JPH10100270A - Grain bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grain bag improved in appearance and capable of withstanding a falling test by forming a tubular film forming two side end parts from a specific polyethylene resin and specifying the heat sealing strength of a formed bottom part and attaching a binding string to the upper end part of either one of the front and rear parts of the tubular film. SOLUTION: A grain bag 1 consists of two side end parts 2a, 2b formed by inwardly gussetting the peripheries of two opposed places of a tubular film, the front and rear surface parts 3a, 3b composed of the other opposed peripheries, the bottom part 4 formed by closing one of the opening parts of the tubular films and the opening part 5 opposed to the bottom part 4. This tubular film is composed of a linear low density polyethylene resin prepared by using a metallocene catalyst or a compsn. thereof. The bottom part 4 is heat-sealed and this heat seal strength is set to 30N/15mm or more. The binding string 6 is attached to the upper end part of either one of the front and rear surface parts 3a, 3b.

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 more particularly, to a grain bag made of polyethylene resin.

[0002]

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

For example, there is a grain bag having two polyethylene resin films closed on three sides by heat sealing and having an opening on one side. However, such a bag for grain contains 30 kg of grain therein, closes the opening, and then drops the bag from a height of 1.5 m (flat drop).
In some cases, the bag is broken from the heat-sealed portion of the grain bag, and the heat-sealing strength is not always sufficient. The inventors of the present application have studied the heat sealing strength of the side end of the cereal bag as described above, and as a result, at least 40 N / 15
It was found that a heat seal strength of mm was required. In addition, the grain bag does not have a good appearance because of the heat seal portions on three sides.

[0004] Therefore, there is a demand for a grain bag having a good appearance and sufficient strength to withstand a drop test.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a grain bag having a good appearance and sufficient strength to withstand a drop test.

[0006]

SUMMARY OF THE INVENTION A grain bag according to the present invention has a front surface comprising two side ends formed by gusset-folding two opposing peripheral surfaces of a tubular film inward, and another opposing peripheral surface. And a back portion, a bottom formed by closing one of the openings of the tubular film, and a bag for cereal consisting of an opening facing the bottom, wherein the tubular film uses a metallocene catalyst. Wherein the bottom is heat-sealed, the heat-sealing strength is 30 N / 15 mm or more, and any one of the front part and the back part is prepared. A binding string is attached to one upper end.

[0007] The linear low density polyethylene resin (A)
Is composed of ethylene and an α-olefin having 4 or more carbon atoms, and has a melt flow rate (ASTM D 1238, 190 ° C,
(Load 2.16 kg) is 0.1 to 1.0 g / 10 min, the density is 0.900 to 0.918 g / cm ³ , and the molecular weight distribution (Mw / Mn) determined by GPC is 1.5 to 1.0 g / cm ³ . 3.
It is preferably 5.

The linear low density polyethylene resin (A) composition comprises (A) ethylene and an α-olefin having 4 or more carbon atoms, and has a melt flow rate (AS
TM D 1238, 190 ° C, load 2.16kg) 0.1 ~ 1.0g /
10 minutes, density 0.900 to 0.918 g / cm
³ and the molecular weight distribution (Mw / M
n) a linear low-density polyethylene resin having a density of 1.5 to 3.5: 40 to 70 parts by weight, and (B) a density of 0.935 to
0.970 g / cm ³ linear medium / high density polyethylene resin: 1 to 55 parts by weight, and (C) density 0.915 to
A high-pressure low-density polyethylene resin having a composition of 0.924 g / cm ³ : 5 to 29 parts by weight [the total of components (A), (B) and (C) is 100 parts by weight], And the composition has a melt flow rate (ASTM
D 1238, 190 ° C, load 2.16kg) 0.5-2.0g / 1
0 minutes and a density of 0.918 to 0.935 g / cm ³
And the melt tension is preferably 5 g or more.

[0009] The grain bag according to the present invention is preferably provided with a plurality of ventilation holes. In addition, the grain bag according to the present invention is preferably subjected to a surface treatment such as corona discharge from the viewpoint of printability.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The grain bag according to the present invention will be specifically described with reference to the drawings. FIG. 1 is a perspective view showing an example of a grain bag according to the present invention.

