JPH0952332A - Multilayer film for agriculture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer film for agriculture which has improved defogging continuity, dustproof characteristics, strength, and stretching work effifciency. SOLUTION: An outer layer comprising an ethylene/α-olefin copolymer (A) having a density of 0.925-0.940g/cm<3> , an intermediate layer comprising an ethylene/α-olefin copolymer (B) having a density of 0.880-0.910g/cm<3> and defogging agents (C), and an inner layer comprising an ethylene/α-olefin copper (D) having a density of 0.905-0.930g/cm<3> and defogging agents (C) are laminated one over another, and the relationship between the density (dA) of the copolymer (A) and the density (dD) of the copolymer (D) satisfies dA>=dD. Each of the layers may contain a high pressure process low density polyethylene.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to agricultural multilayer films.

[0002]

BACKGROUND OF THE INVENTION In greenhouse cultivation, tunnel cultivation, mulch cultivation and the like for agricultural forcing cultivation, a large amount of agricultural films made of various thermoplastic resins are generally used as a covering material. Such agricultural films include, for example, polyvinyl chloride film, ethylene / vinyl acetate copolymer film, polyethylene film and the like. Among them, polyvinyl chloride film has heat retention, transparency and toughness (mechanical strength). It is most often used because of its excellent properties.

However, the polyvinyl chloride film has a problem that it is slightly inferior in dustproof property and spreading workability, and that it produces a toxic gas when it is discarded by incineration. Here, "heat retention" absorbs and reflects the radiation emitted at night from the earth where the temperature rises due to the absorption of solar heat during the day, and the internal temperature (air temperature and ground temperature) of the house, tunnel, etc. The ability to hold

The term "dustproofness" refers to the ability to suppress the deterioration of the transparency of the film due to the adhesion of dust after use for a certain period of time. Further, the "spreading workability" indicates whether or not the film is sticky and easy to handle.

On the other hand, a film containing an ethylene / vinyl acetate copolymer as a main component is superior in waste treatment to a polyvinyl chloride film, but is inferior in toughness.
Spreading workability and dust resistance are insufficient.

Further, when polyethylene is applied to an agricultural film, this film has improved spreading workability and dustproof property as compared with the above-mentioned film containing an ethylene / vinyl acetate copolymer as a main component, but has not been improved yet. Inadequate,
There is a problem that it is inferior in toughness to a linear ethylene / α-olefin copolymer film.

Further, as an agricultural film in which the heat retention of the polyolefin resin film is improved by an additive, there is a coating film formed by adding silicon oxide to low density polyethylene or ethylene / vinyl acetate copolymer.

However, although such an agricultural film has improved heat retention of the polyethylene resin film, it has a higher toughness than that of the polyvinyl chloride film.
Insufficient transparency.

In order to improve the toughness of such a polyethylene resin film, an agricultural film utilizing the toughness of linear low-density polyethylene has recently been devised. For example, JP-A-58-160146 discloses an antifogging method in which a base layer mainly composed of linear low-density polyethylene and a layer made of a polyethylene resin or the like produced by a conventional production method containing a surfactant are laminated. Agricultural multilayer films having good properties have been proposed. Although this agricultural multi-layer film has improved toughness, its use has not been examined for the use of a resin or an additive having a higher heat retaining property, so that it has a considerably lower heat retaining property than a polyvinyl chloride film.

Japanese Patent Application Laid-Open No. 1-182037 discloses an agricultural multilayer (laminated) film. The agricultural multilayer film has an outer layer whose main component is a linear ethylene / α-olefin copolymer. The inner layer is formed of a polyethylene resin having an ethylene / vinyl acetate copolymer as a main component, an inorganic compound, and an antifogging agent. JP-A-1
The agricultural multi-layer film described in -182037 has good heat retention, dustproofness, spreadability, transparency,
It is said to have both weather resistance and extremely excellent toughness.

However, the conventional agricultural multilayer films described above have room for improvement in antifogging durability, dust resistance, toughness and the like. Therefore, there is a demand for an agricultural multi-layer film which is less susceptible to lapse of anti-fogging continuity than the conventional agricultural multi-layer film described above and which is excellent in dust resistance and toughness.

[0012]

The object of the present invention is to provide an agricultural multi-layer film which has a lower degree of anti-fogging continuity over time as compared with the above-mentioned conventional agricultural (multi-layer) film, and which is excellent in dust resistance and toughness. It is intended to be.

[0013]

The first agricultural multilayer film according to the present invention is obtained by copolymerizing [I] ethylene with an α-olefin having 4 to 12 carbon atoms, and has a density of 0.925 to 0.2. 9
40 g / cm ³ and a melt flow rate of 0.1 to
Outer layer consisting of ethylene / α-olefin copolymer (A) of 10 g / 10 min, [II] ethylene and 4 carbon atoms
Ethylene-α, which is obtained by copolymerizing with ~ 12-α-olefin and has a density of 0.880-0.910 g / cm ³ and a melt flow rate of 0.1-10 g / 10 min.
-An intermediate layer comprising an olefin copolymer (B) and an antifogging agent (C), and [III] ethylene and 4 to 1 carbon atoms
The density obtained by copolymerizing 2 with α-olefin is 0.9
A 05~0.930g / cm ^3, ethylene · alpha-olefin copolymer melt flow rate is 0.1 to 10 g / 10 min and (D), is an inner layer consisting of a anti-fogging agent (C) laminated And the density (d _A ) of the ethylene / α-olefin copolymer ( _A ) and the density (d _D ) of the ethylene / α-olefin copolymer (D) are d _A ≧ d _D Characterized by a satisfying relationship.

The preferred agricultural multilayer film according to the present invention is [I] ethylene and α-containing 4 to 12 carbon atoms.
Obtained by copolymerizing olefin with a density of 0.925 to
60% to 99% by weight of an ethylene / α-olefin copolymer (A) having a melt flow rate of 0.1 to 10 g / 10 minutes and a high pressure low density polyethylene (E) 40 of 0.940 g / cm ^3. An outer layer composed of a mixture of 1 to 1% by weight, obtained by copolymerizing [II] ethylene with an α-olefin having 4 to 12 carbon atoms and having a density of 0.880 to 0.9.
10 g / cm ³ and a melt flow rate of 0.1 to
From a mixture of 60 to 99% by weight of an ethylene / α-olefin copolymer (B) of 10 g / 10 minutes and 40 to 1% by weight of a high-pressure low density polyethylene (E), and an antifogging agent (C) Which is obtained by copolymerizing [III] ethylene with an α-olefin having 4 to 12 carbon atoms, has a density of 0.905 to 0.930 g / cm ³ , and a melt flow rate of 0.1. ~ 10g / 10min ethylene ethylene
-An outer layer formed by laminating an inner layer composed of a mixture of 60 to 99% by weight of an olefin copolymer (D) and 40 to 1% by weight of a high pressure low density polyethylene (E) and an antifogging agent (C) The density (d _AE ) of the mixture of the ethylene / α-olefin copolymer (A) as the forming resin and the high-pressure low density polyethylene (E), and the ethylene / α-olefin copolymer (D) of the inner layer forming resin ) And the density (d _DE ) of the mixture of the high-pressure low-density polyethylene (E) are: d _AE ≧ d _DE
It is characterized by having a relationship that satisfies.

