JPH10264334A - Agricultural multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a film with excellent transparency and tear strength by forming ethylene-α-olefin copolymer having specific physical properties in inner, intermediate and outer layers, and setting densities of the respective layers to a specific relationship. SOLUTION: Inner and outer layers of ethylene-α-olefin copolymer for constituting the film satisfy Tem <=286D1 -137, where 0.1 to 50 g/10 min of melt flow rate, 0.900 to 0.928 g/cm<3> of a density, 70 to 130 deg.C of extrapolation melt finishing temperature (Tem) of a melting peak by a differential scanning calorimetry, and density D1 of the copolymer itself therewith. The relation of the copolymer itself with density D2 satisfies Temp <=286D2 -137 among MRF of an intermediate layer of 0.1 to 50 g/10 min, density of 0.8800 to 0.924 g/cm<3> , Tem of 70 to 130 deg.C. And, D1 is larger than the D2 . 1 to 20% of inorganic compound containing at least one atom selected from a group consisting of Mg, C, Al and Si is added to copolymer of the intermediate layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer agricultural film having excellent transparency, tear strength, impact strength and tensile strength.

[0002]

2. Description of the Related Art In house cultivation, tunnel cultivation, mulch cultivation, and the like for the purpose of forcing cultivation on agriculture, agricultural films composed of various thermoplastic resins are generally used in large quantities as covering materials. Films that are mainly used include, for example, polyvinyl chloride film, polyethylene film, ethylene-vinyl acetate copolymer film, etc., among which polyvinyl chloride film is excellent in transparency, toughness, heat retention and the like. And is used most often.

However, in the case of a polyvinyl chloride film, since the film weight in the same volume is heavy and sticky, it is inferior in terms of house expansion workability, and the film adheres to the plasticizer due to dust adhesion. There is a problem that transparency is deteriorated, that is, a so-called dust-proof property is inferior, and a problem that toxic gas is generated during incineration of waste.

[0004] Polyethylene films are superior to polyvinyl chloride films in price, spreadability, dustproofness and disposal, but are inferior in transparency, toughness and heat retention. is there.

On the other hand, when a film containing ethylene-vinyl acetate copolymer as a main component is applied to an agricultural film,
Although the transparency and the heat retention are improved as compared with the above-mentioned polyethylene film, there is a problem that it is still inferior as compared with the polyvinyl chloride film.

[0006] When polyethylene or ethylene-vinyl acetate copolymer having these problems is used as an agricultural film, attempts have been made to improve the heat retention of the film by adding an inorganic additive having a high infrared absorbing ability. Examples of the inorganic additives include silica powder (Japanese Patent Publication No. 47-13853), magnesium compound (Japanese Patent Publication No. 3-50791), hydrotalcite (Japanese Patent Publication No. 62-31744), and the like. Has been proposed.

[0007] However, agricultural films made of polyethylene resins such as polyethylene and ethylene-vinyl acetate copolymer have improved heat insulation properties of the films, but still have a higher heat retention than polyvinyl chloride films. Transparency and toughness are insufficient.

[0008] In order to improve the toughness of such a polyethylene resin film, agricultural films utilizing the toughness of linear low-density polyethylene have recently been devised. For example, Japanese Unexamined Patent Publication (Kokai) No. 58-160146 proposes an agricultural multilayer film in which a base layer mainly composed of linear low-density polyethylene and a polyethylene resin layer formed by a conventional production method are laminated. I have. Although this agricultural multi-layer film has improved toughness to some extent, the improvement in the fold strength, which is a disadvantage at the time of forming the blown film, is still insufficient. There is a problem that it is inferior to a vinyl film.

Japanese Patent Application Laid-Open No. 1-182037 discloses that an outer layer is formed of a polyethylene resin containing a linear ethylene-α-olefin copolymer as a main component, and an inner layer is formed of an ethylene-vinyl acetate copolymer. A multilayer agricultural film formed of a polyethylene resin as a main component has been proposed. Agricultural multilayer films described in this publication are not sufficiently satisfactory in toughness and transparency as in the above-mentioned multilayer film described in JP-A-58-160146. Since it is a film, there is a problem that curling occurs in the film product.

