JP2003311890A - Agricultural flexible multilayered film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agricultural flexible multilayered film further excellent in transparency, toughness and flexibility while holding heat insulating properties, becoming easy in ventilation work in a house or a tunnel, reduced in film bulkiness at the time of keeping and housing of the film after use over one season, and not whitened under a much moisture condition. <P>SOLUTION: The agricultural flexible multilayered film is constituted of at least three layers, that is, an inner layer A, an interlayer B and an outer layer C, and the Young's modulus thereof is not more than 120 N/mm<SP>2</SP>. A specific ethylene/vinyl acetate copolymer is used in the inner layer A and the interlayer B, and polyethylene is used in the outer layer C. The respective layers contain an inorganic filler having a specific surface area. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an agricultural flexible multilayer film used as a covering material for houses and tunnels. More specifically, it has excellent transparency, flexibility, toughness, and heat retention, and reduces ventilation work in houses and tunnels.
The present invention relates to an agricultural flexible multi-layer film that requires less storage space for the film after one season and does not whiten when exposed to high humidity.

[0002]

2. Description of the Related Art Various plastic films are used as covering materials for agricultural houses and tunnels.
Typical of them are polyvinyl chloride film (hereinafter referred to as farming) and polyethylene film (hereinafter referred to as
Agricultural poly), ethylene vinyl acetate copolymer film (hereinafter referred to as agricultural vinegar), agricultural polyolefin special film (hereinafter referred to as agricultural multilayer film), and the like.

Among them, agricultural crops are most often used because they are excellent in heat retention, transparency and economy. But,
Agricultural plastic has a large specific gravity, and thus the weight of the film becomes large when it is spread on the house, which makes the spreading work difficult. Also,
There is also a problem that hydrogen chloride gas is generated when incineration is performed as a disposal process after use, and agricultural substitutes that do not generate harmful gas are desired.

On the other hand, agricultural poly- or agricultural vinegar is superior to agricultural-biologically in terms of dust resistance and ease of disposal.
However, agricultural poly is inferior in heat retention, flexibility and toughness, so it is difficult to grow crops and ventilation work in a house or tunnel is difficult to perform, and when storing the film after one season of use, the film bulk at the time of storage It has become expensive and requires a large storage space, and improvements have been desired. In addition, although agricultural vinegar has improved flexibility compared to agricultural poly, it has problems such as film blocking and has poor heat retention compared to agricultural vine, causing poor growth of crops.

In recent years, in place of conventional multi-site catalysts
Ethylene-α-o obtained using a single-site catalyst
Development of linear low density polyethylene which is a reffin copolymer
And the density is 0.9 in Japanese Patent Laid-Open No. 9-53232.
25-0.940g / cm^ThreeEthylene-α-olefin
Outer layer of copolymer (large outside the house or tunnel)
Layer in contact with air), density 0.880-0.910 g / c
m^ThreeIntermediate consisting of ethylene-α-olefin copolymer
Layer and density 0.905 to 0.930 g / cm ^ThreeEmpty
Inner layer consisting of ethylene-α-olefin copolymer
Agricultural in which the layers in contact with the atmosphere inside the uss and the tunnel) are stacked
Commercial laminated films have been proposed. In addition, JP-A-8-
No. 276,542 discloses an ethylene-vinyl acetate copolymer.
As an intermediate layer, and ethylene-α-olefin as an inner layer and an outer layer.
A multi-layer film for agriculture using a copolymer has been proposed
There is.

