JP4460142B2 - Package - Google Patents

Description

【００６１】
【表２】

【００６２】
【表３】

【００６３】
これらの結果から、各実施例のフィルムは、いずれも本包装形態における重要な特性、品質を全て満足しており、優れた包装体を形成できることが分かる。
【００６４】
【発明の効果】
以上説明したように、本発明の包装体は、従来のストレッチ包装に比べてフィルムの使用面積が少なく、また、蓋付き容器に比べても包装コストが安く、かつ、いずれの包装形態に比較しても液漏れを略完全に防止できる従来にない画期的な包装体であり、特に食品用包装体として最適である。
【図面の簡単な説明】
【図１】 本発明の包装体を製造するために用いられる包装機の概略図である。
【図２】 包装動作の説明図である。
【図３】 包装動作の説明図である。
【図４】 トレー及びヒートローラの配置を示す平面図である。
【図５】 ヒートローラの動作を示す平面図である。
【図６】 フィルムがトレーのフランジに密着した状態を示す図である。
【図７】 フィルムがトレーのフランジ部にヒートシールされ、フィルムが溶断される状態を示す図である。
【図８】 被計量物が載せられた本発明の包装体の概要断面図である。
【符号の説明】
１…包装装置、２…トレーの保持部材、３…ヒートローラ、５…フィルム供給機構、６…リフト機構、１０…ラップフィルム、１１…被包装物、１２…トレー、５１…フィルム供給ローラ、５２ａ，５２ｂ…搬送ローラ、５２ｃ，５２ｄ…押えローラ、５３…フィルム巻き取りローラ、５４…ベルト、６３…移動部、７２…リンク機構、７３…押え板、７４…レバー機構、８１…回転軸、８２…モータ[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a package, and more particularly, to a package optimal for food in which food is placed in a lightweight tray in packaging of fresh food, prepared dishes, etc., and the edge (flange) portion is sealed with a wrap film to form a lid portion. .
[0002]
[Prior art]
Conventionally, as pre-package packaging for fresh foods, side dishes, etc., a packaging form (stretch packaging) in which food in a lightweight polystyrene paper (PSP) tray is overlap-wrapped with a stretch film has been most popular. However, in the case of foods containing liquids such as juice and oil, the liquid may go around from the edge portion of the tray to the bottom portion, which may impair the appearance or cause the seal portion to peel off.
[0003]
In addition, containers with transparent lids are increasingly used in side dishes that emphasize display effects and product protection, such as shape collapse due to stacking and handling, and prevention of peeling of wrapped films. However, in the case of a container with a lid, problems such as high cost as a packaging material and leakage of liquid from a fitting portion between the lid and the bottom material cannot be solved in the same manner as in stretch packaging. Furthermore, when the container is disposed of, there is a problem that it is bulkier than the stretch film and increases in weight.
[0004]
[Problems to be solved by the invention]
On the other hand, a top-seal type packaging form in which a flange is heat-sealed by covering a PSP tray with a film is also used in a very small part. However, this packaging form requires that the shape of the tray is limited due to the mechanism of the packaging machine, and that the layer on the seal side of the film must be the same layer of styrenic material as the tray. In some cases, an adhesive resin layer is required for the film. As a result, the cost of the film is high, and the film does not have sufficient stretch properties as a stretch film.
[0005]
Further, it is conceivable to use a tray made of polyethylene or polypropylene resin instead of a tray made of polystyrene material. However, when a commercially available polyolefin-based stretch film is used as it is and the flange portion of the tray is sealed, there is a problem that sufficient sealing strength cannot be obtained although packaging can be performed without wrinkles.
