JP2007000043A - Agricultural film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agricultural film excellent in heat-retaining property and weed control property, keeping the temperature of soil covered with the agricultural film high at night, and inhibiting photosynthesis of weeds to prevent the weeds from growing thickly so that time and labor required for weeding are saved to improve the efficiency in agricultural work while promoting the growth of desired farm crops. <P>SOLUTION: The agricultural film comprises 100 pts.wt. of thermoplastic resin, 1-10 pts.wt. of porous zeolite, and organic pigment; wherein light transmittance is ≤40% in any wavelength in a wavelength range of 400-700 nm, and ≥60% in any wavelength in a wavelength range of 710-2,600 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an agricultural film excellent in heat retention and weed control, and more particularly to an agricultural film that is suitably used from the beginning of autumn to early spring for the purpose of maintaining soil temperature at night and controlling weeds.

  In general, the heat retention of agricultural film is a characteristic that prevents the temperature of soil covered with the agricultural film from decreasing at night. Specifically, the soil covered with the agricultural film is While it absorbs heat energy from the sun, etc., it dissipates the absorbed heat energy to the outside at night, but it is a characteristic that prevents this dissipated heat energy from being dissipated outside the agricultural film.

  Transparent agricultural film transmits large amounts of thermal energy from the sun during the day, greatly increasing the temperature of the soil covered by the agricultural film, but the thermal energy dissipated by the soil at night. The temperature of the soil that has been permeated in large amounts and covered with a transparent agricultural film is drastically lowered at night.

  On the other hand, the black agricultural film blocks sunlight and blocks light with a wavelength of 710 nm or more, which is effective for raising the temperature of the soil. Soil that is not done and covered with black agricultural film does not rise that much during the day.

  Therefore, the superiority or inferiority of the heat retention of agricultural films is determined by the degree of thermal energy transmission and the retention of thermal energy released from the soil. There is a demand for an agricultural film capable of appropriately increasing the temperature of the soil covered with the film for use while maintaining the thermal energy dissipated by the soil at night.

  On the other hand, the inside covered with the film for agriculture has a problem that weeds are easy to propagate in addition to the plants to be cultivated and weeding is difficult. Recently, many studies have been made on the relationship between the growth of plants and the wavelength of light, and it has become clear that the light wavelength region effective for photosynthesis is 400 to 700 nm. It is a problem to prevent weeds that are harmful to the growth of crops by blocking light.

  By solving this problem, it is possible to reduce labor for weeding during crop production. If you only want to block the transmission of light in the wavelength region that is effective for photosynthesis, you can use an agricultural film with reduced light transmittance, such as a black agricultural film. There is a problem that it cannot be secured.

  Therefore, a film containing a large amount of zeolite (see Patent Document 1) has been proposed as an agricultural film in order to ensure heat retention, but this film has good heat retention but has a problem in weed control. It was. In addition, as a film having both heat retaining properties and weed control properties, a film containing iron oxide particles and a pigment (see Patent Document 2) has been developed as an agricultural film. The result is that the heat resistance is good but the heat retention is poor, and an agricultural film that sufficiently satisfies both the heat retention and the weed control is desired.

Japanese Examined Patent Publication No. 61-44092 Japanese Patent No. 3215581

  The present invention provides an agricultural film excellent in heat retention and weed control.

  The agricultural film of the present invention comprises 100 parts by weight of a thermoplastic resin, 1 to 10 parts by weight of porous zeolite and an organic pigment, and has a light transmittance of 40% or less at any wavelength in the wavelength range of 400 to 700 nm. The light transmittance is 60% or more at any wavelength in the wavelength region of 710 to 2600 nm.

  As the thermoplastic resin used in the present invention, those conventionally used for agricultural films are used, for example, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene- Polyolefin resins such as polyethylene resins such as α-olefin copolymers and ethylene-vinyl acetate copolymers, and polypropylene resins such as homopolypropylene, propylene-α-olefin copolymers and propylene-vinyl acetate copolymers; Polyvinyl chloride resin; polyester resin; polymethyl methacrylate resin; polycarbonate resin. A thermoplastic resin may be used independently, or 2 or more types may be used together. Of these, the thermoplastic resin is preferably a polyolefin-based resin, and more preferably contains low-density polyethylene and linear low-density polyethylene.

  Examples of the α-olefin constituting the ethylene-α-olefin copolymer include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, and propylene. Examples of the α-olefin constituting the α-olefin copolymer include ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like.

