JP2020049764A - Transparent multilayer film and package - Google Patents

Abstract

To provide a transparent multilayer film that suppresses smoking from the start to finish of its production.SOLUTION: A transparent multilayer film 1 has laminate of an easy peeling layer 11, a water vapor barrier layer 12, an intermediate layer 13, and an oxygen barrier layer 14, the water vapor barrier layer 12 and intermediate layer 13 being disposed between the easy peeling layer 11 and oxygen barrier layer 14, the water vapor barrier layer 12 disposed adjacent to the easy peeling layer 11, and the intermediate layer 13 containing a nitrogen-containing resin with a melting point of 210°C or lower.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transparent multilayer film and a package.

  As one type of food packaging, there is one in which a tray is sealed with a lid film. In particular, a package sealed with a transparent lid material film is in great demand because the food placed on the tray can be visually recognized from the outside of the package.

  Such a film is required to have an easy peel property to a tray, a barrier property for suppressing permeation of oxygen and water vapor, a pinhole resistance property, and the like, and usually a transparent multilayer film is used (Patent Reference 1).

JP 2005-288793 A

  The transparent multilayer film is produced, for example, by forming a film by a method involving heating such as a co-extrusion method, and such a transparent multilayer film emits smoke during the period from the start of the production to the end of the production. May be seen. If there is smoke, the smoke component condenses in the intermediate of the transparent multilayer film during the production or in the transparent multilayer film, and due to this process abnormality, the transparent multilayer film cannot be normally produced. On the other hand, it is not clear whether the transparent multilayer film described in Patent Document 1 solves such a problem.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a transparent multilayer film in which smoke is suppressed from the start of production to the end of production.

In order to solve the above problems, the present invention employs the following configurations.
[1]. An easy peel layer, a water vapor barrier layer, an intermediate layer, and an oxygen barrier layer are stacked, and the water vapor barrier layer and the intermediate layer are formed between the easy peel layer and the oxygen barrier layer. Wherein the water vapor barrier layer is disposed adjacent to the easy peel layer, and the intermediate layer contains a nitrogen-containing resin having a melting point of 210 ° C. or less.
[2]. The transparent multilayer film according to [1], wherein the easy peel layer contains an antifogging agent.
[3]. The transparent multilayer film according to [1] or [2], wherein the nitrogen-containing resin is a polyamide.
[4]. The transparent multilayer film according to any one of [1] to [3], wherein the water vapor barrier layer contains polypropylene.

[5]. The transparent multilayer film according to any one of [1] to [4], wherein the thickness of the oxygen barrier layer is 15 μm or less.
[6]. The transparent multilayer film according to any one of [1] to [5], wherein the water vapor barrier layer contains a crystallization nucleating agent.
[7]. A package comprising the transparent multilayer film according to any one of [1] to [6].

  According to the present invention, there is provided a transparent multilayer film in which smoke is suppressed from the start of production to the end of production.

It is a sectional view showing typically an example of a transparent multilayer film concerning one embodiment of the present invention. It is sectional drawing which shows typically an example of the package which concerns on one Embodiment of this invention.

<< Transparent multilayer film >>
The transparent multilayer film according to one embodiment of the present invention is configured by stacking an easy peel layer, a water vapor barrier layer, an intermediate layer, and an oxygen barrier layer, wherein the water vapor barrier layer and the intermediate layer are The water vapor barrier layer is disposed between the easy peel layer and the oxygen barrier layer, the water vapor barrier layer is disposed adjacent to the easy peel layer, and the intermediate layer has a melting point of 210 ° C. or less. Contains nitrogen resin.
The transparent multilayer film of this embodiment has transparency as a whole.

  In the transparent multilayer film of the present embodiment, the intermediate layer contains a nitrogen-containing resin having a melting point of 210 ° C. or less. During the production of such a transparent multilayer film, the film formation temperature can be set at a relatively low temperature equal to or higher than the melting point. And, during the period from the start of the production of the transparent multilayer film to the end of the production, smoke can be suppressed, and as a result, the intermediate of the transparent multilayer film being manufactured, and in the transparent multilayer film, the condensation of the smoke component can be suppressed, A transparent multilayer film can be manufactured normally.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make the features of the present invention easy to understand, for the sake of convenience, the main portions may be enlarged, and the dimensional ratios and the like of the respective components may be the same as those in the actual case. Is not always the case.

FIG. 1 is a cross-sectional view schematically illustrating an example of the transparent multilayer film of the present embodiment.
The transparent multilayer film 1 shown here is configured by stacking an easy peel layer 11, a water vapor barrier layer 12, an intermediate layer 13, and an oxygen barrier layer 14.
In the transparent multilayer film 1, the water vapor barrier layer 12 and the intermediate layer 13 are disposed between the easy peel layer 11 and the oxygen barrier layer. Further, the water vapor barrier layer 12 is arranged adjacent to the easy peel layer 11.
Further, the transparent multilayer film 1 includes an adhesive layer 15 between the water vapor barrier layer 12 and the intermediate layer 13.
That is, the transparent multilayer film 1 is configured such that the easy peel layer 11, the water vapor barrier layer 12, the adhesive layer 15, the intermediate layer 13, and the oxygen barrier layer 14 are laminated in this order in the thickness direction.

<Easy peel layer>
The easy peel layer 11 is one outermost layer in the transparent multilayer film 1 and is disposed on the outermost side in the laminating direction of each layer constituting the transparent multilayer film 1.
A package can be formed by sealing the transparent multilayer film 1 with another film or sheet by the easy peel layer 11 therein. A surface 11a of the easy peel layer 11 opposite to the water vapor barrier layer 12 (in other words, an exposed surface, which may be referred to as a “first surface” in this specification) 11a seals with another film or sheet. Seal surface.
The easy peel layer 11 has transparency.

The constituent material of the easy peel layer 11 may be a known material.
Preferred examples of the easy peel layer 11 include those exhibiting releasability due to cohesive failure.
As the easy peel layer 11 exhibiting releasability due to cohesive failure, for example, a layer containing two types of incompatible polyolefins may be mentioned.

  Examples of the two incompatible polyolefins contained in the easy peel layer 11 include an ethylene-based polymer having at least a constituent unit derived from ethylene and a propylene-based polymer having at least a constituent unit derived from propylene. And coalescence.

  Examples of the ethylene-based polymer contained in the easy peel layer 11 include a homopolymer of ethylene and an ethylene-based copolymer.

  Examples of the ethylene homopolymer include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-catalyzed linear low-density polyethylene (metallocene LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene. 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-based copolymer include ethylene-vinyl acetate copolymer (EVA resin), ethylene-methyl acrylate copolymer (EMA resin), ethylene-methyl methacrylate copolymer (EMMA resin), and ethylene. -Ethyl acrylate copolymer (EEA resin), ethylene-acrylic acid copolymer (EAA resin), ethylene-methacrylic acid copolymer (EMAA resin), ethylene-ethyl acrylate-maleic anhydride copolymer (E -EA-MAH resin) and ionomer resin (ION resin).