[0006]
Accordingly, an object of the present invention is to provide a package that has a small film use area, is low in packaging cost, can be completely prevented from leaking liquid, and has a sufficient sealing strength.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, the package of the present invention uses a tray made of polypropylene resin or polyethylene resin, or a tray laminated with these resins on the surface, and heats the wrap film on the edge (flange) portion of the upper surface of the tray. A package formed by sealing, wherein the wrap film has a structure of two or more layers, and the tray and the heat-sealed layer are made of a linear low density polyethylene resin (A) produced by a metallocene catalyst, A layer made of resin (B) having a crystal melting peak temperature measured by raising the temperature at a scanning rate of 10 ° C./min with a scanning calorimeter is 10 to 70 ° C. higher than that of the resin (A) is laminated on the resin (A) layer.The density of the resin (A) is 0.86 to 0.93 g / cm. ³ In this range, the thickness of the resin (A) layer is 0.5 μm or more, and the total thickness occupied by the resin (A) layer in the wrap film is less than 10 μm.It is characterized by that.
[0008]
  Also,The resin (B) laminated on the linear low density polyethylene resin (A) contains 30% by weight or more of polypropylene, and the peel strength of the heat seal surface between the tray and the wrap film is 300 g / It is characterized by a width of 15 mm or more.
[0009]
The package of the present invention uses the tray and wrap film as described above, and heat seals the wrap film only on the upper part of the tray, thereby preventing liquid leakage as compared with a container with a lid and a conventional stretch stretch packaging. In addition to being extremely high, it is possible to provide a packaging form with excellent packaging costs.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
First, the packaging body of the present invention is a packaging body in which a wrap film is heat-sealed on a tray made of a polypropylene resin or a polyethylene resin or an edge (flange) portion of the upper surface of a tray laminated with these resins on the surface, By making the structure of the wrap film into a structure of two or more layers made of a specific resin, both the fusing property of the film at the time of packaging and the high heat seal strength after packaging are achieved. It is an epoch-making packaging form with excellent prevention.
[0011]
The tray is made of polypropylene resin or polyethylene resin, or is laminated on the surface thereof. By forming a layer of polypropylene or polyethylene on the surface, for example, when packaging food containing a small amount of oil, it retains its shape without deformation or melting even when heated in a microwave oven In addition to providing practical heat resistance, sufficient sealing strength can be obtained in heat sealing with a wrap film described later.
[0012]
The resin for forming the tray surface is not particularly limited as long as it is a polypropylene resin or a polyethylene resin, but in the case of a polypropylene resin, it has a melting point close to the melting point of the heat seal side resin of the wrap film. Therefore, a random copolymer of propylene and ethylene having a relatively low melting point is more preferable.
[0013]
On the other hand, the material and structure of the wrap film sealed on the upper surface of the tray is a linear low-density polyethylene in which at least the surface to be heat-sealed with the tray is manufactured with a metallocene catalyst among the front and back layers of two or more layers. It is a resin (A) layer. The resin (A) on the heat seal surface side has a density of 0.86 to 0.93 g / cm.³In this range, the layer thickness is preferably 0.5 μm or more, and the total thickness occupied by the resin (A) layer in the wrap film is preferably less than 10 μm. The linear low density polyethylene resin (A) layer has a melting point higher than that of the resin (A) by 10 to 70 ° C., specifically, the temperature is increased at a scanning speed of 10 ° C./min with a differential scanning calorimeter. The crystal melting peak temperature measured in this manner is laminated with a layer made of the resin (B) which is 10 to 70 ° C. higher than the resin (A).
[0014]
In order to achieve the object of the present invention, the linear low density polyethylene resin (A) on the heat seal surface side must be produced by a metallocene catalyst. A linear low-density polyethylene resin using a metallocene catalyst has a more uniform molecular weight distribution and branching state and higher heat seal strength than a polyethylene resin produced using conventional Ziegler and Natta catalysts. In this package, since the heat seal surface is limited to the flange portion of the tray, a complete seal is required at that portion, but as shown in the examples described later, the seal mechanism using four heater rollers, Even if the sealing conditions vary slightly for some reason, a metallocene linear low density polyethylene resin can provide a remarkable effect that a very stable sealing state can be obtained.
[0015]
The density of the linear low density polyethylene resin (A) used in the present invention is 0.86 to 0.93 g / cm.³The range of is preferable. Density is 0.86 g / cm³The film crystallinity and the melting point of the film are too low, and the film is likely to be blocked, the peeling resistance at the time of unwinding the film becomes too large, or the sealing layer is completely melted when heat-sealing with the tray. Seal strength may not be obtained. The density is 0.93 g / cm³If it exceeds 1, the crystallinity is too high and the seal temperature range is narrowed, so that sufficient seal strength cannot be obtained. In addition, there is a problem that it is difficult to obtain sufficient transparency in a film forming method by an inflation method described later.
