JPWO2017204191A1 - Fluorine resin film for agriculture and coating material for agriculture - Google Patents

Abstract

Provided is an agricultural fluororesin film that is highly transparent and has excellent UV-blocking sustainability as compared with a conventional fluororesin film containing an inorganic UV absorber, and a coating material using the same. .
Provided with a fluorine resin film containing fluorine resin and titanium oxide particles,
The titanium oxide particles are particles having an average aspect ratio of 1.2 or more and an average length in the longitudinal direction of 550 nm or less. The titanium oxide particles have a multilayer coating layer on the titanium oxide, and the multilayer coating The layer includes at least a zirconium oxide coating layer, an aluminum hydroxide coating layer, and an organopolysiloxane coating layer, and the film thickness of the multilayer coating layer is 2 nm to 7 nm.

Description

  The present invention relates to a fluorine-based resin film and an agricultural coating material excellent in ultraviolet blocking durability while maintaining high transparency.

  Conventionally, a fluorine-based resin film is excellent in weather resistance and antifouling properties, and thus has been used for outdoor use in green houses. However, the fluororesin film has a high light transmittance, so the materials in the house may deteriorate due to the ultraviolet rays, and crop burning may occur. Depending on the usage environment, the light transmittance in the ultraviolet region is suppressed. Technology is required.

Conventional technology

  Conventionally, as a technique for imparting ultraviolet blocking performance to a fluorine resin film, for example, Patent Document 1 discloses a fluorine resin film containing rutile titanium oxide particles having an average particle diameter of 0.01 to 0.05 μm. The particles are coated with titanium oxide, aluminum oxide, and organopolysiloxane in sequence on the surface of titanium oxide, and contain 0.05 to 2.0% by weight of the particles. Resin films have been proposed.

  Patent Document 2 states that in the amorphous-cerium oxide composite particles, the amorphous silica-cerium oxide composite particles containing 95% by weight or more of particles having a particle size of 1 to 30 μm are dispersed in the fluororesin. A characteristic fluorine-based resin film has been proposed.

  Patent Document 3 discloses a fluororesin film containing zinc oxide particles having an average particle diameter of 0.01 to 0.05 μm, and the particles have a coating layer made of silicon oxide on the surface of zinc oxide. A fluororesin film characterized by containing 0.05 to 2.0 parts by mass of the particles with respect to 100 parts by mass of the fluororesin has been proposed.

JP 2011-157492 A JP-A-10-287784 JP 2010-143948 A

  However, when titanium oxide having an average particle size and a relatively small particle size as disclosed in Patent Document 1 is used, the transparency is good, but since the specific surface area is large and aggregation is likely to occur, it is sufficiently covered. There is a problem that cannot be done.

  In addition, in the case of Patent Document 2 using composite particles containing cerium oxide, the refractive index is low and transparency is high compared to titanium oxide. There is a need to increase it, resulting in a loss of transparency. There is also a problem that the cost is relatively increased.

  In the case of Patent Document 3 using zinc oxide, the transparency is better than that of titanium oxide, but zinc oxide is easily transformed into zinc fluoride by reacting with a small amount of a fluorine compound. This causes the problem of low UV blocking durability.

  The present invention has been made in view of the above circumstances. Compared to a conventional fluorine-based resin film containing an inorganic ultraviolet absorber, the present invention has high transparency and is excellent in ultraviolet blocking durability. The purpose is to provide covering materials.

  According to some embodiments of the present invention, a fluororesin film containing a fluororesin and titanium oxide particles is provided, and the titanium oxide particles have an average aspect ratio of 1.2 or more and an average length in the longitudinal direction. The titanium oxide particles have a multilayer coating layer on titanium oxide, and the multilayer coating layer includes at least a zirconium oxide coating layer, an aluminum hydroxide coating layer, and an organopolysiloxane coating layer. There is provided an agricultural fluororesin film in which the thickness of the multilayer coating layer is 2 nm to 7 nm.

  The inventors of the present invention have intensively studied the development of a fluorine-based resin film having excellent ultraviolet blocking durability while maintaining transparency in use in a green house, and the average aspect ratio is not less than a specific value. When the titanium oxide particles having a coating layer of the above were used, it was found that they were excellent in transparency and UV blocking durability, and the present invention was completed.

  Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.

Preferably, in the multilayer coating layer, a zirconium oxide coating layer, an aluminum hydroxide coating layer, and an organopolysiloxane coating layer are formed in this order from the inside.
Preferably, the titanium oxide particles are contained in an amount of 0.03 to 1.0 parts by mass with respect to 100 parts by mass of the fluororesin.
Preferably, a droplet layer having hydrophilic performance is provided on at least one surface.
Preferably, the fluororesin is a random copolymer containing 80 to 90% by mass of monomer units based on vinylidene fluoride and 10 to 20% by mass of monomer units based on hexafluoropropylene. Become.

  According to another aspect, an agricultural covering material using the above-described agricultural fluororesin film is provided.

  The agricultural fluororesin film of the present invention is a film that can be used as a covering material for a greenhouse, and is superior in transparency and UV blocking durability as compared with conventional fluororesin films.

The agricultural fluororesin film of the present invention comprises a fluororesin film containing a fluororesin and titanium oxide particles, and the titanium oxide particles have an average aspect ratio of 1.2 or more and an average length in the longitudinal direction. The titanium oxide particles have a multilayer coating layer on titanium oxide, and the multilayer coating layer includes at least a zirconium oxide coating layer, an aluminum hydroxide coating layer, and an organopolysiloxane coating layer. The film thickness of the multilayer coating layer is 2 nm to 7 nm.
Hereinafter, embodiments of the present invention will be described in detail.

<Titanium oxide particles>
In the embodiment of the present invention, there are provided an agricultural fluororesin film and an agricultural covering material excellent in transparency and UV blocking durability because the titanium oxide particles have a specific shape and size.

  When the particle size of the titanium oxide particles is reduced, the transparency is excellent. On the other hand, the titanium oxide particles are highly cohesive, and it is difficult to sufficiently cover the aggregated titanium oxide particles. In the case where the coating cannot be performed sufficiently, titanium oxide generates active species and alters the film (photocatalytic action), so that the transparency is lowered. That is, a problem occurs in weather resistance. Further, when the size is increased, the cohesiveness is lowered, but the titanium oxide particles scatter light, and high transparency cannot be expected.

  On the other hand, in the present invention, since the average aspect ratio of the titanium oxide particles is a specific value or more, even if the particle size of the titanium oxide particles is made small enough to ensure transparency, the aggregation of the particle surface is difficult to occur. Is good. In other words, transparency and weather resistance, which are difficult to satisfy at the same time only by changing the particle size (size), change not only the particle size but also the shape (aspect ratio: ratio of length to width, length / width). Successfully fulfilled at the same time.

  The average aspect ratio of the titanium oxide particles used in the embodiment of the present invention is 1.2 or more, preferably 1.5 or more, and more preferably 2 or more. If the average aspect ratio is less than 1.2, the cohesiveness is high and the coating property is not good, so that the activity cannot be suppressed and the weather resistance is poor. Moreover, in order to have high transparency, since a certain width is required, the average aspect ratio is preferably 6 or less, and more preferably 5 or less.

  The average length of the titanium oxide particles in the longitudinal direction is 550 nm or less, preferably 400 nm or less, and more preferably 350 nm or less. Although there is no restriction | limiting in particular about the minimum of the average length of the longitudinal direction of a titanium oxide particle, since it is difficult to control the average aspect-ratio of a titanium oxide particle if it is too small, 60 nm or more is preferable and 90 nm or more is more preferable.

  The shape (average aspect ratio, average length, etc.) of the titanium oxide particles can be measured, for example, by observation with an electron microscope (SEM or TEM). Specifically, for example, using a transmission electron microscope (TEM), 100 or more particles are randomly selected from one or more electron microscope images captured with an applied voltage of 200 kV, and the length of each particle is selected. Measure the length in the short direction. And let the arithmetic average value of the length of a longitudinal direction and a transversal direction be an average length of a longitudinal direction and a transversal direction. A value obtained by dividing the average length in the longitudinal direction by the average length in the short direction is defined as an average aspect ratio.

