JP4860169B2 - Easy-open coextruded film, lid using the film, and deep-drawn container - Google Patents

Description

  The present invention relates to an easy-open coextruded film, a lid using the film, and a deep-drawn container, and in particular, has good easy peel properties for a bottom material for a deep-drawn molded gas pack having a polypropylene resin as a sealant. The present invention relates to an easy-open coextruded film having a high barrier property, a lid using the film, and a deep-drawn container.

  In recent years, lids for food containers with easy peel properties have been developed as lids used for food packaging containers in consideration of openability. However, in the conventional lid material, in order to realize easy peel properties, oxygen barrier properties, puncture strength, and the like, the lid material is formed by laminating separate films having respective properties.

  For example, a stretched nylon (hereinafter sometimes referred to as “ONy”) layer, an ethylene vinyl acetate copolymer saponified resin (hereinafter sometimes referred to as “EVOH”) layer, and an easy peel layer (hereinafter referred to as “EP”). Layered) (ONy layer // EVOH layer // EP layer) were used as the lid material (where “//” is a dry laminate) The same shall apply hereinafter.)

  In such a conventional lid, it was difficult to make the thickness of the EVOH film 12 μm or less from the viewpoint of the film property of the film. Therefore, from the viewpoint of providing oxygen barrier properties, the thickness of the EVOH layer that imparts oxygen barrier properties needs to be increased more than necessary, resulting in an increase in cost. Moreover, in such a conventional lid material, since it was necessary to laminate at least twice, there was a problem that productivity was low and cost was high.

  In addition, since the EVOH layer and the EP layer are dry-laminated in the cover material, the residual solvent used in the dry-lamination passes through an easy peel material having a low barrier property and moves to the food, which is the content, to absorb the odor. There was a possibility that the contents could be contaminated by deteriorating the flavor.

  In addition, among conventional lid materials, lid materials using polypropylene resin as a sealant have a high sealing temperature and are inferior in contaminant sealing performance. On the other hand, when a hot-melt type resin with improved low-temperature sealability is used in the heat seal layer of the lid material, there is a problem that hot tackiness is poor and delamination occurs when stress is applied immediately after sealing. Further, when hot water treatment such as high-temperature pressure sterilization treatment is performed after packing, there is a problem that whitening or delamination occurs.

Further, Patent Document 1 discloses that ONy layer // EVOH layer / Ny layer / adhesive layer / PP layer / EP layer (“/” indicates lamination by coextrusion method) as a laminate by coextrusion molding instead of dry lamination. In the following description, an easily-openable coextruded composite film having a layer structure is described. However, since EVOH absorbs moisture during the high-temperature sterilization treatment and plasticizes, ONy shrinks. There was a problem that delamination occurred between the layer and the EVOH layer.
Japanese Patent Laid-Open No. 11-34245

  The present invention has been made to solve the above-mentioned problems of the prior art, and the object of the present invention is to combine excellent oxygen barrier properties, easy peel properties and heat resistance, and particularly hot water such as high-temperature sterilization treatment. After processing, whitening and delamination do not occur, contaminant sealability and hot tackiness are good, the problem of high cost due to the lamination of each layer by dry lamination, when used as a deep drawn container, etc. An object of the present invention is to provide an easy-open coextruded film that does not cause the problem of contamination of the contents by the residual solvent.

  Another object of the present invention is to provide a lid material using the easy-open coextruded film and a deep-drawn container using the lid material.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The first present invention comprises a heat-resistant ethylene-vinyl acetate copolymer saponified resin layer (A layer) (10), a polyamide resin layer (B layer) (20), an adhesive resin layer (C layer) (30), Polypropylene resin layer (D layer) (40), resin layer (E layer) (50) composed of a mixture of a linear low density polyethylene resin and an amorphous or ethylene-α-olefin copolymer having a crystallinity of 15% or less And a resin layer (F layer) (60) made of a polypropylene resin obtained by using an ethylene-propylene random copolymer and / or a metallocene catalyst, and an easy-open coextrusion characterized by comprising It is a film (100).

The easy-open coextruded film preferably has a layer structure (100a to 100d) selected from the following (1) to (4).
(1) A layer (10) / B layer (20) / C layer (30) / D layer (40) / E layer (50) / F layer (60)
(2) A layer (10) / B layer (20) / C layer (30) / F layer (60) / E layer (50) / D layer (40)
(3) B layer (20) / A layer (10) / C layer (30) / D layer (40) / E layer (50) / F layer (60)
(4) B layer (20) / A layer (10) / C layer (30) / F layer (60) / E layer (50) / D layer (40)

  In the easy-open coextruded film (100), the polyamide resin of the layer B (20) is 6 nylon, 6-66 copolymer nylon, or a mixture of 6 nylon and 6-66 copolymer nylon. Is preferred.

  In the easy-open coextruded film (100), the polypropylene resin of the D layer (40) is preferably a propylene homopolymer or a random copolymer of ethylene and propylene.

  In the easy-open coextruded film (100), at least one layer selected from the D layer (40), the E layer (50) and the F layer (60) preferably contains an antifogging agent. .

  In the easy-open coextruded film (100), the total thickness of the E layer (50) and the F layer (60) is preferably 2 μm or more and 20 μm or less.

