JP2007295858A - Agricultural coating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agricultural coating material sufficiently transmitting light whose wave length is in a visible area without excessively transmitting light whose wave length is in an infrared light area, and also having satisfactory transparency and excellent heat-shielding property in spite of being provided with titanium oxide-containing coating film. <P>SOLUTION: The agricultural coating material comprises at least a single-layer thermoplastic resin film, and is provided with a coating film applied to at least one surface of the film, wherein the coating film contains the titanium oxide having a weight average particle diameter of 0.6-1.5 μm in its composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an agricultural covering material having heat shielding performance suitable for agricultural houses, tunnels and the like for crop cultivation.

  Conventionally, agricultural coating materials such as polyolefin resin films and polyvinyl chloride resin films have been used in agricultural crop cultivation facilities such as agricultural houses. However, when such an agricultural film is used for cultivating crops in an agricultural house, there is a problem that the temperature in the house becomes high due to solar sunshine and the cultivation of the crops is hindered. Moreover, since raising seedlings, such as a strawberry seedling with weak resistance, is performed with a dark-colored seedling pot, the overheated state was not preferable for raising seedlings. In order to solve such problems, countermeasures such as applying a cold chill or a light-shielding net on the agricultural covering material, or providing a light blocking layer or a reflecting layer on the agricultural covering material itself have been taken.

  For example, in Japanese Patent Application Laid-Open No. 61-111350 (Patent Document 1), a light shielding property for agriculture comprising a vinyl chloride resin and an aluminum powder, a white pigment (titanium oxide) or a white pigment, and carbon black. A film is disclosed. In JP 2004-314363 A (Patent Document 2), a polyethylene multilayer comprising at least one white resin layer containing 100 parts by mass of a polyethylene resin and 10 to 50 parts by mass of a titanium oxide pigment. Agricultural covering material that is a film, 10 to 50 parts by mass of titanium oxide pigment with respect to 100 parts by mass of polyethylene resin in the entire multilayer film, a film thickness of 70 to 200 μm, and a light shielding rate of 80% or more. It is disclosed. However, in the agricultural coating materials described in Patent Documents 1 and 2, in order to efficiently shield sunlight from the titanium oxide to be contained, the weight average particle diameter is generally about 500 nm or less (preferably 100 nm to 300 nm). Particle size titanium oxide was used. Therefore, even if a small amount of titanium oxide pigment is contained, the agricultural coating itself becomes white and the appearance and transparency are impaired, and the average transmittance of light in the visible light region necessary for photosynthesis is lowered and There has been a problem of affecting the development of

  In Japanese Patent Application Laid-Open No. 11-292996 (Patent Document 3), a metal in which another metal having an oxidation number equal to or lower than the oxidation number of the metal constituting the metal oxide is dissolved in the crystal structure of the metal oxide. A thermoplastic resin film comprising a substance obtained by coating an oxide with a titanium oxide or a hydrous oxide is disclosed. However, in the thermoplastic resin film described in Patent Document 3, titanium oxide having a fine particle diameter of 1 to 500 nm is used, and thus the problem that transparency is impaired and the visibility necessary for photosynthesis are required. There was a problem that even the light in the light region was largely blocked, affecting the cultivation of crops.

Japanese Patent Application Laid-Open No. 11-18589 (Patent Document 4) discloses an agricultural synthetic resin film coated with a coating film containing titanium oxide having a photocatalytic function. The titanium oxide added here is not added for heat shielding performance, but has a photocatalytic function on the coating film. I do not have.
Japanese Patent Laid-Open No. 61-111350 JP 2004-314363 A Japanese Patent Laid-Open No. 11-292996 Japanese Patent Laid-Open No. 11-18589

  The present invention has been made in view of the above-described problems of the prior art, and is a light having a wavelength in the near infrared region despite being an agricultural coating material having a coating film containing titanium oxide. Ground temperature that can sufficiently transmit light having a wavelength in the visible light range without excessive transmission, and has sufficient transparency and excellent heat shielding properties, and affects the root part of the crop. An object of the present invention is to provide an agricultural covering material that can suppress the increase in the amount of light and reduce the burning of leaves caused by direct light irradiation.

