WO2022239700A1

WO2022239700A1 - Composite film, lid, and content-filled, lid-equipped container

Info

Publication number: WO2022239700A1
Application number: PCT/JP2022/019531
Authority: WO
Inventors: 栞小野; 誠悟 ▲吉▼村; 遼治谷川
Original assignee: 共同印刷株式会社
Priority date: 2021-05-14
Filing date: 2022-05-02
Publication date: 2022-11-17
Also published as: JP2022175739A

Abstract

The present invention forms a laminate having a specific layer configuration which uses specific materials from a composite film for forming a resealable package by heat-sealing, and as a result, makes it easy to break the inner edge even when opening in a low-temperature environment and minimizes residue of a film comprising an adhesive layer and a heat-sealing layer on the resealing part.

Description

Composite film, lidding material, and lidded container containing contents

The present invention relates to a composite film, a lid material, and a lidded container containing contents.

Conventionally, various types of packages with a resealing function have been used as a means of packaging foods, medicines, etc. that cannot be consumed at once. As such a package, sealing using a multi-layer film has been proposed, which can impart a resealing function to the package itself without attaching an accessory such as a zipper.

As a resealable multilayer film, for example, a surface resin layer (A) containing a thermoplastic resin (a) as a main component and a styrene-based thermoplastic elastomer (b) having specific physical properties as a main component. A laminate is disclosed in which an adhesive resin layer (B) and a heat-sealable resin layer (C) containing an olefin resin (c) as a main component are laminated in the order of (A)/(B)/(C). (see Patent Document 1).

A package in which the multilayer film described in Patent Document 1 is heat-sealed to a container body or the like and sealed can be opened and resealed without causing any problems.

Here, in the package heat-sealed and sealed to the container body, the mechanism that enables opening and resealing is that the adhesive resin layer (B) and the heat This is due to breakage of the sealing resin layer (C) (hereinafter sometimes referred to as "edge breakage").

Taking as an example a package in which a lid material is heat-sealed to a container body, the mechanism that enables opening and resealing will be described using FIG.

FIG. 2 is a diagram showing a lidded container 300 containing contents formed using the lid material 100. FIG. When the lidded container 300 containing contents is opened, as shown in FIG. 2(a), the tab 110 protruding from the flange portion 202 is grasped and the lid material 100 is pulled up to correspond to the outer periphery of the joint portion 202a. At a position, the adhesive layer 104 and the heat seal layer 106 are broken (outer edge cut), exposing the first break 120a corresponding to this position.

Further, when the lid material 100 is pulled up, the lid material 100 delaminates at the interface between the base material layer 102 and the adhesive layer 104 as shown in FIG. 2(b). After that, when the delamination reaches the position corresponding to the inner periphery of the joint portion 202a, as shown in FIG. is exposed, and a resealing portion 104a is formed on the flange portion 202 of the container body 200. As shown in FIG.

That is, the resealing portion 104a is formed by cutting the adhesive layer 104 and the heat seal layer from the lid material 100 by cutting the outer edge, delaminating the layers, and cutting the inner edge in the region of the joint portion 202a formed in the flange portion 202. 106, and the adhesive layer 104 is exposed on the surface.

When resealing the opened lidded container 300 containing contents, the lid material 100 is pressed against the resealing portion 104a, so that the base material layer 102 and the adhesive layer 104 are in close contact with each other and resealed. becomes.

JP 2007-125820 A

In a low-temperature environment, it may be difficult to break the inner edge of the package described in Patent Document 1, which is heat-sealed with a multilayer film. Therefore, when the container is unsealed in a low-temperature environment, the resealing portion may not be cut off due to the broken inner edge, and the film composed of the adhesive layer and the heat-sealing layer may remain on the flange portion of the container.

The present invention has been made in view of the above background. It is an object of the present invention to provide a composite film, a lid material formed from the composite film, and a lidded container containing a content, which can suppress the residue of a film composed of.

The present inventors have made intensive studies to solve the above problems. Then, if the composite film for forming a package that can be heat-sealed and resealed is a laminate with a specific laminate structure using a specific material, the inner edge will be cut even if it is opened in a low temperature environment. The present inventors have found that the adhesive layer and the heat-sealable layer can be prevented from remaining in the resealing portion, thereby completing the present invention. That is, the present invention is as follows.

