JP2000128184A - Paper bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper bag which is suitable as a multiply bag for housing easily solidifying articles, and is equipped with a moderate air-permeability and a low moisture permeability while being recyclable. SOLUTION: A base for which laminated parts 12 on which a resin layer is respectively laminated and non-laminated parts 13 on which lamination is not made are arranged alternately at least on one side of a paper 11 is used as the base 10 for forming a paper bag. The bag is desirable to be such that is a multiply bag made up by laminating such bases. At this time, the laminated parts of the adjoining bases constituting a multiple layer or the laminated parts are not overlapped with one another. The resin layer (the laminated parts) 12 is desirable to be formed by partial coating with a water-soluble high molecular compound or by partial lamination with a biodegradable resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper bag suitable for storing industrial powders such as cement and fertilizers and food powders.

[0002]

2. Description of the Related Art As a conventional heavy bag, in particular, a paper bag of cement or the like in which contents are easily consolidated, a multilayer bag of kraft stretched paper is used. Such a multi-layer bag is generally formed by stacking two or three layers of kraft stretched paper and sandwiching a plastic film such as a polyethylene film between the layers. Water penetrates into the bag, thereby preventing the cement from solidifying. Also, the polyethylene film is provided with a number of slits to allow air to escape when the contents are filled.

[0003] Such a conventional cement paper bag uses a plastic film to impart water resistance to kraft paper, and therefore cannot be recycled or pollutes the environment when recycled, discarded or incinerated after use. There was a problem.

On the other hand, coated paper having a functional coating for the purpose of imparting waterproofness and water resistance to paper has been widely used for various packaging purposes. In some cases, this coated paper is used as a heavy bag for storing the above-mentioned cement, fertilizer, and the like. However, if the coating material is plastic, there may be a problem at the time of disposal or recycling as in the case of the polyethylene film described above. In addition, coated paper is generally excellent in terms of preservation of its contents because of its high airtightness.However, when filling the contents at high pressure, there is no escape of air, so there is a risk of damage, etc. Not suitable for use as.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a paper bag which is recyclable, has no problem of environmental pollution at the time of disposal or incineration, and has various performances required for heavy bags. And

[0006]

A paper bag according to the present invention for achieving the above object is a paper bag made of paper as a base material, wherein a resin layer is laminated on at least one side of paper as a base material and a resin layer. It is provided so that non-laminated portions where layers are not laminated are mixed.

By partially providing the resin layer, it is possible to secure the required air permeability at the time of filling, reduce the moisture permeability, and protect the contents from moisture.

[0008] In order to obtain the above performance, the ratio of the laminated portion to the base material is 25 to 80% or more of the area of the base material, preferably 3 to 80%.
It is preferable to set it to 5 to 70%. If the area of the laminated portion is too small, sufficient moisture permeability cannot be obtained. If the area of the laminated portion is too large, the paper bag becomes airtight and loses air permeability, and the bag may be damaged by the pressure at the time of filling the contents.

The laminated portion and the non-laminated portion need only be arranged substantially evenly on the substrate, and their shapes and patterns are not particularly limited. As an example, the laminated portion and the non-laminated portion are each formed in a linear shape. , Can be arranged alternately.

In the case of a multi-layered paper bag in which a plurality of base materials are stacked,
It is preferable that the laminated portions or the non-laminated portions are arranged so as not to overlap each other between the adjacent base materials.

As the resin forming the resin layer, a biodegradable resin or a water-soluble resin is preferably used. This enables recycling, and there is no risk of polluting the environment when discarded or incinerated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the paper bag of the present invention will be described below with reference to the drawings.

FIG. 2 is a view showing the entirety of a cement paper bag 20 to which the present invention is applied. The upper end of a paper tube 21 is notch-cut, the lower end is cut straight, and both ends are taped for reinforcement 22. And a valve opening 23 for taking in and out the contents is formed in a notch-cut portion at the upper end.

