JP2012196875A - Laminated sheet for manufacturing packaging base material, packaging base material and food package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated sheet for manufacturing a packaging base material excellent in moldability, gas barrier performance, odor blocking performance, cold resistance, heat resistance, heat insulation performance and rigidity, the packaging base material using the laminated sheet and a food package using the packaging base material.SOLUTION: The laminated sheet 1 for manufacturing the packaging base material is characterized in that an adhesive layer 3, one or more gas barrier resin layers 4, 5 and a sealant layer 6 are laminated in this order on one face of a foaming sheet layer 2 which is composed of a polystyrene-based resin foaming sheet containing a polyphenyleneether-based resin.

Description

  The present invention relates to a packaging substrate used for gas pack packaging of food and vacuum packaging, etc., and packaging substrate excellent in moldability, gas barrier property, odor blocking property, cold resistance, heat resistance, heat insulation and rigidity. The present invention relates to a laminated sheet for production, a packaging substrate using the laminated sheet, and a food packaging body using the packaging substrate.

  Polypropylene (PP) resin sheets and polystyrene (PS) resin sheets as food packaging materials are widely used in food containers such as food trays, but because of their poor gas barrier properties, Since deterioration proceeds, it is not suitable as a long-term storage container.

  In recent years, containers have been proposed that can be stored for a long time even after filling and packaging foods by laminating films with gas barrier properties on the surface of PP resin trays and PS resin trays. Yes. A food package that lasts for a long time can be obtained by filling the bottom material obtained by thermoforming the molding material with a foodstuff and then vacuum-processing it using a cover material such as a gas barrier shrink film.

  For example, Patent Document 1 discloses that a heat-resistant resin layer, a gas barrier resin layer, and a polypropylene resin layer are laminated in this order as a bottom material for food packaging. A worn laminated sheet is disclosed.

  Patent Document 2 discloses a gas barrier property in which a hot melt adhesive layer, an ethylene-vinyl acetate copolymer saponified resin layer, an adhesive resin layer, and an easily openable resin layer are laminated in this order as a bottom material for food packaging. A multilayer sheet is disclosed in which a foam sheet of polypropylene or polystyrene resin that can be deep-drawn is laminated on a film.

  In Patent Document 3, a polystyrene resin and / or a polyphenylene ether resin is previously added to 100 parts by mass of a base resin composed of 50 to 90 parts by mass of a polystyrene resin and 50 to 10 parts by mass of a polyphenylene ether resin. A heat-resistant foam containing 1 to 10 parts by mass of master pellets containing 10 to 40% by mass of hydrophobic zeolite and 3% by mass or less of a volatile foaming agent is disclosed.

JP 2002-192668 A JP 2003-020070 A JP 2008-94919 A

However, the conventional techniques disclosed in Patent Documents 1 to 3 have the following problems.
Although the polypropylene resin film disclosed in Patent Document 1 has heat resistance, it has poor impact resistance at a low temperature of 0 ° C. or lower, and may break due to impact such as dropping, and is not suitable for frozen storage. Further, in the deep drawing, the thickness of the molded product is not uniform and the formability of details is inferior.
In the multilayer sheet disclosed in Patent Document 2, when a polypropylene resin foam sheet is laminated, although the polypropylene resin has heat resistance, it is poor in impact resistance at a low temperature of 0 ° C. or less, and is caused by impact such as dropping. There is a risk of cracking and it is not suitable for frozen storage. Further, in the deep drawing, the thickness of the molded product is not uniform and the formability of details is inferior. In addition, foamed materials have high heat insulation properties, and it is difficult to transfer heat during heat molding, so it is necessary to perform molding under high temperature conditions. However, when molding is performed under high temperature conditions, the gas barrier film laminated on the surface is heated. There is a risk of being fused to a hot plate as a heating medium during molding. Also, when a polystyrene resin foam sheet is laminated, the polystyrene resin is excellent in moldability, but is more brittle at room temperature than the polypropylene resin and polyethylene resin, and easily cracks. Furthermore, the heat resistance is low, and there is a problem that deformation occurs when heated by a microwave oven.
The heat-resistant foam disclosed in Patent Document 3 has poor gas barrier properties, and a food packaged using this as a packaging base material cannot be stored for a long time. In addition, the heat-resistant foam disclosed in Patent Document 3 uses a polyphenylene ether resin having a unique strong odor, and a hydrophobic zeolite is added to remove this odor. The odor of ether could not be completely removed, and the odor moved to the food packaged as a packaging substrate, and after the food was heated in the microwave, there was a problem that the food felt a strange odor. .

