JP3343374B2 - Agricultural film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to agricultural films. More specifically, the present invention relates to an agricultural film characterized by excellent heat retention, heat resistance, impact resistance, tear resistance, puncture resistance, cold resistance, and high transparency, and a method for producing the same, And the film of this invention is used for house cultivation, tunnel cultivation, mulch cultivation, etc. for the purpose of forcing cultivation for agriculture.

[0002]

2. Description of the Related Art Conventionally, as an agricultural film for house cultivation, tunnel cultivation, etc., polyvinyl chloride is low in cost, has good handleability (workability), and is excellent in transparency, durability, heat retention and the like. Film has been used. However, since this film contains a plasticizer and is used for a long period of time, bleed occurs on the film surface, dust is adsorbed here, lowering the light transmittance, and also giving a dirty feeling. If used in incineration after use, hydrogen chloride gas may be generated, which may cause pollution problems.In addition, it is weak against piercing and tearing by protrusions and frictional tear with house aggregate, and has poor cold resistance. However, depending on the use conditions, it often causes a problem. On the other hand, polyolefin-based films are also used as agricultural films, but they have no polar groups in the molecule and therefore have no infrared absorption ability, and therefore are radiated from plants and soil in night, house, and tunnel house. The infrared energy is dissipated to the outside world, and there is a drawback that the heat retaining property is lacking. On the other hand, many heat insulating agents have been proposed, for example, a phosphate compound (Japanese Patent Publication No. 47-926).
0), silicon oxide (JP-B-47-13853), silica gel (JP-B-56-18141), particle size 100 μm
m or less of anhydrous silicon dioxide (JP-B-57-4666)
No.), barium sulfate (JP-A-59-22334), hydrotalcite (JP-B-62-31744), zeolite (JP-B-61-44092) and the like. However, since these heat insulating agents do not provide sufficient heat insulating properties or contain water of crystallization, the film is broken by a foaming phenomenon due to moisture during film formation, and the inner wall of the extruder is hard due to its high crystallinity and hardness. Or mold wear, poor dispersibility in polyolefin, or colored,
There is a problem that the film has low light transmittance and makes the film opaque, and further improvement has been desired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an agricultural film comprising an olefin resin, which has sufficiently improved the heat retaining property and has no various disadvantages such as the case where the conventional heat insulating agent is added. It is an object to provide a film and a method for producing the film.

[0004]

Means for Solving the Problems The inventors of the present invention carried out experiments by blending a large number of inorganic compounds with polyolefin, and found that agricultural films having various performances were excellent when a specific inorganic compound was blended. Obtained, and when a specific one is selected from among the polyolefins, and this is mixed with the above specific inorganic compound, and when the film has a specific configuration, an agricultural film with even better performance is obtained. And completed the present invention.

[0005] That is, the present invention provides an outer layer 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 10 to 15% by weight, and a density of 0.910 g / ml, melting point 116 ° C. or more, 1% modulus 1200 kg / cm ² or less, n-hexane extractables 10% by weight or less, melt index 0.
A laminated film comprising 100 parts by weight of an ultra-low-density ethylene-α-olefin copolymer having a weight of 8 to 10 g / 10 minutes and an intermediate layer composed of 1 to 20 parts by weight of anhydrous amorphous aluminosilicate, The thickness of the layer occupies 35 to 90% of the total thickness of the laminated film, and the total thickness of the laminated film is 50 to 200 μm. Furthermore, the present invention provides a melt index of 0.5 to 5 g / 10 min and a vinyl acetate content of 5
Both outer layers of an ethylene-vinyl acetate copolymer having a density of 0.910 g / ml or less and a melting point of 1 to 15% by weight.
100 parts by weight of an ultra-low-density ethylene-α-olefin copolymer having a temperature of 16 ° C. or more, a 1% modulus of 1200 kg / cm ² or less, an extractable amount of n-hexane of 10% by weight or less, and a melt index of 0.8 to 10 g / 10 minutes; The present invention relates to a method for producing a laminated film for agricultural use, comprising producing an intermediate layer comprising 1 to 20 parts by weight of anhydrous amorphous aluminosilicate by a co-extrusion method.

