JPH07291268A - Paper container - Google Patents

Abstract

PURPOSE:To obtain a paper container which prevents alkaline liquid contents from leaking and is appropriate for long-term preservation. CONSTITUTION:A paper container comprised of a laminate body having paper as its base material has at least a biaxially oriented poly-P-phenylenesulfide layer 5 on its inside. The laminate body comprises, for example, a polyethylene layer 1, the paper layer 2, a polyethylene layer 3, an aluminum foil 4, the biaxially oriented poly-P-phenylenesulfide layer 5, and a polyethylene layer 6, in that order from the top.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper container which is suitable for storage of acidic or alkaline liquid contents.

[0002]

2. Description of the Related Art In general, a liquid paper container is formed by using various laminated bodies mainly composed of paper in order to secure the storability of contents, suitability for distribution and handling. For example, a laminated body of polyethylene (PE) / paper / PE is used in milk and fruit juice drinks that are chilled and have a short shelf life. Further, even if the chilled product has a long shelf life, in order to prevent liquid leakage and impart an oxygen barrier property, for example, as shown in FIG.
1 / Paper 2 / PE3 / Aluminum foil 4 / Biaxially oriented polyester (PET) 8 / PE6 is widely used, or PE / paper / ethylene-acrylic acid copolymer / aluminum foil / two A layered structure such as axially stretched PET / PE is also used. In the above laminated body, the biaxially stretched PET prevents the generation of pinholes due to heat of heat sealing of the paper container, ruled line processing and folding,
It is used to prevent liquid leakage. The innermost layer PE
If there is a pinhole, it also has the effect of preventing the penetration of the contents. On the other hand, the aluminum foil is used for imparting a gas barrier property, and when the aluminum foil is not used, biaxially stretched PET vapor-deposited with silica may be used.

[0003]

However, in the above-mentioned conventional liquid paper container, when the content to be contained is an alkaline substance, if a pinhole is generated in the innermost layer PE, it is provided adjacent to the PE layer. Since the biaxially stretched PET layer is not sufficiently resistant to alkali, there is a problem in that the biaxially stretched PET layer is hydrolyzed when contacted with the content, and the content further invades the aluminum, and finally liquid leakage occurs. Further, the above problems are premised on eliminating pinholes in the innermost PE layer, but it is difficult to eliminate such pinholes during film formation and post-processing. The present invention has been made in view of the above circumstances, and particularly when the content to be contained is an alkaline substance, an object thereof is to provide a paper container having good storage suitability for safely storing the content. To do.

[0004]

In order to solve the above-mentioned problems, the present invention provides a paper container comprising a laminate having a paper layer as a base material, and at least a biaxially stretched poly- A P-phenylene sulfide layer is provided, an aluminum foil layer is provided between the paper layer and the biaxially stretched poly-P-phenylene sulfide layer, and at least the outermost portion of the laminate,
A gist of a paper container is characterized in that it has a polyolefin resin layer as the innermost layer, and if necessary, a thin film layer of an inorganic oxide is provided on the surface of the biaxially stretched poly-P-phenylene sulfide layer.

[0005]

The paper container according to the present invention does not leak when the contents to be contained are alkaline substances and exhibits particularly excellent storability.

[0006]

The present invention will be described in detail below with reference to the drawings.
The paper container of the present invention is a paper container formed by using a laminate having a paper layer as a base material, and at least a biaxially stretched poly-P-phenylene sulfide layer is provided on the inner surface side of the container. Here, the biaxially stretched poly-P-phenylene sulfide layer means poly-P-phenylene sulfide (P
It is a film obtained by melt-molding a resin composition containing PS as a main component to form a sheet, biaxially stretching and heat-treating.
The resin composition containing poly-P-phenylene sulfide as a main component (hereinafter sometimes referred to as PPS-based composition) means a composition containing 90% by weight or more of PPS. When the content of PPS is less than 90% by weight, the crystallinity and thermal transition of the composition are lowered, and the heat resistance, dimensional stability, mechanical properties, etc., which are the features of the film made of the composition, are impaired. The remaining less than 10% by weight in the composition may contain additives such as polymers other than PPS, inorganic or organic fillers, lubricants, colorants, and ultraviolet absorbers. In the present invention, PPS is a polymer in which 70 mol% or more (preferably 85 mol% or more) of the repeating unit is composed of the structural unit represented by the structural formula in the attached sheet (Chemical Formula 1).