  The propylene-based polymer contained in the easy peel layer 11 includes a propylene homopolymer (that is, polypropylene or homopolypropylene, sometimes referred to as “hPP” in this specification) and a propylene-based copolymer. And.

The propylene-based copolymer has a constitutional unit derived from propylene and a constitutional unit derived from a monomer other than propylene.
Examples of the propylene-based copolymer include a propylene-ethylene random copolymer (alias: polypropylene random copolymer, sometimes referred to as “rPP” in this specification) and a propylene-ethylene block copolymer (alias) : Polypropylene block copolymer, which may be referred to as “bPP” in this specification).

  The component that expresses the easy peel property contained in the easy peel layer 11 may be only one kind, or two or more kinds, and when two or more kinds are used, the combination and ratio thereof are It can be arbitrarily selected according to the purpose. For example, when the components that exhibit easy peelability are the two incompatible polyolefins described above, each of these polyolefins contained in the easy peel layer 11 may be only one type or two types. It may be the above.

In the easy peel layer 11, 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 to 90% by mass. Is preferable, and may be any of 15 to 70 mass% and 20 to 50 mass%, for example. When the ratio is equal to or more than the lower limit, the easy peel property of the easy peel layer 11 is further improved. When the ratio is equal to or less than the upper limit, the peel strength is further stabilized.
The ratio is usually the content (parts by mass) of the ethylene-based polymer relative to the total content (parts by mass) of the ethylene-based polymer and the propylene-based polymer in the composition for forming an easy peel layer described below. Same as percentage.

The easy peel layer 11 may contain other components in addition to the component that expresses the easy peel property (for example, the two incompatible polyolefins described above) as long as the easy peel property is not impaired.
The other components contained in the easy peel layer 11 may be only one type, or two or more types, and when two or more types are used, the combination and ratio thereof may be determined according to the purpose. You can choose any.

In the easy peel layer 11, the ratio of the content of the component exhibiting easy peelability to the total mass of the easy peel layer 11 (for example, the ratio of the total content of the two incompatible polyolefins) is 50%. It is preferable that it is 100 mass%, and it is more preferable that it is 70-100 mass%. When the ratio is equal to or more than the lower limit, the easy peel property of the easy peel layer 11 is further improved.
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 composition for forming an easy peel layer described below, and Is the same.

  In this specification, “normal temperature” means a temperature at which cooling or heating is not particularly performed, that is, a normal temperature, and includes, for example, a temperature of 15 to 25 ° C.

Examples of the other components contained in the easy peel layer 11 include an antifogging agent and an antiblocking agent.
In particular, the easy peel layer 11 preferably contains an anti-fogging agent as the other component.

The anti-fogging agent contained in the easy peel layer 11 is a component for suppressing the fogging of the transparent multilayer film 1, particularly the fogging on the exposed surface of the easy peel layer 11.
The anti-fogging agent contained in the easy peel layer 11 may be a known one. Examples of the antifogging agent include polyglycene fatty acid esters, diglycerin fatty acid esters, and the like.

  The anti-fogging agent contained in the easy peel layer 11 may be only one kind, two or more kinds, and when two or more kinds, the combination and ratio thereof are optional depending on the purpose. Can be selected.

When an anti-fogging agent is used, the ratio of the content of the anti-fogging agent to the total mass of the easy peel layer 11 in the easy peel layer 11 is preferably 0.5 to 5.0% by mass, and is preferably 1.0 to 5.0% by mass. It is more preferable that the content is 4.5% by mass. When the ratio is equal to or more than the lower limit, the effect of using the anti-fogging agent is more remarkably obtained. When the ratio is equal to or less than the upper limit, characteristics other than the anti-fogging property of the transparent multilayer film 1 become more favorable.
The ratio is usually the same as the ratio of the content (parts by mass) of the antifogging agent to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming an easy peel layer described later.

  The anti-blocking agent is applied when the transparent multilayer films 1 are stacked together, or when the transparent multilayer film 1 and another film or sheet are stacked, when the transparent multilayer films 1 are stuck together, or when the transparent multilayer film is stacked. It is a component for suppressing sticking (blocking) between 1 and a film or sheet adjacent thereto. The “stacking of the transparent multilayer films 1” also includes a mode of “winding one transparent multilayer film 1 into a roll”.

  The anti-blocking agent contained in the easy peel layer 11 may be a known one. Examples of the anti-blocking agent include silica such as natural silica and synthetic silica.

  The anti-peeling agent contained in the easy peel layer 11 may be only one kind, two or more kinds, and when two or more kinds, the combination and ratio thereof are optional depending on the purpose. Can be selected.

When an anti-blocking agent is used, the content of the anti-blocking agent in the easy peel layer 11 with respect to the total mass of the easy peel layer 11 is preferably 0.05 to 3.0% by mass, and is preferably 0.1 to 3.0% by mass. More preferably, it is about 2.5% by mass. When the ratio is equal to or more than the lower limit, the effect of using the antiblocking agent is more remarkably obtained. When the ratio is equal to or less than the upper limit, properties other than the anti-blocking property of the transparent multilayer film 1 become more favorable.
The ratio is usually the same as the ratio of the content (parts by mass) of the antiblocking agent to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming an easy peel layer described later.

  The easy peel layer 11 may be composed of one layer (single layer) or may be composed of two or more layers. When the easy peel layer 11 includes a plurality of layers, the plurality of layers may be the same or different from each other, and the combination of the plurality of layers is not particularly limited as long as the effects of the present invention are not impaired.

  In the present specification, not only the case of the easy peel layer 11, but also "a plurality of layers may be the same or different from each other" means "all the layers may be the same or all the layers may be the same. May be different, or only some of the layers may be the same '', and further, `` a plurality of layers are different from each other '' means that at least one of a constituent material and a thickness of each layer is different from each other. Different ".

  The thickness of the easy peel layer 11 is not particularly limited, but is preferably less than 10 μm, more preferably 9 μm or less, further preferably 7.5 μm or less, and particularly preferably 6 μm or less. . When the easy peel layer that has been sealed with respect to the object to be sealed is peeled (that is, peeled), a part of the easy peel layer is pulled between the peeled portions, and the peeled surface is not flat. (In this specification, such a state may be referred to as “stringing”). In contrast, when the thickness of the easy peel layer 11 is equal to or less than the upper limit, the effect of suppressing the occurrence of such stringing becomes higher. This effect is particularly high when the easy peel layer exhibits peelability due to cohesive failure.

  The lower limit of the thickness of the easy peel layer 11 is not particularly limited. For example, the thickness of the easy peel layer 11 is preferably 2 μm or more from the viewpoint that the structure of the easy peel layer 11 is more stable.

  The thickness of the easy peel layer 11 can be appropriately adjusted within a range set by arbitrarily combining the lower limit and the upper limit described above. For example, in one embodiment, the thickness of the easy peel layer 11 is preferably 2 μm or more and less than 10 μm, more preferably 2 μm to 9 μm, further preferably 2 μm to 7.5 μm, and particularly preferably 2 μm to 6 μm. However, these are examples of the thickness of the easy peel layer 11.