[0006]

In the present invention, the anhydrous amorphous aluminosilicate is an acid and heat-treated zeolite substantially having a zeolite particle state. The zeolite as the raw material is such that the zeolite structure is decomposed in the acid treatment, and is generally SiO ₂ / Al ₂
Zeolites having O ₃ (molar ratio) of about 5 or less are preferred. Examples of such zeolites include A-type zeolites and P zeolites.
Examples include type zeolite, X type zeolite, Y type zeolite, sodalite and analcyme, and A type zeolite is particularly preferable. The acid treatment of the zeolite is carried out by adding an acid or an acidic substance to the aqueous slurry of the raw material zeolite to adjust the pH of the slurry to a weak acidity of 4.5, preferably 5 to 7 even at a low pH. If the pH value of the zeolite slurry is less than 4.5, the particle state of the zeolite changes significantly, or the whole particles dissolve or disappear, and the skeleton of the raw material zeolite is destroyed. Is higher than 9, the degree of amorphization becomes insufficient. The acid-treated amorphous aluminosilicate is then treated at least above 200 ° C., preferably
It is substantially dehydrated in a temperature range of 50 to 500 ° C. to obtain anhydrous amorphous aluminosilicate. The average particle size of the anhydrous amorphous aluminosilicate is in the range of 0.5 to 5 μm, and the particle size in the range of 0.5 to 1.5 times the average particle size is 50% or more of the whole. It preferably has a particle size distribution, and the shape of the particles is preferably such that the particle surface is substantially spherical or rounded with no corners and smooth. The anhydrous amorphous aluminosilicate according to the present invention is clearly distinguished from the raw material zeolite by X-ray diffraction in terms of its physical properties. For example, the cation exchange ability peculiar to zeolite has substantially disappeared. In addition, although a normal dried product has moisture, it does not substantially condense as zeolite by dehydrating by heating. In the present invention, the term “amorphous” means that no diffraction line is observed from the X-ray diffraction pattern.
It refers to those including those in which the height of the diffraction line is reduced to half or less of zeolite and is substantially amorphous. The anhydrous amorphous aluminosilicate of the present invention has a refractive index of 1.35-1.
Since it is adjusted to 53, which is close to the refractive index of the olefin-based resin, it has good light transmittance and does not impair the transparency of the film. In the present invention, ultra-low density ethylene-
An agricultural film is produced by forming a resin composition in which 1 to 20 parts by weight of anhydrous amorphous aluminosilicate is mixed with 100 parts by weight of an α-olefin copolymer . If the amount of the anhydrous amorphous aluminosilicate is less than 1 part by weight, the heat retaining property is insufficient, and if it exceeds 20 parts by weight, the film-forming property is deteriorated, and the transparency, light transmittance, Undesirably, the mechanical strength decreases. In general, when a heat insulating agent is blended with a polyolefin-based resin, blending more than 15 parts by weight is undesirable because the mechanical strength of the film is reduced. Therefore, when 15 parts by weight or more of the heat insulating agent is blended, the above-mentioned ultra-low density ethylene-α-olefin copolymer is used as the olefin resin.

