JP2023124608A - Resin film, package, and fishery product package - Google Patents

Abstract

To provide a package capable of storing a fishery product or a processed product of the fishery product for a long period of time without damaging its flavor by suppressing its degradation.SOLUTION: A resin film is used for a lid material of a vacuum package for a fishery product or a processed product of the fishery product, the package comprising the lid material and a bottom material. The resin film has an oxygen permeation amount of 100 cc/(m2 day atm) or less under a condition of a temperature of 23°C and a relative humidity of 60%, and the resin film measured in compliance with JIS K7127: 1999 has a tensile strength of 0.3 to 4 N/mm2 at a temperature of 140°C. The vacuum package for the fishery product or the processed product of the fishery product comprises the lid material 1 and the bottom material 8, and the package 10 comprises the lid material 1 made of the resin film.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a resin film, a package, and a marine product package.

Edible marine products or processed marine products are, for example, placed on resin trays and packaged together with the resin tray using a transparent resin film with low oxygen barrier properties, or packaged in a bag-like package, and sold at retail. (see Patent Document 1).

Japanese Patent No. 6370290

However, marine products or processed marine products, especially marine products, when placed on resin trays, tend to spoil easily, lose their flavor, and generally do not keep for a long time.

An object of the present invention is to provide a package that suppresses deterioration of marine products or processed marine products and enables long-term storage without impairing their flavor.

In order to solve the above problems, the present invention employs the following configuration.
[1]. A resin film, which is used as a lid material for a vacuum package for marine products or processed marine products, comprising a lid material and a bottom material, under conditions of a temperature of 23° C. and a relative humidity of 60%. The oxygen permeation amount of the resin film is 100 cc/(m ² · day · atm) or less, and the tensile strength of the resin film at a temperature of 140 ° C. measured in accordance with JIS K 7127: 1999 is , 0.3 to 4 N/mm ² , the resin film.
[2]. The resin according to [1], wherein the resin film has a dynamic elastic modulus E' of 1×10 ⁴ to 1×10 ⁷ Pa at a temperature of 140° C., measured according to JIS K 7244-4. film.
[3]. The resin film according to [1] or [2], wherein the resin film exhibits a displacement of 2000 μm at a temperature of 120° C. or higher during thermomechanical analysis.
[4]. The resin film according to any one of [1] to [3], wherein the resin film has a gel fraction of 30% or more.

[5]. The resin film according to any one of [1] to [4], wherein the resin film is irradiated with an electron beam at an absorbed dose of 13 to 300 kGy.
[6]. The resin film according to any one of [1] to [5], having a displacement of 500 μm or less at a temperature of 100° C. in thermomechanical analysis of the resin film.
[7]. The resin according to any one of [1] to [6], wherein the resin film is a multilayer film comprising an outer layer, a functional layer adjacent to the outer layer, an oxygen barrier layer, and a sealant layer. film.
[8]. The resin film according to [7], wherein the outer layer contains a polyethylene-based resin.
[9]. The resin film according to [7] or [8], wherein the functional layer contains an ionomer.
[10]. The resin film according to any one of [7] to [9], wherein the sealant layer contains a polyethylene resin.
[11]. The resin film according to any one of [1] to [10], wherein the vacuum package is a skin pack package for chilled raw meat.

[12]. A vacuum package for marine products or processed marine products, comprising a lid material and a bottom material, wherein the resin film according to any one of [1] to [11] is used as the lid material.
[13]. The package according to [12], wherein the bottom material has an oxygen permeation rate of 300 cc/(m ² ·day·atm) or less under conditions of a temperature of 23°C and a relative humidity of 60%.
[14]. A marine product package in which a marine product or a processed marine product is vacuum-packaged with the bottom member and the lid member of the package according to [12] or [13].

ADVANTAGE OF THE INVENTION According to this invention, the package body which suppresses the deterioration of a marine product or a processed marine product, and can store it for a long period of time is provided, without spoiling the flavor.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically an example of the resin film which concerns on one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically an example of the package which concerns on one Embodiment of this invention.

<<Resin film (lid material)>>
A resin film according to one embodiment of the present invention is a resin film for a lid material of a vacuum package for a marine product or a processed marine product, which includes a lid material and a bottom material, and has a temperature of 23° C. and a relative humidity of 60%. The oxygen permeation amount of the resin film is 100 cc/(m ² · day · atm) or less under the conditions of 140 ° C. of the resin film measured in accordance with JIS K 7127: 1999. has a tensile strength of 0.3 to 4 N/mm ² .

As used herein, the term "vacuum packaging" means vacuuming such that the pressure in the area where the contents are placed is 5000 Pa (50 mbar) or less. The pressure is, for example, preferably 300 to 5000 Pa, more preferably 400 to 4900 Pa, even more preferably 500 to 4800 Pa, particularly preferably 600 to 4700 Pa.

The vacuum package is preferably a skin pack package for chilled raw meat. As used herein, the term "skin pack" refers to placing a stored item on cardboard, cardboard, a bottom film, a tray, or the like, covering it with a heated film, and vacuuming in a chamber to remove the film. It means packaging that is tightly fixed to the contents. The name “skin pack” derives from the fact that the film follows the shape of the product and adheres to the product itself like a skin.

As used herein, the term “refrigeration” refers to artificially using a device (refrigerator or refrigerator) to maintain the quality of stored items such as raw meat at a temperature of 0 ° C or higher and 10 ° C or lower. It means storage, or storage at a temperature of 0° C. or more and 10° C. or less in a natural environment. The temperature is, for example, preferably 0° C. or higher and lower than 10° C., more preferably 0.2° C. or higher and 9.8° C. or lower, and further preferably 0.4° C. or higher and 9.6° C. or lower. It is preferably 0.6°C or higher and 9.4°C or lower, particularly preferably.

The oxygen permeation amount of the resin film (lid material) under conditions of a temperature of 23° C. and a relative humidity of 60% is 100 cc/(m ² ·day·atm) or less. The amount of oxygen permeation of the resin film (lid material) under the conditions of a temperature of 23 ° C. and a relative humidity of 60% is 100 cc / (m ² · day · atm) or less, It can be stored for a long period of time while suppressing its deterioration.

The oxygen permeation amount of the resin film (lid material) under conditions of a temperature of 23° C. and a relative humidity of 60% is preferably 95 cc/(m ² ·day·atm) or less, more preferably 90 cc/(m ² · day·atm) or less, more preferably 85 cc/(m ² ·day·atm) or less, and particularly preferably 80 cc/(m ² ·day·atm) or less. It may be 75 cc/(m ² ·day · atm) or less. Under the conditions of a temperature of 23° C. and a relative humidity of 60%, the amount of oxygen permeation of the resin film (lid material) is equal to or less than the upper limit, so that the stored items that are refrigerated and packaged can be stored for a long time while suppressing their deterioration. It is possible to further improve the effect of
On the other hand, the oxygen permeation amount is 0 cc/(m ² ·day·atm) or more.

The oxygen permeation amount of the resin film (lid material) under conditions of a temperature of 23° C. and a relative humidity of 60% can be measured according to JIS K 7126-2:2006.

The amount of oxygen permeation of the resin film (lid material) can be more easily adjusted by, for example, adjusting the types and contents of components contained in the resin film, the thickness of the resin film, and the like.

The tensile strength of the resin film (lid material) at a temperature of 140° C. is 0.3 to 4 N/mm ² . When the tensile strength is equal to or higher than the lower limit value, the followability of the lid material to the object to be packaged (stored object) is improved. When the tensile strength is equal to or less than the upper limit value, it is possible to pack without pressing the object to be packaged (stored object).

The tensile strength of the resin film (lid material) at a temperature of 140° C. may be, for example, 0.8 to 4 N/mm ² , 0.4 to 3.8 N/mm ² , and 0.8 to 4 N/mm 2 . It may be either 3.8 N/mm ² . When the tensile strength is equal to or higher than the lower limit value, the followability of the lid material to the packaged item (stored item) is further improved. When the tensile strength is equal to or less than the upper limit value, it is possible to pack without pressing the object to be packaged (stored object).

The tensile strength of the resin film (lid material) at a temperature of 140° C. can be measured according to JIS K 7127:1999.

The dynamic elastic modulus E′ of the resin film (lid material) at a temperature of 140° C. is preferably 1×10 ⁴ to 1×10 ⁷ Pa. When the dynamic elastic modulus E′ of the resin film (lid material) at a temperature of 140° C. is 1×10 ⁴ to 1×10 ⁷ Pa, the followability of the lid material to the object to be packaged (stored object) is improved. improve more. As a result, dripping from the stored items during storage (for example, refrigerated storage) is suppressed, the outflow of umami components is prevented, and the stored items can be stored for a longer period of time without lowering the taste than before. .

The dynamic elastic modulus E′ of the resin film (lid material) at a temperature of 140° C. is preferably 2×10 ⁴ to 9.8×10 ⁶ Pa, more preferably 3×10 ⁴ to 9.6×10 ⁶ . more preferably 4×10 ⁴ to 9.4×10 ⁶ Pa, for example, 6×10 ⁴ to 1×10 ⁷ Pa, 7×10 ⁴ to 9.8×10 ⁶ Pa, 8×10 ⁴ to 9.6×10 ⁶ Pa, and 9×10 ⁴ to 9.4×10 ⁶ Pa. When the dynamic elastic modulus E′ of the resin film at a temperature of 140° C. is equal to or higher than the lower limit, the followability of the lid material to the packaged item (stored item) is further improved. When the dynamic elastic modulus E′ of the resin film at a temperature of 140° C. is equal to or less than the upper limit, packaging can be performed without pressing the object to be packaged (stored object).

The dynamic elastic modulus E′ of the resin film (lid material) at a temperature of 140° C. can be measured according to JIS K7244-4. Specifically, the dynamic elastic modulus E' can be measured using, for example, a dynamic viscoelasticity measuring device. At this time, for example, using a sample with a width of 4 mm, the dynamic elastic modulus was measured under the conditions of a displacement of 10 μm, a vibration frequency of 1 Hz, and a temperature increase rate of 3° C./min in a temperature range of 25° C. to 160° C. in tensile mode. E' can be measured.

The dynamic elastic modulus E' of the resin film (lid material) can be more easily adjusted by, for example, adjusting the types and contents of components contained in the resin film, the thickness of the resin film, and the like.

The temperature at which the resin film (lid material) exhibits a displacement of 2000 μm is preferably 120° C. or higher during thermomechanical analysis (TMA). When the temperature is equal to or higher than the lower limit value, the heat resistance of the resin film is further improved, and as a result, the conformability of the resin film to the stored items is further improved.

In the thermomechanical analysis of the resin film (lid material), the temperature at which the displacement of 2000 μm is exhibited is more preferably 120 to 225°C, more preferably 123 to 215°C, for example, 130 to 225°C. , and 130 to 215°C. When the temperature is equal to or higher than the lower limit value, the heat resistance of the resin film is further improved, and as a result, the conformability of the resin film to the stored items is further improved. When the temperature is equal to or lower than the upper limit, excessive heat resistance of the resin film is suppressed.

In the thermomechanical analysis of the resin film, the displacement at a temperature of 100° C. is preferably 500 μm or less, more preferably 30 to 500 μm, even more preferably 30 to 400 μm. 300 μm, 30-200 μm, and 30-150 μm. When the displacement is equal to or less than the upper limit value, the melt tension of the resin film is improved, and as a result, the conformability of the resin film to the stored items is further improved. When the displacement is equal to or greater than the lower limit, excessive melt tension of the resin film is suppressed.

The thermomechanical analysis of the resin film is based on JIS K 7196, and the amount of thermal expansion of the sample is measured from the difference in the amount of thermal expansion when the temperature of the standard sample and the sample to be analyzed is increased at a constant rate. It can be done by

In the thermomechanical analysis of the resin film, the temperature at which the displacement of 2000 μm and the displacement at a temperature of 100° C. are obtained by, for example, electron beam irradiation of the resin film. You can adjust by adjusting. For example, when the resin film is a multilayer film to be described later, the temperature and displacement can be more easily adjusted by adjusting the electron beam irradiation conditions for the outer layer or functional layer in the multilayer film.

The resin film is preferably irradiated with electron beams at an absorption dose of 13 to 300 kGy, more preferably electron beam irradiation at an absorption dose of 15 to 250 kGy. Electron beam irradiation may be performed under any condition of 20 to 250 kGy, 45 to 225 kGy, and 70 to 200 kGy. When the absorbed dose is within such a range, both the temperature at which the displacement of 2000 μm and the displacement at a temperature of 100° C. are within the above numerical range during thermomechanical analysis of the resin film. A resin film is obtained more easily. On the other hand, when the absorbed dose is at least the lower limit, the crosslink density of the resin film (in particular, when the resin film is a multilayer film described later, the outer layers and functional layers in the multilayer film) is increased. As a result, the heat resistance and melt tension of the resin film as a whole are further improved. When the absorbed dose is equal to or less than the upper limit, excessive strength of the resin film is suppressed.

The reason why electron beam irradiation improves the crosslink density of the resin film (in particular, when the resin film is a multilayer film described later, the outer layers and functional layers in the multilayer film) is not clear, but the following reasons are not clear. inferred to. That is, when the resin film is irradiated with an electron beam, the carbon-hydrogen bond in the resin (eg, polyethylene, ionomer) is cut, and radicals are generated at the cut bond ends. The generated radicals come into contact with other resin molecular chains (for example, other polyethylene molecular chains, other ionomer molecular chains) due to molecular motion of the molecular chains, extract hydrogen atoms, and form other resin molecular chains ( (For example, other polyethylene molecular chains, other ionomer molecular chains), and as a result, it is assumed that a crosslinked structure is formed.

The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV, more preferably 120 to 280 kV, even more preferably 140 to 260 kV. When the acceleration voltage during electron beam irradiation is within such a range, the temperature at which the displacement of 2000 μm and the displacement at a temperature of 100° C. are both within the above numerical range during thermomechanical analysis of the resin film. The inner resin film can be obtained more easily. On the other hand, when the acceleration voltage during electron beam irradiation is at least the lower limit, the resin film (particularly, when the resin film is a multilayer film described later, the outer layers and functional layers in the multilayer film). The crosslink density is further improved, and as a result, the heat resistance and melt tension of the resin film as a whole are further improved. When the acceleration voltage during electron beam irradiation is equal to or less than the upper limit, excessive strength of the resin film is suppressed.

The gel fraction of the resin film is preferably 30% or more, more preferably 30 to 90%, even more preferably 32 to 87%, for example, 40 to 87%, 48 to 87%. %, and 55 to 87%. When the gel fraction of the resin film is equal to or higher than the lower limit, heat resistance and melt tension of the resin film are further improved, and as a result, conformability to stored items is further improved. When the gel fraction of the resin film is equal to or less than the upper limit, excessive strength of the resin film is suppressed.

