JP2022102807A - Laminated sheet, package, and method for producing package - Google Patents

Abstract

To provide a laminated sheet and a package having both of high barrier properties and high transparency, and a method for producing the package.SOLUTION: A laminated sheet has a laminated structure including at least two layers of: a substrate layer that contains a propylene resin containing smectic crystals and a polyethylene resin; and a barrier layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laminated sheet, a package, and a method for manufacturing the package.

In laminated sheets used as packaging, etc., polyethylene terephthalate (PET) resin, biaxially stretched polystyrene (OPS) resin, and polypropylene, which are often highly transparent, are often used because the contents of the laminated sheet are excellent in visibility when used as packaging. (PP) resin or the like is used. For example, when a package is used as a food container, the number of packages heated by a microwave oven has increased in recent years, and polypropylene-based resins having high oil resistance and heat resistance have been used.
For example, Patent Document 1 describes (a) one or more selected from the group consisting of a first layer containing polypropylene, polyethylene, polyamide, an ethylene-vinyl alcohol copolymer, and an ethylene-vinyl acetate copolymer. A method for producing a molded product including a step of producing a molded product using a laminated body having a second layer containing the above-mentioned material is described.

Japanese Unexamined Patent Publication No. 2018-127006

Further, as a protective property of the contents (for example, in the case of a food container, in order to suppress food loss and maintain the deliciousness), the package is required to have a barrier property against water vapor and oxygen.
However, there is no laminated sheet that imparts excellent barrier properties to the package while maintaining high transparency.
The laminated body described in Patent Document 1 is a laminated body for decorating a resin molded body, and Patent Document 1 discloses a laminated body for imparting high transparency and excellent barrier property to the molded body. It's not a thing. Further, in the laminate described in Patent Document 1, the second layer is also a layer that is supposed to be separated from the first layer before molding.

An object of the present invention is to provide a laminated sheet and a package having both excellent barrier properties and high transparency, and a method for manufacturing the package.

According to one aspect of the present invention, there is provided a laminated sheet in which at least two layers of a propylene-based resin containing smechika crystals, a polyethylene-based resin-containing base material layer, and a barrier layer are laminated.

In the laminated sheet according to one aspect of the present invention, the base material layer may contain the polyethylene-based resin in an amount of 0.1% by mass or more and 40% by mass or less.

In the package according to one aspect of the present invention, at least a part of the polyethylene-based resin may be polyethylene derived from biomass.

In the laminated sheet according to one aspect of the present invention, the isotactic pentad fraction of the propylene-based resin may be 85 mol% or more and 99 mol% or less.

In the laminated sheet according to one aspect of the present invention, the crystallization rate of the propylene-based resin at 130 ° C. may be 2.5 min ^-1 or less.

In the laminated sheet according to one aspect of the present invention, the propylene resin may have an exothermic peak of 1.0 J / g or more on the low temperature side of the maximum endothermic peak in the differential scanning calorimetry curve.

In the laminated sheet according to one aspect of the present invention, the base material layer may not contain a nucleating agent.

In the laminated sheet according to one aspect of the present invention, the thickness of the laminated sheet may be 0.2 mm or more and 1.2 mm or less.

In the laminated sheet according to one aspect of the present invention, the barrier layer may contain an ethylene vinyl alcohol copolymer resin.

According to one aspect of the present invention, a package using the laminated sheet according to one aspect of the present invention is provided.

Further, according to one aspect of the present invention, there is provided a package obtained by thermoforming a laminated sheet according to one aspect of the present invention at a temperature equal to or lower than the melting point of the propylene resin.

In the package according to one aspect of the present invention, the internal haze of the package is 15% or less, and the ratio of the internal haze of the package to the internal haze of the laminated sheet before thermoforming is 1 or less. May be good.

The package according to one aspect of the present invention may be used for packaging food.

According to one aspect of the present invention, there is provided a method for producing a package in which a laminated sheet according to one aspect of the present invention is thermoformed at a temperature equal to or lower than the melting point of the propylene-based resin.

According to one aspect of the present invention, it is possible to provide a laminated sheet and a package having both excellent barrier properties and high transparency, and a method for manufacturing the package.

It is an enlarged sectional view of the laminated sheet which concerns on one Embodiment of this invention. It is an enlarged sectional view of the laminated sheet which concerns on one Embodiment of this invention. It is an enlarged sectional view of the laminated sheet which concerns on one Embodiment of this invention. It is a schematic diagram of the package which concerns on one Embodiment of this invention. It is a schematic block diagram which shows the manufacturing apparatus which manufactures the laminated sheet of Example 1. FIG. It is a schematic block diagram which shows the manufacturing apparatus which manufactures the laminated sheet of the comparative example 1. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, and duplicate description will be omitted.

[First Embodiment]
In the first embodiment, a laminated sheet, a package, a method for manufacturing the package, and a container including the package according to the embodiment of the present invention will be described.

[Laminated sheet]
FIG. 1 is an enlarged cross-sectional view of the laminated sheet 1 according to the present embodiment. The package according to the present embodiment, which will be described later, is formed by thermoforming a laminated sheet 1 formed by laminating at least two layers of a base material layer 2 and a barrier layer 3.

(Base layer)
The base material layer 2 contains a propylene-based resin and a polyethylene-based resin.

-Propylene-based resin The propylene-based resin may be a polymer containing at least propylene. When the propylene-based resin is a copolymer of propylene and ethylene, it refers to a resin containing more than half of the propylene units. Examples of the polymer containing propylene include homopolypropylene and a copolymer of propylene and an olefin. The copolymer of propylene and olefin may be a block copolymer or a random copolymer. Alternatively, it may be a mixture thereof (a mixture containing a block copolymer and a random copolymer).
From the viewpoint of heat resistance and hardness, the propylene-based resin in the present embodiment is preferably homopolypropylene.

