JP2007162029A - Fluororesin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluororesin film excellent in transparency and shielding property to UV light with wave length less than 360 nm. <P>SOLUTION: The invention relates to the fluororesin film composed of ethylene-tetrafluoroethylene copolymer, etc., containing composite particles dispersed in the resin, wherein the composite particle having 1-30 μm of particle size comprises zinc oxide particles obtained by coating 100 pts.wt. of zinc oxide with 20-200 pts.wt. of amorphous silica and agglutinating, preferably the surface of the composite particles is subjected to a treatment producing a hydrophobic surface by an organic silicone compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluororesin film having excellent dispersibility and transparency of an ultraviolet blocking material blended in a fluororesin and excellent in ultraviolet blocking properties and weather resistance.

  Fluororesin, especially tetrafluoroethylene copolymer, is used as an agricultural house film or roof material as a material that maintains weather resistance, transparency, and contamination resistance over 20 years of outdoor exposure.

  When the fluororesin film is laminated with plastics such as soft vinyl chloride resin, hard vinyl chloride resin, polyethylene, ABS resin, polycarbonate, or metal plates such as stainless steel plate, aluminum plate, galvanized steel plate, etc. Need to be laminated through. However, since the fluororesin film itself transmits ultraviolet rays, the outermost layer fluororesin film blocks ultraviolet rays in order to prevent deterioration of the adhesive by ultraviolet rays, for example, a method of blocking ultraviolet rays by dispersing a pigment in the fluororesin. Has been adopted.

  However, this method impairs the transparency of the fluororesin film. For example, when the fluororesin film is laminated on a steel sheet having a surface printed thereon, there is a problem that the printing is difficult to see. In order to cope with this, it is preferable that the fluororesin film keeps the visible light transmittance of 400 to 700 nm high and blocks ultraviolet light having a wavelength of 360 nm or less that causes photodegradation of the adhesive.

  When a fluororesin film is used as an agricultural house film, in order to improve the color, sugar content, and yield of cultivated fruits, flowers, vegetables, etc., a film in which the ultraviolet transmittance is adjusted correspondingly is required. In particular, in recent years, the damage of pests such as thrips has been great, and in order to prevent the activities of these pests in agricultural houses, the development of agricultural house films that block ultraviolet rays is awaited.

  Conventionally, as a method for imparting an ultraviolet blocking function to a fluororesin film, for example, a method of blending titanium oxide or zinc oxide having a particle diameter of about 0.02 μm with an ethylene-tetrafluoroethylene copolymer (hereinafter referred to as ETFE). It has been proposed (Patent Document 1). However, in this method, the dispersion of the titanium oxide fine particles is poor, the fine particles are aggregated and the film is whitened, and the deterioration of the ETFE film itself is promoted by the photocatalyst of titanium oxide due to light and rain for a long time, and the film becomes hollow. Will occur.

  Also disclosed is a method of producing an ultraviolet blocking film by dispersing and kneading titanium oxide fine particles surface-coated with a silane coupling agent having a methyl group bonded to a silicon atom in ETFE (Patent Document 2). However, the dispersibility of the surface-treated titanium oxide is not improved, and a film having a small haze cannot be obtained. Moreover, the coating thickness of the silane coupling agent obtained by surface-treating fine particles such as titanium oxide is only a few nm, and it is difficult to reduce the photocatalytic action on ETFE.

  An ETFE film with a small amount of added titanium oxide can block ultraviolet rays having a wavelength of 300 nm or less, but it is necessary to increase the amount of added titanium oxide in order to block ultraviolet rays having a wavelength of 360 nm or less. As a result, the transparency of the ETFE film is improved. Significantly damaged.

  Since zinc oxide is superior to titanium oxide in its ability to block ultraviolet rays, at least the amount of zinc oxide added can block ultraviolet rays having a wavelength of 360 nm or less. However, zinc oxide reacts with a fluorine compound liberated from the fluororesin during outdoor exposure and changes to zinc fluoride which does not have an ultraviolet blocking function, resulting in a problem that the ultraviolet blocking function of the ETFE film tends to be lowered. In addition, even when zinc oxide fine particles are kneaded with ETFE to form a film, it is easily altered by the generated fluorine compound.