[0016]
Further, the thickness of the linear low-density polyethylene resin (A) layer on the heat seal surface side is preferably 0.5 μm or more, more preferably 1 μm or more. If it is less than 0.5 μm, sufficient heat seal strength cannot be obtained when heat-sealing with a tray. However, when the linear low-density polyethylene resin (A) is melted by heat, the cut surface is not clean, and it cuts like pulling a thread. In addition, the total thickness of the linear low-density polyethylene resin (A) layer in the entire wrap film including the layer on the heat seal surface side is set to 10 μm or less. It is preferable.
[0017]
Moreover, in order to improve the cutting property (melting property) at the time of fusing of a wrap film, it is preferable to laminate | stack with resin with favorable fusing property. Specifically, long-chain branched low-density polyethylene, polybutene-1, ethylene-vinyl acetate copolymer, ethylene-alkyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid produced by a high-pressure method Illustrative examples include acid copolymers, ionomers of ethylene polymers, and propylene polymers.
[0018]
On the other hand, on the sealing mechanism of the package, it is necessary to achieve not only the fusing property but also the heat resistance of the film that can withstand heat sealing. For this purpose, the linear low-density polyethylene resin (A) It is necessary to have a laminated structure of two or more layers having at least one resin (B) layer having a higher melting point of 10 to 70 ° C. Specifically, it is preferable to arrange a resin layer containing 30% by weight or more of a propylene polymer as the resin (B) layer. Propylene resin generally has a melting point 20 ° C to 60 ° C higher than that of polyethylene resin, and can prevent perforation due to melting of the film when heat for heat sealing is applied to the wrap film. It is suitable in terms of improving heat resistance as a whole. In this respect, the content of the propylene-based resin is preferably 30% by weight or more. If the content is less than 30% by weight, the mixed resin layer does not have sufficient heat resistance, and the hole is formed by melting the film by heat sealing during packaging. May occur.
[0019]
However, in order to give flexibility and elongation uniformity as a wrap film, a relatively soft polymer obtained by copolymerizing propylene and ethylene or ethylene-propylene rubber or the like and a low crystal whose stereoregularity is controlled as necessary. It is preferable to impart flexibility by blending a propylene-based polymer, a copolymer of vinyl aromatic and conjugated diene, or a hydrogenated derivative thereof. At this time, a melt flow ratio (MFR) of 0.2 to 10 g / min is preferable from the viewpoint of moldability.
[0020]
Furthermore, in this invention, other resin (C) with favorable fusing property can also be laminated | stacked besides a heat seal layer. In particular, in molding by the air-cooled inflation method, a new resin layer can be provided in order to improve transparency and improve the stability of bubbles during molding. Specifically, an ethylene-vinyl acetate copolymer can be suitably used. The ethylene-vinyl acetate copolymer has relatively good fusing properties, can improve transparency and bubble stability, and is excellent in compatibility with the additives described below. It is suitable as a layer other than the heat seal layer.
[0021]
As a laminated structure, when a linear low density polyethylene resin layer is an A layer, a layer made of a propylene-based resin is a B layer, and other resin layers having good fusing properties are C layers,
A layer / B layer
A layer / B layer / A layer
A layer / B layer / C layer
A layer / B layer / C layer / A layer
A layer / B layer / C layer / B layer / A layer
A layer / C layer / B layer / C layer / A layer
And so on. At this time, the raw material can be effectively used by mixing the raw material in any layer or adding a layer of the raw material from these laminated films.
[0022]
The total thickness of the wrap film is preferably 5 to 30 μm, more preferably 8 to 20 μm. If the total thickness of the film is 5 μm or less, there is a risk of sagging or tearing due to stacking of products, etc. If it exceeds 30 μm, not only will it be disadvantageous in terms of film cost, but if it is stretched slightly during packaging The shrinkage stress of the film becomes too high, and the tray may be deformed or wrinkles may remain.