[0011] The grain bag 1 according to the present invention has two side end portions 2a and 2b formed by gusset-folding two opposing peripheral surfaces of a tubular film inward, and the other opposing peripheral surfaces. And a bottom portion 4 formed by closing one of the openings of the tubular film.
And an opening 5 opposed to the bottom 4.

This tubular film is made of a linear low-density polyethylene resin (A) prepared using a metallocene-based catalyst or a composition thereof (described later). For example, a conventionally known air-cooled or water-cooled inflation molding method is used. Can be obtained by

The side end portions 2a and 2b are gusset-folded inside a tubular film to form folds having a V-shaped cross section. The above-mentioned conventional grain bag is not good in appearance because the two side ends are heat-sealed, but the grain bag 1 according to the present invention has the side ends 2a, 2b formed by heat sealing. The appearance is good because it is not formed. In addition, since the grain bag 1 according to the present invention spreads the bag 1 so that the V-shaped cross-section of the side end portions 2a and 2b spreads and becomes flat, printing on the side end portions 2a and 2b is possible. For example, a product identification mark or the like can be printed on the side ends 2a and 2b. In order to improve the printability of the surface of the polyethylene resin film at the side end portion of the grain bag, it is preferable to apply a conventionally employed surface treatment method for the polyethylene film, for example, a corona discharge treatment, at least to a portion to be printed.

The bottom 4 is heat-sealed and has a heat-sealing strength of 30 N / 15 mm or more, preferably 3 N / 15 mm.
5 N / 15 mm or more. The heat seal strength is 30N
If the length is 15 mm or more, the grain is stored in the bag and
After wrapping and tying both ends of this bag, this bag (contents 30kg)
Does not break even when a drop test (flat drop) is performed from a height of 1.5 m.

As shown in FIG. 2, the rear portion 3b may have an extended end 8 extending in the opening direction from the open end 7 of the front portion 3a. With such a grain bag having the extended end 8, it is easy to close the opening of the bag by accommodating the grain, winding the tying string 6 around the back part 3 b by an appropriate number of turns, and tying the strap. That is, in the cereal bag 1 as shown in FIG. 1, when the grain is stored in the bag with the front part 3a to which the tying string 6 is attached, the back part 3b is lowered by the weight of the cereal and the opening of the sack is tied with the tying string. It is difficult to close the part. On the other hand, in the grain bag 1 having the extended end 8 as shown in FIG.
Even if the weight of the cereal drops, the back end 3b has the extended end 8, so that the operation of closing the opening of the bag with the tying string is easy.

A tie string 6 is attached to one of the upper end of the front portion 3a and the rear portion 3b. For example, as shown in FIG.
It is attached so as to be included between the upper end of the front part 3a. The binding string 6 does not have to be fixed to the upper end of the string sealing portion 10 or the front portion 3a, and may be fixed so that the binding string 6 does not move. For example, an adhesive may be applied to the inside of the string seal portion 10 to bond the tie string 6 and the string seal portion 10 so that the tie string 6 does not move.

As shown in FIG. 4, a front part 3a and two side ends 2a, 2a at the upper end of the bag-like film.
b is cut out by a predetermined size to form a front part 3
The cut-away portion a may be bent so as to include the tying string 6, and the bent film and the film of the front portion 3a may be welded.

As shown in FIGS. 1 and 2, a grain bag 1 according to the present invention has a front portion 3a along side edges 2a and 2b.
And / or a plurality of ventilation holes 9 can be provided in the back surface 3b by punching. The number, size, and position of the ventilation holes 9 can be appropriately changed according to the type and size of the grain to be stored.

Next, the linear low-density polyethylene resin (A) for forming a tubular film used in the present invention and its composition will be described. Linear low density polyethylene resin (A) Linear low density polyethylene resin (A) used in the present invention
Is ethylene and has 4 or more carbon atoms, preferably 4 to
And a copolymer comprising 20 α-olefins.

As the α-olefin, specifically, 1-olefin
Butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene and the like. The α-olefin content in this copolymer is
It is 1 to 10 mol%, preferably 1.5 to 7 mol%.

