JPH0698737B2 - Multi-layer container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a multi-layer container, and more specifically to a multi-layer container suitable for packaging foods, beverages, pharmaceuticals and the like.

[Prior Art and Its Problems] Conventionally, plastic containers are lightweight and hygienic,
Since it can be easily molded into a desired shape and is suitable for mass production, it has been used in large quantities in recent years for packaging foods, beverages, pharmaceuticals and the like. Among them, a multilayer container in which a gas barrier resin layer and another resin layer are combined can improve the storability of contents, and has recently been attracting attention.

However, since these containers are apt to be charged with static electricity as a property peculiar to plastics, dust and dirt adhere to the container surface before and after filling the contents. It is unsanitary that dust adheres to the container before filling the contents, and rubber etc. adheres to the outer surface of the container after the contents are filled, during storage, transportation, store display, etc. Then, the appearance becomes poor, the consumer feels unclean, and the commercial value thereof decreases.

In addition, the conventional plastic container formed by molding a multi-layered sheet is not optimal for retort foods in which the container is heat-sterilized because the antistatic property deteriorates when heated.

The present invention has been made based on the above circumstances.

That is, the object of the present invention is to reduce the adhesion of dust and the like, which is a property peculiar to plastics, to prevent deterioration of the antistatic property even when heated, and to be suitable for enclosing, for example, retort foods. To provide.

[Means for Solving the Problems] The gist of the present invention for solving the above problems is to provide a gas barrier resin layer, a polyolefin resin layer substantially containing polypropylene, and a nonionic outermost layer. And a polypropylene resin layer containing a nonionic surfactant, wherein the thickness of the polypropylene resin layer containing a nonionic surfactant is 50% or more of the total volume.

Further, an example of the multi-layer container according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the container 1 includes a polypropylene resin layer 2 containing a nonionic surfactant and forming a non-ionic surfactant. It is formed of a multi-layer wall 4 having a gas barrier resin layer 3 which is in direct contact with the object to be packaged and a polyolefin resin layer which substantially contains polypropylene.

Examples of the polypropylene resin as a raw material for forming the polypropylene resin layer 2 containing the nonionic surfactant include homopolypropylene such as atactic polypropylene, isotactic polypropylene and syndiotactic polypropylene, and ethylene-propylene random copolymerization. Copolymers, ethylene-propylene block copolymers, ethylene-propylene-diene copolymers containing other monomers such as dicyclopentadiene, blends of polypropylene and polyethylene, blends of polypropylene and polyethylene and the above ethylene-propylene random copolymers. Examples thereof include blends with polymers.

As a blend of polypropylene and polyethylene, for example, in the presence of a Ziegler-Natta catalyst,
For example, propylene is polymerized in the first stage, and then
Polymerization reaction in the presence of other α-olefins such as ethylene or in the coexistence of other α-olefins such as ethylene with or without removing unreacted propylene monomer from the second stage onward. It is also possible to use polypropylene which is obtained by a so-called multi-stage polymerization method for carrying out.

Among the various polypropylenes mentioned above, homopolypropylene, random polypropylene, and a mixture of homopolypropylene and polyethylene and / or random polypropylene are preferable.

Further, in the polypropylene resin, as long as it does not impair the effects of the present invention, if necessary, elastomer, colorant, flame retardant, antioxidant, ultraviolet absorber, plasticizer, inorganic filler, heat Various additives such as stabilizers may be added and blended.

Examples of the elastomer include styrene-based thermoplastic elastomer, olefin-based thermoplastic elastomer, vinyl chloride-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, fluorine-based thermoplastic elastomer, and the like. Elastomer; polybutadiene rubber, styrene-butadiene rubber, isoprene rubber, ethylene-
Examples thereof include propylene copolymer, ethylene-prolene-diene terpolymer, neoprene-butadiene rubber, chloroprene rubber, urethane rubber, silicone rubber, and fluororubber.

Examples of the colorant include a sparingly soluble azo dye, a red colorant, cadmium yellow, cream yellow, and titanium white.

Examples of the flame retardant include inorganic antimony oxide, zircon oxide, organic phosphates, tricresyl phosphate, and the like.

As the antioxidant, phenol-based, phosphorus-based, triazole-based, salicylic acid-based, and acrylonitrile-based antioxidants are used.

Further, examples of the plasticizer include phthalic acid diester, butanol diester, phosphoric acid diester, and the like.

Examples of the inorganic filler include calcium carbonate, gypsum, talc, mica, barium sulfate, glass fiber, wollastonite, magnesium hydroxide, aluminum hydroxide and the like.

Examples of the nonionic surfactant in the polypropylene resin layer containing the nonionic surfactant include, for example, ether type nonionic surfactants, ether ester type nonionic surfactants, ester type nonionic surfactants and block polymers. Type nonionic surfactants, nitrogen-containing nonionic surfactants and the like can be used.

Examples of the ether type nonionic surfactants include single chain length polyoxyethylene ethers; polyoxyethylene alkyl alcohols and alkyls such as polyoxyethylene fatty alcohol ethers, polyoxyethylene alkyl allyl ethers and polyoxyethylene lanolin alcohols. Allyl ether; ethylene oxide derivative of alkylphenol formalin condensate; polyoxyethylene alkyl thioether and the like can be used.

