JPH0995545A - Agricultural film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an agricultural film excellent in light transmittance, weatherability, stain resistance and long-term antifogging properties. SOLUTION: This film contains an antifogging resin layer comprising a modified α-olefin copolymer (A) composed mainly of a 2-10C α-olefin and containing 0.01-20mol% sulfonated units represented by the formula (wherein R<1> is H or a 1-8C alkyl; R<2> is O or NH; R<3> is a 1-8C alkylene or a 6-12C aryl; A is H, Na, Li or K; and (n) is 0 or 1) and an ethylene/α-olefin copolymer (B) obtained by copolymerizing ethylene and a 3-12C α-olefin at a weight ration of component A to component B of (0.5:99.5) to (99.5:0.5).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an agricultural film, and more specifically, to light transmission, weather resistance,
The present invention relates to an agricultural film having excellent stain resistance and long-term antifogging property.

[0002]

2. Description of the Related Art Films made of thermoplastic resins such as polyolefins such as polyethylene and polypropylene, polyvinyl chloride, ethylene / vinyl acetate copolymers, polyesters, polyamides, etc. can be used for agricultural houses and the like by taking advantage of their excellent characteristics. Widely used in agricultural films. However, since these film surfaces are hydrophobic in nature, when used in agricultural houses,
There is a problem that water drops adhere to the inner surface of the film and block sunlight to adversely affect the growth of crops. Therefore, in order to solve such problems, a surfactant called a drip agent or an antifogging agent is kneaded into the film for molding, or it is applied on the surface of the film after molding to prevent the Attempts have been made to impart cloudiness.

[0003]

However, in the film having the antifogging property imparted by the conventionally known method as described above, the compatibility between the thermoplastic resin and the antifogging agent is poor,
The antifogging agent may bleed out on the surface of the film to cause problems such as whitening of the surface and blocking of the films. Further, since the antifogging agent on the film surface gradually flows out together with water drops, there is room for further improvement in that the antifogging property is maintained for a long period of time.

[0004]

Accordingly, an object of the present invention is to blend a polyolefin and an antifogging agent having excellent compatibility therewith, which is excellent in light transmittance, weather resistance, stain resistance, and long-term antifogging property for agricultural use. To provide a film.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a modified α-olefin copolymer having a specific sulfonic acid group-containing unit and a specific ethylene / α-olefin. By using a copolymer,
The inventors have found that the above problems can be solved, and have reached the present invention. That is, according to the present invention, α having 2 to 10 carbon atoms
-Modified α-olefin copolymer (A) containing olefin as a main component and containing 0.01 to 20 mol% of a sulfonic acid group-containing unit represented by the following general formula (I)

Embedded image (In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ² represents an oxygen atom or an NH group, and R ³ represents an alkylene group having 1 to 8 carbon atoms or 6 to 8 carbon atoms. 12 aryl groups, A represents H, Na, Li, or K. Also, n = 0 or 1.), and ethylene obtained by copolymerizing ethylene with an α-olefin having 3 to 12 carbon atoms. The weight ratio of the modified α-olefin copolymer (A) to the ethylene / α-olefin copolymer (B) containing the α-olefin copolymer (B) as a main component is 0.5: 99. .5 to 99.5: 0.
An agricultural film comprising an antifogging resin layer in the range of 5 is provided.

According to the present invention, the agricultural film according to claim 1, wherein the ethylene / α-olefin copolymer (B) has (a) a melt flow rate of 0.01 to 10 g / 10. In the range of minutes, (b) density 0.8
80 to 0.940 g / cm ³ , (c) GPC
The molecular weight distribution ( _Mw / _Mn : _Mw = weight average molecular weight, _Mn = number average molecular weight) measured in Step 1.
5, and (d) the n-decane-soluble part (W (% by weight)) and the density (d) at 23 ° C. are W <80 × exp (−100 (d−0.88)) + 0. ．
1 is satisfied, and (e) 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 , then B ₁ ≧ B ₂ An agricultural film is provided.

According to the present invention, the film for agriculture according to claim 1, wherein the ethylene / α-olefin copolymer (B) is used in the presence of a metallocene catalyst, ethylene and a carbon atom number 3 are contained. An agricultural film which is an ethylene / α-olefin copolymer obtained by copolymerizing the α-olefin with 1 to 12 is provided.

According to the present invention, the agricultural film according to claim 1, wherein the ethylene / α-olefin copolymer (B) 100 is used in place of the ethylene / α-olefin copolymer (B). Parts by weight and high pressure low density polyethylene 20
Agricultural films using less than or equal to parts by weight of mixed resin are provided.

Further, according to the present invention, in the agricultural film according to claim 4, the mixed resin of the ethylene / α-olefin copolymer (B) and the high-pressure low-density polyethylene is
(A) Melt flow rate is 0.01 to 10 g / 1
In the range of 0 minutes, and (b) the density is 0.880 to 0.
940 g / cm ³ , and (c) molecular weight distribution measured by GPC (Mw / Mn: Mw = weight average molecular weight, M
n = number average molecular weight) in the range of 1.5 to 3.5, and (d) the n-decane-soluble part (W (wt%)) at 23 ° C. and the density are: W <80 × exp (− 100 (d-0.88)) + 0.
1 is satisfied, and (e) 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 There is provided an agricultural film.