  When the easy peel layer 11 includes a plurality of layers, the total thickness of the plurality of layers may be set to the preferable thickness of the easy peel layer 11 described above.

<Steam barrier layer>
The water vapor barrier layer 12 is disposed adjacent to the easy peel layer 11. In the transparent multilayer film of the present embodiment, it is preferable that the water vapor barrier layer is laminated in contact with the easy peel layer.
The water vapor barrier layer 12 has transparency.

  The water vapor barrier layer 12 is preferably a resin layer containing a water vapor barrier resin having a water vapor barrier property.

Examples of the water vapor barrier resin include polyethylene such as low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE); ethylene-α-olefin copolymer; polypropylene; propylene-ethylene random copolymer A propylene-ethylene block copolymer; a propylene-α olefin copolymer; an ethylene-cyclic olefin copolymer obtained by copolymerizing a cyclic olefin such as cyclopentadiene or norbornene; an ethylene-vinyl acetate copolymer (EVA). Resin); partially saponified or completely saponified ethylene-vinyl acetate copolymer; ethylene- (meth) acrylic acid copolymer or its esterified product or ion-crosslinked product; ethylene- (meth) acrylic acid- (meth) acrylic acid Acid ester terpolymer; Maleic anhydride-modified polyethylene; maleic anhydride-polyethylene copolymer and the like.
Among these, the water vapor barrier layer 12 preferably contains polypropylene.

  In this specification, “(meth) acrylic acid” is a concept including both “acrylic acid” and “methacrylic acid”. The same applies to terms similar to (meth) acrylic acid.

  In the case where the water vapor barrier layer 12 contains a component exhibiting a water vapor barrier property (for example, the water vapor barrier resin), only one type may be used, two or more types may be used, or two or more types may be used. The combination and ratio thereof can be arbitrarily selected according to the purpose.

The steam barrier layer 12 may contain other components in addition to the component exhibiting the steam barrier property (for example, the steam barrier resin) as long as the steam barrier property is not impaired.
The other component contained in the water vapor barrier layer 12 may be only one type, or two or more types, and when two or more types are used, their combination and ratio may be determined according to the purpose. You can choose any.

In the water vapor barrier layer 12, the ratio of the content of the component exhibiting the water vapor barrier property to the total mass of the water vapor barrier layer 12 (for example, the ratio of the content of the water vapor barrier resin) is 50 to 100% by mass. , And more preferably 70 to 100% by mass. When the ratio is equal to or more than the lower limit, the water vapor barrier property of the water vapor barrier layer 12 is further increased.
The ratio is usually the ratio of the content (parts by mass) of the component exhibiting the water vapor barrier property to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming a vapor barrier layer described below. Is the same.

  Examples of the other components contained in the water vapor barrier layer 12 include an antifogging agent and a crystallization nucleating agent.

In particular, the water vapor barrier layer 12 preferably contains a crystallization nucleating agent as the other component. The crystallization nucleating agent is a component for improving the transparency of a layer containing the crystallization nucleating agent, as described later.
When the easy peel layer 11 shows the peeling property due to cohesive failure, for example, when the easy peel layer 11 contains the above two incompatible polyolefins, the easy peel layer 11 However, the transparency of the entire transparent multilayer film 1 tends to be lower than when another sealant layer is provided. Therefore, in the present embodiment, when the easy peel layer 11 exhibits releasability due to cohesive failure, the water vapor barrier layer 12 particularly preferably contains a crystallization nucleating agent as the other component.

The antifogging agent contained in the water vapor barrier layer 12 is a component for suppressing the fogging of the transparent multilayer film 1, particularly the fogging on the exposed surface of the easy peel layer 11.
The antifogging agent contained in the water vapor barrier layer 12 may be a known one, and specifically, the same antifogging agent as that contained in the above-mentioned easy peel layer 11 can be used.

  The water vapor barrier layer 12 may contain only one type of antifogging agent, or two or more types, and when there are two or more types, the combination and ratio thereof are optional depending on the purpose. Can be selected.

When using an anti-fogging agent, the content ratio of the anti-fogging agent in the water vapor barrier layer 12 with respect to the total mass of the water vapor barrier layer 12 is preferably 0.05 to 3.0% by mass, and 0.1 to 3.0% by mass. More preferably, it is about 2.5% by mass. When the ratio is equal to or more than the lower limit, the effect of using the anti-fogging agent is more remarkably obtained. When the ratio is equal to or less than the upper limit, characteristics other than the anti-fogging property of the transparent multilayer film 1 become more favorable.
The ratio is usually the same as the ratio of the content (parts by mass) of the antifogging agent to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming a water vapor barrier layer described later.

The crystallization nucleating agent is a component for improving the transparency of the water vapor barrier layer 12 by controlling the crystal growth in the water vapor barrier layer 12.
The crystallization nucleating agent contained in the water vapor barrier layer 12 may be a known one. Examples of the crystallization nucleating agent include a sorbitol-based crystallization nucleating agent.

  The crystallization nucleating agent contained in the water vapor barrier layer 12 may be only one kind, or two or more kinds, and when two or more kinds, the combination and the ratio thereof are determined according to the purpose. You can choose any.

When a crystallization nucleating agent is used, the content ratio of the crystallization nucleating agent in the water vapor barrier layer 12 with respect to the total mass of the water vapor barrier layer 12 is preferably 0.05 to 3.0% by mass. More preferably, it is 0.1 to 2.5% by mass. When the ratio is equal to or more than the lower limit, the effect of using the crystallization nucleating agent is more remarkably obtained. When the ratio is equal to or less than the upper limit, characteristics other than the transparency of the water vapor barrier layer 12 are further improved.
The ratio is usually the same as the ratio of the content (parts by mass) of the crystallization nucleating agent to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming a water vapor barrier layer described later. .

  The water vapor barrier layer 12 may be composed of one layer (single layer) or may be composed of two or more layers. When the water vapor barrier layer 12 includes a plurality of layers, the plurality of layers may be the same or different from each other, and the combination of the plurality of layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the water vapor barrier layer 12 is not particularly limited, but is preferably 5 to 30 μm, more preferably 7.5 to 25 μm, and particularly preferably 10 to 20 μm. When the thickness of the water vapor barrier layer 12 is equal to or more than the lower limit, the water vapor barrier property of the water vapor barrier layer 12, in other words, the water vapor barrier property of the transparent multilayer film 1 is further improved. When the thickness of the water vapor barrier layer 12 is equal to or less than the upper limit, an excessive thickness is suppressed.
When the water vapor barrier layer 12 includes a plurality of layers, the total thickness of the plurality of layers may be set to the preferable thickness of the water vapor barrier layer 12 described above.

The water vapor transmission rate of the water vapor barrier layer 12 is preferably, for example, 100 g / m ² · day or less in an atmosphere of 40 ° C. and 90% RH (relative humidity).
The water vapor transmission rate of the water vapor barrier layer 12 can be measured, for example, in accordance with JIS Z 0208.

