JPH106428A - Material for vacuum-absorbing lid and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a plastic molded container accompanied by the lowering of the internal pressure of a package caused by the liquification of steam present in the head space of the container or the lowering of temp. generated when the container is filled with a hot liquid heated to the vicinity of its b.p. and held to a saturated steam pressure state. SOLUTION: A laminate consisting of a base material film having vent holes 4, an adhesion obstructing layer 13 or a weak adhesive layer and a heat sealable thermoplastic resin layer 20 is used as the lid material of a molded container and the adhesion obstructing layer 13 or the weak adhesive layer is provided other than the heat seal part of the lid material and the molded container to constitute the vacuum-absorbing lid material for the molded container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lid material for sealing a molded container after filling the contents thereof. Belongs to a package that can absorb

[0002]

The lid material of the conventional molded container is composed of a laminated film of a biaxially stretched film provided with a picture layer serving as a base film, and a heat sealant layer having easy opening properties. Was. However, in such a configuration, when sealing is performed after filling the contents, there is a problem that the inside of the package is depressurized and the molded container is deformed depending on the contents and a method of filling and sealing the contents. . For example, if the package is cooled after filling and sealing with a liquid having a saturated vapor pressure heated to near the boiling point, the internal pressure of the package decreases due to the liquefaction of the vapor present in the head space of the package and the temperature difference, There is a problem that the molded container is deformed.

[0003] Further, after the contents of powder and granules, hot rice and the like are filled in an aerated state, the contents are packed and sealed together with an oxygen scavenger so that the contents are not oxidized by residual oxygen. However, there has been a problem that the internal pressure decreases as oxygen is absorbed by the oxygen scavenger, and the molded container is deformed as the pressure is reduced. The present invention
It is an object of the present invention to provide a lid material capable of absorbing the reduced pressure of a package and preventing deformation of the container even when the pressure is reduced after filling and sealing the molded container.

[0004]

In order to achieve the above-mentioned object, the present invention provides a base film provided with a vent hole, comprising an adhesion inhibiting layer or a weak adhesion layer, and a heat-sealable thermoplastic resin layer. A laminated body used as a lid material of a molding container, wherein the adhesion inhibiting layer or the weak adhesion layer is a reduced-pressure absorption lid material provided in a portion other than a heat sealing portion between the lid material and the molding container. In a second aspect, the heat-sealable thermoplastic resin layer of the lid member is a composite film including an ethylene-vinyl alcohol copolymer layer (hereinafter referred to as an EVOH layer). It is an absorbing lid material.
A third aspect of the present invention is a method for using the reduced-pressure absorbing lid material used for a package containing a deoxidizer together with contents.

[0005]

2. Description of the Related Art Hitherto, a lid material of a molded container has been constituted by a laminate of a base film and a heat sealant layer having strong adhesion. In the case of a liquid that requires complete degassing and sealing in the container, a full filling seal (the lid material is heat-sealed in a state where the liquid overflows).
Was done in However, when high nutrients such as fruit juice or sake remain in the seal portion, there is a problem that the contents of the package are spoiled or deteriorated by the trigger.

When full filling sealing cannot be performed, the contents of the heated liquid are filled with a space provided in the upper part of the molding container to keep the heat seal portion clean, and the lid material is heat sealed (hereinafter, referred to as "heat seal"). As described above, filling and sealing the liquid containing the saturated vapor by providing a space above the liquid and filling and sealing the liquid is referred to as "hot filling.") To form a degassed state. For example, when sake is hot-filled and cooled, the inside of the package is decompressed due to liquefaction of steam, and the depressurization cannot be absorbed only by extending the lid material, and the molded container is deformed. .

In such a case, a concave drop cover is provided to the extent that it comes into contact with the surface of the liquid, the vapor is driven out, the lid is sealed, and a slight decompression inside the package due to the liquefaction of the vapor reduces the drop lid. Has been performed to deform and absorb the concave portion provided in the central portion of the device. Since this drop lid uses a molded product, the supply of the lid material is a single-wafer method, and the stacking and conveyance when supplying are complicated, and the productivity is remarkably inferior as compared with the lid material of the winding supply method. There was a problem.