The propylene-based resin forming the base material layer 2 contains Smetica crystals as a crystal structure. Smetica crystals are a metastable intermediate phase, and since each domain size is small, they are excellent in transparency. Further, since it is in a metastable state, the laminated sheet 1 containing Smetika crystals is excellent in moldability because the sheet softens with a lower amount of heat as compared with the sheet containing α crystals in which crystallization has progressed.

The propylene-based resin may contain other crystal forms such as β crystal, γ crystal, and amorphous portion in addition to Smethica crystal. For example, 30% by mass or more, 50% by mass or more, 70% by mass or more, or 90% by mass or more of the propylene-based resin may be Smetica crystals, and other crystal forms may be used.

It can be confirmed by, for example, a small-angle X-ray scattering analysis method that the propylene-based resin contains smetica crystals.

The propylene-based resin preferably has an isotactic pentad fraction of 85 mol% or more and 99 mol% or less. When the isotactic pentad fraction is 85 mol% or more, the laminated sheet 1 is excellent in rigidity. Further, when the isotactic pentad fraction is 99 mol% or less, the laminated sheet 1 is excellent in transparency.
The isotactic pentad fraction is an isotactic pentad fraction in a pentad unit (a unit in which five propylene monomers are continuously isotactically bonded) in a molecular chain of a resin composition. A method for measuring this fraction is described in, for example, Macromoleculars, Vol. 8, pp. 687, and can be measured by ¹³ C-NMR.

The propylene-based resin preferably has a crystallization rate at 130 ° C. of 2.5 min ^-1 or less. When the crystallization rate is 2.5 min ^-1 or less, it is possible to prevent the portion in contact with the mold from being rapidly cured during thermoforming, and it is possible to prevent deterioration of the design. The crystallization rate can be measured by the method described in Examples.

The propylene resin preferably has an exothermic peak of 1.0 J / g or more on the low temperature side of the maximum endothermic peak in the differential scanning calorimetry curve, and more preferably has an exothermic peak of 1.5 J / g or more. The upper limit of the exothermic peak is not particularly limited. The upper limit of the exothermic peak is usually 10 J / g or less.
The exothermic peak can be measured using a differential scanning calorimetry device.

The lower limit of the content of the propylene-based resin in the base material layer 2 is preferably 60% by mass or more. The upper limit of the content of the propylene-based resin is preferably 99.9% by mass or less. When the content of the propylene-based resin in the base material layer 2 is within this range, a laminated sheet and a package (for example, a container body and a lid) having high transparency and excellent rigidity and heat resistance are provided. can. The lower limit of the content of the propylene-based resin in the base material layer 2 is more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, 93. It is particularly preferable that it is by mass or more. In particular, from the viewpoint of improving transparency, the lower limit is more preferably 94.5% by mass or more, further preferably 95.5% by mass or more, further preferably 97% by mass or more, 98. It is particularly preferable that it is by mass or more. Further, the upper limit of the content of the propylene-based resin in the base material layer 2 is more preferably 99.5% by mass or less, further preferably 99.2% by mass or less, and 97% by mass or less. Is even more preferable. In particular, from the viewpoint of improving transparency, the upper limit is more preferably 99.5% by mass or less, and further preferably 99.2% by mass or less. When the laminated sheet has a plurality of base material layers 2, the content of the propylene-based resin in the entire plurality of base material layers 2 is preferably within the above range.

-Polyethylene-based resin The polyethylene-based resin may be a polymer containing at least ethylene. When the polyethylene-based resin is a copolymer of propylene and ethylene, it refers to a resin containing a majority or more of ethylene units.
Examples of the polyethylene-based resin include low-density polyethylene-based resins such as linear low-density polyethylene-based resin ((Linear) Low Density Polyethylene: LDPE), high-density polyethylene (High Density Polyethylene: HDPE), and the like.
When the base material layer 2 contains a polyethylene-based resin, transparency, rigidity, and moldability of the laminated sheet are improved. By increasing the rigidity, it is expected that the effect of suppressing the hump and the effect of suppressing the shrinkage slack when the laminated sheet is wound up. Normally, it is presumed that the rigidity is reduced by adding the polyethylene-based resin, but the reason why the rigidity is increased in the present invention is presumed to be the interaction between the polyethylene-based resin and the fine crystals of Smetica crystals in the propylene-based resin. .. Further, as will be described later, the transparency is also improved by setting the content of the polyethylene-based resin within a predetermined range. In addition, the water vapor barrier property of the package formed by using the laminated sheet tends to be improved to the same level as or higher than the conventional one. Normally, it is presumed that the water vapor barrier property is lowered by adding the polyethylene resin, but the reason why the water vapor barrier property tends to be improved to the same level or higher in the present invention is that the polyethylene resin and the smetica crystals in the propylene resin are used. It is presumed that it is due to the interaction with the microcrystals of.

The polyethylene-based resin in the present embodiment preferably contains at least a part of polyethylene derived from biomass. In recent years, the use of biomass has been attracting attention for the purpose of reducing the environmental load. Biomass is an organic compound photosynthesized from carbon dioxide and water, and is a so-called carbon-neutral renewable energy that becomes carbon dioxide and water again by using biomass. Therefore, since the polyethylene-based resin contains polyethylene derived from biomass, the burden on the environment can be reduced.

Examples of the material of polyethylene derived from biomass include corn, cassava, sugar cane, sugar beet, palm palm, soybean, and castor. Further, the biomass-derived polyethylene may be produced by any method such as fermentation, bacterial fermentation, chemical change, and culture extraction. Such biomass-derived polyethylene may be, for example, low-density polyethylene derived from biomass.
When the polyethylene-based resin in the present embodiment contains polyethylene derived from biomass, the polyethylene-based resin may be a mixed resin of a polyethylene-based resin derived from biomass and a polyethylene-based resin derived from fossil fuel, and may be derived from biomass. It may be a resin consisting only of the polyethylene-based resin of.

