JP7724642B2 - Laminated body for tube containers - Google Patents

Description

The present invention relates to a laminate for tube containers.

Tube containers are required to have a moderate amount of strength and be comfortable to use, and because they must also protect the contents from light, heat, etc., they are often constructed from a laminate containing a metal foil (e.g., aluminum foil) with a barrier effect and multiple resin layers.

Tube containers are manufactured by heat-sealing the above-mentioned laminate to form a side seam, forming it into a cylindrical shape, sealing one end of the opening, attaching a shoulder to the open end opposite the sealed end, and then attaching a cap. However, when the raw laminate is formed into a cylindrical shape, the metal foil in the laminate can wrinkle at the side seam, which can detract from its aesthetic appearance.

To address this issue, for example, Patent Document 1 proposes a method of forming a vapor-deposited metal film above the aluminum foil (on the outer surface) to conceal wrinkles in a laminate containing aluminum foil while maintaining its metallic luster.

Japanese Patent Application Publication No. 4-201332

The technology in Patent Document 1 is designed to conceal wrinkles in the aluminum foil that occur when forming the side seam with a vapor-deposited metal film, but does not prevent wrinkles from occurring.

However, in recent years, changes to manufacturing equipment aimed at improving the production efficiency of tube containers have led to problems such as the fine irregularities and wrinkles in the aluminum foil that could be hidden using conventional technology becoming deeper and no longer being able to be completely hidden.

The present invention was made in light of the current situation described above, and its purpose is to provide a laminate for tubular containers that can suppress the occurrence of wrinkles in the aluminum foil layer at the side seam.

After extensive research, the inventors discovered that the above-mentioned problems could be solved by the following means, and thus completed the present invention. Specifically, the present invention is as follows:

<Aspect 1>
base material layer,
a first high MFR polyolefin layer;
a first low MFR polyolefin layer;
an aluminum foil layer;
a second low MFR polyolefin layer, and a second high MFR polyolefin layer;
in that order,
the melt flow rate of the polyolefin resin constituting the first and second low MFR polyolefin layers is 3.0 g/10 min or less, and the melt flow rate of the polyolefin resin constituting the first and second high MFR polyolefin layers is 0.5 g/10 min or more higher than the melt flow rate of the first and second low MFR polyolefin layers;
Laminate for tube containers.
<Aspect 2>
a first adhesive resin layer is disposed between the aluminum foil layer and the first low MFR polyolefin layer; and a first adhesive resin layer is disposed between the aluminum foil layer and the second low MFR polyolefin layer.
2. The laminate of claim 1.
<Aspect 3>
the polyolefins constituting the first and second low MFR polyolefin layers are both polyethylene; and the polyolefins constituting the first and second high MFR polyolefin layers are both polyethylene.
3. The laminate according to claim 1 or 2.
<Aspect 4>
The laminate according to any one of Aspects 1 to 3, wherein the substrate layer has a metal-vapor-deposited resin layer.
Aspect 5
A laminate according to any one of Aspects 1 to 4, wherein the substrate layer has a printed layer.
Aspect 6
Aspect 6. The laminate of any one of aspects 1 to 5, wherein the second high MFR polyolefin layer is an innermost sealant layer.
Aspect 7
Aspect 6. The laminate of any one of aspects 1 to 5, further comprising an additional sealant layer on the side of the second, higher MFR polyolefin layer opposite the second, lower MFR polyolefin layer as an innermost sealant layer.
<Aspect 8>
A tube container having a body made of the laminate according to any one of Aspects 1 to 7.

The laminate for tube containers of the present invention can suppress the occurrence of wrinkles in the aluminum foil layer at the side seam when forming the side seam when making it into a cylindrical body.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the laminate for tubular containers of the present invention. FIG. 2 is a schematic cross-sectional view showing one embodiment of the substrate layer according to the present invention. FIG. 3 is a schematic diagram showing the procedure for evaluating the laminates of the examples and comparative examples.

Embodiments of the present invention are described in detail below. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the present invention. Furthermore, in the description of the drawings, identical elements are designated by the same reference numerals, and redundant explanations will be omitted.

