JP2017121707A - Multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer film excellent in sealability and easy openability, and also excellent in visibility, while suppressing occurrence of delamination.SOLUTION: In a multilayer film 1 including a sealant layer 2 provided on a part of the outermost layer of the multilayer film 1, and a substrate layer 3 provided adjacently to the sealant layer 2, and containing a polyethylene resin having a melting point of 120-140°C and a nucleus agent, preferably, a density of the polyethylene resin is in the range of 0.925-0.970(g/cm3), the sealant layer contains a propylene-based resin, and a thickness of a substrate layer is 5-75 μm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a multilayer film.

  Conventionally, in order to improve the preservability of food, a gas replacement package in which a package containing food is filled with an inert gas or a vacuum package in which the gas remaining in the package is vacuum deaerated has been used. ing. For example, a package is known in which food is packed in a bottom material molded by a deep drawing machine, and an inert gas is filled or vacuumed to seal the lid. As the film for the bottom material or the lid material, a composite multilayer film having both sealing properties and easy opening properties is generally used.

  Here, Patent Document 1 and Patent Document 2 disclose known techniques for simultaneously providing such sealing properties and easy opening properties. Specifically, in Patent Document 1 and Patent Document 2, an ethylene vinyl acetate copolymer saponified resin layer, a polyamide resin layer, an adhesive resin layer, and a polypropylene resin layer (base material layer) are sequentially laminated, and the polypropylene On the resin layer (base material layer) side, a sealant layer was provided in which an ethylene-propylene random copolymer obtained by copolymerizing an ethylene component with a polypropylene resin and two or more incompatible resins such as a polyethylene resin were blended. The structure of an easily openable composite film (multilayer film) is disclosed.

  According to the easy-open composite film disclosed in Patent Document 1 and Patent Document 2, for example, when used as a film for a lid material, the sealant layer can be easily peeled by cohesive failure at the time of opening. It is said that. Thus, since a sealant layer is a layer which ensures easy opening property, it is also called the easy peel layer.

Japanese Patent No. 3642925 JP 2005-288793 A

  However, when the above-described conventionally known easy-open composite film is used as a bottom material or lid for an inert gas replacement package or vacuum package, the seal strength is locally increased, and stable easy There was a problem that the peel could not be realized.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the multilayer film excellent also in visibility, being excellent in sealing performance and easy-opening property, suppressing generation | occurrence | production of delamination. .

  As a result of intensive investigations to solve the above-mentioned problems, the cause of the local increase in seal strength is that the origin of peeling is not inside the easy peel layer, but the intersection of the base material layer and the easy peel layer. I found out. In addition, in order to realize stable easy opening, it is essential that the starting point of peeling exists inside the easy peel layer and that the base material layer has heat resistance so that it does not flow during sealing. I found out. Therefore, in place of polypropylene resin as the base material layer, the above-mentioned problem can be solved by blending a highly heat-resistant polyethylene resin and a nucleating agent that improves transparency that deteriorates when a highly heat-resistant polyethylene resin is used. The present invention has been completed by obtaining knowledge that it can be solved.

That is, the present invention has the following configuration.
The invention according to claim 1 is a multilayer film comprising a sealant layer and a base material layer provided adjacent to the sealant layer and including a polyethylene resin having a melting point of 120 to 140 ° C. and a nucleating agent.

The invention according to claim 2 is the multilayer film according to claim 1, wherein the density of the polyethylene resin is in the range of 0.925 to 0.970 (g / cm ³ ).

  Moreover, the invention which concerns on Claim 3 is a multilayer film of Claim 1 or 2 in which the said sealant layer contains propylene-type resin.

  Moreover, the invention which concerns on Claim 4 is a multilayer film as described in any one of Claims 1 thru | or 3 whose thickness of the said base material layer is 5-75 micrometers.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the ratio of the thickness of the base material layer to the thickness of the sealant layer is in the range of 80:20 to 20:80. It is a multilayer film of description.

  Moreover, the invention which concerns on Claim 6 is a multilayer film as described in any one of Claims 1 thru | or 5 whose haze value of the said multilayer film whole is 10% or less.

  The multilayer film of the present invention has a structure in which the base material layer adjacent to the sealant layer includes a polyethylene resin having a melting point of 120 to 140 ° C. and a nucleating agent, and is excellent in transparency. Excellent visibility while suppressing delamination.

