JP6881408B2 - Transparent multilayer film and packaging - Google Patents

Description

The present invention relates to transparent multilayer films and packages.

One type of food packaging is a tray sealed with a lid film. In particular, a package sealed with a transparent lid 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 for a tray, a barrier property for suppressing the permeation of oxygen and water vapor, a pinhole resistance, and the like, and a transparent multilayer film is usually used (patented). Reference 1).

Japanese Unexamined Patent Publication No. 2005-288793

The transparent multilayer film is produced by forming a film by a method involving heating such as a coextrusion method. On the other hand, during the production of such a transparent multilayer film, a phenomenon called surging, in which the thickness of any of the layers fluctuates periodically, may be observed depending on the film forming conditions. For example, the constituent material of the water vapor barrier layer for suppressing the permeation of water vapor tends to cause surging, and when the film formation temperature is set low, the tendency becomes high. When surging occurs in any of the layers in this way, the entire transparent multilayer film becomes surging. On the other hand, it is not clear whether or not 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 an object of the present invention is to provide a transparent multilayer film in which surging is suppressed during its manufacture.

In order to solve the above problems, the present invention adopts the following configuration.
[1]. The easy peel layer, the water vapor barrier layer, the intermediate layer, and the oxygen barrier layer are laminated, and the water vapor barrier layer and the intermediate layer are between the easy peel layer and the oxygen barrier layer. The water vapor barrier layer is arranged adjacent to the easy peel layer, and the melt tension of the water vapor barrier layer is 0.2 g or more.
[2]. The transparent multilayer film according to [1], wherein the water vapor barrier layer contains one kind of polypropylene or two or more kinds of polypropylenes having different melt tensions.
[3]. The transparent multilayer film according to [1] or [2], wherein the water vapor barrier layer contains a crystallization nucleating agent.
[4]. The transparent multilayer film according to any one of [1] to [3], wherein the intermediate layer contains a polyamide.
[5]. The transparent multilayer film according to any one of [1] to [4], wherein the oxygen barrier layer has a thickness of 15 μm or less.
[6]. A packaging body comprising the transparent multilayer film according to any one of [1] to [5].

According to the present invention, there is provided a transparent multilayer film in which surging is suppressed during its production.

It is sectional drawing which shows typically an example of the transparent multilayer film which concerns on one Embodiment of this 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 the embodiment of the present invention is formed by laminating an easy peel layer, a water vapor barrier layer, an intermediate layer, and an oxygen barrier layer, and the water vapor barrier layer and the intermediate layer are the same. It is arranged between the easy peel layer and the oxygen barrier layer, the water vapor barrier layer is arranged adjacent to the easy peel layer, and the melt tension of the water vapor barrier layer is 0.2 g or more. It has become.
The transparent multilayer film of the present embodiment has transparency as a whole.

In the transparent multilayer film of the present embodiment, the melt tension of the water vapor barrier layer having the lowest melt tension is usually as high as 0.2 g or more. As a result, at the time of producing the transparent multilayer film of the present embodiment, surging can be suppressed in any layer even if the film formation temperature is low, and surging of the entire transparent multilayer film is suppressed.
In addition, in this specification, "melting tension" means "melting tension at 230 ° C." unless otherwise specified. The melt tension can be measured using a capillograph according to JIS K7199: 1999.

Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, in the figure used in the following description, in order to make it easy to understand the features of the present invention, the main part may be enlarged and shown, and the dimensional ratio of each component is the same as the actual one. Is not always the case.

FIG. 1 is a cross-sectional view schematically showing an example of a transparent multilayer film of the present embodiment.
The transparent multilayer film 1 shown here is configured by laminating 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 arranged between the easy peel layer 11 and the oxygen barrier layer 14. 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 composed of an easy peel layer 11, a water vapor barrier layer 12, an adhesive layer 15, an intermediate layer 13, and an oxygen barrier layer 14 laminated in this order in the thickness direction.

<Easy peel layer>
The easy peel layer 11 is one of the outermost layers of the transparent multilayer film 1, and is arranged on the outermost side of the transparent multilayer film 1 in the stacking direction of each layer constituting the transparent multilayer film 1.
A package can be constructed by sealing the transparent multilayer film 1 with another film or sheet by the easy peel layer 11 in the transparent multilayer film 1. The surface (in other words, the exposed surface, sometimes referred to as the "first surface" in the present specification) 11a of the easy peel layer 11 opposite to the water vapor barrier layer 12 side seals with another film or sheet. It becomes a sealing surface for.
The easy peel layer 11 has transparency.

The constituent material of the easy peel layer 11 may be a known material.
As the preferable easy peel layer 11, a layer showing peelability due to cohesive fracture can be mentioned.
Examples of the easy peel layer 11 exhibiting peelability due to coagulation fracture include those containing two types of incompatible polyolefins.

The two types of incompatible polyolefins contained in the easy peel layer 11 include, for example, an ethylene polymer having at least an ethylene-derived structural unit and a propylene-based weight having at least a propylene-derived structural unit. Coalescence and.

Examples of the ethylene-based polymer contained in the easy peel layer 11 include an ethylene homopolymer 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. Examples include polyethylene (HDPE).

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 an ethylene-vinyl acetate copolymer (EVA resin), an ethylene-methyl acrylate copolymer (EMA resin), an ethylene-methyl methacrylate copolymer (EMMA resin), and ethylene. -Ethyl acrylate copolymer (EEA resin), ethylene-acrylate copolymer (EAA resin), ethylene-methacrylic acid copolymer (EMAA resin), ethylene-ethyl acrylate-maleic anhydride copolymer (E) -EA-MAH resin), ionomer resin (ION resin) and the like.

