JP2003094579A - Coextruded polypropylene film and packaging bag using the film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coextruded polypropylene film which is good in sealability of a heat seal part and free from folding wrinkles and shrinkage wrinkles formed in heat-sealing and is suitable for packaging precessed food such as noodle and bread and a packaging bag using the film. SOLUTION: The coextruded polypropylene film is composed of at least two layers each having a base layer (I) mainly comprising a polypropylene resin and a heat seal layer (II) mainly comprising a propylene-α-olefin random copolymer which is formed on one surface of the base layer. The film meets a start-up temperature of the heat seal between specified heat seal layers, a 1% tensile modulus of elasticity, a static friction coefficient, a haze value, the seal strength between the base layer and the heat seal layer, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene-based co-extrusion film and a packaging bag using the film. More specifically, the heat-sealing portion has a good sealing property, and a sealing portion generated during heat-sealing is formed. TECHNICAL FIELD The present invention relates to a polypropylene-based co-extrusion film suitable for packaging processed foods such as noodles and bread, which is free from creases and shrinkage wrinkles, and a packaging bag using the film.

[0002]

2. Description of the Related Art Unstretched polypropylene film is noodle,
Widely used as a sealant film for packaging processed foods such as bread. It is a film for obtaining an individual package by heat-sealing after loading the contents, and in recent years, in order to improve the productivity of the individual package, a high bag-making process speed is required.

However, the sealant film used so far cannot keep up with the speeding up of the bag making process, and the heat sealing is insufficient. Specifically, in a pillow package in which a vertical seal portion and a horizontal seal portion are present, a poor sealing property due to floating of the seal portion, a so-called tunneling phenomenon occurs at the overlapping portion of the vertical seal portion and the horizontal seal portion. When the tunneling occurs, various germs enter from the void portion to cause a sanitary problem, or air escapes from the void portion to crush the contents inside.

Therefore, a monolayer film using a resin having a lower melting point has been developed. However, in the case of a single-layer film, the melting point of the layer on the side opposite to the heat-sealing layer of the film is the same, so shrinkage wrinkles may occur due to heat from the heat-sealing, the heat-sealing temperature may fluctuate higher than the setting, and the heat-sealing time may be exceeded. In the case of slight overheating such as the above, there was a problem of heat resistance such that the resin adhered to the heat seal bar and the film was broken. Further, since the film has no rigidity, there is a serious problem that folding creases are generated when the bag is half-folded and a tunneling phenomenon occurs.

Further, there has been proposed a laminated film having a heat resistance and rigidity which can be sealed at a low temperature and which comprises a base material layer made of a resin having a high melting point and a heat sealing layer made of a resin having a low melting point. See Kaihei 9-85911). However, in this laminated film, the low melting point sealing layer resin may be insufficiently melted during high-speed bag manufacturing. In other words, the optimum bag-making temperature range is narrow, and the tunneling of the folds and the overlap between the vertical seal and the horizontal seal is not sufficiently eliminated, and the melt filling of the seal layer resin into the creases is not possible. When the heat-sealing temperature is raised for completeness, there has been a problem that shrinkage wrinkles occur in the sealing portion.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is that the heat-sealing portion has a good sealing property, and there is no crease or shrinkage wrinkle of the sealing portion that occurs during heat-sealing. A polypropylene-based co-extrusion film suitable for packaging processed foods such as noodles and bread, and a packaging bag using the film.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have used a propylene / α-olefin random copolymer in a heat seal layer,
Heat-sealing temperature between specific heat-sealing layers, tensile modulus, good sealing performance of the heat-sealing part using a co-pressing film having a coefficient of static friction, and creases in the sealing part occurring during heat-sealing, It was found that a film having no shrinkage wrinkles and good transparency can be obtained, and the present invention has been completed.

That is, according to the first aspect of the present invention,
(I) layer mainly composed of polypropylene resin, and (I)
It is characterized by comprising at least two layers having a (II) layer mainly composed of a propylene / α-olefin random copolymer formed on one surface of the layer, and satisfying the following characteristics (1) to (6): Provided is a polypropylene-based co-extrusion film. Characteristic (1): Heat seal strength between layers (II) is 10
The seal temperature Ts1 at which 0 g / 15 mm is reached is 125 ° C. or lower. Characteristic (2): Heat seal strength between layers (II) is 80
The sealing temperature Th, which is 0 g / 15 mm or more, is 132 ° C. or less. Characteristic (3): 1% tensile elastic modulus is 6000 to 9000 kg
/ Cm ² . Characteristic (4): The coefficient of static friction between layers (II) is 0.35 or less. Characteristic (5): Heat seal strength between layers (I) is 100
The seal temperature Ts2 of g / 15 mm satisfies the following equation. Ts2 ≧ Ts1 + 5 Characteristic (6): The relationship between the haze value (HZ (%)) and the film thickness (d (μm)) satisfies the following equation. (0.04 × d + 0.5) <HZ <(0.04 × d +
2.5)

According to the second aspect of the present invention, the thickness ratio of the (II) layer to the total film thickness is 0.01 to.
The polypropylene-based co-extrusion film according to the first invention is provided, which is 0.5.

According to a third aspect of the present invention, the propylene / α-olefin random copolymer is a propylene / α-olefin random copolymer polymerized using a metallocene catalyst. A polypropylene-based co-extrusion film according to the first or second invention is provided.

According to a fourth aspect of the present invention, the polypropylene described in any one of the first to third aspects, wherein the α-olefin of the propylene / α-olefin random copolymer is ethylene. A co-pressed film is provided.

According to a fifth aspect of the present invention, (I
The heat seal strength between the I) layer and the (I) layer is 100 g / 1.
A polypropylene-based co-extrusion film according to any one of the first to fourth inventions, which is suitable for envelope-type seal packaging, is provided in which a sealing temperature Ts3 of 5 mm satisfies the following formula. Ts1 <Ts3 ≦ 132 ° C.

Further, according to a sixth aspect of the present invention, there is provided the polypropylene-based co-extrusion film according to any one of the first to fifth aspects, which is used in an automatic packaging machine.

Further, according to a seventh aspect of the present invention, there is provided the polypropylene-based co-extrusion film according to any one of the first to sixth aspects, which is used for packaging food products.

According to an eighth aspect of the present invention, the first aspect
A completely hermetically sealed packaging bag comprising the polypropylene-based co-extrusion film according to any one of the inventions to.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Each layer constituting the film of the present invention, its constituent components, a co-extrusion film, a packaging method and the like will be described in detail below.

(1) (II) Layer The (II) layer constituting the co-pressed film of the present invention is a heat-sealing layer mainly composed of a propylene / α-olefin random copolymer. The following copolymers can be used as the propylene / α-olefin random copolymer.