It is a cross-sectional schematic diagram which shows an example of a structure of the multilayer film which is one Embodiment to which this invention is applied.

  Hereinafter, the structure of the multilayer film which is one embodiment to which the present invention is applied will be described in detail. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

First, an example of the structure of the multilayer film which is one embodiment to which the present invention is applied will be described.
FIG. 1 is a schematic cross-sectional view of a multilayer film 1 which is an embodiment to which the present invention is applied. As shown in FIG. 1, the multilayer film 1 of the present embodiment is schematically configured to include a sealant layer 2 and a base material layer 3 provided adjacent to the sealant layer 2. More specifically, the multilayer film 1 includes a coextruded multilayer film 7 in which a sealant layer 2, a base material layer 3, an adhesive layer 4, a tear resistant layer 5 and a gas barrier layer 6 are laminated in this order by a coextrusion method, and a support The layer 9 is laminated with the adhesive layer 8. This multilayer film 1 is applied to the use of an airtight packaging body (hereinafter sometimes simply referred to as “packaging body”) such as an inert gas replacement packaging body or a vacuum packaging body mainly used for food packaging. Can do.

  The sealant layer 2 is provided on one of the outermost layers of the multilayer film 1. The sealant layer 2 can be adhered to the sealant layers 2 or to other members. Although it does not specifically limit as an adhesion method, Specifically, a heat seal, an ultrasonic seal, a high frequency seal, an impulse seal etc. are mentioned, for example. Thus, a packaging body can be formed by bonding the multilayer films 1 having the sealant layer 2 together.

  The material of the sealant layer 2 is not particularly limited, but if it has an adhesive function and does not adversely affect its contents (such as non-adsorptiveness) when used as a package, it has been conventionally used as a sealing material. A general resin material to be used can be appropriately selected and used. Specific examples of such a material include polyethylene resins and polypropylene resins. The sealant layer 2 preferably includes a polypropylene resin, and more preferably a mixture of a polyethylene resin and a propylene resin.

  The polypropylene resin blended in the sealant layer 2 is preferably a polypropylene resin having a melting point of 155 ° C. or higher, preferably 160 ° C. or higher, measured by a differential scanning calorimetry (DSC) test method defined in JIS K7121. Such a resin is preferably a homopolymer of propylene, so-called homopolypropylene resin. If melting | fusing point is the said range, heat resistance will not run short. In addition, the adhesion to the polyethylene resin and the inhibitory effect on the fusion property are sufficient, and appropriate peel strength can be obtained between the adjacent base material layers 3.

  The polyethylene resin blended in the sealant layer 2 preferably has a melting point lower by 25 ° C. or more than the propylene resin. Specifically, for example, a linear polyethylene resin having a density d of 0.940 or more, a high density polyethylene resin (HDPE), a medium density polyethylene resin (MDPE) of 0.925 or more, and a copolymer with an α-olefin. A linear low density polyethylene resin (LLDPE) which is a polymer, a very low density polyethylene resin (VLDPE) having a density d of 0.910 or less, a low density polyethylene resin (LDPE) as a branched polyethylene resin, and a polar monomer Copolymers such as ethylene-vinyl acetate copolymer resin (EVA), ethylene-ethyl acrylate resin (EEA), ethylene-methyl acrylate resin (EMA), ethylene-methacrylic acid resin (EMAA) Is formed by intermolecular bonding of metal ions such as sodium and zinc. Onomer resins (ION), ethylene-acrylic acid copolymer resins (EAA), and elastomers such as ethylene-propylene rubber (EPR), ethylene-propylene diene terpolymers (EPDM), and chlorinated polyethylene. . These may be used alone or in combination.

  In the sealant layer 2, the amount of the propylene-based resin is preferably in the range of 5 to 40% by mass, and more preferably in the range of 10 to 30% by mass. When the blending amount of the propylene-based resin is within the above range, appropriate sealing strength and sealing strength can be obtained, and transparency can be ensured. In addition, as long as melting | fusing point is said range, 2 or more types may be used together for propylene resin. Moreover, you may mix | blend resin other than the above with the sealant layer 2 suitably in the range which does not impair the objective of this invention.