  In said easily openable coextrusion film (100), between two layers chosen from said A layer (10), B layer (20), C layer (30), D layer (40), and F layer (60) It is preferable that the interlayer adhesive strength is 5.88 N / 15 mm width or more and 15 N / 15 mm width or less.

  In the easy-open coextruded film (100), the easy peel strength between the D layer (60) and the E layer (50) is in the range of 2.97 N / 15 mm width to 14.7 N / 15 mm width. And the easy peel strength between the two layers selected from the A layer (10), B layer (20), C layer (30), D layer (40) and F layer (60) It is preferable that the strength is smaller.

  Said easy-open coextruded film (100) is printed or plain biaxially stretched polyethylene terephthalate film (OPET) or biaxially stretched on said outermost layer A layer (10) or B layer (20) A film (200, 300) further having a polypropylene film (OPP) (70, 80) is preferred.

The easy-open coextruded film (100) is measured according to JIS K7126 when sterilized under conditions of 100 ° C. or higher and 125 ° C. or lower and 5 minutes or longer and 120 minutes or shorter, and then left to stand for 3 days. The oxygen permeability is preferably 100 ml / m ² · day · MPa or less.

  Said easy-open coextrusion film (100) is 100 degreeC or more and 125 degrees C or less, and after sterilizing under the conditions of 5 minutes or more and 120 minutes or less, it is the said D layer and E layer when left still for 3 days The easy peel strength between them is in the range of 2.97 N / 15 mm width to 14.7 N / 15 mm width, and an interlayer between two layers selected from the A layer, B layer, C layer, D layer and F layer It is preferable that the adhesive strength is smaller.

  2nd this invention is a lid | cover material formed with said easily openable coextruded film (100, 200, 300).

  The third aspect of the present invention is a deep-drawn container using the above lid material.

  The molded container has a haze value of a seal part measured according to JIS K7105 when sterilized under conditions of 100 ° C to 125 ° C for 5 minutes to 120 minutes and then left to stand for 3 days. The difference from the haze value before the sterilization treatment is preferably 10% or less.

  The easy-open coextruded film of the present invention having the above layer structure has excellent oxygen barrier properties, easy peel properties and heat resistance, and particularly causes whitening and delamination even after hydrothermal treatment such as high-temperature sterilization treatment. Therefore, the film is excellent in transparency and has a high easy barrier property against the bottom material having a sealing layer made of a PP layer, and has a good easy peel property. In addition, the easy-open coextruded film of the present invention has good foreign matter sealability and hot tackiness, a problem of high cost due to lamination of each layer by dry lamination, residual when used as a deep drawn container, etc. It is a film that does not cause the problem of contamination of the contents by the solvent.

  Moreover, since the lid | cover material and deep drawing molded container of this invention consist of the easily openable coextruded film of this invention, they can exhibit the outstanding performance of an above-described easily openable coextruded film.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
Hereinafter, the easy-open coextruded film of the present invention, the lid material using the film, and the deep-drawn container will be described in more detail.

  In FIG. 1 (a)-(d), the layer structure in 1st-4th embodiment of the easy-open coextruded film of this invention was shown typically. The easy-open coextruded film (100a to 100d) of the present invention comprises a heat-resistant ethylene-vinyl acetate copolymer saponified resin layer (A layer) 10, a polyamide resin layer (B layer) 20, an adhesive resin layer (C layer). ) 30, polypropylene resin layer (D layer) 40, resin layer (E layer) 50 comprising a mixture of a linear low-density polyethylene resin and an amorphous or ethylene-α-olefin copolymer having a crystallinity of 15% or less. And a resin layer (F layer) 60 made of a polypropylene resin obtained by using an ethylene-propylene random copolymer and / or a metallocene catalyst.

<Heat-resistant ethylene-vinyl acetate copolymer saponified resin layer (A layer) 10>
The A layer 10 is a layer made of a heat-resistant ethylene-vinyl acetate copolymer saponified resin (hereinafter sometimes abbreviated as “hrEVOH”). hrEVOH is EVOH having heat resistance that can prevent whitening of the film when the film is subjected to high-temperature sterilization treatment, unlike the commonly used ethylene-vinyl acetate copolymer saponified resin (EVOH). As hrEVOH, for example, those described in JP-A-4-304253, JP-A-6-345919 and the like that can improve hot water resistance and prevent whitening of the film after high-temperature sterilization treatment can be used. It is preferable to use it.

  The A layer 10 has a role of imparting oxygen barrier properties to the coextruded film 100. The thickness of the A layer 10 can be appropriately set according to the required oxygen barrier property, and is preferably 5 μm or more, more preferably 7 μm or more, and further preferably 8 μm or more. On the other hand, the upper limit of the thickness of the A layer 10 is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less, from the viewpoint of ensuring good moldability.

<Polyamide resin layer (B layer) 20>
The B layer 20 is a layer made of a polyamide resin (hereinafter sometimes abbreviated as “PA”). Since the easy-open coextruded film 100 of the present invention has the B layer 20 made of PA, it has better pinhole resistance than a normal biaxially stretched film using a PP-based easy peel material.