The propylene-based polymer contained in the easy peel layer 11 includes a propylene homopolymer (that is, polypropylene or homopolypropylene, which may be referred to as "hPP" in the present specification) and a propylene-based copolymer. And.

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 a propylene-ethylene random copolymer (also known as polypropylene random copolymer, which may be referred to as "rPP" in the present specification) and a propylene-ethylene block copolymer (also known as "rPP"). : Polypropylene block copolymer, which may be referred to as "bPP" in the present specification) and the like.

The easy-peel layer 11 contains only one component that exhibits easy-peel properties, two or more, and if there are two or more, the combination and ratio thereof are as follows. It can be selected arbitrarily according to the purpose. For example, when the component exhibiting the easy peel property is the above-mentioned two types of incompatible polyolefins, 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 polymer to the total content (parts by mass) of the ethylene polymer and the propylene polymer shall be 10 to 90% by mass. Is preferable, and for example, it may be any of 15 to 70% by mass and 20 to 50% by mass. When the ratio is at least the lower limit value, the easy peel property of the easy peel layer 11 becomes better. When the ratio is not more than the upper limit value, the peel strength becomes more stable.
The ratio is usually the content (parts by mass) of the ethylene-based polymer with respect 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 later. It is the same as the ratio.

The easy peel layer 11 may contain other components in addition to the components exhibiting the easy peel properties (for example, the above-mentioned two incompatible polyolefins) as long as the easy peel properties are not impaired.
The other components contained in the easy peel layer 11 may be only one kind, may be two or more kinds, and when there are two or more kinds, the combination and ratio thereof may be determined according to the purpose. It can be selected arbitrarily.

In the easy peel layer 11, the ratio of the content of the component exhibiting the easy peel property to the total mass of the easy peel layer 11 (for example, the ratio of the total content of the above-mentioned two incompatible polyolefins) is 50. It is preferably ~ 100% by mass, and more preferably 70 to 100% by mass. When the ratio is at least the lower limit value, the easy peel property of the easy peel layer 11 becomes better.
The ratio is usually the ratio of the content (parts by mass) of the component exhibiting easy peeling property to the total content (parts by mass) of the component that does not vaporize at room temperature in the composition for forming an easy peel layer described later. It is the same.

In addition, in this specification, "room temperature" means a temperature which is not particularly cooled or heated, that is, a normal temperature, and examples thereof include a temperature of 15 to 25 ° C.

Examples of the other components contained in the easy peel layer 11 include anti-fog agents and anti-blocking agents.
Among them, the easy peel layer 11 preferably contains an antifogging agent as the other component.

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

The antifogging agent contained in the easy peel layer 11 may be only one type, may be 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.

When an antifogging agent is used, the ratio of the content of the antifogging 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, preferably 1.0. More preferably, it is ~ 4.5% by mass. When the ratio is at least the lower limit value, the effect of using the antifogging agent can be obtained more remarkably. When the ratio is not more than the upper limit value, the characteristics other than the antifogging property of the transparent multilayer film 1 become better.
The ratio is usually the same as the ratio of the antifogging agent content (parts by mass) 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 such that when the transparent multilayer films 1 are laminated, or when the transparent multilayer film 1 and another film or sheet are laminated, the transparent multilayer films 1 are stuck to each other or the transparent multilayer film 1 is laminated. It is a component for suppressing sticking (blocking) between 1 and a film or sheet adjacent thereto. The mode of "stacking the transparent multilayer films 1 on top of each other" also includes a mode of "winding one transparent multilayer film 1 in a roll shape".

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-blocking agent contained in the easy peel layer 11 may be only one type, may be two or more types, and when there are two or more types, the combination and ratio thereof may be arbitrary depending on the purpose. Can be selected.

When an anti-blocking agent is used, the ratio of the content of the anti-blocking agent to the total mass of the easy peel layer 11 in the easy peel layer 11 is preferably 0.05 to 3.0% by mass, preferably 0.1. More preferably, it is ~ 2.5% by mass. When the ratio is at least the lower limit value, the effect of using the anti-blocking agent can be obtained more remarkably. When the ratio is not more than the upper limit value, the characteristics other than the anti-blocking property of the transparent multilayer film 1 become better.
The ratio is usually the same as the ratio of the content of the antiblocking agent (parts by mass) 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 is composed of 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 in the case of the easy peel layer 11, "a plurality of layers may be the same or different from each other" means "all layers may be the same or all layers". May be different, or only some of the layers may be the same. ”Furthermore,“ a plurality of layers are different from each other ”means that“ at least one of the constituent materials and the thickness of each layer is different from each other. It means "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 in a sealed state with respect to the object to be sealed is peeled (that is, peeled), a part of the easy peel layer is in a state of being pulled between the peeled parts, and the peeled surface is not flat. In some cases (in the present specification, such a state may be referred to as "stringing"). On the other hand, when the thickness of the easy peel layer 11 is not more than the upper limit value, 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 fracture.

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 in 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 above-mentioned lower limit value and upper limit value. 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 to 9 μm, still more preferably 2 to 7.5 μm, and particularly preferably 2 to 6 μm. However, these are examples of the thickness of the easy peel layer 11.

When the easy peel layer 11 is composed of a plurality of layers, the total thickness of the plurality of layers may be set to be the above-mentioned preferable thickness of the easy peel layer 11.