Examples of the α-olefin in the propylene / α-olefin random copolymer include C2-C20 α-olefins other than propylene, such as ethylene, 1-butene, 1-pentene and 1-hexene. , 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene-1 and the like. The α-olefin copolymerized with propylene may be used alone or in combination of two or more. Of these, α-olefins having 2 carbon atoms, that is, ethylene is most preferable. The content of this α-olefin is
2.0 to 23 mol% is preferable, and 2.5 is more preferable.
Is about 15 mol%. The melting point of the propylene / α-olefin random copolymer is preferably lower than 135 ° C, more preferably lower than 132 ° C, particularly preferably 12 ° C.
It is less than 8 ° C.

The above-mentioned propylene / α-olefin random copolymer has a so-called metallocene catalyst consisting of the following catalyst component (A), catalyst component (B) and, if necessary, catalyst component (C). It is preferably produced by copolymerizing propylene with a small amount of α-olefin below.

Catalyst component (A) Q (C ₅ H _4-a R ¹ _a ) (C ₅ H _4-b R ² _b ) Me
XY ^{_{(where, C 5 H 4-a R}} 1 a and _C 5 _{H 4-b} ^{R 2}
_b represents a conjugated five-membered ring ligand. Q represents a bonding group bridging two conjugated five-membered ring ligands. Me represents zirconium or hafnium. X and Y are each independently hydrogen, halogen, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and 1 to 2 carbon atoms.
An alkylamide group having 0, a trifluoromethanesulfonic acid group, a phosphorus-containing hydrocarbon group having 1 to 20 carbon atoms or a silicon-containing hydrocarbon group having 1 to 20 carbon atoms is shown. R ¹ and R
² is a substituent on the conjugated five-membered ring ligand, each independently being a hydrocarbon group having 1 to 20 carbon atoms, a halogen, an alkoxy group, a silicon-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, A nitrogen-containing hydrocarbon group or a boron-containing hydrocarbon group is shown. Two adjacent R ¹ or two R ² may be bonded to each other to form a ring. a and b are 0 ≦ a
It is an integer that satisfies ≦ 4 and 0 ≦ b ≦ 4. However, R ¹
The two five-membered ring ligands with and R ² are asymmetric with respect to the plane containing Me in terms of their relative position via the group Q. )

Here, Q is two conjugated five-membered ring ligands C
₅ H _4-a R ¹ _a and a C ₅ H _{4- b} R ² _b, which are crosslinkable groups. Specifically, for example, (a) carbon number 1 to
20, preferably 1-6 alkylene group, (b) silylene group having 1-20 carbon atoms, preferably 1-12 hydrocarbon group, (c) 1-20 carbon atoms, preferably 1-12
There is a germylene group having a hydrocarbon group of. Of these, an alkylene group and a silylene group are preferable.

Me is zirconium or hafnium.

X and Y may be each independently, that is, may be the same or different, and (a) hydrogen, (b) halogen (fluorine, chlorine, bromine or iodine, preferably chlorine), (c) carbon number 1 To 20 hydrocarbon groups, (d) C1 to C20 alkoxy groups, (e) C1 to C20 alkylamido groups, (f) C1 to C20 phosphorus-containing hydrocarbon groups, (g) It represents a silicon-containing hydrocarbon group having 1 to 20 carbon atoms or a (thi) trifluoromethanesulfonic acid group.

R ¹ and R ² are substituents on the conjugated five-membered ring ligand, each independently being a hydrocarbon group having 1 to 20 carbon atoms, halogen, or an alkoxy group having 1 to 20 carbon atoms. , A silicon-containing hydrocarbon group having 3 to 20 carbon atoms, and 2 carbon atoms
To a phosphorus-containing hydrocarbon group having 20 to 20 carbon atoms, a nitrogen-containing hydrocarbon group having 2 to 20 carbon atoms, or a boron-containing hydrocarbon group having 2 to 20 carbon atoms. These substituents may have a substituent in the side chain. Further, two adjacent R ^{1 s} or two R ^{2 s} may be bonded to each other at the ω-end to form a ring together with a part of the cyclopentadienyl group.
As a typical example in such a case, two adjacent R ¹ (or R ² ) on the cyclopentadienyl group share a double bond of the cyclopentadienyl group to form a condensed 6-membered ring. (Ie, indenyl group and substituted indenyl group, and fluorenyl group and substituted fluorenyl group) and those forming a condensed seven-membered ring (ie, azulenyl group and substituted azulenyl group). Preferably, two adjacent R ¹ or R ² on one or two cyclopentadienyl groups desirably form a condensed seven-membered ring.

A and b are integers satisfying 0≤a≤4 and 0≤b≤4.

The following may be mentioned as non-limiting examples of the above metallocene compounds. It should be noted that these compounds are indicated by their chemical names only, but it goes without saying that their three-dimensional structure has the asymmetry referred to in the present invention. (1) Dimethyl silylene bis {1- (2-methyl-4-
Phenyl-4H-azurenyl)} zirconium dichloride, (2) dimethylsilylenebis [1- {2-methyl-
4- (4-chlorophenyl) -4H-azurenyl}] zirconium dichloride, (3) dimethylsilylenebis [1- {2-methyl-4- (4-fluorophenyl)-
4H-azurenyl}] zirconium dichloride, (4)
Dimethylsilylenebis [1- {2-methyl-4- (3-
Chlorophenyl) -4H-azurenyl}] zirconium dichloride, (5) dimethylsilylene bis [1- {2-
Methyl-4- (2-methylphenyl) -4H-azurenyl}] zirconium dichloride, (6) dimethylsilylenebis [1- {2-methyl-4- (1-naphthyl) -4]
H-azurenyl}] zirconium dichloride, (7) dimethylsilylenebis [1- {2-methyl-4- (2-naphthyl) -4H-azurenyl}] zirconium dichloride, (8) dimethylsilylenebis [1- {2- Methyl-
4- (4-t-butylphenyl) -4H-azurenyl}] zirconium dichloride, (9) dimethylsilylenebis [1- {2-methyl-4- (4-fluoro-1-)
Naphthyl) -4H-azulenyl}] zirconium dichloride, (10) dimethylsilylene bis [1- {2-methyl-4- (4-fluoro-2-naphthyl) -4H-azulenyl}] zirconium dichloride, (11) dimethylsilylene. Bis {1- (2-ethyl-4-phenyl-4H
-Azurenyl)} zirconium dichloride, (12) dimethylsilylene bis [1- {2-ethyl-4- (4-chlorophenyl) -4H-azurenyl}] zirconium dichloride, (13) dimethylsilylene bis [1- {2-
Ethyl-4- (4-fluorophenyl) -4H-azurenyl}] zirconium dichloride, (14) dimethylsilylenebis [1- {2-ethyl-4- (2-methylphenyl) -4H-azurenyl}] zirconium dichloride, (15) Dimethylsilylenebis [1- {2-ethyl-4- (1-naphthyl) -4H-azurenyl}] zirconium dichloride, (16) Dimethylsilylenebis [1.
-{2-Ethyl-4- (1-anthracenyl) -4H-
Azulenyl}] zirconium dichloride, (17) dimethylsilylenebis [1- {2-ethyl-4- (1-phenanthryl) -4H-azurenyl}] zirconium dichloride, (18) dimethylsilylenebis {1- (2-dimethylborano-) 4-indolyl-4H-azulenyl)}
Zirconium dichloride, (19) dimethylsilylene bis {1- (2-methyl-4,5-benzoindenyl)}
Zirconium dichloride, (20) dimethylsilylene bis {1- (2-methyl-4-phenylindenyl)} zirconium dichloride and the like can be mentioned.