Patent Document 3 proposes an agricultural ETFE film in which cerium oxide fine particles are kneaded. Cerium oxide has a smaller photocatalytic function than titanium oxide, and in the same way as zinc oxide, it reacts with fluorine compounds released from fluororesin during outdoor exposure and changes to cerium fluoride, which does not have UV blocking function, and gradually becomes ultraviolet light on the film. There arises a problem that the shut-off function tends to deteriorate. In addition, an ETFE film with a small amount of cerium oxide can block ultraviolet rays having a wavelength of 300 nm or less, but it is necessary to increase the amount of cerium oxide added to block the wavelength of 360 nm or less. As a result, the transparency of the ETFE film is reduced. Significantly damaged.
JP 7-3047 A Japanese Patent Laid-Open No. 7-304924 JP-A-8-37942

  The present invention provides a fluororesin film having excellent transparency and excellent ultraviolet blocking of 360 nm or less.

  In order to ensure good transparency of the film in which the ultraviolet blocking material is dispersed, it has been conventionally desired that the dispersed particle diameter is 0.01 μm or less. However, as a result of intensive studies in order to solve the above-mentioned problems, a composite formed by agglomerating zinc oxide particles coated with amorphous silica as dispersed particles having a dispersed particle size of 100 times larger than 0.01 μm. The fluororesin film in which the particles are dispersed is found to have excellent transparency and completely prevent the alteration of zinc oxide by the fluorine compound generated from the fluororesin, and the present invention is completed based on the knowledge. It came to.

That is, the present invention is a fluororesin film in which composite particles formed by assembling zinc oxide particles coated with 20 to 200 parts by weight of amorphous silica with respect to 100 parts by weight of zinc oxide are dispersed, Provided is a fluororesin film, wherein the ratio of the composite particles having a particle diameter of 1 to 30 μm to the entire composite particles is 95% by weight or more.
Also, composite particles in which the surface of the composite particles formed by assembling zinc oxide particles coated with 20 to 200 parts by weight of amorphous silica with respect to 100 parts by weight of zinc oxide are hydrophobized with an organosilicon compound are dispersed. The fluororesin film is characterized in that the ratio of the composite particles having a particle diameter of 1 to 30 μm to the entire composite particles is 95% by weight or more.

  A fluororesin film having excellent transparency and long-term ultraviolet blocking properties can be obtained.

The composite particles formed by assembling the zinc oxide particles coated with the amorphous silica used in the present invention are burned products of the particles coated with the insoluble zinc compound with the amorphous silica, and the production method is exemplified below. You may use the composite particle obtained by manufacturing methods other than.
The insoluble zinc compound is a zinc compound that is insoluble or hardly soluble in water, and examples thereof include zinc hydroxide, zinc phosphate, zinc carbonate, and zinc oxide. Zinc carbonate is preferred.

Amorphous silica is amorphous silica having no crystallinity. For example, amorphous silica is obtained by hydrolyzing a silicon compound such as No. 3 sodium silicate (SiO ₂ content: 28.5%) or tetraethyl silicate. Silica is mentioned.

  A production example of composite particles formed by assembling zinc oxide particles coated with amorphous silica is shown below. For example, zinc oxide having a particle size of about 0.01 μm is dispersed in water, a silicon compound is dropped into the aqueous dispersion with stirring, and then dried, and further fired at 200 to 1000 ° C., preferably 400 to 600 ° C. The method of doing is mentioned. In addition, water is added to an insoluble zinc compound such as zinc carbonate to form an aqueous dispersion using a disperser or an emulsifier, and a silicon compound is added dropwise to the aqueous dispersion with stirring to coat silica with a particle size of about 0.1 μm or less. An insoluble zinc compound is obtained. Thereafter, it is dried and further calcined at 200 to 1000 ° C., preferably 400 to 600 ° C., whereby the insoluble zinc oxide compound becomes zinc oxide, and the composite particles are formed by collecting zinc oxide particles coated with amorphous silica. Is obtained.

  In the composite particles used in the present invention, the ratio of the composite particles having a particle diameter of 1 to 30 μm in the entire composite particles is 95% by weight or more. The particle diameter is preferably 1 to 20 μm. When the composite particle diameter is large, holes are likely to be formed in the formed film.

  The composite particle used in the present invention has a particle size in the range of 1 to 30 μm, and a composite containing 10 parts by weight or less, particularly 3 parts by weight or less of particles outside this particle size range with respect to 100 parts by weight of the composite particle. Even if it uses, there is no trouble with respect to the effect of this invention. The average particle diameter of the composite particles is preferably 4 to 10 μm, particularly 4 to 8 μm.