  The present invention has been made in view of the above circumstances, and is a laminated sheet for producing a packaging substrate excellent in moldability, gas barrier property, odor blocking property, cold resistance, heat resistance, heat insulation and rigidity, and packaging using the laminated sheet An object is to provide a substrate and a food package using the packaging substrate.

  To achieve the above object, the present invention provides an adhesive layer, one or more gas barrier resin layers, and a sealant layer on one surface of a foamed sheet layer made of a polystyrene resin foam sheet containing a polyphenylene ether resin. A laminated sheet for producing a packaging base material, characterized in that it is laminated in this order.

  In the laminated sheet for manufacturing a packaging substrate of the present invention, it is preferable that 10-50 mass% of a polyphenylene ether-based resin is contained in the resin constituting the foamed sheet layer.

  In the laminated sheet for manufacturing a packaging substrate of the present invention, it is preferable that the gas barrier resin layer includes a polyamide resin layer.

  In the laminated sheet for producing a packaging substrate of the present invention, the gas barrier resin layer preferably contains an ethylene-vinyl acetate copolymer saponified resin layer.

  In the laminated sheet for producing a packaging substrate of the present invention, the sealant layer is preferably composed of a polyolefin resin layer.

  Moreover, this invention provides the packaging base material which consists of the said lamination sheet for packaging base material manufacture.

  In addition, the present invention provides a packaging substrate having a desired shape by thermoforming the laminated sheet for producing a packaging substrate.

  Moreover, this invention provides the food packaging body which mounts a foodstuff on the said packaging base material, and wraps these with a gas-barrier film.

  The laminated sheet for producing a packaging substrate of the present invention has an adhesive layer, one or more gas barrier resin layers, and a sealant on one surface of a foamed sheet layer made of a polystyrene resin foam sheet containing a polyphenylene ether resin. Since the layers are laminated in the order of layers, the foamed sheet layer provides excellent moldability, cold resistance, heat resistance, heat insulation and rigidity, and further laminates a multilayer film including a gas barrier layer on the foamed sheet layer. By doing so, excellent gas barrier properties and odor barrier properties can be obtained.

  The packaging substrate of the present invention comprises the laminated sheet for producing a packaging substrate, or is subjected to thermoforming to the laminated sheet for producing a packaging substrate to obtain a desired shape, so that the moldability, gas barrier property, It has excellent odor barrier properties, cold resistance, heat resistance, heat insulation, and rigidity, and when it is used to package food, etc., it can be stored in a vacuum pack or at a low temperature and stored for a long time. it can. In addition, stored foods and the like can be directly heated in a microwave oven, which is highly convenient. Furthermore, the odor from the foamed sheet layer caused by the polyphenylene ether-based resin can be completely blocked by the multilayer film including the gas barrier layer, and the odor is not transferred to food or the like, and the original flavor of the food is not impaired.

  Since the food package of the present invention is formed by placing food on the packaging substrate and wrapping them with a gas barrier film, it can be stored in a vacuum pack or at a low temperature, and can be stored for a long time. it can. In addition, stored foods and the like can be directly heated in a microwave oven, which is highly convenient. Furthermore, the odor from the foamed sheet layer caused by the polyphenylene ether-based resin can be completely blocked by the multilayer film including the gas barrier layer, and the odor is not transferred to food or the like, and the original flavor of the food is not impaired.