According to the present invention, the agricultural film according to claim 1 has a number average molecular weight of 500 to 200 as measured by gel permeation chromatography of the modified α-olefin copolymer (A). There is provided an agricultural film having a melting point of 70 to 160 ° C. measured by DSC.

Further, according to the present invention, in the agricultural film according to claim 1, the modified α-olefin copolymer (A) contains an α-olefin having 2 to 10 carbon atoms as a main component, A cyclic sulfonate represented by the general formula (II) in a carboxyl group-containing α-olefin copolymer containing 0.01 to 20 mol% of a unit composed of a carboxylic acid and / or a carboxylic acid salt, a general formula ( There is provided an agricultural film obtained by reacting at least one selected from aminosulfonic acids represented by III) and hydroxysulfonic acids represented by the general formula (IV).

[Chemical 6] (In the formula, R ⁴ represents a linear or branched alkyl group having 3 to 10 carbon atoms or an aryl group)

[Chemical 7] (In the formula, R ⁵ represents a linear or branched alkyl group having 1 to 10 carbon atoms or an aryl group.)

Embedded image (In the formula, R ⁶ represents a linear or branched alkyl group having 1 to 10 carbon atoms or an aryl group.)

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

<Modified α-Olefin Copolymer (A)> The modified α-olefin copolymer of the present invention is an α-olefin having 2 to 10 carbon atoms.
-Olefin as a main component, containing 0.01 to 20 mol% of a sulfonic acid group-containing unit represented by the following general formula (I).

Embedded image (In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ² represents an oxygen atom or an NH group, R ³ represents an alkylene group having 1 to 8 carbon atoms, and a carbon number of 6
To 12 aryl groups, A is H, Na, Li, or K
Represents Also, n = 0 or 1. )

Here, as the α-olefin having 2 to 10 carbon atoms, ethylene, propylene, butene, pentene, hexene, octene, nonene, decene,
4-methyl-1-pentene and the like can be mentioned. These α
-The olefins may be used alone or in combination of two or more.

Gel permeation chromatography (GPC) of the modified α-olefin copolymer of the present invention
The number average molecular weight (Mn) measured by is usually from 5 to 2,000,000, preferably from 800 to 1.5 million, more preferably from the viewpoint that the antifog property can be maintained for a long period of time and good moldability can be maintained. 1000 to 100
Range of ten thousand. The melting point measured by DSC is usually 7
The temperature is in the range of 0 to 160 ° C, preferably 75 to 150 ° C, more preferably 80 to 140 ° C.

The gel permeation chromatography in the present invention is measured by GPC1 manufactured by Waters Co.
Using 50C, the temperature is 140 ° C., the solvent is o-dichlorobenzene, and the concentration is 0.1 wt% at a measurement flow rate of 1.0 ml / min.
It was measured at. As a column, Tohso Corp. GMH-H
What connected T (60 cm) and GMH-HTL (60 cm) was used.

As a method of producing such a modified α-olefin copolymer, a conventionally known method of introducing a sulfonic acid group can be used.

For example, a method in which at least a part of the carboxyl groups of a carboxyl group-containing polyolefin is converted to an alkali metal salt and then reacted with a cyclic sulfonic acid ester represented by the formula (II), the carboxyl group-containing polyolefin is represented by the formula (III) A method of reacting an aminosulfonic acid represented by the formula with a hydroxysulfonic acid represented by the formula (IV), or unsaturated of a polymer having an unsaturated bond in the molecule such as an α-olefin / diene copolymer Examples include a method of reacting the bond with a sulfur trioxide donor such as concentrated sulfuric acid.

[0018]

Embedded image (In the formula, R ⁴ represents a linear or branched alkyl group having 3 to 10 carbon atoms or an aryl group.)

[0019]

Embedded image (In the formula, R ⁵ represents a linear or branched alkyl group having 1 to 10 carbon atoms or an aryl group.)

[0020]

[Chemical 12] (In the formula, R ⁶ represents a linear or branched alkyl group having 1 to 10 carbon atoms or an aryl group.)

Among these methods, a method of reacting an alkali metal salt of a carboxyl group-containing polyolefin with a cyclic sulfonic acid ester, or a method of reacting a carboxyl group-containing polyolefin with an aminosulfonic acid, from the viewpoint that the introduction amount of a sulfonic acid group can be easily controlled. It is preferable to use the method of reacting with the above, and the method of reacting the carboxyl group-containing polyolefin with hydroxysulfonic acid.