  The PA used in the B layer 20 of the present invention is not particularly limited as long as it is a polymer having an amide bond. For example, 6 nylon, 66 nylon, 69 nylon, 6-66 nylon, 12 nylon, 11 nylon, Examples thereof include a polymer of a condensed unit such as 610 nylon, 612 nylon, 6I-6T nylon, MXD6 nylon, a copolymer, a copolymer with two or more of these, and a mixture thereof. Among them, 6 nylon, 6-66 copolymer nylon, or a mixture of 6 nylon and 6-66 copolymer nylon can be preferably used. As the PA used in the B layer 20, for example, NOVAMID (trade name) manufactured by Mitsubishi Engineering Plastics is preferably used. The B layer 20 may be a single layer or a plurality of layers, or may be composed of a plurality of layers made of different types of PA.

  If the B layer 20 is too thick, it may be difficult to form a film. Conversely, if the B layer 20 is too thin, pinhole resistance may be reduced, which may cause problems such as surface roughness and streaks. Therefore, the lower limit of the thickness of the B layer 20 is preferably 2 μm or more, more preferably 3 μm or more, and further preferably 4 μm or more. On the other hand, the upper limit of the thickness of the B layer 20 is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less.

<Adhesive resin layer (C layer) 30>
The C layer 30 is a layer made of an adhesive resin (hereinafter may be abbreviated as “AD”). The easy-open coextruded film of this invention can improve interlayer adhesive strength by having C layer 30 which consists of AD.

  The AD used in the C layer 30 requires two layers selected from the A layer 10, the B layer 20, the D layer 40 described below, or the F layer 60, which can be adjacent to each other. Adhesive strength (interlayer adhesive strength has a lower limit of preferably 5.88 N / mm width or more, more preferably 7.84 N / 15 mm width or more, further preferably 9.8 N / 15 mm width or more, and an upper limit of preferably 15 N / 15 mm width or less, and more preferably 14.7 N / 15 mm width or less).

  As AD, for example, a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof is preferably used. As the unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid and the like can be used. Further, as the unsaturated carboxylic acid derivative, the above unsaturated carboxylic acid ester or anhydride can be used. For example, methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate Butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, sodium acrylate and the like. In addition, vinyl acetate can also be used.

  Among them, when the C layer 30 and the B layer 20 and / or the D layer 40 or the C layer and the A layer 10 and / or the F layer 60 are bonded, it is preferable to use polyolefin-based AD. Specific examples of such polyolefin-based AD include Admer (trade name) manufactured by Mitsui Chemicals.

  The thickness of the C layer 30 is not particularly limited as long as the C layer 30 and the A layer 10, the B layer 20, the D layer 40, or the F layer 60 can be bonded with the required interlayer adhesion strength. The lower limit is preferably 2 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, and the upper limit is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less.

<Polypropylene resin layer (D layer) 40>
The D layer 40 is a layer made of a polypropylene resin (hereinafter sometimes abbreviated as “PP”). The PP used in the D layer 40 of the present invention is preferably a polypropylene homopolymer or a random copolymer of ethylene and propylene. Among these, from the viewpoint of delamination with the E layer 50 described below, it is preferable to use a homopolymer of polypropylene that is stiffer. If a polypropylene homopolymer is used as the PP used in the D layer 40, the D layer 40 can have an appropriate hardness, and the PP does not deform at the time of peeling and maintains a stable and good adhesive strength. be able to.

  The thickness of the D layer 40 is not particularly limited, but from the viewpoint of film formation, for example, the lower limit is preferably 3 μm or more, more preferably 5 μm or more, further preferably 8 μm or more, and the upper limit is preferably 50 μm or less. Preferably it is 30 micrometers or less, More preferably, it is 20 micrometers or less.

<E layer 50>
The E layer 50 is composed of a mixture of a linear low-density polyethylene resin (hereinafter sometimes abbreviated as “LLDPE”) and an ethylene-α-olefin copolymer having an amorphous or crystallinity of 15% or less. It is a resin (hereinafter sometimes abbreviated as “mixed resin”) layer. In the easy-open coextruded film of the present invention, an E layer 50 is provided between the D layer 40 and the F layer 60 for the purpose of imparting easy peelability at the time of peeling.

  The ethylene-α-olefin copolymer in the mixed resin is amorphous or has a crystallinity of 15% or less, preferably 13% or less, more preferably 10% or less. The crystallinity of the ethylene-α olefin copolymer can be usually measured by a DSC method.

As a method for measuring the degree of crystallinity, for example, when a sample is heated from a room temperature to a melt holding temperature at a rate of temperature increase of 20 ° C./minute using a DSC apparatus, the peak of the melting endotherm accompanying melting of the crystal is measured. An example is a method in which the apex is the heat melting temperature (Tm), the heat of fusion from the start point to the end point of the melting endotherm at Tm is obtained, and the crystallinity is obtained by the following formula.
Crystallinity (%) = (ΔH / ΔH ₀ ) × 100
ΔH: heat of fusion in E layer 50 ΔH ₀ : equilibrium heat of fusion of ethylene-α olefin copolymer

  Mixing ratio of LLDPE and ethylene-α olefin copolymer having a crystallinity of 15% or less (“LLDPE”: “ethylene-α olefin copolymer having a crystallinity of 15% or less) The union ") needs to increase the interlayer adhesive strength between the E layer 50 and the F layer 60 described later than the interlayer adhesive strength between the D layer 40 and the E layer 50, and therefore preferably" 30:70 "to" 90:10 ", more preferably" 50:50 "to" 90:10 ", and still more preferably" 70:30 "to" 90:10 ". Considering the hot tack property and transparency immediately after sealing, it is preferable to reduce the mixing ratio of the amorphous or α-olefin copolymer having a crystallinity of 15% or less.

