WO2011148912A1

WO2011148912A1 - Multilayer sheet, thermally molded container, and easy-open packaging material

Info

Publication number: WO2011148912A1
Application number: PCT/JP2011/061794
Authority: WO
Inventors: 俊也佐藤
Original assignee: 出光ユニテック株式会社
Priority date: 2010-05-28
Filing date: 2011-05-24
Publication date: 2011-12-01
Also published as: KR20130080009A; JP2011245777A; TW201202033A; CN102905897A; KR101848944B1; JP5523933B2; CN102905897B

Abstract

A multilayer sheet (20) that constitutes a thermally molded container for an easy-open packaging material has a surface layer (27) to which a lid material is to be molten and adhered, wherein the surface layer (27) comprises 30 to 70 mass% inclusive of a polypropylene resin, 10 to 30 mass% inclusive of a propylene-ethylene random copolymer having a melting point of 130°C or lower, and 20 to 40 mass% inclusive of a low-density polyethylene resin having a melting point of 120°C or higher. The multilayer sheet (20) also has a lowermost surface layer (26) which is arranged adjacent to the surface layer (27), wherein the lowermost surface layer (26) contains a polypropylene resin having an isotactic pentad fraction of 93 mol% or more as the main component.

Description

Multilayer sheet, thermoformed container, and easy-open packaging

The present invention relates to a multilayer sheet, a thermoformed container, and an easily openable package including the thermoformed container.

2. Description of the Related Art In recent years, with increasing awareness of food safety, easily openable containers and lid materials that can enhance the hermeticity of contents and take out the contents, and packages including these containers and lid materials have been proposed. (See Patent Documents 1 to 5).
Patent Document 1 describes a layer A composed of 50 to 95 wt% of a polyolefin resin, 50 to 5 wt% of an ethylene / acrylic acid ester / maleic anhydride copolymer resin, and a layer B composed of a polypropylene resin. The structure using the multilayer sheet | seat laminated | stacked is taken. The thickness dimension of the A layer is 5 to 500 μm.
The structure described in Patent Document 2 employs a configuration using a film having a heat-sealing layer made of a low-density polyethylene composition of 99 to 55% by weight of low-density polyethylene and 1 to 45% by weight of a propylene polymer. Yes.
The one described in Patent Document 3 is a cover made of an olefin resin in a container made of a composite sheet having a mixed resin film of an olefin resin and a styrene resin as a first layer and a styrene resin sheet as a second layer. The structure which fuse | fuses is taken.
Patent Document 4 describes that 50 to 83% by mass of polypropylene, 10 to 35% by weight of high density polyethylene having a density of 0.95 g / cm ³ or more and a melt flow rate of 10 to 100 g / 10 min, Using a composition containing 5 to 15% by weight of low-density polyethylene and 2 to 10% by weight of an ethylene / α-olefin copolymer having a density of 0.90 g / cm ³ or less, a skin for the sealing surface of the container The structure which forms a layer is taken.
The material described in Patent Document 5 is a thermoplastic comprising a polypropylene having a melting point of 128 to 140 ° C. and a melt flow rate of 2.6 to 3.2 g / 10 min, and an olefin-based thermoplastic elastomer or a styrene-based thermoplastic elastomer. The structure which made the polymer composition of the elastomer the inner wall surface of the container is taken.

JP 2003-231226 A JP 2002-241716 A JP-A-57-107812 JP 2005-271972 A JP 2006-15999 A

By the way, the sealing strength between the container provided with the sealing layer and the lid member is easily affected by the sealing conditions, and the strength tends to vary.
And in the above-mentioned conventional packaging body, when a resin having a low melting point is used as the resin of the surface layer that is agglomerated and peeled, the resin is applied to the hot plate when continuously produced using a direct hot plate heating type molding machine. There is a risk that it may become stuck and production cannot be continued. In addition, if the raw materials used for the lower and lower layers are not properly selected, the seal plate tends to become excessively entrapped during heat sealing, the stability of the sealing strength will be lost, and the conditions during heat sealing must be set narrowly. is there.
In view of such a point, an object of the present invention is to provide a multilayer sheet, a thermoformed container, and an easy-open packaging body that can be easily molded and have stable sealing performance.

The multilayer sheet according to the present invention is a multilayer sheet formed by laminating at least two layers of a surface layer and a surface lower layer provided adjacent to the surface layer, and the surface layer is made of polypropylene. 30% to 70% by mass of a resin, 10% to 30% by mass of a propylene-ethylene random copolymer having a melting point of 130 ° C. or less, and 20% to 40% of a low density polyethylene resin having a melting point of 120 ° C. or more. The upper and lower surface layers are mainly composed of a polypropylene-based resin having an isotactic pentad fraction of 93 mol% or more.

And in this invention, it is preferable that the said surface lower layer contains 80 mass% or more of polypropylenes whose isotactic pentad fraction is 93 mol% or more.
Furthermore, in the present invention, when the content of polypropylene having an isotactic pentad fraction of 93 mol% or more is less than 80% by mass, the front and lower layers contain talc in an amount of 0.5% by mass to 5% by mass. It is preferable to do.
In the present invention, the surface layer preferably has a thickness dimension of 10 μm to 150 μm.

The thermoformed container according to the present invention is a thermoformed container having an opening obtained by thermoforming the multilayer sheet according to the present invention, and extends outward at the periphery of the opening. A flange portion is formed, and the surface layer is formed on the inner surface side of the thermoformed container.

An easy-open packaging body according to the present invention includes the thermoformed container according to the present invention, and a lid member that is fused to a flange portion of the thermoformed container and closes the opening. .
And in this invention, the said cover material has a sealant layer in the surface fuse | fused to the said thermoforming container, and the said surface layer, the said lower layer, and the said cover material are the opening part side vicinity of the said flange part. It is preferable that a resin reservoir is formed by the sealant layer.

According to the present invention, the surface layer having the above-described composition can prevent the resin from adhering to the heating plate of the direct heating molding machine, for example, when the container is continuously molded, and can easily set the molding conditions widely. Can be molded. Furthermore, since the above-described composition is used as the upper and lower layers laminated adjacent to the surface layer, for example, when the lid material is fused to the container, it is possible to prevent inconvenience such as excessive penetration of the jig to be fused, and stable. It can be manufactured in a fused state, can prevent the seal strength from varying, and can provide stable sealing characteristics.

It is a perspective view which shows schematic structure sealed with the cover material in the easy-open packaging body which concerns on one Embodiment of this invention. It is a perspective view which shows the state which opened the cover material in the easy-open packaging body of this embodiment. It is a fragmentary sectional view of the opening start part in the easy-open packaging body of this embodiment. It is sectional drawing which shows the multilayer sheet which forms the thermoforming container in the easy-open packaging body of this embodiment. It is a schematic diagram which shows the melt | fusion process of the cover material in the case of manufacturing the easy-open packaging body in this embodiment. It is the fragmentary sectional view showing the state of the 1st annular seal board at the time of fusion in this embodiment, and a flange part. It is the elements on larger scale of the 1st annular seal board in this embodiment. It is sectional drawing which showed the state by which the easy-open packaging body of this embodiment was initially opened. It is sectional drawing which showed the state by which the easy-open packaging body of this embodiment was completely opened. It is sectional drawing which showed the state by which the easy-open packaging body which concerns on other embodiment of this invention was initially opened. It is sectional drawing which showed the state by which the easy-open packaging body of other embodiment was completely opened.

[Structure of easy-open packaging]
Hereinafter, the easy-open packaging body of one Embodiment of this invention is demonstrated with reference to drawings.
FIG. 1 is a perspective view showing a schematic configuration sealed with a lid in the easy-open packaging body of the present embodiment. FIG. 2 is a perspective view showing a state in which the lid member in the easy-open packaging body of the present embodiment is opened. FIG. 3 is a partial cross-sectional view of an opening start portion in the easy-open packaging body of the present embodiment. FIG. 4 is a cross-sectional view showing a multilayer sheet forming a thermoformed container in the easy-open packaging body of the present embodiment.

