JPH10291279A - Paper container for liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate easily a paper layer from a barrier layer by a method wherein a water-soluble resin layer is provided between the paper layer and the barrier layer. SOLUTION: A paper layer 12 is used as a substrate, and a polyolefin(PO) resin layer 11 of polyethylene(PE) resin or the like is laminated on its surface. A barrier layer 14 constituted by cladding an aluminum foil onto a polyethylene terephthalate film with an adhesive, is laminated on a rear surface of the paper layer 12 via a water-soluble resin layer 13, and further a PO resin layer 15 of PE or the like is laminated on its inner surface to constitute a laminate 1. As the paper layer 12 of the substrate, for example, milk carton base or cup base is used. To the water-soluble resin layer 13, for example, polyethylene oxide or the like is applied by 0.5-10 g/m<2> . By providing the water-soluble resin layer between the paper can be easily separated from the barrier layer only by immersing the paper container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid paper container using a laminate in which a paper layer and a barrier layer can be easily peeled off and recycled as used paper.

[0002]

2. Description of the Related Art Conventionally, liquid paper containers have been used as containers for milk, juice, liquor, mineral water and the like. In the liquid paper container, for preserving the contents for a long period of time, in order to prevent deterioration due to oxidation, the packaging material is mainly paper, aluminum (hereinafter referred to as Al) foil, aluminum vapor-deposited layer, or silica vapor-deposited layer. A laminate is used in which a polyolefin (hereinafter, referred to as PO) resin such as a polyethylene (hereinafter, referred to as PE) resin is laminated on both surfaces of the outermost layer and the innermost layer.

[0003]

However, in a liquid paper container using such a laminate, although a stable gas barrier property is obtained, the paper layer and the barrier layer are firmly adhered to each other. And the barrier layer cannot be easily separated, and the paper layer cannot be separated and cannot be reused as paper recycling. For such a problem, the liquid paper container of the present invention provides a water-soluble resin layer between a paper layer and a barrier layer, so that a general consumer can be immersed in tap water, preferably hot water, The paper layer and the barrier layer can be easily peeled off. Furthermore, in the case of a liquid paper container with an extraction port, the extraction port can be separated along with the barrier layer. Therefore, it is possible to provide a liquid paper container in which disposal after use is easy and paper can be recycled.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and as a result, a liquid paper container comprising a laminate having at least a paper layer and a barrier layer has a paper layer and a barrier layer. And a liquid paper container characterized by comprising a laminate having a water-soluble resin layer provided between them. According to the present invention, by providing a water-soluble resin layer between the paper layer and the barrier layer, a general consumer can easily peel the paper layer and the barrier layer by immersing in tap water, preferably hot water. can do. Furthermore, in the case of a liquid paper container with a spout,
Spouts can also be separated associated with the barrier layer.
Therefore, it is possible to obtain a liquid paper container that can be easily discarded by separation after use and that can recycle paper.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid paper container according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a material configuration of a laminate that is a material of the liquid paper container of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a material configuration of the laminate of Example 1. FIG. 3 is a schematic cross-sectional view illustrating a material configuration of the laminate of Example 2. FIG. 4 is a schematic cross-sectional view illustrating a material configuration of a laminate of Example 3. FIG. 5 is a schematic cross-sectional view illustrating a material configuration of the laminate of Comparative Example 1. FIG.
6 is a schematic cross-sectional view illustrating a material configuration of a laminate of Comparative Example 2. FIG. FIG. 7 is a schematic cross-sectional view showing the material configuration of the laminate of Comparative Example 3.

The present invention mainly relates to a liquid paper container such as a goebel top type paper container or a cup type paper container. The material composition of the laminate 1 which is the material of the liquid paper container is basically shown in FIG. As shown, a PO resin layer 1 such as a PE resin is formed on the surface of the paper layer 12 using the paper layer 12 as a support.
1 and a water-soluble resin layer 1
, A barrier layer 14 such as a structure in which an Al foil and a polyethylene terephthalate (hereinafter referred to as PET) film are bonded with an adhesive, and a P
It is obtained by laminating PO resin layers 15 such as E.

As the paper layer 12 of the support, milk carton base paper or cup base paper is mainly used, but any paper which can be molded as a container without any problem in hygiene can be used. Paper can also be used. As for the thickness of the paper, those having a basis weight of 100 to 500 g / m ² are used,
For milk carton base paper, the basis weight is usually 113-34.
0 g / m ² paper is used, and also in the case of cup base paper, paper having a basis weight of 113 to 340 g / m ² is used.