[0010] Therefore, in order to solve these problems, the conventional agricultural multi-layer film has the same degree of transparency as a polyvinyl chloride film and has a higher toughness than the conventional agricultural multilayer film. The emergence of films is desired.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an agricultural multilayer film having excellent transparency, tear strength, impact strength and tensile strength.

The present inventors have conducted intensive studies to overcome the above-mentioned problems of the prior art, and as a result, have a certain property.
It has been found that the above object can be achieved by a multilayer polyethylene-based resin film in which at least three layers of ethylene-α-olefin copolymers are laminated.

The present invention has been completed based on these findings.

[0014]

According to the present invention, there is provided an agricultural multilayer film having a laminated structure of at least three layers of an inner layer (A ₁ ) / intermediate layer (B) / outer layer (A ₂ ),
(1) The inner layer (A ₁ ) and the outer layer (A ₂ ) have a melt flow rate within a range of 0.1 to 50 g / 10 minutes and a density (D ₁ ) of 0.900 to 0.928 g / cm ³ . Within the range, the extrapolated melting end temperature (Tem) of the melting peak obtained by differential scanning calorimetry (DSC) is 70 to 130 ° C.
From the ethylene-α-olefin copolymer (a) in which the relation between the extrapolation melting end temperature (Tem) and the density (D ₁ ) satisfies the relational expression Tem ≦ 286D ₁ -137. (2) The intermediate layer (B) has a melt flow rate within a range of 0.1 to 50 g / 10 minutes and a density (D ₂ ) within a range of 0.880 to 0.924 g / cm ^3. Extrapolation melting end temperature (Tem) of the melting peak obtained by differential scanning calorimetry (DSC) is 70 to 130 ° C.
From the ethylene-α-olefin copolymer (b) in which the relation between the extrapolation melting end temperature (Tem) and the density (D ₁ ) satisfies the relational expression Tem ≦ 286D ₂ -137. (3) The density (D ₁ ) of the ethylene-α-olefin copolymer (a) forming the inner layer (A ₁ ) and the outer layer (A ₂ ) is determined by the ethylene-α-olefin forming the B layer. Greater than the density (D ₂ ) of the polymer (b), and
(4) The ethylene-α-olefin copolymer (b) forming the intermediate layer (B) contains one or more inorganic compounds containing at least one atom selected from the group consisting of Mg, Ca, Al and Si. An agricultural multilayer film is provided, which is filled at a ratio of 〜20% by weight.

According to the present invention, the ethylene-α-olefin copolymers (a) and (b) forming each layer are both polymers produced using a metallocene catalyst. Is provided.

According to the present invention, the ethylene-α-olefin copolymers (a) and (b) forming each layer are both ethylene and α-olefin copolymers having 3 to 18 carbon atoms. The above-described agricultural multilayer film is provided.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. 1. Physical Properties of Polymers of Inner Layer (A ₁ ) and Outer Layer (A ₂ ) The ethylene-α-olefin copolymer (a) used for the inner layer (A ₁ ) and the outer layer (A ₂ ) of the present invention is as follows: Shows physical properties.

MFR 190 ° C. according to JIS-K7210, load 2.16
The MFR (melt flow rate: melting flow rate) in kg is
0.1 to 50 g / 10 min, preferably 0.3 to 20 g /
It is 10 minutes, more preferably 0.5 to 8 g / 10 minutes.
If the MFR is larger than the above range, the strength is reduced and the film formation becomes unstable. On the other hand, when the MFR is smaller than the above range, the resin pressure increases and the moldability deteriorates.

Density The density according to JIS-K7112 is 0.900 to
0.928 g / cm ³ , preferably 0.903 to 0.9
26 g / cm ³ , more preferably 0.905 to 0.92
4 g / cm ³ . When the density is larger than the above range,
Transparency and impact strength are poor. On the other hand, if the density is too low, the film becomes less rigid and the film surface becomes sticky, which is preferable.

