JPH05239239A - Translucent synthetic resin film - Google Patents

Abstract

PURPOSE:To provide a film adapted for preventing misty water drops from forming near its surface and for preventing its surface from being clouded by water drops CONSTITUTION:The objective film is a thin film made from a transparent synthetic resin and having fine hollows each having a width of 1-20mum and a depth of 1-10mum throughout at least one of the surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent synthetic resin film. Specifically, it is a film applied when it is necessary to avoid adhesion of water droplets on the film surface or when antifogging property is required.
The present invention relates to a transparent synthetic resin film used as a covering material for agriculture.

[0002]

2. Description of the Related Art Conventionally, as a film for agriculture, a film made of a synthetic resin having excellent heat retention and weather resistance has been widely used as a covering material for greenhouses for useful plant cultivation, tunnels and the like. The synthetic resin film is superior to the glass plate covering material in that it is light and inexpensive. Also, in this field of application, a film having a large light transmittance is preferred,
The antifogging property of the film is important. Fogging is mainly due to the phenomenon that water in the air in a house or tunnel is condensed and adheres to the film surface as water drops.

An antifogging agent is included in the synthetic resin substrate for the purpose of preventing water droplets from forming on the inner surface of the film (the side facing the inside of the house or tunnel), but when the temperature difference between the inside and outside of the film becomes large, A phenomenon in which fog is generated is observed near the inner surface of the film. Such a fog phenomenon reduces the transparency of the film, and also causes the occurrence of disease by wetting the leaves, stems, flowers, fruits, etc. of useful plants cultivated in greenhouses and tunnels. It also helps.

As a method for preventing the generation of fog and fog near the inner surface of the film, as described in JP-A-57-12070 and JP-A-57-14648, an anti-fog agent and a silicone-based agent are used. A method of using a compound or an antifogging agent and a fluorine-containing compound in combination has been proposed. However, when a combination of an antifogging agent and a silicon compound, or a fluorine-containing compound is used in combination, the antifogging property may be adversely affected, especially when the use is started from high temperature summer or early autumn. In some cases, the deterioration of the antifogging property is promoted, and the antifogging durability may be remarkably inferior.

[0005]

Under the circumstances, the present inventors have been able to prevent the generation of water droplets in the form of mist for a long period of time, have good antifogging sustainability, and have a light transmittance of the fill. As a result of extensive studies aimed at providing a film having performance that does not deteriorate, it was discovered that the above-mentioned object was achieved by forming the surface of a transparent synthetic resin film into a special shape, and the present invention was reached. did.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is, however, a thin film made of a transparent synthetic resin, which has a width of 1 to 20 μm across at least one surface thereof. , A transparent synthetic resin film having minute recesses with a depth of more than 1 μm and 10 μm or less.

The present invention will be described in detail below. In the present invention, the synthetic resin may be a resin having excellent transparency, for example, olefins such as ethylene, propylene, butene, pentene, vinyl chloride, vinyl acetate, vinyl alcohol, acrylic acid and its derivatives, and methacrylic acid. Monomers or copolymers of its derivatives, vinyl compounds such as styrene and its derivatives, and diene compounds such as butadiene and cyclopentadiene; polyesters; polyamides; polymers such as polycarbonate or polyimide; It means a blended product.

To produce a film from a synthetic resin, a melt extrusion method, a solution casting method, a calender method, a laminating method or the like may be adopted. Synthetic resin, prior to forming a film, various known resin additives, such as plasticizers, heat stabilizers,
Anti-fog agents, anti-fog agents, lubricants, ultraviolet absorbers, light stabilizers, antioxidants, fillers, dyes, pigments and the like can be blended and contained.

The film of the present invention preferably contains an antifog agent in order to more effectively suppress the generation of fog. As the anti-fog agent, there are conventionally used silicon compounds, fluorine-containing compounds and the like. Silicon-based compounds include silicone oil and organic siloxane-based surfactants, and fluorine-containing compounds include:
Examples thereof include fluorine-based surfactants and copolymerized oligomers of unsaturated esters containing a polyfluoroalkyl group and other compounds. The thickness of the film may be appropriately determined according to the conditions for forming the recesses, but a range of 0.02 to 5 mm is preferable.

