JPH11279358A - Fluororesin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluororesin film which is excellent in clarity and in intercepting ultraviolet rays with wavelengths of 360 nm or shorter. SOLUTION: This film is based on a fluororesin (e.g. an ethylene- tetrafluoroethylene copolymer) and contains composite particles dispersed therein. The composite particles have particle sizes of 1-30 μm and are formed by agglomerating zinc oxide particles prepd. by coating 100 pts.wt. zinc oxide with 20-200 pts.wt. amorphous silica. Pref., the surfaces of the composite particles are hydrophobized with an organosilicon compd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ultraviolet shielding material blended with a fluororesin, which has good dispersibility and transparency.
The present invention relates to a fluororesin film having excellent ultraviolet blocking properties and weather resistance.

[0002]

2. Description of the Related Art Fluororesins, particularly tetrafluoroethylene copolymers, are used as materials for maintaining weatherability, transparency and stain resistance for more than 20 years of outdoor exposure, as agricultural house films and roofing materials. ing.

[0003] Fluororesin films are made of soft vinyl chloride resin, hard vinyl chloride resin, polyethylene, ABS resin,
When laminated with a plastic such as polycarbonate or a metal plate such as a stainless steel plate, an aluminum plate, or a galvanized steel plate to be used for an outdoor building material, it is necessary to laminate with an adhesive. However, since the fluororesin film itself transmits ultraviolet rays, the outermost layer of the fluororesin film blocks ultraviolet rays in order to prevent the adhesive from being deteriorated by ultraviolet rays, for example, a method of dispersing a pigment in the fluororesin to block ultraviolet rays. Is adopted.

However, in this method, the transparency of the fluororesin film is impaired. For example, when the fluororesin film is used after being laminated on a steel plate having a printed surface.
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 transmittance of visible light of 400 to 700 nm high and blocks ultraviolet light of a wavelength of 360 nm or less which causes photodegradation of the adhesive.

[0005] When a fluororesin film is used as an agricultural house film, a film having a correspondingly adjusted ultraviolet transmittance is required to improve the color, sugar content and yield of cultivated fruits, flowers and vegetables. ing.
In recent years, particularly, in recent years, pests such as thrips have been greatly damaged, and in order to prevent the activity of these pests in an agricultural house, development of an agricultural house film that blocks ultraviolet rays has been awaited.

Conventionally, as a method of imparting an ultraviolet ray blocking function to a fluororesin film, for example, titanium oxide or zinc oxide having a particle diameter of about 0.02 μm is mixed with an ethylene-tetrafluoroethylene copolymer (hereinafter referred to as ETFE). (Japanese Patent Laid-Open No. 7-3047).
However, in this method, the dispersion of the titanium oxide fine particles is poor,
The problem that the film is whitened due to aggregation of the fine particles and the problem that the ETFE film itself is deteriorated by the photocatalyst of titanium oxide due to long-term light and rain and the film is hollowed out occur.

Further, a method is disclosed in which a titanium oxide fine particle surface-treated with a silane coupling agent having a methyl group bonded to a silicon atom is dispersed and kneaded in ETFE to produce an ultraviolet shielding film (Japanese Patent Application Laid-Open No. Hei 7 (1999)). −304
924). However, the dispersibility of the surface-treated titanium oxide is not improved, and a film having a small haze cannot be obtained. The coating thickness of the silane coupling agent obtained by surface-treating fine particles such as titanium oxide is only about several nm,
It is difficult to reduce the photocatalytic action on TFE.

An ETFE film containing a small amount of titanium oxide can block at least ultraviolet rays having a wavelength of 300 nm or less. However, it is necessary to increase the amount of titanium oxide added to block ultraviolet rays having a wavelength of 360 nm or less.
The transparency of the E film is significantly impaired.

[0009] Since zinc oxide has better ultraviolet blocking performance than titanium oxide, the amount of zinc oxide added is at least ET.
The FE film can block ultraviolet light having a wavelength of 360 nm or less. However, the zinc oxide reacts with the fluorine compound released from the fluororesin during outdoor exposure and is transformed into zinc fluoride having no ultraviolet ray blocking function. As a result, there is a problem that the ultraviolet ray blocking function of the ETFE film tends to be reduced. Also, when a zinc oxide fine particle is kneaded with ETFE to form a film, the film is easily deteriorated by the generated fluorine compound.