  And as a thermoplastic resin, when low-density polyethylene and linear low-density polyethylene are included, if the content of low-density polyethylene in the thermoplastic resin is small, the molding stability of the film may decrease, If the amount is too large, the mechanical strength of the formed film may be insufficient, so 10 to 30% by weight is preferable. Further, if the content of the linear low density polyethylene in the thermoplastic resin is small, the mechanical strength of the formed film may be insufficient, whereas if it is large, the molding stability of the film may be lowered. Therefore, 70 to 90% by weight is preferable.

  The above-mentioned porous zeolite is a natural or artificial zeolite mineral, and is generally classified structurally by a calcite group, a calcite group, a rhyolite group, a soda zeolite group, a judisite group, and a mordenite group. is there. The porous zeolite has a very large specific surface area and absorbs a large amount of water, thereby significantly increasing the heat energy absorption effect and greatly improving the heat retention of the agricultural film.

  And, if the content of the porous zeolite in the agricultural film is small, the effect of absorbing the heat energy is lowered, while if it is large, the mechanical strength of the agricultural film is lowered, so that 100 parts by weight of the thermoplastic resin. The amount is limited to 1 to 10 parts by weight, and preferably 2 to 5 parts by weight.

  Further, the organic pigment is not particularly limited, but at least one organic pigment selected from the group consisting of a purple organic pigment, a blue organic pigment, and a green organic pigment is preferable. Examples of such organic pigments include dioxazine violet, phthalocyanine blue, diamond green lake, pigment green B, green gold, and phthalocyanine green.

  If the content of the organic pigment in the agricultural film is small, the amount of light transmitted in the wavelength region of 400 to 700 nm in the agricultural film increases, and the weeds synthesize and thrive. The light transmittance in the wavelength region of 400 to 700 nm in the film for use is reduced and weeds can be prevented from growing, but the light transmittance in the wavelength region of 710 to 2600 nm is also reduced, and the soil is covered with the agricultural film. Will hinder the temperature rise. Therefore, in the agricultural film, the light transmittance is 40% or less at any wavelength in the wavelength region of 400 to 700 nm, and the light transmittance is 60% or more at any wavelength in the wavelength region of 710 to 2600 nm. It is preferable to adjust the content of the organic pigment in the agricultural film.

  If necessary, a hindered amine light stabilizer, an antioxidant, an ultraviolet absorber, an antifoggant, a lubricant and the like may be added to the thermoplastic resin as long as the physical properties are not impaired.

  Examples of the hindered amine light stabilizer include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, tetrakis (2,2 , 6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, poly {[6-[(1,1,3,3-tetramethylbutyl) amino] -1, 3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) Imino]} and the like, and may be used alone or in combination of two or more.

  And as said antioxidant, a conventionally well-known thing can be used, For example, chelators, such as a metal salt of carboxylic acid, a phenolic antioxidant, organic phosphorous acid ester, are mentioned.

  As the ultraviolet absorber, conventionally known ones can be used, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2 ′. -Benzophenone ultraviolet absorbers such as dihydroxy-4-methoxybenzophenone, 2,2'-hydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2- (2'-hydroxy -5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5-methylphenyl)- 5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′) Benzotriazole ultraviolet rays such as 5′-di-tert-butylphenyl) -5-chlorobenzotriazole and 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole Absorbers, salicylic acid ester ultraviolet absorbers, cyanoacrylate ultraviolet absorbers and the like may be mentioned, and these may be used alone or in combination of two or more.

  Furthermore, conventionally known antifoggants can be used as the antifogging agent, and examples thereof include surfactants such as silicone surfactants and fluorine surfactants. Also, as the lubricant, conventionally known ones can be used, for example, saturated fatty acid amide such as stearic acid amide, unsaturated fatty acid amide such as erucic acid amide, oleic acid amide, bisamide such as ethylene bis stearic acid amide, etc. Can be mentioned.

  The agricultural film of the present invention can be obtained by molding a resin composition containing the thermoplastic resin, porous zeolite and organic pigment, and an additive added as necessary into a film. As a method for forming the film, any known method may be employed. For example, an inflation method, a T-die method, a calendar method, or the like is employed.

  The agricultural film may be a single-layer thermoplastic resin layer, or may be a laminate of a plurality of thermoplastic resin layers.

  The surface of the agricultural film is obtained by applying and drying an anti-fogging agent composed mainly of colloidal silica in order to make the condensed water generated on the surface of the film into a water film and smoothly flow downward. An anti-fogging layer to be formed or an anti-fogging layer made of a hydrophilic resin such as polyvinyl alcohol may be integrally provided. Examples of the method for applying these antifogging agents include a roll coating method such as a gravure coater, a bar code method, a dip coating method, a spray method, and a brush coating method.

