JPH0671824A - Packing body - Google Patents

Abstract

PURPOSE:To permit a packing body to endure an internal pressure upon heating sterilization, provide the same with easily operable property and permit the same to endure heating cooking by electromagnetic wave by a method wherein the packing body is constituted by laminating a base material layer/a bonding layer/polypropylene/polyethylene/polypropylene in an order from the outer layer while the thickness of respective layers as well as bonding force between layers are specified. CONSTITUTION:The thickness of the innermost layer or a polypropylene layer is specified so as to be 10-70mum and the thickness of neighboring polyethylene layer is specified so as to be 10-40mum. The packing body is formed so as to be a vessel shape having a flange part employing a composite sheet having the relation of X<Y between a bonding force X between the innermost layer or a polypropylene layer and a polyethylene layer and a bonding force Y between the polyethylene layer and a polypropylene layer, opposed to the innermost layer or the polypropylene layer. After the packing is filled with contents, the same body is sealed employing a lid material so that a bonding force Z between the innermost layer of the flange part and the lid material becomes Z>X.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has heat resistance and shape retention that can withstand heating during heat sterilization after filling the contents and sealing the lid material, and has a high internal pressure in the package during heat sterilization. The present invention relates to a package having a hermetically sealing property that can be endured and having an easy-open property when opened.

[0002]

2. Description of the Related Art Conventionally, as a container-shaped package for packaging various kinds of foods, in which the lid can be easily opened, the composition of the resin constituting the lid material or the innermost seal layer of the container is changed. By adjusting the sealing strength between the container flange and the lid material within an appropriate range, the seal layer is cut and destroyed to open the seal. It is easily affected by time conditions, environmental temperature, adhesion of contents, etc., it is difficult to control the seal strength, and the force of peeling the lid material from the outside and the force of cutting and breaking the seal layer from the inside are equal, making it easy to open However, there is a drawback in that the peeling from the inside is naturally easy to occur and a problem occurs in the sealing property during heat sterilization.

In order to remedy such drawbacks, the container is opened by delamination between the sealing layer on the container side and the layer adjacent thereto, as disclosed in Japanese Patent Publication No. 50-37597. A method has been proposed, and many methods for improving this method have been proposed. (For example, JP-A-62-251363, 63-78, 63-25037, etc.) Various proposals have also been made by the present applicant. (For example, actual exploitation 64-3927
However, the structure of these sealing layers and their adjacent layers is excellent in heat resistance such as polypropylene as an adjacent layer to the sealing layer. (3, Actually open 01-96868, JP-A-02-67125, 03-226405, etc.) In the case of arranging the resin, only the one having poor heat resistance such as polyethylene having an appropriate adhesive force with polypropylene can be arranged in the inner layer which comes into contact with the food as the content. For this reason, in recent years, there have been cases where they are exposed to even higher temperatures due to heating and cooking with electromagnetic waves, and there is great concern about these.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a package which has heat resistance and is easy to open, and more specifically, it is resistant to the internal pressure during heat sterilization and yet has an easy openability. An object of the present invention is to provide a package which can withstand heating and cooking by electromagnetic waves.

[0005]

The present invention comprises a base material layer having heat resistance, which is based on a base material layer composed of, for example, polypropylene / adhesive layer / barrier layer. Is laminated in the order of polypropylene / polyethylene / polypropylene via an adhesive layer,
The innermost polypropylene layer has a thickness of 10 to 70 μm
And the thickness of the polyethylene layer adjacent to this layer is 10
Is 40 μm, and the relationship between the adhesive force X between the innermost polypropylene layer and the polyethylene layer and the adhesive force Y between the polyethylene layer and the polypropylene layer on the side opposite to the innermost layer is X <Y. Is molded into a container shape having a flange portion, and after filling the contents with a lid member, sealing is performed so that the interlayer adhesive force Z between the lid member and the innermost layer of the flange portion is Z> X. It is a package.

The present invention is also characterized in the construction of the composite sheet which constitutes the flange portion (composite sheet constituting the container) for sealing with the lid material, and the polypropylene layer is used as the adhesive layer of the flange portion with the lid material. In particular, the fact that this layer is made of a polypropylene layer makes it possible to significantly improve the heat resistance as compared with the case of using conventional polyethylene, a modified product thereof, or a mixture thereof. It is a thing. Needless to say, the sealing layer of the lid material is made of polypropylene-based resin, and can have a strong adhesive strength with the polypropylene layer that is the sealing layer on the container side. In the step of sealing the material, the lid material can be sealed with almost no influence on the adhesive force between the polypropylene layer which is the sealing layer on the container side and the polyethylene layer adjacent to the polypropylene layer.

