JPH10292056A - Fluororesin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluororesin film which efficiently diffuses light and has ultraviolet screening properties by dispersing composite particles each having a structure of, from the outermost layer, amorphous silica-cerium oxide-base pigment in a fluororesin. SOLUTION: Particles formed by coating base pigment particles selected from among silica, talc, and mica and having an average size of 1-3 μm with an insoluble cerium compd. and then with an amorphous silica are baked at 200-1,000 deg.C and if necessary treated with a surface treating agent to give composite particles each having a structure of, from the outermost layer, amorphous silica-cerium oxidebase pigment and adjusted to a methanol hydrophobization degree of 40-75%. The objective fluororesin film is obtd. by dispersing 0.4-5 pts.wt. above-prepd. composite particles in 100 pts.wt. fluororesin (e.g. an ethylene-tetrafluoroethylene copolymer or a hxafluoropropylene- tetrafluoroethylene copoymer) and converting the resultant compsn. into a film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin film excellent in light diffusing property and ultraviolet ray cutting property.

[0002]

BACKGROUND OF THE INVENTION Fluororesins, especially tetrafluoroethylene copolymer fluororesins, are used in agricultural house films as materials whose weatherability, transparency and stain resistance are maintained for more than 20 years of outdoor exposure. ing.

[0003] Fluorine resin films are 280-700n
Since it has a high transmittance of ultraviolet and visible light and a high light amount, it is suitable as an agricultural house film for growing melon or strawberry.

When used as an agricultural house film,
The types of fruits, flowers, vegetables, etc. to be cultivated include their color, sugar content,
In order to improve the yield or prevent the occurrence of pests and insects, there is a demand for a film whose ultraviolet transmittance and light diffusivity are adjusted.

[0005] When a film obtained by ordinary film forming and having a smooth surface is used, the above shaded portion is generated due to a small amount of diffused light. In an agricultural house called a tunnel house or a pipe house, which has many pillars supporting a film, there is a problem that these pillars create a place where sunlight does not shine, and the crops grown in the shade become poorly grown.

[0006] As a method of imparting an ultraviolet ray cut function to a tetrafluoroethylene copolymer, titanium oxide having a particle diameter of 0.01 to 0.05 µm is added to an ethylene-tetrafluoroethylene copolymer (hereinafter referred to as ETFE). (Japanese Patent Laid-Open Publication No. Hei 3-10193)
3).

According to this method, titanium oxide is dispersed and kneaded in ETFE without surface treatment, so that titanium oxide particles are not only aggregated but also react with a small amount of hydrogen fluoride gas generated at the time of melting and kneading with ETFE to form black. There was a problem of becoming. The blackening of the film lowers the total light transmittance, resulting in poor growth of the plant to be cultivated.

In adjusting the light diffusivity, a method is generally employed in which irregularities are formed on the film surface during film formation and irregular reflection on the surface is utilized. Since the unevenness of the film surface is determined by the pattern of the unevenness of the embossing roll to be used, it is necessary to pay close attention to the shape management of the roll in order to make the unevenness with good reproducibility.

[0009]

SUMMARY OF THE INVENTION The present invention provides a fluororesin film which efficiently generates diffused light and has an ultraviolet cut property.

[0010]

According to the present invention, an average particle size of 1 to 1 is provided.
A fluororesin film comprising a composite particle having a structure of amorphous silica-cerium oxide-based pigment dispersed from a 3 μm outermost layer in a fluororesin.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The base pigment of the composite particles used in the present invention is selected from silica, talc and mica. The light refractive index of these base pigments is usually about 1.5 to 1.6.

The base pigment preferably has a spherical shape in order to have a high light diffusion effect, but preferably has a flat structure in order to also have an effect of cutting off ultraviolet rays. Generally, when a flat base pigment is formed into a film, the longitudinal direction of the flat particles is oriented perpendicular to the thickness direction of the film. For this reason, if the surface of the particles of the base pigment is coated with cerium oxide, the blending amount is small and a large ultraviolet ray cutting effect can be obtained.

Further, if the cerium oxide coating amount on the particle surface of the base pigment is the same, the ultraviolet ray cutting ability is almost the same regardless of the base pigment, but the effect of light diffusion differs depending on the type of the base pigment. Therefore, by using one type of base pigment alone or dispersing it in combination with a fluororesin, a fluororesin film having various ultraviolet ray cutting and light diffusing capabilities can be formed.