<Water vapor barrier layer>
The water vapor barrier layer 12 is arranged 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 in this way.
The water vapor barrier layer 12 has transparency.

The melt tension of the water vapor barrier layer 12 is 0.2 g or more. Among the transparent multilayer films 1, when the melt tension of the water vapor barrier layer 12 that is most likely to cause surging is equal to or higher than the lower limit, surging of the entire transparent multilayer film 1 is suppressed.

The melt tension of the water vapor barrier layer 12 may be, for example, 0.3 g or more, 0.5 g or more, and 0.7 g or more in that the above-mentioned effect becomes higher.

The upper limit of the melting tension of the water vapor barrier layer 12 is not particularly limited. For example, the melt tension of the water vapor barrier layer 12 is preferably 1 g or less in that the water vapor barrier layer 12 is relatively easy to form.

The melting tension of the water vapor barrier layer 12 can be appropriately adjusted within a range set by arbitrarily combining the above-mentioned lower limit value and upper limit value. For example, in one embodiment, the melt tension of the water vapor barrier layer 12 is preferably 0.2 to 1 g, for example, any one of 0.3 to 1 g, 0.5 to 1 g, and 0.7 to 1 g. It may be. However, these are examples of the melt tension of the water vapor barrier layer 12.

The melt tension of the water vapor barrier layer 12 can be adjusted by adjusting the type and content of the components contained in the water vapor barrier layer 12, for example, the water vapor barrier resin described later.
The components contained in the water vapor barrier layer 12 exhibit the melt tension of the city (in other words, form a film or sheet having the melt tension of the city) according to the type of the component. Type and content can be selected.

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 polyethylenes such as low-density polyethylene (LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE); ethylene-α-olefin copolymer; polypropylene; propylene-ethylene random copolymer. Propylene-ethylene block copolymer; propylene-α-olefin copolymer; ethylene-cyclic olefin copolymer obtained by copolymerizing a cyclic olefin such as cyclopentadiene or norbornene; ethylene-vinyl acetate copolymer (EVA) Resin); partially saponified or completely saponified product of ethylene-vinyl acetate copolymer; ethylene- (meth) acrylic acid copolymer or esterified product thereof or ionic crosslinked product; ethylene- (meth) acrylic acid- (meth) acrylic Examples thereof include an acid ester ternary copolymer; maleic anhydride-modified polyethylene; maleic anhydride-polyethylene copolymer and the like.
Among these, the water vapor barrier layer 12 preferably contains polypropylene.
Further, in terms of increasing the melt tension of the water vapor barrier layer 12, the water vapor barrier layer 12 preferably contains a resin having branched chains, and more preferably contains a resin having many branched chains.

In addition, 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.

The water vapor barrier layer 12 preferably contains one type of polypropylene, or preferably contains two or more types of polypropylene having different melt tensions. For example, when only one type of polypropylene is selected, it may be difficult to set the melt tension of the water vapor barrier layer 12 to a desired value. In that case, the melt tension of the water vapor barrier layer 12 can be easily set by using two or more kinds of polypropylenes having different melt tensions in combination. That is, the melt tension of the water vapor barrier layer 12 can be easily adjusted by using polypropylene having a low melt tension and polypropylene having a high melt tension in combination in consideration of these melt tensions. For example, a polypropylene having a high melt tension is preferable, and a metallocene-based high melt tension polypropylene (in other words, a metallocene-catalyzed high melt tension polypropylene) can be mentioned.

Here, the case where the melt tension of the water vapor barrier layer 12 is adjusted by using polypropylene has been described, but the melt tension may be adjusted by using a component other than polypropylene.

For example, when the first component and the second component having a higher melt tension than the first component are used in combination as the contained component of the water vapor barrier layer 12 to adjust the melt tension of the water vapor barrier layer 12, the water vapor barrier is used. In layer 12, the ratio of the content of the second component (parts by mass) to the content (parts by mass) of the first component ([content of the second component of the water vapor barrier layer 12 (parts by mass)] / [steam barrier] The content (parts by mass) of the first component of the layer 12] × 100) is preferably 1 to 99% by mass, more preferably 3 to 97% by mass, and 6 to 94% by mass. Is more preferable, and for example, it may be any of 6 to 80% by mass, 6 to 60% by mass, 6 to 40% by mass, and 6 to 20% by mass.

The component exhibiting the water vapor barrier property (for example, the water vapor barrier resin) contained in the water vapor barrier layer 12 may be only one type, two or more types, or two or more types. , Their combinations and ratios can be arbitrarily selected according to the purpose.

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

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. Is preferable, and 70 to 100% by mass is more preferable. When the ratio is at least the lower limit value, the water vapor barrier property of the water vapor barrier layer 12 becomes higher.
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 the water vapor barrier layer described later. It 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.

Among them, 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 the layer containing the crystallization nucleating agent, as will be described later.
When the easy peel layer 11 exhibits peelability due to cohesive fracture, for example, when the easy peel layer 11 contains the above-mentioned two types of incompatible polyolefins, the easy peel layer 11 The transparency of the entire transparent multilayer film 1 tends to be lower than that of the case where the other sealant layer is provided instead. Therefore, in the present embodiment, when the easy peel layer 11 exhibits peelability due to cohesive fracture, it is particularly preferable that the water vapor barrier layer 12 contains a crystallization nucleating agent as the other component.