<<Aspect 1>>
Including a base material layer, an adhesive layer, and a heat seal layer in this order,
The base material layer and the heat seal layer are adhered to each other by the adhesive layer,
The adhesive layer contains a thermoplastic elastomer and a rosin ester, and the heat seal layer contains a polyethylene resin,
composite film.
<<Aspect 2>>
The composite film according to aspect 1, wherein the thermoplastic elastomer is a styrenic thermoplastic elastomer.
<<Aspect 3>>
The composite film according to

aspect

1 or 2, wherein the thermoplastic elastomer is a styrene-butadiene-butylene-styrene copolymer.
<<Aspect 4>>
The composite film according to any one of aspects 1 to 3, wherein the adhesive layer has a thickness of 5 μm or less.
<<Aspect 5>>
The composite film according to any one of aspects 1-4, wherein the heat seal layer is a polyethylene resin layer having a density of 0.920-0.958 g/cm ³ .
<<Aspect 6>>
6. The composite film of aspect 5, wherein the polyethylene resin layer comprises only high density polyethylene, or high density polyethylene and low density polyethylene.
<<Aspect 7>>
The composite film according to aspect 6, wherein the content of the high-density polyethylene is 50% by mass or more based on the total mass of the heat seal layer.
<<Aspect 8>>
A lid material formed from the composite film according to any one of aspects 1 to 7.
<<Aspect 9>>
The lidding material according to aspect 8, which is for resealing.
<<Aspect 10>>
The lid material according to aspect 8 or 9, which does not have a half cut on the heat seal layer side.
<<Aspect 11>>
a container body having a storage portion and a flange portion;
a content housed in the container body;
a lid material formed from the composite film according to any one of aspects 1 to 7;
with
the heat seal layer is heat sealed to the flange to form a resealable joint;
Container with lid containing contents.
<<Aspect 12>>
The container body is a paper cup,
The lidded container containing contents according to aspect 11, wherein the flange portion is coated with a polyethylene-based resin.

According to the composite film of the present invention, the heat seal layer is heat-sealed to the container body or the like to form a resealable package. It is possible to suppress the remaining of the film composed of the adhesive layer and the heat seal layer on the part.

In addition, in a package formed by heat-sealing the heat-seal layer of the composite film of the present invention to a container body or the like, the heat-seal layer is broken at both the outer edge and the inner edge of the heat-sealed joint. Therefore, it is not necessary to provide a cut (half-cut) for opening from the surface of the composite film on the heat seal layer side.

Therefore, there is no need to provide a half-cut along the area intended to be heat-sealed with the container, for example, the area to be heat-sealed with the flange portion of the container body, and no alignment operation is required during heat-sealing. , composite films, lids, and containers with lids.

1 is a cross-sectional view of a composite film according to one embodiment of the invention; FIG. FIG. 4 is a diagram showing a peeling mechanism when the lidded container containing contents according to one embodiment of the present invention is opened.

《Composite film》
The composite film of the present invention is a composite film in which at least a substrate layer, an adhesive layer, and a heat seal layer are laminated in this order, and the substrate layer and the heat seal layer are adhered to each other by the adhesive layer. there is The adhesive layer and the heat seal layer are made of specific materials.

The structure of the composite film of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of one embodiment of the composite film of the present invention.

The composite film 10 according to one embodiment of the composite film of the present invention shown in FIG. an adhesive layer 4 arranged adjacent to the resin layer 3; and a heat seal layer 5 laminated inside the adhesive layer 4.

In the composite film 10 according to one embodiment of the composite film of the present invention shown in FIG. 1, the base layer is a laminate composed of three layers. , an aluminum layer 2 and a resin layer 3 . In the composite film 10 shown in FIG. 1, a substrate layer, an adhesive layer 4, and a heat seal layer 5 are laminated in this order.

The composite film of the present invention may optionally include layers other than the base material layer, the adhesive layer, and the heat-seal layer as essential components.

The thickness of each layer constituting the composite film of the present invention can be appropriately determined according to the use of the composite film.

<Base material layer>
The substrate layer is an essential constituent layer in the composite film of the present invention. The base material layer is adjacent to the adhesive layer and adhered to the heat seal layer by the adhesive layer. In the composite film of the present invention, the substrate layer may be a single layer or a laminate composed of multiple layers.

In the composite film of the present invention, the substrate layer, the adhesive layer, and the heat seal layer are laminated in this order. It may be the outer layer. In this case, the substrate layer can serve as a protective layer when the innermost heat seal layer is heat-sealed to form a structure. In addition, it can also be a printing layer for printing for displaying contents and the like.

When the substrate layer is a single layer, the substrate layer may be a resin layer made of a resin, particularly a resin that serves as a protective layer and enables printing. Commonly used resins can be used as the material for forming the resin layer that serves as the base material layer. ), polyolefins such as polyethylene (PE), polypropylene (PP) and polystyrene (PS), polyamides (PA) such as nylon-6 and nylon-66, and polycarbonate (PC).

