JPH1158629A - Fog-resistant film for agriculture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fog-resistant film for agriculture which shows the outstanding endurance and durability of fog resistance effects and also high resistance to the adhesion of pollutant. SOLUTION: This fog-resistant film for agriculture has a substantially transparent layer B containing a photocatalytic material (b) made up of a photocatalytic action substance (b-1) and a silicon compound (b-2) formed on at least, one of the faces of a film A of a fluororesin. The silicon compound (b-2) is made of a silicone or a silicone precursor or silica or a silica precursor. The layer B shows water wetting properties at 10 deg. or less in terms of an angle of contact with water in accordance with photoexcitation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antifogging film for agricultural use which has excellent durability and durability of an antifogging effect and also has antifouling adhesion.

[0002]

2. Description of the Related Art Agricultural films are widely used as components of roofs and walls of agricultural houses used for growing crops. Such a film is required to have durability and weather resistance due to long-term exposure to wind and rain, and also has sufficient light transmission and becomes cloudy due to long-term use so that the crop is exposed to sufficient sunlight. There must be some ingenuity. Agricultural anti-fog films have been developed for such purpose, and various films have been proposed.

In order to maintain anti-fogging properties, for example, a mixture of a resin constituting a film with an inorganic substance such as colloidal silica or alumina sol and a hydrophilic binder such as polymethyl methacrylate or polyvinyl pyrrolidone is used. . However, this film has poor initial anti-fogging property (anti-fogging property when fogging starts to occur), so that when the temperature of the outside air drops sharply in the morning, dew condensation occurs on the inner surface of the film and the water drops. As a result, the crops in the house are adversely affected, and the light transmittance is reduced. Further, since the adhesion between the film and the antifogging layer formed on the surface of the film deteriorates with time, there is a disadvantage that the antifogging effect deteriorates with time.

JP-A-53-39347, JP-A-5-39347
JP-A-5-99987 and JP-A-57-73059 disclose an antifogging agent containing unmodified polyvinyl alcohol and an inorganic substance such as colloidal silica and sodium silicate as main components. However, since the surface hardness decreases when the haze (moisture) generated on the surface is absorbed by the antifogging layer, scratches and the like are likely to occur,
The wettability to water was also insufficient, and was not practical.

Japanese Unexamined Patent Publication (Kokai) No. 59-179885 discloses that a modified polyvinyl alcohol having a silyl group and an ionic hydrophilic group in a molecule and an antifogging agent composed of an inorganic substance are mainly applied to a glass plate or a polyester film. A technique for performing this is disclosed. However, in this technique, since the polyester film and the anti-fogging agent are adhered using an adhesive, there are disadvantages that the process becomes complicated and the cost becomes high.

Incidentally, it is known that a photocatalytic substance such as titanium oxide is photo-excited by ultraviolet rays to generate a strong oxidizing and reducing power. As a result, it exhibits the property of decomposing organic substances, and is contained in paints and the like for the purpose of decomposing harmful substances, odorous substances and oils and imparting an antibacterial effect. It is being considered for use.

However, there has been no technique for applying these photocatalytic substances to the above-mentioned agricultural anti-fog film. Furthermore, photocatalytic substances are originally
Since it is excited by light to generate oxidation and reducing power and exerts antibacterial action and the like, if a film is formed by including a photocatalytic substance in a resin, the resin itself containing the photocatalytic substance will be subjected to the oxidation. In addition, it is considered that the resin is decomposed due to the reducing action, and the function of the film itself is degraded, and it has been difficult to realize the function by a usual method.

Japanese Patent Application Laid-Open No. 4-284851 discloses a method of forming a coating film having a photocatalyst by laminating and pressing a mixture of photocatalyst particles and a fluoropolymer. Japanese Patent Application Laid-Open No. 4-334552 discloses a technique for obtaining the same effect by thermally fusing photocatalyst particles to a fluoropolymer. Furthermore,
JP-A-7-171408 discloses a technique in which photocatalyst particles are adhered to a substrate via a hardly decomposable binder such as a fluorine-based polymer and a silicon-based polymer.

