JP7087870B2 - Packaging material - Google Patents

Description

The present invention relates to packaging materials, and more particularly to packaging materials for packaging alcoholic beverages such as sake, shochu and wine, liquid beverages such as coffee, juice and milk, and liquid foods such as soup, soup stock and noodle soup.

Conventionally, as a packaging material used for a packaging container for packaging contents such as alcoholic beverages, liquid beverages and liquid foods, a paper base material layer and a gas blocking property such as oxygen and steam to improve the storage stability of the contents are used. It is widely known that a laminated body in which a barrier layer provided with the above and a heat-sealing resin layer made of a heat-sealing resin are laminated is used. However, a polyethylene resin having excellent sealing properties and sealing properties is generally used on the side of the heat-sealing resin layer in contact with the contents.

However, since polyethylene resin is used on the innermost surface in contact with the contents of the heat-sealing resin layer, some of the components contained in the contents are adsorbed on the polyethylene resin, and especially in the case of ginjo liquor, a trace amount peculiar to ginjo liquor. There is a problem that the aroma component of polyethylene is adsorbed and the flavor of ginjo sake is impaired. On the other hand, the odor of the adhesive layer interposed between the barrier layer and the heat-sealing resin layer permeates through the polyethylene resin layer of the heat-sealing resin layer on the innermost surface and transfers to the contents, and the taste of the contents deteriorates. There is a problem.

A liquid paper container having at least a thermoplastic resin layer on the front surface and at least a gas barrier layer and a sealant layer (also referred to as a heat-sealing resin layer) on the back surface in order to solve such a problem. A configuration using a cyclic olefin resin layer on the surface in contact with the contents of the above has been proposed (see, for example, Patent Document 1). The cyclic olefin resin suppresses the adsorption of a part of the components contained in the content (hereinafter referred to as non-adsorbent) and suppresses the transfer of the odor of the adhesive layer to the content (hereinafter referred to as non-adsorbent). It has the property of being able to (referred to as permeability). Patent Document 1 is a liquid paper container having non-adsorption and non-permeability because a cyclic olefin resin layer is used on the surface in contact with the contents.

Japanese Unexamined Patent Publication No. 2012-86856

However, since the packaging material used for the liquid paper container described in Patent Document 1 uses a cyclic olefin resin on the inner surface of the sealant layer, the sealant layer is compared with the conventional packaging material using a polyethylene resin on the inner surface. When heat-bonding each other, it is necessary to raise the heating temperature, and when the sealant layer is heated, the air contained in the paper base material expands, or the water vaporizes and expands, so that the paper base material layer expands. There is a problem that air bubbles are generated between the barrier layer and the barrier layer (hereinafter referred to as bubbling). In particular, in the case of a liquid paper container, bubbling is more likely to occur because both the inner and outer surfaces of the packaging material are heated at the same time.

Therefore, the present invention has been made to solve the above problem, and the purpose thereof is to suppress the adsorption (non-adsorptive) of the components contained in the content, and the odor of the adhesive layer is transferred to the content. It is an object of the present invention to provide a packaging material which can suppress (non-permeability) and suppress the occurrence of bubbling during heating when the heat-bonded portion of the packaging material is heat-bonded.

In order to achieve the above problems, the present invention according to claim 1 includes, in order, at least a resin composed of a thermoplastic resin layer, a paper base material layer, an adhesive resin layer, a barrier layer, and a cyclic olefin copolymer. A packaging material provided with a heat-bondable resin layer, wherein the paper substrate layer is a paper substrate having a density of 0.780 g / cm ³ or more and 0.850 g / cm ³ or less. Is.

Further, in the present invention according to claim 2, in the packaging material according to claim 1, the heat-sealing resin layer is at least a polyolefin resin layer and a first cyclic olefin copolymer in order from the side of the barrier layer. The second cyclic olefin copolymer resin layer is provided with a resin layer and a second cyclic olefin copolymer resin layer, and the first cyclic olefin copolymer resin layer contains 80% by mass or more of a resin made of the cyclic olefin copolymer and the second cyclic olefin copolymer. The olefin copolymer resin layer is characterized by containing 10% by mass or more and 80% by mass or less of the resin made of the cyclic olefin copolymer.

Further, the present invention according to claim 3 is characterized in that, in the packaging material according to claim 1 or 2, the thickness of the adhesive resin layer is 15 μm or more and 50 μm or less.

Further, in the present invention according to claim 4, in the packaging material according to any one of claims 1 to 3, the barrier layer is a metal foil or a resin film on which an inorganic oxide or a metal is vapor-deposited on one surface. It is characterized in that it is a vapor-deposited film having a thin-film-deposited layer.