<<Laminate for tube containers>>
The laminate for a tube container of the present invention (hereinafter also simply referred to as "the laminate of the present invention") is
base material layer,
a first high MFR polyolefin layer;
a first low MFR polyolefin layer;
an optional first adhesive resin layer;
an aluminum foil layer;
an optional second adhesive resin layer;
a second low MFR polyolefin layer, and a second high MFR polyolefin layer;
in that order,
the melt flow rate of the polyolefin resin constituting the first and second low MFR polyolefin layers is 3.0 g/10 min or less, and the melt flow rate of the polyolefin resin constituting the first and second high MFR polyolefin layers is 0.5 g/10 min or more higher than the melt flow rate of the first and second low MFR polyolefin layers;
A laminate for a tube container.

For example, Figure 1 is a schematic cross-sectional view showing one embodiment of the laminate for tube containers of the present invention.

The laminate 100 for tubular containers of the present invention shown in Figure 1 comprises, in this order, a substrate layer 10, a first high MFR polyolefin layer 11a, a first low MFR polyolefin layer 12a, a first adhesive resin layer 13a, an aluminum foil layer 14, a second adhesive resin layer 13b, a second low MFR polyolefin layer 12b, and a second high MFR polyolefin layer 11b. The melt flow rate of the polyolefin resin constituting the first and second low MFR polyolefin layers 12a and 12b is 3.0 g/10 min or less, and the melt flow rate of the polyolefin resin constituting the first and second high MFR polyolefin layers 11a and 11b is at least 0.5 g/10 min higher than the melt flow rate of the first and second low MFR polyolefin layers 12a and 12b.

The laminate of the present invention is able to achieve the effects of the present invention by having the unique structure described above.

Specifically, firstly, we believe that the formation of wrinkles in the aluminum foil layer at the side seams can be suppressed precisely because low MFR polyolefin layers are provided on both sides of the aluminum foil layer at the center.

In other words, the first and second low-MFR polyolefin layers, which are relatively close to the aluminum foil layer, contain polyolefin resins with relatively low melt flow rates (MFRs), which prevents excessive flow of the resin near the aluminum foil when the laminate is heat-sealed to form the side seam, thereby preventing wrinkles from forming in the aluminum foil layer at the side seam.

Secondly, the first and second high MFR polyolefin layers, which are relatively far from the aluminum foil layer, have polyolefin resins that have relatively high melt flow rates (MFR), which facilitates heat sealing when heat-sealing the laminate to form the side seam.

Furthermore, thirdly, in the laminate of the present invention, the low MFR polyolefin layer and the high MFR polyolefin layer are arranged on both sides of the aluminum foil layer at the center, which prevents the balance of stress acting on both sides of the aluminum foil layer from becoming unbalanced, thereby preventing wrinkles from occurring in the aluminum foil layer at the side seam.

In the present invention, melt flow rate (MFR) is a value that represents the fluidity of a resin when molten, and can be measured in accordance with JIS K 7210-1:2014.

<Low MFR polyolefin layer>
In the laminate of the present invention, the first and second low MFR polyolefin layers may be composed of polyolefin resins having the same melt flow rate value, or may be composed of polyolefin resins having different melt flow rates. From the viewpoint of reducing the stress applied to the aluminum foil layer during heat sealing and from the viewpoint of ease of production, it is preferable that the first and second low MFR polyolefin layers be composed of polyolefin resins having the same melt flow rate value.

The melt flow rate of the polyolefin resin constituting the first and second low MFR polyolefin layers is 3.0 g/10 min or less, i.e., it may be 3.0 g/10 min or less, 2.8 g/10 min or less, 2.5 g/10 min or less, 2.2 g/10 min or less, or 2.0 g/10 min or less, or it may be 0.5 g/10 min or more, 1.0 g/10 min or more, or 1.5 g/10 min or more.

In the laminate of the present invention, the polyolefin resins constituting the first and second low MFR polyolefin layers may be the same or different, but from the standpoint of ease of production, it is preferable that they are the same. Furthermore, examples of polyolefin resins that can be used include polyethylene-based resins and polypropylene-based resins.

In the present invention, a polyethylene-based resin refers to a resin that contains more than 50 mol%, 60 mol% or more, 70 mol% or more, or 80 mol% or more of ethylene group repeat units in the polymer main chain, and may be selected from the group consisting of, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), derivatives thereof, and mixtures thereof.