[0023]
The wrap film can be obtained by melt-extruding a material from an extruder and forming it into a film shape by inflation molding or T-die molding. In the case of a laminated film, it is advantageous to co-extrusion with a multilayer die.
[0024]
Practically, it is preferable that the material resin is melt-extruded and blown from the viewpoint of the balance of elongation characteristics in both the MD and TD directions during stretching, and the blow-up ratio (bubble diameter / die diameter) is 4 or more. In particular, the range of 5 to 7 is suitable.
[0025]
In addition, various additives can be added to the wrap film in order to impart performances such as antifogging properties, antistatic properties, and slipperiness. For example, surfactants such as glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, and ethylene oxide adduct can be appropriately added.
[0026]
The wrap film having the above-described configuration is placed on the tray (on which an object to be packaged such as food is placed), heat sealed at the flange portion of the tray to form a lid, and protrudes from the flange portion. The film portion is melted to form the package of the present invention (see FIG. 8). In addition, when covering a tray with a film and performing heat sealing by a flange part, it is preferable to use a packaging machine as shown in the below-mentioned Example.
[0027]
In the present invention, the heat sealing of the wrap film at the flange portion of the tray is performed by a heater pressing the flange portion of the tray from above the wrap film. The heat seal condition is that the heater roller moves on the film at a temperature of usually 180 ° C. to 200 ° C. while holding the wrap film with its own weight, and the sealing speed is 100 msec / cm to 200 msec / cm. it can.
[0028]
Fusing of the wrap film that protrudes from the flange portion of the tray is performed at the same time as or immediately after heat sealing, but since the wrap film is in a heated state, as shown in the examples described later, Since moderate tension is applied, the wrap film protruding from the tray is melted while being pulled. At this time, a cutter may be used as an auxiliary.
[0029]
In this way, in order to obtain this package, the wrap film is required to have good heat sealability and fusing performance at the flange end in addition to appropriate stretchability. A good package cannot be obtained. In the present invention, by using the wrap film having the above-described configuration, a practical package was successfully obtained for the first time.
[0030]
【Example】
Hereinafter, the effect of the present invention will be clarified by examples. In addition, about the characteristic and performance of a film, and the characteristic of the packaging sample, it measured and evaluated by the following method.
[0031]
1) Crystal melting peak temperature of material resin
The crystal melting peak temperature was measured when the temperature of the material was raised under the following conditions using DSC-7 manufactured by PerkinElmer.
Temperature conditions: −50 ° C. (1 minute hold) → 250 ° C. (1 minute hold)
Scanning speed: 10 ° C / min
[0032]
2) Haze value of film
The haze value of one wrap film obtained using NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. was measured.
[0033]
3) Fusing property during packaging
A top tray packaging machine (Ishida Co., Ltd. (Japanese Patent Application No. 2000-104433) packaging machine) was used to wrap a predetermined tray with a wrap film, and the cut state of the end face of the wrap film was evaluated.
[0034]
4) Seal strength
After cutting 12 pieces of strip-shaped test pieces 15 mm wide in the direction perpendicular to the flange from the heat-sealed flange portion of the packaging sample, the wrap film side was affixed with tape to prevent stretching, and then made by Shimadzu Corporation. Using a tensile tester AGS-H, 500N, perform a tensile test by chucking the lap film and tray at a temperature of 20 ° C and a chuck distance of 50 mm, the maximum peel load as the heat seal strength, and average the 12 data And asked.
[0035]
5) Liquid leakage vibration test
(1) Preparation of packaging samples
Using the above-described top seal packaging machine, 50 g of water is put into a tray (the tray flange width is 5 mm, the dimensions of the tray including the flange are 100 mm length, 80 mm width, 30 mm height) to prepare a packaging sample. .
[0036]
▲ 2 ▼ Excitation conditions
Excitation time: 24 hours
Vibration frequency: 5Hz-50Hz (12 minutes by reciprocation)
Sweep method: logarithmic sweep
Excitation acceleration: 1G
[0037]
(3) Evaluation method
After the vibration test, the tray was tilted, and pinholes and water leaks were checked with pressure applied to the film, and the state was observed.