Further, when the water vapor barrier layer 12 contains two or more different components (particularly resin components), such as when two or more polypropylenes having different melt tensions are contained as described above, these 2 types are used. Depending on the affinity or compatibility of the components above the species, the transparency of the water vapor barrier layer 12 (as a result, the transparency of the entire transparent multilayer film 1) may decrease. Therefore, in the present embodiment, when the water vapor barrier layer 12 contains two or more kinds of components in this way, it is particularly preferable that the water vapor barrier layer 12 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 fogging of the transparent multilayer film 1, particularly 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 specific examples thereof include the same antifogging agent contained in the easy peel layer 11 described above.

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

When an antifogging agent is used, the ratio of the content of the antifogging agent to the total mass of the water vapor barrier layer 12 in the water vapor barrier layer 12 is preferably 0.05 to 3.0% by mass, preferably 0.1. More preferably, it is ~ 2.5% by mass. When the ratio is at least the lower limit value, the effect of using the antifogging agent can be obtained more remarkably. When the ratio is not more than the upper limit value, the characteristics other than the antifogging property of the transparent multilayer film 1 become better.
The ratio is usually the same as the ratio of the antifogging agent content (parts by mass) 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 type, may be two or more types, and when there are two or more types, the combination and ratio thereof may be determined according to the purpose. It can be selected arbitrarily.

When a crystallization nucleating agent is used, the ratio of the content of the crystallization nucleating agent to the total mass of the water vapor barrier layer 12 in the water vapor barrier layer 12 is preferably 0.05 to 3.0% by mass, and is 0. .1 to 2.5% by mass is more preferable. When the ratio is at least the lower limit value, the effect of using the crystallization nucleating agent can be obtained more remarkably. When the ratio is not more than the upper limit value, the characteristics other than the transparency of the water vapor barrier layer 12 become better.
The ratio is usually the same as the ratio of the content of the crystallization nucleating agent (parts by mass) 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 is composed of 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 at least the above lower limit value, 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 not more than the upper limit value, it is possible to prevent the water vapor barrier layer 12 from becoming excessively thick.
When the water vapor barrier layer 12 is composed of a plurality of layers, the total thickness of the plurality of layers may be set to be the above-mentioned preferable thickness of the water vapor barrier layer 12.

Water vapor permeability of the water vapor barrier layer 12 is, for example, 40 ° C., in an atmosphere of 90% RH (relative humidity), is preferably not more than 100g ^/ m 2 · day.
The amount of water vapor permeation of the water vapor barrier layer 12 can be measured according to, for example, JIS Z 0208.

<Middle layer>
The intermediate layer 13 imparts molding processability to the transparent multilayer film 1 and 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 lower as a constituent material thereof. In the present specification, unless otherwise specified, the "nitrogen-containing resin" means a nitrogen-containing resin having a melting point of 210 ° C. or lower.
The intermediate layer 13 has transparency.

The intermediate layer 13 preferably contains a nitrogen-containing resin having a melting point of 210 ° C. or lower as a constituent material thereof.
At the time of producing a transparent multilayer film, for example, each layer is molded (in other words, a film) by a method involving heating such as a coextrusion method using a resin or a resin composition for forming each layer constituting the transparent multilayer film.
On the other hand, the nitrogen-containing resin is usually preferable as a constituent material of the intermediate layer, but has a relatively high melting point. That is, the intermediate layer usually requires a higher film formation temperature than the other layers. Here, if the film formation temperature is too high, any layer constituting the transparent multilayer film or the resin composition for forming the transparent multilayer film can be used between the start of production and the end of production of the transparent multilayer film. , A component with a relatively low boiling point may vaporize and be observed as smoke. In that case, the smoke-generating component (that is, the vaporized component described above) condenses due to cooling, which causes a process abnormality and makes it impossible to normally produce the transparent multilayer film. Such smoke generation is observed not only when the film formation temperature is too high, but also when the thickness of any layer formed (deposited) from the resin composition containing a component causing smoke generation is low. Be done. Examples of the component that easily causes such smoke generation include the above-mentioned antifogging agent.
On the other hand, in the transparent multilayer film 1, if the melting point of the nitrogen-containing resin contained in the intermediate layer 13 is 210 ° C. or lower, which is a relatively low melting point, each layer in the transparent multilayer film 1 contains the air. As a component that can be converted (for example, typically an antifogging agent), it is easy to select a component having a boiling point higher than 210 ° C. (in other words, the melting point of the nitrogen-containing resin). That is, the transparent multilayer film 1 can sufficiently suppress smoke generation from the start of production to the end of production. For example, in the transparent multilayer film 1, if the upper limit of the thickness of the layer containing the antifogging agent (for example, the easy peel layer 11 and the water vapor barrier layer 12 described above) is 40 μm, such smoke generation occurs. The inhibitory effect can be obtained more remarkably.

In this way, smoke generation can be suppressed by adopting a relatively low film formation temperature during the production of the transparent multilayer film, but on the other hand, when the film formation temperature is low, the transparent multilayer film is usually produced. Is prone to surging. However, as described above, the transparent multilayer film of the present embodiment suppresses surging even when the film formation temperature is low.

The nitrogen-containing resin contained in the intermediate layer 13 preferably has a nitrogen atom in its main chain.
Above all, it is more preferable that the nitrogen-containing resin is polyamide, that is, the intermediate layer 13 contains polyamide.

Examples of the polyamide include cyclic lactams (lactams having 3 or more ring members), amino acids, or polyamides obtained by polymerizing or copolymerizing a nylon salt obtained by reacting a diamine with a dicarboxylic acid. Can be mentioned.

