JP2010111087A - Multilayer sheet, thermoformed container, and easy-to-open package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a container with stable easy-to-open property and opening feeling, and with good heat resistance and appearance of opened surface; a package provided with the container; and a multilayer sheet constituting the container and the package. <P>SOLUTION: The multilayer sheet 20 is a sheet comprising a surface layer 21 and a sub-surface layer 22 laid next to the surface layer 21, where the thickness size of the surface layer 21 is 1-200 μm, the surface layer 21 is constituted by including polypropylene, a polypropylene-based resin, a polyethylene-based resin and a styrene-based polymer the content rates of which are 60-80 wt.%, 1-10 wt.%, 8-28 wt.% and 4-14 wt.%, respectively, and the sub-surface layer 22 includes a polyethylene-based resin the content rate of which is 5-50 wt.%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer sheet, a thermoformed container, and an easy-open packaging body provided with the container. For example, it is an easy-open packaging body using a packaging form in which a lid material and a container are sealed by heat sealing, and packages food, medicine, cosmetics, and the like.

2. Description of the Related Art In recent years, with increasing awareness of food safety, easily openable containers and lids that can improve the hermeticity of contents and take out the contents, and packages including these containers and lids are known. (See Patent Documents 1 and 2).
Patent Document 1 discloses a multilayer sheet including a layer A made of a polyolefin resin and an ethylene / acrylic acid ester / maleic anhydride copolymer resin and a layer B made of a polyolefin resin. A thermoformed container formed by thermoforming a multilayer sheet is also disclosed.
Patent Document 2 discloses an easily peelable composite sheet for a lid material composed of two layers of a surface layer containing a polyolefin resin and a styrene block polymer and a base material layer containing a styrene resin and a styrene block polymer. Has been.

JP 2003-231226 A JP-A-7-223299

However, in the container described in Patent Document 1, the unsealed surface is unstable due to random occurrence of cohesive failure occurring in the A layer as the sealing layer and delamination between the A layer and the adjacent B layer. There is. Therefore, a trace of cohesive failure that is disturbed on the seal surface remains like hair, which may result in a partial mixing of the package and a feeling at the time of opening.
Moreover, the raw material which comprises A layer uses what has low melting | fusing point. Therefore, when the heating zone at the time of thermoforming is contact heating of the heating plate, the sheet adheres to the heating plate and may inhibit stable container forming. Furthermore, when placed in a high-temperature atmosphere during the filling, sterilization, and storage processes of the contents, the A layer may melt or be easily broken. Furthermore, when the heat seal condition is set high, the A layer is likely to be rejected, which may cause the sealing performance to be hindered.
Moreover, the thing of patent document 2 opens by delamination, and peeling strength may change easily by the change of the heating conditions at the time of sheet | seat shaping | molding, and container thermoforming, and a feeling of opening may worsen. .
Further, when the package is filled with the contents and sealed, the heat seal condition may be set high in order to prevent leakage of the contents. However, in this case, the appearance after opening and the feeling of opening may be sacrificed due to the improved sealing performance.

  An object of the present invention is to provide a container having stable openability and opening feeling, heat resistance and good appearance of an opened surface, a package including the container, and a multilayer sheet constituting the container and the package. There is.

The multilayer sheet of the present invention is a multilayer sheet configured to include a surface layer and a surface layer laminated adjacent to the surface layer, and the thickness dimension of the surface layer is 1 μm to 200 μm, The surface layer includes a polypropylene, a polypropylene resin, a polyethylene resin, and a styrene polymer, and the content of these polypropylene, polypropylene resin, polyethylene resin, and styrene polymer is 60 wt% or more and 80 wt%, respectively. 1 wt% or more and 10 wt% or less, 8 wt% or more and 28 wt% or less, 4 wt% or more and 14 wt% or less, and the front and lower layers contain a polyethylene resin, and the content of the polyethylene resin is 5 wt% or more and 50 wt% It is characterized by the following.
The multilayer sheet of the present invention is a multilayer sheet comprising a surface layer and a base material layer laminated adjacent to the surface layer, and the thickness dimension of the surface layer is 1 μm to 200 μm. And the surface layer includes polypropylene, a polypropylene resin, a polyethylene resin, and a styrene polymer, and the content of these polypropylene, polypropylene resin, polyethylene resin, and styrene polymer is 60 wt%, respectively. 80 wt% or less, 1 wt% or more and 10 wt% or less, 8 wt% or more and 28 wt% or less, 4 wt% or more and 14 wt% or less, and the base material layer contains a polyethylene resin, and the content of the polyethylene resin is 5 wt% % Or more and 50 wt% or less.
Here, in the multilayer sheet of the present invention, it is preferable that a dispersing agent is contained in the surface layer.
Moreover, in this invention, it is preferable that the polypropylene resin used for the said surface layer is a propylene ethylene butene 1 terpolymer. Furthermore, the styrenic polymer is preferably a styrene ethylene butene styrene block copolymer.
A thermoformed container of the present invention is a thermoformed container having an opening obtained by thermoforming the multilayer sheet according to any one of claims 1 to 4, wherein A flange portion is formed around the periphery.
An easy-open packaging body according to the present invention is characterized by comprising the container according to claim 5 and a lid member fused to close the opening of the container.
Here, in the easy-open packaging body of the present invention, it is preferable that a resin reservoir is formed in the vicinity of the opening of the flange portion.