The above ethylene / α-olefin copolymers (A), (B) and (D) are (i) molecular weight distributions (Mw / Mn: Mw = weight average molecular weight, Mn = number average) measured by GPC. Molecular weight) is in the range of 1.5 to 3.5, and (ii) n-decane-soluble component amount fraction (W
(% By weight)) and the density (d), W <80 × exp (−100 (d−0.88)) + 0.
(Iii) When the average value of the number of branches on the high molecular weight side by GPC-IR is B ₁ and the average value of the number of branches on the low molecular weight side is B ₂ , B ₁ ≧ B ₂ Preferably there is.

Further, a mixture of the ethylene / α-olefin copolymer (A) and the high-pressure low-density polyethylene (E), a mixture of the ethylene / α-olefin copolymer (B) and a high-pressure low-density polyethylene (E). ) And a mixture of the ethylene / α-olefin copolymer (D) and the high-pressure low-density polyethylene (E), (i) the molecular weight distribution measured by GPC (Mw / Mn: Mw = weight average molecular weight). , Mn = number average molecular weight) is in the range of 1.5 to 3.5, and (ii) n-decane-soluble component amount fraction (W) at 23 ° C.
(% By weight)) and the density (d), W <80 × exp (−100 (d−0.88)) + 0.
(Iii) When the average value of the number of branches on the high molecular weight side by GPC-IR is B ₁ and the average value of the number of branches on the low molecular weight side is B ₂ , B ₁ ≧ B ₂ Preferably there is.

Further, the agricultural multilayer film according to the present invention as described above has (i) Elmendorf tear strength of 90 kg / cm or more in the MD direction and 90 in the TD direction.
kg / cm or more, (ii) Dart impact strength at a thickness of 100 μm is 900 g or more, (iii) Tensile breaking strength is 350 kg / cm ² or more in MD direction, and 350 kg / cm in TD direction. It is preferably ² or more.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The agricultural multilayer film according to the present invention will be specifically described below. The agricultural multilayer film according to the present invention is a three-layer laminated film including an outer layer, an intermediate layer, and an inner layer.

Outer Layer The outer layer constituting the agricultural multilayer film according to the present invention is formed of an ethylene / α-olefin copolymer (A).

[Ethylene / α-olefin copolymer (A)] Ethylene / α for forming the outer layer used in the present invention
The olefin copolymer (A) is a copolymer comprising ethylene and an α-olefin having 4 to 12 carbon atoms.

The α-olefin having 4 to 12 carbon atoms used for the copolymerization with ethylene is specifically 1-
Butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene and the like. Among them, α-olefins having 4 to 10 carbon atoms, particularly α-olefins having 4 to 6 carbon atoms are preferred.

In the present invention, the above ethylene / α-olefin copolymer (A) can be used alone or in combination of two or more kinds. The ethylene / α-olefin copolymer (A) used in the present invention has a constitutional unit derived from ethylene of 50% by weight or more and 100% by weight or more.
Less than 55, preferably from 99 to 99% by weight, more preferably from 65 to 98% by weight, particularly preferably from 70 to 96% by weight, wherein the constituent units derived from α-olefins having 4 to 12 carbon atoms comprise 50 or less. Wt% or less, preferably 1-4
It is desirable to be present in an amount of 5% by weight, more preferably 2-35% by weight, particularly preferably 4-30% by weight.

The composition of the ethylene / α-olefin copolymer is usually determined by measuring the ¹³ C-NMR spectrum of a sample obtained by uniformly dissolving about 200 mg of the copolymer in 1 ml of hexachlorobutadiene in a 10 mmφ sample tube at the measurement temperature. 120
° C, measurement frequency 25.05 MHz, spectrum width 150
0Hz, pulse repetition time 4.2sec., Pulse width 6μse
It is determined by measuring under the measurement conditions of c.

The ethylene / α-olefin copolymer (A) for forming the outer layer has a density of 0.925 to 0.940 g / c.
m ³ , preferably in the range of 0.927 to 0.935 g / cm ³ . When the density of the ethylene / α-olefin copolymer (A) is less than 0.925 g / cm ³ , the adhesion of dust and dirt to the outer layer increases, and the dust resistance tends to be impaired.

The density is 2.16 at 190 ° C.
The strand obtained at the time of melt flow rate (MFR) measurement under a kg load is heat-treated at 120 ° C. for 1 hour, gradually cooled to room temperature over 1 hour, and measured with a density gradient tube.

The melt flow rate (MFR; ASTM) of this ethylene / α-olefin copolymer (A)
D 1238-65T, 190 ° C, load 2.16kg)
Is 0.1 to 10 g / 10 minutes, preferably 0.1 to 5 g
/ 10 minutes, more preferably 0.5 to 2 g / 10 minutes.

Molecular weight distribution (Mw / M of this ethylene / α-olefin copolymer (A) measured by GPC
n: Mw = weight average molecular weight, Mn = number average molecular weight)
It is in the range of 1.5 to 3.5, preferably 2.0 to 3.0.

The molecular weight distribution (Mw / Mn) was measured as follows using GPC-150C manufactured by Millipore. The separation column is TSK GNH HT,
The column size is 72 mm in diameter and 600 mm in length,
The column temperature was 140 ° C., O-dichlorobenzene (manufactured by Wako Pure Chemical Industries, Ltd.) as the mobile phase, and 0.025% by weight of BHT (manufactured by Takeda Pharmaceutical Co., Ltd.) as an antioxidant were used. It was moved at 0 ml / min, the sample concentration was 0.1% by weight, the sample injection amount was 500 microliters, and a differential refractometer was used as a detector. Standard polystyrene is
For a molecular weight of Mw <1000 and Mw> 4 × 10 ⁶ , Tosoh Corp.
^{As for 6} , a pressure chemical product was used.

Further, the ethylene / α-olefin copolymer (A) has a n-decane-soluble component fraction (W
(Wt%)) and the density (d) satisfy the relationship shown below.

W <80 × exp (-100 (d-0.8
8)) +0.1 In addition, the amount of n-decane soluble component of the ethylene / α-olefin copolymer (the smaller the soluble component, the narrower the composition distribution)
The measurement of ethylene-α-olefin copolymer was about 3 g
After adding to 450 ml of n-decane and dissolving at 145 ° C., 23
It is carried out by cooling to ℃, removing the n-decane-insoluble portion by filtration, and recovering the n-decane-soluble portion from the filtrate.

Further, the ethylene / α-olefin copolymer has a temperature [Tm (° C.)] and a density [d] at the maximum peak position of the endothermic curve measured by a differential scanning calorimeter (DSC).
(G / cm ³ )], Tm <400 × d-250, preferably Tm <450 × d-297, more preferably Tm <500 × d-344, and most preferably Tm <550 × d-391. It is desirable to satisfy.