Catalyst component (B) In the metallocene catalyst, the component (B) is reacted with the following (b-1) aluminum oxy compound and (b-2) component (A) to convert the component (A) into a cation. A component selected from a particulate carrier supporting an ionic compound or Lewis acid capable of conversion, (b-3) solid acid particulates, and (b-4) ion-exchange layered silicate is desirable.

(B-1) Aluminumoxy compound: Examples of the aluminumoxy compound include so-called alumoxanes such as methylalumoxane and methylisobutylalumoxane. The aluminum oxy compound may be supported on a fine particle carrier. Examples of the fine particle carrier include fine particle carriers made of an inorganic or organic compound. Examples of the inorganic carrier include silica, alumina, silica-alumina magnesium chloride, activated carbon, and inorganic silicate. Alternatively, it may be a mixture thereof. Examples of the organic carrier include polymers of α-olefins having 2 to 14 carbon atoms such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene; and aromatic unsaturated hydrocarbons such as styrene and divinylbenzene. A fine particle carrier of a porous polymer made of a polymer or the like can be used. Alternatively, it may be a mixture thereof.

(B-2) Fine particle carrier carrying an ionic compound or Lewis acid capable of converting the component (A) into a cation by reacting with the component (A): component (A)
Examples of the ionic compound capable of reacting with the component (A) to convert into a cation include cations such as carbonium cation and ammonium cation, triphenylboron, tris (3,5-difluorophenyl) boron, Examples thereof include complex compounds of organic boron compounds such as tris (pentafluorophenyl) boron with cations. Examples of Lewis acids, particularly Lewis acids capable of converting the component (A) into cations include various organic boron compounds such as tris (pentafluorophenyl) boron. Alternatively, metal halide compounds such as aluminum chloride and magnesium chloride are exemplified. As the particulate carrier, the above-mentioned ones can be appropriately used.

(B-3) Solid acid: Examples of the solid acid include alumina and silica-alumina.

(B-4) Ion-exchange layered silicate: As the component (b-4), an ion-exchange layered silicate is used. The ion-exchange layered silicate is a silicate compound that has a crystal structure in which planes formed by ionic bonds and the like are stacked in parallel with each other with weak bonding forces, and the ion-exchangeable layered silicate is referred to. Preferred specific examples of the ion-exchange layered silicate include montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, smectite group such as stevensite, vermiculite group such as vermiculite, mica, illite, sericite, sea green. Mica tribe such as stone is mentioned.

As the component B, (b-4) is particularly preferable.

Catalyst Component (C) Component (C) is an organoaluminum compound. The organoaluminum compound used as the component (C) in the present invention is suitably a compound represented by the general formula (AlR ⁴ _n X _3-n ) _m . In this formula, R ⁴ represents a hydrocarbon group having 1 to 20 carbon atoms, X represents halogen, hydrogen, an alkoxy group,
Indicates an amino group. n is an integer of 1 to 3 and m is an integer of 1 to 2. Specific examples of the component (C) include trimethylaluminum, triethylaluminum, trinormalpropylaluminum, trinormalbutylaluminum, triisobutylaluminum, trinormalhexylaluminum, trinormaloctylaluminum, trinormaldecylaluminum, diethylaluminum chloride, diethyl. Aluminum sesquichloride, diethyl aluminum hydride, diethyl aluminum ethoxide, diethyl aluminum dimethylamide, diisobutyl aluminum hydride, diisobutyl aluminum chloride and the like can be mentioned.

The amounts of component (A), component (B) and component (C) used in the preparation of the above catalyst can be used in any ratio.

The propylene / α-olefin random copolymer can be polymerized by a slurry method using an inert solvent in the presence of the above metallocene catalyst, a gas phase method or a solution method using substantially no solvent, or The bulk polymerization method etc. which use a polymerization monomer as a solvent are mentioned. The propylene / α-olefin random copolymer obtained by the above-mentioned polymerization method has a characteristic that the temperature range in which the resin melts is narrow because the composition distribution is narrow. When a resin having this characteristic is used for the heat-sealing layer, the resin is likely to be completely melted when a certain temperature is reached, so that complete sealing can be performed.

In the layer (II), the propylene / α-olefin random copolymer obtained as described above may be used alone as a resin component, or a mixture with another resin may be used. When using a mixture, the above propylene
When a resin having a melting point higher than that of the α-olefin random copolymer is used, the propylene / α-olefin random copolymer may be used as a main component, specifically, the propylene / α-olefin random copolymer may be 60% or more. % Or more, preferably 70% by weight or more, more preferably 80% by weight or more, and when a resin having a lower melting point than the propylene / α-olefin random copolymer is used, the propylene / α-olefin is used. The random copolymer content is preferably 70% by weight or more. Examples of the other resin include ethylene / propylene elastomer, ethylene / butene elastomer, propylene / butene elastomer, polybutene-1, homopolypropylene, and terpolymer.

Further, in the layer (II), various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, a nucleating agent, an antistatic agent, and the like are added to the extent that the object of the present invention is not impaired. Slip agent, anti-blocking agent, anti-fog agent, colorant,
Fillers and the like can be added.

(2) Layer (I) The layer (I) of the co-pressed film of the present invention is made of a resin mainly composed of polypropylene resin and constitutes the base layer of the co-pressed film. As the polypropylene-based resin, a resin having a melting point (Tm) of 145 ° C. or higher and 170 ° C. or lower is preferably used, and a homopolymer of propylene, a random propylene and an α-olefin such as ethylene, 1-butene or 1-hexene. Examples thereof include copolymers and block copolymers. Tm of polypropylene resin is 145 to 165 ° C
In the film property (3) described below, the 1% tensile elastic modulus is set to 6000 to 9000 kg / cm ^2.
Can be easily done. Of these, propylene homopolymers and propylene random copolymers are preferable, and they may be used alone or in combination of two or more kinds.

In the layer (I), various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, a nucleating agent, an antistatic agent, and a slip agent are used as long as the object of the present invention is not impaired. , An anti-blocking agent, an antifogging agent, a coloring agent, a filler and the like can be added.