The gel fraction of the resin film can be measured according to JIS K 6769 by utilizing the fact that the crosslinked portion of the film does not dissolve in a solvent. That is, the resin film is immersed in an organic solvent such as xylene, the remaining insoluble film is dried, and then the mass of the resulting dried product is measured. The gel fraction can be calculated from the mass of the dried insoluble film. More specifically, for example, a resin film (mass X g) is wrapped with a stainless steel wire mesh (mass Y g), immersed in a heated solvent, and then the resin film wrapped with the stainless steel wire mesh (in other words, the above Remove the insoluble film). Then, it is vacuum-dried, and the mass (Zg) of the resin film (in other words, the insoluble film) wrapped with the stainless wire mesh after drying is measured. and the following formula (1):
Gel fraction (% by mass) of resin film = (ZY)/X x 100 (1)
Then, the gel fraction of the resin film is calculated.

The gel fraction of the resin film is determined, for example, by electron beam irradiation of the resin film (in particular, when the resin film is a multilayer film described later, an outer layer or a functional layer in the multilayer film), It can be adjusted by adjusting the electron beam irradiation conditions at this time. In this case, the electron beam irradiation conditions are the same as those for adjusting the temperature at which a displacement of 2000 μm and the displacement at a temperature of 100° C. are adjusted in the thermomechanical analysis of the resin film described above. Absorbed dose and accelerating voltage for electron beam irradiation can be employed.

It is preferable that the resin film satisfies either one of the above conditions of the temperature at which a displacement of 2000 μm is exhibited in the thermomechanical analysis and the gel fraction, or both of the conditions. That is, for example, the resin film has a temperature of 120° C. or more at which a displacement of 2000 μm is exhibited during thermomechanical analysis, and a gel fraction of less than 30%; Those having a temperature of less than 120°C and a gel fraction of 30% or more; those having a temperature of 120°C or more at which a displacement of 2000 µm is exhibited during thermomechanical analysis and a gel fraction of 30% or more. Some things are mentioned.
Generally, however, the resin film satisfies both of the above conditions, that is, the temperature at which a displacement of 2000 μm is exhibited during thermomechanical analysis is 120° C. or higher, and the gel fraction is 30% or higher. is more preferred.

The thickness of the resin film (lid material) is preferably 60 μm or more, more preferably 70 to 400 μm, even more preferably 80 to 300 μm, and may be, for example, 100 to 200 μm. . When the thickness of the resin film is equal to or greater than the lower limit, the strength of the resin film is further improved. When the thickness of the resin film is equal to or less than the upper limit value, excessive thickness of the resin film is suppressed.

The resin film is preferably a laminated film configured by laminating a plurality of layers.
A preferred example of the resin film which is a laminated film is a multilayer film including an outer layer, a functional layer adjacent to the outer layer, an oxygen barrier layer, and a sealant layer. Such multilayer films are described in detail later.

In the resin film (lid material), it is preferable that all layers have transparency regardless of the type thereof, and that the resin film has transparency, that is, the resin film is a transparent resin film. . In a package constructed using such a resin film, the stored items can be easily visually recognized through the resin film (lid material).

A more detailed configuration of the resin film (lid material) and a manufacturing method thereof will be described in detail separately.

The present invention will be described in more detail below with reference to the drawings. In the drawings used in the following description, in order to make it easier to understand the features of the present invention, there are cases where the main parts are enlarged for convenience, and the dimensional ratio of each component is the same as the actual one. not necessarily.

<<One Embodiment of Resin Film (Lid Material)>>
FIG. 1 is a cross-sectional view schematically showing an example of the multilayer film (laminated film) of the resin film (lid material) in this embodiment.
The multilayer film 1 shown here comprises an outer layer 12 , a functional layer 13 adjacent to the outer layer 12 , an oxygen barrier layer 14 and a sealant layer 11 . In the multilayer film 1, the outer layer 12 is one of the outermost layers, and the sealant layer 11 is the other outermost layer.

Furthermore, the multilayer film 1 includes a pinhole-resistant layer 16 disposed on the sealant layer 11 and disposed between the pinhole-resistant layer 16 and the oxygen barrier layer 14 from the sealant layer 11 side to the outer layer 12 side. and the adhesive layer 15 arranged between the oxygen barrier layer 14 and the functional layer 13 .
That is, the multilayer film 1 includes a sealant layer 11, a pinhole-resistant layer 16, an adhesive layer 15, an oxygen barrier layer 14, an adhesive layer 15, a functional layer 13, and an outer layer 12, which are laminated in this order in the thickness direction, It is configured.

<Sealant layer>
The sealant layer 11 is made of polyethylene-based resin such as ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), ionomer (ION), polyethylene-based copolymer (herein referred to as "polyethylene-based resin (a)"). may be called). Since the sealant layer 11 contains the polyethylene-based resin (a), the multilayer film 1 is improved in easy peelability due to pseudo-adhesiveness to the adherend.

As used herein, the term "polyethylene-based resin" refers to a resin having at least structural units derived from ethylene, and may have only structural units derived from ethylene, or may have structural units derived from ethylene. It may have structural units and other structural units.

As used herein, the term "ionomer" refers to a copolymer of ethylene and a small amount of acrylic acid or methacrylic acid having an ionically crosslinked structure through salt formation between the acid moieties therein and metal ions. means a resin that has
Examples of the metal ions include sodium ions and zinc ions. In this specification, ionomers in which the metal ions are sodium ions are sometimes referred to as "sodium ionomers", and ionomers in which the metal ions are zinc ions are sometimes referred to as "zinc ionomers".

The polyethylene resin (a) contained in the sealant layer 11 may be of only one type, or may be of two or more types. Can be selected arbitrarily.

The sealant layer 11 may contain only the polyethylene resin (a) (that is, it may consist of the polyethylene resin (a)), or the polyethylene resin (a) and other components (In this specification, it may be referred to as "another component") (that is, it may consist of a polyethylene resin (a) and the other component) .

The other components contained in the sealant layer 11 are not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.
The other component, which is a resin component, is a resin that does not correspond to the polyethylene-based resin (a).
The other component, which is a resin component, may be a homopolymer that is a polymer of one type of monomer, or a copolymer that is a polymer of two or more types of monomers.

Examples of the other components, which are non-resin components, include additives known in the art.
Examples of the additives include antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, viscosity reducers, thickeners, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and the like.

The other components contained in the sealant layer 11 may be only one type, or may be two or more types, and when there are two or more types, the combination and ratio thereof may be arbitrarily depending on the purpose. You can choose.

The ratio of the content of the polyethylene resin (a) in the sealant layer 11 to the total mass of the sealant layer 11 is preferably 65 to 100% by mass, more preferably 70 to 100% by mass. It is more preferably ~100% by mass, and may be, for example, 85 to 100% by mass. When the ratio is equal to or higher than the lower limit, the easy peel property is further improved due to the development of pseudo-adhesiveness with the adherend.
The ratio is usually the same as the ratio of the content (parts by mass) of the polyethylene resin (a) to the total content (parts by mass) of the components that do not vaporize at room temperature in the sealant layer-forming composition described later. be.

As used herein, the term "ordinary temperature" means a temperature that is not particularly cooled or heated, that is, a normal temperature.

The sealant layer 11 may consist of one layer (single layer), or may consist of multiple layers of two or more layers. When the sealant layer 11 is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

In this specification, not only in the case of the sealant layer 11, "the plurality of layers may be the same or different" means "all the layers may be the same or all the layers may be different." may be the same, or only some of the layers may be the same", and further, "multiple layers are different from each other" means "at least one of the constituent materials and thickness of each layer is different from each other" means

Although the thickness of the sealant layer 11 is not particularly limited, it is preferably 4 to 96 μm, more preferably 7 to 93 μm, even more preferably 10 to 90 μm. 50 μm, and 10 to 30 μm, or 20 to 90 μm, 30 to 90 μm, and 40 to 90 μm. The strength of the sealant layer 11 becomes higher because the thickness of the sealant layer 11 is equal to or more than the lower limit. When the thickness of the sealant layer 11 is equal to or less than the upper limit, the sealant layer 11 is prevented from becoming excessively thick, and the sealing strength increases when the multilayer film 1 is heated and sealed. .
Here, the "thickness of the sealant layer 11" means the thickness of the entire sealant layer 11. For example, the thickness of the sealant layer 11 consisting of a plurality of layers is the total thickness of all layers constituting the sealant layer 11. means the thickness of

An exposed surface 11a of the sealant layer 11 opposite to the outer layer 12 side (in this specification, may be referred to as a "first surface") 11a is a sealing surface.

<Outer layer>
The outer layer 12 is made of a polyethylene resin such as polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), ionomer (ION), polyethylene copolymer (herein referred to as "polyethylene resin (b1)"). or polyester-based resins such as polyethylene terephthalate-based resins (PET, PETG) (in this specification, the polyethylene-based resin (b1) and the polyester-based resin are collectively referred to as "resin (B)") may contain). Since the outer layer 12 contains the resin (B), the crosslink density of the outer layer 12 can be improved by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side. As a result, the followability of the package (lid material) formed using the multilayer film 1 to the stored items is further improved.

The resin (B) contained in the outer layer 12 may be of only one type, or may be of two or more types. When there are two or more types, the combination and ratio thereof may be arbitrarily selected according to the purpose. can.

The outer layer 12 preferably contains a polyethylene resin (b1) as the resin (B), such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene catalyst linear low density polyethylene ( mLLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), and ionomer (ION). is more preferred. When the outer layer 12 contains such a resin (B), the crosslink density of the outer layer 12 can be further improved by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side.

As used herein, the density of low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and metallocene-catalyzed linear low density polyethylene (mLLDPE) is less than 0.94 g/cm ³ .
The density of medium density polyethylene (MDPE) is 0.94 g/cm ³ or more and less than 0.945 g/cm ³ .
The density of high density polyethylene (HDPE) is 0.945 g/cm ³ or higher.

The outer layer 12 may contain only the resin (B) (that is, may consist of the resin (B)), or the resin (B) and other components (in this specification, may be referred to as "another component") (that is, it may consist of the resin (B) and the other component).

The other components included in the outer layer 12 are not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.
The other component, which is a resin component, is a resin other than the resin (B).

The other components contained in the outer layer 12 may be only one kind, or may be two or more kinds, and when there are two or more kinds, the combination and ratio thereof are arbitrarily selected according to the purpose. can.

The ratio of the resin (B) content in the outer layer 12 to the total weight of the outer layer 12 is preferably 50% by mass or more, more preferably 55 to 100% by mass, and 60 to 100% by mass. More preferably, it may be, for example, 70 to 100% by mass or 85 to 100% by mass. When the ratio is equal to or higher than the lower limit, the crosslink density of the outer layer 12 can be further improved by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side.
The ratio is generally the same as the ratio of the content (parts by mass) of the resin (B) to the total content (parts by mass) of components that do not vaporize at room temperature in the outer layer-forming composition described later.

The outer layer 12 may consist of one layer (single layer), or may consist of two or more layers. When the outer layer 12 is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the outer layer 12 is not particularly limited, but is preferably 4 to 146 μm, more preferably 7 to 143 μm, even more preferably 10 to 140 μm, such as 10 to 110 μm, 10 to 90 μm. , 10 to 70 μm, 10 to 50 μm, and 10 to 30 μm, or 20 to 140 μm and 30 to 140 μm. When the thickness of the outer layer 12 is equal to or greater than the lower limit, the crosslink density of the outer layer 12 can be further improved by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side. Since the thickness of the outer layer 12 is equal to or less than the upper limit value, the excessive thickness of the outer layer 12 is suppressed.
Here, the "thickness of the outer layer 12" means the thickness of the entire outer layer 12. For example, the thickness of the outer layer 12 consisting of a plurality of layers is the total thickness of all layers constituting the outer layer 12. means.

The ratio of the thickness of the outer layer 12 to the thickness of the multilayer film 1 is not particularly limited, but is preferably 10% or more, more preferably 12 to 88%, and more preferably 14 to 86%. More preferably, it may be, for example, 14-60%, 14-40%, or 14-30%, or 30-86%. When the ratio is equal to or higher than the lower limit, the effect obtained by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side becomes higher. When the ratio is equal to or less than the upper limit, it is possible to prevent the thickness of the outer layer 12 from becoming excessive.

<Function layer>
Functional layer 13 adjoins outer layer 12 .
The functional layer 13 is made of polyethylene-based resin such as ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), ionomer (ION), polyethylene-based copolymer (herein referred to as "polyethylene-based resin (c)"). It is preferable that it contains Since the functional layer 13 contains the polyethylene-based resin (c), the crosslink density of the functional layer 13 can be improved when the multilayer film 1 is irradiated with an electron beam from the outside on the outer layer 12 side. As a result, the followability of the package (lid material) formed using the multilayer film 1 to the stored items is further improved.

The polyethylene-based resin (c) contained in the functional layer 13 may be of only one type, or may be of two or more types. Can be selected arbitrarily.

The functional layer 13 preferably contains an ionomer as the polyethylene-based resin (c).

The functional layer 13 may contain only the polyethylene-based resin (c) (that is, may consist of the polyethylene-based resin (c)), or may include the polyethylene-based resin (c) and other components. (In this specification, it may be referred to as "another component") (that is, it may consist of a polyethylene resin (c) and the other component) .

The other components included in the functional layer 13 are not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.
The other component, which is a resin component, is a resin other than the polyethylene-based resin (c).

The other components contained in the functional layer 13 may be of only one type, or may be of two or more types, and when there are two or more types, their combination and ratio may be arbitrarily selected depending on the purpose. You can choose.

The content ratio of the polyethylene-based resin (c) in the functional layer 13 with respect to the total mass of the functional layer 13 is preferably 50% by mass or more, more preferably 55 to 100% by mass, and 60 to 100% by mass. It is more preferably 100% by mass, and may be, for example, 70 to 100% by mass or 85 to 100% by mass. When the ratio is equal to or higher than the lower limit, the crosslink density of the functional layer 13 can be further improved by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side.
The ratio is usually the same as the ratio of the content (parts by mass) of the polyethylene resin (c) to the total content (parts by mass) of the components that do not vaporize at room temperature in the functional layer-forming composition described later. be.