The polyethylene resin preferably has a lower limit of MFR (Melt Flow Rate) of 0.5 g / 10 min or more. Further, the polyethylene resin preferably has an upper limit of MFR of 6 g / 10 min or less. When the MFR of the polyethylene resin is within this range, it is possible to provide a laminated sheet and a package (for example, a container body and a lid) having high transparency and excellent moldability.
The lower limit of the MFR of the polyethylene resin is more preferably 0.8 g / 10 min or more, further preferably 1.0 g / 10 min or more, and even more preferably 1.5 g / 10 min or more.
Further, the upper limit of the MFR of the polyethylene resin is more preferably 5 g / 10 min or less, and further preferably 4 g / 10 min or less.
The MFR in the present specification can be measured at a measurement temperature of 190 ° C. and a load of 2.16 kg in accordance with ASTM D1238-89.

The lower limit of the density of the polyethylene resin is preferably 870 g / cm ³ or more. Further, the upper limit of the density of the polyethylene resin is preferably 940 g / cm ³ or less. When the density of the polyethylene-based resin is within this range, it is possible to provide a laminated sheet and a package (for example, a container body and a lid) having high transparency and excellent moldability.
The lower limit of the density of the polyethylene resin is more preferably 890 g / cm ³ or more, and further preferably 898 g / cm ³ or more.
Further, the upper limit of the density of the polyethylene resin is more preferably 930 g / cm ³ or less, and further preferably 920 g / cm ³ or less.

From the viewpoint of rigidity, the lower limit of the content of the polyethylene-based resin in the base material layer 2 is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and 0.8% by mass. The above is even more preferable, and it is even more preferable that the content is 3% by mass or more. Further, from the viewpoint of rigidity, the upper limit of the content of the polyethylene-based resin in the base material layer 2 is preferably 40% by mass or less, more preferably 30% by mass or less, and 20% by mass or less. Is even more preferable, and 10% by mass or less is even more preferable, and 7% by mass or less is particularly preferable. Further, within this range, the water vapor barrier property tends to be improved to the same level or higher as compared with the case where the polyethylene-based resin is not contained.
On the other hand, from the viewpoint of transparency, the lower limit of the content of the polyethylene-based resin in the base material layer 2 is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and 0. It is more preferably 8% by mass or more. Further, from the viewpoint of transparency, the upper limit of the content of the polyethylene-based resin in the base material layer 2 is preferably 5.5% by mass or less, more preferably 4.5% by mass or less. It is more preferably 0% by mass or less, and even more preferably 2.0% by mass or less.

When the polyethylene-based resin contains polyethylene derived from biomass, the lower limit of the content of polyethylene derived from the biomass in the base material layer 2 is 0 with respect to the entire base material layer 2 from the viewpoint of reducing the burden on the environment. .1% by mass or more is preferable, 0.5% by mass or more is more preferable, 0.8% by mass or more is further preferable, and 3% by mass or more is even more preferable. Further, the upper limit of the content of the biomass-derived polyethylene in the base material layer 2 is preferably 40% by mass or less, preferably 30% by mass or less, based on the entire base material layer 2 from the viewpoint of transparency. Is more preferably 20% by mass or less, further preferably 10% by mass or less, and particularly preferably 7% by mass or less.
Further, from the viewpoint of transparency, when the polyethylene-based resin contains polyethylene derived from biomass, the lower limit of the content of polyethylene derived from the biomass in the base material layer 2 is preferably 0.1% by mass or more. It is more preferably 0.5% by mass or more, and further preferably 0.8% by mass or more. Further, from the viewpoint of transparency, when the polyethylene-based resin contains polyethylene derived from biomass, the upper limit of the content of the polyethylene derived from the biomass in the base material layer 2 is preferably 5.5% by mass or less. It is more preferably 4.5% by mass or less, further preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less.

When the laminated sheet has a plurality of base material layers 2, the content of the polyethylene-based resin and the polyethylene derived from biomass in the entire plurality of base material layers 2 is preferably within the above range.

In addition to the propylene-based resin and the polyethylene-based resin, the base material layer 2 may contain a resin other than the propylene-based resin and the polyethylene-based resin, an additive, and the like, as long as the effects of the present invention are not impaired. ..
Also in this case, it is preferable that the content of the propylene-based resin and the polyethylene-based resin in the base material layer 2 satisfies the above-mentioned content.

The base material layer 2 preferably does not contain a nucleating agent. Since the base material layer 2 does not contain a nucleating agent, the number of α crystals and spherulites in the base material layer 2 does not increase, and the crystallinity of the base material layer 2 does not increase.
Examples of the nucleating agent include a sorbitol-based crystal nucleating agent and the like. Examples of commercially available products include Gelol MD (New Japan Rika Co., Ltd.), Rikemaster FC-2 (RIKEN Vitamin Co., Ltd.) and the like.

The thickness _TB1 of the base material layer 2 is not particularly limited. The thickness _TB1 of the base material layer 2 is appropriately set depending on the intended use of the package.

(Barrier layer)
The barrier layer 3 is a layer having an oxygen barrier property that suppresses oxidative deterioration of the contents.
The barrier layer 3 is formed of, for example, at least one resin selected from the group consisting of ethylene vinyl alcohol copolymer resin (EVOH), polyvinylidene chloride resin (PVDC), and polyacrylonitrile resin (PAN). Alternatively, as described later, when the barrier layer 3 is formed by a method of coating the base material layer 2 with the material of the barrier layer 3, for example, silica, alumina, aluminum, and the material for forming the barrier layer 3 are used. Inorganic materials such as silicon nitride, organic materials such as polyvinyl alcohol (PVA), and silica /
Examples thereof include a coating material selected from the group consisting of organic-inorganic hybrid materials such as PVA.

The barrier layer 3 preferably contains an ethylene vinyl alcohol copolymer resin (EVOH). A high oxygen barrier property is realized by the barrier layer containing EVOH.
From the viewpoint of transparency and thermoformability, EVOH preferably has an ethylene copolymerization ratio of 38 mol% or more and 47 mol% or less.