In the present invention, a polypropylene-based resin refers to a resin containing more than 50 mol%, 60 mol% or more, 70 mol% or more, or 80 mol% or more of repeating propylene groups in the polymer main chain, and may be selected from the group consisting of, for example, polypropylene (PP) homopolymer, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, acid-modified polypropylene, derivatives thereof, and mixtures thereof.

Among the above, the polyolefin resins constituting the first and second low MFR polyolefin layers are preferably polyethylene-based resins, such as LLDPE resins.

The first and second low MFR polyolefin layers may be formed using a resin supplied in the form of powder or pellets, for example, by a film-forming method such as melt extrusion or casting, or the resin supplied as a film may be used as is.

In the laminate of the present invention, the thicknesses of the first and second low MFR polyolefin layers are not particularly limited and may be set appropriately taking into consideration processability, the mechanical strength of the laminate, and the like. Furthermore, the thicknesses of the first and second low MFR polyolefin layers may be the same or different. More specifically, the thicknesses of the first and second low MFR polyolefin layers may each independently be, for example, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, or 50 μm or more, and may be 100 μm or less, or 80 μm or less.

<High MFR polyolefin layer>
In the present invention, the "high MFR polyolefin layer" refers to a layer made of a resin having a melt flow rate relatively higher than that of the polyolefin resin constituting the above-mentioned "low MFR polyolefin layer". More specifically, the melt flow rate of the polyolefin resin constituting the first and second high MFR polyolefin layers may be at least 0.5 g/10 min higher than the melt flow rate of the first and second low MFR polyolefin layers, and may be, for example, at least 0.5 g/10 min, at least 1.0 g/10 min, at least 1.5 g/10 min, at least 2.0 g/10 min, at least 2.5 g/10 min, at least 3.0 g/10 min, at least 3.5 g/10 min, or at least 4.0 g/10 min higher.

In the laminate of the present invention, the first and second high MFR polyolefin layers may be composed of polyolefin resins having the same melt flow rate value, or may be composed of polyolefin resins having different melt flow rate values. From the standpoint of reducing the stress applied to the aluminum foil layer during sealing and from the standpoint of ease of production, it is preferable that the first and second high MFR polyolefin layers be composed of polyolefin resins having the same melt flow rate value.

Furthermore, in the laminate of the present invention, the first and second high MFR polyolefin layers can be laminated directly to the first and second low MFR polyolefin layers, i.e., without an adhesive layer or the like therebetween.

The melt flow rate of the polyolefin resin constituting the first and second high MFR polyolefin layers may be, for example, 1.0 g/10 min or more, 1.5 g/10 min or more, 2.0 g/10 min or more, 2.5 g/10 min or more, 3.0 g/10 min or more, 3.5 g/10 min or more, 4.0 g/10 min or more, 4.5 g/10 min or more, 5.0 g/10 min or more, 5.0 g/10 min or more, or 6.0 g/10 min or more, and may be 15 g/10 min or less, 10 g/10 min or less, or 8.0 g/10 min or less.

In the laminate of the present invention, the polyolefin resins constituting the first and second high MFR polyolefin layers may be the same or different, but from the standpoint of ease of production, it is preferable that they are the same. Furthermore, the polyolefin resin may be, for example, a polyethylene-based resin or a polypropylene-based resin. The "polyethylene-based resin" and "polypropylene-based resin" may be appropriately selected from those described above in the "low MFR polyolefin layer" section.

As an example, among the above-mentioned polyolefin resins, it is preferable that both of the polyolefin resins constituting the first and second high MFR polyolefin layers are polyethylene-based resins, such as LLDPE resins.

In the laminate of the present invention, the polyolefin resin constituting the first high MFR polyolefin layer is preferably the same type of polyolefin resin as the polyolefin resin constituting the first low MFR polyolefin layer, i.e., for example, both are polyethylene-based resins or both are polypropylene-based resins, in order to integrate the first high MFR polyolefin layer and the first low MFR polyolefin layer after heat sealing. Similarly, in the laminate of the present invention, the polyolefin resin constituting the second high MFR polyolefin layer is preferably the same type of polyolefin resin as the polyolefin resin constituting the second low MFR polyolefin layer.