Japanese Patent Application Laid-Open No. 8-37942 proposes an agricultural ETFE film in which cerium oxide fine particles are kneaded. Cerium oxide has a smaller photocatalytic function than titanium oxide.Similarly to zinc oxide, it reacts with a fluorine compound released from a fluororesin during outdoor exposure and transforms into cerium fluoride, which does not have an ultraviolet ray blocking function. There is a problem that the shut-off function is apt to deteriorate. An ETFE film with a small amount of cerium oxide added has a wavelength of 30.
Although ultraviolet rays of 0 nm or less can be blocked, it is necessary to increase the amount of cerium oxide added to block ultraviolet rays of 360 nm or less, and as a result, the transparency of the ETFE film is significantly impaired.

[0011]

SUMMARY OF THE INVENTION The present invention provides a fluororesin film having excellent transparency and being excellent in blocking ultraviolet rays of 360 nm or less.

[0012]

Means for Solving the Problems In order to ensure good transparency of a film in which an ultraviolet ray shielding material is dispersed, it has conventionally been considered that the dispersed particle diameter is desirably 0.01 μm or less. However, as a result of intensive studies to solve the above-mentioned problems, the dispersed particle diameter is 100 μm compared to 0.01 μm.
More than twice as large, a fluororesin film in which composite particles formed by aggregating zinc oxide particles coated with amorphous silica as dispersed particles have excellent transparency, and a fluorine compound generated from the fluororesin is used. It has been found that the alteration of zinc oxide is completely prevented, and the present invention has been completed based on the findings.

That is, according to the present invention, composite particles having a particle diameter of 1 to 30 μm, which are formed by gathering 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. To provide a fluororesin film characterized in that: The surface of the composite particles having a particle diameter of 1 to 30 μm, in which zinc oxide particles coated with amorphous silica in an amount of 20 to 200 parts by weight with respect to 100 parts by weight of zinc oxide, are subjected to a hydrophobic treatment with an organosilicon compound. A fluororesin film, wherein the composite particles are dispersed.

The composite particles obtained by assembling the zinc oxide particles coated with amorphous silica used in the present invention are baked products of particles formed by coating an insoluble zinc compound with amorphous silica. Examples of the production method are described below. However, composite particles obtained by other production methods may be used. The insoluble zinc compound is a zinc compound that is insoluble or hardly soluble in water, such as zinc hydroxide, zinc phosphate, zinc carbonate, zinc oxide, and the like.
Zinc carbonate is preferred.

The amorphous silica is an amorphous silica having no crystallinity, for example, sodium silicate No. 3 (Si
(O ₂ content: 28.5%) and amorphous silica obtained by hydrolyzing a silicon compound such as tetraethyl silicate.

An example of the production of composite particles comprising aggregated 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, and a silicon compound is added dropwise to the aqueous dispersion with stirring.
Dry, and then 200-1000 ° C., preferably 400
A method of firing at -600 ° C is exemplified. 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. A silicon compound is dropped into the aqueous dispersion with stirring, and silica coating having a particle diameter of about 0.1 μm or less is performed. An insoluble zinc compound is obtained. After that, it is dried and further 20
By baking at 0 to 1000 ° C., preferably 400 to 600 ° C., the insoluble zinc oxide compound becomes zinc oxide, and composite particles obtained by gathering zinc oxide particles coated with amorphous silica are obtained.

The composite particles used in the present invention are aggregates of zinc oxide particles coated with amorphous silica having a particle diameter of 0.1 μm or less obtained by the above-mentioned production method, and the particle diameter is 1 to 30 μm. Preferably, it is 1 to 20 μm. If the composite particle size is large, pores are likely to be formed in the formed film.

The composite particles used in the present invention have a particle size of 1 to 30 μm.
However, the effect of the present invention can be obtained even when a composite containing particles having a particle size outside this range is not more than 10 parts by weight, especially not more than 3 parts by weight, per 100 parts by weight of the composite particles. No problem. The average particle size of the composite particles is 4 to 1
0 μm is preferable, and particularly preferably 4 to 8 μm.