Further, in the present invention, by controlling the thickness of the polypropylene layer which is the innermost layer and the polyethylene layer adjacent to the polypropylene layer and controlling the lamination between the layers, it is possible to improve the sealing material of polypropylene sealant which has been difficult in the past. This is because the peeling was easy. In the present invention, the thickness of the polypropylene layer which is the innermost layer needs to be 10 to 70 μm, and the thickness of this polypropylene layer is 1
If it is less than 0 μm, the sealing strength when receiving internal pressure is not sufficient, sufficient sealing performance cannot be ensured, and at the same time the heat resistance becomes insufficient, causing a problem in shape retention during heat sterilization. If the thickness of the innermost polypropylene layer is more than 70 μm, the heat resistance is increased, but the peeling resistance at the time of opening becomes large and smooth opening is impaired.

The thickness of the polyethylene layer adjacent to the innermost polypropylene layer must be 10 to 40 μm, and the thickness of this polyethylene layer is 10 μm.
When the thickness is less than μm, the polyethylene layer is lifted up in the peeling of the innermost polypropylene layer and the polyethylene layer adjacent to the polypropylene layer at the time of opening, and the polyethylene layer may be cut off in some cases, resulting in peeling. It may damage the appearance after opening. When the thickness of the polyethylene layer is more than 40 μm, there is no problem in opening the polyethylene layer, but the proportion of the polyethylene layer in the entire layer structure is high, the heat resistance is lowered, and deformation during heating is likely to occur. .

In the present invention, the adhesive force X between the innermost polypropylene layer and the adjacent polyethylene layer,
In order to make the relationship between the interlayer adhesive force Y between the polyethylene layer and the polypropylene layer constituting the outside thereof and the interlayer adhesive force X <Y, the polypropylene of the polypropylene layer constituting the outside of the polyethylene layer is For example, by blending polyethylene to increase the adhesive force Y, or by selecting the polypropylene resin of the polypropylene layer, for example, by using random or copolymer polypropylene, the adhesive force Y of the polyethylene layer is increased, while the polypropylene layer of the innermost layer is It is also possible to use a method in which the resin is a homopolymer so that the interlayer adhesion has a relationship of X <Y, or a method in which another resin is blended with the polyethylene layer resin. Further, the adhesive force Z between the innermost polypropylene layer and the lid material is made stronger by using the same polypropylene resin as the innermost polypropylene resin, and the relation Z> X is obtained.

Further, when sealing the container and the lid member made of the layered structure of the present invention, a line is formed on the innermost side or the innermost side and the outermost side of the container flange portion, which is more linear than the flange face. Moreover, if the lid member is sealed so as to have a pressing mark so as to have a concave shape, the opening can be performed more smoothly than when the flange portion is sealed with a flat surface. To form the concave shape of the filament on the innermost side or the innermost side and the outermost side of this flange, use a sealing board that has linear projections on the innermost or outermost part of the flange of the sealing board. May be used for sealing, or even if it is flat once and then double-sealed to form a concave shape at this position using a linear sealing plate, or if it is the innermost or innermost side of the flange. It is possible to double-seal using a flat-faced sealing disc after forming a pressing trace such that the sealing portion has a concave shape by using a sealing disc having a linear protrusion on the outermost side.

Further, even if the lid member is sealed after forming a myriad of minute concave portions on the entire surface or a part of the flange portion of the container, the unsealing property is improved. To form the minute recesses in the flange portion, the minute recesses can be formed by a method such as ultrasonic oscillation or pressing with a hot plate or the like having minute protrusions. If these minute recesses are formed on the entire surface or a part of the container flange portion or a part of the inner surface of the rising portion of the flange portion, the unsealing property is remarkably improved.