Further, in the present invention according to claim 5, in the packaging material according to any one of claims 2 to 4, the polyolefin resin layer provided on the side of the barrier layer of the heat-sealing resin layer is at least. It is characterized by comprising a polyethylene resin layer and a linear low-density polyethylene resin layer.

Since the packaging material of the present invention uses a heat-sealing resin layer made of a cyclic olefin copolymer on the surface in contact with the contents, the adsorption of the components contained in the contents can be suppressed (non-adsorbent). Further, since the odor of the adhesive layer can be suppressed from being transferred to the contents (impermeable), it is possible to prevent the taste of the contents from being impaired. Further, when the heat-bonded portion of the packaging material is heat-bonded, it is possible to suppress the occurrence of bubbling during heating.

It is a perspective view which shows one Embodiment of the packaging container using the packaging material which concerns on this invention. It is a schematic sectional drawing which shows the layer structure of the packaging material which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing which shows the layer structure of the packaging material which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the layer structure of the packaging material which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the state which the liquid paper container which used the packaging material which concerns on this invention is boxed and made into a cylinder shape from the state which the body was pasted and folded before the assembly completion is completed. It is a perspective view which shows the state which was folded before the heating of the top part before the assembly completion of the liquid paper container which used the packaging material which concerns on this invention. It is explanatory drawing explaining the heating part for the top of the apparatus main body provided with the chamber part.

The present invention described above will be described in detail below with reference to drawings and the like.
FIG. 1 is a perspective view showing an embodiment of a packaging container using the packaging material according to the present invention, FIG. 2 is a schematic cross-sectional view showing a layer structure of the packaging material according to the first embodiment of the present invention, and FIG. 3 is a present. Schematic cross-sectional view showing the layer structure of the packaging material according to the second embodiment of the present invention, FIG. 4 is a schematic cross-sectional view showing the layer structure of the packaging material according to the third embodiment of the present invention, and FIG. 5 is the packaging according to the present invention. Assembling of a liquid paper container using a material A perspective view showing a state in which a body is pasted and folded before completion of assembly and a state in which the package is raised into a tubular shape, FIG. 6 shows a liquid paper container using the packaging material according to the present invention. A perspective view showing a state in which the top is folded before heating before the assembly is completed, FIG. 7 is an explanatory view illustrating a heating portion for the top of the main body of the apparatus provided with a chamber portion, and 100, 200, and 300 in the figure are explanatory views. Packaging material, 110 is a thermoplastic resin layer, 120 is a paper substrate layer, 130 is an adhesive resin layer, 140 is a barrier layer, 141 is a resin film, 142 is a vapor deposition layer, 150 is an adhesive layer, and 160 is a heat-sealing resin. The layer, 161 is a polyolefin resin layer, 161a is a polyethylene resin layer, 161b is a linear low-density polyethylene resin layer, 162 is a first cyclic olefin copolymer resin layer, and 163 is a second cyclic olefin copolymer resin layer. 10 is a liquid paper container, 10'is a liquid paper container before assembly is completed, 11 is a body heat fusion part, 12 is a top heat fusion part, 13 is a spout part, 14 is an opening top end part, and 14'is. A folded opening top end, 15 is an opening bottom end, 16 is a hole, 17 is a top, 18 is a bottom, 20 is a chamber portion, 21 is an outer surface heating portion, and 22 is an inner surface heating portion.

[First Embodiment]
FIG. 1 is a perspective view showing an embodiment of a packaging container using the packaging material according to the present invention, and shows an example of a liquid paper container 10.

The liquid paper container 10 is, for example, in a developed state (hereinafter referred to as a blank) obtained by punching a packaging material 100 (see FIG. 2) into a predetermined outer shape with a punching die equipped with a predetermined ruled line and a cutting edge. , The ends of the bent blanks are overlapped with each other along the ruled lines to provide the body heat-sealed portion 11 having a predetermined width, and the body heat-sealed portion 11 is formed into a tubular shape by performing frame sealing, for example, and then the bottom heat-fused portion is melted by a filling machine. A gable top type container formed in a box shape by heat-pressing a landing portion (not shown) and a top heat-sealing portion 12 is shown. The body heat-sealed portion 11, the top heat-sealed portion 12, and the bottom heat-sealed portion are heat-sealed with the heat-sealing resin layer 160 (see FIG. 2), which is the innermost layer of the packaging material 100, facing each other. be. Although the top heat-sealing portion 12 is visible in FIG. 1, the body heat-sealing portion 11 is provided in a strip shape at one corner in the vertical direction in FIG. 1 on the opposite side of the spout portion 13, for example. Since it is not visible, it is shown by a broken line, and the bottom heat fusion part is not shown. The liquid paper container 10 is filled and sealed with alcoholic beverages such as sake and shochu, liquid beverages such as juice, tea, water, coffee and dairy beverages, and liquid foods such as soup (not shown). The top 17 is provided with a spout 13 provided with a spout body and a cap so that the contents and the like can be easily poured during use. Although not shown, the outer surface of the thermoplastic resin layer 110 (see FIG. 2), which is usually on the outside, is printed by a gravure printing method, an offset printing method, a flexographic printing method, or the like.