In the present invention, in order to form the concave portion on the surface of the transparent synthetic resin film, ion beam etching, photo etching (combination of photoresist and etching), photo electro A method of forming (a combination of photoresist and electroforming) or a method of embossing after forming an uneven metal mold by cutting or the like may be used. The minute recesses on the synthetic resin film surface have a width of 1 to 20 μm and a depth of more than 1 μm and 10 μm.
It is preferably m or less, and particularly preferably, the width of the recess is 5 to 20 μm and the depth of the recess is 2 to 5 μm. If the width of the recess exceeds 20 μm or the depth exceeds 10 μm, the function of preventing fog formation near the surface decreases, and
When the width of the recess is less than 1 μm or the depth is less than 1 μm, the antifogging durability is insufficient.

The shape of the recess may be a groove or a depression. When the film is formed in a groove shape, the arrangement on the film surface may be parallel, concentric, spiral, lattice-like, or the like. Further, in the case of forming a depression, the shape on the film surface may be a circle, an ellipse, a triangle, a quadrangle, and the like, and each depression may be independent, but it is preferable to disperse them uniformly. The ratio of the recessed area to the surface on which the recessed portion is formed is preferably 30% or more from the viewpoints of the fog-preventing ability and the antifogging sustainability, and particularly 5
It is preferably 0% or more.

The recesses on the surface of the synthetic resin film may be formed on both sides or only on one side depending on the usage of the film. A film in which the recesses are linear grooves formed in parallel to each other and whose cross section is V-shaped or U-shaped is easier to manufacture than other types of films, and therefore, it is recommended.

When the transparent synthetic resin film according to the present invention is used as a film for agricultural houses or tunnels, the film is stretched with the surface having the recesses formed inside.
When a predetermined concave portion is formed on the inner surface of the film, water droplets are easily condensed in the concave portion, so that fog generation near the inner surface of the film can be prevented. Further, the presence of the concave portions also improves the antifogging sustainability. When the film of the present invention is used as an agricultural film, it is preferable to use a substrate containing an antifogging agent in order to further improve the antifogging property. Further, in order to improve the dustproof property on the outer side of the stretched film, it is also effective to form a dustproof film based on a solvent paint, a water-soluble paint, an ultraviolet curable paint or the like.

The film of the present invention can be applied also in fields other than agriculture, such as when it is necessary to avoid adhesion of water droplets, when antifogging property is required, or when water repellency is required. For example, it is possible to improve the antifogging property by laminating the film of the present invention on a glass plate, a plastic sheet or film, a woven fabric or a non-woven fabric. Therefore, it is considered that the film of the present invention can be advantageously used also for boards and panels for which dew condensation prevention is required for construction, sports or work goggles, raincoats for rainwear, umbrellas and the like.

[0015]

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Examples 1-4, Comparative Examples 1-6 I. Film manufacturing

[0016]

[Table 1]

The basic composition shown in Table 1 is mixed with the antifog agent shown in Table 2 as needed, mixed with a supermixer and fed to a calender roll heated to 180 ° C. to have a thickness of 0.1 mm. 10 kinds of films were prepared.

[0018]

[Table 2]

II. Formation of recesses By photo-etching (cutting in the comparative example), FIG.
An embossing roll having the shape shown in Table 2 and having a pitch and a grain height of 210 mm in diameter shown in Table 2 was prepared and used as a water-cooled embossing roll. The film produced in I was heated with an infrared heater to the temperature shown in Table-2, the film was passed between a water-cooled embossing roll and a water-cooling rubber roll under a pressure of 0.5 kg / cm, and a recess was formed on one side. Formed. The grain shape of the film was measured with a three-dimensional surface roughness meter (TOPO-3D) manufactured by Matsu Trading Equipment Co., Ltd., and the area ratio of the recessed area was calculated by the power spectrum. It was shown to.