When the easily oxidized contents are enclosed in a package together with a deoxidizer in an aerated state, the inside of the package is reduced in pressure as the oxygen inside is absorbed, and the molded container is deformed. There was a problem.

[0009] By forming the base film of the lid material only from an unstretched film instead of a biaxially stretched film, it is possible to absorb the reduced pressure in the package to some extent by utilizing its flexibility and stretchability. . However, the unstretched film is inferior in strength to the biaxially stretched stretched film, so that it is torn at the time of opening, or printing at a regular pitch for providing a pattern layer has a large tension fluctuation, and a filling machine. There is a problem that it is difficult to synchronize the positions of the picture layer and the heat seal portion.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The base film provided with air holes according to the present invention mainly comprises a polyolefin resin such as polyethylene or polypropylene, polystyrene, polyvinyl chloride, polyvinyl alcohol, EVOH, polyamide, acrylate or methacrylate. Acrylic resin as a component, polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, acetyl di- or tri-cellulose fibrous derivatives, stretched or unstretched films made of polycarbonate, etc. or stretched films thereof Is subjected to aluminum evaporation. Also,
A laminate of paper, aluminum foil, and the above-mentioned thermoplastic resin film can also be used. The polyvinyl alcohol and EVOH films serving as the base film are not laminated as a so-called gas barrier film, but as a film for preventing adhesion of dust due to static electricity.
The aluminum foil and the aluminum vapor-deposited film utilize the decorative effect as the metallic luster. Particularly, a biaxially stretched film of polyethylene terephthalate, polypropylene or nylon 6 having excellent printability and post-processing suitability having a thickness of 6 to 50 μm is excellent in processability such as printability and is preferable as a base plastic film.

The adhesion-inhibiting layer can be selected from those having a strong adhesion to the base film and no affinity for the adhesive. Depending on the relationship with the base film, known resins such as fluorine-based resin, various waxes, vaseline, silicone resin and other peelable materials, such as acrylic resin, polyester-based resin, polyamide comprising dimer acid and diamine, A varnish prepared in addition to a vinyl chloride / vinyl acetate copolymer or a cellulose derivative can be provided by printing on a portion corresponding to a peeling space described later.

The adhesion-inhibiting layer can be formed by gravure printing, flexographic printing or silk screen printing, and the coating amount is only required to be able to form a certain film.
1 to 3 g / solid (the amount of coating is hereinafter described as solid)
m ² , even if there is some printing unevenness, it is sufficient that the adhesion balance (peelability) with the adhesive layer used when laminating the base film and the heat-sealable thermoplastic resin layer is maintained.

The weak adhesive layer is selected from materials having a low adhesive strength to the base film or a material which reduces the adhesive strength to the base film in a heat treatment step for providing a heat-sealable thermoplastic resin layer. be able to. There are varnishes of nitrified cotton (including a plasticizer) for polyester film and biaxially oriented polypropylene film, vinyl chloride / vinyl acetate copolymer, polyvinyl butyral, and chloride rubber. In addition, when a weak adhesive layer is provided, a certain amount of adhesive strength is exhibited, but a method of forming a heat-sealable thermoplastic resin layer, for example, a low-density polyethylene or the like is provided by melt extrusion coating, or a heat-sealable thermoplastic A film that becomes a resin layer, the adhesive strength is reduced by heat when sandwich lamination with molten polyethylene, a material with poor so-called heat resistance, for example, a vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, dimer acid and diamine And the like. And it can be formed by sheet printing or rotary printing by gravure printing, flexographic printing, silk screen printing or the like, which can be printed on a plastic film in the same manner as the adhesion inhibiting layer.

The adhesion-inhibiting layer or the weak-adhesion layer does not necessarily need to be printed with a colorless varnish, and can be colored with ordinary dyes or pigments if there is no problem in design, so that the desired position can be obtained. It has the advantage of being easy to print. Further, it is not necessary to clearly separate the adhesion-inhibiting layer and the weak-adhesion layer. Even if it is interfacial peeling, both functions may be mixed.

