JPH09150841A - Cereal bag and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost, by stretching the end of one film higher than the opening end of the other film in a cereal bag in which three sides of the superposed two films are closed and folding back the stretched end to the opening end side to form a sealing part for a string. SOLUTION: Two sheets of polyethylene film are superposed and respective faces 10a, 10b are sealed at three sides thereof and the bottom 12 is formed at one closed end and the opening 11 and a stretched end 18 are formed at the other end. When the opening 11 is formed, the opening side end of the rear side film 10b is stretched to the opening side longer than the opening side end 11a of the front side film 10a to form the stretched end 18. A sealing part 15 for a string to fix a binding string 14 and a clearance 16 are provided at the stretched end 18. In the sealing part 15 for the string, the stretched end 18 is folded back to the opening end side 11a. After the binding string 14 has been superposed so as to be enveloped, it is welded with heat to form this cereal bag.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain bag and a manufacturing method thereof, and more particularly to a grain bag made of a synthetic resin and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, there are the following grain bags for storing grains such as rice and wheat, for example, grain bags for storing 20 kg to 30 kg of grains.

For example, two paper sheets are closed on three sides to form a bag body having an opening on one side, and the width of the bag body along one open end of the paper sheet forming the opening. There is a grain bag with a paper tie that is longer than the length of the direction.

In this grain bag, after opening an opening and inserting an appropriate amount of grains such as rice and wheat into the bag, the binding string is wound around the bottom side of the bag for an appropriate number of times and then the binding string is wrapped. The opening is closed by tying together.

[0005]

However, the above-mentioned paper-made grain bag is expensive, and therefore, the cost is high when the grain bag is used to store or sell grains. was there.

Therefore, it is conceivable to manufacture a grain bag using a material cheaper than paper. However, for a producer or a trader who has traditionally been engaged in storing grains, when the grain bag is used. The grain containment procedures should not be changed.

The present invention has been made in view of the above problems, and it is a technical object to provide an inexpensive grain bag without changing the conventional grain storage operation.

[0008]

DISCLOSURE OF THE INVENTION The present invention is a grain product in which two synthetic resin films that are stacked are closed in three directions, and a bottom is formed at one end and an opening is formed at the other end. The bag has the following structure in order to solve the above-mentioned technical problems.

That is, the opening has an extended end in which the end of one film extends in the opening direction more than the end of the other film. The extended end portion is inverted and bent to the opening end side of the other film at a portion spaced from the opening end of the other film by a predetermined distance, and the binding string is included at the bent portion. It has a seal part for the string which is superposed on the. A gap is left between the string seal portion and the open end of the other film (corresponding to claim 1).

Each constituent element will be described below individually. (Outline of Bag) In the grain bag of the present invention, two laminated synthetic resin films are closed in three directions. This may be done in any manner provided that the opening is formed at one end and the bottom is formed at the other end. For example, one synthetic resin film may be folded in two and its both sides may be closed, or two synthetic resin films may be superposed and closed in three directions. ,
Alternatively, one of the tubular (tubular) films formed by the inflation method or the like may be closed and the other may be used as an opening.

When closing the film in one direction,
For example, it is preferable to weld the films to each other, but any method may be used as long as the contents can be closed in a state where the films can be closed when the films are closed.

(Extended end portion) The extended end portion serves as a base for attaching a binding string which will be described below, and a winding allowance when closing the opening portion of the grain bag of the present invention. It will be.

The extension end may have a separate film attached to one end of the open end of the bag-shaped film, and when the bag is formed, the films are superposed so that the extension end is formed. It may be formed by.

(Binding string) The binding string is for closing the opening of the grain bag. Any kind of material may be used for the binding string, but it is preferable to use the same material as the film in terms of improving convenience when recycling the grain bag of the present invention.

(String seal part) The string seal part is provided to mount the binding string on the extended end. This string seal part is formed by bending a part of the extending end part toward the open end part of the other film and folding it so as to enclose the binding string inside. Then, for example, the folded extending ends may be sealed to each other so that the binding string is simply inserted. Alternatively, the binding string may be fixed by sealing the binding string together with the extended end portions. However, for example, an adhesive may be applied to the inside of the string seal part to bond the tie string and the string seal part so that the tie string does not move.

(Gap) The gap is provided between the string seal portion and the open end of the other film. Providing this gap is preferable in that the opening portion is easily opened when the grain bag is used, and a winding margin is provided when the grain bag is wound and closed. The width of this gap is 5
100 mm and even 10-30 mm are suitable.

(Additional Constituent Elements of the Present Invention) The grain bag of the present invention is composed of the above-mentioned essential constituent elements, but can be established even when the constituent elements described below are added.

(Flap Section) The grain bag of the present invention may be provided with a flap section extending from the string seal section toward the opening end side and having a predetermined width so as to cover the opening section. (Corresponding to claim 2). In this case, the flap will stop the contents near the opening,
Even if the grain bag is arranged laterally, it is preferable that the stored grain is less likely to spill.

The width of the flap portion is at least the width of the gap, and is 30 to 150 mm, more preferably 50 to 100 mm. (Fold) The bottom may be provided with a fold having a V-shaped cross section formed by folding one end of the synthetic resin film inward (corresponding to claim 3). This is preferable because when the grain is put inside the grain bag, the bottom of the bag becomes flat and the bag is in a stable standing state.

At this time, if each of the corners on the bottom side of the grain bag is provided with a slanted line-shaped seal that draws the hypotenuse of an isosceles triangle whose two sides are approximately the same length as the width of each fold,
This is preferable because the width of the bottom is constant regardless of the amount of grains contained.

(Ventilation hole) It is preferable to provide a plurality of ventilation holes in the film along both sides of the grain bag because the state of the stored grain can be appropriately maintained (claim 4). Correspondence). A plurality of the ventilation holes may be formed along at least one of the opening end and the bottom end of the film (corresponding to claim 5). Further, each vent hole may be formed in a rectangular shape integrally with the film.