  As a result of intensive studies to achieve the above object, the present inventors have found that at least one coating film containing titanium oxide having a weight average particle diameter of 0.6 to 1.5 μm in an agricultural coating material. Surprisingly, the light having the wavelength in the near-infrared light region can be sufficiently transmitted without excessively transmitting the light having the wavelength in the near-infrared light region, and sufficiently transparent. The present invention has been completed by discovering that the direct light transmittance can be reduced by reducing the direct light transmittance.

  That is, the agricultural coating material of the present invention is an agricultural coating material comprising at least one layer of a thermoplastic resin film, and a coating film is provided on at least one surface, and the weight average particle in the coating film composition It contains titanium oxide having a diameter of 0.6 to 1.5 μm.

  Moreover, as the agricultural covering material of the present invention, the average transmittance of light in the visible light region having a wavelength of 400 nm or more and less than 700 nm is 75% or more, and the near infrared light region having a wavelength of 700 nm or more and less than 2000 nm. It is preferable that the average transmittance | permeability of the light ray in is 85% or less.

  Furthermore, as the agricultural covering material of the present invention, it is preferable that the direct light transmittance is 40% or more and 75% or less in the transmitted light in the near infrared light region having a wavelength of 700 nm or more and less than 2000 nm.

  The direct light in the present invention is a light beam that linearly passes through the coating material, and the direct light transmittance is a thing that indicates the ratio of the light beam that is transmitted as direct light to the transmitted light beam. It is.

  According to the present invention, the wavelength is in the visible light region without excessively transmitting the light having the wavelength in the near infrared light region, even though it is an agricultural covering material having a coating film containing titanium oxide. It is possible to provide an agricultural covering material that can sufficiently transmit light and that has sufficient transparency and excellent heat shielding properties.

  The average transmittance of light in the visible light region having a wavelength of 400 nm or more and less than 700 nm is 75% or more, and the average transmittance of light in the near infrared light region having a wavelength of 700 nm or more and less than 2000 nm is 85%. Since it is possible to suppress an increase in the temperature in the house, it is possible to prevent poor crop growth due to an overheat failure.

  Furthermore, since the direct light transmittance is 40% or more and 75% or less in the transmitted light in the near-infrared light region having a wavelength of 700 nm or more and less than 2000 nm, the burning or discoloration of the crop leaves by the direct light is prevented. In addition, since it becomes possible to suppress an increase in temperature particularly in the seedling pot, it is suitable for growing seedlings such as strawberry seedlings.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  The agricultural coating material of the present invention is an agricultural coating material comprising at least one layer of a thermoplastic resin film, and a coating film is provided on at least one surface, wherein the coating film composition has a weight average particle diameter. It contains titanium oxide having a thickness of 0.6 to 1.5 μm.

  The titanium oxide according to the present invention has a weight average particle diameter of 0.6 to 1.5 μm. When the weight average particle diameter is less than 0.6, the average transmittance of light in the visible light region having a wavelength of 400 nm or more and less than 700 nm is lowered and the light in the near infrared light region having a wavelength of 700 nm or more and less than 2000 nm is reduced. As the average transmittance increases, the resulting agricultural covering material becomes white and the transparency decreases, which reduces the efficiency of photosynthesis in the house covered with the agricultural covering material, and further provides heat insulation. Also decreases. On the other hand, when the weight average particle diameter exceeds 1.5, the light scattering efficiency in the near infrared region decreases, and as a result, the average light transmittance in the near infrared region increases and the heat shielding property decreases. Furthermore, the dispersibility to a coating-film composition also falls, a uniform coating film cannot be applied, and a moldability falls.

  Examples of the thermoplastic resin according to the present invention include vinyl chloride resin, olefin resin, ethylene-vinyl acetate copolymer resin, polyester resin, fluorine resin, acrylic resin, and polyurethane resin.

  Examples of the vinyl chloride resin include polyvinyl chloride, which is a homopolymer of vinyl chloride, and vinyl chloride and other monomers, such as ethylene, propylene, vinyl acetate, acrylic acid, methacrylic acid, acrylic ester, methacrylic acid. Examples thereof include copolymers with esters, maleic acid, maleic esters, fumaric acid, itaconic acid, vinylidene chloride, acrylonitrile, higher vinyl ethers, and the like. Such vinyl chloride resins can be used singly or in combination of two or more.