  As the titanium oxide particles having the above average aspect ratio, for example, plate-like or rod-like particles can be used. The plate shape only needs to have a length (long side) larger than a width (short side), and is not necessarily a complete plane. The rod shape is a structure having a length (long side) larger than a width (short side), and most of the surface is a curved surface. However, the surface does not necessarily need to be a complete curved surface, and a part of the surface may be included. However, a tube-like one is not preferable because the coating cannot be performed sufficiently.

  The production method of the titanium oxide particles is not particularly limited. For example, the method of neutralizing titanyl sulfate with an alkali, the method of burning titanium chloride, or converting the titanium titanium into titanium oxide by a sol-gel method. Methods and the like.

  The titanium oxide particles have a coating layer on titanium oxide serving as a core (core), and the coating layer is a multilayer coating layer forming a multilayer structure. The multilayer coating layer includes at least a zirconium oxide coating layer, an aluminum hydroxide coating layer, and an organopolysiloxane coating layer.

  By providing a zirconium oxide coating layer, an aluminum hydroxide coating layer, and an organopolysiloxane coating layer as the coating layer of titanium oxide particles, discoloration, decomposition and photocatalysis of titanium oxide due to ultraviolet rays are suppressed, and the fluororesin film Discoloration and deterioration of mechanical properties are maintained stably for a long time.

The method of coating the titanium oxide particles by coating with zirconium oxide is not particularly limited. For example, there is a method of preparing an aqueous suspension of titanium oxide particles, adding an aqueous solution of zirconium sulfate to this and neutralizing with an alkali to coat the titanium oxide particles. Can be mentioned. The coating amount of zirconium oxide is 10 to 22 parts by mass, preferably 12 to 16 parts by mass as ZrO _{2 with} respect to 100 parts by mass of titanium oxide as a nucleus. If the coating amount of the zirconium oxide coating amount is 22 parts by mass or more, the amount of adsorbed moisture increases, and problems such as foaming during film production occur. In addition, when the amount is less than 10 parts by mass, the photocatalytic action is not preferable because it is weak.

  The method for coating the titanium oxide particles with the aluminum hydroxide coating is not particularly limited. For example, an aqueous suspension of titanium oxide particles is prepared, and an aqueous solution of a water-soluble compound of aluminum hydroxide is added thereto. Examples include a method of adding an alkali as a neutralizing agent to neutralize an aluminum compound to form an aluminum hydroxide coating layer. Examples of the water-soluble compound of aluminum include aluminum nitrate, aluminum sulfate, and sodium aluminate. As the acid that is a neutralizing agent, inorganic acids such as sulfuric acid and organic acids such as acetic acid and oxalic acid are preferably used.

  The coating amount of the aluminum hydroxide coating layer is 15 to 30 parts by mass, preferably 15 to 20 parts by mass as aluminum hydroxide with respect to 100 parts by mass of titanium oxide as a nucleus. If the coating amount of aluminum hydroxide is less than 15 parts by mass, the suppression of the photocatalytic action is insufficient and the resin is deteriorated, which is not preferable. Moreover, when more than 30 mass parts, the increase of the aluminum hydroxide aggregate and the cohesion force of fillers increase, and it is unpreferable since transparency of a film is impaired.

  The method of coating the titanium oxide particles with the organopolysiloxane coating is not particularly limited. For example, a solution containing an organopolysiloxane added with alkali and titanium oxide particles are mixed with a stirrer or the like, and the surface of the titanium oxide particles is coated. The method of coating with organopolysiloxane is mentioned.

  The coating amount of the organopolysiloxane coating layer is 1 to 20 parts by mass, preferably 3 to 10 parts by mass with respect to 100 parts by mass of titanium oxide as a nucleus. As the organopolysiloxane, for example, dimethylpolysiloxane, methylhydrogenpolysiloxane, methicone-dimethicone copolymer and the like are preferably used. When such an organopolysiloxane is less than 1 part by mass with respect to 100 parts by mass of titanium oxide, the effect of improving the dispersibility in the resin is poor. On the other hand, when it is more than 20 parts by mass, the filler is aggregated. The problem of poor transparency may occur. Further, the silane coupling agent may be coated before coating with the organopolysiloxane, whereby the organopolysiloxane can be coated more uniformly.