The base pigment particles have an average particle size of 1 to 3 μm.
m. The average particle size here refers to a value of 50% as measured by a laser diffraction / scattering type particle size distribution analyzer and accumulated from small particle sizes.

In general, those having an average particle size of about 0.5 μm have a weak light diffusion effect, while those having an average particle diameter of about 10 μm have stronger reflected light and absorbed light than light diffusion, and lower light transmittance. .

The particles having the surface of the base pigment coated with cerium oxide are produced by coating the base pigment particles with an insoluble cerium compound. The insoluble cerium compound is a cerium compound that is insoluble in water, and examples thereof include cerium hydroxide, cerium phosphate, and cerium carbonate. Among them, preferred is cerium hydroxide.

For the particles having the base pigment particles coated with an insoluble cerium compound, for example, the base pigment is dispersed in water, an aqueous cerium nitrate solution is dropped while heating the aqueous base pigment dispersion, and then sodium hydroxide is added. By dropping the aqueous solution so that the pH becomes 7 to 9, cerium hydroxide can be deposited on the surface of the base pigment particles to produce the pigment. In order to uniformly coat the insoluble cerium compound on the base pigment having an average particle diameter of 1 to 3 μm, about 20 to 60 parts by weight of cerium nitrate is added to 100 parts by weight of the base pigment.

The amorphous silica-cerium oxide-based pigment particles used in the present invention are baked products of particles obtained by coating the above-mentioned base pigment with an insoluble cerium compound and further coating the particles with amorphous silica.

The amorphous silica is an amorphous silica having no crystallinity, and specific examples include amorphous silica obtained by hydrolyzing sodium silicate.

As an example of the production of the composite silica, for example, particles obtained by coating the base pigment with an insoluble cerium compound are then filtered, washed with water, and dried. Thereafter, the particles are again made into an aqueous dispersion using a disperser or an emulsifier, and the silicate solution is dropped into the aqueous dispersion while stirring to obtain silica-coated particles. Thereafter, it is dried, and further, 200 to 1000
C., preferably at 400 to 600.degree. C. for 2 hours. By this calcination, the insoluble cerium compound becomes cerium oxide, and a composite having a three-layer structure of amorphous silica-cerium oxide-based pigment is obtained from the outermost layer (hereinafter, referred to as composite). In addition, as a silicate solution, No. 3 sodium silicate is mentioned, for example.

The average particle size of the obtained composite particles is 1 to 3 μm.
m, the same as the particles of the base pigment.

By coating the amorphous silica,
It can weaken the catalytic action of cerium oxide and suppress thermal degradation and light degradation of the fluororesin. Further, when the composite is kneaded and dispersed in a fluororesin to form a fluororesin film,
Coloring of the fluororesin film can be prevented and dispersibility can be improved.

The amount of the amorphous silica is preferably 10 to 50 parts by weight based on 100 parts by weight of the base pigment coated with the insoluble cerium compound. When the amount is less than 10 parts by weight, the surface of the cerium oxide cannot be uniformly coated, and when the amount exceeds 50 parts by weight, aggregates of only amorphous silica are generated.

In the present invention, the surface of the composite particles is preferably treated with a surface coating agent to control the degree of hydrophobicity of methanol in order to prevent the composite from aggregating during melt-kneading with the fluororesin.

The degree of hydrophobicity of the composite particles with methanol is 40.
-75% is preferable, and 60-70% is particularly preferable. If the composite particles have a low degree of methanol hydrophobicity, the dispersibility of the composite particles in the fluororesin is low, and the composite particles are likely to be colored. The required degree of methanol hydrophobicity required varies slightly depending on the type of fluororesin.
It is preferably 0%, and in the case of a hexafluoropropylene-tetrafluoroethylene-based copolymer or a perfluoro (alkyl vinyl ether) -tetrafluoroethylene-based copolymer, the content is preferably 60 to 75%. 40-70% in the case of a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer
It is preferable that

As the above-mentioned surface coating agent, any one can be used as long as it can firmly bind to the surface of the composite particles and can increase the degree of hydrophobicity. Preferably, a hydroxyl group or a hydrolyzable group is directly bonded to a silicon atom. Reactive silicon compounds are used. More preferably, an organosilicon compound having such a hydroxyl group or a hydrolyzable group and having a hydrophobic organic group bonded to a silicon atom by a carbon-silicon bond is used.