The heat-sealable thermoplastic resin layer may be either a layer showing a strong heat-sealing property by heat-sealing with a molding container or a layer showing an easy peeling property.
Further, even those that adhere with adhesive force can be used. For example, low density, medium density or high density polyethylene, linear polyethylene, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic ester copolymer, ionomer, EVOH, polyester, polyamide, wire Polyester, polyisobutylene, blends of these, and multilayer composite films. Then, the film can be formed by using a normal circular die or a T die. The thickness is preferably 15 to 60 μm, and it goes without saying that the thickness can be slightly increased or decreased depending on the material and application.

The heat-sealable thermoplastic resin layer is formed by dry laminating the formed film with a polyester-isocyanate-based adhesive or a polyether isocyanate-based adhesive, or by providing a primer layer with a low-density polyethylene or the like. It can be formed by sandwich lamination using an adhesive resin layer. Further, it can be formed by melt extrusion coating or co-extrusion coating using the above materials.

In order to form the EVOH described in the second invention into a heat-sealable thermoplastic resin layer, the base film provided with the adhesion inhibiting layer and the single-layer EVOH film may be dry-laminated, Can be combined by sandwich lamination. Further, a heat-sealable resin is laminated to form a reduced-pressure absorbing lid material.
In addition, as shown in FIG. 3, a preferred method of forming the EVOH into a heat-sealable thermoplastic resin layer is a polyethylene layer (hereinafter referred to as a PE layer) 17 an EVOH layer 30.
It is a co-extruded multilayer film, such as the EVOH-containing composite film 21 composed of the PE layer 17. Then, the base film 11 provided with the adhesion inhibiting layer 13 and, if necessary, a layer having a desired heat sealing function are laminated on the other side to form a reduced-pressure absorbing lid material. Further, the co-extruded multilayer film containing EVOH is thinner (3 to 20 μm) than when an expensive EVOH layer is formed as a single layer (thickness of 10 μm or more).
There are advantages that can be done. Then, the PE layer 17 and the EVOH layer 3
A layer having an adhesive property to both resins may be interposed between the two layers.

The method for forming the air holes provided in the base film is not particularly limited, and a commonly used method can be used. For example, the surface can be continuously rotated and processed by a roll having a fine needle-like structure on the surface, or can be partially provided at a desired position by a stamp. In addition, it can be processed by a laser or the like. In any case, it is difficult to recognize the existence of the pores from the surface, and the air permeability is 20%.
0 to 5000 cc / min is preferable. If it is less than 200 cc, it is not possible to follow the reduced pressure and the molded container may be deformed.

As shown in FIG. 1, the pressure-reducing absorbing lid member is provided with an adhesion inhibiting layer 13 by gravure printing on a portion of the base film 11 excluding the heat-sealed portion, and further forms fine air holes 4 on the entire surface. Then, the lid member 1 having the deformed portion 2 in which the thermoplastic resin layer 20 that can be heat-sealed through the adhesive layer 12 can be formed. Then, the package, which is filled with the contents at a temperature close to the saturated vapor pressure in the molding container 5 and heat-sealed around the container, is depressurized inside the package as it is cooled. As shown, the deformed portion 2 peels off on the surface of the adhesion inhibiting layer 13, and the plastically deformed portion 2 forms a peeling space 6 to absorb the reduced pressure of the package. Therefore, the base film 11 and the molded container 5 can maintain the state at the time of filling without being deformed.

Although not shown, the base film 11
And a weak adhesive layer 14 provided by gravure printing in a portion except for the heat seal portion, and further, fine air holes 4 are formed on the entire surface, and a thermoplastic resin layer 20 that can be heat sealed through the adhesive layer 12 is formed. The lid member 1 having the laminated deformed portions 2 can be configured. Then, the lid 1 is filled with the contents at a temperature close to the saturated vapor pressure in the molding container 5, and the heat sealed around the molding container 5 is cooled. However, as shown in FIG. 4, the deformed portion 2 is peeled between the base film 11 and the weak adhesive layer 14, and the plastic deformed portion 2 forms the peeling space 6 to reduce the pressure of the package. Absorb. Therefore, the base film 11 and the molding container 5 can maintain the state at the time of filling without deformation.