The functional layer 13 may consist of one layer (single layer), or may consist of multiple layers of two or more layers. When the functional layer 13 is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the functional layer 13 is preferably 4 to 146 μm, more preferably 7 to 143 μm, even more preferably 10 to 140 μm, for example 10 to 110 μm, 10 to 80 μm, 10 to 50 μm. , and 10 to 30 μm. When the thickness of the functional layer 13 is equal to or greater than the lower limit, the crosslink density of the functional layer 13 can be further improved by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side. Since the thickness of the functional layer 13 is equal to or less than the upper limit value, the excessive thickness of the functional layer 13 is suppressed.
Here, the "thickness of the functional layer 13" means the thickness of the entire functional layer 13. For example, the thickness of the functional layer 13 consisting of a plurality of layers is the total thickness of all layers constituting the functional layer 13. means the thickness of

The ratio of the thickness of the functional layer 13 to the thickness of the multilayer film 1 is not particularly limited, but is preferably 10% or more, more preferably 11 to 89%, and 12 to 88%. is more preferred. When the ratio is equal to or higher than the lower limit, the effect obtained by irradiating the multilayer film 1 with an electron beam from the outside on the outer layer 12 side becomes higher. When the ratio is equal to or less than the upper limit, excessive thickness of the functional layer 13 is suppressed.

<Oxygen barrier layer>
The oxygen barrier layer 14 provides the multilayer film 1 with a strong oxygen barrier property (in other words, a property of suppressing permeation of oxygen gas).

The oxygen barrier layer 14 is made of ethylene-vinyl alcohol copolymer (EVOH, also known as saponified ethylene-vinyl acetate copolymer) or polyvinylidene chloride (PVDC) (in this specification, EVOH and PVDC are collectively referred to as " (sometimes referred to as "resin (D)"). The oxygen barrier property of the multilayer film 1 provided with such an oxygen barrier layer 14 is further enhanced.

In the ethylene-vinyl alcohol copolymer contained in the oxygen barrier layer, the ratio of the amount of structural units derived from ethylene to the total amount of structural units in the ethylene-vinyl alcohol copolymer (in this specification, "ethylene (sometimes referred to as "copolymerization ratio") is preferably 30 to 50 mol%, more preferably 30 to 40 mol%.

The resin (D) contained in the oxygen barrier layer 14 may be of only one type, or may be of two or more types. When two or more types are used, the combination and ratio thereof may be arbitrary depending on the purpose. can be selected to

The oxygen barrier layer 14 may contain only the resin (D) (that is, may consist of the resin (D)), or may contain the resin (D) and other components (in this specification, may be referred to as "another component") (that is, it may consist of the resin (D) and the other component).

The other components contained in the oxygen barrier layer 14 are not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.
The other component, which is a resin component, is a resin other than the resin (D).
Examples of the other components, which are non-resin components, include the same additives as the other components included in the sealant layer 11 .

The other components contained in the oxygen barrier layer 14 may be of only one type, or may be of two or more types, and when two or more types are used, their combination and ratio may be arbitrarily determined according to the purpose. You can choose.

The ratio of the content of the resin (D) in the oxygen barrier layer 14 to the total mass of the oxygen barrier layer 14 is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, and 70% by mass. It is more preferably ~100% by mass, and may be, for example, 85 to 100% by mass. When the ratio is equal to or higher than the lower limit, the multilayer film 1 has higher oxygen barrier properties.
The ratio is usually the same as the ratio of the content (parts by mass) of the resin (D) to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming an oxygen barrier layer, which will be described later. .

The oxygen barrier layer 14 may consist of one layer (single layer), or may consist of multiple layers of two or more layers. When the oxygen barrier layer 14 is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the oxygen barrier layer 14 is preferably 1 to 100 μm, more preferably 1.5 to 90 μm, even more preferably 2 to 80 μm, for example 4 to 60 μm, 4 to 40 μm, and 4 to 20 μm. When the thickness of the oxygen barrier layer 14 is equal to or greater than the lower limit value, the oxygen barrier property of the multilayer film 1 is further enhanced. Since the thickness of the oxygen barrier layer 14 is equal to or less than the upper limit value, the oxygen barrier layer 14 is prevented from becoming excessively thick.
Here, the “thickness of the oxygen barrier layer 14” means the thickness of the entire oxygen barrier layer 14. For example, the thickness of the oxygen barrier layer 14 consisting of a plurality of layers refers to the thickness of all the oxygen barrier layers 14 constituting the oxygen barrier layer 14. means the total thickness of the layers of

The ratio of the thickness of the oxygen barrier layer 14 to the thickness of the multilayer film 1 is not particularly limited, but is preferably 1% or more, more preferably 2 to 30%, and 3 to 25%. is more preferred. When the ratio is equal to or higher than the lower limit, the multilayer film 1 has higher oxygen barrier properties. When the ratio is equal to or less than the upper limit, the oxygen barrier layer 14 is prevented from becoming excessively thick.

In the case of skin pack packages for foods, the multilayer film constituting the skin pack packages is required to have an oxygen barrier layer in order to suppress oxidative deterioration of the food. However, there is a problem that the presence of the oxygen barrier layer reduces the conformability of the skin pack package to food (property of adhering to food without causing wrinkles). On the other hand, the skin pack package constructed using the multilayer film 1 of the present embodiment having the outer layer 12 and the functional layer 13 solves such problems. The reason for this is that the presence of the outer layer 12 and the functional layer 13 improves the heat resistance and melt tension of the multilayer film 1, and as a result, the multilayer film 1 has excellent followability to the stored items. .
In particular, when the items to be stored are marine products or processed marine products, they are likely to be crushed by pressure and often have complex shapes, making skin pack packaging difficult. A skin-pack package constructed using this material exhibits excellent conformability to such a stored item, and can satisfactorily skin-pack package such a stored item.

<Adhesive layer>
The adhesive layer 15 contains an adhesive.
Adhesive layer 15 adheres two adjacent layers on both sides thereof. In the multilayer film 1, the adhesive layer 15 disposed between the anti-pinhole layer 16 and the oxygen barrier layer 14 bonds the anti-pinhole layer 16 and the oxygen barrier layer 14, and the oxygen barrier layer 14 and the functional layer The adhesive layer 15 disposed between the oxygen barrier layer 14 and the functional layer 13 adheres to each other. In this specification, in order to distinguish these two adhesive layers 15 from each other, the adhesive layer 15 disposed between the anti-pinhole layer 16 and the oxygen barrier layer 14 is referred to as the first adhesive layer, if necessary. The adhesive layer 15 which is called the layer 151 and which is arranged between the oxygen barrier layer 14 and the functional layer 13 is sometimes called the second adhesive layer 152 .
These two adhesive layers 15 (first adhesive layer 151 and second adhesive layer 152) may be the same or different.

The adhesive contained in the adhesive layer 15 is not particularly limited as long as it can adhere two layers to be adhered with sufficient strength.
Examples of the adhesive include adhesive resins such as olefin resins (that is, polymers of olefins that are one or more monomers).

More specific examples of the olefin-based resin contained in the adhesive layer 15 include ethylene-based copolymers, propylene-based copolymers, butene-based copolymers, and the like.
The ethylene-based copolymer is a copolymer of ethylene and a monomer other than ethylene.
The propylene-based copolymer is a copolymer of propylene and a monomer other than propylene.
The butene-based copolymer is a copolymer of butene and a monomer other than butene.

Examples of the ethylene copolymer contained in the adhesive layer 15 include a copolymer of ethylene and a vinyl group-containing monomer.
Examples of copolymers of ethylene and vinyl group-containing monomers include maleic anhydride graft-modified linear low-density polyethylene, ethylene-vinyl acetate copolymer (EVA), and ethylene-methyl acrylate copolymer (EMA). , ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-acrylic Ethyl acid-maleic anhydride copolymers (E-EA-MAH), ionomers (ION), ethylene-based thermoplastic elastomers, and the like can be mentioned.
The ionomer includes, for example, the same ionomers as the ionomers included in the functional layer 13 .

Examples of the propylene-based copolymer contained in the adhesive layer 15 include a copolymer of propylene and a vinyl group-containing monomer.
Examples of copolymers of propylene and vinyl group-containing monomers include maleic anhydride graft-modified linear low-density polypropylene and propylene-based thermoplastic elastomers.

Examples of the butene-based copolymer included in the adhesive layer 15 include a copolymer of 1-butene and a vinyl group-containing monomer, a copolymer of 2-butene and a vinyl group-containing monomer, and modifications of these copolymers. products (modified copolymers) and the like.

The adhesive layer 15 may contain only one kind of adhesive, or two or more kinds thereof, and when two or more kinds of adhesives are contained, the combination and ratio thereof can be arbitrarily selected according to the purpose. .

The adhesive layer 15 may contain only an adhesive (that is, may consist of an adhesive), or may include an adhesive and other components (in this specification, "other components"). ) (that is, it may consist of an adhesive and the other components).

The other components included in the adhesive layer 15 are not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.

The other components contained in the adhesive layer 15 may be of only one type, or may be of two or more types. When there are two or more types, the combination and ratio thereof may be arbitrarily selected depending on the purpose. You can choose.

The content ratio of the adhesive in the adhesive layer 15 to the total mass of the adhesive layer 15 may be, for example, 50 to 100% by mass.
The ratio is usually the same as the ratio of the content (parts by mass) of the adhesive to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming an adhesive layer, which will be described later.

The adhesive layer 15 may consist of one layer (single layer), or may consist of multiple layers of two or more layers. When the adhesive layer 15 is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the adhesive layer 15 is preferably 4 to 96 μm, more preferably 7 to 93 μm, for example, 7 to 80 μm, 7 to 60 μm, 7 to 40 μm, and 7 to 20 μm. may When the thickness of the adhesive layer 15 is equal to or greater than the lower limit value, the adhesive strength between the two layers to be adhered becomes higher. Since the thickness of the adhesive layer 15 is equal to or less than the upper limit value, the excessive thickness of the adhesive layer 15 is suppressed.
Here, the "thickness of the adhesive layer 15" means the thickness of the entire adhesive layer 15 (for example, the thickness of the entire adhesive layer 15 disposed between the anti-pinhole layer 16 and the oxygen barrier layer 14, The total thickness of the adhesive layer 15 disposed between the oxygen barrier layer 14 and the functional layer 13). It means the total thickness of the layers.

<Anti-pinhole layer>
The multi-layer film 1 may not have the pinhole-resistant layer 16, but the pinhole-resistant layer 16 increases its pinhole resistance. In the package constructed using this multilayer film 1, it is possible to suppress the reduction in strength during the heat treatment.

The pinhole-resistant layer 16 is made of polyethylene resin such as ionomer (ION), ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), polyethylene copolymer (herein referred to as "polyethylene resin (d) ) is preferably included. Since the pinhole-resistant layer 16 contains the polyethylene-based resin (d), the pinhole-resistant property of the multilayer film 1 is further enhanced, and the multilayer film 1 is irradiated with an electron beam from the outside on the outer layer 12 side. In this case, the crosslink density of the anti-pinhole layer 16 can be improved. As a result, the followability of the package (lid material) formed using the multilayer film 1 to the stored items is further improved.

The polyethylene-based resin (d) contained in the pinhole-resistant layer 16 may be of only one type, or may be of two or more types. It can be selected arbitrarily.

The pinhole-resistant layer 16 may contain only the polyethylene resin (d) (that is, may consist of the polyethylene resin (d)), or may contain the polyethylene resin (d) and other (In this specification, it may be referred to as "another component") (that is, even if it consists of a polyethylene resin (d) and the other component, good).

The other components contained in the pinhole resistant layer 16 are not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.
The other component, which is a resin component, is a resin other than the polyethylene-based resin (d).

The other components contained in the anti-pinhole layer 16 may be of only one type, or may be of two or more types. Can be selected arbitrarily.

The ratio of the content of the polyethylene resin (d) in the pinhole-resistant layer 16 to the total mass of the pinhole-resistant layer 16 is preferably 50% by mass or more, more preferably 55 to 100% by mass. It is preferably 60 to 100% by mass, and may be, for example, 70 to 100% by mass or 85 to 100% by mass. When the ratio is equal to or higher than the lower limit, the effect obtained by including the polyethylene-based resin (d) in the multilayer film 1 becomes higher.
The ratio is usually the ratio of the content (parts by mass) of the polyethylene resin (d) to the total content (parts by mass) of the components that do not vaporize at room temperature in the pinhole-resistant layer-forming composition described later. are the same.

The pinhole-resistant layer 16 may consist of one layer (single layer), or may consist of multiple layers of two or more layers. When the pinhole resistant layer 16 is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the anti-pinhole layer 16 is preferably 4 to 146 μm, more preferably 7 to 143 μm, even more preferably 10 to 140 μm, such as 10 to 110 μm, 10 to 80 μm, and It may be anywhere from 10 to 50 μm. When the thickness of the pinhole-resistant layer 16 is equal to or greater than the lower limit, the multi-layer film 1 has higher pinhole resistance. By setting the thickness of the pinhole-resistant layer 16 to be equal to or less than the upper limit value, the pinhole-resistant layer 16 is prevented from becoming excessively thick.
Here, the "thickness of the anti-pinhole layer 16" means the thickness of the entire anti-pinhole layer 16. For example, the thickness of the multi-layered anti-pinhole layer 16 is means the total thickness of all the layers that make up the

The ratio of the thickness of the pinhole-resistant layer 16 to the thickness of the multilayer film 1 is not particularly limited, but is preferably 10% or more, more preferably 11 to 89%, and more preferably 12 to 88%. It is even more preferable to have When the ratio is equal to or higher than the lower limit, the multi-layer film 1 has higher pinhole resistance. When the ratio is equal to or less than the upper limit, it is possible to prevent the pinhole-resistant layer 16 from becoming excessively thick.

<Other layers>
The multilayer film 1 includes any of the sealant layer 11, the outer layer 12, the functional layer 13, the oxygen barrier layer 14, the adhesive layer 15, and the anti-pinhole layer 16 within a range that does not impair the effects of the present invention. Other layers may also be provided that do not fall under

The type and arrangement position of the other layer are not particularly limited, and can be arbitrarily selected according to the purpose.

The other layers provided in the multilayer film 1 may be of only one type, or may be of two or more types. Can be selected arbitrarily.

Each of the other layers may consist of one layer (single layer) or may consist of two or more layers. When the other layer is composed of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the other layer can be arbitrarily set according to its type, and is not particularly limited.

When the multilayer film 1 includes the other layer, the multilayer film 1 may further include an adhesive layer (for example, an adhesive layer 15 or the like) for bonding the other layer to other layers.

The thickness of the multilayer film 1 is the same as the thickness of the resin film (lid material) described above.

The multilayer film in this embodiment is not limited to the above-described one, and part of the configuration may be changed, deleted, or added within the scope of the present invention.
For example, the multilayer film may not include any one or more of the pinhole-resistant layer, the adhesive layer, and the functional layer.