The ventilation holes may be provided in only one of the two films, or may be provided in both films. (Material of Grain Bag) The synthetic resin used as the material of the grain bag of the present invention will be described. Although any kind of synthetic resin may be used, polyethylene is usually used. In particular, an ethylene-α-olefin copolymer produced by copolymerizing ethylene with a small amount of an α-olefin having 4 or more carbon atoms using a metacelone-based olefin polymerization catalyst is preferable (corresponding to claim 6). This copolymer has a density of 0.90.
0 to 0.920 (g / cm ³ ), and the molecular weight distribution (Mw / Mn) measured by the GPC method is 1.5 to 3.5, so that it has high mechanical strength, no stickiness, and grain. Suitable for manufacturing bags.

In addition, the grain bag is required to have excellent impact resistance and tear resistance because it contains the polymer and is frequently moved. In that case,
Satisfy the required quality by film-forming a composition obtained by blending the above-mentioned ethylene-α-olefin copolymer with other polyethylene, for example, linear medium / high-density polyethylene, and high-pressure polyethylene, and making a bag. You can A particularly preferred polyethylene composition is exemplified below.

That is, (I) ethylene and an α-olefin having 4 or more carbon atoms, a melt flow rate (190 ° C.) of 0.1 to 1.0 g / 10 minutes, and a density of 0.900. ~ 0.918 g / cm ³ , GPC
Molecular weight distribution (Mw / Mn) determined by the method is 1.5 to
Linear low density polyethylene resin having 3.5: 40 to 70
Parts by weight and (II) density of 0.935 to 0.970 g / c
m ³ is a linear medium-density polyethylene resin: 1 to 55
Parts by weight, and (III) density of 0.915 to 0.924 g /
cm ³ high pressure low density polyethylene resin: 5 to 29
Parts by weight [total of components (I), (II) and (III) is 1
00 parts by weight], and the composition has (i) a melt flow rate (190 ° C.) of 0.5 to 2.0 g / 10 minutes, and (ii) a density of 0.9
18 to 0.935 g / cm ³ , and (iii) a polyethylene resin composition having a melt tension of 5 g or more (corresponding to claim 7).

In this case, since the grain bag has an appropriate strength, the grain bag can be made thinner than conventional polyethylene. A film molded from this polyethylene resin composition by an air-cooled inflation method has (i) a tensile Young's modulus of 4,000 kg / cm.
² or more, (ii) Dirt impact strength is 55 kg
When it is / cm or more, it is suitable for use as a grain bag (corresponding to claim 8).

Further, it is preferable that the film has a gloss of 50% or more, and as a grain bag, the film has a thickness of 30 to 200 μm.
Next, the polyethylene resin for bag for grain and the polyethylene resin film for bag for grain formed of the composition will be specifically described.

First, the components used in the polyethylene resin composition will be described. Linear low-density polyethylene resin (I) The linear low-density polyethylene resin (I) is a copolymer composed of ethylene and an α-olefin having 4 or more carbon atoms, preferably 4 to 20 carbon atoms.

Specific examples of the α-olefin include 1-
Examples include butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene.

The content of α-olefin in this copolymer is 1 to 10 mol%, preferably 1.5 to 7 mol%.
It is. Such linear low density polyethylene resin (I)
Is the melt flow rate (MFR: ASTM D 123
8, 190 ℃, load 2.16kg) 0.1-1.0g
/ 10 minutes, preferably 0.3 to 0.7 g / 10 minutes. When the linear low density polyethylene resin (I) having a melt flow rate in the above range is used, a polyethylene resin composition having excellent film formability by an air-cooled inflation method can be obtained. That is, a film having good resin extrudability during film formation, stable bubbles, and no rough skin can be obtained.

Further, linear low density polyethylene resin (I)
Has a density (ASTM D 1505) of 0.900-0.
918 g / cm ³ , preferably 0.900 to 0.915
g / cm ³ . When the linear low-density polyethylene resin (I) having a density within the above range is used, a polyethylene resin composition capable of providing a film having high strength and rigidity can be obtained.

Such a linear low density polyethylene resin (I) has a molecular weight distribution (Mw / M determined by GPC method).
n: Mw = weight average molecular weight, Mn = number average molecular weight)) is 1.5 to 3.5, preferably 1.8 to 3.0. When the linear low density polyethylene resin (I) having a narrow molecular weight distribution as described above is used, a polyethylene resin composition capable of providing a tough film having more excellent impact resistance can be obtained.

The linear low-density polyethylene resin (I) is 100 parts by weight of the linear low-density polyethylene resin (I), the linear medium / high-density polyethylene resin (II) and the high-pressure low-density polyethylene resin (III). 40 to 70 parts
It is used in an amount of 40 parts by weight, preferably 40 to 65 parts by weight, more preferably 45 to 60 parts by weight. When the linear low-density polyethylene resin (I) having the above characteristics is used in the above proportion, a polyethylene resin composition capable of providing a tough film having excellent impact resistance can be obtained.

The linear low-density polyethylene resin (I) as described above is disclosed in JP-A-6-9724 and JP-A-6-13.
No. 6195, JP-A-6-136196, JP-A-6-207057, etc., in the presence of a so-called metallocene-based olefin polymerization catalyst containing a metallocene catalyst component, ethylene and carbon atoms of 4 or more Α
-Olefin with a density of the resulting copolymer of 0.90
It can be produced by copolymerizing so as to be 0 to 0.918 g / cm ³ .

Such a metallocene-based olefin polymerization catalyst is usually a metallocene catalyst component (a) comprising a transition metal compound of Group IVB of the periodic table having at least one ligand having a cyclopentadienyl skeleton, And an organoaluminum oxy compound catalyst component (b) and, if necessary, other components in combination.

Linear Medium / High Density Polyethylene Resin (II) The linear medium / high density polyethylene resin (II) used in the present invention is a copolymer of ethylene homopolymer or ethylene and the same α-olefin as described above. It is a polymer.