Although these agricultural multilayer films have improved toughness, they are inferior in flexibility and the film does not have appropriate stickiness.
Part of the tucked-up film fell, and the ventilation efficiency in the house and tunnel deteriorated, which could affect the growth of crops. In addition, in recent years, in order to reduce the cost of covering materials, single-year films tend to be used for about two seasons, and after one season's use, the film is put in a box and stored in a barn, etc., and then two seasons later. The number of cases where the eyes are used and discarded is increasing. When the film is stored after one season, if the film is not flexible, the film becomes bulky when stored, and there is a problem that a wide storage space is required. Furthermore, if water from crops in the house or irrigation or water from outdoor rain adheres, the film absorbs water and a phenomenon of whitening occurs,
There was a problem that the photosynthesis of crops was affected because the light transmittance decreased.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to maintain heat retention while being excellent in transparency, toughness and flexibility,
Ventilation work in a house or tunnel is facilitated, and when storing the film after one season of use, the bulk of the film during storage is small and the storage space is reduced, and a flexible multilayer film for agriculture that does not whiten when humid is provided. That is.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems. As a result, an agricultural flexible multilayer film composed of at least three layers of an inner layer A, an intermediate layer B and an outer layer C, and having a Young's modulus of 120 N / mm ² or less, and ethylene specific to the inner layer A and the intermediate layer B is used. Based on this finding, it was found that a flexible agricultural multilayer film that uses a vinyl acetate copolymer and polyethylene as the outer layer C, and each layer contains an inorganic filler having a specific surface area, solves the above-mentioned problems. The present invention has been completed.

The present invention comprises the following: 1. A flexible agricultural multilayer film composed of at least three layers of an inner layer A, an intermediate layer B and an outer layer C, wherein the three layers are composed of the following layers, and the agricultural flexible multilayer film has a longitudinal (MD) direction. And a Young's modulus in the transverse (TD) direction is 120 N / mm ² or less, respectively, and a flexible agricultural multilayer film.

(1) 5% by weight of an inorganic filler having a BET specific surface area of 5 to 50 m ² / g with respect to polyethylene
An outer layer C composed of a composition containing

(2) The vinyl acetate content is 1 to 5% by weight,
The BET specific surface area is 5 to 50 with respect to the ethylene vinyl acetate copolymer having a density of 0.850 to 0.970 g / cm ^3.
an inner layer A composed of a composition containing 5% by weight or less of an inorganic filler of m ² / g,

(3) Vinyl acetate content of 10 to 30 weight
%, Density 0.850-0.970 g / cm^ThreeEchile of
BET specific surface area of 5 to that of vinyl acetate copolymer
50m ^Two1 to 10% by weight of an inorganic filler of 1 / g
An intermediate layer B composed of the composition described above.

2. When the outer layer C is composed of a composition further containing an ethylene vinyl acetate copolymer with respect to the composition, and the vinyl acetate content of the composition is I and the vinyl acetate content of the composition is II, I> The flexible agricultural multilayer film according to 1 above, which satisfies the condition II.

3. 2. The agricultural flexible multilayer film according to 1 above, wherein the inorganic filler is at least one selected from talc, hydrotalcite-based compounds and lithium-aluminum composite hydroxide salt-based compounds.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The agricultural flexible multilayer film according to the present invention will be described in detail below. The ethylene vinyl acetate copolymer used in the composition constituting the intermediate layer B of the present invention has a vinyl acetate content of 10 to 30% by weight, particularly preferably 10 to 20% by weight in terms of cost. The density of the vinyl acetate copolymer is 0.85.
It is in the range of 0 to 0.970 g / cm ³ .

The ethylene vinyl acetate copolymer used in the composition constituting the inner layer A of the present invention has a vinyl acetate content of 1 to 5% by weight, particularly preferably 3 to 5% by weight. The density of the vinyl acetate copolymer is 0.850 to
It is in the range of 0.970 g / cm ³ .

The polyethylene used in the composition constituting the outer layer C of the present invention is not particularly limited. Density 0.8
8 to 0.92 g / cm ³ low density polyethylene, linear low density polyethylene, density 0.94 to 0.97 g / cm ³
The ethylene-α-olefin copolymer having a density of 0.88 to 0.94 g / cm ³ polymerized by using the high-density polyethylene and the single-site catalyst is preferably used in terms of transparency and price, Density 0.88-0.92 g / cm
Low density polyethylene of ³ or the like is preferably used.

The outer layer C may be composed of a composition further containing an ethylene vinyl acetate copolymer. The ethylene vinyl acetate copolymer preferably has a vinyl acetate content of 5 to 30% by weight, and the vinyl acetate copolymer preferably has a density of 0.850 to 0.970 g / cm ³ .