Such a linear low-density polyethylene resin (A) has a melt flow rate (MFR: ASTM D
1238, 190 ° C, load 2.16 kg)
1.0 g / 10 min, preferably 0.3 to 0.7 g / 10
Minutes. When the linear low-density polyethylene resin (A) having a melt flow rate in the above range is used, a polyethylene resin composition excellent in film formability by an air-cooled inflation method can be obtained. That is, the extrudability of the resin during film formation is good, the bubbles are stable,
A film without rough skin is obtained.

The linear low-density polyethylene resin (A)
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 (A) having a density in the above range is used, a polyethylene resin composition capable of providing a film having high strength and rigidity is obtained.

The linear low-density polyethylene resin (A) has a molecular weight distribution (Mw / M
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 (A) having a molecular weight distribution in the narrow range as described above is used, a polyethylene resin composition capable of providing a tough film having more excellent impact resistance is obtained.

In the present invention, the linear low density polyethylene resin (A) can be used alone or as a composition thereof. In the linear low-density polyethylene resin (A) composition, the linear low-density polyethylene resin (A) includes a linear low-density polyethylene resin (A), a linear medium / high-density polyethylene resin (B), and a high-pressure low-density resin. 40 to 70 parts by weight, preferably 40 to 65 parts by weight, based on 100 parts by weight of the total amount of the polyethylene resin (C),
More preferably, it is used in a proportion of 45 to 60 parts by weight. When the linear low-density polyethylene resin (A) having the above properties is used in the above ratio, a polyethylene resin composition capable of providing a tough film excellent in impact resistance is obtained.

The linear low density polyethylene resin (A) 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
-An olefin and the resulting copolymer has a density 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 generally comprises 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 organic aluminum oxy compound catalyst component (b), if necessary, a particulate carrier (c), an organic aluminum compound catalyst component (d), and an ionized ionic compound catalyst component (e).

The metallocene catalyst component (a) preferably used in the present invention is a transition metal compound of Group IVB of the periodic table having at least one ligand having a cyclopentadienyl skeleton. Examples of such a transition metal compound include a transition metal compound represented by the following general formula [I].

ML ¹ _x ... [I] In the formula, x is the valence of the transition metal atom M. M is a transition metal atom selected from Group IVB of the periodic table, and specifically, zirconium, titanium, and hafnium. Among them, zirconium is preferred.

L ¹ is a ligand that coordinates to the transition metal atom M, and at least one of these ligands L ¹
Is a ligand having a cyclopentadienyl skeleton.
As the ligand L ¹ having a cyclopentadienyl skeleton coordinated to the transition metal atom M as described above, specifically,
Cyclopentadienyl group, methylcyclopentadienyl group, dimethylcyclopentadienyl group, trimethylcyclopentadienyl group, tetramethylcyclopentadienyl group, pentamethylcyclopentadienyl group, methylethylcyclopentadienyl group And an alkyl-substituted cyclopentadienyl group such as hexylcyclopentadienyl group, or an indenyl group, a 4,5,6,7-tetrahydroindenyl group or a fluorenyl group. These groups are
It may be substituted with a halogen atom, a trialkylsilyl group or the like.

When the compound represented by the above general formula [I] contains two or more groups having a cyclopentadienyl skeleton, two of the groups having a cyclopentadienyl skeleton are connected to each other by ethylene, propylene or the like. An alkylene group,
It may be bonded through a substituted alkylene group such as isopropylidene diphenylmethylene or the like, or a silylene group or a substituted silylene group such as a dimethylsilylene group, a diphenylsilylene group or a methylphenylsilylene group.

The ligand L ¹ other than the ligand having a cyclopentadienyl skeleton is a hydrocarbon group having 1 to 12 carbon atoms; an alkoxy group such as a methoxy group; an aryloxy group such as a phenoxy group; a trimethylsilyl group; A trialkylsilyl group such as a triphenylsilyl group; SO ₃ R (R is a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent such as halogen), a halogen atom or a hydrogen atom.

As the organoaluminum oxy compound catalyst component (b), aluminoxane is preferably used. Specifically, methylaluminoxane, ethylaluminoxane, methylethylaluminoxane having a repeating unit represented by the formula -Al (R) O-, wherein R is an alkyl group, is usually about 3 to 50. Are used.

