JPH0633344B2 - Agricultural dressing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a UV-shielding agricultural coating material, and more specifically, to the UV-shielding ability, that is, the continuous retention, weather resistance, tear resistance retention, impact resistance, waist strength, It is excellent in various properties such as dust resistance, and has no whitening phenomenon such as blowout and crystallization of the UV absorber. It is mainly composed of linear rhodesity polyethylene. The present invention relates to an agricultural coating material composed of a resin film in which transmission of ultraviolet rays is substantially blocked.

2. Description of the Related Art Forcing or semi-forcing cultivation of various agricultural products in a house or a tunnel in which a synthetic resin film or a board is spread has been actively performed. At this time, polyvinyl chloride and polyethylene are mainly used as materials for synthetic resin films and boards (generally collectively referred to as "agricultural covering materials") spread in houses and tunnels.

On the other hand, various studies have been conducted on the relationship between the cultivation environment of crops and light quality, and the relationship between the cultivation environment of crops and ultraviolet rays has also been studied. Blight fungus and sesame leaf blight fungus; Eggplant, tomato, cucumber, strawberry, watermelon, melon, pepper, lettuce, Chinese cabbage, carrots, burdock, radish, sclerotium fungus, botrytis, anthracnose, vine There is a close relationship between the reproduction of molds such as bacterial blight, black mold, and spot fungus, and the wavelength of ultraviolet rays.
It has been reported that the growth of such molds is prevented under the complete shielding condition of ultraviolet rays having a wavelength of ˜380 nm or less.

The Applicant pays particular attention to the cultivation environment of crops and the influence of ultraviolet rays, and blends a certain specific benzotriazole-based ultraviolet absorber as an agricultural coating material for the reproduction and control of molds of plant diseases as described above. A vinyl chloride resin film capable of substantially completely blocking transmission of ultraviolet rays having a wavelength of 380 nm or less has been developed and proposed (Japanese Patent Publication No. 53-47).
No. 383).

The applicant of the present application, while further researching the cultivation environment of crops and the effects of ultraviolet rays, ultraviolet rays not only affect the reproduction of plant disease molds, but also the growth of crops,
It has been found that the quality of harvested crops is also greatly affected, and an agricultural film that substantially blocks transmission of ultraviolet rays having a wavelength of 370 nm or less is cultivated in a facility under the coating of such an agricultural film. To prevent fruit cracking of tomatoes, stand-up cultivation of chive and chives, speed up the heading of lettuce or Chinese cabbage and increase the heading rate, increase sugar content of fruits, prevent aging of peppers, etc. Proposed finding (Japanese Patent Publication No. 55-12208,
JP-B-55-10203, JP-B-56-4637
5, JP-B-57-59725, JP-A-53.
-127126 gazette etc.).

By the way, in order to obtain such an ultraviolet-shielding agricultural film, it is necessary to blend a considerably large amount of an ultraviolet absorber into the film, and in the case of polyethylene which is often used along with polyvinyl chloride as an agricultural film material, The amount of the UV absorber can be blended to obtain a practical UV-shielding film to some extent, but the UV absorber may be blown onto the film surface during the severe cold season of winter or the high temperature of summer, It was found that a so-called whitening phenomenon sometimes occurs, in which the ultraviolet absorber crystallizes in the film and the film becomes cloudy.

In particular, in the case of a thin polyethylene film, this whitening phenomenon is remarkable because of the addition of a larger amount of an ultraviolet absorber than that of a thick one in order to obtain a sufficient ultraviolet shielding property, the deterioration of the ultraviolet shielding ability and the weather resistance. Deterioration of lightness, decrease of light transmittance,
Problems such as deterioration of dust resistance are likely to occur.