As the ether ester type nonionic surfactant, for example, polyoxyethylene ether containing an ester bond such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glyceryl monofatty acid ester, polyoxyethylene sorbitol fatty acid ester;
Natural oils and fats and polyoxyethylene derivatives of waxes such as castor oil, hydrogenated castor oil derivative, lanolin derivative,
Etc. can be used.

Examples of the ester type nonionic surfactants include polyoxyethylene fatty acid esters; polyhydric alcohol esters such as higher fatty acid glycerin esters, sorbitan fatty acid esters, and sucrose fatty acid esters; ethylene glycol, diethylene glycol, propylene glycol, and the like. Polyhydric alcohol and lauric acid,
Esters with fatty acids such as stearic acid, oleic acid and myristic acid can be used.

Moreover, as the block polymer type nonionic surfactant, for example, a block polymer containing a pluronic type or a tetronic type alkyl group can be used.

As the nitrogen-containing nonionic surfactant, for example,
Polyoxyethylene fatty acid amide, alkylolamide, polyoxyethylene alkylamine, alkylamine oxide, alkylamine fatty acid ester and the like can be used.

Among these, polyhydric alcohol fatty acid ester and alkylamine fatty acid ester are preferable.

The blending amount of this nonionic surfactant is preferably 0.1 to 5% by weight, and 0.5 to 3% by weight, based on the polypropylene resin.
Is more preferable. If the blending amount of the nonionic surfactant is more than the above 5% by weight, stickiness may occur on the sheet or the container, and if the blending amount is less than 0.1% by weight, the desired antistatic effect is exhibited. There are things you can't do.

Further, the method of blending the nonionic surfactant to the polypropylene resin is not particularly limited, for example, a ribbon blender, a tumble mixer, a Henschel mixer, the kneading, open roll, Banbury mixer,
It can be carried out using a Henschel mixer, a single screw extruder, a twin screw extruder, a single reciprocating screw kneader, or the like. In particular, it is preferable to use a masterbatch in which a large amount of a nonionic surfactant has been previously mixed.

Examples of the gas barrier resin that is a raw material of the gas barrier resin layer 2 include saponified ethylene-vinyl acetate copolymers; polyamides such as nylon 6, nylon 66 and nylon 610; polyvinylidene chloride; polyethylene terephthalate and polybutylene terephthalate. Polyester ;, polyacrylonitrile, and the like.

The polyolefin resin layer 5 consisting essentially of polypropylene contains a polypropylene resin as a main component, and other components such as polyethylene, polybutene, poly-4-methylpentene-1 resin, unless the object of the present invention is impaired,
You may contain a filler etc.

As described above, the multi-layer container 1 according to the present invention includes the gas barrier resin layer, the polyolefin resin layer containing substantially polypropylene, and the outermost polypropylene resin layer containing a nonionic surfactant. Are integrally formed, and for example, a multilayer sheet is subjected to thermoforming such as vacuum forming or pressure forming or blow molding so that the polypropylene resin layer 2 containing the nonionic surfactant forms an outer surface of the multilayer wall 4. Can be obtained.

The multilayer wall 4 includes at least a gas barrier resin layer,
It has a polyolefin resin layer substantially containing polypropylene and a polypropylene resin layer containing a nonionic surfactant, and the polypropylene resin layer 2 containing the nonionic surfactant forms an outer surface. As shown in FIG. 2, an adhesive layer 7 may be provided, and as shown in FIG. 3, one surface is bonded to the polypropylene resin layer 2 containing a nonionic surfactant. A multi-layer wall may be formed by laminating one or more polyolefin resin layers 5 substantially containing polypropylene capable of adhering to the sheet on the other surface of the gas barrier resin layer 3 to be bonded to each other. Furthermore, as shown in FIG. 4, a polyolefin resin layer 5 substantially containing polypropylene is bonded to the polypropylene resin layer 2 containing a nonionic surfactant, and the other surface of the polyolefin resin layer 6 is covered with a gas. The multi-layered wall 4 may be formed by joining the barrier resin layer 3 and then by superposing the polyolefin resin layer 5 containing polypropylene substantially on the other surface of the gas barrier resin layer 3 and joining them together.

As the other resin layer 5, for example, a polyolefin resin can be used, and as the polyolefin resin, for example, polyethylene, polypropylene, polybutene, poly-4-methylpentene-1 resin or the like can be used. When the polyolefin resin layer 5 containing substantially polypropylene is interposed between the polypropylene resin layer containing a nonionic surfactant and the gas barrier resin layer, the nonionic surfactant has a gas barrier property. The transfer to the resin layer is prevented. When the polyolefin resin layer 5 containing substantially polypropylene is used so as to be inside the container, the polyolefin resin layer 5 containing substantially polypropylene is a polypropylene containing a nonionic surfactant. It is desirable to use the same kind of polypropylene resin as the material of the resin layer. The formation of the raw material multilayer sheet for obtaining the multilayer container of the present invention by thermoforming can be performed by, for example, wet lamination using an adhesive, dry lamination, hot melt lamination, or extrusion lamination or coextrusion lamination. it can.

