TW202116820A - Water-retaining material - Google Patents

Abstract

The present invention relates to a water-retaining material comprising a water-absorbent resin and one or more substances selected from the group consisting of acetic acid and acetic acid derivatives.

Description

Water retention material

The present invention relates to water-retaining materials.

Recently, with chronic water depletion, attempts have been made to effectively and appropriately use agricultural water, and to maintain or increase the yield of agricultural products even with a smaller amount of irrigation water than before (for example, Patent Documents 1 to 3). These agricultural water-retaining materials use super absorbent resin (SAP) as the main component, and because they exhibit effects in a very small amount when compared with peat moss, which is used to improve the water retention of soil, for example, it has an agricultural function. It has the advantage of less burden during use. However, the conventional water-absorbent resin obviously exerts an adverse effect on the germination of seeds or the growth of plants (Patent Document 4 and Non-Patent Document 1). As the reason, Patent Document 4 describes that roots cannot effectively use the water-absorbent resin. water.

On the other hand, in order to increase the drying tolerance of the plant itself in a dry state, for example, Patent Document 5 discloses the administration of acetic acid to the plant. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 1998/005196 Pamphlet [Patent Document 2] JP 2013-544929 A [Patent Document 3] JP 2013-540164 A [Patent Document 4] JP 2009-148163 A [Patent Document 5] U.S. Patent Publication No. 2012/0227134 [Non-Patent Literature]

[Non-Patent Document 1] Sugimura Juno et al., Utilization of Super Absorbent Polymers as Materials for Green Chemical Industry, Green Chemical Technology, 9(2), 11-15, 1983

[The problem to be solved by the invention]

Since the above-mentioned water-absorbent resin has an ionic functional group, an osmotic pressure difference occurs between the inside and outside of the resin during water immersion, and can absorb a large amount of water. However, according to research conducted by the inventors of the present application, it is known that if the concentration of the ionic functional group is too high, the roots cannot absorb water from the resin, and on the contrary, the resin absorbs water from the roots. Furthermore, it is considered that if the water-absorbent resin dries, the concentration of ionic functional groups will further increase, so that the water flowing out from the roots will further increase, and it will give an adverse effect on the growth of plants. In other words, it was discovered that if the water-absorbent resin is added, the soil becomes difficult to dry, but once it dries, it may adversely affect the problem.

On the other hand, the inventors of the present case discovered that when the method of imparting drying tolerance to the plant itself described in Patent Document 5 was applied to seedlings, the seedlings were raised using shallow boxes with openings on the bottom, which are generally called seedling boxes. , So water, nutrients, etc. flow out from the bottom surface, and the amount that plants can actually use is a small amount compared to the amount of injection. Therefore, it has been found that in the above method, soil is easy to dry, and plants cannot fully utilize acetic acid, etc., so that the desired drying tolerance cannot be obtained. Furthermore, it is known that the growth of plants is inhibited because the pH of the soil temporarily drops.

Therefore, the object of the present invention is to solve the above-mentioned problems and provide a water-holding material that imparts sufficient drying tolerance to plants and promotes the growth of plants. [Means to solve the problem]

As a result of intensive research, the inventors of the present case have found that a water-retaining material containing a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives can solve the above-mentioned problems.

That is, the present invention includes the following suitable aspects. [1] A water-retaining material comprising a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. [2] The water-retaining material as described in [1], wherein the content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives is 0.001% by mass to 70% by mass relative to the mass of the water-retaining material . [3] The water retaining material according to [1] or [2], wherein the acetic acid derivative is one or more compounds selected from the group consisting of sodium acetate, magnesium acetate, potassium acetate, ammonium acetate, and calcium acetate. [4] The water-retaining material according to any one of [1] to [3], wherein the water-absorbent resin contains selected from the group consisting of vinyl alcohol-based polymers, acrylic polymers, acrylamide-based polymers, and methacrylic acid. A polymer of the group of polymers and starch-based polymers. [5] The water retaining material according to [4], wherein the vinyl alcohol-based polymer contains a copolymer containing a monomer structural unit having a vinyl alcohol structural unit and an ionic group or a derivative thereof. [6] The water-retaining material according to [4] or [5], wherein the vinyl alcohol polymer contains potassium ion or ammonium ion as a relative cation of the ionic group. [7] The water-retaining material according to any one of [4] to [6], wherein the vinyl alcohol-based polymer has a cross-linked structure. [8] The water-holding material as described in any one of [1] to [7], which is used for agriculture. [9] The water-holding material as described in any one of [1] to [8], which is used for nursery. [10] The water-retaining material according to any one of [1] to [9], wherein the water-absorbent resin is contained in the resin and contains an element that does not constitute the polymer skeleton of the resin, and the element is selected from the group consisting of phosphorus One or more elements from the group of element, potassium element, and nitrogen element. [11] The water-retaining material as described in [10], wherein the content of one or more elements selected from the group consisting of phosphorus, potassium, and nitrogen, present in the resin, is relative to the mass of the resin 0.001% by mass or more and 50% by mass or less. [12] The water-retaining material according to [10] or [11], wherein the water-retaining material further contains a water-retaining material that is not present in the resin but is present in the water-retaining material and is selected from the group consisting of phosphorus, potassium, and nitrogen. More than one element. [13] The water-retaining material as described in any one of [10] to [12], wherein the aforementioned 1 is selected from the group consisting of phosphorus, potassium, and nitrogen, which is not present in the resin but is present in the water-retaining material The content of more than one element is 0.001% by mass to 50% by mass relative to the mass of the aforementioned resin. [14] The water-retaining material according to any one of [1] to [13], wherein the water-absorbent resin is contained within the water-absorbing resin in an amount of 0.00001 mass% or more and 10 mass% or less relative to the mass of the resin The above-mentioned agents that kill microorganisms or inhibit the proliferation of microorganisms. [15] The water-retaining material according to [14], wherein the water-retaining material further contains one or more of the aforementioned agents that are not present in the water-absorbing resin but are present in the water-retaining material. [16] The water-retaining material as described in [15], wherein the content of one or more agents not present in the water-absorbing resin but present in the water-retaining material is 0.00001 mass% or more and 10 mass% relative to the mass of the resin %the following. [17] The water-retaining material according to any one of [1] to [16], wherein the water-retaining material in the water-absorbing state of water that is 50 mass times the mass of the water-retaining material, the plant can absorb The proportion of water is 7.6% by mass or more based on the mass of the aforementioned water-retaining material in the water-absorbent state. [18] The water-retaining material according to any one of [1] to [17], wherein the water-retaining material further contains an SP value of 6.0 (cal/cm ³ ) ^1/2 or more and 30.0 (cal/cm ³ ) ^{1/ 2} or less compound (Y). [19] The water-retaining material as described in [18], wherein the aforementioned compound (Y) is selected from the group consisting of water, glycerol, methanol, dimethyl sulfoxide, ethanol, acetonitrile, isopropanol, N-methyl-2- One or more compounds in the group of pyrrolidone, methyl acetate, tetrahydrofuran, diethyl ether, N,N-dimethylformamide and ethylene glycol. [20] The water-retaining material according to [18] or [19], wherein the content of the compound (Y) relative to the mass of the water-retaining material is 0.001% by mass to 98% by mass. [Effects of Invention]

According to the present invention, it is possible to provide a water-holding material that imparts sufficient drying tolerance to plants and promotes the growth of plants.

[Form to implement the invention]

The following is an illustration of an embodiment of the present invention, and it is not intended to limit the present invention to the following embodiment.

＜Water retention material＞ The water-retaining material of the present invention contains a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives.

The inventors of the present case discovered that the water-retaining material of the present invention imparts sufficient drying tolerance to plants and promotes the growth of plants. The water-retaining material of the present invention has a high affinity with one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, and the aforementioned compounds easily penetrate into the resin. Therefore, the aforementioned compound is prevented from flowing out of the bottom surface of the nursery box, and it is considered that the amount of the plant can be used is larger than that in the case of direct administration. Furthermore, since the impregnated compound is slowly released into the culture medium with the passage of time, it is considered that the plant can use the slowly released compound over a long period of time. In addition, since it is also possible to prevent plants from being exposed to the aforementioned compounds at a high concentration that can cause adverse effects on plants, it is considered that the effect of promoting growth can be obtained. However, assuming that the actual situation is different from the aforementioned estimation, it is also included in the scope of the present invention. Therefore, the fact that a water-retaining material containing a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives has the effect of promoting plant growth is clarified for the first time in the present invention.

＜Acetic acid derivatives＞ The acetic acid derivative is not particularly limited. Examples include sodium acetate, magnesium acetate, potassium acetate, ammonium acetate, calcium acetate, methyl acetate, ethyl acetate, iron acetate, copper acetate, lithium acetate, rubidium acetate and acetic anhydride, etc., but from the affinity with water-absorbent resins In terms of good properties, sodium acetate, magnesium acetate, potassium acetate, ammonium acetate, and calcium acetate are preferred.

The molecular weight of the aforementioned acetic acid derivative is preferably 1000 or less, more preferably 500 or less. If the molecular weight of the acetic acid derivative is in the aforementioned range, it is preferable that the acetic acid derivative easily passes through the cell membrane of the plant and is easily used by the plant. The molecular weight of the aforementioned acetic acid derivative can be measured by, for example, gas chromatography mass spectrometry, liquid chromatography mass spectrometry, or the like.

The content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, relative to the mass of the water-holding material, is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and more preferably 0.01% by mass Above, more preferably 0.02 mass% or more, more preferably 0.05 mass% or more, still more preferably 0.1 mass% or more, still more preferably 0.3 mass% or more, still more preferably 1 mass% or more, particularly preferably 5 mass% Above, it is preferably 70% by mass or less, more preferably 65% by mass or less, still more preferably 60% by mass or less, still more preferably 55% by mass or less, particularly preferably 40% by mass or less. The content of the aforementioned compound can be measured by an appropriate measurement method such as ion chromatography and gas chromatography, depending on the type of compound. In the case of measuring by ion chromatography, the aforementioned compound is detected as acetate ion, and the content of acetate ion relative to the mass of the water-holding material is preferably 0.0005 mass% or more, more preferably 0.003 mass% or more, and more preferably 0.005 Mass% or more, more preferably 0.01 mass% or more, more preferably 0.03 mass% or more, more preferably 0.05 mass% or more, still more preferably 0.3 mass% or more, still more preferably 0.5 mass% or more, particularly preferably 3 % By mass or more, preferably 66% by mass or less, more preferably 63% by mass or less, still more preferably 60% by mass or less, still more preferably 50% by mass or less, particularly preferably 30% by mass or less. The content when measured by gas chromatography is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, more preferably 0.01 mass% or more, still more preferably 0.02 mass% or more, more preferably 0.05 mass% Above, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, still more preferably 1% by mass or more, particularly preferably 5% by mass or more, preferably 70% by mass or less, more preferably 65% by mass Hereinafter, it is more preferably 60% by mass or less, still more preferably 55% by mass or less, and particularly preferably 40% by mass or less. If the content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives is within the aforementioned range, it is preferable to impart sufficient drying tolerance to plants and less likely to adversely affect plants. The aforementioned amount can be adjusted to the aforementioned range according to, for example, the feed amount during the production of the water-retaining material, washing conditions, and the like.

In the above-mentioned embodiment, the content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives in the water-retaining material is preferably 0.001% by mass or more relative to the mass of the resin, and more preferably 0.005 mass% or more, more preferably 0.01 mass% or more, more preferably 0.02 mass% or more, more preferably 0.05 mass% or more, still more preferably 0.1 mass% or more, still more preferably 0.3 mass% or more, particularly preferred It is 1% by mass or more, more preferably 5.3% by mass or more, preferably 250% by mass or less, more preferably 200% by mass or less, still more preferably 150% by mass or less, and still more preferably 130% by mass or less, Particularly preferably, it is 70% by mass or less. The quality of the resin at this time is the quality of its dry state. The so-called "dry state" in the present invention may mean that the resin does not contain water or water in a detectable amount (for example, 0.1% by mass or more) by a general method (for example, the mass change before and after heating at 60°C under vacuum). The state of volatile components such as organic solvents.

＜Water Absorbent Resin＞ The water-absorbent resin in the present invention is not particularly limited. As the water-absorbent resin, for example, acrylic polymers, isobutylene-maleic acid copolymers, carboxymethyl cellulose polymers, saponification polymers of acrylonitrile, alginate polymers, sulfonic acid polymers can be used. Polymers, vinyl acetate-maleic anhydride-based copolymers, N-vinylacetamide-based polymers, acrylamide-based polymers, methacrylic acid-based polymers, starch-based polymers, and glycol-based polymers , And vinyl alcohol polymers, etc. These polymers can be used individually by 1 type or in combination of 2 or more types.