  The sealant layer 2 may contain other components such as an antifogging agent (for example, a PE antifogging master batch) in addition to the above-described polypropylene resin and polyethylene resin.

  The thickness of the sealant layer 2 is not particularly limited, but is preferably in the range of 1 to 15 μm, and more preferably in the range of 2 to 10 μm. When the thickness of the sealant layer 2 is within the above range, preferable sealing properties and unsealing properties can be obtained.

  The base material layer 3 is a resin layer provided adjacent to the sealant layer 2. More specifically, the base material layer 3 is laminated so as to be between the sealant layer 2 and the adhesive layer 4. The base material layer 3 gives the multilayer film 1 excellent flexibility.

  The base material layer 3 is a resin layer containing a polyethylene resin having a melting point of 120 to 140 ° C. and a nucleating agent measured by a differential scanning calorimetry (DSC) test method defined in JIS K7121. Here, when the melting point of the resin constituting the base material layer 3 is less than 120 ° C., when the multilayer film 1 is used for a package or the like, the resin constituting the base material layer 3 flows out when sealing. Is not preferable because delamination may occur.

  Although it does not specifically limit as a polyethylene resin which comprises the base material layer 3 and whose melting | fusing point is 120-140 degreeC, The range (generally, medium density-high density) is 0.925-0.970. Density) polyethylene resin is preferred, and polyethylene resin in the range of 0.941 to 0.970 (generally high density) is more preferred.

  Further, as the polyethylene resin constituting the base material layer 3, as long as the melting point of the base material layer itself (the whole) measured by DSC is in the range of 120 to 140 ° C., a single resin having a density within the above range is used. It may be composed of a single polyethylene resin, or may include a plurality of polyethylene resins having different densities.

  Moreover, it is preferable that the base material layer 3 contains 50 mass% or more of the polyethylene resin having a density within the above-described range in which the melting point is in the range of 120 to 140 ° C.

As the nucleating agent to be blended in the base material layer 3, a polyethylene-based crystallization nucleating agent having a density range of 0.925 to 0.970 (g / cm ³ ) is preferable. Moreover, as a compounding quantity of the nucleating agent in the base material layer 3, it is preferable to set it as the range of 1.5-3.5 mass parts with respect to 100 mass parts of polyethylene resins.

  The base material layer 3 may contain other components such as an antifogging agent (for example, a PE antifogging master batch) in addition to the above-described polyethylene resin and nucleating agent.

  By the way, in the conventional easy-open composite film (multilayer film), a polypropylene resin having a high melting point was used as the base material layer, so that the resin constituting the base material layer did not flow out when sealing, and delamination occurred. There was an advantage that can be suppressed.

  However, when a general polypropylene resin is used for the base material layer, the seal strength is locally increased, it is difficult to peel off, and a stable easy peel is not achieved.

  On the other hand, when a polyethylene-based resin is used as the base material layer, the haze value can be easily improved by including a nucleating agent, so that the visibility of the contents can be ensured. However, when a polyethylene-based resin having a melting point of less than 120 ° C., such as a low-density polyethylene resin (LDPE), is used as the base material layer, the resin constituting the base material layer flows out when sealing. There has been a problem that it is difficult to suppress the occurrence of water.

On the other hand, according to the multilayer film 1 of this embodiment, the base material layer 3 is a resin layer containing a polyethylene resin having a melting point of 120 to 140 ° C. (density range: 0.925 to 0.970 g / cm ³ ). Since it is comprised, when sealing, resin which comprises a base material layer does not flow out, but generation | occurrence | production of delamination can be suppressed. Furthermore, when the base material layer 3 contains the nucleating agent, the haze value of the polyethylene resin is improved. Therefore, the visibility with respect to the contents can be ensured.

  Although it does not specifically limit as thickness of the base material layer 3, Specifically, the range of 5-50 micrometers is preferable, for example, and 5-45 micrometers is more preferable. It is preferable for the thickness of the base material layer 3 to be in the above range because excellent transparency can be imparted to the multilayer film 1.

  As the transparency of the base material layer 3, the haze value at a thickness of 0.15 mm is preferably 40% or less, and more preferably 35% or less. Here, when the haze value at a thickness of 0.15 mm is 40% or less, for example, when the thickness is set to 5 μm or more and 50 μm or less as a base material layer of a food packaging body, the content is sufficiently transparent so that the contents can be visually recognized. It is preferable because of its properties. In addition, the haze of a polyethylene resin layer can be measured by the method etc. based on JISK7136, for example.