  Examples of the olefin resin include low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polyethylene such as polyethylene polymerized using a metallocene catalyst; random polymerized polypropylene, block polymerized polypropylene, isotactic polypropylene, Examples thereof include polypropylene such as syndiotactic polypropylene; and olefin resins such as ethylene-vinyl acetate, ethylene-acrylic acid, ethylene-acrylic acid ester, ethylene-methacrylic acid, ethylene-methacrylic acid ester, and other ethylene-based copolymers. Such olefin resin can be used individually by 1 type or in mixture of 2 or more types.

  The ethylene-vinyl acetate copolymer (EVA) -based resin is not particularly limited, but those having a vinyl acetate (VA) content of about 5 to 20% by mass can be preferably used. Further, such ethylene-vinyl acetate copolymer resins may be used alone or in combination of two or more different ethylene contents.

  The polyester-based resin is not particularly limited, but polyethylene terephthalate is preferable, and biodegradable aliphatic polyesters, aromatic-aliphatic polyesters, and the like can also be used.

  Further, as the fluororesin, homopolymers or copolymers of ethylene tetrafluoride, ethylene trifluoride chloride, vinylidene fluoride, vinyl fluoride, hexafluoropropylene, perfluorovinyl ether, and other fluorine-containing monomers Alternatively, copolymers of these fluorine-containing monomers and monomers not containing fluorine, such as ethylene-tetrafluoroethylene copolymer and ethylene-trifluorotrifluoroethylene copolymer, can be mentioned. Such a fluorine-type resin can be used individually by 1 type or in mixture of 2 or more types.

  In addition, as the acrylic resin, a homopolymer of a compound such as acrylic acid ester, methacrylic acid ester, acrylic acid, methacrylic acid, acrylamide, acrylonitrile, or a copolymer of the compound, further, the compound and the compound Copolymers with other monomers that can be copolymerized with styrene. Such acrylic resins can be used singly or in combination of two or more.

  Furthermore, examples of the polyurethane-based resin include resins having a urethane group in a molecular structure obtained by appropriately reacting a known bifunctional polyol and a known diisocyanate as appropriate as main components. Such polyurethane resins can be used singly or in combination of two or more.

  Moreover, in the range which does not impair the effect of this invention, the said thermoplastic resin can also be used in mixture of 2 or more types. Moreover, you may comprise the agricultural coating | covering material of this invention by making said thermoplastic resin into a multilayered structure of two or more layers. For example, when the thermoplastic resin is composed of an olefin resin, a multilayer structure is preferable in consideration of processability such as a welder.

  The coating film provided on at least one surface of the agricultural covering material of the present invention is provided by applying a paint containing titanium oxide having a weight average particle diameter of 0.6 to 1.5 μm. As thickness of a coating film, 1-20 micrometers is preferable. When the thickness of the coating film is less than 1 μm, the weight average particle diameter of titanium oxide is 0.6 μm or more. It is easy to be damaged and may reduce the transparency of the agricultural covering material, which is not preferable. If it exceeds 20 μm, whitening may occur when the agricultural covering material is bent.

  This paint is composed of titanium oxide having the above particle size, a binder resin component, and, if necessary, a diluting solvent composed of water or an organic solvent.

  The dilution solvent is appropriately selected depending on the coating property of the paint and the binder resin component. Further, the amount of titanium oxide added to the paint is appropriately determined depending on the thickness of the coating film to be formed. For example, when the coating thickness is 2.0 μm, the addition amount of titanium oxide is 10 to 35 parts by mass with respect to 100 parts by mass of the resin solid content, and when the coating thickness is 10 μm, the resin solid content is 100 parts by mass. On the other hand, the addition amount of titanium oxide is about 2 to 7 parts by mass. If the addition amount of titanium oxide is small, the average transmittance of light in the near-infrared light region having a wavelength of 700 m or more and less than 2000 nm exceeds 85%, which is not preferable in terms of the heat shielding effect. If the amount is too large, the average transmittance of light in the visible light region having a wavelength of 400 nm or more and less than 700 nm is less than 75%, which increases the possibility of hindering crop growth and decreases transparency.