The temperature (Tm) at the maximum peak position of the endothermic curve measured by a differential scanning calorimeter (DSC) is
Approximately 5mg of sample is packed in aluminum pan and 200 ℃ at 10 ℃ / min
It is determined from the endothermic curve when the temperature is raised to 200 ° C., the temperature is held at 200 ° C. for 5 minutes, the temperature is lowered to room temperature at 20 ° C./minute, and then the temperature is raised at 10 ° C./minute. Measured by Perkin Elmer
Use a DSC-7 type device.

Thus, the relationship between the n-decane-soluble component amount fraction (W) and the density (d), and the temperature (Tm) at the maximum peak position in the endothermic curve measured by the differential scanning calorimeter (DSC). It can be said that the ethylene / α-olefin copolymer having the above-mentioned relationship between the () and the density (d) has a narrow composition distribution.

Further, ethylene / α-used in the present invention
The olefin copolymer (A) satisfies B ₁ ≧ B ₂ when the average value of the number of branches on the high molecular weight side by GPC-IR is B ₁ and the average value of the number of branches on the low molecular weight side is B ₂ .

Here, the average value (B ₁ ) of the number of branches on the high molecular weight side by GPC-IR means that the cumulative weight fraction of the polymer elution amount classified by GPC is 15 to 85%.
The measurement value group of the number of branches measured for each fraction in the range of (ie, the high molecular weight region excluding 15% and the high molecular weight region excluding 15%) was divided into two by the molecular weight at the peak position of the GPC elution curve. It is the average of the values on the high molecular weight side. On the other hand, the average value of the number of branches on the low molecular weight side (B
₂ ) is the average value on the low molecular weight side of the two divided products.

The measurement conditions of B ₁ and B ₂ are as follows. Measuring device: Perkin Elmer 1760X Column: TSK gel GMH-HT (7.5mmI.
D. × 600 mm) × 1 eluent: o-dichlorobenzene (ODCB) containing 0.05% of MP-J [manufactured by Wako Pure Chemical Industries, ex
tra pure grade] Column temperature: 140 ° C. Sample concentration: 0.1% (weight / volume) Injection volume (inj.volume): 100 microliter detector: MCT Resolution: 8 cm ^-1 The B ₁ and B ₂ is the Ethylene and α in such a relationship
-The olefin copolymer (A) has a narrow composition distribution and a small amount of a low polymer, and thus has a low stickiness. Therefore, when the above-mentioned ethylene / α-olefin copolymer (A) is used for the outer layer of a multilayer film, an agricultural film having a multilayer structure excellent in dust resistance can be obtained.

Further, since the outer layer made of the ethylene / α-olefin copolymer (A) has a very small decrease in light transmittance with time, an agricultural multilayer film having such an outer layer can be used for a long period of time. In addition to being capable of being stretched, the outer layer of the multilayer film can be thinned and the weight of the multilayer film can be reduced because it has excellent mechanical properties.

The ethylene / α-olefin copolymers (A) as described above are disclosed in JP-A-6-9724 and JP-A-6-9724.
In the presence of a so-called metallocene-based olefin polymerization catalyst containing a metallocene catalyst component described in JP-A-136195, JP-A-6-136196, JP-A-6-207057, etc., ethylene and carbon atoms having 4 carbon atoms are used.
And 12 of the α- olefin, the density of the resulting copolymer can be produced by copolymerizing such a 0.925~0.940g / cm ^3.

Such a metallocene catalyst usually contains at least one ligand having a cyclopentadienyl skeleton.
Metallocene catalyst component (a) comprising a transition metal compound of Group IVB of the periodic table, an organoaluminum oxy compound catalyst component (b), a particulate carrier (c), and, if necessary, an organoaluminum compound catalyst component (d ), An ionized ionic compound formed from the 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, the groups having two cyclopentadienyl skeletons among them are ethylene, propylene and the like. An alkylene group of
They may be bonded via a substituted alkylene group such as isopropylidene diphenylmethylene, a silylene group or a dimethylsilylene group, a substituted silylene group such as a diphenylsilylene group, a methylphenylsilylene group and the like.

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.

Examples of the hydrocarbon group having 1 to 12 carbon atoms include an alkyl group such as a methyl group, a cycloalkyl group such as a cyclopentyl group, an aryl group such as a phenyl group, and an aralkyl group such as a benzyl group.

Specific examples of the ligand represented by SO ₃ R include a P-toluenesulfonato group, a methanesulfonato group, and a trifluoromethanesulfonato group. As the organoaluminum oxy compound catalyst component (b), aluminoxane is preferably used. Specifically, methyl aluminoxane, ethyl aluminoxane, methyl ethyl aluminoxane having a repeating unit represented by the formula -Al (R) O- where 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 particulate carrier (c) used in the preparation of the catalyst for olefin polymerization is an inorganic or organic compound and has a particle size of usually 10 to 300 μm.
The degree is about 20 to 200 μm, and preferably a granular or fine particle solid.

The inorganic carrier is preferably a porous oxide, and specifically, SiO ₂ , Al ₂ O ₃ , MgO, Zr.
O ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, S
Examples thereof include nO _{2 and the} like, or a mixture thereof. The inorganic oxide contains a small amount of a carbonate such as Na ₂ CO _3, a sulfate such as Al ₂ (SO ₄ ) ₃ , a nitrate such as KNO ₃ , and an oxide such as Li ₂ O. It doesn't matter.

The properties of such a carrier differ depending on the type and production method, but the carrier preferably used in the present invention has a specific surface area of 50 to 1000 m ² / g, preferably 1.
00-700 m ² / g, and the pore volume is 0.3-2.
It is preferably 5 cm ³ / g.

This carrier may contain 100 to 100, if necessary.
It is used by firing at 0 ° C, preferably 150 to 700 ° C. The organic compound used as the fine particle carrier may be a (co) polymer produced mainly from an α-olefin having 2 to 14 carbon atoms such as ethylene or 4-methyl-1-pentene, or vinylcyclohexane. An example is a (co) polymer produced mainly from styrene.

Specific examples of the organoaluminum compound catalyst component (d) used in the preparation of the olefin polymerization catalyst include trialkylaluminum such as trimethylaluminum, alkenylaluminum such as isoprenylaluminum, and dimethylaluminum. Examples thereof include dialkylaluminum halides such as chloride, alkylaluminum sesquihalides such as methylaluminum sesquichloride, alkylaluminum dihalides such as methylaluminum dichloride, and alkylaluminum hydrides such as diethylaluminum hydride.

Examples of the ionizable ionic compound catalyst component (e) include triphenylboron, MgCl ₂ and Al described in USP-5,321,106.
Lewis acids such as ₂ O ₃ and SiO ₂ —Al ₂ O ₃ ; ionic compounds such as triphenylcarbenium tetrakis (pentafluorophenyl) borate; carborane compounds such as dodecaborane and bis-n-butylammonium (1-carbedodeca) borate Is mentioned.

The ethylene / α-olefin copolymer (A) used in the present invention includes the metallocene catalyst component (a), the organoaluminum oxy compound catalyst component (b), the fine particle carrier (c), and If necessary, 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. , Ethylene and α-C4-12
It can be obtained by copolymerizing with an olefin.