The composite particles are particles in which amorphous silica coated with insoluble zinc compound particles is fused and solidified in the drying and firing steps during the production of the composite particles. However, since the insoluble zinc compound particles and zinc oxide particles before firing are covered with amorphous silica, the insoluble zinc compound particles and zinc oxide particles do not undergo secondary aggregation or tertiary aggregation. The aggregate of particles in the composite particles used in the present invention is 0.1%, which is conventionally used to ensure good transparency.
This is different from that in which ultrafine particles of not more than 01 μm are subjected to secondary aggregation or tertiary aggregation. Since amorphous silica has high transparency,
Even if the large composite particles of 30 μm are dispersed, the transparency of the fluorine film is not adversely affected.

In the composite used in the present invention, the coating thickness of the amorphous silica coating the zinc oxide is large, so that the zinc oxide does not come into contact with the fluororesin, and reacts with a fluorine compound generated from the fluororesin to react with the zinc fluoride. Can be prevented from being transformed into

The amorphous silica is used in an amount of 20 to 200 parts by weight, preferably 50 to 150 parts by weight, per 100 parts by weight of zinc oxide.
Parts by weight. 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 due to the fluorine compound generated in the fluororesin for a long period of time.

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

As a measure of hydrophobicity, the degree of methanol hydrophobicity is used. The methanol hydrophobicity is an index indicating the hydrophobicity of the particles, and the measuring method is as follows. 300
50 cc of distilled water is placed in a cc beaker, and 5 g of the particles are charged with good stirring. If the particles are uniformly dispersed, they are very compatible with distilled water and have a methanol hydrophobicity of 0%. If the particles are not uniformly dispersed, methanol is slowly added dropwise until the particles are uniformly dispersed in the aqueous solution. From the total amount M of methanol added (unit: cc) until it is just uniformly dispersed, the degree of methanol hydrophobicity D (unit:%) is determined by the following equation. D = 100M / (M + 50)

Before the surface treatment, the composite particles have a methanol hydrophobicity of less than 10%. Since such particles having a low methanol hydrophobicity have low dispersibility in a fluororesin, it is preferable to use 40 to 75% of composite particles in the present invention. The required degree of methanol hydrophobicity required by the type of fluororesin is slightly different, and in the case of ETFE, it is preferably 40 to 70%, and a hexafluoropropylene-tetrafluoroethylene copolymer,
In the case of a perfluoro (alkyl vinyl ether) -tetrafluoroethylene copolymer, the content is preferably 60 to 75%. In the case of the tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer, the content is preferably 40 to 70%.

As the surface treating agent, any agent capable of firmly bonding to the surface of the composite particles and increasing the degree of hydrophobicity can be used, and a hydrolyzable group such as an alkoxy group, a hydroxyl group, an isocyanate group, and a chlorine atom, in particular, Organosilicon compounds in which 2-3 alkoxy groups having 4 or less carbon atoms are directly bonded to silicon atoms are preferably used. More preferably, an organosilicon compound having such a hydrolyzable group and further having a hydrophobic organic group bonded to a silicon atom through a carbon-silicon bond is used, such as a silane coupling agent or silicone oil. Organosilicon compounds are preferred.

An ordinary silane coupling agent has a hydrolyzable group and a non-hydrolyzable organic group, and the non-hydrolyzable organic group has a functional group such as an epoxy group or an amino group. Such a functional group has high hydrophilicity and is not so preferable as the surface coating agent in the present invention. Rather, an organic silicon compound having, as an organic group, a hydrocarbon group having no hydrophilic group or a fluorinated hydrocarbon group providing high hydrophobicity is preferred.

Examples of the organic group bonded to the silicon atom through a carbon-silicon bond include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, a mono (or poly) fluoroalkyl group, and a mono (or poly) fluoroaryl group. Are preferred. Particularly, an alkyl group having 2 to 20 carbon atoms, 1
Preferred are a mono (or poly) fluoroalkyl group having 2 to 20 carbon atoms having a fluorine atom and a phenyl group which may be substituted with an alkyl group or a mono (or poly) fluoroalkyl group.