It is sectional drawing which shows one Embodiment of the lamination sheet for packaging base material manufacture which concerns on this invention. It is sectional drawing which shows one Embodiment of the food packaging body which concerns on this invention.

(Laminated sheet for manufacturing packaging substrate)
FIG. 1 is a view showing an embodiment of a laminated sheet for producing a packaging substrate according to the present invention. The laminated sheet 1 for manufacturing a packaging substrate according to this embodiment includes an adhesive layer 3 and a first gas barrier resin on one surface of a foamed sheet layer 2 made of a polystyrene resin foamed sheet containing a polyphenylene ether resin. The layer 4, the second gas barrier resin layer 5, and the sealant layer 6 are laminated in this order.

  The laminated sheet for manufacturing a packaging substrate 1 includes an adhesive layer 3, a first gas barrier resin layer 4, a second gas barrier resin layer 5, and a sealant layer 6 that are laminated on a foamed sheet layer 2. Laminated films (hereinafter, these laminated films are referred to as “gas barrier films”) are prepared in advance, and the foam sheet layer 2 is separately produced by extrusion foaming, and the gas barrier film is formed on the foam sheet layer 2. It is manufactured by laminating the adhesive layer 3 side of each other and bonding them together.

(Foamed sheet layer)
The foamed sheet layer 2 is prepared by mixing 50 to 90 parts by mass of a polystyrene resin and 10 to 50 parts by mass of a polyphenylene ether resin, supplying the resin material to an extruder of an extrusion foam molding apparatus, and heating the extruder in the extruder. Melting, 1 to 10 parts by mass of a foaming agent such as pentane or butane in the middle of the extruder is pressed and kneaded in the middle of the extruder, and the foaming agent-containing molten resin is extruded from the die slit at the tip of the extruder. It is manufactured by an extrusion foaming method in which it is foamed and cooled to be formed into a long sheet.

  Examples of the polystyrene resin include homopolymers of styrene monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene, or copolymers thereof. A polystyrene-based resin containing 50% by mass or more of styrene is preferable, and polystyrene is more preferable. Further, the polystyrene resin may be a copolymer of the styrene monomer and a vinyl monomer copolymerizable with the styrene monomer, the main component of which is the styrene monomer. As, for example, alkyl (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cetyl (meth) acrylate, (meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl In addition to fumarate and ethyl fumarate, bifunctional monomers such as divinylbenzene and alkylene glycol dimethacrylate are exemplified. As the polystyrene resin, other than polystyrene resins newly produced by methods such as commercially available ordinary polystyrene resins and suspension polymerization methods, polystyrene resins that are not recycled materials (virgin polystyrene) can be used, Recycled raw materials obtained by reprocessing used polystyrene-based resin foamed molded products can be used. Moreover, virgin polystyrene and a recycled raw material can be mixed and used. As this recycled material, used polystyrene-based resin foam moldings, for example, food packaging trays, fish boxes, household appliance cushioning materials, etc. are collected and recycled materials that are regenerated by the limonene dissolution method or heating volume reduction method. Can do. Recyclable raw materials that can be used include home appliances (eg, TVs, refrigerators, washing machines, air conditioners) and office work, in addition to those obtained by reprocessing used polystyrene-based resin foam moldings. A non-foamed polystyrene resin molded product that has been separated and collected from an industrial machine (for example, a copying machine, a facsimile machine, a printer, etc.), pulverized, melt-kneaded, and repelletized can be used. Among these, it is preferable to use all or part of a recycled material obtained by regenerating a food packaging tray which is a used polystyrene resin foam molded article.

  Examples of the polyphenylene ether resin include poly (2,6-dimethylphenylene-1,4-ether), poly (2,6-diethylphenylene-1,4-ether), and poly (2,6-dichloro). Polyphenylene ethers such as phenylene-1,4-ether) and the like, and in particular, modified polyphenylene ethers obtained by alloying other resins such as polystyrene resins with polyphenylene ether are preferable. Examples of commercially available polyphenylene ether resins preferably used in the present invention include “Noryl” (trade name) manufactured by Savic, “Zylon” (trade name) manufactured by Asahi Kasei Chemicals, and the like.