The aforementioned water-absorbent resin preferably contains vinyl alcohol-based polymers, acrylic-based polymers, acrylamide-based polymers, methacrylic-based polymers, and starch-based polymers from the viewpoints of ease of production and water retention. Preferably, it contains a vinyl alcohol-based polymer, and a preferred embodiment is that the water-absorbent resin is a vinyl alcohol-based polymer.

＜Vinyl alcohol polymer＞ As a vinyl alcohol polymer [hereinafter, sometimes referred to as a vinyl alcohol polymer (A)], for example, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and their vinyl alcohol unit by acetalizing agent Those who have been acetalized. From the viewpoint of good affinity with one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, it is preferable that the vinyl alcohol polymer (A) contains a vinyl alcohol structural unit and an ionic group. Or a copolymer of monomeric structural units of its derivatives. The ionic group or its derivative is preferably a carboxyl group, a sulfonic acid group, an ammonium group or a salt thereof, and more preferably a carboxyl group or a salt thereof. The content of the vinyl alcohol polymer (A) in the water-absorbent resin is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% by mass or more , Can also be 100% by mass. Furthermore, the content of the aforementioned copolymer in the vinyl alcohol polymer (A) is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% by mass % Or more, particularly preferably 100% by mass. That is, in a preferred embodiment, the vinyl alcohol-based polymer (A) is a copolymer containing a vinyl alcohol structural unit and a monomer structural unit having an ionic group or a derivative thereof.

In the case where the vinyl alcohol polymer (A) has a carboxyl group, a sulfonic acid group, and an ammonium group as an ionic group, examples of the vinyl alcohol polymer (A) include (i-1) selected from those having a carboxyl group and a sulfonic acid group. Saponified products of copolymers of one or more of monomers of acid groups and ammonium groups and derivatives of the monomers with vinyl esters; (i-2) Vinyl alcohol-based polymers and functional groups capable of reacting with hydroxyl groups ( b1) The reaction product of the compound (B) with a carboxyl group and/or a functional group (b2) that can be derivatized into a carboxyl group, etc.

In the above (i-1), the monomer having a carboxyl group is not particularly limited, but examples thereof include acrylic acid, methacrylic acid, itaconic acid, and maleic acid. In addition, as derivatives of the monomers having a carboxyl group, acid anhydrides, esterified products, and neutralized products of the monomers can be exemplified. For example, methyl acrylate, methyl methacrylate, dimethyl iconate, etc. can be used. Monomethyl maleate, maleic anhydride, etc.

In the above (i-1), the monomer having a sulfonic acid group is not particularly limited, but examples thereof include vinylsulfonic acid, 2-propenamide-2-methylpropanesulfonic acid, and p-styrenesulfonic acid. In addition, examples of derivatives of the monomer having a sulfonic acid group include esterified products and neutralized products of the monomers. For example, sodium vinyl sulfonate, 2-propenamide-2-methylpropane, etc. can be used. Sodium sulfonate and sodium p-styrene sulfonate, etc.

In the above (i-1), the monomer having an ammonium group is not particularly limited, but examples include diallyl dimethyl ammonium chloride, vinyl trimethyl ammonium chloride, and allyl trimethyl ammonium chloride. Methylammonium, p-vinylbenzyltrimethylammonium chloride and 3-(methacrylamide)propyltrimethylammonium chloride. Moreover, as a derivative of the monomer having an ammonium group, the amine of the monomer can be cited. For example, diallylmethylamine, vinylamine, allylamine, and p-vinylbenzyldimethylamine can be used. Base amine and 3-(methacrylamide) propyl dimethyl amine, etc.

In the above (i-1), the vinyl ester is not particularly limited, but vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl stearate, vinyl benzoate, three Vinyl fluoroacetate, trimethyl vinyl acetate, etc. are preferably vinyl acetate.

The method for producing the saponified product of (i-1) is not particularly limited. A well-known polymerization initiator can be used, and one or more selected from a monomer having a carboxyl group and a derivative of the monomer and a vinyl ester can be well-known. The polymerization reaction is followed by a saponification reaction in a well-known method to produce.

In the compound (B) used in the above (i-2) having a functional group (b1) that can react with a hydroxyl group, a carboxyl group and/or a functional group (b2) that can be derivatized into a carboxyl group, as a functional group that can react with a hydroxyl group (b1) is not particularly limited, but examples thereof include aldehyde groups, carboxyl groups, amine groups, and derivatives of these functional groups. Among them, from the viewpoint of ease of production and durability of the vinyl alcohol polymer, aldehyde groups and derivatives of aldehyde groups are preferred. That is, the compound (B) is preferably an aldehyde having a carboxyl group and/or a derivative of the aldehyde.

That is, as the reactant of (i-2), it is preferable that at least a part of the vinyl alcohol unit is acetalized by one or more selected from the group consisting of an aldehyde having a carboxyl group and/or a derivative of the aldehyde. Vinyl alcohol polymer [hereinafter, sometimes referred to as vinyl alcohol polymer (A-1)].

The aldehyde having a carboxyl group in the compound (B) is not particularly limited, but examples thereof include glyoxylic acid, 2-methanylpropionic acid, 3-methanylpropionic acid, and phthalic acid. Among them, glyoxylic acid is preferred from the viewpoint of ease of acquisition and biodegradability. In addition, as the derivative of the aldehyde having a carboxyl group of the aforementioned compound (B), anhydrides, hydrates, esters, acetals, and neutralized products of the aldehyde can be cited. For example, glyoxylate, acetaldehyde, etc. can be used. Alkoxylic acid monohydrate, glyoxylic acid ester and glyoxylic acid dimethyl acetal, etc.

Examples of the relative cation of the glyoxylate include alkali metal ions such as sodium ion, potassium ion, and lithium ion; alkaline earth metal ions such as calcium ion and magnesium ion; and organic cations such as ammonium ion and alkylammonium ion. Wait. Among them, from the viewpoint of good affinity with acetic acid and acetic acid derivatives, potassium ion, ammonium ion, calcium ion, and magnesium ion are preferred. From the viewpoint of plant growth, potassium ion and ammonium ion are more preferable, and from the viewpoint of ease of production, potassium ion is more preferable.

Examples of the glyoxylate include methyl glyoxylate, ethyl glyoxylate, propyl glyoxylate, isopropyl glyoxylate, butyl glyoxylate, isobutyl glyoxylate, and acetaldehyde. 2-Butyl glyoxylate, tertiary butyl glyoxylate, hexyl glyoxylate, octyl glyoxylate, 2-ethylhexyl glyoxylate, etc.

There are no particular limitations on the production method of the vinyl alcohol polymer (A-1), and at least a part of the vinyl alcohol units of the vinyl alcohol polymer produced by a well-known method can be used in the presence or absence of a catalyst Next, it is produced by acetalizing at least one selected from an aldehyde having a carboxyl group and a derivative of the aldehyde.

Examples of the catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid; organic acids such as carboxylic acid and sulfonic acid; solid acids such as cation exchange resins and heterogeneous polyacids. These catalysts can be used alone or in combination of multiple types. In addition, since glyoxylic acid is also an acid that promotes the acetalization reaction, it also functions as a catalyst when producing the vinyl alcohol-based polymer (A-1). That is, from the viewpoint of ease of handling after the reaction, when producing the vinyl alcohol-based polymer (A-1), a method of using glyoxylic acid as the aldehyde having a carboxyl group is preferred.

The vinyl alcohol polymer used as a raw material in the production of the vinyl alcohol polymer (A-1) may be commercially available products manufactured industrially; vinyl carboxylates such as vinyl acetate and other monomers as required Coexist, use a well-known polymerization initiator to carry out the well-known polymerization reaction, and then carry out the saponification reaction by the well-known method; Produced by the cationic polymerization reaction and hydrolysis reaction of vinyl ether; Produced by the direct reaction of acetaldehyde Any one of polymerization manufacturers, etc., but it is preferably a manufacturer that saponifies polyvinyl acetate of polymerized vinyl acetate. The degree of saponification of the vinyl alcohol polymer used as the above-mentioned raw material is preferably 30 mol% or more, more preferably 60 mol% or more. In one embodiment of the present invention, from the viewpoint of easy introduction of an appropriate amount of carboxyl groups, further It is preferably 80 mol% or more, and more preferably 90 mol% or more.

The degree of acetalization of the vinyl alcohol polymer (A-1) is preferably 0.01 mol% or more and 85 mol% or less. If the degree of acetalization is within the aforementioned range, it is easy to improve water absorption. From the foregoing viewpoints, the degree of acetalization is preferably 0.1 mol% or more, more preferably 1 mol% or more, still more preferably 5 mol% or more, still more preferably 8 mol% or more, and particularly preferably 10 mol% or more, more preferably 80 mol% or less, more preferably 70 mol% or less, still more preferably 60 mol% or less, still more preferably 50 mol% or less, particularly preferably 45 mol% or less, more preferably 40 mol% or less.

From the viewpoint of easily inhibiting the elution of vinyl alcohol polymer (for example, during seedling raising, etc.), in the production of vinyl alcohol polymer (A-1), aldehydes having carboxyl groups and other derivatives other than the aldehydes can be used in combination Aldehydes to carry out the acetalization reaction. Examples of the other aldehydes include aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, secondary butyraldehyde, and tertiary butyl butyraldehyde; benzaldehyde, anisaldehyde, and cinnamon Aromatic aldehydes such as aldehydes, 4-benzyloxybenzaldehyde, 3-benzyloxybenzaldehyde, 4-pentyloxybenzaldehyde, and 3-pentyloxybenzaldehyde. Among them, formaldehyde, acetaldehyde, and n-butyraldehyde are preferred from the viewpoint of ease of production or the water absorption and strength of the obtained vinyl alcohol-based polymer. When other aldehydes are used in combination, the amount used is not particularly limited, but it is usually 0.01-30 mol%, preferably 0.1-10 mol% relative to the total of the aldehyde having carboxylic acid and derivatives of the aldehyde. , More preferably 1 to 5 mol%. If the amount of other aldehydes used is less than the aforementioned upper limit, the resulting vinyl alcohol polymer tends to be excellent in water absorption. If it is more than the aforementioned lower limit, it is easy to suppress ethylene caused by the combined use of other aldehydes. The effect of the elution of alcohol-based polymers during seedling cultivation. In addition, the aforementioned other aldehydes can be used as derivatives such as acetals.

In one embodiment of the present invention, when the vinyl alcohol polymer (A) has an ionic group (for example, a carboxyl group), part or all of the ionic group may be a salt (when the ionic group is a carboxyl group, it is a carboxylic acid Salt). Examples of the relative cation of the salt include alkali metal ions such as lithium ion, sodium ion, potassium ion, rubidium ion, and cesium ion; alkaline earth metal ion such as magnesium ion, calcium ion, strontium ion, and barium ion; aluminum Ions and other metal ions such as zinc ions; onium cations such as ammonium ions, imidazoliums, pyridiniums, and phosphonium ions. Among them, from the viewpoint of good affinity with acetic acid and acetic acid derivatives, potassium ion, ammonium ion, calcium ion, and magnesium ion are preferred. From the viewpoint of plant growth, potassium ion and ammonium ion are more preferable, and from the viewpoint of ease of production, potassium ion is more preferable. Therefore, in a preferred embodiment of the present invention, the vinyl alcohol polymer (A) contains potassium ion or ammonium ion as the relative cation of the ionic group, preferably potassium ion. In the case where the ionic group is a carboxyl group, as a method for producing a vinyl alcohol polymer (A) in which part or all of the carboxyl group is a carboxylate, for example, the above-mentioned (i-1) uses a monomer having a carboxyl group Method (I) of the neutralized product; Method (II) of the neutralized product using a compound having a functional group that can react with a hydroxyl group and a carboxyl group in the above (i-2); In the production of a carboxyl group by the above-mentioned various methods, etc. After the vinyl alcohol-based polymer (A), the neutralization method (III) and the like are carried out, of which the above-mentioned method (III) is preferred.