However, when a photocatalytic substance is contained in these or vinylidene fluoride rubbers, those having a large amount of monomers having C—H bonds and C—Cl bonds in the polymer are deteriorated by light. In addition, crystalline polymers such as polytetrafluoroethylene have problems that high-temperature baking is essential and that the specific surface area of the photocatalyst particles is reduced due to the high-temperature heat treatment, so that the photocatalytic function is reduced.

[0010] A technique for forming a film suitable for greenhouse horticulture by suppressing a specific wavelength light (harmful ultraviolet light) region by adding an ultraviolet ray blocking agent to an agricultural anti-fog film is known. However, the ultraviolet ray blocking agent has a particle size of 0.01 μm, preferably about 0.1 μm, and is intended to block ultraviolet rays by being contained, and does not function as a photocatalyst. Did not.

[0011]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides an anti-fogging film for agricultural use which has excellent durability and durability of the anti-fogging effect and also has anti-staining and adhesion properties. It is intended for.

[0012]

According to the present invention, a film (A) comprising a fluororesin is provided on at least one surface thereof with a photocatalytic material (b-1) comprising a photocatalytic substance (b-1) and a silicon compound (b-2). An agricultural antifogging film formed by forming a substantially transparent layer (B) containing b), wherein the silicon compound (b-2) comprises silicone or a silicone precursor or silica or a silica precursor. The above-mentioned layer (B) is an antifogging film for agricultural use characterized by exhibiting water wettability of 10 ° or less in terms of a contact angle with respect to water in response to light excitation. is there. Hereinafter, the present invention will be described in detail.

The agricultural antifogging film of the present invention comprises a film (A) made of a fluororesin and a substantially transparent layer (B) formed on one or both surfaces. The layer (B) will be described later, and the fluororesin constituting the film (A) will be described first. The fluororesin is an ethylene / tetrafluoroethylene copolymer (ET
FE) or tetrafluoroethylene / hexafluoropropylene copolymer (FEP). Fluororesins other than these two are not preferred for application to the agricultural anti-fog film of the present invention. As the ETFE, for example, as described in JP-A-59-197411, ethylene, tetrafluoroethylene, and a fluorine-containing vinyl monomer are used as monomers, and the molar ratio of ethylene: tetrafluoroethylene is 40%. : 60-60:
40, and the compounding ratio of the fluorine-containing vinyl monomer was 0.1.
What is 1-10 mol% is preferable from the point which is excellent in moldability and transparency.

The above-mentioned fluorine-containing vinyl monomer has the general formula: CH ₂ ＣCXRf (wherein X represents a hydrogen atom or a fluorine atom. Rf
Represents a fluoroalkyl group. The compounds represented by the formula (1), in which X is fluorine, are preferred. R
The alkyl group of the fluoroalkyl group represented by f preferably has 2 to 10 carbon atoms. When it is less than 2, the copolymer is not sufficiently modified, and when it exceeds 10, it is disadvantageous in terms of polymerization reactivity. Examples of the fluorine-containing vinyl monomer include, for example, CH ₂ ＣＦCFC ₅ F ₁₀ H and CH ₂ ＣＦCFC ₃ F ₆
H, CH ₂ ＣＦCFC ₂ F _{5 and the} like can be mentioned.

As the above-mentioned FEP, for example, JP-A-54
As described in JP-A-31492, diisopropyl peroxydicarbonate is used as a polymerization initiator in an aqueous medium in an amount of 0.05 to 5 based on the total amount of monomers.
A copolymer obtained by copolymerizing tetrafluoroethylene and hexafluoropropylene by weight, wherein the blending amount of hexafluoropropylene in the copolymer is 8 to 20% by weight. Is preferred in that it has excellent moldability and crack resistance.