[Chemical 1] If the amount of such components is less than 70 mol%, the crystallinity of the polymer, the heat transition temperature, etc. are lowered, and the heat resistance, dimensional stability, mechanical properties, etc., which are characteristics of the film made of the resin composition containing PPS as a main component, are impaired. Less than 30 mol% of repeating units,
If it is preferably less than 15 mol%, a unit containing a copolymerizable sulfide bond may be contained. The thickness of the biaxially stretched poly-P-phenylene sulfide layer (biaxially stretched PPS film) is not particularly limited, but normally about 5 to 80 μm is suitable. Above PPS
The film has resistance to acids, alkalis, oils and various solvents, and has hydrolysis resistance and heat resistance.

The laminate of the paper container according to the present invention is characterized in that at least a biaxially stretched PPS film is provided, and the layer structure other than the biaxially stretched PPS film is not particularly limited. That is, various layer configurations other than the biaxially stretched PPS film can be considered. An example of this laminate is shown in FIGS. Figure 1
Is a PE layer 1 / paper base material 2 / P in order from the outside.
E layer 3 / Aluminum foil 4 / Biaxially stretched PPS film 5 / PE
It is composed of the layer 6. Where PE is the outermost layer
As the PE forming the layer 1, for example, low density polyethylene, linear low density polyethylene, high density polyethylene or the like is used, and the thickness thereof is preferably about 10 to 30 μm. Further, it is preferable that the surface thereof is subjected to surface treatment such as corona discharge treatment in order to impart printability. The basis weight of the paper base material ² is preferably about 100 to 500 g / m ² . Examples of a method for laminating the paper base material 2 and the PE layer 1 include an extrusion lamination method and the like. PE
Examples of PE forming the layer 3 include low-density polyethylene and the like, but in addition, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer and the like are also used. The thickness is preferably about 10 to 50 μm. The PE layer 3 is used to attach the paper base material 2 and the aluminum foil 4 by sand lamination.
The aluminum foil 4 is used to impart a high gas barrier property. A suitable thickness is 5 to 30 μm. The biaxially stretched PPS film 5 and the aluminum foil 4 are bonded together by dry lamination. As the PE forming the innermost PE layer 6, for example, low-density polyethylene,
Linear low density polyethylene, high density polyethylene, etc. are used. Instead of the PE layer 6, the innermost layer may be formed of a linear low crystalline polyester, an ethylene-vinyl alcohol copolymer, or the like, which hardly absorbs the flavor of the contents. A suitable thickness of the PE layer 6 is about 40 to 150 μm. Further, as a method for laminating the PE layer and the biaxially stretched PPS film 5, known methods such as an extrusion lamination method and a dry lamination method can be used.

The laminated body shown in FIG. 2 is obtained by removing the aluminum foil 4 from the laminated body shown in FIG. The laminated structure is composed of PE layer 1 / paper base material 2 / PE layer 3 / biaxially stretched PPS film 5 / PE layer 6 in order from the outside.

The laminate shown in FIG. 3 has a structure in which the aluminum foil 4 is removed from the laminate shown in FIG. 1 and an inorganic oxide thin film layer 7 is provided on the surface of the biaxially stretched PPS film 5 on the contents side. The other points are the same as those of the laminated body shown in FIG. Here, the inorganic oxide thin film layer 7 has a function of imparting a high barrier property to water vapor, oxygen, etc., and is composed of silicon oxide (SiO _x ), aluminum oxide (A
1 _x O _Y ) and other inorganic oxides. Examples of the method for forming the inorganic oxide thin film layer 7 include a physical vapor deposition method and a chemical vapor deposition method. A suitable thickness of the inorganic oxide thin film layer 7 is about 100 to 2000Å. It should be noted that carbon black is mixed into the resin to be vapor-deposited or black printing is performed in order to impart a light-shielding property. In order to impart this printability, an olefin layer containing a white pigment or a white printed olefin layer may be provided on the outside of the inorganic oxide vapor deposition film.
Thus, in the present invention, by providing the inorganic oxide thin film layer 7, a high barrier property against water vapor, oxygen and the like can be provided without using an aluminum foil.

If necessary, each resin layer constituting the paper container of the present invention contains an antioxidant, an ultraviolet absorber, an antistatic agent, an antiblocking agent, a lubricant, a flame retardant, an inorganic or organic material. Fillers, dyes, pigments and the like may be added appropriately.