  In the multilayer film 1 of the present embodiment, the ratio between the thickness of the sealant layer 2 and the thickness of the base material layer 3 is preferably in the range of 80:20 to 20:80. When the ratio of the thickness of the sealant layer 2 to the thickness of the base material layer 3 is within the above range, the flow (flow) between the sealant layer and the base material layer is not disturbed, so that a stable appearance is preferable.

  The adhesive layer 4 is provided between the base material layer 3 and the tear resistant layer 5 in order to adhere the base material layer 3 and the tear resistant layer 5. Thereby, the adhesive force between the layers of the base material layer 3 and the tear-resistant layer 5 is increased, and in the multilayer film 1, peeling at these interfaces can be prevented.

  Although it does not specifically limit as a material of the contact bonding layer 4, Specifically, adhesive polypropylene-type resin, adhesive polyethylene-type resin, etc. can be used, for example. Moreover, you may use an anchor coat agent etc. according to the objective.

  The tear resistant layer 5 is an arbitrary resin layer provided for imparting tear resistance of the multilayer film 1. In the present embodiment, the tear resistant layer 5 is provided between the adhesive layer 4 and the gas barrier layer 6, and is provided so as to be laminated adjacent to the adhesive layer 4 and the gas barrier layer 6.

  The resin component of the tear resistant layer 5 is not particularly limited, and specific examples thereof include nylon resins.

  As tear resistance of the tear resistant layer 5, the tear strength is preferably 150 (N / mm) or more, and more preferably 200 (N / mm) or more. As a result, it is possible to prevent breakage caused by pinholes and cracks.

  The thickness of the tear resistant layer 5 is not particularly limited, but specifically, for example, 5 μm or more is preferable and 10 μm or more is more preferable. When the thickness of the tear resistant layer 5 is within the above range, it is preferable because sufficient tear resistance can be exhibited.

  This tear resistant layer 5 can produce a film containing a nylon resin by melt kneading a nylon resin and laminating the resin in a molten state with several different extruders.

  The gas barrier layer 6 is a resin layer provided mainly for suppressing oxygen permeation. Further, the gas barrier layer 6 is provided so as to be on the support layer 9 side in the coextruded multilayer film 7 constituting the multilayer film 1 of the present embodiment. By providing the gas barrier layer 6 so as to be on the support layer 9 side, when a multilayer body 1 is used to form a package or the like, oxygen can be prevented from entering the package or the like from the support layer 9 side. be able to.

  The material of the gas barrier layer 6 (that is, the barrier material) is not particularly limited as long as the material does not impair the transparency of the multilayer film 1. Specifically, for example, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer (EVOH), polyester such as polyethylene terephthalate (PET), aromatic polyamide such as polymetaxylylene adipamide (МXD6), etc. It is preferable to use an oxygen barrier resin. Among these, it is more preferable to use an ethylene-vinyl alcohol copolymer (EVOH).

  The thickness of the gas barrier layer 6 is not particularly limited, but specifically, for example, 5 μm or more is preferable, and 7 μm or more is more preferable. When the thickness of the gas barrier layer 6 is within the above range, the gas barrier property is exhibited according to the content, the content is protected from external oxygen, and the internal flavor is prevented from leaking to the outside. It is preferable because it is possible.

  In the multilayer film 1 of the present embodiment, the above-described sealant layer 2, base material layer 3, adhesive layer 4, tear resistant layer 5 and gas barrier layer 6 are laminated in this order to constitute a coextruded multilayer film 7. The coextruded multilayer film 7 can be formed by a coextrusion method. In the co-extruded multilayer film 7, one surface layer is the sealant layer 2, and the other surface layer is the gas barrier layer 6.

  The thickness of the coextruded multilayer film 7 is not particularly limited, but specifically, for example, 30 μm or more and 100 μm or less is preferable, and 40 μm or more and 90 μm or less is more preferable. When the thickness of the coextruded multilayer film 7 is within the above range, it is preferable because of having excellent transparency.

