JP2010220567A - Heat-shielding agricultural film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shielding agricultural film having strength and weather resistance, sufficiently transmitting the sunlight, sufficiently shielding heat rays from the sunlight, and maintaining antifog and flow drop-preventive properties. <P>SOLUTION: The heat-shielding agricultural film comprises 100 pts.wt. of a thermoplastic resin and 0.1-10 pts.wt. of mica whose surface is coated with titanium oxide. The mica whose surface is coated with titanium oxide includes 10% cumulated one having a particle diameter of ≥3 μm, and 90% cumulated one having a particle diameter of ≤80 μm, wherein the coating ratio of the mica with the titanium oxide is 35-70%. An antifog and flow drop-preventive layer formed of a pH 7-12 antifog and flow drip-preventive agent produced by dispersing 0.1-20 pts.wt. of chain-like silica colloid particles each obtained by joining silica colloid particles each having a particle diameter of 5-40 nm with one another in a length of 40-300 nm into a chain state, and 0.1-10 pts.wt. of polyethylene oxide having a viscosity-average molecular weight of 50,000-1,500,000, into 100 pts.wt. of aqueous medium, is formed on the surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In general, soft vegetables such as spinach, Japanese mustard spinach, chingena, celery, and mizuna are grown in an agricultural house with an agricultural film. In order to cultivate the soft vegetables, although it is necessary to shield heat rays from sunlight to some extent, it is also necessary to sufficiently transmit light rays from sunlight into the agricultural house. If the amount of light from sunlight is insufficient, crop growth will be poor and vegetable quality will be reduced. On the other hand, if the heat rays from sunlight are not shielded at all, especially when the above-mentioned soft vegetables are cultivated at relatively high temperatures from May to September, the germination rate compared to other relatively low temperatures. This caused problems such as a decrease in growth rate, growth delay, wilt disease in spinach, yellow wilt disease in komatsuna, etc., and a decrease in the yield of harvested vegetables.

  In order to solve the above problems, conventionally, the cultivation of soft vegetables at high temperatures is stopped, or the outer surface of an agricultural film such as an agricultural vinyl chloride film or an agricultural polyolefin film is further provided with a cold chill, a light shielding net, and a light shielding. A method of cultivating soft vegetables by overlaying shading materials such as curtains and non-woven fabrics and covering the outer surface of the transparent film for agriculture with the shading material. However, in the above method, although the heat rays from sunlight could be shielded, the amount of light from sunlight was insufficient, resulting in poor growth and poor quality of soft vegetables.

  Furthermore, as another method, there is a method of shielding heat rays from sunlight by kneading a heat ray shielding agent in a transparent film for agriculture and covering the agricultural house with the transparent film for agriculture. For example, Patent Literature 1 and Patent Literature 2 disclose a method using a naphthalocyanine compound as a heat ray absorbent. However, the above method has a problem in the weather resistance of the naphthalocyanine compound and the durability of the heat ray shielding effect.

  Patent Document 3 and Patent Document 4 include a film containing a solution containing fine particles of tin oxide doped with antimony (hereinafter abbreviated as “ATO”) or fine particles of indium oxide doped with tin (hereinafter abbreviated as “ITO”). A method of applying to a substrate surface is disclosed. Furthermore, Patent Document 5 discloses a method of kneading ATO fine particles or ITO fine particles into a thermoplastic resin film. However, in any method, the price of ATO fine particles or ITO fine particles is very expensive, which is economically disadvantageous, and when ATO fine particles or ITO fine particles are applied to a film substrate, it is applied. The coated film peeled off from the base material, and the heat ray shielding effect was reduced.

  In addition, since agricultural films conventionally used for agricultural applications such as pipe houses and tunnels are used in an outdoor environment, moisture easily adheres to the surface. For example, when agricultural films are spread on a house, Due to temperature differences and humidity inside and outside the house, fog and water droplets are formed on the surface of the agricultural film inside the house, which prevents the growth of crops due to poor sunlight transmission, or water droplets generated on the surface of the agricultural film Has fallen onto crops, causing illness and other problems.