Such a modified multilayer film includes, for example, an outer layer, an oxygen barrier layer, and a sealant layer, and does not include a functional layer, and the thickness of the outer layer is the above-described multilayer film including the functional layer. A multilayer film that is set to be thicker than the thickness of the outer layer of the film is also included. Such a multilayer film having no functional layer corresponds to the above-described multilayer film having a functional layer in which the constituent material of the functional layer is the same as the constituent material of the outer layer. In other words, such a multilayer film having no functional layer can be regarded as a multilayer film designed so that the thickness of the outer layer is increased so that the outer layer also functions as a functional layer.
In such a multilayer film having no functional layer, the thickness of the outer layer is not particularly limited, but is preferably 30 to 146 μm, more preferably 30 to 143 μm, and more preferably 30 to 140 μm. is more preferable, and may be, for example, any one of 30-110 μm, 30-90 μm, 30-70 μm, and 30-50 μm. When the thickness of the outer layer is equal to or more than the lower limit, the crosslink density of the outer layer can be further improved by irradiating the multilayer film with an electron beam from the outside on the outer layer side. Furthermore, the followability of the package (lid material) to the stored items is improved to the same extent as in the case of the multilayer film provided with the functional layer. On the other hand, since the thickness of the outer layer is equal to or less than the upper limit value, excessive thickness of the outer layer 12 is suppressed.
Here, the "thickness of the outer layer" has the same meaning as the above-mentioned "thickness of the outer layer 12".

Such a multilayer film without a functional layer may be the same as the multilayer film 1 described above, except that it does not have a functional layer and that it has the outer layer described above.

As the multilayer film of the modified example as described above, for example, it includes an outer layer, a functional layer, an oxygen barrier layer, and a sealant layer, does not include an anti-pinhole layer, and the thickness of the sealant layer is A multilayer film having a thickness greater than that of the sealant layer in the multilayer film provided with the anti-pinhole layer is also included. Such a multilayer film not provided with a pinhole-resistant layer corresponds to the multilayer film provided with the pinhole-resistant layer described above, in which the constituent material of the pinhole-resistant layer is the same as the constituent material of the sealant layer. do. That is, such a multilayer film without a pinhole-resistant layer is considered to be a multilayer film designed so that the thickness of the sealant layer is increased so that the sealant layer also functions as a pinhole-resistant layer. be able to
In such a multilayer film not provided with a pinhole-resistant layer, the thickness of the sealant layer is not particularly limited, but is preferably 40 to 96 μm, more preferably 40 to 93 μm, and more preferably 40 to 90 μm. is more preferable, and may be, for example, 40 to 70 μm or 40 to 50 μm. When the thickness of the sealant layer is equal to or greater than the lower limit, the strength of the sealant layer is further increased. Furthermore, in a package (lid material) constructed using this multilayer film, it is possible to suppress a decrease in strength during heat treatment to the same extent as in the case of a multilayer film having a pinhole-resistant layer. On the other hand, when the thickness of the sealant layer is equal to or less than the above upper limit, the sealant layer is prevented from becoming excessively thick, and the sealing strength becomes higher when the multilayer film is sealed by heating.
Here, the "thickness of the sealant layer" has the same meaning as the above-mentioned "thickness of the sealant layer 11".

A multilayer film not provided with such a pinhole-resistant layer is the same as the multilayer film 1 described above, except that it does not include a pinhole-resistant layer and that it includes the sealant layer described above. It can be.

The resin film of the present embodiment is used as a lid material for a vacuum package for marine products or processed marine products, which includes a lid material and a bottom material, and is particularly suitable for constructing a skin pack package.
Examples of marine products include fish such as red-fleshed fish and white-fleshed fish; crustaceans and the like.
Examples of the processed marine product include cooked fish and boiled fish paste.
Preferred examples of marine products or processed marine products include refrigerated raw meat such as tuna and salmon.

<<Method for manufacturing resin film (lid material)>>
The resin film (lid material) can be produced by a known method depending on the type.
For example, a laminated film such as the multilayer film can be produced by a feed block method in which resins, resin compositions, etc., which are the materials for forming each layer, are melt-extruded using several extruders, or a co-extrusion T die such as a multi-manifold method. method, air-cooled or water-cooled co-extrusion inflation method, or the like.

In addition, the laminated film is obtained by coating the surface of another layer for forming the laminated film with a resin, a resin composition, or the like, which is a material for forming one of the layers therein, and drying it as necessary. Thus, it can be produced by forming a laminated structure in the laminated film and, if necessary, further laminating layers other than these so as to obtain the intended arrangement form.

In addition, the laminated film is obtained by separately preparing two or more films for constituting two or more layers of them in advance, and using an adhesive to laminate these films by a dry lamination method, an extrusion lamination method, It can also be manufactured by laminating and laminating by either a hot-melt lamination method or a wet lamination method, and if necessary, further laminating layers other than these so as to have the intended arrangement form. At this time, an adhesive capable of forming the adhesive layer may be used as the adhesive.

In addition, the laminated film is obtained by laminating two or more films separately prepared in advance as described above by laminating them by a thermal (heat) laminating method or the like without using an adhesive. Accordingly, it can also be produced by further laminating layers other than these so as to obtain a desired arrangement form.

When producing the laminated film, two or more of the methods for forming any layer (film) in the laminated film described above may be combined.

In any case of the production method, the resin composition, which is a material for forming one of the layers in the laminated film, contains the target component (constituent material) of the layer to be formed, and the target content It may be produced by adjusting the type and content of the ingredients so that it is contained in. For example, the content ratio of the components that do not vaporize at room temperature in the resin composition is usually the same as the content ratio of the components in the layer formed from the resin composition.

As a resin composition for forming the sealant layer (the sealant layer 11 in the multilayer film 1 shown in FIG. 1) (herein sometimes referred to as a "sealant layer-forming composition"), for example , the polyethylene-based resin (a), and, if necessary, the other components.

As the resin composition for forming the outer layer (outer layer 12 in the multilayer film 1 shown in FIG. 1) (herein sometimes referred to as "outer layer forming composition"), for example, the resin Those containing (B) and, if necessary, the other components are mentioned.

As the resin composition for forming the functional layer (the functional layer 13 in the multilayer film 1 shown in FIG. 1) (herein sometimes referred to as a "functional layer forming composition"), for example , the polyethylene-based resin (c), and, if necessary, the other components.

As a resin composition for forming an oxygen barrier layer (oxygen barrier layer 14 in the multilayer film 1 shown in FIG. 1) (herein, sometimes referred to as "oxygen barrier layer-forming composition") includes, for example, the resin (D) and, if necessary, the other components.

A resin composition for forming a pinhole-resistant layer (in the multilayer film 1 shown in FIG. 1, the pinhole-resistant layer 16) (in this specification, it may be referred to as a "pinhole-resistant layer-forming composition"). (a) includes, for example, the polyethylene-based resin (d) and, if necessary, the other component.

As the resin composition for forming the adhesive layer (adhesive layer 15 in the multilayer film 1 shown in FIG. 1) (herein sometimes referred to as "adhesive layer forming composition"), for example , the adhesive, and, if necessary, the other components.

<<Bottom Material>>
The bottom material is not particularly limited as long as the resin film is used as a lid material and, together with this lid material, a packaging body (vacuum packaging body) for vacuum packaging marine products or processed marine products can be constructed.
The bottom material may be a known one.

The oxygen permeation amount of the bottom material under conditions of a temperature of 23° C. and a relative humidity of 60% is preferably 300 cc/(m ² ·day·atm) or less, more preferably 260 cc/(m ² ·day·atm). It is more preferably below, for example, 200 cc / (m ² · day · atm) or less, 150 cc / (m ² · day · atm) or less, 100 cc / (m ² · day · atm) or less, and 50 cc / ( m ² · day · atm) or less.
On the other hand, the oxygen permeation amount is 0 cc/(m ² ·day·atm) or more.

The oxygen permeation amount of the bottom material under conditions of a temperature of 23° C. and a relative humidity of 60% can be measured according to JIS K 7126-2:2006.

The oxygen permeation amount of the bottom material can be more easily adjusted by adjusting the types and contents of components contained in the bottom material, the thickness of the bottom material, and the like.

The thickness of the bottom material is preferably 100 μm or more, more preferably 110 μm or more, and even more preferably 120 μm or more. When the thickness of the bottom material is equal to or greater than the lower limit, the strength of the bottom material is further improved.
The thickness of the bottom material is preferably 6000 μm or less. Since the thickness of the bottom material is equal to or less than the upper limit value, excessive thickness of the bottom material is suppressed.
The thickness of the bottom material can be appropriately adjusted within a range set by arbitrarily combining any of the above lower limits and upper limits.

In the bottom material, regardless of the type, all layers may have transparency, the bottom material may have transparency, or all or part of the layers may not have transparency. , the bottom material may not have transparency. In a package constructed using a transparent bottom material, the stored items can be easily visually recognized through the bottom material.

A more detailed configuration of the bottom material and a manufacturing method thereof will be described in detail separately.

<< one embodiment of the bottom material >>
The bottom material is preferably a laminate formed by laminating a plurality of layers.
A preferred example of the bottom material that is a laminate is a resin laminate comprising a foamed resin layer and a non-foamed resin layer provided on the foamed resin layer.

The foamed resin layer may be a known one.
Examples of the foamed resin layer include a resin layer containing a polystyrene resin (PSP) foam.

Although the density of the foamed resin layer is not particularly limited, it is preferably 0.05 to 0.5 g/cm ³ .
The expansion rate of the foamed resin layer is not particularly limited, but is preferably 2 to 20 times. Although the thickness of the foamed resin layer is not particularly limited, it is preferably 500 to 6000 μm.

As the non-foamed resin layer, for example, an easy-peel layer, an oxygen barrier layer, a pinhole-resistant layer, and an adhesive layer are laminated in this order in the thickness direction. film. In the multilayer film for bottom material, the easy peel layer is one of the outermost layers, and the adhesive layer is the other outermost layer.

The multilayer film for bottom material may have, for example, an intermediate adhesive layer between the easy peel layer and the oxygen barrier layer for bonding these two layers.
Further, the multilayer film for bottom material may comprise, for example, an intermediate adhesive layer between the oxygen barrier layer and the pinhole resistant layer for bonding these two layers.
That is, the multilayer film for a bottom material includes an easy peel layer, an intermediate adhesive layer, an oxygen barrier layer, an intermediate adhesive layer, an anti-pinhole layer, and an adhesive layer in this order in the thickness direction. It may be laminated and configured.

In this specification, in order to distinguish these two intermediate adhesive layers from each other, the intermediate adhesive layer disposed between the easy peel layer and the oxygen barrier layer is referred to as the first intermediate adhesive layer as necessary. layer, and the intermediate adhesive layer disposed between the oxygen barrier layer and the pinhole resistant layer may be referred to as a second intermediate adhesive layer.
These two intermediate adhesive layers (first intermediate adhesive layer, second intermediate adhesive layer) may be the same or different.

<Easy peel layer>
Examples of the easy-peel layer in the multilayer film for bottom material include those exhibiting peelability due to cohesive failure.
Examples of the easy peel layer exhibiting peelability due to cohesive failure include those containing two incompatible polyolefins.

The two incompatible polyolefins contained in the easy peel layer in the multilayer film for bottom material include, for example, an ethylene-based polymer having at least structural units derived from ethylene and at least a structural unit derived from propylene. and a propylene-based polymer having
That is, examples of the easy peel layer include those containing an ethylene-based polymer having at least structural units derived from ethylene and a propylene-based polymer having at least structural units derived from propylene.

Examples of the ethylene-based polymer contained in the easy peel layer in the multilayer film for bottom material include ethylene homopolymers and ethylene-based copolymers.

Examples of the homopolymer of ethylene include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene catalyst linear low density polyethylene (mLLDPE), medium density polyethylene (MDPE), and high density polyethylene. (HDPE) and the like.

The ethylene-based copolymer has a structural unit derived from ethylene and a structural unit derived from a monomer other than ethylene.
Examples of the ethylene copolymer include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-acrylic acid Ethyl copolymer (EEA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ionomer (ION) and the like.
The ionomer includes, for example, the same ionomers as those included in the functional layer 13 in the multilayer film 1 described above.

The easy peel layer in the multilayer film for bottom material preferably contains low-density polyethylene as the ethylene-based polymer. The easy peel property of such an easy peel layer is better.

Examples of the propylene-based polymer contained in the easy-peel layer in the multilayer film for bottom material include homopolymers of propylene (that is, polypropylene or homopolypropylene, hPP) and propylene-based copolymers.

The propylene-based copolymer has a structural unit derived from propylene and a structural unit derived from a monomer other than propylene.
Examples of the propylene-based copolymer include propylene-ethylene random copolymer (also: polypropylene random copolymer, rPP), propylene-ethylene block copolymer (also: polypropylene block copolymer, bPP), and the like.

The easy peel layer in the multilayer film for bottom material preferably contains polypropylene as the propylene-based polymer. The easy peel property of such an easy peel layer is better.

The component that exhibits easy peel property contained in the easy peel layer in the multilayer film for bottom material may be one type or two or more types, and when two or more types are used, a combination thereof. and ratio can be arbitrarily selected depending on the purpose. For example, when the components that exhibit easy peel properties are the two types of incompatible polyolefins described above, the easy peel layer may contain only one type of these polyolefins, or two or more types of polyolefins. There may be.

In the easy peel layer in the multilayer film for bottom material, the ratio of the content (parts by mass) of the ethylene-based polymer to the total content (parts by mass) of the ethylene-based polymer and the propylene-based polymer is 10. It is preferably up to 90% by mass, and may be, for example, 30 to 90% by mass, 45 to 90% by mass, or 60 to 90% by mass. When the ratio is equal to or higher than the lower limit, the easy peel property of the easy peel layer becomes better. Peel strength becomes more stable because the said ratio is below the said upper limit.
The ratio is usually the content (mass part) is the same as

The easy-peel layer in the multi-layer film for bottom material contains other components in addition to the components exhibiting easy-peelability (for example, the two incompatible polyolefins described above) within a range that does not impair the easy-peelability. You can
The other components contained in the easy peel layer may be one type or two or more types, and when there are two or more types, the combination and ratio thereof are arbitrary depending on the purpose. can be selected to

In the easy peel layer in the bottom material multilayer film, the ratio of the content of components that exhibit easy peel properties to the total mass of the easy peel layer (for example, the total content of the two incompatible polyolefins described above) ratio) is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, for example, 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, 97 to 100% by mass % by mass, and 99 to 100% by mass. When the ratio is equal to or higher than the lower limit, the easy peel property of the easy peel layer becomes better.
The ratio is usually the ratio of the content (parts by mass) of the component that exhibits easy peelability to the total content (parts by mass) of the components that do not vaporize at room temperature in the easy-peel layer-forming composition for the bottom material described later. Same as percentage.