As the barrier layer 14, usually, an Al foil is bonded to a PET film using an adhesive, and
To form a liquid paper container with barrier properties. As the barrier layer 14, in addition to a configuration in which an Al foil is attached to a PET film, a thin film layer may be formed on the PET film by vacuum deposition or sputtering, and used in some cases. In some cases, instead of Al vapor deposition, an inorganic oxide such as silica or alumina is used by forming a thin film layer on a plastic film such as a PET film by vacuum vapor deposition or sputtering. Other inorganic oxides include indium tin oxide (IT)
O) or metal oxides such as zinc, tin, titanium, zirconium, vanadium, barium, and chromium, silicon nitride, and silicon carbide. The thickness of the inorganic oxide thin film layer is 5
It can be used in the range of 0 to 3000 °, preferably 100
Å1000 °.

A plastic film for forming the barrier layer 14 can be used as long as it can be formed into a film with a thermoplastic resin, and is not particularly limited. For example, films such as PET, nylon, polypropylene, polyethylene, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, cellophane, and triacetate can be used. The film thickness is 1
It can be used in the range of 0 to 200 μm, preferably 10 to 200 μm.
80 μm.

[0010] An anchor coat layer is provided in order to improve the adhesion between the Al-deposited surface or the inorganic oxide-deposited surface and the inner PE. As the anchor coat layer, a phenolic resin, a vinyl resin, an acrylic resin, a polycarbonate resin, a polyester resin, a cellulose resin, a urethane resin, an ionomer resin, a polyolefin resin, or a modified resin thereof is used. You.

A wide range of water-soluble resins are used for the water-soluble resin layer 13. Examples thereof include polyethylene oxide, polyvinyl alcohol, polyethylene glycol, and the like, and modified resins, copolymers, and mixtures of these resins as long as the water solubility of the resin is not impaired.
There are several methods for forming the water-soluble resin layer 13. One way is to use films of these resins. Alternatively, there is a method based on melt molding, and various types of molding such as T-die extrusion molding and extrusion lamination processing are also possible and suitable. Furthermore, there is also a method of applying an adhesive dissolved in an emulsion or a solvent of these resins. Examples of the coating method include roll coating and gravure coating, and the amount of coating is not limited, but is preferably 0%. a ^{.5~10g / m 2, 0.5g / m} 2
It and reduces the releasability of the water below, not exhibited the effect of the present invention, curling the paper is produced during drying and they 10 g / m ² or more.

Next, a process of manufacturing the liquid paper container of the present invention using the laminate 1 will be described. First, the laminate 1 is punched into a blank plate for a liquid paper container in a punching step. Next, the punched blank plate is folded, and both end portions are thermally bonded to each other to obtain a tubular folded product. Subsequently, the tubular folded product is raised and made into a tubular shape, and the bottom is sealed with heat to produce a square tubular body having a bottom.
The rectangular cylinder is filled with the liquid as the contents, and the zenith is formed by heat and pressure to obtain a liquid paper container filled with the contents.

[0013]

Hereinafter, the liquid paper container of the present invention will be described in more detail with reference to examples and comparison with comparative examples.

Example 1 First, as shown in FIG. 2A, a milk carton base paper having a basis weight of 400 g / m ² was used as a paper layer 12 of a support, and low density PE (density:
0.923 g / cm ³ , MI: 3.7, melting point: 111
C.) to form a 20 μm-thick PO resin layer 11 by an extrusion method.
MI indicates a melt flow rate based on JIS-K-6900, and the same shall apply hereinafter.

Next, as shown in FIG.
PET layer 17 of 2 μm PET film, thickness 9 μm
Was laminated by a dry lamination method using a two-component curable isocyanate-based adhesive to form a barrier layer 14a.

Subsequently, the PO resin layer 1 of the laminated paper 3
A polyethylene oxide film of 20 μm as the water-soluble resin layer 13 is bonded to the opposite side of the paper layer 12, that is, the paper layer 12 by heat lamination (70 ° C., 50 kgf / cm ² ), and the polyethylene oxide film surface and the barrier layer 14 a 2A was dry-laminated with a two-component curable isocyanate-based adhesive to form a laminated sheet 4a as shown in FIG. 2 (c).

Further, an isocyanate-based anchor coating agent is applied as an anchor coat layer 19 on the PET film surface of the laminated sheet 4a, and a PO resin layer 15 having a thickness of 4
While supplying a 0 μm PE film, low-density PE (density: 0.923 g / cm ³ , MI: 3.7, melting point: 11)
1 ° C.), melt-extruded, and laminated by a sandwich lamination method, as shown in FIG.
m of PE layers 19 were formed to form a laminate 1a.

Example 2 First, as in Example 1, a laminated paper 3 was prepared as shown in FIG. Next, an Al vapor-deposited film 16b having a thickness of 400 ° was formed on a PET film having a thickness of 12 μm by a vacuum vapor deposition method.
As shown in (b), a barrier layer 14b was formed.