When the vinyl acetate content of the composition constituting the inner layer A is I and the vinyl acetate content of the composition constituting the outer layer C is II, it is preferable that the condition of I> II is satisfied. As a result, the film does not whiten when the humidity is high, and the light transmittance is not significantly reduced.

The production method of the resin used in the composition constituting each layer in the present invention is not limited. Moreover, it is also possible to select and use those having desired specifications from the market.

The composition constituting each of the inner layer A, the intermediate layer B and the outer layer C of the agricultural flexible multilayer film of the present invention contains an inorganic filler for the purpose of improving the heat retention of the multilayer film. As the inorganic filler, silicon oxide,
Silicate compounds such as magnesium silicate, aluminum silicate and calcium silicate, aluminosilicate compounds such as calcium aluminosilicate, sodium aluminosilicate, potassium aluminosilicate, aluminate compounds such as alumina, sodium aluminate, potassium aluminate and calcium aluminate, carbonic acid Calcium, the following formula (2), the following formula (3), the following formula (4) and the following formula (5), the lithium-aluminum complex hydroxide salt-based compound and the hydrotalcite represented by the following formula (6). At least one type of inorganic filler selected from the group of compounds and the like can be mentioned.

Li ⁺ (Al ³⁺ ) ₂ (OH ⁻ ) ₆ · (A ₂ ⁿ⁻ ) _{1 / n} · mH ₂ O (2) (In the formula, A ₂ ⁿ⁻ is an n-valent anion, and m is 0 ≦. (m represents a number in the range of 3 and n represents a number in the range of 1 ≦ n ≦ 3.)

[Al ₂ Li (OH) ₆ ] ₂ (A ⁿ⁻ ) .mH ₂ O (3) (In the formula, A ⁿ⁻ represents an n-valent anion, and m represents a number of 3 or less.)

[(Al ³⁺ ) ₂ (Li ⁺ _(1-x) ^{.M 2+} _x ) (OH ⁻ ) ₆ ] ₂ · (Si _y O _{(2y + 1)} ^{2 −} ) _{(1 + x)} · mH ₂ O (4) (In the formula, M ²⁺ is a divalent metal ion, m is a number in the range of 0 ≦ m <5, x is a number in the range of 0 ≦ x <1, y is 2
A number in the range of ≦ y ≦ 4 is shown. )

[(Al ³⁺ ) ₂ (Li ⁺ _(1-x) · M ²⁺ _x ) (OH ⁻ ) ₆ ] ₂ · (A ⁿ⁻ ) _{2 (1 + x) / n} · mH ₂ O (5) (Formula ^Where M ²⁺ is a divalent metal ion, A ⁿ⁻ is an n-valent anion, m is a number in the range of 0 ≦ m <5, and x is a number in the range of 0.01 ≦ x <1. , N is a number in the range of 1 ≦ n ≦ 3.)

M ²⁺ _1-x Al ³⁺ _x (OH ⁻ ) ₂ (A ₁ ⁿ⁻ ) _{x / n} · mH ₂ O (6) (In the formula, M ²⁺ is Mg ²⁺ , Ca ²⁺ , and Zn ^2+. Of at least one divalent metal ion selected from the group, A ₁ ⁿ⁻ is an n-valent anion, x is a number in the range of 0 <x <0.5, and m is 0 ≦ m ≦ 2. Number in the range, n is 1
A number in the range of ≤n≤3 is shown. )

As the inorganic filler, JIS Z
BET specific surface area of 5 to 50 measured according to 8830
m ² / g, preferably 5 to ²⁰ m ² / g is used. When the BET specific surface area is within this range, the antifog performance and the antifog performance due to the migration of the antifog and antifog agents to the film surface are sufficient, and their sustainability is sufficient.

The amount of the inorganic filler added to the composition of the intermediate layer B is 1 to 10% by weight. Similarly,
The addition amount to the composition constituting the inner layer A or the outer layer C is 5% by weight or less. When the amount added is in this range, the heat retaining property is sufficient, and the transparency and mechanical properties are not significantly deteriorated.