  In the resin component constituting the foamed sheet layer 2, the ratio of the polyphenylene ether-based resin is preferably in the range of 10 to 50% by mass, and more preferably in the range of 15 to 40% by mass. When the ratio of the polyphenylene ether-based resin is less than 10% by mass, rigidity and heat resistance are deteriorated, and the packaging base material is easily deformed when heated in a microwave oven. When the ratio of the polyphenylene ether resin exceeds 50% by mass, the moldability is deteriorated and the bad odor becomes strong, which is not preferable.

In the foamed sheet layer 2, in addition to the foaming agent, a foaming nucleating agent, a binding inhibitor, a cell regulator, a crosslinking agent, a filler, a flame retardant, as long as the physical properties of the foamable thermoplastic resin particles obtained are not impaired Additives such as flame retardant aids, lubricants, and colorants may be added.
Further, a deodorizing agent such as a zirconium phosphate deodorant and a zeolite deodorant can be added to the foam sheet layer 2.

The thickness of the foamed sheet layer 2 is not particularly limited, but is preferably in the range of 0.5 to 5.0 mm and more preferably in the range of 0.7 to 3.0 mm when used for normal food packaging applications.
The basis weight of the foam sheet layer 2 is in the range of 80 - 400 g / ^{m 2} is preferred.
The expansion ratio of the foam sheet layer 2 is preferably in the range of 1.3 to 10 times.

(Gas barrier film)
As described above, in the gas barrier film, the adhesive layer 3, the first gas barrier resin layer 4, the second gas barrier resin layer 5, and the sealant layer 6 are laminated in this order from the foam sheet layer 2 side. It is configured.

  The adhesive layer 3 only needs to be able to stably adhere the interlayer between the foam sheet layer 2 and the first gas barrier resin layer 4, and is appropriately selected from various adhesives according to the material of each layer and used. be able to. Examples of the adhesive layer 3 include an acrylic ester adhesive, an acrylic urethane adhesive, and a hot melt adhesive.

The first gas barrier resin layer 4 is composed of a polyamide-based resin or a polyester-based resin that is excellent in gas barrier properties, strong, deep drawing moldability, and pinhole resistance. Examples of the polyamide-based resin include one kind or a mixture of two or more kinds selected from various polyamide resins, and films such as alloys and copolymers with other resins. Examples of the polyester resin include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) films. Examples of PET include films such as APET (amorphous PET) and PETG (modified PET).
The thickness of the first gas barrier resin layer 4 is preferably in the range of 10 to 40 μm in the case of a polyamide resin film, and is preferably in the range of 20 to 1000 μm in the case of a polyester resin film.

The second gas barrier resin layer 5 is made of an ethylene-vinyl acetate copolymer saponified resin (EVOH) having excellent gas barrier properties.
The thickness of the second gas barrier resin layer 5 is preferably in the range of 5 to 25 μm.

The sealant layer 6 is a layer on the innermost side of the laminated sheet 1 for manufacturing a packaging substrate, and is a layer that comes into contact with food and is heat-sealed with a lid.
The resin used for the sealant layer 6 can be used without particular limitation as long as it is a polyolefin resin generally used as a sealant layer. For example, polyethylene such as low density polyethylene, linear low density polyethylene, and high density polyethylene, ethylene -Polyethylene resins such as vinyl acetate copolymers, ethylene-methacrylic acid copolymers and metal cross-linked products thereof; polypropylene resins and the like can be used alone or in combination. As the resin used for the sealant layer, it is particularly preferable to use a polyethylene resin, and it is more preferable to use a linear low-density polyethylene resin.
When the thickness of the sealant layer 6 is thin, the peel strength is insufficient, and when it is thick, the easy peel strength is likely to vary. Therefore, the thickness is preferably about 1 to 40 μm.