  In response to the above problems, various techniques have been devised so far to cause condensed water generated on the surface of agricultural films to flow and to exhibit antifogging properties. For example, there is a method of kneading an anti-fogging drop into an agricultural film and bleeding out the anti-fogging drop to cause the condensed water adhering to the inner surface of the house to flow. However, with this method, an anti-fogging effect can be obtained for a short period of time, but if the anti-fogging drop agent completely bleeds out, the anti-fogging effect is completely lost, that is, the anti-fogging sustainability for a long period is insufficient. There was a problem to do.

  As another method, an antifogging drop agent is coated on the surface of an agricultural film to form an antifogging layer, and this antifogging layer causes the condensed water on the surface of the agricultural film to flow down for a long period of time. Various anti-fogging laminates that maintain the anti-fogging effect have been proposed. For example, Patent Literature 6, Patent Literature 7, Patent Literature 8, and Patent Literature 9 disclose a method of forming an antifogging coating using silica colloid and colloidal alumina in combination.

  However, these methods do not sufficiently solve the above problems, and when the agricultural film is used over a long period of time, the water droplets adhering to the surface of the agricultural film do not become a water film, and the liquid droplets are defective. There was a problem that water droplets could fall on the crop. Moreover, since the antifogging droplets using a general silica colloid are acidic, the storage stability of the antifogging droplets often deteriorates when stored for a long period of time. Furthermore, when such acidic antifogging drops are used, operating the coating equipment necessary for applying the antifogging drops for a long time not only rusts the coating apparatus but also prevents the antifogging drops. When the agricultural film coated with the agent is used for the exterior of the house, the environment inside the house is hot and humid, and therefore, there is a problem in that rusting is promoted in the steel frame portion of the house.

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 JP-A-7-53747 JP-A-7-82398 JP-A-8-319476 JP-A-11-240112

  The present invention has strength and weather resistance that can be used as an agricultural film, can sufficiently transmit light rays from sunlight, and can sufficiently shield heat rays from sunlight over a long period of time. A heat-shielding agricultural film that can maintain antifogging flowability and can be suitably used as an outer layer of an agricultural house is provided.

  The heat-shielding agricultural film of the present invention is a heat-shielding agricultural film containing 100 parts by weight of a thermoplastic resin and 0.1 to 10 parts by weight of mica whose surface is coated with titanium oxide. The mica coated with titanium oxide has a 10% particle diameter of 3 μm or more and a 90% particle diameter of 80 μm or less, and the coverage of mica by titanium oxide is 35 to 70%. In the part, 0.1 to 20 parts by weight of chain silica colloidal particles obtained by binding silica colloidal particles having a particle size of 5 to 40 nm in a chain shape with a length of 40 to 300 nm, and a viscosity average molecular weight of 50,000 to 1. Anti-fog formed by applying and drying an anti-fogging drop having a pH of 7 to 12 on one surface of the above heat-shielding agricultural film, in which 0.1 to 10 parts by weight of 1,500,000 polyethylene oxide is dispersed. Clouded droplet layer is shaped It is characterized by being made.

  As the thermoplastic resin used in the heat-shielding agricultural film of the present invention, those conventionally used in agricultural films are used, for example, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α. -Polyolefin resins such as olefin copolymers, polyethylene resins such as ethylene-vinyl acetate copolymers, and polypropylene resins such as homopolypropylene, propylene-α-olefin copolymers, propylene-vinyl acetate copolymers; Examples thereof include a vinyl chloride resin; a polyester resin; a polymethyl methacrylate resin; and a polycarbonate resin. These may be used alone or in combination of two or more. Among these, as the thermoplastic resin, polyolefin resins are preferable, polyethylene resins are more preferable, and ethylene-α-olefin copolymers and ethylene-vinyl acetate copolymers are particularly preferable.