It should be noted that the above resins may be blended not only by one type but also by blending two or more types, and if necessary, additives and the like for imparting functionality and the like may be blended.

From the viewpoint of improving the adhesiveness between the base material layer and the adhesive layer, the resin constituting the base material layer is preferably polyester. The polyester resin is not particularly limited, and examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polycyclohexane terephthalate (PCT), Polycarbonate (PC) etc. are mentioned.

Furthermore, polyethylene terephthalate (PET) is particularly preferred in terms of printability, imparting rigidity to the composite film, ease of availability, and handleability.

In addition, when the base material layer is a resin layer, a preformed resin film may be applied. The resin film that serves as the base material layer may be a film formed from the above resins or the like, and may be unstretched or uniaxially or biaxially stretched. Among them, a biaxially stretched film is preferred.

Furthermore, the resin film that serves as the base layer may be subjected to roughening treatment for roughening the surface. By roughening the surface, an anchor effect with the adjoining adhesive layer occurs, and adhesion can be improved.

When the base material layer is a laminate of two or more layers, it should be provided with other layers in addition to the layer in the case of the single layer described above. Other layers include, for example, a barrier layer for imparting barrier properties, a reinforcing layer for reinforcing strength, or an adhesive layer for bonding between layers. Moreover, two or more layers of the same kind may be provided in the base material layer to be the laminate.

(barrier layer)
The barrier layer constituting the base material layer is a layer for imparting barrier properties to the composite film.

As the barrier layer, for example, ethylene-vinyl alcohol copolymer (EVOH), nylon (NY), polyvinylidene chloride (PVDC), or polyacrylonitrile (PAN), which exhibits a function of blocking gases such as oxygen and water vapor, is used. and the like.

Alternatively, for example, it may be an inorganic deposition film layer, a metal foil layer, an organic coating layer, or the like.

Examples of the vapor deposited inorganic film layer that serves as a barrier layer include a vapor deposited silica film, a vapor deposited aluminum film, a vapor deposited alumina film, a vapor deposited silica/alumina film, and the like.

Examples of metal foils that serve as barrier layers include metal foils such as aluminum foil, copper foil, and titanium foil, and alloy foils such as aluminum alloy foil and stainless steel foil.

A barrier coat layer such as a vinylidene chloride coat layer or a polyvinylidene fluoride coat layer may be used as the organic coat layer that serves as a barrier layer.

When an inorganic deposition film layer or an organic coating layer is present as the barrier layer, the thickness of the barrier layer is 100 nm or more, 200 nm or more, 300 nm or more, 500 nm or more, 700 nm or more, or 1 μm or more. From the viewpoint of ensuring barrier properties, the thickness is preferably 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less, from the viewpoint of improving handleability when the composite film is used as a packaging material or the like.

When metal foil is used as the barrier layer, the thickness of the barrier layer is preferably 5 μm or more, 7 μm or more, 10 μm or more, or 15 μm or more from the viewpoint of ensuring strength and barrier properties. In addition, it is preferably 100 μm or less, 80 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, or 35 μm or less from the viewpoint of improving handleability when the composite film is used as a packaging material or the like.

(reinforcing layer)
The reinforcing layer constituting the base material layer is a layer for reinforcing the strength of the composite film. Examples of materials for the reinforcing layer include paper such as coated paper and art paper, synthetic paper, and nonwoven fabric. When the paper or the like serving as the reinforcing layer faces the outside of the base material layer, the surface thereof may be printed by gravure printing, flexographic printing, or the like.

(adhesion layer)
The adhesive layer that constitutes the base material layer is a layer that exists between layers and bonds the layers together. Examples of the adhesive layer include layers made of ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), and ionomer.

The adhesive layer may also be a layer made of an adhesive. For example, it may be dry lamination adhesives, hot melt adhesives, water-soluble adhesives, emulsion adhesives, non-solvent lamination adhesives, and thermoplastic resins for extrusion lamination.

<Adhesive layer>
The adhesive layer is an essential constituent layer in the composite film of the present invention, and is arranged between the adjacent base material layer and heat seal layer to adhere them to each other.

In the composite film of the present invention, the heat-sealable layer is heat-sealed with the container body or the like to form a resealable package, and when the package is opened, the adhesive layer and the base layer adjacent to the adhesive layer delamination can occur between the

In the composite film of the present invention, the adhesive layer contains a thermoplastic elastomer and a rosin ester as essential constituents. Since the adhesive layer contains a thermoplastic elastomer and a rosin ester, the composite film of the present invention can be heat-sealed with the heat-seal layer to form a resealable package, and the package can be opened. Occasionally, delamination can occur between the adhesive layer and the substrate layer, and good resealability can be exhibited.