Examples of the adhesive that is a raw material of the adhesive layer 7 include:
Adhesives such as cyanoacrylate-based, chloroprene rubber-based, nitrile rubber-based, dope cement-based, epoxy-based, and hot-melt-based adhesives can be used, but in the case of coextrusion molding, such as ionomers and maleic anhydride, for example. It is also desirable to use an adhesive resin such as a modified polyolefin modified with an unsaturated carboxylic acid or its derivative.

The total thickness of the multilayer wall 4 is not particularly limited, and can be determined according to the property of the contents.

However, as the preferable multilayer wall 4, the thickness of the layer (including the nonionic surfactant-containing polypropylene resin layer and other polypropylene resin layers) made of polyolefin resin as a raw material is 70% or more of the total thickness, preferably Is 80%
The above is desirable, and the thickness of the polyolefin resin layer 2 itself containing the nonionic surfactant is equal to that of the multilayer wall 4.
The total thickness is 50% or less.

Since the multi-layer container according to the present invention uses the gas barrier resin, it is suitable for packaging easily degradable contents such as foods, beverages and pharmaceuticals. Since the container has a structure in which a polypropylene resin layer containing a specific additive as an antistatic agent is provided on the outside of the container, dust or the like does not adhere to the container due to electrification, so that commercial value is not impaired. When this container is used as a packaging container for retort food, when the container is molded, stored, when packaging the retort food, or when sterilized or sterilized by heating after filling the retort food, the entire container is heated. Also, the antistatic property does not deteriorate,
Therefore, after the container containing the retort food is shipped, it is kept as a beautiful container free from dust and the like until it reaches the consumer's permission.

EFFECT OF THE INVENTION According to the present invention, a multi-layer container having a polypropylene resin in which a specific additive, that is, an antistatic agent is added to polypropylene, a gas barrier resin, and a polyolefin resin layer substantially containing polypropylene is provided. Since the resin layer is formed on the outside so that no dust is attached to the outer surface of the container, it is possible to provide a container capable of maintaining a beautiful surface appearance.

In particular, this container is surprisingly not deteriorated in antistatic property even after being heated. Therefore, this container is suitable as a container for retort foods, which can be mass-produced at low cost by heating and thermoforming a multilayer sheet and requires heating for sterilization and sterilization. In other words, it is optimal as a container that can store retort foods for a long period of time. Moreover, even after the sterilization and sterilization treatments, dust does not adhere to the outer surface of the container, and it is possible to prevent the commercial value of the container from lowering.

[Examples] Next, examples and comparative examples of the present invention will be described.

(Example 1) Polypropylene (Brand name: Idemitsu Polypropylene E-100)
G, MI 0.6 g / 10 min, Idemitsu Petrochemical Co., Ltd.), polypropylene modified with maleic anhydride as an adhesive resin (trade name: Idemitsu Polytac E100, Idemitsu Petrochemical Co., Ltd.),
Saponified ethylene-vinyl acetate copolymer (trade name: EVAL EP-101, ethylene content 32 mol%, MI 1.3 g / 10
(Manufactured by Kuraray Co., Ltd.), 1.5% by weight of polypropylene modified by maleic anhydride as an adhesive resin (same as above), polypropylene (same as above), and polyhydric alcohol fatty acid ester (Denon 2220, manufactured by Marubishi Co., Ltd.) Using a multi-layered sheet [sheet thickness (μ) = 400/30/40/30/400/300] obtained by co-extruding and stacking polypropylene (same as above) in this order, polypropylene containing polyhydric alcohol fatty acid ester is used outside As a result of vacuum forming, 130 × 90 × 30
An oval container of (height) was obtained. The antistatic properties of the multilayer sheet and the container were evaluated, and the results are shown in Table 1.

Example 2 Instead of polypropylene containing 1.5% by weight of a polyhydric alcohol fatty acid ester (Denon 2220, manufactured by Maruhishi Co., Ltd.), an alkylamine fatty acid ester (Antex EX SA) was used.
-300B, manufactured by Toho Kagaku Co., Ltd.) except that a polypropylene containing 1.5% by weight is used, and the same procedure as in Example 1 is performed to obtain a container similar to that in Example 1. The antistatic property was evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIGS. 2, 3, and 4 are partial vertical sectional views showing other examples of the multilayer wall. 1 ... Container, 2 ... Polypropylene resin layer containing nonionic surfactant, 3 ... Gas barrier resin layer, 4 ...
Multi-layered wall. 5, 6 ... Polyolefin resin layer substantially containing polypropylene, 7 ... Adhesive layer.

Claims (1)

[Claims] 1. A gas barrier resin layer, a polyolefin resin layer substantially containing polypropylene, and a polypropylene resin layer containing a nonionic surfactant, which is the outermost layer, containing a nonionic surfactant. The multi-layer container characterized in that the thickness of the polypropylene resin layer is 50% or more of the whole.