FIG. 2 is a schematic cross-sectional view showing the layer structure of the packaging material 100 according to the first embodiment of the present invention. The packaging material 100 includes, in order, at least a thermoplastic resin layer 110, a paper base material layer 120, an adhesive resin layer 130, a barrier layer 140, and a heat-sealing resin layer 160 containing a resin composed of a cyclic olefin copolymer. be. Further, the barrier layer 140 and the heat-sealing resin layer 160 are laminated via the adhesive layer 150. The adhesive layer 150 is provided as needed.

As shown in FIG. 2, the heat-sealing resin layer 160 includes at least a polyolefin resin layer 161, a first cyclic olefin copolymer resin layer 162, and a second cyclic olefin copolymer resin layer in order from the barrier layer 140 side. It is equipped with 163. The heat-bondable resin layer 160 may contain a resin made of a cyclic olefin copolymer, and is not limited to the configuration shown in FIG. 2, but is a preferred embodiment.

Next, each layer constituting the packaging material 100 will be described.
For the paper base material layer 120, milk carton base paper, cup base paper, paperboard, etc. having shapeability, bending resistance, rigidity, waist, strength, etc. are used to make the liquid paper container 10 rigid, and the density of the paper is high. It is characterized in that it is 0.780 g / cm ³ or more and 0.850 g / cm ³ or less. By defining the density of the base paper used for the paper base material layer 120, even if the heat-fused resin layer 160 contains a resin made of a cyclic olefin copolymer, as will be described later, when the heat-bonded portion is heat-bonded. , It is possible to suppress the occurrence of bubbling. If the density of the base paper is less than 0.780 g / cm ³ , the rigidity, waist, and strength are insufficient, and a rigid liquid paper container 10 cannot be obtained. If the density of the base paper exceeds 0.850 g / cm ³ , heat fusion is performed. Bubbles generated by the expansion of the air contained in the base paper of the paper base layer generated when the portion is heated, or the vaporization and expansion of water, make it difficult for the bubbles generated to escape to the outside through the paper base layer 120, resulting in bubbling. It is more likely to occur. In addition, a base paper having a basis weight of about 100 to 450 g / m ² is used.

The thermoplastic resin layer 110 formed on the upper surface of the paper base material layer 120 imparts water resistance to the liquid paper container 10 and heat-fuses the thermoplastic resin layer 110 so as to face each other. Is used, mainly low density polyethylene is used. The thermoplastic resin layer 110 is made by laminating low-density polyethylene on the paper substrate layer 120 by a hot melt extrusion method. Since the surface of the thermoplastic resin layer 110 is usually printed, it is preferable to perform a surface treatment such as a corona discharge treatment in order to improve the adhesiveness of the printing ink.

The adhesive resin layer 130 is composed of a resin layer that adheres the paper base material layer 120 and the barrier layer 140 by a method such as an extrusion laminating method or a coextrusion laminating method. Resins used in the extrusion laminating method and the coextrusion laminating method include low density polyethylene, ionomer, ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), and ethylene-methyl acrylate copolymer. Resins such as coalescing (EMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-methyl methacrylate copolymer (EMMA) are used.

The thickness of the adhesive resin layer 130 is preferably 15 μm or more and 50 μm or less. If the thickness is less than 15 μm, the adhesive force between the paper substrate layer 120 and the barrier layer 140 is insufficient, and if the thickness exceeds 50 μm, molding defects occur when the liquid paper container is made into a liquid paper container by the liquid paper container filling and sealing device. It will be easier.

The barrier layer 140 has a gas barrier property, prevents oxygen and water vapor from permeating the packaging material 100 from the outside and invading the inside of the liquid paper container 10, and the contents filled in the liquid paper container 10. It plays a role of preventing, for example, an aroma component possessed by an object from permeating the packaging material 100 and diverging to the outside of the liquid paper container 10. The barrier layer 140 has a vapor deposition layer 142 (see FIG. 3) in which a metal such as aluminum, silicon oxide, aluminum oxide, or the like is vapor-deposited on a resin film 141 (see FIG. 3) such as a polyethylene terephthalate film or a nylon film. A film or a metal foil such as aluminum can be used. The aluminum foil imparts functions such as gas barrier property and light shielding property, and a soft, semi-hard, hard or alloy type aluminum foil having a thickness of 5 to 20 μm is used. When a thin-film film is used as the barrier layer 140, the thin-film layer 142 is laminated so as to be located on the adhesive resin layer 130 side.