As shown in FIGS. 1 and 2, the easy-open packaging body 1 packages various articles such as foods, medicines, cosmetics, sundries, etc., regardless of the form of liquid or solid.
The easy-open packaging body 1 includes a thermoformed container 2 and a lid 3.

(Configuration of thermoformed container)
The thermoformed container 2 has an opening 21 on the upper surface and a storage portion 23 that forms a storage space 22 for storing an article (not shown) inside, and is formed in a substantially rectangular tray shape. On the periphery of the opening 21 of the storage portion 23, a series of flange portions 24 extending outwardly in a bowl shape are provided.
As shown in FIG. 3, the thermoformed container 2 includes a base material layer 25, a surface lower layer 26 laminated adjacent to the base material layer 25, and a cohesive fracture property laminated adjacent to the surface lower layer 26. It is a laminate having a surface layer 27.
The thermoforming container 2 is obtained by heat-molding the multilayer sheet 20 with a molding machine such as a direct hot plate heating molding machine in a state where the surface layer 27 faces the inner surface side of the storage unit 23. In addition, as a shaping | molding method, not only a direct hot plate heating system but various shaping | molding methods are applicable.

Here, as shown in FIG. 4, the multilayer sheet 20 has a laminated structure in which a base material layer 25, a surface lower layer 26, and a surface layer 27 are laminated.
The base material layer 25 has a structure in which a first base material layer 25A, a first adhesive layer 25B, a gas barrier layer 25C, a second adhesive layer 25D, and a second base material layer 25E are sequentially laminated.
For example, a polypropylene resin, a polyethylene resin, a polyamide resin, a polyethylene terephthalate resin, or the like can be used for the first base material layer 25A and the second base material layer 25E, but is not limited thereto. The thickness dimensions of the first base material layer 25A and the second base material layer 25E are 100 μm or more and 2000 μm or less, and preferably 200 μm or more and 1000 μm or less.
For example, an unsaturated carboxylic acid or a derivative-modified polyolefin resin thereof can be used for the first adhesive layer 25B and the second adhesive layer 25D, but a polyvinylidene chloride resin may be used.
As the gas barrier layer 25C, it is preferable to use materials such as polyamide resin, polyethylene terephthalate resin, ethylene-vinyl alcohol resin, and polyvinylidene chloride. Among them, ethylene-vinyl alcohol resin is preferably used.
The base material layer 25 may further contain an additive such as a dispersant, a pigment, or a dye.
Examples of the dispersant include glycerin fatty acid ester monoglyceride, sorbitan fatty acid ester, and polyglycerin fatty acid ester. And when adding a dispersing agent, content of a dispersing agent is 1 to 8 mass%, Preferably they are 2 to 5 mass%.

The surface lower layer 26 contains a polypropylene resin having an isotactic pentad fraction of 93 mol% or more, preferably 97 mol% or more as a main component. The surface lower layer 26 may contain various polyolefin-based resins, polystyrene-based resins, polyester-based resins, mixtures thereof, and the like in addition to the polypropylene-based resins. As the polypropylene resin, homopolypropylene, random polypropylene or the like is used alone or in appropriate combination.
In the lower layer 26, the content of the polypropylene resin is 60% by mass or more and 90% by mass or less, preferably 65% by mass or more and 85% by mass or less, and more preferably 80% by mass or more and 85% by mass or less. Here, if the content of the polypropylene-based resin is less than 60% by mass, there is a risk that an excessive bite is likely to occur during sealing. On the other hand, when the content of the polypropylene-based resin is more than 90% by mass, there is a possibility that the thermoforming container 2 is liable to be cracked.

Further, the front lower layer 26 preferably contains 80% by mass or more of polypropylene having an isotactic pentad fraction of 93 mol% or more. Here, when the amount of the polypropylene is less than 80% by mass, there is a possibility that an excessive bite is likely to occur at the time of sealing.
Further, when the polypropylene having an isotactic pentad fraction of 93 mol% or more is contained in the lower surface layer 26 in an amount of less than 80 mass%, particularly 65 mass% or more and less than 80 mass%, talc is contained in an amount of 0.5 mass% or more and 5 mass% or less. It is preferable to contain it below. Here, if the talc is less than 0.5% by mass, the biting stability at the time of sealing may be deteriorated. On the other hand, if the talc content is more than 5% by mass, it is necessary to increase the heating temperature at the time of thermoforming, and there is a possibility of adhering to the hot plate of the molding machine.
And the surface lower layer 26 may contain additives, such as a dispersing agent, a pigment, or a dye, similarly to the base material layer 25.

In addition, when the isotactic pentad fraction of the polypropylene resin is smaller than 93 mol%, the front lower layer 26 is set to 93 mol% or more because excessive biting tends to occur during sealing.
Here, the measurement of the isotactic pentad fraction used as an index of stereoregularity is, for example, A. Examples thereof include a method based on a ¹³ C-NMR method (Macromolecules, 6925, 1973) disclosed by Zambelli. Specifically, first, 220 mg of i-PP sample was collected in a 10 mm diameter NMR sample tube, and 2.5 ml of a 1,2,4-trichlorobenzene / heavy benzene mixed solution (90/10 vol%) was added, and uniform at 140 ° C. After the mixture was dissolved, ¹³ C-NMR spectrum was measured using JNM-EX400 (trade name: manufactured by JEOL Ltd.). ^The conditions for ¹³ C-NMR spectrum measurement are shown below.
・ Pulse width: 7.5μs / 45 degrees ・ Observation frequency range: 25,000Hz
-Pulse repetition time: 4 seconds-Measurement temperature: 130 ° C
Number of integrations: 10,000 times And, the isotactic pentad fraction has 9 types of bond patterns of five propylene molecules (“mmmm”, “mmmr”, “rmmr”, “mmrr”, “rmrr + mrmm”, “ rmrm "," rrrr "," mrrrr "," mrrrm ") corresponding to each of the nine peaks observed as ¹³ C-NMR spectra, the peak area corresponding to" mmmm " Defined as relative ratio. Specifically, it was calculated by the following relational expression (1). Here, when there was an overlap between the two peaks, a perpendicular line was drawn vertically from the valley of the two peaks to the base line to divide both peaks (vertical division method).
{Relation (1)}
Isotactic pentad fraction (mol%)
= {A (mmmm) / A (total)} × 100 (1)
Here, A (mmmm) is the area of the mmmm peak, and A (total) means the sum of the nine peak areas.
In addition, when there is an overlap between two peaks, in addition to the above vertical division method, there is also known a method of performing waveform separation using each peak as an aggregate of Lorentz-type peaks. Analysis software (ALICE 2 from JEOL Ltd.) is also known. ) May be used.

The surface layer 27 is made of a resin composition containing a polypropylene resin, a propylene-ethylene random copolymer having a melting point of 130 ° C. or lower, and a low density polyethylene resin having a melting point of 120 ° C. or higher.
As the polypropylene resin, homopolypropylene, random polypropylene, block polypropylene and the like are used alone or in appropriate combination.
As the polypropylene-based resin, those having a melt flow rate of 0.3 g / 10 min or more and 0.8 g / 10 min or less, preferably 0.4 g / 10 min or more and 0.7 g / 10 min or less are used. If the melt flow rate is smaller than 0.3 g / 10 min, the surface layer 27 may not be spread uniformly. On the other hand, if the melt flow rate is greater than 0.8 g / 10 min, the dispersibility may be impaired.
Moreover, content of a polypropylene resin is 30 to 70 mass%, Preferably it is 40 to 50 mass%. When the content of the polypropylene resin is less than 30% by mass, the adhesion with the lid member 3 is weak, and the adhesion may be deteriorated or the heat resistance may be deteriorated. On the other hand, when the content of the polypropylene resin is more than 70% by mass, the adhesiveness becomes too strong, and the openability may be deteriorated.

