JP2006141268A - Heat ray shielding-type agricultural film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat ray shielding-type agricultural film excellent in mechanical strength, and improved in weather resistance of course and sufficient transmission of a ray quantity from sunlight and effect of shielding heat ray from sunlight, and retaining heat ray shielding effect for a long period. <P>SOLUTION: This heat ray shielding-type agricultural film contains 0.01-5 pts.wt. of minute particle-like graphite as a heat ray shielding agent, based on 100 pts.wt. of thermoplastic resin. The average particle diameter of the minute particle-like graphite is preferably 1-20 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an agricultural film used in a crop cultivation facility. More specifically, the present invention relates to a heat ray shielding agricultural film that is suitably used as an outer layer of an agricultural house having transparency and excellent heat shielding properties.

  In the cultivation of soft vegetables (for example, spinach, Japanese mustard spinach, gentian vegetables, celery, mizuna), it is necessary to sufficiently transmit the amount of light from sunlight and to block heat rays from sunlight to some extent. This is because when the amount of light from sunlight is insufficient, there are problems such as poor growth of crops and poor quality of vegetables. Also, if the heat rays from sunlight are not shielded to some extent, for example, when the above-mentioned soft vegetables are cultivated at a relatively high temperature from May to September, the germination rate is higher than that at other relatively low temperatures. This is because there is a problem that a decrease in growth rate or growth delay occurs, diseases (for example, wilt disease such as spinach, yellow wilt disease such as komatsuna) tend to occur, and the yield rate of harvested vegetables also decreases. Therefore, in order to solve these problems, conventionally, cultivation at a high temperature is suspended, or cold straw, light-shielding nets, light-shielding are provided on the outside of agricultural transparent films (such as agricultural vinyl chloride films and agricultural polyolefin-based films). There is a method to cover and layer shading materials such as curtains and non-woven fabrics for cultivation.

However, in this method, even if the heat ray can be shielded, the amount of light from sunlight is insufficient, resulting in poor growth and poor quality of vegetables. Furthermore, as another method, there is also a method of shielding heat rays from sunlight by kneading a heat ray shielding agent into an agricultural transparent film and covering the agricultural house. For example, Patent Literature 1 and Patent Literature 2 disclose a method using a naphthalocyanine compound as a heat ray absorbent. However, in this method, there is a problem in the weather resistance of the naphthalocyanine compound and the durability of the heat ray shielding effect. In Patent Document 3 and Patent Document 4, a solution containing fine particles of tin oxide doped with antimony (hereinafter abbreviated as ATO) or indium oxide doped with tin (hereinafter abbreviated as ITO) is applied to the surface of the film substrate. A method is disclosed. Furthermore, Patent Document 5 discloses a method of kneading ATO or ITO into a thermoplastic resin film. However, in any of the methods, the price of ATO or ITO is very expensive and economically disadvantageous, and particularly in the former case, the applied solution is peeled off from the substrate, and the heat ray shielding effect is reduced. There was a problem.
JP 2003-265033 A JP 2003-265034 A Japanese Patent Laid-Open No. 10-250001 Japanese Patent Laid-Open No. 10-250002 JP-A-9-140275

  The present invention is excellent in mechanical strength, not only weather resistance of the film, but also sufficiently transmits the amount of light from sunlight and improves the shielding effect of heat rays from sunlight, and further shields against heat rays over a long period of time. An object of the present invention is to provide a heat ray shielding agricultural film capable of sustaining the effect.

  The invention according to claim 1 is a heat ray shielding agricultural film characterized in that 0.01 to 5 parts by weight of particulate graphite is contained as a heat ray shielding agent with respect to 100 parts by weight of a thermoplastic resin.

  The invention according to claim 2 is the heat ray-shielding agricultural film according to claim 1, wherein the average particle diameter of the particulate graphite is 1 to 20 μm.

  As a result of intensive studies to solve the above problems, the present inventor has solved the above problems by blending 0.01 to 5% by weight of particulate graphite with respect to 100 parts by weight of the thermoplastic resin.

The details will be described below.
The thermoplastic resin used in the present invention is not particularly limited as long as it has been conventionally used in agricultural films. For example, polyethylene resins such as low density polyethylene, medium density polyethylene, and high density polyethylene, ethylene Copolymer of propylene, 1-butene, 4-methyl 1-pentene, 1-hexene, 1-octene and the like, olefin, ethylene-vinyl acetate copolymer, polypropylene resin, propylene and the α-olefin Copolymer, propylene-vinyl acetate copolymer, polyvinyl chloride resin, polyester resin, polymethyl methacrylate resin, polycarbonate resin, etc., and these may be used alone or in combination of two or more. You may use together.

