JPH089222B2 - Agricultural laminated film and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an agricultural laminated film and a method for producing the same. More specifically, the present invention is a laminated film for agriculture characterized by being excellent in heat resistance, impact resistance, abrasion resistance, tear resistance, puncture resistance, cold resistance, and high transparency, and a method for producing the same. And the film of the present invention is used for greenhouse cultivation, tunnel cultivation, mulch cultivation and the like for the purpose of forcing cultivation for agriculture.

[0002]

2. Description of the Related Art Polyvinyl chloride films, high-pressure low-density polyethylene films, linear low-density polyethylene films, etc. are mainly used as agricultural films that have been conventionally used for greenhouse cultivation and tunnel cultivation. it can.

Polyvinyl chloride film is excellent in transparency, toughness, durability, heat retaining property, economical efficiency, workability, etc. However, since it contains a plasticizer, it bleeds on the surface of the film. However, dust is adsorbed here, which lowers the light transmittance and gives a dirty feeling, which is not desirable.
Furthermore, if the polyvinyl chloride film is treated by incineration after use, hydrogen chloride gas will be generated, which may cause pollution problems, and it is vulnerable to piercing and tearing due to protrusions, and against frictional tearing with house aggregates. It was weak and poor in cold resistance, and often caused problems depending on the usage conditions.

Unlike the polyvinyl chloride film, the high-pressure method low-density polyethylene film does not generate hydrogen chloride gas when incinerated and does not use a plasticizer, so that it causes pollution problems, reduced light transmission, and dirt due to dust adhesion. Although there is an advantage that it does not exist, since the crystallinity is about 40%, the light transmittance (transparency) is slightly inferior. In addition, since the film is charged and water adheres to the film surface, when an antistatic agent or an antifogging agent is added, it has a drawback that it adsorbs bleed and dust on the film surface to lower the light transmittance.

The linear low-density polyethylene film is similar to the high-pressure low-density polyethylene film in the above properties, but is excellent in mechanical strength.
Since the thickness of the film can be reduced and the economic effect is great,
Although it has been widely used as an agricultural film, it has a problem of low light transmittance because of its high crystallinity. In addition, since these polyethylene films do not have a polar group in the molecule, they do not have the ability to absorb infrared rays. Therefore, infrared energy emitted from plants and soil in greenhouses at night is dissipated to the outside world, resulting in a lack of heat retention. There is.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides an agricultural film which has been improved in its drawbacks while maintaining the advantages of the polyvinyl chloride film and polyethylene film which have been conventionally used as agricultural films, that is, when incinerated. Agricultural film that does not generate harmful gas, does not need to use plasticizer, and has excellent puncture resistance, abrasion resistance, cold resistance, light transmission (high transparency), mechanical strength, and processability. It is an object to provide the manufacturing method.

[0007]

Means for Solving the Problems As a result of intensive research, the inventors of the present invention have produced a specific ethylene-α-produced by a specific method, which has never been used as an agricultural film.
The inventors have found that the above problems can be solved when a laminated film having a specific structure is formed by using an olefin copolymer and a specific ethylene-vinyl acetate copolymer as film layers, respectively, and completed the present invention.

That is, the present invention has a density of 0.910 g / ml.
Below, melting point 116 ℃ or more, 1% modulus 1200 kg
/ Cm ² or less, n-hexane extractable content of 10% by weight or less, melt index of 0.8 to 10 g / 10 minutes, and an intermediate layer composed of an ultra-low density ethylene-α-olefin copolymer, and melt index of 0.5 to A laminated film comprising 5 g / 10 minutes and both outer layers made of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 to 15% by weight, wherein the thickness of the intermediate layer is the total thickness of the laminated film. Of the laminated film, and the total thickness of the laminated film is 50 to 200 μm.

The present invention also has a density of 0.910 g / ml or less, a melting point of 116 ° C. or more, and a 1% modulus of 1200 kg /
cm ² or less, n-hexane extractable content 10% by weight or less, and melt index of 0.8 to 10 g / 10 minutes, and an intermediate layer made of an ultra-low density ethylene-α-olefin copolymer,
A laminated film for agriculture, characterized by being produced by coextrusion with both outer layers made of an ethylene-vinyl acetate copolymer having a melt index of 0.5 to 5 g / 10 minutes and a vinyl acetate content of 5 to 15% by weight. Manufacturing method.