  The α-olefin component constituting the amorphous or ethylene-α-olefin copolymer having a crystallinity of 15% or less contained in the mixed resin is not particularly limited, and for example, propylene or butene can be used. Specific examples of the amorphous or α-olefin copolymer having a crystallinity of 15% or less include Tuffmer (registered trademark) manufactured by Mitsui Chemicals.

  The easy peel strength between the D layer and the E layer is preferably 2.97 N / 15 mm width or more and 14.7 N / 15 mm width or less (500 gf / 15 mm width or more and 2000 gf / 15 mm width or less) for a deep-drawn gas pack. More preferably, it is 6.9 N / 15 mm width or more and 11.8 N / 15 mm width or less (700 gf / 15 mm width or more and 1200 gf / 15 mm width or less), More preferably, it is 7.8 N / 15 mm width or more and 10.8 N / 15 mm. It is below the width (800 gf / 15 mm width to 1100 gf / 15 mm width). The easy peel strength is obtained by appropriately adjusting the blending amount of the mixture of LLDPE contained in the E layer 50 and an amorphous or ethylene-α-olefin copolymer having a crystallinity of 15% or less within the above range. A desired easy peel strength can be obtained between 40 and the E layer 50.

  The easy peel strength can be determined by cutting the seal portion into a strip of 15 mm width and measuring the strength when peeled at a rate of 200 mm / min using a tensile tester.

<F layer 60>
The F layer 60 is a resin layer made of a polypropylene resin (hereinafter, may be abbreviated as “special PP”) obtained by using an ethylene propylene random copolymer and / or a metallocene catalyst. The lower limit of the melting point of the ethylene-propylene random copolymer is preferably 130 ° C or higher, more preferably 135 ° C or higher, still more preferably 140 ° C or higher, and the upper limit is preferably 155 ° C or lower, more preferably 150 ° C or lower. More preferably, it is 145 degrees C or less. If the melting point of the ethylene-propylene random copolymer is in the range of 130 ° C. or higher and 155 ° C. or lower, heat sealing can be realized at a relatively low temperature, which is desirable. The blending ratio of ethylene and propylene in the ethylene-propylene random copolymer (“ethylene”: “propylene”) is appropriately determined within the range of the melting point, preferably “3:97” to “20:80”, More preferably, they are “5:95” to “15:85”, and more preferably “7:93” to “10:90”.

  The lower limit of the melting point of the polypropylene resin obtained using the metallocene catalyst is preferably 120 ° C or higher, more preferably 123 ° C or higher, still more preferably 125 ° C or higher, and the upper limit is preferably 140 ° C or lower, more preferably. Is 130 ° C. or lower. If the melting point of the polypropylene resin obtained using the metallocene catalyst is in the range of 120 ° C. or higher and 140 ° C. or lower, it is desirable because heat sealing can be realized at a relatively low temperature.

  The lower limit of the total thickness of the E layer 50 and the F layer 60 is preferably 2 μm or more, more preferably 3 μm or more, still more preferably 4 μm or more, and the upper limit is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably. 8 μm or less. If the total thickness of the E layer 50 and the F layer 60 is 2 μm or more, a stable sealing property can be obtained, and if the total thickness is 20 μm or less, the E layer 50 and F generated when the lid is opened from the bottom material Fluffing (film remaining phenomenon) can be prevented at the vertical cuts between the layers 60, and a good appearance can be maintained.

  When the film of the present invention is used as a gas pack, it is preferable to add an antifogging agent to at least one layer selected from the D layer 40, the E layer 50, and the F layer 60 to impart antifogging properties. Examples of the anti-fogging agent that can be used include glycerin fatty acid esters such as glycerin stearic acid monoester, diglycerin laurate, and glycerylate, and sorbitan fatty acid esters such as sorbitan laurate and sorbitan urea. The content of the antifogging agent is preferably 0.5% by mass or more based on the mass (100% by mass) of at least one layer selected from the D layer 40, the E layer 50 and the F layer 60 containing the antifog agent. It is 2.0 mass% or less, More preferably, it is 0.8 mass% or more and 1.8 mass% or less, More preferably, it is 1.0 mass% or more and 1.5 mass% or less.

  When the coextruded film having the above configuration is used as a lid for a gas pack, it is generally difficult to seal in terms of heat resistance, and the peelability tends to be unstable. Therefore, in the easy-open coextruded film of the present invention, the easy-open coextruded film comprising at least six layers of the above-described A layer 10, B layer 20, C layer 30, D layer 40, E layer 50, and F layer 60. It is preferable that the biaxially stretched film 70 is bonded to the A layer 10 or B layer 20 side which is the outermost layer in the films 100a to 100d. A form 200 in which the biaxially stretched films are bonded together is schematically shown in FIG. 2 as a fifth embodiment.