  Specific examples of the binder resin component used in the present invention include acrylic resins (including perfluoroacrylic resins), fluororesins, vinyl chloride resins, cellulose resins, polyamide resins, and urethane resins. , Epoxy resin-based, silicone resin-based, polyester resin-based organic solvent-based (preferably alcohol-based) paints or water-based (emulsion-based) paints; or water, methanol, isopropyl alcohol, n-butyl without a resin binder Any coating material using alcohol, isobutyl alcohol, ethylene glycol, xylene or the like as a dispersion medium can be used.

  As a method for applying the paint to at least one surface of the agricultural covering material, a generally performed method such as a roll coater can be used.

In addition, in the paint containing titanium oxide according to the present invention, in addition to the titanium oxide and the binder resin, a light stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a pigment, a drip-proof agent, an anti-fogging agent, etc. Various additives can be added.

  Examples of the light stabilizer include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6- Tetramethyl-4-piperidylbenzoate, N- (2,2,6,6-tetramethyl-4-piperidyl) dodecylsuccinimide, 1-[(3,5-di-tert-butyl-4-hydroxyphenyl) Propionyloxyethyl] -2,2,6,6-tetramethyl-4-piperidyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, bis (2,2,6,6-tetramethyl- 4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (1,2,2,6,6, -pentamethyl-4-piperidi ) -2-Butyl-2- (3,5-di-tert-butyl-4-hydroxybenzyl) malonate, N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylene Diamine, tetra (2,2,6,6-tetramethyl-4-piperidyl) butanetetracarboxylate, bis (2,2,6,6-tetramethyl-4-piperidyl) di (tridecyl) butanetetracarboxylate, Bis (1,2,2,6,6-pentamethyl-4-piperidyl) di (tridecyl) butanetetracarboxylate, 3,9-bis {1,1-dimethyl-2- [tris (2,2,6, 6-tetramethyl-4-piperidyloxycarbonyloxy) butylcarbonyloxy] ethyl} -2,4,8,10-tetraoxysaspiro [5,5] undecane 3,9-bis {1,1-dimethyl-2- [tris (1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyloxy) butylcarbonyloxy] ethyl} -2,4,8,10 -Tetraoxaspiro [5,5] undecane, 1,5,8,12-tetrakis {4,6-bis [N- (2,2,6,6-tetramethyl-4-biperidyl) butylamino] -1 , 3,5-triazin-2-yl} -1,5,8,12-tetraazadodecane, 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-piperidinol / succinic acid Dimethyl condensate, 2-tert-octylamino-4,6-dichloro-s-triazine / N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine condensate, N , N′− Examples thereof include hindered amine light stabilizers such as bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine / dibromoethane condensate. Among such hindered amine light stabilizers, hindered amine light stabilizers having an average molecular weight of about 800 to 2000 are preferable. Moreover, as an addition amount of such a light stabilizer, it is preferable that it is 0.01-0.3 mass part with respect to 100 mass parts of binder resin.

  Examples of the antioxidant include alkylphenols, alkylene bisphenols, alkylphenol thioethers, β, β'-thiopropionic acid esters, organic phosphites, aromatic amines, phenol / nickel composites, and the like. Such antioxidant can be used individually by 1 type or in mixture of 2 or more types.

  Examples of the ultraviolet absorber include salicylic acid esters, benzotriazoles, hydroxybenzophenones, acrylonitrile substituted products, and the like. Such an ultraviolet absorber can be used individually by 1 type or in mixture of 2 or more types. Specifically, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-ethoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 5,5′-methylenebis (2-hydroxy 2-hydroxybenzophenones such as -4-methoxybenzophenone); 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butyl) Phenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert-) Octylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′- 2- (2′-hydroxyphenyl) benzotriazoles such as cumylphenyl) benzotriazole, 2,2′-methylenebis (4-tert-octyl-6-benzotriazole) phenol; phenyl salicylate, resorcinol monobenzoate, 2, Benzoates such as 4-di-tert-butylphenyl-3 ′, 5′-di-tert-butyl-4′-hydroxybenzoate, hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate; Oxanilides such as ethoxy-4'-dodecyloxanilide; Cyanoacrylates such as ethyl-α-cyano-β, β-diphenylacrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate Kind.