In the present invention, the above-mentioned ultra-low density ethylene-
The α-olefin copolymer is the following continuous production method of ethylene copolymer: (a) a higher α-olefin: ethylene molar ratio at a temperature of 10 to 80 ° C. and a pressure of 7,000 kPa or less in a fluidized bed reaction zone. Is 0.35: 1 to 8.0: 1
A gas mixture containing ethylene and at least one higher α-olefin having 3 to 8 carbon atoms, and (b) at least 25 mol% of at least one diluent gas, having the formula: Mg _m Ti (OR) _n X _p [ED] _q (In the formula, R represents an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms or a group COR ', and R'is aliphatic having 1 to 14 carbon atoms. Or represents an aromatic hydrocarbon group, X
Is selected from the group consisting of chlorine atom, bromine atom, iodine atom and mixtures thereof, and ED is an organic group selected from the group consisting of alkyl esters of aliphatic or aromatic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. It represents an electron-donating compound, m is 0.5 to 56, n is 0, 1 or 2, p is 2 to 116, and q is 2 to 85. ) Is continuously contacted with particles of a catalyst system consisting of a precursor composition, said precursor composition is diluted with an inert carrier material and the following formula: Al (R ′) _d X ′ _e H _f (In the formula, X ′ represents a chlorine atom or a group OR ″, R ′ and R ″ represent a saturated hydrocarbon group having 1 to 14 carbon atoms, e is 0 to 1.5, and f is 0 or 1 and d
+ E + f = 3. ) Fully activated with an organoaluminum compound represented by the formula (1), and the activated compound has a molar ratio of total aluminum: titanium in the reaction zone of 10:
It is preferably produced by using an amount of 1 to 400: 1.

In the present invention, ultra-low density ethylene-α-
Olefin copolymer (hereinafter also referred to as VLDPE)
Is a special polyethylene resin developed by Union Carbide Chemical and Plastics Company of the United States, to which the inventors of the present invention belong and which has a technical tie-up with Nippon Unicar Co., Ltd., which is the applicant of the present application. This is described in detail in Japanese Patent Publication No. 59-230011.

The density of VLDPE used in the present invention is 0.910 g / ml or less, and if it exceeds this, the crystallinity increases and the transparency of the film deteriorates, which is not desirable. Also, the melting point of VLDPE is 116 ° C. or higher,
If it is less than this range, the heat resistance is insufficient and the mechanical strength is also insufficient. The 1% modulus of VLDPE is 1200
It is less than kg / cm ² , and if it exceeds this, the abrasion resistance is deteriorated. Furthermore, the amount of n-hexane extracted from VLDPE is 10
When the content is less than the weight%, the low molecular weight polymer bleeds on the surface of the laminated film, and dust adheres to the polymer to impede the light transmittance, which is not desirable. The melt index of VLDPE is 0.8 to 10 g / 10 minutes,
If it is less than 0.8 g / 10 minutes, the extrusion characteristics are poor, while on the other hand 10 g
If it exceeds / 10 minutes, mechanical properties are deteriorated, which is not desirable.

The above ethylene used in the present invention
The vinyl acetate copolymer (hereinafter, also referred to as EVA) has a melt index of 0.5 to 5 g / 10 minutes, and a melt index of 0.
If it is less than 5 g / 10 minutes, the extrusion property is poor, while on the other hand, it is 5 g / 10 minutes.
If it exceeds the limit, the mechanical properties deteriorate, which is not desirable. Also,
The vinyl acetate content is 5 to 15% by weight. When it is less than 5% by weight, the transparency of the laminated film is deteriorated, and when it exceeds 15% by weight, the laminated film is blocked, which is not desirable.

The relationship between the melting point (MP, unit ° C) and the vinyl acetate content (VA, unit% by weight) of EVA used in the present invention is represented by the following formula: MP = 114-1.44VA Those having a distribution (M _w / M _n ) of less than 4 are particularly desirable, and those having this numerical range have a melting point of 2 to 2 as compared with EVA having the same vinyl acetate content outside the above range.
It is 5 ° C higher and has excellent heat resistance and mechanical strength.