In order to develop an ultraviolet shielding agricultural coating material that does not cause such a problem, the present inventors have conducted research from both the film material and the ultraviolet absorber, and as a result, the linear rodentity Polyethylene and ethylene
By using a mixture with a vinyl acetate copolymer and blending it with a benzotriazole-based UV absorber, 37
An agricultural coating material that highly shields ultraviolet rays having a wavelength of 0 nm or less and does not bleach even under severe weather conditions in winter or summer and can maintain its high ultraviolet shielding ability for a long period of time is obtained. The present invention has been completed and the present invention has been completed.

Thus, according to the present invention, the linear rodency
Polyethylene 80-95 parts by weight and vinyl acetate content 5-
40% by weight of a mixture of 20 to 5 parts by weight of ethylene-vinyl acetate copolymer, wherein the mixture comprises a resin composition having a vinyl acetate content of 0.5 to 5% by weight, and a benzotriazole-based ultraviolet ray. Absorbent-containing thickness is 45 ~
Provided is an agricultural coating material which is made of a resin film of 105 microns and is substantially impermeable to ultraviolet light having a wavelength of at least 370 nm or less.

Linear Low Density Polyethy-lene-hereinafter referred to as L-L, which is used as the base of the resin film constituting the above-mentioned agricultural coating material.
DPE may be abbreviated as DPE), which was recently developed as an improved form of low-density polyethylene and contains ethylene and a small amount of, for example, 1-butene, 1-hexene, 1-octene, 4-methyl-1-. _C 3 _{-C 10} of pentene α-
A substantially linear copolymer prepared by copolymerization with at least one olefin, wherein the C ₃ -C ₁₀ α-olefin-based alkyl side chain is present at the polymer chain. Therefore, it has excellent physical properties such as tear strength, impact resistance, and waist strength as compared with conventional low-density polyethylene, and has recently begun to be used in the field of agricultural coating materials.

Which type of L-LDPE for the film of the present invention
However, the density is generally 0.890 to 0.940 g / cm ³ , preferably 0. 0, from the viewpoints of ease of processing into a thin film, continuous retention of the ultraviolet absorber, and the like. Suitable values are in the range of 910 to 0.935 g / cm ³ and the melt index is in the range of 0.1 to 20 g / min, preferably 0.3 to 15 g / min. Further, L-L which is preferably used in the present invention
DPE has a content of α-olefin in the copolymer is generally 3 to 3 based on the total amount of ethylene and α-olefin.
It is in the range of 25% by weight, preferably 5 to 15% by weight, and the one in which 1-butene and / or 4-methyl-1-pentene and the like are copolymerized as α-olefin is particularly preferable. .

In the present specification, the density and melt index of L-LDPE refer to JIS K-7112 (method for measuring density) and JIS K-7210 (melt index) used in JIS K-6760 (polyethylene test method). It is the value measured according to the method of measuring lux).

The above L-LDPE may be used alone or in combination of two or more.

According to the present invention, the above L-LDPE is used as a mixture with an ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA). The ethylene-vinyl acetate copolymer which can be used has a vinyl acetate content of 5 to 40% by weight, preferably 5 to 20% by weight, more preferably 5 to 15% by weight. The EVA is generally 0.89 to 0.98 g / cm ³ , and preferably 0.91 to 0.98 g / cm ³ .
It has a density in the range of 0.95 g / cm ³ and a melt index of generally 0.1 to 20 g / min, preferably 0.3.
Those in the range of -15 g / min are advantageously used.

EVA is mixed with L-LDPE in a range that does not significantly deteriorate the above-mentioned preferable properties of L-LDPE, and the mixing ratio is L-LPEE: 80 to 95 parts by weight, preferably 85 to 9 parts.
5 parts by weight, more preferably 90 to 95 parts by weight, and EVA: 20 to 5 parts by weight, preferably 15 to 5 parts by weight,
More preferably, it can be 10 to 5 parts by weight. When the mixing ratio of EVA exceeds 20 parts by weight, the anti-blocking property of the film is deteriorated,
Furthermore, the dustproofness of the film tends to be poor when it is stretched outdoors. On the other hand, if the mixing ratio of EVA is less than 5 parts by weight, the persistence of UV shielding tends to be reduced.