In addition, even when the package is opened in a low-temperature environment, the inner edge can be easily cut, and the film consisting of the adhesive layer and the heat seal layer can be suppressed from remaining in the resealing part.

The adhesive layer can be produced, for example, by preparing a composition containing a thermoplastic elastomer, a rosin ester, and a solvent, and coating it on the surface of the layer to be laminated. A solvent capable of dissolving both the thermoplastic elastomer and the rosin ester includes, for example, ethyl acetate. Examples of coating means include gravure printing, offset printing, flexographic printing, silk printing, and coating using a dry laminator.

The thickness of the adhesive layer is preferably 5 μm or less. If it is 5 μm or less, the heat-seal layer is heat-sealed to form a resealable package, and when the package is opened, the delamination between the adhesive layer and the base layer becomes easier. It can be carried out.

The thickness of the adhesive layer may be 4 μm or less, or 3 μm or less, and preferably 1 μm or more, 1.5 μm or more, or 2 μm or more from the viewpoint of obtaining sufficient resealability.

In addition, the presence of the adhesive layer in an amount of 4.0 g/m ² or less is preferable from the viewpoint of achieving good delamination between the adhesive layer and the base material layer and realizing good resealability. preferable. The amount of adhesive layer may be 3.8 g/m ² or less, or 3.5 g/m ² or less, 0.1 g/m ² or more, 0.3 g/m ² or more, or 0.5 g/m 2 or more. It may be ² or more.

(thermoplastic elastomer)
The thermoplastic elastomer constituting the adhesive layer of the composite film of the present invention is a material that can be fluidized and molded at high temperatures and that exhibits rubber elasticity at room temperature. The thermoplastic elastomer that can be applied to the present invention is not particularly limited, but examples thereof include olefinic thermoplastic elastomers and styrene thermoplastic elastomers.

Examples of olefinic thermoplastic elastomers include ethylene-propylene copolymers (EPM), ethylene-butene copolymers (EBM), ethylene-octene copolymers, ethylene-propylene-butene copolymers, propylene-butene copolymers, polymers, ethylene-propylene-diene copolymers (EPDM), and the like.

It is also possible to use a blend type olefinic thermoplastic elastomer in which olefinic rubber (EPM, EPDM, etc.) is dispersed in a matrix of olefinic resin (eg, polypropylene, polyethylene, etc.).

Styrene-based thermoplastic elastomers include, for example, styrene-ethylene/butene copolymer (SEB), styrene-ethylene/propylene copolymer (SEP), styrene-ethylene/butene-styrene copolymer (SEBS), and styrene-ethylene. - Propylene-styrene copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS), styrene-butadiene-butylene-styrene copolymer (partially hydrogenated styrene-butadiene-styrene copolymer; SBBS), partially hydrogenated styrene-isoprene-styrene copolymer, partially hydrogenated styrene-isoprene-butadiene-styrene copolymer, and the like.

The thermoplastic elastomer constituting the adhesive layer of the composite film of the present invention may be used singly or in combination of two or more thermoplastic elastomers.

The thermoplastic elastomer that constitutes the adhesive layer of the present invention may be a styrene-based thermoplastic elastomer because it exhibits rubber elasticity in the normal temperature or high temperature range.

Furthermore, among styrene-based thermoplastic elastomers, styrene-butadiene/butylene-styrene copolymers may be used because of their good compatibility with tackifiers.

The content of the thermoplastic elastomer in the adhesive layer may be 30% by mass or more, 35% by mass or more, 40% by mass or more, or 45% by mass or more with respect to the entire mass of the adhesive layer, and 70% by mass or less, It may be 65% by mass or less, 60% by mass or less, or 55% by mass or less.

(rosin ester)
The rosin ester constituting the adhesive layer of the composite film of the present invention is a compound obtained by esterifying rosin.

The type of resin acid (various isomers), which is the main component of the rosin to be esterified, is not particularly limited. may also be a mixture thereof.

Conjugated resin acids include, for example, abietic acid, neoabietic acid, and parastric acid. Examples of non-conjugated resin acids include pimaric acid, isopimaric acid, dehydroabietic acid and the like.

The form of the rosin ester is not particularly limited, and examples include esters of rosin or polymerized rosin with polyhydric alcohols, hydrogenated rosin esters, and maleic acid-modified rosins obtained by adding maleic acid to esters. It may be an ester or the like.