The agricultural laminated film of the present invention can be produced by a coextrusion molding machine, for example, an inflation method using a circular die, a T die method using a flat die, or the like. The reason for having a three-layer structure including an intermediate layer and both outer layers in the present invention is described below. First, when VLDPE is used alone to form a film, the extrusion processability is poor, and even if it is extruded, melt fracture occurs, a film with a smooth surface cannot be obtained, and the produced film is severely blocked and difficult to handle. Met. The present inventors have found that if VLDPE is used as an intermediate layer and resin layers are coextruded on both sides thereof, VLDPE, which is difficult to form by itself, can be formed, and this was adopted as the intermediate layer. Next, specific EVA was adopted as both outer layers of the VLDPE intermediate layer because EVA is superior in transparency as compared with high-pressure low density polyethylene and the like. However, in the case of EVA, the transparency and cold resistance increase as the vinyl acetate (VA) content increases, but the blocking properties and mechanical properties deteriorate, so the above range was set.

The thickness of the laminated film of the present invention is 50 to 2
If it is less than 50 μm, the mechanical strength will be insufficient, and the film will be difficult to handle. If it exceeds 200 μm, the quality will be excessive and the economy will be poor, such being undesirable.
The ratio of the VLDPE layer (intermediate layer) to the whole laminated film, that is, the ratio of thickness is 35 to 90%,
If it is less than 35%, the transparency, mechanical properties, cold resistance, abrasion resistance, economy and the like will be poor, and if it exceeds 90%, coextrusion will be impossible. The thickness of each outer layer may be the same or different, but it is essential that they account for at least 5% of the total thickness of the laminated film to allow coextrusion.

Although the heat retention of the laminated film of the present invention is slightly inferior to that of the polyvinyl chloride film, EVA of both outer layers is used.
As the thickness of the part is increased, the heat retaining property is improved. When higher heat retention is required, the following inorganic compound particles that are generally used as heat retaining agents: silicon oxide,
Anhydrous aluminosilicate, phosphate, sulfate, carbonate, hydroxyl group-containing magnesium, aluminate, etc. are blended with the raw material resin. Specifically, hydrous silica, anhydrous silica, synthetic silica, aluminum oxide, calcium oxide, zirconium oxide, titanium oxide, magnesium oxide, boron oxide, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, lithium hydroxide, calcium phosphate, phosphorus. Magnesium oxide, zinc carbonate, aluminum carbonate, calcium carbonate, barium carbonate, magnesium carbonate, lithium carbonate,
Zinc sulfate, aluminum sulfate, potassium sulfate, calcium sulfate, zirconium sulfate, barium sulfate, magnesium sulfate, aluminum silicate gel, aluminosilicate gel and the like are examples of the heat retaining agent, and the particle size thereof is 1 to 10 μm.
m, and the blending amount with respect to the raw material resin is preferably 10% or less. Although the heat retaining property of these heat retaining agents is enhanced by increasing the blending amount thereof, the light transmittance (transparency) is lowered, and therefore it is important to blend them in consideration of the balance between them. The VLDPE used in the present invention has the advantages of being excellent in the filling property of the inorganic compound granules and less in the decrease in mechanical strength, as compared with other polyolefin resins, which is one of the effects of the present invention.

[0018]