The content of the propylene-ethylene random copolymer having a melting point of 130 ° C. or less is 10% by mass or more and 30% by mass or less, preferably 15% by mass or more and 25% by mass or less.
As the propylene-ethylene random copolymer, one having a melt flow rate of 0.5 g / 10 min to 3 g / 10 min, preferably 1.5 g / 10 min to 2.5 g / 10 min is used. If the melt flow rate is less than 0.5 g / 10 min, the surface layer 27 may be difficult to spread uniformly. On the other hand, when the melt flow rate is greater than 3 g / 10 min, the dispersibility may be impaired.
If the melting point of the propylene-ethylene random copolymer is higher than 130 ° C., the sealing property with the lid 3 may be weakened. Therefore, the melting point of the propylene-ethylene random copolymer is 130 ° C. or lower, preferably 120 ° C. or higher and 130 ° C. or lower.
Further, when the content of the propylene-ethylene random copolymer is less than 10% by mass, the sealing property with the lid member 3 may be weakened. On the other hand, if the content of the propylene-ethylene random copolymer is more than 30% by mass, the sealing property with the lid member 3 may be too strong.

The content of the low-density polyethylene resin having a melting point of 120 ° C. or higher is 20% by mass or more and 40% by mass or less, preferably 25% by mass or more and 35% by mass or less.
As the low density polyethylene-based resin, those having a melt flow rate of 3.5 g / 10 min or more and 6.5 g / 10 min or less, preferably 4 g / 10 min or more and 5 g / 10 min or less are used. If the melt flow rate is less than 3.5 g / 10 min, the dispersed state may be impaired. On the other hand, when the melt flow rate is larger than 6.5 g / 10 minutes, the dispersion state may be impaired.
If the low-density polyethylene resin has a melting point lower than 120 ° C., it may be attached to the heating plate by a direct heating type molding machine. For this reason, the melting point of the low-density polyethylene resin is 120 ° C. or higher, preferably 120 ° C. or higher and 130 ° C. or lower.
Moreover, when content of a low density polyethylene-type resin becomes less than 20 mass%, there exists a possibility that adhesiveness with the cover material 3 may become strong too much and unsealing property may deteriorate. On the other hand, when the content of the low density polyethylene resin is more than 40% by mass, the adhesiveness with the lid member 3 may be greatly changed.

Further, the surface layer 27 may further contain an additive such as a dispersant, a pigment, or a dye, as in the case of the base material layer 25 and the surface lower layer 26.
The surface layer 27 is preferably formed with a thickness of 10 μm to 150 μm, particularly 15 μm to 100 μm. If the thickness dimension of the surface layer 27 is thinner than 10 μm, it is difficult to control the thickness dimension, the productivity may be deteriorated, and the surface layer 27 may be rejected during fusion. On the other hand, if the thickness dimension of the surface layer 27 is thicker than 150 μm, the cohesive failure surface is not stable, and there is a possibility that an appearance defect may occur at the time of opening.

And the multilayer sheet 20 is shape | molded by the multilayer extrusion molding method which used T-die, for example.
Specifically, using an extruder corresponding to the base material layer 25, the surface lower layer 26 and the surface layer 27, the base material layer 25, the surface lower layer 26 and the surface layer 27 extruded from each extruder are used as a T die. Molded by joining and laminating with special blocks provided just before entering.

(Composition of lid material)
As shown in FIG. 3, the lid 3 includes an outer layer 31 that appears outside the easy-open packaging body 1, a sealant layer 32 that is fused to the surface layer 27 of the thermoformed container 2, and the outer layer 31 and the sealant layer. It is a laminated body having an intermediate layer 33 interposed between 32.
The sealant layer 32 of the lid member 3 to be fused with the surface layer 27 of the thermoforming container 2 is an unsealing mode in which the surface layer 27 of the thermoforming container 2 is agglomerated and peeled off (see FIG. 8). Specifically, as shown in FIGS. 1 and 2, the opening start portions 34 of the lid 3 provided at the four corners of the easy-open packaging body 1 are separated from the flange portions 24 of the thermoforming container 2 (see FIG. 1). By pulling in the direction indicated by the arrow 2 in FIG. 2, the surface layer 27 is agglomerated and peeled off, and the easy-open packaging body 1 is opened.

For the outer layer 31 of the lid member 3, for example, a polyethylene terephthalate (PET) film, a biaxially stretched nylon film (O—Ny), or the like can be used.
The intermediate layer 33 is preferably made of, for example, a polyamide resin, a polyethylene terephthalate resin, an ethylene-vinyl alcohol resin, or polyvinylidene chloride.
The sealant layer 32 is preferably made of, for example, polypropylene resin or polyethylene resin.

(Configuration of resin reservoir)
Then, as shown in FIG. 3, the easy-open packaging body 1 has a ring material as shown in FIGS. 1 and 2 in which a lid 3 is fused to a thermoformed container 2 formed from the multilayer sheet 20 described above. A seal portion 28 is formed. By fusing the surface layer 27 of the thermoformed container 2 and the sealant layer 32 of the lid member 3, the opening 21 of the thermoformed container 2 is sealed, and the storage space 22 of the easy-open packaging body 1 is sealed. .
Here, as shown in FIG. 3, the seal portion 28 includes a first annular seal portion 281 formed by the first annular seal disc 7 and a second annular seal portion 282 formed by the second annular seal disc 7a. Formed with.
As a result of the fusion of the lid member 3, as shown in FIG. 3, a bump-shaped resin reservoir portion is formed in the vicinity of the inner peripheral edge (position X in FIG. 3) of the annular first annular seal portion 281 on the flange portion 24. 6 is formed. The resin reservoir 6 is formed such that the surface lower layer 26, the surface layer 27 of the thermoforming container 2, and the sealant layer 32 of the lid 3 are pushed out to the opening edge side of the opening 21 of the thermoforming container 2.
Specifically, as shown in FIG. 3, the resin reservoir 6 includes the first resin reservoir 61 of the surface layer 27 of the thermoforming container 2, the second resin reservoir 62 of the front and lower layer 26, and the sealant layer of the lid member 3. 32 third resin reservoirs 63 are formed together.
The easy-open packaging body 1 in an unsealed form in which the surface layer 27 of the thermoformed container 2 is agglomerated and peeled is provided with such a resin reservoir portion 6 so that it has a high sealing property as a packaging container and is agglomerated and peeled. Easy-openability can be maintained in a good state by the opening form. Furthermore, in the easy-open packaging body 1, the lid 3 and the flange portion 24 of the thermoformed container 2 are easily cut by the resin reservoir 6. In addition, the easy-open packaging body 1 has improved sealing properties because the direction in which stress due to internal pressure is applied differs from the direction in which easy opening due to cohesive failure occurs. Specifically, the stress of the internal pressure is applied from the vicinity of the inner peripheral edge X of the first annular seal portion 281 to the concave portion of the base in the first resin reservoir 61 and the second resin reservoir 62 (position Y in FIG. 3). It is easy to act, it is difficult to open depending on the stress of the internal pressure, and the sealing performance is improved.

In the easy-open packaging body 1, the resin reservoir portion 6 is formed on the entire circumference in the vicinity of the inner peripheral edge X of the annular first annular seal portion 281 on the upper surface of the flange portion 24 of the thermoformed container 2. The outer peripheral edge of the annular first annular seal portion 281 in the opening start portion 34 of the thermoformed container 2 is flat or resin smaller than the resin reservoir 6 in the vicinity of the inner peripheral edge X of the first annular seal portion 281. Only a pool is formed.
For this reason, the portion other than the opening start portion 34 is substantially the same as the resin reservoir portion 6 in the vicinity of the inner peripheral edge X of the first annular seal portion 281 on the entire outer periphery of the annular first annular seal portion 281. You may form the resin reservoir part which a magnitude | size does not illustrate. By adopting this configuration, it is preferable in terms of being excellent in high sealing performance, easy opening, and prevention of opening of the lid member 3 from other than the opening start portion 34.