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

  The mica whose surface is coated with titanium oxide (hereinafter sometimes referred to as “titanium oxide-coated mica”) is used as a heat ray shielding agent. If the coverage of mica by titanium oxide in the titanium oxide-coated mica is low, the heat ray shielding property from sunlight is insufficient, and if it is high, the transparency of the heat-shielding agricultural film is reduced, or the catalyst possessed by titanium oxide Since the weather resistance of the heat-shielding agricultural film is lowered by the activity, it is limited to 35 to 70% and preferably 45 to 60%. The method for producing the titanium oxide-coated mica is not particularly limited, and examples thereof include a method in which titanium hydroxide is coated on the surface of mica by hydrolysis of titanium tetrachloride and further sintered to crystallize titanium oxide. It is done.

  The coverage of titanium oxide on the surface of mica represents the weight ratio of titanium oxide in terms of titanium dioxide in the mica whose surface is coated with titanium oxide.

  If the 10% particle size of the titanium oxide-coated mica is small, the effect of shielding heat rays from sunlight is reduced, so it is limited to 3 μm or more, and preferably 5 μm or more. Further, if the 90% particle diameter of the titanium oxide-coated mica is large, the transparency of the heat-shielding agricultural film is lowered or the strength is lowered. Therefore, it is limited to 80 μm or less, and preferably 65 μm or less.

  In addition, the 10% particle diameter and 90% particle diameter of the titanium oxide-coated mica are those measured in the following manner. First, the particle size distribution of the titanium oxide-coated mica to be measured is measured by a laser diffraction method. In the particle size distribution on the basis of the weight of the obtained titanium oxide-coated mica, the particle diameter accumulated by 10% is oxidized from the titanium oxide-coated mica having the smallest particle diameter toward the titanium oxide-coated mica having the largest particle diameter. The 10% particle diameter of the titanium-coated mica is 90%, and the 90% cumulative particle diameter is the 90% particle diameter of the titanium oxide-coated mica.

  Examples of the titanium oxide-coated mica are commercially available from Merck Co., Ltd. under the trade names “Iriodin 123”, “Iriodin 221”, “Solarflair 870”, “Solarflair 875”, and the like.

  If the content of titanium oxide-coated mica in the heat-shielding agricultural film is small, the effect of shielding the heat rays from sunlight will be reduced, while if it is large, the transparency of the heat-shielding agricultural film will be reduced. It is limited to 0.1 to 10 parts by weight with respect to 100 parts by weight of the thermoplastic resin constituting the agricultural film, and preferably 0.5 to 5 parts by weight.

  To the above heat-shielding agricultural film, an inorganic heat insulating agent, an organic heat insulating agent, a light stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a pigment, and the like are added as necessary within the range not impairing the effects of the present invention. May be.

  The inorganic heat-retaining agent is added for the two purposes of improving the heat-retaining property of the heat-shielding agricultural film and preventing extrusion fluctuations during film formation. Examples of the inorganic heat insulating agent include 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, and a composite having at least two elements selected from alkali metals, alkaline earth metals, transition metals, group 2B elements, group 4B elements over silicon A hydroxide etc. are mentioned, These may be used independently or 2 or more types may be used together.

  Conventionally known light stabilizers can be used as the light stabilizer. Among these, hindered amine light stabilizers are preferable. 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]} These may be used, and these may be used alone or in combination of two or more.

  As the antioxidant, conventionally known ones can be used, but those having an effect as a heat stabilizer are preferable. Examples of such antioxidants include chelators such as metal salts of carboxylic acids, phenolic antioxidants, and organic phosphites, and these may be used alone or in combination of two or more. .

  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′-dihydroxy Benzophenone ultraviolet absorbers such as -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 ′, 5 -Di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) -5-chlorobenzotriazole and other benzotriazole ultraviolet absorbers , Salicylic acid ester ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, and the like. These may be used alone or in combination of two or more.

  The heat-insulating agricultural film may be a single layer, but may be a multilayer heat-insulating agricultural film that has better film strength and anti-blocking properties than a single-layer heat-insulating agricultural film. It is preferable that a thermoplastic resin film is laminated and integrated on at least one surface of the film, and more preferably, a thermoplastic resin film is laminated and integrated on both surfaces of the heat-shielding agricultural film.

