WO2023032686A1

WO2023032686A1 - Culture medium for hydroponics, method for producing culture medium for hydroponics, hydroponic method using culture medium for hydroponics, and dispersion liquid for suppressing occurrence of algae

Info

Publication number: WO2023032686A1
Application number: PCT/JP2022/031156
Authority: WO
Inventors: 厚中村; 幸介藤田; 美代坂井; 俊介河中
Original assignee: Dic株式会社
Priority date: 2021-09-01
Filing date: 2022-08-18
Publication date: 2023-03-09
Also published as: CN117794645A; JPWO2023032686A1

Abstract

The present invention provides a culture medium for hydroponics, in which a photocatalyst composition (B) is supported on a porous material (A), wherein the photocatalyst composition (B) is a photocatalyst composition in which a metal is supported on a titanium oxide composition. This culture medium for hydroponics is for use in a hydroponic method which suppresses the occurrence of algae and does not inhibit the growth of plants.

Description

Hydroponic culture medium, method for producing hydroponic culture medium, hydroponic culture method using hydroponic culture medium, and dispersion for suppressing algae growth

The present invention relates to a hydroponic culture medium, a method for producing a hydroponic culture medium, a hydroponic culture method using the hydroponic culture medium, and a dispersion liquid for suppressing the growth of algae.

In recent years, hydroponics, which does not use soil, has attracted attention. Hydroponics is a cultivation method in which crops are grown in a "culture solution" using raw water and liquid fertilizer. Hydroponics is a cultivation method that does not require work such as soiling and fertilization, is less affected by the geographical environment, and has high utility value.
However, a problem unique to cultivation that uses water is the occurrence of algae. Since algae grow as long as they have light and nutrients, the occurrence of algae is inevitable in hydroponics.
When a large amount of algae grows, it changes the balance of components in the culture solution. If the culture solution becomes alkaline, the roots of crops will be damaged. In addition, when mucus-like acidic polysaccharides generated by a large amount of algae cover the roots of agricultural crops, they prevent the crops from absorbing nutrients and oxygen.
Therefore, in hydroponics, an anti-algae measure for preventing the generation of algae is desired.

It has been reported that the use of silver that exhibits bactericidal activity can suppress the growth of algae in hydroponics (see, for example, Non-Patent Documents 1 and 2).

However, according to the descriptions of Non-Patent Documents 1 and 2 above, algae control measures using silver can suppress the growth of algae, but if a certain amount of silver is used to achieve the effect, the growth of plants is also inhibited. I know it will be suppressed.
Therefore, it has been desired to provide a hydroponic cultivation method that suppresses the growth of algae and does not inhibit the growth of plants.

The purpose of the present invention is to provide a hydroponic culture medium for use in a hydroponic culture method that suppresses the growth of algae and does not inhibit the growth of plants.

The inventors have made intensive studies to solve the above problems, and as a result, a hydroponic culture medium in which a photocatalyst composition in which a metal is supported on a titanium oxide composition is supported on a porous material is provided. can be solved, and the present invention has been completed.

That is, the present invention includes the following aspects.
[1] A hydroponic culture medium in which a photocatalyst composition (B) is supported on a porous material (A),
The photocatalyst composition (B) is a hydroponic culture medium, which is a photocatalyst composition in which a metal is supported on a titanium oxide composition.
[2] The hydroponic culture medium according to [1], wherein the titanium oxide composition contains rutile-type titanium oxide.
[3] The hydroponic culture medium according to [1] or [2], wherein the metal is a transition metal or a typical metal.
[4] The hydroponic culture medium according to any one of [1] to [3], wherein the titanium oxide composition substantially contains at least one metal element selected from the group consisting of zirconium and niobium.
[5] The hydroponic culture medium according to any one of [1] to [4], wherein the porous material (A) is a foam containing an open cell structure.
[6] The hydroponic culture medium according to [5], wherein the porous material (A) is urethane foam.
[7] The hydroponic culture medium according to [6], wherein the porous material (A) is urethane foam with a density of 10 to 30 g/m ³ .
[8] For hydroponics according to any one of [1] to [7], wherein the photocatalyst composition (B) is supported on the porous material (A) via a binder resin (C). Culture medium.
[9] The hydroponic culture medium according to [8], wherein the binder resin (C) is a urethane resin or an acrylic resin.
[10] A method for producing a hydroponic culture medium for producing the hydroponic culture medium according to any one of [1] to [9],
a step of dispersing the photocatalyst composition (B) and the binder resin (C) in the medium (D) to obtain a dispersion (E);
a step of impregnating the porous material (A) with the dispersion (E);
a step of drying and removing the medium (D) from the porous material (A);
A method for producing a hydroponic culture medium having
[11] The method for producing a hydroponic culture medium according to [10], wherein the medium (D) contains water.
[12] The dispersion (E) further contains a wetting and dispersing agent (F),
Production of a hydroponic culture medium according to [10] or [11], wherein the wetting and dispersing agent (F) is a copolymer having an ammonium base or a copolymer having an acid value of 10 mg KOH/g or more having a free fatty acid group. Method.
[13] A hydroponic cultivation method using the hydroponic cultivation medium according to any one of [1] to [9] and light irradiation means.
[14]
A dispersion for suppressing the growth of algae used in hydroponics,
The dispersion (E), which is a dispersion for suppressing the growth of algae, contains at least a medium (D) and a photocatalyst composition (B),
The photocatalyst composition (B) is a dispersion liquid for suppressing the growth of algae, which is a photocatalyst composition in which a metal is supported on a titanium oxide composition.
[15] The dispersion for suppressing the growth of algae according to [14], wherein the titanium oxide composition contains rutile-type titanium oxide.
[16] The dispersion for suppressing the growth of algae according to [14] or [15], wherein the metal is a transition metal or a typical metal.
[17] The algae growth inhibitor according to any one of [14] to [16], wherein the titanium oxide composition substantially contains at least one metal element selected from the group consisting of zirconium and niobium. dispersion.
[18] The dispersion for suppressing the growth of algae according to any one of [14] to [17], further containing a binder resin (C).
[19] The dispersion for suppressing the growth of algae according to [18], wherein the binder resin (C) is a urethane resin or an acrylic resin.
[20] The dispersion for suppressing the growth of algae according to any one of [14] to [19], wherein the medium (D) contains water.
[21] The dispersion (E) further contains a wetting and dispersing agent (F),
The wetting and dispersing agent (F) is a copolymer having an ammonium base or a copolymer having an acid value of 10 mg KOH/g or more having a free fatty acid group, suppressing algae growth according to any one of [14] to [20]. dispersion for

According to the present invention, it is possible to provide a hydroponic cultivation medium for use in a hydroponic cultivation method that suppresses the growth of algae and does not inhibit the growth of plants.