  The composite particles are obtained by fusing and solidifying amorphous silica coated with insoluble zinc compound particles at the time of production of the composite particles in a drying and firing process. However, since the insoluble zinc compound particles and zinc oxide particles before firing are coated with amorphous silica, the insoluble zinc compound particles and zinc oxide particles are neither secondary nor tertiary aggregated. The aggregate of the particles in the composite particles used in the present invention is different from that in which ultrafine particles having a size of 0.01 μm or less, which has been conventionally used for ensuring good transparency, are secondary or tertiary aggregated. Since amorphous silica has high transparency, even if large composite particles of 1 to 30 μm are dispersed, the transparency of the fluorine film is not adversely affected.

  Since the composite used in the present invention has a large coating thickness of amorphous silica covering zinc oxide, the zinc oxide does not come into contact with the fluororesin, and reacts with the fluorine compound generated from the fluororesin and transforms into zinc fluoride. Can be prevented.

  The amorphous silica is 20 to 200 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of zinc oxide. If the amount is less than 20 parts by weight, the coating thickness of the amorphous silica is small, so that it is difficult to prevent the deterioration of zinc oxide by the fluorine compound generated in the fluororesin for a long period of time.

  In order to improve dispersion of the composite particles in the fluororesin, the surface of the composite particles is preferably subjected to a hydrophobic treatment with a surface treatment agent. Since the composite particles used in the present invention have a large particle size of 1 to 30 μm, the surface treatment can be easily performed.

As a measure of hydrophobicity, the degree of methanol hydrophobicity is used. The degree of methanol hydrophobization is an index indicating the hydrophobicity of particles, and the measurement method is as follows. Add 50 cc of distilled water to a 300 cc beaker and add 5 g of particles while stirring well. If the particles are evenly dispersed, the particles are very familiar with distilled water and have a methanol hydrophobization degree of 0%. If the particles are not uniformly dispersed, methanol is gradually added dropwise until the particles are uniformly dispersed in the aqueous solution. The methanol hydrophobization degree D (unit:%) is determined by the following equation from the total amount M (unit: cc) of methanol added until it is uniformly dispersed.
D = 100M / (M + 50)

The methanol hydrophobicity of the composite particles before surface treatment is less than 10%. Such particles having a low degree of hydrophobicity of methanol have a low dispersibility with respect to the fluororesin, and therefore it is preferable to use 40 to 75% of composite particles in the present invention.
The preferred degree of methanol hydrophobization required varies depending on the type of fluororesin, and in the case of ETFE, it is preferably 40 to 70%. Hexafluoropropylene-tetrafluoroethylene copolymer, perfluoro (alkyl vinyl ether) -In the case of a tetrafluoroethylene copolymer, it is preferably 60 to 75%. In the case of a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer, the content is preferably 40 to 70%.

  Any surface treating agent can be used as long as it can be firmly bonded to the surface of the composite particle and can increase the degree of hydrophobicity. Hydrolyzable groups such as alkoxy groups, hydroxyl groups, isocyanate groups and chlorine atoms, particularly those having 4 carbon atoms. Organosilicon compounds in which 2 to 3 of the following alkoxy groups are directly bonded to a silicon atom are preferably used. More preferably, an organosilicon compound having such a hydrolyzable group and having a hydrophobic organic group bonded to a silicon atom by a carbon-silicon bond is used, and a silane coupling agent, silicone oil, or the like is used. Organosilicon compounds are preferred.

  A normal silane coupling agent has a hydrolyzable group and a non-hydrolyzable organic group, and the non-hydrolyzable organic group has, for example, an epoxy group or an amino group as a functional group. Such a functional group has high hydrophilicity and is not so preferable as a surface coating agent in the present invention. Rather, an organosilicon compound having a hydrocarbon group that does not have a hydrophilic group or a fluorinated hydrocarbon group that provides high hydrophobicity as an organic group is preferable.

  As the organic group bonded to the silicon atom by a carbon-silicon bond, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, a mono (or poly) fluoroalkyl group, a mono (or poly) fluoroaryl group, and the like are preferable. . In particular, it may be substituted with an alkyl group having 2 to 20 carbon atoms, a mono (or poly) fluoroalkyl group having 2 to 20 carbon atoms having one or more fluorine atoms, an alkyl group or a mono (or poly) fluoroalkyl group. A phenyl group and the like are preferable.

  The organosilicon compound may be an organosilicone compound in which a hydrolyzable group is directly bonded to a silicon atom. The organic group in the organosilicone compound is preferably an alkyl group having 4 or less carbon atoms or a phenyl group. As such an organosilicone compound, what is called silicone oil can be used.