  Examples of the thermoplastic resin used in the thermoplastic resin film include linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer. Polyolefin resins such as polyethylene resins such as coalescence, propylene resins such as homopolypropylene, propylene-α-olefin copolymers, propylene-vinyl acetate copolymers; polyvinyl chloride resins; polyester resins; polymethyl methacrylate Resin, polycarbonate resin, and the like. These may be used alone or in combination of two or more. Among the thermoplastic resins used for these thermoplastic resin films, linear low-density polyethylene and low-density polyethylene are preferable from the viewpoint that the heat-shielding agricultural film is excellent in film strength and antiblocking properties.

  As a method for forming the heat-shielding agricultural film, a conventionally known method may be employed. When the heat-shielding agricultural film is a single layer, for example, an inflation method, a T-die extrusion method, a calendar method, and the like may be mentioned. In the case where the heat-insulating agricultural film is a multilayer, for example, by forming a film for forming each layer by the above method and then stacking and integrating a plurality of films, a T-die extrusion method or an inflation method Examples include a multilayer extrusion method, and a multilayer extrusion method by an inflation method is preferable.

  If the thickness of the heat-shielding agricultural film is thin, the mechanical strength and the heat-shielding effect of the heat-shielding agricultural film may be reduced. On the other hand, if the thickness is thick, the heat-shielding agricultural film is cut, bonded, stretched, etc. 20 to 200 μm is preferable, and 50 to 150 μm is more preferable. In addition, when the thermoplastic resin film is laminated and integrated on one surface or both surfaces of the heat-shielding agricultural film, the thickness of the heat-shielding agricultural film refers to the thickness including the thermoplastic resin film.

  On one surface of the heat-shielding agricultural film, an antifogging droplet layer is formed by applying and drying an antifogging droplet agent. In addition, when a thermoplastic resin film is laminated and integrated on at least one surface of the heat-shielding agricultural film, an anti-fogging droplet layer is formed on the surface of either the heat-shielding agricultural film or the thermoplastic resin film. The

  This anti-fogging drop is composed of chain silica colloidal particles 0.1 to 0.1 in which silica colloidal particles having a particle size of 5 to 40 nm are bonded in a chain shape with a length of 40 to 300 nm in 100 parts by weight of an aqueous medium. 20 parts by weight and 0.1 to 10 parts by weight of polyethylene oxide having a viscosity average molecular weight of 5 to 1,500,000 are dispersed, and the pH is 7 to 12.

  The aqueous medium used for the anti-fogging droplet is not particularly limited as long as it can disperse the chain silica colloidal particles and polyethylene oxide. For example, a mixed medium of water and a water-soluble solvent, water, etc. Is mentioned.

  Examples of the water-soluble medium include alcohols such as ethyl alcohol, methyl alcohol, and propyl alcohol. If the amount of the water-soluble medium in the mixed medium increases, there is a risk of ignition in the drying process after the antifogging drop agent is applied to the thermoplastic resin film. Is preferred.

  The chain silica colloidal particles used in the antifogging droplets are those in which a plurality of silica colloid particles are linked in a chain, and the silica colloid particles at both ends are not bound to each other. Even though it may be branched in the middle, it is preferably linear.

  And if the particle size of the silica colloidal particles is small, it becomes difficult to produce the chain silica colloidal particles, or the antifogging property of the antifogging droplet is lowered, and if it is large, it is obtained from the antifogging droplet. Since the adhesiveness of a coating film and a thermoplastic resin film falls, it is limited to 5-40 nm, 10-30 nm is preferable and 18-25 nm is more preferable. The particle size of the silica colloidal particles is measured by the dynamic light diffusion method. This dynamic light diffusion method detects the Brownian motion of the colloidal particles in the solution by the light diffusion method. This is a method of calculating the particle size of the slag.

  If the length of the chain silica colloidal particles is short, the antifogging property of the antifogging drop agent is lowered. If the length is long, it becomes difficult to produce the chain silica colloidal particles. 100 to 200 nm is preferable.