[Manufacturing method of easy-open packaging body]
Next, the manufacturing method of an easily openable package is demonstrated with reference to drawings.
FIG. 5 is a schematic view showing a lid material fusion process in the case of manufacturing the easy-open packaging body according to the present embodiment. FIG. 6 is a partial cross-sectional view showing a state of the first annular seal disc and the flange portion at the time of fusion in the present embodiment. FIG. 7 is a partially enlarged view of the first annular seal disc in the present embodiment.

In manufacturing the easy-open packaging body 1, in order to make the easy-open packaging body 1 in a sealed state by fusing the flange portion 24 and the lid material 3 of the thermoforming container 2, The lid member 3 is overlaid on the flange portion 24. Then, heat sealing is performed by pressing the heated first annular sealing disk 7 from the upper surface of the lid 3.
In order to form the knob-shaped resin reservoir 6 near the inner periphery X of the seal portion of the opening start portion 34 as described above, for example, the following method may be used.

As shown in FIG. 5, the heat seal between the flange portion 24 of the thermoformed container 2 and the lid material 3 is performed by superimposing the lid material 3 on the flange portion 24 of the thermoformed container 2 and heating the lid material 3 from above. The first annular sealing disc 7 in the state is pressed in the direction of the arrow in FIG. By this pressing, the surface layer 27 appearing on the flange portion 24 of the thermoforming container 2 and the sealant layer 32 of the lid member 3 are fused.
Here, as for the 1st cyclic | annular sealing board 7 used in order to manufacture the easy-open packaging body 1 of this embodiment, R process is given to the inner periphery with respect to the upper surface of the flange part 24, and an outer periphery is This is the first annular seal disc 7 having a shape that is adapted to come into contact with the lid member 3 with a delay from the tip end of the first annular seal disc 7 (tip 73 in FIG. 7). Specifically, the first annular seal disc 7 has an inclined surface portion 71 having an inclined cross section on the outer peripheral edge side and an inner peripheral edge side via the boundary A (also the tip 73 of the first annular seal disc 7). R is processed and a curved surface portion 72 having a curved cross section is continuously formed.

Among these, the inclined surface portion 71 formed on the outer peripheral edge side of the first annular seal disc 7 is formed from the inner peripheral edge toward the outer peripheral edge with respect to the surface of the flange portion 24 as shown in FIG. The angle (θ) is preferably set to 2 ° to 20 °, particularly 3 ° to 15 °. Note that the angle of the inclined surface portion 71 is appropriately set according to the width H of the first annular seal disc 7.
If the angle of the inclined surface portion 71 is smaller than 2 °, the resin reservoir portion 6 as shown in FIG. 3 is easily formed in the vicinity of the outer peripheral edge of the seal portion 28 even when pressed at the time of fusion. The resistance on the outside of the seal portion 28 at the time of opening increases, and it may be difficult to perform opening smoothly. On the other hand, when the angle of the inclined surface portion 71 exceeds 20 °, the periphery of the boundary A is gently pointed, and the lid member 3 may be cut at the time of fusing or opening, so that easy-openability is impaired. There is a risk of being.

In addition, it is preferable that the radius of curvature R is about 0.2Hmm or more and 0.5Hmm or less in the R processing applied to the curved surface portion 72 formed on the inner peripheral edge side of the first annular seal disc 7. The radius of curvature R of the curved surface portion 72 is appropriately set according to the width dimension H of the first annular seal disc 7 as shown by multiplying this numerical range.
If the radius of curvature R of the curved surface portion 72 is smaller than 0.2 Hmm, the periphery of the boundary A will be gently sharpened, and the lid 3 may be cut during fusion or opening. On the other hand, when the radius of curvature R exceeds 0.5 Hmm, the resin reservoir 6 is hardly formed in the vicinity of the inner peripheral edge X of the seal portion 28 of the flange portion 24 even when pressed at the time of fusion.

Here, with respect to the first annular seal disc 7, the inclined surface portion 71 and the curved surface portion 72 are such that the boundary A is closer to the inner side (close to the inner peripheral edge) than the cross-sectional width direction of the first annular seal disc 7. Preferably it is formed. If the boundary A is inside with respect to the cross-sectional width direction of the first annular seal disc 7, the curved surface portion 72 is provided on the inner peripheral side of the first annular seal disc 7, and the inclined surface portion 71 is provided on the outer peripheral side of the first annular seal disc 7. Combined with the formation, the tip 73 comes into contact with the lid 3 first from the outer peripheral edge side of the first annular seal disc 7 at the time of fusion. That is, it is ensured that the outer peripheral edge of the first annular seal disc 7 comes into contact with the lid member 3 with a delay from the tip 73. For this reason, the resin reservoir 6 is selectively formed on the inner side with respect to the opening 21 side on the inner peripheral edge side in contact with the tip.

Moreover, in this embodiment, it corresponds to parts other than the opening start part 34 of the thermoforming container 2, and is rounded to the entire circumference of the inner peripheral edge and the outer peripheral edge of the first annular seal disc 7 and has a curved cross section. A portion 72 is formed. And the site | part of the 1st cyclic | annular sealing board 7 corresponding to the opening start part 34 of the thermoforming container 2 is R-processed by the inner periphery, and the curved-surface part 72 with a curved cross section is formed. Thus, by using the first annular seal disc 7 having a shape in which the outer peripheral edge comes in contact with the lid member 3 later than the tip 73 of the first annular seal disc 7, high sealing performance, easy opening property, And it is preferable at the point which can manufacture the easy-open packaging body 1 which is excellent in the opening prevention property of the cover material 3 other than the opening start part 34. FIG.

The first annular seal disc 7 is formed by continuously forming the inclined surface portion 71 and the curved surface portion 72 in an annular manner so as to integrally form a circumferential seal portion 28 as shown in FIGS. 1 and 2. An annular sealing disc (seal ring) may be used. Further, the first annular seal disc 7 may be an annular seal disc (seal ring) in which the inclined surface portion 71 and the curved surface portion 72 are formed only for the portion corresponding to the opening start portion 34 of the easy-open packaging body 1. Good.

In order to fuse the flange portion 24 and the lid member 3 of the thermoformed container 2 using the first annular sealing disk 7 having the shape shown in FIGS. 6 and 7, first, as shown in FIG. A tip 73 corresponding to the boundary A between the inclined surface portion 71 and the curved surface portion 72 in the annular seal disc 7 is in contact with the lid member 3. Thereafter, the curved surface portion 72 formed on the inner peripheral edge side of the boundary A is directed toward the inner side of the lid member 3, and the inclined surface portion 71 formed on the outer peripheral edge side of the boundary A is directed toward the outer side of the lid member 3. Press.
Thereby, the resin component of the surface layer 27 of the thermoforming container 2 and the surface lower layer 26 adjacent to the surface layer 27 is extruded from the lower part of the boundary A to the inside of the thermoforming container 2, and the first in the flange portion 24. Bump-

like resin reservoirs

61 and 62 are formed in the vicinity of the position where the inner peripheral edge of the annular seal disc 7 is in contact, that is, in the vicinity of the inner peripheral edge X of the seal portion 28 of the thermoformed container 2. Further, the sealant layer 32 of the lid 3 also follows to form a resin reservoir 63, and in a state where these form the resin reservoir 6, the surface layer 27 appearing on the flange portion 24 of the thermoforming container 2, and the lid 3 sealant layers 32 are fused.