  Among the above thermoplastic resins, polyolefins such as polyethylene resin, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, polypropylene resin, propylene-α-olefin copolymer, propylene-vinyl acetate copolymer, etc. Resins are preferred, and ethylene-α-olefin copolymers and ethylene-vinyl acetate copolymers are more preferred.

  The heat ray shielding agricultural film of the present invention may be a single layer film or a multilayer film, but is preferably a multilayer film from the viewpoint of film strength, anti-blocking property and the like.

  In the case of a multilayer film, the intermediate layer is not particularly limited, but at least one of the surface layers is preferably an ethylene-α-olefin copolymer from the viewpoint of film strength and antiblocking properties.

  In the case of a single layer film, an ethylene-α-olefin copolymer is preferable from the viewpoint of film strength and antiblocking properties.

  The amount of the particulate graphite added is 0.01 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin. If the addition amount is less than 0.01 parts by weight, the heat shielding effect is reduced. On the contrary, if the addition amount is more than 5 parts by weight, the transparency of the heat ray shielding agricultural film is lowered.

  The fine particle graphite is not particularly limited, but the average particle diameter is preferably 1 to 20 μm, more preferably 3 to 10 μm, and still more preferably 5 to 7 μm. When the particle diameter of the fine graphite is smaller than 1 μm, not only the heat shielding effect is reduced, but also the dispersibility in the thermoplastic resin is deteriorated and the molding stability is also lowered. On the contrary, if the particle diameter is larger than 20 μm, the transparency of the heat ray shielding agricultural film is lowered.

  In the heat ray-shielding agricultural film of the present invention, an inorganic heat retention agent, an organic heat retention agent, a hindered amine light stabilizer, a heat stabilizer, an antioxidant, and an ultraviolet absorption as long as the effects of the present invention are not impaired. Agents, anti-fogging agents, lubricants, pigments and the like may be added.

  As the above-mentioned inorganic heat insulating agent, it is added for the two purposes of improving the heat retention of the obtained heat ray-shielding agricultural film and improving the fluctuation of extrusion during film formation. For example, magnesium oxide, calcium oxide, aluminum oxide, Magnesium carbonate, calcium carbonate, magnesium sulfate, calcium sulfate, aluminum sulfate, lithium phosphate, calcium phosphate, magnesium silicate, calcium silicate, aluminum silicate, kaolin, clay, talc, hydrotalcite, lithium aluminum composite hydroxide, other composites And hydroxides (hydroxides having at least two kinds of elements selected from alkali metals, alkaline earth metals, transition metals, 2B group elements, and 4B group elements of silicon or more). These may be used alone or in combination of two or more.

  As said hindered amine light stabilizer, conventionally well-known arbitrary things are used and it does not specifically limit. Specifically, 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. These may be used alone or in combination of two or more.

  The heat stabilizer may be any conventionally known heat stabilizer and is not particularly limited. Specific examples include chelators such as metal salts of carboxylic acids, phenolic antioxidants, and organic phosphites. These heat stabilizers may be used alone or in combination of two or more.

  The antioxidant is not particularly limited and may be any conventionally known antioxidant. Usually, there are many which have the effect as the said heat stabilizer, for example, chelators, such as a metal salt of carboxylic acid, a phenolic antioxidant, organic phosphorous acid ester, are mentioned. These heat stabilizers may be used alone or in combination of two or more.

  The UV absorber may be any conventionally known UV absorber and is not particularly limited. For example, benzophenone series, benzotriazole series, salicylic acid ester series, cyanoacrylate series, etc. can be used alone or in admixture of two or more. Specifically, as a benzophenone ultraviolet absorber, 2,4-dihydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2'-hydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, etc .; 2- (2'-hydroxy-5'-tert-) as a benzotriazole UV absorber Butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di tert- butylphenyl) -5-chloro-benzotriazole, 2- (2'-hydroxy-3 ', 5'-di -tert- amylphenyl) -5-chloro-benzotriazole, and the like. These ultraviolet absorbers may be used alone or in combination of two or more.

  The anti-fogging agent may be any conventionally known anti-fogging agent and is not particularly limited. For example, surfactants such as silicone-based and fluorine-based can be used. The lubricant may be any conventionally known lubricant and is not particularly limited. Examples thereof include saturated fatty acid amides such as stearic acid amide, unsaturated fatty acid amides such as erucic acid amide and oleic acid amide, and bisamides such as ethylene bis stearic acid amide.