  The binding state of the chain silica colloid particles can be confirmed using a scanning electron microscope (SEM), and the length of the chain silica colloid particles is the length of the chain silica colloid particles observed with the scanning electron microscope. Is measured by dividing by the magnification. When the chain silica colloidal particles have a branched structure, the length of the chain silica colloidal particles refers to the length of the longest chain portion.

  And, if the content of the chain silica colloid particles in the anti-fogging drop is small, not only does the anti-fogging property of the anti-fogging drop drop, but it becomes difficult to form a water film on the film surface. In addition, the heat insulation effect due to the water film is reduced, the heat retention performance is also lowered, and if it is large, the storage stability of the antifogging drop is lowered, so it is limited to 0.1 to 20 parts by weight with respect to 100 parts by weight of the aqueous medium. 2 to 10 parts by weight is preferred.

In addition, if the viscosity average molecular weight of polyethylene oxide used for the antifogging drop agent is low, not only the coating property of the antifogging drop agent is lowered but also the film surface cannot be uniformly applied. Water film formation becomes difficult, the heat insulation effect by the water film decreases, the heat retention performance also decreases, and if it is high, the viscosity of the antifogging drop increases excessively and the antifogging drop of uniform thickness on the film surface The formation of the layer becomes difficult, the formation of a water film on the film surface becomes difficult, and the heat retaining performance is also lowered, so that the layer is limited to 50,000 to 1,500,000, and preferably 100,000 to 1,000,000. The viscosity average molecular weight Mv of polyethylene oxide is E. Bailey Jr. et al. , J .; Polym. Sci. , 32, 517 (1958), and calculated from the intrinsic viscosity [η] measured at 30 ° C. for an aqueous polyethylene oxide solution.
[Η] = 1.25 × 10 ⁻⁴ × Mv ^0.78

  If the content of polyethylene oxide in the anti-fogging drop is low, the storage stability and coating properties of the anti-fogging drop will be reduced, and if it is high, the viscosity of the anti-fogging drop will be increased. Therefore, the amount is limited to 0.1 to 10 parts by weight with respect to 100 parts by weight of the aqueous medium, and preferably 1 to 5 parts by weight.

  In addition, if the weight ratio of the chain silica colloid particles to the amount of polyethylene oxide (chain silica colloid particles / polyethylene oxide) in the antifogging drop agent is small, the antifogging drop property is lowered. If it is large, the adhesion between the heat-shielding agricultural film and the chain silica colloidal particles will be reduced, or the scratch resistance of the coating film obtained from the antifogging drop agent will be reduced. preferable.

  Further, when the pH of the antifogging droplet is low, the storage stability of the antifogging droplet is lowered, while when high, the chain silica colloidal particles are dissolved in an aqueous solvent and the antifogging droplet is dissolved. Since antifogging property falls, it is limited to 7-12, and 8-11 are preferable.

  It should be noted that additives such as a viscosity modifier, a surfactant, an antifoaming agent, and a crosslinking agent may be added to the antifogging drop of the present invention as long as the physical properties are not impaired.

  Next, the manufacturing method of the said anti-fogging drop agent is demonstrated. The method for producing the antifogging drop is not particularly limited, and a colloidal solution in which chain silica colloidal particles are dispersed in an aqueous medium and polyethylene oxide are added to the aqueous medium, and various methods can be used as necessary. And a method in which the aqueous medium is stirred using a general-purpose stirring device such as a homogenizer. A colloidal solution in which chain silica colloidal particles are dispersed in an aqueous medium is commercially available from Nissan Chemical Industries under the trade names “ST-PSM”, “ST-PSS”, and the like.

  The method for applying the anti-fogging drop onto one surface of the heat-shielding agricultural film is not particularly limited. For example, a roll coating method such as a gravure coater, a barcode method, a dip coating method, a spray method, a brushing method. The painting method etc. are mentioned.

  The anti-fogging droplet layer obtained by applying the anti-fogging droplet agent on one surface of the heat-shielding agricultural film as described above and drying it exhibits excellent anti-fogging droplet properties. Furthermore, since the antifogging droplet layer formed from the antifogging droplet agent has a high water film forming ability, a water film is formed on the antifogging droplet layer of the heat-shielding agricultural film. Plays the role of heat insulation layer. Therefore, when the heat-insulating agricultural film of the present invention is used as an outer covering of an agricultural house, the heat retaining effect of the agricultural house at night is particularly excellent.

