JP3167666B2 - Composite sheet and 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 composite sheet and a sealed container excellent in storage stability and physical properties with respect to contents.

[0002]

2. Description of the Related Art Conventionally, a storage container using plastic has a structure in which an ethylene-vinyl alcohol copolymer and a vinylidene chloride copolymer are used as a gas barrier layer, and both sides are laminated with a polyolefin such as polypropylene or polyethylene. Has been used. These have been widely used as having both gas barrier properties and sealing properties with the lid. However, as the research on the deterioration of the contents progresses, in the container containing polyolefin in the innermost layer, the innermost layer may adsorb the flavor of the contents or the odor component of the innermost resin layer may transfer to the contents. Understandably, the innermost layer other than the polyolefin was required.

As a container having these flavor characteristics, a container having an inner layer of polyethylene terephthalate, ethylene vinyl alcohol copolymer and polycarbonate has been proposed (Japanese Patent Laid-Open No. 3-244, Japanese Patent Publication No. Sho 5 (1993)).
Although the former can be used for hot-filled contents and pasteurized (100 ° C. or less) contents, the innermost layer is not used for high-temperature pasteurized (retort food) and the like. It could not be used due to the disadvantage of softening by heat. On the other hand, the latter polycarbonate has been considered as a resin to compensate for these disadvantages (Japanese Utility Model Publication No. 5-8127, Japanese Utility Model Application Laid-Open No. 61-115626, Japanese Patent Application Laid-Open No. 60-68938), but polycarbonate is a heat-resistant resin. Therefore, heat sealability is poor.
The temperature must be 0 ° C. or higher. In this case, there is a case where the lid material is melted and deteriorated, and there is a drawback that a sufficient sealing property cannot be obtained at a temperature at which the lid material does not deteriorate. Further, in combination with another resin, since polycarbonate is a heat-resistant resin, when a multilayer sheet layer is formed by vacuum forming or the like, there is a drawback that molding cannot be performed satisfactorily.

[0004]

SUMMARY OF THE INVENTION The present invention has been studied in various ways to solve these problems of the conventional sealed container, and the object is to provide various kinds of foods which are contents depending on the container. It is an object of the present invention to provide a composite sheet and a sealed container which are excellent in storage stability and sealability without impairing flavor.

[0005]

The present invention relates to a ternary polymer (A) of bisphenol A, diphenyl carbonate and 1,10-decanedicarboxylic acid, polypropylene (B), and a mixture of metaxylenediamine and adipic acid. A crystalline sheet obtained from the polycondensation polymerization reaction (hereinafter, referred to as nylon MXD6) (C) is a composite sheet in which ABCC is laminated in this order,
The polymerization molar ratio of the 10-decanedicarboxylic acid component is 5% or more and 2
Preferably, the polymer (A) has a thickness of 10% or less of the total thickness, the polypropylene (B) has a melt flow rate of 2.0 or less, and the polypropylene layer has a thickness of not more than 2.0%. The thickness is preferably 50% or more of the entire thickness. Further, a sealed container is formed by using a composite sheet to form a container so that the three-component polymer (A) becomes the innermost layer, and sealing the container with a lid having gas barrier properties.

BEST MODE FOR CARRYING OUT THE INVENTION

The ternary copolymer used in the present invention is:
Bisphenol A and diphenyl carbonate and 1,10
It consists of three components of decanedicarboxylic acid, in which the molar ratio of bisphenol A to diphenyl carbonate is 1: 1 and the molar ratio of bisphenol A to 1,10 decanedicarboxylic acid is 95: 5 to 80:20. It is polymerized.

As long as the polypropylene used in the present invention has a melt flow rate of 2.0 or less, various polypropylenes such as a homopolymer, a copolymer and a random polymer can be used. Further, other resins such as polyethylene may be mixed as long as the melt flow rate is not changed.

The nylon MXD6 used in the present invention is obtained by a polycondensation polymerization reaction between metaxylenediamine and adipic acid. H- [NHCH ₂ -mC ₆ H ₄ -CH ₂ -NHCO- (CH ₂ ) ₄ -CO] _n -OH
It has a structure of

As a method for laminating these resins, known laminating techniques such as a coextrusion method, a coextrusion laminating method, an extruding laminating method and a dry laminating method are used. In order to bond the respective resins for lamination, an adhesive or an adhesive resin suitable between the individual resins is used.

As a method for forming these multilayer sheets into a container, generally, a vacuum forming method, a pressure forming method,
A vacuum pressure molding method is used.

As the lid material used in the present invention, any material can be used as long as it can seal with the innermost layer and has gas barrier properties. For example, the sealant layer is a heat-sealable polyethylene terephthalate, the barrier layer is a vinylidene chloride copolymer, the outermost layer is a three-layer film of nylon, the sealant layer is a heat-sealable polyethylene terephthalate, the barrier layer is an aluminum foil, and the outermost layer is polyethylene terephthalate. There is. Further, the lid is not limited to a film shape, but may be a molded product. For example, it is also possible to use a multilayer sheet in which the sealant is heat-sealable polyethylene terephthalate, the barrier layer is an ethylene vinyl alcohol copolymer, and the outer layer is polypropylene, which is formed into a drop lid shape by vacuum forming.

As a method for welding the lid and the main body container, known heat sealing, ultrasonic sealing, and high frequency sealing are used.