  The gas barrier film is formed by, for example, coextruding three layers of the first gas barrier resin layer 4, the second gas barrier resin layer 5 and the sealant layer 6, and then laminating the adhesive layer 3. Can be manufactured.

Note that the laminated sheet 1 for manufacturing a packaging substrate shown in FIG. 1 is merely an example of the present invention, and the laminated structure, material, thickness, and the like are not limited to the above examples, and can be changed or modified as appropriate.
For example, in the above example, the gas barrier resin layer has a two-layer structure, but it can be formed by any one layer or a laminated structure of three or more layers.
Moreover, each layer of the sealant layer 6, the gas barrier resin layers 4 and 5, and the foamed sheet layer 2 may be appropriately colored or printed with a product name, a logo, or the like as necessary.

This laminated sheet 1 for manufacturing a packaging substrate has an adhesive layer 3 on one side of a foamed sheet layer 2 made of a polystyrene-based resin foamed sheet containing a polyphenylene ether resin, and is strong and excellent in pinhole resistance. Since the first gas barrier resin layer 4, the second gas barrier resin layer 5 excellent in gas barrier property, and the gas barrier film laminated in the order of the sealant layer 6 are laminated, the foam sheet layer 2 Excellent moldability, cold resistance, heat resistance, heat insulation and rigidity can be obtained by laminating a gas barrier film, and excellent gas barrier properties and odor blocking properties can be obtained.
In addition, since the first gas barrier resin layer 4 having toughness and excellent pinhole resistance is provided, it is possible to prevent the packaging substrate from being pierced by a sharp toothpick or bamboo skewer.

(Packaging substrate)
The laminated sheet 1 for manufacturing a packaging substrate is cut into an appropriate size and used as a packaging substrate called a mount in the form of the sheet, or thermoformed into the laminated sheet 1 for producing a packaging substrate. Is used as a packaging base material having a desired shape. As the shape of the packaging substrate, in addition to the sheet shape, various shapes such as a tray shape, a plate shape provided with one or more recesses serving as a food storage portion, a cup shape such as a round shape or a square shape, and a bowl shape can do.

  A method and a manufacturing apparatus for manufacturing a packaging substrate of a desired shape by thermoforming the laminated sheet 1 for manufacturing a packaging substrate are, for example, well-known methods and manufacturing apparatuses used in the thermoforming of polystyrene resin foam sheets. Can be used. Moreover, also when printing on this packaging base material, it can implement using the known printing method and printing apparatus used at the time of printing of a polystyrene-type resin foaming molded object etc.

  Since this packaging substrate is composed of the laminated sheet 1 for producing a packaging substrate or thermoformed on the laminated sheet 1 for producing a packaging substrate to obtain a desired shape, the moldability, gas barrier property, It has excellent odor barrier properties, cold resistance, heat resistance, heat insulation, and rigidity, and when it is used to package food, etc., it can be stored in a vacuum pack or at a low temperature and stored for a long time. it can. In addition, stored foods and the like can be directly heated in a microwave oven, which is highly convenient. Furthermore, the odor from the foamed sheet layer 2 caused by the polyphenylene ether resin can be completely blocked by the gas barrier film, the odor does not move to foods and the like, and the original flavor of the food is not impaired.

(Food packaging)
FIG. 2 is a diagram showing an embodiment of a food package according to the present invention.
The food packaging body 13 of the present embodiment has a configuration in which foods 11 are placed on a packaging substrate 10 made of the laminated sheet 1 for producing a packaging substrate, and these are wrapped with a gas barrier shrink film 12.

  The kind of the food 11 packaged by the food packaging 13 is not particularly limited, and examples thereof include fresh fish such as salmon fillets, marine products such as abalone, shrimp, and squid, seafood processed products such as salmon grilled salmon, beef, pork, and the like. And cooked foods such as hamburgers, semi-cooked foods, pasta and other noodles, cooked rice, and confectionery. In addition to the food 11, the packaging substrate 10 can be packed with a small bag of seasoning materials such as soy sauce, sauce, and soy sauce, and dishes such as chopsticks, spoons, and forks.