FIG. 1 shows the results of the follow-up observation of the growth of algae in the bat and the growth of lettuce with or without sowing lettuce seeds in Example 1, Comparative Example 1, and Comparative Example 2, and the observation results on the 7th day. is a photograph showing FIG. 2 shows the results of the follow-up observation of the state of algal growth and the state of lettuce growth in the bat with and without sowing lettuce seeds in Example 1, Comparative Example 1, and Comparative Example 2, and the observation results on the 14th day. is a photograph showing FIG. 3 shows the results of the follow-up observation of the growth of algae in the bat and the growth of lettuce with or without sowing lettuce seeds in Example 1, Comparative Example 1, and Comparative Example 2, and the observation results on the 21st day. is a photograph showing FIG. 4 is a schematic diagram showing an example of a hydroponic cultivation apparatus for carrying out the hydroponic cultivation method. FIG. 5 is a schematic diagram showing an example of a hydroponic cultivation apparatus for carrying out the hydroponic cultivation method.

The present invention will be described in detail below. It should be noted that the description of the constituent elements described below is an example for describing the present invention, and the present invention is not limited to these contents.

(Medium for hydroponics)
In the hydroponic culture medium, the photocatalyst composition (B) is supported on the porous material (A).

<Porous material (A)>
The porous material (A) is not particularly limited as long as it is a substrate having a large number of pores and can support the photocatalyst composition (B), and can be appropriately selected according to the purpose. Examples include rockwool, vermiculite, and foams containing cellular structures. Examples of foams include synthetic resin foams such as polyurethane, polystyrene, polyethylene, and polypropylene, as well as pulp- and cotton-derived cellulose sponges, sponge-derived natural sponges, and plant-derived fiber porous bodies such as luffa. As a medium for hydroponics, a biodegradable porous material is preferable because it is discarded after being used for a short period of about one month.
Among foams containing cell structures, foams with an open cell structure are preferred. A foam having an open-cell structure is suitable as a sponge for hydroponic cultivation because the cells are connected, so that moisture and air can easily pass through the foam.
A preferred embodiment of the porous material (A) is a urethane foam porous material. Here, urethane foam is obtained by, for example, using polyol and polyisocyanate as raw materials, stirring and mixing a foaming agent, a foam stabilizer, a catalyst, etc., and simultaneously performing a foaming reaction and a resinification reaction. , refers to plastic foam.
Among urethane foam porous materials, a urethane foam porous body having a density of 10 to 30 g/m ³ is more preferable. The density here means the mass per unit volume of a sample containing both air-permeable and air-impermeable cells (here, a porous urethane foam material), ie, the so-called apparent density. This apparent density can be determined according to JIS K 7222:2005 (Foamed plastics and rubber-Determination of apparent density).

<Photocatalytic composition (B)>
The photocatalyst composition (B) is a composition exhibiting visible light responsiveness due to the metal being supported on the titanium oxide composition.

<<Titanium oxide composition>>
The titanium oxide composition of the present invention must contain at least titanium oxide, but may contain metal elements other than titanium oxide.
A preferred embodiment of the titanium oxide composition of the present invention includes, for example, a titanium oxide composition substantially containing at least one metal element selected from the group consisting of zirconium and niobium.
The titanium oxide in the titanium oxide composition preferably contains rutile-type titanium oxide. In addition to rutile-type titanium oxide, titanium oxide may also contain anatase-type titanium oxide, brookite-type titanium oxide, and the like.
The content of rutile-type titanium oxide in titanium oxide (rutilization rate) is preferably 15 mol% or more from the viewpoint of satisfying excellent anti-algae properties, plant growth, and visible light responsiveness. It is more preferably 50 mol % or more, and even more preferably 90 mol % or more.
Titanium oxide produced by either a vapor phase method or a liquid phase method can be used, but it is preferable to use one produced by a liquid phase method.

A liquid phase method and a gas phase method are generally known as methods for producing a titanium oxide composition. The liquid phase method is a method of obtaining titanium oxide by hydrolyzing or neutralizing titanyl sulfate obtained from a liquid in which raw ore such as ilmenite ore is dissolved. The vapor phase method is a method of obtaining titanium oxide through a vapor phase reaction between oxygen and titanium tetrachloride obtained by chlorinating raw material ore such as rutile ore.
When the liquid phase method is used, ilmenite ore may be used as the raw material ore for titanium oxide, or titanium slag obtained by metallurgically treating ilmenite ore to increase the purity of titanium may be used.

The BET specific surface area of titanium oxide in the titanium oxide composition is preferably in the range of 1 to 200 m ² /g, preferably 3 to 100 m, from the viewpoint of satisfying excellent anti-algae properties, plant growth, and visible light responsiveness. ² /g, more preferably 4 to 70 m ² /g, even more preferably 4 to 50 m ² /g. A range of ² /g is particularly preferred. The method for measuring the BET specific surface area of titanium oxide will be described later in Examples.

The primary particle size of titanium oxide in the titanium oxide composition is preferably in the range of 0.01 to 0.5 μm from the viewpoint of satisfying excellent anti-algae properties, plant growth, and visible light responsiveness. A range of 0.03 to 0.35 μm is more preferable, and a range of 0.06 to 0.35 μm is even more preferable. In addition, the method for measuring the primary particle size of titanium oxide indicates a value measured by a method of directly measuring the size of primary particles from an electron micrograph using a transmission electron microscope (TEM). Specifically, the minor axis diameter and major axis diameter of each primary particle of titanium oxide are measured, the average is taken as the particle diameter of the primary particles, and then for 100 or more titanium oxide particles, each particle The volume (weight) of is approximated to a cube of the determined particle size, and the volume average particle size can be taken as the average primary particle size.

As described above, the titanium oxide composition of the present invention is preferably a titanium oxide composition substantially containing at least one metal element selected from the group consisting of zirconium and niobium.
The content ratio of zirconium to titanium 100 (Zr/Ti ratio) in the titanium oxide composition is preferably 0.03 or more, more preferably 0.04 or more, still more preferably 0.05 or more, and preferably 0. 0.8 or less, more preferably 0.5 or less, and still more preferably 0.3 or less. Any combination of these upper and lower limits may be used. The content ratio of zirconium to titanium 100 (Zr/Ti ratio) in the titanium oxide composition is preferably 0.03 to 0.8, more preferably 0.04 to 0.5, still more preferably 0.05 to 0.5. 3.
The content ratio of niobium to titanium 100 (Nb/Ti ratio) in the titanium oxide composition is preferably 0.05 or more, more preferably 0.08 or more, still more preferably 0.1 or more, and preferably 0. 0.8 or less, more preferably 0.5 or less, and still more preferably 0.3 or less. Any combination of these upper and lower limits may be used. The content ratio of niobium to titanium 100 (Nb/Ti ratio) in the titanium oxide composition is preferably 0.05 to 0.8, more preferably 0.08 to 0.5, still more preferably 0.10 to 0.5. 3.
If the zirconium and niobium contained in the titanium oxide composition are within the above range, the dispersibility in the solvent is high, and even if the concentration of titanium oxide is increased, the mixed solution can be handled satisfactorily.
That titanium oxide substantially contains a metal element (zirconium and/or niobium) means that the content ratio of the metal element in titanium oxide is 0.02 or more to 100 of titanium. Titanium oxide substantially containing a metal element (zirconium and/or niobium) is a titanium oxide composition substantially containing a metal element (zirconium and/or niobium).
Titanium oxide, which substantially contains a metal element (zirconium and/or niobium), has a small cohesive force with respect to the specific surface area (BET value) due to the primary particles, and can suppress the viscosity of the mixed liquid. , and is presumed to contribute to the improvement of the concentration of titanium oxide.