In the slurry polymerization method or the solution polymerization method, an inert hydrocarbon may be used as the solvent, or the olefin itself may be used as the solvent. When carrying out the polymerization, the above-mentioned metallocene-based olefin polymerization catalyst is usually used in a concentration of 10 ^-8 , based on the concentration of the transition metal atom in the polymerization reaction system.
-10 ^-3 gram atom / liter, preferably 10 ^{-7 -1
Preferably,} it is used in an amount of ^0-4 grams atom / liter.

In addition, in the polymerization, in addition to the organoaluminum oxy compound catalyst component (b) and the organoaluminum compound catalyst component (c) supported on the carrier, the organoaluminum oxy compound catalyst component (b) not further supported is added. And / or the organoaluminum compound catalyst component (c) may be used. In this case, the aluminum atom (Al) derived from the unsupported organoaluminum oxy compound catalyst component (b) and / or the organoaluminum compound catalyst component (c) and the transition metal atom (a) derived from the metallocene catalyst component (a) ( M) atomic ratio [Al
/ M] is in the range of 5 to 300, preferably 10 to 200, and more preferably 15 to 150.

The polymerization temperature in the slurry polymerization method is usually -50 to 100 ° C, preferably 0 to 90 ° C, and the polymerization temperature in the solution polymerization method is usually -50 to 50 ° C.
0 ° C, preferably in the range of 0 to 400 ° C. The polymerization temperature in the gas phase polymerization method is usually 0 to 120 ° C, preferably 20 to 100 ° C.

The polymerization pressure is usually atmospheric pressure to 100 kg /
It is under a pressure condition of cm ² , preferably ² to 50 kg / cm ² , and the polymerization can be carried out by any of batch system, semi-continuous system and continuous system.

In the present invention, when preparing the ethylene / α-olefin copolymer (A), if necessary,
(1) Multistage polymerization, (2) Multistage polymerization of liquid phase and gas phase, or (3)
Means such as performing polymerization in a gas phase after performing preliminary polymerization in a liquid phase can be employed. In the present invention,
The multistage polymerization of (1) above is preferred.

Examples of the multistage polymerization method include the following multistage polymerization methods. [1] A metallocene catalyst component comprising at least one compound selected from the group IVB transition metal compounds of the periodic table containing a ligand having a cyclopentadienyl skeleton represented by the above general formula [I], and an organic compound. In the presence of a metallocene catalyst containing an aluminum oxy compound catalyst component, ethylene is copolymerized with an α-olefin having 4 to 12 carbon atoms to produce an ethylene / α-olefin copolymer (A-1). In a polymerization vessel different from the step and [2] the polymerization vessel in which the above-mentioned copolymerization reaction is carried out, the above-mentioned general formula [I]
And a metallocene catalyst component comprising at least one compound selected from the group IVB transition metal compounds of the periodic table containing a ligand having a cyclopentadienyl skeleton represented by In the presence of a system catalyst, ethylene and C4
And α-olefin of 12
And a step of producing an olefin copolymer (A-2). However, the manufacturing conditions in the step [1] are different from the manufacturing conditions in the step [2]. Such production conditions include, for example, the type and amount of the metallocene catalyst component, the type and amount of the organoaluminum oxy compound catalyst component, and the molar ratio of ethylene to α-olefin.

The metallocene catalyst used in the copolymerization step [1] and / or [2] is added to the metallocene catalyst component (a) and the organoaluminum oxy compound catalyst component (b), and the organoaluminum compound catalyst component (d). ) Or a solid catalyst in which the metallocene catalyst component (a) and the organoaluminum catalyst component (b) are supported on the fine-particle carrier (c). Further, these metallocene catalysts are prepolymerized catalysts obtained by prepolymerizing olefins on a solid catalyst component in which a metallocene catalyst component (a) and an organoaluminum catalyst component (b) are supported on a particulate carrier (c). May be. Further, these metallocene-based catalysts include a catalyst comprising the above-mentioned solid catalyst (solid catalyst component) and an organoaluminum compound catalyst component (d), or the above-mentioned prepolymerization catalyst (preliminary polymerization catalyst component) and an organoaluminum compound catalyst component (d). ) May be used.

In this multistage polymerization method, the above ethylene / α-olefin copolymer (A-1) is first produced by using a plurality of polymerization vessels connected in series, and then ethylene / α
-Introducing the ethylene / α-olefin copolymer (A-1) into a polymerization vessel different from the polymerization vessel used for producing the olefin copolymer (A-1), the ethylene / α-olefin copolymer (A The ethylene / α-olefin copolymer (A-2) can be produced in the presence of -1).

Further, a plurality of polymerization vessels are connected in parallel, and ethylene / α-olefin copolymers (A-1) and (A-2) are produced in each of the polymerization vessels, and then both copolymers are produced. Can also be blended.

[High-Pressure Low Density Polyethylene (E)] The high-pressure low-density polyethylene (E) used in the present invention for forming an outer layer has a melt flow rate (MFR; A).
STM D 1238, 190 ° C., load 2.16 kg) 0.1 to 100 g / 10 min, density 0.915 to 0.9
It is preferable that the swell ratio is 35 g / cm ³ and the swell ratio is 60% or less.

The high-pressure process low-density polyethylene (E) is mixed in an amount of 1 to 100% by weight of the total amount of the ethylene / α-olefin random copolymer (A) and the high-pressure process low-density polyethylene (E). 40% by weight, preferably 1
It is desirable that the content is -20% by weight.

The density of the high-pressure low-density polyethylene (E) can be determined by the same method as the method for measuring the density of the ethylene / α-olefin copolymer (A) described above. Further, the swell ratio is obtained as follows.

The diameter at the position of 5 mm from the tip of the strand obtained at the time of measuring the melt flow rate is measured with a micrometer as the diameter (mm) of the sample. Then, the swell ratio is calculated by the following formula.

Swell ratio (%) = [(L ₁ / L ₀ ) −1] × 100 L ₁ : Sample diameter (mm) L ₀ : Orifice diameter (= 2.0955 mm) High density low density as described above Polyethylene (E) can be produced by a conventionally known high pressure method.

[Other Components] The above-mentioned ethylene / α-olefin copolymer (A) for forming the outer layer and the low-density polyethylene (E) prepared by the high pressure method are added to the conventionally known weather stabilizers, antifogging agents, antifog agents, Additives such as an inorganic compound, an antistatic agent, and a heat stabilizer can be added within a range that does not impair the object of the present invention.

The weather resistance stabilizer is roughly classified into an ultraviolet absorber and a light stabilizer. The light stabilizer is more effective for thin agricultural films and has a great effect of improving the weather resistance stability. As the light stabilizer, a conventionally known light stabilizer can be used,
Among them, hindered amine light stabilizers (HALS; Hinder
ed Amine Light Stabilizers) are preferably used.