The first and second high MFR polyolefin layers may be formed using a resin supplied in the form of powder or pellets, for example, by a film-forming method such as melt extrusion or casting, or the resin supplied as a film may be used as is.

Furthermore, when the laminate of the present invention is molded into a tubular container, the second high MFR polyolefin layer can be the innermost layer of the tubular container. In other words, in this case, the second high MFR polyolefin layer can be the innermost sealant layer.

In the present invention, the innermost sealant layer refers to the layer that will form the innermost layer of the tube container when the laminate is molded into a tube container. When manufacturing the tube container, the innermost sealant layer can be fused to other surfaces (for example, the surface layer described below) at the side seam to form a cylindrical body.

When the second high MFR polyolefin layer is the innermost sealant layer, the resin constituting the second high MFR polyolefin layer preferably has good heat sealing properties, such as LDPE, LLDPE, or MDPE.

In the laminate of the present invention, the thicknesses of the first and second high MFR polyolefin layers are not particularly limited and may be appropriately set taking into consideration processability, the mechanical strength of the laminate, etc. Furthermore, the thicknesses of the first and second high MFR polyolefin layers may be the same or different. More specifically, the thicknesses of the first and second high MFR polyolefin layers may each independently be, for example, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, or 50 μm or more, and may be 100 μm or less, or 80 μm or less.

<Adhesive resin layer>
The adhesive resin layer is an optional layer provided particularly for improving the adhesive strength between layers. The laminate of the present invention can have a first adhesive resin layer and a second adhesive resin layer between the aluminum foil layer and the first and second low MFR polyolefin layers, respectively.

In the laminate of the present invention, the first and second adhesive resin layers may be ethylene-methacrylic acid copolymer resin layers or ethylene-acrylic acid copolymer resin layers, and are preferably ethylene-methacrylic acid copolymer resin layers. This is because ethylene-methacrylic acid copolymer resin (EMAA) can be melt-extruded at relatively low temperatures and can also obtain sufficient adhesive strength.

In the laminate of the present invention, the thicknesses of the first and second adhesive resin layers are not particularly limited and may be set appropriately taking into consideration processability, the mechanical strength of the laminate, and the like. Furthermore, the thicknesses of the first and second adhesive resin layers may be the same or different. More specifically, the thicknesses of the first and second adhesive resin layers may each independently be, for example, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, or 50 μm or more, and may be 80 μm or less, or 50 μm or less.

<Aluminum foil layer>
In the laminate of the present invention, the aluminum foil layer can exhibit a barrier effect.

The thickness of the aluminum foil layer is not particularly limited, and may be, for example, 5.0 μm or more, 6.0 μm or more, 7.0 μm or more, 8.0 μm or more, or 9.0 μm or more from the standpoint of exhibiting sufficient barrier properties and expressing a luxurious metallic luster, and may be 30 μm or less, 20 μm or less, 15 μm or less, or 12 μm or less from the standpoint of ease of handling and the appearance of wrinkles in the side seam area.

<Base material layer>
In the laminate of the present invention, the substrate layer is a layer that supports the above-mentioned high MFR polyolefin layer, low MFR polyolefin layer, adhesive resin layer, aluminum foil layer, and other layers. The substrate layer may be a single layer, or from the viewpoint of imparting functionality, it may be a laminate containing multiple layers. Below, layers that can be included in the substrate layer when it is a laminate will be described as examples, but the present invention is not limited thereto.

Figure 2 is a schematic cross-sectional view showing one embodiment of a substrate layer according to the present invention. The substrate layer 10 shown in Figure 2 has a surface layer 1, an intermediate layer 2, a printed layer 3, and a metal-vapor-deposited resin layer 4, in that order. Although not shown, adhesive layers may optionally be provided between these layers. More specifically, for example, adhesive layers may optionally be provided between the surface layer 1 and the intermediate layer 2, and between the printed layer 3 and the metal-vapor-deposited resin layer 4.

(surface)
In the present invention, the substrate layer may have a surface layer. The surface layer of the substrate layer may be made of a resin. Here, the surface layer refers to a layer that constitutes the outermost layer of the tube when the laminate is molded into a tube container.