In one embodiment of the present invention, when the vinyl alcohol-based polymer (A) has ionic groups, the amount of ionic groups in the vinyl alcohol-based polymer (A) is relative to the above-mentioned vinyl alcohol-based polymer All structural units of (A) are preferably 0.1 mol% or more, more preferably 1 mol% or more, particularly preferably 3 mol% or more, most preferably 5 mol% or more, and preferably 80 mol% % Or less, more preferably 50 mol% or less, more preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 25 mol% or less, particularly preferably 20 mol% or less, most preferably Preferably, it is less than 18 mol%. If the amount of the ionic group is more than the aforementioned lower limit, the water absorption of the vinyl alcohol polymer used in the present invention is more excellent, and if it is less than the aforementioned upper limit, decomposition due to ultraviolet rays is less likely to occur and Maintain the retention of acetic acid and acetic acid derivatives. Furthermore, when the vinyl alcohol polymer (A) has a carboxyl group as an ionic group, the amount of the carboxyl group derived from acrylic acid or its salt among the carboxyl groups is preferably 20 relative to all the structural units of the vinyl alcohol polymer. Mole% or less, more preferably 15 mole% or less, particularly preferably 10 mole% or less, and may also be 0 mole%. If the amount of the carboxyl group derived from acrylic acid or its salt among the carboxyl groups is less than or equal to the aforementioned upper limit, it is easier to obtain more excellent weather resistance (particularly ultraviolet resistance). In addition, when part or all of the ionic groups contained in the vinyl alcohol polymer (A) take the form of derivatives (such as salts), the content of the above-mentioned ionic groups is that of the ionic groups and their derivatives. The content or the content of the derivative of the ionic group. In a preferred embodiment, more than half of the ionic groups contained in the vinyl alcohol-based polymer (A) are in the form of derivatives. In a more preferred embodiment, the vinyl alcohol-based polymer (A) is in the form of derivatives. Most of the ionic groups contained are in the form of derivatives. In a particularly preferred embodiment, all of the ionic groups contained in the vinyl alcohol polymer (A) are in the form of derivatives.

The content of the ionic group in the vinyl alcohol polymer (A), especially the amount of the above-mentioned carboxyl group and the amount of the carboxyl group derived from acrylic acid or its salt among the carboxyl groups, can be used, for example, by solid ¹³ C-NMR (nuclear magnetic resonance spectroscopy). Method), FTIR (Fourier Transform Infrared Spectroscopy) or acid-base titration. In addition, the "structural unit" in the present invention means the repeating unit constituting the polymer, for example, the vinyl alcohol unit counts as "1 unit", and the 2-unit vinyl alcohol unit is counted as "2 units".

The content of the vinyl alcohol structural unit of the vinyl alcohol polymer (A) is preferably more than 20 mol%, more preferably 50 mol% or more, relative to all the structural units of the vinyl alcohol polymer (A), More preferably, it is 60 mol% or more, more preferably 98 mol% or less, more preferably 95 mol% or less, and still more preferably 90 mol% or less. The content of the above-mentioned vinyl alcohol structural unit can be measured by, for example, FTIR (Fourier transform infrared spectroscopy), solid ¹³ C-NMR (nuclear magnetic resonance spectroscopy), etc., and can also be measured from acetic anhydride when reacted with a certain amount of acetic anhydride. To calculate the consumption.

The vinyl alcohol-based polymer (A) may contain structural units other than the vinyl alcohol structural unit. Examples of the above-mentioned other structural units include structural units derived from vinyl carboxylates such as vinyl acetate and trimethyl vinyl acetate; structural units derived from olefins such as ethylene, 1-butene, and isobutylene; and structural units derived from olefins such as ethylene, 1-butene, and isobutylene; Acrylic acid and its derivatives, methacrylic acid and its derivatives, acrylamide and its derivatives, methacrylamide and its derivatives, maleic acid and its derivatives, and maleimide derivatives, etc. Structural units, etc. The said other structural unit may contain 1 type, and may contain multiple types. The content of the above-mentioned other structural units, relative to all structural units of the vinyl alcohol polymer (A), is preferably 50 mol% or less, more preferably 30 mol% or less, and further preferably 15 mol% or less, or It is 0 mol%. If the content of the other structural unit is equal to or less than the aforementioned upper limit, the water-retaining material of the present invention can easily obtain more excellent water absorption and water absorption speed.

The viscosity average polymerization degree of the vinyl alcohol polymer (A) is not particularly limited, but from the viewpoint of ease of manufacture, it is preferably 20,000 or less, more preferably 10,000 or less, still more preferably 4,000 or less, particularly preferably 3,000 or less . On the other hand, from the viewpoints of the mechanical properties of the vinyl alcohol-based polymer (A) and the elution resistance to water, it is preferably 100 or more, more preferably 200 or more, and still more preferably 400 or more. The viscosity average degree of polymerization of the vinyl alcohol polymer (A) can be measured by a method in accordance with, for example, JIS K 6726. When the vinyl alcohol polymer (A) has a crosslinked structure as described later, for example, when the vinyl alcohol polymer (A) has an acetal structure or an ester structure as the crosslinked structure, the viscosity average degree of polymerization is measured It can be done after cutting the cross-linked structure. The aforementioned cutting can be performed by a general method (for example, hydrolysis using an acid or a base).

The vinyl alcohol-based polymer (A) used in the present invention preferably contains a cross-linked structure from the viewpoint of preventing the elution of the vinyl alcohol-based polymer during seedling raising. When the vinyl alcohol polymer (A) used in the present invention contains a cross-linked structure, it becomes a gel state when it absorbs water. The form of the cross-linked structure is not particularly limited, and examples thereof include cross-linked structures caused by ester bonds, ether bonds, acetal bonds, and carbon-carbon bonds.

As an example of the above-mentioned ester bond, when the vinyl alcohol polymer (A) contains a carboxyl group as an ionic group, an ester bond formed between a hydroxyl group and a carboxyl group possessed by the vinyl alcohol polymer (A) can be cited. As an example of the said ether bond, the ether bond formed by dehydration condensation between the hydroxyl groups which a vinyl alcohol-type polymer (A) has is mentioned. As an example of the above-mentioned acetal bond, when an aldehyde having a carboxyl group is used in the production of a vinyl alcohol-based polymer (A), the hydroxyl groups of two vinyl alcohol-based polymers (A) may be combined with the above-mentioned aldehyde. Acetal bond formed by acetalization reaction. Examples of the above-mentioned carbon-carbon bond include carbon-carbon formed by coupling between carbon radicals of the vinyl alcohol polymer (A), which is generated when the vinyl alcohol polymer (A) is irradiated with active energy rays. key. These cross-linked structures may be contained alone or in plural. Among them, from the viewpoint of ease of manufacture, a cross-linked structure due to ester bonds and acetal bonds is preferred, and from the viewpoints of water retention during seedling cultivation, retention of acetic acid and acetic acid derivatives, and UV resistance. , More preferably a cross-linked structure caused by acetal bonds. Such a cross-linked structure may be formed at the same time as the acetalization reaction in the step of acetalizing at least a part of vinyl alcohol units by using one or more selected from aldehydes having carboxyl groups and the aldehyde derivatives. It is formed in another step, but in the present invention, it is preferable to form a cross-linked structure by further adding a cross-linking agent.

As the crosslinking agent, glyoxal, malonaldehyde, succinic aldehyde, glutaraldehyde, 1,9-nonanedial, adipaldehyde, maleic aldehyde, tartaraldehyde, citral, o-phthalaldehyde, M-phthalaldehyde, terephthalaldehyde, etc.

In the case of adding a crosslinking agent, the amount of crosslinking in the vinyl alcohol polymer (A) is preferably 0.001 mol% or more, more preferably 0.005 mol% from the viewpoint of easy maintenance of water retention in the soil Above, more preferably 0.01 mol% or more, still more preferably 0.03 mol% or more, more preferably 0.5 mol% or less, more preferably 0.4 mol% or less, still more preferably 0.3 mol% or less .

＜Acrylic polymer＞ As a polymer which the said water-absorbent resin may contain, an acrylic polymer is mentioned. In this specification, the so-called acrylic polymer generally refers to homopolymers of acrylic acid or acrylic acid derivatives, and acrylic acid or acrylic acid derivatives as the main monomer (in the monomer components, the monomer with the most molar% (Body) acrylic copolymer obtained by copolymerization of monomer components. For example, as raw materials, acrylic acid, sodium acrylate, potassium acrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, secondary butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate and Examples of phenyl acrylate and the like include those obtained by copolymerizing one or more of these monomers with a crosslinking agent, or at least one of the aforementioned monomers, a crosslinking agent, and another copolymer that can be further copolymerized. At least one type of monomer is copolymerized using a well-known method. Specifically, for example, a crosslinked product of an acrylic acid-sodium acrylate copolymer and the like can be cited. Commercially available products include superabsorbent polymers (acrylic acid salt series); Wako Pure Chemical Industries, Ltd., Acryhope (registered trademark); Nippon Shokubai Co., Ltd., Sanwet (registered trademark); Sanyo Chemical Industry Co., Ltd. (Stock) system and so on.

＜Acrylic amide polymer＞ As the polymer that the water-absorbent resin may contain, an acrylamide-based polymer may be mentioned. In this specification, the so-called acrylamide-based polymer generally refers to a homopolymer of acrylamide or an acrylamide derivative, and an acrylamide or acrylamide derivative as the main monomer (monomer Among the ingredients, the monomer with the most mole%) is an acrylamide copolymer obtained by copolymerizing the monomer component. For example, the raw materials include acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-alkyl acrylamide, etc., and examples include combining one or more of these monomers with a crosslinking agent It is obtained by copolymerization, or obtained by polymerizing the aforementioned at least one monomer, a crosslinking agent, and another at least one monomer that can be further copolymerized using a well-known method. Specifically, for example, a cross-linked product of an acrylamide-acrylic acid-sodium acrylate copolymer, a cross-linked product of an acrylamide-acrylic acid-potassium acrylate copolymer, etc. are mentioned. As a commercially available product, Miracle-Gro (registered trademark) Water Storing Crystal; manufactured by Scotts Miracle Corporation, AQUASORB (registered trademark); SNF (stock) system, etc. can be cited.

＜Methacrylic polymer＞ As a polymer which the said water-absorbent resin may contain, a methacrylic polymer is mentioned. The so-called methacrylic polymer generally refers to homopolymers of methacrylic acid or methacrylic acid derivatives, and methacrylic acid or methacrylic acid derivatives as the main monomer (most of the monomer components are A methacrylic copolymer obtained by copolymerizing the monomer components of the monomer with the most ear%. For example, as raw materials, methacrylic acid, sodium methacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, propyl methacrylate, isopropyl methacrylate, and cyclohexyl methacrylate can be cited. Ester, phenyl methacrylate, methacrylic acid (2-ethylhexyl), methacrylic acid (tertiary butyl cyclohexyl), benzyl methacrylate and methacrylic acid (2,2,2-tri Fluoroethyl ester), etc., including those obtained by polymerizing one or more of these monomers, or those obtained by polymerizing at least one of the aforementioned monomers, a crosslinking agent, and another at least one that can be further copolymerized The monomer is copolymerized by a well-known method.

＜Starch polymer＞ Examples of the polymer that the water-absorbent resin may contain include starch-based polymers. Examples of starch-based polymers include those obtained by graft-polymerizing acrylic acid, sodium acrylate, potassium acrylate, and acrylonitrile to starch.

＜Phosphorus, Potassium and Nitrogen＞ In a preferred aspect of the present invention, the water-absorbent resin contained in the water-retaining material of the present invention is in the interior of the resin, and may contain an element that does not constitute the polymer skeleton of the resin, and the element is selected from the group consisting of phosphorus elements, One or more elements of the group of potassium element and nitrogen element. In this specification, the content of elements that do not constitute the polymer backbone of the resin inside the water-absorbent resin, as described in the examples below, generally refers to the content of the elements in the section of the untreated resin (the content of the constituent polymer contained in the resin The total value of the element content of the polymer skeleton and the content of elements that do not constitute the polymer skeleton), and the value calculated by subtracting the element content of the resin cross-section after the water washing and drying treatment (the content of the elements constituting the polymer skeleton).

The aforementioned phosphorus element, potassium element, and nitrogen element are known as the three elements of fertilizers. Examples of their sources include potassium sulfate, potassium chloride, potassium carbonate, potassium bicarbonate, ammonium chloride, ammonium nitrate, ammonium sulfate, and sodium nitrate. , Phosphoric acid, diammonium hydrogen phosphate, superphosphate, urea, calcium dihydrogen phosphate, potassium nitrate, potassium chloride, potassium hydroxide, ammonium ion, nitrate ion, nitrite ion, phosphate ion, dihydrogen phosphate ion, phosphoric acid one Compounds or ions having the foregoing atoms, such as hydrogen ion and potassium ion, are preferably diammonium phosphate, potassium sulfate, potassium chloride, potassium hydroxide, potassium nitrate, ammonium sulfate, urea, and Superphosphate.