As the hindered amine stabilizer, the following compounds are specifically used. (1) Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, (2) Dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-succinate Tetramethylpiperidine polycondensate, (3) tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, (4) 2,2,6, 6-tetramethyl-4-piperidinyl benzoate, (5) bis- (1,2,6,6-tetramethyl-4
-Piperidinyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate, (6) bis (N-
Methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, (7) 1,1 ′-(1,2-ethanediyl) bis (3,3,
5,5-Tetramethylpiperazinone), (8) (Mixed
2,2,6,6-tetramethyl-4-piperidyl / tridecyl)-
1,2,3,4-butanetetracarboxylate, (9) (mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate ,
(10) Mixed {2,2,6,6-tetramethyl-4-piperidyl / β, β, β ′, β′-tetramethyl-3-9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl｝ -1,2,
3,4-butanetetracarboxylate, (11) mixed {1,2,2,6,6-pentamethyl-4-piperidyl / β, β,
β ', β'-tetramethyl-3-9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl} -1,2,3,4-butanetetracarboxylate, (12 ) N, N'-Bis (3-aminopropyl) ethylenediamine-2-4-bis [N-butyl-N-
(1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6
-Chloro-1,3,5-triazine condensate, (13) of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine and 1,2-dibromoethane Condensate, (14)
[N- (2,2,6,6-tetramethyl-4-piperidyl) -2-methyl-2- (2,2,6,6-tetramethyl-4-piperidyl) imino] propionamide and the like.

These hindered amine light stabilizers are
They can be used alone or in combination of two or more. Such a light stabilizer is used in an amount of 0.005 to 5 based on 100 parts by weight of the ethylene / α-olefin copolymer (A).
It is used in an amount of 0.001 to 2 parts by weight, preferably 0.005 to 2 parts by weight, and more preferably 0.01 to 1 part by weight.

Specific examples of the ultraviolet absorber include salicylic acid type ultraviolet absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate and p-octylphenyl salicylate; 2,4-dihydroxybenzophenone and 2-hydroxy-4. -Methoxybenzophenone, 2-hydroxy-4
-Octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy- Benzophenone-based UV absorbers such as 5-sulfobenzophenone; 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-tert-butylphenyl) benzotriazole, 2-
(2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5- Benzotriazole-based absorbents such as chlorobenzotriazole and 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole; 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate And cyanoacrylate-based ultraviolet absorbers such as ethyl-2-cyano-3,3'-diphenylacrylate.

The ultraviolet absorber is 0.005 to 100 parts by weight of the ethylene / α-olefin copolymer (A).
5 parts by weight, preferably 0.005 to 2 parts by weight, more preferably 0.01 to 1 part by weight.

Specific examples of the antifogging agent include sorbitan monostearate, sorbitan distearate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan monobehenate, sorbitan dibehenate, sorbitan monolaurate and sorbitan. Sorbitan surfactants such as dilaurate; glycerin monolaurate,
Glycerin surfactants such as glycerin dilaurate, diglycerin monopalmitate, diglycerin dipalmitate, glycerin monostearate, glycerin distearate, diglycerin monostearate, diglycerin distearate; polyethylene glycol monostearate; Polyethylene glycol-based surfactants such as polyethylene glycol monopalminate; trimethylolpropane-based surfactants such as trimethylolpropane monostearate; pentaerythritol-based surfactants such as pentaerythritol monopalmitate and polyoxyethylene sorbitan monostearate. And polyoxyethylene sorbitan distearate, mono- and distearate of sorbitan-diglycerin condensate, and the like. These can be used alone or in combination of two or more.

The antifogging agent is used in an amount of 0.05 to 5 parts by weight, preferably 0.1 to 4 parts by weight, and more preferably 0.5 to 100 parts by weight of the ethylene / α-olefin copolymer (A). Used in a proportion of 3 parts by weight.

The inorganic compound used for forming the outer layer of the multilayer film is Mg, Ca, Al which is effective as a heat retaining agent.
And inorganic oxides containing at least one atom of Si, inorganic hydroxides, hydrotalcites, and the like.

Specifically, SiO ₂ , Al ₂ O ₃ , Mg
Inorganic oxides such as O and CaO; Al (OH) ₃ , Mg (O
H) ₂ , inorganic hydroxide such as Ca (OH) ₂ ; Formula M 2 ⁺ _1-x Al _x (OH) ₂ (A ^n- ) _{x / n} · mH ₂ O [wherein M ²⁺ is It is a divalent metal ion of Mg, Ca, or Zn, and A ^n- is Cl ⁻ , Br ⁻ , I ⁻ , NO ₃ ²⁻ , C.
^{_{lO 4-, SO 4 2-, CO}} 2 2-, SiO 3 2-, HPO
An anion such as ₄ ²⁻ , HBO ₃ ²⁻ , PO ₄ ²⁻ , x
Is a numerical value that satisfies the condition of 0 <x <0.5, and m
Is a numerical value satisfying the condition of 0 ≦ m ≦ 2], and hydrotalcites such as a fired product thereof. Among these, hydrotalcites are preferable, and a calcined product of the inorganic composite compound represented by the above formula is particularly preferable.

The above inorganic compounds can be used alone or in combination of two or more kinds. It is desirable that the average particle size of the inorganic compound is 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less.

When the average particle size of the inorganic compound is within the above range, a multilayer film having good transparency can be obtained. In the present invention, the inorganic compound is ethylene α-
1 to 100 parts by weight of the olefin copolymer (A)
It is used in a proportion of 20 parts by weight, preferably 1 to 18 parts by weight, more preferably 2 to 15 parts by weight.

When the inorganic compound is used in the above proportion when forming the outer layer of the multilayer film, a multilayer film excellent in heat retention can be obtained. Intermediate layer The intermediate layer that constitutes the agricultural multilayer film according to the present invention,
It is formed from an ethylene / α-olefin copolymer (B) and an antifogging agent (C).

[Ethylene / α-olefin Copolymer (B)] Ethylene /.
The α-olefin copolymer (B) is a copolymer composed of ethylene and an α-olefin having 4 to 12 carbon atoms, and has a density of 0.880 to 0.910 g / cm ³ , preferably 0.890. ~ 0.905 g / cm ³ , except that the ethylene / α-olefin copolymer (A) described above is used.
Is the same as If the density of the ethylene / α-olefin copolymer (B) exceeds 0.910 g / cm ³ and becomes too large, the obtained film becomes stiff and the elongation is insufficient, so that the spreading workability is deteriorated or the stretching is finished. Inconveniences such as wrinkles are easily formed on the film.

The ethylene / α-olefin copolymer (B) as described above is prepared by the same method as the above-mentioned method for producing the ethylene / α-olefin copolymer (A) and the presence of the metallocene-based olefin polymerization catalyst. It can be produced by copolymerizing ethylene with an α-olefin having 4 to 12 carbon atoms so that the resulting copolymer has a density of 0.880 to 0.910 g / cm ^3. .

[Anti-fog Agent (C)] The anti-fog agent (C) used in the present invention is a conventionally known anti-fog agent, and its specific examples are as described above.

The antifogging agent (C) is used in an amount of 0.05 to 5 with respect to 100 parts by weight of the ethylene / α-olefin copolymer (B).
Parts by weight, preferably 0.1 to 4 parts by weight, more preferably 0.5 to 3 parts by weight.

