JPH06345102A - Multiple packing paper bag - Google Patents

Abstract

PURPOSE:To prevent a multiple packing bag from dewing by making use of a high humidity-adjusting ability of the kraft paper layer in the high relative humidity range thereof, by arranging a non-bleached kraft paper layer carrying at least silicon dioxide in the constituting layers of the multiple packing paper. CONSTITUTION:A bag 1 is constituted of the inner layer 2, the intermediate layer 3, and the outer layer 4 for instance and also constituted as a triple-layer bag having folds 5. The inner layer 2 is made of a tubeless-tube of low density polyethylene film and the intermediate layer 3 is made of non-bleached kraft paper carrying silicon dioxide and the outer layer 4 is made of regular non- bleached kraft paper respectively. The inner layer tube 4 is heat-sealed at the bottom 1 and a crape tape 7 folded into two is attached to the bottom and after that, the whole layers are sewed 8 by a machine. On the other hand, the contents 9 are charged in the bag 1 and the similar heat-sealing 6 and machine-sewing 8 are applied on the opening 1b. In this way, the multiple packing paper bag can be prevented from dewing by making use of the humidityadjusting ability of the intermediate layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy wrapping paper bag, and more particularly to an improved heavy wrapping paper bag which is effective in preventing dew condensation.

[0002]

2. Description of the Related Art Conventionally, heavy packaging bags have been used for packaging many chemical industrial products. Among them, it is usual to use a synthetic resin film as the innermost layer for the packaging of products that do not like contact with moisture and kraft paper. After filling and sealing the contents of these heavy wrapping paper bags, they are usually stacked on a pallet with 5 bags in 1 stage and 8 stages (40 bags in total).
It was very common to stack and store pallets.

[0003]

However, the heavy wrapping paper bag stored in such a state, especially the one having the innermost layer made of the synthetic resin film, has a large difference in the outside air temperature in a day. There was a problem that dew condensation is likely to occur over the entire load during the autumn and high rainy season. When dew condensation occurs in this way, as shown in FIGS. 5 and 6, the weight of the cargo is loaded at the clearance X mark of the bag 1 from the bottom of the bags stacked on the pallet 10 to the third rank from the bottom. Causes the kraft paper layer underneath to break, and even if the innermost layer is composed of a moisture-resistant polyethylene film, it cannot withstand the heavy load of the stacked cargo, and the film also breaks and the contents spill out. In the worst case, the cargo piled up on top of it lost its balance and could lead to a collapse accident. The present invention has been made in view of such circumstances, and an object thereof is to provide a heavy wrapping paper bag that is effective in preventing dew condensation.

[0004]

[Means for Solving the Problems] In the papermaking process, attempts have been made to improve the properties of paper products by adding an alkali metal salt (silicate) of silicic acid such as sodium silicate to a raw material. . For example, US Pat.
1,562 discloses a technique of applying a silicate for the purpose of sizing paper, and US Pat. No. 2,399,98.
No. 1 discloses a technique of impregnating paper with silicate for the purpose of improving wet strength. Further, JP-A-4-18193 and JP-A-4-57964 disclose pulp containing silicon dioxide, and The specification attached to the application of Japanese Patent Application No. 3-285256 discloses a method of supporting silicon dioxide on paper efficiently and strongly.

The inventor of the present invention is studying the use of unbleached kraft paper produced by using a pulp supporting silicon dioxide produced according to the method described in JP-A-4-18193. In the process, it was conceived of a heavy wrapping paper bag using this paper, which is effective in preventing dew condensation. That is, in order to solve the above-mentioned problems, the heavy wrapping paper bag of the present invention is characterized by comprising a constituent layer including an unbleached kraft paper layer supporting silicon dioxide.

The present invention can be applied to any type of heavy wrapping paper bag shown in International Standard ISO 6591/1 and Japanese Utility Model Publication No. 44-15582. Incidentally, since the heavy wrapping paper bag whose innermost layer is composed of a synthetic resin film is liable to dew, the effect of the present invention is remarkable, and in that case, the unbleached kraft paper layer supporting the silicon dioxide is a synthetic resin film layer. When placed adjacent to the outside, the dew condensation prevention effect is remarkable.

[0007]

In the heavy wrapping paper bag of the present invention, the kraft paper layer supporting silicon dioxide has a high humidity adjusting ability in the high relative humidity region (see FIG. 4) to prevent the dew condensation.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to this. FIG. 1 is a plan view of a heavy wrapping paper bag according to an embodiment of the present invention, showing a state in which a part of the paper layer is cut out for convenience of explanation. FIG. 2 is a cross-sectional view of the heavy wrapping paper bag of FIG. 1 taken along the line AA ′ in FIG. 1, and FIG. 3 is (FIG. 1 and) the heavy wrapping paper bag of FIG. 2 is filled with contents (low-density polyethylene pellets). FIG. 6 is a cross-sectional view when the mouth end is closed. In the drawings, reference numeral 1 is a bag, 1a is a bottom end, 1b is a mouth end, 2 is an inner layer (or innermost layer), 3 is an intermediate layer, 4 is an outer layer (or outermost layer), 5 is a fold, and 6 is The heat seal portion, 7 is a crepe tape, 8 is a sewing machine sewing portion, and 9 is a content.

As shown in FIGS. 1 and 2, the bag body 1 of the present embodiment.
Is a three-layer bag having inner layer 2, intermediate layer 3 and outer layer 4 and pleats 5. Inner layer 2 is a seamless tube of a low density polyethylene film having a thickness of 0.04 mm, and intermediate layer 3 is silicon dioxide. 80g / m ² unbleached kraft paper,
The outer layer 4 is a commercially available 76 g / m ² regular unbleached kraft paper. Seamless inner layer 2 of low density polyethylene
The tube is heat-sealed 6 and sealed at the bottom end 1a. Then, the folded crepe tape 7 is brought into contact with the end edge of the bottom end portion 1a, and the entire layer is sewn (8) and closed at a portion closer to the end edge than the heat seal portion 6 of the inner layer 2 from above. .