Examples of the other components contained in the easy peel layer in the multilayer film for bottom material include antifogging agents and antiblocking agents.

The easy-peel layer in the multi-layer film for bottom material may consist of one layer (single layer) or may consist of two or more layers. When the easy peel layer consists of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the easy peel layer in the multilayer film for bottom material is preferably 2 to 50 μm. When the thickness of the easy peel layer is equal to or more than the lower limit, the seal strength of the easy peel layer is moderately high. Easy peel property becomes higher because the thickness of the easy peel layer is equal to or less than the upper limit.
Here, the "thickness of the easy peel layer" means the thickness of the entire easy peel layer. means the thickness of

The ratio of the thickness of the easy peel layer to the thickness of the bottom material multilayer film is not particularly limited, but is preferably 5 to 40%. When the ratio is equal to or higher than the lower limit, the seal strength of the easy peel layer is moderately high. Easy peel property becomes higher because the said ratio is below the said upper limit.

<Oxygen barrier layer>
The oxygen barrier layer imparts an oxygen barrier property (in other words, a property of suppressing permeation of oxygen gas) to the multilayer film for bottom material.

The oxygen barrier layer in the multilayer film for bottom material preferably contains ethylene-vinyl alcohol copolymer (EVOH, also known as ethylene-vinyl acetate copolymer saponified product) or polyamide.

Examples of the ethylene-vinyl alcohol copolymer include the same ethylene-vinyl alcohol copolymers as those included in the oxygen barrier layer 14 in the multilayer film 1 described above.

Examples of the polyamide include 4-nylon, 6-nylon, 7-nylon, 11-nylon, 12-nylon, 46-nylon, 66-nylon, 69-nylon, 610-nylon, 611-nylon, 612-nylon , 6T-nylon, 6I nylon, copolymer of 6-nylon and 66-nylon (nylon 6/66), copolymer of 6-nylon and 610-nylon, copolymer of 6-nylon and 611-nylon, 6-nylon and 12-nylon (nylon 6/12), 6-nylon and 612 nylon copolymer, 6-nylon and 6T-nylon copolymer, 6-nylon and 6I-nylon copolymer, 6-nylon and Copolymers of 66-nylon and 610-nylon, copolymers of 6-nylon, 66-nylon and 12-nylon (nylon 6/66/12), copolymers of 6-nylon, 66-nylon and 612-nylon, 66 - copolymer of nylon and 6T-nylon, copolymer of 66-nylon and 6I-nylon, copolymer of 6T-nylon and 6I-nylon, copolymer of 66-nylon, 6T-nylon and 6I-nylon, etc. .

In terms of heat resistance, mechanical strength, ease of availability, etc., the polyamide is 6-nylon (in this specification, sometimes abbreviated as "Ny6"), 12-nylon, 66-nylon , nylon 6/66, nylon 6/12 or nylon 6/66/12.

The polyamide contained in the oxygen barrier layer in the multilayer film for bottom material may be of only one type, or may be of two or more types. can be selected arbitrarily.

The oxygen barrier layer in the multilayer film for bottom material may contain only one or both of the ethylene-vinyl alcohol copolymer and polyamide (that is, either one of the ethylene-vinyl alcohol copolymer and polyamide or It may be composed of both), and either one or both of the ethylene-vinyl alcohol copolymer and the polyamide, and components other than these (herein, may be referred to as "other components" ) (that is, it may consist of either one or both of an ethylene-vinyl alcohol copolymer and a polyamide, and the other components).

The other component contained in the oxygen barrier layer in the multilayer film for bottom material is not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component. The other component, which is a resin component, is a resin that is neither an ethylene-vinyl alcohol copolymer nor a polyamide.
Examples of the other components, which are non-resin components, include the same additives as the other components contained in the sealant layer 11 in the multilayer film 1 described above.

The other components contained in the oxygen barrier layer in the multilayer film for bottom material may be only one kind, or may be two or more kinds. can be selected arbitrarily according to

The ratio of the total content of the ethylene-vinyl alcohol copolymer and the polyamide to the total weight of the oxygen barrier layer in the multilayer film for bottom material is preferably 50 to 100% by weight, and 60 It is more preferably up to 100% by mass, and may be, for example, 70 to 100% by mass or 85 to 100% by mass.
The above ratio is usually the total content of the ethylene-vinyl alcohol copolymer and the polyamide (mass part) is the same as

The oxygen barrier layer in the multilayer film for bottom material may consist of one layer (single layer) or may consist of multiple layers of two or more layers. When the oxygen barrier layer is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the oxygen barrier layer in the multilayer film for bottom material is preferably 2 to 20 μm. When the thickness of the oxygen barrier layer is equal to or greater than the lower limit, the oxygen barrier property of the oxygen barrier layer becomes higher. When the thickness of the oxygen barrier layer is equal to or less than the upper limit, the oxygen barrier layer is prevented from becoming excessively thick.
Here, the "thickness of the oxygen barrier layer" means the thickness of the entire oxygen barrier layer. means the thickness of

Although the ratio of the thickness of the oxygen barrier layer to the thickness of the bottom material multilayer film is not particularly limited, it is preferably 5 to 15%. When the ratio is equal to or higher than the lower limit, the oxygen barrier property of the bottom material multilayer film becomes higher. When the ratio is equal to or less than the upper limit, it is possible to prevent the oxygen barrier layer from becoming excessively thick.

<Anti-pinhole layer>
The anti-pinhole layer is a layer for protecting the structure of the multilayer film for bottom material, such as by suppressing the generation of pinholes in the multilayer film for bottom material.

The anti-pinhole layer in the multi-layer film for bottom material preferably contains polyolefin.
Examples of the polyolefin include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene catalyst linear low density polyethylene (mLLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), and the like. polyethylene (PE); polypropylene (PP);

The pinhole-resistant layer in the multilayer film for bottom material may contain only polyolefin (that is, may consist of polyolefin), or may contain polyolefin and other components (in this specification, " may be referred to as "another component") (that is, it may consist of a polyolefin and the other component).

The other component contained in the pinhole-resistant layer in the multilayer film for bottom material is not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.
The other component, which is a resin component, is a resin other than polyolefin.
Examples of the other components, which are non-resin components, include the same additives as the other components contained in the sealant layer 11 in the multilayer film 1 described above.

The other component contained in the anti-pinhole layer in the multilayer film for bottom material may be of only one kind, or may be of two or more kinds. It can be arbitrarily selected according to the purpose.

The content of the polyolefin in the pinhole-resistant layer in the bottom multilayer film is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, with respect to the total mass of the pinhole-resistant layer. is more preferable, and may be, for example, 70 to 100% by mass or 85 to 100% by mass.
The ratio is usually the same as the ratio of the polyolefin content (parts by mass) to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming a pinhole-resistant layer for a bottom material, which will be described later. be.

The pinhole-resistant layer in the multilayer film for bottom material may consist of one layer (single layer) or may consist of two or more layers. When the anti-pinhole layer is composed of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the anti-pinhole layer in the multilayer film for bottom material is preferably 2 to 50 μm. When the thickness of the pinhole-resistant layer is equal to or greater than the lower limit, the pinhole-resistant layer has a higher protective ability. When the thickness of the pinhole-resistant layer is equal to or less than the upper limit value, the pinhole-resistant layer is prevented from being excessively thick.
Here, the "thickness of the pinhole-resistant layer" means the thickness of the entire pinhole-resistant layer. means the total thickness of the layers of

Although the ratio of the thickness of the pinhole-resistant layer to the thickness of the bottom material multilayer film is not particularly limited, it is preferably 5 to 40%. When the ratio is equal to or higher than the lower limit, the pinhole resistance of the bottom material multilayer film becomes higher. When the ratio is equal to or less than the upper limit, it is possible to prevent the pinhole-resistant layer from becoming excessively thick.

<Adhesive layer>
The adhesive layer is a layer for adhering the multilayer film for bottom material to the foamed resin layer, and contains an adhesive.

The adhesive is preferably an adhesive resin, more preferably an ethylene-vinyl acetate copolymer resin.
The ethylene-vinyl acetate copolymer resin has a structural unit derived from ethylene and a structural unit derived from vinyl acetate, and may have other structural units other than these, It does not have to be.
Examples of preferred ethylene-vinyl acetate copolymer resins include partially saponified ethylene-vinyl acetate copolymers.

The adhesive contained in the adhesive layer in the multilayer film for bottom material may be of only one type, or may be of two or more types. can be selected arbitrarily.

The adhesive layer in the multilayer film for bottom material may contain only an adhesive (that is, may consist of an adhesive), or may include an adhesive and other components (in the present specification, may be referred to as "another component") (that is, it may consist of an adhesive and the other component).

The other component contained in the adhesive layer in the multilayer film for bottom material is not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.

The other component contained in the adhesive layer in the multilayer film for bottom material may be only one kind, or may be two or more kinds. It can be selected arbitrarily.

The content of the adhesive in the adhesive layer in the bottom material multilayer film may be, for example, 50 to 100% by mass with respect to the total mass of the adhesive layer.
The ratio is usually the same as the ratio of the adhesive content (parts by mass) to the total content (parts by mass) of components that do not vaporize at room temperature in the composition for forming an adhesive layer for a bottom material, which will be described later. .

The adhesive layer in the multilayer film for bottom material may consist of one layer (single layer) or may consist of multiple layers of two or more layers. When the adhesive layer is composed of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the adhesive layer in the multilayer film for bottom material is preferably 2 to 40 μm. When the thickness of the adhesive layer is equal to or greater than the lower limit, the adhesive strength between the two layers to be adhered becomes higher. When the thickness of the adhesive layer is equal to or less than the upper limit value, excessive thickness of the adhesive layer is suppressed.
Here, the "thickness of the adhesive layer" means the thickness of the entire adhesive layer. means.

Although the ratio of the thickness of the adhesive layer to the thickness of the bottom material multilayer film is not particularly limited, it is preferably 5 to 40%. When the ratio is equal to or higher than the lower limit value, the adhesive strength of the two layers to be adhered becomes higher. When the ratio is equal to or less than the upper limit, excessive thickness of the adhesive layer is suppressed.

<First Intermediate Adhesive Layer, Second Intermediate Adhesive Layer>
The first intermediate adhesive layer and the second intermediate adhesive layer contain an adhesive.
The adhesive is preferably an adhesive resin.
Examples of the adhesive resin include polyolefin resins.
The polyolefin-based resin is a resin having structural units derived from an olefin, and may be a modified polyolefin such as an acid-modified polyolefin having an acidic group (eg, acid-modified polyethylene, acid-modified polypropylene).
Examples of polyolefin-based resins include ethylene-based copolymers, propylene-based copolymers, butene-based copolymers, modified products of these copolymers (in other words, modified copolymers), and the like.
The polyolefin-based resin is preferably a random copolymer, a graft copolymer, or a block copolymer from the viewpoint of further improving adhesiveness.

Examples of the ethylene-based copolymer include the ethylene-based copolymers and their modified products (modified copolymers) described above as those included in the easy peel layer in the multilayer film for bottom material.
Examples of the propylene-based copolymer include copolymers of propylene and a vinyl group-containing monomer, modified products thereof (modified copolymers), and the like. More specific examples of such propylene-based copolymers include maleic anhydride graft-modified linear low-density polypropylene and propylene-based thermoplastic elastomers.
Examples of the butene-based copolymer include copolymers of 1-butene and a vinyl group-containing monomer, copolymers of 2-butene and a vinyl group-containing monomer, and modified products of these copolymers (modified copolymers). coalescence) and the like.

The adhesives contained in the first intermediate adhesive layer and the second intermediate adhesive layer may be of only one type, or may be of two or more types. , can be arbitrarily selected according to the purpose.

The first intermediate adhesive layer and the second intermediate adhesive layer may contain only an adhesive (that is, may consist of an adhesive), or may contain an adhesive and other components (this specification In the literature, it may be referred to as "another component") (that is, it may consist of an adhesive and the other component).

The other components included in the first intermediate adhesive layer and the second intermediate adhesive layer are not particularly limited and can be arbitrarily selected according to the purpose, and may be, for example, either a resin component or a non-resin component.

The other components contained in the first intermediate adhesive layer and the second intermediate adhesive layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, combinations and ratios thereof can be arbitrarily selected according to the purpose.

In the first intermediate adhesive layer in the bottom material multilayer film, the content of the adhesive may be, for example, 50 to 100% by mass with respect to the total mass of the first intermediate adhesive layer.
The ratio is usually the ratio of the content (parts by mass) of the adhesive to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming the first intermediate adhesive layer for the bottom material, which will be described later. are the same.
In the second intermediate adhesive layer in the bottom material multilayer film, the content of the adhesive may be, for example, 50 to 100% by mass with respect to the total mass of the second intermediate adhesive layer.
The ratio is usually the ratio of the content (parts by mass) of the adhesive to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming the second intermediate adhesive layer for the bottom material, which will be described later. are the same.

Each of the first intermediate adhesive layer and the second intermediate adhesive layer in the multilayer film for bottom material may consist of one layer (single layer), or may consist of two or more layers. good too. When the first intermediate adhesive layer or the second intermediate adhesive layer consists of multiple layers, these multiple layers may be the same or different from each other. Not limited.

The thicknesses of the first intermediate adhesive layer and the second intermediate adhesive layer in the multilayer film for bottom material are preferably 2 to 15 μm independently. When the thicknesses of the first intermediate adhesive layer and the second intermediate adhesive layer are equal to or greater than the lower limit values, the adhesive strength of the two layers to be adhered becomes higher. Since the thicknesses of the first intermediate adhesive layer and the second intermediate adhesive layer are equal to or less than the upper limit value, the thicknesses of the first intermediate adhesive layer and the second intermediate adhesive layer are prevented from being excessive.
Here, the "thickness of the first intermediate adhesive layer" means the thickness of the entire first intermediate adhesive layer. means the total thickness of all the layers that make up the This is the same for the second intermediate adhesive layer.

The ratio of the thickness of the first intermediate adhesive layer and the second intermediate adhesive layer to the thickness of the bottom material multilayer film is not particularly limited, but is preferably 3 to 20%. When the ratio is equal to or higher than the lower limit value, the adhesive strength of the two layers to be adhered becomes higher. When the ratio is equal to or less than the upper limit, excessive thicknesses of the first intermediate adhesive layer and the second intermediate adhesive layer are suppressed.