The paper container of the present invention formed by using the laminated body as shown in FIGS. 1 to 3 can be assembled into various shapes such as a Gobeltop type, a flattop type and a brick type.
In this case, the laminate is punched out as a blank, and in the Gobel top, flap top type paper container, the one in which the body is pasted with a frame seal or a hot air seal is supplied to a filling machine, and molded and filled on the filling machine. Often seals. In addition, in order to prevent the end surface of the paper base material from coming into contact with the contents, skiving hemming tape sticking is often performed on the blank before sticking the body. Also, in a brick-type paper container,
In many cases, the material is supplied in a roll form to a molding and filling machine, and molding, filling, and sealing are continuously performed.

The use of the paper container of the present invention is not particularly limited, but for example, car cleaning agents, floor cleaning agents, kitchen detergents,
Various detergents such as liquid detergent for laundry, toiletries such as shampoo, rinse, perm solution, chemical products such as mold repellent, developer, pesticides, and sake, shochu, wine, milk, fruit juice beverage,
It is preferably applied as a liquid food container for green tea, black tea, oolong tea, soy sauce, mirin, dressing and the like. Further, the paper container of the present invention is not limited to the liquid contents.

[0013]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Example 1) As shown in FIG. 1, a low-density polyethylene ("Mirason 16P" manufactured by Mitsui Petrochemical Co., Ltd.) 1 having a thickness of 30 μm was formed on one surface of a paper substrate 2 having a basis weight of 400 g / m ^2. After extrusion lamination, the surface was subjected to corona discharge treatment. Then, dry laminating an aluminum foil having a thickness of 9 μm and a biaxially stretched PPS film 5 having a thickness of 12 μm,
Further, a low-density polyethylene film (“Mirason 16P” manufactured by Mitsui Petrochemical Co., Ltd.) 6 having a thickness of 60 μm was dry-laminated on the other surface of the biaxially stretched PPS film 5. The dry lamination was performed by applying a two-component curing type urethane adhesive at 3 g / m ² . An ethylene-methacrylic acid copolymer having a thickness of 30 μm (“Neucrele N” manufactured by Mitsui DuPont Polychemical Co., Ltd.) was formed on the aluminum foil 4 side of the thus obtained laminate and the other surface of the paper base material 2. -1108A ") Layer 3 was subjected to sand lamination to prepare a laminated sheet for a paper container. Next, using the laminated sheet for a paper container, the internal volume of which is 1.8 L and 85 mm
A square gobel top pattern paper container (carton) was prepared.
Incidentally, in order to prevent the body end face which is the container inner face side of the paper container laminate sheet from contacting the contents, after covering the container inner face side end face of the laminate sheet with a skive hemming tape, Pasted together The paper container thus obtained was filled with the contents of the following composition and stored at a temperature of 50 ° C. for 6 months, and the occurrence of liquid leakage was evaluated. The results are shown in Table 1. The occurrence of liquid leakage was visually determined. Content composition Sodium hydroxide 4% by weight Anionic surfactant 30% by weight Water 66% by weight

(Embodiment 2) As shown in FIG.
30 μ of low density polyethylene (“Mirason 16P” manufactured by Mitsui Petrochemical Co., Ltd.) 1 on one surface of the paper base material 2 of 0 g / m ^2.
After extrusion-lamination with a thickness of m, the surface was subjected to corona discharge treatment. Then, a biaxially stretched PP having a thickness of 12 μm
An S film 5 and a low-density polyethylene (“Mirason 16P” manufactured by Mitsui Petrochemical Co., Ltd.) 6 having a thickness of 60 μm 6 were dry laminated using a two-component curing type urethane adhesive. Furthermore, on the other surface of the biaxially stretched PPS film 5,
After applying the isocyanate-based anchor coating agent, low-density polyethylene (“Mirason 16P” manufactured by Mitsui Petrochemical Co., Ltd.) 3 was extruded and laminated to a thickness of 15 μm, and this surface and the other surface of the paper substrate 2 were laminated. , Thickness 1
Through a 5 μm low density polyethylene (“Mirason 16P” manufactured by Mitsui Petrochemical Co., Ltd.), sand lamination was performed to prepare a laminated sheet for a paper container. Next, using the above-mentioned laminated sheet for paper containers, an 85 mm square Gobel-top type paper container having an internal volume of 1.8 L was prepared in the same manner as in Example 1. The paper container thus obtained was evaluated for liquid leakage in the same manner as in Example 1. The results are shown in Table 1.