Subsequently, as the water-soluble resin layer 13, 20 μm
m of polyethylene oxide film is adhered by thermal lamination, and the polyethylene oxide film surface and the Al vapor-deposited film 16b of the barrier layer 14 are dry-laminated using a two-part curable isocyanate-based adhesive.
As shown in (c), a laminated sheet 4b having an Al deposited film 16b as the barrier layer 14b was prepared. further,
A two-component curing type anchor coating agent is applied to the PET layer 17 of the laminated sheet 4b, and the PO resin layer 15 having a thickness of 40 μm is formed by a sandwich lamination method of PE.
By laminating with a film, a laminate 1b as shown in FIG.

Example 3 First, as in Example 2, a laminated paper 3 was produced as shown in FIG. Next, a silicon oxide (SiO ₂ ) deposited film 1 having a thickness of 500 ° was formed on a PET film having a thickness of 12 μm by a vacuum deposition method.
6c was formed as the barrier layer 14c. Subsequently, a 20 μm polyethylene oxide film was bonded as a water-soluble resin layer 13 by heat lamination, and the polyethylene oxide film surface and the PET film surface of the barrier layer 14 c were dried using a two-component curable isocyanate-based adhesive. After lamination, as shown in FIG. 4 (c), a laminated sheet 4c having an SiO ₂ evaporated film 16c as a barrier layer 14c was prepared. Further, in the same manner as in Example 2, a two-component curing type anchor coating agent is applied to the SiO ₂ vapor-deposited film 16c of the laminated sheet 4c, and the laminated sheet 4 and PO
A 40 μm-thick PE film as the resin layer 15 is
The laminate E was laminated by the sandwich lamination method of E to form a laminate 1c as shown in FIG.

Example 4 In Example 1, an adhesive made of polyvinyl alcohol resin was used for the water-soluble resin layer 13 instead of the polyethylene oxide resin.
An emulsion adhesive of a polyvinyl alcohol resin is coated on the paper layer 12 of the laminated paper 3 at a coating amount of 5 g / m ² , dried, subjected to a corona treatment, and coated with the polyvinyl alcohol resin and the AL of the barrier layer 14a. The foil 16a surface was laminated. Others are the same as in Example 1. Further, as in Example 1, a two-component curing type anchor coating agent is applied to the PET layer 17 and the PO resin layer 1
A 40 μm-thick PE film as No. 5 was laminated by a sandwich lamination method of PE to form a laminate 1d as shown in FIG.

(Example 5) In Example 2, instead of polyethylene oxide resin, a polyvinyl alcohol resin adhesive was used as the water-soluble resin layer 13.
An emulsion adhesive of polyvinyl alcohol resin is coated on the paper layer 12 of the laminated paper 3 at a coating amount of 5 g / m ² , dried, subjected to a corona treatment, coated with the polyvinyl alcohol resin, and coated on the barrier layer 14b. Lamination was performed with the deposition surface. Further, in the same manner as in Example 2, a two-component curable anchor coating agent is applied to the PET layer 17, and a 40-μm-thick PE film as the PO resin layer 15 is laminated by a sandwich lamination method of PE. A laminate 1e as shown in FIG. 6 was produced.

(Example 6) In Example 3, an adhesive made of polyvinyl alcohol resin was used for the water-soluble resin layer 13 instead of the polyethylene oxide resin.
An emulsion adhesive of polyvinyl alcohol resin is coated on the paper layer 12 of the laminated paper 3 at a coating amount of 5 g / m ² , dried, subjected to corona treatment, and PET coated on the coated surface of the polyvinyl alcohol resin and the barrier layer 14c.
Lamination was performed with the film surface. Further, Example 3
Similarly to the above, a two-component curable anchor coating agent is applied to the SiO ₂ vapor-deposited film
A μm PE film was laminated by a sandwich lamination method of PE to obtain a laminate 1 as shown in FIG.
f was created.

(Example 7) In Example 3, an adhesive made of polyvinyl alcohol resin was used for the water-soluble resin layer 13 instead of the polyethylene oxide resin.
An emulsion adhesive of polyvinyl alcohol resin is coated on the paper layer 12 of the laminated paper 3 at a coating amount of 5 g / m ² , dried, subjected to a corona treatment, and melt-extruded on the coated surface of the polyvinyl alcohol resin by 30 μm.
A low-density polyethylene resin layer having a thickness of m was provided as a PO resin layer 15 to prepare a laminate 1g as shown in FIG.

(Comparative Example 1) In Example 1, an ethylene / methacrylic acid copolymer was used instead of the polyethylene oxide film of a water-soluble resin, and extruded and laminated at a thickness of 20 μm. hand,
A laminate 2a as shown in FIG. 9 was produced.