[High Pressure Low Density Polyethylene (E)] In the present invention, the high pressure low density polyethylene (E) optionally used for forming the intermediate layer is the high pressure low density polyethylene (E) used for forming the outer layer described above. ) Is the same.

The mixing amount of the high-pressure low-density polyethylene (E) is 1 to 40 with respect to 100% by weight of the total amount of the ethylene / α-olefin copolymer (B) and the high-pressure low-density polyethylene (E). It is desirable that the content is wt%, preferably 1 to 20 wt%.

[Other Components] The ethylene / α-olefin copolymer (B) for forming the intermediate layer, the antifogging agent (C), and the high-pressure low-density polyethylene (E) may be used, if necessary, conventionally known. Additives such as a weather resistance stabilizer, an inorganic compound, an antifog agent, an antistatic agent, and a heat stabilizer can be added within a range that does not impair the object of the present invention.

The weather resistance stabilizer used in the formation of the intermediate layer is the same as the ultraviolet absorber and the light stabilizer optionally used in the formation of the outer layer. The light stabilizer is 0.005 to 5 parts by weight, preferably 0.005 parts, relative to 100 parts by weight of the ethylene / α-olefin copolymer (B).
To 2 parts by weight, more preferably 0.01 to 1 part by weight.

The ultraviolet absorber is 0.005 to 100 parts by weight of the ethylene / α-olefin copolymer (B).
5 parts by weight, preferably 0.005 to 2 parts by weight, more preferably 0.01 to 1 part by weight.

The inorganic compound used for forming the intermediate layer is the same as the inorganic compound used as necessary for forming the outer layer. The inorganic compound is ethylene α
-1 to 100 parts by weight of olefin copolymer (B)
-20 parts by weight, preferably 1-18 parts by weight, more preferably 2-15 parts by weight.

Inner Layer The inner layer constituting the multilayer film for agriculture according to the present invention is formed of an ethylene / α-olefin copolymer (D) and an antifogging agent (C).

[Ethylene / α-olefin copolymer (D)] Ethylene / α for forming the inner layer used in the present invention
-The olefin copolymer (D) is a copolymer comprising ethylene and an α-olefin having 4 to 12 carbon atoms,
Except that the density is 0.905 to 0.930 g / cm ³ , preferably 0.910 to 0.920 g / cm ³
It is the same as the above-mentioned ethylene / α-olefin copolymer (A).

In the present invention, the density (d _A ) of the ethylene / α-olefin copolymer (A) for forming the outer layer,
Ethylene / α-olefin copolymer for inner layer formation (D)
And a density (d _D ) satisfying d _A ≧ d _D.

Therefore, the antifogging agent (C) contained in the intermediate layer of the agricultural multilayer film of the present invention gradually migrates to the inner layer composed of the ethylene / α-olefin copolymer (D) having a low density. Therefore, the antifogging property of the inner layer can be maintained.

If the density of the ethylene / α-olefin copolymer (D) for forming the inner layer is too low than 0.905 g / cm ³ , the stickiness on the inner surface of the film becomes large, and the pipe is not suitable for pipes in a pipe house. Slippage becomes worse and the spreading workability is impaired.

The ethylene / α-olefin copolymer (D) as described above is prepared by the same method as the above-mentioned method for producing the ethylene / α-olefin copolymer (A) and the presence of the metallocene-based olefin polymerization catalyst. It can be produced by copolymerizing ethylene with an α-olefin having 4 to 12 carbon atoms so that the resulting copolymer has a density of 0.905 to 0.930 g / cm ^3. .

[Anti-fog Agent (C)] The anti-fog agent (C) used in the present invention is a conventionally known anti-fog agent, and specific examples thereof are as described above.

The antifogging agent (C) is used in an amount of 0.05 to 5 with respect to 100 parts by weight of the ethylene / α-olefin copolymer (D).
Parts by weight, preferably 0.1 to 4 parts by weight, more preferably 0.5 to 3 parts by weight.

[High Pressure Low Density Polyethylene (E)] In the present invention, the high pressure low density polyethylene (E) optionally used for forming the inner layer is the high pressure low density polyethylene used for forming the outer layer and the intermediate layer described above. Same as (E).

The mixing amount of the high-pressure low-density polyethylene (E) is 1 to 40 with respect to 100% by weight of the total amount of the ethylene / α-olefin copolymer (D) and the high-pressure low-density polyethylene (E). It is desirable that the content is wt%, preferably 1 to 20 wt%.

[Other components] Ethylene for forming the inner layer
If necessary, additives such as conventionally known weather resistance stabilizers, inorganic compounds, antifog agents, antistatic agents, heat stabilizers, etc. are added to the α-olefin copolymer (D) and the high-pressure low-density polyethylene (E). Can be blended within a range that does not impair the object of the present invention. That is, these additives are used in an amount that does not prevent the antifogging agent (C) contained in the intermediate layer of the multilayer film from being gradually transferred to the inner layer.

The weather resistance stabilizer used for forming the inner layer is the same as the ultraviolet absorber and the light stabilizer which are optionally used for forming the outer layer. The light stabilizer is used in an amount of 0.005 to 5 parts by weight, preferably 0.005 parts by weight, based on 100 parts by weight of the ethylene / α-olefin copolymer (D).
To 2 parts by weight, more preferably 0.01 to 1 part by weight.

The ultraviolet absorber is 0.005 to 100 parts by weight of the ethylene / α-olefin copolymer (D).
5 parts by weight, preferably 0.005 to 2 parts by weight, more preferably 0.01 to 1 part by weight.

The inorganic compound used for forming the inner layer is the same as the inorganic compound used as necessary for forming the outer layer. The inorganic compound is ethylene α
-1 to 100 parts by weight of olefin copolymer (D)
It is used in a proportion of up to 3 parts by weight.

When the inorganic compound is used in the above proportion in forming the inner layer of the multilayer film, a multilayer film excellent in heat retention can be obtained. Multilayer film The agricultural multilayer film according to the present invention, which comprises the outer layer, the intermediate layer and the inner layer as described above, usually has an outer layer thickness of 3 to 1.
00 μm, preferably 10 to 80 μm, more preferably 20 to 70 μm, and the thickness of the intermediate layer is 10 to 10 μm.
150 μm, preferably 20 to 120 μm, more preferably 30 to 100 μm, and the inner layer has a thickness of 3
To 100 μm, preferably 10 to 80 μm, more preferably 20 to 70 μm, and the total thickness of these layers is 30 to 200 μm, preferably 50 to 18 μm.
It is in the range of 0 μm, more preferably 70 to 150 μm.

In the present invention, the thickness ratio (outer layer [I] / intermediate layer [II] / inner layer [III]) of the outer layer [I], the intermediate layer [II] and the inner layer [III] is 0. 2-4
It is desirable that it is / 1 to 10/1, preferably 0.5 to 2/2 to 6/1.