<Other layers>
The multilayer film for a bottom material comprises the easy peel layer, the first intermediate adhesive layer, the oxygen barrier layer, the second intermediate adhesive layer, and the anti-pinhole layer within the range that does not impair the effects of the present invention. Other layers that are neither the layer nor the adhesive layer may be provided.

The type and arrangement position of the other layers in the multilayer film for bottom material are not particularly limited, and can be arbitrarily selected according to the purpose.

The other layers included in the bottom material multilayer film may be of only one type, or may be of two or more types. It can be selected arbitrarily.

Each type of the other layer in the multilayer film for bottom material may consist of one layer (single layer) or may consist of two or more layers. When the other layer is composed of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the other layers in the multilayer film for bottom material can be arbitrarily set according to the type thereof, and is not particularly limited.

When the multi-layer film for bottom material comprises the other layer, it may further comprise an intermediate adhesive layer for bonding the other layer to the other layer. In this case, the intermediate adhesive layer is , for example, the same as the first intermediate adhesive layer or the second intermediate adhesive layer described above.

Although the thickness of the non-foamed resin layer of the multi-layer film for bottom material is not particularly limited, it is preferably 40 to 120 μm.

<<Manufacturing method of bottom material>>
The bottom material can be manufactured by a known method depending on its type.
For example, when the bottom material is a resin laminate including the foamed resin layer and the non-foamed resin layer, one surface of the foamed resin layer and one surface of the non-foamed resin layer (non-foamed resin When the layer is the multi-layer film for the base material, the base material can be produced by laminating together the adhesive layer in it by heat lamination. The heat lamination at this time may be performed by, for example, a melt pressure lamination method as described later in Examples, or may be performed by an extrusion lamination method.
Among the non-foamed resin layers, the multilayer film for the bottom material is formed in the same manner as in the case of the resin film (lid material) described above, except that the types of resins or resin compositions that are the forming materials of each layer are different, for example. can be manufactured.

Regardless of the manufacturing method, the resin composition, which is a material for forming any of the layers in the multilayer film for bottom material, contains the desired component (constituent material) for the layer to be formed. The type and content of the ingredients may be adjusted so as to contain the required amount. For example, the content ratio of the components that do not vaporize at room temperature in the resin composition is usually the same as the content ratio of the components in the layer formed from the resin composition.

The resin composition for forming the easy-peel layer in the multilayer film for bottom material (which may be referred to herein as the "composition for forming an easy-peel layer for bottom material") includes, for example, the polyolefin and , and optionally the other components.

Examples of the resin composition for forming the oxygen barrier layer in the bottom material multilayer film (which may be referred to herein as the "bottom material oxygen barrier layer-forming composition") include, for example, ethylene-vinyl Examples include those containing either one or both of an alcohol copolymer and a polyamide, and optionally the other components.

Examples of the resin composition for forming the pinhole-resistant layer in the bottom material multilayer film (which may be referred to herein as a "bottom material pinhole-resistant layer-forming composition") include, for example, Examples include those containing polyolefin and, if necessary, the other components described above.

A resin composition for forming an adhesive layer (in this specification, may be referred to as a "composition for forming an adhesive layer for a bottom material") in a multilayer film for a bottom material, forming a first intermediate adhesive layer (In this specification, it may be referred to as a "first intermediate adhesive layer forming composition for bottom material"), a resin composition for forming a second intermediate adhesive layer (in this specification, may be referred to as "the composition for forming the second intermediate adhesive layer for the bottom material"), any one containing, for example, the adhesive and, if necessary, the other component mentioned.

<< package >>
A packaging body according to one embodiment of the present invention is a vacuum packaging body for marine products or processed marine products, which includes a lid member and a bottom member, and the resin film is used as the lid member.
By using the resin film, the package of the present embodiment suppresses the deterioration of marine products or processed marine products and enables long-term storage without spoiling the flavor. More specifically, since the oxygen permeation amount of the lid material (resin film) is 100 cc/(m ² ·day·atm) or less, the lid material is used together with the bottom material having a low oxygen permeation amount. As a result, the oxygen barrier property of the package is enhanced. Marine products or processed marine products vacuum-packaged in such packages are prevented from being deteriorated due to oxidation or the like during storage, and for example, are prevented from discoloring. Furthermore, since the tensile strength of the lid material (resin film) at a temperature of 140 ° C. is 0.3 N / mm ² or more, the lid material has high followability to marine products or processed marine products (objects to be packaged), Since the tensile strength is 4 N/mm ² or less, the marine product or processed marine product (item to be packaged) can be wrapped in the package without being pressed. As a result, the marine products or processed marine products vacuum-packaged in the packaging body are prevented from dripping during storage, which further inhibits the growth of bacteria in the marine products or processed marine products, thereby improving storage. It does not impair the flavor of marine products or processed marine products. In this way, marine products or processed marine products during storage can be stored for a long period of time while their deterioration is suppressed and their flavor is not impaired.

<<One Embodiment of Package>>
FIG. 2 is a cross-sectional view schematically showing an example of the package of this embodiment.
In the drawings after FIG. 2, the same constituent elements as those shown in already explained figures are given the same reference numerals as in the already explained figures, and detailed explanations thereof will be omitted.

The package 10 shown here comprises the multilayer film (lid material) 1 and the bottom material 8 shown in FIG. The package 10 vacuum-packages a marine product or a processed marine product as a container 9 . That is, the package 10 is a marine product package in which a marine product or a processed marine product is vacuum-packaged as a container 9 with a bottom member 8 and a lid member 1 .
In addition, in FIG. 2, distinction of each layer in the multilayer film 1 is omitted.

In the package 10, the lid material (multilayer film) 1 has an oxygen permeation rate of 100 cc/(m ² ·day·atm) or less under conditions of a temperature of 23° C. and a relative humidity of 60%.
The package 10 has a dynamic elastic modulus E' of 104 or more and 107 Pa or less at a temperature of 140°C.
In the package 10, the tensile strength of the lid material (multilayer film) 1 at a temperature of 140° C. measured according to JIS K 7127:1999 is 0.3 to 4 N/mm ² .

In the package 10, the dynamic elastic modulus E' of the cover material (multilayer film) 1 at a temperature of 140°C is preferably 1 x ¹⁰⁴ to 1 x ¹⁰⁷ Pa.
In the package 10, it is preferable that the temperature at which the lid material (multilayer film) 1 exhibits a displacement of 2000 μm is 120° C. or higher during thermomechanical analysis.
In the package 10, the gel fraction of the cover material (multilayer film) 1 is preferably 30% or more.
In the package 10, the cover material (multilayer film) 1 is preferably irradiated with electron beams at an absorption dose of 13 to 300 kGy.
In the package 10, the displacement at a temperature of 100° C. is preferably 500 μm or less during thermomechanical analysis of the lid material (multilayer film) 1 .

In the package 10, it is preferable that the bottom material 8 has an oxygen permeation rate of 300 cc/(m ² ·day·atm) or less under conditions of a temperature of 23° C. and a relative humidity of 60%.

By using the multi-layer film 1, the package 10 suppresses the deterioration of the marine product or the processed marine product, which is the container 9, and enables long-term storage without spoiling the flavor. In the package 10 , the lid material (multilayer film) 1 has a high followability to the stored object 9 .

One surface 8a of the bottom material 8 (in this specification, sometimes referred to as the “first surface”) 8a is a sealing surface, and a part of the first surface 8a and the sealant layer in the multilayer film 1 A portion of the first surface 11a of 11 is in close contact with a seal. In FIG. 2, the portion where the first surface 8a of the bottom material 8 and the first surface 11a of the sealant layer 11 in the multilayer film 1 are in direct contact is the seal portion. As a result, a storage portion 10a is formed between the first surface 8a of the bottom material 8 and the first surface 11a of the sealant layer 11 . A stored item 9 is sealed in the storage portion 10a.

When the bottom material 8 is the bottom material multilayer film, the first surface 8a of the bottom material 8 is the surface of the easy peel layer opposite to the oxygen barrier layer side.

In FIG. 2, there are some gaps between the contents 9 and the multilayer film 1 and between the contents 9 and the bottom material 8 in the storage part 10a of the package 10. The gap may not exist in the package 10 in which the contents 9 are stored.

The package of this embodiment is not limited to the one shown in FIG. 2, and may be partially changed, deleted, or added to within the scope of the present invention.
For example, FIG. 2 shows the package 10 configured using the multilayer film 1 shown in FIG. may be

<<Method for manufacturing package>>
The package of the present embodiment can be produced by vacuum packaging an object to be packaged (a marine product or a processed marine product) using the resin film. The package of the present embodiment can be manufactured in the same manner as the conventional package, except that the resin film is used instead of the conventional film. A test package, which will be described later, can also be produced in the same manner.

In the package of the present embodiment, for example, an object to be packaged (marine products or processed marine products) is placed on the surface of the bottom material that is sealed with the lid material, and the surface of the bottom material and the An object to be packaged is covered with the lid material from above, and a region between the bottom material and the lid material where the object to be packaged is arranged is vacuumed to wrap the lid material. It can be produced by heat-sealing the bottom member and the lid member in a region where the packaging object is not arranged while being tightly fixed to the object. When the bottom material is the multilayer film for the bottom material, the surface of the bottom material (the surface to be sealed with the lid material) is the surface of the easy peel layer opposite to the oxygen barrier layer side. .

The pressure in the area where the packaging objects are placed is preferably 5,000 Pa (50 mbar) or less, and may be, for example, 300 to 5,000 Pa, due to the evacuation during heat sealing. When the pressure is equal to or less than the upper limit, the followability (adherence) of the lid material to the object to be packaged is higher, and a package body with higher storage aptitude for the object to be packaged (stored object) can be obtained. Since the pressure is equal to or higher than the lower limit, an excessive degree of vacuum can be avoided.

Although the sealing temperature during heat sealing is not particularly limited, it is preferably 100 to 170°C. When the sealing temperature is equal to or higher than the lower limit, the sealing strength of the package becomes higher while maintaining easy peelability. When the sealing temperature is equal to or lower than the upper limit, it becomes easier to open the package.

The sealing time during heat sealing can be appropriately adjusted according to the sealing temperature, but is usually preferably 10 to 30 seconds. When the sealing time is equal to or longer than the lower limit, the sealing strength of the package becomes higher while maintaining easy peelability. When the sealing time is equal to or less than the upper limit, it becomes easier to open the package.

The sealing pressure at the time of heat sealing can be appropriately adjusted according to the sealing temperature, but is usually preferably 0.1 to 1 MPa. When the sealing pressure is equal to or higher than the lower limit, the sealing strength of the package becomes higher while maintaining easy peelability. When the sealing pressure is equal to or lower than the upper limit, the package can be opened more easily.

<<How to store marine products or processed marine products>>
The package of the present embodiment, which is obtained by vacuum packaging marine products or processed marine products using the resin film, suppresses deterioration of the marine products or processed marine products, without impairing their flavor, Long-term storage is possible.
For example, the temperature during storage of the package (storage temperature) is preferably -60 to 10°C. When the storage temperature is equal to or lower than the upper limit, deterioration of marine products or processed marine products is suppressed, and the period of storage without spoiling the flavor becomes longer. When the storage temperature is equal to or higher than the lower limit, the stability of the package (lid material and bottom material) is further improved within a more realistic temperature range.
The storage period of the package that can store marine products or processed marine products while suppressing their deterioration and losing their flavor can be, for example, 5 days or more if they are cut into pieces under refrigerated conditions. is.

The present invention will be described in more detail below with reference to specific examples. However, the present invention is by no means limited to the examples shown below.

[Example 1]
<<Manufacturing of multilayer film (lid material)>>
A multilayer film having the structure shown in FIG. 1 was manufactured by the procedure shown below.
That is, an ethylene-vinyl acetate copolymer (EVA, “V5714C” manufactured by Dow Mitsui Polychemicals, Inc.) was prepared as a resin constituting the sealant layer.
Low-density polyethylene (LDPE, density 0.922 g/cm ³ , "F222NH" manufactured by Ube Maruzen Polyethylene Co., Ltd.) was prepared as the resin constituting the outer layer. In this specification, this LDPE may be referred to as "LDPE (1)".
A sodium-based ionomer (ION, “1601” manufactured by Mitsui DuPont Polychemicals Co., Ltd.) was prepared as a resin constituting the functional layer and the pinhole-resistant layer.
As a resin constituting the oxygen barrier layer, an ethylene-vinyl alcohol copolymer (EVOH, “GH3804B” manufactured by Nippon Gosei Co., Ltd., the ethylene copolymerization ratio of 38 mol %) was prepared. In this specification, this EVOH may be referred to as "EVOH (1)".
Maleic anhydride-modified polyethylene (modified PE, “NF536” manufactured by Mitsui Chemicals, Inc.) was prepared as an adhesive (adhesive resin) constituting the adhesive layers (first adhesive layer and second adhesive layer). In this specification, this modified PE is sometimes referred to as "modified PE (1)".

The temperature of the die was set to 250° C., and the EVA, the ION, the modified PE (1), the EVOH (1), the modified PE (1), the ION, and the LDPE (1) were , By coextrusion (coextrusion T-die method) in this order, a sealant layer (24 μm thick), a pinhole resistant layer (29 μm thick), an adhesive layer (first adhesive layer, 8 μm thick), an oxygen barrier A layer (thickness 10 μm), an adhesive layer (second adhesive layer, thickness 8 μm), a functional layer (thickness 17 μm) and an outer layer (thickness 24 μm) are laminated in this order in the thickness direction. A multilayer film (120 μm thick) was produced.

Next, the multilayer film obtained above was irradiated with an electron beam from the outside on the outer layer side under the conditions of an absorption dose of 175 kGy and an acceleration voltage of 160 kV.
As described above, the target electron beam-irradiated multilayer film (hereinafter sometimes referred to as “lid material (I)”) was obtained.

<<Evaluation of multilayer film (lid material)>>
<Measurement of tensile strength at 140°C>
The electron beam-irradiated multilayer film (lid material (I)) obtained above was measured using a tensile strength measuring device ("AGS-X" manufactured by Shimadzu Corporation) in accordance with JIS K 7127:1999. , tensile strength was measured under the conditions of a tensile speed of 500 mm/min. Table 1 shows the results.

<Measurement of dynamic elastic modulus at 140°C>
For the electron beam-irradiated multilayer film (lid material (I)) obtained above, a dynamic viscoelasticity measuring device (“DMA 7100” manufactured by Hitachi High-Tech Science Co., Ltd.) was used to measure according to JIS K 7244-4. Then, using a sample with a width of 4 mm, the dynamic elastic modulus E' was obtained under the conditions of a displacement of 10 µm, a vibration frequency of 1 Hz, and a temperature increase rate of 3 ° C./min in a temperature range of 25 ° C. to 160 ° C. in tensile mode. It was measured. Table 1 shows the results.

