must have enough insulation to be able to be held directly in the hand after cooking.

(d) Stored food retains heat well once heated.

(e) Must have water resistance, oil resistance, and gas barrier properties.

(f) There should be no food hygiene problems.

(g) Give a favorable impression in terms of appearance.

etc.

Conventionally, containers made of a composite material of paper and polyester resin have been used as food storage containers that can be heated and cooked.
It is not completely satisfactory in terms of (b), (c), and (d), and for example, when heated in a microwave oven, the wrapped film may not be able to resist the shrinkage force or water vapor pressure, causing deformation, or it may not be able to be handled by hand immediately after cooking. It has the disadvantages that it becomes hot and difficult to handle when held in a cup, and that heated food tends to cool down easily. Furthermore, since the base material of the container is paper, it is necessary to overlap the corner portions in order to make it into a container shape during manufacturing. There was a problem in that the container was difficult to manufacture.

Therefore, the inventors of the present invention attempted to develop a food container that can be heated and cooked directly, and which does not feel hot even when held in the hand immediately after cooking, and which retains its shape. A study was conducted assuming that synthetic resin foam was not used. Synthetic resin foams such as polystyrene resin foam sheets have traditionally been used for containers and various other uses.
There is no food container on the market that can be heated directly in a microwave oven. This is because polystyrene resin foam, which is often used in containers such as cutlet ramen, does not have sufficient heat resistance, and although it has no problems with rigidity and shape retention at room temperature, it becomes extremely rigid when heated. This is because other foams with good heat resistance are expensive and difficult to mold into a container shape.

In view of the above, as a result of further research and consideration, the present invention was developed using a foamed sheet made of a mixed resin of polystyrene resin and inorganic filler, which has excellent rigidity and heat resistance, and has sufficient rigidity and shape retention even when heated. The company discovered that the heat-resistant mixed resin can retain its properties, and was able to use it in food containers.In particular, by laminating a synthetic resin film with oil resistance and gas barrier properties on a foamed sheet of the heat-resistant mixed resin, The purpose of the present invention is to provide a food container that compensates for the weaknesses of foam sheets, has heat resistance, oil resistance, and other properties, and is suitable for cooking.

That is, the present invention uses polystyrene resin 50~
Inorganic filler 50 consisting of 89% by weight and at least one kind of silicon compound such as talc, calcium carbonate, magnesium carbonate, calcium sulfate, mica, etc.
Foaming ratio made from mixed resin with ~11% by weight
Abstract: A food container for heating and cooking that is integrally formed from a composite sheet made by laminating a synthetic resin film with relatively oil resistance and gas barrier properties on at least one side of a foam sheet with a thickness of 1.5 to 10 times and a thickness of 0.5 to 5.0 mm. That is.

Next, embodiments of the present invention will be described based on the drawings.
In the figure, A indicates a food container according to the present invention,
A composite sheet is made of a composite sheet in which a synthetic resin film 2 having relatively oil resistance and gas barrier properties is laminated on at least one side of a foamed sheet 1 obtained by extrusion and foam molding a mixed resin of a polystyrene resin and an inorganic filler, This is integrally formed into a desired container shape by appropriate forming means such as press molding or vacuum forming.

The composite sheet that is the constituent material of food container A has synthetic resin films 2 on both sides of the foam sheet as shown in the figure.
Alternatively, a synthetic resin film can be laminated on only one side, but at least the film laminated on the inner surface of the container will not have any adverse effects (for example, dissolution, infiltration, etc.) due to the cooking oil that occurs during heating. This is preferable from the standpoint of preventing. In addition to the shape shown in FIG. 1, the shape of the container may be any other shape such as that shown in FIG. 3 or 4 depending on the form of the food or dish to be stored.

The mixed resin that is the material of the foam sheet 1 above is
It consists of a polystyrene resin and an inorganic filler, but in addition to polystyrene resin, the polystyrene resin includes copolymer resins of styrene and maleic anhydride, other styrene-based copolymers, AS resins, and ABS. Examples include resins, among which copolymer resins of styrene and maleic anhydride are more preferable because of their high heat resistance. As the inorganic filler, silicon compounds such as talc, calcium carbonate, magnesium carbonate, calcium sulfate, mica, and other known inorganic fillers can be used.
These can be used alone or in combination. The mixing ratio of this mixed resin is 50 to 89% by weight of polystyrene resin and 50% by weight of inorganic filler.
If the inorganic filler exceeds 50% by weight in the mixed resin, the heat resistance and rigidity of the resulting foam sheet will improve, but the foam moldability and sheet moldability will be poor and the desired container will not be obtained. If it is less than 4% by weight, foam moldability and sheet moldability are good, but the resulting container has insufficient heat resistance and rigidity, making it difficult to handle after cooking in a microwave oven. This is not desirable. In addition, this mixed resin contains various known additives as necessary.