  Since the heat-shielding agricultural film of the present invention has the above-described configuration, it has strength and weather resistance that can be used as an agricultural film, sufficiently transmits light from sunlight, and for a long period of time. The heat rays from sunlight can be sufficiently shielded, and the anti-fogging droplet layer is obtained by applying and drying the anti-fogging droplet agent, and the anti-fogging droplet property is maintained over a long period of time. It also has excellent heat retention due to the ability of the clouded droplet layer to form a water film.

  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.

(Anti-fog drop A)
Colloidal solution in which linear silica colloidal particles are dispersed in water (trade name “ST-PSM” manufactured by Nissan Chemical Industries, Ltd., silica colloidal particle size: 18 to 25 nm, length of linear silica colloidal particles 80: 120 nm, linear silica colloid particles: 20% by weight) and polyethylene oxide (trade name “PEO-1Z” manufactured by Sumitomo Seika Co., Ltd., viscosity average molecular weight: 275,000) are added, mixed and anti-fogged. A dripping agent was obtained. In addition, the anti-fogging drop was formed by dispersing 5 parts by weight of chain silica colloidal particles and 2 parts by weight of polyethylene oxide in 100 parts by weight of water. The pH of the anti-fogging drop was 10. The linear silica colloidal particles were obtained by linearly binding silica colloidal particles having a particle diameter of 18 to 25 nm to a length of 80 to 120 nm.

(Anti-fog drop B)
Colloidal solution in which linear silica colloidal particles are dispersed in water (trade name “ST-PSM” manufactured by Nissan Chemical Industries, Ltd., silica colloidal particle size: 18 to 25 nm, length of linear silica colloidal particles 80: 120 nm, linear silica colloidal particles: 20% by weight) and polyethylene oxide (trade name “PEO-3Z” manufactured by Sumitomo Seika Co., Ltd., viscosity average molecular weight: 850,000) are added and mixed to form anti-fogging droplets. An agent was obtained. In addition, the anti-fogging drop was formed by dispersing 5 parts by weight of chain silica colloidal particles and 2 parts by weight of polyethylene oxide in 100 parts by weight of water. The pH of the anti-fogging drop was 10. The linear silica colloidal particles were obtained by linearly binding silica colloidal particles having a particle diameter of 18 to 25 nm to a length of 80 to 120 nm.

(Anti-fog drop C)
Colloidal solution in which linear silica colloidal particles are dispersed in water (trade name “ST-PSM” manufactured by Nissan Chemical Industries, Ltd., silica colloidal particle size: 18 to 25 nm, length of linear silica colloidal particles 80: 120 nm, linear silica colloidal particles: 20% by weight) and polyethylene oxide (trade name “PEO-8Z” manufactured by Sumitomo Seika Co., Ltd., viscosity average molecular weight: 19.95 million) are added and mixed to form anti-fogging droplets. An agent was obtained. In addition, the anti-fogging drop was formed by dispersing 5 parts by weight of chain silica colloidal particles and 2 parts by weight of polyethylene oxide in 100 parts by weight of water. The pH of the anti-fogging drop was 10. The linear silica colloidal particles were obtained by linearly binding silica colloidal particles having a particle diameter of 18 to 25 nm to a length of 80 to 120 nm.

(Anti-fog drop D)
Colloidal solution in which spherical silica colloidal particles are dispersed in water (trade name “ST-20” manufactured by Nissan Chemical Industries, particle size: 80 to 120 nm, spherical silica colloidal particles: 20% by weight) and polyethylene oxide ( Sumitomo Seika Co., Ltd. product name "PEO-1Z", viscosity average molecular weight: 275,000) was added and mixed to obtain an antifogging drop. In addition, the anti-fogging drop was formed by dispersing 5 parts by weight of spherical silica colloid particles and 2 parts by weight of polyethylene oxide in 100 parts by weight of water. The pH of the anti-fogging drop was 10.