  ADVANTAGE OF THE INVENTION According to this invention, the easy-open property and opening feel are stabilized, the heat resistance and the favorable external appearance of an open surface are provided, the package provided with the container, and the multilayer sheet which comprises these containers and a package be able to.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a multilayer sheet according to an embodiment of the present invention.

The multilayer sheet 20 of the present invention includes a base material layer 23, a surface lower layer 22 laminated adjacent to the base material layer 23, and a cohesive fracture surface layer 21 laminated adjacent to the surface lower layer 22. Prepare.
The base material layer 23 has a configuration in which a first base material layer 23E, a first adhesive layer 23D, a gas barrier layer 23C, a second adhesive layer 23B, and a second base material layer 23A are sequentially laminated. It is.

For example, a polypropylene resin, a polyethylene resin, a polyamide resin, a polyethylene terephthalate resin, or the like can be used for the first and second base material layers 23E and 23A, but is not limited thereto. The thickness of each base material layer 23E and 23A is 100-2000 micrometers, Preferably, it is 200-1000 micrometers.
For the first and second adhesive layers 23D and 23B, for example, a polyvinylidene chloride resin can be used, but an unsaturated carboxylic acid or a derivative-modified polyolefin resin thereof may be used.
As the gas barrier layer 23C, it is preferable to use materials such as polyamide resin, polyethylene terephthalate resin, ethylene-vinyl alcohol resin, and polyvinylidene chloride. Among them, it is preferable to use ethylene-vinyl alcohol resin.

The lower surface layer 22 contains a polyethylene-based resin, and the content thereof is 5 wt% or more and 50 wt% or less, preferably 10 wt% or more and 30 wt% or less.
Further, the front and lower layer 22 may contain a polypropylene resin, for example, homopolypropylene or random polypropylene.

The surface layer 21 contains at least polypropylene, polypropylene resin, polyethylene resin, and styrene polymer.
The content of polypropylene is 60 wt% or more and 80 wt% or less, preferably 65 wt% or more and 75 wt% or less.
The content of the polypropylene resin is 1 wt% or more and 10 wt% or less, preferably 2 wt% or more and 5 wt% or less. As the polypropylene resin, for example, propylene ethylene butene 1 terpolymer can be used.
Further, the content of the polyethylene resin in the surface layer 21 is 8 wt% or more and 28 wt% or less, preferably 13 wt% or more and 23 wt% or less.
The content of the styrenic polymer is 4 wt% or more and 14 wt% or less, preferably 6 wt% or more and 12 wt% or less.
Styrene polymers used in the present embodiment include styrene, aromatic vinyl hydrocarbons such as o-methyl styrene, m-methyl styrene, p-methyl styrene, ethyl styrene, dimethyl styrene, butadiene, isoprene, pentadiene, and the like. It is a block copolymer with a diene compound. The structure includes binary block copolymers such as polystyrene-polybutadiene (SB) and polystyrene-polyisoprene (SI), ternary systems such as polystyrene-polybutadiene-polystyrene (SBS) and polystyrene-polyisoprene-polystyrene (SIS). It is a block copolymer. In addition, saturated PS-based BPs such as styrene-ethylenebutene-styrene (SEBS) and styrene-ethylenepropylene-styrene (SEPS) obtained by hydrogenating these block copolymers may be mentioned. For the SB BP, it is preferable to use a styrene ethylene butene styrene block copolymer.

  The styrene content in the styrenic polymer is not particularly limited, but a commercially available product of aromatic vinyl hydrocarbon such as styrene in the range of 10 wt% to 80 wt%, specifically, ) Denka STR, Denka Clearen, Nippon Synthetic Rubber Co., Ltd. JSR-TR, Asahi Kasei Kogyo Co., Ltd. Flex TR, Clayton G, Kuraray Co., Ltd. Septon, etc. can be used.

Further, the surface layer 21 may further contain a dispersant. In this case, the content of the dispersant is 1 wt% or more and 8 wt% or less, preferably 2 wt% or more and 5 wt% or less.
The thickness of the surface layer 21 is 1 μm or more and 200 μm or less, preferably 10 μm or more and 100 μm or less.

  Such a multilayer sheet 20 is formed by a multilayer extrusion method using a T die. That is, using an extruder corresponding to each layer 21 to 23, each layer 21 to 23 extruded from each extruder is joined and laminated by a special block provided immediately before entering the T die.

Next, with reference to FIGS. 2 and 3, an easy-open packaging body (hereinafter abbreviated as “packaging body”) including a container and a lid according to an embodiment of the present invention will be described. The package of this embodiment can be suitably used as a package for food such as desserts, food for microwave ovens, food for retort and the like.
[First Embodiment]
(I) Configuration of package 1:
FIG. 2 is a schematic view showing one aspect (first embodiment) of the package 1 of the present invention, FIG. 2 (A) is in a state where the lid 3 is sealed, and FIG. 2 (B) is the start of opening. The state which opened the cover material 3 from the part 4 is each shown. FIG. 3 is a cross-sectional view of the opening start portion 4 of FIG.

The thermoformed container 2 (hereinafter abbreviated as “container”) has the lid 3 placed on the opening 24 and the flange 25 and the lid disposed on the periphery of the opening 24 of the container 2. 3 is heat-sealed to form an annular seal portion 26 (a seal portion 262 formed by the annular seal disc 7 and 261 formed by the annular seal disc 7a shown in FIG. 3). As shown, the inside of one easy-open container is sealed.
On the other hand, in order to open the package 1 in a sealed state, as shown in FIG. 2B (and as shown in FIGS. 7 and 8 to be described later), an opening provided at the corner of the package 1 is provided. If the cover member 3 is pulled upward at the start portion 4 (in the direction of the arrow in FIG. 2B), the package 1 is easily opened.

(I-1) Configuration of container 2:
The package 1 shown in FIGS. 2 and 3 includes a container 2, and the container 2 is a laminate including a surface layer 21, a surface lower layer 22, and a base material layer 23.
Further, the container 2 has a substantially rectangular tray shape having a predetermined depth, and has a substantially rectangular opening 24, and a flange portion protrudes outward from the periphery of the opening 24. 25 is arranged.

  Here, in the present embodiment, as shown in FIG. 7 to be described later, the surface layer 21 of the container 2 is opened by cohesive peeling which causes cohesive failure.

(I-2) Configuration of the lid member 3:
In this embodiment, the lid member 3 is interposed between the outer layer 33 that appears outside the package 1, the seal layer 31 that is heat-sealed with the surface layer 21 of the container 2, and the seal layer 31 and the outer layer 33. It is a laminate composed of the intermediate layer 32 formed.
The surface layer 21 of the container 2 and the sealing layer 31 of the lid material 3 to be heat-sealed are in an opened state in which the surface layer 21 of the container 2 is peeled off due to cohesive failure.

  The intermediate layer 32 constituting the lid member 3 preferably uses a polyamide-based resin, and the outer layer 33 preferably uses a polyethylene terephthalate-based resin. For example, a polyethylene terephthalate (PET) film, a biaxially stretched nylon film (O—Ny), or the like can be used.

  In the case where such a surface layer 21 is used for the container 2 and the sealing layer 31 is used for the lid member 3 and both are heat-sealed, both the layers 21 and 31 are fused, while opening. In this case, the surface layer 21 of the container 2 that is weak against stress is agglomerated and peeled off, and the opening is performed well.

(I-3) Formation of resin reservoir 6:
As shown in FIG. 3, the packaging body 1 of the present embodiment has a surface layer 22, a surface layer 21, and a lid of the container 2 in the vicinity of the inner periphery of the seal portion (position X in FIG. 3) on the flange portion 25. As the seal layer 31 of the material 3 is pushed out in the direction of the opening 24 of the container 2, a knob-shaped resin reservoir 6 is formed.
As shown in FIG. 3, the resin reservoir 6 is formed by collecting the resin reservoir 61 of the surface layer 21 of the container 2, the resin reservoir 62 of the front and lower layers 22, and the resin reservoir 63 of the seal layer 31 of the lid member 3. However, by forming such a resin reservoir 6 on the package 1 in an opened form in which the surface layer 21 of the container 2 is agglomerated and peeled, the container 2 has a high sealing property and is opened by agglomeration and peeling. While adopting a form to maintain easy-openability in a good state, the lid 3 and the flange portion 25 of the container 2 in the resin reservoir portion 6 are simply cut, and stress due to internal pressure is applied. By changing the direction of easy opening by cohesive failure, the sealing performance is improved.

  Further, in the present invention, the resin reservoir portion 6 is provided on the entire periphery in the vicinity of the inner peripheral edge (position X in FIG. 3) of the annular seal portion 262 on the upper surface of the flange portion 25 of the container, and the opening of the container is started. The outer peripheral edge of the annular seal part 262 in the part is flat or has only a resin reservoir smaller than the resin reservoir part 6 in the vicinity of the inner peripheral edge X, and the annular seal part is provided in a part other than the start part 4 of the container 2. The container 1 having a resin reservoir portion (not shown) of the same size as the resin reservoir portion 6 in the vicinity of the inner peripheral edge X also on the entire outer peripheral edge of the H.262 has a high sealability, an easy opening property, and an opening start portion 4. It is preferable at the point which is excellent in the opening prevention property of the lid | cover material 3 from other than.

  Here, if the content of the polyethylene resin in the front and lower layers 22 of the container 2 is less than 5 wt%, fuzz may occur due to the surface layer 21 and the interlayer between the front and lower layers 22 and the cohesive failure surface. On the other hand, when the content of the polyethylene-based resin exceeds 50 wt%, the interlayer may peel between the front lower layer 22 and the base material layer 23.

Moreover, when the content of polypropylene in the surface layer 21 of the container 2 is less than 60 wt%, adhesion to the lid member 3 is weak, adhesion may deteriorate, and heat resistance may deteriorate. On the other hand, when the content of polypropylene exceeds 80 wt%, the adhesion becomes too strong, and the opening property may deteriorate.
Moreover, when the content of the polypropylene resin in the surface layer 21 of the container 2 is less than 1 wt%, the adhesion to 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 exceeds 10 wt%, the adhesion with the lid member 3 becomes too strong, and the unsealing property may deteriorate or the cost may increase.
And when content of the polyethylene-type resin of the surface layer 21 is less than 8 wt%, adhesiveness with the lid | cover material 3 will become strong too much, and unsealing property may deteriorate. On the other hand, when the content of the polyethylene resin exceeds 28 wt%, the cost may increase.
Furthermore, when the content of the styrenic polymer in the surface layer 21 is less than 4 wt%, the dispersibility may deteriorate. On the other hand, when the content of the styrenic polymer exceeds 14 wt%, the heat resistance may deteriorate and the cost may increase.
If the thickness of the surface layer 21 is less than 1 μm or more than 200 μm, cohesive failure may be difficult to occur.

  In manufacturing the packaging body 1, in order to fuse the flange portion 25 of the container 2 and the lid member 3 and to seal the packaging body 1, the lid member 3 is overlapped on the flange portion 25 of the container 2. The heat sealing is carried out by pressing the heated annular sealing disc from the upper surface of the lid member 3. As described above, in the vicinity of the inner peripheral edge X of the sealing portion of the opening start portion 4, a ridge shape is formed. In order to form the resin reservoir 6, for example, the following method may be used.

FIG. 4 is a schematic diagram showing a sealing process of the opening start portion 4 when manufacturing the package 1 of the present embodiment.
As shown in FIG. 4, the heat sealing between the flange portion 25 of the container 2 and the lid member 3 is performed by superimposing the lid member 3 on the flange portion 25 of the container 2, and the annular seal in a heated state from above the lid member 3. This is performed by pressing the board 7 in the direction of the arrow in FIG. 4, whereby the surface layer 21 that appears on the flange portion 25 of the container 2 and the seal layer 31 of the lid member 3 are fused.

FIG. 5 is a partial cross-sectional view showing the state of the annular seal disc 7 and the flange portion 25 at the time of heat sealing, and FIG. 6 is a partial enlarged cross-sectional view of the annular seal disc 7.
The annular seal disc 7 used for manufacturing the package 1 of the present embodiment has an inner peripheral edge subjected to R processing on the upper surface of the flange portion, and the outer peripheral edge is the tip of the annular seal disc 7 (in FIG. 6). It is an annular seal disc 7 shaped so as to come into contact with the lid member 3 later than the tip 73), specifically, on the outer peripheral edge side via the boundary A (also the tip 73 of the annular seal disc 7), An inclined surface portion 71 having an inclined cross section is formed on the inner peripheral edge side, and a curved surface portion 72 having a curved cross section is continuously formed on the inner periphery side.

Among these, the angle (θ) that is formed from the inner peripheral edge toward the outer peripheral edge with respect to the flange portion 25 as shown in FIG. 5 in the inclined surface portion 71 formed on the outer peripheral edge side of the annular seal disc 7 is annular. Although it varies depending on the width H of the seal disc 7, it is preferably set to 2 to 20 °, preferably 3 to 15 °.
When 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 26 even when pressed at the time of heat sealing. Thus, the resistance increases outside the seal portion 26 when the obtained container 1 is opened, and it is difficult to smoothly open the package 1. 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 sealing or opening, which may impair easy-openability. There is.

  Further, the R processing applied to the curved surface portion 72 formed on the inner peripheral edge side of the annular seal disc 7 varies depending on the width H of the annular seal disc 7, but R is about 0.2 mm to 0.5 HmmR. Preferably, about 0.5 mm to 0.4 HmmR is particularly preferable. If R is less than 0.2 mmR, the periphery of the boundary A may be sharply sharpened, and the lid 3 or the like may be cut during sealing or opening. On the other hand, when R exceeds 0.5 HmmR, the resin pool portion 6 is hardly formed in the vicinity of the inner peripheral edge 24 of the seal portion of the flange portion 25 even when pressed at the time of heat sealing.

  Here, with respect to the annular seal disc 7, the inclined surface portion 71 and the curved surface portion 72 are formed so that the boundary A is closer to the inner side (closer to the inner peripheral edge) than the cross-sectional width direction of the annular seal disc 7. Is preferred. If the boundary A is inside with respect to the cross-sectional width direction of the annular seal disc 7, the curved surface portion 72 may be formed on the inner peripheral side of the annular seal disc 7, and the inclined surface portion 71 may be formed on the outer peripheral side of the seal disc 7. Together, it is ensured that the tip 73 comes into contact with the lid 3 first from the outer peripheral side of the annular seal disc 7 during heat sealing (the outer peripheral edge of the annular seal disc 7 comes into contact with the lid 3 after the tip 73 later). Thus, the resin reservoir portion 6 is selectively formed on the inner side with respect to the opening portion 24 side on the inner peripheral edge side in contact with the tip.

  Further, in the present invention, the curved surface portion 72 having a curved cross section is formed on the entire circumference of the inner peripheral edge and the outer peripheral edge of the annular sealing plate 7 corresponding to the portion other than the opening start portion 4 of the container 1. The portion of the annular seal disc 7 that is formed and corresponds to the opening start portion 4 of the container 1 has the curved surface portion 72 having a curved cross section formed on the inner periphery, and the outer periphery is an annular seal. When an annular seal disc having a shape that comes in contact with the lid 3 after the tip 73 of the disc 7 is used, high sealing performance, easy opening, and prevention of opening the lid 3 from other than the opening start portion 4 It is preferable at the point which can manufacture the container which is excellent in this.

  The annular seal disc 7 is an annular seal disc in which the inclined surface portion 71 and the curved surface portion 72 are continuously formed in an annular shape in order to integrally form the circumferential heat seal portion 26 as shown in FIG. It is also possible to use 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 4 of the package 1.

  In order to heat-seal the flange portion 25 of the container 2 and the lid 3 using the annular seal disc 7 having the shape shown in FIGS. 5 and 6, first, as shown in FIG. The tip 73 corresponding to the boundary A between the surface portion 71 and the curved surface portion 72 is in contact with the lid member 3, and thereafter, the curved surface portion 72 formed on the inner peripheral edge side of the boundary A is directed toward the inside of the lid member 3. The inclined surface portion 71 formed on the outer peripheral edge side of the boundary A presses toward the outside of the lid member 3. Thereby, the resin component of the surface layer 21 of the container 2 and the surface layer 22 adjacent to the surface layer 21 is pushed out from the lower part of the boundary A to the inside of the container 2, and the inside of the annular seal disc 7 of the flange portion 25. Swell-like resin reservoirs 61 and 62 are formed in the vicinity of the position where the peripheral edge contacts, that is, in the vicinity of the inner peripheral edge X of the seal portion 26 of the container 2, and the seal layer 31 of the lid member 3 follows the resin reservoir. 63, and in a state where these form the resin reservoir 6, the surface layer 21 that appears on the flange 25 of the container 2 and the sealing layer 31 of the lid 3 are heat sealed, and both are fused. Will be.

Here, as the sealing condition, the sealing temperature may be appropriately determined depending on the type of the material to be heat-sealed or the like, but generally may be about 160 ° C to 240 ° C. Similarly, the sealing pressure may be about 10 to 50 kg / cm ² (100 to 500 kPa).

  In addition, there exists a possibility that a foreign material may enter easily from an outer periphery side only by the heat seal by the annular sealing board 7. FIG. In order to prevent such a situation, in this case, the sealing layer 31 of the lid member 3 is replaced with the surface layer 21 of the flange portion 25 while the above-described knob-shaped resin reservoir portion 6 is formed by the annular sealing disc 7. After heat-sealing, the other annular seal disc (annular seal disc 7a in FIG. 3) is used so that the annular seal disc does not hit the resin reservoir 6 and hits the outer peripheral side of the resin reservoir 7. What is necessary is just to heat-seal the surface layer 21 of the container 2 and the sealing layer 31 of the lid | cover material 3 by pressing. Although the sealing surface of the other annular sealing disk 7a described above may be smooth, it may be a surface capable of partial adhesion such as knurling so as not to impair easy-openability.

(I-4) Opening of the package 1:
FIG. 7 is a cross-sectional view showing a state in which the package 1 of the present embodiment is initially opened, and FIG. 8 is a cross-sectional view showing a state in which the package 1 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 package 1 of the present embodiment obtained by heat-sealing the flange portion 25 and the lid material 3 of the container 2 as described above from the opening start portion 4, as shown in FIG. When a force F is applied to the lid 3 in the direction of the arrow in FIG. 7, the cohesive separation of the surface layer 21 of the container 2 proceeds.
In addition, when the aggregated peeling reaches the resin reservoir 6, the aggregated peeling of the surface layer 21 proceeds along the shape of the resin reservoir 62 formed on the surface layer 22 adjacent to the surface layer 21. It will be.

  Then, when the cohesive peeling of the surface layer 21 reaches the vicinity of the inner peripheral edge X (which also becomes the cutting position) X of the seal portion, it follows the shape of the resin reservoir 63 formed in the seal layer 31 of the lid member 3. By cutting the resin reservoir 61 of the surface layer 21 of the container 2, the container 2 and the lid member 3 in the package 1 are easily opened.

[Effect of the embodiment]
In the multilayer sheet 20 constituting the container 2 of the present embodiment, the thickness of the surface layer 21 and the respective contents of polypropylene, polypropylene resin, polyethylene resin, and styrene polymer contained in the surface layer were specified. . Furthermore, the content rate of the polyethylene-type resin of the surface lower layer 22 was also specified.
Therefore, the peeling surface by the cohesive failure inside the surface layer 21 can be stabilized, and easy opening property and opening feeling can be ensured. In addition, since the aggregation peeling position does not shift, mixing of the aggregation portion can be prevented, and a clean unsealed appearance can be achieved.
Moreover, the heat resistance in a high temperature atmosphere can be improved, and adhesion of the sheet to the heating plate can be prevented when the heating plate is contacted during thermoforming. Therefore, it is possible to realize stable productivity obtained from heat resistance regardless of the heating method of the thermoforming machine.
Furthermore, the content of the oily content, filling at a high temperature, and sheet dissolution at the time of reheating can be prevented, and the container 2 can be used regardless of the content, the storage method, and the cooking method.
In addition, when the cover material 3 is heat-sealed to the multilayer sheet 20 that does not include the front and lower layers 22 and includes only one layer of the surface layer 21, an appearance defect may occur at the time of opening or the opening feeling may not be stable.

  Moreover, the dispersibility of a styrene-type polymer improves by containing the dispersing agent in the surface layer 21, The unevenness | protrusion which generate | occur | produces in the surface layer 21 is eliminated, and the external appearance of the container 2 may improve more.

The package 1 of the present embodiment is formed by heat-sealing the lid 3 on the flange portion 25 of the container 2.
The package 1 has a stable openability and a feel of opening, and heat resistance and an appearance of the opening surface are good.

Further, the resin reservoir 6 was formed in the vicinity of the opening 24 side of the package 1.
For this reason, when the cohesive peeling proceeds to the point 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 separating the lid 3 from the container 2. Cutting with the flange part 25 will be performed favorably, and it will become the package 1 provided with favorable openability.

[Second Embodiment]
The package 1 according to the first embodiment described above shows a mode in which the surface layer 21 of the container 2 is agglomerated and peeled when the container 2 and the lid 3 are opened.
On the other hand, as shown in FIGS. 9 and 10, the packaging body 1 a of the second embodiment is such that when the container 2 and the lid 3 are opened, the seal layer 31 of the lid 3 is agglomerated and peeled off. This is different from the first embodiment.
In the present embodiment, the same structure and the same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

FIG. 9 is a cross-sectional view showing a state in which the package 1a of the present embodiment is initially opened, and FIG. 10 is a cross-sectional view showing a state in which the package 1a is completely opened.
As shown in FIGS. 9 and 10, in order for the sealing layer 31 of the lid member 3 constituting the package 1 a to cohesively break and the lid member 3 to peel off, as a material constituting the sealing layer 31, A configuration similar to that of the surface layer 21 described above is employed, and a configuration similar to that of the surface layer 22 described above is employed as the intermediate layer 32.
In this case, as the surface layer 21 of the container 2, a polyolefin resin such as a polypropylene resin or a polyethylene resin, or a blend system thereof may be used.

  In the case where such a sealing layer 31 is used for the lid member 3 and the surface layer 21 is used for the container 2 and both are heat-sealed, both layers 21 and 31 are fused, while opening, The sealing layer 31 of the lid 3 that is weak against stress is coherently broken, and the opening is performed well.

In order to open the package 1a of the present embodiment from the opening start part 4, as shown in FIG. 9, when a force F is applied to the lid 3 in the direction of the arrow in FIG. Aggregation peeling of the layer 31 will progress. When the opening reaches the resin reservoir 6, the cohesive separation of the seal layer 31 follows the shape of the resin reservoir 61 formed on the surface layer 21 of the container 2 heat-sealed with the seal layer 31. Will proceed.
After the cohesive separation of the seal layer 31 of the lid 3 reaches the vicinity of the inner peripheral edge X (which also becomes the cutting position) X of the seal portion, the resin reservoir 63 of the seal layer 31 is cut, whereby the package 1 The container 2 and the lid 3 are easily opened.

[Modification of Embodiment]
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. Further, the specific structure, shape, etc. in carrying out the present invention are not problematic as other structures, shapes, etc., within the scope of achieving the objects and effects of the present invention. The present invention is not limited to the above-described embodiments, and modifications and improvements within the scope that can achieve the object of the present invention are included in the present invention.

In the multilayer sheet 20 and the container 2 of the present embodiment, the configuration including the surface layer 21, the front lower layer 22, and the base material layer 23 is shown, but is not limited thereto.
For example, the base material layer may not be provided, and the front surface layer 21 and the upper and lower layers 22 may be configured as two layers. That is, the structure which the surface lower layer 22 becomes a base material layer may be sufficient.
In addition, the multilayer sheet 20 and the substrate layer 23 of the container 2 of the present embodiment include the first substrate layer 23E, the first adhesive layer 23D, the gas barrier layer 23C, the second adhesive layer 23B, and the second substrate. Although the configuration including the layer 23A is shown, the configuration is not limited thereto.
For example, as shown in FIG. 11, the base material layer 23 may be composed of only the first base material layer 23E.
That is, the multilayer sheet 20 and the container 2 may have a multilayer configuration of two or more layers including at least the surface layer 21 and the upper and lower layers 22.

  In the present embodiment, the surface layer 21 of the container 2 is agglomerated and peeled. However, in the present invention, both the surface layer 21 of the container 2 and the seal layer 31 of the lid 3 are opened at the time of opening. This includes the case where the layer is coherently broken and opened.

In addition, when implementing the manufacturing method of the easily openable container of this invention and manufacturing the easily openable container of the structure shown by FIG.2 and FIG.3, depending on the case, the inner peripheral edge of the annular seal disc | board 7 may be. In addition to the resin reservoir 6 formed in the portion corresponding to the contact position, the resin reservoir may be formed in the portion corresponding to the position where the outer peripheral edge of the seal board 7 contacts. Since the resin reservoir formed at the inner peripheral edge is larger than the resin reservoir formed at the outer peripheral edge, good easy-openability and high sealing performance are maintained.
In addition, the specific structure, shape, and the like in the implementation of the present invention may be other structures as long as the object of the present invention can be achieved.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not restrict | limited at all to description content, such as these Examples.