Such an aluminoxane can be prepared by a conventionally known production method. The fine-particle carrier (c) used as necessary in the preparation of the catalyst for olefin polymerization is an inorganic or organic compound and has a particle size of usually about 10 to 300 µm, preferably 20 to 2 µm.
It is a granular or particulate solid of 00 μm.

As the inorganic carrier, a porous oxide is preferable. Specifically, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ ,
TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, SnO ₂
Or a mixture thereof.

Examples of the organoaluminum compound catalyst component (d) optionally used in the preparation of the olefin polymerization catalyst include trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, and alkylaluminum dihalide. Can be exemplified.

Examples of the ionized ionic compound catalyst component (e) include triphenylboron, MgCl ₂ , Al ₂ O ₃ , and S described in US Pat. No. 5,321,106.
Lewis acids such as iO ₂ —Al ₂ O ₃ are exemplified.

The linear low-density polyethylene resin (A) used in the present invention comprises the metallocene catalyst component (a) and the organoaluminum oxy compound catalyst component (b) as described above, and if necessary, a particulate carrier (c). ), In the presence of an olefin polymerization catalyst containing an organoaluminum compound catalyst component (d) and an ionized ionic compound catalyst component (e), in a gas phase, or in a slurry or solution liquid phase, under various conditions. And an α-olefin having 4 or more carbon atoms.

Linear Medium / High Density Polyethylene Resin (B) The linear medium / high density polyethylene resin (B) used in the present invention is an ethylene homopolymer or an ethylene / α-olefin copolymer.

As the α-olefin constituting the ethylene / α-olefin copolymer, the above-mentioned α-olefin having 3 to 20 carbon atoms, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4 -Methyl-1-pentene and 1-octene are preferred.

The α-olefin content in the ethylene / α-olefin copolymer is 10 mol% or less, preferably 0.2 to 7 mol%. The linear medium / high density polyethylene resin (B) used in the present invention has a density (AS)
TMD 1505) is 0.935 to 0.970 g / cm
³ , preferably 0.937 to 0.968 g / cm ³ . By using the linear medium / high density polyethylene resin (B) having a density in the above range, a polyethylene resin composition having high rigidity and strength and capable of providing a strong film can be obtained.

Such a linear medium / high density polyethylene resin (B) 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 (B) having a melt flow rate in the above range is used, a resin having good extrudability at the time of film formation by air cooling inflation and having high strength can be provided. A polyethylene resin composition is obtained.

Further, such a linear medium / high density polyethylene resin (B) has a molecular weight distribution (Mw / Mn) determined by the GPC method of usually 2.0 to 5.0, preferably 2.
0 to 4.5. When a linear medium / high density polyethylene resin (B) having a molecular weight distribution in the above range is used,
Thus, a polyethylene resin composition having high rigidity and strength and capable of providing a strong film can be obtained.

In the present invention, the linear medium / high density polyethylene resin (B) includes the linear low density polyethylene resin (A), the linear medium / high density polyethylene resin (B), and the high pressure method low density polyethylene resin (B). 1 to 55 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of the total amount of C)
Parts by weight, more preferably 20 to 45 parts by weight. When the linear medium / high density polyethylene resin (B) having the above characteristics is used at the above ratio,
A polyethylene resin composition capable of providing a firm film is obtained.

The linear medium / high density polyethylene resin (B) 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, and a Phillips method.

High-pressure low-density polyethylene resin (C) The high-pressure low-density polyethylene resin (C) used in the present invention is an ethylene homopolymer or an ethylene / vinyl acetate copolymer.

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

Such a high-pressure low-density polyethylene resin has a melt tension (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-off speed: 2 m / min High-pressure low-density polyethylene resin used in the present invention (C) is a melt flow rate (MFR: ASTM D)
1238, 190 ° C, load 2.16 kg) is usually 0.1
To 2.0 g / 10 min, preferably 0.1 to 1.5 g / 1
0 minutes, more preferably 0.2 to 1.5 g / 10 minutes. When a high-pressure low-density polyethylene resin (C) having a melt flow rate in the above range is used, the resin extrudability during film formation by air-cooling inflation is good, bubble stability is excellent, and thickness is uniform. A polyethylene resin composition capable of providing a film is obtained.