Examples of the cyclic lactam include ε-caprolactam, ω-enantractam, 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 forming the nylon salt include tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2. Aliphatic amines such as 4-trimethylhexamethylenediamine and 2,4,4-trimethylhexamethylenediamine;
1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, isophorone diamine, piperazine, bis (4-aminocyclohexyl) methane, 2,2-bis- (4-aminocyclohexyl) propane, etc. Alicyclic diamine;
Examples thereof include aromatic diamines such as m-xylylenediamine and paraxylylenediamine.

Examples of the dicarboxylic acid forming the nylon salt include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sepatic acid, undecandic acid, and dodecandioic acid;
Hexahydroterephthalic acid, and alicyclic carboxylic acids such as hexahydroisophthalic acid;
Telephthalic 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- Examples thereof include 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, 612-nylon, 6T-nylon, 6I nylon, copolymer of 6-nylon and 66-nylon (nylon 6/66), copolymer of 6-nylon and 610-nylon, 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 , 6-Nylon, 66-Nylon and 610-Nylon Copolymer, 6-Nylon, 66-Nylon and 12-Nylon Copolymer (Nylon 6/66/12), 6-Nylon, 66-Nylon and 612-Nylon Copolymer with, 66-Nylon and 6T-Nylon, 66-Nylon and 6I-Nylon, 6T-Nylon and 6I-Nylon, 66-Nylon, 6T-Nylon and 6I-Nylon Examples include copolymers.

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, availability, and the like. Is preferable.

The nitrogen-containing resin contained in the intermediate layer 13 may be only one type, may be 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.

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

The lower limit of the melting point of the nitrogen-containing resin is not particularly limited. For example, in that the nitrogen-containing resin is relatively easy to obtain, 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. It is particularly preferable that the temperature is 175 ° C. or higher.

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

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 components contained in the intermediate layer 13 may be only one kind, two or more kinds, and when there are two or more kinds, the combination and ratio thereof are arbitrary depending on 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 at least the lower limit value, the effect obtained by the transparent multilayer film 1 including the intermediate layer 13 becomes higher.
The ratio is usually the same as the ratio of the content of the nitrogen-containing resin (parts by mass) to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming an intermediate layer described later.

Examples of the other components contained in the intermediate layer 13 include antioxidants 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 is composed of 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 at least the above lower limit value, the effect obtained by the transparent multilayer film 1 including the intermediate layer 13 becomes higher. When the thickness of the intermediate layer 13 is not more than the upper limit value, it is possible to prevent the intermediate layer 13 from becoming excessively thick.
When the intermediate layer 13 is composed of a plurality of layers, the total thickness of the plurality of layers may be set to be the above-mentioned preferable thickness of the intermediate layer 13.

<Oxygen barrier layer>
The oxygen barrier layer 14 is the outermost layer of the other in the transparent multilayer film 1, and is arranged on the outermost side of the other side opposite to the easy peel layer 11 in the stacking direction of each layer constituting the transparent multilayer film 1. There is.
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 ethylene-vinyl alcohol copolymer (also known as ethylene-vinyl acetate copolymer saponified product, EVOH), polyamide, polyvinyl alcohol, and polyacrylonitrile.
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 with respect to the total amount of the constituent units in the ethylene-vinyl alcohol copolymer). It is more preferable to contain an ethylene-vinyl alcohol copolymer having an (ratio of the amount of the derived constituent units) of 30 to 50 mol%.

The oxygen barrier layer 14 contains only one type of component exhibiting oxygen barrier properties (for example, the oxygen barrier resin), two or more types, or two or more types. , Their combinations and ratios 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 components contained in the oxygen barrier layer 14 may be only one type, may be two or more types, and when there are two or more types, the combination and ratio thereof may be determined according to the purpose. It can be selected arbitrarily.

In the oxygen barrier layer 14, the ratio of the content of the component exhibiting the oxygen barrier property 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. Is preferable, and 70 to 100% by mass is more preferable. When the ratio is equal to or higher than the lower limit value, the oxygen barrier property of the oxygen barrier layer 14 becomes higher.
The ratio is usually the same as the ratio of the content (parts by mass) of the component exhibiting oxygen barrier property to the total content (parts by mass) of the component that does not vaporize at room temperature in the composition for forming an intermediate layer described later. Is.

Examples of the other components contained in the oxygen barrier layer 14 include antioxidants 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 is composed of 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 not more than the upper limit value, the oxygen barrier layer 14 maintains a good oxygen barrier property and is highly effective in suppressing deterioration of appearance such as foaming during film formation.

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 in that the oxygen barrier property of the oxygen barrier layer 14, in other words, the oxygen barrier property of the transparent multilayer film 1 is further improved.

The thickness of the oxygen barrier layer 14 can be appropriately adjusted within a range set by arbitrarily combining the above-mentioned lower limit value and upper limit value. 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 is composed of a plurality of layers, the total thickness of the plurality of layers may be set to be the above-mentioned preferable thickness of the oxygen barrier layer 14.

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

<Adhesive layer>
The adhesive layer 15 adheres 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 arbitrary 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 polyolefin resins and the like.
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 ethylene-based copolymers, propylene-based copolymers, butene-based copolymers, and modified products of these copolymers (in other words, modified copolymers). 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, and a modified product (modified copolymer) thereof.
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 specific examples of such a propylene-based copolymer include maleic anhydride graft-modified linear low-density polypropylene and propylene-based thermoplastic elastomer.
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 adhesive layer 15 contains only one type of component (for example, the adhesive resin) that exhibits adhesiveness, may be two or more types, and if there are two or more types, they may be used. The combination and ratio of the above can be arbitrarily selected according to the purpose.