  Examples of the lubricant or the anti-adhesive agent include metal soaps such as zinc stearate, barium stearate, calcium stearate; hydrocarbons such as liquid paraffin, polyethylene waxes, chlorinated hydrocarbons; stearic acid, stearamide, Fatty acids and fatty acid amides such as palmitic acid amide, methylene bisstearamide, ethylene bisstearamide; fatty acid esters such as butyl stearate, cetyl palmitate, monoglyceride stearate; fatty acids such as stearic acid, isostearic acid, palmitic acid Lubricants: Lubricants such as organophosphate metal salt lubricants such as barium isodecyl phosphate and calcium octadecyl phosphate can be used. Such lubricants or anti-sticking agents can be used alone or in combination of two or more.

  Examples of the drip-proofing agent include sorbitan fatty acid ester, sorbitol fatty acid ester, glycerin fatty acid ester, diglycerin fatty acid ester, triglycerin fatty acid ester, tetraglycerin fatty acid ester, and the like; sorbitan fatty acid / dibasic acid ester, sorbitol fatty acid -Esters of polyhydric alcohols and fatty acids such as dibasic acid esters, diglycerin fatty acids and dibasic acid esters, esters of polyhydric alcohols and fatty acids and dibasic acids; or ethylene oxide, propylene oxide, butylene oxide, etc. In particular, sorbitan palmitate, sorbitan stearate, sorbitan stearate / ethylene oxide 2 mol adduct, Rubitan stearate / propylene oxide 3 mol adduct, sorbitol stearate, sorbitol stearate / ethylene oxide 3 mol adduct, diglycerin palmitate / ethylene oxide 2 mol adduct, sorbitan stearate adipate / ethylene oxide 2 mol adduct And diglycerin palmitate sebacate / propylene oxide 3 mol adduct, sorbitol palmitate adipate / ethylene oxide 3 mol adduct, and the like. Such drip-proofing agents can be used alone or in combination of two or more. Moreover, as addition amount of such a dripproofing agent, about 0.5-6 mass parts is preferable with respect to 100 mass parts of binder resin.

Examples of the anti-fogging agent include a fluorine-containing compound having a fluorine-containing group and at least one group selected from a hydroxyl group and an alkylene oxide group in one molecule. Examples of the fluorine-containing group, a perfluoroalkyl group _{(C n F 2n + 1} group), perfluoro alkoxyl group _{(C n F 2n + 1} O group), polyfluoroalkyl group _{(H m C n F 2n +} 1-m group), perfluoro alkenyl group _{(C n F 2n-1} group), polyfluoroalkenyl group _{(H m C n F 2n-} 1-m group). In the formula of the fluorine-containing group, m represents an integer of 1 to 3, and n represents an integer of 3 to 20. As examples of the alkylene oxide group, the general formula _{(C 2} H 4 _{O) x,} or a group represented by _{(C 3} H 6 _{O) x} and the like. Moreover, x in the said general formula shows the integer of 1-30. The addition amount of such a fluorine-containing compound is preferably 0.01 to 1 part by mass, more preferably about 0.05 to 0.5 part by mass with respect to 100 parts by mass of the binder resin.

Other additives include mineral additives such as hydrotalcite and feldspar, and homopolymers and / or copolymers of glycidyl acrylate and / or glycidyl methacrylate. As such a homopolymer and / or copolymer of glycidyl acrylate and / or glycidyl methacrylate, those having an average molecular weight of 1000 or more are preferable. In particular, a homopolymer of glycidyl methacrylate is preferable. The addition amount of the homopolymer and / or copolymer of glycidyl acrylate and / or glycidyl methacrylate is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin. It is. When the addition amount of the homopolymer and / or copolymer of glycidyl acrylate and / or glycidyl methacrylate is less than the lower limit relative to 100 parts by weight of the thermoplastic resin, no improvement in durability is observed, and there is a tendency to stick when kneaded for a long time. . On the other hand, when the addition amount of the homopolymer and / or copolymer of glycidyl acrylate and / or glycidyl methacrylate with respect to 100 parts by weight of the thermoplastic resin exceeds the above upper limit, the improvement in durability is small for the cost increase, and molding processing Coloring of time tends to occur.

