JP2002219784A - Laminated materials for paper containers - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To be able to satisfy both good cutting performance when punching a blank from a laminated material for paper containers and low-temperature sealing performance at the time of box making or heat sealing after filling contents. An object of the present invention is to provide a laminated material for a paper container having a sealant layer. In a laminate in which a paper layer 2 is used as a base material and a gas barrier layer 4, a plastic film layer 5, and a sealant layer 10 are laminated on the paper layer 2, the sealant layer 10 is formed on the low-density polyethylene resin layer 7 by a thickness of 25 μm. It is characterized by being formed by laminating the following linear low-density polyethylene resin layers 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated material for a paper container filled with contents such as alcoholic beverages, beverages, seasonings and oils.

[0002]

2. Description of the Related Art As a laminated material for a paper container, a multilayer structure in which a thermoplastic resin layer, a paper layer, an adhesive resin layer, a gas barrier layer, a plastic film layer, an adhesive layer, and a sealant layer are laminated in order from the surface. Conventionally, an aluminum foil or a vapor-deposited thin film of aluminum has been used as the gas barrier layer having the multilayer structure, and a low-density polyethylene resin has been mainly used as the sealant layer. In recent years, from the viewpoint of recycling for building a recycling-oriented society, vapor-deposited thin films of inorganic oxides such as aluminum oxide and silicon oxide have been used as gas barrier layers instead of aluminum foil. With the speeding up of the material filling machine, the innermost surface of the sealant layer of the laminated material has come to use a thermoplastic resin having a lower temperature sealing property, mainly a linear low density polyethylene resin. In order to make a paper container, first, a blank obtained by punching the laminated material for the paper container to a specified size as it is or after pasting is loaded into a filling and packaging system, and the box making and filling of contents are performed on the system. It is common to seal after implementation.

[0003]

As a method of punching the laminated material for paper containers into a specified size to form a blank, there are generally a method of punching with a flat pressure type and a method of punching with a rotary type. The rotary type is suitable for this. There are also two types of rotary type. The push-cut type can cut all surfaces in the thickness direction of the laminated material, so it can cut reliably, but the contact surface between the punching blade and the laminated material etc. increases, so the contact friction is large and the efficiency is high. Falls. on the other hand,
The clearance method is widely used because it has fewer contact surfaces, so there is less contact wear of the extraction blade, the durability of the extraction blade is good, and there is no connection, so the finish is beautiful.

FIG. 5 is an explanatory view showing a method of punching a blank from a laminated material for a paper container by a rotary clearance method. The blank 210 is formed by punching the laminated material 200 for a paper container with a punching roller 310 having an upper punching blade 311 and a lower anvil roller 320. At this time, as shown in FIG. 5, in order to provide a clearance of about 10 μm between the cutting edge of the extraction blade 311 of the extraction roller 310 and the surface of the anvil roller 320, the conventional paper container laminated material 200 shown in FIG. In this case, as shown in FIG. 6A, a part of the innermost linear low-density polyethylene resin layer 9 of the sealant layer 10 is 9
As shown in FIG. 6A, the remaining portion 9a is not cut at a thickness of about several μm and remains. Even if the remaining portion 9a is torn off and cut later, as shown in 9b of FIG. It became insufficient, and it was easy to cause troubles such as leftovers and tears.

The conventional laminated material for paper containers has good cutting properties when punching a blank when the innermost surface of the sealant layer 10 is made of a low-density polyethylene resin, but lacks low-temperature sealing properties, and the innermost surface is not straight. In the case of a chain low-density polyethylene resin, low-temperature sealing properties are good, but there is no laminated material for paper containers that satisfies both cutting properties and low-temperature sealing properties, such as poor cutting due to high strength of the resin itself.

Accordingly, an object of the present invention is to satisfy both good cutting performance when punching a blank from a laminated material for a paper container and low-temperature sealing performance at the time of box making or heat sealing after filling contents. An object of the present invention is to provide a laminated material for a paper container having a sealant layer that can be formed.

[0007]

The invention according to claim 1 of the present invention is directed to a laminate in which a paper layer is used as a base material and a gas barrier layer, a plastic film layer, and a sealant layer are laminated on the paper layer. A laminated material for a paper container, comprising a laminated structure of a linear low-density polyethylene resin layer having a thickness of 25 μm or less on a high-density polyethylene resin layer.