When the barrier layer 3 contains an ethylene vinyl alcohol copolymer resin (EVOH), the package obtained by thermoforming the laminated sheet 1 has excellent oxygen barrier properties. The base material layer 2 of the laminated sheet 1 according to the present embodiment has a high water vapor barrier property. Therefore, in the laminated sheet 1, the base material layer 2 suppresses the deterioration of the oxygen barrier property due to the contact of the barrier layer 3 formed of the ethylene vinyl alcohol copolymer resin (EVOH) with water or water vapor, and as a result, the result is A package (for example, a container body, a lid, etc.) formed by heat-molding a laminated sheet 1 having a barrier layer 3 has excellent oxygen barrier properties.

When the barrier layer 3 is made of an ethylene vinyl alcohol copolymer resin (EVOH), the ratio of the thickness T of the entire laminated sheet 1 to the thickness _TB2 of the barrier layer 3 [( _TB2 / T) × 100]. However, it is preferably 2% or more and 15% or less. If this ratio is 2% or more, excellent oxygen barrier properties can be easily obtained, and if it is 15% or less, the laminated sheet 1 can be easily thermoformed, and the cost increase of the laminated sheet 1 can be suppressed.

In addition to EVOH, the barrier layer 3 may contain a resin other than EVOH, an additive, and the like.

The thickness of the laminated sheet 1 is appropriately set depending on the intended use of the package. For example, the thickness of the laminated sheet 1 can be 0.2 mm or more and 1.2 mm or less.

The laminated sheet 1 may contain an anti-fog agent, if necessary. When the laminated sheet 1 contains an anti-fog agent, at least one of the base material layer 2 and the barrier layer 3 may contain the anti-fog agent.
The antifogging agent is not particularly limited, and is, for example, at least one antifogging agent selected from the group consisting of sucrose-based fatty acid ester, glycerin fatty acid ester, tertiary fatty acid amide, higher alcohol fatty acid ester, and propylene glycol fatty acid ester. It is preferably an agent, and among these, a sucrose-based fatty acid ester is preferable from the viewpoint of transparency and antifogging property, and a partial ester compound of sucrose and an aliphatic monocarboxylic acid having 12 or more and 22 or less carbon atoms is preferable. Is more preferable. As the anti-fog agent, one type may be used alone, or two or more types may be mixed and used.

Further, the laminated sheet used for the package is not limited to the two-layer structure composed of the base material layer 2 and the barrier layer 3 like the laminated sheet 1, and may be a multilayer structure having three or more layers. The laminated sheet having a multilayer structure of three or more layers may have other layers in addition to the base material layer and the barrier layer, for example. For example, in the laminated sheet 1 of FIG. 1, a laminated sheet having another layer (not shown) between the base material layer 2 and the barrier layer 3 can be mentioned. Examples of the other layer include an adhesive layer or an anti-fog layer containing an anti-fog agent.

When the laminated sheet has an anti-fog layer, the anti-fog layer is preferably formed of a resin composition in which an anti-fog agent and a binder component are mixed.
The binder component is not particularly limited, but is preferably an acrylic adhesive, and more preferably a hydrophilic acrylic resin from the viewpoint of transparency, moldability, and stickiness of the anti-fog layer. The hydrophilic acrylic resin is not particularly limited, but a copolymer such as a polyacrylic acid ester can be adopted. Here, examples of the acrylic acid ester constituting the polyacrylic acid ester include methyl ester, ethyl ester, butyl ester, octyl ester, and 2-ethylhexyl ester of acrylic acid. The polyacrylic acid ester is obtained by copolymerizing these acrylic acid esters with at least one monomer selected from the group consisting of, for example, methacrylic acid ester, styrene, acrylonitrile, vinyl chloride and vinyl acetate. Coalescence can be adopted. Further, as the polyacrylic acid ester, these acrylic acid esters were copolymerized with at least one functional monomer selected from the group consisting of, for example, acrylic acid, acrylamide, methylolacrylamide, and hydroxydialkylmethacrylate. A copolymer can also be adopted.

Further, the laminated sheet used for the package may have a plurality of base material layers 2. For example, as shown in FIG. 2, the laminated sheet 1A in which the first base material layer 2A, the barrier layer 3, and the second base material layer 2B are laminated in this order may be used. When the laminated sheet used for the package has a plurality of base material layers 2, the propylene-based resins in the plurality of base material layers 2 may be the same or different from each other. Further, the polyethylene-based resins in the plurality of base material layers 2 may be the same or different from each other.
Further, for example, a laminated sheet having another layer independently between the first base material layer and the barrier layer and between the barrier layer and the second base material layer may be used. For example, as shown in FIG. 3, the first base material layer 2A, the first adhesive layer 4A, the barrier layer 3, the second adhesive layer 4B, and the second base material layer 2B are the same. The laminated sheet 1B laminated in order may be used. In the laminated sheet 1A and the laminated sheet 1B, the first base material layer 2A and the second base material layer 2B correspond to the above-mentioned base material layer 2.
The laminated sheet used for the package has the first base material layer 2A on one surface side of the barrier layer 3 and is on the other surface side of the barrier layer 3, like the laminated sheet 1A or the laminated sheet 1B. By having the second base material layer 2B, it is preferable to have a structure in which the barrier layer is sandwiched between a plurality of base material layers. Since the barrier layer is sandwiched between a plurality of base material layers in the laminated sheet, it is easier to prevent the oxygen barrier ability of the barrier layer from being deteriorated by water vapor, and as a result, the packaging formed by thermoforming the laminated sheet. The oxygen barrier property of the body (for example, the container body and the lid) is further excellent.

[Manufacturing of laminated sheets]
The laminated sheet 1 according to the present embodiment can be manufactured, for example, by the method described in the first embodiment. Alternatively, the barrier layer 3 may be formed by a method of manufacturing the base material layer 2 by the manufacturing apparatus according to the first embodiment and then coating the base material layer 2 with the material of the barrier layer 3.

