JP3393809B2 - Sealed container - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetically sealed container having a sealability and heat resistance that can withstand pressure and heat applied during heat sterilization as a packaging material for foods, beverages and the like.

[0002]

2. Description of the Related Art Conventionally, a gas barrier layer has been generally provided in a plastic packaging container for foods, beverages, etc. in order to preserve the contents. In particular, as the gas barrier resin, an ethylene-vinyl alcohol copolymer or a crystalline polyamide resin obtained from a polycondensation polymerization reaction of metaxylenediamine and adipic acid (hereinafter referred to as nylon MXD6
Is described) is generally used. However, after molding and punching the container, the layer of ethylene-vinyl alcohol copolymer or nylon MXD6 is exposed on the end surface of the container, so under a humid condition, for example, sterilization with hot water causes gas barrier to absorb moisture. A decline in sex was unavoidable. In order to solve this problem, it is often the case that the gas barrier property must be maintained by increasing the thickness of the gas burr layer, and there is no effective countermeasure.

[0003]

DISCLOSURE OF THE INVENTION The present invention is excellent in heat resistance and sealing property, and further prevents deterioration of gas barrier property due to moisture absorption from an end surface after sealing with a lid material, and sealing for improving storage stability of contents. It was made for the purpose of providing a container.

[0004]

As a result of intensive studies to solve the above problems, the present invention has revealed that a layer adjacent to the seal layer side of a gas barrier layer made of ethylene-vinyl alcohol copolymer or nylon MXD6. By arranging the resin layer of the fluidized bed in, when the lid and the container are sealed,
It was found that the heat and pressure of the sealing board applied from the sealing surface side of the container cause the resin of the fluidized bed to flow out to the end surface side of the container, cover the end of the gas barrier layer, and suppress the deterioration of the gas barrier property due to moisture absorption by the gas barrier layer. The present invention has been completed based on this finding. That is, the present invention comprises (A) a seal layer, (B) a fluidized bed, (C) a gas barrier layer, and (D) a support layer, and is A-B-C-D * or A-D-B-C-. It is a sealed container in which a composite sheet laminated in the order of D * is molded into a container so that the (D *) support layer is the outermost layer and sealed with a lid. Further, the present invention comprises (B) a fluidized bed, (C) a gas barrier layer, and (D) a support layer, and comprises B-C-D * or D-B-C.
It is a hermetically sealed container obtained by molding a composite sheet laminated in the order of -D * so that the (D *) support layer is the outermost layer and hermetically sealing it with a lid. As a preferable form,
(A) The thickness of the seal layer is 3 to 500 μm, and (C)
The end surface of the gas barrier layer is coated with the resin of the (B) fluidized bed, and the melt flow rate of the resin used in the (B) fluidized bed is 2 according to the test method specified in JISK6758.
To 50 (g / 10 min), and (C) the gas barrier layer is a hermetically sealed container made of an ethylene-vinyl alcohol copolymer resin or a crystalline polyamide resin obtained by a polycondensation polymerization reaction of metaxylenediamine and adipic acid. Is.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The thickness of the (A) seal layer used in the hermetically sealed container of the present invention is preferably 3 to 500 μm, more preferably 10 to 25 μm. The heat and pressure from the sealing board is easily transmitted to the. (B) The MFR of the resin used in the fluidized bed is JIS K
2 to 50 (g / 10 according to the test method specified in 6758)
min), but more preferably 4 to
When it is in the range of 10 (g / 10 min), film formation by a coextrusion method or the like is easier. The (C) gas barrier layer is preferably an ethylene-vinyl alcohol copolymer resin or nylon MXD6. The support layer (D) is not particularly limited, but a low moisture-permeable polyolefin resin such as polypropylene or polyethylene can be used. The polyolefin resin preferably has a melt flow rate of 5 g / 10 minutes or less.
It is more preferably g / 10 minutes or less. If the melt flow rate of the polyolefin resin exceeds 5 g / 10 minutes, the drawdown during thermoforming may increase, and it may be difficult to obtain a good molded product.