Incidentally, in a usual silane coupling agent,
This organic group has a reactive functional group (for example, an epoxy group, an amino group, etc.), but such a reactive functional group is often highly hydrophilic, and is thus less preferable as the surface coating agent in the present invention. Absent. Rather, an organosilicon compound having, as an organic group, a hydrocarbon group having no reactive functional group or hydrophilic group, or a fluorinated hydrocarbon group providing high hydrophobicity is preferred.

Examples of the hydrolyzable group in the organosilicon compound include an alkoxy group, an acyloxy group, an amino group, an isocyanate group and a chlorine atom.
The following alkoxy groups are preferred. This hydrolyzable group is
It is preferable that 1 to 4, especially 2 to 3, bonds are bonded to the silicon atom.

As the organic group bonded to the silicon atom through a carbon-silicon bond, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, a fluoroalkyl group, a fluoroaryl group and the like are preferable. Particularly, an alkyl group having 2 to 20 carbon atoms and 2 to 2 carbon atoms having 1 or less fluorine atoms.
A fluoroalkyl group of 0, a phenyl group which may be substituted with an alkyl group or a fluoroalkyl group, or the like is preferable.

The organosilicon compound may be an organosilicone compound having a hydroxyl group or a hydrolyzable group 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 as a surface coating agent include tetraalkoxysilanes such as tetraethoxysilane and tetramethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, and the like.
Examples include trialkoxysilanes such as (3,3,3-trifluoropropyl) trimethoxysilane and silicone oils such as dimethyl silicone oil, methyl hydrogen silicone oil and phenylmethyl silicone oil. Of these, isobutyltrimethoxysilane , Hexyltrimethoxysilane and dimethyl silicone oil are preferred.

The treatment amount of the surface coating agent is proportional to the specific surface area of the composite particles. If the treatment amount is small, the particles turn black or brown when kneaded with the fluororesin,
Conversely, when the treatment amount is large, aggregates formed of the surface coating agent appear as lumps, and the film appearance may be deteriorated. Further, since the degree of methanol hydrophobicity of the obtained particles changes depending on the amount of treatment of the surface coating agent, it is necessary to adjust the amount of treatment so as to achieve the above-mentioned degree of methanol hydrophobicity.

The methanol hydrophobicity is an index indicating the hydrophobicity of the particles. The measuring method is as follows. That is, put 50 cc of distilled water into a 300 cc beaker,
g of particles are charged with good stirring. If the particles are dispersed uniformly, 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. Total amount of methanol added until it is just uniformly dispersed (unit: cc)
Thus, the methanol hydrophobicity D (unit:%) is determined by the following equation. D = 100M / (M + 50)

The dispersion amount of the surface-treated cerium oxide composite particles dispersed in the fluororesin film of the present invention may be in the range of 0.4 to 5 parts by weight, preferably 100 parts by weight of the fluororesin. Is 0.5 to 3 parts by weight.

Various fluororesins can be used as the fluororesin in which the surface-treated composite is dispersed. Specific examples thereof include a vinyl fluoride polymer, a vinylidene fluoride polymer, a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, and a tetrafluoroethylene copolymer. Ethylene-propylene-based copolymer, tetrafluoroethylene-vinylidene fluoride-propylene-based copolymer, E
Examples include TFE, hexafluoropropylene-tetrafluoroethylene copolymer, and perfluoro (alkyl vinyl ether) -tetrafluoroethylene copolymer.

The thickness of the fluororesin film is not particularly limited, but is usually in the range of 5 to 500 μm, preferably 10 to 500 μm.
２００200 μm.

The obtained film can be used for an agricultural house film, an agricultural tunnel house, an agricultural pipe house, a curtain in a house, and the like.

[0038]

Next, the present invention will be described with reference to examples. In the examples, an example of a film in which the total light transmittance of ultraviolet light at 320 nm is about 20% for an agricultural house is shown. However, the ultraviolet light cutoff property and light diffusion property are particularly limited to this example. There is no.

Example 1 Amorphous silica-cerium oxide-talc composite (Nippon Inorganic Chemical Co., Serigard T-30)
200 g of 18-02, average particle size 1.8 μm) was put into a small Henschel mixer, and 14 g of isobutyltrimethoxysilane was subsequently added to water: methanol = 1: 9 (weight ratio).
Was slowly added and stirred for 10 minutes. Subsequently, the wet particles were dried at 120 ° C. for 1 hour and sufficiently loosened again with a small Henschel mixer for 2 minutes to obtain Composite 1. In addition, Serigard T-3018-0
In No. 2, the talc content of the base pigment is 59% by weight, the cerium oxide content is 21% by weight, the amorphous silica content is 19% by weight, and the alumina content is 1% by weight.