  As the biaxially stretched film 70, a biaxially stretched nylon film (hereinafter sometimes abbreviated as “ONy”), a biaxially stretched polypropylene film (hereinafter sometimes abbreviated as “OPP”), and biaxially. A stretched polyethylene terephthalate film (hereinafter may be abbreviated as “OPET”) can be given. These biaxially stretched films 70 may be printed or plain. Of these, OPET and OPP are preferably used, and in particular, OPET is most preferably used in terms of heat resistance and printing pitch stability. An easy-open coextruded film 300 in which the biaxially stretched film 70 is printed and a printed layer 80 is formed (so-called back printing) is schematically shown in FIG. 3 as a sixth embodiment.

(Layer structure)
As shown in FIGS. 1A to 1D, the easy-open coextruded film of the present invention can have the layer configurations 100a to 100d of the first to fourth embodiments shown below.
(First embodiment) A layer 10 / B layer 20 / C layer 30 / D layer 40 / E layer 50 / F layer 60
(Second Embodiment) A layer 10 / B layer 20 / C layer 30 / F layer 60 / E layer 50 / D layer 40
(3rd embodiment) B layer 20 / A layer 10 / C layer 30 / D layer 40 / E layer 50 / F layer 60
(Fourth embodiment) B layer 20 / A layer 10 / C layer 30 / F layer 60 / E layer 50 / D layer 40

  In the layer configuration of (first embodiment) and (second embodiment), since they are laminated in the order of “A layer 10 / B layer 20 / C layer 30”, the layers between the A layer 10 / B layer 20 In addition, the interlayer strength of the B layer 20 / C layer 30 can be made stronger than, for example, the lamination of the A layer 10 / C layer 30 / B layer 20 in this order.

  In the easy-open coextruded film of the present invention, the lower limit of the interlayer adhesive strength between two layers selected from the A layer 10, the B layer 20, the C layer 30, the D layer 40 and the F layer 60 is preferable. 5.88 N / mm width or more, more preferably 7.84 N / 15 mm width or more, further preferably 9.8 N / 15 mm width or more, and the upper limit is preferably 15 N / 15 mm width or less, more preferably 14.7 N / width. The width is 15 mm or less. Further, since the A layer 10 has good dry laminate suitability without being subjected to corona treatment, it is firmly bonded to the biaxially stretched film 70 described above. Accordingly, since the interlayer adhesive strength other than the D layer 40 / E layer 50 / F layer 60 is very strong, peeling between the layers other than the D layer 40 and the E layer 50 does not occur, and a smooth easy peel is possible. Become.

  In conventional lid materials, when a high barrier substrate is bonded to a non-barrier composite film, generally the interlayer strength on the K coat (vinylidene chloride coat) surface or the transparent vapor deposition surface is insufficient. Therefore, particularly in the case of a package having a relatively high easy peel strength for a gas pack, there has been a problem in that during easy peel, peeling occurs between layers where the interlayer strength is insufficient, and smooth opening cannot be performed. . The present invention solves such a problem.

  The easy-open coextruded film (100, 200, 300) of the present invention has good heat resistance, and in particular, does not cause whitening even after hydrothermal treatment such as high-temperature sterilization treatment and maintains good transparency. In addition, the oxygen barrier property can be maintained, and an excellent effect of not causing delamination is achieved.

The easy-open coextruded film (100, 200, 300) of the present invention having such properties is sterilized under conditions of 100 ° C. or more and 125 ° C. or less and 5 minutes or more and 120 minutes or less, and then allowed to stand for 3 days. The oxygen permeability measured in accordance with JIS K7126 is 100 ml / m ² · day · MPa or less, preferably 50 ml / m ² · day · MPa or less, more preferably 10 ml / m ² · day · MPa or less. It is. If the oxygen permeability after the sterilization treatment is 100 ml / m ² · day · MPa or less, when a deep-drawn molded container is formed, the growth of fungi can be suppressed and the contents can be stored for a long time. .

  Furthermore, the easy-open coextruded film (100, 200, 300) of the present invention is sterilized under conditions of 100 ° C. or higher and 125 ° C. or lower and 5 minutes or longer and 120 minutes or shorter, and then left to stand for 3 days. The easy peel strength between the layer 40 and the E layer 50 is preferably 2.97 N / 15 mm width to 14.7 N / 15 mm width, more preferably 4 N / 15 mm width to 12 N / 15 mm width, and even more preferably 6 N / 15 mm width to 11 N / 15 mm width and less than the interlayer adhesion strength between two layers selected from the A layer 10, B layer 20, C layer 30, D layer 40 and F layer 60 Can do. If the easy peel strength after heat treatment and standing under the above conditions is 14.7 N / 15 mm width or less, good easy-openability can be obtained even after sterilization treatment.

  Further, the lower limit of the interlayer adhesive strength after sterilization treatment under conditions of 100 ° C. or more and 125 ° C. or less and 5 minutes or more and 120 minutes or less is preferably 6.5 N / 15 mm width or more, more preferably 8 N / 15 mm width or more. Yes, the upper limit is preferably 12.5 N / 15 mm width or less, more preferably 11 N / 15 mm width or less.