The adhesive layer 15 may contain other components in addition to the component exhibiting adhesiveness (for example, the adhesive resin) as long as the adhesiveness is not impaired.
The other components contained in the adhesive layer 15 may be only one type, two or more types, and when two or more types, the combination and ratio thereof are arbitrary depending on 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 higher than the lower limit value, the adhesiveness of the adhesive layer 15 becomes higher.
The ratio is usually the same as the ratio of the content (parts by mass) of the component exhibiting adhesiveness to the total content (parts by mass) of the component that does not vaporize at room temperature in the composition for forming an adhesive layer described later. is there.

Examples of the other components contained in the adhesive layer 15 include antioxidants 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 is composed of 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 greater than the lower limit, the adhesive layer 15 has better adhesiveness. When the thickness of the adhesive layer 15 is not more than the upper limit value, it is possible to prevent the adhesive layer 15 from becoming excessively thick.
When the adhesive layer 15 is composed of a plurality of layers, the total thickness of the plurality of layers may be set to be the above-mentioned preferable thickness of the adhesive layer 15.

The haze of the transparent multilayer film 1 is preferably 12% or less, and more preferably 10% or less.
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 can be 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 haze. 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, the amount used when the crystallization nucleating agent is used, and the like.

In the present specification, the “film haze” means a film measured in accordance with JIS K 7136: 2000.

The transparent multilayer film of the present embodiment is not limited to the above-described embodiment, and a part of the structure may be changed, deleted or added 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. May also have other layers, which are not applicable.
The other layer is not particularly limited and may be arbitrarily selected depending on the intended purpose.
For example, the transparent multilayer film 1 may be provided with an adhesive layer similar to the adhesive layer 15 in the other two layers other than between the water vapor barrier layer 12 and the intermediate layer 13.

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

Further, in the transparent multilayer film, a resin or a resin composition serving as a material for forming any of the layers thereof is coated on the surface of another layer for forming the transparent multilayer film, if necessary. It can also be produced by forming a laminated structure in a transparent multilayer film by drying and, if necessary, further laminating layers other than these so as to have a desired arrangement form.

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

Further, the transparent multilayer film is required by laminating two or more films separately prepared in advance by a thermal (heat) laminating method or the like without using an adhesive. Depending on the situation, it can also be manufactured by further laminating layers other than these so as to have a desired arrangement form.

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

The resin composition used as a material for forming any of the layers in the transparent multilayer film adjusts the type and content of the contained components so that the formed layer contains the desired component at the desired content. Then, it may be manufactured. For example, the ratio of the contents of the components that do not vaporize at room temperature in the resin composition is usually the same as the ratio of the contents of the components in the 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 the present specification, it may be referred to as a "composition for forming an easy peel layer"). Examples thereof include those containing a component exhibiting easy peeling property (for example, the above-mentioned two types of incompatible polyolefins) and other components. Examples of the other component in the easy peel layer include the anti-fog agent and the anti-blocking 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 the present specification, it may be referred to as a "water vapor barrier layer forming composition"). Examples thereof include those containing a component exhibiting a water vapor barrier property (for example, the water vapor barrier resin) and other components. Examples of the other component in the composition for forming a water vapor barrier layer include the antifogging agent and the crystallization nucleating agent.

As a resin composition for forming an intermediate layer (intermediate layer 13 in the transparent multilayer film 1 shown in FIG. 1) (in the present specification, it may be referred to as a “composition for forming an intermediate layer”). For example, those containing the nitrogen-containing resin and other components may be mentioned. Examples of the other components in the composition for forming an intermediate layer include antioxidants and the like.

A resin composition for forming an oxygen barrier layer (in the transparent multilayer film 1 shown in FIG. 1, the oxygen barrier layer 14) (in the present specification, it 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 antioxidants and the like.

As a resin composition for forming an adhesive layer (adhesive layer 15 in the transparent multilayer film 1 shown in FIG. 1) (in the present specification, it may be referred to as an "adhesive layer forming composition"). For example, those containing a component exhibiting adhesiveness (for example, the adhesive resin) and other components other than that may be mentioned. Examples of the other components in the composition for forming an adhesive layer include antioxidants and the like.

<< Packaging >>
The package according to one embodiment of the present invention includes the transparent multilayer film.
The transparent multilayer film can be formed into various packages by sealing the transparent multilayer film with another resin film, a resin sheet or a resin tray (in other words, a resin bottom material) by the easy peel layer in the transparent multilayer film.

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 showing an example of the package of the present embodiment.
In FIG. 2, the same components as those shown in FIG. 1 are designated 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, which is 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 of the resin tray 9 (sometimes referred to as a "first surface" in the present specification) 9a is concave, and the peripheral edge 90a thereof is flat. There is.

In the package 2, the peripheral edge portion 110a of the first surface 11a of the easy peel layer 11 in the transparent multilayer film 1 and the peripheral edge portion 90a of the first surface 9a of the resin tray 9 are sealed and adhered to each other. doing. The easy peel layer 11 and the resin tray 9 are not sealed (closely adhered) in regions other than these peripheral edges (the peripheral edges 110a and the peripheral edges 90a). By sealing the transparent multilayer film 1 and the resin tray 9 in this way, the package 2 is accommodated by being surrounded by the first surface 11a of the easy peel layer 11 and the first surface 9a of the resin tray 9. It has a space S. The packaging object 8 is housed and sealed in the storage space S.