Examples of resins that may form the surface layer include, but are not limited to, low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), ethylene/vinyl acetate copolymer (EVA), ionomer resin, ethylene/(meth)acrylic acid copolymer, and ethylene/(meth)acrylic acid ester copolymer (e.g., ethylene/ethyl (meth)acrylate copolymer).

Since the surface layer becomes the sealant layer on the back side when manufacturing the tube container, the resin that makes up this surface layer is preferably a resin that has heat-sealing properties, and more preferably a resin that has good heat-sealing properties with the resin that makes up the sealant layer. It is particularly preferable that the resin that makes up the surface layer and the resin that makes up the sealant layer are the same type.

The surface layer may be formed using a resin supplied in the form of powder or pellets, for example, by a film-forming method such as melt extrusion or casting, or the resin supplied as a film may be used as is. However, from the standpoint of processability and surface smoothness, it is preferable to use a resin in film form.

The thickness of the surface layer is not particularly limited and can be set appropriately taking into consideration processability, heat sealability, etc., and may be, for example, 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, or 90 μm or more, and may be 200 μm or less, 150 μm or less, or 100 μm or less.

(middle class)
In the present invention, the substrate layer may have an intermediate layer. The intermediate layer is an optionally provided layer, and may be a single layer or a laminate consisting of multiple layers.

The intermediate layer may be made of a resin. In addition to the resins listed above for the surface layer, polyesters can also be used as resins for the intermediate layer. Examples of polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate.

The thickness of the intermediate layer (or the total thickness if the intermediate layer is multilayered) is not particularly limited and can be set appropriately taking into consideration processability and the mechanical strength of the laminate. For example, it may be 1.0 μm or more, 5.0 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 50 μm or more, or 200 μm or less, 100 μm or less, or 50 μm or less.

(Printing layer)
In the present invention, the substrate layer may have a printed layer. By providing a printed layer, the design of the tube container can be improved by the pattern or the like on the printed layer.

The printed layer can be formed, for example, on any one surface of the intermediate layer described above by a printing method, such as gravure printing.

(Metal-deposited resin layer)
In the present invention, the substrate layer may have a metal-deposited resin layer. By providing the metal-deposited resin layer, the barrier effect of the laminate of the present invention can be improved, and further, the design of the tube container can be improved, and fine irregularities and wrinkles in the aluminum foil layer at the side seam portion, if any, can be concealed.

A metal-vapor-deposited resin layer is a layer in which a metal-vapor-deposited film formed by vacuum vapor deposition of a metal compound is laminated on the surface of a vapor-deposited substrate.

Examples of deposition substrates include, but are not limited to, films made from stretched polyethylene terephthalate resin (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), nylon, polyvinyl alcohol (PVA), etc.

Metal compounds include, but are not limited to, metals such as aluminum, tin, indium, nickel, titanium, and chromium, as well as metal oxides.

The thickness of the metal-vapor-deposited resin layer is not particularly limited and can be set appropriately taking into consideration processability and the barrier properties of the laminate. For example, it may be 1.0 μm or more, 5.0 μm or more, 10 μm or more, or 12 μm or more, or 50 μm or less, 30 μm or less, or 20 μm or less.

Other demographics
The laminate of the present invention may further include other layers in addition to the layers described above. The other layers will be described below as examples, but the present invention is not limited thereto.

(Adhesive layer)
The laminate of the present invention may have an adhesive layer, which is an optional layer that can be present between the above-mentioned layers and can improve the adhesion between the layers.

Examples of materials that can be used to form the adhesive layer include, but are not limited to, dry laminating adhesives, hot melt adhesives, water-soluble adhesives, emulsion adhesives, non-solvent laminating adhesives, and thermoplastic resins for extrusion laminating.

(Innermost sealant layer)
The laminate of the present invention may have an innermost sealant layer in addition to the second high MFR polyolefin layer described above. In particular, to reinforce the function of the second high MFR polyolefin layer as a sealant layer, the laminate of the present invention may further have an additional sealant layer as an innermost sealant layer on the side of the second high MFR polyolefin layer opposite to the second low MFR polyolefin layer.

The innermost sealant layer may be made of a resin. The resin making up the innermost sealant layer preferably has good heat-sealing properties, such as LDPE, LLDPE, or MDPE.