Further, EVA has a vinyl acetate content of 0.5 to 5% by weight in the mixture within the above mixing ratio range.
It is necessary to select the kind and / or mixing ratio so that it is preferably in the range of 0.5 to 4% by weight, more preferably 1 to 3% by weight. If the vinyl acetate content of the mixture of L-LDPE and EVA is lower than 0.5% by weight, the durability of the UV shielding may be deteriorated, and if the vinyl acetate content exceeds 5% by weight, the film of Blocking resistance and film dust resistance during outdoor expansion tend to be reduced.

According to the present invention, a benzotriazole-based ultraviolet absorber is added to the resin composition made of the mixture of L-LDPE and EVA described above. As the benzotriazole-based ultraviolet absorber that can be blended, one or two or more selected from the following examples in consideration of the ultraviolet absorbing ability of the ultraviolet absorber and the compatibility with the resin composition. It can be appropriately selected and used: Hydroquinone-based UV absorber: Hydroquinone, hydroquinone disalicylate Salicylate-based UV absorber: Phenyl salicylate, Para-octyl phenyl salicylate Benzophenone-based UV absorber: 2-hydroxy -4-
Methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy -4
4'-dimethoxybenzophenone, 2-hydroxy-4
-Benzoyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,
2 ', 4,4'-tetrahydroxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxy-5-
Sodium sulfobenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-5
-Chlorobenzophenone Benzotriazole type UV absorber: 2- (2'-hydroxy-5'-methylphenyl) -5-butoxycarbonylbenzotriazole, 2- (2'-hydroxy-)
5'-methylphenyl) -5,6-dichlorobenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) -5-ethylsulfobenzotriazole, 2-
(2'-hydroxy-5'-tert-butylphenyl)-
5-chlorobenzotriazole, 2- (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-amylphenyl)
Benzotriazole, 2- (2'-hydroxy-3 ',
5'-dimethylphenyl) benzotriazole, 2-
(2'-hydroxy-3 ', 5'-dimethylphenyl)
-5-methoxybenzotriazole, 2- (2'-methyl-4'-hydroxyphenyl) benzotriazole,
2- (2'-stearyloxy-3 ', 5'-dimethylphenyl) -5-methylbenzotriazole, 2-
(2'-hydroxy-5'-ethoxycarbonylphenyl) benzotriazole, 2- (2'-hydroxy-
3'-methyl-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methoxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-phenylphenyl) -5-chloro Benzotriazole, 2- (2'-hydroxy-5'-cyclohexylphenyl) benzotriazole, 2- (2'-hydroxy-4 ', 5'-dimethylphenyl) -5-butoxycarbonylbenzotriazole, 2- ( 2'-hydroxy-3 ', 5'-dichlorophenyl) benzotriazole, 2- (2'-hydroxy-4', 5'-dichlorophenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-dimethyl Phenyl) -5-ethylsulfobenzotriazole, 2- (2'-hydroxy-5 '
-Phenylphenyl) benzotriazole, 2- (2 '
-Hydroxy-4'-octoxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-methoxyphenyl) -5-methylbenzotriazole, 2- (2 '
-Hydroxy-5'-methylphenyl) -5-ethoxycarbonylbenzotriazole, 2- (2'-acetoxy-5'-methylphenyl) benzotriazole.

Of these UV absorbers, the preferred UV absorber is of the formula [Wherein R ₁ and R ₂ are the same or different and each represents a hydrogen atom, a lower alkyl group, particularly a branched lower alkyl group, or an aryl group, especially a phenyl group, and X represents a hydrogen atom or a halogen atom. , Especially a chlorine atom].

A particularly preferred UV absorber is of the formula Or Is represented by.

When the above-mentioned suitable UV absorbers are mixed and used, the relative proportions of the UV absorbers (I) and (II) are varied over a wide range according to the thickness of the film and the degree of UV shielding. However, in general, it is convenient that the total amount of the ultraviolet absorbers (I) and (II) is within the following range based on the total amount.