The α-olefin content in this ethylene / α-olefin copolymer is 10 mol% or less, preferably 0.2 to 7 mol%. This linear medium / high-density polyethylene resin (II) has a density (ASTM D 150
5) is 0.935 to 0.970 g / cm ³ , preferably 0.937 to 0.968 g / cm ³ . When the linear medium / high-density polyethylene resin (II) having a density within the above range is used, a polyethylene resin composition having high rigidity and strength and capable of providing a strong film can be obtained.

Such linear medium / high density polyethylene resin (II) has a melt flow rate (MFR: ASTM).
D 1238, 190 ° C., load 2.16 kg) is usually 2.0 to 60 g / 10 min, preferably 2.5 to 50 g / min.
10 minutes, more preferably 2.8 to 40 g / 10 minutes. When the linear medium / high-density polyethylene resin (II) having a melt flow rate in the above range is used, it is possible to provide a film having high resin extrudability and high strength during film formation by the air-cooled inflation method. A polyethylene resin composition is obtained.

The linear medium / high density polyethylene resin (II) has a molecular weight distribution (Mw / Mn) determined by GPC of usually 2.0 to 5.0, preferably 2.
0 to 4.5. When a linear medium / high density polyethylene resin (II) having a molecular weight distribution within the above range is used,
A polyethylene resin composition having high rigidity and strength and capable of providing a strong film is obtained.

Linear medium / high density polyethylene resin (II)
Is 1 to 100 parts by weight of the total amount of the linear low-density polyethylene resin (I), the linear medium / high-density polyethylene resin (II) and the high-pressure low-density polyethylene resin (III).
It is used in a proportion of 55 parts by weight, preferably 10 to 50 parts by weight, more preferably 20 to 45 parts by weight. Linear medium / high density polyethylene resin (I
When I) is used in the above proportion, a polyethylene resin composition capable of providing a strong film can be obtained.

The linear medium / high density polyethylene resin (II) as described above can be produced by a medium pressure method such as a low pressure method using a Ziegler-Natta catalyst, a low pressure method using a metallocene catalyst, or a Phillips method.

High Pressure Low Density Polyethylene Resin (III) High Pressure Low Density Polyethylene Resin (II
I) is an ethylene homopolymer or an ethylene / vinyl acetate copolymer.

The content of vinyl acetate in the ethylene / vinyl acetate copolymer is 2 to 10 mol%, preferably 2
８8 mol%. The high-pressure low-density polyethylene resin (III) used in the present invention has a density (ASTM D 150
5) is 0.915 to 0.924 g / cm ³ , preferably 0.918 to 0.924 g / cm ³ . High-pressure method low-density polyethylene resin (II
When I) is used, a polyethylene resin composition capable of providing a film having high rigidity and strength can be obtained.

The high-pressure low-density polyethylene resin has a melt tension of 5 g or more, preferably 7 g or more. The melt tension is measured by a melt tension tester manufactured by Toyo Seiki Seisaku-sho, Ltd. The measurement conditions are as follows.

(Measurement Conditions) Nozzle used: L = 8,000 mm, D = 2.095 mm Measurement temperature: 190 ° C. Resin extrusion speed: 15 mm / min Take-up speed: 2 m / min High-pressure low-density polyethylene resin used in the present invention (II
I) is the melt flow rate (MFR: ASTM D 1
238, 190 ℃, load 2.16kg) is usually 0.1
~ 2.0 g / 10 minutes, preferably 0.1-1.5 g / 1
0 minutes, more preferably 0.2 to 1.5 g / 10 minutes. When the high-pressure low-density polyethylene resin (III) having a melt flow rate in the above range is used, the resin extrudability during film formation by the air-cooled inflation method is excellent, the bubble stability is excellent, and the thickness is uniform. A polyethylene resin composition that can provide a film is obtained.

High-pressure low-density polyethylene resin (III)
Is 5 to 100 parts by weight of the total amount of the linear low density polyethylene resin (I), the linear medium / high density polyethylene resin (II) and the high pressure method low density polyethylene resin (III).
It is used in a proportion of 29 parts by weight, preferably 5 to 25 parts by weight, more preferably 7 to 25 parts by weight. A polyethylene resin composition capable of providing a film excellent in low temperature characteristics such as low temperature drop bag strength characteristics and transparency when the high pressure method low density polyethylene resin (III) having the above characteristics is used in the above proportions Is obtained.

The high-pressure low-density polyethylene resin (III) as described above is, for example, 1,000 to 2,000 atm.
It can be produced by a so-called high pressure method in which radical polymerization is carried out at 200 to 300 ° C.

Polyethylene resin composition for bag for grain The polyethylene resin composition for bag for grain which can be used in the present invention includes the above-mentioned linear low density polyethylene resin (I), linear medium / high density polyethylene resin (II ) And high-pressure method low-density polyethylene resin (III) in the above-described proportions by adopting a dry blending method using a Henschel mixer or the like, a melt blending method using an extruder or the like, or a blending method using these methods in combination. Obtained by mixing.

The polyethylene resin composition for bags for grains obtained as described above has a melt flow rate (ASTM).
D 1238, 190 ° C, load 2.16kg) is 0.5
~ 2.0 g / 10 minutes, preferably 0.5-1.8 g / 1
It is 0 minutes, more preferably 0.5 to 1.5 g / 10 minutes. The density (ASTM D 1505) is 0.918.
-0.935 g / cm < ³ >, preferably 0.920-0.
935 g / cm ³ , more preferably 0.922-0.
It is 935 g / cm ³ , and the melt tension is 5 g or more, preferably 5.5 to 15 g. The measuring method of the melt tension is the same as the measuring method already described above.

Polyethylene resin film for bag for grain The polyethylene resin film used for molding the bag for grain is
It is a film obtained by molding polyethylene or the above-mentioned polyethylene composition by, for example, an inflation method.

As the grain bag according to the present invention, the film used has a tensile Young's modulus of 4,000 kg / cm ^2.
Above, it is desirable that the dirt impact strength is 55 kg / cm or more. The gloss (glossiness) of this film is 50% or more. The thickness of the film is 30 to 200 μm.