<<<Method for Producing Titanium Oxide Composition>>>
As a method for producing the titanium oxide composition, it can be produced by the general sulfuric acid method based on the liquid phase method described above, or the general chlorine method based on the vapor phase method described above.
For example, a titanium oxide composition can be produced as follows.
a) According to a general sulfuric acid method, sulfuric acid, water, and iron are added to and dissolved in ilmenite ore to obtain a solution containing titanium sulfate and iron sulfate as main components. Next, impurities such as iron sulfate are removed, followed by thermal hydrolysis to obtain a hydrous titanium hydroxide composition. Next, the titanium hydroxide composition is washed, sintered at a temperature in the range of 400° C. to 1,600° C., and the obtained solids are pulverized. Thereby, a titanium oxide composition can be obtained.

Alternatively, a titanium oxide composition can be produced as follows.
b) According to a general chlorine method, rutile ore, coke and chlorine are reacted to obtain titanium tetrachloride. Titanium tetrachloride is distilled to remove impurities, subjected to combustion treatment under oxygen at a temperature range of 700° C. to 1,600° C., and after cooling, the resulting solid is pulverized. Thereby, a titanium oxide composition can be obtained.

Further, as a preferred embodiment, when producing a titanium oxide composition substantially containing at least one metal element selected from the group consisting of zirconium and niobium, for example, the titanium oxide composition is prepared as follows. can be manufactured.
c) According to a general sulfuric acid method, sulfuric acid, water, and iron are added to and dissolved in a mixture of ilmenite ore, niobium pentoxide, and zirconium oxide to obtain a solution containing titanium sulfate and iron sulfate as main components. . Next, impurities such as iron sulfate are removed, followed by thermal hydrolysis to obtain a hydrous titanium hydroxide composition. Next, the titanium hydroxide composition is washed, sintered at a temperature in the range of 400° C. to 1,600° C., and the obtained solids are pulverized. Thereby, a titanium oxide composition substantially containing at least one metal element selected from the group consisting of zirconium and niobium can be obtained.

In addition to the step of supporting a metal for forming the photocatalyst composition (B) of the present invention, the above-mentioned Surface treatments such as inorganic substance treatment and organic substance treatment may be arbitrarily combined with respect to the titanium oxide composition. Examples of inorganic treatment include surface treatment with inorganic metal hydrous oxides such as alumina, silica, zinc oxide, zirconia, titania, tin oxide and antimony oxide. Surface treatment with compounds such as polyols, alkanolamines, and silicones can be used as the organic treatment. As a surface treatment method, a known method used for titanium oxide, such as surface treatment of alumina of titanium oxide pigment, surface treatment of silane coupling agent, and the like can be used.

<<Metal>>
A metal is supported on the titanium oxide composition to form a photocatalyst composition (B).
The metal may be in the form of a metal element, an alloy, or a compound containing metal ions or metal elements. Compounds containing metal elements include, for example, metal chlorides, bromides, iodides, oxides, suboxides, sulfides, cyanides, hydroxides, fluorides, sulfate compounds, sulfite compounds, nitrate compounds, Nitrate compounds, phosphate compounds, phosphite compounds, carbonate compounds, etc. are included, and organometallic compounds are not included.
The metal supported on titanium oxide works as an active site, promotes multi-electron reactions by accumulating charges, and functions as a co-catalyst such as promoting charge separation, thereby improving the visible light range of the photocatalyst composition. Photocatalytic activity can be improved. In addition, various functions can be imparted to the photocatalyst composition by supporting the metal, and in particular, the photocatalyst composition of the present invention can satisfy both the effects of suppressing the growth of algae and promoting the growth of plants. can.
The supported metal is preferably insoluble or sparingly soluble in water, and in the hydroponic culture medium of the present invention, the metal is eluted as metal ions from the porous material (A). Therefore, plants can be cultivated safely. In addition, when titanium oxide is exposed to light, water and oxygen near the surface of the titanium oxide photocatalyst are converted into active oxygen, and it is presumed that this active oxygen exerts an effect of inhibiting the growth of algae.
Moreover, the photocatalyst composition of the present invention is also excellent in antibacterial effect.

The metal element of the metal supported on the photocatalyst composition (B) may be a typical metal or a transition metal. Not included. Specifically, for example, transition metals such as copper, iron, tungsten, zirconium, molybdenum, cobalt, manganese, neodymium, nickel, palladium, platinum and gold, and typical metals such as zinc, aluminum, antimony, tin and bismuth. It can be used preferably.

Among the metals supported by the photocatalyst composition (B), copper is preferred, and divalent copper is more preferred, from the viewpoint of satisfying excellent anti-algae properties, plant growth, visible light responsiveness, and the like.

Examples of divalent copper compounds include copper sulfate, copper nitrate, copper iodate, copper perchlorate, copper oxalate, copper tetraborate, copper ammonium sulfate, copper amidosulfate, copper ammonium chloride, copper pyrophosphate, and carbonate. Inorganic acid salts of divalent copper such as copper; halides of divalent copper such as copper chloride, copper fluoride and copper bromide; copper oxide, copper sulfide, azurite, malachite, copper azide and the like can be used. These compounds may be used alone or in combination of two or more.

As the divalent copper compound raw material, it is preferable to use one represented by the following general formula (1) among those mentioned above.
_CuX2 (1)
(In formula (1), X represents a halogen atom, CH ₃ COO, NO ₃ , or (SO ₄ ) _1/2 .)

X in the above formula (1) is more preferably a halogen atom, more preferably a chlorine atom.

<<Method for producing photocatalyst composition (B)>>
As a processing method for supporting the support (the metal) on the photocatalyst composition (B), a known method can be used as long as it is a wet method.
Examples thereof include a method of adsorbing with a mixed solution of a titanium oxide composition suspended in an aqueous solution of a support and a solvent, and a method of reacting a titanium oxide composition with a mixed solution of a support, a solvent and an alkaline substance. Make a mixture for processing. The mixture contains at least a titanium oxide composition and a solvent.

The concentration of the titanium oxide composition in the mixed solution is preferably in the range of 3 to 40% by mass. In addition, in the present invention, it is preferable to use titanium oxide produced by a liquid phase method, and even if the concentration of titanium oxide is increased, the reaction can be performed with a mixed solution that is easy to handle. Specifically, even when the concentration of the titanium oxide composition is in the range of more than 25% by mass to 40% by mass or less, the reaction can be carried out in a favorable mixed solution.

The amount of the support raw material used in the mixed solution is preferably in the range of 0.01 to 20 parts by mass, more preferably in the range of 0.1 to 15 parts by mass, with respect to 100 parts by mass of titanium oxide. 0.3 to 10 parts by mass is more preferable.