The carboxyl group-containing polyolefin used here is one having an α-olefin having 2 to 10 carbon atoms as a main component and containing 0.01 to 20 mol% of a unit consisting of a carboxylic acid. As a method for producing such a carboxyl group-containing polyolefin, a conventionally known method can be adopted. That is, having 2 to 10 carbon atoms
A method of copolymerizing an α-olefin and an unsaturated carboxylic acid using a radical catalyst, a method of copolymerizing an α-olefin and an unsaturated carboxylic acid in the presence of a coordination catalyst, α
-A method of graft-copolymerizing an olefin homopolymer or copolymer with unsaturated carboxylic acids in the presence / absence of a radical catalyst.

The unsaturated carboxylic acid used here is
There is no particular limitation as long as it is a compound having both a radically polymerizable unsaturated bond and a carboxyl group in the molecule, but examples thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, and citracone. Acid, crotonic acid, isocrotonic acid, norbornene dicarboxylic acid, bicyclo [2,2,1] hept-2-
Unsaturated carboxylic acids such as ene-5,6-dicarboxylic acid,
Or these acid anhydrides are mentioned. Among these, acrylic acid, methacrylic acid, and maleic anhydride are preferable because they can efficiently introduce a carboxyl group.

As the above radical initiator, compounds such as organic peroxides and azo compounds are used.

Specific examples of the organic peroxide include 1,1-
Bis (t-butylperoxy) -3,5,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl- Peroxy ketals such as 4,4-bis (t-butylperoxy) bararate and 2,2-bis (t-butylperoxy) butane;
-Butyl peroxide, dicumyl peroxide, t
-Butylcumyl peroxide, α, α'-bis (t-
Butylperoxy-m-isopropyl) benzene, 2,
5-dimethyl-2,5-bis (t-butylperoxy)
Dialkyl peroxides such as hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl Peroxide, 3,5,5
-Triacylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diacyl peroxides such as m-trioyl peroxide, t-butylperoxyacetate, t
-Butylperoxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate,
Di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, cumylperoxyoctate Peroxyesters such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetra Hydroperoxides such as methylbutyl hydroperoxide can be mentioned.

Of these, preferred are 1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane, di-t-butylperoxide, dicumyl peroxide and 2,5-dimethyl. -2,5-bis (t-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-
3, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-trioyl peroxide, and t-butylperoxy-2-ethylhexanoate.

Specific examples of the azo compound include azoisobutyronitrile. Such radical initiators can be used alone or in combination.

When the thus obtained carboxyl group-containing polyolefin is reacted with the cyclic sulfonic acid ester represented by the general formula (II), at least a part of the carboxyl group is alkali metal such as sodium or potassium itself. , Or a basic compound thereof (for example, sodium hydroxide, potassium hydroxide, etc.) to give an alkali metal salt, which is then reacted with a cyclic sulfonate. The reaction may use a large excess of cyclic sulfonic acid ester, but in order to obtain a product with excellent thermal stability, the cyclic sulfonic acid ester is used in an amount of 0.1 to 5 times the mol of the carboxylate Is preferred.

[0029]

Embedded image (In the formula, R ⁴ represents a linear or branched alkyl group having 3 to 10 carbon atoms or an aryl group.)

Cyclic sulfonic acid esters that can be used in the present invention include 1,3-propane sultone, 1,4-butane sultone, 2,4-butane sultone and 2-methyl-sultone.
Examples thereof include aliphatic sultone such as 2,4-butane sultone, 2-methyl-2,4-pentane sultone and 1,3-octane sultone, and aromatic sultone such as benzyl sultone, tolyl sultone and 1,8-naphthalene sultone.
Of these, 1,3-propane sultone and 1,4-butane sultone are preferable because they can be produced at low cost.

When the above-mentioned carboxyl group-containing polyolefin is reacted with aminosulfonic acids, it is preferable to react with 0.1 to 5 moles of aminosulfonic acids with respect to the carboxyl groups. Examples of the aminosulfonic acids used at this time include p-aminobenzenesulfonic acid (sulfanilic acid), m-aminobenzenesulfonic acid, o-aminobenzenesulfonic acid, and 2-aminoethanesulfonic acid (taurine). Before or after the reaction with the carboxyl group-containing polyolefin, these aminosulfonic acids may be neutralized with an alkali metal or a basic compound thereof, if necessary, to give an alkali metal salt.

The reaction of the carboxyl group-containing polyolefin with the cyclic sulfonic acid ester and the aminosulfonic acid may be carried out in a state in which the carboxyl group-containing polyolefin is at least partially dissolved in a nonpolar organic solvent or in a molten state. it can.

When the above-mentioned carboxyl group-containing polyolefin is reacted with hydroxysulfonic acids, it is preferable to react with 0.1 to 5 moles of hydroxysulfonic acids with respect to the carboxyl groups. Examples of the hydroxysulfonic acids used at this time include hydroxyethanesulfonic acid (isethionic acid), P-hydroxybenzenesulfonic acid, hydroxypropanesulfonic acid, and hydroxybutanesulfonic acid.