In the composite sheet of the present invention, between the (A) sealing layer and the (B) fluidized layer, the (B) fluidized layer and the (C) gas barrier layer, and the (C) gas barrier layer and the (D) support layer. Can be provided with an adhesive layer. The adhesive used for the adhesive layer is not particularly limited, and examples thereof include maleic anhydride-modified polypropylene. By providing the adhesive layer, the adhesive strength between the layers can be improved.

If necessary, a pigment may be added to the resin constituting the (A) sealing layer, (B) fluidized layer and (D) supporting layer. The pigment to be mixed is not particularly limited, but white pigment such as titanium oxide may be used.

In the composite sheet of the present invention, (B),
The thickness of each of the layers (C) and (D) is not particularly limited, but the thickness of the fluidized bed (B) is preferably 10 to 500 μm, and the thickness of the support layer (D) is 10 to 1000 μm.
m is preferred.

There is no particular limitation on the method for producing the laminate which is the composite sheet of the present invention. For example, known lamination techniques such as coextrusion method, coextrusion laminating method, extrusion laminating method and dry laminating method are used. Can be manufactured.

The hermetically sealed container of the present invention is formed by molding a composite sheet so that the support layer (D) is the outermost layer and sealing it with a lid. There is no particular limitation on the method of forming the composite sheet into a container, for example, a vacuum forming method,
It can be molded using a known molding method such as a pressure molding method or a vacuum pressure molding method.

The lid used in the present invention is not particularly limited, but generally, a polyethylene resin, a polypropylene resin, a mixture thereof or the like can be used depending on the resin used for the sealing layer of the bottom container. . If necessary, a vinylidene chloride copolymer or ethylene vinyl alcohol copolymer may be provided as a gas barrier layer, and a three-layer film in which the outermost layer is nylon may be used.
Further, the lid is not limited to the film shape, and a molded article shape can be used. For example, a multilayer sheet having a linear low-density polyethylene sealant layer, an ethylene vinyl alcohol copolymer gas barrier layer, and polypropylene as the outermost layer can be formed into a lid shape dropped by vacuum forming and used.

As a method for sealing a container formed by using the composite sheet of the present invention with these lid materials, the purpose is to extrude to the end of the fluidized bed, so the shape of the sealing plate is not necessarily limited. Although not a thing, it is desirable to use, for example, a flat thing, an R-shaped thing of about R60, and a linear thing, and to carry out by a heat-sealing method.

The effects of the present invention will be described with reference to the following examples. Table 1 shows the configurations of the composite multilayer sheets for the containers of Examples and Comparative Examples. These multilayer sheets were prepared by the coextrusion method. The structure of the lid used is as follows: Examples 1, 2, 3, 5, 6, 9, 10: PET (12 μm) / AL (7 μm) / PET (12 μm) /
LLDPE (50 μm) Examples 4, 7, 8 and Comparative Example 2: PET (12 μm) / AL (7 μm) / PET (12 μm) /
CPP (50 μm) Comparative Example 1: PET (12 μm) / AL (7 μm) / PET (12 μm) /
Amorphous PET (30 μm) A composite multi-layer sheet for a container was calibrated using an indirect heating type vacuum forming machine with a caliber of 70 mmφ, a height of 40 mm and a bottom diameter of 50 mmφ.
The container of was produced. The contents were filled with 100 ml of hot water. The space is replaced with N2 gas, the lid is heat-sealed, and then the retort treatment is performed at 121 ° C for 30 minutes.
After storage for 3 days at 23 ° C. and 90% RH, the concentration of oxygen contained in the headspace of the container was measured. The results are shown in Table 1. The abbreviations used in the tables and in the lid structure are as follows. LLDPE; linear low-density polyethylene HDPE; high-density polyethylene LDPE; low-density polyethylene EVOH; ethylene-vinyl alcohol copolymer PP; polypropylene R-PP; ethylene-propylene random copolymer (ethylene content: 4 wt%) PET; Polyethylene terephthalate MFR; Melt flow rate AL; Aluminum CPP; Unstretched polypropylene