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 Plastic Company of the United States of America, to which the present inventors belong and to which the present applicant has a technical tie-up, and whose production method is disclosed in This is described in detail in JP-A-59-230011. The density of the VLDPE used in the present invention is 0.910 g / ml or less, and when it exceeds this, the crystallinity increases and the transparency of the film deteriorates, which is not desirable. Further, the melting point of VLDPE is 116 ° C. or higher, and if it is lower than this, the heat resistance is insufficient and the mechanical strength is also insufficient. The 1% modulus of VLDPE is 12
It is not more than 00 kg / cm ² , and if it exceeds this, the friction resistance is deteriorated. Furthermore, the extractable amount of n-hexane of VLDPE is 10% by weight or less, and if it exceeds this, the low molecular weight polymer bleeds on the film surface, and dust adheres to the film to inhibit light transmission, 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 10 g
If it exceeds / 10 minutes, the mechanical properties deteriorate, which is not desirable.
In the present invention, the ultra-low density ethylene-α-olefin copolymer is a continuous production method of the following ethylene copolymer:
Temperature of 10-80 ° C. and 7000 k in a fluidized bed reaction zone
(A) ethylene and at least one higher α having 3 to 8 carbon atoms at a pressure of not more than Pa at a molar ratio of (a) higher α-olefin: ethylene of 0.35: 1 to 8.0: 1.
A gas mixture containing an olefin and (b) at least 25 mol% of at least one diluent gas is formed by the following formula: Mg _m Ti (OR) _n X _p [ED] _q (where R is a carbon atom X represents an aliphatic or aromatic hydrocarbon group or a group COR ′ having 1 to 14 carbon atoms, R ′ represents an aliphatic or aromatic hydrocarbon group having 1 to 14 carbon atoms,
Is selected from the group consisting of chlorine, bromine, iodine and mixtures thereof, and ED is an organic selected from the group consisting of alkyl esters of aliphatic or aromatic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. 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 comprising the precursor composition represented by the formula (1), the precursor composition is diluted with an inert carrier material, and the following formula: Al (R ') _d X' _e H _f (Wherein 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, f is 0 or 1 and d
+ E + f = 3. ) Is completely activated with the organoaluminum compound represented by the formula (1), and the activated compound has a total aluminum: titanium molar ratio of 10:
It is preferably manufactured by using an amount of 1 to 400: 1.

The ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA) used in the present invention has a melt index of 0.5 to 5 g / 10 minutes,
If it is less than / 10 minutes, the extrusion properties are poor, while if it exceeds 5 g / 10 minutes, the mechanical properties deteriorate, which is not desirable. The vinyl acetate content is usually 10 to 15% by weight,
If the amount is less than 15% by weight, the transparency of the film deteriorates, and when the film is stretched as a tunnel house, the handling property of the film deteriorates, which is undesirable. If it exceeds 15% by weight, the mechanical strength of the film decreases, which is not desirable. .
In the present invention, when EVA is used in combination with VLDPE to form a laminated film, the vinyl acetate content of EVA is 5%.
１５15% by weight. This is because the laminated film has flexibility even when the vinyl acetate content is less than 10% by weight. Further, the relationship between the melting point (MP, unit ° C) and the vinyl acetate content (VA, unit weight%) of EVA used in the present invention is represented by the following formula: MP = 114-1.44VA, and the molecular weight distribution (M _w / M _n ) of less than 4 is particularly desirable, and those in this numerical range have the same vinyl acetate content and a melting point of 2 to 2 compared to EVA outside the above range.
5 ° C higher, excellent in heat resistance and mechanical strength.

The agricultural film of the present invention can be produced by a co-extrusion molding machine using each of the resin compositions to be the intermediate layer and both outer layers. In this case, for example, an inflation method using a circular die and a T A die method or the like can be applied. The reason why a three-layer structure including an intermediate layer and both outer layers when VLDPE is used in combination in the present invention is described below. First, even if VLDPE alone is used 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 has severe blocking and is difficult to handle. Met. The present inventors have found that if VLDPE is used as an intermediate layer and a resin layer is co-extruded on both sides of the intermediate layer, it is possible to form a VLDPE film that is difficult to form alone.
This was adopted for the middle layer. Next, the reason why specific EVA was adopted as both outer layers of the VLDPE intermediate layer is that EVA is superior in transparency as compared with high-pressure low-density polyethylene or the like. However, in the case of EVA, vinyl acetate (V
A) Although the transparency and cold resistance increase as the content increases,
Since the blocking properties and the mechanical properties are deteriorated, the above numerical ranges are set.