The adhesive layer 150 is provided as necessary for adhering the barrier layer 140 and the heat-sealing resin layer 160. As the adhesive layer 150, a urethane-based two-component curable adhesive or an adhesive resin is used, and the adhesive layer 150 is formed by a dry laminating method or an extrusion laminating method. As the adhesive resin, the same resin as the adhesive resin layer 130 can be used.

The heat-bondable resin layer 160 preferably contains a resin made of a cyclic olefin copolymer. Examples of the cyclic olefin copolymer include an ethylene / cyclic olefin copolymer random copolymer, a hydride of a ring-opened copolymer of a cyclic olefin copolymer, and a graft-modified ethylene / cyclic olefin copolymer random copolymer. Examples thereof include a ring-opening copolymer of a cyclic olefin copolymer modified by coalescence and grafting. Specific examples of the resin composed of the cyclic olefin copolymer include TOPAS (registered trademark) manufactured by Polyplastics Co., Ltd., APEL (registered trademark) manufactured by Mitsui Chemicals, Inc., ZEONOR (registered trademark) manufactured by Nippon Zeon Co., Ltd., and ZEONEX. (Registered trademark) and the like.

The heat-bondable resin layer 160 may be a single layer made of a cyclic olefin resin, but a multilayer of two or more layers is preferable. As shown in FIG. 2, the heat-bondable resin layer 160 includes at least a polyolefin resin layer 161, a first cyclic olefin copolymer resin layer 162, and a second cyclic olefin copolymer resin layer in order from the adhesive layer 150 side. 163 is provided. As the polyolefin resin of the polyolefin resin layer 161, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and polypropylene can be used, but polyethylene-based resins are preferable. The first cyclic olefin copolymer resin layer 162 contains 80% by mass or more of a resin made of a cyclic olefin copolymer, and the second cyclic olefin copolymer resin layer 163 contains a resin made of a cyclic olefin copolymer. It is preferably contained in an amount of 10% by mass or more and 80% by mass or less. These three layers of the polyolefin resin layer 161, the first cyclic olefin copolymer resin layer 162, and the second cyclic olefin copolymer resin layer 163 can also be coextruded and used as a coextruded film. The total thickness of the heat-bondable resin layer 160 is about 30 μm or more and 80 μm or less.

The polyolefin resin layer 161 constituting the heat-bondable resin layer 160 is a layer for increasing the lamination strength with the barrier layer 140 or the adhesive layer 150, and is a first cyclic olefin copolymer resin layer 162 and a second cyclic. By containing the cyclic olefin copolymer in the olefin copolymer resin layer 163, the components of the adhesive layer 150 are prevented from migrating to the liquid paper container 10, and the components of the contents are transferred to the heat-sealing resin layer 160. Prevents being adsorbed. Therefore, the quality of the contents can be maintained, and particularly when the contents are liquid, the adsorption of aroma components can be prevented and the taste of the contents can be well maintained. As described above, the cyclic olefin copolymer resin has non-adsorbability and non-permeability. On the other hand, when the body heat-sealed portion 11, the top heat-sealed portion 12, and the bottom heat-sealed portion are heat-sealed, the cyclic olefin copolymer resin needs to have a higher heat-sealing temperature than the low-density polyethylene. be. Therefore, the content of the cyclic olefin copolymer contained in the first cyclic olefin copolymer resin layer 162 is increased to enhance the non-adsorption property and the impermeable property, and the second cyclic olefin copolymer resin layer 163 is used. By making the content of the cyclic olefin copolymer contained in the first cyclic olefin copolymer resin layer 162 smaller than the content of the cyclic olefin copolymer contained in the first cyclic olefin copolymer resin layer 162, the content of the cyclic olefin copolymer is set to be non-adsorbable and non-permeable. , It is possible to suppress the increase in heat fusion temperature and widen the selection range of the temperature for heat crimping. That is, by controlling the content of the cyclic olefin copolymer resin, the non-adsorptive effect of the cyclic olefin copolymer and the property that the heat fusion temperature is higher than that of low-density polyethylene can be controlled. And heat fusion properties can be achieved at the same time.

[Second Embodiment]
FIG. 3 is a schematic cross-sectional view showing the layer structure of the packaging material 200 according to the second embodiment of the present invention. The packaging material 200 of the second embodiment is a vapor-deposited film in which the barrier layer 140 has a thin-film vapor-deposited layer 142 on which an inorganic oxide or a metal is vapor-deposited on one surface of the resin film 141, and the other parts are the same as those of the first embodiment. The same applies, and the same reference numerals are given and the description thereof will be omitted. The vapor-filmed layer 142 of the barrier layer 140 is preferably arranged on the adhesive resin layer 130 side.