Further, the layer (I) may be a single layer or a layer composed of a plurality of layers. When the (I) layer is a plurality of layers, from the viewpoint of film rigidity, the melting point of the polypropylene resin on the surface side of the (II) layer is preferably 130 to 170 ° C., and the melting point of the resin not on the surface side of the (II) layer is 150
~ 170 ° C is preferred.

(3) Co-Pressed Film The co-pressed film of the present invention comprises a (II) layer composed of a resin containing the above propylene / α-olefin copolymer as a main component and the above polypropylene resin (I) as a main component. It is a laminated film composed of layers. The (I) layer may be one layer or two or more layers. In the case of two or more layers, the melting point Tm of the polypropylene resin is the melting point T of the layer directly facing the (II) layer.
m. The layer structure of the co-pushed film includes (II) layer / (I) layer, (II) layer / (I) layer (i
-Intermediate layer) / (I) layer (ii-surface layer) are exemplified. Furthermore, when the co-extruded film of the present invention is used as a packaging bag, the layer (II) is used as an inner heat-sealing layer so as to have a central joint-sealing seal or an envelope-type seal as shown in FIGS. Often used as a hermetically sealed packaging bag. FIG. 1 is a side view for explaining a seal portion of a packaging bag made into a bag, and FIG. 2 shows a vertical seal portion (II).
X- in FIG. 1, which is a gastric seal in which layers are heat-sealed.
FIG. 3 is a cross-sectional view as seen from the X ′ direction, and FIG. 3 is a cross-sectional view as seen from the XX ′ direction in FIG. 1 in which the vertical seal portion is an envelope type seal in which the (I) layer and the (II) layer are heat-sealed. Figure 1
3 to 3, 1 is an upper horizontal seal portion, 2 is a lower horizontal seal portion, 3 is a vertical seal portion, 4 is a portion where the vertical seal and the horizontal seal are overlapped, 5 is a vertical joint seal portion, and 6 is a vertical envelope type seal portion. ,
Reference numerals 7 indicate half-folded portions, respectively.

The co-pressed film of the present invention is a film having the following properties (1) to (6), and more preferably the property (7).

Characteristic (1): Heat seal strength between layers of Ts1 (II) is 100 g / 15 m.
The seal temperature Ts1 at which m is 125 ° C. or lower, preferably 124 ° C. or lower, and more preferably 122 ° C. or lower.
Ts1 is called a heat-seal rising temperature, and is a measure showing how low temperature the film can be heat-sealed. If Ts1 exceeds 125 ° C., it is necessary to raise the sealing temperature during bag making, and shrink wrinkles occur. Since the film may become sticky, the lower limit is practically about 90 ° C.

Characteristic (2): The heat seal strength between the Th (II) layers is 800 g / 15 m.
The sealing temperature Th at which the temperature is m or higher is 132 ° C. or lower, preferably 131 ° C. or lower, and more preferably 129 ° C. or lower. If Th exceeds 132 ° C, creases will occur during bag making, or insufficient melt filling will occur at the overlapping portion of the vertical seal portion and the horizontal seal portion (4 in Fig. 1), tunneling will easily occur, and complete sealing will occur. The possible bag making temperature range is narrowed.

Characteristic (3): 1% Tensile Elastic Modulus In the present invention, 1% tensile elastic modulus means 1 of the film in the direction of flow (MD direction) and the direction orthogonal to the direction of flow (TD direction) during film formation. It refers to% tensile modulus. 1%
Tensile elastic modulus is 6000 in MD and TD respectively
~ 9000 kg / cm ² , preferably 6100-850
0 kg / cm ² , more preferably 6300 to 8000 k
It is g / cm ² . 1% tensile elastic modulus is 6000 kg / c
If it is less than m ² , many folds and wrinkles will occur during bag making, and tunneling will occur, resulting in incomplete sealing. 9000kg / cm ²
When it exceeds, tunneling occurs at the half-folded portion of the bag making (7 shown in FIGS. 2 and 3), and the bag cannot be completely sealed.

Generally, during bag making, half-folding shown in FIGS.
If the rib part 7 is properly folded in half, it will not break.
It is difficult to fold in half when the waist is low, and it folds
You can In order for 1% tensile modulus to meet the above conditions
Is due to the change in the resin thickness ratio of the (II) layer.
It suffices to change the Tm of the fat, and the thickness ratio of the (II) layer resin
Is about 0.01 to 0.2, the polypropylene resin
Tm is about 145 to 155 ℃
If the ratio is about 0.2 to 0.5, the polypropylene resin
Polypropylene based with Tm of about 155 to 170 ° C
When a resin is selected, the 1% elastic modulus easily falls within the above range.
Become. Tm of polypropylene resin is 145 to 170 ° C
By setting the 1% tensile elastic modulus to 6000 to 900
0 kg / cm ^TwoCan be easily done.

Characteristic (4): Coefficient of static friction Coefficient of static friction between layers (II) of the film is 0.35 or less, preferably 0.30 or less, more preferably 0.20.
It is the following. More than 0.35, slippage is bad during bag making,
Creases will occur and cause tunneling.

The coefficient of static friction between layers (II) of the film can be controlled to 0.35 or less by adding an anti-blocking agent and / or a lubricant to the resin of layer (II). Examples of the antiblocking agent include inorganic or organic fine particles.

As the inorganic anti-blocking agent,
For example, synthetic or natural silica (silicon dioxide), magnesium silicate, aluminosilicate, talc, zeolite, aluminum borate, calcium carbonate, calcium sulfate, barium sulfate, calcium phosphate and the like are used.
Examples of organic antiblocking agents include polymethylmethacrylate, poly (methylsilyltosesquioxane (silicone), polyamide, polytetrafluoroethylene, epoxy resin, polyester resin, benzoguanamine formaldehyde (urea resin), phenol resin, etc. Can be used. The average particle size of the fine particles is generally about 0.1 to 20 μm, and the average particle size of 1 to 5 μm is preferably used. The antiblocking agent is preferably 0.01 to 0.7 parts by weight, more preferably 0.05 to 0.5 parts by weight, and particularly preferably 0 to 100 parts by weight of the propylene / α-olefin random copolymer. It is used in a proportion of 0.05 to 0.3 part by weight.

As the lubricant, for example, a linear monocarboxylic acid monoamide compound or a linear monocarboxylic acid bisamide compound can be used alone or in combination of two or more. As the linear monocarboxylic acid monoamide compound, for example, oleic acid amide, stearic acid amide, erucic acid amide, palmitic acid amide,
Examples thereof include behenic acid amide and lauric acid amide. Examples of the linear monocarboxylic acid bisamide compound include ethylenebisoleic acid amide, ethylenebisstearic acid amide, and methylenebisstearic acid amide. The amount of lubricant added is propylene
With respect to 100 parts by weight of the α-olefin random copolymer, preferably 0.01 to 1.0 part by weight, more preferably 0.02 to 0.5 part by weight, particularly preferably 0.04 to 10 parts by weight.
0.25 parts by weight.