Commercially available "rosin esters" can be used, and examples thereof include Harima Chemicals Co., Ltd.'s Haritak series, Arakawa Chemical Industries, Ltd.'s Ertergam series, Pencel (registered trademark) series, and the like. .

The content of the rosin ester in the adhesive layer may be 30% by mass or more, 35% by mass or more, 40% by mass or more, or 45% by mass or more, 70% by mass or less, 65% by mass or more, relative to the total mass of the adhesive layer. % by mass or less, 60% by mass or less, or 55% by mass or less.

The adhesion of the adhesive layer can be improved by including a sufficient amount of rosin ester in the adhesive layer, and the strength of the adhesive layer can be maintained by preventing the amount of rosin ester from becoming excessive. can do.

The rosin ester that constitutes the adhesive layer of the composite film of the present invention may be used singly or in combination of two or more rosin esters.

(other ingredients)
The adhesive layer of the composite film of the present invention, in addition to the thermoplastic elastomer and rosin ester, which are essential components, may optionally contain other resins and additives for imparting functionality and the like. good.

<Heat seal layer>
The heat seal layer is an essential constituent layer in the composite film of the present invention. The heat-sealing layer is a layer used for heat-sealing when the composite film of the present invention is used to form a package or the like. Therefore, the heat seal layer is arranged so as to be the innermost layer of the composite film.

The heat seal layer of the composite film of the present invention contains polyethylene resin. A polyethylene resin can be thermally bonded, and can impart sufficient sealing strength to the formed structure.

Examples of the polyethylene resin contained in the heat seal layer include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

When it is desired to impart content resistance to the composite film of the present invention, it is preferable to use, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or the like.

The heat seal layer may be formed using a preformed film, or may be formed by melting and extruding a material for forming the heat seal layer on the surface of the target laminate, and cooling and solidifying it. may

It should be noted that the polyethylene resin constituting the heat seal layer may be blended not only with one type but also with two or more types. In addition, the heat seal layer may contain, if necessary, resins other than polyethylene resins, additives, and the like.

The heat seal layer constituting the composite film of the present invention may be a polyethylene resin layer having a density of 0.920-0.958 g/cm ³ . According to such a configuration, it is possible to provide sufficient film-forming properties and heat-sealing properties, and to facilitate edge cutting.

In addition, in the present invention, the density may be a value measured according to JIS K7112-1999.

The density of the heat seal layer is 0.923 g/cm ³ or more, 0.925 g/cm ³ or more, 0.927 g/cm ³ or more, 0.930 g/cm ³ or more, 0.933 g/cm ³ or more, or 0.923 g/cm 3 or more. It may be 935 g/cm ³ or more, and may be 0.952 g/cm ³ or less, 0.950 g/cm ³ or less, or 0.948 g/cm ³ or less.

In the composite film of the present invention, the heat seal layer preferably contains only high density polyethylene or high density polyethylene and low density polyethylene. If the layer is made of a mixed resin containing only high-density polyethylene or high-density polyethylene and low-density polyethylene, the heat-sealing layer can have better film formability and edge tearability.

Whether the heat seal layer is a layer made of a mixed resin containing high-density polyethylene and low-density polyethylene can be determined, for example, using a differential scanning calorimeter (DSC) using a curve measured for the heat seal layer and the mixed resin This can be confirmed by comparing the curves measured for each polyethylene constituting the layer.

When the polyethylene resin layer contained in the heat seal layer is a mixed resin layer containing high-density polyethylene and low-density polyethylene, the density of each component is weighted by the content of each component. weighted average.

The thickness of the heat seal layer is not particularly limited, and may be, for example, 1 μm or more, 2 μm or more, or 3 μm or more. This thickness is preferably less than 10 μm, 7 μm or less, 6 μm or less, or 5 μm or less from the viewpoint of facilitating edge cutting.

(high density polyethylene)
In this specification, high-density polyethylene includes 80 mol% or more, 90 mol% or more, 95 mol% or more, or 98 mol% or more of repeating units of methylene groups, including the branch difference when it has a branched chain, or substantially A polyethylene with a density of 0.942 g/cm ³ or more in which all repeating units are methylene groups.

In particular, 0.942 g/cm ³ or more, 0.945 g/cm ³ or more, 0.948 g/cm ³ or more, 0.950 g/cm ³ or more, 0.952 g/cm ³ or more, or 0.955 g/cm ³ or more It has a density of , substantially does not have a long-chain branched structure, and is obtained by radically polymerizing ethylene by a low-pressure method.