The agricultural multilayer film according to the present invention has the following physical properties and characteristics. (I) Elmendorf tear strength is 90kg in MD
/ Cm or more, preferably 100 kg / cm or more,
Also, 90 kg / cm or more in the TD direction, preferably 10
It is 0 kg / cm or more. (Ii) The dirt impact strength at a thickness of 100 μm is 9
The amount is 00 g or more, preferably 1,000 g or more. (Iii) Tensile strength at break is 350 kg / c in MD direction
m ² or more, preferably 370 kg / cm ² or more,
Further, it is 350 kg / cm ² or more, preferably 370 kg / cm ² or more in the TD direction. (Iv) The initial light transmittance at a thickness of 100 μm is 90% or more, preferably 92% or more, and the outdoor exposure is 12
The light transmittance after 0 days is 85% or more, preferably 87% or more.

In addition, the 50 μm-thick agricultural multilayer film according to the present invention has a gloss of usually 60% or more and a haze of 15% or less. The film gloss is
It was measured at an incident angle of 60 ° C. according to ASTM D523. The haze of the film is ASTM D 1003.
It was measured according to -61.

Preparation of Multilayer Film The agricultural multilayer film according to the present invention as described above is prepared by mixing the polyethylene resin used in each layer of the multilayer film and the components such as the above-mentioned additives, and mixing them with a Banbury mixer, a roll mill or an extrusion machine. It can be prepared by melt mixing in a machine or the like, and then laminating an outer layer, an intermediate layer and an inner layer by a coextrusion inflation method or a coextrusion T-die method.

[0110]

According to the present invention, it is possible to provide an agricultural multilayer film having excellent antifogging durability, dust resistance and toughness as compared with the above-mentioned conventional agricultural (multilayer) film. . In addition, the agricultural multilayer film according to the present invention is lightweight, and has a low amount of low molecular weight components in the polymer used. Is advantageous. In particular, ethylene, which forms the outer layer
Since the α-olefin copolymer (A) has a higher density than the ethylene / α-olefin copolymer (D) forming the inner layer, the antifogging durability is excellent.

Since the agricultural multilayer film according to the present invention has the effects as described above, it can be spread in agricultural and horticultural facilities such as houses and tunnels and can be used for cultivation of useful crops for a long period of time.

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. In addition, evaluation of the agricultural multilayer film in an Example and a comparative example was performed as follows. (1) Anti-fog property A pipe house (frontage 3.6) in which a multilayer film was installed in a test field of Mitsui Petrochemical Industry Co., Ltd. in Sodegaura City, Chiba Prefecture.
m, depth 20 m), and from October 1994 1
A spreading test was conducted for 6 months until April 995. During the test period, water was sprayed almost every week to keep the water in the house. After a predetermined time, the state of water droplets adhering to the inner surface of the film was observed and evaluated as the antifogging property of the film.

<Three-stage evaluation> O: No water droplet is observed in the flowing state. Δ: Large water droplets partially adhere to the film.

X: Fine water droplets are attached to almost the entire surface of the film. (2) Elmendorf tear strength: longitudinal and transverse strengths were measured by a method based on JIS Z-1702. (3) Dirt impact strength Dirt impact strength was obtained by performing an impact test in accordance with JIS Z 1707 (dart tip diameter 38 mm). (4) Tensile Breaking Point Strength The tensile breaking point strength is based on JIS K 6781, and under the following conditions, in the MD direction and the TD direction of the multilayer film, a constant crosshead moving speed type tensile tester (manufactured by Instron). It is a value obtained by conducting a tensile test using.

[Test Conditions] Sample: JIS K 6781 Ambient temperature: 23 ° C. Tensile speed: 500 mm / min

[0116]

[Reference Example 1] Preparation of ethylene / 1-hexene copolymer [Preparation of catalyst for olefin polymerization] 5.0 kg of silica dried at 250 ° C for 10 hours was suspended in 80 liters of toluene, and then cooled to 0 ° C. Cool. Thereafter, 28.7 l of a toluene solution of methylaluminoxane (Al; 1.33 mol / l) was added dropwise over 1 hour. At this time, the temperature in the system was kept at 0 ° C. Subsequently, the reaction was carried out at 0 ° C. for 60 minutes, then the temperature was raised to 95 ° C. over 1.5 hours, and the reaction was carried out at that temperature for 20 hours. Then, the temperature was lowered to 60 ° C., and the supernatant was removed by the decantation method.

The solid component thus obtained was washed twice with toluene and then resuspended in 80 liters of toluene. 7.4 liters of a toluene solution of bis (1,3-n-butylmethylcyclopentadienyl) zirconium dichloride (Zr; 34.0 mmol / l) and bis (1,3-dimethylcyclopentadienyl) were introduced into the system. ) 1.0 L of a toluene solution of zirconium dichloride (Zr; 28.1 mmol / L) was added dropwise at 80 ° C over 30 minutes, and the reaction was further performed at 80 ° C for 2 hours. Thereafter, the supernatant was removed and washed twice with hexane to obtain a solid catalyst containing 3.6 mg of zirconium per gram. [Preparation of prepolymerized catalyst] In 85 l of hexane containing 1.7 mol of triisobutylaluminum, 0.85 kg of the solid catalyst obtained above and 1-hexene 25 were added.
5 g was added and ethylene was prepolymerized at 35 ° C. for 12 hours to obtain a prepolymerized catalyst in which 10 g of polyethylene was prepolymerized per 1 g of the solid catalyst. The intrinsic viscosity [η] of this ethylene polymer was 1.74 dl / g. [Polymerization] Using two continuous fluidized-bed gas-phase polymerization apparatuses connected in series, ethylene and 1-
Copolymerization with hexene was performed to obtain an ethylene / 1-hexene copolymer.

The ethylene / 1-hexene copolymer obtained as described above had a 1-hexene content of 7.5% by weight, a density of 0.928 g / cm ³ , and a melt flow rate (MFR). ASTM D 1238-65T, 19;
0 ° C., load 2.16 kg) was 1.63 g / 10 min, and the molecular weight distribution (Mw / Mn) measured by GPC
Was 3.5.

This copolymer has a temperature [Tm] of 120 ° C. at the maximum peak of the endothermic curve measured by a differential scanning calorimeter (DSC), and the n-decane-soluble component amount fraction at room temperature. [W] was 0.25% by weight.

The above-mentioned B ₁ measured by GPC-IR analysis for this copolymer was 12.2 / 1000 C (12.2 per 1000 carbon atoms), and B ₂ was 9.9 / 1.
It was 000C.

[0121]

[Reference Example 2] Copolymerization of ethylene and 1-hexene was carried out in the presence of the prepolymerization catalyst described in Reference Example 1 above, using two continuous fluidized bed gas phase polymerization apparatuses connected in series. An ethylene / 1-hexene copolymer was obtained.

The ethylene / 1-hexene copolymer obtained as described above had a 1-hexene content of 11% by weight, a density of 0.915 g / cm ³ , and a melt flow rate (MFR; ASTM). D 1238-65T, 19
Molecular weight distribution (Mw / Mn) measured by GPC at 0 ° C., load 2.16 kg) is 2.19 g / 10 min.
Was 3.5.