  The adhesive layer 8 is provided between the coextruded multilayer film 7 and the support layer 9 in order to bond the coextruded multilayer film 7 and the support layer 9. By providing this adhesive layer 8, the adhesive force between the layers of the coextruded multilayer film 7 and the support layer 9 is increased, and peeling at these interfaces can be prevented. The material of the adhesive layer 8 is not particularly limited, but specifically, for example, the same material as that of the adhesive layer 4 can be used. Further, the adhesive layer 8 may be made of a material different from that of the adhesive layer 4.

  The support layer 9 is a transparent resin layer provided for imparting shape retention (rigidity), heat resistance, and transparency to the multilayer film 1 of the present embodiment. The support layer 9 is laminated with the coextruded multilayer film 7 via the adhesive layer 8 and is provided to be the other surface of the multilayer film 1 (that is, the surface opposite to the sealant layer 2). Yes.

The material of the support layer 9 is not particularly limited, but preferable materials include, for example, polyolefins such as low density polyethylene, high density polyethylene, and polypropylene; polyamides of nylon (registered trademark); polyesters such as polyethylene terephthalate (PET); Resin; Resin such as cellulose (cellophane and paper are also included in the cellulose).
Among these, the material of the support layer 9 is more preferably polyolefin, nylon (registered trademark), or polyester stretched uniaxially or biaxially.

  Although the thickness of the support layer 9 is not specifically limited, For example, it is preferable that it is 5-300 micrometers, and it is more preferable that it is 10-250 micrometers. It is preferable for the thickness of the support layer 9 to be in the above-mentioned range because it looks good when used in a gas pack.

  Although the thickness of the multilayer film 1 whole of this embodiment is not specifically limited, For example, it is preferable that it is 35-400 micrometers, and it is more preferable that it is 50-340 micrometers. When the thickness of the entire multilayer film 1 is within the above range, it is preferable because it looks good when used in a gas pack.

  Moreover, it is preferable that the haze value of the multilayer film 1 whole of this embodiment is 10% or less, and it is more preferable that it is 9% or less. Here, when the haze value is 10% or less, for example, when the total thickness of the multilayer film 1 is set to 35 μm or more and 400 μm or less as a food packaging body or the like, the transparency is sufficient to allow the contents to be visually recognized. Is preferable. In addition, the haze value of the multilayer film 1 can be measured by, for example, a method based on JIS K7136.

Next, an example of the manufacturing method of the multilayer film 1 of this embodiment mentioned above is demonstrated.
Although it does not specifically limit as a manufacturing method of the multilayer film 1, For example, co-extrusion T die methods, such as the feed block method which melts and extrudes resin etc. which are raw materials with several extruders, a multi-manifold method, an air cooling type Alternatively, a water-cooled coextrusion inflation method or a method of laminating a single layer extruded film by laminating may be mentioned, and among these, the method of forming a film by the coextrusion T-die method is particularly preferable in terms of excellent thickness control of each layer.

  Specifically, for example, first, the co-extruded multilayer film 7 is formed by coextrusion of the raw material resin up to the sealant layer 2, the base material layer 3, the adhesive layer 4, the tear resistant layer 5 and the gas barrier layer 6. Next, the multilayer film 1 of this embodiment can be manufactured by laminating the coextruded multilayer film 7 formed through the adhesive layer 8 and the support layer 9.

  In addition, the method for producing a package using the multilayer film 1 of the present embodiment is not particularly limited. For example, first, using a generally used deep drawing machine, vacuum forming, The storage part is formed on the molding package (laminated film) by pressure forming or plug forming.

  Next, after the contents (for example, food) are filled in the storage part of the molding package described above, the multilayer film 1 of this embodiment is overlaid as a cover film, and the molding package and the cover film (multilayer film 1). ) Can be bonded to produce a package.

  As described above, according to the multilayer film 1 of this embodiment, the base material layer 3 adjacent to the sealant layer 2 is configured to include a polyethylene resin having a melting point of 120 to 140 ° C. and a nucleating agent, and also has transparency. Since it is excellent, it is excellent in sealability and easy-openability, and it is excellent in visibility while suppressing the occurrence of delamination.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. Moreover, it does not specifically limit as a use of the multilayer film 1 of this embodiment. Specifically, for example, it may be a food bag such as meat, processed meat, and fruits, or a packaging bag that stores medical instruments such as an injection needle, a syringe, a test kit, and a catheter.