  Specific examples of the organosilicon compound include isobutyltrimethoxysilane, hexyltrimethoxysilane, trialkoxysilanes such as (3,3,3-trifluoropropyl) trimethoxysilane, ethyltriethoxysilane, dimethyl silicone oil, methyl hydrogen Silicone oils such as silicone oil and phenylmethyl silicone oil are preferable, and isobutyltrimethoxysilane, hexyltrimethoxysilane, ethyltriethoxysilane, and dimethylsilicone oil are particularly preferable.

The treatment amount of the surface treatment agent is related to the specific surface area of the composite particles, the reactivity of the surface treatment agent with the composite, and the like. Accordingly, a surface treatment agent having high reactivity with the complex and capable of hydrophobizing the complex with a small amount is preferable. In the present invention, 5 to 50 parts by weight of a surface treatment agent is reacted with 100 parts by weight of the composite to adjust the degree of methanol hydrophobicity of the composite. When the amount of treatment is large, the surface treatment agent between the composite particles adheres, and the aggregates composed of the composite particles become lumpy and the film appearance may deteriorate.
The surface treatment method is not particularly limited, but a method of dispersing the composite particles in a solution of water, alcohol, acetone, n-hexane or the like in which the surface treatment agent is dissolved, and then drying is preferable.

  The ultraviolet blocking function required for the fluororesin film of the present invention varies depending on the use of the film. For example, when used in a laminated manner, block UV light of 330 to 360 nm for protecting the adhesive by 70% or more, and allow visible light of 400 to 700 nm to pass through 70% or more for easy printing on the substrate surface. Is preferred.

  Moreover, when using for an agricultural house, it is necessary to have the ultraviolet-blocking function suitable for the kind of grain, a flower, a vegetable, and a fruit, the film which blocks | interrupts 100-300% of ultraviolet rays of 330-360 nm, the film which blocks 80%, 50 % Blocking film is used. Moreover, in order to prevent the activity of pests such as thrips, a film that blocks 70% or more of ultraviolet rays of 330 to 360 nm is used.

  The light transmittance in the present invention is determined by a measuring method based on JIS-K7105 and refers to the total amount of diffused light and parallel light, that is, the total light transmittance. The light source used in this method is standard light distributed according to JIS-Z8720 and distributed at 300 to 830 nm.

  In the present invention, “blocking light of 330 to 360 nm by 70% or more” means blocking 70% or more over the entire wavelength range. Further, “transmitting light of 400 to 700 nm by 70% or more” means transmitting 70% or more over the entire wavelength range.

  The fluororesin in the present invention is not particularly limited, but vinyl fluoride polymer, vinylidene fluoride polymer, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer, tetrafluoroethylene-propylene copolymer, tetrafluoroethylene -Hexafluoropropylene-propylene copolymer, ETFE, hexafluoropropylene-tetrafluoroethylene copolymer, or perfluoro (alkyl vinyl ether) -tetrafluoroethylene copolymer resin.

  Among these fluororesins, ETFE, hexafluoropropylene-tetrafluoroethylene copolymer, perfluoro (alkyl vinyl ether) -tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer are particularly preferred. preferable.

What is necessary is just to set the quantity of the composite particle disperse | distributed to the fluororesin film of this invention according to the ultraviolet-ray blocking performance requested | required, Usually, about 0.4-10 weight part is disperse | distributed with respect to 100 weight part of fluororesins. Is preferred.
Although the thickness of a fluororesin film does not have a restriction | limiting in particular, Usually, 6-500 micrometers, Preferably it is the range of 10-200 micrometers.

  The present invention will be described in detail with reference to examples and comparative examples. In this example, a film that blocks about 80% of ultraviolet rays of 330 to 360 nm was prepared, and its long-term performance was evaluated as an agricultural house film. In addition, a film that blocks 100% of ultraviolet light of 360 nm or less as a laminate application was prepared and evaluated. The ultraviolet blocking degree of the fluororesin film of the present invention is not particularly limited to this example.

[Example 1]
Sodium carbonate was added while blowing carbon dioxide gas into a 20 wt% zinc chloride aqueous solution to obtain a fine white slurry of zinc carbonate. The particle size of zinc carbonate was 0.005 to 0.02 μm. The zinc carbonate was thoroughly washed with water, kept at 60 ° C., and an ethanol solution containing 20% by weight of tetraethyl silicate was added dropwise with stirring to deposit amorphous silica on the surface of the zinc carbonate particles. The amount of tetraethyl silicate added dropwise was 100 parts by weight as SiO ₂ with respect to 100 parts by weight of zinc carbonate. Thereafter, stirring was continued for 1 hour or longer, and finally, neutralization was performed by adding dilute nitric acid to finish the coating of zinc carbonate with amorphous silica. Then, after passing through the steps of washing with water, drying and pulverization, firing was performed at 500 ° C. for 1 hour to obtain composite particles in which zinc oxide particles coated with amorphous silica were assembled.