  A method for molding the thermoplastic resin film is not particularly limited, and a known molding method such as a calendar method, an extrusion method, an inflation method, or the like can be appropriately employed. Further, when an olefin resin is used as the thermoplastic resin, it is preferable to adopt an inflation method from the viewpoints of processability and the width of the product to be obtained (when the width is about 12 m).

  Moreover, as an agricultural covering material of the present invention, when using a polyolefin resin film as the thermoplastic resin film, it is preferable to have a multilayer structure in consideration of processability and physical properties such as a welder. At least two or more thermoplastic resin films may be provided, and at least one of the thermoplastic resin films may be a polyolefin resin film.

  In the case where the agricultural covering material of the present invention has a multilayer structure, the type of resin constituting the other layer may be the same as or different from that of the thermoplastic resin film. Further, when the agricultural coating material of the present invention has a multilayer structure, it is preferable that adjacent layers are layers having high compatibility or adhesiveness.

  A method for producing such a multi-layered agricultural covering material is not particularly limited, and a known method can be used as appropriate. For example, a film having a multi-layered structure at a time by a molding method such as a multi-layer coextrusion inflation method. Alternatively, a film having a multilayer structure may be produced by forming a single layer thermoplastic resin film and then laminating it.

  Moreover, as the agricultural covering material of the present invention, the average transmittance of light in the visible light region having a wavelength of 400 nm or more and less than 700 nm is 75% or more, and in the near infrared light region having a wavelength of 700 nm or more and less than 2000 nm. It is preferable that the average transmittance of a certain light beam is 85% or less. When the average transmittance of light rays in the visible light region is less than 75%, the obtained agricultural coating material tends not to sufficiently transmit the light rays necessary for growing crops, while in the near infrared light region. If the average transmittance of a certain light beam exceeds 85%, sufficient heat shielding properties cannot be obtained in the area covered with the resulting agricultural covering material, which may cause crop appearance defects and growth obstacles. This is not preferable because the growth inhibition of the root occurs or the heat shielding effect cannot be obtained and the possibility of the root growth inhibition due to overheating increases.

  Moreover, it is preferable that the average transmittance of direct light among the transmitted light in the near-infrared light region having a wavelength of 700 nm or more and less than 2000 nm is 40% or more and 75% or less. It is possible to prevent appearance defects such as burning, and it is possible to suppress an increase in underground temperature, and in particular, it is possible to suppress an increase in temperature in the seedling pot, so that strawberry seedlings grown in summer An agricultural covering material that can be suitably used for raising seedlings.

  The thickness of the agricultural coating material of the present invention is not particularly limited, and can be set to a desired light transmittance depending on the amount of titanium oxide added to the coating film and the thickness of the coating film. Although it can select, it is preferable that it is 50-200 micrometers, for example, and it is more preferable that it is 75-150 micrometers. If the thickness of the agricultural film of the present invention is less than the lower limit, physical properties such as tensile strength of the resulting agricultural covering material tend to decrease, and the stretching work during use tends to be difficult. Since the obtained agricultural film becomes heavy, it tends to be difficult to perform the expansion work at the time of use. In addition, when making the agricultural coating | covering material of this invention into a multilayer structure, it is preferable that the thermoplastic resin film concerning this invention has a thickness of 50-150 micrometers from a viewpoint of exhibiting the effect of this invention reliably. .

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. Moreover, the agricultural coating | covering material obtained by each Example and each comparative example was evaluated as follows.

<Evaluation of light transmittance>
The total light transmittance of the agricultural covering material obtained in each example and each comparative example was measured using a spectrophotometer (manufactured by JASCO Corporation: trade name “V-570”). Among the obtained results, the average transmittance of light having a wavelength of 380 to 400 nm, the average transmittance of light in the visible light region having a wavelength of 400 nm to less than 700 nm, and the near infrared light region having a wavelength of 700 nm to less than 2000 nm. Table 1 shows the average transmittance of light and the average transmittance of direct light among transmitted light in the near-infrared light region having a wavelength of 700 nm or more and less than 2000 nm.