(Example 3) As shown in FIG. 3, a 500 Å-thick silicon oxide thin film layer 7 was formed on the surface of the biaxially stretched PPS film 5 on the contents side by vacuum deposition without using an aluminum foil. Except for the above, a laminated sheet for a paper container was prepared in the same manner as in Example 2, and an 85 mm square Gobel-top type paper container having an internal capacity of 1.8 L was prepared using this laminated sheet for a paper container. The paper container thus obtained was evaluated for liquid leakage in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 The same as Example 1 except that a 12 μm thick biaxially oriented polyethylene terephthalate (PET) film was used in place of the biaxially oriented PPS film. To produce a laminated sheet for a paper container, and using this laminated sheet for a paper container, an 85 mm square Gobel-top type paper container having an internal volume of 1.8 L was produced. The paper container thus obtained was evaluated for liquid leakage in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 The same as Example 3 except that a biaxially stretched polyethylene terephthalate (PET) film having a thickness of 12 μm was used in place of the biaxially stretched PPS film in Comparative Example 2. To produce a laminated sheet for a paper container, and using this laminated sheet for a paper container, an 85 mm square Gobel-top type paper container having an internal volume of 1.8 L was produced. The paper container thus obtained was evaluated for liquid leakage in the same manner as in Example 1. The results are shown in Table 1.

[0018]

[Table 1] 6-month storage test results

(Results of Evaluation) As is clear from Table 1,
In the conventional paper containers (Comparative Examples 1 and 2), the content liquid penetrates through the pinholes of the PE layer, which is the innermost layer, and penetrates the layers such as the biaxially stretched PET film and the aluminum foil to cause the liquid leakage for the first month. However, the paper container according to the present invention (Examples 1 to 3)
No liquid leakage was observed even after storage for 6 months.

[0020]

The paper container according to the present invention has a PPS film provided on the inner surface of the container so that it can have good storability against leakage of alkaline contents. By making it possible to switch to, it is possible to significantly reduce the amount of plastic, reduce the total cost of manufacturing and logistics, and further reduce the environmental impact by facilitating disposal after use. There is.

[Brief description of drawings]

FIG. 1 is a sectional view of Example 1 of a paper container laminate of the present invention.

FIG. 2 is a sectional view of Example 2 of the paper container laminate of the present invention.

FIG. 3 is a sectional view of Example 3 of the paper container laminate of the present invention.

[Explanation of symbols]

1 PE layer (outermost layer) 2 Paper base layer 3 PE layer 4 Aluminum foil 5 Biaxially stretched poly-P-phenylene sulfide layer (PPS film) 6 PE layer (innermost layer) 7 Inorganic oxide thin film layer 8 Biaxially stretched Polyethylene terephthalate (PET)
layer

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[Procedure amendment]

[Submission date] December 16, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a sectional view of Example 1 of a paper container laminate of the present invention.

FIG. 2 is a sectional view of Example 2 of the paper container laminate of the present invention.

FIG. 3 is a sectional view of Example 3 of the paper container laminate of the present invention.

FIG. 4 is a sectional view of a conventional liquid paper container stack.

[Explanation of Codes] 1 PE layer (outermost layer) 2 Paper base material layer 3 PE layer 4 Aluminum foil 5 Biaxially stretched poly-P-phenylene sulfide layer (PPS film) 6 PE layer (innermost layer) 7 Inorganic oxide thin film Layer 8 Biaxially oriented polyethylene terephthalate (PET)
layer

Claims (4)

[Claims] 1. A paper container comprising a laminated body having a paper layer as a base material, wherein at least a biaxially stretched poly-P-phenylene sulfide layer is provided on the inner surface side of the base material in the paper container. . 2. The paper container according to claim 1, further comprising an aluminum foil layer provided between the paper layer and the biaxially stretched poly-P-phenylene sulfide layer. 3. The paper container according to claim 1 or 2, wherein at least the outermost and innermost layers of the laminate have a polyolefin resin layer. 4. The paper container according to claim 1, wherein a thin film layer of an inorganic oxide is provided on the surface of the biaxially stretched poly-P-phenylene sulfide layer.