[Third Embodiment]
FIG. 4 is a schematic cross-sectional view showing the layer structure of the packaging material 300 according to the third embodiment of the present invention. The packaging material 300 of the third embodiment is the same as that of the first embodiment except that the structure of the heat-sealing resin layer 160 is different, and the same reference numerals are given and the description thereof will be omitted. The heat-bondable resin layer 160 of the packaging material 300 includes at least a polyolefin resin layer 161, a first cyclic olefin copolymer resin layer 162, and a second cyclic olefin copolymer resin layer 163 in this order from the adhesive layer 150 side. The polyolefin resin layer 161 provided on the side of the adhesive layer 150 is composed of two layers, and includes at least a polyethylene resin layer 161a and a linear low-density polyethylene resin layer 161b. The polyethylene resin layer 161a is arranged on the side of the adhesive layer 150, and the linear low-density polyethylene resin layer 161b is arranged on the side of the first cyclic olefin copolymer resin layer 162.

Low-density polyethylene, medium-density polyethylene, and high-density polyethylene are used for the polyethylene resin layer 161a of the polyolefin resin layer 161. Low-density polyethylene is preferable, and the polyethylene resin layer 161 can be well bonded to the adhesive layer 150. The linear low-density polyethylene resin layer 161b arranged on the side of the first cyclic olefin copolymer resin layer 162 adheres well to the first cyclic olefin copolymer resin layer 162. Further, the low-density polyethylene of the polyethylene resin layer 161a adheres well to the linear low-density polyethylene resin layer 161b. Therefore, by forming the polyolefin resin layer 161 into multiple layers in this way, the interlayer adhesion between each layer and the adjacent layer becomes good, and the adhesive strength of the heat-sealing resin layers 160 of the liquid paper container 10 is heat-sealed. Can be high.

Next, in order to deepen the understanding of the state in which bubbling occurs, a state in which the top heat-sealed portion 12 is heat-bonded will be described with reference to FIGS. 5, 6, and 7.

First, the assembly of the liquid paper container 10 will be described. To assemble a liquid paper container 10 as shown in FIG. 1 from a blank (not shown) punched into a predetermined shape by applying a ruled line to the packaging material, a substantially rectangular blank is folded and one end facing the blank is, for example, a frame. The body heat-sealed portion 11 is heat-sealed by a seal and attached to a cylinder, and the body is attached to the cylinder before the assembly is completed to form a folded flat state. This is supplied to a liquid paper container filling and sealing device, and as shown in FIG. 5, a folded flat liquid paper container is unboxed, and a square cylinder provided with an opening top end 14 and an opening bottom end 15 at both ends. The liquid paper container 10'before the assembly is completed is made into a shaped liquid paper container. First, the bottom is folded, heated, and crimped to form the bottom. Then, a gable top mold (gable mold) is formed, then the inner surface is heated, and finally, the top heat-sealed portion 12 of the top forming plate is polymerized and pressure-bonded to form the top of the liquid paper container 10. The assembly is completed. Before filling the contents, the spout portion 13 is attached to a hole portion 16 formed in a circular shape slightly larger than the outer diameter of the spout portion 13, for example, at a predetermined position of the blank.

FIG. 5 is a perspective view showing a state in which the liquid paper container is laid into a cylinder from a state in which the body is pasted and folded before the assembly is completed. The unboxed and cylindrical liquid paper container 10'before the assembly is completed has openings at both ends, and has an opening top end 14 on one side and an opening bottom end 15 on the other side. First, the bottom end portion 15 of the opening is folded with a crease, heated, and crimped to form the bottom portion, and the contents are filled from the top end portion 14 of the opening. Then, as shown in FIG. 6, the top forming plate is folded by a folding rule. Note that the spout portion 13 is omitted in FIG. 6 for the sake of simplicity.