Some crops for greenhouse horticulture and the like need to suppress a specific wavelength light (harmful ultraviolet ray) region. For such a use, a fluororesin contains an ultraviolet ray blocking agent in advance. You may use the film which made it fall. As the above-mentioned ultraviolet ray blocking agent, organic and inorganic ones are known, but as described in JP-A-59-204517, a high temperature (300 to 300.degree.
(400 ° C.), an inorganic type is preferable in that it does not decompose and deteriorate. Examples of the inorganic ultraviolet blocking agent include titanium oxide, zinc oxide, cerium oxide, and aluminum oxide.
As described in Japanese Patent Publication No. 7, titanium oxide and zinc oxide are particularly preferred in view of the ability to block ultraviolet rays and the effect on crops, and these two types may be used in combination. The addition amount of the ultraviolet ray blocking agent is preferably from 0.01 to 10% by weight, and particularly preferably from 0.1 to 5% by weight from the viewpoint of the ultraviolet ray blocking ability and transparency. As the particle size of the ultraviolet blocking agent, 0.01
To 100 μm is preferred, but from the viewpoint of dispersibility and transparency,
0.1 to 10 μm is particularly preferred. The ultraviolet ray blocking agent has an ability to block 30% or more, preferably 50% or more of the ultraviolet ray by reflecting and attenuating the ultraviolet ray of 350 nm or less. An effect having a favorable effect is obtained.

As a method for producing the ETFE or FEP film, a known molding method can be adopted.
For example, an extrusion molding method, an inflation molding method, a calendar molding method, a skive method, and the like can be given. Among them, the extrusion molding method is preferable in terms of excellent secondary workability and productivity. The thickness of the film is preferably from 10 to 250 μm. If it is less than 10 μm, it tends to be easily broken and wrinkled, and if it exceeds 250 μm, workability and transparency at the time of spreading tend to be poor. More preferably,
It is 50 to 150 μm.

Since the film (A) is made of a fluororesin and has water repellency and non-adhesiveness, it is necessary to devise a method of adhering it to the layer (B) described later. In order to improve the surface, the surface of the film (A) can be subjected to corona discharge treatment in advance.

As the atmosphere for the corona discharge treatment, when the fluororesin is ETFE, it is preferable to dissociate the CF bond of ETFE to activate the surface and increase the affinity. F _{1S of} CF bond
It is preferable that the intensity of the spectrum is reduced and an O _1S spectrum indicating the formation of a polar group by surface oxidation appears. Such an atmosphere is an atmosphere containing an active gas.Examples of the active gas include oxygen, carbon monoxide, carbon dioxide, nitrous oxide, methyl methacrylate, glycidyl methacrylate, vinyl acetate, styrene, methyl vinyl ketone, Acrylonitrile, hexane, xylene, and mixtures thereof can be mentioned.

The active gas is usually nitrogen, helium,
It can be used after being diluted with an inert gas such as argon. If the concentration of the active gas after dilution is too low, the surface activation is insufficient and the adhesion between the layer (B) and the film (A) is inferior. It is not preferable in terms of productivity. Processing is performed at a concentration corresponding to the type of each active gas. For example, in the case of oxygen, it can be performed at a concentration of 5 to 80% by volume,
From the viewpoints of productivity and cost, it is preferable to perform corona discharge treatment in air at normal temperature and normal pressure.

The conditions of the corona discharge treatment vary depending on the type, concentration, ambient temperature and pressure of the active gas. When air is used as the ambient at normal temperature and normal pressure, the charge density is 70 to 800 W / m. ² is preferred. 70W / m ²
If it is less than 1, the activation of the film surface becomes insufficient and the adhesion to the layer (B) tends to be poor, and 800 W / m
^If it exceeds ² , the film surface tends to be damaged and the appearance tends to be poor. Preferably from 90~270W / m ^2.

When the fluororesin of the present invention is FEP, for example, 0.3 to 1.5% by volume of vinyl acetate vapor,
Preferably, the corona discharge treatment is performed in a nitrogen atmosphere containing 0.7 to 1.3% by volume. Conditions of the corona discharge treatment in this case is 70~700W / m ^2, a tendency that adhesion is poor between the activation insufficient layers of FEP film surface is less than 70W / m ² (B) If it exceeds 700 W / m ² , the film surface tends to be scratched and the appearance tends to be poor. More preferably 90 to 2
00 W / m ² . When the fluororesin is FEP, activation of the fluororesin surface becomes insufficient by corona discharge treatment in an atmosphere containing only nitrogen.