The density of the high-density polyethylene is 0.970 g/cm ³ or less, 0.967 g/cm ³ or less, 0.965 g/cm ³ or less, 0.962 g/cm ³ or less, or 0.960 g/cm ³ or less. good.

The thermal properties of the preferred high-density polyethylene are not particularly limited, but for example, the melt mass flow rate is JIS K6922-1 and -2 and When measured according to JIS K7210-1, it is preferably 0.1 g/10 min or more, 0.5 g/10 min or more, 1.0 g or more, 3.0 g/10 min or more, or 5.0 g/10 min or more. , 100 g/10 min or less, 50 g/10 min or less, 30 g/10 min or less, or 20 g/10 min or less.

The content of high density polyethylene in the heat seal layer is preferably 50 to 100% by mass with respect to the total mass of the heat seal layer.

Furthermore, the content of high-density polyethylene may be 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more with respect to the total mass of the heat seal layer. , 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less.

(low density polyethylene)
As used herein, low-density polyethylene (LDPE) includes 80 mol% or more, 90 mol% or more, 95 mol% or more, or 98 mol% or more of methylene group repeating units, including branched chains, or substantially all is a polyethylene with a density of less than 0.930 g/cm ³ , in which the repeating unit of is a methylene group.

The density of the low density polyethylene may be 0.925 g/cm ³ or less, or 0.923 g/cm ³ or less, 0.870 g/cm ³ or more, 0.875 g/cm ³ or more, 0.880 g/cm 3 or more. ³ or more, 0.900 g/cm ³ or more, 0.910 g/cm ³ or more, or 0.915 g/cm ³ or more.

The low-density polyethylene may be a so-called linear low-density polyethylene (LLDPE), or may have a long-chain or short-chain branched structure. The short-chain branched structure may be α-olefins having 4 to 18, 4 to 10, or 4 to 8 carbon atoms, such as 1-butene, 1-hexene, 4-methylpentene-1, 1-octene, etc. It may be a branched structure derived from

The thermal properties of the preferred low-density polyethylene are not particularly limited. When measured according to JIS K7210-1, it is preferably 0.1 g/10 min or more, 0.5 g/10 min or more, 1.0 g or more, 3.0 g/10 min or more, or 5.0 g/10 min or more. , 100 g/10 min or less, 50 g/10 min or less, 30 g/10 min or less, or 20 g/10 min or less.

The content of low-density polyethylene in the heat seal layer is not particularly limited, but is, for example, 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass with respect to the total mass of the heat seal layer. % or more, or 25 mass % or more, and may be 50 mass % or less, 45 mass % or less, 40 mass % or less, 35 mass % or less, or 30 mass % or less.

<Other layers>
The composite film of the present invention comprises a substrate layer, an adhesive layer, and a heat seal layer in this order, and if the substrate layer and the heat seal layer are adhered to each other by the adhesive layer, other Layers may be included.

<<Manufacturing method of composite film>>
The method for producing the composite film of the present invention is not particularly limited, and known methods can be applied. Examples include dry lamination, hot melt lamination, extrusion lamination, sandwich lamination, and the like.

《Uses of composite films》
The structure formed using the composite film of the present invention is not particularly limited.

<Packaging bag>
A structure formed using the composite film of the present invention may be a packaging bag. For example, by heat-sealing the heat-seal layers of the composite film of the present invention to each other, a three-side seal bag, a four-side seal bag, a gusset packaging bag, a pillow packaging bag, or the like can be formed.

<Lid material>
A structure formed using the composite film of the present invention may be a lid material. A lid material formed from the composite film of the present invention can be, for example, a lid material for sealing the upper end opening of the container body. Since the lid material formed from the composite film of the present invention is a resealable lid material, a resealable packaging container with a lid can be formed.

The lid material formed from the composite film of the present invention is, for example, heat-sealed to the upper end opening of the container body to form a lidded packaging container. Due to delamination between the adhesive layer and the base material layer and inner edge breakage, the adhesive layer is exposed in a resealable state with the base material layer. Then, when the packaging container is resealed, it is resealed between the adhesive layer and the base material layer.

<Container with lid containing contents>
A structure formed using the composite film of the present invention may be a lidded container containing contents.

Specifically, it comprises a container body having a storage portion and a flange portion, contents housed in the container body, and a lid material formed from the composite film of the present invention, wherein the heat seal layer of the lid material is The lidded container containing the contents is heat-sealed to the flange portion of the container body to form a resealable joint.

In a lidded container containing contents formed using the lid material formed from the composite film of the present invention, the joint where the lid material is heat-sealed is resealable.