Next, a state in which the inner surface and the outer surface of the top heat-sealing portion 12 of the bent-folded opening top end portion 14'are simultaneously heated will be described with reference to FIG. 7. As shown in FIG. 7, the heating device main body (not shown) includes a chamber portion 20 provided with an outer surface heating portion 21 and an inner surface heating portion 22, and the chamber portion 20 is formed on a bent opening top end portion 14'. It descends and heats so as to cover it, and after heating, it rises and separates from the bent opening top end 14'. Upon heating, the lowered chamber portion 20 covers the bent opening top end 14'of the liquid paper container, and the inner and outer surfaces of the bent opening top 14'are the inner surface heating portion 22 and the outer surface heating portion 21. It becomes a state of being surrounded from the inside and the outside, and the air heated to a predetermined temperature supplied from the hot air supply part in the main body of the apparatus is shown from a large number of hot air injection small holes (not shown) of the outer surface heating part 21 and the inner surface heating part 22. As shown by the thick line arrow on 7, the hot air is blown toward the top heat-sealed portion 12 to be adhered to the bent-folded opening top end portion 14', and the inner surface of the top heat-sealed portion 12 is configured. The heat-bondable resin layer 160 and the thermoplastic resin layer 110 on the outer surface are simultaneously heated and melted. After heating, the main body of the device provided with the chamber portion 20 rises and separates from the bent opening top end portion 14'. Next, the gable top type liquid paper container 10 shown in FIG. 1 is completed by crimping and joining with a top pressurizing device (not shown) to form a top heat fusion portion 12. In order to crimp-bond the top heat-sealed portion 12, high-temperature hot air of usually 300 ° C. or higher is blown to the portion including the top heat-sealed portion 12. At this time, the higher the hot air temperature, the more likely it is that bubbling will occur. Therefore, if the heat-sealing resin layer 160 contains the cyclic olefin copolymer, the heat-sealing temperature must be higher than that of the conventional low-density polyethylene, and measures for preventing the occurrence of bubbling are required.

However, in the packaging materials 100, 200, and 300 of the present invention, the content of the heat-sealing resin layer 160 is such that the paper substrate layer 120 has a density of 0.780 g / cm ³ or more and 0.850 g / cm ³ or less. Even if the side in contact with the object is a cyclic olefin copolymer resin, it is possible to suppress the occurrence of bubbling in the top heat-sealed portion 12. That is, when the top heat-sealing portion 12 is heated, the air bubbles contained in the paper base layer expand, or the water vaporizes and expands, so that the density of the paper base layer 120 becomes high. Since it is defined in the above range, it is considered that the paper base material layer 120 serves as a vent and escapes to the outside. In addition, it is possible to suppress the occurrence of bubbling in the bottom heat-sealed portion as well.

The present invention is not limited to the above-described embodiment, and typical configuration examples are listed below.
(1) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 / adhesive layer 150 / heat-bondable resin layer 160 [polyolefin resin layer 161 / first cyclic olefin copolymer resin Layer 162 / Second Cyclic Olefin Copolymer Resin Layer 163] <First Embodiment>
(2) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 / heat-sealing resin layer 160 [polyolefin resin layer 161 / first cyclic olefin copolymer resin layer 162 / first 2 Cyclic olefin copolymer resin layer 163]
(3) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 / adhesive layer 150 / heat-sealing resin layer 160 [polyethylene resin layer 161 (polyethylene resin layer 161a / linear low) Dense polyethylene resin layer 161b) / 1st cyclic olefin copolymer resin layer 162 / 2nd cyclic olefin copolymer resin layer 163] <3rd embodiment>
(4) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 / heat-sealing resin layer 160 [polyethylene resin layer 161 (polyethylene resin layer 161a / linear low-density polyethylene resin layer) 161b) / 1st cyclic olefin copolymer resin layer 162 / 2nd cyclic olefin copolymer resin layer 163] <3rd embodiment>
(5) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 (vapor deposition layer 142 / resin film 141) / adhesive layer 150 / heat-sealing resin layer 160 [polypolymer resin layer 161 / First cyclic olefin copolymer resin layer 162 / second cyclic olefin copolymer resin layer 163] <Second embodiment>
(6) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 (vapor deposition layer 142 / resin film 141) / heat-sealing resin layer 160 [polyolefin resin layer 161 / first annular Olefin copolymer resin layer 162 / second cyclic olefin copolymer resin layer 163]
(7) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 (vapor deposition layer 142 / resin film 141) / adhesive layer 150 / heat-sealing resin layer 160 [polyethylene resin layer 161 (polyethylene resin layer 161) Polyethylene resin layer 161a / Linear low-density polyethylene resin layer 161b) / First cyclic olefin copolymer resin layer 162 / Second cyclic olefin copolymer resin layer 163]
(8) Thermoplastic resin layer 110 / paper base material layer 120 / adhesive resin layer 130 / barrier layer 140 (deposited layer 142 / resin film 141) / heat-sealing resin layer 160 [polyethylene resin layer 161 (polyethylene resin layer 161a) / Linear low-density polyethylene resin layer 161b) / First cyclic olefin copolymer resin layer 162 / Second cyclic olefin copolymer resin layer 163]

Further, the present invention will be described in detail with reference to examples.