[0012]

【Example】

<< Examples 1 to 6 and Comparative Examples 1 to 10 >> Examples of the present invention will be described below in comparison with Comparative Examples. The composite sheet having the container layer structure shown in Table 1 was produced by the coextrusion method. The interlayer adhesion of this composite sheet was measured for each layer by the 180 ° peeling method. This sheet is then vacuum formed to an inner diameter of 65
A container having a size of 25 mm, a height of 25 mm, and a flange width of 5 mm was prepared, and countless minute recesses were formed by ultrasonic treatment inside the container corresponding to 1/2 of the flange width of the flange portion. Further, when the lid material is sealed in this molded container (flat one in which the flange portion is not subjected to ultrasonic treatment), a concave shape is formed on the innermost side of the flange portion using a sealing plate having a linear protrusion,
After that, it was sealed with a flat surface sealer. In the base material layer of the container layer structure, only polypropylene was used for Examples 3 and 4, and 415μ of the thickness 515μ was recovered recycled polypropylene. In Examples 5 and 6, 300 µ of the polypropylene thickness of 400 µ was recycled recycled polypropylene. That is, the base material layer used in Examples 3 and 4 had a layer structure of PP / recovered PP,
The base material layer used in Examples 5 and 6 has a layer structure of PP / recovered PP / adhesive layer / EVOH. The lids used in Examples 1 to 6 and Comparative Examples 1 to 9 were polypropylene (60μ) / polyester (12μ) / ethylene vinyl alcohol copolymer (15μ) / polyester (12μ) from the sealing surface.
In Comparative Examples 10 and 11, polyethylene (60μ) / polyester (12μ) / ethylene vinyl alcohol copolymer (15μ) / polyester (12μ) was used. The container was filled with water using these lid materials, and after sealing and sterilizing under pressure at 125 ° C. for 40 minutes, the openability, heat resistance, and internal pressure resistance were evaluated.
The results are shown in Table 2.

[0013]

[0014]

Table: PP: Polypropylene, PE: Polyethylene EVOH: Ethylene vinyl alcohol copolymer Openability: Evaluation of open feeling by female monitor Good: Good openability Poor: Poor openability Appearance after opening: Visual evaluation Good: Open Good appearance afterwards Poor: Baking on the unsealed surface or the sealing layer becomes bag-shaped Heat resistance: Checking for leakage and deformation of contents after heat sterilization Good: Seal leakage, no deformation Poor: Seal leakage, flange part Internal pressure resistance: Compressed air is injected due to the upper surface of the lid material, and internal pressure resistance from inside is measured, and the average value is shown. No: Cannot be measured due to leakage of contents

[0016]

EFFECTS OF THE INVENTION Since the present invention has a structure having a polypropylene layer as the innermost layer, the heat resistance is remarkably improved as compared with the conventional polyethylene-based one, and further the innermost polypropylene layer and the polyethylene layer adjacent thereto, By adjusting the adhesive force between the polypropylene layers adjacent to this polyethylene layer and by limiting the thickness of the innermost polypropylene layer and the polyethylene layer adjacent to this layer, the easy-open property of the polypropylene sealant, which has been difficult in the past, can be achieved. A package having can be obtained. Further, it is a package that can withstand even pressure heat sterilization treatment without being deformed or peeling of the lid material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B65D 81/34 V 7501-3E

Claims (4)

[Claims] 1. A substrate layer / adhesive layer / polypropylene / polyethylene / polypropylene layered in this order from the outer layer, and the thickness of the innermost polypropylene layer is 10 to 70 μm.
And the thickness of the polyethylene layer adjacent to the polypropylene layer is 10 to 40 μm, the interlayer adhesion between the innermost polypropylene layer and the adjacent polyethylene layer is X, and the polyethylene layer and the polypropylene layer forming the outside thereof are When the inter-layer adhesive strength of is Y, the relation of inter-layer adhesive strength is X <
A container shape having a flange portion is formed using the composite sheet of Y, and after filling the contents, a lid material is used, and the interlayer adhesive force Z between the lid material and the polypropylene layer which is the innermost layer of the flange portion.
Is a package that is sealed so that Z> X. 2. The package according to claim 1, wherein the base layer comprises a polypropylene / adhesive layer / ethylene vinyl alcohol copolymer or polyvinylidene chloride barrier layer. 3. A lid having a pressing trace having a concave shape with respect to the surface of the flange seal portion on the innermost side or the innermost side and outermost side of the seal portion between the flange portion and the lid member of the container constituting the package. The package according to claim 1 or 2, which is formed by sealing a material. 4. The lid material is formed by sealing a lid material on a surface of polypropylene forming the innermost layer of a flange portion of a container constituting a package, in which a myriad of minute concave portions are formed on the whole surface or a part thereof. Packaging.