When the above-mentioned carboxyl group-containing polyolefin is reacted with hydroxysulfonic acids, it is preferable to carry out the reaction under reduced pressure in order to carry out the reaction quickly.
At this time, a known esterification catalyst may be used. Also,
The carboxylic acid moiety of the carboxyl group-containing polyolefin may be esterified with a lower alcohol such as methanol in advance and then reacted with hydroxysulfonic acid. In addition, these hydroxysulfonic acids may be neutralized with an alkali metal or a basic compound thereof, if necessary, before or after the reaction with the carboxyl group-containing polyolefin to obtain an alkali metal salt.

When the reaction is carried out in a state of being at least partially dissolved in a non-polar organic solvent, the non-polar organic solvent used is an aromatic hydrocarbon solvent such as benzene, toluene and xylene, pentane, hexane, heptane. Aliphatic hydrocarbon solvents such as, octane, nonane and decane,
Alicyclic hydrocarbon-based solvents such as cyclohexane, methylcyclohexane, and decahydronaphthalene, and chlorinated hydrocarbons such as chlorobenzene, dichlorobenzene, trichlorobenzene, methylene chloride, chloroform, carbon tetrachloride, and tetrachloroethylene. To be The reaction temperature at that time is 50 to 250 ° C., preferably 60 to 200 ° C.

When the reaction is carried out in a state where the carboxyl group-containing polyolefin is melted, it is preferable to carry out the reaction at a temperature not lower than the melting point of the resin and not higher than 300 ° C. using an extruder or the like.

[Ethylene / α-olefin copolymer (B)] The ethylene / α-olefin copolymer (B) used in the present invention comprises ethylene and 3 to 12 carbon atoms.
And an α-olefin.

Specific examples of the α-olefin having 3 to 12 carbon atoms used for copolymerization with ethylene include propylene, 1-butene, 1-pentene, 1-hexene,
4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene and the like can be mentioned. Among these, 4 carbon atoms
Α-Olefins having from 10 to 10 carbon atoms, particularly α-olefins having from 4 to 6 carbon atoms are preferred.

In the present invention, the above ethylene / α-olefin copolymer (B) can be used alone or in combination of two or more kinds. The ethylene / α-olefin copolymer (B) used in the present invention has a structural unit derived from ethylene of 50% by weight or more and 100% by weight or more.
Less than, preferably 55 to 99% by weight, more preferably 65 to 98% by weight, particularly preferably 70 to 96% by weight, and an α having 4 to 12 carbon atoms.
-Up to 50% by weight of structural units derived from olefins,
It is desirable to be present in an amount of preferably 1 to 45% by weight, more preferably 2 to 35% by weight, particularly preferably 4 to 30% by weight.

The composition of the ethylene / α-olefin copolymer is usually 13 C-NMR spectrum of a sample in which about 200 mg of the copolymer is uniformly dissolved in 1 ml of hexachlorobutadiene in a 10 mmφ sample tube.
° 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.

Ethylene / α-olefin copolymer (B)
Has a density in the range of 0.880 to 0.940 g / cm ³ , preferably 0.926 to 0.940 g / cm ³ , and more preferably 0.926 to 0.936 g / cm ³ .

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.

Further, the ethylene / α-olefin copolymer (B) has a melt flow rate (MFR; ASTM
D 1238-65T, 190 ° C, load 2.16kg)
Is 0.01 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 (B) measured by GPC
n: Mw = weight average molecular weight, Mn = number average molecular weight) 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 (Wako Pure Chemical Industries) was used as the mobile phase, and BHT was used as the antioxidant.
(Takeda Pharmaceutical Co., Ltd.) 0.025% by weight was used, the sample was moved at 1.0 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 has a molecular weight of Mw <10
00 and Mw> 4 × 10 ⁶ were manufactured by Tosoh Corporation, and 1000 <Mw <4 × 10 ⁶ were manufactured by Pressure Chemicals.

In the ethylene / α-olefin copolymer (B), the n-decane-soluble part (W (% by weight)) at 23 ° C. and the density (d) satisfy the relationship shown below. . W <80 × exp (−100 (d−0.88)) + 0.
1 In addition, the amount of n-decane soluble component of ethylene / α-olefin copolymer (the smaller the soluble component, the narrower the composition distribution)
The measurement of about 3 g of ethylene / α-olefin copolymer
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 )], T _m <400 × d-250, preferably T _m <450 × d-297, more preferably T _m <500 × d-344, particularly preferably T _m <550 ×. It is preferable that the relationship represented by d-391 is satisfied.

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 (B) is 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 the cumulative weight fraction of the polymer elution amount separated by GPC by the molecular weight of 15 to 85.
% (That is, a polymer elution component excluding 15% of the low molecular weight region and 15% of the high molecular weight region), the measured value group of the number of branches 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 ones.

The measurement conditions for B ₁ and B ₂ are as follows. Measuring device: PERKIN ELMER 1760X Column: TOSOH TSKgel GMH-HT (7.5mmI.D. x 600mm
) × 1 Eluent: o-dichlorobenzene (ODCB) containing 0.05% MP-J [Wako Pure Chemical Industries, Ltd., extra
pure grade] Column temperature: 140 ° C Sample concentration: 0.1% (weight / volume) Injection volume (inj.volume): 100 microliters detector: MCT resolution: 8 cm ^-1 These B ₁ and B ₂ are as above. Related ethylene / α
Since the olefin copolymer (B) has a narrow composition distribution and a small amount of low polymer, it is less sticky. Therefore, when the ethylene / α-olefin copolymer (B) as described above is used for a multilayer film, it is possible to obtain an agricultural film having a multilayer structure excellent in dustproofness.