[Example 1]
First, a polyethylene resin layer 161a having a thickness of 17.5 μm, a linear low-density polyethylene resin layer 161b having a thickness of 10 μm, a first cyclic olefin copolymer resin layer 162 having a thickness of 5 μm, and a first layer having a thickness of 7.5 μm. A coextruded film is produced by forming a heat-bondable resin layer 160 containing a resin made of a cyclic olefin copolymer having a total thickness of 40 μm, in which the cyclic olefin copolymer resin layers 163 of 2 are laminated in order, by a multilayer inflation method. did. The following resin or resin composition was used for each layer.
Polyethylene resin layer 161a: Low density polyethylene (MFR 4.0 g / 10 minutes, density 0.923 g / cm ³ )
Linear low density polyethylene resin layer 161b: Linear low density polyethylene (MFR 2.3 g / 10 minutes, density 0.914 g / cm ³ )
First Cyclic Olefin Copolymer Resin Layer 162: Cyclic Olefin Copolymer COC (manufactured by Polyplastics Co., Ltd., TOPAS)
Second cyclic olefin copolymer resin layer 163: Cyclic olefin copolymer COC (manufactured by Polyplastics Co., Ltd., TOPAS) 40% by mass, linear low density polyethylene (MFR 2.0 g / 10 minutes, density 0.904 g / cm) ³ ) 45% by mass, low density polyethylene (MFR 4.0 g / 10 minutes, density 0.923 g / cm ³ ) 5% by mass, anti-blocking agent master batch (manufactured by Sumitomo Chemical Co., Ltd., EMB-21) 10% by mass is sufficient. The resin composition was adjusted by kneading.

Next, a paperboard having a basis weight of 400 g / m ² and a density of 0.828 g / cm ³ was used as the paper substrate layer 120, and aluminum oxide was used as the barrier layer 140 on one side of a biaxially stretched polyethylene terephthalate film (PET) having a thickness of 12 μm. An anchor coating agent (AC) is applied to one surface of the paperboard using an aluminum oxide vapor-deposited PET film (VMPET) having a vapor-deposited layer (VM) of Using EMAA), the AC surface of the paperboard and the VM (deposited layer) of VMPET were laminated by a sandwich laminating method while extruding EMAA to a thickness of 25 μm. Next, an ethylene-methacrylic acid copolymer (EMAA) was used as the resin of the adhesive layer 150, and the polyethylene resin layer 161a surface of the coextruded film produced as the heat-sealing resin layer 160 and the PET surface of VMPET were formed into EMAA. It was laminated by the sandwich laminating method while extruding to a thickness of 25 μm. Next, an anchor coating agent (AC) is applied to the other surface of the paperboard, and low-density polyethylene (LDPE) is used as the thermoplastic resin layer 110 to laminate it to a thickness of 25 μm by an extrusion coating method, and the surface of the LDPE is laminated. A packaging material was produced by subjecting it to corona discharge treatment and printing on the corona discharge-treated surface by a gravure printing method or an offset printing method to provide a printing layer. The composition of the obtained packaging material was <printing layer / LDPE 25 μm / paperboard 400 g / m ² / EMAA 25 μm / VMPET 12 μm / EMAA 25 μm / heat-sealing resin layer 40 μm> as a packaging material for liquid paper containers.

[Example 2]
A packaging material was produced in the same manner as in Example 1 except that a paperboard having a basis weight of 400 g / m ² and a density of 0.783 g / cm ³ was used as the paper substrate layer 120.

[Example 3]
A packaging material was produced in the same manner as in Example 1 except that a paperboard having a basis weight of 410 g / m ² and a density of 0.840 g / cm ³ was used as the paper substrate layer 120.

[Comparative Example 1]
A packaging material was produced in the same manner as in Example 1 except that a paperboard having a basis weight of 400 g / m ² and a density of 0.722 g / cm ³ was used as the paper substrate layer 120.

[Comparative Example 2]
A packaging material was produced in the same manner as in Example 1 except that a paperboard having a basis weight of 400 g / m ² and a density of 0.855 g / cm ³ was used as the paper substrate layer 120.

Using the packaging materials for liquid paper containers obtained in Examples 1 to 3 and Comparative Examples 1 and 2, a gable top type liquid paper container having a capacity of 1.8 liters was produced, and the processing suitability and filling suitability of the packaging material were evaluated. The results are shown in Table 1.

The evaluation method and evaluation criteria are as follows.
[Processing aptitude]
A punching blank was produced from a packaging material using a punching machine equipped with a punching die equipped with a predetermined ruled line and a predetermined blank forming cutting edge. Next, while bending the blank, one of the opposite edges was superposed as the body heat-sealing portion 11 to perform a frame seal, and the blank was pasted with a box making machine to obtain a tubular folded liquid paper container.
[Bubbling state]
The bubbling state of the heat-sealed portion 11 of the body of the liquid paper container that had been pasted and folded into a cylindrical shape was visually inspected. Is bubbling occurring as an evaluation standard? , No bubbling occurred was marked as ○.
[Paste bent state]
The state of pasting of the tubular folded liquid paper container was visually inspected. The evaluation standard is to compare the width dimension of one opening side and the width dimension of the other opening side of the cylindrical folded liquid paper container, and if it is less than 1.0 mm, it is considered good, and if it is 1.0 mm or more, it is pasted. As if there is a bend? And said.