The film of the present invention has a thickness of 50 to 200.
If the thickness is less than 50 μm, the mechanical strength is insufficient, and the handling of the film becomes difficult. If the thickness exceeds 200 μm, the quality becomes excessive, and the economical efficiency is poor and undesirable. Further, the ratio of the intermediate layer to the whole film, that is, the ratio of the thickness is 35 to 90%, and if it is less than 35%, transparency, mechanical properties, cold resistance, friction resistance, economy, etc. are deteriorated. , 90%, coextrusion becomes impossible. The thickness of each outer layer may be the same or different.

[0012]

Next, the present invention will be described in more detail with reference to examples. Synthesis Example (Preparation of anhydrous amorphous aluminosilicate) Na-A type zeolite (Nihon Kagaku) was placed in a 500 ml beaker .
"Zeostar MA-100" manufactured by Gaku Kogyo Co., Ltd.
P ") 50 g was weighed, and 200 g of water was added to prepare a slurry having a zeolite concentration of 20%. The pH of this slurry was 11.7. While stirring the slurry,
250 g of 4% sulfuric acid was gradually added over about 5 minutes, and the mixture was further stirred for 1 hour after completion of the addition (during this, the pH of the slurry was
Was always kept at 4 or more), and then filtered by a usual method.
Washing, drying and pulverization were performed to obtain an acid-treated product of Na-A type zeolite. X-ray diffraction (XRD) of this acid-treated product
As a result of analysis, no diffraction peak was observed, and it was confirmed that the substance was amorphous aluminosilicate. Next, this acid-treated product was heat-treated at a temperature of about 300 ° C. for 2 hours, dehydrated, and pulverized to obtain anhydrous amorphous aluminosilicate. This average particle size is 2.9 μm, and the average particle size is 0.1 μm.
The particle size distribution is 82.0% in the range of 5 to 1.5 times, the Ca ion exchange capacity is 28.4 mg CaO / g, the equilibrium pH is 8.5, the refractive index is 1.39, and the composition is Na ₂ O 9.4.
%, Al ₂ O ₃ 43.8%, SiO ₂ 45.0%, H ₂
O was 1.8%. The raw material Na-A type zeolite has an average particle size of 2.8 μm and an average particle size of 0.5 μm.
1.5 times the range of a particle size distribution that exists 87.0%, Ca ion exchange capacity 124.0mgCaO / g, the equilibrium pH 11.2, a refractive index of 1.46, the composition _Na 2 O1
6.3%, Al ₂ O ₃ 27.8%, SiO ₂ 33.6
% And H ₂ O 22.4%.

Embodiment 1(Reference example)  Melt index (MI) 2 g / 10 min, density 0.9
100 g by weight of 20 g / ml high-pressure low-density polyethylene
Anhydrous amorphous aluminosilicate prepared in the above synthesis example
Formulated after treating 7 parts by weight of sodium stearate
And a 50μm thick film by inflation molding
I got Visible light (wavelength 0.4-
0.7 μm) has a transmittance of 75% and infrared rays (wavelength 5 to 50).
μm) is 15%, and transparency and heat retention
It was shown that there is. As for the heat retention,
Agricultural tunnels are built in the
When the outside air temperature was measured, it was 4.3 ° C and-
It was 1.8 ° C., and it was confirmed that the film had sufficient heat retention.

Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that zeolite as a raw material was used in place of the anhydrous amorphous aluminosilicate used in Example 1, and a film was produced by the inflation method. could not. This is because the film of the zeolite foams due to the moisture, and air is blown out of the film to break the film.