Here, as a fusing condition, the fusing temperature may be appropriately determined depending on the type of material to be fused, but may be about 160 ° C. or higher and 240 ° C. or lower.
Similarly, the fusion pressure may be about 10 kg / cm ² (100 to 500 kPa) or more and 50 kg / cm ² (100 to 500 kPa) or less.

In addition, there exists a possibility that a foreign substance may enter easily from the outer periphery side only by the fusion | fusion by the 1st annular seal disc | board 7. In order to prevent such a situation, the sealant layer 32 of the lid member 3 is fused to the surface layer 27 of the flange portion 24 while forming the above-mentioned knob-shaped resin reservoir portion 6 by the first annular seal disc 7. After that, the second annular seal disc 7a is used to press the outer peripheral side of the seal portion 28 so that the surface layer 27 of the thermoformed container 2 and the sealant layer 32 of the lid 3 are fused. Good.
If the sealing surface of the second annular sealing disk 7a is a smooth flat shape or an R shape, the positional relationship between the resin reservoir 6 and the second annular sealing disk 7a need not be considered.
However, when the sealing surface of the second annular sealing disk 7a is processed so that partial adhesion is possible, such as knurls, the unsealed appearance may be impaired due to the crushed resin reservoir 6 being crushed into irregularities. Therefore, it is preferable to prevent the second annular seal disc 7a from hitting the resin reservoir 6.

[How to open easy-open packaging]
Next, the opening method of the said easily openable package 1 is demonstrated with reference to drawings.
FIG. 8 is a cross-sectional view showing a state in which the easy-open packaging body of the present embodiment is initially opened. FIG. 9 is a cross-sectional view showing a state where the easy-open packaging body of the present embodiment is completely opened.
Here, the “initially opened state” refers to a state where the peeled and peeled surface does not reach the resin reservoir 6.

In order to open the easy-open packaging body 1 of this embodiment from the opening start part 34, as shown in FIG. 8, when force F is applied to the cover material 3 in the arrow direction of FIG. Aggregation peeling of the surface layer 27 proceeds.
Further, when the flaking and peeling reaches the resin reservoir 6, the flaking of the surface layer 27 proceeds along the shape of the resin pool 62 formed on the surface layer 27 and the adjacent lower and upper layers 26. Will be.

Then, when the cohesive separation of the surface layer 27 reaches the vicinity X of the inner peripheral edge of the seal portion 28, the thermoforming container 2 follows the shape of the resin reservoir 63 formed in the sealant layer 32 of the lid member 3. When the resin reservoir 61 of the surface layer 27 is cut, the thermoforming container 2 and the lid member 3 in the easy-open packaging body 1 are easily opened.

[Effects of Embodiment]
As described above, according to the above embodiment, the following effects can be obtained.
That is, in this embodiment, the multilayer sheet 20 that forms the thermoformed container 2 of the easy-open packaging body 1 has a polypropylene resin as the surface layer 27 of 30% by mass to 70% by mass and a melting point of 130 ° C. or less. The ethylene random copolymer contains 10% by mass or more and 30% by mass or less, and the low-density polyethylene resin having a melting point of 120 ° C. or more contains 20% by mass or more and 40% by mass or less. Thereby, the melting start temperature at the time of fusing the lid 3 to the thermoforming container 2 becomes about 120 ° C. or higher and 130 ° C. or lower, and the fusion temperature can be set at 160 ° C. or higher and 240 ° C. or lower. For this reason, when manufacturing the thermoforming container 2 using a direct hot plate heating type molding machine effective in terms of continuous production, the fusion temperature can be set at a higher temperature and a wider temperature range than conventional materials. Therefore, the thermoformed container 2 can be efficiently manufactured without causing inconvenience such as the surface layer 27 of the multilayer sheet 20 adhering to the hot plate of the molding machine.
Further, as the upper and lower layers 26 provided adjacent to the surface layer 27, a polypropylene resin having an isotactic pentad fraction of 93 mol% or more is a main component. As a result, the rigidity of the upper and lower layers 26 is improved, and excessive flow of the upper and lower layers 26 when the first annular seal disc 7 is pressed when the lid 3 is fused to the thermoforming container 2 can be prevented. The fluidity of the surface layer 27 can be stabilized. For this reason, there is no inconvenience that the first annular sealing disk 7 bites excessively at the time of fusion, and a stable sealing strength can be obtained and a stable sealing performance can be provided. Further, since excessive flow of the front and lower layers 26 can be prevented, a stable and good resin reservoir portion 6 can be formed, a stable sealing property can be obtained, and a stable sealing property can be provided.

And in this embodiment, the polypropylene of the isotactic pentad fraction 93 mol% contained in the surface lower layer 26 is 80 mass% or more.
For this reason, it is possible to prevent excessive biting at the time of sealing and to seal well.

Further, when the isotactic pentad fraction 93 mol% of polypropylene contained in the lower surface layer 26 is less than 80 mass%, particularly 65 mass% or more and less than 80 mass%, talc is 0.5 mass% or more. It is contained at 5% by mass or less.
For this reason, the rigidity of the surface lower layer 26 can be improved, and the thermoformed container 2 can have rigidity.

Moreover, in this embodiment, the thickness dimension of the surface layer 27 of the multilayer sheet 20 is 10 μm or more and 150 μm or less.
Therefore, the surface layer 27 having a stable thickness can be formed, the yield can be improved, and the surface layer 27 can be satisfactorily sealed without being eliminated during fusion. Furthermore, the cohesive failure surface can be stabilized and the unsealed appearance can be prevented from being impaired.

In this embodiment, the thermoformed container 2 having the flange portion 24 extending outward at the periphery of the opening 21 is positioned on the inner surface side, that is, the surface layer 27 is positioned on the inner surface side of the storage portion 23. The multilayer sheet 20 is formed by thermoforming the layer 27 to face.
For this reason, what is necessary is just to melt | fuse and seal the cover material 3 to the flange part 24, and the easy-open property and open feeling of the easy-open packaging body 1 are stabilized, and the heat resistance and the appearance of an open surface become favorable.

Furthermore, in this embodiment, the sealant layer 32 of the lid member 3 is fused to the flange portion 24 of the easy-open packaging body 1, and the resin reservoir portion 6 is formed in the vicinity of the opening portion 21 side of the flange portion 24. .
As a result, when the cohesive peeling proceeds to the place where the resin reservoir 6 is interposed, the stress that peels due to the presence of the resin reservoir 6 acts in the direction of pulling the lid 3 away from the thermoforming container 2. For this reason, the lid | cover material 3 and the flange part 24 of the thermoforming container 2 are cut | disconnected favorably, and the easily openable packaging body 1 provided with favorable openability can be provided. Furthermore, since the surface lower layer 26 and the sealant layer 32 of the lid member 3 that are hard to coagulate and break are present on both sides of the surface layer 27 that cohesively break, the sealing performance can be improved.

[Modification]
The aspect described above shows one aspect of the present invention, and the present invention is not limited to the above-described embodiment, and has the configuration of the present invention and can achieve the object and effect. It goes without saying that modifications and improvements within the scope are included in the content of the present invention. In addition, specific structures, shapes, and the like in carrying out the present invention include those modified or improved as other structures, shapes, etc. within the scope of achieving the objects and effects of the present invention. Is.

That is, in the multilayer sheet 20 and the thermoforming container 2 of the present embodiment, the configuration including the surface layer 27, the upper and lower layers 26, and the base material layer 25 has been shown, but is not limited thereto.
For example, the base material layer 25 may not be provided, and the front surface layer 27 and the front / lower layer 26 may be used. That is, it is good also as a structure which the surface lower layer 26 functions as a base material layer.
In addition, the multilayer sheet 20 and the base material layer 25 of the thermoforming container 2 of the present embodiment include a first base material layer 25A, a first adhesive layer 25B, a gas barrier layer 25C, a second adhesive layer 25D, and a second base material layer 25E. Although the structure provided with was shown, it is not restricted to this.
For example, the base material layer 25 may be configured by only the first base material layer 25A.
As described above, the multilayer sheet 20 and the thermoforming container 2 may have a multilayer configuration of two or more layers including at least the surface layer 27 and the front and lower layers 26.