The composition of the composite particles was ZnO: SiO ₂ = 100: 120 (weight ratio). Moreover, when the particle size of the composite particles was measured with a laser diffraction / scattering particle size distribution analyzer (manufactured by Seishin Enterprise, LMS-24), 95% of the particles were distributed in 1 to 30 μm, and the average particle size was It was 7.8 μm.

  200 g of the composite particles were put into a small Henschel mixer, and then 40 g of a solution obtained by dissolving 14 g of ethyltriethoxysilane in a mixed solvent of water: methanol = 1: 9 (weight ratio) was slowly added and stirred for 10 minutes. . Subsequently, the surface-treated wet composite particles were dried at 120 ° C. for 1 hour and again sufficiently loosened with a small Henschel mixer for 2 minutes. The surface treated particles have a methanol hydrophobization degree of 65%.

160 g of the surface-treated composite particles and 4 kg of ETFE (Aflon COP88AX, manufactured by Asahi Glass) were dry-mixed with a V mixer. This mixture was pelletized at 320 ° C. with a twin screw extruder.
Next, a 40 μm film was formed at 320 ° C. by a T-die method. This film had a total light transmittance of 92.2% and a haze of 18.5%, a total light transmittance at 360 to 330 nm of 20%, and a total light transmittance of 400 to 700 nm of 83% or more.

  The obtained film was subjected to corona discharge treatment, and 0.2 μm of a dropping agent mainly composed of silica fine particles and a silane coupling agent was applied to this surface. An agricultural pipe house was made using a mica wire coated with a nylon resin on the UV-blocking film subjected to the droplet treatment.

  This house was extended for 3 years, and the optical properties after that were measured. The total light transmittance was 92.8%, haze 18.0%, the total light transmittance at 400 to 700 nm was 85% or more, and the total light transmittance at 360 to 330 nm was 21%. Further, the tensile rupture strength retention rate of the film before and after stretching was 99%, and the tensile elongation retention rate was 98%, and no deterioration was observed. The results are shown in Tables 1 and 2. Moreover, the chart of the total light transmittance in each wavelength before and behind the extension for 3 years is shown in FIG.

  In addition, cucumbers (variety: Sharp 1) were cultivated in this house in the third year of expansion, but there was no damage caused by thrips, and cucumber harvesting was also good. The results are shown in Table 2.

[Examples 2, 3, 4]
In the same manner as in Example 1, the amorphous silica-zinc oxide composite in which the composition (weight ratio) of ZnO and SiO ₂ is 100: 30 (Example 2), 100: 80 (Example 3), and 100: 160 (Example 4) Table 1 shows the physical properties of the particles that were prepared and then surface-treated.

In addition, the film obtained by kneading the surface-treated composite particles into ETFE in the same manner as in Example 1 was subjected to droplet formation, and maintained for 3 years as an agricultural pipe house, and the optical properties before and after the tensile rupture strength was maintained. Tables 1 and 2 show the tensile strength and tensile elongation retention.
In addition, cucumbers were cultivated in this house. Table 2 shows the amount of harvest and the degree of damage caused by thrips.

[Examples 5, 6, and 7 (comparative examples)]
In the same manner as in Example 1, the amorphous silica-zinc oxide composite in which the composition (weight ratio) of ZnO and SiO ₂ is 100: 5 (Example 5), 100: 10 (Example 6), and 100: 15 (Example 7) Table 1 shows the physical properties of the particles that were prepared and then surface-treated.
Further, the optical properties before and after stretching for 3 years as an agricultural pipe house by dropping a film obtained by kneading the surface-treated composite particles into ETFE in the same manner as in Example 1, and tensile breaking strength and The elongation is shown in Tables 1 and 2.

Although the tensile strength and elongation are almost maintained at the initial values, the smaller the amount of amorphous silica covered, the lower the UV blocking function. Therefore, as shown in Table 2, cucumbers were cultivated in this house, but the damage caused by thrips was enormous.
Moreover, the chart of the total light transmittance in each wavelength before and behind the extension for 3 years about the film of Example 6 is shown in FIG.