Characteristic (5) The heat-sealing strength between the Ts2 (I) layers is 100 g / 15 mm.
The seal temperature Ts2 that is 5 ° C. or higher is higher than Ts1. That is, Ts2 ≧ Ts1 + 5, preferably Ts2> Ts1 + 8, and more preferably Ts2> Ts1 + 10. When Ts2 is less than (Ts1 + 5), the seal bar sticks to the (I) layer during heat sealing, which is not preferable. (I) Heat-seal rising temperature Ts2 between layers is T
In order to satisfy s2 ≧ Ts1 + 5, the Tm of the (I) layer may be increased by 5 ° C. or more than the Tm of the surface layer resin.

Characteristic (6): Haze Haze value (HZ) (%) and film thickness (d) (μm)
Satisfies the following relationship. (0.04 × d + 0.5) ≦ HZ ≦ (0.04 × d +
2.5) Preferably, (0.04 × d + 0.7) ≦ HZ ≦ (0.04 × d +
2.3), and more preferably (0.04 × d + 1.0) ≦ HZ ≦ (0.04 × d +
2.0). If the HZ is less than this range, it is difficult to manufacture, or the slipperiness, blocking resistance and the like deteriorate, which is not desirable. When the HZ exceeds this range, the contents put in the packaging bag cannot be clearly seen.

Characteristic (7): Ts3 (II) layer and (I) layer have a heat seal strength of 100 g.
The seal temperature Ts3 of / 15 mm is a temperature higher than Ts1 and is preferably 132 ° C. or lower. That is, Ts1 <Ts3 ≦ 132 ° C. is preferable, Ts1 + 1 <Ts3 ≦ 131 ° C. is more preferable, and Ts1 + 3 <Ts3 ≦ 129 ° C. is particularly preferable. If Ts3 exceeds 132 ° C., sufficient sealing strength will not be obtained when an envelope type seal is made. On the other hand, if it is Ts1 or less, the layer (I) will stick to the seal bar at the time of heat sealing, and troubles such as breakage of the film will occur.
When the film surface is corona-treated, the heat-sealing temperature shifts to a higher level, and when corona-treating the (I) layer, the Tm of the resin of the (I) layer is changed to the Tm of the resin of the (II) layer.
If the temperature is raised by 3 ° C. or more, the above condition will be easily satisfied.

The thickness of the co-extrusion film of the present invention is
5 to 400 μm is preferable, and 10 to 20 is more preferable.
It is 0 μm. (I
The thickness ratio of the I) layer is preferably 0.01 to 0.5, more preferably 0.05 to 0.4, and particularly preferably 0.1 to 0.5.
It is 0.3.

Further, the co-pressed film of the present invention may be subjected to a film treatment method which is usually used for film formation, such as a stretching treatment and a liquid agent coating treatment.

The co-pressed film of the present invention is prepared by mixing the respective components constituting each layer with various blenders,
It can be manufactured by supplying to a multi-layer T-die or circular die film forming machine equipped with die lips in an extruder corresponding to the number of layers of the film and co-extruding.
After being co-extruded, it is cooled by being brought into contact with a roll through which a coolant such as water is passed, and generally has good transparency,
A film with good thickness accuracy can be manufactured.

The co-pressed film of the present invention obtained by the above method can be easily made into a packaging bag by an automatic packaging machine such as an automatic bagging and packaging machine, and a vertical pillow package having a central joint seal or an envelope type seal. Due to, because it can be completely sealed,
It is preferably used as a film for packaging food such as bread and noodles. Here, "completely sealed" refers to a packaging state in which the air inside the bag and the air outside the bag are completely blocked. By perfect sealing,
It is also excellent in product storability, such that bacteria from the outside do not enter, the air inside does not escape easily, and that the contents in the bag are not crushed.

[0058]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not limited to the examples only. The resin physical properties used in the examples, the film physical property measurement methods, the resin polymerization methods used, and the film bag making methods are as follows.

1. Test method, evaluation method (1) (II) Heat-seal rising temperature between layers (Ts1): Measured as follows in accordance with JIS Z1707. Using a 5 mm x 200 mm heat seal bar, the layers (II) of the laminated film were perpendicular to the melt-extruded direction (MD) of the film under the heat seal conditions of pressure 2 kg / cm ² and time 1 second at each temperature setting. A 15 mm wide sample is cut from the sample that has been sealed so that it has a pulling speed of 5 using a Shopper type tensile tester.
It was separated in the MD direction at 00 mm / min, and the load was read. The seal temperature at which the load was 100 g was set to Ts1.

(2) Temperature (Th) at which heat seal strength between layers (II) is 800 g / 15 mm or more: JIS
It measured based on Z1707 as follows. 5m
Using a m × 200 mm heat seal bar, pressure (2 kg) was applied to each layer (II) of the laminated film at each temperature setting.
A sample of 15 mm width is cut from the sample sealed so as to be perpendicular to the melt-extruded direction (MD) of the film under the heat-sealing condition of 1 / cm ² for 1 second, and the pulling speed is 500 mm using a Shopper-type tensile tester. It was pulled apart in the MD direction at / min and the load was read. Load is 8
The sealing temperature at which the amount became 00 g was set to Th.

(3) Heat seal rising temperature (Ts2) between layers (I): Measured in the following manner according to JIS Z1707. The direction (MD) in which the film was melt-extruded under heat-sealing conditions of a pressure of 2 kg / cm ² and a time of 1 second at each temperature setting between layers (I) of the laminated film using a 5 mm × 200 mm heat-sealing bar.
A sample having a width of 15 mm was cut out from the sample sealed so as to be perpendicular to, and was pulled apart in the MD direction at a pulling speed of 500 mm / min using a Shopper type tensile tester, and the load was read. The seal temperature at which the load is 100g is T
s2.

(4) Heat-seal rising temperature (Ts3) between layers (II) and (I): Measured as follows in accordance with JIS Z1707. 5 mm x 200 mm
Using the heat seal bar of No. 2, the pressure of 2 kg / c was applied to the layers (I) and (II) of the laminated film at each temperature setting.
A 15 mm wide sample is cut out from a sample sealed so as to be perpendicular to the melt-extruded direction (MD) of the film under a heat-sealing condition of m ² for 1 second, and a pulling speed of 500 mm / is obtained using a Shopper-type tensile tester. MD in minutes
Separated in the direction, the load was read. Load is 100
The seal temperature at which g was set to Ts3.

(5) Tensile modulus (unit: kg / cm ² ):
Sample length 150m according to JIS K7127
m, sample width 15 mm, distance between chucks 100 mm,
The measurement was performed under the condition of a crosshead speed of 500 mm / min.

(6) Static friction coefficient: ASTM D1894
According to -90, the value between the (II) layers of the film was measured.