The innermost sealant layer may be formed using a resin supplied in the form of powder or pellets, for example, by an appropriate film-forming method such as melt extrusion or casting, or the resin supplied as a film may be used as is.

The thickness of the innermost sealant layer is not particularly limited and can be set appropriately taking into consideration processability, heat sealing properties, etc., and may be, for example, 40 μm or more, 60 μm or more, or 80 μm or more, or 200 μm or less, 150 μm or less, or 120 μm or less.

<Total thickness of laminate>
The total thickness of the laminate of the present invention is not particularly limited, and may be, for example, 120 μm or more, 150 μm or more, 180 μm or more, 200 μm or more, 250 μm or more, or 300 μm or more, from the viewpoint of handleability and mechanical strength when made into a tube container, and may be 500 μm or less, 450 μm or less, or 400 μm or less.

<<Method for manufacturing laminate for tube container>>
The laminate of the present invention can be produced by a known method, or by a method modified by a person skilled in the art, except for using the above-described layers.

When producing the laminate of the present invention, for example, the unit resin layers constituting each of the above-mentioned layers may be laminated in any order to produce a laminate in which the substrate layer, first high MFR polyolefin layer, first low MFR polyolefin layer, first adhesive resin layer, aluminum foil layer, second adhesive resin layer, second low MFR polyolefin layer, and second high MFR polyolefin layer are laminated in this order. Alternatively, the laminate of the present invention may be produced by preparing each of the above-mentioned layers separately and then laminating them together.

When the resin constituting the unit resin layer is supplied in the form of powder or pellets, the layer can be formed by an appropriate film-forming method, such as melt extrusion or casting. When the resin is supplied as a film, the film can be used as is as the resin layer.

The above-mentioned film formation method can also be used to form a layer made of resin supplied in the form of powder or pellets, etc., on a single-layer film or an already formed multilayer laminate. Sand lamination is advantageous for forming a layer made of resin supplied in the form of powder or pellets, etc., between two layers selected from a single-layer film and an already formed multilayer laminate.

Furthermore, when two layers selected from a single-layer film and an already formed multi-layer laminate are to be bonded together, the dry lamination method is preferred.

When the dry lamination method is used to manufacture the laminate of the present invention, examples of adhesives that can be used include urethane adhesives, polyester adhesives, titanate adhesives, imine adhesives, butadiene adhesives, and olefin adhesives. Of these, two-component curing urethane adhesives are preferred.

《Tube container》
The laminate of the present invention described above can be used to produce a tubular container, which has a body made of the laminate of the present invention.

Specific steps for manufacturing a tube container include, for example, cutting the laminate of the present invention to an appropriate size, sealing the sides to form a cylindrical body, and forming a shoulder and mouth. Then, by attaching an appropriate cap to this tube container and sealing the bottom, it can be used as a tube-shaped airtight container. A step of filling the contents may also be added. The order of the above steps can be changed as desired.

Furthermore, the side and buttocks sealing can be performed using, for example, heat sealing, ultrasonic sealing, or high-frequency continuous oscillation sealing.

Tube containers manufactured from the laminate of the present invention can be filled with, for example, medicines, cosmetics, skin protection agents (e.g., moisturizers, sunscreens, etc.), food, supplements, toothpaste, etc.

The present invention will be explained in detail below using examples and comparative examples, but the present invention is not limited to these.

Example 1
Based on a manufacturing protocol for a general laminate for a tube, a laminate (raw sheet) of Example 1 was produced. Details of the layers constituting the laminate of Example 1 are shown in Table 1.

Layer structure of laminate for tube of Example 1: "LLDPE film/urethane adhesive/PET-printing/urethane adhesive/VMPET/ac agent/LLDPE resin/LLDPE film/EMAA resin/AL/EMAA resin/LLDPE film/LLDPE resin"

The terms used are explained below:
PET: Polyethylene terephthalate VMPET: Aluminum-deposited biaxially oriented polyethylene terephthalate film LLDPE: Linear low-density polyethylene EMAA: Ethylene-methacrylic acid copolymer AL: Aluminum foil AC agent: Anchor coating agent

Examples 2 and 3
In Examples 2 and 3, the laminates (raw sheets) of Examples 2 and 3 were produced in the same manner as in Example 1, except that the thicknesses of the layers constituting the laminate were changed as shown in Table 1.