And although the aspect which the surface layer 27 of the thermoforming container 2 aggregates and peels among the present embodiment was shown, it is good also as an aspect that the cover material 3 side aggregates and peels, for example. That is, you may form the cover material 3 from the multilayer sheet of this invention.
Specifically, the sealant layer 32 of the lid member 3 is made of the same material as that of the surface layer 27 of the multilayer sheet 20, and the intermediate layer 33 of the lid member 3 is made of the same material as that of the upper and lower layers 26 of the multilayer sheet 20. For example, as shown in FIGS. 10 and 11, the sealant layer 32 of the lid 3 may be fused to the flange portion 24 of the thermoforming container 2. 10 and 11, the sealant layer 32 of the lid member 3 is agglomerated and peeled when the thermoforming container 2 and the lid member 3 are opened.
Further, when opening, both the surface layer 27 of the thermoforming container 2 and the sealant layer 32 of the lid member 3 may be coherently broken and opened.
In addition, the multi-layer sheet of the present invention may be applied to various shapes of the package, in addition to the easy-open package 1 including the thermoformed container 2 and the lid 3 described above.

Further, in manufacturing the easy-open packaging body 1, in addition to the resin reservoir portion 6 formed at a portion corresponding to the position where the inner peripheral edge of the first annular seal plate 7 contacts, A resin reservoir may be formed at a portion corresponding to a position where the peripheral edge contacts.
In this case, since the resin reservoir portion 6 formed on the inner peripheral edge is larger than the resin reservoir formed on the outer peripheral edge, good easy-openability and high sealability are maintained.

And although the structure which makes the front-lower layer 26 contain talc by 0.5 mass% or more and 5 mass% or less was illustrated as the multilayer sheet 20, it does not need to contain talc.
Furthermore, as the multilayer sheet 20, the thickness dimension of the surface layer 27 may not be 10 μm or more and 150 μm or less. The thickness dimension can be appropriately set according to the application.

Next, the present invention will be described in more detail with reference to examples and comparative examples.
In addition, this invention is not restrict | limited at all to description content, such as these Examples.

[Packaging]
(Multilayer sheet)
The multilayer sheet is manufactured by using a commonly used distributor type co-extrusion multilayer sheet manufacturing apparatus, and the following surface layer / first base layer / first adhesive layer / gas barrier layer / second adhesive layer / A multilayer sheet comprising the second substrate layer was produced.
Surface layer: appropriately set for each example and comparative example described later First base layer (surface lower layer), second base layer: appropriately set for each example and comparative example described below First adhesive layer, second adhesive layer : Adhesive resin (manufactured by Mitsubishi Chemical Corporation, maleic anhydride modified PP (trade name: Modic AP P604V))
Gas barrier layer: ethylene-vinyl alcohol copolymer resin (manufactured by Kuraray (trade name: EVAL J171B))
(Thermoforming container)
Using this multilayer sheet, a direct hot plate heating type molding machine (manufactured by Shinwa Machine Co., Ltd. (trade name: direct heating type container molding machine)) was used for both the upper and lower hot plates at 200 ° C. for 2.0 seconds. A thermoformed container was formed by thermoforming three times.
(Cover material)
It was molded into a three-layer laminate of outer layer / intermediate layer / sealant layer described below.
Outer layer: Polyethylene terephthalate (Mitsubishi Chemical Corporation (trade name: Tech Barrier)) 12 μm
Intermediate layer: Nylon (made by Idemitsu Unitech Co., Ltd. (trade name: UNILON S)) 15 μm
Sealant layer: LLPE (made by Idemitsu Unitech Co., Ltd. (product name: LS700C)) 60 μm or polypropylene (PP) (made by Idemitsu Unitech Co., Ltd. (product name: RT610C)) 60 μm
(Top seal)
As will be described later, the shape of the flange of the formed thermoformed container was appropriately formed into a flat shape or a convex shape using a ring-shaped sealing board, a convex sealing board, an R sealing board, or a special-shaped sealing board. . In addition, the used sealing board is as follows.
The ring-shaped sealing discs of Examples 1 to 7 and each comparative example have a width of 1.5 mm and a flat tip shape. The fusing temperature is 190 ° C., the fusing pressure is 150 kg / piece, and the fusing time is 1.0 second.
The convex sealing disk of Example 8 has a width of 3.0 mm and a flat tip shape. The fusing temperature is 190 ° C., the fusing pressure is 150 kg / piece, and the fusing time is 1.0 second.
The R-seal disc of Example 9 has a curved surface with a width of 1.5 mm and a curvature radius of 1.0 mm at the tip protruding at the center in the width direction. The fusing temperature is 210 ° C., the fusing pressure is 200 kg / piece, and the fusing time is 1.0 second.
The specially shaped seal disc of Example 10 has the same shape as the first annular seal disc 7, the width is 1.5 mm, the inclination angle θ is 9 °, and the curved surface machining has a distance ratio radius of 0.5 mm. The fusing temperature is 210 ° C., the fusing pressure is 200 kg / piece, and the fusing time is 1.0 second.

[Example 1]
In Example 1, as shown in Table 1 below, the surface layer and the first base material layer were formed with the following resin composition.
Surface layer (thickness 50 μm):
Polypropylene (PP) (Prime Polymer Co., Ltd. (trade name: E105GM)) 40% by mass
+ Metallocene PP (manufactured by Nippon Polypro Co., Ltd. (trade name: WFX6 melting point 128 ° C.)) 30% by mass
+ Low density polyethylene (LDPE) (manufactured by Tosoh Nickemi Co., Ltd. (trade name: LW01 melting point 128 ° C.)) 30% by mass
First base material layer:
Polypropylene (PP) (manufactured by Prime Polymer Co., Ltd. (trade name: V300SVE, stereoregularity ii97 mol%)) 81.5% by mass
+ Low density polyethylene (LDPE) (Nippon Polyethylene Co., Ltd. (trade name: HE30)) 13.5% by mass
+ 5% by mass of high density polyethylene (HDPE) (manufactured by Prime Polymer Co., Ltd. (trade name: 6203B))
As described above, the flange portion was formed flat using a ring-shaped seal disc.
Example 1-1
In Example 1-1, the thermoformed container was the multilayer sheet of Example 1 above, and the sealant layer of the lid was formed of the above-described polypropylene (PP).
Example 1-2
In Example 1-2, the thermoformed container was the multilayer sheet of Example 1 described above, and the sealant layer of the lid material was formed of the above-described LLPE.

[Example 2]
In Example 2, as shown in Table 1 below, the surface layer was formed with the same composition and thickness as Example 1, and the first base material layer was formed with the following resin composition.
First base material layer:
68% by mass of polypropylene (PP) (manufactured by Prime Polymer Co., Ltd. (trade name: V300SVE, stereoregularity ii 97 mol%))
+ 14% by mass of high density polyethylene (HDPE) (manufactured by Prime Polymer Co., Ltd. (trade name: 6203B))
+ Thermoplastic elastomer (Tokyo Materials Co., Ltd. (trade name: Engage 8200)) 15% by mass
+ Talc (Idemitsu Lion Composite Co., Ltd. (trade name: HMP460-1)) 3% by mass
As described above, the flange portion was formed flat using a ring-shaped seal disc. Others were the same as in Example 1.