  In the multiple coating layer, the order of formation of each coating layer is not particularly limited, but from the viewpoint of ease of production, zirconium oxide coating layer, aluminum hydroxide coating layer from the inner side close to the core titanium oxide, The order of the organopolysiloxane coating layer is preferred. That is, in one embodiment of the present invention, a zirconium oxide coating layer is formed on the surface of the titanium oxide particles, and then an aluminum hydroxide coating layer is formed on the surface of the titanium oxide particles having the zirconium oxide coating layer. It is preferable to form an organopolysiloxane coating layer on the surface of the titanium oxide particles having a layer and an aluminum hydroxide coating layer. Moreover, the stability of the particles may be improved by coating the outermost surface with an organopolysiloxane coating layer.

  In addition, you may provide another layer in the range which does not impair transparency and a weather resistance between titanium oxide and a coating layer, between each coating layer, or the outermost surface. For example, it can be surface-treated with a higher fatty acid such as stearic acid, a higher fatty acid ester such as octyl palmitate, a polyhydric alcohol such as trimethylolethane, trimethylolpropane and pentaerythritol, and an amine compound such as diethanolamine and triethanolamine. .

  The film thickness of the multilayer coating layer is 2 nm to 7 nm, preferably 3 nm to 6 nm. When the film thickness is less than 2 nm, the coating is not sufficient and the photocatalytic action is not sufficiently suppressed, which is not preferable. When the film thickness exceeds 7 nm, the transparency is inferior, which is not preferable.

  The thickness of the multilayer coating layer of titanium oxide particles was determined by embedding the titanium oxide particles in an epoxy resin, preparing a section with a microtome, and using a scanning transmission electron microscope HD-2700 (manufactured by Hitachi High-Technologies Corporation). The average film thickness of the multilayer coating layer is measured based on the photographed image.

  The content of the titanium oxide particles in the fluororesin film of the present invention is not particularly limited as long as it has ultraviolet blocking performance. For example, the titanium oxide particles are 0.03 to 100 parts by mass of the fluororesin. It is preferable that 1.0 mass part is contained, and it is more preferable that 0.05-0.5 mass part is contained. When the content of the titanium oxide particles is more than 1.0 parts by mass, the transparency is inferior, and streaks and foreign matters are generated during production of the film, resulting in inferior handling properties. On the other hand, when the amount is less than 0.03 parts by mass, it is not preferable because the ultraviolet blocking ability that reaches the requirement cannot be provided.

  The agricultural fluororesin film preferably has an ultraviolet transmittance at a wavelength of 300 nm as an ultraviolet blocking performance of an initial value of 70% or less, more preferably 60% or less, and even more preferably 55% or less. preferable. Further, the value after the weather resistance test of the transmittance of ultraviolet light having a wavelength of 300 nm is preferably 60% or less, more preferably 55% or less, and further preferably 50% or less.

  The agricultural fluororesin film preferably has an initial value of total light transmittance of 90% or more as transparency, and more preferably 93% or more. Moreover, it is preferable that the value after a weather resistance test of a total light transmittance is 90% or more, and it is more preferable that it is 93% or more.

  The agricultural fluororesin film preferably has an initial value of HAZE of 20% or less as transparency, more preferably 15% or less, and further preferably 12% or less. Further, the value of HAZE after the weather resistance test is preferably 20% or less, more preferably 15% or less, and further preferably 12% or less.

<Fluorine resin>
According to one embodiment of the present invention, the fluororesin contained in the agricultural fluororesin film comprises 80 to 90% by mass of monomer units based on vinylidene fluoride and 10 to 10 monomer units based on hexafluoropropylene. It is preferably made of a random copolymer contained in a proportion of 20% by mass.
When the proportion of monomer units based on hexafluoropropylene is lower than 10% by mass and the proportion of monomer units based on vinylidene fluoride is higher than 90% by mass, the resulting elastic modulus of the fluororesin film is increased, The workability is poor and the film tends to wrinkle. Further, when the proportion of monomer units based on hexafluoropropylene is higher than 20% by mass and the proportion of monomer units based on vinylidene fluoride is lower than 80% by mass, the resulting fluororesin film has low tensile strength, and typhoon There is a risk of film tearing during natural disasters such as.
More preferably, the proportion of monomer units based on hexafluoropropylene is 15% by mass or more, and the proportion of monomer units based on vinylidene fluoride is 85% by mass or less. With such a ratio, the stretch workability is further improved while maintaining the tensile strength.

