JPH0423772Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to packaging containers for instant food and beverages, etc., and is suitable as a one-way food container that requires oil resistance, water resistance, heat resistance, heat insulation, etc. We aim to provide something.

[Conventional technology]

In recent years, food containers with various configurations have been put on the market as containers for storing various instant foods, pouring boiling water over them, or heating them in a microwave oven before eating.

Molded containers based on expanded polystyrene sheets or expanded polystyrene beads have excellent heat insulation and rigidity, and have been widely used as containers for instant foods that are eaten by pouring hot water into them.

However, with the diversification of stored foods, microwave ovens are being used to heat and cook such foods, and physical property requirements such as heat resistance for food containers are becoming stricter every year.

However, in recent years, containers using various heat-resistant resins,
For example, containers made of filler-containing polypropylene, containers made of low-foam polypropylene, containers made of polymethylpentene, and various paper containers based on paper coated with a heat-resistant polyolefin resin have been developed.

Containers made of crystallized polyethylene terephthalate have also been developed, which have improved heat resistance by crystallizing the material during thermoforming.

[Problem that the invention attempts to solve]

As mentioned above, conventional containers made of heat-resistant plastics have excellent oil and heat resistance, but they have poor insulation properties, and the contents can be damaged by being poured with boiling water or heated in a microwave oven. As the temperature of the container increases, the outer surface of the container becomes too hot to hold with bare hands.

In addition, paper-based containers may have poor water resistance, and paper has a higher dielectric loss than ordinary plastic, and it easily generates heat due to high frequencies, so it may self-heat when cooking in a microwave oven. It may deteriorate.

Containers made of crystallized polyethylene terephthalate have particularly excellent heat resistance, but have lower productivity than other plastic containers, and are problematic as general-purpose one-way containers.

Heat-resistant polyolefin containers alone have the disadvantage of low rigidity, making them dangerous to handle with bare hands especially when the temperature of the contents reaches around 100°C, making them inconvenient as containers for eating and drinking.

In order to overcome these drawbacks, it may be possible to make the wall thickness of the container sufficiently thick, but this poses problems in terms of raw material cost and productivity.

[Means for solving problems]

The purpose of this invention is to eliminate the drawbacks of the above-mentioned conventional techniques, and to provide a food packaging container that is excellent in heat resistance, oil resistance, water resistance, and heat insulation, exhibits appropriate rigidity, and is highly versatile. It is something.

In order to achieve the above object, the container of the present invention is made of a heat-resistant polyolefin container whose outer surface and part of the outer bottom are made of a heat-shrinkable heat-shrinkable polystyrene foam sheet and a heat-shrinkable transparent plastic film with a printed layer interposed therebetween. It is characterized by being tightly covered with heat-shrinkable laminated sheets laminated together.

The structure of the food container according to the present invention will be explained with reference to the drawings.

FIG. 1 is a cross-sectional view of a laminated sheet 1 forming the outer layer of the food container of the present invention, which has a heat-shrinkable property showing heat-shrinkability in the take-off direction, obtained by extrusion foam molding using a heat-resistant polystyrene resin as a raw material. A polystyrene resin foam sheet 1a is printed in advance to form a printed layer 1d, and a heat-shrinkable transparent plastic film 1b exhibiting a heat shrinkage rate equivalent to that of the foam sheet 1a is aligned in the direction of heat shrinkage. It is layered in a similar manner.

The heat-resistant polystyrene resin used in the present invention is a polystyrene resin with a heat distortion temperature higher than 95°C, such as styrene-methacrylic acid copolymer resin, styrene-maleic anhydride copolymer resin, styrene-maleimide copolymer resin, etc. Examples include polymer resins, polyparamethylstyrene resins, etc. alone or in mixtures. The plastic film is a film that exhibits heat shrinkage equivalent to that of the foamed sheet of the base material, and includes, for example, a polystyrene resin film, a polyolefin resin film, and a polyvinyl chloride resin film.