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, a compound called silicone oil can be used.

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

The treatment amount of the surface treating agent is related to the specific surface area of the composite particles, the reactivity of the surface treating agent with the composite, and the like.
Therefore, 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 5 parts by weight of the composite is 100 parts by weight.
0 parts by weight of the surface treating agent is reacted to adjust the degree of methanol hydrophobicity of the complex. If the treatment amount is large, the surface treating agent between the composite particles adheres, and the aggregates composed of the composite particles become lumpy and the film appearance may be deteriorated. The surface treatment method is not particularly limited, but a method in which the composite particles are dispersed in a solution of a surface treatment agent, such as water, alcohol, acetone, or n-hexane, and then dried is preferable.

The ultraviolet blocking function required for the fluororesin film of the present invention differs depending on the use of the film. For example, when used by lamination, ultraviolet rays of 330 to 360 nm are applied to protect the adhesive.
% Or more to make the printing on the substrate surface easier to see.
It is preferable to transmit 70% or more of visible light of 00 to 700 nm.

When used in an agricultural house, grains,
It is necessary to have an ultraviolet blocking function suitable for the types of flowers, vegetables, and fruits.
0% blocking film, 80% blocking film, 50
% Blocking film or the like is used. Further, in order to prevent the activity of pests such as thrips, especially 330-36
A film that blocks 70% or more of ultraviolet light of 0 nm is used.

The light transmittance in the present invention is defined by JIS-
It is obtained by a measurement method based on K7105, and refers to the total amount of diffuse light and parallel light, that is, the total light transmittance. The light source used in this method is standard light distributed in the range of 300 to 830 nm according to JIS-Z8720.

In the present invention, blocking of light of 330 to 360 nm by 70% or more means that light of 70 to 70
% Means blocking. Also, 400 to 700 nm
Transmitting 70% or more of the light means transmitting 70% or more over the entire wavelength range.

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

Of these fluororesins, especially ETF
E, hexafluoropropylene-tetrafluoroethylene copolymer, perfluoro (alkyl vinyl ether)
-A tetrafluoroethylene copolymer and a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer are preferred.

The amount of the composite particles dispersed in the fluororesin film of the present invention may be set in accordance with the required ultraviolet shielding performance.
It is preferable to disperse about 0.4 to 10 parts by weight. The thickness of the fluororesin film is not particularly limited, but is usually 6 to
It is in the range of 500 μm, preferably 10-200 μm.

[0038]

EXAMPLES The present invention will be described in detail with reference to examples and comparative examples. In this example, a film that blocks approximately 80% of ultraviolet rays having a wavelength of 330 to 360 nm was prepared, and its long-term performance as an agricultural house film was evaluated. Also, for laminating purposes, 100% of ultraviolet light of 360 nm or less is used.
A blocking film was prepared and evaluated. The degree of blocking ultraviolet rays of the fluororesin film of the present invention is not particularly limited to this example.

Example 1 Sodium bicarbonate was added to a 20% by weight aqueous solution of zinc chloride while blowing carbon dioxide gas to obtain a slightly white slurry of zinc carbonate. The particle size of zinc carbonate is 0.0
05 to 0.02 μm. After thoroughly washing the zinc carbonate with water, the temperature was maintained at 60 ° C., and a 20 wt% ethanol solution of tetraethyl silicate was added dropwise with stirring to deposit amorphous silica on the surface of the zinc carbonate particles. The addition amount of tetraethylsilicate is based on 100 parts by weight of zinc carbonate.
It was dropped so as to become 100 parts by weight as SiO ₂ . Thereafter, stirring was continued for 1 hour or more, and finally, dilute nitric acid was added to neutralize the mixture, and the coating of zinc carbonate with amorphous silica was terminated. Then, after the steps of washing, drying and pulverizing, 500
Calcination was carried out at 1 ° C. for 1 hour to obtain composite particles in which zinc oxide particles coated with amorphous silica were aggregated.