  The effects of the present invention will be described in more detail based on the following examples and comparative examples, but the present invention is not limited thereto.

<Resin material>
In order to verify the effect of the multilayer film of the present invention, a multilayer film having the structure shown in FIG. 1 was produced. Here, the raw material resin of each layer used for manufacture of a multilayer film is as follows.

"Sealant layer"
(A) Low density polyethylene resin Ube Maruzen Polyethylene Co., Ltd., Ube Polyethylene F324C
Density: 0.924 g / cm ³
Melting point: 112 ° C
(B) Homopolypropylene resin (Prime Polymer Co., Ltd., Prime Polypro Y400GP)
Density: 0.905 g / cm ³
Melting point: 158 ° C
(C) Polyethylene anti-fog MB
Takemoto Yushi Co., Ltd., ELECUTMASTER L117A
Base PE density: 0.923 g / cm ³
-Melting point of base PE: 111 ° C

"Base material layer"
(A) High-density polyethylene resin, made by Prime Polymer Co., Ltd., Hi-Zex 3300F
Density: 0.950 g / cm ³
Melting point: 132 ° C
(B) High-density polyethylene nucleating agent MB
Riken Master CN002, manufactured by Riken Vitamin Co., Ltd.
(C) Polyethylene anti-fog MB
Takemoto Yushi Co., Ltd., ELECUTMASTER L117A
(D) Low density polyethylene resin Sumitomo Chemical L211, manufactured by Sumitomo Chemical Co., Ltd.
Density: 0.924 g / cm ³
Melting point: 113 ° C
(E) Polypropylene resin, Sumitomo Chemical Co., Ltd., Nobrene FH3315
Density: 0.910 g / cm ³
Melting point: 144 ° C

"Adhesive layer"
Polyethylene adhesive resin: manufactured by Mitsui Chemicals, Admer NF536
Density: 0.905 g / cm ³
Melting point 120 ° C
"Tear-resistant layer"
NY: Ube Nylon 1030B2 manufactured by Ube Industries, Ltd.
Density: 1.14 g / cm ³
Melting point: 225 ° C
"Gas barrier layer"
EVOH: Kuraray Co., Ltd., Eval E173B
Density: 1.17 g / cm ³
Melting point: 165 ° C
-Ethylene content: 44 mol%
"adhesive"
Takelac A manufactured by Mitsui Chemicals, Inc.

"Support layer"
(A) OPET film Biaxially stretched polyethylene terephthalate film: manufactured by Teijin DuPont Films, Ltd. Tetoron film GE
(B) APET sheet Polyethylene terephthalate unstretched single layer sheet: manufactured by Toyobo Co., Ltd., PETMAX A750FEIR

<Production of multilayer film>
A multilayer film having the structure shown in FIG. 1 was produced. Specifically, a co-extruded multilayer film is formed by co-extrusion of a raw material resin up to a sealant layer, a base material layer, an adhesive layer, a tear resistant layer and a gas barrier layer, and then a support layer via an adhesive (adhesive layer) Were laminated to produce the multilayer films of Examples 1 to 4 and Comparative Examples 1 to 3. In addition, it shows in following Table 1 about the specific structure (a kind of resin, layer thickness, compounding ratio, etc.) of each layer (especially base material layer and sealant layer).

  The melting point of the base material layer was evaluated by DSC (differential scanning calorimetry). Furthermore, the transparency of the base material layer was evaluated by a method based on JIS K7136. The results are shown in Table 1 below.

Example 1
First, the resins were mixed at a blending ratio shown in Table 1 to prepare a raw material resin for the sealant layer. Moreover, the high density polyethylene resin (A), the nucleating agent (B), and the antifogging agent (C) were mixed at a blending ratio shown in Table 1, and prepared as a raw material resin for the base material layer.
Next, the raw material resin up to the sealant layer, the base material layer, the adhesive layer, the tear resistant layer and the gas barrier layer was coextruded to form a coextruded multilayer film. Subsequently, the biaxially stretched polyethylene terephthalate film (A) was laminated as a support layer using an adhesive to produce a multilayer film having a layer structure shown in Table 1 (multilayer film of Example 1).