<Temperature indicating displacement of 2000 μm, identification of displacement at temperature of 100° C.>
The electron beam-irradiated multilayer film (lid material (I)) obtained above was subjected to thermomechanical analysis using a thermal analysis device (manufactured by SII "EXSTAR6000") in accordance with JIS K 7196. Ta. Then, from the obtained thermomechanical analysis curve, the temperature (° C.) at which the displacement of 2000 μm and the displacement (μm) at the temperature of 100° C. were determined. Table 1 shows the results.

<Measurement of gel fraction>
The gel fraction of the electron beam-irradiated multilayer film (lid (I)) obtained above was measured according to JIS K 6769.
That is, a test piece having a size of 3 cm x 3 cm (about 0.09 g) was cut out from the multilayer film, wrapped in a 400-mesh stainless steel wire mesh (100 g), and placed in xylene (18 mL) at 110°C. It was immersed for 24 hours.
Next, the test piece was taken out from the xylene together with the wire mesh, and vacuum-dried at 110° C. for 24 hours under a pressure of 1.7 kPa to obtain a dried test piece after immersion. The mass of the obtained dried product was measured, and the gel fraction (%) of the electron beam-irradiated multilayer film was determined. Table 1 shows the results.

<Measurement of oxygen permeation amount>
Regarding the electron beam irradiated multilayer film (lid material (I)) obtained above, the oxygen transmission rate ( cc/(m ² ·day · atm)) was measured. Table 1 shows the results.

<<Manufacturing of bottom material>>
<Manufacturing of multilayer film for bottom material>
A multilayer film for a bottom material was produced by the procedure described below.
That is, low-density polyethylene (LDPE, "L211" manufactured by Sumitomo Chemical Co., Ltd.) and polypropylene (PP, "FS2011DG2" manufactured by Sumitomo Chemical Co., Ltd.) were prepared as resins constituting the easy peel layer. In this specification, this LDPE may be referred to as "LDPE(2)".
Metallocene-catalyzed linear low-density polyethylene (mLLDPE) (“Umerit (registered trademark) 1520F” manufactured by Ube Maruzen Polyethylene Co., Ltd., density 0.913 g/cm ³ ) was prepared as a resin constituting the pinhole-resistant layer. In this specification, this mLLDPE may be referred to as "mLLDPE (1)".
An ethylene-vinyl alcohol copolymer (EVOH, “J171B” manufactured by Kuraray Co., Ltd., density 1180 kg/m ³ , MFR 4.2 g/10 min, ethylene copolymerization ratio 32 mol%) was prepared as the resin constituting the oxygen barrier layer. did. In this specification, this EVOH may be referred to as "EVOH (2)".
Acid-modified polypropylene (modified PP, adhesive resin, "ADMER QF551" manufactured by Mitsui Chemicals, Inc.) was prepared as a resin constituting the first intermediate adhesive layer.
Acid-modified polyethylene (modified PE, adhesive resin, "ADMER NF536" manufactured by Mitsui Chemicals, Inc.) was prepared as a resin constituting the second intermediate adhesive layer. In this specification, this modified PE is sometimes referred to as "modified PE (2)".
As the resin constituting the adhesive layer, an ethylene-vinyl acetate copolymer resin (EVA resin, adhesive resin, "Mersen (registered trademark) MX02D" manufactured by Tosoh Corporation) was prepared.

The LDPE (2) (70 parts by mass) and the PP (30 parts by mass) were mixed at room temperature to prepare a composition for forming an easy peel layer for a bottom material.

The temperature of the die is 250 ° C., and the composition for forming an easy peel layer for a bottom material, the modified PP, the EVOH (2), the modified PE (2), the mLLDPE (1), and the EVA By co-extrusion (co-extrusion T-die method) in this order with the system resin, an easy peel layer (thickness 25.9 μm), a first intermediate adhesive layer (thickness 5.6 μm), an oxygen barrier layer (thickness thickness 8.4 μm), a second intermediate adhesive layer (thickness 5.6 μm), a pinhole-resistant layer (thickness 10.5 μm) and an adhesive layer (thickness 14 μm) are laminated in this order in their thickness direction. A multilayer film (thickness 70 μm) for a bottom material was manufactured.

<Manufacturing of bottom material>
A foamed resin sheet (manufactured by Chuo Kagaku Co., Ltd., thickness 3000 μm) containing a polystyrene resin (PSP) foam was used, and on one surface thereof, the exposed surface of the adhesive layer of the multilayer film for bottom material obtained above was applied. A bottom material (hereinafter sometimes referred to as “bottom material (α)”) was obtained by laminating them together by heat lamination. The heat lamination of the foamed resin sheet and the multi-layer film for bottom material was performed by melt pressure lamination using a roll apparatus equipped with melt pressure rolls. The melt pressure bonding roll includes a heating roll and an opposing roll provided opposite to the heating roll. They were laminated together by melt-pressing the films at 180°C.

<<Evaluation of bottom material>>
<Measurement of oxygen permeation amount>
Regarding the bottom material (bottom material (α)) obtained above, the oxygen permeation amount (cc/(m ²・day·atm)) was measured. Table 4 shows the results.

<<Production of package (test package)>>
Using a continuous skin pack packaging machine (“T300” manufactured by Multivac), the sealant layer in the lid material (I) obtained above and the easy peel layer in the bottom material (α) are opposed, A marine product (Atlantic salmon fillets (200 g)) was placed between the lid material (I) and the bottom material (α). Then, while evacuating the place where the fishery product is placed, the peripheral portions of the lid material (I) and the bottom material (α) are heated at a hot plate temperature (sealing temperature) of 140 ° C., a sealing time of 10 seconds, and a sealing pressure of 0.3 MPa. A package (skin pack package, test package) was produced by heat-sealing under the conditions of . During evacuation, the pressure in the area where the seafood was placed was 1000 Pa (10 mbar). As the bottom material (α), one having a size of 20 cm×20 cm was used.

<<Evaluation of package (test package)>>
<Confirming the presence or absence of discoloration of stored items>
The package obtained above was stored frozen at -30°C in an air atmosphere immediately after its production. Then, 14 days after the start of frozen storage, the package was thawed to 4° C. over 16 hours. The unopened package immediately after thawing was visually observed from the outside on the lid side, and according to the following criteria, if no discoloration was observed in the contents (seafood), it was judged as A, and discoloration was observed. If so, it was judged as B. Table 5 shows the results.

<Evaluation of followability of lid material to stored items>
At the time of confirming the presence or absence of discoloration of the contents described above, at the same time, followability of the lid material to the contents (marine products) was evaluated according to the following criteria. Table 5 shows the results.
[Evaluation criteria]
A: There is no or very little lifting of the lid material from the stored material, and the followability is high.
B: Inferior to A, but less lifting of the lid material from the stored material, and good followability.
C: The lid material is often lifted from the stored items, and the followability is low.
D: The lid material does not follow the contents.

<Evaluation of effect of suppressing drip generation>
Immediately after production, the package obtained above was refrigerated at 4° C. for 4 days under an air atmosphere, separately from the package used for each of the above evaluations. Next, immediately take out the contents (seafood) from the unopened package after refrigerated storage, leave it for 5 minutes, and visually observe the amount of drip generation and the degree of turbidity. The inhibitory effect was evaluated. Table 5 shows the results.
[Evaluation criteria]
A: No drip occurred, or the amount of drip generated was extremely small, and the effect of suppressing the occurrence of drip was high.
B: Inferior to A, but the amount of drip generated is small, the drip is less turbid, and the effect of suppressing the generation of drip is recognized.
C: A large amount of drip was generated, and the drip was highly turbid, and the effect of suppressing the generation of drip was not observed or was low.

<Evaluation of Flavor of Stored Items>
A test piece with a size of 1 cm × 3.5 cm × 4.5 cm was cut out from the stored items (marine products) taken out when evaluating the effect of suppressing the occurrence of drip, and a hot plate heated to 220 ° C. was used to cut this test piece. The surface of the test piece was heated for 60 seconds, and the back surface was heated for 90 seconds. Next, the test piece after heating was divided into three equal parts, and each piece was used as a test piece for evaluation for one person. Seven panelists (sensory testers) tasted the test pieces for evaluation, and evaluated the flavor when chewed according to the following criteria. Table 5 shows the results.
[Evaluation criteria]
A: Good flavor as a marine product.
B: Inferior to A, but has flavor as a marine product.
C: Almost no flavor as a marine product.

<<Production and evaluation of multilayer film (lid material), production and evaluation of bottom material, production and evaluation of package (test package)>>
[Example 2]
An electron beam-irradiated multilayer film (hereinafter referred to as “lid material (II)”) was prepared in the same manner as in Example 1, except that the absorbed dose was changed to 120 kGy instead of 175 kGy when the multilayer film was irradiated with an electron beam. ) was manufactured and evaluated.
The multilayer film (lid material) was evaluated in the same manner as in Example 1, except that this electron beam-irradiated multilayer film (lid material (II)) was used. package) was manufactured and evaluated. Results are shown in Tables 1, 4 and 5.

[Example 3]
An electron beam-irradiated multilayer film (hereinafter referred to as “lid material (III)”) was prepared in the same manner as in Example 1, except that the absorbed dose was changed to 90 kGy instead of 175 kGy when the multilayer film was irradiated with an electron beam. ) was manufactured and evaluated.
The multilayer film (lid material) was evaluated in the same manner as in Example 1, except that this electron beam-irradiated multilayer film (lid material (III)) was used. package) was manufactured and evaluated. Results are shown in Tables 1, 4 and 5.

[Example 4]
An electron beam-irradiated multilayer film (hereinafter referred to as "lid material (IV)") was prepared in the same manner as in Example 1, except that the absorbed dose was changed to 15 kGy instead of 175 kGy when the multilayer film was irradiated with an electron beam. ) was manufactured and evaluated.
The multilayer film (lid material) was evaluated in the same manner as in Example 1, except that this electron beam-irradiated multilayer film (lid material (IV)) was used. package) was manufactured and evaluated. Results are shown in Tables 1, 4 and 5.

[Example 5]
Metallocene-catalyzed linear low-density polyethylene (mLLDPE, “4040FC” manufactured by Ube Maruzen Polyethylene Co., Ltd., melting point 126° C., density 0.938 g/cm ³ ) was prepared as the resin constituting the outer layer. In this specification, this mLLDPE may be referred to as "mLLDPE (2)".
Then, a multilayer film was produced in the same manner as in Example 1, except that the mLLDPE (2) was used instead of the LDPE (1).
The multilayer film produced in this example includes a sealant layer (24 μm thick), a pinhole resistant layer (29 μm thick), an adhesive layer (first adhesive layer, 8 μm thick), an oxygen barrier layer (10 μm thick), A multilayer film (thickness: 120 μm) composed of an adhesive layer (second adhesive layer, thickness 8 μm), a functional layer (thickness 17 μm), and an outer layer (thickness 24 μm) laminated in this order in the thickness direction. is.
Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (VII)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1, except that this cover material (VII) was used instead of the cover material (I). . Results are shown in Tables 2, 4 and 5.

[Example 6]
High-density polyethylene (HDPE, “3300F” manufactured by Prime Polymer Co., Ltd., density 0.949 g/cm ³ ) was prepared as the resin constituting the outer layer.
Then, a multilayer film was produced in the same manner as in Example 1, except that HDPE was used instead of LDPE (1).
The multilayer film produced in this example includes a sealant layer (24 μm thick), a pinhole resistant layer (29 μm thick), an adhesive layer (first adhesive layer, 8 μm thick), an oxygen barrier layer (10 μm thick), A multilayer film (thickness: 120 μm) composed of an adhesive layer (second adhesive layer, thickness 8 μm), a functional layer (thickness 17 μm), and an outer layer (thickness 24 μm) laminated in this order in the thickness direction. is.
Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (VIII)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1 except that this lid material (VIII) was used instead of the lid material (I). . Results are shown in Tables 2, 4 and 5.

[Example 7]
A multilayer film was produced in the same manner as in Example 1, except that the EVA was used instead of the LDPE (1) as the resin constituting the outer layer.
The multilayer film produced in this example includes a sealant layer (24 μm thick), a pinhole resistant layer (29 μm thick), an adhesive layer (first adhesive layer, 8 μm thick), an oxygen barrier layer (10 μm thick), A multilayer film (thickness: 120 μm) composed of an adhesive layer (second adhesive layer, thickness 8 μm), a functional layer (thickness 17 μm), and an outer layer (thickness 24 μm) laminated in this order in the thickness direction. is.
Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (IX)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1 except that this lid material (IX) was used instead of the lid material (I). . Results are shown in Tables 2, 4 and 5.

[Example 8]
The ION was prepared as the resin constituting the outer layer.
The die temperature is set to 250° C., and the EVA, the ION, the modified PE (1), the EVOH (1), the modified PE (1), and the ION are co-extruded in this order. By (co-extrusion T-die method), a sealant layer (24 μm thick), a pinhole resistant layer (29 μm thick), an adhesive layer (first adhesive layer, 8 μm thick), an oxygen barrier layer (10 μm thick), A multilayer film (120 μm thick) was produced by laminating an adhesive layer (second adhesive layer, 8 μm thick) and an outer layer (41 μm thick) in this order in the thickness direction.
Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (X)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1 except that this lid material (X) was used instead of the lid material (I). . Results are shown in Tables 2, 4 and 5.

[Example 9]
The EVA was prepared as the resin constituting the functional layer.
The temperature of the die was 250° C., and the EVA, the modified PE (1), the EVOH (1), the modified PE (1), the EVA, and the LDPE (1) were heated in this order. By co-extrusion (co-extrusion T-die method), a sealant layer (thickness 53 μm), an adhesive layer (first adhesive layer, thickness 8 μm), an oxygen barrier layer (thickness 10 μm), an adhesive layer (second adhesive layer , thickness 8 μm), a functional layer (thickness 17 μm) and an outer layer (thickness 24 μm) were laminated in this order in the thickness direction to produce a multilayer film (thickness 120 μm).
Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (XI)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1 except that this lid material (XI) was used instead of the lid material (I). . Results are shown in Tables 2, 4 and 5.