Example 1
For the layer (A) constitution, 70 parts by weight of linear low density polyethylene (density: 0.915 g / cm ³ , melt mass flow rate: 1.5 g / 10 min) and low density polyethylene (density: 0.922 g / cm) ^3. Melt flow rate: 0.4 g / 10 min) 30 parts by weight in the first extruder, 100 parts by weight of ethylene-vinyl acetate copolymer (density: 0.938 g / cm ³⁾ Melt mass flow rate: 1.0 g / 10 min, vinyl acetate content: 20% by weight) and titanium oxide-coated mica A (trade name “Solarflair 870” manufactured by Merck & Co., Inc.), 10% particle size: 5 μm, 90% particle size: Linear low density polyethylene (density: 0.915 g / c) for forming layer (C) using 5 parts by weight of 60 μm, mica coverage with titanium oxide: 45% as a second extruder. ^3, melt mass flow rate: 1.5 g / 10 min) 70 parts by weight low-density polyethylene (density: 0.922 g / cm ^3, melt flow rate: 0.4 g / 10 min) 30 parts by weight of a third extruder After supplying and melt-kneading each, three layers are formed from the first to third extruders by an inflation method so that the thickness ratio of layer (A), layer (B) and layer (C) is 2: 6: 2. Co-extrusion molding was performed to obtain a heat-shielding agricultural film having a total thickness of 150 μm, in which layers (A), (B), and (C) were laminated and integrated into three layers in this order. The melt mass flow rate is a value measured under conditions of a temperature of 190 ° C. and a load of 21.18 N in accordance with JIS K7210. Next, an anti-fogging drop A is applied to the surface (C) of the above heat-shielding agricultural film with a gravure coater so that the coating amount after drying is 10 g / cm ² , and dried with hot air to prevent anti-fogging. A droplet layer was formed.

(Example 2)
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the anti-fogging drop B was used in place of the anti-fogging drop A.

Example 3
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the amount of titanium oxide-coated mica A supplied to the second extruder was 8 parts by weight instead of 5 parts by weight.

Example 4
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the amount of titanium oxide-coated mica A supplied to the second extruder was 0.5 parts by weight instead of 5 parts by weight.

(Example 5)
Instead of titanium oxide-coated mica A, titanium oxide-coated mica B having a 10% particle diameter of 5 μm and a 90% particle diameter of 25 μm and a coverage of mica by titanium oxide of 50% (made by Merck & Co., Inc.) A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that “Solarflair 875”) was used.

(Example 6)
Instead of titanium oxide-coated mica A, titanium oxide-coated mica C (made by Merck Co., Ltd.) having a 10% particle diameter of 5 μm and a 90% particle diameter of 25 μm and a mica coverage of 39% with titanium oxide A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that “Iriodin 123”) was used.

(Comparative Example 1)
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the antifogging droplet C was used in place of the antifogging droplet A.

(Comparative Example 2)
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the antifogging drip agent D was used in place of the antifogging drip agent A.

(Comparative Example 3)
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the amount of titanium oxide-coated mica A supplied to the second extruder was 15 parts by weight instead of 5 parts by weight.

(Comparative Example 4)
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the amount of titanium oxide-coated mica A supplied to the second extruder was 0.05 parts by weight instead of 5 parts by weight.

(Comparative Example 5)
Instead of titanium oxide-coated mica A, titanium oxide-coated mica D having a 10% particle diameter of 10 μm and a 90% particle diameter of 125 μm and a mica coverage of titanium oxide of 36% (made by Merck & Co., Inc.) A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that “Iriodin 299”) was used.

(Comparative Example 6)
Instead of titanium oxide-coated mica A, titanium oxide-coated mica E (made by Merck & Co., Inc.) having a 10% particle diameter of 10 μm and a 90% particle diameter of 60 μm and a mica coverage of titanium oxide of 30% A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that “Iriodin 103”) was used.

(Comparative Example 7)
Further supplying 10 parts by weight of diglycerin stearate (trade name “S71-D”, manufactured by Riken Vitamin Co., Ltd.) as a nonionic surfactant to the second extruder and the third extruder, anti-fogging drop A A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that was not applied to one surface of the heat-shielding agricultural film.