The content of one or more elements selected from the group consisting of phosphorus element, potassium element and nitrogen element present in the resin is preferably 0.001% by mass or more, more preferably 0.05% by mass relative to the mass of the resin. Above, more preferably 0.1% by mass or more, still more preferably 1.0% by mass or more, more preferably 50% by mass or less, more preferably 40% by mass, still more preferably 30% by mass or less, and still more preferably 25% by mass or less. The quality of the resin at this time is the quality of the dry state. If the content of one or more elements selected from the group consisting of phosphorus element, potassium element, and nitrogen element present in the resin is within the aforementioned range, it is preferable that the element is easily released moderately from the resin. The content of one or more elements selected from the group consisting of phosphorus element, potassium element, and nitrogen element present in the aforementioned resin can be used, for example, by energy dispersive X-ray elemental analysis, ICP- as described in the examples below. AES (inductively coupled plasma atomic emission spectroscopy) method. The elements present in the aforementioned resin may be two or more of phosphorus element, potassium element and nitrogen element, preferably in the form of phosphorus element and potassium element, the form of phosphorus element and nitrogen element, and the form of potassium element and phosphorus element. Any of them. Moreover, it is preferable that it is all aspects of phosphorus element, potassium element, and nitrogen element. In addition, the total content of the phosphorus element, potassium element, and nitrogen element present in the resin is preferably 0.002 mass% or more, more preferably 0.06 mass% or more, and still more preferably 0.2 mass% relative to the mass of the resin. % Or more, more preferably 1.1% by mass or more, more preferably 70% by mass or less, more preferably 45% by mass or less, still more preferably 32% by mass or less, still more preferably 27% by mass or less, particularly preferred It is 10% by mass or less, and most preferably 5% by mass or less. The quality of the resin at this time is the quality of the dry state. The aforementioned amount can be adjusted to the aforementioned range by, for example, the amount of feed and washing conditions (number of times, time, etc.) during resin production.

The water-retaining material of the present invention may further contain one or more elements selected from the group consisting of phosphorus element, potassium element, and nitrogen element that are not present in the resin but are present in the water-retaining material.

The aforementioned one or more elements selected from the group consisting of phosphorus, potassium and nitrogen, which are not present in the resin but are present in the water-retaining material, may be the same as the aforementioned elements contained in the resin, or may be different .

The content of one or more elements selected from the group consisting of phosphorus, potassium, and nitrogen, which are not present in the resin but are present in the water-retaining material, is preferably 0.001% by mass or more relative to the mass of the resin , More preferably 0.3% by mass or more, still more preferably 1.0% by mass or more, still more preferably 1.5% by mass or more, preferably 50% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass % Or less, more preferably 10% by mass or less. The quality of the resin at this time is the quality of the dry state. If the content of one or more elements selected from the group consisting of phosphorus, potassium, and nitrogen, which are not present in the resin but exist in the water-retaining material, are within the aforementioned range, the plant is unlikely to cause root burns. Better. The aforementioned elements that are not present in the resin but are present in the water-retaining material may be two or more of phosphorus, potassium, and nitrogen, preferably in the form of phosphorus and potassium, and in the form of phosphorus and nitrogen. , Potassium and Phosphorus. Moreover, it is also preferable that it is all aspects of phosphorus element, potassium element, and nitrogen element. In addition, the total content of the phosphorus element, potassium element, and nitrogen element that are not present in the resin but present in the water-retaining material is preferably 0.4% by mass or more, more preferably 1.1% by mass or more, relative to the mass of the aforementioned resin. It is more preferably 1.6% by mass or more, more preferably 70% by mass or less, more preferably 25% by mass or less, still more preferably 17% by mass or less, still more preferably 11% by mass or less, particularly preferably 5% by mass the following. The quality of the resin at this time is the quality of the dry state. The aforementioned amount can be adjusted to be within the aforementioned range by, for example, the feed amount and washing conditions (number of times, time) during the production of the water-retaining material. In the present invention, the water-retaining material includes phosphorus element, potassium element, and nitrogen element from one or more compounds selected from the group including acetic acid and acetic acid derivatives, and 1 element selected from the group including acetic acid and acetic acid derivatives. In the case of the phosphorus element, potassium element, and nitrogen element in a compound other than one or more compounds, the aforementioned content is the total amount.

＜Pharmaceuticals＞ In a preferred aspect of the present invention, the water-absorbent resin contained in the water-retaining material of the present invention may contain at least one type of resin in an amount of 0.00001 mass% to 10 mass% relative to the mass of the aforementioned resin. Agents that kill microorganisms or inhibit the proliferation of microorganisms. Here, the term “one or more kinds of drugs” means that the drugs described later are contained alone or in combination of two or more kinds.

In the resin, the amount of the drug contained in the resin is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, particularly preferably 0.05% by mass or more, preferably 2% by mass or less, more preferably 1% by mass % Or less, particularly preferably 0.1% by mass or less. If the dosage is within the aforementioned range, the water-retaining material does not hinder the growth of plants and is easy to have excellent stability during storage and use. It is considered that this is because the drug is contained in the resin in an appropriate amount, and the drug is easily released from the resin in an appropriate amount during use. The aforementioned amount can be adjusted by the feed amount of the agent and the washing conditions (number of times, time) during the production of the water-retaining material, etc., and can be measured, for example, by the method described in the examples.

The drug contained in the resin should be capable of killing microorganisms (for example, fungi (such as molds and yeasts), slime molds, protists, single-celled algae, rickettsia, bacteria, viruses, etc.) ] Or an agent that inhibits the proliferation of microorganisms, and is not particularly limited. Examples of such agents include preservatives, bactericides, antibacterial agents, preservatives, and antifungal agents.

As an example of a preservative, sorbic acid and its salt, etc. can be mentioned.

(thiadiazine)劑、硫蘭劑等)、單硫代胺基甲酸酯、二硫代胺基甲酸酯、噻二

、磺醯胺、酞醯亞胺、石油醚、萘醌、苯醌、二硫化物、汞化合物(mercury(II) compound)、四氫酞醯亞胺、砷酸酯(arsenate)、銅鹽(Cupric salt)、有機銅劑(例如8-氧基喹啉銅等)、胍鹽、三

、二氫咪唑(glyoxalidine)鹽、喹啉鎓(quinolinium)鹽及巴豆酸苯酯等。Examples of fungicides or antibacterial agents include tetrachloroisophthalonitrile (TPN), Captan, vinclozolin, procymidone, and thiocyanate ( Benthiazole) agents, quaternary ammonium salts, phenolic compounds, quaternary pyridinium salts, peracids, formaldehyde, glutaraldehyde, antibiotics (for example, penicillin, streptomycin, chloramphenicol, etc.), N-chlorosuccinic acid Amines, limes, sulfur, organic sulfur agents (for example, Zineb, Maneb, thiadiene)

(thiadiazine) agent, thioblue agent, etc.), monothiocarbamate, dithiocarbamate, thiadiazine

, Sulfonamide, phthalimide, petroleum ether, naphthoquinone, benzoquinone, disulfide, mercury compound (mercury(II) compound), tetrahydrophthalimide, arsenate, copper salt ( Cupric salt), organic copper agents (e.g. 8-oxyquinoline copper, etc.), guanidine salt, three

, Dihydroimidazole (glyoxalidine) salt, quinolinium (quinolinium) salt and phenyl crotonate, etc.

Examples of preservatives or antifungal agents include halogen donors, especially chlorine donors, such as chlorine-cyanuric acid and its salts, especially monosodium or potassium dichloroisocyanurate; hydroxyquinones , Sulfite, silver and copper salts, etc.

In addition, the following agents are also exemplified as agents that have the effect of killing microorganisms or inhibiting the proliferation of microorganisms: water-soluble oxidants of hypochlorous acid (salt) as preservatives, bactericides, preservatives, or antifungal agents; as bactericides Or phenylphenols such as o-phenylphenol (except for methoxyphenols) as fungicides; benzoic acid or its esters as fungicides (preferably C ₁ ～C ₂₀ , more preferably C ₁ ~ C ₁₀ alkyl ester); hydroxybenzoate as a fungicide or an ester (preferably C ₁ ~ C _20, more preferably an alkyl ester of C ₁ ~ C _10). Among them, benzoic acid or its ester and hydroxybenzoic acid or its ester are preferred.

Examples of benzoic acid esters include methyl paraoxybenzoate (methyl 4-hydroxybenzoate), ethyl paraoxybenzoate (ethyl paraoxybenzoate), propyl paraoxybenzoate, and p-hydroxybenzoate. Isopropyl paraoxybenzoate, butyl paraoxybenzoate, isobutyl paraoxybenzoate, benzyl paraoxybenzoate, etc. In addition, examples of hydroxybenzoic acid include gallic acid, and examples of hydroxybenzoic acid esters include propyl gallate.

In one aspect of the present invention, the water-retaining material may further contain one or more of the aforementioned agents that are not present in the resin but are present in the water-retaining material.

In this aspect, the content of one or more medicaments that are not present in the resin but are present in the water-retaining material is preferably 0.00001 mass% or more, more preferably 0.001 mass% or more, relative to the mass of the aforementioned resin. It is preferably 0.01% by mass or more, more preferably 10% by mass or less, more preferably 0.3% by mass or less, and particularly preferably 0.05% by mass or less. The quality of the resin at this time is the quality of the dry state. If the aforementioned content is within the aforementioned range, the water-retaining material tends to have excellent stability during storage, does not hinder the growth of plants, and tends to have excellent stability when used not only in a short period of time but also over a long period of time. The aforementioned content can be adjusted by, for example, the feed amount of the chemical during the production of the water-retaining material and the washing conditions (number of times, time), etc., and can be measured by the method described in the examples.

In a preferred aspect of the present invention, in the water-retaining material in a water-absorbing state that is 50 times the mass of the water-retaining material of the present invention, the proportion of water that can be absorbed by plants is the same as the aforementioned water-absorbing state The quality of the water-retaining material is a reference, preferably 7.6% by mass or more, more preferably 10% by mass or more, still more preferably 30% by mass or more, particularly preferably 50% by mass or more. The upper limit of the aforementioned ratio is not particularly limited. The aforementioned ratio is usually 90% by mass or less.

In the present invention, the aforementioned so-called plant-absorbable water is the water released by the water-absorbing water-retaining material. By allowing the plant to absorb the water released from the water-absorbing water-retaining material, the plant can use the water for growth. If the water-holding material has a high water absorption capacity but has a low capacity to release absorbed water, it will be difficult for the plant to absorb a sufficient amount of water from the water-holding material. In a preferred aspect, since the water-retaining material of the present invention has a very good water release ability, plants can fully absorb water that can be used for growth from the water-retaining material. In addition, it is thought that with the release of water from the water-retaining material, since each component contained in the resin is appropriately released, the water-retaining material does not hinder the growth of plants, and it becomes easy to be used not only in a short period of time but also over a long period of time. The excellent stability.

The proportion of water that can be absorbed by the above-mentioned plants can be adjusted according to the amount of the cross-linked structure in the resin, the amount of the structural unit forming the carboxylate, and the type or amount of the agent contained in the water-holding material. For example, the above-mentioned ratio can be increased by increasing the amount of crosslinked structures in the resin, or reducing the amount of structural units forming carboxylate. The proportion of water that can be absorbed by the above-mentioned plants can be measured by the method described in the examples described later.

<Compound Y> In a preferred aspect of the present invention, the water-retaining material of the present invention may further contain a compound with an SP value of 6.0 (cal/cm ³ ) ^1/2 or more and 30.0 (cal/cm ³ ) ^1/2 or less (Y). By further containing the compound (Y) in the water-retaining material, it is possible to increase the water absorption speed of the water-retaining material and suppress the generation of dust.

The SP value of the compound (Y) is preferably 9.0 (cal/cm ³ ) ^1/2 or more, more preferably 11.0 (cal/cm ³ ) ^1/2 or more, and still more preferably 13.0 (cal/cm ³ ) ^{1/ 2} or more, preferably 29.0 (cal/cm ³ ) ^1/2 or less, more preferably 26.0 (cal/cm ³ ) ^1/2 or less, still more preferably 25.0 (cal/cm ³ ) ^1/2 or less. If the SP value is within the aforementioned range, it is easy to increase the water absorption speed of the water-retaining material and suppress the generation of dust. Here, the SP value in the present invention is based on the Fedors method [SP value basis, application and calculation method (published: Information Agency, Author: Hideki Yamamoto, 2005), RFFedors, Polym. Eng. Sci. 14,147 (1974)] The calculated SP value.

The compound (Y) having such an SP value is preferably selected from the group consisting of water, glycerol, methanol, dimethyl sulfoxide, ethanol, acetonitrile, from the viewpoint of easily achieving improvement in the water absorption speed of the water-retaining material and suppression of dust generation. One or more compounds in the group of isopropanol, N-methyl-2-pyrrolidone, methyl acetate, tetrahydrofuran, diethyl ether, N,N-dimethylformamide, and ethylene glycol.

When the water-retaining material contains the compound (Y), the content of the compound (Y) in the water-retaining material relative to the mass of the water-retaining material is preferably 0.001% by mass or more, more preferably 0.1% by mass or more, and still more preferably 1 Mass% or more, more preferably 5 mass% or more, particularly preferably 10 mass% or more (for example, 15 mass% or more), preferably 98 mass% or less, more preferably 90 mass% or less, still more preferably 80 % By mass or less, particularly preferably 50% by mass or less (for example, 40% by mass or less). If the content of the compound (Y) is within the aforementioned range, it is easy to increase the water absorption speed of the water-retaining material and suppress the generation of dust.