In the present invention, the high-pressure low-density polyethylene resin (C) includes a linear low-density polyethylene resin (A), a linear medium / high-density polyethylene resin (B), and a high-pressure low-density polyethylene resin (C). Is used in an amount of 5 to 29 parts by weight, preferably 5 to 25 parts by weight, and more preferably 7 to 25 parts by weight, based on 100 parts by weight of the total amount. When the high-pressure method low-density polyethylene resin (C) having the above-mentioned properties is used in the above-mentioned ratio, a polyethylene resin composition capable of providing a film having excellent low-temperature properties such as low-temperature dropping strength properties and transparency. Is obtained.

A polyethylene tree for forming a tubular film
Fat Composition The polyethylene resin composition used in the present invention includes the linear low density polyethylene resin (A), the linear medium / high density polyethylene resin (B) and the high pressure method low density polyethylene resin (C) described above. It can be obtained by mixing at a ratio using 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 combining these methods.

The polyethylene resin composition obtained as described above has a melt flow rate (ASTM D123).
8, 190 ° C, load 2.16 kg) 0.5 to 2.0 g
/ 10 minutes, preferably 0.5 to 1.8 g / 10 minutes, and more preferably 0.5 to 1.5 g / 10 minutes. Also,
Density (ASTM D 1505) 0.918 to 0.93
5 g / cm ³ , preferably 0.920 to 0.935 g /
cm ³ , more preferably 0.922 to 0.935 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.

Tubular Film The tubular film used in the present invention is a film formed from the above-mentioned linear low-density polyethylene resin (A) or a composition thereof by an inflation method, preferably an air-cooled inflation method. .

The tubular film obtained as described above usually has a tensile Young's modulus of 4,000 kg / cm.
² or more, and the dirt impact strength is 55 kg / cm
That is all. Also, the gloss (gloss) of this film
Is 50% or more.

The thickness of the tubular film used in the present invention is 30 to 200 μm. Method for Producing Grain Bag The above-described grain bag according to the present invention is produced, for example, through the following steps.

That is, the grain bag according to the present invention comprises a step (1) of forming a tubular film from a linear low-density polyethylene resin (A) or a composition thereof by inflation molding; A step (2) of forming two side end portions by gusset-folding the peripheral surfaces of the portions, a step (3) of cutting the gusset-folded tubular film, and one of the openings of the tubular film. A step (4) of forming a bottom by closing by heat sealing, a step (5) of attaching a tie string to an upper end of one of the front part and the back part, and a step (5) of the front part and the back part along the side end. It is manufactured through the step (6) of perforating a film.

[0056]

The grain bag according to the present invention has good appearance and sufficient strength to withstand a drop test.

Further, since the grain bag according to the present invention is formed by gusset folding on both side ends, it can be compactly stored horizontally before filling the grain.

Further, in the grain bag according to the present invention, for example, a product identification mark can be printed not only on the front and back film surfaces but also on the side film surfaces. Product identification mark printed on the film surface of the side end, if using the grain bag according to the present invention,
Even when a plurality of cereal bags containing cereals are stacked flat, they can be distinguished from other commodities.

[0059]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The measurements of the physical properties and the like of the films and bags in the examples and comparative examples were performed 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). [Test conditions] Sample: JIS K6781 Atmospheric temperature: 23 ° C Pulling speed: 500 mm / min Chart speed: 200 mm / min

The Young's modulus of the film in the MD and TD directions was calculated from the chart obtained in the above test by the following equation, and the average of the obtained values was defined as the Young's modulus (E). E ₀ = R ₀ (L ₀ / A) [where E ₀ is the Young's modulus in each direction, R ₀ is the initial gradient, L ₀ is the distance between the chucks, and A is the minimum area during sample preparation. Shown respectively. This R ₀ was calculated by the following equation. R ₀ = F ₁ / L ₁ [where F ₁ represents a load at an arbitrary point on the initial tangent line, and L ₁ represents an elongation corresponding to F ₁ on the tangent line. ]

(2) Dart Impact Strength The value obtained by dividing the value measured according to the ASTM D 1709 B method by the thickness of the film was defined as the dart impact strength. (3) Gloss The gloss of the film was measured at an incident angle of 60 degrees according to ASTM D523.