The innermost three-component copolymer layer used in the container of the present invention is used for protecting the flavor of the contents and for improving the heat sealability. Further, the ternary copolymer component is excellent in heat resistance as compared with other thermoplastic resins, and can be used for foods requiring retort sterilization or the like.
1,10 decanedicarboxylic acid of the three components is used for improving heat sealability. The copolymer of bisphenol A and diphenyl carbonate is polycarbonate, which is excellent in heat resistance and fragrance retention, but inferior in heat sealability as described above. By copolymerizing a long fatty chain component with these two components, it is possible to improve the heat sealing property. When the lid sealant is heat-sealing polyethylene terephthalate, the former has a minimum heat sealing temperature of 230 ° C. On the other hand, the latter can be heat-sealed from 200 ° C., which is 30 ° C. lower. At this time, the copolymerization molar ratio of 1,10 decanecarboxylic acid was 5%.
If it is less than 20%, the heat sealability is not improved, and if it exceeds 20%, the fragrance retention becomes poor.

Although the heat sealability was improved by this, the heat resistance was still too good and a large amount of heat was required at the time of container heat molding. Further, it is said that the drawdown at the time of heating the sheet is large, and is generally not suitable for the vacuum forming method and the pressure forming method of the sheet heat forming type. For this reason, it is preferable to suppress the thickness of the ternary copolymer to 10% or less of the total thickness. As for the suitability of the flavor to the contents, a sufficient function can be achieved at this thickness ratio, and it is more preferable to suppress the content to 5% or less.

The polypropylene layer used in the present invention is used as a strength maintaining layer, a water vapor barrier layer, and a moldability improving layer. The thickness ratio is preferably 50% or more, and the melt flow rate of the polypropylene used is preferably 2.0 or less. In the case of polypropylene, if the melt flow rate exceeds 2.0, the drawdown during heating increases, and a satisfactory molded product cannot be obtained. If the polypropylene layer has a thickness ratio of less than 50%, drawdown during molding becomes large, which is inconvenient for container molding. In order to minimize the water absorption of nylon MXD6, which is a gas barrier layer during retort sterilization, the thickness ratio of the polypropylene layer is set to 50.
% Is preferable. This is because nylon MXD6, which is a gas barrier layer, has a reduced barrier property due to water absorption.

[0016]

EXAMPLES The effects of the present invention will be described below with reference to examples. Table 1 shows the configurations of three types of multilayer sheets used in the present invention and four types of multilayer sheets used for comparison. These multilayer sheets were prepared by a co-extrusion method. These multi-layered sheets are 80 mm in diameter and 50 m in height using an indirect heating type vacuum forming machine.
m, a container with a bottom diameter of 40 mmφ is filled with two kinds of contents, orange juice and curry. The former is hot-filled at 60 ° C, the latter is retort sterilized at 120 ° C for 30 minutes after filling, and at room temperature. One month storage was performed, and the storage stability and flavor suitability were compared. In addition, comparative evaluation was also performed on moldability during thermoforming. Table 2 shows the results.

[0017]

[Table 1]

The abbreviations of the resins shown in Table 1 are as follows. PC: polycarbonate. PP: polypropylene. MFR: melt flow rate. The copolymerization molar ratio of the resin (A) is as follows. Bisphenol A: diphenyl carbonate: 1,10
Decanedicarboxylic acid A1 is 91: 91: 9 A2 is 94: 94: 6 A3 is 81:81:19

[0019]

[Table 2]

The evaluation method is as follows. (1) Moldability: Molding was carried out using an 80 mm diameter container and a mold capable of simultaneously molding 42 pieces. ：: A good molded product was obtained. ×: Drawdown during heating was large, and a satisfactory molded product was not obtained. (Many occurrence of wrinkles and the like) (2) Flavor property: evaluation of orange juice The amount of limonene, which is a component in orange juice, adsorbed to the innermost layer was measured. ：: Very little. Δ: Little. ×: Many. (3) Flavor property: Evaluation of curry A taste test of the contents after storage for one month was performed. ：: No change in flavor was observed. X: A change in flavor is observed (a plastic smell is felt).

(4) Storage property: Evaluation after storage for one month: Evaluation of orange juice ：: Less decrease in vitamin C content and good taste. ×: Vitamin C content is greatly reduced and change is observed. (5) Storage property: Evaluation after storage for one month: Evaluation of curry ○: Less oxidation of oil, suitable for food. ×: Oxidation of oil is large, a smell is felt, and it is not edible. (6) Sealability: lid material PET (12μ) / AL (7μ)
/ Heat sealable polyethylene terephthalate (50
Minimum temperature that can be sealed in μ). Sealing capacity is 10
Kg was applied and leakage of the contents was confirmed.

[0022]

According to the sealed container of the present invention, a container which does not cause a change in the flavor of the contents can be obtained by an inexpensive molding method as compared with a conventional plastic barrier multilayer container.

Claims (5)

(57) [Claims] 1. A polymer obtained from a polycondensation polymerization reaction of a ternary polymer (A) of bisphenol A, diphenyl carbonate and 1,10 decanedicarboxylic acid, polypropylene (B), metaxylenediamine and adipic acid. A composite sheet, characterized in that the polyamide (C) is laminated in the order of ABCB. 2. The polymer (A) comprising a three-component system,
0 The polymerization molar ratio of the decane dicarboxylic acid component is 5% or more and 20 or more.
%. 3. The composite sheet according to claim 1, wherein the thickness of the ternary polymer (A) is 10% or less of the total thickness. 4. A melt flow rate of the polypropylene (B) is a block resin is 2.0 or less, and claims 1, 2 polypropylene layer is 50% or more of the total thickness
Or the composite sheet according to 3 . 5. A lid having gas barrier properties, wherein the composite sheet according to any one of claims 1 to 4, wherein a container is formed so that the ternary polymer (A) is the innermost layer. A sealed container characterized by being sealed by: