JPH08295003A - Easily peelable coextrusion laminated film - Google Patents

Abstract

PURPOSE: To enable a laminated film to be easily peeled off smoothly by flocculation/separation of a heat sealed layer by laminating a first layer of blend polymer which falls under the range of specific weight ratio, blend percentage, thickness and flocculation/breakdown strength and a second layer of a similar composition with a higher flocculation/breakdown strength than the first layer, using a coextrusion method. CONSTITUTION: This coextrusion laminated film consists of a first layer of a blend polymer containing a polymer selected from among copolymers including an ethylene methylmethacrylate copolymer, a polymer such as polyethylene copolymer and an acid-modified polyolefin. The weight ratio of these polymers is within the range of 95:5 to 60:40 and the blend rate is 7 to 30wt.%. The thickness is 1 to 20mm and the flocculation/breakdown strength is within the range of 50 to 1000g/15mm. In addition, the film consists of a second layer whose blend polymer contains a polymer selected from among similar copolymers to the first layer and an ethylene propyrene copolymer. The weight ratio of these polymers is within the range of 10:90 to 45:55. The flocculation/ breakdown strength is at least, 1.5 times that of the first layer. These two layers are coextruded into a laminate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealing laminated film, and more specifically, it has a sealing property and an easy peeling property (easy-opening property), and can be uniformly and smoothly opened. The present invention relates to an easy-peel coextrusion laminated film capable of forming a heat-sealed portion which has a beautiful surface, is free from stringing and filming phenomena, has few pinholes, and has excellent impact resistance.

[0002]

2. Description of the Related Art In the field of food packaging and the like, a multilayer gas barrier packaging material having a heat-sealing layer having a good sealing property is used for protecting and storing contents. recent years,
For such packaging materials, there is a demand for satisfying the sealing property by heat sealing and easy peeling property for easy opening at the time of consumption. Various proposals have been made so far for packaging materials having both practical sealing properties and easy peeling properties.

For example, in JP-A-57-131556, a layer obtained by blending polyethylene or ethylene-vinyl acetate copolymer with polybutene-1 or a layer obtained by blending low-density polyethylene with polypropylene is used as a heat-sealing layer. There has been proposed a method for producing a polyolefin resin layer and an easy peelable easy peel film, which is obtained by co-extruding a processability improving resin layer.
In Japanese Patent Laid-Open No. 60-239238, a heat-seal layer formed by blending an ionomer with an ethylene / propylene copolymer is arranged as a seal layer of a laminate, and an easily openable seal is possible with an olefin resin as a seal partner. Various multi-layer packaging materials have been proposed. However, in these easy-peel packaging materials, the peeling surface becomes fibrous and rough when opened, and a threading phenomenon or a filming phenomenon (the material of the layer peels off into a film at the time of peeling) is generated. However, there is a problem in that the appearance of the sealing surface is remarkably deteriorated and the commercial value is impaired.

JP-A-62-109768 proposes an easily openable hermetic packaging material having a sealant layer which is a coextruded film of a polypropylene layer and a blend polymer layer containing polypropylene and having a thickness of 11 μm or less. However, in this packaging material, since the polypropylene layer has no adhesive force, interfacial peeling occurs between both layers at the time of opening, and uniform and smooth opening cannot be performed, and the appearance of the peeled surface is likely to be impaired.

In order to solve these problems, the inventor of the present invention has proposed a heat-sealable laminated film comprising at least two layers, wherein the first layer serving as a seal layer has an ethylene / methacrylic acid copolymer, ethylene. -At least one polymer selected from the group consisting of a methyl methacrylate copolymer, an ionomer, an ethylene / acrylic acid copolymer, an ethylene / ethyl acrylate copolymer, and an ethylene / methyl acrylate copolymer, and polyethylene, A layer containing a blend polymer with at least one polymer selected from the group consisting of polypropylene and an ethylene / propylene copolymer is arranged, and as a second layer adjacent to the first layer, an ethylene / methacrylic acid copolymer, Ethylene / methyl methacrylate copolymer, ionomer, ethylene / vinyl acetate copolymer, A layer containing at least one polymer selected from the group consisting of a ethylene / acrylic acid copolymer, an ethylene / ethyl acrylate copolymer, and an ethylene / methyl acrylate copolymer is arranged, and a first layer is provided. We proposed an easy-peel coextrusion laminated film in which the cohesive failure strength of the second layer was adjusted (Japanese Patent Laid-Open No. 5-2128).
No. 35). This easy-peel coextrusion laminated film has excellent sealing property and easy-peel property, can be uniformly and smoothly opened, and has a beautiful peeling surface at the time of opening, and does not cause a stringing phenomenon or a filming phenomenon. It has characteristics. However, a multi-layer laminated film substrate in which this easy-peelable co-extruded laminated film is arranged as a heat-sealing layer is deep-drawn into a container-shaped bottom material, and after filling the contents therein, the laminated film of the lid material. When heat-sealing with the (seal mating material) under vacuum forming, pinholes are generated in the flange corners (root parts) of the deep-drawn portion of the container, and as a result, the impact resistance of the product is insufficient. I knew it was.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to have a good sealing property with a seal mating material, to be able to easily open it without causing a stringing phenomenon, to give a good appearance of a peeled surface, and to make a deep surface. It is an object of the present invention to provide an easy-peel coextruded laminated film having excellent impact resistance without generating pinholes due to heat sealing even when it is drawn. Further, according to the present invention, not by interfacial peeling between the base film layer and the layer, but by cohesive peeling of the seal layer,
An object of the present invention is to provide an easy-peelable coextrusion laminated film that enables uniform and smooth easy peeling.

The inventors of the present invention proposed an ethylene-propylene copolymer in the polymer forming the second layer in the easy-peel coextrusion laminated film disclosed in JP-A-5-212835. By blending a large amount, the heat resistance of the second layer is improved, while the adhesiveness between the first layer and the first layer, which has been lowered by the inclusion of the ethylene / propylene copolymer in the second layer, is improved. By blending a certain amount of acid-modified polyolefin into the blend polymer of No. 1, there is no pinhole while maintaining excellent easy peeling, and as a result, easy peeling coextrusion lamination with excellent impact resistance. I found what I could get from the film.

This easy-peelable coextruded laminated film can be used as a packaging material having a multilayer laminated structure by, for example, coextruding or laminating with a multilayer film substrate having a gas barrier layer. By heat-sealing a deep-drawing container (bottom material) formed of the packaging material and a lid material having a heat-sealing layer, a packaging container having both sealing property and easy peeling property and excellent impact resistance can be obtained. can get. This easy-peelable coextrusion laminated film can also be used for the sealing layer of the lid material.

In the easy-peel coextrusion laminated film of the present invention, the cohesive failure strength (cohesive peel strength) of the first layer is kept low, and the interlayer adhesion with the second layer (peeling strength) is strong. Moreover, the thickness of the first layer is extremely thin. Therefore, at the time of opening, not the interfacial peeling between the first layer and the second layer but mainly the cohesive peeling at the first layer, which enables smooth and stable easy peeling, and the peeled surface has a thin film. The phenomenon does not occur, and it does not become a fiber and the threading phenomenon does not occur. Moreover, since a specific polymer is used as the material of the seal layer, the sealing property is also good. The present invention has been completed based on these findings.

[0010]

Thus, according to the present invention, a heat-sealable laminated film comprising at least two layers, wherein (a) the first layer to be the sealing layer is an ethylene / methacrylic acid copolymer. , An ethylene / methyl methacrylate copolymer, an ionomer, an ethylene / acrylic acid copolymer, an ethylene / ethyl acrylate copolymer, and an ethylene / methyl acrylate copolymer (at least one polymer (S ₁ ), at least one polymer (S ₂ ) selected from the group consisting of polyethylene, polypropylene, and an ethylene / propylene copolymer,
And a layer of a blended polymer comprising an acid-modified polyolefin (S ₃ ) and the polymer S in the blended polymer.
The weight ratio of ₁ to the polymer S ₂ (S ₁ : S ₂ ) is 95: 5-6.
Within the range of 0:40, the compounding ratio of the acid-modified polyolefin S ₃ is 7 to 30% by weight, and the thickness of the first layer is 1 to 2
At 0 μm, the cohesive failure strength is 50 to 1,000 g / 1
Within the range of 5 mm width,

(B) The second layer adjacent to the first layer has an ethylene / methacrylic acid copolymer, an ethylene / methyl methacrylate copolymer, an ionomer, an ethylene / vinyl acetate copolymer, an ethylene / acrylic acid copolymer. A blend containing at least one polymer (M ₁ ) selected from the group consisting of a polymer, an ethylene / ethyl acrylate copolymer and an ethylene / methyl acrylate copolymer, and an ethylene / propylene copolymer (M ₂ ). A layer of polymer, wherein the weight ratio (M ₁ : M ₂ ) of polymer M ₁ and polymer M ₂ in the blended polymer is in the range of 10:90 to 45:55,
The cohesive failure strength of the second layer is 1.
It is 5 times or more, and (c) at least 1st layer and 2nd layer are laminated | stacked by coextrusion, The easy peeling coextrusion laminated | multilayer film is provided.

The present invention will be described in detail below. First, the problems and solutions of the present invention will be described in more detail with reference to the drawings. Japanese Patent Application Laid-Open No. 5-2 related to the proposal of the present inventor
The laminated film substrate on which the easy-peelable coextruded laminated film described in 12835 is arranged is deep-drawn to obtain a cylindrical container 1 as shown in the cross section in FIG.
In this container (bottom material) 1, contents (for example, ham) 3
And the container 1 and the sealing partner material (lid material) 2 are heat-sealed. The shape and size of the container are slightly larger than the contents 3 in order to automatically fill the contents.
For example, when automatically filling circular sliced ham,
Usually, the diameter of the container is made larger than the diameter of the ham by about several mm. A sealant layer is arranged on the sealing surface of the container 1.

After the container 1 (bottom material) is filled with the contents, the container material 2 is covered and heated in a vacuum state for heat sealing.
At that time, because of the difference in diameter between the container and the contents, as shown in FIG. 2, a large number of vertical wrinkles 4 are generated in the deep drawn portion of the bottom material 1 (side surface of the cylindrical container). There are cases. Pinholes are easily generated in the flange corner portions (root portions) 5 of the vertical wrinkles 4. FIG. 3 shows an enlarged sectional view of the flange corner portion 5 of the vertical wrinkle 4. In FIG. 3, a sealant layer 6 made of an easy-peelable coextruded laminated film is arranged as an inner layer of the laminated film base material that forms the container 1. By heating during heat sealing under vacuum forming, the sealant layer is melted and stretched, and the sealant layer 7 of the flange corner portion 5 becomes thin, which causes pinholes. At the flange corner portion 5 where the sealant layer 6 is thin, delamination from other layers is likely to occur. In addition, the product in such a state is inferior in impact resistance, and the seal portion is likely to be peeled off or broken due to an impact of dropping or the like.

In the present invention, the second layer of the sealant layer is provided with a blend polymer layer having an ethylene / propylene copolymer in a predominant amount to improve heat resistance as compared with the first layer.
This improves the phenomenon that the second layer is melted and stretched at the time of heat sealing, and is stretched and thinned. That is, instead of the conventional polymer layer having low heat resistance such as ethylene / vinyl acetate copolymer (EVA) as the second layer, a blend polymer layer in which the ethylene / propylene copolymer having good heat resistance serves as a matrix is used. Deploy. However, when the second layer is formed of a blend polymer in which the ethylene / propylene copolymer is in a predominant amount, the adhesiveness between the first layer and the second layer is lowered, and the interlayer between the two layers is opened at the time of opening. Peel off,
The easy peeling property and the appearance of the peeled surface are impaired. In order to solve this problem, the present invention further improves the adhesion between the first layer and the second layer by blending a specific amount of the acid-modified polyolefin in the polymer blend forming the first layer. .

In the present invention, by devising the polymer component forming the first layer and the second layer and the mixing ratio thereof,
As shown in FIG. 4, it is possible to obtain an easy-peel coextrusion laminated film in which the sealant layer 7 at the flange corner portion does not extend and become thin, and a packaged product using the same. The sealant layer comprising the easy-peelable coextruded laminated film of the present invention has a smooth and stable easy-peel because the first layer and the second layer do not undergo delamination at the time of opening and cohesive delamination occurs in the first layer. It is possible.

(First Layer) In the easy-peelable coextruded laminated film of the present invention, the first layer serving as a sealing layer is an ethylene / methacrylic acid copolymer (EMAA) or an ethylene / methyl methacrylate copolymer (EMMA). ), Ionomer (IO), ethylene / acrylic acid copolymer (EA
A), ethylene-ethyl acrylate copolymer (EEA)
And at least one polymer (S ₁ ) selected from the group consisting of ethylene-methyl acrylate copolymer (EMA), polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymer (Et-P).
A layer containing a blend polymer of at least one polymer (S ₂ ) selected from the group consisting of P) and an acid-modified polyolefin (S ₃ ).

In order to secure the sealing property by heat sealing, the polymer forming the sealing layer needs to have excellent heat sealing property. On the other hand, in order to exhibit a stable easy peel property, the cohesive failure strength of the first layer must be reduced to such an extent that opening can be facilitated. Therefore, in the present invention, as the matrix polymer of the first layer, using the polymer S _1, and, in order to express the easy peel properties, this polymer S ₁
A specific polymer S ₂ which is incompatible with the above is blended to adjust the cohesive failure strength. Further, in the present invention, in order to improve the interlayer adhesion with the second layer, the acid-modified polyolefin S ₃ is blended with the polymer blend of the first layer. The blend ratio of the polymer S _{2 to} the polymer S ₁ (S ₁ : S ₂ ) is usually 95: 5-6 by weight.
It is in the range of 0:40, preferably 90:10 to 65:35. If the proportion of the polymer S ₂ is too large, the sealing property will be deteriorated, while if it is too small, it will be difficult to reduce the cohesive failure strength.

The blending ratio of the acid-modified polyolefin S _{3 in} the blend polymer forming the first layer is 7 to 30% by weight, preferably 10 to 25% by weight. If the blending ratio of the acid-modified polyolefin is less than 7% by weight, the first layer and the second layer are delaminated during opening, so that uniform and smooth easy peeling property is deteriorated. If the compounding ratio of the acid-modified polyolefin exceeds 30% by weight, the adhesiveness of the first layer becomes too large, and the easy peeling property with the sealing partner material (lid material) is impaired. Examples of the acid-modified polyolefin include maleic acid-modified polypropylene, maleic acid-modified ultra-low density polyethylene, maleic acid-modified ethylene / vinyl acetate copolymer, carboxylic acid-modified polypropylene, and carboxylic acid-modified polyethylene.

The cohesive failure strength of the polymer blend layer of the first layer is 50 to 1,000 g / 15 mm width, preferably 100 to 700 g / 15 mm width. The cohesive failure strength is a value obtained by a measuring method (described later) based on ASTM D903-49, and has a correlation with the cohesive force of the material. If the cohesive failure strength of the first layer exceeds 1,000 g / 15 mm width, the easy peeling property deteriorates, and conversely, if it is less than 50 g / 15 mm width, the seal portion is likely to peel off due to impact or the like.

For easy opening, the peel strength is generally 100 to 300 g / 15 mm width in the case of a face seal having a large seal area, and the peel strength is generally in the case of a line seal having a small seal area. Preferably 500g / 15m
It is practical to set the width to about m. Since the easy-peel coextrusion laminated film of the present invention is peeled off by cohesive peeling of the first layer at the time of opening, the cohesive fracture strength of the seal portion is adjusted by adjusting the cohesive fracture strength according to the shape, area, etc. of the seal surface. The peel strength can be set to a desired value. First
The layer thickness is in the range of 1 to 20 μm, preferably 5 to 15 μm. If the thickness of the first layer exceeds 20 μm, a stringing phenomenon is likely to occur at the time of opening, which is not preferable.
On the other hand, when the thickness of the first layer is less than 1 μm, the expression of the easy peel property may be impaired.

(Second Layer) The second layer is provided directly adjacent to the first layer by a coextrusion method without an adhesive. Second
One of the blend polymers forming the layer (polymer M ₁ )
In order to enhance the interlayer adhesion with the first layer,
It is preferable to use a material having substantially the same material as the matrix polymer S _{1 of the} layer. That is, the polymer M ₁
As the polymer, at least one polymer selected from the group consisting of EMAA, EMMA, IO, ethylene / vinyl acetate copolymer (EVA), EAA, EEA and EMA is used. In the present invention, in order to improve the heat resistance of the second layer, an ethylene / propylene copolymer is used as the other component (polymer M ₂ ) of the blend polymer forming the second layer. As the ethylene / propylene copolymer, one having an ethylene content of about 3 to 7% by weight is usually preferable.

The weight ratio (M ₁ : M ₂ ) of the polymer M ₁ and the polymer M ₂ in the blended polymer forming the second layer is 1
0:90 to 45:55, preferably 15:85 to 40:
60, more preferably 20:80 to 40:60.
If the blending ratio of the ethylene / propylene copolymer (polymer M ₂ ) is less than 55% by weight, the polypropylene component is less likely to form a matrix in the blend polymer, so that the heat resistance improving effect is small and the thinning phenomenon during sealing occurs. Cannot be suppressed sufficiently. When the blending ratio of the ethylene / propylene copolymer (polymer M ₂ ) exceeds 90% by weight, the transparency, processability and fluidity are deteriorated, and the film tends to curl. A reduction in the cuttability of the film also occurs.

The cohesive failure strength of the second layer must be 1.5 times or more the cohesive failure strength of the first layer. It is preferably 3 times or more, more preferably 5 times or more. When the cohesive failure strength of the second layer is less than 1.5 times the cohesive failure strength of the first layer, the cohesive failure of the first layer at the time of opening is propagated to the second layer, which impairs smooth opening. In addition, the stringing phenomenon is likely to occur. Further, if the cohesive failure strength of the second layer is too small, the seal portion is likely to peel off due to impact. The thickness of the second layer is usually 5 to 500 μm, preferably 10 to 200.
μm, and more preferably 50 to 100 μm.

(Easy peeling coextrusion laminated film)
The easy peelable coextrusion laminated film of the present invention includes at least the first layer and the second layer. The first layer and the second layer are laminated by coextrusion. The first layer serves as a seal layer and thus constitutes the outermost layer. If desired, various layers can be laminated on the opposite surface of the second layer. To form the blended polymer layer, powders or pellets may be dry blended to form a blend and used to coextrude.

The easy-peel coextrusion laminated film of the present invention can be laminated with a base film to be used as a lid material or a bottom material of a package. As the substrate film, a laminate including a gas barrier resin layer, a reinforcing layer provided as necessary, and an adhesive layer for adhesion between layers is usually used. These base films are the first layer and the second layer.
Coextrusion with the layers can be a component of an easy peel coextruded laminated film. Alternatively, both may be laminated after film formation. The method for laminating the laminated film of the first layer and the second layer and the base film is not particularly limited.

As the gas barrier resin layer, for example,
Polyvinylidene chloride (PVDC), saponified ethylene / vinyl acetate copolymer (EVOH), polyvinyl alcohol, polyamide, polyester, nitrile resin, PV
A film selected from a film such as DC latex-coated cellophane, a coating sheet, and a plate, or a resin layer containing an aluminum foil, a metal deposition film, or the like may be used.
As the reinforcing layer, those having a reinforcing property among the gas barrier resin layers are used, but in addition, polyvinyl chloride (PVC), polystyrene, polycarbonate, polyolefin and the like are preferable. If a nylon layer such as nylon 6 or nylon 66 is introduced as a reinforcing layer,
The impact resistance is further improved, and the occurrence of pinholes is further reduced. The thickness of the nylon layer is usually 1 to 10
If the thickness is too large, the drawability will be poor and the cost will increase, and if it is too thin, the reinforcing effect will be small. As the adhesive, for example, an ethylene / vinyl acetate copolymer, a chlorinated polyethylene, an unsaturated carboxylic acid graft product of an ethylene copolymer, or the like is used as necessary.

The easy-peel coextrusion laminated film of the present invention is provided with an easy-peel function that can be easily opened from the seal portion in a package composed of a lid material and a bottom material. The material of the layer to be sealed that forms the sealing surface of the sealing partner may be any material that can be heat-sealed, and among them, EMAA, EMMA, IO and EVA.
Is preferable, and IO and EVA are particularly preferable. The thickness of the layer to be sealed is usually 20 to 70 μm, preferably 30.
-60 μm. The sealing partner is usually a sealing layer,
It has a gas barrier resin layer and a reinforcing layer.

The packaging material containing the easy-peelable coextruded laminated film of the present invention is suitable for packaging, for example, in which meat, sliced ham, etc. are placed in a deep-drawing container and covered with a lid to heat seal the peripheral portion of the container. is there. The easy-peel coextrusion laminated film of the present invention can be uniformly and smoothly opened because the first layer cohesively breaks and peels off when opened, and is free from stringing phenomenon, filming phenomenon, etc. It becomes the peeling surface. Especially, the seal layer of the seal partner is IO
And EVA, the polymer S ₁ in the blend polymer forming the first layer is an ethylene / methacrylic acid copolymer and the polymer S ₂ is an ethylene / propylene copolymer to form the second layer. It is preferable to use an easy peeling coextrusion laminated film in which the polymer M ₁ in the blended polymer is an ethylene / methacrylic acid copolymer or an ethylene / vinyl acetate copolymer. A packaged product using the easy-peel coextrusion laminated film of the present invention has excellent impact resistance and few pinholes.

[0029]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The methods for measuring physical properties are as follows.

<Impact resistance (% of bag breakage)> The sealed packages prepared in Examples and Comparative Examples are put in a box having a regular hexagonal cross section shown in FIG. 5 and rotated at 30 rpm. The box 8 shown in FIG. 5 is provided with three shelves 9 inside and can be rotated by a rotating shaft 10 connected to a driving means. When this box 8 makes one rotation, the presence of the shelves 9 causes a drop of 20 cm three times, and when it is rotated for 5 minutes, it makes a total of 450 drops. A cold shock resistance test was performed by placing 40 sealed packages in this box and rotating them at 5 ° C. for 30 minutes. The number (%) of bag breakages was counted and the rate (%) was calculated. Incidentally, in most of the crushed packages, pinholes were formed in the vertical wrinkle flange corners on the cylindrical side of the package.

<Cohesive failure strength> The cohesive failure strength of the first and second layers in the present invention was measured by the following method. That is, 5 layers of material whose cohesive fracture strength is to be measured
0 μm surface layer, adhesive layer (15 μm), PVC layer (1
A 50 μm) coextruded laminated film was prepared. PVC
As the adhesive, an unsaturated carboxylic acid modified product of an ethylene / vinyl acetate copolymer (Showa Denko, trade name Show Allomer) was used as the adhesive. . The surface layers of this laminated film were overlapped with each other, and a film piece having a width of 60 mm and a length of 100 mm was cut out. This film piece was heat-sealed under the conditions of 160 ° C., 3 kg / cm ² G, and 1 second, leaving 40 mm in the lengthwise end. Then, from this film piece, width 15 mm ×
Length 40 mm (30 mm is the heat-sealed portion, 10 mm
Cut the test piece of the part that is not heat-sealed)
The cohesive failure strength of the material to be measured was determined by the measuring method based on D903-49. Further, the cross-sections of the heat-sealed surface layers were observed by an electron microscope, but the surface layers were completely welded and no boundary surface was observed. Further, the surface of the layer peeled off by cohesive failure was rough as observed by an electron microscope, and it was confirmed that cohesive failure had occurred.

<Peeling strength of seal part> The peeling strength of the seal part is the same as the sample for measuring cohesive failure strength.
Tensile tester (Toyo Baldwin, trade name UTM-
(Type III tensilon), and the tensile speed was 200 mm / min.

<Peelability> The sealed packages prepared in Examples and Comparative Examples were opened, and the peelability was evaluated according to the following criteria. A: There is no stringing phenomenon and the peeled surface is beautiful. : It can be easily opened, but there is some stringing phenomenon, or the peeled surface is slightly rough. X: There is a stringing phenomenon and the peeled surface is rough.

Examples 1 and 2, Comparative Examples 1 to 5 As shown in Table 1, blend polymers for the first layer and the second layer were prepared using the following materials. Bottom laminated multilayer film,
The materials constituting the multilayer laminated film of the lid material are also shown below. (1) EMAA: Dupont Mitsui, Nucrel, methacrylic acid content 9% by weight (2) EP (Et-PP): Sumitomo Chemical, Nobrene F
M321, ethylene content 5% by weight, melting point 142 ° C. (3) MO: maleic acid modified polypropylene, Mitsubishi Petrochemical, Modic P-300M (4) EVA: Sumitomo Chemical Co., Ltd. EvaTate D-201
1, melting point 103 ° C. (5) Adhesive: Modified unsaturated carboxylic acid of ethylene / vinyl acetate copolymer, Admer SF-7 manufactured by Mitsui Petrochemical Co., Ltd.
05 (6) EVOH: made by Kuraray, Eval EP-K (7) PET: copolyester (made by Eastman Chemical, KODAR PETG6763; copolymer of terephthalic acid and ethylene glycol, cyclohexanedimethanol) (8) lid material: A laminate in which the sealant is EVA and PVDC is latex-coated with cellophane laminated with PP.

As shown in Table 1, EMAA, EP and MO
The blended polymer of the first layer was prepared by variously changing the blending ratio of. Further, the blend ratio of EVA and EP was variously changed to prepare the second layer blend polymer.
Then, the seal layer (first layer) / second layer / adhesive layer / EVO
A laminated film was prepared by coextrusion with a laminated structure of H / adhesive layer / PET. Co-extrusion uses each component with a diameter of 45 m
m, L / D ratio of 28 was used to feed the coextrusion die. The thickness of each layer is shown in Table 1.

Using this laminated film as a bottom material, a cylindrical container (1 was prepared by using a deep drawing machine (Omori Machine Co., Ltd., FV603).
00 mmφ × 15 mm depth) was molded. The sealing width of this container was 50 to 100 mm so that surface sealing was possible. This container was filled with sliced ham, and a lid material having the laminated constitution shown in Table 1 was heat-sealed to prepare a hermetically sealed package. Heat seal is 130 ℃, 5kg / c
It was carried out under the conditions of m ² and 1.5 seconds. The clearance between the cylindrical container and the ham was 2 mm. Using each of the obtained sealed packages, the impact resistance, the cohesive failure strength of the bottom material (first layer and second layer), the peel strength of the seal portion (in the case of face seal), and the peeling property were measured. The results are collectively shown in Table 1.

[0037]

[Table 1] (* 1) Peeling occurred between the first layer and the second layer of the bottom material (laminated film).

[Examples 3 to 5 and Comparative Examples 6 to 7] As shown in Table 2, the blending ratio of MO in the first layer was changed, and a nylon layer was added to the bottom material as a reinforcing layer. A sealed package was prepared in the same manner as in Examples 1 and 2 except that the materials and laminated constitution shown in Table 2 were adopted. The evaluation results are collectively shown in Table 2. The polymers used are as follows. (1) Nylon: Nylon 6, Toray-made Amilan CM
1021 (2) PVC: manufactured by Kureha Chemical Co., Ltd., polymerization degree 720

[0039]

[Table 2]

(* 1) Peeling occurred between the first layer and the second layer of the bottom material (laminated film). (* 2) There is no easy peeling property with the lid material.

[0041]

EFFECTS OF THE INVENTION According to the present invention, the sealability with the sealing partner material is good, and it can be easily opened without causing a stringing phenomenon or a filming phenomenon, and the peeled surface has a good-looking easy peeling property. A coextruded laminated film is provided.
Further, according to the present invention, there is provided an easy-peel coextrusion laminated film that enables uniform and smooth easy peeling by cohesive peeling of the seal layer. Further, according to the present invention, there is provided an easy-peel coextrusion laminated film capable of forming a heat-sealed portion having few pinholes and excellent impact resistance. When the easy-peel coextrusion laminated film of the present invention is used, the stringing phenomenon on the release surface and the rough feeling due to fiberization are reduced, the appearance of the sealing surface becomes beautiful, and the commercial value can be improved. A deep drawn container is created using a laminated body in which a gas barrier layer is laminated on this laminated film, foods such as meat and sliced ham are put into this, covered with a lid material and heat-sealed around the container, it is sealed. It is possible to obtain a product that satisfies the requirements and has an easy peel property that can be easily opened at the time of consumption. This package has excellent impact resistance.