Since the ethylene / α-olefin copolymer (B) has a very small decrease in light transmittance with time, an agricultural multilayer film having such an ethylene / α-olefin copolymer is It is possible to extend for a long time.

Further, when the above ethylene / α-olefin copolymer (B) is used, the multilayer film can be made thin, and the weight of the multilayer film can be reduced.

The ethylene / α-olefin copolymer (B) as described above is disclosed in JP-A-6-9724 and JP-A-6-9724.
-136195, JP-A-6-136196, JP-A-6-207057, etc. In the presence of a so-called metallocene olefin polymerization catalyst containing a metallocene catalyst component, ethylene and 3 carbon atoms are contained.
It can be produced by copolymerizing the α-olefins of 1 to 12 so that the density of the resulting copolymer is 0.940 g / cm ³ or less.

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 transition metal compounds include transition metal compounds represented by the following general formula [V].

ML ¹ x [V] 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 with 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 [V] 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 alkyl groups such as methyl group, cycloalkyl groups such as cyclopentyl group, aryl groups such as phenyl group and aralkyl groups such as benzyl group.

As the ligand represented by SO ₃ R,
Specific examples 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, the repeating unit represented by the formula —Al (R) O— [wherein R is an alkyl group] is usually 3 to 50.
To some extent, methylaluminoxane, ethylaluminoxane, methylethylaluminoxane, etc. are used.

Such an aluminoxane can be prepared by a conventionally known method. The fine particle carrier (c) used in the preparation of the olefin polymerization catalyst is an inorganic or organic compound and has a particle size of usually 10 to 300.
It is about .mu.m, and preferably 20 to 200 .mu.m granular or fine particle solid.

Porous oxides are preferred as the inorganic carrier.
Specifically, SiO₂ , Al₂ O _Three , MgO, Zr
O₂ , TiO₂ , B₂ O_Three , CaO, ZnO, BaO,
SnO ₂ Etc. or mixtures thereof can be exemplified.
You. In addition, a small amount of Na is contained in the above inorganic oxide.₂ CO_Three etc
Carbonate of Al₂ (SO_Four )_Three Sulfates such as KNO_Three etc
Nitrate, Li₂ Even if it contains oxides such as O
I can't.

The properties of such a carrier vary 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 100 to 700 m ² / g. The pore volume is preferably 0.3 to 2.5 cm ³ / g.

This carrier may contain 100 to 1 if necessary.
It is used after firing at 000 ° C, preferably 150 to 700 ° C. As the organic compound used as the fine particle carrier, a (co) polymer produced mainly from an α-olefin having 2 to 14 carbon atoms such as ethylene and 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 trialkyl aluminum such as trimethyl aluminum, alkenyl aluminum such as isoprenyl aluminum, and dimethyl aluminum. 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.

Ionized ionic compound catalyst component (e)
Described in USP-547718, for example.
Triphenylboron, MgCl₂ , Al₂ O_Three , S
iO ₂ -Al₂ O_Three Lewis acids such as triphenylcarb
Aluminum tetrakis (pentafluorophenyl) borate
Ionic compounds such as; dodecaborane, bis-n-butylan
Carborane conversion of monium (1-carbedodeca) borate, etc.
Compounds.

The ethylene / α-olefin copolymer (B) used in the present invention comprises the metallocene catalyst component (a), the organoaluminumoxy 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 an α-olefin having 3 to 12 carbon atoms are copolymerized.

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.
To 10 ^-3 gram atom / liter, preferably 10 ^-7
It is preferably used in an amount of from 10 ^-4 g 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) which is 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 5 to 300, preferably 10 to 20
The range is 0, 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 500 ° C, preferably 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 /
The polymerization can be carried out in any of a rotation type system, a semi-continuous system and a continuous system under a pressure condition of cm ² , preferably 2 to 50 kg / cm ² .

In the present invention, when preparing the ethylene / α-olefin copolymer (B), 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 multi-stage polymerization of the above (1) is preferred.