Extrapolation melting end temperature (Tem) of the melting peak by differential scanning calorimetry (DSC) In the case of the ethylene-α-olefin copolymer used for the inner layer (A ₁ ) and outer layer (A ₂ ) of the present invention The differential melting curve obtained by differential scanning calorimetry (DSC) has one melting peak, and the melting peak has an extrapolated melting end temperature (Tem) of 70 to 130 ° C., preferably 80 to 130 ° C.
The temperature is 27 ° C, particularly preferably 90 to 124 ° C. Further, regarding the relationship between the temperature (Tem) and the density (D ₁ ) of the copolymer itself, the following relational expression: Tem ≦ 286 D ₁ -13
7 must be satisfied. Preferably Tem ≦ 42
9D ₁ -271, most preferably Tem ≦ 571D ₁ -4
04 is desirable.

When there is no peak in the differential melting curve,
It is not preferable because stickiness occurs when the film is formed. The differential melting curve preferably has one peak, and when there are two or more peaks, the transparency, impact strength, and tensile strength are undesirably poor.

Extrapolation melting end temperature of the above peak (Tem)
Is smaller than the above range, blocking tends to occur when formed into a film. On the other hand, if the temperature is higher than the above range, transparency, impact strength, and tensile strength become poor, which is not preferable.

In some cases, a component that melts at a temperature other than the melting temperature of the peak may be recognized, but a component having a very slow melting behavior is not recognized as a peak. 2. Polymer of Intermediate Layer (B) The ethylene-α-olefin copolymer (b) used in the intermediate layer (B) of the present invention exhibits the following physical properties.

MFR 190 ° C. under JIS-K7210, load 2.16
The MFR (melt flow rate: melting flow rate) in kg is
0.1 to 50 g / 10 min, preferably 0.3 to 20 g /
It is 10 minutes, more preferably 0.5 to 8 g / 10 minutes.
If the MFR is larger than the above range, the strength is reduced and the film formation becomes unstable. On the other hand, when the MFR is smaller than the above range, the resin pressure increases and the moldability deteriorates.

Density The density according to JIS-K7112 is 0.880 to
0.924 g / cm ³ , preferably 0.885 to 0.9
20 g / cm ³ , more preferably 0.890 to 0.91
5 g / cm ³ . When the density is larger than the above range,
Transparency and impact strength are poor. On the other hand, if the density is too low, the film becomes less rigid and the film surface becomes sticky, which is preferable.

Extrapolation melting end temperature (Tem) of the melting peak by differential scanning calorimetry (DSC) In the case of the ethylene-α-olefin copolymer used in the intermediate layer (B) of the present invention, the differential scanning calorimetry is used. (DSC)
Is one melting peak in the differential melting curve obtained by the above method, and the extrapolative melting end temperature (Te
m) is in the range from 50 to 130C, preferably from 60 to 122C, particularly preferably from 70 to 118C. Further, as for the relationship between the temperature (Tem) and the density (D ₂ ) of the copolymer itself, it is necessary to satisfy the following relational expression: Tem ≦ 286D ₂ -137. Preferably Tem ≦ 429D
₂ -271, and most preferably Tem ≦ 571D ₂ -404
It is desirable to satisfy

When there is no peak in the differential melting curve,
It is not preferable because stickiness occurs when the film is formed. The differential melting curve preferably has one peak, and when there are two or more peaks, the transparency, impact strength, and tensile strength are undesirably poor.

Extrapolated melting end temperature of the above peak (Tem)
Is smaller than the above range, blocking tends to occur when formed into a film. On the other hand, if the temperature is higher than the above range, transparency, impact strength, and tensile strength become poor, which is not preferable.

In some cases, a component that melts at a temperature other than the melting temperature of the peak may be recognized, but a material having a very slow melting behavior is not recognized as a peak. 3. Production Method The ethylene-α-olefin copolymer used in the inner layer (A ₁ ), the outer layer (A ₂ ) and the intermediate layer (B) of the present invention can be produced by various methods. JP-A-58-19309, JP-A-59-95292, JP-A-60-35005, JP-A-60-35006,
JP-A-60-35007, JP-A-60-35008
JP-A-60-35009, JP-A-61-13033
No. 14, JP-A-3-163088, EP-A-420,436, U.S. Pat. No. 5,055,438, and International Publication WO0
For example, a metallocene catalyst or a metallocene / alumoxane catalyst as described in JP-A-91 / 04257 or the like can be used, or, for example, WO092 / 0712.
For example, a catalyst composed of a metallocene compound and a compound which reacts with the metallocene compound to form a stable ion as disclosed in the specification of JP-A No. 3 is used to obtain ethylene as a main component and α-olefin as a subcomponent. Can be produced by copolymerizing 4. Metallocene catalyst A compound that reacts with a metallocene compound to form a stable ion is an ionic compound or an electrophilic compound formed from an ion pair of a cation and an anion, and these are stable ions that react with a metallocene compound. To form polymerization active species. Among them, the ionic compound is represented by the following formula (I).