The surface to be subjected to corona discharge treatment may be one side or both sides of the film (A), depending on the surface on which the layer (B) is formed. Further, the corona discharge treatment may be performed while flowing the atmosphere gas. Furthermore, corona discharge treatment may be performed while moving the film.

Now that the description of the film (A) of the present invention has been completed, the layer (B) will be described below.
The layer (B) of the present invention is a substantially transparent layer. In the present specification, “substantially transparent” means that the layer (B) does not affect the transparency of the film (A) by being formed on the surface of the film (A). means. Such a substantially transparent property can be achieved by the structure of the layer (B) described in detail below.

The layer (B) contains the photocatalytic material (b) described below, and can be prepared by blending, for example, various additives in addition to the photocatalytic material (b). The additive is not particularly limited, and examples thereof include various antifoaming agents, nonionic, cationic, and anionic surfactants.

The photocatalytic material (b) contained in the layer (B) comprises a photocatalytic substance (b-1) and a silicon compound (b-2). The photocatalytic substance (b-1)
Is in the form of fine particles. The fine particles, the average particle diameter,
0.1 to 0.001 μm.

As the photocatalytic substance (b-1),
It is not particularly limited as long as it has a photocatalytic function, and examples thereof include titanium oxide, zirconium oxide, zinc oxide, strontium titanate, tin oxide, tungsten oxide, iron oxide, bismuth oxide, and ruthenium oxide. Among them, titanium oxide is preferable.

The above-mentioned titanium oxide is harmless, chemically stable, and available at low cost. Titanium oxide also has a high band gap energy,
Ultraviolet light is required for photoexcitation and does not absorb visible light in the process of photoexcitation, so that color formation by complementary color components does not occur.

As the titanium oxide, any of anatase type and rutile type can be used. Rutile-type titanium oxide can be sintered at a high temperature, and a coating film with excellent strength and abrasion resistance can be obtained.However, anatase-type titanium oxide has a commercially available sol in which extremely fine particles are dispersed. And has the advantage that it can be easily obtained and that a very thin coating film can be easily formed. For the purpose of the present invention, anatase type titanium oxide is preferable.

When the above-mentioned titanium oxide is used, water is chemically adsorbed on the surface in the form of a hydroxyl group by photocatalysis when the titanium oxide is photo-excited by ultraviolet rays to be described later.
The unique effects of the present invention can be exhibited.

The silicon compound (b-2) constituting the photocatalytic material (b) of the present invention is 5 to 90 mol%, preferably 10 to 70 mol%, more preferably, in the photocatalytic material (b). , 10 to 50 mol%. As the silicon compound (b-2), first, silicone (organopolysiloxane) or silicone precursor can be used. These have an organic group bonded to a silicon atom, and the organic group is substituted by a hydroxyl group in response to photoexcitation, thereby exhibiting an effect unique to the present invention.

The material for forming the silicone is not particularly limited, and examples thereof include the following. Methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltrit
-Butoxysilane, n-propyltrichlorosilane, n
-Propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-propyltri-t-
Butoxysilane, n-hexyltrichlorosilane, n-
Hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane, n-decyltrichlorosilane, n-decyltribromosilane, n- Decyltrimethoxysilane,
n-decyltriethoxysilane, n-decyltriisopropoxysilane, n-decyltri-t-butoxysilane,
n-octadecyltrichlorosilane, n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n-octadecyltri-t-butoxysilane, phenyltrichlorosilane, phenyltrisilane Bromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-butoxysilane, tetrachlorosilane, tetrabromosilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane , Dimethyldichlorosilane, dimethyldibromosilane, dimethyldiethoxysilane, diphenyldiethoxysilane, diphenyldichlorosilane, diphenyl Jiburomushiran, diphenyl diethoxy silane.

Phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane, tri-t-butoxy Hydrosilane, trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane,
Trifluoropropyltri-t-butoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyl Trimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri-t-butoxysilane, γ-aminopropylmethyldimethoxysilane, γ -Aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane, γ-mercaptopropylmethyldimethoxysilane , Γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane,
β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane; partial hydrolysates of the above silane compounds, and mixtures thereof.