(7) Haze (unit:%): JIS K7
It measured based on 105.

(8) Confirmation of appearance (wrinkle) of film (i) Folded lines: Folded lines of the lateral seal portion of the bag-making product were evaluated according to the following criteria. ◯: No creases W: Slight creases are seen ×: Severe creases are observed (ii) Shrinkage wrinkles: Regarding contraction wrinkles in the lateral seal part, within the lateral seal temperature range where no contraction wrinkles occurred. The following criteria evaluated. ⊚: 10 ° C. or higher ○: 6 to less than 10 ° C Δ: 4 to less than 6 ° C. ×: less than 4 ° C. (Comprehensive judgment was 6 ° C. or higher and passed otherwise.)

(9) Confirmation of film sealing property As shown in FIG. 1, the central portion of the packaging bag cut along the line XX 'is cut to confirm the horizontal sealing condition of the upper and lower portions of the bag. Seal checker on the seal part (brand name Ageless seal check Distributor: Mitsubishi Gas Chemical, manufacturer:
It is assumed that tunneling has occurred when the seal checker has completely passed through the seal portion, and 15 bags made at each horizontal sealing temperature, and a seal check for 30 upper and lower seals have been performed, and tunneling has occurred. The number was counted and evaluated according to the following criteria. ⊚: Number of tunneling occurrences is 0/30 ◯: Number of tunneling occurrences is 1 to 2/30 △: Number of tunneling occurrences is 3 to 5/30 ×: Number of tunneling occurrences is 6 or more / 30 (◎ and ○ are It was judged that the tunneling was good.
Tunneling good temperature range condition: Ex above 10 ° C
cellent, less than 6-10 ° C is Good, 4-6 ° C
Bad was less than 4 and Poor was less than 4 ° C, and good sealing performance was obtained at 6 ° C or more. )

2. The film used in the bag-making method example was subjected to vertical pillow (center gassho seal, envelope-type seal) packaging by the following method using an automatic bagging and packaging machine (TSV330 type manufactured by Toyo Corporation), I made a bag. (I) Central gas palm seal: speed 22 bags / min, vertical heat seal temperature 120 ° C., air gauge pressure 4 kg / cm ² , horizontal heat seal temperature was changed from 140 ° C. to about 150 ° C. in steps of 2 ° C. The film width was 330 mm, the length 170 mm × width 155 mm flat bag, and the palm part 10 mm. (Ii) Envelope type seal: speed 22 bags / min, vertical heat seal temperature 125 ° C., air gauge pressure 4 kg / cm ² , horizontal heat seal temperature changed from 140 ° C. to about 150 ° C. in 2 ° C. increments. Film width 330 mm width, height 170 mm ×
A flat bag having a width of 155 mm and a vertical seal overlapping portion of 20 mm was used.

The propylene / α-olefin random copolymer used in the present invention was produced as shown in Polymerization Example 1. Polymerization Example 1 (1) Preparation of catalyst (i) Production of catalyst component (A) (r) -dichloro {1,1-dimethylsilylenebis [2
Synthesis of -methyl-4 (4-chlorophenyl) -4H-azurenyl]} zirconium is described in JP-A-11-24090.
It was synthesized by the method described in JP-A-9.

(Ii) Preparation of catalyst component (B) Preparation of ion-exchange layered silicate In a glass separable flask equipped with a 10-liter stirring blade, 3.75 liters of distilled water was added, followed by concentrated sulfuric acid (96
%) 2.5 kg was added slowly. At 50 ° C., montmorillonite (Ben clay SL manufactured by Mizusawa Chemical Co., Ltd .; average particle size = 25 μm, particle size distribution = 10 to 60 μm) was further added to 1 k.
g was dispersed, the temperature was raised to 90 ° C., and the temperature was maintained for 6.5 hours. After cooling to 50 ° C., this slurry was filtered under reduced pressure to collect a cake. Distilled water (7 liters) was added to this cake to form a reslurry, which was then filtered. This washing operation was carried out until the pH of the washing liquid (filtrate) exceeded 3.5.

The recovered cake was dried overnight at 110 ° C. under a nitrogen atmosphere. The weight after drying was 705 g. The composition (molar) ratio of the obtained ion-exchange layered silicate was
Al / Si = 0.129, Mg / Si = 0.018, F
e / Si was 0.013.

Furthermore, 1.72 liters of distilled water and then lithium sulfate monohydrate (700 g) were added to a glass separable flask equipped with a 10-liter stirring blade to prepare a solution, which was obtained as above. An ion-exchange layered silicate was added. The slurry was stirred at room temperature for 240 minutes. This slurry was filtered under reduced pressure to collect the cake. Distilled water (7 liters) was added to the cake to re-slurry it, and then filtered. This operation was repeated 3 times. The collected cake was dried overnight at 110 ° C. under a nitrogen atmosphere. Weight after drying is 69
It was 5 g. The composition (molar) ratio of the obtained ion-exchange layered silicate was Al / Si = 0.127, Mg / S.
i = 0.020, Fe / Si = 0.013, Li / Si
Was 0.018.

The previously chemically treated silicate was further dried with a kiln dryer. The specifications and drying conditions are as follows. Rotating cylinder: cylindrical, inner diameter 50 mm, heating zone 550 mm (electric furnace), with rotating blade: rotation speed: 2 rpm, inclination angle: 20/520, silicate supply rate: 2.5 g / min, gas flow rate: nitrogen, 96 liters / hour, countercurrent, drying temperature: 200 ° C (powder temperature)

(Iii) Preparation of catalyst In a metal reactor equipped with a stirrer with an internal volume of 13 liters,
A mixture of 0.24 kg of the dry silicate obtained above and 0.74 L of heptane containing 3% toluene (hereinafter, mixed heptane) was introduced, and 1.26 L of a solution of trinormal octylaluminum in heptane (0.40 M) was added. The internal temperature was maintained at 25 ° C. After the reaction for 1 hour, the mixture was thoroughly washed with mixed heptane to prepare a silicate slurry of 2.0 L.

In parallel, (r) -dichloro {1,1'-
Dimethylsilylenebis [2-methyl-4- (4-chlorophenyl) -4H-azurenyl]} zirconium was added to 2.
0.80 L of toluene was added to 18 g (3.0 mmol), and a heptane solution of triisobutylaluminum (0.
71M) was added thereto, and the mixture was reacted at room temperature for 1 hour. The mixture was added to the silicate slurry and stirred for 1 hour.
The mixed heptane was added to adjust to 5.0 L. continue,
When the internal temperature was raised to 40 ° C. and became stable, propylene was supplied at a rate of 100 g / hour to maintain the temperature. Four
After a lapse of time, the supply of propylene was stopped and the propylene was maintained for another hour. After the completion of the preliminary polymerization, the residual monomer was purged, and the catalyst was thoroughly washed with mixed heptane. Subsequently, 0.17 L of a heptane solution of triisobutylaluminum (0.71 M / L) was added, followed by vacuum drying at 45 ° C. By this operation, the dry prepolymerized catalyst 0.60k
g was obtained.