The paper tube 21 is formed by laminating one or more layers of a base material into a tube shape. In the present invention, a resin layer is partially laminated on kraft paper or stretched kraft paper as a base material. Use the one that is

FIG. 1 is a view showing one embodiment of such a base material 10. A plurality of linear resin layers (laminated portions) 12 are provided on at least one surface of kraft paper or stretched kraft paper 11.
(Indicated by oblique lines in the drawing). Resin layer 1
The portion 13 between the resin layer 2 and the resin layer 12 is a portion (unlaminated portion) of unprocessed kraft paper or stretched kraft paper. The widths w1 and w2 of the laminated portion 12 and the non-laminated portion 13 are not particularly limited, and w1 and w2 may be the same or different.
It is preferable that the laminated portion 12 and the non-laminated portion 13 are arranged substantially evenly. For example, in the case of a cement paper bag having a body width of 419 mm, w1 is set to 20 to 100 mm, preferably about 40 to 60 mm. Further, the ratio of the laminated portion 12 and the non-laminated portion 13 is preferably about 20:80 to 80:20 in area ratio. Thereby, uniform characteristics (water resistance, air permeability, strength, etc.) can be imparted to the entire bag.

It is preferable to use a water-soluble resin or a biodegradable resin as a material constituting the resin layer. Examples of the water-soluble resin include natural polymer compounds such as casein, albumin and gelatin; water-soluble celluloses such as methylcellulose, carboxymethylcellulose and human doxyethylcellulose; polyethers such as polyethylene glycol and polypropylene glycol; and (meth) acrylic acid. Water-soluble synthetic polymers such as water-soluble acrylic resins such as acrylic polymers and acrylic-styrene copolymers, and water-soluble polybutyral and polyvinyl alcohol. Such a water-soluble resin is easily dissolved in water in a recycling process or the like, so that the paper bag can be easily recycled, and no toxic substance is generated even when incinerated.

A biodegradable resin is a material that can be decomposed into low molecular weight compounds such as carbon dioxide, methane, water, and biomass in a relatively short time by microorganisms, etc., and uses microbial polysaccharides such as cellulose, chitin, and chitosan. Synthetic biodegradable resin such as microbial biodegradable resin, polylactic acid, polyglycolide, polyγ-methylglutamate, polycaprolactone, fatty acid polyester, etc., composite biodegradability such as chitosan / cellulose mixture, starch / polyvinyl alcohol polymer alloy Resins can be used. Many of these biodegradable resins are water-soluble resins and, like the water-soluble resins described above, are easily dissolved in water during the recycling process, etc., so that paper bags can be easily recycled. Even if released, it is quickly decomposed into low molecular weight compounds, and there is no problem of environmental pollution.

The resin layer 12 can be formed by a known coating method such as bar coating, roll coating, gravure coating, air knife coating, blade coating, or the like, or a solution obtained by dissolving or dispersing the above resin in water or an emulsion of these resins. In the case of a biodegradable resin, a method of applying a film or laminating a film made of such a resin by melt extrusion can also be adopted.

Although the thickness of the resin layer 12 is not particularly limited,
When the resin layer is formed by coating, it is usually 10 g / m ² or more in terms of wet weight. Further, when formed by lamination, 15 μm to 60 μm, preferably 25 μm to 35 μm.
μm.

When the paper bag of the present invention is applied to, for example, a cement paper bag shown in FIG. 2, it is manufactured as follows.

First, one or two substrates 10 having the above-described structure are used.
The ends of the stacked pieces are laminated with a water-soluble adhesive or the like to form a tube. In this case, the resin layer 12 may be on the inner side or the outer side of the paper bag. It is preferable that the resin layer 12 be located on the inner side in view of printability and appearance of the paper bag.

When a plurality of base materials are stacked to form a multilayer bag, the laminated portions 12 and the non-laminated portions 13 are alternately arranged as shown in FIGS. 3 (a) to 3 (c). Laminate. FIG. 4A shows a case where the width w1 of the laminated portion 12 is equal to the width w2 of the non-laminated portion 13, and FIGS. 4B and 4C show w1 respectively.
> W2, w1 <w2. Or the same figure (d)
As shown in FIG.
2 may be overlapped so as to be orthogonal. Also, in FIG. 3, the two substrates are overlapped in the same direction, but may be reversed. For example, as shown in FIG. 4 (a), the resin layer may be on the inside or vice versa. You may overlap so that it may become outside. Further, as shown in FIG. 4B, only one of the two layers of base material may be a base material on which a resin layer is formed, and the other may be ordinary kraft paper. Further, three or more base materials may be stacked.