Relative ratio (wt%) UV absorber General range Suitable range (I) 30-70 35-65 (II) 70-30 65-35 The UV absorber as described above is blended with the UV absorber. The film formed from the resin composition is blended in an amount such that it does not substantially transmit ultraviolet rays having a wavelength of at least 370 nm or less, preferably 380 nm or less. Here, "substantially not transmitting ultraviolet rays having a wavelength of x nm or less" means not only completely transmitting ultraviolet rays having a wavelength of x nm or less (transmittance 0%), but also ultraviolet rays having a wavelength of x nm or less. If the transmittance is 5% or less, preferably 2% or less, it means that some transmission of ultraviolet rays having the wavelength is allowed.

The amount of the above-mentioned UV absorber to achieve such UV-shielding properties cannot be unconditionally determined because it is related to the UV-absorption properties of the individual UV absorbers used, the thickness of the film, etc. As a measure of the amount, the amount of the ultraviolet absorber blended (A) [the amount blended per 100 parts by weight of the mixture with L-LDPE (parts by weight)] and the film thickness (B)
The product (AB) with [unit: micron] is generally 20 to 15
0, preferably 30 to 140, more preferably 35 to 1
It is suitable to fall within the range of 30. Also,
If the blending amount of the ultraviolet absorber becomes too large, it may cause blowout, so the upper limit of the blending amount of the ultraviolet absorber is L-.
Generally 3 per 100 parts by weight of a mixture of LDPE and EVA.
It is desirable that the amount is not more than 2 parts by weight, preferably 2 parts by weight or less.

A more specific blending amount can be easily determined by those skilled in the art by experimentally preparing a film for each ultraviolet absorber and measuring its light transmission characteristics.

The resin film provided by the present invention may be colorless and transparent, may be colored, and may be embossed. When it is colored, its color tone is preferably blue or purple. Such a colored film can be usually obtained by adding a colorant (dye or pigment) to the film of the present invention in addition to the above-mentioned ultraviolet absorber.

Examples of colorants that can be used in the production of the colored film include green pigments such as copper phthalocyanine green, Guinea green, and chrome oxide green; white pigments such as titanium oxide and lead white; iron black, carbon black,
Black pigments such as aniline black; blue pigments such as ultramarine blue, navy blue, cobalt blue, copper phthalocyanine blue, phthalocyanine blue, and fast sky blue; orange pigments such as cadmium orange, chrome vermillion, chrome orange, and benzidine orange; cadmium yellow, chrome yellow , Yellow pigments such as strontium yellow, titanium yellow, yellow ocher, yellow iron oxide, tartrazine yellow, benzidine yellow, hansa yellow, and yellow.
Purple pigments such as cobalt violet, mineral violet and dioxazine violet; cadmium red,
Rouge, Permanent Violet F5R, Brilliant Carmine 6B, Brilliant Carmine 3B, Rakelet C, Pyrazolone Red, Cincacia Red, Bold-
Red pigments such as 10B, bonmarcillite, rhodamine lake B, and naphthol red; and the like.

These colorants are preferably blended in such an amount that the average transmittance of light rays in the visible light region of the resulting colored film falls within the range of 60% or more, preferably 70% or more, more preferably 80%. Is. Here, the "visible light region" refers to a light ray region within the wavelength range of 400 nm to 800 nm that is perceived by the human eye, and the film of the present invention may be any type of uncolored, colored or embossed. In particular, the average transmittance of light in the visible light region of 420 nm or more of 60
Conveniently, it is in the range of not less than%, more preferably not less than 70%.

The "transmittance" and "average transmittance" used for light rays in the ultraviolet and visible light ranges herein are based on the total transmittance, and the total transmittance can be represented by the following formula.