In the packaging body 2, the packaging object 8 housed in the storage space S can be clearly seen through the transparent multilayer film 1.

When the package 2 is opened, the transparent multilayer film 1 is peeled off from the resin tray 9, so that the easy peel layer 11 in the transparent multilayer film 1 is easily peeled off.

The package of the present embodiment is not limited to the above-described embodiment, and a part of the package may be changed, deleted or added without departing from the spirit of the present invention.

For example, in the package 2 shown in FIG. 2, the peripheral edge portion 90a of the first surface 9a of the resin tray 9 is flat, but the peripheral edge portion 90a may have another shape such as a curved surface. ..
Further, although FIG. 2 shows the package 2 using the transparent multilayer film 1, the package of the present embodiment uses the transparent multilayer film of the present invention other than the transparent multilayer film 1. May be good.
Further, in FIG. 2, the packaging body 2 using the resin tray 9 is shown as the sealing object of the transparent multilayer film 1, but the packaging body of the present embodiment is used as the sealing object of the transparent multilayer film 1. A resin film or a resin sheet may be used instead of the resin tray.

<< Manufacturing method of packaging >>
The package uses the transparent multilayer film, and seals (bonds) the transparent multilayer film with another resin film, resin sheet, or resin tray so as to form a desired storage space. Can be manufactured. The sealing at this time is preferably performed while heating (performing by heating lamination).
When the resin tray is used, for example, a flat resin sheet may be formed into a desired shape by a known method to prepare a resin tray.

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 shown below.

<< Manufacturing of transparent multilayer film >>
[Example 1]
<Manufacturing of composition for forming easy peel layer>
27 parts by mass of low density polyethylene (LDPE, "F522N" manufactured by Ube Maruzen Polyethylene), 40 parts by mass of polypropylene random copolymer (rPP, "S131" manufactured by Sumitomo Chemical Co., Ltd.), and antifogging agent master batch ("F522N" manufactured by Takemoto Oil & Fat Co., Ltd. "P302AB", the content of the fatty acid ester compound which is an antifogging agent is 10% by mass, the content of the polypropylene resin is 90% by mass) and 30 parts by mass, and the anti-blocking agent master batch ("A22" manufactured by Sumitomo Chemical Co., Ltd.), The content of the silica content, which is an anti-blocking agent, was 10% by mass, and the content of the polyethylene-based resin was 90% by mass), and 3 parts by mass was kneaded at room temperature to obtain a composition for forming an easy peel layer.

<Manufacturing of composition for forming water vapor barrier layer>
72 parts by mass of homopolypropylene (hPP, "WF836DG3" manufactured by Sumitomo Chemical Co., Ltd., melting tension at 230 ° C. 0.1 g) and metallocene-based high melt tension polypropylene (hmsPP, "MFX3" manufactured by Japan Polypropylene Corporation, melting at 230 ° C.) (Tension 5.0 g) 10 parts by mass, crystallization nucleating agent master batch ("PPM-NAT94" manufactured by Tokyo Ink Co., Ltd., content of sorbitol-based crystallization nucleating agent is 10% by mass, content of polypropylene-based resin is 90% by mass. %) 3 parts by mass and 5 parts by mass of the antifogging agent master batch (“P302AB” manufactured by Takemoto Oil & Fat Co., Ltd., the content of the fatty acid ester compound which is the antifogging agent is 10% by mass, and the content of the polypropylene resin is 90% by mass). The parts were kneaded at room temperature to obtain a composition for forming a steam barrier layer. In this composition for forming a water vapor barrier layer, the ratio of the content of hmsPP to the content of hPP was 10% by mass.

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

The temperature of the die is set 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 to make an easy peel. A layer (thickness 5 μm), a water vapor barrier layer (thickness 15 μm), an adhesive layer (thickness 7.5 μm), an intermediate layer (thickness 12.5 μm), and an oxygen barrier layer (thickness 10 μm) , In this order, a transparent multilayer film (thickness 50 μm) constructed by being laminated in these thickness directions was obtained.

[Example 2]
The ratio of the content of hmsPP to the content of hPP in the composition for forming a water vapor barrier layer by increasing the amount of hmsPP used and reducing the amount of hPP used during the production of the composition for forming a water vapor barrier layer. The easy peel layer (thickness 5 μm), the water vapor barrier layer (thickness 15 μm), and the adhesive layer were obtained in the same manner as in Example 1 except that the amount was changed to 15% by mass instead of 10% by mass. A transparent multilayer film (thickness 7.5 μm), an intermediate layer (thickness 12.5 μm), and an oxygen barrier layer (thickness 10 μm) laminated in this order in these thickness directions (a transparent multilayer film (thickness 12.5 μm)). A thickness of 50 μm) was obtained. In this example, the total amount of the composition for forming the water vapor barrier layer was the same as in the case of Example 1.

[Example 3]
The ratio of the content of hmsPP to the content of hPP in the composition for forming a water vapor barrier layer by reducing the amount of hmsPP used and increasing the amount of hPP used during the production of the composition for forming a water vapor barrier layer. The easy peel layer (thickness 5 μm), the water vapor barrier layer (thickness 15 μm), and the adhesive layer were obtained in the same manner as in Example 1 except that the amount was changed to 5% by mass instead of 10% by mass. A transparent multilayer film (thickness 7.5 μm), an intermediate layer (thickness 12.5 μm), and an oxygen barrier layer (thickness 10 μm) laminated in this order in these thickness directions (a transparent multilayer film (thickness 12.5 μm)). A thickness of 50 μm) was obtained. In this example, the total amount of the composition for forming the water vapor barrier layer was the same as in the case of Example 1.