<Intermediate layer>
The intermediate layer 13 imparts moldability to the transparent multilayer film 1 and also suppresses the occurrence of pinholes in the transparent multilayer film 1.
The intermediate layer 13 contains a nitrogen-containing resin having a melting point of 210 ° C. or less as a constituent material. In this specification, unless otherwise specified, “nitrogen-containing resin” means a nitrogen-containing resin having a melting point of 210 ° C. or less.
The intermediate layer 13 has transparency.

The nitrogen-containing resin contained in the intermediate layer 13 is not particularly limited as long as it has a melting point of 210 ° C. or lower, but preferably has a nitrogen atom in its main chain.
In particular, the nitrogen-containing resin is more preferably a polyamide.

  Examples of the polyamide include a polyamide obtained by polymerizing or copolymerizing a cyclic lactam (lactam having 3 or more ring members), an amino acid, or a nylon salt obtained by reacting a diamine with a dicarboxylic acid. No.

  Examples of the cyclic lactam include ε-caprolactam, ω-enantholactam, ω-laurolactam, α-pyrrolidone, α-piperidone and the like.

  Examples of the amino acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and the like.

Examples of the diamine that forms the nylon salt include, for example, tetramethylene diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2,2,2 Aliphatic amines such as 4-trimethylhexamethylenediamine and 2,4,4-trimethylhexamethylenediamine;
1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, isophoronediamine, piperazine, bis (4-aminocyclohexyl) methane, 2,2-bis- (4-aminocyclohexyl) propane, etc. An alicyclic diamine;
Aromatic diamines such as meta-xylylenediamine and para-xylylenediamine are exemplified.

Examples of the dicarboxylic acid that forms the nylon salt include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sepatinic acid, undecanedioic acid, and dodecanedioic acid;
Alicyclic carboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid;
Terephthalic acid, isophthalic acid, 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7- And aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

  More specifically, as the polyamide, for example, 4-nylon, 6-nylon, 7-nylon, 11-nylon, 12-nylon, 46-nylon, 66-nylon, 69-nylon, 610-nylon, 611-nylon Nylon, 612-nylon, 6T-nylon, 6I nylon, 6-nylon and 66-nylon copolymer (nylon 6/66), 6-nylon and 610-nylon copolymer, 6-nylon and 611-nylon Copolymer, copolymer of 6-nylon and 12-nylon (nylon 6/12), copolymer of 6-nylon and 612 nylon, copolymer of 6-nylon and 6T-nylon, copolymer of 6-nylon and 6I-nylon A copolymer of 6-nylon, 66-nylon and 610-nylon, Copolymers of nylon, 66-nylon and 12-nylon (nylon 6/66/12), copolymers of 6-nylon, 66-nylon and 612-nylon, copolymers of 66-nylon and 6T-nylon, 66- Copolymers of nylon and 6I-nylon, copolymers of 6T-nylon and 6I-nylon, copolymers of 66-nylon, 6T-nylon and 6I-nylon, and the like.

  The polyamide is 6-nylon, 12-nylon, 66-nylon, nylon 6/66, nylon 6/12 or nylon 6/66/12 in terms of heat resistance, mechanical strength, and availability. It is preferred that

  The nitrogen-containing resin contained in the intermediate layer 13 may be only one kind, two or more kinds, and when two or more kinds, the combination and ratio thereof are optional according to the purpose. Can be selected.

When manufacturing the transparent multilayer film, for example, each layer is formed (in other words, formed into a film) by a method involving heating such as a co-extrusion method using a resin or a resin composition for forming each layer constituting the transparent multilayer film.
On the other hand, the intermediate layer is usually formed using a resin having a higher melting point than the other layers, for example, including the above-described nitrogen-containing resin. That is, the intermediate layer usually requires a higher deposition temperature than the other layers. Here, if the film formation temperature is too high, from the start of the production of the transparent multilayer film to the end of the production, any of the layers constituting the transparent multilayer film, or from the resin composition for forming the same. In addition, components having relatively low boiling points may be vaporized and observed as fuming. In this case, the smoke component (that is, the above-mentioned vaporized component) condenses due to cooling, which causes a process abnormality, and makes it impossible to normally produce a transparent multilayer film. Such smoke is seen not only when the film formation temperature is too high but also when the thickness of any layer formed (formed) from the resin composition containing the component causing smoke is low. Can be In addition, as a component which is likely to cause such smoking, for example, the above-described anti-fogging agent can be mentioned.
On the other hand, in the transparent multilayer film 1, the melting point of the nitrogen-containing resin contained in the intermediate layer 13 is 210 ° C. or less, which is a relatively low melting point. And as a vaporizable component (for example, typically an antifogging agent) contained in each layer in the transparent multilayer film 1, one having a boiling point higher than 210 ° C. (in other words, the melting point of the nitrogen-containing resin). It is easy to choose. That is, the transparent multilayer film 1 can sufficiently suppress the generation of smoke from the start of the production to the end of the production. For example, in the transparent multilayer film 1, if the upper limit of the thickness of the layer containing the anti-fogging agent (for example, the above-described easy peel layer 11 and water vapor barrier layer 12) is set to 40 μm, the generation of such smoke is possible. The suppression effect can be obtained more remarkably.

  The melting point of the nitrogen-containing resin is preferably 205 ° C. or lower, more preferably 200 ° C. or lower, and particularly preferably 197 ° C. or lower, from the viewpoint that the above-mentioned effect of suppressing smoke emission is further enhanced.

  The lower limit of the melting point of the nitrogen-containing resin is not particularly limited. For example, the melting point of the nitrogen-containing resin is preferably 160 ° C. or higher, more preferably 165 ° C. or higher, and even more preferably 170 ° C. or higher, from the viewpoint that it is relatively easy to obtain the nitrogen-containing resin. 175 ° C. or higher is particularly preferred.

  The melting point of the nitrogen-containing resin can be appropriately adjusted within a range set by arbitrarily combining the lower limit and the upper limit. For example, in one embodiment, the melting point of the nitrogen-containing resin is preferably from 160 to 210C, more preferably from 165 to 205C, still more preferably from 170 to 200C, and particularly preferably from 175 to 197C. However, these are examples of the melting point of the nitrogen-containing resin.

The intermediate layer 13 may contain other components in addition to the nitrogen-containing resin as long as the effect is not impaired.
The other component contained in the intermediate layer 13 may be only one kind, two or more kinds, and when two or more kinds, the combination and ratio thereof are optional according to the purpose. Can be selected.

In the intermediate layer 13, the ratio of the content of the nitrogen-containing resin to the total mass of the intermediate layer 13 is preferably 50 to 100% by mass, and more preferably 70 to 100% by mass. When the ratio is equal to or more than the lower limit, the effect obtained by providing the transparent multilayer film 1 with the intermediate layer 13 is further enhanced.
The ratio is usually the same as the ratio of the content (parts by mass) of the nitrogen-containing resin to the total content (parts by mass) of the components that do not vaporize at room temperature in the intermediate layer forming composition described later.

  Examples of the other components contained in the intermediate layer 13 include an antioxidant and the like.