Further, since this film is excellent in low-temperature characteristics such as low-temperature drop bag strength characteristics that can be sufficiently used for grain bags even in cold regions below freezing, the film thickness can be made thin. High speed molding is possible.

According to the grain bag of the present invention, first, the opening provided at the other end of the grain bag is opened, and an appropriate amount of grain is put through this opening. Next, the extended end portion is wound around the opening end side of the other film by an appropriate number of turns. Finally, the openings are closed by tying both sides of the tie string together. Therefore, the method of using the grain bag is the same as the method of using the conventional paper grain bag, and is changed to the working practice of the producer or trader who is working using the conventional grain bag. Never come.

Since the grain bag of the present invention uses a synthetic resin bag, it can be manufactured at a lower cost than the conventional paper grain bag. It should be noted that the above respective constituent elements can be arbitrarily combined as much as possible.

(Method for Manufacturing Grain Bag) Next, the method for manufacturing a grain bag of the present invention is configured as follows. That is, of the two films, an extension portion forming step of providing an extension end portion in which the end portion of one film extends in the opening direction more than the opening end portion of the other film, and in the extension end portion. , A string supplying step of supplying a tie string along the width direction of the bag body to a portion at a predetermined distance from the opening end of the other film, and including the tie string at the extended end. As such, a folding step of reversing and bending to the opening end side of the other film, the extending end portion that is reversed and bent, the binding string is included, and the opening end portion of the other film. A sealing step is provided in which a gap is left between the two and the two are overlapped and welded (corresponding to claim 9).

Here, two grains of synthetic resin film, which are superposed on each other, are closed in three directions, and a bottom portion is formed at one end and an opening portion is formed at the other end. The film may be formed by sealing three sides of the film, or may be formed by folding one film into two and sealing in two directions, but a film formed in a tubular shape in advance such as an inflation film may be formed. When used, the manufacturing process is easy because the two directions are closed from the beginning.

Further, there may be provided a bottom folding step of folding the bottom portion inward to form a fold portion having a V-shaped cross section. Moreover, you may provide the perforation process which provides a some ventilation hole along both sides of the film of the said other end.

Further, a second perforating step of forming a plurality of ventilation holes along at least one of the open end and the bottom side end of the other film may be provided.

[0058]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment A preferred embodiment of the grain bag of the present invention will be described in more detail with reference to the drawings.

<Outline of Grain Bag> In the grain bag 10, two polyethylene films are superposed, one of the films is a back film 10b of the bag, and the other is a front film 10a of the bag. ing. And each side 10
The three sides a and 10b are closed by sealing or the like, the bottom portion 12 is provided at one closed end, and the opening portion 11 and the extended end portion 18 are provided at the other end.

<Bottom> As shown in FIG. 2, the bottom 12 is provided with pleats 13a, 13b forming a V-shaped cross section. Each of these pleats 13a, 13b is
One end of the film forming each of the front side film 10a and the back side film 10b of the grain bag 10 is further folded inward in the opening direction. Each fold 1
3a and 13b are provided so as to have the same length in the width direction.

The folds 13a and the front side film 10a, and the folds 13b and the back side film 10b are heat-welded by applying oblique line seals 19 as shown in FIG.

Each of the slanted line seals 19 is used for the grain bag 10
Is formed so as to form a hypotenuse of a substantially isosceles triangle having two corners of the bottom portion 12 of each of the two sides, and the other two sides of the isosceles triangle have the length l in the width direction of the pleats 13a and 13b. The length is almost equal to. In addition, each of the slanted line-shaped seals 19 is a so-called "H-shaped seal" because it is applied to each of the front-side film 10a and the back-side film 10b of the grain bag 10 at two places. Is.

As described above, the folds 13a are formed on the bottom portion 12,
By providing 13b, when the grain bag 10 stores grains, the bottom portion 12 becomes a flat surface as shown in FIG. Therefore, the grain bag 10 is in a stable standing state. Further, since the diagonal seal 19 is applied to the bottom portion 12, the bottom portion 12 is expanded by the length of the fold portions 13a and 13b in the width direction, and the shape of the bottom portion 12 is stabilized.

<Extended End> Opening 11 of bag 10 for grain
Is provided by heat-welding both sides of two polyethylene films that are superposed. This opening 1
1 is provided, the backside film 10b of the grain bag 10
Of the front side film 10 of the grain bag 10
a so as to extend in the opening direction from the opening end 11a of a,
An extended end portion 18 is provided by superposing two films. That is, in FIGS. 1 and 2, the portion surrounded by the dotted line is the extended end portion 18.

The extending end portion 18 is provided with a string seal portion 15 for fixing the binding string 14 and a gap 16. <String Sealing Part> The end of the extending end 18 in the extending direction is inverted and bent toward the opening end 11a side at a portion spaced from the opening end 11a of the front film 10a by a predetermined distance. After the binding string 14 is overlapped so as to include the binding string 14 at the bent portion, it is heat-welded to form the string seal portion 15.

The binding string 14 is longer than the length of the grain bag 10 in the width direction, and both ends thereof are in a state of protruding in the width direction of the grain bag 10. Although the binding string 14 may be made of any material, polyethylene, which is the same material as the grain bag 10, is used here.

The string seal part 15 is provided so that a gap 16 is formed between the string seal part 15 and the opening end 11a of the front film 10a of the grain bag 10. The gap 16 serves as a winding margin and is 5 to 100 mm, which is the range of the present invention, and is 15 mm in this embodiment.

<Ventilation Hole> As shown in FIG. 1, the front film 10a of the grain bag 10 is provided with a plurality of ventilation holes 17 along both sides of the grain bag 10 by punching.
However, the ventilation holes 17 may be provided in the back film 10b of the grain bag 10.

The ventilation holes 17 are provided in the grain bag 1
When 0 is used, the ventilation hole 17 is not closed by the winding of the opening 11, so that the ventilation hole 17 is positioned below the planned winding allowance.