[0014]

[Table 1]

Examples 1 and 2 are (A) a sealing layer,
(B) fluidized bed, (C) gas barrier layer, (D) support layer,
The container was a hermetically-sealed container that was laminated in the order of ABCD from the inside of the container, and the residual oxygen concentration was kept low. Examples 3 and 4 are (A) a sealing layer, (B) a fluidized bed,
The gas barrier layer (C) and the support layer (D) are sealed containers in which A-B-B-C-D are stacked in this order from the inside of the container, and the residual oxygen concentration was suppressed to a low level. Examples 5 and 6 are hermetically sealed containers in which the fluidized bed (B), the gas barrier layer (C), and the support layer (D) are laminated in the order of B-C-D from the inside of the container, and residual oxygen is left. The concentration was kept low. In Examples 7 and 8, the fluidized bed (B), the gas barrier layer (C), and the support layer (D) were used as D-B-C-
The sealed container was laminated in the order of D, and the residual oxygen concentration was kept low. In Examples 9 and 10, (B) the MFR of the resin of the fluidized bed was low, and the gas barrier layer was not sufficiently covered. Therefore, the residual oxygen concentration in the space was slightly higher than that of the other Examples. In Comparative Examples 1 and 2, since the (B) fluidized bed was not provided, coating of the gas barrier layer did not occur, so the residual oxygen concentration in the space was higher than that of the Examples.

FIG. 1 shows a state in which the fluidized bed (B) covers the gas barrier layer (C) during heat sealing. Figure 1
As described in (3), the end portion of the (C) gas barrier layer is completely covered with the fluidized bed, so that the (C) gas barrier layer is prevented from absorbing moisture and prevents deterioration of the gas barrier property.

[0017]

The hermetically sealed container of the present invention can be easily manufactured, and moreover, the end portion of the gas barrier layer is reliably covered by the heat sealing method without any special treatment, and the gas barrier property is lowered due to moisture absorption. Can be stopped.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a gas barrier layer (C) is covered with a fluidized bed (B) when heat-sealed with a lid material in the sealed container of the present invention.

[Explanation of symbols]

1: container 2: Lid 3: Seal board 4: Seal layer 5: Fluidized bed 6: Gas barrier layer 7: Support layer 8: Cover part

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B32B 27/00 B65D 1/00 B65D 1/09 B65D 53/00 B65D 81/24

Claims (5)

(57) [Claims] 1. A seal layer, (B) fluidized bed, (C) gas barrier layer, and (D) support layer.
The composite sheet laminated in the order of D * or A-D-B-C-D * is sealed by molding the container so that the (D *) support layer is the outermost layer and sealing the lid. A sealed container comprising: when the lid and the container are sealed
Then, due to the heat and pressure of the seal plate, (B) the fluidized bed is
(C) covers the end surface of the gas barrier layer.
A sealed container characterized by the above . 2. A fluidized bed (B), a gas barrier layer (C), and a support layer (D), comprising B-C-D * or D-B-.
The composite sheet laminated in the order of C-D * is (D *)
Support layer molded container so that the outermost layer, Sea the lid
A sealed container that is sealed by
When the lid and container are sealed, heat and pressure of the sealing plate
Causes (B) the fluidized bed to flow out to the end surface of the container, and
Sealing volume characterized by covering the end face of the barrier layer
vessel. 3. The hermetically sealed container according to claim 1, wherein the thickness of the (A) sealing layer is 3 to 500 μm. Wherein (B) by the test method of melt flow rate of the resin used in the fluidized bed defined in JISK6758, claim 1-3 What is 2~50 (g / 10min)
A sealed container according to any one of the above. 5. The (C) gas barrier layer comprises an ethylene-vinyl alcohol copolymer resin or a crystalline polyamide resin obtained by a polycondensation polymerization reaction of metaxylenediamine and adipic acid . sealed container according one paragraph.