  The intermediate layer 13 may be composed of one layer (single layer) or may be composed of two or more layers. When the intermediate layer 13 includes a plurality of layers, the plurality of layers may be the same or different from each other, and the combination of the plurality of layers is not particularly limited as long as the effects of the present invention are not impaired.

The thickness of the intermediate layer 13 is not particularly limited, but is preferably 3 to 30 μm, more preferably 5 to 25 μm, and particularly preferably 7 to 20 μm. When the thickness of the intermediate layer 13 is equal to or more than the lower limit, the effect obtained by providing the transparent multilayer film 1 with the intermediate layer 13 is further enhanced. When the thickness of the intermediate layer 13 is equal to or less than the upper limit, an excessive thickness is suppressed.
When the intermediate layer 13 is composed of a plurality of layers, the total thickness of the plurality of layers may be set to the preferable thickness of the intermediate layer 13 described above.

<Oxygen barrier layer>
The oxygen barrier layer 14 is the other outermost layer in the transparent multilayer film 1 and is disposed on the other outermost side on the side opposite to the easy peel layer 11 in the laminating direction of each layer constituting the transparent multilayer film 1. I have.
The oxygen barrier layer 14 has transparency.

  The oxygen barrier layer 14 is preferably a resin layer containing an oxygen barrier resin having an oxygen barrier property.

Examples of the oxygen barrier resin include an ethylene-vinyl alcohol copolymer (alias: saponified ethylene-vinyl acetate copolymer, EVOH), polyamide, polyvinyl alcohol, polyacrylonitrile, and the like.
Among these, the oxygen barrier layer 14 preferably contains an ethylene-vinyl alcohol copolymer, and the copolymerization ratio of ethylene (in other words, from ethylene to the total amount of the structural units in the ethylene-vinyl alcohol copolymer, It is more preferable to contain an ethylene-vinyl alcohol copolymer having a ratio of the amount of the derived structural unit) of 30 to 50 mol%.

  In the case where the oxygen barrier layer 14 contains components that exhibit oxygen barrier properties (for example, the oxygen barrier resin), only one type may be used, two or more types may be used, or two or more types may be used. The combination and ratio thereof can be arbitrarily selected according to the purpose.

The oxygen barrier layer 14 may contain other components in addition to the component exhibiting the oxygen barrier property (for example, the oxygen barrier resin) as long as the oxygen barrier property is not impaired.
The other component contained in the oxygen barrier layer 14 may be only one kind, or two or more kinds, and when two or more kinds, the combination and ratio thereof may be determined according to the purpose. You can choose any.

In the oxygen barrier layer 14, the ratio of the content of the component exhibiting oxygen barrier properties to the total mass of the oxygen barrier layer 14 (for example, the ratio of the content of the oxygen barrier resin) is 50 to 100% by mass. , And more preferably 70 to 100% by mass. When the ratio is equal to or more than the lower limit, the oxygen barrier property of the oxygen barrier layer 14 is further increased.
The ratio is usually the same as the ratio of the content (parts by mass) of the component exhibiting oxygen barrier properties to the total content (parts by mass) of the components that do not vaporize at room temperature in the intermediate layer forming composition described later. It is.

  Examples of the other components contained in the oxygen barrier layer 14 include an antioxidant and the like.

  The oxygen barrier layer 14 may be composed of one layer (single layer), or may be composed of two or more layers. When the oxygen barrier layer 14 includes a plurality of layers, the plurality of layers may be the same or different from each other, and the combination of the plurality of 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 not particularly limited, but is preferably 15 μm or less, more preferably 13 μm or less, and particularly preferably 11 μm or less. When the thickness of the oxygen barrier layer 14 is equal to or less than the upper limit, the oxygen barrier layer 14 has a high effect of suppressing appearance deterioration such as foaming during film formation while maintaining good oxygen barrier properties.

  The lower limit of the thickness of the oxygen barrier layer 14 is not particularly limited. For example, the thickness of the oxygen barrier layer 14 is preferably 5 μm or more from the viewpoint of further improving the oxygen barrier property of the oxygen barrier layer 14, in other words, the oxygen barrier property of the transparent multilayer film 1.

  The thickness of the oxygen barrier layer 14 can be appropriately adjusted within a range set by arbitrarily combining the lower limit and the upper limit described above. For example, in one embodiment, the thickness of the oxygen barrier layer 14 is preferably 5 to 15 μm, more preferably 5 to 13 μm, and particularly preferably 5 to 11 μm. However, these are examples of the thickness of the oxygen barrier layer 14.

  When the oxygen barrier layer 14 includes a plurality of layers, the total thickness of the plurality of layers may be set to the preferable thickness of the oxygen barrier layer 14 described above.

The oxygen gas permeation amount of the oxygen barrier layer 14 is preferably, for example, 50 cc / m ² · atm · day or less in an atmosphere of 20 ° C. and 80% RH (relative humidity).
The oxygen gas permeation amount of the oxygen barrier layer 14 can be measured, for example, in accordance with JIS K 7126-2.

<Adhesive layer>
The bonding layer 15 bonds the water vapor barrier layer 12 and the intermediate layer 13 adjacent thereto.
The adhesive layer 15 has transparency.
The adhesive layer 15 is an optional component and can be omitted in the transparent multilayer film 1. However, the provision of the adhesive layer 15 further stabilizes the multilayer structure of the transparent multilayer film 1.

  The adhesive layer 15 is preferably a resin layer containing an adhesive resin.

Examples of the adhesive resin include a polyolefin resin.
The polyolefin-based resin is a resin having a structural unit derived from an olefin, and may be a modified polyolefin such as an acid-modified polyolefin having an acidic group.
Examples of the polyolefin-based resin include an ethylene-based copolymer, a propylene-based copolymer, a butene-based copolymer, and a modified product of these copolymers (in other words, a modified copolymer). The polyolefin-based resin is preferably a random copolymer, a graft copolymer or a block copolymer from the viewpoint of further improving the adhesiveness.

Examples of the ethylene-based copolymer contained in the adhesive layer 15 include the ethylene-based copolymer described above as a component contained in the easy peel layer 11, a modified product thereof (modified copolymer), and the like.
Examples of the propylene-based copolymer contained in the adhesive layer 15 include a copolymer of propylene and a vinyl group-containing monomer, a modified product thereof (modified copolymer), and the like. More specifically, examples of such a propylene-based copolymer include a maleic anhydride-grafted linear low-density polypropylene, a propylene-based thermoplastic elastomer, and the like.
Examples of the butene-based copolymer contained 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 a copolymer of these copolymers. Modified products (modified copolymers) and the like can be mentioned.

  The component (for example, the adhesive resin) that exhibits adhesiveness contained in the adhesive layer 15 may be only one kind, or two or more kinds, and when two or more kinds, Can be arbitrarily selected according to the purpose.

The adhesive layer 15 may contain other components in addition to the component exhibiting the adhesive property (for example, the adhesive resin) as long as the adhesive property is not impaired.
The other component contained in the adhesive layer 15 may be only one kind, or two or more kinds, and when two or more kinds, the combination and ratio thereof are optional according to the purpose. Can be selected.