Further, the film of the present invention may further contain other additives such as a lubricant, an antioxidant, an antistatic agent, a heat stabilizer and a flame retardant, if necessary. As a lubricant,
Examples thereof include ethylene bis-stearyl amide, butyl stearate paraffin wax, low molecular weight polyethylene, montanic acid wax, stearic acid and stearyl alcohol. Examples of the antioxidant include 2,6
-Di-tert-butyl-4-methylphenol, 2,4
6-tri-tert-butylphenol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol),
4,4′-thiobis- (3-methyl-6-tert-butylphenol), phenyl α-naphthylamine and the like can be mentioned.

Further, as the antistatic agent, for example, polyoxylethylenealkylamide, alkylolamide, ethanolamide, alkylphosphate, alkylsulfate, etc. can be used, and as the heat stabilizer, for example, dibutyltinmalate, dibutyltinlaurate can be used. Rate, calcium stearate, zinc ricinoleate, triphenyl phosphite and the like are suitable.

In addition, a flame retardant such as antimony oxide, aluminum hydroxide, or a halogen-containing phosphoric acid ester may be appropriately mixed.

The film of the present invention can be produced from the above-mentioned film components by a film forming method known per se, for example, by melting T-film.
It can be easily processed by a die extrusion method, an inflation extrusion method, a solution casting method, a calender method, or the like.

The film of the present invention is 45 to 105 as a covering material for agriculture.
Suitably it has a thickness of micron, preferably in the range of 50-100 micron. The suitable range of the thickness of the film of the present invention varies depending on the situation where it is used as a covering material for agriculture, but for example, for a tunnel house with a width of 1.5 to 3 m and a height of 0.5 to 1.0 m. Is preferably 45-80 microns, particularly preferably 50-75.
Micron: For a small house having a width of 3 to 5 m and a height of 1.0 to 1.5 m (generally referred to as Vietcon house, Roushaus, etc.), preferably 70 to 105 microns, particularly preferably 75. -100 micron; preferably 45-80 micron for lining a large house,
Particularly preferably, it is in the range of 50 to 75 .mu .; in the case of rain shelter cultivation such as fruit trees, the range is preferably 70 to 105 .mu.m, particularly preferably 75 to 100 .mu.m.

The ultraviolet-shielding agricultural coating material of the present invention described above is extremely excellent in weather resistance, maintains its advanced ultraviolet-shielding ability for a long period of time under outdoor exposure, and exhibits a whitening phenomenon even under severe weather conditions. It does not occur and has excellent physical properties such as impact resistance, dust resistance, tear strength, and waist strength, and is extremely useful in facility cultivation of agricultural products.

Next, the present invention will be described more specifically by way of examples.

Example 1 Commercially available L-LDPE [Showa Denko KK, grade 22]
0FS, melt index 2.0 g / min, density 0.9
22 g / cm ³ ] 90 parts by weight and EVA [Showa Denko KK
Made, grade BM-05-6 melt index 0.5
g / min, density 0.927 g / cm ³ , vinyl acetate content 5w
t%] 10 parts by weight, 2- (2'- as an ultraviolet absorber
Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole [Tinuvin 326, manufactured by Nippon Ciba-Geigy Co., Ltd.] 0.8 part by weight and 2-
0.5 parts by weight of (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole (Tinuvin 327, manufactured by Nippon Ciba-Geigy Co., Ltd.) were mixed, and the resulting mixture was added to T-. Cylinder temperature C _{1 to} C ₃ 190 to 220 ° C., die temperature D _{1 to} D _{3 with a} die extruder.
The film was melt-kneaded and extruded at 200 ° C. to obtain a film having a thickness of 50 μm. The characteristics of this film were tested by the evaluation methods described below. The test results are shown in Table 1 below.

Examples 2 to 10 and Comparative Examples 1 to 6 In exactly the same manner as in Example 1, the resins and ultraviolet absorbers shown in Table 1 below were mixed in a predetermined amount, and a thickness of 5 was obtained using a T-die extruder.
Films of 0 to 100 μ were prepared. The characteristics of these films were measured in the same manner as in Example 1, and the results are also shown in Table 1.