After filling the bag 1 with the contents 9 as described above, the inner layer 2 is heat-sealed (6) and sealed at the mouth end portion 1b in the same manner as the bottom end portion 1a, and the end portion of the mouth end portion 1b is sealed. The folded crepe tape is brought into contact with the edge, and the portion closer to the edge than the heat seal portion 6 is sewn from above by the sewing machine (8).
Then close it.

In the present example, the unbleached kraft paper supporting silicon dioxide used as the intermediate layer 3 of the bag 1 was beaten softwood unbleached kraft pulp (NUKP) to a freeness of 300 ml to give No. 3. After immersing in a sodium silicate (molar ratio 3.15, Be <Baume> = 42) solution for 1 hour, deliquoring and defibrating, react with carbon dioxide gas under normal pressure to make silicon dioxide inside and outside the fiber. A pulp supporting 32% by weight of silicon dioxide obtained by dissociating the pulp in water and then washing it with water to remove silicon dioxide adhering to the outside of the fiber and sodium carbonate as a reaction by-product. The content of silicon dioxide after papermaking was 28% by weight.

In order to confirm the dew condensation prevention effect of the heavy wrapping paper bag of this embodiment, a low density is used for the heavy wrapping paper bag of the above structure having the same dimensions as the currently used product (bag width 440 mm, fold width 52.5 mm, bag length 670 mm). A 25 kg polyethylene pellet was filled and a mouth end was closed by the above method to prepare a test product.
Also, as with the current product, both the outer and middle layers are made of regular unbleached kraft paper with a weight of 76 g / m ² , and the inner layer is 0.04 mm.
A thin tube of thick low density polyethylene film made into a seamless tube of the same size and type as above, filled with 25 kg of low density polyethylene pellets, and the mouth end was closed in the same way as the above test product. I prepared the goods.

These test products and comparative products were pre-cooled at -5 ° C. for 3 hours and then at 30 ° C. and 90% RH (absolute humidity 27.
It was moved to a high temperature and high humidity condition of ³ g / m ³ ) and the state of dew condensation generation was observed for 3 hours. After these test products and comparative products were transferred to a high temperature and high humidity chamber, initial dew condensation occurred as if a slight mist was blown on the surface of the exterior paper, but it was soon absorbed by the paper and the paper itself became damp. Most of the full-scale dew condensation occurred on the surface of the inner layer (low density polyethylene film). This is because after the surface of the outer layer paper is warmed up to the temperature in the chamber, the humid air is cooled to a temperature below the dew point and condenses at a position (the surface of the inner layer) closest to the content that is still sufficiently cooled.

The comparative product was transferred to a high temperature and high humidity chamber.
After a lapse of time, the regular kraft paper in the outer and middle layers could not absorb all the condensed water, and the surface of the outer layer was wet with excess water. On the other hand, the test product is probably because the kraft paper supporting the silicon dioxide of the intermediate layer 3 has absorbed a relatively large amount of water.
The outer layer 4 regular kraft paper only felt damp.

In addition to the above-mentioned test product and the comparative product, the outer layer was loaded with silicon dioxide in the same manner as the test product.
m ² of unbleached kraft paper, and commercialized 76g /
unbleached kraft paper of regular m ² arranged to obtain a seamless tube of low-density polyethylene film having a thickness of 0.04mm and an inner layer, the test article and the comparative article of the same dimensions,
The same type of heavy wrapping paper bag was tested under exactly the same conditions as described above, but in this case, the kraft paper carrying silicon dioxide in the outer layer absorbs dew condensation water that the regular kraft paper in the middle layer could not absorb, and The marks appeared as relatively large spots.

[0016]

In the heavy wrapping paper bag of the present invention, dew condensation can be prevented by the high humidity control ability of the kraft paper layer supporting silicon dioxide in the high relative humidity region.
As described in detail above, according to the present invention, it is possible to provide a heavy wrapping paper bag that is effective in preventing dew condensation.

[Brief description of drawings]

FIG. 1 is a plan view of a heavy-weight paper bag according to an embodiment of the present invention.

2 is a cross-sectional view of the heavy wrapping paper bag of FIG. 1 taken along the line AA ′ of FIG.

FIG. 3 is a cross-sectional view of the heavy wrapping paper bag of FIG. 2 in which the contents are filled and the mouth end is closed.

FIG. 4 is a chart showing the relationship between humidity and moisture absorption rate of paper (humidity adjusting ability of paper).

FIG. 5 is a side view showing a state in which conventional heavy-duty wrapping paper bags filled with contents are palletized.

6 is a plan view showing the state of the bottom of the pallet-stacked heavy wrapping paper bag shown in FIG.

[Explanation of symbols]

1 ... Bag, 1a ... Bottom end, 1b ... Mouth end,
2 ... inner layer (or innermost layer), 3 ... intermediate layer, 4 ...
・ Outer layer (or outermost layer), 5 ... folds, 6 ... heat seal part, 7 ... crepe tape, 8 ... sewing part, 9 ... contents, 10 ... pallet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Iwasaki 3-6 Sotokanda, Chiyoda-ku, Tokyo Inside Oji Seizo Co., Ltd. (72) Inc. Toshiro Oki 3-6 Sotokanda, Chiyoda-ku, Tokyo No. 4 Oji Bag Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A heavy-weight wrapping paper bag comprising constituent layers including an unbleached kraft paper layer supporting silicon dioxide.