[0038]
6) Film formation stability
The bubble stability at the time of forming a film with an inflation film-forming facility was evaluated. Evaluation was as follows.
◎ Extremely stable
○ Stable
△ Slightly unstable
× No film formation
[0039]
Example 1
(1) Wrap film
<< Interlayer resin composition >> (B)
(1) Propylene-ethylene random copolymer (ethylene 2 mol%, MFR at 230 ° C. = 2.3 g / 10 min, crystal melting peak temperature 150 ° C.)
(Hereinafter abbreviated as PP): 50% by weight
(2) Propylene-ethylenepropylene rubber copolymer (ethylene 23 mol%, MFR at 230 ° C. = 1.5 g / 10 min, crystal melting peak temperature 152 ° C.)
(Hereinafter abbreviated as PER): 20% by weight
(3) Hydrogenated derivative of styrene-isoprene-styrene triblock copolymer comprising 20% by weight of styrene and 80% by weight of polyisoprene
(Hereinafter abbreviated as HSIS): 30% by weight
The mixed resin composition comprising the above three components (1), (2), and (3) was used as an intermediate layer. The crystal melting peak temperature of this mixed resin composition was 151 ° C.
[0040]
<< Front and back layer resin composition >> (A)
Linear low density polyethylene resin polymerized by metallocene catalyst (ethylene-hexene-1 copolymer, density 0.905 g / cm³MFR at 190 ° C. = 3.5 g / 10 min, crystal melting peak temperature of 97 ° C., hereinafter abbreviated as MLL) 98% by weight and 2% by weight of diglycerin monooleate as an antifogging agent are melt-blended. It was.
[0041]
A film having a total thickness of 15 μm (thickness ratio: 3 μm / 9 μm / 3 μm) was obtained from the resin composition forming the intermediate layer and the front and back layers by a coextrusion inflation method.
[0042]
(2) Tray
The tray is prepared by laminating a polypropylene film (thickness 30 μm) on the surface of expanded polystyrene (the width of the tray flange is 5 mm, the dimensions of the tray including the flange are 100 mm long, 80 mm wide, 30 mm high). Then, 50 g of water was put in the tray.
[0043]
(3) Formation of package
1 to 3 show an outline of the structure and operation of the top seal packaging machine 1. In this top seal packaging machine 1, when a tray 12 (packaged object is not shown) on which a packaged object (water in this embodiment) is placed is placed on the holding member 2, a film roll set of the film supply mechanism 5. The wrap film 10 is paid out from the part 51 (FIG. 1). Two belts 54a stretched around the transport rollers 52a and 52b and two belts 54b stretched around the presser rollers 52c and 52d (these belts hold down the end in the width direction of the film). Attached) is moved in a direction perpendicular to the conveying direction, and the wrap film is stretched in the width direction. As a result, the wrap film 10 is in a state of being tensioned in the width direction. Next, the moving part 63 of the lift mechanism 6 rises, and the tray 12 pushes up the wrap film 10 and stops (FIG. 2).
[0044]
As the tray 12 is pushed up, the wrap film 10 is further tensioned along the transport direction. As shown in FIG. 6, the wrap film 10 is in close contact with the flange portion of the tray 12. Next, the downward biasing of the lever mechanism 74 against the presser plate 73 is eliminated and the link mechanism 72 is opened, so that the heat roller 3 moves until it contacts the tray by its own weight (FIG. 3). As shown in FIG. 4, four heat rollers 3 are provided, but are independent of each other, and thus contact the tray 10 with the same pressure.
[0045]
Next, the heat roller 3 is rotated as shown in FIG. 5 by rotating the rotating shaft 81 by a predetermined angle by the motor 82. At this time, the heat roller 3 moves so as to trace the flange portion of the tray 10. In this embodiment, the surface temperature of the heat roller 3 is set to 190 ° C., whereby the film 10 is heat-sealed to the flange portion of the tray 12 and the portion protruding therefrom is melted (FIG. 7). In this embodiment, the sealing speed of the heat roller 3 is 100 msec / cm.