Embodiment 2(Reference example)  MI 3g / 10min, vinyl acetate content 13% by weight
Prepared by synthesis example in 100 parts by weight of lene-vinyl acetate copolymer
15 parts by weight of anhydrous amorphous aluminosilicate
After treatment with sodium phosphate, mix and calender
A 100 μm thick film was obtained. Of the resulting film
The transmittance of visible light (wavelength 0.4 to 0.7 μm) is 63.
%, And the transmittance of infrared rays (wavelength 5 to 50 μm) is 8%.
Although the transparency is slightly inferior to the film of Example 1,
Sufficient, indicating that the heat retention was very good.
In terms of heat retention, the above film also
And measured the inside temperature and outside temperature of the tunnel.
Excellent at 5.4 ° C and -1.8 ° C, respectively.
It was confirmed that it had heat retention. Also this film
Is as flexible as polyvinyl chloride,
The workability of film expansion is very good, and the effect of labor saving is also recognized.
Was.

Comparative Example 2 An experiment was conducted in the same manner as in Example 2 except that zeolite as a raw material was used in place of the anhydrous amorphous aluminosilicate used in Example 2, and a foaming phenomenon occurred on the film surface. The surface was rough, the light transmittance was poor, and the film was damaged in a short time due to friction with the metal support.

Example 3 An ethylene-vinyl acetate copolymer having a MI of 2 g / 10 min and a vinyl acetate content of 10% by weight was used as a raw material for both outer layers, and had a density of 0.903 g / ml and a melting point of 117 ° C.
% Modulus 950 kg / cm ² , n-hexane extractables 2.8 wt%, MI ² g / 10 min, ethylene-hexene-1 copolymer (United States Union Carbide
Traders made by Chemical and Plastic Company
Product name "DEFD-9078") 100 parts by weight of a resin composition containing 10 parts by weight of anhydrous amorphous aluminosilicate prepared in the synthesis example (treated with sodium stearate) was used as a raw material for an intermediate layer, and was subjected to a die-blowing method. At a temperature of 210 ° C., a laminated film having a total thickness of 100 μm, in which the thickness of the intermediate layer was 80 μm and the thickness of both outer layers was 10 μm, was manufactured. The tensile strength of the obtained film was 7 in the machine direction.
The weight was 5 kg / cm and the lateral direction was 93 kg / cm, and the practicality was sufficient. The haze (JIS K-6714) was 6.2, and the transparency was high. Heat resistance is outside temperature 80
℃ (temperature at which the film near the steel frame of the agricultural house in the summer is exposed), the tensile strength was measured and determined.
38 kg / cm ² , and the practicality was sufficient. Furthermore, when making an agricultural house from this film and measuring the internal temperature and the outside temperature of the house to evaluate the heat retention, the temperature was 5.2 ° C. and −1.8 ° C., respectively, indicating that the film had excellent heat retention. confirmed.

Comparative Example 3 The same experiment as in Example 3 was carried out except that zeolite as a raw material was used in place of the anhydrous amorphous aluminosilicate used in Example 3, and a foaming phenomenon occurred in the intermediate layer. Poor light transmission caused the growth of plants in agricultural houses made from this film to be inhibited.

[0019]

As described in detail above, the agricultural film of the present invention has high light transmittance and infrared absorption by using anhydrous amorphous aluminosilicate as a heat insulator. Heightened. For this reason, the agricultural film of the present invention is excellent in heat retention, enhances the growth of crops, and contributes to energy saving. Furthermore, ultra-low density ethylene-α- blended with anhydrous amorphous aluminosilicate
The film of the present invention in which both outer layers made of a specific ethylene-vinyl acetate copolymer are laminated on an intermediate layer made of an olefin copolymer, has heat retention, transparency, heat resistance, impact resistance,
It is excellent in tear resistance, piercing resistance, cold resistance and the like, and is suitable as an agricultural film for house cultivation, tunnel cultivation and mulch cultivation. In the present invention, since the anhydrous amorphous aluminosilicate is used, a foaming phenomenon does not occur unlike the case of using another inorganic heat retaining agent, and a film having excellent performance is produced. In particular, in the case of a resin having a high melting point (polypropylene, HDPE, LLDPE, etc.), the film must be formed at a high temperature.
Although it is easy to foam, when the anhydrous amorphous aluminosilicate of the present invention is used, it does not foam even at a high temperature and does not adversely affect the film. Furthermore, a high concentration of anhydrous amorphous aluminosilicate as an insulating agent (olefin resin 1
(15 parts by weight or more with respect to 00 parts by weight), the use of the heat insulating agent together with the ultra-low-density ethylene-α-olefin copolymer can prevent a decrease in the mechanical strength of the film.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 5/18 C08L 23/00-23/36