[Example 1-1 to Example 5, Comparative Example 1-1 to Comparative Example 5-2]
FIG. 12 is a schematic diagram illustrating measurement positions of the opening strength and the sealing strength performed in the examples and comparative examples.
(1) Manufacture of containers:
A laminate having a thickness of 600 μm composed of the following surface layer / surface lower layer / base material layer was formed by coextrusion molding.

(Container configuration)
As the surface layer and the front and lower layers, those described in Tables 1 and 2 were used.
Second base material layer (thickness): polypropylene (150 μm)
Second adhesive layer (thickness): adhesive resin (5 μm)
Gas barrier layer (thickness): ethylene vinyl alcohol (EVOH) (30 μm)
First adhesive layer (thickness): adhesive resin (5 μm)
First base material layer (thickness): polypropylene (300 μm)
Next, a container with a flange of 130 mm × 150 mm × 30 mm was formed by plug-assisted vacuum forming using this laminate. This container has a flange portion having a width of 15 mm with respect to the opening, and is formed in a substantially rectangular tray shape.
The multi-layer film having the following configuration is placed as a lid on the flange at the periphery of the opening of the container thus obtained, and the sealing conditions shown below are used. Using the annular sealing disc (seal ring) in which the inclined surface portion and the curved surface portion were formed on the entire circumference, the lid material was heat-sealed with respect to the flange of the container to produce the package of the present invention.
In addition, when the container and lid | cover material of this structure are used, the cohesive peeling which peeling will advance by the cohesive failure of the surface layer of a container will be performed at the time of opening.
(Composition of lid material)
Outer layer: Polyethylene terephthalate (PET) (12 μm)
Intermediate layer: polyamide (nylon, Ny) (15 μm)
Sealing layer: polyethylene (PE) (60 μm) or polypropylene (PP) (60 μm)
The order of the outer layer, the intermediate layer, and the sealing layer is PET / Ny / PE or PET / Ny / PP.

[Production Conditions for Examples 1-1 to 4 and Comparative Examples 1-1 to 4-2]
(Sealing conditions)
Sealing temperature: 200 ° C
Sealing pressure: 100 kg / piece Time: 1.0 seconds Number of heat seals: Once (specifications of the annular seal disc)
Seal width: 3mm
Inclination angle θ (inclined surface portion 71): 6 °
R processing (curved surface portion 72): 1.0 mmR
[Production conditions of Example 5 and Comparative Examples 5-1 and 5-2]
(Sealing conditions)
Sealing temperature: 200 ° C
Sealing pressure: 200kg / piece Time: 2.0 seconds Number of heat seals: Once (specifications of the annular seal disc)
Seal width: 3mm
Inclination angle θ (inclined surface portion 71): 6 °
R processing (curved surface portion 72): 1.0 mmR

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

(Seal strength)
As shown to FIG. 12B, the side part of the package 1 is cut | disconnected to 15 mm width, and it is set as a test sample, The said sample is outside (outer peripheral edge side of a flange part) from the inner side (opening part side of a container main body). Using an autograph tensile tester (in the direction of the arrow in FIG. 10B), the measurement was performed at 180 ° peeling under a condition of 300 mm / min. The test was performed with n = 8.

(Peel strength)
As shown to FIG. 12A, the corner (opening start part) of the package 1 is cut | disconnected to 15 mm width, and it is set as a test sample, The said sample is made into the inside (container main body side) from the outer side (outer peripheral edge side of a flange part). Using an autograph tensile tester (opening side) (in the direction of the arrow in FIG. 12A), measurement was performed at 135 ° peeling under a condition of 300 mm / min. The test was performed with n = 6.

(Opened appearance)
The contents of evaluation were evaluated in two stages: “◯” when no noticeable fuzz or lid tearing occurred after opening, and “X” when fuzz or lid tear occurred after opening.

(Heat-resistant)
The contents of the evaluation are “O” when not attached to a 170 ° C. heating plate assuming a hot plate contact heating method at the time of container molding, and “No” attached to a 170 ° C. heating plate but not attached to a 155 ° C. heating plate. [Delta] "The case of attaching to a heating plate at 155 [deg.] C. was evaluated in three stages, with" x ".

＊１：蓋材と強接着しており、剥離せず蓋材が破れる。
＊２：蓋材との接着が弱く、密封性なし。
＊３：蓋材との接着が弱く、密封性なし。耐熱性悪化。
＊４：性能良好だが、耐熱性悪化。
＊５：開封面が安定せず凝集破壊面が乱れ毛羽立ちが発生。
＊６：表面層および表下層の層間と凝集破壊面とにより毛羽立ち発生。
＊７：性能良好だが耐熱性悪化。

* 1: Strongly bonded to the lid material, and the lid material is torn without peeling.
* 2: Adhesion with the lid is weak and there is no sealing performance.
* 3: Adhesion with the lid is weak and there is no sealing performance. Heat resistance deteriorated.
* 4: Performance is good, but heat resistance deteriorates.
* 5: The opening surface is not stable, the cohesive failure surface is disturbed, and fluffing occurs.
* 6: Fluffing occurred due to the surface layer and the lower and upper interlayers and the cohesive failure surface.
* 7: Performance is good but heat resistance deteriorates.