  In addition, if the thickness of the agricultural film is thin, the mechanical strength of the agricultural film is reduced and the film is easily damaged. On the other hand, if the film is thick, cutting, joining, and stretching work of the agricultural film are difficult. Since handling property falls, 10-100 micrometers is preferable and 20-50 micrometers is more preferable.

  The agricultural film of the present invention contains a predetermined amount of porous zeolite, and can keep the temperature of the soil covered with this agricultural film high at night and transmit light in a specific wavelength region. Organic pigments are added so that the rate is within a specific range, which prevents weeds from photosynthesis and prevents weeds from growing. It is possible to sufficiently heat, and therefore, it is possible to improve the efficiency of farm work by promoting the growth of a desired crop and reducing the labor required for weed care.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

(Examples 1-3, Comparative Examples 1-4)
Shown in Table 1 given amount of linear low density polyethylene (density: 0.920 g / cm ^3, melt index: 1.0 g / 10 min), low density polyethylene (density: 0.922 g / cm ^3, a melt index : 0.9 g / 10 min), inflation using a resin composition comprising porous zeolite (trade name “SP2300” manufactured by Nippon Clean Pack Co., Ltd.) and a green organic pigment (trade name “PEX Dark” manufactured by Tokyo Ink Co., Ltd.) An agricultural film having a thickness of 30 μm was obtained by the method. The melt index is a value measured under conditions of a temperature of 190 ° C. and a load of 21.18 N in accordance with JIS K7210.

  In the obtained agricultural film, the light transmittance in the wavelength region of 400 to 700 nm and the wavelength region of 710 to 2600 nm, heat retention performance, weed control, and tensile breaking point load were measured by the methods shown below. The results are shown in Table 1.

(Light transmittance)
Using an ultraviolet / visible / near infrared spectrophotometer (manufactured by Hitachi, Ltd.), the wavelength is continuously increased from 200 nm to 2600 nm in the wavelength region of 200 to 2600 nm, and the agricultural film in the wavelength region of 200 to 2600 nm The light transmittance of was measured continuously. Table 1 shows the maximum light transmittance in the wavelength region of 400 to 700 nm and the minimum light transmittance in the wavelength region of 710 to 2600 nm.

(Heat retention performance)
Seven planters (length 70 cm × width 40 cm × height 50 cm) filled with soil inside were installed in a steel frame house (length 6 m × width 6 m × height 4 m). And the agricultural film obtained by the Example or the comparative example was stretched | stretched all over the upper-end opening part of each planter, respectively, and the upper-end opening part of the planter was coat | covered. In addition, another planter was prepared for the reference, and a transparent agricultural film was stretched in the same manner as described above at the upper end opening of the planter.

And the thermocouple was arrange | positioned in the soil of each planter, and the soil temperature of the depth of 10 cm in the ground was continuously measured every hour for 1 week. The measured temperature is arithmetically averaged for each planter to obtain the measured temperature, and the temperature difference from the measured temperature of the reference planter (reference measured temperature) is calculated for each planter based on the following formula. And evaluated.
Temperature difference (° C) = Measurement temperature-Reference measurement temperature

○: The temperature difference was 2 ° C. or more.
(Triangle | delta): The temperature difference was 0.5 degreeC or more and less than 2 degreeC.
X: The temperature difference was less than 0.5 degreeC.

(Weed control)
Agricultural film was laid on July 1, 2004 on the farmland in Sekisui Film Co., Ltd. Sendai Factory, and evaluated based on the weed growth after 30 days.
○: Weed overgrowth was not observed.
Δ: A small amount of weeds proliferated, but there was little problem.
X: A large amount of weeds grew.

(Tensile breaking point load)
The tensile breaking point load of the agricultural film was measured according to JIS K7127 using Tensilon (manufactured by Toyo Seiki Seisakusho) and evaluated according to the following criteria.
○: No breakage occurred at a load of less than 1000 g.
Δ: Fracture occurred at a load of 500 g or more and less than 1000 g.
X: Fractured with a load of less than 500 g.

Claims (2)

It consists of 100 parts by weight of a thermoplastic resin, 1 to 10 parts by weight of porous zeolite and an organic pigment, and has a light transmittance of 40% or less at any wavelength in the wavelength region of 400 to 700 nm and in the wavelength region of 710 to 2600 nm. An agricultural film having a light transmittance of 60% or more at any wavelength. The agricultural film according to claim 1, wherein the thermoplastic resin comprises low density polyethylene and linear low density polyethylene.