Examples of the multi-stage polymerization method include the following multi-stage polymerization methods. [1] Ethylene and carbon in the presence of a metallocene catalyst containing a metallocene catalyst component composed of at least one compound selected from the transition metal compounds represented by the general formula [V] and an organoaluminum oxy compound catalyst component. Polymerization different from the step of producing an ethylene / α-olefin copolymer (B-1) by copolymerizing with α-olefin having 3 to 12 atoms and [2] the polymerization vessel in which the copolymerization reaction is performed. And a metallocene catalyst component comprising at least one compound selected from Group IVB transition metal compounds of the periodic table containing a ligand having a cyclopentadienyl skeleton represented by the above general formula [V], In the presence of a metallocene-based catalyst containing an organoaluminum oxy compound catalyst component, ethylene and C 3-12
And a step of producing an ethylene / α-olefin copolymer (B-2), and a multistage polymerization method of an 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 particulate 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 (B-1) is first produced using a plurality of polymerization vessels connected in series, and then ethylene / α
-The ethylene / α-olefin copolymer (B-1) was introduced into a polymerization vessel different from the polymerization vessel used for the production of the olefin copolymer (B-1), and the ethylene / α-olefin copolymer (B The ethylene / α-olefin copolymer (B-2) can be produced in the presence of -1). Alternatively, first, an ethylene / α-olefin copolymer (B-2) is produced, and then an ethylene / α-olefin copolymer (B-
The ethylene / α-olefin copolymer (B-2) was introduced into a polymerization vessel different from the polymerization vessel used for the production of 2), and ethylene was added in the presence of the ethylene / α-olefin copolymer (B-2). -The α-olefin copolymer (B-1) can be produced.

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

The use form of the antifogging agent is ethylene-α.
-A method of kneading into an olefin copolymer resin for use,
A method in which the antifogging agent alone is used as a film and laminated with a film of an ethylene-α-olefin copolymer resin, or they are coextruded to form a multilayer film, or an antifogging agent is used as an aqueous dispersion and ethylene-α-olefin Examples include a method of coating and drying the film of the copolymer resin,
Above all, it is preferable to use it by kneading it with an ethylene-α-olefin copolymer resin and use it as at least the innermost layer of the agricultural multilayer film.

The thermoplastic resin used together with the ethylene-α-olefin copolymer includes polyolefins such as polyethylene and polypropylene, ethylene / vinyl acetate copolymer (EVA), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC). ), Polystyrene, polyethylene terephthalate, nylon, polycarbonate and the like. Among these thermoplastic resins, polyethylene, polypropylene, E from the viewpoint of compatibility with antifog agents.
VA, PVC and PVDC are preferable, and high pressure low density polyethylene is particularly preferable. The amount of high-pressure polyethylene used is ethylene-α-olefin copolymer (B)
It is used in an amount of 30 parts by weight or less, preferably 1 to 20 parts by weight, based on 100 parts by weight.

When the ethylene-α-olefin copolymer resin is kneaded with the antifogging agent and used, the compounding amount of the antifogging agent is
The polymerization ratio with the ethylene-α-olefin copolymer (B) is in the range of 0.5: 99.5 to 99.5: 0.5, preferably 1:99 to 50:50, particularly preferably 1 : 99 to 30:70.

The high-pressure low-density polyethylene used in the present invention has a melt flow rate (MFR;
ASTM D 1238-65T, 190 ° C, load 2.
16 kg) is 0.1 to 100 g / 10 minutes, preferably 0.2 to 10 g / 10 minutes, more preferably 0.1.
It is in the range of 5 to 5 g / 10 minutes.

[0084] Further, high-pressure low-density polyethylene, to a density no 0.915 0.935 g / cm ^3, preferably 0.920 to 0.930 g / cm ^3, more preferably to no 0.922 0.928 g / cm It is in the range of ³ . This density is measured by the above-mentioned ethylene / α-
This is the same as the method for measuring the density of the olefin copolymer (B).

Further, the high pressure low density polyethylene preferably has a swell ratio of 60% or less, more preferably 5%.
It is 0% or less, particularly preferably 45% or less. The swell ratio is obtained as follows.

The diameter at a 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) In the present invention, ethylene / α -The weight ratio of the olefin copolymer (B) and the high-pressure low-density polyethylene is 99.
/ 1 to 80/20, preferably 95/5 to 85
/ 15, more preferably 90/10 to 85/15.

[0088]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. <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. Cooled. Then, 28.7 liters of a toluene solution of methylaluminoxane (A1; 1.33 mol / liter) was added dropwise over 1 hour. At that time, the temperature in the system was kept at 0 ° C. Subsequently, the mixture was reacted at 0 ° C for 60 minutes, then heated to 95 ° C over 1.5 hours, and reacted 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. Into this system, a solution of bis (1,3-n-butylmethylcyclopentadienyl) zirconium dichloride in toluene (Zr; 34.0 mmol / liter), 7.4 liters, and bis (1,3-dimethylcyclopentadienyl) were added. )
Toluene solution of zirconium dichloride (Zr; 28.
1 mmol / liter) 1.0 liter at 80 ° C.
The mixture was added dropwise over a period of 1 minute, and further reacted at 80 ° C for 2 hours. Then, the supernatant liquid was removed, and the solid catalyst was washed twice with hexane to obtain a solid catalyst containing 3.6 mg of zirconium per 1 g.

[Preparation of Prepolymerized Catalyst] In 85 liters of hexane containing 1.7 mol of triisobutylaluminum, 0.85 kg of the solid catalyst obtained above and 1-
By adding 255 g of hexene and preliminarily polymerizing ethylene at 35 ° C. for 12 hours, 10 g per 1 g of the solid catalyst is obtained.
g of polyethylene was prepolymerized to obtain a prepolymerized catalyst. The intrinsic viscosity [η] of this ethylene polymer is 1.74d.
It was 1 / g.