(4) Heat Seal Strength After sealing the film with New Long HS-33D Top Sealer (trade name, manufactured by Tester Sangyo Co., Ltd.), a constant crosshead moving speed tensile tester (manufactured by Instron) )
, And the breaking strength was measured, and this breaking strength was defined as the seal strength.

[0064]

Example 1 First, a linear low-density polyethylene resin prepared using a metallocene catalyst [ethylene / 1-hexene copolymer, ethylene content: 2.6 mol%, MFR (ASTM D
1238, 190 ° C, load 2.16 kg): 1.0 g / 10 min, density: 0.930 g / cm ³ , molecular weight distribution (Mw / Mn) determined by GPC method: 2.5], and air-cooled inflation molding. Under the following molding conditions, the thickness is 150 μm,
A tubular film having an outer circumference of 940 mm was formed. [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, Dice with intermediate mixing: 200 mmφ (diameter), 2.5 mm (lip width) Air ring: 2 gap type Molding temperature: 190 ° C. Take-off speed: 20 m / min The Young's modulus, dart impact strength and gloss of the film obtained as described above are described above. The following results were obtained.

Young's modulus: 5000 kg / cm ² Dart impact strength: 90 kg / cm Gross: 75% Next, the two opposing peripheral surfaces of the tubular film were gusseted 70 mm inward and cut into predetermined dimensions. . The cut film had a width of 370 mm and a length of 910 mm in a planar state. Many such cut films were produced.

Next, one of the openings of the cut film was heat-sealed at a temperature of 180 ° C. with a width of 5 mm, and the heat seal strength was 30 N / 15 mm, 40 N / 15 mm and 5 N.
One hundred bag-like films of 0 N / 15 mm were produced.

Each of these bag-like films was attached in the width direction of the bag as a binding string of a 10 mm-wide film made of the above-mentioned linear low-density polyethylene resin 1000 mm above the bottom of the bag.

In the bag obtained in this way, rice 30 k
g and the opening was closed with a lace.
The bag was flattened from a height of 5 m, and the state of the bag was visually observed. The results are shown in Table 1.

[0069]

Comparative Example 1 Two 150 μm-thick rectangular films made of the linear low-density polyethylene resin used in Example 1 were overlaid, the longitudinal end of the film was heat-sealed, and the film was further opened. Was heat-sealed in the width direction to produce a bag-shaped film. This bag has a width of 470 mm and a length of 910 mm in a planar state.
Met.

The above heat seal is 180 ° C. with a width of 5 mm.
Heat sealing at a temperature of 20 N /
15mm, 30N / 15mm, 40N / 15mm and 50N / 15mm
Each of 100 bag-shaped films was produced.

Each of these bag-like films was attached in the width direction of the bag as a binding string of a 10 mm-wide film made of the above-mentioned linear low-density polyethylene resin 1000 mm above the bottom of the bag.

In the bag thus obtained, 30 kg of rice
g and the opening was closed with a lace.
The bag was dropped from a height of 5 m, and the state of the bag was visually observed.

Table 1 shows the results.

[0074]

Comparative Example 2 The procedure of Example 1 was repeated, except that the heat seal strength was changed to 20 N / 15 mm.
100 bags with a tying string were produced.

The 100 bags obtained were flattened out in the same manner as in Example 1, and the state of the bags was visually observed.
The results are shown in Table 1.

[0076]

[Table 1]

[0077]

Example 2 The heat seal strength produced in Example 1 was 3
In the same manner as in Example 1, 100 bags the same as a bag with a tying strap of 0 N / 15 mm were produced. The film thickness forming the bag is 15
0 μm.

In the bag obtained in this way, rice 30 k
g and the opening was closed with a lace.
The leveling was repeated 10 times from a height of 5 m, and each time the state of the bag was visually observed.

Table 2 shows the results.