It is preferable that the silicone contains three-dimensionally crosslinked siloxane in an amount of 10 mol% or more.
In order to further secure good hardness and smoothness, it is preferable that the two-dimensionally crosslinked siloxane is contained in an amount of 60 mol% or more. Further, in order to increase the rate at which the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by photoexcitation, a silicone in which the organic group bonded to the silicon atom of the silicone molecule is an n-propyl group or a phenyl group is used. Is preferred. It is also possible to use an organopolysilazane compound having a silazane bond instead of the silicone having a siloxane bond.

As the silicon compound (b-2), silica or a silica precursor can be mentioned in addition to the silicone or the silicone precursor. The silica precursor is not particularly limited as long as it is a substance constituting silica by a reaction, and examples thereof include tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetraethoxysilane, and tetramethoxysilane. And silanol which is a hydrolyzate thereof, and polysiloxane having an average molecular weight of 3000 or less.

In preparing the photocatalytic material (b) from the photocatalytic substance (b-1) and the silicon compound (b-2), the photocatalytic substance (b-1) and the silicon compound (b) are prepared. -2) is preferably blended uniformly. Therefore, the photocatalytic substance (b-1) and the silicon compound (b-2) are preferably applied in the form of a dispersion, a solution, or a powder. For example, in order to disperse the photocatalytic substance (b-1) and the silica particles, they are mixed and put into a solvent, and a surfactant, an antifreezing agent, an antifoaming agent, and a pH adjuster are used. After adding other additives as necessary, such as a sand mill, ball mill, paint shaker, jet mill, grind mill, three rolls, stirring with a kneader,
A dispersing method can be adopted. When the liquid silicon compound (b-2) and the photocatalytic substance (b-1) are mixed, the photocatalytic substance (b-1) is charged into the liquid silicon compound (b-2), and The mixture can be uniformly mixed by stirring and dispersing in the same manner as described above.

The silica or the silica precursor is prepared, for example, by preparing a mixture with the photocatalytic substance (b-1) and, if necessary, hydrolyzing to form silanol. By heating at the above temperature to cause dehydration polycondensation of silanol, a photocatalytic material (b) in which titanium oxide is bound with amorphous silica can be obtained.

When titanium oxide is used as the photocatalytic substance (b-1) and silica is used as the silicon compound (b-2), for example, particles of anatase or rutile titanium oxide and silica particles are contained. After preparing the suspension, the photocatalytic material (b) can be obtained by sintering the suspension. Further, a mixture of a silica precursor and a crystalline titanium oxide sol is prepared, and if necessary, hydrolyzed to form silanol, and then heated at a temperature of about 100 ° C. or more to cause dehydration polycondensation of silanol. By
A photocatalytic material (b) in which titanium oxide is bound with amorphous silica can be obtained. In particular, when the dehydration-condensation polymerization temperature of silanol is about 200 ° C. or more, the degree of polymerization of silanol can be increased, and the alkali resistance performance of the photocatalytic material (b) can be improved.

In the present invention, as a method for forming a substantially transparent layer (B) containing the photocatalytic material (b) on the surface of the film (A), For example, a method of applying the composition containing the conductive material (b), a method of spraying the composition containing the photocatalytic material (b) on the surface of the film (A), and the like can be adopted.

As a method of applying the composition on the surface of the film (A), the composition containing the photocatalytic material (b) is formed into a dispersion (dispersion), a solution, or a powder, and then the composition is usually used. Is applied to one or both surfaces of the film (A) without or after performing the corona discharge treatment described above. The coating method is not particularly limited, and examples thereof include bar coater coating, brush coating, spray coating, dip coating, spin coating, die coating, flow coating, air knife coating, and blade coating.

The coating amount of the composition containing the photocatalytic material (b) is preferably 0.1 to 5.0 g / m ² (solid content). If it is less than 0.1 g / m ² , the antifogging property for a long time tends to be unable to be maintained, and if it exceeds 5.0 g / m ² , transparency tends to be poor. Preferably, 0.3
３3.8 g / m ² .