Claims (3)

(57) [Claims] 1. Melt index 0.5 to 5 g / 10
Ethylene acetate having a vinyl acetate content of 5 to 15% by weight.
Both outer layers made of a vinyl acetate copolymer and a density of 0.91
0 g / ml or less, melting point 116 ° C. or more, 1% modulus 1
Ultra-low-density ethylene-α-olefin copolymer 100 with 200 kg / cm ² or less, n-hexane extractables 10% by weight or less, melt index 0.8 to 10 g / 10 minutes
Parts by weight and an intermediate layer comprising 1 to 20 parts by weight of anhydrous amorphous aluminosilicate, wherein the thickness of the intermediate layer is 35 to 30% of the total thickness of the laminated film.
90%, and the total thickness of the laminated film is 50-200.
A laminated film for agricultural use characterized by having a thickness of μm. 2. An ultra-low density ethylene-α-olefin copolymer
Method for continuous production of an ethylene copolymer having the following coalescence: temperature of 10 to 80 ° C. and 7000 k in a fluidized bed reaction zone.
At a pressure of Pa or less, (a) higher α-olefin:
Ethylene having a molar ratio of lene of 0.35: 1 to 8.0: 1.
And at least one higher α having 3 to 8 carbon atoms
-An olefin and (b) at least one dilution of at least 25 mol%
A gas mixture containing a gas is represented by the following formula: Mg_mTi (OR)_nX_p[ED]_q  (Wherein, R is an aliphatic or aromatic hydrocarbon having 1 to 14 carbon atoms)
R ′ represents a hydrogen atom or a group COR ′, wherein R ′ has 1 to 1 carbon atoms.
X represents an aliphatic or aromatic hydrocarbon group, X represents a chlorine atom, a bromine atom, an iodine atom and a mixture thereof
Wherein ED is an alkyl ester of an aliphatic or aromatic acid,
Consisting of aliphatic ethers, cyclic ethers and aliphatic ketones
Represents an organic electron donating compound selected from the group, m is 0.5 to 56, n is 0, 1 or 2, p is 2 to 116, and q is 2 to 85. ) From the precursor composition represented by
The precursor composition is brought into continuous contact with particles of the catalyst system
With an inert carrier material and the following formula: Al (R ')_dX '_eH_f  (Wherein X ′ represents a chlorine atom or a group OR ″, and R ′ and R ″ are a saturated hydrocarbon group having 1 to 14 carbon atoms.
E is 0 to 1.5, f is 0 or 1, and d + e + f = 3. ) Completely activated by the organoaluminum compound represented by
All the aluminum in the reaction zone
The molar ratio of titanium: titanium is 10: 1 to 400: 1
Used in such amounts, manufactured byClaim 1Agricultural laminate as described
the film. 3. Melt index 0.5 to 5 g / 10
Ethylene acetate having a vinyl acetate content of 5 to 15% by weight.
Both outer layers made of a vinyl acetate copolymer and a density of 0.91
0 g / ml or less, melting point 116 ° C. or more, 1% modulus 1
Ultra-low-density ethylene-α-olefin copolymer 100 with 200 kg / cm ² or less, n-hexane extractables 10% by weight or less, melt index 0.8 to 10 g / 10 minutes
A method for producing a laminated film for agriculture, comprising producing, by co-extrusion, an intermediate layer comprising 1 part by weight and 1 to 20 parts by weight of an anhydrous amorphous aluminosilicate.