In the above aspect, the content of the compound (Y) in the water-retaining material is preferably 0.001% by mass or more, more preferably 1% by mass or more, and still more preferably 5% by mass or more relative to the mass of the resin. 11% by mass or more (for example, 18% by mass or more), preferably 4900% by mass or less, more preferably 900% by mass or less, still more preferably 400% by mass or less, particularly preferably 100% by mass or less (for example, 67% by mass) the following). The quality of the resin at this time is the quality of the dry state.

In a preferred aspect, the compound (Y) contains one or more compounds selected from the group consisting of water, glycerol, methanol, ethanol, and isopropanol, and the content of the compound is relative to the mass of the water-holding material , Preferably 3% by mass or more, more preferably 10% by mass or more, particularly preferably 15% by mass or more, preferably 90% by mass or less, more preferably 80% by mass or less, particularly preferably 40% by mass or less. In this aspect, in addition to the rapid water absorption speed of the water-holding material and low dust generation, it is easy to obtain an excellent germination rate. In this aspect, the content of the compound (Y) relative to the mass of the resin is preferably 3% by mass or more, more preferably 11% by mass or more, particularly preferably 18% by mass or more, and preferably 900% by mass or less, It is more preferably 400% by mass or less, and particularly preferably 67% by mass or less. The quality of the resin at this time is the quality of the dry state.

In a preferred aspect, the compound (Y) contains water or methanol. In another preferred aspect, the compound (Y) contains water. In another preferred aspect, the compound (Y) contains methanol. In these aspects, in addition to low dust generation and excellent germination rate, it is also easy to obtain the extremely rapid water absorption speed of the water-holding material. The content of water or methanol relative to the mass of the water-retaining material is preferably 3% by mass or more, more preferably 5% by mass or more, particularly preferably 10% by mass or more (for example, 15% by mass or more), and preferably 90% by mass Hereinafter, it is more preferably 80% by mass or less, and particularly preferably 40% by mass or less. In this aspect, the content of water or methanol relative to the mass of the resin is preferably 3% by mass or more, more preferably 5% by mass or more, particularly preferably 11% by mass or more (for example, 18% by mass or more). It is preferably 900% by mass or less, more preferably 400% by mass or less, and particularly preferably 67% by mass or less. The quality of the resin at this time is the quality of the dry state.

＜Additives＞ The water-retaining material of the present invention may optionally contain additives in addition to a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. Examples of such additives include polysaccharides such as sodium alginate, chitin, chitosan, cellulose and its derivatives; polyethylene, polypropylene, ethylene-propylene copolymer, and polystyrene. , Acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polycarbonate resin, polyethylene terephthalate, polybutylene terephthalate, polylactic acid, polysuccinic acid, poly Polyamide 6, polyamide 6･6, polyamide 6･10, polyamide 11, polyamide 12, polyamide 6･12, polyhexamethylene diamine terephthalamide, polyhexamethylene Methyl diamine isophthalamide, polynonamethylene diamine terephthalamide, polyphenylene ether, polyoxymethylene, polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene Resins such as methyl glycol and polyurethane; natural rubber, synthetic isoprene rubber, chloroprene rubber, silicone rubber, fluorine rubber, urethane rubber, acrylic rubber, Rubber and elastomers such as styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, ester-based thermoplastic elastomers, urethane-based thermoplastic elastomers, and amide-based thermoplastic elastomers; UV absorbers, antioxidants , Light stabilizers, defoamers, tackifiers, surfactants, lubricants, and antistatic agents, etc. These additives can be used individually by 1 type or in combination of 2 or more types. When the water-retaining material contains additives, the total content may be within a range that does not impair the effects of the present invention. The total mass of the water-retaining material is usually 20% by mass or less, and preferably 15% by mass or less.

The shape of the water-retaining material of the present invention is preferably particulate. When the water-retaining material of the present invention is in the form of particles, the volume average particle size of the particles is preferably 1 μm or more, more preferably 50 μm or more, still more preferably 100 μm or more, particularly preferably 300 μm or more, preferably 10,000 μm or less, more preferably It is 2000 μm or less, more preferably 1500 μm or less. If the volume average particle size is equal to or greater than the aforementioned lower limit value, handleability is excellent, and if it is equal to or less than the aforementioned upper limit value, an excellent water absorption speed can be easily obtained. The aforementioned volume average particle diameter can be measured by laser diffraction/scattering.

＜Manufacturing method of water retaining material＞ The water-retaining material of the present invention can be achieved by, for example: (ii-1) a method of mixing a water-absorbent resin, one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, and any of the above-mentioned additives; (ii-2) ) One or more compounds selected from the group consisting of acetic acid and acetic acid derivatives (if it is a solid, after being dissolved in any solvent such as water, alcohol, etc.), spray and mix the water-absorbent resin with a sprayer or A method of impregnating and mixing a water-absorbent resin, and optionally mixing the mixed water-absorbent resin with the above-mentioned additives; (ii-3) the preparation of the water-absorbent resin remains selected from the group consisting of acetic acid and acetic acid derivatives A method of mixing one or more compounds of the group, and optionally mixing the obtained preparation with the above-mentioned additives; or (ii-4) combining the above-mentioned methods (ii-1) to (ii-3) and the like to produce. In the above (ii-1) to (ii-4), the amount of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, and the degree of washing of the water-retaining material can be adjusted to adjust the The content of one or more compounds in the group including acetic acid and acetic acid derivatives.

In the case where the water-retaining material of the present invention also contains one or more elements selected from the group consisting of phosphorus element, potassium element and nitrogen element, the production method can be achieved by, for example: (iii-1) in addition to being selected from the group consisting of acetic acid In addition to one or more compounds in the group of acetic acid derivatives, a compound or ion containing one or more elements selected from the group consisting of phosphorus, potassium, and nitrogen, a water-absorbent resin, and any of the above additives Method of mixing; (iii-2) In addition to one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, it will contain one or more compounds selected from the group consisting of phosphorus, potassium and nitrogen The compound of the element is dissolved in an arbitrary solvent solution or a solution containing the ion of the aforementioned element, sprays and mixes the water-absorbent resin with a sprayer, or immerses and mixes the water-absorbent resin in the aforementioned solution, and arbitrarily absorbs water after mixing A method of mixing a synthetic resin with the above-mentioned additives; (iii-3) In the preparation of a water-absorbent resin, in addition to one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, it is made to contain elements selected from phosphorus, A method in which compounds and ions of one or more elements in the group of potassium element and nitrogen element remain, and the obtained preparation is arbitrarily mixed with the above-mentioned additives; or (iii-4) a method of combining the above-mentioned (iii-1)~ (iii-3) method and so on. In the above (iii-1) to (iii-4), the amount of compounds containing phosphorus, potassium, and nitrogen and the degree of cleaning of the water-retaining material can be adjusted to adjust the selection of phosphorus and potassium And the content of one or more compounds in the group of nitrogen elements.

When the water-retaining material of the present invention also contains more than one agent that kills microorganisms or inhibits the proliferation of microorganisms, the production method can be performed by, for example, (iv-1) except for 1 selected from the group consisting of acetic acid and acetic acid derivatives. In addition to more than one compound, dissolve the above-mentioned agent in a solution of any solvent, spray and mix the water-absorbent resin with a sprayer, or immerse and mix the water-absorbent resin in the aforementioned solution, and wash and remove the solvent as necessary The method and so on to manufacture. In the case of manufacturing a water-retaining material that also contains additives, for example, in (iv-1) above, (iv-2) in addition to medicaments, a solution that also contains additives is used, or (iv-3) By mixing with the additives during the aforementioned mixing, or (iv-4) by mixing the water-retaining material after the solvent has been removed with the additives, or (iv-5) by combining the above (iv-2)~( iv-4) 2 or more types. In the case of producing a water-retaining material that also contains the aforementioned compound (Y), for example, a method of mixing the water-retaining material and the compound (Y), spraying and mixing the compound (Y) with the water-retaining material sprayer, or mixing the compound (Y) with the compound (Y) A method of immersing and mixing the water-retaining material in the water-absorbing resin, a method of leaving the compound (Y) in the preparation of the water-absorbent resin, or a combination of two or more of the above-mentioned methods.

The water-retaining material of the present invention contains one or more elements selected from the group consisting of phosphorus, potassium, and nitrogen, one or more agents that kill microorganisms or inhibit the proliferation of microorganisms, and all of the aforementioned compounds (Y) In this case, the manufacturing method can be manufactured by arbitrarily combining the above-mentioned manufacturing methods. One or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, compounds or ions containing one or more elements selected from the group consisting of phosphorus, potassium, and nitrogen, kill microorganisms or inhibit microorganisms The order of mixing the proliferating agent, compound (Y), and optional additives is not particularly limited.

In the above-mentioned manufacturing method, mixing can be carried out sequentially or simultaneously by using a general device (for example, a reactor equipped with a stirring blade, a mixer, etc.). In the above (ii-3) and (iii-3), the remaining one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives include compounds that can be used in the preparation of water-absorbent resins, such as acetic acid , Sodium acetate, potassium acetate, etc., as residual compounds and ions, include compounds that can be used in the preparation of water-absorbent resins, for example, potassium hydroxide, nitric acid, ammonium nitrate, ammonium sulfate, ammonia, potassium hydrogen sulfate, phosphoric acid, Potassium dihydrogen phosphate, dipotassium hydrogen phosphate, ammonium dihydrogen phosphate, potassium diammonium phosphate, ammonium ion, phosphate ion, hydrogen phosphate ion, dihydrogen phosphate ion, nitrate ion, etc. In addition, in the case of producing a water-retaining material that also contains the aforementioned compound (Y), when selecting a method for making the compound (Y) remain in the preparation of the water-absorbent resin, as the remaining compound (Y), one of the water-absorbent resin may be mentioned. Compounds that can be used in the preparation, such as water, acetonitrile, ethanol, and methanol.

The production method of the present invention may optionally include a step of pulverizing the water-absorbent resin and/or the water-retaining material and/or a step of sieving. For example, the water-retaining material obtained after the water-absorbent resin and/or solvent is removed can be delivered to the pulverization step and/or the sieving step, or the intermediate product obtained during the preparation of the water-absorbent resin containing acrylic structural units The polyvinyl alcohol is delivered to the crushing step and/or the sieving step.

In a preferred embodiment, the water-retaining material of the present invention is for agricultural use. In a further preferred embodiment, the water-retaining material of the present invention is used for raising seedlings. Therefore, in one aspect of the present invention, the water-retaining material can be used as a culture medium for raising seedlings. The medium system may contain optional components in addition to the water-retaining material.

＜Optional ingredients＞ As such optional components, for example, resins other than the water-absorbent resin contained in the water-retaining material, cultivating earth, other optional components described later, and combinations thereof can be cited. In addition, in the following description of the preferable content of the optional component when the medium contains the above optional component, the composition of the medium other than one or more compounds selected from acetic acid and acetic acid derivatives (the water-absorbing material contained in the water-retaining material The mass of the resin, the additives when contained in the water-retaining material, and the optional components when contained) is the mass in the dry state.

＜Resin other than water-absorbent resin＞ Examples of resins other than the water-absorbent resin include polyethylene, polypropylene, alkyd resin, phenol resin, polyethylene glycol, and polyurethane. These resins can be used alone or in combination of two or more kinds. When the culture medium contains the above-mentioned resin, the total content of the resin is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less relative to the total mass of the culture medium.

＜Cultivate soil＞ In the case where the culture medium contains the cultivated soil, since the roots grow in the gaps between the cultivated soil, the roots become entangled with each other appropriately, and it becomes easy to obtain the excellent drainage and air permeability of the culture medium. The cultivating earth is not particularly limited, and one kind of commercially available cultivating earth can be used alone or in combination of two or more kinds. In addition, it is also possible to use a conventional method (for example, a method of spraying a solution or dispersion of an optional component on the soil and then drying it) to attach an optional component described later to the soil for use.

From the viewpoint of easily obtaining more excellent drainage and air permeability, the plowing soil is preferably granular. The particle size of the granular soil is preferably 0.2 to 20 mm, more preferably 0.5 to 10 mm, particularly preferably 1 to 5 mm. In order to adjust the particle size of the granular cultivating soil to the aforementioned range, commercially available granular cultivating soil for rice can be sieved and used. Granulation methods such as compression granulation method, extrusion granulation method, rotation granulation method, fluidized bed granulation method, etc. can be used for the production of granular soil. The particle size of the granular soil can be measured by the following method. Thirty particles were randomly selected from the granular soil, the diameter of each particle was measured using a vernier caliper, and the average value was taken as the particle diameter of the granular soil. In addition, when the particle is not spherical, the average value of the longest side and the shortest side is regarded as the diameter of the particle.