[0046]
When the sealing of the wrap film 10 to the flange portion of the tray 12 is finished, the heat roll 3 is pulled up, the tray 12 is lowered by the lift mechanism 6, packaging is completed, and the tray 12 is taken out from the holding member 2. The film 10 from which the central portion of the film has been removed by the above-described packaging operation is taken up by the take-up roller 53. Thereby, the package of the state shown in FIG. 8 is obtained. In this embodiment, water is put in the tray 12 and sealing is performed. However, even if a packaged object such as food is placed on the tray and sealed, sealing can be performed in the same procedure. When the height of the body is larger than the depth of the tray, the wrap film rises along the packaged body.
[0047]
Example 2
Diglycerin monooleate as an antifogging agent in 98% by weight of ethylene-vinyl acetate copolymer (va = 15% by weight, MFR at 190 ° C. = 2.3 g / 10 minutes, crystal melting peak temperature 91 ° C .: hereinafter abbreviated as EVA) A composition obtained by melt-mixing 2% by weight is newly provided as 2 or 4 layers between the intermediate layer and the resin composition of the front and back layers in the same manner as in Example 1 to form a 5-layer structure, and by coextrusion inflation method, A film having a thickness of 15 μm (thickness ratio of 2 μm / 2 μm / 7 μm / 2 μm / 2 μm) was obtained. This film was used and packaged in the same procedure as in Example 1 in the same tray.
[0048]
Example 3
A film having a total material thickness of 15 μm (thickness ratio of 11 μm / 2 μm / 9 μm / 2 μm / 1 μm), in which only the thickness ratio is changed, is made of a film having the same material structure as that of Example 2, and this film is used as in Example 1. In the same manner, the trays were packed.
[0049]
Example 4
The same film as in Example 3 was used, and the tray was packaged in place of a foamed polystyrene surface laminated with a polyethylene film (thickness 30 μm) (length 100 mm, width 80 mm, height 30 mm).
[0050]
Comparative Example 1
A linear low density polyethylene (ethylene-octene-1 copolymer, density: 0.917 g / cm) polymerized by Ziegler and Natta catalyst only for the material of the front and back layers of Example 2.³, MFR at 190 ° C. = 2.1 g / 10 minutes, crystal melting peak temperature 114 ° C .: hereinafter abbreviated as LL), except for changing to a composition in which 98% by weight of diglycerin monooleate 2% by weight is melt-mixed as an antifogging agent Obtained a film having a total thickness of 15 μm (thickness ratio: 2 μm / 2 μm / 7 μm / 2 μm / 2 μm) in the same manner as in Example 2. Using this film, the same tray as in Example 1 was packaged in the same procedure.
[0051]
Comparative Example 2
Anti-fogging agent to 98% by weight of ethylene-vinyl acetate copolymer (va = 15%, MFR at 190 ° C. = 2.3 g / 10 min) used for the front and back layers of Example 1 in Examples 2, 2 and 4 A film having a total thickness of 15 μm (thickness ratio: 3 μm / 9 μm / 3 μm) was obtained in the same manner as in Example 1 except that the composition was obtained by melt-mixing 2% by weight of diglycerin monooleate. Using this film, the same tray as in Example 1 was packaged in the same procedure.
[0052]
Comparative Example 3
Only the thickness ratio was changed in the same material configuration as in Example 1, and a film having a total thickness of 15 μm (thickness ratio of 6 μm / 3 μm / 6 μm) was obtained. Using this film, the same tray as in Example 1 was packaged in the same procedure.
[0053]
Comparative Example 4
Only the thickness ratio was changed in the same material configuration as in Example 2, and a film having a total thickness of 15 μm (thickness ratio 0.3 μm / 3.7 μm / 7 μm / 3.7 μm / 0.3 μm) was obtained. Using this film, the same tray as in Example 1 was packaged in the same procedure.
[0054]
Comparative Example 5
The front and back layers use the same MLL resin composition as in Example 1, and the intermediate layer uses the same EVA resin composition as used in the second and fourth layers of Example 2, as in Example 1. A film having a total thickness of 15 μm (thickness ratio: 3 μm / 9 μm / 3 μm) was obtained. Using this film, the same tray as in Example 1 was packaged in the same procedure.