[Example 10]
Same as Example 1 except that 6-nylon (Ny6, “1030B2” manufactured by Ube Industries, Ltd., melting point 225° C.) was used as the resin constituting the oxygen barrier layer instead of EVOH (2). The method produced a multilayer film for the substrate.
The multilayer film for bottom material produced in this example includes an easy peel layer (25.9 μm thick), a first intermediate adhesive layer (5.6 μm thick), an oxygen barrier layer (8.4 μm thick), a second A multi-layered base material comprising an intermediate adhesive layer (thickness 5.6 μm), a pinhole resistant layer (thickness 10.5 μm) and an adhesive layer (thickness 14 μm) laminated in this order in the thickness direction. It is a film (thickness 70 μm) (hereinafter sometimes referred to as “bottom material (β)”).
Hereinafter, this bottom material (β) was evaluated in the same manner as in Example 1, and the lid material (I) and Packages (test packages) were produced and evaluated. Results are shown in Tables 1, 4 and 6.

[Comparative Example 1]
A multilayer film having a structure different from that of the multilayer film shown in FIG. 1 was manufactured by the procedure described below.
That is, low-density polyethylene (LDPE, density 0.922 g/cm ³ , "F222NH" manufactured by Ube Maruzen Polyethylene Co., Ltd.) was prepared as a resin constituting the sealant layer. In this specification, this LDPE may be referred to as "LDPE(3)".
Amorphous polyethylene terephthalate (PETG, "S2008" manufactured by SK Chemicals) was prepared as the resin constituting the outer layer.

The temperature of the die is 250° C., and the LDPE (3), the modified PE (1), the Ny6, the EVOH (1), the modified PE (1), and the PETG are added in this order. By co-extrusion (co-extrusion T-die method), a sealant layer (thickness 29 μm), an adhesive layer (first adhesive layer, thickness 6 μm), a pinhole resistant layer (thickness 20 μm), an oxygen barrier layer (thickness 12 μm), an adhesive layer (second adhesive layer, 8 μm thick), and an outer layer (45 μm thick) laminated in this order in the thickness direction to produce a multilayer film (thickness 120 μm).

Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (XII)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1, except that this lid material (XII) was used instead of the lid material (I). . Results are shown in Tables 3, 4 and 6.

[Comparative Example 2]
An ethylene-methacrylic acid copolymer (EMAA, "N0903HC" manufactured by Dow Mitsui Polychemicals) was prepared as a resin constituting the cushion layer.

The temperature of the die is 250° C., and the ION, the EMAA, the modified PE (1), the Ny6, the EVOH (1), the modified PE (1), and the Ny6 are heated in this order. By co-extrusion (co-extrusion T-die method), a sealant layer (thickness 24 μm), a cushion layer (thickness 40 μm), an adhesive layer (first adhesive layer, thickness 8 μm), a pinhole resistant layer (thickness 24 μm), an oxygen barrier layer (thickness 6 μm), an adhesive layer (second adhesive layer, thickness 10 μm), and an outer layer (thickness 8 μm) laminated in this order in the thickness direction. (thickness 120 μm) was manufactured.

Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (XIII)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1 except that this lid material (XIII) was used instead of the lid material (I). . Results are shown in Tables 2, 4 and 6.

[Comparative Example 3]
The temperature of the die is 250° C., and the LDPE (3), the EMAA, the modified PE (1), the Ny6, the EVOH (1), the modified PE (1), and the Ny6 are , By co-extrusion (co-extrusion T-die method) in this order, a sealant layer (thickness 8 μm), a cushion layer (thickness 46 μm), an adhesive layer (first adhesive layer, thickness 8 μm), and a pinhole resistant layer (thickness 30 μm), oxygen barrier layer (thickness 6 μm), adhesive layer (second adhesive layer, thickness 10 μm), and outer layer (thickness 12 μm) are laminated in this order in the thickness direction. A multilayer film (120 μm thick) was produced.

Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (XIV)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1 except that this lid material (XIV) was used instead of the lid material (I). . Results are shown in Tables 2, 4 and 6.

[Comparative Example 4]
A cover material (multilayer film not irradiated with electron beams, hereinafter sometimes referred to as "cover material (V)") was prepared in the same manner as in Example 1 except that the multilayer film was not irradiated with an electron beam. ) were manufactured and evaluated.
Hereinafter, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1, except that this electron beam non-irradiated multilayer film (lid material (V)) was used. did. Results are shown in Tables 1, 4 and 6.

[Comparative Example 5]
The temperature of the die is 250 ° C., and the composition for forming an easy peel layer for a bottom material, the modified PP, the mLLDPE (1), the modified PE (2), the mLLDPE (1), and the EVA By co-extrusion (co-extrusion T-die method) in this order with the system resin, an easy peel layer (thickness 25.9 μm), a first intermediate adhesive layer (thickness 5.6 μm), an oxygen barrier layer (thickness thickness 8.4 μm), a second intermediate adhesive layer (thickness 5.6 μm), a pinhole-resistant layer (thickness 10.5 μm) and an adhesive layer (thickness 14 μm) are laminated in this order in their thickness direction. A multilayer film for a bottom material (thickness: 70 μm) (hereinafter sometimes referred to as “bottom material (γ)”) was manufactured.
Hereinafter, this bottom material (γ) was evaluated by the same method as in Example 1, and the lid material (I) and Packages (test packages) were produced and evaluated. Results are shown in Tables 1, 4 and 6.

[Comparative Example 6]
A multilayer film was produced in the same manner as in Example 1, except that Ny6 was used instead of EVOH (1) as the resin constituting the oxygen barrier layer.
The multilayer film produced in this example includes a sealant layer (24 μm thick), a pinhole resistant layer (29 μm thick), an adhesive layer (first adhesive layer, 8 μm thick), an oxygen barrier layer (10 μm thick), A multilayer film (thickness: 120 μm) composed of an adhesive layer (second adhesive layer, thickness 8 μm), a functional layer (thickness 17 μm), and an outer layer (thickness 24 μm) laminated in this order in the thickness direction. is.
Hereinafter, an electron beam-irradiated multilayer film (hereinafter sometimes referred to as "lid material (VI)") was produced and evaluated in the same manner as in Example 1, except that this multilayer film was used. did. Then, a bottom material and a package (test package) were produced and evaluated in the same manner as in Example 1, except that this lid material (VI) was used instead of the lid material (I). . Results are shown in Tables 1, 4 and 6.

[Comparative Example 7]
The two cover materials (I) obtained above are arranged so that the sealant layers therein face each other, and a marine product (Atlantic salmon fillet (200 g)) is placed between these cover materials (I). was placed. Then, while degassing the place where the seafood is arranged, the peripheral edges of the lid material (I) are heat-sealed under the conditions of a sealing temperature of 140 ° C., a sealing time of 2 seconds, and a sealing pressure of 0.3 MPa. A body (a degassing seal package, a test package) was produced.
This package (test package) was evaluated in the same manner as in Example 1 below. Results are shown in Tables 1 and 6. Since no bottom material is used in this comparative example, "-" is indicated in the "bottom material" column in Table 6.

As is clear from the above results, in Examples 1 to 10, discoloration of the stored items was suppressed, and deterioration such as oxidation of the stored items was suppressed. In addition, in Examples 1 to 10, the occurrence of drip was suppressed, which was consistent with the good followability of the lid material to the stored items. Thus, in Examples 1 to 10, it is speculated that the growth of bacteria in the stored items was suppressed during storage of the package by suppressing the occurrence of drip, and furthermore, the stored items It was presumed that the flavor of the stored items was also good because the deterioration due to oxidation etc. was suppressed. In the packages of Examples 1 to 10, deterioration of the contents (marine products) was suppressed, and the contents could be stored for a long period of time without spoiling their flavor.

In Examples 1 to 10, lid materials (I) to (IV) and (VII) to (XI) were used as lid materials, and the oxygen permeation amount of these lid materials (multilayer films) was 6 cc/(m ² * day * atm). Furthermore, the bottom material (α) or (β) is used as the bottom material, and the oxygen permeation amount of these bottom materials (multilayer film for bottom material) is 250 cc / (m ² · day · atm) or less (2 to 250 cc / (m ² ·day · atm)).
In Examples 1 to 10, the tensile strength of the cover material at a temperature of 140° C. was 0.6 to 3.5 N/mm ² .

Among them, in Examples 1 to 3 and 5 to 10, the followability of the lid material to the contents was particularly high, the effect of suppressing the occurrence of drip was particularly high, and the flavor of the contents was particularly good.
In Examples 1 to 3 and 5 to 10, lid materials (I) to (III) and (VII) to (XI) were used as lid materials. Furthermore, the bottom material (α) or (β) is used as the bottom material, and the oxygen permeation amount of these bottom materials (multilayer film for bottom material) is 250 cc / (m ² · day · atm) or less (2 to 250 cc / (m ² ·day · atm)).
In Examples 1 to 3 and 5 to 10, the tensile strength of the cover material at a temperature of 140° C. was 1 to 3.5 N/mm ² .

In Examples 1 to 10, the dynamic elastic modulus E′ of the lid material at a temperature of 140° C. was 5.5×10 ⁴ to 9.2×10 ⁶ Pa, and during thermomechanical analysis of the lid material, The temperature at which the displacement of 2000 μm is exhibited is 125° C. or higher (125 to 210° C.), the gel fraction of the cover material is 35% or higher (35 to 85%), and the absorbed dose of the cover material is 15 to 175 kGy. At the time of thermomechanical analysis of the lid material, the displacement at a temperature of 100° C. was 320 μm or less (40 to 320 μm).
Among them, in Examples 1 to 3 and 5 to 10, the dynamic elastic modulus E′ of the lid material at a temperature of 140° C. was 1.0×10 ⁵ to 9.2×10 ⁶ Pa, and the lid material The temperature at which a displacement of 2000 μm is exhibited is 135° C. or higher (135 to 210° C.), the gel fraction of the lid material is 60% or higher (60 to 85%), and the lid material is It was irradiated with an electron beam at an absorption dose of 90 to 175 kGy, and the displacement at a temperature of 100° C. was 120 μm or less (40 to 120 μm) during thermomechanical analysis of the lid material.

On the other hand, in Comparative Examples 1 to 3, the followability of the lid material to the contents was low, and the lid material pressed the contents, and as a result, the effect of suppressing the occurrence of drip was low.
In Comparative Examples 1 to 3, lid materials (XII) to (XIV) were used, and in these lid materials, the ratio of the total thickness of the layers made of Ny6 or PETG to the total thickness was high. , these lids were hard. In Comparative Examples 1 to 3, the tensile strength of the cover material at a temperature of 140° C. was 4.1 N/mm ² or more. Furthermore, in Comparative Examples 1 to 3, the dynamic elastic modulus E′ of the cover material at a temperature of 140° C. was 3.2×10 ⁷ Pa or more, and the gel fraction of the cover material was 25% or less. .

In Comparative Example 4, the followability of the lid member to the stored items was low, and a gap existed between the lid member and the stored items. As a result, the effect of suppressing the occurrence of drip was low.
In Comparative Example 4, lid material (V) was used, and this lid material was a multilayer film not irradiated with electron beams. In Comparative Example 4, the tensile strength of the cover material at a temperature of 140° C. was 0.2 N/mm ² .

In Comparative Example 5, discoloration of the contents was not suppressed, deterioration such as oxidation of the contents was not suppressed, and as a result, the flavor of the contents was lost.
In Comparative Example 5, the bottom material (γ) was used as the bottom material, and the oxygen permeation amount of this bottom material (multilayer film for bottom material) was 500 cc/(m ² ·day·atm).

Also in Comparative Example 6, the discoloration of the stored items was not suppressed, and deterioration such as oxidation of the stored items was not suppressed, and as a result, the flavor of the stored items was lost.
In Comparative Example 6, the lid material (VI) was used as the lid material, and the oxygen permeation amount of this lid material was 120 cc/(m ² ·day·atm). Comparative Example 6 had an oxygen barrier layer made of Ny6.

In Comparative Example 7, the package was not a skin pack package but a vacuum seal package, and the lid material (whole package) did not follow the contents and had many wrinkles. As a result, the occurrence of drip was not suppressed.

INDUSTRIAL APPLICABILITY The present invention can be used as a package for marine products or processed marine products intended for long-term storage.

1 Multilayer film (lid material)
DESCRIPTION OF SYMBOLS 11... Sealant layer 12... Outer layer 13... Functional layer 14... Oxygen barrier layer 15... Adhesive layer 151... First adhesive layer 152... Second adhesive layer 16... Anti-pinhole layer 10 Package (vacuum package)
8 Bottom material 9 Items to be stored (marine products or processed marine products)

Claims (14)

A resin film,
The resin film is for a lid material of a vacuum package for marine products or processed marine products, comprising a lid material and a bottom material,
The oxygen permeation amount of the resin film under conditions of a temperature of 23° C. and a relative humidity of 60% is 100 cc/(m ² ·day · atm) or less,
A resin film having a tensile strength of 0.3 to 4 N/mm ² at a temperature of 140° C., measured according to JIS K 7127:1999. 2. The resin according to claim 1, wherein the resin film has a dynamic elastic modulus E′ of 1×10 ⁴ to 1×10 ⁷ Pa at a temperature of 140° C., measured according to JIS K 7244-4. film. 3. The resin film according to claim 1, wherein the temperature at which the resin film exhibits a displacement of 2000 [mu]m is 120[deg.] C. or higher during thermomechanical analysis. The resin film according to any one of claims 1 to 3, wherein the resin film has a gel fraction of 30% or more. The resin film according to any one of claims 1 to 4, wherein the resin film is irradiated with an electron beam under the condition of an absorbed dose of 13 to 300 kGy. The resin film according to any one of claims 1 to 5, wherein a displacement at a temperature of 100°C is 500 µm or less in thermomechanical analysis of the resin film. The resin film is
an outer layer;
a functional layer adjacent to the outer layer;
an oxygen barrier layer;
a sealant layer;
The resin film according to any one of claims 1 to 6, which is a multilayer film comprising The resin film according to claim 7, wherein the outer layer contains a polyethylene resin. The resin film according to claim 7 or 8, wherein the functional layer contains an ionomer. The resin film according to any one of claims 7 to 9, wherein the sealant layer contains a polyethylene resin. The resin film according to any one of claims 1 to 10, wherein the vacuum package is a skin pack package for chilled raw meat. A vacuum package for marine products or processed marine products, comprising a lid material and a bottom material,
A package comprising the resin film according to any one of claims 1 to 11 as the lid member. 13. The package according to claim 12, wherein the bottom material has an oxygen permeation rate of 300 cc/(m ^<2> *day*atm) or less under conditions of a temperature of 23[deg.] C. and a relative humidity of 60%. A marine product package in which a marine product or a processed marine product is vacuum-packaged with the bottom member and lid member of the package according to claim 12 or 13.

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