III. Evaluation of film <Fog generation test> Frontage of 5.4 m in a field in Isshi-gun, Mie prefecture
Build 10 pipe houses with 3m height and 15m depth,
Each building was coated with the concave surface of the test film inside (September 29, 1990). For the evaluation of the degree of fog generation, one day after coating the film on the pipe house, 5 days (October 29th to November 2nd, 1990), and 5 days after 4 months (January 28th, 1991) Sunday-February 1) and 5 days after 6 months have passed (April 1-April 5, 1991).

The numerical values of "evaluation of fog generation" have the following meanings. “1”: No fog was found in the house, or a very small amount was generated near the inner surface of the film. “2”: Fog is generated over the entire house, but the back of the house 15 m ahead can be clearly identified. “3”: A state where fog was generated in the entire house in a slightly thicker area and the back of the house 15 m ahead could not be clearly identified. "4": The fog was heavily generated over the entire house, and the inside of the house 15 m ahead could not be identified at all. Show the average value of the values for 5 days when observing the fog generation condition-
3 shows.

[0022]

[Table 3]

<Evaluation of anti-fog property> In a field in Nagoya City, Aichi Prefecture, in a single roof house with a frontage of 2 m, a building height of 2 m and a depth of 30 m, 10 kinds of test films were placed on the concave surface on September 14, 1990. After coating, the antifogging property of each film was visually observed and evaluated periodically with the naked eye. The results are shown in Table-3. The numerical values of "evaluation of antifogging property" have the following meanings. “1”: Water adhered in a thin film form, and no water droplet was observed. "2": Water adhered in a thin film, but slightly large water droplets were observed. "3": A state in which adhesion of fine water droplets is partially recognized. "4": A state in which fine water droplets are recognized on the entire inner surface of the film.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embossing roll used in an example.

[Explanation of symbols]

 p pitch h grain height

Claims (12)

[Claims] 1. A thin film made of a transparent synthetic resin, wherein minute recesses having a width of 1 to 20 μm and a depth of more than 1 μm and 10 μm or less are formed over at least one surface thereof. Transparent synthetic resin film. 2. The film according to claim 1, wherein the total area of the minute recesses is 30% or more of the area of the film surface on which the recesses are formed. 3. The film according to claim 1, wherein the recesses are linear grooves formed in parallel with each other. 4. The film according to claim 3, wherein the transverse cross section of the groove is V-shaped or U-shaped. 5. The film according to claim 1, wherein the film has a thickness of 0.02 to 5 mm. 6. A thin fill film made of a transparent synthetic resin, having a width of 1 over the entire surface of at least one of the surfaces.
-20 μm, a fine recess having a depth of more than 1 μm and 10 μm or less is formed, and the total area of the fine recess is 30% or more with respect to the area of the film surface on which the recess is formed. Cloudy film. 7. The film according to claim 6, wherein the recesses are linear grooves formed in parallel with each other. 8. The film according to claim 7, wherein the transverse cross section of the groove is V-shaped or U-shaped. 9. The film of claim 6, wherein the film has a thickness of 0.02 to 5 mm. 10. A thin film made of a transparent synthetic resin, wherein a recess having a width of 1 to 20 μm and a depth of more than 1 μm and 10 μm or less is formed across at least one surface of the thin film. , Transparent synthetic resin coating material. 11. The covering material according to claim 10, wherein the total area of the concave regions is 30% or more of the area of the film surface on which the concave portions are formed. 12. A thin fill film made of a transparent synthetic resin, wherein minute recesses having a width of 1 to 20 μm and a depth of more than 1 μm and not more than 10 μm are spread over at least one surface thereof. Micro-recesses having parallel V-shapes and a V-shaped or U-shaped cross-section in the width direction of the recesses are formed, and the total area of the micro-recesses is the area of the film surface on which the recesses are formed. 30% or more,
A film for coating agricultural houses or tunnels, which has a film thickness of 0.02 to 5 mm.