Plant husbandry – Water culture – apparatus or method – Porous support
Reexamination Certificate
2001-03-27
2003-05-13
Jordan, Charles T. (Department: 3644)
Plant husbandry
Water culture, apparatus or method
Porous support
Reexamination Certificate
active
06560923
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an aqueous artificial medium being preferably suitable as a substitute medium for soil, which is used for a plant (or vegetable) such as a potted plant and a cut flower.
BACKGROUND ART
It is already known that a water-absorbing polymer is used in a medium for a plant. For example, a polymer based on a crosslinked polyacrylate, a starch/polyacrylate or the like is mixed with a part of soil and used as the medium. If this is used as the medium being suitable for cultivation of a plant, it is particularly necessary that water-holding property and water-supplying property provided by the water-absorbing polymer is well-balanced or the like. From such a viewpoint, a water-absorbing polymer having an improved performance has been recently proposed.
For example, JP-A 8-256592 teaches an artificial medium blended with 0.3 to 10% by weight of a crosslinked homopolymer or copolymer based on N-vinyl carboxylic acid amide. The polymer has a well-balanced ability to hold water and to supply water to a plant and are considered to have no influence on growth of the plant, too. Further, JP-A 8-266147 discloses that, by incorporation of about 0.1 to 10% by weight of a crosslinked polymer such as a poly N-substituted (meth)acrylamide-derivative showing temperature-dependent equilibrium water adsorption ratio into a medium, the amount of supplied water is regulated depending on a change in the temperature.
When the water-absorbing polymer, particularly a polyacrylic acid-based anionic water-absorbing polymer, is used in the artificial medium, the polyacrylic acid remaining generally as a soluble component exerts an adverse effect on the plant, thus often causing insufficient growth. Further, it is known that the growth of the cut flower is inhibited by a waste matter derived from the plant, by colloidal particles in tap water, or by microbial germinal, bacterial, etc.) growth. To solve such a problem, the artificial media composed exclusively of the water-absorbing polymer(s) is unsatisfactory and hardly exhibits a cultivation ability equivalent to that of soil.
DISCLOSURE OF INVENTION
The present invention provides an aqueous artificial medium and a polymer composition comprising 0.01 to 10% by weight of a water-absorbing polymer and 0.001 to 10% by weight of a cationic polymer. The present invention provides the aqueous artificial medium and the polymer composition further comprising a porous water-supplying support having a communicating hole. When the balance is water, tap water is usually used, but purified water, deionized water or the like can also be used.
Preferably, the water-absorbing polymer is selected from an anionic polymer, a nonionic polymer and a mixture thereof. It may contain a porous water-supplying support having a communicating hole. The ratio by weight of the water-absorbing polymer: the cationic polymer may be from 1:0.01 to 1:10. It may further comprise a fertilizer.
The present invention provides a method of growing a plant in an aqueous artificial medium comprising 0.01 to 10% by weight of a water-absorbing polymer and 0.001 to 10% by weight of a cationic polymer, as well as use of a polymer composition comprising a water-absorbing polymer and a cationic polymer for an aqueous artificial medium.
Further, the present invention relates to a polymer composition for an aqueous artificial medium comprising a water-absorbing polymer and a cationic polymer at a ratio of from 1:0.01 to 1:10 by weight, as well as an aqueous artificial medium material comprising a polymer composition for an aqueous artificial medium comprising a water-absorbing polymer and a cationic polymer at a ratio of from 1:0.01 to 1:10 by weight and a porous water-supplying support having a communicating hole.
MODES FOR CARRYING OUT THE INVENTION
The water-absorbing polymer used in the present invention is a product rendered water-insoluble by slightly crosslinking (that is, making a three-dimension of) a water-soluble resin, and it is generally an anionic polymer or a nonionic polymer. However, this is not intended to exclude use of a cationic polymer such as a quaternary ammonium salt or of an ampho-ionic polymer. From the viewpoint of a wide use or the like, however, an anionic polymer, a nonionic polymer or a mixture thereof is preferable.
The anionic polymer includes e.g. a product based on polyacrylic acid, isobutylene/malate, starch/polyacrylate, vinyl alcohol/acrylate, carboxymethyl cellulose, acrylate/acrylamide or vinyl acetate/acrylate; a saponified product based on polyacrylonitrile or starch/acrylonitrile graft polymer; a product based on polysaccharide/acrylate, alginate or polysulfonate; and a saponified product based on vinyl acetate/acrylate copolymer. These can also be used singly or in combination thereof. These are generally powdery or fibrous and may be in a form of complex fiber with polyacrylonitrile core/polyacrylate shell.
The nonionic polymer includes those based on polyvinyl alcohol, starch/polyacrylonitrile, poloxyethylene, vinyl acetate/maleic anhydride, poly-N-vinyl acetamide and polyacrylamide. These can also be used singly or in combination thereof and are generally in a form of powdery or fibrous products.
Among the water-absorbing polymers described above, those based on polyacrylate, isobutylene/maleate, starch/polyacrylate, polyvinyl alcohol, vinyl acetate/maleic anhydride and poly N-acetamide are preferable. In view of water absorption, water-holding property, water penetration or the like, it is more preferable that the water-absorbing polymer based on polyacrylate, polyvinyl alcohol, vinyl acetate/maleic anhydride or poly N-acetamide is used.
The used amount of the water-absorbing polymer is in the range of from 0.01% by weight, which is the minimum amount of thereof being capable of holding water, to 10% by weight. If its amount is less than 0.01% by weight, the water-absorbing polymer is liquefied without being solidified. On the other hand, if its amount is more than 10% by weight, the water absorption is too strong, and water releasability is weak, to grow a plant. The used amount of the water-absorbing polymer is preferably 0.1 to 10% by weight.
The cationic polymer for use may be any cationic polymer of soluble or insoluble ones in an aqueous solution or an aqueous salt solution. The soluble one includes cationic cellulose, cationic starch, cationic chitosan, cationic polyvinyl alcohol and cationic guar gum. On the other hand, the insoluble one includes an acrylamide polymer modified with a group having a quaternary ammonium salt, an acrylamide/acrylate copolymer modified with a group having a quaternary ammonium salt, an acrylate polymer modified with a group having a quaternary ammonium salt (such as Amberlite IRA-458 provided by Japan Organo Co., Ltd.), a styrene polymer modified with a group having a quaternary ammonium salt, a styrene/divinyl benzene copolymer modified with a group having a quaternary ammonium salt (such as Diaion series provided by Mitsubishi Chemical Corp.; Amberlite series from Japan Organo Co., Ltd.; Dowex series from Dow Chemical Co.; and Duolite series from Chemical Process Co.), a diallylamine polymer modified with a group having a quaternary ammonium salt, and a condensate of alkylamine with epichlorohydrin modified with a group having a quaternary ammonium salt.
When an anion-exchange resin is used as the cationic polymer, its structure may be either in a gel form or in an MR (macro reticular structure). Its counter ion may be either OH type or Cl type. The ion-exchange capacity in total is preferably more than 2.0 mg equivalent/1 g dry resin. Further, a porous anion-exchange resin is preferable. The anion-exchange resin for use may be a commercial product being available under trade names such as Amberlite IRA-67 (provided by Japan Organo Co., Ltd., with its ion-exchange capacity in total of 5.6 mg equivalent/1 g dry resin), Dowex MSA-1 (provided by Dow Chemical Co., with its ion-exchange capacity in total of 4.2 mg equivalent/1 g dry resin,), Duolite A-101D (provided by Chemical
Hayashi Masaharu
Kamei Masatoshi
Suzuki Tadayuki
Kao Corporation
Palo Francis T.
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