Next, according to a second aspect of the present invention, in the first aspect of the present invention, the low density polyethylene resin layer of the sealant layer and the linear low density polyethylene resin layer are laminated by a co-extrusion method. A laminated material for paper containers.

[0009]

According to the present invention, since the innermost surface of the sealant layer of the laminated material for a paper container is made of a linear low-density polyethylene resin having a thickness of 25 μm or less, a blank is formed from this laminated material by a rotary clearance method. After punching
It has both cutting properties that can be easily separated at the time of tear-cutting, and low-temperature sealing properties at the time of box making and filling and sealing of contents. Furthermore, since the low-density polyethylene resin layer of the sealant layer and the linear low-density polyethylene resin layer are laminated by a co-extrusion method, the adhesion strength between both layers is strong, and the efficiency at the time of producing a laminated material is also improved. good.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laminated material 100 for a paper container according to the present invention.
1 is shown in FIG. In order from the surface to the inner surface in the thickness direction, a thermoplastic resin layer 1, a paper layer 2, an adhesive resin layer 3,
It has a gas barrier layer 4, a plastic film layer 5, an adhesive layer 6, and a sealant layer 10. The sealant layer 10 has a low-density polyethylene resin layer 7 provided on the plastic film layer 5 side and a thickness of 25 μm. The following linear low-density polyethylene resin layer 8 is laminated.

In the present invention, the sealant layer 10 comprises a low-density polyethylene resin layer 7 and a linear low-density polyethylene resin layer 8 having a thickness of 25 μm or less, which are previously laminated at a high temperature in a die of a co-extrusion laminator. After that, it is necessary that they are laminated on a plastic film 5 by a co-extrusion method which is simultaneously extruded via an adhesive layer 6.

The thickness of the linear low-density polyethylene resin layer 8 on the innermost surface of the sealant layer 10 must be 25 μm or less, preferably in the range of 5 to 25 μm, more preferably in the range of 5 to 20 μm. is there. In the case of laminating a resin layer having a thickness of about 5 μm, it is difficult with a general single extrusion coating method. As described above, the resin layer is laminated with another resin layer in advance in a die of a co-extruder at a high temperature, and the laminated resin is laminated. In the present invention, the layers are laminated by a coextrusion method because the layers need to be extrusion coated at the same time.

In the present invention, the thickness of the linear low-density polyethylene resin layer 8 on the innermost surface of the sealant layer 10 is preferably set to 5 to 20 μm. As shown in FIG. 3 (a), a blank was punched out of the linear low-density polyethylene resin layer 8 leaving an uncut portion 8a having a thickness of about several μm as shown in FIG.
As shown in (b), when the blank 110 is torn off from the laminated material 100, it has good cutting properties that can be easily separated. Furthermore, since the innermost surface is a linear low-density polyethylene resin, it also has low-temperature sealing properties at the time of heat sealing after box making and filling of contents. Furthermore, since the low-density polyethylene resin layer 7 and the linear low-density polyethylene resin layer 8 are laminated by the co-extrusion method, the adhesion strength between the two layers is strong, and the work efficiency in manufacturing the laminated material is good.

The thickness of the sealant layer 10 is generally 4
Those having a size of 0 to 60 μm are often used.

Further, other layer constitutions of the laminated material for a paper container of the present invention will be described.

As the thermoplastic resin layer 1, a polyolefin resin is generally used, but a low-density polyethylene resin is more preferable. The thickness is 10-20μ
m is often used.

The paper layer 2 generally has a basis weight of 350
４５０450 g / m ² paperboard is used.

The adhesive resin layer 3 is made of polyethylene resin, ethylene / vinyl acetate copolymer resin, ethylene / ethyl acrylate copolymer resin, ethylene / acrylic acid copolymer resin, ethylene / methacrylic acid copolymer resin. Or an ionomer resin. The present invention is not particularly limited.