[0021]

Hereinafter, the present invention will be described in more detail with reference to examples. Example 1 As shown in FIG. 1, a circular coating amount of 80 mm in diameter was applied to one side of a 12 μm-thick polyethylene terephthalate film 11 by gravure printing at a rate of 3 g / g.
The m ² adhesion inhibition layer 13 was printed using a varnish using polyamide as a binder. Further, from the other side of the film 11, 3 needle-like projections having a diameter of 0.5 mm / cm ²
Perforated with rollers. The air permeability of the film is 2
It was 500 cc / min. Further, the film 11
Polyester-isocyanate adhesive 1 as a thermoplastic resin layer 20 capable of heat-sealing an unstretched polypropylene film having a thickness of 50 μm on the side having the adhesion inhibition layer 13
2 were laminated by dry lamination using 4 g / m ^2, thereby producing a lid 1 of Example 1 shown in FIG.

(Example 2) A coating amount of a circular shape having a diameter of 80 mm was 2 g / m 2 by gravure printing on one side of a polyethylene terephthalate film 11 having a thickness of 12 μm.
^{The second} weak adhesive layer 14 was printed with a varnish using a vinyl chloride / vinyl acetate copolymer as a binder. Further, the unstretched polypropylene film 20 having a thickness of 50 μm was laminated by dry lamination from the other side of the film 11 in the same manner as in Example 1 using 3 g / m ² of the polyester-isocyanate adhesive 12. Lid 1 of Example 2 was made.

Comparative Example 1 A comparative example in which polyethylene terephthalate 11 and an unstretched polypropylene film having a thickness of 50 μm were laminated in the same configuration as in Example 1 except that the adhesion inhibiting layer or the weak adhesive layer and the vent were not provided. Thus, a film lid material 1A was prepared.

In a polypropylene injection-molded cup-shaped container 5 having an outer diameter of 98 mm and an inner diameter of 88 mm, that is, a flange width of 5 mm and a height of 80 mm, sake heated at 80 ° C. as a content 10 at a position 10 mm below the flange. Until the injection. Then, the lid member 1 of the first and second embodiments
As for (2), the adhesion-inhibiting layer or the weakly-adhesive layer was prevented from touching the heat-sealed portion, and the lid 1A of Comparative Example 1 was sealed with a ring sealer having a width of 2 mm and cooled to room temperature.

At first, the pressure in the head space of the cup was close to the atmospheric pressure due to the presence of high-temperature steam and alcohol vapor. became. As a result, the lid materials of Example 1 and Example 2 are shown in FIGS. 2 (peeling between the adhesion inhibiting layer 13 and the adhesive layer 12) and FIG. 4 (between the weak adhesive layer 14 and the base film 11). The deformed portion 2 extends as shown in FIG.
0 indicates the state in which the peeling space 6 was formed, and the cup shape as a whole was kept at the time of filling. However,
In the case of the comparative example, as shown in FIG.
In addition to being deformed so as to come into contact with 0, the side surface of the cup was curved inward and exhibited poor appearance.

Example 3 One side of a 25 μm-thick polyethylene terephthalate film 11 was gravure-printed at 95 mm × 125 mm and the corner R was 10 m.
As the adhesion inhibiting layer 13 having the shape of m, a varnish obtained by adding 0.5% of silicone to a binder of polyamide: nitrified cotton = 1: 1 was printed so that the coating amount became 3 g / m ² , and the center was printed. Two vent holes 4 having a diameter of 0.3 mm were provided in the portion. A polyester / isocyanate-based primer 16 was provided on the side of the adhesion inhibiting layer 13
The low-density polyethylene of 5 μm is used as the adhesive resin layer 15 as “PE layer 17 / EVOH layer 30 / PE layer 17 total thickness 3”.
Sandwich lamination with EVOH-containing composite film 21 "by co-extrusion film formation of 0 μm, and
A low-pressure absorption lid material 1 shown in FIG. 3 was prepared by sandwich lamination of 5 μm low-density polyethylene as an adhesive resin layer 15 and “a 30 μm-thick easy-opening layer 18 composed of linear polyethylene and polypropylene”.