(2) After completely replacing the inside of the stirring autoclave having an internal volume of 200 liters with propylene, 45 kg of sufficiently dehydrated liquefied propylene was introduced. To this, 500 ml of triisobutylaluminum / n-heptane solution (0.12 mo
l), ethylene 2.25 kg, hydrogen 8.0 NL,
The internal temperature was maintained at 30 ° C. Next, 1.2 g of the above-mentioned prepolymerization catalyst was pressure-inserted with argon to start polymerization, the temperature was raised to 70 ° C. over 30 minutes, and the temperature was maintained for 1 hour. Here, 100 ml of ethanol was added to stop the reaction. Residual gas was purged and MFR (230 ° C) was 70 g /
10 minutes, Tm 124.5 ° C, Tc 88.7 ° C propylene-ethylene random copolymer (mRCP) 21k
g was obtained.

Example 1 100 parts by weight of the propylene-ethylene random copolymer (mRCP) obtained in Polymerization Example 1 was added with Irganox 1010 (manufactured by Ciba Specialty Chemicals) / Irgafos 168 (manufactured by Ciba Specialty Chemicals) as an additive. ) / Calcium stearate / citric acid treated synthetic silica (average particle size 2.7 μm) / ermic acid amide (Neutron S) = 0.05 parts by weight / 0.05 parts by weight / 0.05 parts by weight / 0.15 parts by weight Part / 0.10 part by weight, and was extruded at 200 ° C. using a twin-screw extruder PCM30 (manufactured by Ikegai Seisakusho) and granulated to obtain resin composition pellets.

The (mRCP) resin composition obtained above was applied to the layer (II) with a melting point of 163 ° C. and an MFR (230 ° C.) =
7.0 g / 10 min homopolypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FB3GT), melting point 140 ° C., MF
R (230 ° C.) = 7.0 g / 10 minutes random polypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FW3E) in a 50/50 (weight ratio) mixture in the (I) layer (i-intermediate layer), Also, melting point 140 ° C., MFR (230 ° C.) = 7.
Random polypropylene (trade name: FW3E, manufactured by Nippon Polychem Co., Ltd.) of 0 g / 10 minutes was used for the (I) layer (ii-surface layer), and the (I-ii) layer / (I-i) layer / (II).
Three extruders each independent of three layers ((I-ii) layer / (I-i) layer / (II) layer =) so that the layer ratio becomes 1/4/1 =
(Extruder with caliber of 40 mmφ / 40 mmφ / 40 mmφ), three-layer T die having a width of 500 mm connected to this, air knife (wind speed 8 m / sec), cooling roll (diameter 500 m)
mφ) equipped with a three-layer T-die method film manufacturing apparatus, co-extruding the melted three layers so that the sealant surface is in contact with the cooling roll at an extrusion resin temperature of 230 ° C., and then taking a film at a cooling roll temperature of 25 ° C. 30 μm thickness at a speed of 40 m / min
The co-extruded unstretched film of was obtained and its physical properties were evaluated.
The results are shown in Table 1. Further, vertical pillow packaging was performed with a central packing seal with an automatic bagging and packaging machine, and creases, shrinkage wrinkles, and tunneling were observed. The results are shown in Table 1. The surface layer was subjected to corona discharge treatment before bag making.

Example 2 As the (II) layer, a 9/1 (weight ratio) mixture of a (mRCP) resin composition and a propylene-butene type elastomer (manufactured by Mitsui Chemicals, Inc., trade name Toughmer XR110T) was used, and (I -I) The layer has a melting point of 163 ° C. and MFR (23
0 ° C.) = 7.0 g / 10 min homopolypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FB3GT) and melting point 140
℃, MFR (230 ℃) = 7.0g / 10 minutes random polypropylene (Nippon Polychem Co., Ltd., trade name FW
3E) and a 65/35 (weight ratio) mixture with (I-
ii) Layer, melting point 140 ° C., MFR (230 ° C.) =
Using 7.0 g / 10 min of random polypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FW3E), (I-i
Example 1 except that the ratio of i) layer / (I-i) layer / (II) layer was 1/3/1 and the film thickness was 40 μm.
A co-extruded film was obtained in the same manner as above, a packaging bag was manufactured, and the physical properties and the appearance were measured. The results are shown in Table 1.

Example 3 (I-i) and (I-ii) layers had a melting point of 163 ° C. and MF.
R (230 ° C.) = 7.0 g / 10 min homopolypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FB3GT) was used, and the (I-ii) layer / (I-i) layer / (II) layer ratio was set. Two
A co-pushing film was obtained in the same manner as in Example 1 except that the ratio was 1/1, and a packaging bag was manufactured. The physical properties and the appearance of the packaging bag were measured. The results are shown in Table 1.

Comparative Example 1 (II) layer having a melting point of 140 ° C. and MFR (230 ° C.)
= 7.0 g / 10 min random polypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FW3E) is used,
A co-extruded film was obtained in the same manner as in Example 1, a packaging bag was manufactured, and the physical properties and the appearance thereof were measured. The results are shown in Table 2.

Comparative Example 2 As the (Ii) layer, the melting point was 163 ° C. and the MFR (230
(° C) = 7.0 g / 10 min homopolypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FB3GT) was used, and (I-
A co-pressed film was obtained in the same manner as in Example 1 except that the ratio of ii) layer / (I-i) layer / (II) layer was 1/8/1, and a packaging bag was produced. The physical properties and appearance were measured. The results are shown in Table 2.

Comparative Example 3 A co-extruded film was obtained in the same manner as in Example 1 except that a citric acid-treated synthetic silica which was an anti-blocking agent was not added as the layer (II), and a packaging bag was produced. And the appearance was measured. The results are shown in Table 2.

Comparative Example 4 A co-extruded film was obtained in the same manner as in Example 1 except that the (mRCP) resin composition was used as the (Ii) layer, and a packaging bag was produced. It was measured.
The results are shown in Table 2.

Comparative Example 5 (II) layer having a melting point of 140 ° C. and MFR (230 ° C.)
= 7.0 g / 10 min of a random polypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FW3E) and a propylene-butene elastomer (manufactured by Mitsui Chemicals, Inc., trade name Toughmer XR110T) in an 8/2 (weight ratio) mixture. A co-extruded film was obtained in the same manner as in Example 1 except that the packaging bag was manufactured, and the physical properties and the appearance thereof were measured. The results are shown in Table 2.

Comparative Example 6 (I-i) layer has a melting point of 140 ° C. and MFR (230).
C.) = 7.0 g / 10 min homopolypropylene (manufactured by Nippon Polychem Co., Ltd., trade name FW3E)
A co-extruded film was obtained in the same manner as in Example 1, a packaging bag was manufactured, and the physical properties and the appearance thereof were measured. The results are shown in Table 2.