In the case where the culture medium contains the cultivated soil, the content of the cultivated soil relative to the total mass of the culture medium is preferably 20 to 99.9999 mass%, more preferably 70 to 99.95 mass%, particularly preferably 80 to 99.9 mass%, and most preferably 90 to 99.8% by mass.

＜Other optional ingredients＞ Other optional ingredients include peat, peat, peat, peat moss, cocoa peat, rice, humus fermentation material, charcoal, diatomaceous earth burned granules, shellfish fossil powder, shell powder, crab shell, VA bacteria Root fungus, microbial materials and other animal and plant materials; vermiculite, perlite, bentonite, natural zeolite, synthetic zeolite, gypsum, fly ash, rock wool, kaolinite, bentonite, montmorillonite, sericite, chlorite, Minerals such as sea green stone and talc; fertilizers and combinations of these. These can be used for disinfection or sterilization as needed, and can also be used with pH adjusters or pesticides. When the culture medium contains other optional components, the total content may be within a range that does not impair the effects of the present invention. The total mass of the culture medium is usually 50% by mass or less, and preferably 30% by mass or less.

As examples of fertilizers, three fertilizers including nitrogen-based fertilizers, phosphorus-based fertilizers, and potassium-based fertilizers can be cited; essential for plants containing calcium, magnesium, sulfur, iron, copper, manganese, zinc, boron, molybdenum, chlorine, nickel, etc. The essential elements of fertilizer; compost of bark, cow dung, pig dung, chicken dung, moisture-containing garbage, pruning debris, etc. Examples of nitrogen-based fertilizers include ammonium sulfate, ammonium chloride, ammonium nitrate, sodium nitrate, calcium nitrate, ammonium humate fertilizer, urea, lime nitrogen, ammonium nitrate lime, sodium ammonium nitrate, and magnesium nitrate fertilizer; as phosphorus-based fertilizers, Examples include superphosphate, superphosphate, soluble phosphate fertilizer, humic acid phosphate fertilizer, burned phosphorus, burnt phosphorus, Linster, magnesium superphosphate, mixed phosphoric acid fertilizer, by-product phosphoric acid fertilizer, high-concentration phosphoric acid; Examples of potassium-based fertilizers include potassium sulfate, potassium chloride, potassium magnesium sulfate, potassium carbonate, potassium hydrogen carbonate, potassium silicate, and the like. These fertilizers can be used as solid, paste, liquid, solution, etc., and can also be used as coated fertilizers. Examples of pesticides include insecticides, fungicides, insecticide fungicides, herbicides, rodenticides, preservatives, plant growth regulators, and the like.

When the water-retaining material of the present invention is combined with a fertilizer to produce a culture medium, in a preferred embodiment, the fertilizer is used as a coated fertilizer. Coated fertilizer is made by coating fertilizer with resin. Examples of resins include polyolefins. In the case of using a coated fertilizer, the fertilizer can be successively supplied to the soil as the resin is decomposed. In addition, when granular coating fertilizers are used to make seedlings, the strength of the resulting seedlings tends to be higher. The particle size of the coated fertilizer is preferably 1 mm to 10 mm, more preferably 3 mm to 6 mm. In the case of using a coated fertilizer, the content of the coated fertilizer in the culture medium is preferably 10-99.99% by mass, more preferably 15-90% by mass, particularly preferably 20-80% by mass, and most preferably 30-60% by mass .

When the water-retaining material of the present invention is used in combination with optional components, the water-retaining material and optional components may be mixed and used, or sprinkled on a culture medium after germination. In the case of mixed use, the mixing method is not particularly limited. A general method can be used to mix the water-retaining material and optional components to prepare a culture medium for raising seedlings. In the case of sprinkling on a medium after germination, the period of sowing is not particularly limited, but it is preferably during the seedling raising period when the plant cannot withstand drying (about 1 month from sowing).

The amount of the water-retaining material of the present invention and any components used in combination varies depending on the combined soil and other components, but it is usually 0.0001% to 20% by mass relative to the total mass of the culture medium, preferably 0.05% by mass ~15% by mass, more preferably 0.1% by mass to 10% by mass.

When the medium is used for growing rice seedlings, rice seeds can be sown in the medium. The sowing of rice seeds is mostly carried out in a rice seedling box with a rice seedling culture medium introduced. Generally, the amount of rice seedlings is 100 to 500 g per box of rice seedling raising boxes (28 cm in length x 58 cm in width). The culture medium can be used for either of bed soil (soil introduced into the rice seedling box before sowing rice seeds) or covering soil (soil covered from above after sowing rice seeds), and can also be used for both. In the case of using both, the composition of the culture medium, the bed soil and the covering soil, may be the same or different. In addition, it can be used by sprinkling the culture medium on top of the cultivation soil after germination. [Example]

Hereinafter, the present invention will be further specifically explained using examples and the like, but the present invention is not limited in any way by these examples and the like.

＜Evaluation items and methods＞ (1) Survival rate (after 9 days, 14 days or 21 days from sowing) After 9 days from sowing (Examples 13-22, Comparative Examples 6-10), 14 days (Examples 1-12, Comparative Examples 1-5) or 21 days (Examples 23-33, Comparative Example 11) ~14), the number of roots of the seedlings (color scale less than 1) without wilting was visually measured, and the ratio to the number of roots of all the seedlings was regarded as the survival rate.

(2) Moisture rate The seedling pieces (including soil and water-retaining materials) 14 days after sowing were taken out from the rice seedling box, cut into 10cm×6cm, and the mass w1 was measured. After the cut seedling pieces were dried with hot air at 105°C for 24 hours, the mass w2 was measured again. According to the following formula, the moisture content is measured. Moisture rate (mass%)={(w1-w2)/w1}×100

(3) The content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives 100 mg of water-retaining material was added to 1 L of pure water, and stirring was performed at 23°C for 24 hours. After filtering the liquid phase with a 0.45 μm filter, the content was calculated by ion chromatography (Dionex ICS-1600 manufactured by Thermo Fisher Scientific). In the case of low content, increase the amount of water-retaining material to 1000 mg, and perform ion chromatography measurement after concentrating the liquid phase with an evaporator.

(4) Crop height (9 days, 14 days or 21 days after sowing) After 9 days from sowing (Examples 13-22, Comparative Examples 6-10), 14 days (Examples 1-12, Comparative Examples 1-5) or 21 days (Examples 23-33, Comparative Examples) 11-14). For 10 seedlings randomly sampled in a rice seedling box, measure the length from the top of the culture medium to the top of the seedling, and use the average value as the crop height. In addition, when the sampled seedlings wilt, they are stretched and their length is measured.

(5) The content of phosphorus, potassium and nitrogen (5)-1. The total content (Fa) of the content of the elements constituting the polymer skeleton of the water-absorbent resin and the content of the elements contained in the water-absorbent resin that does not constitute the aforementioned polymer skeleton After embedding the water-absorbing resin contained in the water-retaining material or the mixture produced in the Examples and Comparative Examples in an epoxy resin, the cross-section of the water-absorbing resin was produced by cutting. Introduced into a scanning electron microscope equipped with an energy dispersive X-ray analyzer, as a part of the resin, measure the 5μm point from the surface of the resin, the center and 3 points of their intermediate points, calculate the average value and use it as each element The content of Fa (mass%). (5)-2. The content of elements contained in the polymer backbone of the water-absorbent resin (Fb) 0.1g of water-absorbent resin contained in the water-retaining material or mixture produced in the Examples and Comparative Examples was washed 5 times with 100g of pure water to remove the phosphorus, potassium, and nitrogen contained in the resin that does not constitute the polymer skeleton . The cleaned resin was vacuum-dried at 40°C for 12 hours, embedded in an epoxy resin, and then cut to produce a cross section of the water-absorbent resin. Introduce into a scanning electron microscope equipped with an energy dispersive X-ray analyzer, and perform elemental analysis of the profile of the water-absorbent resin in the same way as (5)-1., and measure the content of each element constituting the polymer skeleton of the water-absorbent resin Fb (mass%). (5)-3. The content of elements contained in the water-holding material (Fc) Nitrogen is measured by burning the water-holding material with an organic element analyzer. Regarding phosphorus and potassium, nitric acid was added to the water-retaining material and subjected to microwave decomposition, and then the content was measured by ICP-AES. The content of phosphorus element, potassium element, and nitrogen element contained in the water holding material is referred to as Fc (mass %). The phosphorus element, potassium element, and nitrogen element content Fi contained in the water-absorbent resin that does not constitute the polymer skeleton are determined by the following equation. Fi=Fa-Fb The phosphorus element, potassium element, and nitrogen element Fo, which are not contained in the resin but contained in the water-retaining material, are obtained from the following equation. Fo=Fc-Fa

(6) Germination rate (2 days after sowing) In the rice seedling box, visually count the number of buds that germinated and appeared on the cover soil (N1). Using the number (N2) of the sown to promote germination rice, the bud percentage was calculated according to the following formula. Germination rate[%]=(N1/N2)×100

(7) The content of the medicine (7)-1. The amount of medicament that does not exist in the resin but exists in the water-retaining material (Eo) Put 1g of the water-retaining material or mixture produced in the examples or comparative examples (in the case of Examples 32 and 33, instead of the water-retaining material, the water-retaining material is heated at 60°C under vacuum for 12 hours to dry). Cylinder filter paper [manufactured by Toyo Filter Paper Co., Ltd., Advantech (registered trademark) #84, inner diameter of 25 mm, outer diameter of 28 mm, and length of 100 mm] was inserted, and each cylindrical filter paper was immersed in 0.1 L of acetone for 10 seconds. Next, the cylindrical filter paper containing the water-retaining material was taken out, the concentration Co of the drug in the acetone solution was measured by a liquid chromatography mass spectrometer (LC-MS), and Eo was obtained from the following equation. Eo(mass%)=[{Co(g/L)×0.1(L)}/1(g)]×100 When the concentration of the drug is low, use an evaporator to concentrate the acetone solution and perform LC-MS measurement. (7)-2. The amount of medicament present in the water-holding material (Ea) 1g of the water-retaining material or mixture produced in the examples or comparative examples (in the case of Examples 32 and 33, instead of the water-retaining material, the water-retaining material is heated at 60°C under vacuum for 12 hours to dry it). A cylindrical filter paper (manufactured by Toyo Filter Paper Co., Ltd., Advantech (registered trademark) #84, inner diameter of 25 mm, outer diameter of 28 mm, and length of 100 mm) was inserted, and 0.2 L of acetone was used for 24 hours of Soxhlet extraction. After further adding acetone to the extracted acetone solution to make the total volume 0.3 L, the concentration Ca of the drug in the acetone solution was measured by LC-MS, and Ea was obtained from the following formula. Ea(mass%)=[{Ca(g/L)×0.3(L)}/1(g)]×100 When the concentration of the drug is low, use an evaporator to concentrate the acetone solution and perform LC-MS measurement. (7)-3. The amount of medicine contained in the resin (Ei) Ei is obtained from the following equation. Ei=Ea-Eo

(8) The proportion of water that plants can absorb In the present invention, the "proportion of water that can be absorbed by plants" [W (unit: mass %)] means the mass of the water-holding material based on the state of water that is 50 times the weight of the water-holding material itself. Plants can absorb The proportion of water. This ratio W can be easily obtained by the centrifugal separation method. In the present invention, W is obtained by the following method. As the sample, 2.4 g of the water-retaining material that absorbs 50 mass times the mass of the water-retaining material produced in the examples or comparative examples was introduced into the syringe, and the syringe was placed at a distance from the small centrifuge manufactured by Kokusan Co., Ltd. "H-36" is fixed inside the centrifuge tube so that the center of it is 10.2cm. The centrifuge was rotated at 2200 rpm for 60 minutes, and the ratio W (unit: mass %) of water that the plants can absorb was calculated according to the following formula. However, when the water-retaining material cannot absorb 50 times the mass of water, 2.4 g of the water-retaining material saturated with water is introduced into the syringe. W=[{(Sample mass before centrifugation)-(Sample mass after centrifugation)}/(Sample mass before centrifugation)]×100

(9) Water absorption speed (vortex method) According to JIS K 7224, the water-retaining material was weighed so that the mass other than the mass of the compound (Y) was 0.5 g, and the water-retaining material and 50 g of pure water were used to measure the water absorption time. The shorter the water absorption time measured by this method, the faster the water absorption speed of the water-retaining material.