(Comparative Example 8)
A heat-shielding agricultural film was obtained in the same manner as in Example 1 except that the titanium oxide-coated mica A was not supplied to the second extruder.

(Total light transmittance)
The total light transmittance at 550 nm of the obtained heat-shielding agricultural film was measured using a turbidimeter (trade name “NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd.).

(Heat insulation and heat retention at night)
A heat-shielding agricultural film was spread on a sealed pipe house (length 1.5 m x width 1 m x depth 2.5 m), and the ground temperature and temperature during the summer (August) were measured. The soil temperature was measured using a thermocouple for soil temperatures of 10 cm in the soil at the center of the pipe house and outside the pipe house. The temperature was measured inside and outside the pipe house at 2 pm on a clear day. Based on these ground temperature and temperature, the ground temperature difference and the temperature difference were calculated based on the following formula.
Ground temperature difference (℃) = (Soil temperature at the center of the pipe house)-(Soil temperature outside the pipe house)
Temperature difference (℃) = (temperature inside the pipe house)-(temperature outside the pipe house)

Furthermore, using the same house, the nighttime temperature and temperature in winter (February) were measured in the same manner as described above. However, the temperature was measured inside and outside the pipe house at 4 am. Based on these ground temperature and temperature, the ground temperature difference and the temperature difference were calculated based on the following formula.
Ground temperature difference (℃) = (Soil temperature at the center of the pipe house)-(Soil temperature outside the pipe house)
Temperature difference (℃) = (temperature inside the pipe house)-(temperature outside the pipe house)

(Anti-fogging drip property)
A heat-shielding agricultural film is placed on the top of the water tank so that the layer (C) is on the water tank side, and the air temperature is kept at 15 ° C. and the water temperature at 23 ° C. for 1 hour. The state of water droplets formed on the surface of the agricultural film was visually observed, and the antifogging flowability was evaluated according to the following criteria. In addition, the distance of the water surface in a water tank and the heat-shielding agricultural film was 30 cm.

The first measurement result is evaluated as the initial antifogging drip property, and the above measurement is repeated 200 times after drying the heat-shielding agricultural film every time the measurement is completed, and the 200th measurement is completed. Then, the antifogging flowability was evaluated as antifogging durability.
○: A water film quickly formed.
(Triangle | delta): It grew to the water film, after the minute water droplet adhered.
X: A minute water droplet was formed for a long time (60 minutes or more).

(Tape peelability of anti-fogging droplet layer)
Adhesive tape is attached on the anti-fogging drip layer of the heat-shielding agricultural film, and the peeling state of the anti-fogging drip layer of the heat-shielding agricultural film after peeling off the adhesive tape is visually observed to the following standards. Based on the evaluation.
○: The antifogging droplet layer did not peel off.
Δ: A part of the anti-fogging droplet layer was peeled off.
X: The anti-fogging droplet layer was peeled off entirely.

Claims (2)

A heat-shielding agricultural film containing 100 parts by weight of a thermoplastic resin and 0.1 to 10 parts by weight of mica whose surface is coated with titanium oxide, the mica whose surface is coated with titanium oxide, The 10% particle diameter is 3 μm or more and the 90% particle diameter is 80 μm or less, and the coverage of mica by titanium oxide is 35 to 70%. Further, the particle diameter is 5 to 40 nm in 100 parts by weight of the aqueous medium. 0.1 to 20 parts by weight of chain silica colloidal particles obtained by bonding the silica colloidal particles in a chain shape with a length of 40 to 300 nm, and 0.1 to 10 parts of polyethylene oxide having a viscosity average molecular weight of 50,000 to 1,500,000. An anti-fogging droplet layer formed by applying and drying an anti-fogging droplet agent having a pH of 7 to 12 on one surface of the heat-shielding agricultural film is formed. Shielding features Thermal agricultural film. The heat-insulating agricultural film according to claim 1, wherein the thermoplastic resin is a polyolefin resin.