[0080]

Comparative Example 3 The procedure of Example 2 was repeated, except that the linear low-density polyethylene resin used in Example 2 was replaced by a high-pressure low-density polyethylene resin having the following properties. One hundred bags with tying cords were produced, and flattened and repeated as in Example 2. The film thickness forming the bag is 150 μm.

<High pressure method low density polyethylene resin> MFR (ASTM D 1238, 190 ° C, load 2.16 kg): 0.3 g
Density: 0.922 g / cm ³ Molecular weight distribution (Mw / Mn) determined by GPC method: 8.
0 The results are shown in Table 2.

[0082]

Comparative Example 4 In Example 2, a linear low-density polyethylene resin having the following characteristics and prepared using a titanium-based catalyst was used instead of the linear low-density polyethylene resin used in Example 2. In the same manner as in Example 2, 100 bags with a tying string were prepared, and the bag was flattened and subjected to a repeated test as in Example 2. The film thickness forming the bag is 150
μm.

<Linear low-density polyethylene resin> Type of comonomer: 1-hexene Ethylene content: 2.8 mol% MFR (ASTM D 1238, 190 ° C., load 2.16 kg): 1.0 g
Density: 0.930 g / cm ³ Molecular weight distribution (Mw / Mn) determined by GPC method:
0 The results are shown in Table 2.

[0084]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a grain bag according to the present invention.

FIG. 2 is a perspective view showing one example of a grain bag according to the present invention.

FIG. 3 is a cross-sectional view showing an example of a grain bag according to the present invention.

FIG. 4 is a cross-sectional view showing one example of a grain bag according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grain bag 2a Side end 2b Side end 3a Front part 3b Back part 4 Bottom part 5 Opening part 6 Tie string 7 Open end part 8 Extension end part 9 Vent hole 10 String seal part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C08L 23/06 C08L 23/06 B29K 23:00

Claims (5)

[Claims] 1. Two side end portions formed by gusset-folding two opposing peripheral surfaces of a tubular film, and a front portion and a rear portion formed by other opposing peripheral surfaces.
A bottom portion formed by closing one of the openings of the tubular film, and a bag for cereal consisting of an opening facing the bottom portion, wherein the tubular film is a linear shape prepared using a metallocene catalyst. It is made of a low-density polyethylene resin (A) or a composition thereof, wherein the bottom is heat-sealed, the heat-sealing strength is 30 N / 15 mm or more, and the bottom is tied to one of the front and rear ends. A grain bag to which a string is attached. 2. The linear low density polyethylene resin (A)
Is composed of ethylene and an α-olefin having 4 or more carbon atoms, and has a melt flow rate (ASTM D 1238, 190 ° C,
(Load 2.16 kg) is 0.1 to 1.0 g / 10 min, the density is 0.900 to 0.918 g / cm ³ , and the molecular weight distribution (Mw / Mn) determined by GPC is 1.5 to 1.0 g / cm ³ . 3.
The grain bag according to claim 1, wherein the number is 5. 3. The linear low-density polyethylene resin (A) composition comprises (A) ethylene and an α-olefin having 4 or more carbon atoms, and has a melt flow rate (ASTM D 123).
8,190 ° C., load 2.16 kg) are 0.1 to 1.0 g / 10 min, the density is 0.900 to 0.918 g / cm ³ , and the molecular weight distribution (Mw / Mn) determined by the GPC method Is a linear low-density polyethylene resin having a ratio of 1.5 to 3.5: 4
0-70 parts by weight, and (B) density 0.935-0.97
0 g / cm ³ linear medium / high density polyethylene resin:
1 to 55 parts by weight and (C) density of 0.915 to 0.92
High pressure method low density polyethylene resin of 4 g / cm ³ : 5
To 29 parts by weight [the total of components (A), (B) and (C) is 100 parts by weight], and the composition has a melt flow rate (ASTM D 1238,190). ℃, load 2.16k
g) is 0.5 to 2.0 g / 10 min and the density is 0.9.
18~0.935g / cm ^3, and grain bag according to claim 1, melt tension is equal to or not less than 5g. 4. The grain bag according to claim 1, wherein a plurality of ventilation holes are provided. 5. The cereal bag according to claim 1, wherein a surface treatment by corona discharge is performed.