(10) Powder scattering rate A stainless steel tube with an inner diameter of 2.9 cm and a length of 44 cm was vertically erected, and a petri dish with an inner diameter of 4.1 cm was placed 15 cm below the tube. Put 2g of the water-retaining material of the sample from the top of the tube for 3 seconds, measure the mass of the sample contained in the petri dish without scattering, and calculate the powder scattering rate according to the following formula. The lower the powder scattering rate, the lower the health risk caused by the inhalation of the operator of the water-retaining material, and the less likely it is for dust explosions to occur. Powder scattering rate [mass%] =[(The quality of the input sample-the quality of the sample stored in the petri dish)/(The quality of the input sample)]×100

(11) SP value SP value is calculated using Fedors method [SP value basis･application and calculation method (issued by information agency, author: Hideki Yamamoto, 2005), RFFedors, Polym. Eng. Sci. 14,147(1974)]. In addition, the SP value of water is 23.4. The SP values of the compound (Y) used in the Examples and Comparative Examples obtained by the above method are shown in Table 1 below. [Table 1] Compound (Y) SP value (cal/cm ³ ) ^1/2 Acetonitrile 11.2 Methyl acetate 8.8 Methanol 13.8 Dimethyl sulfide (DMSO) 13.2 N-Methyl-2-pyrrolidone (NMP) 10.8 Ethanol 12.6 Isopropanol 11.6 Glycerol 20.0 water 23.4

(12) The content of compound (Y) relative to the mass of the water-holding material 1 g of the water-retaining material was put into cylindrical filter paper [manufactured by Toyo Filter Paper Co., Ltd., Advantech (registered trademark) #84, inner diameter of 25 mm, outer diameter of 28 mm, and length of 100 mm], and Soxhlet extraction was performed using 0.2 L of methanol for 24 hours. After the extraction, the solid remaining on the cylindrical filter paper was vacuum dried at 40°C for 16 hours, and then the mass W2 was measured, and the content of the compound (Y) relative to the mass of the water-holding material was obtained from the following formula. The content of compound (Y) relative to the mass of the water-holding material=[{1(g)-W2(g)}/1(g)]×100

(13) Volume average particle size A laser diffraction/scattering particle size distribution measuring device (“LA-950V2” manufactured by Horiba Manufacturing Co., Ltd.) was used for the measurement. The dispersion medium is not used in the measurement, and the volume average particle diameter is measured in a dry method. The so-called volume average particle size is the particle size at which the cumulative volume is 50%.

＜Synthesis of water-absorbent resin＞ [Synthetic raw materials] Glyoxylic acid monohydrate, 40% by mass aqueous glyoxal solution, 25% by mass aqueous glutaraldehyde solution, acetonitrile, methanol, vinyl acetate, sodium hydroxide, methyl acrylate, and azobisisobutyronitrile, acetic acid, acetic acid Cross-linked product of sodium, acrylic acid-sodium acrylate copolymer (product name: super absorbent polymer (acrylate series)); manufactured by Wako Pure Chemical Industries, Ltd. Crosslinked product of acrylamide-acrylic acid-potassium acrylate copolymer (composition ratio (mol) 67:11:22) (product name: Miracle-Gro (registered trademark) Water Storing Crystal); manufactured by Scotts Miracle Polyvinyl alcohol A; ELVANOL (registered trademark) 71-30 manufactured by Kuraray America

[Synthesis of water-absorbent resin a-0] Into a 500 mL four-necked separation flask equipped with a reflux cooling tube and a stirring blade, 12.55 g of glyoxylic acid monohydrate, 0.11 g of 40% by mass glyoxal aqueous solution, 12.55 g of ion exchange water, and 150 mL of acetonitrile were introduced And 40.0 g of polyvinyl alcohol a (sodium acetate content 1.0% by mass), and stirred at 23°C for 1 hour. After raising the temperature of the obtained mixture to 70°C, 16.87 g of a 25% by mass sulfuric acid aqueous solution was added dropwise over 10 minutes, and the mixture was kept at 70°C for 6 hours to react. Then, after cooling to 30°C, 150 mL of ion-exchanged water was added, and the resin was taken out by filtration. Next, the filtered resin was washed 5 times with 200 mL of methanol once (washing 1). The cleaned resin was introduced into a 500 mL four-necked separation flask equipped with a reflux cooling tube and a stirring blade, and 180 mL of methanol, 11.6 mL of ion exchange water and 16.8 mL of 8 mol/L potassium hydroxide aqueous solution were added, and the mixture was refluxed. Let it react for 2 hours. The resin was taken out by filtration, washed 6 times with 200 mL of methanol every time (wash 2), and vacuum-dried at 40°C for 6 hours to obtain the desired water-absorbent resin (hereinafter referred to as "water-absorbent resin a-0" "). The volume average particle diameter of the vinyl alcohol-based polymer a-0 measured using a laser diffraction/scattering particle size distribution measuring device was 142 μm.

[Synthesis of water-absorbent resin b-0] In a reactor equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, and a starting agent addition port, 602 g of vinyl acetate, 1.21 g of methyl acrylate, and 254 g of Methanol, nitrogen gas was bubbled, and inert gas was replaced in the reactor for 30 minutes. The temperature rise of the reactor was started using a water bath, and when the internal temperature of the reactor reached 60°C, 0.16 g of azobisisobutyronitrile (AIBN) was added as an initiator to start the polymerization. Appropriate sampling is performed to confirm the progress of the polymerization from the solid content concentration, and the consumption rate of the total mass of vinyl acetate and methyl acrylate consumed by the polymerization is obtained relative to the total mass of the introduced vinyl acetate and methyl acrylate . When the consumption rate reached 4%, the internal temperature of the reactor was cooled to 30°C to stop the polymerization. It was connected to a vacuum line, and the remaining vinyl acetate and methanol were distilled off under reduced pressure at 30°C. While visually confirming the inside of the reactor, when the viscosity increased, distillation was continued while adding appropriate methanol to obtain polyvinyl acetate containing 5.2 mol% of acrylic acid structural units. The content of the acrylic acid structural unit ^{is measured using 13} C-NMR. Next, in the same reactor as above, 1 g of the obtained polyvinyl acetate containing acrylic acid structural unit and 18.2 g of methanol were added, and the polyvinyl acetate containing acrylic structural unit was dissolved. The temperature rise of the reactor was started using a water bath, and the internal temperature of the reactor was heated up to 70°C while stirring. 0.78 g of a methanol solution of sodium hydroxide (caustic alkali, concentration 15% by mass) was added thereto, and saponification was performed at 70°C for 2 hours. The resulting solution was filtered to obtain polyvinyl alcohol (hereinafter referred to as "polyvinyl alcohol b") containing 5.2 mol% of acrylic acid structural units. The obtained polyvinyl alcohol b contained 1.2% by mass of sodium acetate. Into a three-necked separation flask equipped with a reflux cooling tube and a stirring blade, 58.9 g of acetonitrile, 6.28 g of ion exchange water, 0.171 g of 25% by mass glutaraldehyde aqueous solution, and 20 g of polyvinyl alcohol b were introduced and stirred at 23°C , And disperse polyvinyl alcohol b. 12.38 g of a 16.9% by mass sulfuric acid aqueous solution was added dropwise over 15 minutes, and the temperature was raised to 65°C to be reacted for 6 hours. After the reaction, the resin was taken out by filtration, and the filtered resin was washed 6 times with 160 g of methanol every time (washing 3). The cleaned resin was introduced into a three-necked separation flask equipped with a reflux cooling tube and stirring blades, 71 g of methanol, 13.3 g of ion exchange water, and 5.7 g of potassium hydroxide were added, and reacted at 65°C for 2 hours . After the reaction, after the resin was taken out by filtration, the filtered resin was washed 6 times with 160 g of methanol (wash 4), and vacuum-dried at 40°C for 12 hours to obtain the desired water-absorbent resin (hereinafter referred to as "Water-absorbing resin b-0"). The volume average particle diameter of the vinyl alcohol-based polymer b-0 measured using a laser diffraction/scattering particle size distribution measuring device was 135 μm.

[Example 1] Except that the number of times of washing 1 was changed from 5 times to once, and the number of times of washing 2 was changed from 6 times to once, the water-absorbent resin was performed in the same manner as the water-absorbent resin a-0 (below It is called "water-absorbent resin a-1") synthesis. The water-absorbent resin a-1 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin a-1 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material a-1"). 1800g of granular soil (containing NP ₂ O ₅ -K ₂ O=0.5-1.5-0.5g/kg as fertilizer, with an average particle size of 2.7mm), covered with an internal size of 58cm×28cm and 56 holes with a diameter of 2mm on the bottom In the rice seedling box, use a spray can to irrigate 1000 mL of water for 5 seconds. After 200 g of germinated rice (variety: Koshihikari) was evenly sown, 1200 g of granular soil was evenly spread on it to produce a rice seedling box. Further, the above operation was performed twice to prepare three rice seedling boxes into which the same rice seedling cultivation soil and water were introduced. After germinating in a germination bank at 30°C and 100% humidity for 2 days, take it out of the germination bank and grow seedlings in a 25°C and 50% humidity box equipped with LEDs. After 9 days from the sowing, 20 g of the water-retaining material a-1 was sown on the covering soil, and 1 L was irrigated. After the seedlings were raised continuously, the survival rate and water content were measured 14 days after sowing. The results are shown in Table 2.

[Example 2] In addition to [Synthesis of water-absorbent resin a-0], in addition to the sulfuric acid aqueous solution, 1.0 g of acetic acid as a catalyst for acetalization was added, and the number of wash 1 was changed from 5 to 1, and the wash The frequency of 2 was changed from 6 times to 1 time, and the 8mol/L potassium hydroxide aqueous solution 16.8mL was changed to 18.8mL, and the water-absorbent resin (hereinafter referred to as "water-absorbent resin a- 2”). The water-absorbent resin a-2 contains 1.1% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin a-2 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material a-2"). Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 3] In addition to [Synthesis of water-absorbent resin a-0], in addition to the sulfuric acid aqueous solution, 10.0 g of acetic acid as a catalyst for acetalization was added, and the number of washing 1 was changed from 5 to 1, and the washing was changed. The number of times of 2 was changed from 6 times to once, and the 8mol/L potassium hydroxide aqueous solution 16.8mL was changed to 33.6mL, and the water-absorbent resin (hereinafter referred to as "water-absorbent resin a- 3”). The water-absorbent resin a-3 contains 6.2% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin a-3 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material a-3"). Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 4] 4 g of acetic acid was mixed with 21 g of water-absorbent resin a-0 as a water-retaining material a-4. Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 5] A solution in which 24 g of sodium acetate was dissolved in 150 g of pure water was mixed with 21 g of the water-absorbent resin a-0, and vacuum-dried at 40°C for 6 hours as a water-retaining material a-5. Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 6] In addition to the [Synthesis of water-absorbent resin b-0], the number of wash 3 was changed from 6 to 4, and the number of wash 4 was changed from 6 to 3, and it was combined with water-absorbent resin b-0 Similarly, synthesis of a water-absorbent resin (hereinafter referred to as "water-absorbent resin b-1") was performed. The water-absorbent resin b-1 contains 0.01% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-1 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-1"). Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 7] Except in the [Synthesis of water-absorbent resin b-0], the number of wash 3 was changed from 6 to 1 and the number of wash 4 was changed from 6 to 1. Similarly, synthesis of a water-absorbent resin (hereinafter referred to as "water-absorbent resin b-2") was performed. The water-absorbent resin b-2 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-2 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-2"). Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 8] In addition to [Synthesis of water-absorbent resin b-0], in addition to the sulfuric acid aqueous solution, 0.5 g of acetic acid as a catalyst for acetalization was added. The number of wash 3 was changed from 6 to 1 and the wash Except for changing the number of 4 times from 6 times to once, the synthesis of a water-absorbent resin (hereinafter referred to as "water-absorbent resin b-3") was carried out in the same manner as in the water-absorbent resin b-0. The water-absorbent resin b-3 contains 0.9% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-3 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-3"). Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 9] 4 g of acetic acid was mixed with 21 g of water-absorbent resin b-0 as a water-retaining material b-4. Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 10] 4 g of acetic acid was mixed with 21 g of the cross-linked product of the acrylic acid-sodium acrylate copolymer as the water retaining material c-1. Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 11] 4 g of acetic acid was mixed with 21 g of the cross-linked product of acrylamide-acrylic acid-potassium acrylate copolymer as a water-retaining material d-1. Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 12] After dissolving 10 g of polyvinyl alcohol b in 500 g of water, it was dropped into 10 kg of methanol, and the resin was precipitated. Except that the precipitated resin was used, the number of washing 3 was changed from 6 to 0, and the number of washing 4 was changed from 6 to 0, the water-absorbent resin was performed in the same manner as the water-absorbent resin b-0 ( Hereinafter referred to as "water-absorbent resin b-5") synthesis. The water-absorbent resin b-5 contains 0.004% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-5 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-5"). Except for using this water-retaining material, it carried out similarly to Example 1, preparation and measurement of a rice seedling raising box. The results are shown in Table 2.