Each vent hole 17 is sized so that the grains contained therein cannot pass through. However, the number and size of the ventilation holes 17 can be appropriately changed according to the type and size of the grain to be stored. Further, the ventilation hole 17 is
It may be provided only on both sides of the grain bag 10, or may be provided only in the width direction of the grain bag 10. These ventilation holes 17 make it possible to properly maintain the state of the grain stored in the grain bag 10.

<Material of Grain Bag> The material of the grain bag will be described below with reference to examples. The physical properties of the film in the examples were measured by the following methods. (1) Young's modulus A tensile test was performed in the MD and TD directions of the film using a constant crosshead moving speed type tensile tester (manufactured by Instron Co., Ltd.).
The Young's modulus of the film in the D direction was calculated, and the average value of the obtained values was defined as Young's modulus (E). (2) Dirt impact strength A value obtained by dividing the value measured according to the ASTM D 1709 B method by the film thickness was taken as the dirt impact strength. (3) Gloss The gloss of the film was measured at an incident angle of 60 degrees according to ASTM D523. (4) Seal strength After sealing the film with a New Long HS-33D Top Sealer [trade name, manufactured by Tester Sangyo Co., Ltd.], a crosshead constant moving speed type tensile tester (manufactured by Instron)
, And the breaking strength was measured, and this breaking strength was defined as the seal strength.

[0072]

Example 1 Linear low density polyethylene resin (LLDP
E) 50 parts by weight, linear polyethylene resin (LPE) 35
Parts by weight and high pressure low density polyethylene resin (HPLD
15 parts by weight of PE) were mixed with a Henschel mixer and pelletized with an extruder.

The resin components used here have the following physical properties. (1) Using a metallocene olefin polymerization catalyst composed of linear low-density polyethylene bis (n.butylcyclopentadienyl) zirconium dichloride and methylaluminoxane, a copolymer of ethylene and 1-hexene is prepared. Obtained. The copolymer had a 1-hexene content of 5.3 mol%, a density of 0.905 g / cm ³ , a melt flow rate of 0.5 g / 10 min, and an Mw / Mn of 2.1. (2) Linear polyethylene Using a Ziegler catalyst composed of titanium tetrachloride and diethylaluminum chloride, a copolymer of ethylene and 4-methyl-1-pentene was obtained. 4-methyl-
1-Pentene content is 4.0 mol%, density 0.910 g /
cm ³ , melt flow rate 2.0 g / 10 min, M
It was a copolymer having a w / Mn of 3.5. (3) High-pressure method low-density polyethylene Commercially available polyethylene having a density of 0.921 (g / cm ³ ) and a melt flow rate of 0.35 (g / 10 min) was used.

The characteristics of the polyethylene resin composition obtained as described above were as follows. Melt flow rate: 0.85 g / 10 min Density: 0.926 g / cm ³ Melt tension: 6.4 g Further, the obtained composition was molded by an air cooling inflation method under the following molding conditions to obtain a wall thickness of 150 μm, Width 4
A 50 mm film was successfully produced.

[Molding Conditions] Molding machine: 90 mmφ inflation molding machine manufactured by Modern Machinery Co., Ltd. (high-pressure method low-density polyethylene resin specification) Screw: L / D = 28, C / R = 2.8, da with intermediate mixing Is: 200 mmφ (diameter), 2.5 mm (lip width) Air ring: 2 gap type Molding temperature: 190 ° C. Take-off speed: 20 m / min Physical properties of the film obtained as described above were measured and I got the result.

Young's modulus: 4.4 × 10 ³ kg / cm ² Dart impact strength: 71 kg / cm Gloss: 74% Seal strength: 5700 g / 15 mm (How to use a grain bag) It is used as follows. First, the opening 11 provided at the other end of the grain bag 10 is opened, and grains such as rice and wheat, which are the contents, are put into the opening 11. When a proper amount of grain is put in, the open end 1 of the grain bag front side film 10a is made so that the string seal portion 15 of the extended end portion 18 serves as a core.
Wind a suitable number of turns to the 1a side. Finally, both sides of the binding string 14 are tied together to close the binding opening 11.

According to the grain bag 10 described above, the method of using the grain bag 10 is the same as the method of using the conventional paper grain bag, and the conventional grain bag is used for the work. It does not change the working practices of producers or traders. Further, since the gap 16 is provided between the string seal portion 15 and the opening end portion 11a, the opening portion 11 is easier to open than a paper grain bag.

Further, since the grain bag of the present invention uses a synthetic resin bag, it can be manufactured at a lower cost than conventional paper grain bags. This makes it possible to keep the price of grains traded in the grain bag low as long as the prices of the grains themselves are the same.

<Second Embodiment> Next, a second embodiment of the grain bag of the present invention will be described with reference to FIG. The second embodiment of the grain bag is a mode in which the grain bag 10 shown in FIG. 1 is provided with a flap portion 21 that covers the opening 11.

<Flap Part> As shown in FIG. 5, the flap part 21 extends from the string seal part 15 toward the opening end side and is provided so as to cover the opening part 11. Specifically, the extended end portion 18 is formed so as to extend longer than the extended end portion 18 of the grain bag 10 shown in FIG. 1, and the extended end portion 18 is inverted to the opening end side. Even after the string seal portion 15 is provided and the binding string 14 is fixed, as shown in FIG. 6, the extended end portion 18 having a predetermined width is left, and the extended end portion 18 of the remaining portion is left. Is the flap portion 21. However, the flap portion 21 may be one in which a rectangular synthetic resin film having a predetermined width is attached along the end portion on the opening end 11a side of the string seal portion 15.

The width of the flap portion 21 in the embodiment was about 80 mm. The grain bag 10 according to the second embodiment has the same configuration as the grain bag 10 according to the first embodiment except for the flap portion 21.
Therefore, the description of each part other than the flap part 21 is omitted because it is the same as the description in the first embodiment.