In the adhesive layer 15, the ratio of the content of the component exhibiting adhesiveness to the total mass of the adhesive layer 15 (for example, the ratio of the content of the adhesive resin) is preferably 80 to 100% by mass, More preferably, it is 90 to 100% by mass. When the ratio is equal to or more than the lower limit, the adhesiveness of the adhesive layer 15 is further increased.
The ratio is usually the same as the ratio of the content (parts by mass) of the component that exhibits adhesiveness to the total content (parts by mass) of the components that do not vaporize at room temperature in the adhesive layer forming composition described below. is there.

  Examples of the other components contained in the adhesive layer 15 include an antioxidant and the like.

  The adhesive layer 15 may be composed of one layer (single layer) or may be composed of two or more layers. When the adhesive layer 15 includes a plurality of layers, the plurality of layers may be the same or different from each other, and the combination of the plurality of 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 not particularly limited, but is preferably 0.1 to 30 μm, more preferably 0.5 to 20 μm, and particularly preferably 1 to 10 μm. When the thickness of the adhesive layer 15 is equal to or more than the lower limit, the adhesive layer 15 has more excellent adhesiveness. When the thickness of the adhesive layer 15 is equal to or less than the upper limit, an excessive thickness is suppressed.
When the adhesive layer 15 includes a plurality of layers, the total thickness of the plurality of layers may be set to the preferable thickness of the adhesive layer 15 described above.

The haze of the transparent multilayer film 1 is preferably at most 12%, more preferably at most 10%.
On the other hand, the lower limit of the haze of the transparent multilayer film 1 is not particularly limited. For example, the haze may be 0.5% or more in that the transparent multilayer film 1 is easily manufactured.
However, the haze of the transparent multilayer film 1 shown here is an example.

  The haze of the transparent multilayer film 1 can be adjusted by adjusting the type or content of the components contained in each of the above-mentioned layers constituting the transparent multilayer film 1. For example, the haze can be more easily adjusted by adjusting the presence or absence of the above-mentioned crystallization nucleating agent in each layer and adjusting the amount of the nucleating agent used.

  In addition, in this specification, "the haze of a film" means what was measured based on JISK7136: 2000.

  The transparent multilayer film of the present embodiment is not limited to the above-described embodiment, and may have a partially modified, deleted, or added configuration without departing from the spirit of the present invention.

For example, the transparent multilayer film 1 shown in FIG. 1 includes an easy peel layer 11, a water vapor barrier layer 12, an intermediate layer 13, an oxygen barrier layer 14, and an adhesive layer 15, and any of these may be used. Other layers that do not apply may be further provided.
The other layers are not particularly limited and can be arbitrarily selected according to the purpose.
For example, the transparent multilayer film 1 may include an adhesive layer similar to the adhesive layer 15 between the other two layers other than between the water vapor barrier layer 12 and the intermediate layer 13.

<< Production method of transparent multilayer film >>
The transparent multilayer film may be formed, for example, by using several extruders, a feed block method in which a resin or a resin composition or the like as a material for forming each layer is melt-extruded, a co-extrusion T-die method such as a multi-manifold method, or air cooling. It can be produced by a co-extrusion or water-cooled co-extrusion inflation method.

  In addition, the transparent multilayer film is coated with a resin or a resin composition or the like to be a material for forming any of the layers on the surface of another layer for forming the transparent multilayer film, if necessary. By drying, a laminated structure in the transparent multilayer film is formed, and if necessary, it can be produced by further laminating other layers so as to have a desired arrangement form.

  Further, the transparent multilayer film is prepared by separately preparing two or more films for constituting any two or more layers thereof, and using an adhesive to dry these films, a dry lamination method, an extrusion lamination method. It can also be manufactured by laminating by laminating any one of a hot melt laminating method and a wet laminating method, and, if necessary, further laminating other layers so as to have a desired arrangement form. At this time, an adhesive capable of forming the adhesive layer may be used.

  In addition, as described above, the transparent multilayer film is formed by laminating two or more films separately prepared in advance by a thermal (heat) lamination method or the like without using an adhesive. According to the above, it can also be manufactured by further laminating layers other than these so as to have an intended arrangement form.

  When manufacturing the transparent multilayer film, two or more of the above-described methods for forming any layer (in other words, a film) in the transparent multilayer film may be combined.

  The resin composition, which is a material for forming any of the layers in the transparent multilayer film, controls the type and content of the components so that the layer to be formed contains the desired components at the desired contents. Then, it may be manufactured. For example, the content ratio of components that do not vaporize at room temperature in the resin composition is usually the same as the content ratio of the components in a layer formed from the resin composition.

  A resin composition for forming an easy peel layer (in the transparent multilayer film 1 shown in FIG. 1, the easy peel layer 11) (in this specification, it may be referred to as an “easy peel layer forming composition”). Examples thereof include those containing a component exhibiting easy peelability (for example, the two incompatible polyolefins described above) and other components. Examples of the other components in the easy peel layer include the antifogging agent and the antiblocking agent.

  A resin composition for forming a water vapor barrier layer (in the transparent multilayer film 1 shown in FIG. 1, the water vapor barrier layer 12) (in this specification, this may be referred to as a “composition for forming a water vapor barrier layer”). Examples thereof include those containing a component exhibiting water vapor barrier properties (for example, the water vapor barrier resin) and other components. Examples of the other components in the composition for forming a water vapor barrier layer include the antifogging agent and the crystallization nucleating agent.

  Examples of the resin composition for forming the intermediate layer (in the transparent multilayer film 1 shown in FIG. 1, the intermediate layer 13) (in this specification, sometimes referred to as “composition for forming an intermediate layer”) include: For example, a resin containing a nitrogen-containing resin having a melting point of 210 ° C. or lower and other components is used. Examples of the other components in the composition for forming an intermediate layer include an antioxidant.

  A resin composition for forming an oxygen barrier layer (the oxygen barrier layer 14 in the transparent multilayer film 1 shown in FIG. 1) (in this specification, this may be referred to as an “oxygen barrier layer forming composition”). Examples thereof include those containing a component exhibiting oxygen barrier properties (for example, the oxygen barrier resin) and other components. Examples of the other components in the composition for forming an oxygen barrier layer include an antioxidant.

  Examples of the resin composition for forming the adhesive layer (the adhesive layer 15 in the transparent multilayer film 1 shown in FIG. 1) (in this specification, sometimes referred to as “composition for forming an adhesive layer”) include: For example, a material containing a component exhibiting adhesiveness (for example, the adhesive resin) and another component other than the above component may be used. Examples of the other components in the adhesive layer forming composition include an antioxidant.

<< Package >>
A package according to one embodiment of the present invention includes the transparent multilayer film.
The transparent multilayer film can form various packages by being sealed with another resin film, a resin sheet or a resin tray (in other words, a resin bottom material) by an easy peel layer therein.

  Preferred examples of the package include those in which the transparent multilayer film is a lid material for a tray, and the transparent multilayer film is sealed with a resin tray by an easy peel layer therein.

FIG. 2 is a cross-sectional view schematically illustrating an example of the package of the present embodiment.
In FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof will be omitted.