The agricultural flexible multilayer film of the present invention is
By using the above composition, the machine direction (MD) of the film
Direction Young's modulus and transverse (TD) direction Young's modulus are 120 N /
mm ^TwoSince it is below and has excellent flexibility,
Expresses ease of combing.

In the present invention, the composition constituting the inner layer A, the intermediate layer B and the outer layer C may contain a modifying resin or an additive which is usually used in an agricultural film, as long as the object of the present invention is not impaired. It can be blended. Examples of the additives include an antifogging agent, a weatherproofing agent, an antifog agent, an ultraviolet absorber, an antistatic agent, a lubricant, an antioxidant, a heat stabilizer, an antibacterial agent, and a coloring / coloring agent.

As a method for obtaining the composition constituting the inner layer A, the intermediate layer B and the outer layer C, the desired additives described above are added to the thermoplastic resin used for each layer, and a high speed such as Henschel mixer (trade name) is used. Examples thereof include a mixing method using a usual mixing device such as a mixer with a stirrer, a ribbon blender, and a tumbler mixer, and a pelletizing method using a normal single-screw extruder or a twin-screw extruder.

The thickness of the agricultural flexible multilayer film of the present invention varies depending on the place of use and the service life, but generally a thickness of about 0.05 to 0.3 mm is preferably used. The thickness T _a of the inner layer A, the thickness T _c of the thickness T _b and the outer layer C of the intermediate layer B but is not particularly limited, T _a: T _b:
The range of the thickness ratio of T _c = 1 to 5: 1 to 5: 1 to 5 is preferable.

The agricultural flexible multilayer film of the present invention can be produced by a technique such as an inflation method or a T-die method using the above-mentioned composition, and in addition to the intermediate layer B, it has a heat retaining property. It may be a multilayer film of four or more layers in which an intermediate layer D, an intermediate layer G for improving the antifogging property, an intermediate layer H containing recycled raw materials and the like are laminated. Furthermore,
A dust-proof coating agent, an anti-fogging coating agent or the like may be applied and dried to form a coating film on the surface.

The agricultural flexible multilayer film of the present invention may be transparent or satin, and may be used for mulching other than covering for agricultural houses (greenhouses), tunnels, etc., for bagging, etc. .

[0035]

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The evaluation of the agricultural flexible multilayer films in Examples and Comparative Examples was carried out by the following methods.

1) Total light transmittance and haze; JIS K
7105, the color computer "HGM-
2K ”(trade name, manufactured by Suga Test Instruments Co., Ltd.) was used to measure the product two weeks after the film was manufactured. The smaller the numerical value of haze, the better the transparency.

2) Tensile modulus (flexibility: Young's modulus); A
The tensile (MD) and transverse (TD) tensile modulus of a sample of film was measured according to STM D 882.

3) Tensile load: Tensile cutting loads in the longitudinal (MD) direction and the transverse (TD) direction were determined according to JIS K6732. It is tough when the tensile cutting load and tensile modulus are large.

4) Density; measured according to JIS K7112.

5) Melt flow rate (MFR); JI
It was measured according to SK 7210 under the conditions of 190 ° C. and 21.18 N.

6) Spreading test: A film having a film thickness of 0.1 mm, a length of 100 m, and a width of 2 m was banded in a tunnel house and stretched for 3 months, followed by tucking up every 5 m at 19 sites on one side and a total of 38 sites on both sides. Ventilation was performed, and the number of places where ventilation was taken up was measured. The higher the number,
Difficult to do tuck-up ventilation.

7) Storage test; film thickness 0.1 mm,
A film measuring 100 m in length and 2.7 m in width is stored in a box of 50 cm in length, 30 cm in width, 50 cm in height in a square shape, covered with an upper plate, and a weight of 5 kg is put on the top and pressure is measured for 3 minutes. did. The larger the number, the higher the bulk,
Needs storage space.

8) Water whitening resistance test; film thickness 0.1 m
m, length 15 cm, width 5 cm, cut the film, put 200 ml of water at a water temperature of 15 ° C. in a beaker, and haze after soaking for 12 hours in accordance with JIS K 7105. Color computer “HGM-2K” (trade name, Suga testing machine
(Manufactured by KK).