[Polymerization] Using two continuous fluidized bed gas phase polymerization apparatuses connected in series, in the presence of the above-mentioned prepolymerization catalyst,
Copolymerization of ethylene and 1-hexene was performed to obtain an ethylene / 1-hexene copolymer. The ethylene / 1-hexene copolymer (hereinafter sometimes abbreviated as B-1) obtained as described above has a 1-hexene content of 7.5% by weight and a density of 0.928 g / cm 3. ³ and the melt flow rate (MFR; ASTM D 1238-65T,
The molecular weight distribution (Mw / M) measured by GPC at 190 ° C and a load of 2.16 kg is 1.63 g / 10 minutes.
n) was 3.5.

The copolymer had a maximum endothermic curve temperature [Tm] of 120 ° C. measured by a differential scanning calorimeter (DSC), and the n-decane-soluble component amount fraction [W] at room temperature. Was 0.25% by weight. The above-mentioned B ₁ measured by GPC-IR analysis for this copolymer
Is 12.2 / 1000C (1 per 1000 carbon atoms
2.2) and B ₂ was 9.9 / 1000C.

<Reference Example 2> Preparation of ethylene-4-methyl-1-pentene copolymer Ethylene was copolymerized with 4-methyl-1-pentene in the presence of a conventional Ti-based polymerization catalyst to obtain ethylene.・ 4-
A methyl-1-pentene copolymer was obtained. The ethylene / 4-methyl-1-pentene copolymer obtained as described above has a 4-methyl-1-pentene content of 13.6% by weight and a density of 0.920 g / cm ³ . Melt flow rate (MFR; ASTM D 1238-65T,
The molecular weight distribution (Mw / M) measured by GPC at 190 ° C and a load of 2.16 kg was 2.01 g / 10 minutes.
n) was 4.4.

This copolymer had a maximum endothermic curve temperature [Tm] of 122 ° C. measured by a differential scanning calorimeter (DSC), and the n-decane-soluble component fraction [W] at room temperature. ] Was 8.5% by weight. GPC for this copolymer (hereinafter sometimes abbreviated as E-1)
-IR analysis above B ₁ measured in the 12.7 / 1000
C and B ₂ was 14.5 / 1000C.

<Production Example 1> Preparation of antifogging agent Using p-xylene as a reaction solvent, 150 g of ethylene / acrylic acid copolymer per 1 liter of this p-xylene (acrylic acid content: 20 wt%, Mn: 1200)
Was melted at 140 ° C. Then, an aqueous solution of sodium hydroxide (8 g / 27 ml) was added dropwise to this solution. After the dropping was completed, the temperature was kept as it was for 1.5 hours to completely distill off the water. Furthermore, butane sultone 3 was added to this solution.
1.7 g was added dropwise and reacted for 1.5 hours.

After the solution after the reaction was cooled to room temperature, acetone was added to precipitate a polymer. The precipitated polymer is filtered and washed repeatedly with water and acetone to 80 ° C.
Then, the product was dried for one day and night to obtain the desired modified α-olefin-based copolymer. This modified α-olefin-based copolymer (hereinafter sometimes abbreviated as A-1) has a sulfonic acid content of 8
Mol%, Mn measured by GPC was 2000 and melting point [Tm] measured by DSC was 80.5. The sulfonic acid group was quantified by atomic absorption spectrometry of S atom.

<Production Example 2> Preparation of antifogging agent The same as Production Example 3 except that an aqueous solution of sodium aminoethanesulfonate (40.9 g / 30 ml) was used in place of butanesultone and the neutralization step with sodium hydroxide was omitted. Similarly, a modified α-olefin-based copolymer was synthesized.
This modified α-olefin-based copolymer (hereinafter sometimes abbreviated as B-2) has a sulfonic acid content of 5 mol% and G
Mn measured by PC was 1300, and melting point [Tm] measured by DSC was 80.9 ° C. The physical properties of the agricultural films in Examples and Comparative Examples were evaluated as follows.

[Preparation of Film] The modified α-olefin copolymer and the ethylene / α-olefin copolymer were mixed at a predetermined ratio and melt-kneaded at 190 ° C. using a Labo Plastomill. The obtained composition was held at 200 ° C. and 50 kgf / cm ² for 3 minutes using a press molding machine,
It was prepared by holding at 50 kgf / cm ² for 5 minutes with a cooling press set at 20 ° C.

[Initial haze] Initial haze (Haze (1)
%) Was measured using an integrating sphere type measuring device haze meter described in ASTM D 1003.

[Haze after 12 months of outdoor exposure] After the film was exposed outdoors for 12 months, the haze of this film (HA
ZE (2);%) was measured in the same manner as in (1) above.