[Example 4]
The ratio of the content of hmsPP to the content of hPP in the composition for forming a water vapor barrier layer by reducing the amount of hmsPP used and increasing the amount of hPP used during the production of the composition for forming a water vapor barrier layer. The easy peel layer (thickness 5 μm), the water vapor barrier layer (thickness 15 μm), and the adhesive layer were obtained in the same manner as in Example 1 except that the amount was changed to 3% by mass instead of 10% by mass. A transparent multilayer film (thickness 7.5 μm), an intermediate layer (thickness 12.5 μm), and an oxygen barrier layer (thickness 10 μm) laminated in this order in these thickness directions (a transparent multilayer film (thickness 12.5 μm)). A thickness of 50 μm) was obtained. In this example, the total amount of the composition for forming the water vapor barrier layer was the same as in the case of Example 1.

[Comparative Example 1]
The ratio of the content of hmsPP to the content of hPP in the composition for forming a water vapor barrier layer by reducing the amount of hmsPP used and increasing the amount of hPP used during the production of the composition for forming a water vapor barrier layer. The easy peel layer (thickness 5 μm), the water vapor barrier layer (thickness 15 μm), and the adhesive layer were obtained in the same manner as in Example 1 except that the amount was changed to 1% by mass instead of 10% by mass. A transparent multilayer film (thickness 7.5 μm), an intermediate layer (thickness 12.5 μm), and an oxygen barrier layer (thickness 10 μm) laminated in this order in these thickness directions (a transparent multilayer film (thickness 12.5 μm)). A thickness of 50 μm) was obtained. In this comparative example, the total amount of the composition for forming the water vapor barrier layer was the same as in the case of Example 1.

<< Evaluation of water vapor barrier layer >>
<Measurement of melt tension of water vapor barrier layer>
The same water vapor barrier layer as in the case of producing the transparent multilayer film in each of the above Examples and Comparative Examples was separately prepared independently. Using a Capillograph manufactured by DJK, the melt tension of this separately prepared water vapor barrier layer was measured at 230 ° C. in accordance with JIS K7199: 1999. The results are shown in Table 1.

<< Evaluation of transparent multilayer film >>
<Evaluation of surging suppression effect during manufacturing>
In each of the above Examples and Comparative Examples, the presence or absence of surging in the obtained transparent multilayer film was visually confirmed. Then, the surging suppressing effect of the transparent multilayer film was evaluated according to the following criteria. The results are shown in Table 1.
(Evaluation criteria)
A: No surging was observed.
B: Surging was observed.

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 (mass%) of the antifogging agent" means that the antifogging agent is used in the manufacturing process of the transparent multilayer film. It means the content of the antifogging agent in these layers, assuming that they did not vaporize.
That is, the "apparent content (% by mass) of the antifogging agent" in the easy peel layer is the antifogging agent with respect to 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. It is the same as the ratio of the content (parts by mass) of.
Similarly, the "apparent content (% by mass) of the antifogging agent" in the water vapor barrier layer is the antifogging relative to the total content (parts by mass) of the components that do not vaporize at room temperature in the composition for forming the water vapor barrier layer. It is the same as the ratio of the content (parts by mass) of the agent.

As is clear from the above results, in Examples 1 to 4, surging of the transparent multilayer film was suppressed during the production of the transparent multilayer film.
In Examples 1 to 4, the melt tension of the water vapor barrier layer was 0.25 g or more (0.25 to 0.84 g).

On the other hand, in Comparative Example 1, surging of the transparent multilayer film was not suppressed during the production of the transparent multilayer film.
In Comparative Example 1, the melt tension of the water vapor barrier layer was 0.15 g.

The present invention can be used for food packaging.

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)

The easy peel layer, the water vapor barrier layer, the intermediate layer, and the oxygen barrier layer are laminated and configured.
The water vapor barrier layer and the intermediate layer are arranged between the easy peel layer and the oxygen barrier layer.
The water vapor barrier layer is arranged adjacent to the easy peel layer, and is arranged adjacent to the easy peel layer.
The water vapor barrier layer contains two or more types of polypropylene having different melt tensions.
A transparent multilayer film having a melt tension of 0.2 g or more for the water vapor barrier layer. The easy peel layer, the water vapor barrier layer, the intermediate layer, and the oxygen barrier layer are laminated and configured.
The water vapor barrier layer and the intermediate layer are arranged between the easy peel layer and the oxygen barrier layer.
The water vapor barrier layer is arranged adjacent to the easy peel layer, and is arranged adjacent to the easy peel layer.
A transparent multilayer film having a melt tension of 0.25 g or more for the water vapor barrier layer. The transparent multilayer film according to claim 2 , wherein the water vapor barrier layer contains one kind of polypropylene or two or more kinds of polypropylenes having different melt tensions. The transparent multilayer film according to any one of claims 1 to 3, wherein the water vapor barrier layer contains a crystallization nucleating agent. The transparent multilayer film according to any one of claims 1 to 4 , wherein the intermediate layer contains a polyamide. The transparent multilayer film according to any one of claims 1 to 5 , wherein the oxygen barrier layer has a thickness of 15 μm or less. A package comprising the transparent multilayer film according to any one of claims 1 to 6.

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