[Q] ^{m +} [Y] ^m− (m is an integer of 1 or more) In the formula, Q is a cation component of the ionic compound, for example, a carbonium cation, a tropylium cation,
Ammonium cation, oxonium cation, sulfonium cation, phosphonium cation and the like, and further,
Metal cations and organic metal cations that are easily reduced by themselves are exemplified.

These cations are disclosed in JP-T-1-5019.
Not only a cation capable of giving a proton as disclosed in Japanese Patent Publication No. 50 and 50, but also a cation not providing a proton may be used. Specific examples of these cations include triphenylcarbonium, diphenylcarbonium, cycloheptatrienium, indenium, triethylammonium, tripropylammonium, tributylammonium, N, N-dimethylammonium, dipropylammonium, dicyclohexylammonium, Phenylphosphonium, trimethylphosphonium, tri (dimethylphenyl) phosphonium, tri (methylphenyl) phosphonium, triphenylsulfonium, triphenyloxonium, triethyloxonium, pyrylium, silver ion, gold ion, platinum ion, palladium ion, mercury Ion, ferrocenium ion and the like.

On the other hand, Y in the formula is an anionic component of the ionic compound. This is a component that reacts with the metallocene compound to form a stable anion, such as an organic boron compound anion, an organic aluminum compound anion, an organic gallium compound anion, an organic phosphorus compound anion, an organic arsenic compound anion, and an organic antimony compound anion. No. Specific examples of these compounds include tetraphenylboron, tetrakis (3,4,5-trifluorophenyl) boron, tetrakis [3,5-di (trifluoromethyl) phenyl] boron, tetrakis [3 5-di (t-butyl) phenyl] boron, tetrakis (pentafluorophenyl) boron, tetraphenylaluminum, tetrakis (3,4,5-trifluorophenyl) aluminum, tetrakis [3,5-di (trifluoromethyl) Phenyl] aluminum, tetrakis [3,5-di (t-butyl) phenyl] aluminum, tetrakis (pentafluorophenyl) aluminum, tetraphenylgallium, tetrakis (3,4
5-trifluorophenyl) gallium, tetrakis [3,5-di (trifluoromethyl) phenyl] gallium, tetrakis [3,5-di (t-butyl) phenyl]
Gallium, tetrakis (pentafluorophenyl) gallium, tetraphenylphosphorus, tetrakis (pentafluorophenyl) phosphorus, tetraphenylarsenic, tetrakis (pentafluorophenyl) arsenic, tetraphenylantimony, tetrakis (pentafluorophenyl) antimony, decaborate, undecarate Borate, carbado decaborate, decachloro decaborate and the like.

As the electrophilic compound, among the compounds known as Lewis acid compounds, those which react with metallocene compounds to form stable ions to form polymerization active species are used, and various metal halide compounds are used. And metal oxides known as solid acids. Specific examples of those corresponding to these include magnesium halide and Lewis acidic inorganic compounds. 5. α-Olefin In many cases, the α-olefin has 3 to 18 carbon atoms.
Α-olefin is used. Specifically, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-1-pentene, 4
-Methyl-1-hexene, 4,4-dimethyl-1-pentene and the like. Among these α-olefins,
Preferably those having 4 to 12 carbon atoms, particularly preferably those having 6 to 10 carbon atoms are desirable. This α-olefin is
In many cases, one of the above is selected and used, but two or more may be used simultaneously if desired. When the α-olefin is copolymerized with ethylene, 2 to 50% by weight, preferably 3 to 50% by weight of the α-olefin is used.
It is desirable to copolymerize 35% by weight, particularly preferably 5 to 25% by weight, and ethylene 50 to 98% by weight, preferably 75 to 97% by weight, particularly preferably 75 to 95% by weight. 6. Copolymerization Copolymerization methods include a gas phase method, a slurry method, a solution method,
A high-pressure ionic polymerization method can be used. Among these, a solution method and a high-pressure ionic polymerization method are preferable, and a high-pressure ionic polymer that can further exert the effects of the present invention is particularly preferable.