The layer (B) is formed at 100 to 200 ° C.
It is formed by performing a heat treatment for 30 minutes, preferably at 120 to 180 ° C. for 1 to 15 minutes. If the temperature of the heat treatment is lower than 100 ° C., the surface hardness at the time of water absorption tends to decrease, and if it exceeds 200 ° C., the film (A) tends to wrinkle. If the heat treatment time is less than 1 minute, the surface hardness at the time of absorbing water tends to be low,
If the time exceeds minutes, the production efficiency tends to deteriorate.

The thickness of the layer (B) thus formed is 0.1 to 2.0 μm, preferably 0.2 to 1.8.
μm. If the thickness is less than 0.1 μm, the antifogging property for a long time tends to be unable to be maintained.
If it exceeds m, the transparency tends to deteriorate.

In the method of spraying the composition containing the photocatalytic material (b) on the surface of the film (A), the composition is instantaneously heated to a temperature equal to or higher than the melting point and melted. It can be done by attaching.

The above-mentioned spraying method will be described more specifically. Various combustion gases such as city gas and acetylene gas can be used as the combustion gas. These have, for example, a melting temperature of 300 when compared to the plasma spraying method or the like.
Although there is a drawback that 0 ° C is the limit, the advantage of low cost can be maximized. When the composition is melted by heating the composition to a temperature equal to or higher than the melting point using the combustion gas, the particulate composition is transported and supplied by gas into the flame in which the combustion gas is burned, and installed in front of the flame. Sprayed on the surface of the fluorinated resin film. Although the distance between the flame of the combustion gas and the fluororesin film is not particularly limited, it is usually preferably 20 cm or less from the tip of the flame, and the flame of the combustion gas may hit the fluororesin film.

The temperature of the combustion gas depends on the photocatalytic substance (b) constituting the photocatalytic material (b) contained in the composition.
-1) and / or the melting point of the silicon compound (b-2). For example, when the photocatalytic substance (b-1) is titanium oxide, the melting point of titanium oxide is taken into consideration. 1000-3000 degreeC has a small fall of a photocatalytic activity, and is more preferable.

The speed at the time of the above-mentioned spraying is not particularly limited, but is usually in the range of 100 to 1000 m / sec, preferably 300 to 650 m / sec. Further, the amount of thermal spraying is not particularly limited, but is usually preferably 0.1 to 40 g / m ² . The temperature of the film (A) to be sprayed is preferably kept at room temperature, but is usually heated to about 80 to 130 ° C. However, depending on such a temperature, the film (A) is not affected by the spraying.

The layer (B) constituting the antifogging film for agriculture of the present invention has such a property that the water wettability becomes 10 ° or less in terms of a contact angle with water in response to light excitation. Those having such properties are the agricultural anti-fog films of the present invention, and the agricultural anti-fog films of the present invention are only those obtained after photoexcitation to impart such properties. It is not limited. If the water wettability exceeds 10 ° in terms of the contact angle with respect to water, the object of the present invention cannot be achieved, so that it is limited to the above range. In the present specification, the term “contact angle with water” means a temperature of 25 ° C. using a contact angle meter CA-DT · A type manufactured by Kyowa Interface Chemical Co., Ltd.
It means a value measured at a humidity of 22% RH.

The photoexcitation can be carried out by using any light source having a wavelength of energy higher than the band gap energy of the photocatalytic material (b). For example, when the photoexcitation wavelength is located in the ultraviolet region as in the case of titanium oxide, ultraviolet light contained in sunlight can be suitably used. In a room or at night, light excitation can be performed by an artificial light source. Further, light excitation can be easily performed even with weak ultraviolet light contained in a fluorescent lamp.