The present invention will be described in more detail based on the following examples. Example 1 Raw material / intermediate layer: Density 0.903 g / ml, melting point 117 ° C., 1%
An ethylene-butene-1 copolymer having a modulus (1% Md) of 950 kg / cm ² , an n-hexane extract (nH _eq ) of 2.8% by weight, and a melt index (MI) of 2 g / 10 min is disclosed in JP-A-59 / 1999. It was prepared according to the method described in No. 230011. Both outer layers: MI 2 g / 10 minutes, vinyl acetate (VA) content 10% by weight, melting point 99.6 ° C., ethylene-vinyl acetate copolymer having a molecular weight distribution of 3.5 are prepared using a high-pressure polyethylene manufacturing apparatus. did. Production of Laminated Film An inflation film was produced by rapid cooling with the following equipment and conditions. -Extrusion device: Inflation film processing device manufactured by Placo Co., Ltd. (caliber 40 mm x 3 units, L / D28) -Circular 3-layer die: φ150 mm, die cap 1.5 m
m ・ Cooling device: with single lip straight and conical color ・ Discharge rate: 60 kg / hr ・ Die temperature: 190 ° C ・ Blow ratio: 3.0 The thickness of the produced laminated film intermediate layer is 80 μm, and both outer layers are Both thicknesses are 1
0 μm. Evaluation and tear strength of laminated film for agriculture : 110kg / cm in the vertical direction and 126k in the horizontal direction.
It is g / cm, and is sufficiently practical. -Haze (measured according to JIS K-6714): 4.5
And the transparency is sufficient. -Heat resistance (tensile strength measured under an environment with an outside air temperature of 80 ° C): 45 g / cm ² , which is sufficiently practical. The outside temperature of 80 ° C. is a temperature at which the film near the steel aggregate of the agricultural house is exposed in the middle of summer. Examples 2 to 5 and Comparative Examples 1 to 11 The same experiment as in Example 1 was performed except that the raw material resins used for the intermediate layer and both outer layers and the thickness of each film layer were changed. The conditions and results of those experiments including Example 1 are summarized in Table 1 and Table 2, respectively.

[0019]

[Table 1] Experimental conditions Footprint in Table 1 ・ Unit density of items related to VLDPE and EVA properties: g / ml, melting point: ° C, 1% Md (modulus): kg / cm ² , nH _eq (n-hexane extract):
% By weight, MI: g / 10 minutes, α-olefin: number of carbon atoms, VA content:% by weight NUCG-5221 = low density linear ethylene-α-olefin copolymer manufactured by Nippon Unicar, density 0.921 g / Ml, MI: 1.0 g / 10 minutes-DFD-0118 = High pressure low density polyethylene manufactured by Nippon Unicar, density 0.923 g / ml, MI: 2.3 g
/ 10 minutes Toughmer A4090 = Amorphous ultra low density polyethylene manufactured by Mitsui Petrochemical, density 0.89 g / ml, M
I: 3.6 g / 10 minutes, melting point 86 ° C., Comparative Examples 4, 5, 6
The symbol Y in indicates that each substance was used. The unit of film thickness is μm.

[0020]

[Table 2] Experimental results (evaluation as a laminated film for agriculture) Footnotes in Table 2 ・ Unit of tear strength is kg / cm in both machine direction and machine direction ・ Evaluation in other items is as follows: A = Low molecular weight polyolefin is left for 3 months after production of laminated film. Bleed on the surface, resulting in poor transparency and dust adhesion. B = film formation was impossible C = film formation was impossible D = severe blocking E = film formation was not possible

[0021]

As described in detail above, the agricultural laminated film of the present invention comprises an intermediate layer made of a specific ultra-low density ethylene-α-olefin copolymer and a specific ethylene-based film.
Since it is composed of both outer layers composed of a vinyl acetate copolymer, it has excellent properties of both an ultra-low density ethylene-α-olefin copolymer and an ethylene-vinyl acetate copolymer, and does not exist conventionally. Agricultural film with well-balanced tear strength, transparency and heat resistance.

Therefore, the present invention is suitable for greenhouse cultivation, tunnel cultivation, mulch cultivation, etc., and has heat resistance, impact resistance, and
It has become possible to provide an agricultural laminated film having excellent abrasion resistance, tear resistance, puncture resistance, cold resistance, and high transparency, and a method for producing the same.