  In addition, melting | fusing point (namely, melting | fusing point of raw material resin, the same hereafter) in the single layer of the base material layer (high density polyethylene resin (A) + nucleating agent (B) + antifogging agent (C)) which comprises Example 1 is 126 ° C. Moreover, the haze value in the thickness of the base material layer of 0.15 mm was 25%. Furthermore, the thickness of the whole multilayer film of Example 1 was 72 μm, and the haze value of the whole multilayer film was 4%.

(Example 2)
Example 2 is the same as Example 1 except that the structure of the base material layer is changed to only the high-density polyethylene resin (A) and the nucleating agent (B) (not including the antifogging agent (C)). A multilayer film was produced.

  In addition, melting | fusing point in the single layer of the base material layer (high density polyethylene resin (A) + nucleating agent (B)) which comprises Example 2 was 132 degreeC. Moreover, the haze value in the thickness of the base material layer of 0.15 mm was 30%. Furthermore, the thickness of the whole multilayer film of Example 2 was 72 μm, and the haze value of the whole multilayer film was 5%.

(Example 3)
A multilayer film of Example 3 was produced in the same manner as in Example 1 except that the configuration of the support layer was changed to the polyethylene terephthalate unstretched single layer sheet (B).
In addition, the thickness of the whole multilayer film of Example 3 was 260 micrometers, and the haze value of the whole multilayer film was 6%.

Example 4
The coextruded multilayer film formed in Example 1 was used as the multilayer film of Example 4. The thickness of the entire multilayer film of Example 4 was 60 μm, and the haze value of the entire multilayer film was 3%.

(Comparative Example 1)
In the structure of the base material layer, a comparative example was obtained in the same manner as in Example 1 except that the polypropylene resin (E) was used instead of the high density polyethylene resin (A) and the nucleating agent (B) was not included. 1 multilayer film was produced.

  In addition, melting | fusing point in the single layer of the base material layer (polypropylene-type resin (E) + antifogging agent (C)) which comprises the comparative example 1 was 138 degreeC. Moreover, the haze value in the thickness of the base material layer of 0.15 mm was 15%. Furthermore, the thickness of the whole multilayer film of Comparative Example 1 was 72 μm, and the haze value of the whole multilayer film was 6%.

(Comparative Example 2)
In the configuration of the base material layer, a comparison was made in the same manner as in Example 1 except that the low-density polyethylene resin (D) was replaced with the high-density polyethylene resin (A) and the nucleating agent (B) was not included. The multilayer film of Example 2 was produced.

  In addition, melting | fusing point in the single layer of the base material layer (low density polyethylene resin (D) + antifogging agent (C)) which comprises the comparative example 2 was 112 degreeC. Moreover, the haze value in the thickness of the base material layer of 0.15 mm was 8%. Furthermore, the thickness of the entire multilayer film of Comparative Example 2 was 72 μm, and the haze value of the entire multilayer film was 3%.

(Comparative Example 3)
Comparative Example 3 was carried out in the same manner as in Example 1 except that the structure of the base material layer was changed to a high-density polyethylene resin (A) and an antifogging agent (C) only (not including the nucleating agent (B)). A multilayer film was produced.

  In addition, melting | fusing point in the single layer of the base material layer (high density polyethylene resin (A) + antifogging agent (C)) which comprises the comparative example 3 was 126 degreeC. Moreover, the haze value in the thickness of the base material layer of 0.15 mm was 45%. Furthermore, the thickness of the entire multilayer film of Comparative Example 3 was 72 μm, and the haze value of the entire multilayer film was 11%.

<Evaluation of multilayer film>
About the produced multilayer film of Examples 1-4 and Comparative Examples 1-3, delamination resistance, seal strength, and visibility were evaluated.

(Evaluation of delamination resistance)
About the multilayer film produced in Examples 1-4 and Comparative Examples 1-3, the characteristic was evaluated using the vacuum made from a multi-back Co., Ltd., and a gas substitution packaging machine (R535 series).
Specifically, first, a container having a size of length 200 mm × width 90 mm × depth 25 mm is formed, and the layer structure is amorphous polyethylene terephthalate resin / adhesive resin / EVOH / NY / adhesive resin / polyethylene resin ( 80 g of sliced ham was filled as a content into a formed rectangular tray having a thickness of 140/10/8/8/12/12 μm and a total thickness of 190 μm. The container for evaluation was formed by heat-sealing (145 ° C. × 1.5 s, sealing pressure 6 kgf / cm ² ) using the multilayer film produced in Examples 1 to 4 and Comparative Examples 1 to 3 as a lid.