As the solvent, only water may be used, or a mixed solvent of water and an organic solvent may be used. In the case of a mixed solvent, an aqueous solvent containing water as a main component is preferred. Here, the aqueous solvent containing water as a main component refers to a solvent having the highest water content in the total amount of the solvent, preferably 50% by mass or more of water.
In the case of a mixed solvent containing an organic solvent, the composition of the organic solvent is determined according to the properties of the desired mixed liquid. From the viewpoint of reducing environmental load and improving safety, the mixed solvent preferably contains an organic solvent in an amount of 30% by mass or less, preferably 5% by mass or less in the total amount of the solvent.

The organic solvent that can be used as the solvent is not particularly limited, but for example, an organic solvent that is miscible with water is preferably used. Organic solvents that can be used as solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, 1-pentanol, 2-methyl-2-pentanol, and 3-methyl-3-pentane. monofunctional alcohols such as tanol,
Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane Diol, 1,12-dodecanediol, propylene glycol, 1,2-butanediol, 3-methyl-1,3-butanediol, 1,2-pentanediol, 2-methyl-1,3-propanediol, 1,2 - Various diols such as hexanediol, dipropylene glycol and diethylene glycol, polyhydric alcohols such as glycerin,
ketones such as methyl ethyl ketone and methyl isobutyl ketone, dimethylformamide, tetrahydrofuran,
Bisphenol A, aromatic diols which are adducts of alkylene oxides having 2 or 3 carbon atoms (average addition mole number of 1 to 16) of bisphenol A, alicyclic diols such as hydrogenated bisphenol A, polyoxypropylene-2,2- Bis(4-hydroxyphenyl)propane, polyoxyethylene-2,2-bis(4-hydroxyphenyl)propane, cyclohexanediol, ethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether , diethylene glycol monomethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, ethyl carbitol, γ-butyrolactone, and the like. These may be used singly or in combination of two or more, with no limitation.

Among others, 1-butanol, isobutanol, 1-pentanol, 2-methyl-2-pentanol, 3-methyl-3-pentanol, methyl ethyl ketone, methanol, ethanol, n-propyl alcohol (NPA), isopropyl alcohol (IPA ), propylene glycol, propylene glycol monomethyl ether (1-methoxy-2-propanol) (PGM), and ethylene glycol are preferred.

Examples of the alkaline substance include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetrabutylammonium hydroxide, triethylamine, trimethylamine, ammonia, basic surfactants, and the like. It is preferable to use

The alkaline substance is preferably added in the form of a solution, since the reaction can be easily controlled. A range of L is more preferred, and a range of 0.5 to 3 mol/L is even more preferred.

<<<embodiment of method for producing photocatalyst composition (B)>>>
A more preferred embodiment of the method for producing the photocatalyst composition (B) includes a production method for obtaining the photocatalyst composition (B) by supporting a divalent copper compound on a titanium oxide composition.
A method for supporting a divalent copper compound on a titanium oxide composition will be described in detail below.

The mixed solution may be obtained by mixing the titanium oxide composition, the divalent copper compound raw material, the solvent, and the alkaline substance. A method of mixing raw materials of a valent copper compound, stirring, and then adding an alkaline substance and stirring may be used. With this mixed solution, the divalent copper compound derived from the divalent copper compound raw material is supported on the titanium oxide composition.

The total stirring time for the mixed solution is, for example, 5 to 120 minutes, preferably 10 to 60 minutes. The reaction temperature of the mixed solution is, for example, in the range of room temperature to 70°C.

From the viewpoint that the divalent copper compound is well supported on the titanium oxide composition, the titanium oxide composition, the divalent copper compound raw material, and water are mixed and stirred, and then the alkaline substance is mixed and stirred. The pH of the mixed solution is preferably in the range of 8 to 11, more preferably in the range of 9.0 to 10.5.

After the reaction in the mixed liquid is completed, the solid content can be separated. Examples of the method for separation include filtration, sedimentation, centrifugation, and evaporation drying, with filtration being preferred. The separated solid content may then be washed with water, pulverized, classified, etc., if necessary.

After obtaining the solid content, the solid content is heat-treated from the viewpoint that the divalent copper compound derived from the divalent copper compound raw material and supported on the titanium oxide composition can be more strongly bonded. is preferred. The heat treatment temperature is preferably in the range of 150 to 600°C, more preferably in the range of 250 to 450°C. The heat treatment time is preferably 1 to 10 hours, more preferably 2 to 5 hours.

By the above method, a photocatalyst composition (B) in which a divalent copper compound is supported on a titanium oxide composition can be obtained.
The amount of the bivalent copper compound supported by the titanium oxide composition is in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of titanium oxide. It is preferable from the viewpoint of satisfying plant growth and visible light responsiveness. The amount of the divalent copper compound supported can be adjusted by adjusting the amount of the divalent copper compound raw material used in the mixed solution. A method for measuring the supported amount of the divalent copper compound will be described later in Examples.

The mixed solution may contain other ingredients as long as the effects of the present invention can be obtained. Other components include pigments, leveling agents, antifoaming agents, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants and the like.

<Preferred embodiment of hydroponic culture medium>
As a preferred embodiment of the hydroponic culture medium, the content of the photocatalyst composition (B) in the porous material (A) is is preferably 0.1 kg/m ³ to 2 kg/m ³ .

A preferable embodiment of the hydroponic culture medium includes a hydroponic culture medium in which the photocatalyst composition (B) is supported on the porous material (A) via the binder resin (C).
Here, examples of the binder resin (C) include urethane-based resins and acrylic-based resins.
Examples of the urethane-based resin include polyester-polyurethane resin, polyether-polyurethane resin, polycarbonate-polyurethane resin, and the like.
As the urethane-based resin, a water-dispersible polyurethane resin having an alkylene oxide chain in the molecule can be used. In addition to the alkylene oxide chain, the molecule may contain a hydrophilic group such as a carboxylic acid or a sulfonic acid.
Examples of commercially available water-dispersible polyurethane resins containing an alkylene oxide chain in the molecule include "Hydran" (trade name) manufactured by DIC Corporation and "Impranil" (trade name) manufactured by Covestro. , "Permaline" (trade name) manufactured by Sanyo Chemical Industries, Ltd., and the like.
As a water-dispersible resin of polycarbonate-polyurethane resin, for example, Hydlan WLS-210, a commercially available product, can also be used.

The acrylic resin is obtained by polymerizing a polymerizable monomer containing an acrylic monomer as an essential component. Moreover, in order to improve solubility or dispersion in an aqueous medium, it is preferable to use a polymerizable monomer having a carboxyl group.
Examples of acrylic monomers include polyethylene glycol mono (meth) acrylate, stearoxy polypropylene glycol mono (meth) acrylate, allyloxy polyethylene glycol mono (meth) acrylate, allyloxy polypropylene glycol mono (meth) acrylate, nonylphenoxy polyethylene glycol mono (meth) acrylate. Alkyl group-terminated polyalkylene glycol mono(meth)acrylates such as (meth)acrylates and nonylphenoxypolypropylene glycol mono(meth)acrylate; silane-based (meth)acrylates such as trimethylsiloxyethyl (meth)acrylate; 3-(meth)acryloyl (Meth)acryloyloxyalkyls such as oxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, etc. Silane compounds; fluorine-based (meth)acrylates such as perfluoroalkylethyl (meth)acrylate; glycidyl (meth)acrylate, epoxy (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylene glycol tetra(meth)acrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis [4-(Acryloxyethoxy)phenyl]propane, dicyclopentenyl (meth)acrylate tricyclodecanyl (meth)acrylate, tris (acryloxyethyl) isocyanurate, urethane (meth)acrylate and other (meth)acrylate compounds; Examples thereof include (meth)acrylates having an alkylamino group such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate. These (meth)acrylate compounds can be used alone or in combination of two or more.