  As the gas barrier shrink film 12, it is preferable to select and use a film having excellent gas barrier properties and shrinkability among conventionally known packaging films. As such a gas barrier shrink film 12, a cross-linked polyolefin multilayer shrink film or the like is preferably used.

  The food package 13 uses the well-known shrink wrapping technique, and the food 11 is hermetically packaged by gas pack packaging or vacuum pack packaging, and further stored at a low temperature to maintain the flavor of the food 11 for a long period of time. It becomes possible. In addition, the stored food 11 can be heated as it is in a microwave oven, which is highly convenient. Furthermore, the odor from the foamed sheet layer 2 caused by the polyphenylene ether resin can be completely blocked by the gas barrier film, the odor does not move to foods and the like, and the original flavor of the food is not impaired.

[Example 1]
(1) Production of gas barrier film First layer: L-LDPE (linear low density polyethylene), second layer: EVOH, third layer: three layers made of crystalline polyamide as sealant layer and gas barrier layer Polystyrene resin film (thickness) excellent in adhesion to a polystyrene resin foam sheet layer containing a polyphenylene ether resin as an adhesive layer on a film (Mitsubishi Resin Co., Ltd., trade name “DIAMIRON C906”, thickness 60 μm) 20 μm) was laminated by a dry laminating method to produce a gas barrier film.

(2) Production of polystyrene resin foam sheet containing PPE resin 70 parts by mass of polystyrene resin (DICPS GPPS (styrene homopolymer), trade name “XC-515”) and polyphenylene ether resin (PPE) ) And polystyrene resin (PS) mixed resin (trade name “Noryl EFN4230”, PPE / PS = 70/30, manufactured by Savic Co., Ltd.) 30 parts by mass, talc masterbatch (trade name “DSM1401A” Toyo) PS / talc = 60/40 manufactured by Styrene Co., Ltd. was dry blended in 1.0 part by mass, and this mixture was put into a hopper of a tandem extruder (caliber 115 mm-150 mm) having first and second extruders. While being melted and kneaded in the first extruder, butane (isobutane / normal butane = 65 / 5) was pressed total amount of 3.0 parts by weight per 100 parts by weight of polystyrene resin and polyphenylene ether resin. Further, the melt mixture obtained by kneading is continuously supplied from the first extruder to the second extruder, extruded and foamed into a cylindrical shape from an annular mold connected to the tip of the second extruder, and has a thickness of 1.5 mm. A polystyrene resin foam sheet having a basis weight of 220 g / m ² was produced.

(3) Production of laminated sheet for manufacturing packaging substrate The gas barrier film obtained in (1) above is laminated on the polystyrene resin foam sheet containing the PPE resin obtained in (2) by a hot roll. To produce a laminated sheet for manufacturing a packaging substrate having the structure shown in FIG.

(4) Production of food packaging body The laminated sheet for production of packaging base material produced in (3) above is shallowly formed using a packaging machine (trade name “R530” manufactured by Mulchback Co., Ltd.) to produce a packaging base material. did.
The recess of the obtained packaging substrate (hereinafter referred to as a container) is filled with food (boiled salmon fillet: 200 g), and a gas barrier shrink film (trade name “CRYOVAC film”, thickness 150 μm, manufactured by Shield Air) is used. Covered and vacuum-sucked, heat-sealed to seal the food, to obtain a food package.

  The food packaging prepared as described above was subjected to the following <low temperature drop cracking test>, <range up resistance test>, and <odor test> to evaluate the performance. The results are shown in Table 1.