This high-pressure ionic polymerization method is disclosed in
No. 18607 and JP-A-58-225106.
kg / cm ² or more, preferably 300-2,000 kg /
cm ² , temperature is 125 ° C. or higher, preferably 130 to 25
This is a method for producing an ethylene polymer which is carried out under a reaction condition of 0 ° C, particularly preferably 150 to 200 ° C. 7. Laminated Structure The multilayer film of the present invention comprises an inner layer (A ₁ ) / intermediate layer (B)
/ At least three layers of the outer layer (A ₂ ), and a known base material layer, protective layer and the like can be provided as necessary. Among them, a three-layer structure of A ₁ / B / A ₂ is preferable.

As described above, the ethylene-α-olefin copolymer (a) used for the inner layer (A ₁ ) and the outer layer (A ₂ ) needs to satisfy specific requirements with respect to MFR, density and Tem. However, as long as this requirement is satisfied, they may be the same or different, and can be appropriately selected for each layer according to the intended use.

The density (D ₁ ) of the ethylene-α-olefin copolymer (a) is higher than the density (D ₂ ) of the ethylene-α-olefin copolymer (b) used for the intermediate layer. It is necessary. This is because if the density (D ₁ ) is lower than the density (D ₂ ), the blocking between the films becomes poor, which is not preferable. 8. Other additives and components The ethylene-α-olefin copolymer (b) used in the intermediate layer (B) of the present invention includes Mg, Ca, Al and Si.
And an inorganic compound containing at least one atom selected from the group consisting of: This inorganic compound may be in the form of any of its oxides, hydroxides, and ramming compounds. Specifically, SiO ₂ , Al ₂ O ₃ , MgO, Ca
O, Al (OH) ₃ , Mg (OH) ₂ , Ca (OH) ₂ ,
Alternatively, a compound represented by the following general formula (II) or a substance called a hydrotalcite in a calcined product thereof may be used.

General Formula M 2 ⁺ _{1 -X} Al _X (OH) ₂ (A ⁿ⁻ ) _{x / n} · mH ₂ O (II) In the formula, M ²⁺ is selected from the group consisting of Mg, Ca and Zn. Denotes a divalent metal ion, and x and m satisfy the following conditions:

0 <x <0.5, 0 ≦ m ≦ 2 Of these, preferred are hydrotalcites, and particularly preferred is a calcined product of the compound represented by the general formula (II) (usually at 200 to 300 ° C.). Firing). One or two or more of these inorganic compounds can be used in combination. These inorganic compounds have an average particle size of 10 μm or less,
Preferably it is 5 μm or less, particularly preferably 3 μm or less. If the average particle size is too large, the transparency of the film is impaired, which is not preferable.

The ethylene-α-olefin copolymers (a) and (b) forming the multilayer film of the present invention may contain, if necessary, various known auxiliary additives commonly used for resin compositions, For example, antioxidants (among others, phenol and phosphorus antioxidants are preferred), light stabilizers, antiblocking agents, slip agents, heat stabilizers,
An ultraviolet absorber, a neutralizing agent, an antifogging agent, a colorant, a pigment, a nucleating agent and the like can be blended. As for the antifogging agent, a known film surface coating type antifogging agent can be applied onto the multilayer film.

Further, in order to improve the moldability in forming a film, an ethylene polymer, for example,
High-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, or the like can be added as necessary. in this case,
The addition amount is 5 to 5 as long as the toughness of the base ethylene-α-olefin copolymer is not practically impaired.
15% by weight is preferred. 9. Production of agricultural multilayer film The agricultural multilayer film of the present invention comprises an ethylene-α-olefin copolymer (a) and (b) containing a predetermined additive.
By a known molding method. Examples of the manufacturing method include an extruder according to the number of layers and a usual feed block type, a multi-manifold type, a multi-slot type air-cooled blown film molding having a joining / merging portion, a T-die film molding, a water-cooled blown film molding, and the like. And
A suitable film can be obtained by any of these methods.