[Filling aptitude]
A gable top type liquid paper container 10 shown in FIG. 1 was manufactured by hoisting and assembling a folded liquid paper container with a paper container filling / sealing device equipped with a tubular carton assembling device or the like.
[Bubbling generation temperature]
The temperature of the chamber portion was changed every 10 ° C. from 290 ° C. to 330 ° C., and the temperature at which bubbling occurred was measured.
The presence or absence of bubbling was confirmed as follows. The liquid paper container 10 shown in FIG. 1 was cut horizontally between the top 17 and the bottom 18 and divided into upper and lower halves to prepare a test sample. The test solution was poured from the cutting port of the test sample with the cutting port of the top 17 and the bottom 18 facing up, and allowed to stand for about 1 hour with the cutting port facing up. Then, it was visually inspected whether or not the test liquid permeated into the paper base material layer 120 of the heat-sealed portion and was colored. What is colored? , The one that was not colored is marked as 〇? The temperature evaluated in 1 was defined as the bubbling generation temperature. As the test solution, a microcheck penetrant (Ichinen Chemicals) was used.
[Formability]
When the packaging material is folded along the ruled line at the top 17 or the bottom 18, the folding misalignment or the folding wrinkles are regarded as molding defects? And said. Good ones with no molding defects were rated as 〇. In addition, although the frequency was low, those in which molding defects such as folding misalignment and wrinkles were observed were marked with Δ.

As shown in Table 1, in Examples 1 to 3, good processing aptitude and filling aptitude were obtained, and in particular, no bubbling was observed in the processing aptitude and filling aptitude, which were good. In Comparative Example 1, the bubbling was good, but the sticking was observed, and the processability was inferior. In terms of filling suitability, the bubbling generation temperature was good at 330 ° C., but molding defects occurred. In Comparative Example 2, bubbling was observed in the processing suitability, and the processing suitability was inferior. Further, in terms of filling suitability, bubbling was observed at 300 ° C., and in terms of moldability, the rigidity of the paperboard was too strong, and molding defects were observed at a frequency of about 10%, which was not sufficient.

10 Liquid paper container 10'Liquid paper container before completion of assembly 11 Body heat fusion part 12 Top heat fusion part 13 Outlet part 14 Open top end 14'Cut-folded opening top end 15 Open bottom end 16 hole Part 17 Top 18 Bottom 20 Chamber part 21 Outer surface heating part 22 Inner surface heating part 100, 200, 300 Packaging material 110 Thermoplastic resin layer 120 Paper base layer 130 Adhesive resin layer 140 Barrier layer 141 Resin film 142 Evaporation layer 150 Adhesive layer 160 Heat-bondable resin layer 161 Polyethylene resin layer 161a Polyethylene resin layer 161b Linear low-density polyethylene resin layer 162 First cyclic olefin copolymer resin layer 163 Second cyclic olefin copolymer resin layer

Claims (5)

A packaging material provided with a heat-sealing resin layer containing at least a thermoplastic resin layer, a paper base material layer, an adhesive resin layer, a barrier layer, and a resin composed of a cyclic olefin copolymer in this order.
A packaging material, wherein the paper base material layer is a paper base material having a density of 0.780 g / cm ³ or more and 0.850 g / cm ³ or less. The heat-sealing resin layer includes at least a polyolefin resin layer, a first cyclic olefin copolymer resin layer, and a second cyclic olefin copolymer resin layer in order from the barrier layer side.
The first cyclic olefin copolymer resin layer contains 80% by mass or more of the resin made of the cyclic olefin copolymer.
The packaging material according to claim 1, wherein the second cyclic olefin copolymer resin layer contains 10% by mass or more and 80% by mass or less of a resin made of the cyclic olefin copolymer. The packaging material according to claim 1 or 2, wherein the thickness of the adhesive resin layer is 15 μm or more and 50 μm or less. The invention according to any one of claims 1 to 3, wherein the barrier layer is a thin-film film having a thin-film film on which an inorganic oxide or a metal is vapor-deposited on one surface of a metal foil or a resin film. Packaging material. Any of claims 2 to 4, wherein the polyolefin resin layer provided on the side of the barrier layer of the heat-sealing resin layer includes at least a polyethylene resin layer and a linear low-density polyethylene resin layer. The packaging material described in Crab.

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