  In addition, the heat ray-shielding agricultural film of the present invention is kneaded with an antifogging agent as necessary in order to allow water droplets condensed on its inner surface to flow when spread on an agricultural house, or the like. An antifogging film may be formed on the inner surface. The anti-fogging agent may be any conventionally known anti-fogging agent and is not particularly limited. For example, the anti-fogging agent may be a polyvalent such as glycerin stearic acid ester, diglycerin stearic acid ester, polyglycerin stearic acid ester, sorbitol glyceryl stearic acid ester. Examples thereof include polyhydric alcohol unsaturated fatty acid esters such as alcohol saturated fatty acid ester, glycerin oleate and diglycerin oleate.

  The antifogging film formed on the inner surface of the house is, for example, a coating film of an inorganic oxide sol represented by colloidal silica or colloidal alumina, and as an application thereof, an inorganic oxide sol and an organic compound (surfactant or Coating films such as resins), liquid coating films mainly composed of surfactants, and films mainly composed of hydrophilic resins (for example, polyvinyl alcohol, polyethylene oxide, polysaccharides, polyacrylic acid, etc.) Etc. Examples of a method for forming these films 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.

  As a method for forming the heat ray shielding agricultural film of the present invention, any conventionally known method may be employed. For example, an inflation method, a T-die extrusion method, a calendering method, etc. For example, a method of laminating after forming a film for forming each layer by the above method, a multilayer extrusion method by a T-die extrusion method or an inflation method, and the like, and a multilayer extrusion method by an inflation method are preferably used.

  The thickness of the heat ray shielding agricultural film of the present invention is preferably 20 to 200 μm. If the thickness is less than 20 μm, not only the mechanical strength of the resulting film is lowered but also a heat shielding effect is exhibited. For this purpose, a large amount of heat ray shielding agent must be added, the transparency is lowered, and if it exceeds 200 μm, cutting, joining, stretching work and the like become difficult, and handling properties are lowered. Therefore, the thickness of the film is preferably 20 to 200 μm, more preferably 50 to 150 μm.

  Since the heat ray shielding agricultural film of the present invention has the above-mentioned configuration, it has excellent mechanical strength, weather resistance of the film, as well as sufficient amount of light from sunlight, and from sunlight. The heat ray shielding effect can be improved, and the heat warding shielding effect can be maintained for a longer period of time.

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

(Examples 1-6, Comparative Examples 1-6)
A resin composition for forming the layer (A), the layer (B) and the layer (C) was prepared at the blending ratio shown in Table 1, and each was put into another extruder and melt-kneaded, and then the layer (A ), Layer (B) and layer (C) are three-layer coextrusion molded by inflation method so that the thickness ratio is 1: 7: 2, and layer (A), layer (B) and layer (C) A heat ray-shielding agricultural film composed of a three-layer laminate having a total thickness of 100 μm laminated in this order was obtained. In addition, MFR shown in Table 1 shows melt mass flow rate, and is a value measured at a temperature of 190 ° C. and a load of 21.18 N in accordance with JIS K 7210.

(Evaluation test)
About the heat ray shielding type agricultural film obtained in Examples and Comparative Examples, the following evaluation tests were performed. The results are shown in Table 1.
(1) Molding stability Molding stability when three-layer coextrusion molding was performed by an inflation method was evaluated according to the following criteria.
○: Dispersibility of the additive and film appearance were good, and good molding stability was obtained.
X: Dispersibility of the additive and film appearance were poor, and molding stability was insufficient.

(2) Visible light transmittance The total light transmittance at 550 nm was measured for the visible light transmittance of the obtained heat ray-shielding agricultural film using a self-recording spectrophotometer (Hitachi U-3500 type).

(3) Heat ray blocking rate The total light transmittance of the heat ray shielding agricultural film at 300 to 2100 nm was measured using a self-recording spectrophotometer (Hitachi U-3500 type). Next, the energy which permeate | transmits a heat ray shielding type agricultural film was calculated from the calculated | required total light transmittance and the wavelength dependence data of the solar radiation energy from the sun. The heat ray blocking rate was calculated from the transmitted energy and the sunlight energy when not passing through the film.

(4) Thermal insulation The heat ray-shielded agricultural film obtained above was stretched in a closed pipe house (vertical 1.5m x lateral 1m x depth 2.5m), and the ground temperature and temperature during the summer were measured. The soil temperature was measured by putting sand in the center of the house and setting a thermocouple at a depth of 10 cm. The temperature difference between the inside and outside of the pipe house (internal temperature-external temperature) was calculated at 2 pm on a clear day.

Claims (2)

  A heat ray-shielding agricultural film, comprising 0.01 to 5 parts by weight of particulate graphite as a heat ray shielding agent with respect to 100 parts by weight of a thermoplastic resin. The heat ray-shielding agricultural film according to claim 1, wherein the average particle diameter of the particulate graphite is 1 to 20 µm.