The multilayer composition ratio is such that the thickness of the outer layer is 5 to 1
00 μm, preferably 10 to 80 μm, more preferably 15 to 60 μm, and the thickness of the intermediate layer is 10 to
150 μm, preferably in the range of 20 to 120 μm, more preferably 30 to 100 μm, the thickness of the inner layer,
5-100 μm, preferably 10-80 μm, more preferably 15-60 μm, and the total thickness of these layers is 30-200 μm, preferably 50-1 μm.
Those having a diameter of 80 μm, more preferably 70 to 150 μm are desirable.

The film of the present invention can be subjected to various treatments such as corona discharge treatment, flame treatment, stretching treatment and liquid agent coating treatment as required.

[0043]

The present invention will be described more specifically below with reference to examples and comparative examples. [I] Measurement and evaluation methods of physical properties Measurement and evaluation of physical properties in Examples and Comparative Examples were carried out by the following methods.

(1) Method of measuring physical properties (a) MFR: Measured according to JIS-K7210. (B) Density: measured according to JIS-K7112. (C) Extrapolation melting end temperature (Tem) of the melting peak by differential scanning calorimetry (DSD): 5 mg of a sample was weighed from a 100 μm film formed by hot pressing,
It was set on an RDC 220 differential scanning calorimeter manufactured by Seiko Electronic Industry Co., Ltd., heated to 170 ° C. and kept at that temperature for 5 minutes, and then cooled at a rate of 10 ° C./min to −10.
Cooled to ° C. Next, after holding for 1 minute, the heating rate was 10
The temperature was increased to 170 ° C. at a rate of ° C./min, and the measurement was performed. As a result, the temperature was raised from -10 ° C to 170 ° C to obtain a DSC curve. According to JIS-K7121, extrapolate the temperature at the intersection of a line obtained by extending the high-temperature-side baseline of the DSC curve to the low-temperature side and a tangent drawn at the point where the gradient on the high-temperature side curve of the melting peak becomes maximum. The melting end temperature (Tem) was set.

(2) Evaluation method (a) Initial haze: Measured according to JIS-K7105. (B) Haze after exposure: After exposure of the film outdoors for 12 months, it was measured in accordance with JIS-K7105. (C) Vertical tensile break strength: measured in accordance with JIS-K6781. (D) Vertical Elmendorf tear strength: JIS-Z170
2 was measured. (E) Punching impact strength: Measured according to JIS-P8134, by attaching a metal penetrating part having a 13.0 mm hemispherical mirror gloss to the tip of the arc-shaped arm of the pendulum. (F) Blocking: After aligning the inner and outer surfaces of the film at a temperature of 45 ° C. and a load of 15 kg, the film was allowed to stand for 7 days to promote the adhesion between the films. Next, the adhesive surface is 500
It was cut to a size of 500 mm x 500 mm, the adhesive surface was peeled off by hand, and the blocking was evaluated according to the following criteria. ：: Smooth peeling without resistance. ×: Stable peeling is not possible due to resistance. Example 1 (1) Preparation of component A (a) Preparation of catalyst The catalyst was prepared by the method described in JP-A-61-130314. That is, to 2.0 mmol of the complex ethylenebis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, methylalumoxane (manufactured by Toyo Stouffer) was added 1,000 times as much as the complex and diluted to 10 liters with toluene. Thus, a catalyst solution was prepared. (B) Polymerization A mixture of ethylene and 1-hexene was supplied to a stirred autoclave type continuous reactor having an internal volume of 1.5 liters so that the composition of 1-hexene became 75% by weight, and the pressure in the reactor was increased. Was maintained at 1300 kg / cm ² and the reaction was carried out at a temperature of 150 ° C.

After completion of the reaction, the MFR was 2.2 g / 10 min.
An ethylene-1-hexene copolymer having a density of 0.910 g / cm ³ , one melting peak by differential scanning calorimetry (DSC) and an extrapolated melting end temperature (Tem) of 108 ° C. is obtained. Was. (C) Compounding The obtained copolymer was mixed with an appropriate amount of Irganox 1076 (manufactured by Ciba-Geigy) and P-EPQ (manufactured by Sandos) as antioxidants to prepare Component A. (2) Preparation of Component B Using the same catalyst and reactor as in (1), polymerization was carried out by changing the supply amount of 1-hexene, the pressure and temperature in the reactor,
MFR 2.2 g / 10 min, density 0.895 g / cm
^{In 3} , an ethylene-1-hexene copolymer having one melting peak by differential scanning calorimetry (DSC) and having an extrapolated melting end temperature (Tem) of 98 ° C. was obtained.