<Low temperature drop cracking test>
The food package was stored in a freezer at −20 ° C. for 24 hours to freeze the food as the contents, and used as a drop test sample. This drop test sample was dropped on a steel plate from a height of 100 cm in a -20 ° C freezer, and a cracking test of the container at a low temperature was performed. The evaluation criteria were as follows.
Good (○): No cracking Bad (×): Cracking or cracking occurred

<Range up resistance test>
The range-up resistance test was performed by heating the food package for 5 minutes in a 500 W microwave oven. The evaluation criteria were as follows.
Good (○): No deformation of the container
Defect (x): Deformed container

<Odor test>
After the food packaging was ranged up, a sensory test was carried out by the odor when food (boiled salmon fillet) was included in the mouth. In addition, evaluation was performed by relative comparison using a standard sample of the sashimi fillet without packaging.
The sensory test evaluation was as follows.
Good (○): I did not feel a bad smell Bad (×): I felt a bad smell

[Example 2]
When preparing a polystyrene-based resin foam sheet containing a PPE-based resin, zirconium phosphate-based deodorant (trade name “Kesmon NS-10”) manufactured by Toa Gosei Co., Ltd. as a deodorizing component was added to 100 parts by mass of the resin component. On the other hand, a polystyrene resin foam sheet was prepared by blending 0.5 parts by mass. Other than that produced the food packaging body similarly to Example 1. FIG. The results are shown in Table 1.

[Comparative Example 1]
A food package in which food was sealed without laminating a gas barrier film on the polystyrene resin foam sheet containing the PPE resin obtained in Example 1 was prepared, and the other processes were performed in the same manner as in Example 1. . The results are shown in Table 1.

[Comparative Example 2]
Instead of the polystyrene resin foam sheet in Example 1, 100 parts by mass of a polystyrene resin (GPPS (styrene homopolymer) manufactured by DIC, trade name “XC-515”) is used to produce a polystyrene resin foam sheet. Otherwise, a food sealed container was prepared in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
As a gas barrier film, the first layer: LLDPE, the second layer: EVOH, the third layer: a three-layer film (made by Mitsubishi Plastics, trade name: Diamilon C906, thickness 60 μm) made of crystalline polyamide resin A film in which L-LDPE (thickness: 30 μm) was laminated by a dry laminating method to give adhesion to the HDPE foam layer as four layers was obtained.
As a foam sheet, 100 parts by mass of high-density polyethylene (trade name “HS451” manufactured by Nippon Polyethylene Co., Ltd.) and a master batch of a mixture of sodium bicarbonate and citric acid as a foam regulator (trade name “Finecell Master manufactured by Dainichi Seika Co., Ltd.”) 0.4 parts by weight of SSCPO410 "was dry blended, and this mixture was supplied to a hopper of a tandem extruder (caliber 90 mm to 115 mm) having first and second extruders, and melted in the first extruder. While being kneaded, butane (isobutane / normal butane = 65/35) was injected as 1 part by mass per 100 parts by mass of the resin, and the melt-kneaded molten mixture was continuously fed from the first extruder to the second extruder. And is extruded and foamed into a cylindrical shape from an annular mold connected to the tip of the second extruder, and HDP having a thickness of 0.75 mm and a basis weight of 300 g / m ² An E-based resin foam sheet was produced.
A barrier film was thermally fused to the obtained HDPE foam sheet by thermal lamination to produce a barrier laminate foam sheet, and a food package was produced in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
As a foam sheet, 25 parts by mass of polypropylene resin (A) (trade name “SD632” manufactured by Sun Allomer Co., Ltd.), 75 parts by mass of polypropylene resin (B) (trade name “PM 600” manufactured by Sun Allomer Co., Ltd.), Master batch of a mixture with citric acid (trade name “Finecel Master SSCPO410” 0.19 parts by mass manufactured by Dainichi Seika Co., Ltd. was dry blended, and this mixture was tandem extruded with first and second two extruders. 1 part by weight of 100 parts by weight of resin was fed into butane (isobutane / normal butane = 65/35) as a foaming agent while being melted and kneaded in the first extruder. Further, the melt mixture obtained by kneading is continuously supplied from the first extruder to the second extruder, and connected to the tip of the second extruder. A polypropylene resin foam sheet having a thickness of 0.8 mm and a basis weight of 310 g / m ² was produced by extrusion foaming from a cylindrical mold into a cylindrical shape.
The barrier film obtained in Comparative Example 3 was heat-sealed by heat lamination to a polypropylene resin foam sheet to produce a barrier laminate foamed sheet, and a food package was produced in the same manner as in Example 1. The results are shown in Table 1.