[Manufacturing of packaging and packaging]
The laminated sheet according to one aspect of the present invention can be used as a package.
The package according to the present embodiment can be manufactured, for example, by thermoforming the laminated sheet 1 according to the present embodiment. In this case, it is preferable to thermoform at a temperature equal to or lower than the melting point of the propylene-based resin in the base material layer 2 of the laminated sheet 1. Specifically, the package according to the present embodiment may be manufactured by the method described in the examples.

The package according to the present embodiment can be used, for example, as a container body, a lid, or the like of a container for food or the like.
Hereinafter, an example in which the package according to the present embodiment is used as the lid of the container will be described.

[container]
FIG. 4 is a cross-sectional view showing the container of the present embodiment.
As shown in FIG. 4, the container 50 of the present embodiment is composed of a container body 30 and a lid 40. In the container 50 of the present embodiment, a package in which the above-mentioned laminated sheet 1 is molded, specifically, is molded by heating is used for the lid 40. In the package obtained by thermoforming the laminated sheet 1, the base material layer 2 and the barrier layer 3 are not separated from each other and are used as elements constituting the package.
As the container described in the present embodiment, for example, a structure for opening by delamination with a notch, a structure for opening with agglomeration without a notch, and the like are appropriately selected.

[Container body configuration]
As shown in FIG. 4, the container body 30 is composed of a base layer 31 and a surface layer 32.
The base material layer 31 of the container body 30 is basically not particularly limited as long as it is a thermoformed material. For example, polypropylene, polystyrene, polyamide, polyethylene terephthalate, polycarbonate, polyethylene naphthalate and the like are exemplified. These materials may be used alone or in combination. Preferably polypropylene is used. Examples of polypropylene include homopolypropylene, block copolymers or random copolymers of propylene and ethylene, block copolymers or random copolymers of propylene, ethylene and butene, and the like.
Further, for example, polymer alloys such as polypropylene and polystyrene and rubber-modified polystyrene can be used to improve rigidity and moldability.
Further, the base material layer 31 of the container body 30 can contain various additives in the resin. For example, an inorganic filler can be included to improve rigidity.

Further, the base material layer 31 of the container main body 30 may be composed not only of one layer but also by laminating a plurality of layers, if necessary. For example, an adhesive resin layer or the like may be included.
The surface layer 32 of the container body 30 is preferably made of polypropylene resin or polyethylene resin in consideration of oil resistance, chemical resistance, and heat resistance.
Further, the container main body 30 is obtained by molding a resin sheet composed of a base material layer 31 and a surface layer 32 into a desired shape having a flange 30a shown in FIG. Examples of the molding method include a vacuum forming method and a compressed air forming method.

[Closure structure]
As shown in FIG. 4, the lid 40 is composed of a base material layer 41 and a barrier layer 42.
The lid 40 is molded using the laminated sheet 1 of the present embodiment. Therefore, the base material layer 41 of the lid 40 is composed of the base material layer 2 of the laminated sheet 1 described above, and the barrier layer 42 of the lid 40 is composed of the barrier layer 3 of the laminated sheet 1 described above.
Further, the lid 40 is obtained by molding the laminated sheet 1 of the present embodiment into a desired shape having the flange 40a shown in FIG. Examples of the molding method include a vacuum forming method and a compressed air forming method. At this time, the lid 40 is thermoformed at a temperature equal to or lower than the melting point of the propylene-based resin in the base material layer 2 of the laminated sheet 1. By thermoforming the lid 40 at a temperature equal to or lower than the melting point of the propylene resin, the fine crystal structure is maintained and the lid 40 becomes highly transparent. Regarding obtaining a package by thermoforming a laminated sheet at a temperature equal to or lower than the melting point of the propylene resin in the base material layer in order to maintain high transparency of the package, Patent Document 1 relating to a method for manufacturing a decorative molded body. Not listed in.
The melting point of the propylene resin in the base material layer of the laminated sheet can be measured by differential scanning calorimetry (DSC).
Since the lid 40 in the present embodiment is molded using the laminated sheet 1 of the present embodiment, it has an excellent barrier property. In addition to having good transparency, it also has excellent performance in various physical properties such as cold impact resistance, heat resistance, and rigidity.

[How to seal the container body and lid]
When the container body 30 and the lid 40 are sealed and sealed, the flange 30a of the container body 30 and the flange 40a of the lid 40 are overlapped, and the overlapped flanges 30a and 40a are attached from the lid side with a seal bar. It is sealed by heat-sealing and making close contact.
The sealing temperature is preferably 170 ° C. or higher and 220 ° C. or lower, and more preferably 180 ° C. or higher and 200 ° C. or lower. When the sealing temperature is 170 ° C. or higher, the sealing time can be shortened and the productivity is improved. Further, if the temperature is 220 ° C. or lower, there is no risk that the base material layer will melt and cause edge breakage.
The sealing pressure is preferably 1 MPa or more and 5 MPa or less, the sealing time is preferably 0.5 seconds or more and 5 seconds or less, and the sealing pressure is more preferably 2 MPa or more and 4 MPa or less, and the sealing time is more preferably 1 second or more and 3 seconds or less. When the sealing pressure is 1 MPa or more, sufficient sealing strength can be obtained. Further, if the sealing pressure is 5 MPa or less, there is no risk of edge breakage.
By heat-sealing under the above heat-sealing conditions, a container having high sealing properties can be obtained.