Irganox 1076 (manufactured by Ciba-Geigy) and P-
An appropriate amount of EPQ (manufactured by Sandoz Co., Ltd.) was blended to prepare Component B. (3) Preparation of Component C Using the same catalyst and reactor as in (1), polymerization was carried out by changing the supply amount of 1-hexene, the pressure and temperature in the reactor,
MFR 2.2 g / 10 min, density 0.905 g / cm
^{In 3} , there was one melting peak by differential scanning calorimetry (DSC) and the extrapolated melting end temperature (Tem) was 105 ° C.
Was obtained as the ethylene-1-hexene copolymer.

Irganox 1076 (manufactured by Ciba-Geigy) and P-
An appropriate amount of EPQ (manufactured by Sandoz Co., Ltd.) was blended to prepare Component C. (4) Preparation of Component D The ethylene-1-hexene copolymer used for Component B was treated with a hydrotalcite calcined product (trade name: DHT-4A-2, manufactured by Kyowa Chemical Industry Co., Ltd .; 4 μm)
Was mixed at a ratio of 40% by weight with respect to the ethylene-1-hexene copolymer.
To obtain a component D (inorganic substance masterbatch). (5) Film Forming and Evaluation Using resin pellets of Component A, Component B, Component C, and Component D as appropriate, molding at 180 ° C. with a multilayer inflation molding machine manufactured by Mitsubishi Chemical Engineering Co., Ltd. 17 μm of component A, 100% by weight), 66 μm of intermediate layer (mixture of 78% by weight of component B and 22% by weight of component D) and 17 μm of outer layer (component C, 100% by weight)
m was obtained as a three-layer blown film. The inner layer and the outer layer each contained 0.8% by weight of dicalite white filler (manufactured by Rasa Shoji) as an antiblocking agent and 0.2% by weight of oleic amide (manufactured by Nippon Kasei Co., Ltd.) as a slipping agent.

The three-layer film was evaluated.
Table 1 shows the results. Example 2 Except that the resin pellet used for the outer layer was 100% by weight of the component A, it was molded and evaluated in the same manner as in Example 1. Table 1 shows the results. Example 3 The resin pellet used for the inner layer was 100% by weight of the component C, and the resin pellet used for the outer layer was 100% by weight of the component A.
Except for the above, molding and evaluation were performed in the same manner as in Example 1.
Table 1 shows the results. Example 4 The resin component used for the inner layer and the outer layer was found to have an MFR of 2.0 g /
Ethylene-1 having a density of 0.915 g / cm ³ , a single melting peak by differential scanning calorimetry (DSC), and an extrapolated melting end temperature (Tem) of 113 ° C. for 10 minutes.
-Molded and evaluated in the same manner as in Example 1 except that the hexene copolymer was 100% by weight. Table 1 shows the results. Example 5 Example 1 was repeated except that the resin pellets used for the intermediate layer were a mixture of 70% by weight of component B and 30% by weight of component D.
Molding and evaluation were performed in the same manner as in the above. Table 1 shows the results. Example 6 Example 1 was repeated except that the resin pellet used for the intermediate layer was a mixture of 63% by weight of the component B and 37% by weight of the component D.
Molding and evaluation were performed in the same manner as in the above. Table 1 shows the results. Comparative Example 1 (1) Preparation of Component E LV420 grade of Novatec (registered trademark) EVA manufactured by Nippon Polychem Co., Ltd. (vinyl acetate content is 15% by weight,
An ethylene-vinyl acetate copolymer resin having an MFR of 0.5 g / 10 min) was treated with a hydrosite calcined product (trade name: DHT-4A-2, average particle size: 0.4 μm, manufactured by Kyowa Chemical Co., Ltd.).
m) was mixed with the resin at a ratio of 40% by weight, and the mixture was granulated with a twin-screw extruder at an extrusion temperature of 200 ° C. to prepare a component E (inorganic substance masterbatch). did. (2) Film molding and evaluation Resin pellets used for the intermediate layer were the same as those described in (1) above, Novatech (registered trademark) EVA LV4 manufactured by Nippon Polychem Co., Ltd.
Molding and evaluation were performed in the same manner as in Example 1, except that a mixture of 78% by weight of 20 grades and 22% by weight of component E was used. Table 2 shows the results. Comparative Example 2 A resin component used for the inner layer and the outer layer had an MFR of 2.0 g /
Ethylene-1- with a density of 0.935 g / cm ³ , a melting peak by differential scanning calorimetry (DSC) of 1 and an extrapolated melting end temperature (Tem) of 131 ° C. for 10 minutes
Molding and evaluation were performed in the same manner as in Example 1 except that the hexene copolymer was 100% by weight. Table 2 shows the results. Comparative Example 3 The same as Example 1 except that the resin pellet used for the intermediate layer was a mixture of 78% by weight of the component C and 22% by weight of the component D, and the resin pellet used for the outer layer was 100% by weight of the component B. Molding and evaluation. Table 2 shows the results. Comparative Example 4 The resin component used for the inner layer and the outer layer was 100% by weight of Novatec (registered trademark) LV120 manufactured by Nippon Polychem Co., Ltd., and the resin pellet used for the intermediate layer was Nippon Polychem Co., Ltd.
Molding and evaluation were performed in the same manner as in Example 1 except that a mixture of 78% by weight of Novatec LV420 and 22% by weight of component E was used. Table 2 shows the results. Comparative Example 5 A commercially available polyvinyl chloride film was evaluated in the same manner as in Example 1. Table 2 shows the results.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