(Manufacturing method of easy-open coextruded film)
The resins constituting the A layer 10, the B layer 20, the C layer 30, the D layer 40, the E layer 50, and the F layer 60 described above are introduced into a uniaxial or biaxial kneading extruder, respectively, and a feed block system or a multi-manifold is used. By the co-extrusion of the hold method, a laminated sheet can be obtained by a general method in which the resin that has flowed out of the T-die is taken up by a casting roll. Thereby, the easy-open coextruded film 100a-100d of 1st-4th embodiment of this invention can be obtained. And the easy-open coextruded film 200 of 5th embodiment of this invention can be obtained by laminating | stacking the above-mentioned biaxially stretched film 70 on A layer 10 or B layer 20 which is the outermost layer (two). When the printing layer 80 is formed on the axial stretched film 70, the easy-open coextruded film 300 of the sixth embodiment can be obtained.

(Cover material and deep-drawn container)
The easy-open coextruded film of the present invention can be formed into a deep-drawn container lid material having a size and shape corresponding to the contents using a deep-drawing packaging machine. The lid material of the present invention is formed by the above-described easy-open coextruded films 100 and 200. For example, this lid material is sealed to a bottom material having a polypropylene resin as a sealant, and is used as a deep drawing container (for example, a gas pack container), or a bottom material composed of an EVOH layer and a PP layer and a PP layer as a sealing layer. And is suitably used as a high oxygen barrier container for jelly and the like.

  The deep-drawn container of the present invention is heat-sealed as measured in accordance with JIS K7105 when sterilized under conditions of 100 ° C. to 125 ° C. for 5 minutes to 120 minutes and left to stand for 3 days. The difference between the haze value of the part and the haze value before the sterilization treatment is preferably 10% or less, more preferably 8% or less, and further preferably 5% or less. Since the difference in haze value before and after the high temperature sterilization treatment is 10% or less in the deep-drawn molded container of the present invention, it is possible to suppress whitening of the film due to the conventional high temperature sterilization treatment and maintain good transparency.

  The deep-drawn molded container of the present invention can be produced by sealing the above-described lid material of the present invention to the bottom material. For example, after a bottom film is formed into a desired shape and size with a deep drawing mold (film supply process and film forming process), contents such as sliced ham are filled therein (content filling process) Furthermore, it is further sealed with the easy-open coextruded film (100, 200, 300) of the present invention (cover material film supplying step and sealing step), vacuum packaged (vacuum packaging step), and cooled (cooling step) ), By cutting (cutting step), a deep-drawn molded container can be produced.

Hereinafter, although the Example and comparative example of this invention are shown, this invention is not limited to this.
In Examples 1 to 4 and Comparative Examples 1 to 3, films were produced by the production methods shown respectively. About the produced film, it evaluated according to the evaluation method shown below. In the following examples and comparative examples, “/” indicates coextrusion and “//” indicates dry lamination.

Example 1
A six-layer laminated sheet was obtained by a general method in which the resin flowing out from the T-die was drawn with a casting roll by feed block co-extrusion using six twin-screw kneading extruders having a diameter of 65 mm. Then, an OPET film (16 μm) was laminated on the hrEVOH layer by a dry laminating method to obtain a film having the following layer structure.
OPET film (16 μm) // hr EVOH layer (A layer, 10 μm) / PA layer (B layer, 15 μm) / AD layer (C layer, 5 μm) / PP layer (D layer, 32 μm) / mixed resin layer (E layer, 5μm) / Special PP layer (F layer, 3μm)
The resin used in each layer is shown below.
OPET film: Diafoil H500 (Mitsubishi Chemical Polyester Film, biaxially stretched)
hrEVOH layer (A layer): heat-resistant EVOH (EF-CR manufactured by Kuraray Co., Ltd.)
PA layer (B layer): 6-66 copolymerized Ny with 66 nylon ratio of 15% by mass
AD layer (C layer): Admer QF500 (Mitsui Chemicals)
PP layer (D layer): Homo PP (melting point 164 ° C.)
Mixed resin layer (E layer): C4 type LLDPE (80% by mass) and Tuffmer A 4085 (Mitsui Chemicals) (20% by mass) Special PP layer (F layer): Metallocene PP (Nippon Polypro, Win Tech)

(Example 2)
A film was obtained in the same manner as in Example 1 except that an ethylene-propylene random copolymer (melting point: 145 ° C.) was used as the resin constituting the F layer.

(Example 3)
A film was obtained in the same manner as in Example 1 except that an OPP film (OPU-1, manufactured by Tosello Co., Ltd., biaxially stretched product) subjected to back printing was used instead of the OPET film.

Example 4
A film was obtained in the same manner as in Example 1 except that an ONy film (SNR-XT, manufactured by Mitsubishi Plastics, biaxially stretched product) was used instead of the OPET film.

(Comparative Example 1)
Using two twin-screw kneading extruders with a diameter of 65 mm, a two-layer laminated sheet was obtained by a general method in which the resin flowing out from the T-die was drawn by a casting roll by co-extrusion using a feed block method. And the EVOH film (25 micrometers) and the ONy film (25 micrometers) were laminated | stacked on PP layer, and the film which has the layer structure shown below was obtained.
ONy film (25 μm) // EVOH film (25 μm) // PP layer (45 μm) / cohesive failure layer (5 μm)
The resin used in each layer is shown below.
ONy film: SNR-XT (manufactured by Mitsubishi Plastics, biaxially stretched)
EVOH film: heat-resistant EVOH film (Kuraray Co., Ltd., EF-CR)
PP layer: Homo PP (melting point 164 ° C.)
Cohesive failure layer: Mixture of ethylene-propylene random copolymer (melting point 145 ° C.) (70 mass%) and low density polyethylene (30 mass%)