The mechanism for opening and resealing the lidded container is as described above.

[Construction of lidded container containing contents]
A lidded container containing contents includes a container body, contents, and a lid made of the composite film of the present invention.
(container body)
A container body for forming a lidded container containing contents has a storage portion and a flange portion.

The material of the container body is not particularly limited as long as the heat-sealable layer of the lid material formed from the composite film of the present invention can be heat-sealed. For example, a paper container whose surface is coated with a resin, or a resin container may be used.

{storage part}
The storage part is a part in which contents are stored. The shape of this portion is not particularly limited, and may be, for example, a substantially truncated cone shape, a polygonal truncated pyramid shape, a rectangular parallelepiped shape, a cubic shape, or the like.

{Flange}
The flange portion is a peripheral portion of the upper end opening of the storage portion of the container body. The shape is not particularly limited, and may be, for example, a brim shape. Moreover, the shape of the outer periphery of the flange portion can be appropriately selected according to the shape of the lid member.

Among them, it is preferable that at least the flange portion of the container is coated with a polyethylene-based resin. Furthermore, it is preferable that the container body is a paper cup and the flange portion is coated with a polyethylene-based resin.

If the container body is a paper cup having a flange portion coated with a polyethylene resin, the pressure-sensitive adhesive layer and the heat-sealing layer of the lid material formed from the composite film of the present invention can obtain a certain degree of sealing strength. Smooth delamination can be achieved at the interface with the base material layer.

(Contents)
The contents are stored in the storage unit. The contents are not particularly limited, but examples thereof include heated foods such as soups, instant noodles, chilled foods and frozen foods, and non-heated foods such as snacks and gummy candies.

The present invention will be specifically described by way of examples, comparative examples, etc., but the present invention is not limited to these.

<Material>
In the examples and comparative examples, the following materials were prepared for the layers.

(1) Paper layer Paper (NM Art, Nippon Paper Industries Co., Ltd., basis weight: 79.1 g/m ² )

(2) Aluminum layer Aluminum foil (1N30, manufactured by UACJ Corporation, thickness: 7 μm)

(3) Resin layer PET film (PETB, Unitika Ltd., thickness: 12 μm)

(4) Adhesive layer Thermoplastic elastomer Styrene-butadiene-butylene-styrene copolymer: SBBS (N515, Asahi Kasei Co., Ltd.)
Rosin ester (Ester Gum AA-G, Arakawa Chemical Industries, Ltd.)
Polyterpene (Sylvares® TRB115, Kraton)

(5) Heat seal layer LDPE (Suntech (registered trademark) LD L2340, Asahi Kasei Corporation, density: 0.923 g/cm ³ )
・HDPE (Nipolon Hard (registered trademark) LW13D, Tosoh Corporation, density: 0.956 g/cm ³ )
・HDPE (Novatec (registered trademark) HD HJ490, Nippon Polyethylene Co., Ltd., density: 0.958 g/cm ³ )

<<Examples 1 and 2>>
<Production of composite film>
Using the materials shown in Table 1, a composite film having a laminated structure of (paper layer//aluminum layer//resin layer/adhesive layer/heat seal layer) was produced by the method shown below. In the produced composite film, the substrate layer is a laminate composed of three layers, that is, the substrate layer is a laminate composed of paper layer//aluminum layer//resin layer. The composite film has a form in which a substrate layer, an adhesive layer, and a heat seal layer are laminated in this order. In addition, the part laminated by dry lamination is shown by "//". The composition (% by mass) of the adhesive layer indicates the solid content of each component with respect to the entire adhesive layer.

1. An aluminum foil serving as an aluminum layer and a polyester film serving as a resin layer were laminated by dry lamination to prepare a laminate of (resin layer//PET film). As the dry lamination adhesive, a two-component curing type dry lamination adhesive (Takelac A525/Takenate A52, Mitsui Chemicals, Inc.) was used.

2. A sheet of paper to be a paper layer was attached to the aluminum layer side by dry lamination to prepare a laminate of (paper//aluminum layer//PET film). As the dry lamination adhesive, a two-component curing type dry lamination adhesive (Takelac A525/Takenate A52, Mitsui Chemicals, Inc.) was used.

3. On the PET film side, a mixed resin of a thermoplastic elastomer and a rosin ester, a thermoplastic elastomer alone, or a mixed resin of a thermoplastic elastomer and a polyterpene, which serves as an adhesive layer, was applied at a dry weight of 3 g/m ² (thickness: 3 μm). A laminate of (paper//aluminum layer//resin layer/adhesive layer) was produced. The types and mixing ratios of the adhesive layer are as shown in Table 1.