  The random copolymer as used in the present specification is a copolymer in which the main constitution of the copolymer is not constituted by block copolymerization, and there may be a portion in which the same constitutional unit is continued in part. Although it may include graft copolymerization or alternating copolymerization, it is a copolymer mainly composed of random copolymerization. The block copolymer has a high dynamic elastic modulus, the desired flexibility performance cannot be obtained, and there is a concern that the physical properties are reduced due to crystallization.

  As a polymerization method of the copolymer to be used, it can be prepared by performing a conventionally known polymerization method such as suspension polymerization or emulsion polymerization.

  The monomer unit of the random copolymer may contain other monomer units in addition to vinylidene fluoride and hexafluoropropylene as long as flexibility and mechanical strength are satisfied, but the monomer unit based on vinylidene fluoride It is preferable to contain the monomer unit based on 80 to 90% by mass and 10 to 20% by mass based on hexafluoropropylene. For example, tetrafluoroethylene may be included as another monomer unit, but when the above ratio is not satisfied, the tensile strength is reduced and the natural disaster resistance is reduced. More preferably, the copolymer does not contain tetrafluoroethylene as a monomer unit.

  The film thickness of the agricultural fluororesin film of the present invention is preferably 30 μm to 400 μm, more preferably 60 to 200 μm. If it is less than 30 μm, sufficient durability may not be obtained. If it exceeds 200 μm, it is disadvantageous in terms of cost, such as an increase in raw material costs, and the secondary workability in easiness of stretching and film cutting and joining may be reduced.

  The dynamic elastic modulus of the agricultural fluororesin film according to an embodiment of the present invention is not particularly limited as long as the stretching operation is possible, but is preferably 150 to 750 MPa, for example, 200 to 700 MPa. More preferably, it is 220-550 MPa. When the dynamic elastic modulus is smaller than 150 MPa, the film does not have a proper waist and is very difficult to stretch. When the tensile elastic modulus is larger than 750 MPa, the film may be hard and cannot be applied successfully when it is spread on a house.

<Flowing layer>
In one embodiment of the present invention, the agricultural fluororesin film preferably includes a droplet layer having hydrophilic performance on at least one surface. The droplet layer is formed by applying a colloidal layered silicate and a droplet agent containing a polymer binder, a light stabilizer or an organic ultraviolet absorber. The layered silicate is colloidal, and since the colloid is nanometer size, a transparent coating film can be formed. The droplet agent for forming the droplet layer is preferably transparent without becoming cloudy. The particle size of the layered silicate is usually 10 to 1000 nm, preferably 10 to 100 nm.

  The layered silicate is at least one selected from, for example, mica and smectite. Examples of mica include vermiculite. Examples of the smectite include montmorillonite, iron montmorillonite, beidellite, saponite, nontronite, hectorite, stevensite, and socosite. The layered silicate is preferably a synthetic layered silicate, particularly preferably a synthetic smectite.

  The polymer binder is not particularly limited as long as it is transparent when mixed with the above-mentioned layered silicate and can stably fix the droplet layer on the film, but is alcohol-soluble nylon resin, acrylic resin phenol resin Etc., and preferably an alcohol-soluble nylon resin. When these polymer binders are used, it is possible to form a droplet layer that is not easily peeled off even by friction by a stretching operation while ensuring transparency.

  The mixing ratio of the layered silicate and the polymer binder is not particularly limited as long as transparency and fixing stability are ensured, but the layered silicate is added in an amount of 2 to 60 masses per 100 mass parts of the polymer binder. It can be contained in an amount of preferably 5 to 20 parts by mass. When the amount is less than 2 parts by mass, the contact angle of water becomes high and the dropping property is low, and when it exceeds 60 parts by mass, the transparency is lowered.