[Examples 1 to 4 and Comparative Examples 1 to 5]
In Examples 1 to 4 and Comparative Examples 1 to 5, the coating composition having the blending amounts shown in Table 1 was used for each coating composition with respect to 100 parts by weight of a diluted mixed solution composed of 50/50 ethyl acetate / isopropyl alcohol. The product is adjusted to 15 parts by mass, coated on an agricultural covering material (product name: NON-KILLY Asuka, film thickness 0.1 mm, Achilles Co., Ltd.) by the gravure coating method, and then dried at 90 ° C. for 30 seconds. The agricultural coating material of each Example having a coating film with a thickness of 2 μm was prepared.

  The light transmittance of the obtained agricultural coating material was measured and the results are shown in Table 1.

As is clear from the results shown in Table 1, the average transmittance of light in the visible light region of the agricultural coating material of the present invention is as high as 75% or more, and the average transmittance of light in the near infrared light region. Are both as low as 85% or less, and the average transmittance of direct light among the transmitted light of the light in the near infrared region is 75% or less. Therefore, the agricultural coating material of the present invention has a wavelength in the near infrared region. It was confirmed that a light beam having a wavelength in the visible light region can be sufficiently transmitted without excessively transmitting the light beam in the region. Moreover, from the value of the average transmittance | permeability of the light ray of such a visible light area | region, it was confirmed that the agricultural coating | covering material of this invention has high transparency. Therefore, it was confirmed that the agricultural film of the present invention has high transparency and an excellent heat shielding effect.

  On the other hand, in Comparative Examples 1 and 2 in which the content of titanium oxide is less than 10 parts by mass with respect to 100 parts by mass of the binder resin, the average transmittance of light in the near-infrared region is 85% or more. The shortage is confirmed, and the average transmittance of direct light in the near-infrared light region exceeds 75%, which seems to possibly inhibit the growth of crops. In Comparative Examples 3 and 4, since the content of titanium oxide exceeds 35 parts by mass with respect to 100 parts by mass of the binder resin, the average transmittance of light in the visible light region becomes less than 75%, and the growth of the crop It is not preferable because it may cause trouble.

  In Comparative Example 5, since the weight average particle diameter of titanium oxide was 0.6 μm or less, even when added in an equivalent amount to Example 2, there was a problem in all light transmittances.

  As described above, according to the present invention, although the coating material for agriculture has a coating film containing titanium oxide, the wavelength is not excessively transmitted through the light beam in the infrared region. It is possible to provide an agricultural covering material that can sufficiently transmit light rays in the visible light region and that has sufficient transparency and excellent heat shielding properties.

  Therefore, when the agricultural covering material of the present invention is used for, for example, an agricultural house, it can sufficiently transmit light having a wavelength necessary for growing crops in the visible light region while suppressing temperature rise in the house. It is possible to reduce the direct light with respect to the ground temperature, so it is also excellent for raising seedlings using seedling pots and is useful as an agricultural covering material for agricultural facilities such as agricultural houses and tunnels. .

Claims (4)

  An agricultural covering material comprising at least one layer of a thermoplastic resin film and provided with a coating film on at least one surface, the weight average particle diameter being 0.6 to 1.5 μm in the coating film composition Agricultural covering material characterized by containing titanium oxide.   The average transmittance of light in the visible light region having a wavelength of 400 nm or more and less than 700 nm is 75% or more, and the average transmittance of light in the near infrared light region having a wavelength of 700 nm or more and less than 2000 nm is 85% or less. The agricultural covering material according to claim 1, characterized in that it is present.   The agricultural coating material according to claim 1 or 2, wherein the direct light transmittance of transmitted light having a wavelength of 700 nm or more and less than 2000 nm is 40% or more and 75% or less. The agricultural covering material according to any one of claims 1 to 3, comprising at least two thermoplastic resin films, wherein at least one of the thermoplastic resin films is a polyolefin resin film.