In the present invention, "(meth)acrylate" refers to one or both of methacrylate and acrylate, "(meth)acryloyl" refers to one or both of methacryloyl and acryloyl, and "(meth)acrylic acid ” refers to one or both of methacrylic acid and acrylic acid.

In the case of introducing a carboxyl group into the acrylic resin, the raw materials include, for example, (meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, polymerization having a carboxyl group such as citraconic acid can be used. These polymerizable monomers can be used alone or in combination of two or more. Further, after introducing a carboxyl group into the acrylic resin using these polymerizable monomers having a carboxyl group, part or all of the carboxyl group is replaced with a metal hydroxide such as potassium hydroxide or sodium hydroxide. ; it may be neutralized with a base such as ammonia, an organic substance such as triethylamine.

Furthermore, as a raw material for the acrylic resin, other polymerizable monomers may be used as polymerizable monomers other than the acrylic monomers. Examples of the polymerizable monomer include styrene, styrene derivatives (α-methylstyrene, p-dimethylsilylstyrene, (p-vinylphenyl)methylsulfide, p-hexynylstyrene, p-methoxystyrene, p-tert-butyl dimethylsiloxystyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, α-methylstyrene, etc.), aromatic vinyl compounds such as vinylnaphthalene, vinylanthracene, 1,1-diphenylethylene; acrylamide, N,N-dimethylacrylamide, isopropylacrylamide, diacetoneacrylamide and other acrylamide compounds; 2-vinylpyridine, 4-vinylpyridine, naphthylvinylpyridine and other vinylpyridine compounds; 1,3-butadiene, 2-methyl-1 ,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-cyclohexadiene and other conjugated dienes. These polymerizable monomers can be used alone or in combination of two or more.

As a method for producing the acrylic resin, for example, a known emulsion polymerization method can be used.

The dispersion liquid used for manufacturing the hydroponic culture medium will be described in detail below. At that time, the binder resin (C) will also be described in detail.

By supporting the photocatalyst composition (B) on the porous material (A) via the binder resin (C), the photocatalyst composition (B) is more firmly supported on the porous material (A). , detachment of the photocatalyst composition (B) from the porous material (A) can be prevented. Therefore, even if water is circulated, the photocatalyst composition (B) can be prevented from falling off, and a medium suitable for hydroponics can be provided.
A method for producing a hydroponic culture medium in which the photocatalyst composition (B) is supported on the porous material (A) via the binder resin (C) will be described later.

(Method for producing hydroponic culture medium)
The method for producing a hydroponic culture medium of the present invention comprises:
(I) step: a step of dispersing the photocatalyst composition (B) in the medium (D) to obtain a dispersion (E);
(II) step: a step of impregnating the porous material (A) with the dispersion (E);
(III) step: a step of drying and removing the medium (D) from the porous material (A);
have

As described above, when the photocatalyst composition (B) is supported on the porous material (A) via the binder resin (C), the photocatalyst composition (B) is more likely to be absorbed by the porous material (A). As a more preferable embodiment of the method for producing a hydroponic culture medium, the following production method can be mentioned, since a firmly supported hydroponic culture medium can be obtained.
(I') step: a step of dispersing the photocatalyst composition (B) and the binder resin (C) in the medium (D) to obtain a dispersion (E);
(II) step: a step of impregnating the porous material (A) with the dispersion (E);
(III) step: a step of drying and removing the medium (D) from the porous material (A);
have

About the above step (I) and the above step (I′) (the above step (I) and the above step (I′) are collectively referred to as the (I) step), the above step (II), and the above step (III) , which will be described in detail below.

<(I) Step>
The photocatalyst composition (B) is dispersed in the medium (D) to obtain a dispersion (E).
When the photocatalyst composition (B) is supported on the porous material (A) via the binder resin (C), the medium (D) is provided with the photocatalyst composition (B) and the binder resin (C). Disperse to obtain a dispersion (E).
Here, the photocatalyst composition (B) is as described in the section <Photocatalyst composition (B)> above. In addition, the binder resin (C) is as described in the section <<preferred embodiment of hydroponic culture medium>>.
Medium (D) contains water.
The medium (D) is an aqueous medium containing water as a main component and may contain an organic solvent. In the present invention, only water may be used, or a mixture of water and an organic solvent may be used, but from the viewpoint of reducing environmental load and improving safety, the amount of organic solvent used is preferably as small as possible. .
When an organic solvent is contained, the medium (D) preferably contains the organic solvent in an amount of 30% by mass or less, preferably 5% by mass or less.

The organic solvent that can be used is not particularly limited. - monofunctional alcohols such as pentanol, methyl ethyl ketone, methanol, ethanol, n-propyl alcohol (hereinafter also referred to as NPA) and isopropyl alcohol (hereinafter also referred to as IPA), various diols, polyhydric alcohols such as glycerin, ethylene Glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol , 1,12-dodecanediol, propylene glycol, 1,2-butanediol, 3-methyl-1,3-butanediol, 1,2-pentanediol, 2-methyl-1,3-propanediol, 1,2-hexanediol, di Diols such as propylene glycol and diethylene glycol,

Bisphenol A, aromatic diols which are adducts of alkylene oxides having 2 or 3 carbon atoms (average addition mole number of 1 to 16) of bisphenol A, alicyclic diols such as hydrogenated bisphenol A, polyoxypropylene-2,2- Bis(4-hydroxyphenyl)propane, polyoxyethylene-2,2-bis(4-hydroxyphenyl)propane, cyclohexanediol, ethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether , diethylene glycol monomethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, ethyl carbitol, γ-butyrolactone, and the like. These may be used singly or as a mixture of two or more kinds, and there is no limitation.
Among them, 1-butanol, isobutanol, 1-pentanol, 2-methyl-2-pentanol, 3-methyl-3-pentanol, methyl ethyl ketone, methanol, ethanol, n-propyl alcohol (hereinafter also referred to as NPA) , isopropyl alcohol (hereinafter also referred to as IPA), propylene glycol, propylene glycol monomethyl ether (1-methoxy-2-propanol) (also referred to as PGM), and ethylene glycol are preferable.

