JP2000025170A - Polyolefinic foamed sheet and container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyolefinic foamed sheet withstanding the heating by a microwave oven and a container using the same. SOLUTION: A polyolefinic foamed sheet 11 is constituted by laminating a polypropylene(PP) layer 15 to one surface of a polystyrene(PS) layer 13 being an intermediate layer through an adhesive layer 14 and laminating polystyrene paper(PSP) to the other surface of the intermediate layer. A container is produced by thermally molding this polyolefinic, foamed sheet 11 so that the polypropylene layer 15 becomes an inner layer and the polystyrene paper 16 becomes an outer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyolefin foam sheet and a container using the same.

[0002]

BACKGROUND ART Conventionally, polystyrene paper (PSP) has been used as a tray for meat and fish sold in supermarkets and the like. Since such a PSP is inferior in heat resistance, the tray made of the PSP could not be heated in a microwave oven while the food was placed on the tray. On the other hand, if the container is made of expanded polypropylene, for example, there is no problem in both heat resistance and oil resistance, but the expansion ratio is smaller and more expensive than PSP.

[0003] In order to solve such disadvantages, Japanese Patent Laid-Open No.
JP-A-99506 proposes a laminated sheet having a configuration in which a styrene-based resin foamed sheet is used as an intermediate layer, a styrene-based resin non-foamed film is laminated on one side, and a polypropylene non-foamed film is laminated on the other side. ing. In the case of a container using this laminated sheet, the rigidity is insufficient because the intermediate layer is a styrene resin foam sheet. Also, since the styrene resin foam sheet is located in the middle layer,
In particular, when heated in a microwave oven or the like, deformation due to heat is likely to occur.

Accordingly, an object of the present invention is to provide a polyolefin foam sheet that can withstand heating by a microwave oven or the like and a container using the same.

[0005]

The polyolefin foam sheet according to the first invention of the present invention is made of polystyrene (PS).
With the layer as an intermediate layer, a polypropylene (PP) layer is laminated on one side of the intermediate layer via an adhesive layer, and polystyrene paper (PSP) is laminated on the other side of the intermediate layer. It is characterized by.

As the adhesive for the adhesive layer, a mixture of an EVA resin and a terpene resin can be used. The PS
The layer and the PSP are thermally laminated. In the case of a container thermoformed so that the PP layer is on the inner layer side and the PSP is on the outer layer side, the PP layer is on the inner layer side, so that it has moisture resistance, oil resistance and heat resistance.

On the other hand, since the PSP is located on the outer layer side, the PSP has heat insulation properties. For example, it is possible to hold the container immediately after being heated by a microwave oven or the like. Moreover, since it is a PSP, it is less expensive than foamed polypropylene. Further, P
Since the S layer is an intermediate layer, the rigidity of the container can be increased. Further, when the contents are put in a container and heated by a microwave oven or the like, even if the temperature up to the intermediate PS layer becomes high due to the transfer of heat from the inside, deformation due to heat does not occur.

The polyolefin foam sheet according to the second invention of the present invention is the polyolefin foam sheet according to the first invention, wherein the polystyrene layer has a thickness of 0.05 mm to 2.00 mm, the polypropylene layer has a thickness of 10 μm to 500 μm, Thickness
It is characterized by being set to 0.1 mm to 2.0 mm. The reason why the thickness of the polystyrene layer is 0.05 mm to 2.00 mm is that if the thickness is less than 0.05 mm, sufficient rigidity cannot be obtained, and if it exceeds 2.00 mm, the thickness of the entire sheet becomes too thick.

The thickness of the polypropylene layer is 10 μm to 500 μm.
The reason why the thickness is set to μm is that if it is less than 10 μm, the strength as a layer becomes weak, and if it exceeds 500 μm, the cost increases.
The reason why the thickness of the polystyrene paper is 0.1 mm to 2.0 mm is that if the thickness is less than 0.1 mm, the heat insulating property is insufficient, and if it exceeds 2.0 mm, the thickness of the entire sheet becomes too thick.