[Example 3]
In Example 3, as shown in Table 1 below, the surface layer was formed with the following resin composition, and the first base material layer was formed with the same composition as Example 1.
Surface layer:
Polypropylene (PP) (same material as in Example 1) 50% by mass
+ Metallocene PP (same material as Example 1) 20% by mass
+ Low density polyethylene (LDPE) (same material as Example 1) 30% by mass
As described above, the flange portion was formed flat using a ring-shaped seal disc. Others were the same as in Example 1.

[Example 4]
In Example 4, as shown in Table 1 below, the surface layer was formed with the following resin composition, and the first base material layer was formed with the same composition as Example 1.
Surface layer:
Polypropylene (PP) (same material as Example 1) 30% by mass
+ Metallocene PP (same material as Example 1) 30% by mass
+ Low density polyethylene (LDPE) (same material as in Example 1) 40% by mass
As described above, the flange portion was formed flat using a ring-shaped seal disc. Others were the same as in Example 1.

[Example 5]
In Example 5, as shown in Table 1 below, the surface layer was formed with the following resin composition, and the first base material layer was formed with the same composition as Example 1.
Surface layer:
Polypropylene (PP) (same material as in Example 1) 70% by mass
+ Metallocene PP (same material as Example 1) 10% by mass
+ Low density polyethylene (LDPE) (same material as in Example 1) 20% by mass
As described above, the flange portion was formed flat using a ring-shaped seal disc. Others were the same as in Example 1.

* 1: Peeling strength is slightly weak but good * 2: At the time of container molding, it is pulled by the hot plate but does not adhere. Peeling strength is slightly higher but good * 3: Good when pulled into a hot plate but not attached

[Example 6]
In Example 6, as shown in Table 2 below, both the surface layer and the first base material layer had the same composition as in Example 1, and the thickness dimension of the surface layer was 150 μm.
As described above, the flange portion was formed flat using a ring-shaped seal disc. Others were the same as in Example 1.

[Example 7]
In Example 7, as shown in Table 2 below, both the surface layer and the first base material layer had the same composition as Example 1, and the thickness dimension of the surface layer was 10 μm.
As described above, the flange portion was formed flat using a ring-shaped seal disc. Others were the same as in Example 1.

[Example 8]
In Example 8, as shown in Table 2 below, both the surface layer and the first base material layer had the same composition as in Example 1, and the thickness dimension of the surface layer was 50 μm.
As described above, the flange portion was formed in a convex cross section using a convex sealing disk. Others were the same as in Example 1.

[Example 9]
In Example 9, as shown in Table 2 below, both the surface layer and the first base material layer had the same composition as Example 1, and the thickness dimension of the surface layer was also formed to be the same as 50 μm.
As described above, the flange portion was formed flat using an R seal disc. Others were the same as in Example 1.

[Example 10]
In Example 10, as shown in Table 2 below, both the surface layer and the first base material layer had the same composition as in Example 1, and the thickness dimension of the surface layer was also formed to 50 μm.
As described above, the flange portion was formed in a flat shape using a specially shaped seal disc. Others were the same as in Example 1.

* 1: Peel strength is slightly weak but good

[Example 11]
Example 11 was formed with the same formulation as Example 1 as shown in Table 3 below. The surface layer was formed with a thickness of 160 μm.

[Example 12]
Example 12 was formed with the same formulation as Example 1 as shown in Table 3 below. The surface layer was formed with a thickness of 5 μm.

[Example 13]
In Example 13, as shown in Table 3 below, the surface layer was formed with the same composition as Example 1 and a thickness of 50 μm. The first base material layer was formed with the following resin composition. Others were formed in the same manner as in Example 1.
First base material layer:
75% by mass of polypropylene (PP) (manufactured by Prime Polymer Co., Ltd. (trade name: V300SVE stereoregularity ii 97 mol%))
+ 20% by mass of high density polyethylene (HDPE) (manufactured by Prime Polymer Co., Ltd. (trade name: 6203B))
+ 5% by mass of thermoplastic elastomer (manufactured by Tokyo Materials Co., Ltd. (trade name: Engage 8200))

[Example 14]
In Example 14, as shown in Table 3 below, the surface layer had the same composition as in Example 1 and was formed to a thickness of 50 μm. The first base material layer was formed with the following resin composition. Others were formed in the same manner as in Example 1.
First base material layer:
75% by mass of polypropylene (PP) (manufactured by Prime Polymer Co., Ltd. (trade name: V300SVE stereoregularity ii 97 mol%))
+ 10% by mass of high density polyethylene (HDPE) (manufactured by Prime Polymer Co., Ltd. (trade name: 6203B))
+ 5% by mass of thermoplastic elastomer (manufactured by Tokyo Materials Co., Ltd. (trade name: Engage 8200))
+ Talc (Idemitsu Lion Composite Co., Ltd. (trade name: HMP460-1)) 10% by mass

[Example 15]
In Example 15, as shown in Table 3 below, the surface layer had the same composition as Example 1 and was formed to a thickness of 50 μm. The first base material layer was formed with the following resin composition. Others were formed in the same manner as in Example 1.
First base material layer:
75% by mass of polypropylene (PP) (manufactured by Prime Polymer Co., Ltd. (trade name: V300SVE stereoregularity ii 97 mol%))
+ 20% by mass of high density polyethylene (HDPE) (manufactured by Prime Polymer Co., Ltd. (trade name: 6203B))
+ 4.7% by mass of thermoplastic elastomer (Tokyo Material Co., Ltd. (trade name: Engage 8200))
+ Talc (Idemitsu Lion Composite Co., Ltd. (trade name: HMP460-1)) 0.3% by mass

[Comparative Example 1]
In Comparative Example 1, as shown in Table 4 below, the surface layer was formed with the same composition and thickness as Example 1, and the first base material layer was formed with the following resin composition.
First base material layer:
80% by mass of polypropylene (PP) (manufactured by Prime Polymer Co., Ltd. (trade name: E105GM stereoregularity ii92 mol%))
+ Low density polyethylene (LDPE) (manufactured by Nippon Polyethylene Co., Ltd. (trade name: HE30)) 20% by mass
In addition, as above-mentioned, the flange part was formed flat using the ring-shaped sealing disk.
Then, Comparative Example 1-1 is similar to Example 1-1, in which the lid material whose sealant layer is the above-described polypropylene (PP) is fused to the thermoformed container formed of the multilayer sheet of Comparative Example 1. It was. Further, in Comparative Example 1-2, similarly to Example 1-2, the lid material whose sealant layer is the above-described LLPE is fused to the thermoformed container formed of the multilayer sheet of Comparative Example 1.

[Comparative Example 2]
In Comparative Example 2, as shown in Table 4 below, the surface layer was formed with the following resin composition to a thickness of 50 μm, and the first base material layer was formed with the same composition as Example 1, that is, polypropylene (PP). As for stereoregularity ii 97 mol% (manufactured by Prime Polymer Co., Ltd. (trade name: V300SVE)) was used. In addition, it formed similarly to the comparative example 1.
Surface layer:
Polypropylene (PP) (same material as Comparative Example 1) 70% by mass
+ 30% by mass of ethylene / acrylic acid ester / maleic anhydride copolymer (manufactured by Nippon Polyethylene Co., Ltd. (trade name: ET220X))

[Comparative Example 3]
In Comparative Example 3, as shown in Table 4 below, the surface layer was formed to a thickness of 50 μm with the following resin composition, and the first base material layer was formed with the same composition as Example 1. In addition, it formed similarly to the comparative example 1.
Surface layer:
Polypropylene (PP) (same material as Comparative Example 1) 70% by mass
+ Low density polyethylene (LDPE) (same material as Example 1) 30% by mass

[Comparative Example 4]
In Comparative Example 4, as shown in Table 4 below, the surface layer was formed to the thickness of 50 μm with the following resin composition, and the first base material layer was formed with the same composition as Example 1. In addition, it formed similarly to the comparative example 1.
Surface layer:
Polypropylene (PP) (same material as Comparative Example 1) 20% by mass
+ Metallocene PP (same material as Example 1) 50% by mass
+ Low density polyethylene (LDPE) (same material as Example 1) 30% by mass