  The package 2 shown here uses the transparent multilayer film 1 shown in FIG. 1 as a lid material, and is configured to be sealed with a resin tray 9.

The resin tray 9 may be a known one.
The resin tray 9 is formed by molding a resin sheet or a resin film so that one surface thereof is concave (in other words, the other surface is convex). More specifically, one surface 9a of the resin tray 9 (which may be referred to as a “first surface” in this specification) is concave, and its peripheral edge 90a is flat. I have.

  In the package 2, the peripheral portion 110 a of the first surface 11 a of the easy peel layer 11 in the transparent multilayer film 1 and the peripheral portion 90 a of the first surface 9 a of the resin tray 9 are sealed and adhered. doing. Then, the easy peel layer 11 and the resin tray 9 are not sealed (closely adhered) in regions other than these peripheral portions (the peripheral portion 110a and the peripheral portion 90a). Since the transparent multilayer film 1 and the resin tray 9 are sealed as described above, the package 2 is housed by being surrounded by the first surface 11 a of the easy peel layer 11 and the first surface 9 a of the resin tray 9. It has a space S. The object 8 to be packaged is accommodated in the accommodation space S, and is sealed.

  In the package 2, the packaging target 8 accommodated in the accommodation space S can be clearly seen through the transparent multilayer film 1.

  When the package 2 is opened, the easy peel layer 11 in the transparent multilayer film 1 is easily peeled off by performing an operation of peeling the transparent multilayer film 1 from the resin tray 9.

  The package of the present embodiment is not limited to the above-described embodiment, and may have a partially modified, deleted, or added configuration without departing from the spirit of the present invention.

For example, in the package 2 shown in FIG. 2, the peripheral portion 90a of the first surface 9a of the resin tray 9 is flat, but the peripheral portion 90a may have another shape such as a curved surface. .
FIG. 2 shows the package 2 using the transparent multilayer film 1, but the package of the present embodiment uses the transparent multilayer film of the present invention other than the transparent multilayer film 1. Is also good.
Further, in FIG. 2, the package 2 using the resin tray 9 is shown as an object to be sealed of the transparent multilayer film 1. Instead of a resin tray, a resin film or a resin sheet may be used.

<< Package manufacturing method >>
The packaging body, by using the transparent multilayer film, so as to form a target accommodation space, by sealing (attaching) the transparent multilayer film and another resin film, a resin sheet or a resin tray, Can be manufactured. The sealing at this time is preferably performed while heating (heating lamination).
In the case of using the resin tray, a resin tray may be manufactured by, for example, forming a planar resin sheet into a desired shape by a known method.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples described below.

<< Production of transparent multilayer film >>
[Example 1]
<Production of a composition for forming an easy peel layer>
27 parts by mass of low density polyethylene (LDPE, "F522N" manufactured by Ube Maruzen Polyethylene Co., Ltd.), 40 parts by mass of polypropylene random copolymer (rPP, "S131" manufactured by Sumitomo Chemical Co., Ltd.), and antifogging agent masterbatch (manufactured by Takemoto Yushi Co., Ltd.) P302AB ", 30 parts by mass of a fatty acid ester compound serving as an antifogging agent in a content of 10% by mass and a content of a polypropylene resin of 90% by mass), and an antiblocking agent masterbatch (" A22 "manufactured by Sumitomo Chemical Co., Ltd.) 3 parts by mass of a silica-containing material as an antiblocking agent in a content of 10% by mass and a polyethylene-based resin in a content of 90% by mass) were kneaded at room temperature to obtain a composition for forming an easy peel layer.

<Production of a composition for forming a water vapor barrier layer>
82 parts by mass of a homopolypropylene (hPP, "WF836DG3" manufactured by Sumitomo Chemical Co., Ltd.) and a crystallization nucleating agent masterbatch ("PPM-NAT94" manufactured by Tokyo Ink Co., Ltd .; content of sorbitol crystallization nucleating agent is 10% by mass, polypropylene 3 parts by mass of an antifogging agent masterbatch (“P302AB” manufactured by Takemoto Yushi Co., Ltd., 10% by mass of a fatty acid ester compound as an antifogging agent, content of polypropylene resin) (Amount of 90% by mass) and 5 parts by mass were kneaded at room temperature to obtain a composition for forming a water vapor barrier layer.

<Manufacture of transparent multilayer film>
A modified polypropylene (modified PP, "QF551" manufactured by Mitsui Chemicals, Inc.) is prepared as a resin (adhesive resin) constituting the adhesive layer, and a copolymer of 6-nylon and 66-nylon is used as the resin constituting the intermediate layer ( Hereinafter, it may be abbreviated as “Ny6 / 66” (“5033X80” manufactured by Ube Industries, melting point: 196 ° C.), and as a resin constituting the oxygen barrier layer, a saponified ethylene-vinyl acetate copolymer ( EVOH, "E173B" manufactured by Kuraray Co., Ltd.) was prepared.

  The temperature of the die is set to 220 to 245 ° C., and the composition for forming an easy peel layer, the composition for forming a water vapor barrier layer, the modified PP, Ny6 / 66, and EVOH are co-extruded in this order, Easy peel layer (thickness 5 μm), water vapor barrier layer (thickness 15 μm), adhesive layer (thickness 7.5 μm), intermediate layer (thickness 12.5 μm), and oxygen barrier layer (thickness 10 μm) Was obtained in this order to obtain a transparent multilayer film (thickness: 50 μm) laminated in the thickness direction.

[Example 2]
As a resin constituting the intermediate layer, a copolymer of 6-nylon and 66-nylon (Ny6 / 66, “5034B” manufactured by Ube Industries, melting point 192 ° C.) was prepared.
The easy peel layer (in the same manner as in Example 1) except that this Ny6 / 66 having a melting point of 196 ° C. was used instead of Ny6 / 66 (“5033X80” manufactured by Ube Industries, Ltd.) was used. 5 μm), a water vapor barrier layer (15 μm in thickness), an adhesive layer (7.5 μm in thickness), an intermediate layer (12.5 μm in thickness), and an oxygen barrier layer (10 μm in thickness). In this order, a transparent multilayer film (thickness: 50 μm) laminated in the thickness direction was obtained.

[Comparative Example 1]
6-nylon (Ny6, “1030B2” manufactured by Ube Industries, melting point: 225 ° C.) was prepared as a resin constituting the intermediate layer.
Then, instead of Ny6 / 66 (“5033X80” manufactured by Ube Industries, Ltd.) having a melting point of 196 ° C., this 6-nylon was used, and the temperature of the die was changed to 250 to 270 ° C. instead of 220 to 245 ° C. Except for the above, in the same manner as in Example 1, an easy peel layer (5 μm in thickness), a water vapor barrier layer (15 μm in thickness), an adhesive layer (7.5 μm in thickness), and an intermediate layer (A thickness of 12.5 μm) and an oxygen barrier layer (a thickness of 10 μm) were laminated in this order in a thickness direction to obtain a transparent multilayer film (a thickness of 50 μm).