(Comparative Example 2)
Using two twin-screw kneading extruders with a diameter of 65 mm, a two-layer laminated sheet was obtained by a general method in which the resin flowing out from the T-die was drawn by a casting roll by co-extrusion using a feed block method. And transparent vapor deposition PET film (12 micrometers) and PET film (16 micrometers) were laminated | stacked on PP layer, and the film which has the layer structure shown below was obtained.
PET film (16 μm) // Transparent deposited PET film (12 μm) / PP layer (45 μm) / Low crystalline polyolefin layer (5 μm)
The resin used for each layer is shown below.
PET film: Diafoil H500 (Mitsubishi Chemical Polyester Film, biaxially stretched)
Transparent vapor-deposited PET film: Tech barrier TZ (manufactured by Mitsubishi Plastics, biaxially stretched)
PP layer: Homo PP (melting point 164 ° C.)
Low crystalline polyolefin layer: ethylene-butene 1 copolymer

(Comparative Example 3)
A film was obtained in the same manner as in Example 1 except that the hrEVOH layer (A layer) was an EVOH layer using EVOH of a general type having an ethylene content of 38 mol%.

<Evaluation method>
The film obtained in Examples 1 to 4 and Comparative Examples 1 to 3 was used as a cover material, and a coextruded film (PP layer (230 μm) / AD layer (20 μm) / EVOH layer (30 μm) / AD layer ( 20 μm) / PP layer (200 μm) (melting point of the PP layer: 160 ° C.)), a pack product was produced with a deep drawing packaging machine R530 (manufactured by Mulchback).
The production conditions of the pack product are as follows.
Molding temperature: 160 ° C
Sealing temperature: Size of optional packed product: Vertical seal 170 mm x Horizontal 127 mm rectangular seal width: 5 mm wide frame seal The obtained packed product was evaluated by the following evaluation method. The results are shown in the table.

(transparency)
The obtained pack product was subjected to high-temperature sterilization treatment at 120 ° C. for 20 minutes, and the haze values in the sealed portion before sterilization treatment and after standing for 3 days after sterilization treatment were measured with a spectrophotometer. As a result, the case where the difference in measured haze values was 5% or less was evaluated as “◯”, the case where it exceeded 5% and 8% or less was evaluated as “Δ”, and the case where it exceeded 10% was evaluated as “X”.

(Sealability)
When sealing the lid material and the bottom material, the seal temperature was increased from 120 ° C. in increments of 10 ° C., and the lowest seal temperature at which sealing could be performed reliably was taken as the seal start temperature. The lower the sealing start temperature, the better the sealing performance.

(Easy peel strength before high temperature sterilization)
Sealing was performed at the optimum sealing temperature (guideline: sealing start temperature + 20 ° C.), the seal part was cut into a strip shape with a width of 15 mm, and the strength when peeled at a rate of 200 mm / min was measured using a tensile tester. The average of the measured values of 10 test pieces was defined as easy peel strength (N / 15 mm width).

(Easy peel strength after high temperature sterilization)
Sealing is performed at the optimum sealing temperature (guideline: sealing start temperature + 20 ° C), the seal part is cut into a 15 mm width strip, subjected to high-temperature sterilization at 120 ° C for 20 minutes, and left still for 3 days after high-temperature sterilization. The strength when peeled at a rate of 200 mm / min was measured using a tensile tester. The average of the measured values of 10 test pieces was defined as easy peel strength (N / 15 mm width).

(Easy peel strength stability)
When the above-mentioned easy peel strength was measured, the case where the strength flare was less than ± 50% of the average value was evaluated as “◯”, and the case where the strength flare exceeded ± 50% was evaluated as “X”.

(Easy peel and adhesion suitability)
When the lid is peeled off, “○” indicates that it was peeled off between layers of normal easy peel, “△” indicates that a part of the peel occurred outside the layers of normal easy peel, and “between layers of normal easy peel” The case where all peeling occurred was evaluated as “x”.

(Oxygen barrier properties)
Based on the method prescribed | regulated to JISK7126 (The gas permeability test method of a plastic film and a sheet | seat), the oxygen permeability of the obtained film was measured under 23 degreeC and 0% humidity. Oxygen permeability was evaluated of less than 100ml / m ² · day · MPa as "○", "×" of not less than ^{100ml / m 2 · day · MPa} .

(Evaluation results)
When the easy-open coextruded films of Examples 1 to 3 of the present invention were used, the lid material and molded product of the present invention had good properties. In addition, when using the easy-open coextruded film of Example 4 of the present invention, the ONy film used as the biaxially stretched film is a film having moisture permeability. Transparency after the sterilization treatment was slightly lowered, and partial peeling occurred except for the normal easy peel layer.

  On the other hand, since the film of Comparative Example 1 was a film produced by a dry lamination method, partial peeling occurred in addition to the normal easy peel layer, and the easy peel property and interlayer adhesion were inferior. .

  When the film of Comparative Example 2 was used, since the transparent vapor-deposited PET film with poor adhesion was used, the transparency was good, but the easy peel strength stability was poor, and normal easy peel Apart from the interlayer, partial peeling occurred.