The film of the present invention has an excellent transparency equivalent to that of a polyvinyl chloride film which has been used for a long time, and a toughness exceeding it, as compared with a conventional agricultural multilayer film. Have Specifically, by laminating at least three layers of two types of ethylene-α-olefin copolymers having specific properties, agricultural properties having excellent transparency, tear strength, impact strength and tensile strength are obtained. A multilayer film is obtained.

Claims (3)

[Claims] 1. An agricultural multilayer film having a laminated structure of at least three layers of an inner layer (A ₁ ) / intermediate layer (B) / outer layer (A ₂ ), wherein (1) an inner layer (A ₁ ) and an outer layer ( A ₂ ) has a melt flow rate within a range of 0.1 to 50 g / 10 minutes, a density (D ₁ ) within a range of 0.900 to 0.928 g / cm ³ , and a differential scanning calorimetry (DSC). ) Of the melting peak obtained by the extrapolation melting end temperature (Tem) is 70 to 130 ° C.
From the ethylene-α-olefin copolymer (a) in which the relation between the extrapolation melting end temperature (Tem) and the density (D ₁ ) satisfies the relational expression Tem ≦ 286D ₁ -137. (2) The intermediate layer (B) has a melt flow rate within a range of 0.1 to 50 g / 10 minutes and a density (D ₂ ) within a range of 0.880 to 0.924 g / cm ^3. Extrapolation melting end temperature (Tem) of the melting peak obtained by differential scanning calorimetry (DSC) is 70 to 130 ° C.
From the ethylene-α-olefin copolymer (b) in which the relation between the extrapolation melting end temperature (Tem) and the density (D ₁ ) satisfies the relational expression Tem ≦ 286D ₂ -137. (3) The density (D ₁ ) of the ethylene-α-olefin copolymer (a) forming the inner layer (A ₁ ) and the outer layer (A ₂ ) is determined by the ethylene-α-olefin forming the B layer. Greater than the density (D ₂ ) of the polymer (b), and
(4) The ethylene-α-olefin copolymer (b) forming the intermediate layer (B) contains one or more inorganic compounds containing at least one atom selected from the group consisting of Mg, Ca, Al and Si. A multilayer film for agricultural use, characterized by being filled at a ratio of up to 20% by weight. 2. The agriculture according to claim 1, wherein each of the ethylene-α-olefin copolymers (a) and (b) forming each layer is a polymer produced using a metallocene catalyst. For multilayer film. 3. The ethylene-α-olefin copolymer (a) and (b) forming each layer are both ethylene and an α-olefin copolymer having 3 to 18 carbon atoms. Item 3. The agricultural multilayer film according to Item 1 or 2.