The dispersion (E) may further contain a wetting and dispersing agent (F).
As the wetting and dispersing agent (F), any dispersing agent can be used as long as it is effective in improving the wettability and dispersibility of the metal oxide. Copolymers having free fatty acid groups and having an acid value of 10 mg KOH/g or more are included.
Among the wetting and dispersing agents (F), dispersing agents having an acid value are preferably used.
The above copolymer preferably has a relatively high molecular weight. For example, the molecular weight of the copolymer is preferably 500 to 200,000, more preferably 1,000 to 150,000. As copolymers having an ammonium base, for example, polyfunctional polymers and acrylic copolymers are preferred. If the molecular weight of the copolymer is within the above range, the dispersibility is improved.

Examples of polyfunctional polymers include polymers having, as structural units, plural types of polymerizable monomers having functional groups such as amine groups, carboxyl groups, ether groups, and silyl groups.
Examples of acrylic copolymers include copolymers having acrylic polymerizable monomers, such as methacrylic acid and acrylic acid, as constitutional units.
Ammonium bases include, for example, alkylolamine salts.
The free fatty acid group can be obtained by using a polymerizable monomer having a carboxyl group such as (meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic anhydride, or citraconic acid as a structural unit. be.

The acid value of the copolymer having a free fatty acid group is 10 mg KOH/g or more, preferably 20 mg KOH/g or more, and usually 150 mg KOH/g or less, preferably 100 mg KOH/g or less. . The acid value of the copolymer having free fatty acid groups may be 10 mg KOH/g or more and 150 mg KOH/g or less, may be 10 mg KOH/g or more and 100 mg KOH/g or less, may be 20 mg KOH/g or more and 150 mg KOH/g or less, and may be 20 mg. KOH/g or more and 100 mg KOH/g or less may be sufficient.
Acid number is defined as milligrams of potassium hydroxide required to neutralize free fatty acids contained in 1 g.

Specific examples of the wetting and dispersing agent (A) falling within the above range include BYK-154, DISPERBYK180, DISPERBYK181, DISPERBYK190, DISPERBYK191, and DISPERBYK194N manufactured by BYK-Chemie Japan.

As long as the dispersion liquid (E) contains the above-described components, there is no particular limitation on the mixing method or mixing order of each component, and the mixing method can be appropriately selected in consideration of the type of each component to be used. However, more specifically, for example, the method for producing the dispersion (E) described below can be mentioned.
An example in which the dispersion (E) also contains the wetting and dispersing agent (F) will be described below.
(i) The photocatalyst composition (B), the wetting and dispersing agent (F) and the medium (D) are mixed and stirred. At that time, it is preferable to add beads to the mixed liquid and stir the slurry, which is a mixture of powder and liquid, and the beads in a bead mill to grind the crushed material particles. After grinding, the beads are separated from the mixture to obtain a photocatalyst dispersion (G).
(ii) The photocatalyst dispersion (G), the binder resin (C), and the medium (D) are mixed to obtain a dispersion (E).
Here, the mixing ratio of the photocatalyst dispersing element (G) and the binder resin (C) in the dispersion (E) is preferably 10:90 to 90:10 in solid content ratio.

<(II) step>
The porous material (A) is impregnated with the dispersion (E).
For example, the porous material (A) can be impregnated with the dispersion (E) by placing the dispersion (E) in an impregnation tank and supplying the porous material (A) into this bath.

<(III) step>
The medium (D) is removed by drying from the porous material (A).
For example, the medium (D) is dried and removed from the porous material (A) using squeeze rolls or a drying oven. More specifically, for example, after the impregnation in the step (II), the porous material (A) is squeezed with a squeeze roll to adjust the adhesion amount of the dispersion (E) in the porous material (A). For example, the squeezing roll interval is adjusted so that the dispersion liquid (E) in an amount such that the dry weight of the dispersion liquid (E) is 0.1 kg/m ³ to 3 kg/m ³ adheres to the porous material (A). do. Then, the porous material (A) is passed through the squeezing rolls. After passing through the squeezing rolls, the porous material (A) is passed through a drying furnace set at 60°C to 160°C and dried with hot air. Thereby, the hydroponic culture medium of the present invention can be obtained.

(dispersion liquid)
As described above, the dispersion liquid (E) is prepared in order to support the photocatalyst composition (B) on the porous material (A) when producing the hydroponic culture medium.
Dispersion (E) contains medium (D) and photocatalyst composition (B). A preferred embodiment of the dispersion (E) further contains a binder resin (C).

The dispersion liquid (E) can be used for medium processing to produce a hydroponic culture medium.
However, the dispersion liquid (E) according to the present invention is applicable not only to the production of culture media, but also to hydroponics in general where suppression of algae growth is desired. For example, it can be applied to a water tank for hydroponics (also called a cultivation container (bat)), a hydroponic panel (also called a cultivation board), etc., as a dispersion for suppressing the growth of algae used in hydroponics. . More specifically, for example, application to cultivation vessels (bats), growth boards, culture solution circulation tanks, filtering devices, filters, piping, and the like can be mentioned.
Among hydroponic cultivation devices, it is preferably applied to a portion in contact with the culture medium, near the site where algae are generated, and more preferably applied to the site irradiated with light. Therefore, it is particularly preferable to apply the dispersion (E) according to the present invention to hydroponic culture media, cultivation containers (bats), growth boards, and the like.

The binder resin (C) contained in the dispersion (E) is desirably selected from resin solutions, resin dispersions, and curable liquid resins that can impart adhesiveness to the application member. Examples of the binder resin (C) include acrylic resins, urethane resins, polyester resins, epoxy resins, alkyd resins, biodegradable resins such as cellulose, which are used as resins for coating agents and adhesives, UV curable ( A meth)acrylate resin or the like can be used. These resins may be used in combination as appropriate.
Water, an organic solvent, or the like can be appropriately used as a diluent for the dispersion (E). The dispersion (E) may be a solventless type such as a UV curable or thermosetting resin. An aqueous dispersion is preferred from the viewpoint of environmental friendliness and safety of coating workers.

(Hydroponic cultivation method)
In the hydroponic cultivation method of the present invention, plants are grown using the hydroponic culture medium of the present invention. More specifically, the hydroponic culture medium of the present invention, a light irradiation means for irradiating the hydroponic culture medium with visible light, and more preferably a vessel for holding the culture solution and a circulation means for circulating the culture solution. and are used to grow plants.
Here, as the culture solution, a culture solution generally used in hydroponics can be used, and examples thereof include an aqueous solution containing plant nutrients. Nutrients for plants include nutrients containing nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, and the like. Nutrients for plants include inorganic nutrients and organic nutrients containing these elements.
The nutrient composition of the plant in the culture solution is selected according to the growing plant and the growth state of the plant.

The light irradiating means is, for example, means for irradiating the growing plant and the hydroponic culture medium with visible light (for example, a device arranged at a position where the portion irradiated with light is above the container).
However, the light irradiating means may be a device that irradiates at least the hydroponic culture medium with visible light. On the other hand, when the hydroponic cultivation apparatus is installed indoors where sunlight does not reach or is difficult to reach, the light irradiation means is preferably a device that irradiates the plants and the hydroponic culture medium with visible light. .

The light irradiation means has a light source that emits visible light. Examples of the light source include an LED (Light Emitting Diode) unit, a laser unit, a fluorescent lamp, etc. Among them, an LED lighting means is preferable.