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

200 g of the composite particles were charged into a small Henschel mixer, and 40 g of a solution of 14 g of ethyltriethoxysilane dissolved in a mixed solvent of water: methanol = 1: 9 (weight ratio) was slowly charged. Stirred for minutes. Subsequently, the surface-treated wet composite particles were heated to 120 ° C.
For 1 hour, and again sufficiently loosened with a small Henschel mixer for 2 minutes. The methanol hydrophobicity of the surface-treated particles is 65%.

160 g of the surface-treated composite particles and 4 kg of ETFE (Aflon COP88AX, manufactured by Asahi Glass)
Was dry-mixed with a V mixer. This mixture was pelletized at 320 ° C. using 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.
%, The total light transmittance at 360 to 330 nm was 20%, and the total light transmittance at 400 to 700 nm was 83% or more.

The resulting film was subjected to a corona discharge treatment, and a 0.2 μm dropping agent containing silica fine particles and a silane coupling agent as main components was applied to this surface. A pipe house for agriculture was produced using a mica wire coated with a nylon resin on the dipped ultraviolet ray blocking film.

The house was expanded for three years, and the optical characteristics after that were measured. Total light transmittance is 92.8%, haze 1
8.0%, total light transmittance of 400 to 700 nm is 85%
As described above, the total light transmittance at 360 to 330 nm is 21.
%Met. In addition, the tensile breaking strength retention of the film before and after stretching was 99%, and the tensile elongation retention was 98%.
No deterioration was observed. The results are shown in Tables 1 and 2. FIG. 1 shows a chart of the total light transmittance at each wavelength before and after the expansion for three years.

In the third year of expansion, cucumber (cultivar: Sharp 1) was cultivated in this house, but there was no damage by thrips, and the cucumber harvest was good.
Table 2 shows the results.

[Examples 2, 3, 4] In the same manner as in Example 1, Zn
The composition (weight ratio) of O and SiO ₂ is 100: 30 (Example 2), 100: 80 (Example 3), 100: 160 (Example 4).
Table 1 shows the physical properties of the particles obtained by preparing an amorphous silica-zinc oxide composite and then performing a surface treatment.

The composite particles subjected to the surface treatment were kneaded with ETFE in the same manner as in Example 1 to obtain a film. Tables 1 and 2 show the breaking strength retention and the tensile elongation retention. In addition, cucumber was cultivated in this house, and the yield and the degree of damage by thrips are shown in Table 2.

Examples 5, 6, and 7 (Comparative Examples) As in Example 1, the composition (weight ratio) of ZnO and SiO ₂ was 100:
5 (Example 5), 100: 10 (Example 6), and 100: 15 (Example 7) were prepared as amorphous silica-zinc oxide composites, and then the physical properties of the particles subjected to surface treatment are shown in Table 1. Also,
The surface-treated composite particles were subjected to ETF in the same manner as in Example 1.
Tables 1 and 2 show the optical properties, tensile breaking strength, and elongation before and after the film obtained by kneading E was subjected to dropping processing and expanded as an agricultural pipe house for 3 years.

Although the initial values of the tensile strength and elongation are almost maintained, the UV blocking function decreases as the amount of the amorphous silica coating decreases. Therefore, as shown in Table 2, cucumber was cultivated in this house, but the thrips damage was enormous. FIG. 2 shows a chart of the total light transmittance of the film of Example 6 at each wavelength before and after stretching for three years.

Example 8 (Comparative Example) Average particle size 0.01 μm
Of cerium oxide (CeO ₂ ) particles of 1.5 parts by weight with respect to 100 parts by weight of ETFE to form a 40 μm ETFE film. This film has a total light transmittance of 92.5.
%, The haze was 16.5%, the total light transmittance at 360 nm was 40%, and the total light transmittance at 400 to 700 nm was 80% or more. Tables 1 and 2 show the optical properties, tensile breaking strength and elongation of this film after being stretched for 3 years as an agricultural pipe house in the same manner as in Example 1.
Shown in FIG. 3 shows a chart of the total light transmittance at each wavelength before and after the three-year expansion. The tensile strength and elongation almost maintained the initial values. However, when cucumber was grown in this house, the damage caused by thrips was enormous.