The container according to the third invention of the present invention uses the polyolefin foam sheet according to the first or second invention, and is thermoformed so that the polypropylene layer is on the inner layer side and the polystyrene paper is on the outer layer side. It is characterized by being manufactured by. Although the specific example of the container is arbitrary, it has a sufficient heat resistance, and thus is suitable as, for example, a food container accompanied by heating in a microwave oven. Specifically, the thermoforming is performed by heating the foamed sheet with a heating means and then shaping the softened foamed sheet into a predetermined shape using a mold.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A polyolefin foam sheet 11 and a container 12 using the same according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a polyolefin foam sheet 11 according to the present embodiment has a polystyrene (PS) layer 13 as an intermediate layer, and a polypropylene (PP) layer on one side of the intermediate layer via an adhesive layer 14. A layer 15 is laminated, and polystyrene paper (PSP) 16 is laminated on the other surface side of the intermediate layer.

The PS layer 13 has a thickness of 0.05 mm to 2.00 mm, the PP layer 15 has a thickness of 10 μm to 500 μm, and the PSP 16 has a thickness of 0.1 mm to 2.0 mm. This polyolefin foam sheet 11 can be manufactured as follows. PS sheet and P
Sheet A in which an SP sheet is thermally laminated, and film B in which a PP film is coated with an adhesive
Are prepared, and the sheet A and the film B are thermally laminated to obtain the polyolefin foam sheet 11 of the present embodiment.

As shown in FIG. 2, the container 12 according to the present embodiment uses the polyolefin foam sheet 11 and is thermoformed so that the PP layer 15 is on the inner layer side and the PSP 16 is on the outer layer side. It was produced in.

[0014]

EXAMPLE An adhesive layer (thickness: 37 μm) and a sheet A in which a PS sheet (thickness: 0.45 mm) and a PSP sheet (thickness: 2.0 mm) were heat-laminated, and a PP film (thickness: 37 μm) 7 μm) were prepared, and the sheet A and the film B were subjected to thermal lamination to produce the polyolefin foam sheet 11 of the present example.

The polyolefin foam sheet
11 was used and thermoforming so that the polypropylene layer 15 was on the inner layer side and the polystyrene paper 16 was on the outer layer side, thereby producing a bowl-type container 12. When ramen and water were placed in the container 12 and heated in a microwave oven, no deformation of the container due to heat was observed, and the container 12 had sufficient heat resistance. Also the container
Despite the presence of ramen and water inside 12, there was no change in container shape due to the weight of the contents, and the container had sufficient rigidity. Furthermore, the container 12 immediately after being heated in the microwave oven could be held by hand, and had sufficient heat insulating properties.

[0016]

According to the present invention, it is possible to obtain a polyolefin foam sheet that can withstand heating by a microwave oven or the like and a container using the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a polyolefin foam sheet according to an embodiment of the present invention.

FIG. 2 is a sectional view of a container according to an embodiment of the present invention.

[Explanation of symbols]

 11 Polyolefin foam sheet 12 Container 13 Polystyrene 14 Adhesive layer 15 Polypropylene layer 16 Polystyrene paper

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 25:00 B29L 7:00 9:00 22:00 F term (Reference) 4F100 AK07A AK12B AK12C BA03 BA07 BA10A BA10C BA14 CB00 DA01 DG10C DJ01B GB15 JJ03 YY00A YY00B YY00C 4F208 AA11 AA13 AD08 AD17 AG03 AH52 AH56 AH58 MA01 MA06 MB01 MG04 MG13

Claims (3)

[Claims] 1. A method in which a polystyrene layer is used as an intermediate layer, a polypropylene layer is laminated on one surface side of the intermediate layer via an adhesive layer, and polystyrene paper is laminated on the other surface side of the intermediate layer. A polyolefin foam sheet characterized by the following. 2. The polyolefin foam sheet according to claim 1, wherein the polystyrene layer has a thickness of 0.05 mm to 2.00 mm, the polypropylene layer has a thickness of 10 μm to 500 μm, and the polystyrene paper has a thickness of 0.1 mm. A polyolefin foam sheet characterized by being set to 2.0 mm. 3. A container using the polyolefin-based foamed sheet according to claim 1 or 2 and thermoformed so that the polypropylene layer is on the inner layer side and the polystyrene paper is on the outer layer side. .