The irradiation time of the light irradiation means in hydroponics can be appropriately selected according to the type of growing plant, but for example, the irradiation time per day is 16 hours (8 hours in a dark place). be able to.
In addition, in the photocatalyst composition (B) according to the present invention, when a copper compound is used as the metal, the photocatalyst composition (B) supporting the copper compound is also excellent in dark place activity. is effective in suppressing

<Hydroponic equipment>
In order to carry out the hydroponic cultivation method of the present invention, for example, plants can be cultivated using the hydroponic cultivation apparatus shown in FIGS.
A hydroponic cultivation apparatus (10) shown in FIGS. 4 and 5 is an apparatus for growing a plant (11) supported on a culture medium (14) using a culture solution (12). The hydroponic cultivation apparatus has a cultivation container (13), a culture solution circulation filtration pump (16), light irradiation means (20), and a light source (21).
In the hydroponic cultivation apparatus (10) shown in FIGS. 4 and 5, the cultivation medium (14) includes a plant support portion (14a) for supporting the plant (11) and the plant support portion (14a). and a holding portion (14b) for holding. In the holding part (14b), if the opening for inserting the plant support part (14a) is narrow and the plant is held by the holding part even if the plant is directly inserted into the opening, The plant support portion (14a) may not be provided.

In the hydroponic cultivation system, there is a particular concern about the growth of algae in the areas that come into contact with the culture solution. It is therefore preferred to apply the dispersion according to the invention to such locations. In particular, it is preferable to apply the dispersion liquid (E) according to the present invention to hydroponic culture media, cultivation containers (bats), cultivation boards, and the like in which algae easily grow by light irradiation.

The contents and effects of the present invention will be described in more detail below by way of examples, but the present invention is not limited to these. In addition, "parts" shown below represent "parts by mass".

<Porous material>
(1) Porous material A1
A soft urethane foam (open cell type) with a thickness of 28 mm is cut so that one block can be separated into 23 mm squares, and a cross cut is made in the center of each block for seed planting. Used as material A1.
The apparent density of the porous material A1 was 13 kg/m ³ .

<Photocatalytic composition>
(1) Titanium oxide composition b
According to a general sulfuric acid method, sulfuric acid, water, and iron were added and dissolved in a mixture of ilmenite ore, niobium pentoxide, and zirconium oxide to obtain a solution containing titanium sulfate and iron sulfate as main components.
Impurities such as iron sulfate were removed, followed by thermal hydrolysis to obtain a hydrous titanium hydroxide composition. The titanium hydroxide composition was washed, calcined at 900° C., and the obtained solid was pulverized to obtain a titanium oxide composition b having the following characteristics.
a) Crystalline rutile-type titanium oxide b) Physical properties ・BET specific surface area: 9.0 m ² /g
・Rutilization rate: 95.4%
・Primary particle size: 0.18 μm
・Zr/Ti ratio: 0.05
・Nb/Ti ratio: 0.17

(2) Photocatalyst composition B1
a) Mixing step (reaction step)
600 parts by mass of the titanium oxide composition b, 8 parts by mass of copper (ii) chloride dihydrate, and 900 parts by mass of water were mixed in a stainless container. Next, the mixture was stirred with a stirrer (“Robomix” manufactured by Tokushu Kika Kogyo Co., Ltd.), and a 1 mol/L sodium hydroxide aqueous solution was added dropwise until the pH of the mixture reached 10.
b) Dehydration step Filtration under reduced pressure was performed with a qualitative filter paper (5C) to separate the solid content from the mixed solution, and the solid content was washed with ion-exchanged water. The washed solid was then dried at 120° C. for 12 hours to remove moisture. After drying, a powdery titanium oxide composition was obtained with a mill ("Milcer" manufactured by Iwatani Sangyo Co., Ltd.).
c) Heat treatment step The powdery titanium oxide composition obtained in the dehydration step b) above is heated at 450°C for 3 hours in the presence of oxygen using a precision thermostat ("DH650" manufactured by Yamato Scientific Co., Ltd.). After heat treatment, a photocatalyst composition B1 containing titanium oxide on which a divalent copper compound was supported was obtained.
The amount of the divalent copper compound supported in the titanium oxide on which the divalent copper compound was supported was 0.5% by mass with respect to the titanium oxide.

<Photocatalyst dispersion>
(1) Photocatalyst dispersion G1
25 parts of photocatalyst composition B1, 75 parts of water, and 8 parts of wetting and dispersing agent F1 (acid value 75 mgKOH/g, BYK-Chemie Co., Ltd. "DISPERBYK-194N") are mixed and stirred, and 100 parts of 1.0 mmφ ceramic beads are mixed. was added and ground in a sand grinder for 4 hours. After grinding, the beads were separated from the dispersion liquid to obtain a photocatalyst dispersion G1.

<Dispersion>
(1) Dispersion E1
Water 561 parts by mass, photocatalyst dispersion G1 (solid content 25% by mass) 20 parts by mass, polycarbonate-polyurethane resin water dispersion C1 ("Hydran WLS-210" manufactured by DIC Corporation) 19 parts by mass (total 600 parts by mass) were uniformly mixed using a dispersion stirrer (TK Homodisper manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a dispersion E1 for processing the medium.
The solid content of this dispersion was 19.2% by mass, and the solid content ratio of the photocatalyst composition B1 and the binder resin C1 was 44:56.

(Example 1)
<Preparation of hydroponic culture medium>
By impregnating the porous material A1 with the dispersion E1 using an impregnation tank, a squeeze roll, and a drying oven, and drying the porous material A1, a hydroponic culture medium in which the photocatalyst composition was supported on the porous material was produced.
That is, the above dispersion E1 was placed in an impregnation tank, 28 mm thick flexible urethane foam A1 was supplied into the bath, and the squeezing roll interval was adjusted so that the dry weight of the dispersion was 0.6 kg/m ³ . Next, the soft urethane foam A1 was passed through a squeezing roll and dried with hot air in a drying furnace set at 120° C. to obtain the target hydroponic culture medium.
Using the hydroponic culture medium, the growth of algae and the growth of lettuce were evaluated by the methods described below.

(Comparative example 1)
Algae generation and lettuce growth were evaluated in the same manner as in Example 1, except that the photocatalyst composition-unsupported porous material A1 was used as the hydroponic culture medium.

(Comparative example 2)
As the porous material, the flexible polyurethane foam described in Japanese Patent No. 2813693 was used as a reference.
The hydroponic culture medium is a commercially available antibacterial sponge that is a soft urethane foam containing a silver-based antibacterial agent (Crypika Sponge Ag antibacterial product manufactured by Kikuron Co., Ltd.; apparent density 30 kg/m ³ ) processed to the same dimensions as the porous material A1. In the same manner as in Example 1, algae generation and lettuce growth conditions were evaluated, except that the conditions were as follows.

<Evaluation method>
[Method for measuring BET specific surface area of titanium oxide]
Using a fully automatic BET specific surface area measuring device "MacSORBHM model-1208" manufactured by Mountec Co., Ltd., measurement was performed by specific surface area measurement (BET 1-point method).