Subsequently, about the state at the time of opening of the obtained container for evaluation, the presence or absence (delamination tolerance) of delamination was evaluated on the following reference | standard. The results are also shown in Table 1 below.
・ No delamination: No film peeling or tearing occurs between multilayer film layers ・ Partial occurrence: Partial film peeling occurs between multilayer film layers

(Evaluation of seal strength)
Similarly, an evaluation container was formed using the multilayer films prepared in Examples 1 to 4 and Comparative Examples 1 to 3.
Next, the following criteria were used to monitor the feeling of peeling (stiffness) when the lids of the containers for evaluation of Examples 1 to 4 and Comparative Examples 1 to 3 were peeled off. The results are also shown in Table 1 below.
・ Appropriate: 6 or more persons determined to be moderately firm in an opening test with 10 monitors ・ Stiff: 6 or more persons were determined to be heavy or firm in an opening test with 10 monitors

(Visibility evaluation)
Similarly, an evaluation container was formed using the multilayer films prepared in Examples 1 to 4 and Comparative Examples 1 to 3.
Subsequently, in order to confirm the visibility of the contents in the obtained container for evaluation, monitoring was performed according to the following criteria, and practical evaluation of transparency (visibility) was performed. The results are shown in Table 1 below.
-Good: 6 or more people are judged to have good visibility by visual confirmation from the lid material side by 10 monitors.-Bad: 6 or more people are judged to be poor visibility by visual confirmation from the lid material side by 10 monitors.

  As shown in Table 1, since the multilayer sheet of Comparative Example 1 uses a polypropylene resin as a resin constituting the base layer, it is excellent both as a single base layer and as a whole multilayer sheet without using a nucleating agent. However, since unevenness occurs in delamination resistance and seal strength, a stable easy peel cannot be realized when used as a lid.

  In addition, since the multilayer sheet of Comparative Example 2 uses a low-density polyethylene resin as the resin constituting the base layer, excellent transparency as a whole multi-layer sheet can be achieved by using only the base layer without using a nucleating agent ( However, when used as a lid, the delamination resistance was not sufficient.

  Moreover, since the multilayer sheet of Comparative Example 3 uses a high-density polyethylene resin that does not contain a nucleating agent as the resin constituting the base material layer, the base material layer alone or the entire multilayer sheet is transparent (visibility) Was not enough.

  On the other hand, the multilayer sheets of Examples 1 to 4 have a configuration in which the base material layer includes a polyethylene resin having a temperature of 120 to 140 ° C. and a nucleating agent. It was confirmed that it was excellent in visibility and also excellent in visibility while suppressing the occurrence of delamination.

  The multilayer film of the present invention can be used for packaging bags, packaging containers and the like for packaging foods, pharmaceuticals, medical instruments and the like.

  DESCRIPTION OF SYMBOLS 1 ... Multilayer film, 2 ... Sealant layer, 3 ... Base material layer, 4 ... Adhesive layer, 5 ... Tear resistant layer, 6 ... Gas barrier layer, 7 ... Coextrusion multilayer film, 8 ... Adhesive layer, 9 ... Support layer

Claims (6)

  A multilayer film comprising: a sealant layer; and a base material layer provided adjacent to the sealant layer and including a polyethylene resin having a melting point of 120 to 140 ° C. and a nucleating agent. The multilayer film of Claim 1 whose density of the said polyethylene resin is the range of 0.925-0.970 (g / cm < ³ >).   The multilayer film according to claim 1, wherein the sealant layer contains a propylene-based resin.   The multilayer film as described in any one of Claims 1 thru | or 3 whose thickness of the said base material layer is 5-75 micrometers.   The multilayer film according to any one of claims 1 to 4, wherein a ratio of the thickness of the base material layer to the thickness of the sealant layer is in a range of 80:20 to 20:80.   The multilayer film as described in any one of Claims 1 thru | or 5 whose haze value of the said multilayer film whole is 10% or less.

Images