JPS6039018B2 - Agricultural coating film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an agricultural covering film with excellent weather resistance.

Conventionally, polyvinyl chloride film, polyethylene film, ethylene-vinyl acetate copolymer film, etc. have been used as coating films for agricultural greenhouses, tunnel houses, and munching, but these coating films are resistant to sunlight, rain and wind. The film deteriorates slightly due to exposure, and may break within two to three years at most, or even if it is not damaged, the surface may become discolored or contaminated, impairing its light transmittance, so the film must be replaced each time. There was a drawback that it had to be done.

In particular, large-scale agricultural covered houses made of steel are required to be durable and do not require replacement over a long period of time, and for this reason, many are made of glass.

However, in order to build a glass greenhouse, a sturdy frame is required that can support the weight of the glass and secure the glass in place.Also, the glass itself is hot, which makes the greenhouse expensive. there were.
As mentioned above, the present invention was made to eliminate the drawbacks of conventional agricultural covering films and to provide a film that can be used for a long period of time. The present invention relates to an agricultural coating film provided with a synthetic resin layer having a surface that prevents droplet adhesion.

Therefore, in the present invention, the fluorine-based resin film is a vinyl fluoride resin film, a vinylidene fluoride resin film,
Tetrafluoroethylene resin film, hexafluoropropylene resin film, copolymer film of tetrafluoroethylene and hexafluoropropylene, copolymer film of ethylene and tetrafluoroethylene, as side chains of each of the above resins. These include films made of resins having perfluoroalkoxy groups. These fluorine-based resin films are flexible, have excellent mechanical properties such as strength and elongation, have good light transmittance, and are less susceptible to deterioration from sunlight, so from these points of view they are superior to conventional coating films. However, since the inside of the greenhouse is hotter and more humid than the outside air, water droplets tend to adhere to the inner surface of the coating film. When water droplets adhere, they scatter sunlight, impairing the light transmittance of the coating film and hindering the growth of crops. Conventional coating films such as polyvinyl chloride films contain surfactants, and this surfactant gradually migrates to the film surface to prevent the formation of water droplets. In the case of resin films, it is difficult to mix surfactants and form them into films because the film forming temperature is high, and even if a special surfactant is used and formed into a film, Surfactants migrate to the film surface and leach out in a very short period of time, so they do not help prevent water droplet formation. Furthermore, even if corona discharge treatment, oxidation treatment with chromic acid solution, or corrosion treatment with metal sodium solution is applied, the generation of water droplets can only be prevented for several months. Therefore, in the present invention, a synthetic resin layer having a surface that prevents droplet-like adhesion of water is provided on at least one surface of the fluororesin film.

The synthetic resin layer may be any synthetic resin that can prevent water droplets from adhering to the surface and can be adhered to fluororesin films.For example, polyvinyl chloride film, polyethylene, which has been used as agricultural covering film conventionally, may be used. film, ethylene-vinyl acetate copolymer film, etc., but in the present invention, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, acrylonitrile, etc. before polymerization or a copolymer, or these monomers may be used. Acrylic resins such as copolymers of polymers and olefins, silicone resins, polyethylene terephthalate, chlorinated polyiJ
Ethylene, chlorosulfonated polyethylene, low saponification degree poval, etc. are suitable. These resins can be easily treated to prevent water droplets from adhering to their surfaces, have good weather resistance with relatively little deterioration from sunlight, etc., have good light transmittance, and are easy to combine with fluorine-based resin films. They are selected for their flexibility, chemical resistance, heat resistance, and resistance to microbial contamination. Although these synthetic resin layers deteriorate, since they are laminated to fluororesin, the strength of the coating film as a whole does not deteriorate to the extent that it is damaged, and since this synthetic resin layer is stretched toward the inside of the greenhouse, there is no chance of contamination. There is little chance of compromising transparency.

In order to prevent water droplets from adhering to the surface of these synthetic resin layers, even if a surfactant is added to the synthetic resin to form a layer, the surface of the synthetic resin layer may be treated with a corona discharge treatment or a chromic acid solution. An oxidation treatment using a metal sodium solution, a corrosion treatment using a metallic sodium solution, etc. may also be performed.