Further, this copolymer has a temperature [Tm] of 108 at the maximum peak of the endothermic curve measured by a differential scanning calorimeter (DSC), and the n-decane-soluble component amount fraction at room temperature. [W] was 0.42% by weight.

The above-mentioned B ₁ measured by GPC-IR analysis for this copolymer was 18.6 / 1000 C, and B
₂ was 14.7 / 1000C.

[0125]

Reference Examples 3 and 4 In the same manner as in Reference Example 1, ethylene / 1-hexene copolymers as shown in Table 1 were obtained.

[0126]

[Table 1]

[0127]

Examples 1 and 2 and Comparative Examples 1 and 2 Using the resins shown in Table 1, a three-layer film having a thickness of 100 μm was inflation-molded under the conditions shown in Table 2 under the following conditions. [Inflation molding conditions] Molding machine: Three-layer machine manufactured by Alpine, Inc. Die diameter: 400 mm Molding temperature: 200 ° C Folding width: 1500 mm Thickness: All layers 100 μm (outer layer / intermediate layer / inner layer = 20 μm)
(m / 60 μm / 20 μm) Table 3 shows the physical properties of the film obtained as described above.

[0128]

[Table 2]

[0129]

[Table 3]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B32B 27/18 B32B 27/18 Z

Claims (9)

[Claims] [1] [I] ethylene and α having 4 to 12 carbon atoms
An ethylene-α-olefin copolymer (A) having a density of 0.925 to 0.940 g / cm ³ and a melt flow rate of 0.1 to 10 g / 10 min. ) Outer layer,
[II] Obtained by copolymerizing ethylene with an α-olefin having 4 to 12 carbon atoms, the density is 0.880 to 0.910 g / cm ³ , and the melt flow rate is 0.1 to 10 g / 10. The intermediate layer consisting of the ethylene / α-olefin copolymer (B) and the antifogging agent (C), and [III] ethylene and an α-olefin having 4 to 12 carbon atoms are copolymerized. An ethylene / α-olefin copolymer (D) having a density of 0.905 to 0.930 g / cm ³ and a melt flow rate of 0.1 to 10 g / 10 min, and an antifogging agent (C) An ethylene / α-olefin copolymer (A) having a density (d
_A ) An agricultural multilayer film, wherein _A ) and the density (d _D ) of the ethylene / α-olefin copolymer (D) satisfy d _A ≧ d _D. 2. [I] ethylene and α having 4 to 12 carbon atoms
An ethylene / α-olefin copolymer having a density of 0.925 to 0.940 g / cm ³ and a melt flow rate of 0.1 to 10 g / 10 min (A ) And an outer layer composed of a mixture of high-pressure low-density polyethylene (E), [II] ethylene and an α-olefin having 4 to 12 carbon atoms are copolymerized, and have a density of 0.880 to 0. A mixture of an ethylene / α-olefin copolymer (B) having a melt flow rate of 910 g / cm ³ and a melt flow rate of 0.1 to 10 g / 10 minutes and a high-pressure low-density polyethylene (E), and an antifogging agent (C) an intermediate layer, and [III] ethylene having a density of 0.905 to 0.930 g / cm ³ obtained by copolymerizing ethylene with an α-olefin having 4 to 12 carbon atoms, and a melt flow rate. Rate is 0.1-10g / 10min Ethylene / α-olefin copolymer (D), a mixture of high-pressure low-density polyethylene (E), and an antifogging agent (C) are laminated to form an inner layer of ethylene / α-olefin copolymer (D). Density (d _AE ) of a mixture of α-olefin copolymer (A) and high-pressure low-density polyethylene (E), and ethylene / α-olefin copolymer (D) for inner layer forming resin and high-pressure low-density The density (d _DE ) of the mixture with polyethylene (E) is d _AE ≧ d _DE
A multilayer film for agriculture characterized by satisfying the following conditions. 3. A mixture of the ethylene / α-olefin copolymer (A) and a high-pressure low-density polyethylene (E),
A mixture of ethylene / α-olefin copolymer (B) and high-pressure low density polyethylene (E), and ethylene / α
In each of the mixture of the olefin copolymer (A) and the high-pressure low-density polyethylene (E), the high-pressure low-density polyethylene (E) is mixed in an amount of 1 to 40% by weight of the total mixture. The multilayer film for agriculture according to claim 2. 4. The ethylene / α-olefin copolymers (A), (B) and (D) are (i) a molecular weight distribution (Mw / Mn: Mw = weight average molecular weight, Mn = Mw) measured by GPC. The number average molecular weight) is in the range of 1.5 to 3.5, and (ii) the n-decane-soluble component amount fraction (W
(% By weight)) and the density (d), W <80 × exp (−100 (d−0.88)) + 0.
(Iii) When the average value of the number of branches on the high molecular weight side by GPC-IR is B ₁ and the average value of the number of branches on the low molecular weight side is B ₂ , B ₁ ≧ B ₂ The multilayer film for agricultural use according to claim 1, wherein the film is provided. 5. A mixture of the ethylene / α-olefin copolymer (A) and a high-pressure low-density polyethylene (E),
A mixture of ethylene / α-olefin copolymer (B) and high-pressure low density polyethylene (E), and ethylene / α
-The mixture of the olefin copolymer (D) and the high-pressure low-density polyethylene (E) has (i) a molecular weight distribution measured by GPC (Mw / Mn: Mw = weight average molecular weight, Mn
= Number average molecular weight) is in the range of 1.5 to 3.5, and (i
i) The fraction (W (% by weight)) and the density (d) of the n-decane soluble component at 23 ° C. are W <80 × exp (−100 (d−0.88)) + 0.
(Iii) When the average value of the number of branches on the high molecular weight side by GPC-IR is B ₁ and the average value of the number of branches on the low molecular weight side is B ₂ , B ₁ ≧ B ₂ The multilayer film for agricultural use according to claim 2 or 3, wherein the film is provided. 6. The ethylene / α-olefin copolymers (A), (B) and (D) are prepared by using a metallocene-based catalyst and ethylene and an α-olefin having 4 to 12 carbon atoms. A copolymer, which is a copolymer.
The multilayer film for agriculture according to any one of to 5. 7. The thickness ratio of each of the outer layer [I], the intermediate layer [II] and the inner layer [III] (outer layer [I] / intermediate layer [II]).
/ Inner layer [III]) is 0.2 to 4/1 to 10/1,
And the total thickness of these layers is 30-200 micrometers, The agricultural multilayer film in any one of Claims 1-6 characterized by the above-mentioned. 8. The agricultural multilayer film according to claim 1, wherein at least one of the outer layer, the intermediate layer and the inner layer contains a weathering stabilizer. 9. (i) Elmendorf tear strength is 90 kg / cm or more in the MD direction and 90 kg / cm or more in the TD direction, and (ii) thickness 10
The dart impact strength at 0 μm is 900 g or more, and (iii) the tensile breaking strength is 350 kg / in the MD direction.
The agricultural multi-layer film according to any one of claims 1 to 8, wherein the agricultural multi-layer film has a cm ² or more and a TD direction of 350 kg / cm ² or more.