As shown in Tables 1 and 2, in Examples 1-1 to 5, the sealing strength, peel strength, unsealed appearance, and heat resistance were judged comprehensively and were good.
On the other hand, in Comparative Examples 1-1 to 5-2, as shown in Table 2, the evaluation was “x” for at least one of seal strength, peel strength, unsealed appearance, and heat resistance.
Therefore, the content of PP, PP resin, PE resin and styrene polymer contained in the surface layer is specified, the content of PE in the front and lower layers is specified, and the thickness of the surface layer is specified. Thus, it was found that the adhesion (sealing) property, peel strength, opening feeling, appearance, and heat resistance are improved.

The easy-open container of the present invention has both high sealability and easy-openability, and provides an easy-open container that can be widely used as a packaging container for various foods such as retort foods, medicines, cosmetics, etc. To do.

Sectional drawing which shows the multilayer sheet of this embodiment. It is the figure which showed the easily openable container in 1st Embodiment of this invention, Comprising: (A) is the state sealed with the cover material, (B) is the schematic which shows the state which opened the cover material from the opening start part. . The fragmentary sectional view of the opening start part of the easily openable container in 1st Embodiment. The schematic diagram which showed the sealing process of the easily openable container in 1st Embodiment. The fragmentary sectional view which showed the state of the sealing board at the time of the heat seal in 1st Embodiment, and a flange part. The elements on larger scale of the annular seal disc | board in 1st Embodiment. The fragmentary sectional view which showed the state by which the easy-open container of 1st Embodiment was initially opened. The fragmentary sectional view which showed the state by which the easy-open container of 1st Embodiment was opened completely. The fragmentary sectional view which showed the state by which the easy-open container of 2nd Embodiment was initially opened. The fragmentary sectional view which showed the state by which the easy-open container of 2nd Embodiment was opened completely. Sectional drawing which shows the multilayer sheet of other embodiment. The schematic diagram which shows the measurement position of the unsealing strength and sealing strength which were implemented in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Easy-open packaging body 2 Container 3 Cover material 4 Opening start part 6 Resin pool part 7 Annular seal board 7a Other annular seal board 20 Multilayer sheet 21 Surface layer 22 Subsurface layer 23 Base material layer 23A 2nd base material Layer 23B Second adhesive layer 23C Gas barrier layer 23D First adhesive layer 23E First base material layer 24 Opening portion 25 Flange portion 26 Seal portion 261 7-formed seal portion 262 7a-formed seal portion 31 Seal Layer 32 Intermediate layer 33 Outer layer 61 21 Resin reservoir 62 22 Resin reservoir 63 31 Resin reservoir 71 Inclined surface portion 72 Curved portion 73, A Tip (boundary)
X Near the inner periphery of the seal

Claims (7)

A multilayer sheet comprising a surface layer and a surface layer laminated adjacent to the surface layer,
The thickness dimension of the surface layer is 1 μm to 200 μm,
The surface layer includes polypropylene, polypropylene resin, polyethylene resin, and styrene polymer,
The content of these polypropylene, polypropylene resin, polyethylene resin and styrene polymer is 60 wt% or more and 80 wt% or less, 1 wt% or more and 10 wt% or less, 8 wt% or more and 28 wt% or less, 4 wt% or more and 14 wt% or less,
The said lower layer contains a polyethylene-type resin, The content rate of this polyethylene-type resin is 5 wt% or more and 50 wt% or less. The multilayer sheet characterized by the above-mentioned. A multilayer sheet comprising a surface layer and a base material layer laminated adjacent to the surface layer,
The thickness dimension of the surface layer is 1 μm to 200 μm,
The surface layer includes polypropylene, polypropylene resin, polyethylene resin, and styrene polymer,
The content of these polypropylene, polypropylene resin, polyethylene resin and styrene polymer is 60 wt% or more and 80 wt% or less, 1 wt% or more and 10 wt% or less, 8 wt% or more and 28 wt% or less, 4 wt% or more and 14 wt% or less,
The said base material layer contains a polyethylene-type resin, The content rate of this polyethylene-type resin is 5 wt% or more and 50 wt% or less. The multilayer sheet characterized by the above-mentioned. The multilayer sheet according to claim 1 or 2,
A multilayer sheet characterized in that a dispersing agent is contained in the surface layer. The multilayer sheet according to any one of claims 1 to 3,
The multi-layer sheet, wherein the styrenic polymer is a styrene ethylene butene styrene block copolymer. A thermoformed container having an opening obtained by thermoforming the multilayer sheet according to any one of claims 1 to 4,
A thermoformed container, wherein a flange is formed around the opening. A container according to claim 5;
A lid material fused to close the opening of the container;
An easy-open packaging body characterized by comprising: The easy-open packaging body according to claim 6,
An easy-open packaging body, wherein a resin reservoir is formed in the vicinity of the opening of the flange.

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