Comparative Example 2 In Example 2, an ethylene / methacrylic acid copolymer was used in place of the polyethylene oxide film of the water-soluble resin, extruded and laminated at a thickness of 20 μm, and the other conditions were the same as in Example 2. hand,
A laminate 2b as shown in FIG. 10 was created.

Comparative Example 3 In Example 3, an ethylene / methacrylic acid copolymer was used in place of the polyethylene oxide film of the water-soluble resin, and extruded and laminated at a thickness of 20 μm. hand,
A laminate 2c as shown in FIG. 11 was created.

The laminates prepared in Examples 1 to 7 and Comparative Examples 1 to 3 prepared as described above were used as samples.
It was sliced into 0 mm × 50 mm, and the dissolution time and solubility were examined.

Table 1 shows the test results. As can be seen from Table 1, the laminates prepared in Examples 1 to 7 took approximately 5 minutes to 10 minutes.
After a minute, the water-soluble resin, polyethylene oxide, was dissolved, and the paper and the barrier layer were easily separated. On the other hand, the laminate of the comparative example not using the water-soluble resin was 6
No delamination occurred even after 0 minutes, suggesting that it is difficult to recycle waste paper. Therefore, the liquid paper container of the present invention that uses the laminates manufactured in Examples 1 to 7 can easily peel paper with an aqueous solution, and can be reused for recycling used paper. Similarly, in a liquid paper container with a spout, the spout can be separated together with the barrier layer. (Below)

[0030]

[Table 1] A: Peeled off within 10 minutes. ：: peeled off within 20 minutes. X: It does not peel even after 60 minutes.

[0031]

According to the present invention, the water-soluble resin layer is provided between the paper and the barrier layer in the layer structure of the liquid paper container. The barrier layer can be easily peeled off. Therefore, after the portion where the barrier layer and the plastic film are laminated is peeled off from the paper container, the paper laminated with PE can be easily recycled into waste paper in the conventional waste paper recycling process. Therefore, since the liquid paper container of the present invention can be recycled for recycling used paper, the problem of disposal of the container can be solved and resources can be saved. The water-soluble resin used in the present invention is a thermoplastic resin, and can be laminated by an extrusion method using an extruder. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a material configuration of a laminate that is a material of a liquid paper container of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating a material configuration of a laminate of Example 1.

FIG. 3 is a schematic cross-sectional view illustrating a material configuration of a laminate of Example 2.

FIG. 4 is a schematic cross-sectional view illustrating a material configuration of a laminate of Example 3.

FIG. 5 is a schematic cross-sectional view illustrating a material configuration of a laminate of Example 4.

FIG. 6 is a schematic cross-sectional view illustrating a material configuration of a laminate of Example 5.

FIG. 7 is a schematic cross-sectional view illustrating a material configuration of a laminate of Example 6.

FIG. 8 is a schematic cross-sectional view showing a material configuration of a laminate of Example 7.

FIG. 9 is a schematic cross-sectional view illustrating a material configuration of a laminate of Comparative Example 1.

FIG. 10 is a schematic cross-sectional view illustrating a material configuration of a laminate of Comparative Example 2.

FIG. 11 is a schematic cross-sectional view illustrating a material configuration of a laminate of Comparative Example 3.

[Explanation of symbols]

Reference Signs List 1 laminate 1a laminate (laminate of Example 1) 1b laminate (laminate of Example 2) 1c laminate (laminate of Example 3) 1d laminate (laminate of Example 4) 1e laminate (Laminate of Example 5) 1f Laminate (Layer of Example 6) 1g Laminate (Layer of Example 7) 2a Laminate (Layer of Comparative Example 1) 2b Laminate (Layer of Comparative Example 2) 2c laminated body (laminated body of Comparative Example 3) 3 laminated paper 4 laminated sheet 4a laminated sheet (Example 1) 4b laminated sheet (Example 2) 4c laminated sheet (Example 3) 11 PO resin layer (extruded PE) ) 12 paper layer 13 water-soluble resin layer 14 barrier layer 14a barrier layer (Al foil) 14b barrier layer (Al deposited film) 14c barrier layer (SiO ₂ deposited film) 15 PO resin layer 16a Al foil 16b Al deposited film 16c SiO ₂ Evaporated film 1 7 PET layer 18 Adhesive layer 19 PE layer 20 Anchor coat layer 21 Ethylene / methacrylic acid copolymer layer

Claims (1)

[Claims] 1. A liquid paper container comprising a laminate having at least a paper layer and a barrier layer, wherein the liquid comprises a laminate having a water-soluble resin layer provided between the paper layer and the barrier layer. Paper container.