9) Heat retention (infrared reflection absorption rate, unit:
%); Infrared spectrometer (PERKIN ELMER PA
RAGON1000PC) 400-4000 cm ^-1
Infrared transmittance of the coating material in the wavenumber region of 10cm
^It was measured for each ^-1 and calculated by the following calculation formula. E ₁ = C ₁ λ ⁻⁵ / {exp (C ₂ / λT) −1} J / m ² · hr · m (7) (where λ is the wavelength (m), T is the absolute temperature (K), C ₁ is 1.346 × 10 ⁻¹² J · m ² / h, C ₂ is 0.01
It is 4387 m · K. ) A ₁ = E ₁ × {1- (IR transmittance at the inflection point)} (8) (A _{1 in the} formula is an infrared reflection absorptance for each 10 cm ⁻¹ .) S ₁ = (A ₁ + A ₂ ) × (λ ₂ −λ ₁ ) / 2 (9) (wherein λ ₂ · λ ₁ is the wavelength, A ₁ + A ₂ is each infrared reflection absorptivity, S ₁ is surrounded by the wavelength axis and the blackbody radiation curve. A = ΣS / ΣE (10) (In the formula, A is the infrared ray reflection / absorption rate up to a wavelength of 2.5 to 25 μm.) The higher the infrared ray reflection / absorption rate, the more the infrared rays emitted from the ground are transmitted. It shows that it is hard to do and is excellent in heat retention.

Examples 1 to 10 and Comparative Examples 1 to 9 Compositions for each layer were prepared according to the formulation for each layer of the agricultural flexible multilayer film shown in Tables 1 and 2 and the common formulation described below. . Using the composition obtained, using a three-kind three-layer inflation multilayer extruder having one 65 mmφ extruder and two 45 mmφ extruders at a molding temperature of 180 ° C.
A multilayer film having a thickness of 0.1 mm was formed. The thickness ratio of each layer of the multilayer film is outer layer: middle layer: inner layer = 1: 3: 1.
Is. The evaluation results of the obtained multilayer film are shown in Tables 1 and 2.

The symbols and contents of the resins used in the compositions constituting the layers of the multilayer films shown in Tables 1 and 2 are as follows. LDPE: low-density polyethylene, NUC8505 (trade name, manufactured by Nippon Unicar Co., Ltd.), MFR (190 ° C.) = 0.
8 g / 10 minutes, density = 0.92 g / cm ³

LLDPE: Linear low density polyethylene (ethylene-α-olefin copolymer), Dow Rex 2045AC (trade name, manufactured by Dow Chemical Co., Ltd.), MF
R (190 ° C) = 1.0 g / 10 minutes, density = 0.920 g
/ Cm ³ , α-olefin (1-butene) content <20
weight%

EVA (5%): ethylene-vinyl acetate copolymer having a vinyl acetate content of 5% by weight, NUC3250.
(Product name, manufactured by Nippon Unicar Co., Ltd.), MFR (190 ° C) =
1.5 g / 10 minutes, density = 0.93 g / cm ³

M-PE: Single-site catalyst type ethylene-α-olefin copolymer, Elite 5400 (trade name, manufactured by Dow Chemical Co., Ltd.), MFR (190 ° C.) = 1.
0 g / 10 minutes, density = 0.916 g / cm ³ , α-olefin (1-octene) content <20% by weight

EVA (25%): vinyl acetate content 2
5 wt% ethylene vinyl acetate copolymer, NUC319
5 (trade name, manufactured by Nippon Unicar Co., Ltd.), MFR (190
℃) = 4.0g / 10 min, density = 0.95 g / cm ³

EVA (15%): vinyl acetate content 1
5 wt% ethylene vinyl acetate copolymer, NUC845
2 (trade name, manufactured by Nippon Unicar Co., Ltd.), MFR (190
C) = 1.0 g / 10 min, density = 0.94 g / cm ^3.