FIG. 2 shows a sleeve 3 made of the laminated sheet 1 attached to a heat-resistant polyolefin container 2 that is a base material.
FIG.

The sleeve 3 is the foam sheet 1 of the laminated sheet 1.
The laminated sheet 1 is wound and joined so that the heat shrinkage direction of the laminated sheet 1 coincides with the circumferential direction of the sleeve 3, and the inner diameter of the sleeve 3 is equal to the maximum outer diameter of the polyolefin container 2, with a facing inside. It is something that

The polyolefin container 2 covered with a sleeve 3
is fitted into a mandrel 4 that can be internally cooled, and while the polyolefin container 2 is cooled by the mandrel 4, only the sleeve 3 is heated and contracted, so that the sleeve 3 tightly covers the heat-resistant polyolefin container 2. Then, a food container according to the present invention is formed.

FIG. 3 is a cross-sectional view of the food container of the present invention, in which a part of the outer surface and outer bottom of the polyolefin container 2 is closely covered with a laminated sheet 1 consisting of the foam sheet 1a and a printed transparent plastic film 1b. ing.

[Effect of idea]

Since the food container according to the present invention has an inner layer made of a heat-resistant polyolefin container, the inner layer has superior heat resistance and oil resistance compared to, for example, polystyrene. In addition to its excellent water resistance, it does not generate self-heating and is highly suitable for heating in a microwave oven.

In addition, the outer layer is made of a heat-insulating laminated sheet, so even if the temperature of the contents reaches 110°C after heating, the temperature of the outer surface of the food container will not exceed 80°C. Due to its low conductivity, it does not feel hot even when held with bare hands, making it easy to handle.

Furthermore, since the heat-resistant polyolefin container is reinforced with a laminated sheet made of a heat-resistant polystyrene resin foam sheet as a base material, it is provided with rigidity that cannot be obtained with a heat-resistant polyolefin container alone, and there is no safety problem.

Furthermore, since the outer layer includes a foam sheet, there is an advantage that the cold shock resistance required during frozen storage can be improved.

Furthermore, because the laminated sheet is laminated with a foam sheet through a printing layer formed on a transparent plastic film, precise and beautiful printing is possible, and the outermost layer of the container is made of a transparent plastic film. It has an excellent design, with a highly glossy appearance.

As described above, the present invention has sufficient heat resistance, water resistance, and oil resistance to be used as an instant food container for serving by pouring boiling water into it, and as a heating container for cooking instant foods and frozen foods using a microwave oven. It has the advantage of being durable, rigid, and heat insulating, and can be printed with beautiful prints, so it has the advantage of stimulating people's desire to purchase it, so it has practical value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heat-shrinkable laminated sheet, FIG. 2 is a sectional view of a sleeve attached to a heat-resistant polyolefin container, and FIG. 3 is a sectional view of a food container. In the figure, 1... Heat-shrinkable laminated sheet, 1a... Heat-shrinkable polystyrene resin foam sheet, 1b... Printed heat-shrinkable transparent plastic film,
1c...Heat-shrinkable transparent plastic film, 1
d...printing layer, 2...heat-resistant polyolefin container, 3...sleeve, 4...mandrel.

Claims (1)

[Claims for Utility Model Registration] 1. A heat-shrinkable laminated sheet 1 is closely attached to the outer surface of a container 2 made of heat-resistant polyolefin, and the laminated sheet 1 has a heat-shrinkable polystyrene resin foam sheet 1a and a heat-shrinkable transparent sheet 1a. A food container characterized in that a plastic film 1c is laminated such that a heat-shrinkable polystyrene foam sheet 1a is in contact with a heat-resistant polyolefin container 2 via a printed layer 1d. 2. The food container according to claim 1, wherein the heat-shrinkable polystyrene resin is a heat-resistant polystyrene resin. 3. The food container according to claim 1, wherein the heat-shrinkable plastic film is made of polystyrene resin, polyolefin resin, or polyvinyl chloride resin.