From the viewpoint of improving transparency, the container 50 preferably has an internal haze of 15% or less of the lid 40 as a package. Further, the ratio of the internal haze of the lid 40 as a package / the internal haze of the laminated sheet 1 before thermoforming (the ratio of the internal haze of the package (cover 40) to the internal haze of the laminated sheet 1 before thermoforming). Is also preferably 1 or less.
In the container 50, the internal haze of the lid 40 as a package is 15% or less, and the ratio of the internal haze of the lid 40 as a package / the internal haze of the laminated sheet before thermoforming is 1 or less. Is more preferable. If the internal haze of the lid 40 as a package is 15% or less and the ratio of the internal haze of the lid 40 as a package to the internal haze of the laminated sheet before thermoforming is 1 or less, the container 50 is more suitable. It will be a highly transparent container.
The internal haze is the haze of the resin itself measured by excluding the influence of the roughness of the surface of the sheet or the like. The internal haze can be measured by a haze meter NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS-K-7136.

The container 50 is used for foods, for example, for filling foods, seasonings, food raw materials, beverages, etc., for secondary packaging of pharmaceutical products, and for daily miscellaneous goods. Furthermore, not only solids but also various kinds of objects to be packaged such as liquids and mixtures thereof can be filled.

[Effect of this embodiment]
The container 50 according to the present embodiment includes, as a package, a lid 40 formed by thermoforming a laminated sheet obtained by laminating at least two layers of a base material layer 41 and a barrier layer 42. The base material layer 41 contains a propylene-based resin containing smetica crystals and a polyethylene-based resin, and the lid 40 is thermoformed at a temperature equal to or lower than the melting point of the propylene-based resin. As a result, the container 50 becomes a container having both excellent barrier properties and high transparency.
Further, according to the knowledge of the present inventor, when a propylene-based resin which is a transparent crystalline resin is used as a raw material and a polyethylene-based resin is further added as a raw material, problems such as a decrease in rigidity and a deterioration in transparency occur. I know that. The container 50 according to the present embodiment is a container having excellent rigidity and transparency even when a polyethylene-based resin is added because the base material layer 41 in the lid 40 contains a propylene-based resin containing smetica crystals. ..

[Modification example]
The best configuration for carrying out the present invention and the like are disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been described mainly with respect to a specific embodiment, the material, quantity, and other details with respect to the above-described embodiments without departing from the scope of the technical idea and purpose of the present invention. Various modifications can be made by those skilled in the art in various configurations.
Therefore, the description that limits the material, layer structure, etc. disclosed above is merely an example description for facilitating the understanding of the present invention, and does not limit the present invention. For this reason, the description with a name excluding some or all of the restrictions on the materials and the like is included in the present invention.

For example, in the above embodiment, the container 50 in which the package is the lid 40 is exemplified, but the package in the container may be the container body or the like.
In the above embodiment, the container 50 having the lid 40 as a package obtained by molding the laminated sheet 1 by heating has been described as an example, but the present invention is not limited to such an embodiment. For example, the container body may be a package obtained by molding the laminated sheet 1 by heating. In this case, both the lid and the container body may be a combination of packages in which the laminated sheet 1 is molded by heating, or the container body is a package in which the laminated sheet 1 is molded by heating, and the lid is used. May be a general-purpose film.

Further, the container 50 may have various shapes such as a circular shape, a square shape, and an elliptical shape. Further, although the dome shape is exemplified as the lid body 40, it may be in the form of a flat sheet.

Further, the bonding between the container body 30 and the lid 40 is not limited to heat sealing, and various bonding methods such as welding by ultrasonic waves and bonding using an adhesive or the like can be used.
Further, the structure for opening the container body 30 and the lid 40 may be either opening by delamination or opening by coagulation peeling.
The heat seal of the flange 30a of the container body 30 and the flange 40a of the lid 40 is not limited to the case where the heat seal portion is formed in an annular shape along the outer peripheral edge to impart sealing property, and the heat seal portion is provided in the outer peripheral direction. It may be partially heat-sealed so that the dots are scattered.

Further, as the laminated sheet forming the lid 40, the two-layer structure of the base material layer 41 and the barrier layer 42 has been described, but the base material layer 41 may be a sheet having a multi-layer structure of two or more layers.
Further, the laminated sheet forming the lid 40 may be a sheet having a multi-layer structure of three or more layers having another layer between the base material layer 41 and the barrier layer 42. Examples of the other layer include an adhesive layer and the like.
Further, the laminated sheet forming the lid 40 may be a sheet in which the first base material layer, the barrier layer, and the second base material layer are laminated in this order.
Further, the container body 30 may also have a multi-layer structure having three or more layers.

Further, not only the form of the container 50 composed of the container body 30 and the lid 40, but also the form in which the bonded portion is interposed between the container body 30 and the lid 40 may be used.

Hereinafter, examples according to the present invention will be described. The present invention is not limited to these examples.

(Example 1)
[Manufacturing of laminated sheets]
The laminated sheet 1B was manufactured as follows using the manufacturing apparatus 10 shown in FIG.
The following three types of molten resin (resin obtained by melting the resin of the base material layer, the resin of the barrier layer, and the resin of the adhesive layer) are co-extruded as a sheet-like material 1a from the T-die 11 of the extruder to form a sheet. The object 1a was sandwiched between the metal endless belt 25 and the fourth cooling roll 22 on the first cooling roll 21. In this state, the sheet-like material 1a was pressure-welded and rapidly cooled by the first cooling roll 21 and the fourth cooling roll 22 at the arc portion corresponding to the center angle θ1 of the first cooling roll 21.
Subsequently, the sheet-like material 1a is sandwiched between the metal endless belt 25 and the fourth cooling roll 22 at the arc portion corresponding to the substantially lower half circumference of the fourth cooling roll 22, and the sheet-like material 1a is surface-pressed and sprayed with cooling water. The sheet-like material 1a was further rapidly cooled by spraying cooling water onto the back surface side of the metal endless belt 25 by the nozzle 26. The sprayed cooling water was collected in the water tank 27, and the collected water was discharged through the drainage ditch 27a.
After surface pressure welding and cooling with the fourth cooling roll 22, the sheet-like material 1a in close contact with the metal endless belt 25 was moved onto the second cooling roll 23 with the rotation of the metal endless belt 25. Here, the sheet-like material 1a guided by the release roll 29 and pressed toward the second cooling roll 23 is, as described above, formed by the metal endless belt 25 at the arc portion corresponding to substantially the upper half circumference of the second cooling roll 23. Surface pressure welding was performed and the mixture was cooled again. The water adhering to the back surface of the metal endless belt 25 was removed by the water absorption roll 28 provided during the movement from the fourth cooling roll 22 to the second cooling roll 23.
The sheet-like material 1a (laminated sheet 1B) cooled on the second cooling roll 23 was then peeled from the metal endless belt 25 by the peeling roll 29.
The surface of the first cooling roll 21 is coated with an elastic material 21a made of nitrile-butadiene rubber (NBR). The surface of the second cooling roll 23 is also coated with an elastic material (not shown) made of nitrile-butadiene rubber (NBR).
Further, the temperature of the metal endless belt 25 can be controlled by a cooling means (not shown) such as a water cooling type built in the third cooling roll 24 or the like.