The effect of the grain bag 10 according to the second embodiment of the present invention is almost the same as that of the grain bag 10 according to the first embodiment. When the bag 10 is used, the flap portion 21 is wound so as to cover the opening portion 11 and the opening portion 11 is closed. For this reason, compared to the first embodiment of the grain bag 10, the stored grain is less likely to spill outside.
Therefore, an appropriate grain storage state can be maintained regardless of the arrangement and orientation of the grain bag 10 storing grains, as compared to the first embodiment.

<Third Embodiment> Next, a third embodiment will be described with reference to the drawings. The third embodiment is an embodiment of the method for manufacturing a grain bag of the present invention.

Here, a method for forming a bag from a polyethylene film produced by the inflation extrusion molding method and producing a grain bag from the bag will be described.

Here, the same polyethylene composition as that used in Example 1 was used as the material for the grain bag. <Polyethylene Film Molding Line> First, the inflation film molding line by the inflation extrusion molding method will be described.

The polyethylene film, which is the material for the grain bag, is manufactured by the inflation extrusion molding device 24 shown in FIG. The inflation extrusion molding device 24 includes, for example, a hopper 25, an extruder 26, a die 27, an air ring (cooler) 33, and a tower 28.
And an inner plate 29 and a pinch roll 30. Any type of inflation extrusion molding device 24 may be used.

In such an inflation extrusion molding device 24, when the material of the polyethylene resin composition for bags for grain is put into the hopper 25, the material of the polyethylene resin composition is melted by the extruder 26, and is appropriately melted. It is pushed out of the die 27 by pressure. At this time, a tubular film (referred to as a bubble) having a circular cross section is extruded from the die 27 and rises, and at the same time, air is sent into the bubble from the die 27 to inflate the bubble.

At the same time, the air ring 33 blows air to the outer surface of the bubble inside the tower 28 to cool the bubble. The bubbles cooled by the air ring 33 are gradually transformed into a tubular film having a flat cross section by a guide plate 29 provided on the upper part of the tower 27, and wrinkles and the like are removed by the pinch rolls 30. It is conveyed to the bag forming line 32 by the conveying means.

However, this flat tubular inflation film is not shown in the winder (winder).
The film may be once wound into a roll by means of, and then conveyed to a bag forming line 32, which is provided separately from the blown film manufacturing line, and supplied to the bag forming line 32.

<Bag Body Forming Line> Next, the bag body forming line 32 will be described. This bag forming line 32
Is provided with a slitting step, a fold forming step, a cutting step, a welding step, and a perforating step on the blown film conveyance line.

<Cleaving Process> A cutter 35 shown in FIG. 9 is installed above the position where the slitting process is performed in the bag forming line 32. This cutter 35
The blade is installed in the direction opposite to the transport direction of the film, and is designed to cut a predetermined position of the transported film in the transport direction.

In the present invention, this is the extension portion provided with the extension end portion 18 in which the end portion of one of the two films extends in the opening direction more than the opening end portion 11a of the other film. It becomes a forming process.

<Step of Forming Folds> At the position where the step of forming the folds 13 is performed, as shown in FIG. 11, the positioning plates 37a and 37b are parallel to each other above and below the carrying line in a substantially horizontal direction. It is installed in such a way that the film conveyed between them passes.

The folding plate 36 is inserted into the positioning plate 37a, 37b at a substantially intermediate position with the tip portion inserted.
Is installed. The folding plate 36 is formed obliquely on the side opposite to the film transport direction when viewed from above, so that when the film passes between the positioning plates 37a and 37b, the folded portion of the film abuts. Has been done. This is the bottom folding step of the present invention in which the bottom portion is folded inward to form a fold portion having a V-shaped cross section.

<Cutting Step> A cutter (not shown) is arranged near the position where the cutting step is performed, and cuts the conveyed film in a direction orthogonal to the conveying direction. At this time, the film is cut so as to have an appropriate width direction length as the grain bag 10.

<Welding Step> A heat plate (not shown) is installed above the position where the welding step is performed.
It is installed so that it can move up and down with respect to the conveyed film. When the film cut at the welding position is conveyed, the heat plate descends with respect to the film and heat-bonds both sides of the film.

At the welding step position, as shown in FIG. 15, the sealing irons 39, 39 for oblique sealing are
It is installed so that it can move up and down. The two sealing irons 39, 39 for the oblique line-shaped sealing are arranged above and below the film conveying line so as to form two cross-sections, and four in total.

Also, a rectangular base plate 3 for the oblique line seal
8 is installed in a state in which it can be moved back and forth in a direction substantially orthogonal to the transport direction of the film, and advances to the film in accordance with the rise and fall of the sealing irons 39, 39 for the diagonal line seal, It is adapted to be inserted into the bottom portion 12 side of the grain bag 10.

<Punching Step> Above the position where the punching step is performed, a punch (not shown) is installed so as to be vertically movable with respect to the conveyed film. The punch (not shown) descends when the film is conveyed to the punching position and penetrates the film to make a hole.
At this time, the punch is configured to form a rectangular ventilation hole 17 integrally with the film.

[0100] The bag body thus formed further includes a grain bag 1 which further includes a binding string supplying step which is a string supplying step, a folding back step which is a bending step, and a sealing step.
After 0 manufacturing steps, the grain bag 10 of the present invention is completed.

<Binding string supplying step> Above the position where the binding string supplying step is performed, a binding string feeding device (not shown) is provided, and when the film is conveyed, the binding string 14 is set at the set feeding position. To supply. This is the string supplying step of supplying a binding string along the width direction of the bag body to a portion of the extended end portion, which is spaced a predetermined distance from the opening end of the other film, in the present invention.

<Bending Process> The folding process is performed at the same position as the binding string supplying position. A fold device (not shown) is provided at the tie string supply position, and the portion to be the extended end portion 18 of the conveyed film is used for grain while enclosing the tie string 14 supplied from the tie string supply device. The bag 10 is adapted to be bent toward the open end side.