The complex 1 has a methanol hydrophobicity of 50.
%. 60 g of the composite 1 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. using a twin-screw extruder.

Then, at 320 ° C., 60 μm by T-die method.
m was formed. This film had a total light transmittance of 90.9% and a diffuse light transmittance of 38.4%.
The total light transmittance at 0 nm was 22%. FIG. 1 shows the total light transmittance and the parallel light transmittance. The difference between the total light transmittance and the parallel light transmittance is the diffuse transmittance, which indicates light diffusion.

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. An agricultural pipe house with this film spread was created, and spinach was cultivated therein.

The pillars supporting the film were not shadowed due to light diffusion, and the spinach grew well regardless of where it was grown. In addition, no wilt was observed because the ultraviolet rays were cut off.

Example 2 Amorphous silica-cerium oxide-silica composite (Nippon Inorganic Chemical Co., Ltd., Celigard S-30)
18-02, average particle size 2.2 μm) 200 g was charged into a small Henschel mixer, and then 14 g of isobutyltrimethoxysilane was added to water: methanol = 1: 9 (weight ratio).
Was slowly added and stirred for 10 minutes. Subsequently, the wet particles were dried at 120 ° C. for 1 hour, and sufficiently loosened again with a small Henschel mixer for 2 minutes to obtain a composite 2. In addition, Serigard S-3018-0
In No. 2, the amount of silica in the base pigment is 59% by weight, the amount of cerium oxide is 21% by weight, the amount of amorphous silica is 19% by weight, and the amount of alumina is 1% by weight.

The methanol hydrophobization degree of this complex 2 was 50.
%. 60 g of the composite 2 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. using a twin-screw extruder.

Then, at 320 ° C., 60 μm by T-die method.
m was formed. This film has a total light transmittance of 92.3%, a diffuse light transmittance of 31.3%, and 32
The total light transmittance at 0 nm was 22%. FIG. 1 shows the total light transmittance and the parallel light transmittance.

The obtained film was subjected to a corona discharge treatment, and a droplet of 0.2 μm containing silica fine particles and a silane coupling agent as main components was applied. Then, an agricultural pipe house with this film spread was created, and spinach was cultivated therein.

The pillars supporting the film were not shadowed due to light diffusion, and the spinach grew well regardless of the place where it was grown. In addition, no wilt occurred because the ultraviolet rays were cut off.

[Comparative Example 1] Only ETFE (Aflon COP88AX manufactured by Asahi Glass Co., Ltd.) was heated at 320 ° C. by a T-die method.
To form a 60 μm film. This film had a total light transmittance of 94.3%, a diffuse light transmittance of 4.8%, and a total light transmittance at 320 nm of 87%. FIG. 1 shows the total light transmittance and the parallel light transmittance.

The obtained film was subjected to a corona discharge treatment, and a droplet of 0.2 μm containing silica fine particles and a silane coupling agent as main components was applied. Then, an agricultural pipe house on which the film was spread was created, and spinach was cultivated therein.

[0051] Due to the small amount of diffused light, the shadows of the pillars supporting the film were formed, and poor growth was observed in spinach cultivated in a place where sunlight was difficult to reach. In addition, wilt disease occurred because ultraviolet rays were not cut.

[0052]

According to the present invention, a fluororesin film having an excellent ultraviolet-cutting property and light diffusing effect can be obtained.

[Brief description of the drawings]

FIG. 1 shows a film 7 of Example 1, Example 2, and Comparative Example 1.
4 shows a chart of total light transmittance from 00 nm to 280 nm and parallel light transmittance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 27/12 C08L 27/12

Claims (3)

[Claims] 1. A fluororesin film comprising composite particles having an amorphous silica-cerium oxide-based pigment constitution dispersed in a fluororesin from the outermost layer of particles having an average particle diameter of 1 to 3 .mu.m. 2. The composite particles having a methanol hydrophobicity of 40 to 40.
The fluororesin film according to claim 1, which is 75%. 3. The fluororesin is an ethylene-tetrafluoroethylene copolymer, a hexafluoropropylene-tetrafluoroethylene copolymer, a perfluoro (alkyl vinyl ether) -tetrafluoroethylene copolymer or a tetrafluoroethylene copolymer. 3. The fluororesin film according to claim 1, which is a hexafluoropropylene-vinylidene fluoride copolymer.