[Comparative Example 2]
6-nylon (Ny6, “1030B2” manufactured by Ube Industries, melting point: 225 ° C.) was prepared as a resin constituting the intermediate layer.
Then, instead of Ny6 / 66 (“5033X80” manufactured by Ube Industries, Ltd.) having a melting point of 196 ° C., the 6-nylon was used, and the temperature of the die was set to 270 to 290 ° C. instead of 220 to 245 ° C. Except that the amount of the composition for forming the easy peel layer was increased, and that the amount of the composition for forming the water vapor barrier layer was reduced, the same method as in Example 1 was used. A layer (9 μm in thickness), a water vapor barrier layer (11 μm in thickness), an adhesive layer (7.5 μm in thickness), an intermediate layer (12.5 μm in thickness), and an oxygen barrier layer (10 μm in thickness). In this order, a transparent multilayer film (thickness: 50 μm) formed by laminating in the thickness direction was obtained.

<< Evaluation of transparent multilayer film >>
<Evaluation of smoke suppression effect in manufacturing process>
In each of the above Examples and Comparative Examples, between the start of the production of the transparent multilayer film and the end of the production thereof, the production of the transparent multilayer film intermediate during the production, or from the transparent multilayer film, the presence or absence of smoke was visually confirmed. . Then, according to the following criteria, the smoke suppressing effect of the transparent multilayer film was evaluated. Table 1 shows the results.
(Evaluation criteria)
A: No fuming was observed or only a small amount of fuming was observed, and there was no effect on the production of the transparent multilayer film.
B: Smoke was moderately observed, which affected the production of the transparent multilayer film.
C: A large amount of smoke was generated, which had a significant effect on the production of the transparent multilayer film.

<Evaluation of antifogging property of transparent multilayer film>
Water (200 mL) at 40 ° C. was placed in a 500 mL beaker.
Then, the opening of the beaker was closed with the transparent multilayer films obtained in the above Examples and Comparative Examples. At this time, the easy peel layer of the transparent multilayer film was directed to the beaker side (in other words, the oxygen barrier layer was directed to the side opposite to the beaker side, that is, to the outside).
Then, immediately, the beaker was kept in this state in a refrigerator having an internal temperature of 10 ° C. and stored for 1 hour.
Next, the beaker was taken out of the refrigerator, and the transparent multilayer film covering the opening of the beaker was visually observed, and the antifogging property of the transparent multilayer film was evaluated according to the following criteria. Table 1 shows the results.
(Evaluation criteria)
A: Water spreads evenly on the surface of the transparent multilayer film, and the visibility ahead through the transparent multilayer film is good.
B: Water does not spread evenly on the surface of the transparent multilayer film, large water droplets are attached, and the front visibility through the transparent multilayer film is slightly poor.
C: Water does not spread evenly on the surface of the transparent multilayer film, small water droplets are attached, and the visibility ahead through the transparent multilayer film is extremely poor.

In addition, in the column of the easy peel layer and the column of the water vapor barrier layer in Table 1, the “apparent content (% by mass) of the anti-fogging agent” refers to the fact that the anti-fogging agent is used in the production process of the transparent multilayer film. It means the content of antifogging agent in these layers, assuming that they did not evaporate.
That is, the “apparent content (% by mass) of the antifogging agent” in the easy peel layer is defined as the antifogging agent based on the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming the easy peel layer. Of the content (parts by mass).
Similarly, the “apparent content (% by mass) of the antifogging agent” in the water vapor barrier layer refers to the antifogging amount relative to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming the vapor barrier layer. And the content (parts by mass) of the agent.

As is evident from the above results, in Examples 1 and 2, smoke was suppressed between the start of the production of the transparent multilayer film and the end of the production, and the production of the transparent multilayer film intermediate and the transparent multilayer film was suppressed. In each case, no condensation of the smoke-emitting component was observed, and a transparent multilayer film could be produced without any process abnormality.
In Examples 1 and 2, since the melting point of Ny6 / 66, which is the main constituent material of the intermediate layer, was 196 ° C or lower (192 to 196 ° C), the film forming temperature was 245 ° C or lower (220 to 245 ° C). , Could be relatively low. In Examples 1 and 2, the anti-fogging property of the transparent multilayer film was high, and this was because the film formation temperature was relatively low, so that the vaporization of the anti-fogging agent during the production process of the transparent multilayer film (in other words, at the time of film formation). It was supposed that this was because the content of the antifogging agent in the transparent multilayer film was kept high. This was consistent with the fact that smoke was suppressed as described above.

On the other hand, in Comparative Examples 1 and 2, during the period from the start of the production of the transparent multilayer film to the end of the production, smoking is not suppressed, and in both the transparent multilayer film intermediate and the transparent multilayer film, Condensation of fuming components was observed, and process abnormalities were observed.
In Comparative Examples 1 and 2, since the melting point of Ny6, which is a main constituent material of the intermediate layer, was 225 ° C., the film forming temperature had to be raised to 250 ° C. or higher (250 to 290 ° C.). Since the film formation temperature was high in this way, the vaporization of the anti-fogging agent was not suppressed during the production process of the transparent multilayer film (in other words, during film formation), and as a result, the content of the anti-fogging agent in the transparent multilayer film was low. It was presumed that the antifogging property of the transparent multilayer film was finally lowered. This was consistent with the fact that smoke was not suppressed as described above.

  In Comparative Examples 1 and 2, although the main constituent materials of the intermediate layer were the same, Comparative Example 2 had a higher film formation temperature, and as a result, Comparative Example 2 was more difficult in the process of manufacturing the transparent multilayer film. It was presumed that the amount of vaporization of the antifogging agent was large. Comparative Example 2 was inferior to Comparative Example 1 in both the effect of suppressing smoke in the production process of the transparent multilayer film and the anti-fogging property of the transparent multilayer film. Was consistent with

  INDUSTRIAL APPLICABILITY The present invention can be used for a food package.

DESCRIPTION OF SYMBOLS 1 ... Transparent multilayer film 11 ... Easy peel layer 12 ... Water vapor barrier layer 13 ... Intermediate layer 14 ... Oxygen barrier layer 2 ... Package 9 ... Resin tray

Claims (7)

An easy peel layer, a water vapor barrier layer, an intermediate layer, and an oxygen barrier layer are stacked and configured,
The water vapor barrier layer and the intermediate layer, the easy peel layer, and the oxygen barrier layer, disposed between,
The water vapor barrier layer is disposed adjacent to the easy peel layer,
A transparent multilayer film, wherein the intermediate layer contains a nitrogen-containing resin having a melting point of 210 ° C. or less.   The transparent multilayer film according to claim 1, wherein the easy peel layer contains an antifogging agent.   The transparent multilayer film according to claim 1, wherein the nitrogen-containing resin is a polyamide.   The transparent multilayer film according to any one of claims 1 to 3, wherein the water vapor barrier layer contains polypropylene.   The transparent multilayer film according to claim 1, wherein the thickness of the oxygen barrier layer is 15 μm or less.   The transparent multilayer film according to any one of claims 1 to 5, wherein the water vapor barrier layer contains a crystallization nucleating agent.   A package comprising the transparent multilayer film according to claim 1.

Images