Plant husbandry – Cover – shade – or screen – Adjustable on supporting structure or having means allowing...
Patent
1996-08-20
1998-06-30
Carone, Michael J.
Plant husbandry
Cover, shade, or screen
Adjustable on supporting structure or having means allowing...
47 17, A01G 914
Patent
active
057716307
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an agricultural covering material, particularly to an agricultural covering material which partially intercepts the rays of particular wavelength ranges and which can be used in a spread state over a long period of time.
BACKGROUND ART
There have been used, as covering materials for plastic tunnel or pipe house, a polyethylene film, an ethylene-vinyl acetate copolymer film, a polyester film, a vinyl chloride resin film, etc. A vinyl chloride resin film occupies a major portion because of the applicability, price, heat-insulatability, etc. Since these resins have inferior outdoor durability, they are used for 1-2 years and farmers replace the covering materials every 1-2 years.
Full-scale large houses have been used in recent years for the purposes of labor saving for house management, enlargement of cultivation area, cultivation of higher quality crops, prolongation of house life, etc. In these large houses are used, as covering materials durable for about 5 years, such covering materials as polyester resin panel, polycarbonate resin panel, hard vinyl chloride resin panel, acrylic resin panel, fiber-reinforced plastic panel and the like. Since these covering materials have a large thickness, they have drawbacks in that they must use a specially made large base material and be spread, making the application very complicated and moreover they are relatively expensive. A polyester resin panel, a polycarbonate resin panel, a hard vinyl chloride resin panel, an acrylic resin panel, etc. have further problems in that they tend to generate cracks when hit by hail, etc. and the cracks tend to propagate.
Also, flat glass is used as a durable covering material which can be used for 10 years or more. Flat glass, however, has problems in that it is expensive and, moreover, it is broken easily and, once broken, the soil inside house must be replaced to remove the fine pieces of broken glass.
In order to solve these problems, Japanese Patent Application Kokai (Laid-Open) No. 43535/1989, for example, proposes an agricultural covering material comprising a fluororesin film.
While the above-mentioned conventional agricultural covering materials contain a small amount of an ultraviolet absorber for improvement of the weatherability and generally have a property of intercepting the ultraviolet rays of sunlight to some extent, a fluororesin film has excellent weatherability by itself and accordingly requires no use of any weatherability improver (e.g. ultraviolet absorber) therein. Consequently, an agricultural covering material comprising a fluororesin film transmits even the ultraviolet rays of sunlight. Therefore, when the crop for in-house cultivation which had been subjected to breeding so as to fit the cultivation in a house covered with a conventional agricultural covering material capable of intercepting ultraviolet rays to some extent, was cultivated in a house covered with a fluororesin film, there have arisen new problems not experienced with conventional agricultural covering materials, such as delay of growth or harvesting time, reduction in quality of harvest owing to, for example, the hardening of stem and leaf or of fruit, flower color darkening or discoloration of flowers and ornamental plants, and the like.
Fluororesin films are superior in mechanical strengths, transparency, weatherability, etc. and are best suited as a base material for use in an agricultural covering material which can be used in a spread state over a long period of time, for example, 10 years or more. Hence, the present inventors made a study in order to solve the above-mentioned problems possessed by an agricultural covering material comprising a fluororesin film.
It is thought, as one mean for solving the problems, to use an ultraviolet absorber in a fluororesin film as in the case of conventional agricultural covering materials. However, fluororesins have a high melt-processing temperature and it is practically difficult to use therein an organic ultraviolet absorber such as used in
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patent: 3857804 (1974-12-01), Glahi et al.
patent: 3911620 (1975-10-01), Glahi
patent: 4266370 (1981-05-01), Kodera et al.
patent: 4965302 (1990-10-01), Hirahara et al.
patent: 5482986 (1996-01-01), Ogiso et al.
Harasawa Isamu
Ishisaki Yoshiaki
Oonishi Yasuaki
Carone Michael J.
Nippon Carbide Kogyo Kabushiki Kaisha
Pezzuto Robert
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