  In order to provide weather resistance to the droplet layer, it is preferable to add a light stabilizer, and known ones can be used. As the light stabilizer, one that captures the active species at the start of photodegradation in the resin and prevents photooxidation can be used. Specifically, one or a combination of two or more selected from hindered amine compounds, hindered piperidine compounds, and the like can be used. Among these, it is preferable to use a hindered amine compound. These light stabilizers do not easily become emulsions and are excellent in coating film workability.

<Method for producing agricultural fluororesin film>
Next, the manufacturing method of the agricultural fluororesin film of this invention is demonstrated.

  First, an extrusion method is suitably employed as a method for producing an agricultural fluororesin film. As a specific method at that time, a method of forming a film using a T-type die or a method of forming a film using an inflation die is not particularly limited as an extrusion condition. Generally, a fluororesin film is used. The conditions used to form can be used. When using a T-shaped die, a metal cooling roll and a rubber roll are placed under the T-shaped die, and a film is produced while the molten resin extruded from the lip port of the T-shaped die is pinched between the rolls and cooled and solidified. Either a film forming method or a method of forming a film by cooling and solidifying only with a metal cooling roll without using a pinch roll can be employed.

  A droplet layer can be provided by applying a droplet agent to at least one surface of the fluororesin film thus obtained and drying it.

  A well-known method can be used for the coating method of a flowing layer. Examples thereof include coat coating, roller coating, hand coating, spin coating, coating by various printing methods, bar coating, die coating, spray coating, and the like.

  When forming the droplet layer, it is preferable to perform a surface treatment on the surface of the agricultural fluorine-based resin film because not only the applicability is improved but also the adhesion of the droplet layer is improved. As the surface treatment method, various methods such as corona discharge treatment, plasma treatment, and high-frequency sputter etching treatment are used.

  The thickness of the droplet layer after drying is preferably 0.2 to 0.8 μm. When the thickness of the droplet layer after drying is less than 0.2 μm, the droplet performance is poor, and when it is thicker than 0.8 μm, the droplet performance itself is not affected but the productivity may be inferior.

  The heating temperature and time for drying are not particularly limited. The heating temperature can be, for example, 60 to 100 ° C. The time can be, for example, 1 to 60 minutes. The heating temperature and time are preferably set in consideration of the heat resistance temperature of the object to be coated.

<Agricultural coating materials>
The agricultural covering material of the present invention uses the agricultural fluororesin film of the present invention. Since the agricultural fluororesin film of the present invention is excellent in transparency and UV blocking durability, the agricultural covering material of the present invention using the film can be suitably used for a covering material for a green house or the like. Moreover, in one embodiment relating to the agricultural fluorine-based resin film of the present invention, it is excellent in flexibility and durability against natural disasters, and can maintain drip performance over a long period of time. The agricultural covering material of the present invention can be suitably used for a covering material such as a green house.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, the raw material used in the Example and the evaluation method of the produced film are as follows.

<Raw materials>
“Kina-Flex 2850-00” (manufactured by Arkema Inc.) Hexafluoropropylene ratio (HFP ratio) 5 mass%, melting point about 157 ° C.
“KINA-FLEX 2800-20” (manufactured by Arkema Co., Ltd.) Hexafluoropropylene ratio (HFP ratio) 10 mass%, melting point about 142 ° C.
“KINA-FLEX 2500-20” (manufactured by Arkema Inc.) Hexafluoropropylene ratio (HFP ratio) 20 mass%, melting point about 121 ° C.
(Drip agent)
“Laclein B1” manufactured by Daiwa Steel Co., Ltd. (containing synthetic smectite as colloidal layered silicate and methoxymethylated nylon as polymer binder, containing 10 parts by weight of layered silicate with respect to 100 parts by weight of polymer binder) And a light stabilizer (hindered amine light stabilizer).

<Evaluation method>

(Optical properties)
(Total light transmittance)
The total light transmittance was measured by cutting out the obtained agricultural fluorine-containing multilayer film into 5 cm square and using “NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K6783.