As the gas barrier layer 4, aluminum foil or a thin film of aluminum or an inorganic oxide vapor-deposited such as aluminum oxide, silicon oxide, tin oxide or magnesium oxide having a thickness of 5 to 300 × 10 ⁻³ μm is used. And more preferably a deposited thin film of aluminum oxide or silicon oxide. In addition, as a method of forming an inorganic oxide vapor-deposited thin film, a normal vacuum vapor deposition method is excellent in consideration of productivity.

The plastic film layer 5 includes:
Biaxially oriented polypropylene film having a thickness of 20 to 30 μm, biaxially oriented nylon film having a thickness of 15 to 25 μm,
Although a biaxially stretched polyester film having a thickness of 6 to 12 μm can be used, a biaxially stretched polyester film is more preferable.

As the adhesive layer 6, a two-component curing type polyurethane adhesive is generally used.

The method of laminating each of the other layers is as follows.

The thermoplastic resin layer 1 is laminated on the paper layer 2 by a known melt extrusion coating method. At this time, it is more preferable that the surface of the paper layer 2 is surface-treated by a corona treatment method or the like because the adhesive strength is strong. The paper layer 2 and the gas barrier layer 4 are laminated via a melt-extruded adhesive resin layer 3 by a sand lamination method. The gas barrier layer 4 and the plastic film layer 5 are laminated by a known dry lamination method when the gas barrier layer 4 is an aluminum foil, and laminated by a vapor deposition method when the gas barrier layer 4 is an inorganic oxide thin film or the like.

[0024]

Next, the laminated material for a paper container of the present invention will be described with reference to specific examples, but the present invention is not limited to these examples.

<Example 1> A polyethylene resin having a density of 0.920 g / cm ³ was used as the thermoplastic resin layer 1, a paperboard having a basis weight of 400 g / m ² was used as the paper layer 2, and ethylene / ethyl acrylate was used as the adhesive resin layer 3. The resin is formed into a gas barrier layer 4 and a plastic film layer 5 having a thickness of 40 × 1.
A biaxially stretched polyester film having a thickness of 12 μm on which silicon oxide having a thickness of 0 ⁻³ μm was deposited was prepared. First, the polyethylene resin is extrusion-coated on the paperboard with a thickness of 20 μm by a known method, and an ethylene / ethyl acrylate resin is coated on the opposite side of the paper with an extrusion laminator to a thickness of 30 μm.
m and extruded, and laminated with the deposited surface of the biaxially stretched polyester film on which the silicon oxide was deposited to obtain a laminated sheet. Next, a 50 μm thick sealant layer 10 was formed on the polyester film surface of the laminated sheet.
Low density polyethylene resin (density = 0.920 g / cm
³ ) and a two-layer resin in which a 10 μm-thick linear low-density polyethylene resin (density = 0.910 g / cm ³ ) was previously laminated in a die of a co-extruder, via a urethane-based adhesive layer 6. Then, they were simultaneously co-extruded and laminated by a co-extrusion laminating machine to obtain a laminated material 100 for a paper container of the present invention.

<Example 2> In Example 1, as the sealant layer 10, a low-density polyethylene resin having a thickness of 40 µm (density = 0.920 g / cm ³ ) and a linear low-density polyethylene resin having a thickness of 20 µm (density = 0.910 g / c
m ³ ) in the same manner as in the present invention except that the two-layer resin previously laminated in a die of a co-extrusion machine was simultaneously co-extruded and laminated by a co-extrusion laminator via a polyurethane adhesive layer 6. Was obtained.

Example 3 In Example 1, the low-density polyethylene resin having a thickness of 35 μm (density = 0.920 g / cm ³ ) and the linear low-density polyethylene resin having a thickness of 25 μm (density = 0.910 g / c
m ³ ) in the same manner as in the present invention except that a two-layer resin previously laminated in a die of a co-extrusion machine was simultaneously co-extruded and laminated by a co-extrusion laminator via a polyurethane adhesive layer 6. Was obtained.

Comparative Example 1 In Example 1, as the sealant layer 10, a low-density polyethylene resin having a thickness of 30 μm (density = 0.920 g / cm ³ ) and a linear low-density polyethylene resin having a thickness of 30 μm (density = 0.910 g / c
m ³ ) for comparison in the same manner except that the two-layer resin previously laminated in the die of the co-extrusion machine was simultaneously co-extruded and laminated with a co-extrusion laminating machine via a urethane-based adhesive layer 6. Was obtained.