The EVAs used in this example and comparative examples are as follows: [Evaluation method] (1) Ultraviolet shielding property The light transmittance (total transmission) of the film at 370 nm is measured by a spectrophotometer [UV-365, manufactured by Shimadzu Corporation].

(2) UV Shielding-Persistence Test A film sample is subjected to a weather resistance test with a spray cycle 18 minutes / 120 minutes using a Sunshine Weathermeter (WOM) manufactured by Suga Test Instruments Mfg. Co., Ltd. 150 and 30
After 0 hours, the film was taken out, and the film was taken out with a spectrophotometer [UV-365, manufactured by Shimadzu Corporation].
The light transmittance at 0 nm (total transmission) is measured.

(3) W-O-M Whitening Acceleration Test A film sample is subjected to a weather resistance test with a Sunshear Weatherometer (W-O-M) manufactured by Suga Test Instruments Co., Ltd. with a spray cycle of 18 minutes / 120 minutes.

The whitening state of the film after W-O-M 300 hours is visually observed and evaluated according to the following criteria.

A: Almost no whitening B: Whitening C: Whitening is extremely large (4) Whitening test (acceleration test at 50 ° C) The film sample was hung in a constant temperature and humidity tank adjusted to a temperature of 50 ° C and a relative humidity of 50% for 2 weeks. After that, the surface blowout state is observed.

The whitening is judged by taking out the film and visually observing the appearance, and the judgment when the ultraviolet absorbent blows out white on the surface and is crystallized is C, and when there is no change compared with the time of production, it is A.

(5) Blocking resistance test 30mm × on a glass test tube (15mmφ × 150mm)
A 300 mm test film is wound with a load of 750 g applied to one end thereof.

Put the roll in a beaker, put the beaker in a desiccator with water on the bottom, and keep it in an electric incubator at 50 ° C for 1 week at a humidity of 100%, and then remove it. Dry in an electric incubator and cool to room temperature. A cellophane tape is attached to the end of the roll, and a weight is attached to this cellophane tape. Gently rotate the test tube in the direction in which the film is rewound, and if unwinding does not occur with this weight load, replace it with a heavier weight and repeat the test to load the film when unwinding begins. Measure (g / 30 mm). The smaller the load at the start of rewinding, the better the blocking resistance.

(6) Dust-proof acceleration test A 60 mm x 60 mm test film is attached to a glass plate, and this glass plate is an electric incubator at 50 ° C (Kiya Seisakusho, Model A
-2), and after drying, cool to room temperature. Then, about 35 g / m ² of talc (Wako Pure Chemicals Reagent-grade) is sprinkled on the surface of the test film. This is placed in an electric incubator at 50 ° C. for 3 days, then taken out and cooled to room temperature. Then, the glass plate is tilted at about 30 °, and water is sprinkled with a diloro from a height of about 30 cm at 20 l / m ² for about 1 minute. Thereafter, the film is placed in an electric incubator at 50 ° C. for about 1 hour to dry the film surface and then cooled to room temperature.

Then, the film is cut into a size of 20 mm × 40 mm, the diffuse transmittance and the total transmittance are measured with an integrating sphere turbidimeter (manufactured by Nippon Seimitsu Optical Co., Ltd., model SEP-T), and the haze (turbidity) is calculated by the following formula. .

The smaller the haze value, the better the antifogging and dustproof property.

Claims (1)

[Claims] 1. A linear rhodecity polyethylene 8
A mixture of 0 to 95 parts by weight and 20 to 5 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 to 40% by weight, wherein the vinyl acetate content of the mixture is 0.5 to 5% by weight. A resin film having a thickness of 45 to 105 microns and containing a benzotriazole-based UV absorber, and having a thickness of at least 370 nm.
An agricultural coating material, which is substantially impermeable to ultraviolet rays having the following wavelengths.