[0055]
Comparative Example 6
The front and back layers use the same MLL resin composition as in Example 1, and the intermediate layer uses a polyamide resin (crystal melting peak temperature 220 ° C.), and the total thickness is 15 μm (thickness ratio: 3 μm / 9 μm / 3 μm) film was obtained. Using this film, the same tray as in Example 1 was packaged in the same procedure.
[0056]
Comparative Example 7
Using the same film as in Example 2, only the tray was changed to a surface without polystyrene foam laminate (length 100 mm, width 80 mm, height 30 mm) and packaged. Using this film, the same tray as in Example 1 was packaged in the same procedure.
[0057]
Comparative Example 8
50 g of water was put inside using the tray used in Example 1 and a commercially available polyolefin-based stretch film, and overlap-wrapped by a push-up packaging machine (WminiZERO1 manufactured by Ishida Co., Ltd.).
[0058]
Comparative Example 9
A normal container with a fitting lid was used, and 50 g of water was put inside and the lid was put on.
[0059]
The film characteristics in each Example and each Comparative Example are shown in Table 1, the characteristic evaluation of each packaging sample is shown in Table 2, and the comprehensive evaluation criteria are shown in Table 3.
[0060]
[Table 1]

[0061]
[Table 2]

[0062]
[Table 3]

[0063]
From these results, it can be seen that the film of each example satisfies all the important characteristics and quality in the present packaging form and can form an excellent package.
[0064]
【The invention's effect】
As described above, the packaging body of the present invention uses less film than conventional stretch packaging, and has a lower packaging cost than a container with a lid, and compared to any packaging form. However, it is an unprecedented innovative package that can almost completely prevent liquid leakage, and is particularly suitable as a food package.
[Brief description of the drawings]
FIG. 1 is a schematic view of a packaging machine used for producing a package of the present invention.
FIG. 2 is an explanatory diagram of a packaging operation.
FIG. 3 is an explanatory diagram of a packaging operation.
FIG. 4 is a plan view showing the arrangement of trays and heat rollers.
FIG. 5 is a plan view showing the operation of the heat roller.
FIG. 6 is a view showing a state where a film is in close contact with a flange of a tray.
FIG. 7 is a view showing a state in which the film is heat sealed to the flange portion of the tray and the film is melted.
FIG. 8 is a schematic cross-sectional view of the package of the present invention on which an object to be weighed is placed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Packaging apparatus, 2 ... Tray holding member, 3 ... Heat roller, 5 ... Film supply mechanism, 6 ... Lift mechanism, 10 ... Wrap film, 11 ... Packaged object, 12 ... Tray, 51 ... Film supply roller, 52a , 52b ... conveying roller, 52c, 52d ... pressing roller, 53 ... film take-up roller, 54 ... belt, 63 ... moving part, 72 ... link mechanism, 73 ... pressing plate, 74 ... lever mechanism, 81 ... rotating shaft, 82 …motor

Claims (3)

A package comprising a tray made of polypropylene resin or polyethylene resin or a tray laminated with these resins on the surface, and a wrap film heat-sealed on the edge portion of the upper surface of the tray, the wrap film having two or more layers In this structure, the layer to be heat-sealed with the tray is composed of a linear low density polyethylene resin (A) produced with a metallocene catalyst, and the temperature was measured with a differential scanning calorimeter at a scanning rate of 10 ° C./min. A layer made of a resin (B) having a crystal melting peak temperature 10 to 70 ° C. higher than that of the resin (A) is laminated on the resin (A) layer , and the density of the resin (A) is 0.86 to 0.93 g / in the range of cm ^3, and the thickness of the resin (a) layer is 0.5μm or more and der than the total thickness of the resin layer (a) occupied 10μm among the wrap film Turkey Package according to claim. Package of claim 1, wherein said resin to be laminated to a linear low-density polyethylene resin (A) (B) contains a polypropylene 30% by weight or more in said wrap film. The package according to claim 2, wherein the peel strength of the heat seal surface between the tray and the wrap film is 300 g / 15 mm width or more.

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