Example 9 Using the surface-treated amorphous silica-zinc oxide composite having a hydrophobicity of 65% of methanol obtained in Example 1,
This was blended with 8 parts by weight with respect to 100 parts by weight of ETFE to prepare a 40 μm ETFE film. This film had a total light transmittance of 89.2% and a haze of 26.2.
%Met. In addition, 100% of ultraviolet light of 360 nm or less is used.
Cut off.

The surface of this film was subjected to corona discharge treatment, laminated with a white polyester sheet using a polyester adhesive, and exposed to a carbon arc type sun shan weatherometer tester for 5000 hours. The adhesion before and after exposure is 1.5 kgf / cm and 1.4 kgf / cm, respectively.
, And almost no decrease in adhesion was observed. In addition, yellowing of the white polyester sheet as the base material was not observed.

[0053]

[Table 1]

[0054]

[Table 2]

Example 10 (Comparative Example) Average Particle Diameter 0.01
The μm zinc oxide was hydrophobized with ethyltriethoxysilane in the same manner as in Example 1 to obtain particles having a methanol hydrophobicity of 60% and an average particle diameter of 0.2 μm. ET this filler
40 μm ET containing 3 parts by weight for 100 parts by weight of FE
An FE film was formed. This film had a total light transmittance of 82.5% and a haze of 20.0%. The total light transmittance at 360 nm was 8%, and the total light transmittance at 330 nm was 8%.

This film was processed in the same manner as in Example 1 and spread as an agricultural pipe house. However, after one month, the film lost its ultraviolet ray blocking property, had a total light transmittance of 93.5% and a haze of 6.2%.
The total light transmittance at 360 nm is 86%,
The total light transmittance at 30 nm was 85%.

[0057]

According to the present invention, it is possible to obtain a fluororesin film which is excellent in transparency and has a long-term ultraviolet shielding property.

[Brief description of the drawings]

FIG. 1: 280 of the film of Example 1 before and after 3 years of expansion, and ETFE film without UV-blocker
4 shows a chart of total light transmittance from 〜700 nm.

FIG. 2 shows 28 of the film of Example 6 before and after expansion for 3 years.
4 shows a chart of total light transmittance from 0 to 700 nm.

FIG. 3 shows 28 of the film of Example 8 before and after expansion for 3 years.
4 shows a chart of total light transmittance from 0 to 700 nm.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 9/06 C08K 9/06 C09K 3/00 C09K 3/00 (72) Inventor Hideaki Miyazawa 3-chome Tsukakoshi, Saiwai-ku, Kawasaki-shi, Kanagawa 474-2 Asahi Glass Co., Ltd. (72) Inventor Sakae Yoshida 3-14-1, Funato, Itabashi-ku, Tokyo Nihonashiki Chemical Industry Co., Ltd. (72) Inventor Osamu Kumazawa 3-1-1, Funato, Itabashi-ku, Tokyo No. Nihon Muki Chemical Industry

Claims (5)

[Claims] (1) 20 to 20 parts by weight of zinc oxide
A fluororesin film comprising dispersed therein composite particles having a particle diameter of 1 to 30 μm, which are formed by assembling zinc oxide particles coated with 0 parts by weight of amorphous silica. 2. 20 to 20 parts by weight of zinc oxide
The surface of the composite particles having a particle diameter of 1 to 30 μm, in which the zinc oxide particles coated with 0 parts by weight of amorphous silica are aggregated, that the composite particles having been subjected to a hydrophobic treatment with an organosilicon compound are dispersed. Characterized fluororesin film. 3. The fluororesin is an ethylene-tetrafluoroethylene copolymer, a hexafluoropropylene-tetrafluoroethylene copolymer, a perfluoro (alkyl vinyl ether) -tetrafluoroethylene copolymer, or tetrafluoroethylene. 2. A hexafluoropropylene-vinylidene fluoride copolymer.
Or the fluororesin film of 2. 4. The fluororesin film according to claim 1, wherein a light ray having a wavelength of 330 to 360 nm is shielded by 50% or more, and a light ray having a wavelength of 400 to 700 nm is transmitted by 70% or more. 5. 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.