The anatase type titanium oxide has a wavelength of 387 n.
m or less, rutile-type titanium oxide can be photoexcited with ultraviolet light of 413 nm or less, tin oxide can be 344 nm or less, and zinc oxide can be photoexcited with ultraviolet rays of 387 nm or less. As the ultraviolet light source, indoor lighting such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, and a mercury lamp can be used. The photoexcitation is carried out until the surface has a contact angle with water of about 10 ° or less, preferably about 5 ° or less, particularly about 0 ° or less. In general, if photoexcitation is performed with an ultraviolet illuminance of 0.001 mW / cm ² , the contact angle with water can be reduced to 0 ° in several days.

[0051]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 ETFE (Neoflon ETFE, manufactured by Daikin Industries, Ltd.) as a fluororesin was extruded at a resin temperature of 330 ° C. to form a 60 μm thick film. One side of the obtained film has a charge density of 190 W / m under a nitrogen gas atmosphere.
^The corona discharge treatment was performed under the conditions of ² . The treated surface is surface-treated with a photocatalytic coating material having super hydrophilicity (manufactured by Totoki Kiki Co., Ltd., a titanium oxide-containing silicone agent).
Heat drying for hours. Thereafter, the specimen was irradiated with sunlight for one week to produce a test piece.

The following test was performed on the obtained test piece. The results are shown in Table 1. The test pieces obtained in Example 1 were evaluated by the following test methods. Water contact angle before peeling: Kyowa Interface Chemical Co., Ltd., contact angle meter CA-
The measurement was performed at a temperature of 25 ° C. and a humidity of 22% RH using a DT · A type.

Initial antifogging property before peeling: inner diameter 6 cm, depth 7 c
100 ml of pure water was placed in a glass bottle having a diameter of m, and the mouth was sealed with the anti-fog layer of the anti-fog film inside. The bottle was placed in a water bath at 40 ° C. so that the film surface had an inclination angle of 4/10. After 30 minutes, the fogging on the surface of the antifogging layer and the state of adhesion of water droplets were visually observed and evaluated according to the following criteria. "5" indicates that the film has complete anti-fogging property without clouding or water droplets attached thereto, and the cloudy or water-dropping adhesion area is 10
% Is less than "4" and the area of cloudiness and water droplets is 1
"3" for those in the range of 0% or more to less than 40%, and "2" for those in the range of 40% to less than 70% that are cloudy and water droplets, and 70% in the area of cloudy and water droplets. Those having no anti-fogging property were designated "1".

Contact angle with water after peeling: An adhesive tape (Cellophane tape, manufactured by Nitto Denko Corporation) is adhered to the treated surface of the antifogging film, and rubbed five times with a finger from above to make it adhere to the tape. The measurement was performed in the same manner as in the above-mentioned measurement of the contact angle with water, except that a test piece was used after peeling.

Initial antifogging property after peeling: Adhesive tape (Cellophane tape, manufactured by Nitto Denko Corporation) is adhered to the treated surface of the antifogging film, and rubbed 5 times from above to adhere, and then the tape is peeled off at once. The test was performed in the same manner as in the above-mentioned measurement of the initial antifogging property before peeling, except that the test piece was used as a test piece.

Stain resistance: The treated surface of the test piece is turned up,
The test was performed at an inclination angle of 30 ° on the site of Daikin Industries Yodogawa Works. One month, two months and three months after the exposure, the degree of adhesion of dirt was visually observed and evaluated according to the following evaluation criteria. A: No stain was generated. ：: Almost no stain was generated. Δ: Dirt was slightly adhered. X: Stain was considerably adhered.

Example 2 An ETFE film having a thickness of 60 μm was formed as in Example 1, and both surfaces of the film were subjected to corona discharge treatment under a condition of a charge density of 190 W / m ² under a normal temperature and normal pressure in a nitrogen gas atmosphere. Was done. The treated surface was treated on both sides with the photocatalyst coating material used in Example 1, and dried by heating at 120 ° C. for 1 hour. Thereafter, sunlight was irradiated for one week. The same test as in Example 1 was performed on the obtained test piece. The results are shown in Table 1.

Example 3 A test piece was prepared in the same manner as in Example 1 except that corona discharge treatment was performed in an air atmosphere instead of a nitrogen gas atmosphere, and the same test as in Example 1 was performed. . The results are shown in Table 1.