Polypropylene layer 100 μm / EVOH3
A multi-layer sheet having a thickness of 0 μm / 200 μm of a polypropylene layer was formed by pressure-air / vacuum forming a tray-shaped forming container 51 having a flange inner size of 100 mm × 130 mm, a flange width of 8 mm, and a height of 25 mm. Then, fill 200 g of cooked rice at about 90 ° C.
Example 3 was prepared by introducing Ageless (oxygen absorber, trade name of Mitsubishi Gas Chemical Co., Ltd.) having an oxygen absorption capacity of 0 cc.
The easy-opening layer 18 of the reduced-pressure absorbing lid material, the polypropylene layer of the lid material of Comparative Example 1, and the flange of the molding container 51 were heat-sealed with a solid seal, respectively.

The shape of the tray after leaving the above-mentioned package at room temperature for 48 hours is as follows:
As shown in FIG. 7, by forming the peeling space 6, the original shape of the molded container was maintained, and the cooked rice was maintained in a loosened state immediately after filling. On the other hand, in the case of using the lid material of Comparative Example 1, as shown in FIG. 8, inside the package, the flange of the tray is bent inward due to the decompression, and only the appearance defect deformed like 51A is exhibited. There was no compressed rice.

[0029]

According to the present invention, a lid material provided with an adhesion-inhibiting layer or a weakly-adhesive layer between a base film provided with a vent and a heat-sealable thermoplastic resin layer is used for a sealed package using a molded container. When the inside is in a decompressed state, the thermoplastic resin layer is peeled off at the portion of the adhesion inhibiting layer or the weakly adhesive layer, forming a peeling space portion and elongating and deforming, so that the reduced pressure of the package can be absorbed. it can. Therefore, even when the molded container is hot-filled, the molded container is not deformed after cooling, and can be applied to a lid material of the molded container such as sake or fruit juice. Further, even when hot-filled in an aerated state like cooked rice and maintained in a reduced pressure state using an oxygen scavenger, an effect of providing a package in which a molded container is not deformed can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a cross section of a reduced-pressure absorbing lid member.

FIG. 2 is a schematic cross-sectional view showing a state where the pressure-reducing absorbing lid member is depressurized.

FIG. 3 is a schematic diagram showing a cross-sectional configuration of a reduced-pressure absorbing lid member including a barrier layer in a heat-sealable thermoplastic resin layer.

FIG. 4 is a schematic cross-sectional view showing a decompressed state of a reduced-pressure absorbing lid member having another configuration.

FIG. 5 is a schematic cross-sectional view showing a decompressed state of a package using a reduced-pressure absorbing lid material.

FIG. 6 is a schematic sectional view showing a decompressed state of a package using a normal lid material.

FIG. 7 is a schematic cross-sectional view showing a decompressed state of a package of another shape using a decompression lid.

FIG. 8 is a schematic cross-sectional view showing a decompressed state of a package having another shape using a normal lid member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1A Lid material 2 Deformation part 4 Vent hole 5 51 Molding container 5A 51A Deformed molding container 6 Peeling space 10 Contents 11 Base film 12 Adhesive layer 13 Adhesion inhibition layer 14 Weak adhesion layer 15 Adhesive resin layer 16 Primer Layer 17 PE layer 18 Easy-open layer 20 Heat-sealable thermoplastic resin layer 21 Composite film containing EVOH 30 EVOH layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B65D 81/26 B65D 1/00 B

Claims (3)

[Claims] 1. A laminate for use as a lid of a molding container, comprising a substrate film provided with a vent, comprising an adhesion-inhibiting layer or a weakly-adhesive layer, and a heat-sealable thermoplastic resin layer. A reduced-pressure absorption lid material, wherein an inhibition layer or a weakly adhesive layer is provided in a portion other than the heat sealing portion between the lid material and the molding container. 2. The reduced-pressure absorbing lid for a molded container according to claim 1, wherein the heat-sealable thermoplastic resin layer of the lid member is a composite film including an ethylene / vinyl alcohol copolymer layer. Wood. 3. The method according to claim 1, wherein the lid is used for a package containing an oxygen scavenger together with the contents.