[Anti-fog property] A beaker of 500 ml is filled with water 30.
Add 0 ml, cover the top of the beaker with the above-mentioned press sheet, and seal it.
It was left in a thermostatic chamber set at 3 ° C. After 1 day and 3 months, the inner surface of the film was observed to evaluate the degree of water drop attachment. ◎ No fogging at all ○ Slight fogging is observed △ Slight fogging is observed × Fogging is present and the contents are not visible

<Examples 1 and 2 and Comparative Example 1> Using the modified α-olefin copolymers and ethylene / α-olefin copolymers shown in Table 1, press sheets were prepared to prevent the haze and The haze was evaluated. The results are shown in Table 1.

[0103]

[Table 1]

[0104]

The agricultural film according to the present invention has an antifogging property by using an ethylene-α-olefin copolymer resin and a modified α-olefin copolymer antifogging agent which are excellent in compatibility. Since it is excellent in transparency and excellent in transparency over a long period of time, it can be used for a longer period of time as compared with a conventional agricultural film, and the frequency of spreading work can be reduced.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B32B 27/32 103 B32B 27/32 103 // C08L 23/08 LCK C08L 23/08 LCK 23/16 LCY 23/16 LCY 23/18 LCZ 23/18 LCZ 33/14 LJH 33/14 LJH 33/24 LJV 33/24 LJV 41/00 LJZ 41/00 LJZ (72) Inventor Hajime Yamaguchi Waki-cho, Kuga-gun 6-1-2 Waki Mitsui Sekiyu Kagaku Kogyo Co., Ltd.

Claims (7)

[Claims] 1. A modified α-olefin-based copolymer mainly containing an α-olefin having 2 to 10 carbon atoms and containing 0.01 to 20 mol% of a sulfonic acid group-containing unit represented by the following general formula (I). Polymer (A) embedded image (In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ² represents an oxygen atom or an NH group, R ³ represents an alkylene group having 1 to 8 carbon atoms, or 6 carbon atoms. To 12 aryl groups, A is H, Na, Li,
Or represents K. Also, n = 0 or 1. And an ethylene / α-olefin copolymer (B) obtained by copolymerizing ethylene with an α-olefin having 3 to 12 carbon atoms as a main component, and the modified α-olefin copolymer (A) as described above. ethylene·
The weight ratio with the α-olefin copolymer (B) is 0.
An agricultural film comprising an antifogging resin layer in the range of 5: 99.5 to 99.5: 0.5. 2. The ethylene / α-olefin copolymer (B) has a melt flow rate (a) in the range of 0.01 to 10 g / 10 min, and a density (b) of 0.880.
To 0.940 g / cm ³ and (c) the molecular weight distribution measured by GPC (M _W / M _n : M _W = weight average molecular weight, M _n = number average molecular weight) is in the range of 1.5 to 3.5. And (d) the n-decane-soluble part (W (% by weight)) and the density (d) at 23 ° C. are W <80 × exp (−100 (d−0.88)) + 0.
1 is satisfied, and (e) 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 , then B ₁ ≧ B ₂ The agricultural film according to claim 1. 3. The ethylene / α-olefin copolymer (B) is an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms in the presence of a metallocene catalyst. The agricultural film according to claim 1, which is a polymer. 4. A mixed resin comprising 100 parts by weight of the ethylene / α-olefin copolymer (B) and 30 parts by weight or less of a high-pressure low-density polyethylene is used in place of the ethylene / α-olefin copolymer (B). The agricultural film according to claim 1. 5. The mixed resin of the ethylene / α-olefin copolymer (B) and the high-pressure low-density polyethylene is
(A) Melt flow rate is 0.01 to 10 g / 1
In the range of 0 minutes, and (b) the density is 0.880 to 0.
940 g / cm ³ , and (c) molecular weight distribution measured by GPC (Mw / Mn: Mw = weight average molecular weight, M
n = number average molecular weight) in the range of 1.5 to 3.5, and (d) the n-decane-soluble part (W (wt%)) at 23 ° C. and the density are: W <80 × exp (− 100 (d-0.88)) + 0.
1 is satisfied, and (e) 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 , then B ₁ ≧ B ₂ The agricultural film according to claim 4. 6. The modified α-olefin-based copolymer (A) has a number average molecular weight of 5 to 2,000,000 as measured by gel permeation chromatography and a melting point of 70 to 160 ° C. as measured by DSC. The agricultural film described. 7. The modified α-olefin-based copolymer (A) contains an α-olefin having 2 to 10 carbon atoms as a main component, and 0.01 to 20 units of a carboxylic acid and / or a carboxylic acid salt. In the carboxyl group-containing α-olefin copolymer containing mol%, cyclic sulfonic acid esters represented by the general formula (II), aminosulfonic acids represented by the general formula (III), and the general formula (IV) The agricultural film according to claim 1, which is obtained by reacting at least one selected from the hydroxysulfonic acids represented by: Embedded image (In the formula, R ⁴ represents a linear or branched alkyl group having 3 to 10 carbon atoms, or an aryl group.) (In the formula, R ⁵ represents a linear or branched alkyl group having 1 to 10 carbon atoms or an aryl group.) (In the formula, R ⁶ represents a linear or branched alkyl group having 1 to 10 carbon atoms or an aryl group.)