Further, the foamed sheet 1 needs to have a foaming ratio of 1.5 to 10 times and a thickness of 0.5 to 5 mm. In other words, if the foaming ratio exceeds 10 times, the thickness should be reduced to 5 mm.
Even if the thickness of the laminated film is made relatively thick, the rigidity will be insufficient and deformation will easily occur when holding one end while food is stored, and if it is less than 1.5 times, the insulation will be insufficient and it will be difficult to handle after cooking. Traditional paper-
It is inappropriate because it is almost the same as a polyester container. Furthermore, if the thickness exceeds 5 mm, thermoformability deteriorates and it becomes difficult to mold into a container shape, and if the thickness is less than 0.5 mm, it is still unsuitable in terms of heat insulation and rigidity. Such expansion ratio and thickness can be set by changing the extrusion foam molding conditions.

The synthetic resin film 2 to be laminated on the foamed sheet 1 is one that has oil resistance and gas barrier properties (including barrier properties against moisture and steam), has good moldability, and does not substantially deform during cooking. It will be done. Specifically, polyolefin resin films such as polyethylene, polypropylene, and polymethylpentene with a melting point of 120°C or higher, polyester resin films, polyamide resin films, and polyvinylidene chloride resin films can be used. Resin films are preferred in terms of oil resistance, gas barrier properties, moldability, etc., and unstretched polypropylene films and polymethylpentene films are particularly preferred. Moreover, the film can also be used in multiple layers.

In addition, the thickness of the synthetic resin film 2 is 10 to 500 mm.
Preferably, it is in microns. If the thickness is too thin, the effect of laminating the films, ie, oil resistance and gas barrier properties, will be reduced, which is undesirable, and if it is too thick, the container itself will be heavy and undesirable in terms of cost. Such films are useful for increasing the rigidity of food containers. Therefore, the expansion ratio of the base foam itself can be increased compared to that of a single foam, and a food container that is more preferable in terms of heat insulation properties can be obtained.

Note that the foamed sheet 1 of the synthetic resin film 2
The lamination may be performed by heat fusion or by interposing an adhesive between the two.

The food container for heating and cooking of the present invention having the above structure has extremely excellent rigidity and heat resistance because the foam sheet 1, which is the main component thereof, is made of a mixed resin of polystyrene resin and inorganic filler. The foamed sheet 1 has sufficient rigidity and shape retention even when heated, and of course has good heat insulation properties.Moreover, the foamed sheet 1 is laminated with a synthetic resin film 2 having oil resistance and gas barrier properties. It also has good properties such as oil resistance and gas barrier properties, which are important elements for food containers, and is also excellent in preserving food and protecting foam sheets. Therefore, the above-mentioned performances (a), (b), (c), (d), (e), (
It satisfies both (f) and (g), and can be suitably used as a food container that can be heated and cooked directly in a microwave oven. Furthermore, the composite sheet has good molding processability, and even complex tray-shaped containers can be easily molded, allowing for mass production and being provided at a relatively low cost.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, in which Fig. 1 is a perspective view, Fig. 2 is an enlarged cross-sectional view taken along the line - front figure, and Figs. 3 and 4 are parts of containers with different shapes. It is a cutaway perspective view. A...Food container, 1...Foam sheet, 2...Synthetic resin film.

Claims (1)

[Scope of utility model registration request] Polystyrene resin 50-89% by weight, talc,
A foaming ratio of 1.5 to 10 times and a thickness of 0.5 to 5.0, made of a mixed resin with 50 to 11% by weight of an inorganic filler consisting of at least one type of silicon compound such as calcium carbonate, magnesium carbonate, calcium sulfate, or mica.
A food container for heating and cooking, which is integrally formed from a composite sheet in which a synthetic resin film having relatively oil resistance and gas barrier properties is laminated on at least one side of a foam sheet having a diameter of 1 mm.