Such a tube is cut, and at least one end (lower end) is closed by sewing or bottoming, and the upper end is opened, or the upper end is notch-cut, and the valve is left closed to close the valve. Obtain the paper bag of the invention. The sealing method and shape of the paper bag are not particularly limited, and may be any method and shape. For example, in the case of the cement paper bag shown in FIG. 2, the upper end of the tubular base material is notch-cut, and the lower end is cut straight. The straight end is covered with the reinforcing paper 24 and the crepe tape 22, glued and sewn with a sewing machine. Then, a valve port 23 for filling cement is formed in the notch cut portion at the upper end, and a cement paper bag is manufactured.

Since the paper bag of the present invention is formed such that the resin layer and the non-laminated portion are mixed on at least one surface of the base material, air is released when the contents are filled, and damage is prevented. Also, since the contents are provided with moisture-proof properties, the contents can be protected from moisture when the contents are stored. In particular, when the base materials are used in layers as shown in FIG. 3, a high moisture-proof effect can be obtained while maintaining sufficient air permeability. Further, by using a water-soluble resin or a biodegradable resin as the resin layer, a paper bag which is easy to recycle and has no problem of environmental pollution can be provided.

In the above embodiment, the pattern of the resin layer formed partially is a linear pattern. However, the pattern of the resin layer is not limited to this. For example, a checkerboard pattern, a lattice pattern, a concentric pattern, or the like can be used. It can be changed arbitrarily.

Also, an example in which the paper bag of the present invention is applied to a cement paper bag has been described. However, the paper bag of the present invention is not limited to a cement paper bag, but is also used for heavy bags for storing beans, grains, etc., and for other uses. The form and the structure can be changed according to each use.

[0027]

Embodiments of the present invention will be described below. Example 1 A biodegradable resin film (polylactic acid-based polymer) was laminated on one side of kraft paper in a strip shape at a thickness of 30 μm, a width of 50 mm, and at regular intervals, and a laminated portion and a non-laminated portion alternated as shown in FIG. Were prepared. Using this base material, a cement paper bag having a length of 200 mm and a body width of 150 mm was produced.

The moisture permeability of the paper bag was measured. The moisture permeability is
Based on the moisture permeability test method of JIS-Z-0222, the amount of water vapor (g / m ² · 24 hr) that entered the paper bag within a certain time was measured.

Further, actually dried cement was stored in this paper bag, the change in the water content of the cement before and after the storage (moisture percentage) was measured, and the presence or absence of cement consolidation after storage was observed. For the measurement of the moisture content, the moisture test method of JIS-p-8127 was applied mutatis mutandis, and the moisture content in the dried cement and the change (%) in the moisture content of the cement after 14 days had passed after storage in this paper bag were expressed by the following formula. Determined by M = {(L1−L2) / L2} × 100 (where, M is the moisture content (%), L2 is the mass of the cement after drying (g), and L1 is 14 days after storing the cement in a paper bag. Regarding the consolidation of cement (expressing mass (g)), it was observed whether or not the contents had consolidated after being left for 50 days in an environment with a humidity of 90% and a temperature of 40 ° C. Furthermore, the air permeability at the time of cement filling was observed.

Table 1 shows the results. In the table, regarding the air permeability, those showing sufficient air permeability at the time of filling are indicated by ○, and those having no air permeability and the paper bag being damaged are indicated by ×.

[0031]

[Table 1]

Example 2 On one side of kraft paper, an acrylic resin emulsion was applied in a line of 30 mm width at an interval of 30 mm to form a line-like resin layer. As shown in FIG. Substrates arranged alternately were produced. 200m long using this substrate
m, a paper bag with a body width of 150 mm was produced.

The moisture content and the moisture permeability of this paper bag were measured in the same manner as in Example 1, and the air permeability at the time of filling with cement and the presence or absence of consolidation of the contents were observed. Table 1 shows the results.

Example 3 A base material and a paper bag were manufactured in the same manner as in Example 2 except that the width and the interval of the resin layer were changed to 50 mm, respectively.

The moisture content and the moisture permeability of this paper bag were measured in the same manner as in Example 1, and the air permeability at the time of filling with cement and the presence or absence of solidification of the contents were observed. Table 1 shows the results.

Examples 4, 5, and 6 Substrates were produced in the same manner as in Examples 1 to 3, and a paper bag was produced by laminating these substrates in two layers. The moisture content and the moisture permeability of this paper bag were measured in the same manner as in Example 1, and the air permeability at the time of filling with cement and the presence or absence of solidification of the contents were observed. Table 1 shows the results.