  When the film of Comparative Example 3 was used, EVOH having no heat resistance was used, so the EVOH layer was whitened and the transparency after the high temperature sterilization treatment was poor. Further, along with this whitening, the oxygen barrier property of the film of Comparative Example 3 was inferior.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the invention is limited to the embodiments disclosed herein. Rather, it can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and an easy-open coextruded film with such a change, a lid formed by this film, It should also be understood that deep drawn containers using this lid are also included within the scope of the present invention.

It is the schematic diagram which showed the layer structure of 1st embodiment of the easy-open coextruded film of this invention. It is the schematic diagram which showed the layer structure of 2nd embodiment of the easy-open coextruded film of this invention. It is the schematic diagram which showed the layer structure of 3rd embodiment of the easy-open coextruded film of this invention. It is the schematic diagram which showed the layer structure of 4th embodiment of the easy-open coextruded film of this invention. It is the schematic diagram which showed the layer structure of 5th embodiment of the easy-open coextruded film of this invention. It is the schematic diagram which showed the layer structure of 6th embodiment of the easy-open coextruded film of this invention.

Explanation of symbols

10 hrEVOH layer (A layer)
20 PA layer (B layer)
30 AD layer (C layer)
40 PP layer (D layer)
50 Mixed resin layer (E layer)
60 Special PP layer (F layer)
70 Biaxially stretched film 80 Printing layer 100a-d, 200, 300 Easy-open coextruded film

Claims (15)

Heat resistant ethylene-vinyl acetate copolymer saponified resin layer (A layer), polyamide resin layer (B layer), adhesive resin layer (C layer), polypropylene resin layer (D layer), linear low density polyethylene resin and Polypropylene obtained by using a resin layer (E layer) made of a mixture with an amorphous or ethylene-α olefin copolymer having a crystallinity of 15% or less, and an ethylene-propylene random copolymer and / or a metallocene catalyst Ri Do at least 6 layers of the resin layer made of a resin (F layer),
An easy-open coextruded film, wherein the heat-resistant ethylene-vinyl acetate copolymer saponified resin is a resin that does not whiten when sterilized at 120 ° C. for 20 minutes at a high temperature . The easy-open coextruded film according to claim 1, which has a layer structure selected from the following (1) to (4).
(1) A layer / B layer / C layer / D layer / E layer / F layer (2) A layer / B layer / C layer / F layer / E layer / D layer (3) B layer / A layer / C Layer / D layer / E layer / F layer (4) B layer / A layer / C layer / F layer / E layer / D layer   The easy-open coextruded film according to claim 1 or 2, wherein the polyamide resin of the B layer is 6 nylon, 6-66 copolymer nylon or a mixture of 6 nylon and 6-66 copolymer nylon.   The easy-open coextruded film according to any one of claims 1 to 3, wherein the polypropylene resin of the D layer is a propylene homopolymer or a random copolymer of ethylene and propylene.   The easily openable coextrusion film in any one of Claims 1-4 in which at least 1 layer chosen from the said D layer, E layer, and F layer contains an antifogging agent.   The easy-open coextruded film according to any one of claims 1 to 5, wherein the total thickness of the E layer and the F layer is 2 µm or more and 20 µm or less.   The interlayer adhesion strength between two layers selected from the A layer, the B layer, the C layer, the D layer, and the F layer is 5.88 N / 15 mm width or more and 15 N / 15 mm width or less. The easy-open coextruded film described in 1.   The easy peel strength between the D layer and the E layer is in the range of 2.97 N / 15 mm width to 14.7 N / 15 mm width, and the easy peel strength is the A layer, B layer, C layer, The easily openable coextruded film according to any one of claims 1 to 7, which is smaller in interlayer adhesive strength between two layers selected from a D layer and an F layer.   The printed or plain biaxially stretched polyethylene terephthalate film (OPET) or biaxially stretched polypropylene film (OPP) is further provided on the A layer or B layer which is the outermost layer. Easy-open coextrusion film. The oxygen permeability measured according to JIS K7126 when sterilized under conditions of 100 ° C. to 125 ° C. for 5 minutes to 120 minutes and left to stand for 3 days is 100 ml / m ² · day · MPa The easily openable coextruded film according to any one of claims 1 to 9, which is as follows.   Easy peel strength between D layer and E layer when sterilized under conditions of 100 ° C to 125 ° C for 5 minutes to 120 minutes and left to stand for 3 days is 2.97 N / 15 mm width or more The range is 14.7 N / 15 mm or less and smaller than the interlayer adhesive strength between two layers selected from the A layer, the B layer, the C layer, the D layer and the F layer. The easy-open coextruded film described in 1. The mixing ratio of the linear low density polyethylene resin and the amorphous or ethylene-α olefin copolymer having a crystallinity of 15% or less in the E layer is 70:30 to 90:10. The easily openable coextrusion film in any one of claim | item 1 -11. Lid formed by the easily openable coextruded film according to any one of claims 1 to 12. A deep-drawn container using the lid according to claim 13 . After sterilizing under conditions of 100 ° C. or higher and 125 ° C. or lower and 5 minutes or longer and 120 minutes or shorter, the haze value of the seal part measured in accordance with JIS K7105 when allowed to stand for 3 days, and before the sterilizing treatment The deep-drawn container according to claim 14 , wherein the difference from the haze value is 10% or less.

Images