The manufacturing conditions of the laminated sheet 1B are as follows. The blending amount of the resin in each layer is as shown in Table 1. The linear low-density polyethylene is a biopolyethylene derived from a plant (sugar cane).
-Resin of base material: PP1 (Homopolypropylene F-300SP (manufactured by Prime Polymer Co., Ltd.) (MFR: 3.0 g / 10 min (230 ° C, 2.16 kg), melting point: 160 ° C, isotactic pentad fraction : [Mmmm] = 94%)) and PE ((Linear low density polyethylene SLH218 (manufactured by Braskem)) (MFR: 2.3 g / 10 min (190 ° C, 2.16 kg), density: 916 kg / m ³ )
-Barrier layer resin: EVOH (ethylene-vinyl alcohol copolymer resin G Soanol (manufactured by Mitsubishi Chemical Corporation))
-Resin for adhesive layer: AD (Modic P674V (manufactured by Mitsubishi Chemical Corporation))
・ Diameter of extruder: 150mm
-Width of T-die 11 (size of the edge of the die): 1400 mm
-Thickness of laminated sheet 1B: 0.3 mm
-Pick-up speed of laminated sheet 1B: 25 m / min-Surface temperature of the fourth cooling roll 22 and the metal endless belt 25: 17 ° C.
-Cooling rate: 10,800 ° C / min (180 ° C / sec)
・ Nucleating agent: None

In the obtained laminated sheet 1B, the ratio of the thickness _TB1 of the base material layer to the total thickness T of the laminated sheet 1B [( _TB1 / T) × 100] was 92%. Further, the ratio of the thickness _TB2 of the barrier layer to the thickness T of the entire laminated sheet 1B [( _TB2 / T) × 100] was 4%.
Further, in the obtained laminated sheet 1B, the first base material layer, the first adhesive layer, the barrier layer, the second adhesive layer, and the second base material layer were laminated in this order. It was a sheet with a five-layer structure.

(Melting point)
The melting point of the resin (polypropylene) of the base material layer was measured as follows.
Using a differential scanning calorimetry (DSC) (“Diamond DSC” manufactured by PerkinElmer Japan Co., Ltd.), raise the temperature of polypropylene from 50 ° C to 200 ° C at 10 ° C / min and hold it at 220 ° C for 5 minutes. It was cooled from 220 ° C. to 50 ° C. at 10 ° C./min. The temperature showing the maximum value of the endothermic peak obtained at this time was defined as the melting point of polypropylene.

(Crystallization rate)
The crystallization rate of polypropylene used for the substrate layer was measured using a differential scanning calorimetry device (DSC) (“Diamond DSC” manufactured by PerkinElmer Japan Co., Ltd.). Specifically, polypropylene is heated from 50 ° C. to 230 ° C. at 10 ° C./min, held at 230 ° C. for 5 minutes, cooled from 230 ° C. to 130 ° C. at 80 ° C./min, and then to 130 ° C. It was retained and crystallized. The measurement of the change in calorific value was started from the time when the temperature reached 130 ° C., and the DSC curve was obtained. From the obtained DSC curve, the crystallization rate was determined by the following procedures (i) to (iv).
(I) The baseline was the linear approximation of the change in calorific value from the time point 10 times the time from the start of measurement to the peak top to the time point 20 times.
(Ii) The intersection of the tangent line having a slope at the inflection point of the peak and the baseline was obtained, and the crystallization start and end times were obtained.
(Iii) The time from the obtained crystallization start time to the peak top was measured as the crystallization time.
(Iv) The crystallization rate was determined from the reciprocal of the obtained crystallization time.
The crystallization rate of polypropylene used for the substrate layer was 0.9 min ^-1 .

[Container molding]
The laminated sheet 1B manufactured as described above is heated to a temperature below the melting point of the resin of the base material layer with an infrared heater and pressed against a mold with vacuum and compressed air to cool the cup container having a diameter of 95 mm. Molded.

(Comparative Example 1)
The container was molded by the same materials and methods as in Example 1 except that the laminated sheet 71 was manufactured under the manufacturing conditions shown below using the manufacturing apparatus shown in FIG.
In the manufacturing apparatus, the molten resin co-extruded from the T-die 72 of the extruder was brought into close contact with the cooling roll 76 by the air knife 74 and cooled by the cooling rolls 76 and 78 to manufacture the laminated sheet 71.
[Manufacturing conditions] -Extruder diameter: 30 mm
-Width of T-die 72: 350 mm
-Pick-up speed of laminated sheet 71: 2.1 m / min-Surface temperature of cooling rolls 76 and 78: 30 ° C.

(Comparative Example 2)
Except that PE ((Linear low density polyethylene SLH218 (manufactured by Braskem) (MFR: 2.3 g / 10 min (190 ° C., 2.16 kg), density: 916 kg / m ³ )) was not used for the resin of the base material layer. Made a laminated sheet of Comparative Example 2 in the same manner as in Example 1.