(Haze)
For the haze measurement, the obtained fluorine-containing multilayer film for agriculture was cut into a 5 cm square and measured using “NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K7136.

(Measurement of light transmittance in the ultraviolet region)
In the measurement of light transmittance in the ultraviolet region, light transmittance at a wavelength of 300 nm was measured using “UV-2600” manufactured by Shimadzu Corporation.

(Dynamic elastic modulus)
The dynamic viscoelastic modulus, which is an index of flexibility, is a value at 25 ° C. measured using a “dynamic viscoelasticity measuring device RSA-G2” (manufactured by TA Instruments Co., Ltd.).

(Optical properties after weather resistance test)
The durability test was performed on the UV irradiation test under the following conditions using “Daipura Metal Weather” (manufactured by Daipura Wentes Co., Ltd.).
UV irradiation intensity: 132 mW / cm ²
1 cycle: 12 hours (10 hours irradiation, 2 hours dark shower)
Humidity: 51%
Black panel temperature: 62 ° C
Time: 504 hours Irradiation surface: Fluorine-based resin layer surface After the test, the optical properties of the film were evaluated, and the total light transmittance and HAZE after the test, and the light transmittance at a wavelength of 300 nm were measured.

<Example 1>
Titanyl sulfate (manufactured by Nacalai Tesque) was hydrolyzed to obtain metatitanic acid, which was baked to obtain titanium oxide. This titanium oxide was dispersed in water to form a water slurry. While stirring, an aqueous zirconium sulfate solution was added to the water slurry so that a surface coating made of zirconia was formed, and sodium hydroxide was added to adjust the pH to 7.0. Furthermore, aluminum nitrate was added to the water slurry so that a surface coating made of aluminum hydroxide was formed, and sodium hydroxide was added to adjust the pH to 7.0.
The slurry was then vacuum filtered to obtain a filter cake, which was washed with water to remove water-soluble salts, and then the filter cake was dried at 130 ° C. Then, it baked at 800 degreeC using the electric furnace.
The obtained baked product was dispersed in water, again made into an aqueous slurry, and pulverized using a bead mill. The slurry is vacuum filtered to obtain a filter cake, which is washed with water to remove residual water-soluble salts, and then the filter cake is dried at 130 ° C. and then pulverized using a fluid energy mill. Then, by performing surface treatment with organopolysiloxane, titanium oxide particles having a surface treatment layer thickness of 4 nm, an average aspect ratio of 3, and an average length in the longitudinal direction of 350 nm were obtained. The thickness of the multilayer coating layer of titanium oxide particles was determined by embedding the titanium oxide particles in an epoxy resin, preparing a section with a microtome, and using a scanning transmission electron microscope HD-2700 (manufactured by Hitachi High-Technologies Corporation). The average film thickness of the multilayer coating layer is measured based on the photographed image.
Next, 100 parts by mass of the above-mentioned vinylidene fluoride-hexafluoropropylene copolymer “Kina-Flex 2800-20” as a raw material for the fluororesin film is blended with a tumbler together with 0.5 parts by mass of the above titanium oxide. And kneaded with a φ30 mm twin screw extruder to obtain a compound.
The above compound is mixed with a vinylidene fluoride-hexafluoropropylene copolymer so that the titanium oxide concentration becomes 0.1 parts by mass, and is put into a single-screw extruder of φ65 mm, extruded by a feed block method, and a metal cooling roll. Film was obtained. Next, after corona treatment was performed on one surface of the produced film, the above-mentioned droplet agent was applied as a droplet layer to prepare a film. Table 1 shows the results of evaluating the optical properties and dynamic elastic modulus of the produced fluororesin film.

<Examples 2 and 3>
A fluororesin film was prepared in the same manner as in Example 1 except that the thickness of the surface treatment layer of titanium oxide was as described in Table 1. The results are shown in Table 1.

<Examples 4 and 5>
A fluororesin film was prepared in the same manner as in Example 1 except that the addition amount of titanium oxide was as described in Table 1. The results are shown in Table 1.
<Example 6>
A fluororesin film was prepared in the same manner as in Example 1 except that the vinylidene fluoride-hexafluoropropylene copolymer species was changed to “KINA-FLEX 2500-20”. The results are shown in Table 1.