[Comparative Example 5]
In Comparative Example 5, as shown in Table 5 below, the surface layer was formed to a thickness of 50 μm with the following resin composition, and the first base material layer was formed with the same composition as Example 1. In addition, it formed similarly to the comparative example 1.
Surface layer:
Polypropylene (PP) (same material as Comparative Example 1) 75% by mass
+ Metallocene PP (same material as Example 1) 5% by mass
+ Low density polyethylene (LDPE) (same material as Example 1) 20% by mass

[Comparative Example 6]
In Comparative Example 6, as shown in Table 5 below, the surface layer was formed with the following resin composition to a thickness of 50 μm, and the first base material layer was formed with the same composition as Example 1. In addition, it formed similarly to the comparative example 1.
Surface layer:
Polypropylene (PP) (same material as Comparative Example 1) 30% by mass
+ Metallocene PP (same material as Example 1) 25% by mass
+ Low density polyethylene (LDPE) (same material as in Example 1) 45% by mass

[Comparative Example 7]
In Comparative Example 7, as shown in Table 5 below, the surface layer was formed to a thickness of 50 μm with the following resin composition, and the first base material layer was formed with the same composition as Example 1. In addition, it formed similarly to the comparative example 1.
Surface layer:
Polypropylene (PP) (same material as Comparative Example 1) 60% by mass
+ Metallocene PP (same material as Example 1) 25% by mass
+ Low density polyethylene (LDPE) (same material as Example 1) 15% by mass

[Evaluation]
The heat resistance, adhesion (sealing) property, peel strength, and unsealed appearance of Examples 1-1 to 15-2 and Comparative Examples 1-1 to 7-2 obtained as described above were compared based on the following criteria: evaluated. The results are shown in Tables 1 to 5 above.

(Heat-resistant)
As for heat resistance, adhesion to a heated heating plate assuming a hot plate contact heating method at the time of thermoforming a thermoformed container was evaluated. Evaluation is in the following three stages.
A: When not attaching to a heating plate at 170 ° C.
B: It does not adhere to the heating plate at 155 ° C, but adheres to the heating plate at 170 ° C.
C: When attached to a heating plate at 155 ° C.

(Adhesion (sealing))
The adhesion (sealing) property is obtained by cutting the side part of the obtained package to a width of 15 mm to obtain a test sample, and from the inside to the outside of the flange part, a tensile tester (manufactured by Imada Co., Ltd. (trade name: Digital Force Gauge / Using a motorized stand)), measurement was performed 8 times at 180 ° peeling and 300 mm / min. Evaluation is in the following two stages.
A: Tensile strength is 9.8 N (1.0 kgf) or more in all 8 times.
B: The average of 8 times of tensile strength is 9.8 N (1.0 kgf) or more.
C: The average of 8 times of tensile strength is less than 9.8 N (1.0 kgf).

(Peel strength)
The peel strength was cut to 15 mm width at the position of the opening start portion at the four corners of the obtained package to obtain a test sample, and the 135 ° peel, 300 mm / 300 mm from the outside of the flange portion to the inside using the above-described tensile tester. The measurement was performed 6 times per minute. Evaluation is in the following three stages.
A: Tensile strength is 6.9 N (0.7 kgf) or more and less than 11.8 N (1.2 kgf) B: Tensile strength is 4.9 N (0.5 kgf) or more and less than 6.9 N (0.7 kgf) or tensile strength is 11.8 N (1.2 kgf) or more and less than 14.7 N (1.5 kgf) C: Tensile strength less than 4.9 N (0.5 kgf) or 14.7 N (1.5 kgf) or less

(Open appearance)
The unsealed appearance was evaluated by observing the presence or absence of fluffing and tearing of the lid after opening. Evaluation is in the following two stages.
A: No fuzzing or tearing of the lid material occurs.
B: Slight fuzz is recognized, but the lid material is not broken.
C: Fluffing or tearing of the cover material occurs.

[result]
As shown in Tables 1 to 5, in Examples 1 to 15, good results were obtained in terms of adhesion (sealing), peel strength, and unsealed appearance.
In Examples 3 and 5, since the blending ratio of PP in the surface layer was large, the peel strength was slightly weak. Moreover, in Example 4, since the blending ratio of PP in the surface layer was small and the low-density polyethylene was large, there was a tendency to be pulled although it did not adhere to the hot plate during thermoforming. Others were good.
On the other hand, in Comparative Example 5 and Comparative Example 7 in which the blending ratio of PP is large and the low-density polyethylene is a small blending, the adhesive strength was too strong to peel. Further, in Comparative Example 6 in which there is a large amount of low density polyethylene, there was an inconvenience that the continuous molding was interrupted by adhering to the hot plate during thermoforming.
Further, in Comparative Example 1 where the isotactic pentad fraction in the lower and lower layers was 92 mol%, the lid material could not be stably fused at the time of fusion, and the variation in adhesiveness and peel strength was large. On the other hand, in an example where the isotactic pentad fraction was 97 mol%, stable adhesiveness and peel strength were obtained.
From Examples 1 and 8 to 10, it was not recognized that the evaluation differs greatly depending on the shape of the flange portion.
From these results, by forming within the blending range of the present invention, it is possible to easily form continuously without causing the inconvenience of the multi-layer sheet adhering during thermoforming, and to obtain a stable sealing property and a package with stable characteristics. It was recognized that we could provide

The present invention has both a high sealing property and an easy-opening property. A multilayer sheet for producing this thermoformed container can be applied.

DESCRIPTION OF SYMBOLS 1 ... Easy-open packaging body 2 ... Thermoformed container 3 ... Cover material 6 ... Resin pool part 20 ... Multilayer sheet 21 ... Opening part 24 ... Flange part 26 ... Outer layer 27 ... Surface layer 32 ... Sealant layer

Claims

A multilayer sheet composed of a laminate of at least two layers of a surface layer and a surface layer provided adjacent to the surface layer,
The surface layer comprises a low-density polyethylene resin having a polypropylene resin of 30% by mass to 70% by mass, a propylene-ethylene random copolymer having a melting point of 130 ° C. or less of 10% by mass to 30% by mass, and a melting point of 120 ° C. or more. Contains 20% by mass or more and 40% by mass or less,
The multilayered sheet characterized in that the front and lower layers are mainly composed of a polypropylene resin having an isotactic pentad fraction of 93 mol% or more.
The multilayer sheet according to claim 1,
The said lower surface layer contains the polypropylene with an isotactic pentad fraction of 93 mol% or more at 80 mass% or more. The multilayer sheet characterized by the above-mentioned.
The multilayer sheet according to claim 1,
When the content of polypropylene having an isotactic pentad fraction of 93 mol% or more is less than 80% by mass, the surface lower layer contains talc in an amount of 0.5% by mass or more and 5% by mass or less. Multi-layer sheet.
In the multilayer sheet according to any one of claims 1 to 3,
The surface layer has a thickness dimension of 10 μm or more and 150 μm or less.
A thermoformed container having an opening obtained by thermoforming the multilayer sheet according to any one of claims 1 to 4,
A flange extending outward is formed at the periphery of the opening,
The surface layer is formed on the inner surface side of the thermoformed container.
A thermoformed container according to claim 5;
An easy-open packaging body, comprising: a lid member that is fused to the flange portion of the thermoformed container and closes the opening.
In the easy-open packaging body according to claim 6,
The lid member has a sealant layer on the surface to be fused to the thermoformed container,
In the vicinity of the opening side of the flange portion, a resin reservoir is formed by the surface layer, the upper and lower layers, and a sealant layer of the lid material.