Further, if a specific resin such as POVAL with a low saponification degree of 70 to 80% is used, it is not necessary to mix a surfactant or perform surface treatment. When a surfactant is blended into the synthetic resin to prevent water droplets from adhering to the surface, any surfactant may be used as long as it is blended in conventional agricultural coating films. For example, 1COO day, group, 1C
OOM-S03 days, 1OH group, 1CON2 days, CO
Those having hydrophilic groups such as OR-○- group and -NH2 group,
Polyethylene glycol alkyl esters such as polyethylene glycol monostearate and polyethylene glycol dibehenate; sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate; bentaerythritol monostearate; Fatty acid esters of pentaerythritol such as lythritol monobehenate, polyoxyethylene fatty acid ethers such as polyoxyethylene lauryl ether, glycerin fatty acid ethers such as glycerin behenyl ether, jetanolamine atearate, etc. Fatty acid alkylolamine condensates and the like are used. Such a surfactant is blended in an amount of 0.2 parts by weight or more, preferably 1 to 5 parts by weight, based on the synthetic resin.

If the amount added is too small, the period during which water droplets can be prevented from adhering to the surface of the synthetic resin layer will be short, and if it exceeds 5 parts by weight, it will be difficult to mix evenly and the transparency and strength will decrease. Because it will come. In the present invention, the synthetic resin layer can be provided on the fluorine resin film by extrusion coating the synthetic resin layer on the fluorine resin film, by molding the synthetic resin film and dry laminating it, or by dry laminating the synthetic resin film. This can be done by coating the solution as a solution. In the case of a fluorine-based resin film having weak adhesive properties, such as a polytetrafluoroethylene polymer, it is preferable to surface-treat the film in advance to improve its adhesive properties. Further, the thickness of the fluorine resin film and the thickness of the synthetic resin layer are determined as appropriate, but the thickness of the fluorine resin film is usually 0.
0.025 to 0.1 Yanagi will suffice.

Particularly when it is used in a windy place, it is sufficient to make it thicker, but if it is too thick, it loses its flexibility and the transmission of light rays becomes poor. Furthermore, since the synthetic resin layer maintains its strength with the fluorine-based resin film, it may have any thickness. In the case of solution coating, the thickness can be several microns, and in the case of extrusion coating, the thickness may be about 0.1 micron. As mentioned above, the agricultural covering film of the present invention is a fluorine-based resin film, and a synthetic resin layer having a surface that prevents water droplet adhesion is provided on at least one surface of the fluorine-based resin film. As a result of its use, it has good strength and transparency, and this strength and transparency are maintained for a long time even when exposed to sunlight, so it can be used as an agricultural covering film for a long time without needing to be replaced. .

In addition, since a synthetic resin layer having a surface that prevents water from adhering in the form of droplets is provided on one side of this fluorine-based resin film,
If this synthetic resin layer is applied to the inside of an agricultural greenhouse, even if the inside of the greenhouse becomes hot and humid and dew condenses on the inner surface of the coating film, it will form a layer that forms drops and will not scatter light. It does not impair the transmission of light. Since it maintains its strength and transparency over a long period of time, it is possible to create an agricultural greenhouse that does not require replacement over a long period of time by simply covering the frame of a conventional agricultural greenhouse, and compared to glass greenhouses, Can be done cheaply.

Furthermore, since the fluorine-based resin film has a low transmittance to far infrared rays, it can prevent the far infrared rays emitted from the ground inside the house from dissipating outside the house at night, and has the effect of keeping the inside of the house warm. Next, examples of the present invention will be shown.

Example 1 One side of a polyvinyl fluoride film with a thickness of 0.025 mm was surface-treated to improve adhesion, and this surface was coated with a copolymer of methyl methacrylate and 2-ethylhexyl acrylate with surface activity. A synthetic resin layer having a side thickness of 0.025 mm and containing 2% by weight of pentaerythritol monostearate as an agent was laminated by extrusion coating to produce the agricultural coating film of the present invention.

The synthetic resin layer side of this film was exposed to a sunshine weatherometer (the rainfall cycle was set to 18 minutes out of 12 minutes,
At a spray pressure of 1.0k9/, nozzle No. 1)
After accelerated deterioration, the synthetic resin layer was placed inside and heated for 6,000 hours.
A thermostatic water tank was surrounded and the top surface was tilted at an angle of 35 degrees with respect to the horizontal plane, and the structure was placed in a sealed state.

When the state of adhesion of water droplets to the inner surface of the coating film was examined, no adhesion of water droplets was observed even after an exposure time of 300 hours in the field (equivalent to 5 years outdoors). Furthermore, almost no decrease in strength or elongation or discoloration of the coated film was observed. As a comparative example, we investigated the state of adhesion of water droplets using a 0.05 willow polyvinyl fluoride film and a film whose surface was treated with an etchant containing metallic sodium. Water droplets adhered to the entire inside surface.

Claims (1)

[Scope of Claims] 1. An agricultural covering film comprising a synthetic resin layer having a surface that prevents water droplets from adhering on one side of a fluorine-based resin film. 2. The agricultural coated film according to claim 1, wherein the synthetic resin layer is an acrylic resin containing 1 to 5% by weight of a surfactant.