Comparative Example 2 In Example 1, except that a low-density polyethylene resin (density = 0.920 g / cm ³ ) having a thickness of 60 μm was laminated as the sealant layer 10.
Similarly, a laminated material for a paper container for comparison was obtained.

<Evaluation> Using the laminated material for paper containers prepared in Examples 1 to 3 and Comparative Examples 1 and 2, the cutting property was evaluated by the method shown in FIG. 2 or FIG. The low-temperature sealing properties during box making and heat sealing were evaluated. Table 1 shows the results.

[0031]

[Table 1]

Table 1 shows that the laminated material for a paper container of Example 1 had good cutting properties and low-temperature sealing properties. The laminated materials for paper containers of Examples 2 and 3 had good low-temperature sealing, but were inferior to Example 1 in cutting performance, but are considered to be sufficiently usable. Comparative Example 1 had good cutting properties, but poor low-temperature sealing properties.
Comparative Example 2 had good low-temperature sealing properties, but poor cutting properties.

[0033]

The laminated material for paper containers of the present invention has a low-density polyethylene resin layer on the plastic film side of the sealant layer and a linear low-density polyethylene resin layer of 25 μm or less on the innermost surface of the laminated material. It has good cutting properties that can be easily separated when punching blanks from the laminated material for paper containers by a rotary clearance method and tear-cutting, and at the time of box making and filling and sealing of contents. Since it also has low-temperature sealing properties, it can sufficiently cope with recent high-speed filling machines. In addition, since the low-density polyethylene resin layer and the linear low-density polyethylene resin layer are laminated by a co-extrusion method, not only the adhesion strength between both layers is strong, but also the efficiency in manufacturing the laminated material is good. It has the following characteristics.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a laminated material for a paper container of the present invention.

FIG. 2 is an explanatory view showing a state in which a blank is punched out from a laminated material for a paper container of the present invention by a rotary clearance method.

FIG. 3A is an explanatory view showing a state in which a punching blade of a punching roller cuts a blank when punching a blank from the laminated material for a paper container of the present invention, and FIG. It is explanatory drawing which shows the state torn apart.

FIG. 4 is a side sectional view of a conventional laminated material for paper containers.

FIG. 5 is an explanatory view showing a state in which a blank is punched from a conventional laminated material for paper containers by a rotary clearance method.

FIG. 6 (a) is an explanatory view showing a state in which a punching blade of a punching roller cuts a blank when punching a blank from a conventional laminated material for paper containers, and FIG. 6 (b) tears the blank from the laminated material. FIG. 4 is an explanatory diagram showing a state in which separation is not possible even when the image is separated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermoplastic resin layer 2 ... Paper layer 3 ... Adhesive resin layer 4 ... Gas barrier layer 5 ... Plastic film layer 6 ... Adhesive layer 7 ... Low density polyethylene resin layer 8 ... Linear low density polyethylene resin layer 8a ... Not yet Cut part 9 ... Linear low-density polyethylene resin layer 9a ... Uncut part 9b ... Tear-cut defective part 10 ... Sealant layer 100,200 ... Paper container laminated material 110,210 ... Blank 310 ... Punching roller 311 ... Punching blade 320 ... Anvil roller

Continued on the front page F-term (reference) 3E086 AB01 AD02 BA04 BA13 BA14 BA15 BA40 BB90 CA11 CA12 4F100 AA20 AK01C AK04 AK04J AK06D AK25 AK25J AK41 AK63E AL01 AR00B AR00D AR00E BA05 BA10A BA10E JE12 GB12E12 EDG12E12D

Claims (2)

[Claims] 1. A laminate comprising a paper layer as a base material and a gas barrier layer, a plastic film layer, and a sealant layer laminated on the paper layer, wherein the sealant layer is formed on the low-density polyethylene resin layer by a linear low-density layer having a thickness of 25 μm or less. A laminated material for paper containers, comprising a laminate of a high density polyethylene resin layer. 2. A laminated material for a paper container, wherein the low-density polyethylene resin layer of the sealant layer and the linear low-density polyethylene resin layer are laminated by a co-extrusion method.