Comparative Example 1
The laminate structure was changed as shown in the following Table 2 to obtain a laminate of Comparative Example 1. Regarding the manufacturing protocol, a manufacturing protocol for a general laminate for a tube can be referred to.

Comparative Example 2
The laminate structure was changed as shown in the following Table 3 to obtain a laminate of Comparative Example 2. Regarding the production protocol, a production protocol for a general laminate for a tube can be referred to.

Comparative Example 3
The laminate structure was changed as shown in the following Table 4 to obtain a laminate of Comparative Example 3. Regarding the production protocol, a production protocol for a general laminate for a tube can be referred to.

"evaluation"
In order to evaluate the laminates of the examples and comparative examples prepared above, heat sealing and cooling treatments were carried out.

More specifically, as shown in Figure 3, two sheets of each laminate were stacked together and heat-sealed under the conditions shown below. This overlapping portion corresponds to the side seam when the laminate is formed into a cylindrical shape.

(Heat sealing conditions)
Pressure: 0.3 MPa
・Temperature: 130℃
Time: 2 seconds

The heat-sealed laminate was then cooled without pressure at room temperature of 25°C by contacting only the bottom surface of the laminate with metal through which 15°C water was passed.

After this treatment, the overlapping portions of the laminate were visually observed from above, and the occurrence of wrinkles in the aluminum foil layer was evaluated according to the following criteria. The results are shown in Table 5.

(Evaluation criteria)
A: There are no irregularities on the aluminum foil layer;
B: The aluminum foil layer is uneven, but the unevenness is not significant enough to affect the appearance;
C: The aluminum foil layer is uneven, affecting the appearance.

As is clear from Table 5, the laminates of Examples 1 to 3 all achieved results that were clearly superior to those of Comparative Examples 1 to 3. In particular, no irregularities were observed in the laminate of Example 1.

REFERENCE SIGNS LIST 1 surface layer 2 intermediate layer 3 printed layer 4 metallized resin layer 10 substrate layer 11a first high MFR polyolefin layer,
11b second high MFR polyolefin layer;
12a first low MFR polyolefin layer;
12b second low MFR polyolefin layer;
13a first adhesive resin layer,
13b second adhesive resin layer;
14 aluminum foil layer,
100 Laminate for tube container.

Claims (9)

base material layer,
a first high MFR polyolefin layer;
a first low MFR polyolefin layer;
an aluminum foil layer;
a second low MFR polyolefin layer, and a second high MFR polyolefin layer;
in that order,
the melt flow rate of the polyolefin resin constituting the first and second low MFR polyolefin layers is 0.5 g/10 min or more and 3.0 g/10 min or less, and the melt flow rate of the polyolefin resin constituting the first and second high MFR polyolefin layers is 5.0 g/10 min or more and 10 g/10 min or less ;
Laminate for tube containers. The thickness of the first and second high MFR polyolefin layers is 10 μm or more and 100 μm or less, and
The thickness of the first and second low MFR polyolefin layers is 20 μm or more and 100 μm or less.
The laminate according to claim 1 . a first adhesive resin layer is disposed between the aluminum foil layer and the first low MFR polyolefin layer; and a first adhesive resin layer is disposed between the aluminum foil layer and the second low MFR polyolefin layer.
The laminate according to claim 1 or 2 . the polyolefin resins constituting the first and second low MFR polyolefin layers are both polyethylene-based resins, and the polyolefin resins constituting the first and second high MFR polyolefin layers are both polyethylene-based resins.
The laminate according to any one of claims 1 to 3 . The laminate according to any one of claims 1 to 4 , wherein the substrate layer has a metal-vapor-deposited resin layer. The laminate according to any one of claims 1 to 5 , wherein the substrate layer has a printed layer. The laminate of any one of claims 1 to 6 , wherein the second high MFR polyolefin layer is an innermost sealant layer. 7. The laminate of any one of claims 1 to 6 , further comprising an additional sealant layer on the side of the second, higher MFR polyolefin layer opposite the second, lower MFR polyolefin layer as an innermost sealant layer. A tube container having a body made of the laminate according to any one of claims 1 to 8 .