When the base material layers of the laminated sheets of Example 1 and Comparative Examples 1 and 2 were analyzed by the small-angle X-ray scattering analysis method, the laminated sheets of Examples 1 and 2 were made of propylene-based resin with smetika crystals. Was confirmed to contain.

(Evaluation of water vapor barrier)
A molded cup container having a diameter of 95 mm was filled with 80 g of water, sealed, and stored under dry conditions at 40 ° C. Moisture loss mass (%) was measured after 1 day, 4 days, and 6 days of storage. The water mass in the cup container immediately after the filling seal is 80 g, and the water mass in the cup container measured 1 day, 4 days, and 6 days after storage is Wx (unit: g), and the water loss mass (%). = {(80-Wx) /80} × 100 was used to calculate the water loss mass (%). The results are shown in Table 2.

(Evaluation of tensile properties)
As the tensile characteristics, "elastic modulus", "yield strength", "break strength", and "elongation" were measured by conducting a tensile test on the sample at 50 mm / min with a tensile tester based on JIS K 7161. , Compared and evaluated. The results are shown in Table 3.
The laminated sheet was measured in the extrusion direction (MD) of molding and in the vertical direction (TD) of MD.

(Haze evaluation)
A haze meter (NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.) was used to measure the total haze of the laminated sheet and the cup container.
For laminated sheets, internal haze and external haze were also measured. The internal haze of the laminated sheet was measured with a haze meter by applying silicone oil to both sides of the sheet and then sandwiching both sides of the sheet with a glass plate to eliminate the influence on the outside of the sheet. The external haze of the laminated sheet was calculated by subtracting the internal haze of the laminated sheet from the total haze of the laminated sheet.
The results of each are shown in Table 4.

(Evaluation of formability)
The formability of the container molded above was evaluated as follows from the appearance and the variation in the meat circumference under the flange neck. The results are shown in Table 5.
A: Good appearance and little variation around the meat around the flange B: Wrinkles in the container and / or variation around the meat around the flange neck, both within the allowable range C: Wrinkles on the container There is and / or there is a large variation around the meat around the flange neck

From the results shown in Table 2, it can be seen that the container of Example 1 is superior in water vapor barrier property to the container of Comparative Example 1. Further, it can be seen that the container of Example 1 is more excellent in water vapor barrier property than the container of Comparative Example 2.
Further, from the results shown in Table 3, it can be seen that the laminated sheet of Example 1 is superior in rigidity to the laminated sheet of Comparative Example 2. This is considered to be a synergistic effect of the base material layer containing the propylene-based resin containing Smetika crystals and the polyethylene-based resin in Example 1. Further, since the base material layer contains the propylene-based resin and the polyethylene-based resin, the rigidity of the container has been lowered in the past, but the container of Example 1 has the same or higher rigidity than the container of Comparative Example 2. It turns out that it is excellent.
Further, from the results shown in Table 4, it can be seen that the laminated sheet of Example 1 has improved internal haze and is excellent in transparency as compared with the laminated sheets of Comparative Examples 1 and 2.
Further, from the results shown in Table 5, it can be seen that the container of Example 1 is superior in moldability to the containers of Comparative Examples 1 and 2.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person having ordinary knowledge in the field of the art to which the present invention belongs can come up with various modifications or modifications within the scope of the technical idea described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

1,1A, 1B ... Laminated sheet, 1a ... Sheet-like material, 2,41 ... Base material layer, 2A ... First base material layer, 2B ... Second base material layer, 3,42 ... Barrier layer, 4A ... First adhesive layer, 4B ... second adhesive layer, 10 ... manufacturing equipment, 11 ... T die, 21 ... first cooling roll, 21a ... elastic material, 22 ... fourth cooling roll, 23 ... second cooling roll, 24 ... 3rd cooling roll, 25 ... metal endless belt, 26 ... cooling water spray nozzle, 27 ... water tank, 27a ... drainage groove, 28 ... water absorption roll, 29 ... peeling roll, 30 ... container body, 30a, 40a ... flange , 31 ... base material layer, 32 ... surface layer, 40 ... lid, 50 ... container, θ1 ... center angle.

Claims (14)

A laminated sheet obtained by laminating at least two layers of a base material layer containing a propylene-based resin containing smechika crystals and a polyethylene-based resin, and a barrier layer. The base material layer contains the polyethylene-based resin in an amount of 0.1% by mass or more and 40% by mass or less.
The laminated sheet according to claim 1. At least a part of the polyethylene-based resin is polyethylene derived from biomass.
The laminated sheet according to claim 1 or 2. The isotactic pentad fraction of the propylene resin is 85 mol% or more and 99 mol% or less.
The laminated sheet according to any one of claims 1 to 3. The crystallization rate of the propylene resin at 130 ° C. is 2.5 min ^-1 or less.
The laminated sheet according to any one of claims 1 to 4. The propylene resin has an exothermic peak of 1.0 J / g or more on the low temperature side of the maximum endothermic peak in the differential scanning calorimetry curve.
The laminated sheet according to any one of claims 1 to 5. The substrate layer does not contain a nucleating agent.
The laminated sheet according to any one of claims 1 to 6. The thickness of the laminated sheet is 0.2 mm or more and 1.2 mm or less.
The laminated sheet according to any one of claims 1 to 7. The barrier layer contains an ethylene vinyl alcohol copolymer resin.
The laminated sheet according to any one of claims 1 to 8. A package using the laminated sheet according to any one of claims 1 to 9. A package obtained by thermoforming the laminated sheet according to any one of claims 1 to 9 at a temperature equal to or lower than the melting point of the propylene-based resin. The internal haze of the package is 15% or less, and the ratio of the internal haze of the package to the internal haze of the laminated sheet before thermoforming is 1 or less.
The package according to claim 11. The package according to any one of claims 10 to 12, which is used for packaging food. A method for producing a package, wherein the laminated sheet according to any one of claims 1 to 9 is thermoformed at a temperature equal to or lower than the melting point of the propylene-based resin.

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