[Example 8 (comparative example)]
A 40 μm ETFE film in which 1.5 parts by weight of cerium oxide (CeO ₂ ) particles having an average particle diameter of 0.01 μm was blended with 100 parts by weight of ETFE was molded. This film had a total light transmittance of 92.5% and a haze of 16.5%, a total light transmittance at 360 nm of 40%, and a total light transmittance at 400 to 700 nm of 80% or more. Tables 1 and 2 show optical properties, tensile strength at break, and elongation after the film was stretched for 3 years as an agricultural pipe house in the same manner as in Example 1.
Moreover, the chart of the total light transmittance in each wavelength before and behind the extension for 3 years is shown in FIG.
Tensile strength and elongation almost maintained their initial values. However, when cultivating cucumbers in this house, the damage caused by thrips was enormous.

[Example 9]
A 40 μm ETFE film was prepared by blending 8 parts by weight of 100 parts by weight of ETFE with the amorphous silica-zinc oxide composite having a surface treatment of 65% hydrophobized in Example 1.
This film had a total light transmittance of 89.2% and a haze of 26.2%. Further, ultraviolet rays of 360 nm or less were blocked 100%.

  This film surface was subjected to corona discharge treatment, laminated with a white polyester sheet using a polyester-based adhesive, and exposed to a carbon arc type Sanshan weatherometer tester for 5000 hours. The adhesion strength before and after exposure was 1.5 kgf / cm and 1.4 kgf / cm, respectively, and almost no decrease in adhesion strength was observed. Moreover, yellowing of the white polyester sheet of the base material was not observed.

[Example 10 (comparative example)]
Zinc oxide having an average particle size of 0.01 μm was hydrophobized with ethyltriethoxysilane in the same manner as in Example 1 to obtain particles having a degree of hydrophobicity of methanol of 60% and an average particle size of 0.2 μm. A 40 μm ETFE film containing 3 parts by weight of this filler with respect to 100 parts by weight of ETFE was formed. This film had a total light transmittance of 82.5% and a haze of 20.0%, a total light transmittance at 360 nm of 8%, and a total light transmittance at 330 nm of 8%.

  This film was processed in the same manner as in Example 1 and expanded as an agricultural pipe house, but in one month it lost its ultraviolet blocking property and had a total light transmittance of 93.5% and a haze of 6.2%. The transmittance was 86%, and the total light transmittance at 330 nm was 85%.

The chart of the total light transmittance of 280-700 nm of the film before extending | stretching of Example 1, the film after extending | stretching for 3 years, and the ETFE film which does not contain a ultraviolet blocker is shown. The chart of the total light transmittance of 280-700 nm of the film after extending | stretching for 3 years before extending | stretching of Example 6 is shown. The chart of the total light transmittance of 280-700 nm of the film after extending for 3 years before extending | stretching of Example 8 is shown.

Claims (6)

A fluororesin film in which composite particles formed by collecting zinc oxide particles coated with 20 to 200 parts by weight of amorphous silica with respect to 100 parts by weight of zinc oxide are dispersed,
A fluororesin film, wherein a ratio of composite particles having a particle diameter of 1 to 30 μm in the entire composite particles is 95% by weight or more. Dispersed are composite particles in which the surface of a composite particle formed by assembling zinc oxide particles coated with 20 to 200 parts by weight of amorphous silica with respect to 100 parts by weight of zinc oxide is hydrophobized with an organosilicon compound. A fluororesin film,
A fluororesin film, wherein a ratio of composite particles having a particle diameter of 1 to 30 μm in the entire composite particles is 95% by weight or more.   The fluororesin film according to claim 1 or 2, wherein an average particle size of the composite particles is 4 to 10 µm.   Fluorine resin is ethylene-tetrafluoroethylene copolymer, hexafluoropropylene-tetrafluoroethylene copolymer, perfluoro (alkyl vinyl ether) -tetrafluoroethylene copolymer, or tetrafluoroethylene-hexafluoropropylene- The fluororesin film according to any one of claims 1 to 3, which is a vinylidene fluoride copolymer.   5. The fluororesin film according to claim 1, wherein 50% or more of light having a wavelength of 330 to 360 nm is shielded and 70% or more of light having a wavelength of 400 to 700 nm is transmitted. The fluororesin film according to claim 1, wherein 70% or more of light having a wavelength of 330 to 360 nm is shielded and 70% or more of light having a wavelength of 400 to 700 nm is transmitted.

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