EVA (10%): vinyl acetate content 1
0 wt% ethylene vinyl acetate copolymer, DQDJ18
30 (trade name, manufactured by Nippon Unicar Co., Ltd.), MFR (190
C) = 1.5 g / 10 min, density = 0.93 g / cm ^3.

Inorganic filler 1: synthetic hydrotalcite, DHT-4A (trade name, manufactured by Kyowa Chemical Industry Co., Ltd.)

In addition, the common compounding composition of each multilayer film shown in Tables 1 and 2 excluding the above-mentioned resins is based on the composition, in the outer layer C, the weathering agent is 0.2% by weight and the ultraviolet absorber is 0.1%. % By weight, phenolic stabilizer 0.1% by weight, phosphorus stabilizer 0.1% by weight, calcium stearate 0.
2% by weight, 0.1% by weight of anti-blocking agent, 0.2% by weight of antistatic agent, 0.3% by weight of weathering agent in intermediate layer B, 0.1% by weight of UV absorber, non-ionic antifogging agent Two
% By weight, 0.1% by weight of phenol-based stabilizer, 0.1% by weight of phosphorus-based stabilizer, 0.3% by weight of calcium stearate, 0.1% by weight of fog-preventing agent. 2% by weight, UV absorber 0.1% by weight, phenol stabilizer 0.1% by weight, phosphorus stabilizer 0.1% by weight,
Calcium stearate 0.2% by weight, anti-blocking agent 0.1%, antistatic agent 0.2% by weight.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

The agricultural flexible multilayer film of the present invention comprises:
It is an agricultural flexible multilayer film that is excellent in transparency, flexibility, heat retention, toughness, ventilation characteristics, storage efficiency and water whitening resistance.

Continued front page    F term (reference) 2B024 DB01 DB07 EA01                 2B029 EB03 EC02 EC06 EC09 EC14                       EC16 EC18 EC19 EC20                 4F100 AA00A AA00B AA00C AA17A                       AA17B AA17C AA19A AA19B                       AA19C AA33A AA33B AA33C                       AC10A AC10B AC10C AK04C                       AK06 AK62 AK63 AK68 AK68A                       AK68B AK68C AL05C BA03                       BA07 BA10A BA10B BA10C                       BA13 BA15 CA23A CA23B                       CA23C EH20 GB01 JA13A                       JA13B JB07 JJ02 JK01                       JK02 JK07 JK13 JK17 JN01                       YY00 YY00A YY00B YY00C

Claims (3)

[Claims] 1. At least an inner layer A, an intermediate layer B and an outer layer C
Is a flexible agricultural multilayer film composed of 3 layers.
The three layers are composed of the following layers, and are flexible for agriculture.
Longitudinal (MD) and transverse (TD) directions of the layered film
Each has a rate of 120 N / mm^TwoCharacterized by
Flexible multi-layer film for agriculture. (1) BET specific surface area of 5 to 5 relative to polyethylene
0m^TwoContains 5% by weight or less of an inorganic filler that is / g
Outer layer C composed of composition, (2) containing vinyl acetate
1-5% by weight, density 0.850-0.970 g /
cm^ThreeBET against ethylene vinyl acetate copolymer of
Specific surface area is 5-50m^Two5 times the inorganic filler which is / g
An inner layer A composed of a composition containing less than or equal to% by weight,
(3) The vinyl acetate content is 10 to 30% by weight, and the density is
0.850-0.970g / cm^ThreeEthylene vinyl acetate
BET specific surface area of 5 to 50 m ^Two/
A composition containing 1 to 10% by weight of an inorganic filler of g
An intermediate layer B composed of 2. The outer layer C is composed of a composition further containing an ethylene vinyl acetate copolymer in the composition, wherein the vinyl acetate content of the composition is I and the vinyl acetate content of the composition is II. The agricultural flexible multilayer film according to claim 1, wherein the condition I> II is satisfied. 3. The agricultural flexible multilayer film according to claim 1, wherein the inorganic filler is at least one selected from talc, hydrotalcite-based compounds and lithium-aluminum composite hydroxide salt-based compounds.