COMPARATIVE EXAMPLE 1 As for the current cement paper bag using a three-layered base material having a slit polyethylene film sandwiched between two stretched kraft papers as the base material, the moisture content and
The moisture permeability, air permeability, and consolidation of the contents were evaluated. Table 1 shows the results. The moisture permeability indicates the measured value of the glued bag, and the value in parentheses indicates the measured value of the sewing bag.

Comparative Examples 2 and 3 The same kraft paper as in Example 1 was provided without providing a resin layer.
As a substrate, single-layer and two-layer paper bags were manufactured. For these paper bags, the moisture content, moisture permeability,
The air permeability and the consolidation of the contents were evaluated. Table 1 shows the results.

Comparative Example 4 The same biodegradable resin film (polylactic acid-based polymer) as in Example 1 was laminated on the entire surface of one side of kraft paper, and had a thickness of 3
A 0 μm laminate layer was formed. A one-layer paper bag using this as a base material was produced. This paper bag was evaluated for moisture content, moisture permeability, air permeability, and consolidation of the contents in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 5 The same acrylic emulsion as in Example 2 was applied to the entire surface of the same kraft paper as in Example 1 to produce a one-layer paper bag using this as a base material. This paper bag was evaluated for moisture content, moisture permeability, air permeability, and consolidation of the contents in the same manner as in Example 1. Table 1 shows the results.

As is clear from the results shown in Table 1, the paper bag of each of the above examples had sufficient air permeability to allow air to escape when the contents were filled in both the single-layer and double-layer cases. On the other hand, when the resin was laminated or coated on the entire surface (Comparative Examples 4 and 5), it hardly passed air, indicating that it was not practical. In addition, the moisture permeability was improved as compared to the case of only kraft paper, and the same or better effect was obtained as the current product. In particular, it was shown that the two-layered material had a low moisture content of the contents and was suitable as a storage bag for a material solidified by moisture.

[0042]

According to the paper bag of the present invention, a resin layer such as a water-soluble resin or a biodegradable resin is partially formed on a kraft paper as a base material, and the resin layer and the resin layer are not formed. Are arranged alternately, it is possible to combine practical air permeability and low moisture permeability required especially for heavy bags for storing cement, grains, and the like. In addition, by using a water-soluble resin or a biodegradable resin as the resin constituting the resin layer, a recyclable paper bag can be provided without environmental pollution at the time of disposal.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view showing one embodiment of a base material used for a paper bag of the present invention.

FIG. 2 is a front view and an end sectional view showing a cement paper bag to which the present invention is applied.

FIGS. 3A to 3C are cross-sectional views each showing another embodiment of the base material used for the paper bag of the present invention, and FIG. 3D is a perspective view showing another embodiment of the base material.

FIGS. 4 (a) and (b) are diagrams showing different embodiments of the paper bag of the present invention, respectively.

[Explanation of symbols]

 11 ... base material 12 ... laminated part (resin layer) 13 ... non-laminated part 20 ... paper bag

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 3E064 AC01 BA01 BA21 BA60 BB03 BC20 EA30 FA06 4F100 AJ04A AK01B AK41B BA02 BA10A BA10B DA01 DC22B DG10A GB01 GB07 GB16 GB23 GB90 JA20B JB09B JC00B JD02 JD04 A82Y02 BE08 FA14 FA20 FA30 GA05 GA30

Claims (6)

[Claims] 1. A paper bag made of paper as a base material, wherein the base material includes a laminated portion in which a resin layer is laminated and a non-laminated portion in which the resin layer is not laminated on at least one surface of the paper. A paper bag characterized by being provided in a paper bag. 2. The paper bag according to claim 1, wherein the resin forming the resin layer is made of a biodegradable resin. 3. The paper bag according to claim 1, wherein the resin forming the resin layer is made of a water-soluble resin. 4. A ratio of the laminated portion to the base material,
The paper bag according to claim 1, wherein the paper bag has an area of 25 to 80% of the area of the base material. 5. The paper bag according to claim 1, wherein the laminated portions and the non-laminated portions are arranged alternately in a linear manner. 6. A multi-layer paper bag in which a plurality of base materials are stacked, wherein the stacked portions or the non-stacked portions are arranged so as not to overlap each other between the base materials overlapping each other. The paper bag according to claim 1.