4. On the adhesive layer, a polyethylene mixed resin or polyethylene resin to be the heat seal layer is extrusion-laminated to a thickness of 5 μm to form (paper//aluminum layer//resin layer/adhesive layer/heat seal layer). A composite film having the structure was obtained. Table 1 shows the type of polyethylene resin used in the heat seal layer and the proportion of the resin in the heat seal layer.

<Production of lid material>
The obtained composite film was cut into a size of φ101 mm with a tab to prepare a lid material.

<Production of lidded container>
The resulting lid material is heat-sealed to a PE-coated paper cup (flange width: 3 mm, opening inner diameter: 90 mm) using a heated heat-seal bar under conditions of a heat-seal width of 3 mm, a pressure of 65 MPa, and a time of 0.7 seconds. Then, a lidded container was produced.

<<Reference example 1>>
As shown in Table 1, a composite film was produced in the same manner as in Example 2, except that a mixed resin of styrene-butadiene-butylene-styrene copolymer (SBBS) and polyterpene was used as the material for forming the adhesive layer. A lidded container was produced using the composite film thus produced.

<<Comparative example 1>>
An adhesive layer was formed by coating only a thermoplastic elastomer in a dry weight of 4 g/m ² (thickness: 4 µm) without using a rosin ester, and the composition of the heat seal layer was as shown in Table 1. A composite film was produced in the same manner as in Example 1, except that the thickness was changed to 10 μm, and a lidded container was produced using the obtained composite film.

<<Comparative Example 2>>
A composite film was produced and obtained in the same manner as in Comparative Example 1, except that only the thermoplastic elastomer was applied twice to form an adhesive layer having a dry weight of 10 g/m ² (thickness: 10 μm). A lidded container was produced using the composite film.

"evaluation"

(Resealing test after hot water supply)
About ⅓ of the containers with lids produced in Examples 1 and 2, Reference Example 1, and Comparative Examples 1 and 2 were opened, hot water at 90° C. was poured, and the containers were resealed by finger pressure. Five minutes after resealing, the lid was evaluated for sealing. The results are shown in Table 1.
○: It was sealed for 5 minutes ×: The lid opened within 5 minutes

(Opening test in low temperature environment)
The containers with lids produced in Examples 1 and 2, Reference Example 1, and Comparative Examples 1 and 2 were subjected to opening tests at 0°C, -10°C, and -20°C, and evaluated according to the following criteria. gone.
○: Inner edge cut without film residue △: No film residue, but stringiness occurred ×: Film residue occurred

REFERENCE SIGNS LIST 1 paper layer 2 aluminum layer 3 resin layer 4 adhesive layer 5 heat seal layer 10 composite film 100 lid material 102 base material layer 104 adhesive layer 106 heat seal layer 104a resealing portion 110 tab 120a first breaking portion 120b second breaking portion Part 200 Container body 202 Flange part 202a Joining part 250 Contents 300 Lid container containing contents

Claims

Including a base material layer, an adhesive layer, and a heat seal layer in this order,
The base material layer and the heat seal layer are adhered to each other by the adhesive layer,
The adhesive layer contains a thermoplastic elastomer and a rosin ester, and the heat seal layer contains a polyethylene resin,
composite film.
The composite film according to claim 1, wherein the thermoplastic elastomer is a styrenic thermoplastic elastomer.
The composite film according to claim 1 or 2, wherein the thermoplastic elastomer is a styrene-butadiene/butylene-styrene copolymer.
The composite film according to any one of claims 1 to 3, wherein the adhesive layer has a thickness of 5 μm or less.
The composite film according to any one of claims 1 to 4, wherein the heat seal layer is a polyethylene resin layer with a density of 0.920-0.958 g/ cm3 .
The composite film according to claim 5, wherein the polyethylene resin layer contains only high-density polyethylene or high-density polyethylene and low-density polyethylene.
The composite film according to claim 6, wherein the content of the high density polyethylene is 50 to 90% by mass with respect to the total mass of the heat seal layer.
A lid material molded from the composite film according to any one of claims 1 to 7.
The lid material according to claim 8, which is for resealing.
The lid material according to claim 8 or 9, which does not have a half cut on the heat seal layer side.
a container body having a storage portion and a flange portion;
a content housed in the container body;
A lid material formed from the composite film according to any one of claims 1 to 7;
with
the heat seal layer is heat sealed to the flange to form a resealable joint;
Container with lid containing contents.
The container body is a paper cup,
12. The lidded container containing contents according to claim 11, wherein said flange portion is coated with a polyethylene resin.