<Sealing Process> The sealing process is also performed at the same position as the binding string supply position, like the bending process. Above the tie string supply position, a heat plate (not shown)
It is provided so that it can be raised and lowered with respect to the conveyed film. This heat plate is arranged so as to perform a linear seal in the transport direction, and the end portion 15a on the open end 11a side of the string seal portion 15 is heat-welded by setting.

At the same time, a cutter for cutting the binding string 14 is designed to cut the binding string 14 at an appropriate length. There is no strict distinction between the bag forming line and the grain bag manufacturing process, and a manufacturing line for realizing the grain bag manufacturing method of the present invention is integrally formed. Further, the order of each step is merely an example, and the order of each step can be appropriately changed as long as possible.

A method of manufacturing the grain bag 10 from the flat tubular inflation film obtained by the inflation extrusion molding device 24 described above will be described.
The flat tubular film formed by the inflation extrusion molding device 24 is conveyed to the bag forming line 32 by a conveying means (not shown). At this time, the tubular film is conveyed in the direction of the arrow in FIG. 8 in the state shown in FIG.

The tube-shaped film in the conveyed state abuts the cutter 35 arranged above the film at the cut open position. As a result, the upper side of the film is cut open in the transport direction as shown in FIG. 9, and the sheet-shaped film is folded in two as shown in FIG. Thereby, the extended end portion 18 is formed.

The bi-folded sheet-shaped film is further conveyed, and at the position where the folds 13 are formed, as shown in FIG.
Pass between 37b. At this time, the folded-back portion of the sheet-shaped film comes into contact with the folding plate 36 having the leading end portion inserted substantially at the intermediate position between the positioning plates 37a and 37b. As a result, as shown in FIG. 12, the folds 13a, 13b having a V-shaped cross section are formed by being folded inward.

The film on which the folds 13a and 13b are formed is further conveyed by the conveying means. Then, at the position where the cutting step is performed, the cutter (not shown) cuts in the direction of the broken line shown in FIG. 12, that is, in the direction orthogonal to the transport direction. At this time, the film is cut so as to have an appropriate width direction length as the grain bag 10.

When the cut film is conveyed to a position where the welding process is performed, a heat plate (not shown) descends from above, and both sides in the conveying direction of the film, that is,
The hatched portion in FIG. 14 is heat-welded. This heat plate rises and returns to the initial position when the both sides of the film are sufficiently heat-welded. As a result, the front side film 10a, the back side film 10b, and the opening 1 of the grain bag 10 are formed.
A bag body is formed having 1, a bottom portion 12, and pleats 13a and 13b.

At the welding step position, at the same time as the heat plate is raised, as shown in FIG. 15, the oblique sealing base plate 38 arranged on the bottom 12 side of the film on the transfer line transfers the bag body. Advance in the direction orthogonal to the direction. The base plate 38 is inserted into a bag-shaped portion having the pleats 13a and 13b on the bottom 12 side of the film as the inner surface.

Then, the sealing irons 39, 39 for the oblique line sealing are respectively lowered and raised from the upper side and the lower side to perform the oblique line seal 19 on the front side film 10a and the back side film 10b. At this time, the diagonal seal 19
The front side film 10a and the back side film 10b are each provided at two places so that a C-shape is drawn. Further, the slanted line seal 19 has two corners on the bottom 12 side of the bag body, and each of these two sides draws the hypotenuse of an isosceles triangle equal to the length l in the width direction of the pleats 13a, 13b. Is applied to.

When the front-side film 10a and the back-side film 10b are thus provided with the slanted line seals 19,
The sealing irons 39, 39 move up and down to return to the initial position, and the base plate 38 retracts to return to the initial position. Then, the bag body is conveyed to the punching position.

When the bag body is conveyed to the punching position, a punch (not shown) descends from above and the film 10 on the front side of the bag body.
A ventilation hole 17 is formed through a and 10b. A plurality of the ventilation holes 17 are provided in the front film 10a and the back film 10b of the bag body so as to integrally form a rectangular shape. Then, when the punch rises and returns to the initial position, the bag body is conveyed to the binding string supply position.

When the bag is conveyed to the binding string supplying position, the binding string supplying device (not shown) supplies the binding string 14 to the set supplying position. That is, the binding string 14 is supplied to a predetermined position of the extended end portion 18 along the width direction of the bag body.

Then, a folding device (not shown) is operated, and the extended end portion 18 of the conveyed bag body is fixed to the supplied binding string 14
While enclosing it, the bag body is inverted and bent toward the opening end 11a side. When the extending end portion 18 is bent, a heat plate (not shown) descends with respect to the bag body and heat-welds the set seal position 15a. As a result, the string seal portion 15 is formed on the extended end portion 18, and the string seal portion 1 is formed.
A predetermined gap 16 is formed between the opening 5 and the opening end 11a. At the same time, the cutter for cutting the binding string 14 cuts the binding string 14 into an appropriate length. In addition, when the binding string supply device supplies the binding string 14 having an appropriate length,
The step of cutting the binding string 14 can be omitted.

According to the third embodiment, since the grain bag 10 can be manufactured by using the polyethylene resin composition which is a synthetic resin, as compared with the conventional paper grain bag,
The manufacturing cost can be suppressed. Further, by using the polyethylene resin composition under the above-mentioned conditions, the strength is improved as compared with the conventional polyethylene, so that the grain bag 10 can be made thin.

The grain bag 10 manufactured by this manufacturing method has the same effects as those described in the first embodiment. When the flap portion 21 is provided as in the second embodiment, the extended end portion 18 is lengthened, leaving the flap portion 21 as shown in FIGS. 20 and 21, and extending from the string seal portion 15 to the flap portion. The part 21 may be formed so as to be left.

[0118]

EFFECTS OF THE INVENTION According to the grain bag of the present invention and the method for producing the same, a grain bag that is less expensive than a paper grain bag is provided without impairing the working practice of the conventional paper grain bag. It becomes possible.

If a flap is provided on the grain bag,
The stored grain can be prevented from spilling from the opening, and can be reliably stored. In addition, if the ventilation holes are provided, it becomes possible to more appropriately maintain the state of the contained grain.