[Method for measuring rutilization rate of titanium oxide]
Using an X-ray diffractometer "XRD-6100" manufactured by Shimadzu Corporation, the ratio of the peak height corresponding to the rutile type crystal was compared to the peak height corresponding to the entire titanium oxide crystal (rutile type, brookite type, anatase type). calculated from

[Calculation method of Zr/Ti ratio and Nb/Ti ratio of titanium oxide]
Using a fluorescent X-ray analyzer "SEA1200VX" manufactured by Seiko Instruments Inc., a metal elemental composition analysis was performed by a bulk fundamental parameter (bulk FP) method.
Regarding the fluorescence intensity (cps: count per second) of each metal element obtained by measuring the titanium oxide sample, the intensity of the fluorescence intensity (cps) of zirconium or niobium when the fluorescence intensity (cps) of titanium is taken as 100 The ratios were calculated as Zr/Ti ratios or Nb/Ti ratios, respectively.

[Method for measuring amount of divalent copper compound supported on titanium oxide]
Titanium oxide was completely dissolved in a hydrofluoric acid solution, and the extract was analyzed by an ICP emission spectrometer to quantify the supported amount (parts by mass) of the divalent copper compound with respect to 100 parts by mass of titanium oxide.

[Evaluation of algae resistance]
As fertilizers, 11 g of OAT House No. 1, 7.5 g of OAT House No. 2, and 0.5 g of OAT House No. 5 were dissolved in 10 liters of tap water to prepare a plant culture solution. The EC value of the medium during testing remained between 1.0 and 2.0 mS/cm.
The culture solution was placed in a seedling-growing bat to a water depth of about 15 mm, and 4×10 medium mats were immersed. The growth of algae in the vat was observed with and without sowing lettuce seeds under an LED lighting irradiation time of 16 hours/day and a growth environment temperature of 22°C. Evaluation was performed as follows.
-Evaluation criteria-
5: No algae 4: Slight algae 3: More than 1/4 covered by algae 2: More than 1/2 covered by algae 1: Entirely covered by algae

[Evaluation of growing status of lettuce]
The state of growth of lettuce in the seeding bat of lettuce seeds used for evaluation of algae resistance was observed based on Comparative Example 1, and evaluated as follows.
-Evaluation criteria-
5: Faster growth than Comparative Example 1 4: Equivalent growth to Comparative Example 1 3: Less than 1 week delay in growth compared to Comparative Example 1 2: More than 1 week delay in growth compared to Comparative Example 1 1: Nearly do not grow

(Evaluation results)
1 to 3 show the results of follow-up observation of the state of algal growth in the bat and the state of lettuce growth in Example 1, Comparative Example 1, and Comparative Example 2 with or without sowing lettuce seeds. FIG. 1 is a photograph showing the observation results on the 7th day, FIG. 2 is a photograph showing the observation results on the 14th day, and FIG. 3 is a photograph showing the observation results on the 21st day. In addition, in Example 1, Comparative Example 1, and Comparative Example 2, the observation results of the state of algae generation in the bat with and without seeding of lettuce seeds and the state of lettuce growth were evaluated according to the above evaluation criteria, and the results are shown in the table below. 1.

It can be seen that Example 1 suppresses the generation of algae as compared with Comparative Example 1. On the other hand, in Comparative Example 2, algae growth was greatly suppressed, but the growth of lettuce was significantly inhibited.
It was confirmed that hydroponics using a medium supporting the photocatalyst composition of the present invention can achieve both the contradictory effects of less inhibition of crop growth and suppression of algae growth.

Claims

A hydroponic culture medium in which a photocatalyst composition (B) is supported on a porous material (A),
The photocatalyst composition (B) is a hydroponic culture medium, which is a photocatalyst composition in which a metal is supported on a titanium oxide composition.
The hydroponic culture medium according to claim 1, wherein the titanium oxide composition contains rutile-type titanium oxide.
The hydroponic culture medium according to claim 1 or 2, wherein the metal is a transition metal or a typical metal.
The hydroponic culture medium according to any one of claims 1 to 3, wherein the titanium oxide composition substantially contains at least one metal element selected from the group consisting of zirconium and niobium.
The hydroponic culture medium according to any one of claims 1 to 4, wherein the porous material (A) is a foam containing an open cell structure.
The hydroponic culture medium according to claim 5, wherein the porous material (A) is urethane foam.
7. The hydroponic culture medium according to claim 6, wherein said porous material (A) is urethane foam having a density of 10 to 30 g/m 3 .
The hydroponic culture medium according to any one of claims 1 to 7, wherein the photocatalyst composition (B) is supported on the porous material (A) via a binder resin (C).
The hydroponic culture medium according to claim 8, wherein the binder resin (C) is a urethane resin or an acrylic resin.
A method for producing a hydroponic culture medium for producing the hydroponic culture medium according to any one of claims 1 to 9,
a step of dispersing the photocatalyst composition (B) and the binder resin (C) in the medium (D) to obtain a dispersion (E);
a step of impregnating the porous material (A) with the dispersion (E);
a step of drying and removing the medium (D) from the porous material (A);
A method for producing a hydroponic culture medium having
The method for producing a hydroponic culture medium according to claim 10, wherein the medium (D) contains water.
The dispersion (E) further contains a wetting and dispersing agent (F),
The method for producing a hydroponic culture medium according to claim 10 or 11, wherein the wetting and dispersing agent (F) is a copolymer having an ammonium base or a copolymer having a free fatty acid group and an acid value of 10 mg KOH/g or more.
A hydroponic cultivation method using the hydroponic cultivation medium according to any one of claims 1 to 9 and light irradiation means.
A dispersion for suppressing the growth of algae used in hydroponics,
The dispersion (E), which is a dispersion for suppressing the growth of algae, contains at least a medium (D) and a photocatalyst composition (B),
The photocatalyst composition (B) is a dispersion liquid for suppressing the growth of algae, which is a photocatalyst composition in which a metal is supported on a titanium oxide composition.
The dispersion for suppressing the growth of algae according to claim 14, wherein the titanium oxide composition contains rutile-type titanium oxide.
The dispersion for suppressing the growth of algae according to claim 14 or 15, wherein the metal is a transition metal or a typical metal.
The dispersion for suppressing the growth of algae according to any one of claims 14 to 16, wherein the titanium oxide composition substantially contains at least one metal element selected from the group consisting of zirconium and niobium.
The dispersion for suppressing the growth of algae according to any one of claims 14 to 17, further comprising a binder resin (C).
The dispersion liquid for suppressing the growth of algae according to claim 18, wherein the binder resin (C) is a urethane resin or an acrylic resin.
The dispersion for suppressing the growth of algae according to any one of claims 14 to 19, wherein the medium (D) contains water.
The dispersion (E) further contains a wetting and dispersing agent (F),
The wetting and dispersing agent (F) is a copolymer having an ammonium base, or a copolymer having an acid value of 10 mg KOH / g or more having a free fatty acid group, suppression of algae growth according to any one of claims 14 to 20 dispersion for