（表中、ＰＰＥはポリフェニレンエーテル系樹脂、ＰＳはポリスチレン系樹脂、ＨＤＰＥは高密度ポリエチレン、ＰＰはポリプロピレンを表す。）

(In the table, PPE represents polyphenylene ether resin, PS represents polystyrene resin, HDPE represents high density polyethylene, and PP represents polypropylene.)

From the results shown in Table 1, the food packaging bodies of Examples 1 and 2 according to the present invention are less likely to crack the container even when stored frozen, while the container does not deform even when heated in a microwave oven, and is excellent. It had cold resistance, heat resistance and rigidity. In addition, the food packaging bodies of Examples 1 and 2 did not transfer odor to the food heated by the microwave oven, and did not impair the original flavor of the food.
On the other hand, the food packaging body of Comparative Example 1 without the gas barrier film was subjected to a sensory test with the food (boiled fillet) in the mouth after range-up, and felt a peculiar odor peculiar to the PPE resin.
Moreover, the food packaging body of the comparative example 2 using the polystyrene resin foam sheet which does not contain PPE was insufficient in cold resistance and heat resistance, and evaluation was bad about the low temperature drop test and the range-up test.
Moreover, the food packaging body of Comparative Example 3 using the HDPE foam sheet was insufficient in heat resistance, and the evaluation for the range-up test was poor.
Moreover, the food packaging body of the comparative example 4 using a polypropylene foam sheet was insufficient in cold resistance, and the evaluation about the low temperature drop test was poor.

  The present invention relates to a packaging substrate used for gas pack packaging of food and vacuum packaging, etc., and packaging substrate excellent in moldability, gas barrier property, odor blocking property, cold resistance, heat resistance, heat insulation and rigidity. The present invention relates to a laminated sheet for production, a packaging substrate using the laminated sheet, and a food packaging body using the packaging substrate.

  DESCRIPTION OF SYMBOLS 1 ... Laminated sheet for packaging base material manufacture, 2 ... Foam sheet layer, 3 ... Adhesive layer, 4 ... 1st gas barrier resin layer, 5 ... 2nd gas barrier resin layer, 6 ... Sealant layer, 10 ... packaging substrate, 11 ... food, 12 ... gas barrier shrink film, 13 ... food package.

Claims (8)

  An adhesive layer, one or more gas barrier resin layers, and a sealant layer are laminated in this order on one surface of a foamed sheet layer made of a polystyrene-based resin foamed sheet containing a polyphenylene ether-based resin. Laminated sheet for manufacturing packaging substrates.   The laminated sheet for producing a packaging substrate according to claim 1, wherein the resin constituting the foamed sheet layer contains 10-50 mass% of a polyphenylene ether resin.   The laminated sheet for manufacturing a packaging substrate according to claim 1 or 2, wherein the gas barrier resin layer includes a polyamide-based resin layer.   The said gas barrier resin layer contains the ethylene-vinyl acetate copolymer saponification resin layer, The laminated sheet for packaging base material manufacture of any one of Claims 1-3 characterized by the above-mentioned.   The said sealant layer consists of a polyolefin-type resin layer, The laminated sheet for packaging base material manufacture of any one of Claims 1-4 characterized by the above-mentioned.   A packaging substrate comprising the laminated sheet for producing a packaging substrate according to any one of claims 1 to 5.   The packaging base material which thermoforms to the laminated sheet for packaging base material manufacture of any one of Claims 1-5, and becomes a desired shape.   A food package comprising a food product placed on the packaging substrate according to claim 6 and wrapped with a gas barrier film.

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