Further, when the polyethylene resin composition according to the present invention is used as the synthetic resin, the strength can be improved and the grain bag can be formed thinner than the conventional polyethylene bag. .

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a grain bag.

FIG. 2 is a sectional view showing a first embodiment of a grain bag.

FIG. 3 is a perspective view partially showing a bottom portion of the grain bag shown in FIG.

4 is a perspective view partially showing a state of the bottom portion when the contents are stored in the grain bag shown in FIG.

FIG. 5 is a front view partially showing a second embodiment of the grain bag.

6 is a sectional view partially showing the grain bag shown in FIG.

FIG. 7 is a front view showing an inflation extrusion molding device.

FIG. 8 is a perspective view showing the film in a conveyed state.

FIG. 9 is a perspective view showing a state of a slitting process.

FIG. 10 is a perspective view showing the film in a state of being cut open in the transport direction.

FIG. 11 is a perspective view showing a state where the film passes through the fold forming process.

FIG. 12 is a perspective view showing the film after a fold forming process.

FIG. 13 is a perspective view showing a film cut in the transport direction in a cutting step.

FIG. 14 is a perspective view showing a film which is welded on both sides to form a bag in a welding step.

FIG. 15 is a perspective view showing a state in which a diagonal seal is applied to the bottom side in the welding process.

FIG. 16 is a perspective view showing a film of a bag body in which ventilation holes are formed in a front film and a back film in a punching step.

FIG. 17 is a perspective view showing a state in which the binding string is supplied to the extended end portion in the binding string supplying step.

FIG. 18 is a perspective view showing a state where the extending end portion is folded back by the folding device.

FIG. 19 is a perspective view showing a state in which the string seal portion is formed and the binding string is cut in the sealing step.

FIG. 20 is a perspective view showing a state where the extending end portion is folded back by the folding device.

FIG. 21 is a perspective view showing a state in which a string seal portion is formed and a binding string is cut in a sealing step.

[Explanation of symbols]

 10 Grain Bag 11 Opening 11a Opening End 12 Bottom 13 Folding 14 Binding String 15 String Sealing 16 Gap 17 Vent Hole 18 Extended End 19 Oblique Line Seal 21 Flap 24 Inflation Extruder 25 Hopper 26 Extruder 27 die 28 tower 29 stabilizer 30 pinch roll 32 bag forming line 35 cutter 36 folding plate 37 positioning plate 38 base plate 39 seal iron

Claims (9)

[Claims] 1. A grain bag in which two laminated synthetic resin films are closed in three directions and a bottom portion is formed at one end and an opening portion is formed at the other end. Has an extending end portion in which the end portion of one film extends in the opening direction more than the opening end portion of the other film, and the extending end portion is more predetermined than the opening end portion of the other film. In a spaced portion, the film is inverted and bent toward the opening end side of the other film, and has a string seal portion sealed in a state of being overlapped so as to include a binding string in the bent part, A grain bag, wherein a gap is left between the string seal portion and the opening end portion of the other film. 2. The grain according to claim 1, further comprising a flap portion that extends from the string seal portion to the opening end side and has a predetermined width so as to cover the opening portion. Bag. 3. The grain according to claim 1, wherein the bottom portion is provided with a fold portion having a V-shaped cross section formed by folding one end of the synthetic resin film inward. Bag. 4. The grain bag of claim 1, wherein the film has a plurality of vent holes along both sides. 5. The grain bag according to claim 1, wherein the film has a plurality of ventilation holes along at least one of the opening end portion and the bottom end portion. 6. The synthetic resin constituting the film is an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 4 or more carbon atoms in the presence of a metachron olefin polymerization catalyst. The grain bag of claim 1, wherein the bag is for grains. 7. The synthetic resin constituting the film is
(I) consisting of ethylene and an α-olefin having 4 or more carbon atoms, and having a melt flow rate (190 ° C.) of 0.1 to 1.0 g /
10 minutes, the density is 0.900 to 0.918 g / cm ³ , and the molecular weight distribution (Mw / Mn) determined by the GPC method is 1.
5 to 3.5 linear low density polyethylene resin: 40 to
70 parts by weight and (II) density of 0.935 to 0.970 g
/ Cm ³ linear medium / high density polyethylene resin: 1 to
55 parts by weight and (III) density of 0.915 to 0.924
g / cm ³ high-pressure low-density polyethylene resin: 5
29 parts by weight [the total of components (I), (II) and (III) is 100 parts by weight], and the composition comprises (i) a melt flow rate (190 ° C.).
Is 0.5 to 2.0 g / 10 minutes, and (ii) the density is 0.
It is 918-0.935 g / cm < ³ >, and (iii) melt tension is 5 g or more, The bag for grains of Claim 1 characterized by the above-mentioned. 8. The film according to claim 1, wherein (i) the tensile Young's modulus is 4,000 kg / cm ² or more, and (ii) the dart impact strength is 55 kg / cm or more. Grain bag. 9. A grain bag in which two laminated synthetic resin films are closed in three directions, a bottom portion is formed at one end, and an opening portion is formed at the other end. In, the one end of the film has an extended end extending in the opening direction than the open end of the other film, the extended end is a predetermined than the open end of the other film. In a region with a space of, the film is inverted and bent to the opening end side of the other film, and at the bent region, a string seal portion is sealed in a state of overlapping so as to include a binding string, A method for producing a grain bag, characterized in that a gap is left between the string seal portion and the opening end portion of the other film, wherein one of the two films is used. The edge of the film is more open than the edge of the other film An extension portion forming step of providing an extension end portion that extends in a direction, in the extension end portion, at a site at a predetermined distance from the opening end of the other film, in the width direction of the bag body. A string supplying step of supplying a tie string along, a bending step of inverting and bending the extended end portion toward the opening end side of the other film so as to include the tie string, and the inverting and bending step. A sealing step in which the extended end portion is overlapped and welded in a state in which the binding string is included and a gap is left between the extended end portion and the opening end portion of the other film. A method for manufacturing a grain bag.