[Brief description of drawings]

FIG. 1 is a drawing showing a laminated film in which an easy-peelable coextruded laminated film described in JP-A-5-212835 is arranged, is formed into a cylindrical container by deep drawing, filled with contents, and then covered. It is sectional drawing which shows preparation of the hermetically sealed package body which seals with a material.

FIG. 2 is a schematic view showing the appearance of the hermetically sealed package, showing that vertical wrinkles occur during heat sealing.

FIG. 3 is a cross-sectional view showing that the sealant layer in the flange corner portion of the vertical wrinkle extends and becomes thinner.

FIG. 4 is a cross-sectional view showing that the sealant layer at the flange corner portion of the vertical wrinkles does not extend and become thin when the laminated film having the easy peelable coextruded laminated film of the present invention is used.

FIG. 5 is a schematic diagram showing an apparatus for measuring the impact resistance of a hermetically sealed package.

[Explanation of symbols]

1: Cylindrical container formed by deep drawing 2: Sealing material (lid material) 3: Content (for example, ham) 4: Vertical wrinkle 5: Vertical wrinkle flange corner portion (root portion) 6: Sealant layer 7: Flange corner part (root part) of sealant layer 8: Box with regular hexahedron cross section 9: Shelf 10: Rotating shaft

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area // B29L 9:00

Claims (4)

[Claims] 1. A heat-sealable laminated film comprising at least two layers, wherein the (a) sealing layer has a first layer, which is an ethylene / methacrylic acid copolymer, an ethylene / methyl methacrylate copolymer, an ionomer, At least one polymer (S ₁ ) selected from the group consisting of ethylene / acrylic acid copolymer, ethylene / ethyl acrylate copolymer, and ethylene / methyl acrylate copolymer, polyethylene, polypropylene, and ethylene / propylene copolymer A layer of a blend polymer containing at least one polymer (S ₂ ) selected from the group consisting of a polymer and an acid-modified polyolefin (S ₃ ), the weight of the polymer S ₁ and the polymer S ₂ in the blend polymer The ratio (S ₁ : S ₂ ) is 9
Within the range of 5: 5 to 60:40, the mixing ratio of the acid-modified polyolefin S ₃ is 7 to 30% by weight, the thickness of the first layer is 1 to 20 μm, and the cohesive failure strength thereof is 50 to 1, 0
(B) the second layer adjacent to the first layer has an ethylene / methacrylic acid copolymer, an ethylene / methyl methacrylate copolymer, an ionomer, an ethylene / vinyl acetate copolymer. At least one polymer (M ₁ ) selected from the group consisting of a polymer, an ethylene / acrylic acid copolymer, an ethylene / ethyl acrylate copolymer, and an ethylene / methyl acrylate copolymer, and an ethylene / propylene copolymer ( M ₂ ) and a layer of a blended polymer, the polymer M in the blended polymer
The weight ratio (M ₁ : M ₂ ) of ₁ to the polymer M ₂ is from 10:90.
Within the range of 45:55, the cohesive failure strength of the second layer is the first.
Greater than 1.5 times the cohesive failure strength of the layer, and (c)
At least 1st layer and 2nd layer are what was laminated | stacked by coextrusion, The easy peeling coextrusion laminated | multilayer film characterized by the above-mentioned. 2. The easy-peel coextrusion laminated film according to claim 1, wherein the first layer has a thickness of 5 to 15 μm and the second layer has a thickness of 50 to 100 μm. 3. The easy-peel coextrusion laminated film according to claim 1, wherein the cohesive failure strength of the second layer is 3 times or more the cohesive failure strength of the first layer. 4. The blended polymer forming the second layer, wherein the polymer S ₁ in the blended polymer forming the first layer is an ethylene / methacrylic acid copolymer and the polymer S ₂ is an ethylene / propylene copolymer. 4. The easy-peelable coextrusion laminated film according to any one of claims 1 to 3, wherein the polymer M ₁ is an ethylene / methacrylic acid copolymer or an ethylene / vinyl acetate copolymer.