[0087]

[Table 1]

[0088]

[Table 2]

Example 4 A packaging bag was obtained in the same manner as in Example 1 except that the co-pressed film obtained in Example 1 was used for vertical pillow packaging with an envelope type seal. Occurrence of folds, shrinkage wrinkles and tunneling of the packaging bag was observed. The results are shown in Table 3.

Example 5 A packaging bag was obtained in the same manner as in Example 1 except that the co-pressed film obtained in Example 2 was used for vertical pillow packaging with an envelope type seal. Occurrence of folds, shrinkage wrinkles and tunneling of the packaging bag was observed. The results are shown in Table 3.

[0091]

[Table 3]

As is clear from Tables 1 to 3, when the co-pressed film of the present invention is used as a packaging bag, it has excellent transparency, good heat sealability, and creases, shrinkage wrinkles, and tunneling. No (Examples 1-5). on the other hand,
In the co-pressed film not using the propylene / ethylene random copolymer in the (II) layer, the heat seal rising temperature Ts1 at which the seal strength between the (II) layers is 100 g / 15 mm and the seal strength between the (II) layers are Since the temperature Th of 800 g / 15 mm or more is too high, tunneling occurs on the low temperature side during bag making,
On the high temperature side, some shrinkage wrinkles occurred and the width of the bag-making conditions was narrow (Comparative Example 1). A high melting point resin is used as the (I) layer resin,
When the thickness ratio of the (II) layer resin layer is reduced, the 1% elasticity ratio becomes too high, so that tunneling occurs at the half-folded portion during heat sealing at low temperature, and some shrinkage wrinkles occur at high temperature, and The bag condition width became narrower (Comparative Example 2). When the anti-blocking agent was not added to the (II) layer, the coefficient of static friction between the (II) layers was large, and the slippage was poor, which caused creases during bag making and tunneling (Comparative Example 3). When the same propylene / ethylene random copolymer as that of the layer (II) is used for the layer (I-ii) (I
Since the heat-sealing rising temperature Ts2 between the (I) layer and the (I-ii) layer is low, the (I-ii) layer stuck to the seal bar during the high-temperature sealing, and a hole was formed in the film or shrinkage wrinkles were generated (comparison). Example 4). In the co-pressed film in which the propylene / ethylene random copolymer is not used for the (II) layer, the temperature Th at which the strength between the (II) layers is 800 g / 15 mm is high, so that in the low temperature seal
The resin of layer I) could not be completely melted and tunneling occurred. Further, at high temperature, some shrinkage wrinkles occurred and the bag-making condition range was narrow (Comparative Example 5). When the polypropylene resin having a low melting point was used for the layer (I), the film had a low 1% elastic modulus, and wrinkles and wrinkles occurred during bag manufacturing, and tunneling also occurred (Comparative Example 6).

[0093]

EFFECTS OF THE INVENTION The co-pressed film of the present invention has a good sealing property in the heat-sealing portion, and has no creases or shrinkage wrinkles in the sealing portion generated during heat-sealing, and is suitable for automatic bagging and packaging machines. It can be easily made into a packaging bag by an automatic packaging machine, and can be perfectly sealed by vertical pillow packaging with a central joint seal or an envelope-type seal, and thus it is suitably used as a film for packaging food such as bread and noodles.

[Brief description of drawings]

FIG. 1 is a side view illustrating a sealing portion of a packaging bag manufactured using the film of the present invention.

FIG. 2 is a cross-sectional view of FIG. 1 seen from the XX ′ direction in which the seal is a gastric seal.

FIG. 3 is a cross-sectional view of FIG. 1 seen from the XX ′ direction in which the seal is an envelope type seal.

[Explanation of symbols]

1 Upper horizontal seal part 2 Lower horizontal seal part 3 Vertical seal part 4 Overlapping part of vertical seal and horizontal seal 5 Vertical joint seal part 6 Vertical envelope type seal part 7 Half-fold

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Omori             No. 1 Toho-cho, Yokkaichi-shi, Mie Japan Polyke             Mu Material Development Center F term (reference) 3E064 AA09 BA30 BB03 BC16 EA04                       EA08 FA01 HM01 HN05                 3E086 AD01 BA15 BB51 BB90 CA01                 4F100 AK07A AK64B BA02 BA25                       EH20 EH202 GB16 GB23                       JK07A JK07B JK09A JK09B                       JL04 JL11 JL13A JL13B                       JN02 YY00A YY00B

Claims (8)

[Claims] 1. At least a (I) layer mainly composed of a polypropylene resin and a (II) layer mainly composed of a propylene / α-olefin random copolymer formed on one surface of the (I) layer. A polypropylene-based co-extrusion film comprising two layers and satisfying the following properties (1) to (6). Characteristic (1): Heat seal strength between layers (II) is 10
The seal temperature Ts1 at which 0 g / 15 mm is reached is 125 ° C. or lower. Characteristic (2): Heat seal strength between layers (II) is 80
The sealing temperature Th, which is 0 g / 15 mm or more, is 132 ° C. or less. Characteristic (3): 1% tensile elastic modulus is 6000 to 9000 kg
/ Cm ² . Characteristic (4): The coefficient of static friction between layers (II) is 0.35 or less. Characteristic (5): Heat seal strength between layers (I) is 100
The seal temperature Ts2 of g / 15 mm satisfies the following equation. Ts2 ≧ Ts1 + 5 Characteristic (6): The relationship between the haze value (HZ (%)) and the film thickness (d (μm)) satisfies the following equation. (0.04 × d + 0.5) <HZ <(0.04 × d +
2.5) 2. The polypropylene-based co-extrusion film according to claim 1, wherein the thickness ratio of the (II) layer to the total film thickness is 0.01 to 0.5. 3. The polypropylene-based copolymer according to claim 1 or 2, wherein the propylene / α-olefin random copolymer is a propylene / α-olefin random copolymer polymerized by using a metallocene catalyst. Push film. 4. The polypropylene-based co-pushed film according to claim 1, wherein the α-olefin of the propylene / α-olefin random copolymer is ethylene. 5. A seal temperature Ts3 at which the heat-sealing strength between the layer (II) and the layer (I) is 100 g / 15 mm satisfies the following expression, which is suitable for an envelope-type sealed package. 5. The polypropylene-based co-extrusion film according to any one of 4 above. Ts1 <Ts3 ≦ 132 ° C. 6. The polypropylene-based co-extrusion film according to claim 1, which is used in an automatic packaging machine. 7. The polypropylene-based co-extrusion film according to claim 1, which is used for food packaging. 8. A completely hermetically sealed packaging bag comprising the polypropylene-based co-pressed film according to any one of claims 1 to 7.