Comparative Example 1 An antifogging agent was produced according to the production method described in Example 1 of JP-A-59-179885. That is, a copolymer of vinyltrimethoxysilane and vinyl acetate obtained by saponification contains 0.5 mol% of silyl groups as vinyl silane units, the degree of saponification of vinyl acetate units is 99.0 mol%, and A modified PVA having a degree of 700 was obtained. The modified PVA was dissolved in a 1.5% aqueous sodium hydroxide solution with respect to the modified PVA so that the modified PVA became 10% to obtain an aqueous solution of the modified PVA. A predetermined amount of silica was added to a predetermined amount of this aqueous solution, and the mixture was stirred to be uniform, thereby obtaining an antifogging agent. This antifogging agent was prepared in Example 1
The surface of the ETFE film having been subjected to the corona discharge treatment prepared in the above was coated with a bar coater so that the anti-fogging layer after the heat treatment became 0.5 g / m ² . The silica used was colloidal silica (Snowtex-O manufactured by Nissan Chemical Industries, Ltd., solid content concentration 6.2%, average particle size 100 μm). Next, heat treatment was performed at 150 ° C. for 3 minutes to prepare a test piece, and the same test as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 2 In Example 1, FEP (Neoflon FEP, manufactured by Daikin Industries, Ltd.) was extruded as a fluororesin at a resin temperature of 390 ° C. to form a film having a thickness of 100 μm. Under a nitrogen gas atmosphere containing 0.5% of vinyl acetate vapor on one side of the obtained film, the charge density was 124 W / m ^2.
The corona discharge treatment was performed under the following conditions. The anti-fogging agent obtained in Comparative Example 1 was applied to the treated surface by a bar coater so that the anti-fogging layer after heat treatment became 0.5 g / m ² .
A heat treatment was performed at 150 ° C. for 3 minutes to prepare a test piece, and the same test as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 3 The same ETFE as in Example 1 was mixed with 0.1% by weight of an ultraviolet ray blocking agent (TiO ₂ ) to form a pellet. The pellet was extruded at 330 ° C. to form a film having a thickness of 60 μm. One surface of the obtained film was subjected to a corona discharge treatment under a nitrogen gas atmosphere under normal temperature and normal pressure at a charge density of 180 W / m ² . On the treated surface, the anti-fogging layer obtained after heat-treating the anti-fogging agent obtained in Comparative Example 1 with a bar coater was 0.5 g /
It was coated in such a way that m ^2. A heat treatment was performed at 150 ° C. for 3 minutes to prepare a test piece. The same test as in Example 1 was performed on the obtained test piece. The results are shown in Table 1.

Comparative Example 4 A test piece was prepared in the same manner as in Example 1 except that the surface treatment with the photocatalytic coating material was not performed, and the same test as in Example 1 was performed. The results are shown in Table 1.

[0064]

[Table 1]

[0065]

Since the agricultural anti-fog film of the present invention has the above-mentioned constitution, it has excellent durability and durability of the anti-fog effect, and also has excellent anti-fouling adhesion. In addition, the antifogging film having the same configuration as the agricultural antifogging film of the present invention exhibits excellent performance as a cover material of a solar cell or the like by utilizing the above-described excellent effects.

Claims (3)

[Claims] 1. A substantially transparent film containing a photocatalytic substance (b-1) and a silicon compound (b-2) on at least one surface of a film (A) composed of a fluororesin. An antifogging film for agricultural use having a layer (B) formed thereon, wherein the silicon compound (b-2)
Is composed of silicone or a silicone precursor or silica or a silica precursor, and the layer (B)
Is an antifogging film for agricultural use, which exhibits water wettability of 10 ° or less in contact with water in response to light excitation. 2. The photocatalytic substance (b-1) is at least one selected from the group consisting of titanium oxide, iron oxide, tungsten oxide, zirconium oxide, tin oxide, bismuth oxide, ruthenium oxide, zinc oxide and strontium oxide. The agricultural antifogging film according to claim 1, which is a compound of a kind. 3. The antifogging film for agricultural use according to claim 2, wherein the photocatalytic substance (b-1) is an anatase type titanium oxide.