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Claims (4)

[Claims] 1. A density of 0.910 g / ml or less and a melting point of 116.
℃ or more, 1% modulus 1200 kg / cm ² or less, n
-Extra low density ethylene having a hexane extract content of 10% by weight or less and a melt index of 0.8 to 10 g / 10 minutes-α-
Intermediate layer composed of olefin copolymer, melt index 0.5 to 5 g / 10 minutes, vinyl acetate content 5 to 15
A laminated film composed of both outer layers consisting of ethylene-vinyl acetate copolymer in a weight percentage, wherein the thickness of the intermediate layer is at least 35 to 90 of the total thickness of the laminated film.
%, The total thickness of the laminated film is 50 to 200 μm
A laminated film for agriculture, characterized in that 2. A method for continuously producing an ethylene copolymer in which an ultra-low density ethylene-α-olefin copolymer is as follows: at a temperature of 10 to 80 ° C. and a pressure of 7,000 kPa or less in a fluidized bed reaction zone, ) Higher α-olefin: ethylene molar ratio of 0.35: 1 to 8.0: 1, ethylene and at least one higher α-olefin having 3 to 8 carbon atoms, and (b) at least 25 mol. At least 1%
A gas mixture containing a diluent gas of the species is prepared by the following formula: Mg _m Ti (OR) _n X _p [ED] _q (wherein R is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms or Represents a group COR ′, R ′ represents an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms, and X
Is selected from the group consisting of chlorine atom, bromine atom, iodine atom and mixtures thereof, and ED is an organic group selected from the group consisting of alkyl esters of aliphatic or aromatic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. It represents an electron-donating compound, m is 0.5 to 56, n is 0, 1 or 2, p is 2 to 116, and q is 2 to 85. ) Is continuously contacted with particles of a catalyst system consisting of a precursor composition, said precursor composition is diluted with an inert carrier material and the following formula: Al (R ′) _d X ′ _e H _f (In the formula, X ′ represents a chlorine atom or a group OR ″, R ′ and R ″ represent a saturated hydrocarbon group having 1 to 14 carbon atoms, e is 0 to 1.5, and f is 0 or 1 and d
+ E + f = 3. ) Is completely activated with an organoaluminum compound represented by the formula (4), and the activation compound has a total aluminum: titanium molar ratio in the reaction zone of 10:
The agricultural laminated film according to claim 1, which is produced by using an amount of 1 to 400: 1. 3. A density of 0.910 g / ml or less and a melting point of 116.
℃ or more, 1% modulus 1200 kg / cm ² or less, n
-Extra low density ethylene having a hexane extract content of 10% by weight or less and a melt index of 0.8 to 10 g / 10 minutes-α-
Intermediate layer composed of olefin copolymer, melt index 0.5 to 5 g / 10 minutes, vinyl acetate content 5 to 15
A method for producing a laminated film for agricultural use, comprising producing both outer layers made of ethylene-vinyl acetate copolymer in an amount of wt% by a coextrusion method. 4. A method for continuously producing an ethylene copolymer, wherein the ultra-low density ethylene-α-olefin copolymer is as follows: at a temperature of 10 to 80 ° C. and a pressure of 7,000 kPa or less in a fluidized bed reaction zone, ) Higher α-olefin: ethylene molar ratio of 0.35: 1 to 8.0: 1, ethylene and at least one higher α-olefin having 3 to 8 carbon atoms, and (b) at least 25 mol. At least 1%
A gas mixture containing a diluent gas of the species is prepared by the following formula: Mg _m Ti (OR) _n X _p [ED] _q (wherein R is an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms or Represents a group COR ′, R ′ represents an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms, and X
Is selected from the group consisting of chlorine atom, bromine atom, iodine atom and mixtures thereof, and ED is an organic group selected from the group consisting of alkyl esters of aliphatic or aromatic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. It represents an electron-donating compound, m is 0.5 to 56, n is 0, 1 or 2, p is 2 to 116, and q is 2 to 85. ) Is continuously contacted with particles of a catalyst system consisting of a precursor composition, said precursor composition is diluted with an inert carrier material and the following formula: Al (R ′) _d X ′ _e H _f (In the formula, X ′ represents a chlorine atom or a group OR ″, R ′ and R ″ represent a saturated hydrocarbon group having 1 to 14 carbon atoms, e is 0 to 1.5, and f is 0 or 1 and d
+ E + f = 3. ) Is completely activated with an organoaluminum compound represented by the formula (4), and the activation compound has a total aluminum: titanium molar ratio in the reaction zone of 10:
The method for producing a laminated film for agricultural use according to claim 3, wherein the method is used in an amount of 1 to 400: 1.