<Examples 7 and 8>
A fluororesin film was produced in the same manner as in Example 1 except that the content of titanium oxide was as described in Table 1. The results are shown in Table 1.

<Example 9>
A fluororesin film was prepared in the same manner as in Example 1 except that the vinylidene fluoride-hexafluoropropylene copolymer species was changed to “KINA-FLEX 2850-20”. The results are shown in Table 1.

<Example 10>
The vinylidene fluoride-hexafluoropropylene copolymer of Example 10 was produced according to the following procedure. That is, 5.6 L of demineralized water was added to a 10 L horizontal autoclave equipped with a stirrer operating at 600 rpm after deaeration. The autoclave was then heated to 85 ° C. and maintained at that temperature for the entire reaction. A monomer gas phase mixture of 48 mol% vinylidene fluoride and 52 mol% hexafluoropropylene was introduced into the autoclave so that the pressure was 19 bar. Thereafter, 40 g of di-ammonium persulfate was added in two stages: 12 g at the start of polymerization and 28 g when the conversion was 70%. The set pressure of 19 bar was kept constant during the polymerization by feeding a mixture consisting of 67.5 mol% vinylidene fluoride and 25.5 mol% hexafluoropropylene. After 77 minutes, the autoclave was cooled and the latex was removed. A vinylidene fluoride-hexafluoropropylene copolymer having a monomer composition of 74.8% by mass of VDF and 25.2% by mass of HFP was produced. A fluororesin film was produced in the same manner as in Example 1 using the polymer. The results are shown in Table 1.

<Example 11>
A fluororesin film was prepared in the same manner as in Example 1 except that the average aspect ratio of titanium oxide was as described in Table 1. The results are shown in Table 1.

<Comparative Example 1>
A fluororesin film was produced in the same manner as in Example 1 except that the average aspect ratio of titanium oxide was as shown in Table 2. The results are shown in Table 2.

<Comparative Examples 2-4>
A fluororesin film was prepared in the same manner as in Example 1 except that the surface treatment layer of titanium oxide was as shown in Table 2. The results are shown in Table 2.

<Comparative Examples 5 and 6>
A fluororesin film was produced in the same manner as in Example 1 except that the thickness of the surface treatment layer of titanium oxide was as shown in Table 2. The results are shown in Table 2.

<Comparative Example 7>
A fluororesin film was produced in the same manner as in Example 1 except that the average length in the longitudinal direction of titanium oxide was as shown in Table 2. The results are shown in Table 2.

<Comparative Example 8>
A fluororesin film was produced in the same manner as in Example 1 without adding titanium oxide. The results are shown in Table 2.

Claims (6)

Provided with a fluorine resin film containing fluorine resin and titanium oxide particles,
The titanium oxide particles are particles having an average aspect ratio of 1.2 or more and an average length in the longitudinal direction of 550 nm or less,
The titanium oxide particles have a multilayer coating layer on titanium oxide,
The multilayer coating layer includes at least a zirconium oxide coating layer, an aluminum hydroxide coating layer, an organopolysiloxane coating layer,
An agricultural fluorine-based resin film, wherein the multilayer coating layer has a thickness of 2 nm to 7 nm. The agricultural-use fluororesin film according to claim 1, wherein the multilayer coating layer is formed with a zirconium oxide coating layer, an aluminum hydroxide coating layer, and an organopolysiloxane coating layer in order from the inside. The agricultural fluorine-based resin film according to any one of claims 1 and 2, wherein 0.03 to 1.0 parts by mass of the titanium oxide particles are contained with respect to 100 parts by mass of the fluorine-based resin. . The agricultural fluororesin film according to any one of claims 1 to 3, further comprising a droplet layer having hydrophilic performance on at least one surface. The fluororesin comprises a random copolymer containing 80 to 90% by mass of monomer units based on vinylidene fluoride and 10 to 20% by mass of monomer units based on hexafluoropropylene. The agricultural fluororesin film according to any one of claims 1 to 4, wherein   The agricultural covering material which uses the agricultural fluororesin film of any one of Claims 1-5.