[Example 13] Except that in [Synthesis of water-absorbent resin b-0], the number of wash 3 was changed from 6 to 5 times, and the water-absorbent resin (hereinafter referred to as "absorbent resin") was performed in the same manner as the water-absorbent resin b-0. b-6”). The water-absorbent resin b-6 contains 0.08% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-6 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-6"). 48 g of the water-holding material b-6 and 600 g of granular soil A (without fertilizer, average particle size 3.0 mm) were uniformly mixed to prepare a rice seedling cultivation soil. 60% by mass of the rice seedling cultivation soil was spread over a rice seedling box with an inner size of 58 cm×28 cm and 56 holes with a diameter of 2 mm on the bottom surface, and 1000 mL of water was irrigated with a spray can for 5 seconds. After evenly sown 200 g of the germinated rice (variety: Koshihikari), the remaining rice seedling cultivation soil (40% by mass of the prepared rice seedling cultivation soil) was evenly spread on it, and the rice seedling cultivation soil and water introduced into the rice seedling cultivation soil and water were made. box. Further, the above operation was performed twice to prepare three rice seedling boxes into which the same rice seedling cultivation soil and water were introduced. After germination was carried out in a germination chamber at 30°C and a humidity of 100% for 2 days, the germination rate was measured. Then, seedlings were raised in a box equipped with LEDs at 25°C and humidity of 60%, and the height and survival rate of the crops were measured 9 days after sowing. The measurement system was carried out in 3 nursery boxes and the average value was used. The results are shown in Table 3.

[Example 14] Except that in [Synthesis of water-absorbent resin b-0], the number of times of washing 3 was changed from 6 to once, the water-absorbent resin (hereinafter referred to as "water-absorbent resin" b-7”). The water-absorbent resin b-7 contains 0.2% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-7 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-7"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 15] Except that in [Synthesis of water-absorbent resin b-0], the number of wash 3 was changed from 6 times to 2 times, the same as water-absorbent resin b-0, water-absorbent resin (hereinafter referred to as "absorbent resin After the synthesis of b-8"), potassium sulfate is mixed. The water-absorbent resin b-8 contains 0.1% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-8 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-8"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 16] Except that in [Synthesis of water-absorbent resin b-0], the number of wash 3 was changed from 6 to 1 time, and the water-absorbent resin (hereinafter referred to as "absorbent resin b-0" After the synthesis of resin b-9"), diammonium hydrogen phosphate was mixed. The water-absorbent resin b-9 contains 0.2% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-9 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-9"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 17] In addition to [Synthesis of water-absorbent resin b-0], in addition to sulfuric acid, 5.0 g of diammonium hydrogen phosphate was added to react polyvinyl alcohol b with glutaraldehyde, and the number of washing 3 was set to 3 Other than that, in the same manner as the water-absorbent resin b-0, synthesis of a water-absorbent resin (hereinafter referred to as "a water-absorbent resin b-10") was performed. After synthesis, mix diammonium hydrogen phosphate and potassium sulfate. The water-absorbent resin b-10 contains 0.08% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-10 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-10"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 18] In addition to [Synthesis of water-absorbent resin b-0], in addition to sulfuric acid, 5.0 g of diammonium hydrogen phosphate was added to react polyvinyl alcohol b with glutaraldehyde, and the number of washing 3 was set to 1 Other than that, the synthesis of a water-absorbent resin (hereinafter referred to as "a water-absorbent resin b-11") was carried out in the same manner as the water-absorbent resin b-0. After synthesis, mix diammonium hydrogen phosphate and potassium sulfate. The water-absorbent resin b-11 contains 0.2% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-11 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-11"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 19] Except in [Synthesis of water-absorbent resin b-0], 12.38 g of 16.9% by mass sulfuric acid aqueous solution was changed to 16.32 g of 10% by mass hydrochloric acid, and 5.0 g of diammonium hydrogen phosphate was added to perform the synthesis of polyvinyl alcohol b and glutaraldehyde. After the reaction, except that the number of times of washing 3 was set to 3, the synthesis of a water-absorbent resin (hereinafter referred to as "a water-absorbent resin b-12") was carried out in the same manner as in the water-absorbent resin b-0. After synthesis, mix diammonium hydrogen phosphate and potassium chloride. The water-absorbent resin b-12 contains 0.07% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-12 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-12"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 20] Except in [Synthesis of water-absorbent resin b-0], 12.38 g of 16.9% by mass sulfuric acid aqueous solution was changed to 27.06 g of 10% by mass nitric acid, and 5.0 g of diammonium hydrogen phosphate was added to perform the synthesis of polyvinyl alcohol b and glutaraldehyde. After the reaction, except that the number of times of washing 3 was set to 3, the synthesis of a water-absorbent resin (hereinafter referred to as "water-absorbent resin b-13") was carried out in the same manner as in the water-absorbent resin b-0. After synthesis, mix diammonium hydrogen phosphate and potassium nitrate. The water-absorbent resin b-13 contains 0.07% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-13 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-13"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 21] In addition to the [synthesis of water-absorbent resin b-0], in addition to sulfuric acid, 2.3 g of urea was added to react polyvinyl alcohol b with glutaraldehyde, and the number of washing 3 times was set to 1 The synthetic resin b-0 was similarly synthesized with a water-absorbent resin (hereinafter referred to as "water-absorbent resin b-14"). After synthesis, mix diammonium hydrogen phosphate and potassium sulfate. The water-absorbent resin b-14 contains 0.2% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-14 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-14"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 22] Except that in [Synthesis of water-absorbent resin a-0], the number of wash 1 was changed from 5 to 2 times, and the water-absorbent resin (hereinafter referred to as "absorbent resin") was performed in the same manner as the water-absorbent resin a-0. After the synthesis of a-6”), potassium sulfate is mixed. The water-absorbent resin a-6 contains 0.1% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin a-6 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material a-6"). Except for using this water-holding material, it carried out similarly to Example 13, preparation and measurement of a rice seedling raising box. The results are shown in Table 3.

[Example 23] In [Synthesis of Water Absorbent Resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the number of washing 4 was changed from 6 to 1 The following mixture (the content of the water-absorbent resin is 20 g) is mixed with a solution of 0.0022 g of ethyl p-hydroxybenzoate dissolved in 60 g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as " Water-absorbent resin b-15"). The water-absorbent resin b-15 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-15 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-15"). Mix 8g of water-retaining material b-15 with 100g of granular soil (containing NP ₂ O ₅ -K ₂ O=0.5-1.5-0.5g/kg as fertilizer, average particle size 2.7mm) to make a rice seedling culture medium . 3.6 times the amount (360 g) of the rice seedling culture medium was spread over a rice seedling box with an inner size of 58 cm×28 cm and 56 holes with a diameter of 2 mm on the bottom surface, and 1000 mL of water was irrigated with a spray can for 5 seconds. After evenly sown 200 g of germinated rice (variety: Koshihikari), spread it evenly on top of 2.4 times the amount (240g) of the prepared rice seedling culture medium to produce a rice seedling box containing rice seedling culture medium, germinated rice and water . The above operation is further performed twice to make 3 identical rice seedling raising boxes. After germination was carried out in a germination chamber at 30°C and a humidity of 100% for 2 days, the germination rate and mold production were evaluated. Then, seedlings were raised in a box equipped with LEDs at 25°C and humidity of 70%, and the production of mold, etc., crop height, and survival rate were evaluated 21 days after sowing. The evaluation system was carried out with 3 rice seedling boxes, and their average value was used. The results are shown in Table 4.

[Example 24] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with a solution of 0.011g of ethyl p-hydroxybenzoate dissolved in 60g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as "absorbent resin b- 16"). The water-absorbent resin b-16 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-16 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-16"). Except that the water holding material b-16 was used instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 25] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with a solution of 0.022g of ethyl p-hydroxybenzoate dissolved in 60g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as "absorbent resin b- 17"). The water-absorbent resin b-17 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-17 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-17"). Except that the water holding material b-17 was used instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 26] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with a solution of 0.11g of ethyl p-hydroxybenzoate dissolved in 60g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as "absorbent resin b- 18"). The water-absorbent resin b-18 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-18 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-18"). Except having used the water holding material b-18 instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 27] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with a solution of 1.9g of ethyl p-hydroxybenzoate dissolved in 60g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as "absorbent resin b- 19"). The water-absorbent resin b-19 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-19 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-19"). Except that the water holding material b-19 was used instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 28] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with a solution of 0.022g of potassium sorbate dissolved in 60g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as "absorbent resin b-20") . The water-absorbent resin b-20 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-20 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-20"). Except that the water holding material b-20 was used instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 29] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with 0.10g of a 25% by mass aqueous solution of glutaraldehyde and 60g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as "absorbent resin b- twenty one"). The water-absorbent resin b-21 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-21 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-21"). Except that the water holding material b-21 was used instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 30] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with a solution of 0.022g of sodium dichlorotrimerisocyanate dissolved in 60g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as "absorbent resin b- twenty two"). The water-absorbent resin b-22 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-22 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-22"). Except that the water holding material b-22 was used instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 31] In [Synthesis of water-absorbent resin a-0], the number of washing 1 was changed from 5 to 1, and the number of washing 2 was changed from 6 to 1, weighing and using the mixture after washing 2. . This mixture (the content of the water-absorbent resin is 20 g) is mixed with a solution of 0.022 g of ethyl p-hydroxybenzoate dissolved in 60 g of methanol, and vacuum-dried at 40°C for 12 hours to obtain a water-absorbent resin (hereinafter referred to as " Water-absorbent resin a-7"). The water-absorbent resin a-7 contains 0.3% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin a-7 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material a-7"). Except having used the water holding material a-7 instead of the water holding material b-15, it carried out similarly to Example 23, the production and evaluation of a rice seedling raising box were performed. The results are shown in Table 4.

[Example 32] In [Synthesis of water-absorbent resin b-0], the number of washing 3 was changed from 6 to 1, the number of washing 4 was changed from 6 to 1, and the mixture after washing 4 (absorbent The content of the resin is 20g) is mixed with a solution of 0.022g ethyl p-hydroxybenzoate dissolved in 60g methanol, and dried under reduced pressure using an evaporator at 40°C until the methanol content becomes 20% by mass to obtain a water-absorbent resin (Hereinafter referred to as "water-absorbent resin b-23"). The water-absorbent resin b-23 contains 0.2% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-23 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-23"). The content of the water-absorbing resin in the water-retaining material b-23 was 79.9% by mass. Except having used the water holding material b-23 instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Example 33] In [Synthesis of Water Absorbent Resin b-0], the number of times of washing 3 was changed from 6 times to once, and the number of times of washing 4 was changed from 6 times to once to obtain a water absorbent resin. 22 g of this water-absorbent resin was prepared, and a solution in which 0.028 g of ethyl p-hydroxybenzoate was dissolved in 5 g of water was sprayed to the sprayer to obtain a water-absorbent resin (hereinafter referred to as "water-absorbent resin b-24"). The water-absorbent resin b-24 contains 0.2% by mass of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. That is, the water-absorbing resin b-24 corresponds to a water-retaining material (hereinafter referred to as "water-retaining material b-24"). The content of the water-absorbent resin in the water-retaining material b-24 was 82.4% by mass, and the content of water was 17.5% by mass. Except that the water holding material b-24 was used instead of the water holding material b-15, the production and evaluation of a rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Comparative Example 1] Except that the water-absorbing resin a-0 was used instead of the water-holding material a-1, the production and measurement of the rice seedling box were carried out in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 2] Except that the water-absorbing resin b-0 was used instead of the water-retaining material a-1, the production and measurement of the rice seedling box were performed in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 3] A rice seedling raising box was produced in the same manner as in Example 1. The seedlings were raised from sowing to 9 days after the sowing, and no water-retaining material was sowed. After dissolving 3.2 g of acetic acid in 1 L of pure water, the seedlings were given to the seedlings. Then, the seedlings were raised from the sowing to 14 days later, and then the measurement was performed. The results are shown in Table 2.

[Comparative Example 4] A rice seedling raising box was produced in the same manner as in Example 1. The seedlings were raised from sowing to 9 days after the sowing, and the water-holding material was not sowed, and only 1 L of pure water was supplied to the seedlings. Then, the measurement was performed 14 days after the seedling was raised from the sowing. The results are shown in Table 2.

[Comparative Example 5] A rice seedling raising box was produced in the same manner as in Example 1. The seedlings were raised from sowing to 9 days after the sowing, and the water-holding material was not sowed, and 1.1 g of acetic acid was dissolved in 1 L of pure water to give seedlings. Then, after 10 days and 12 days from sowing, 1.1 g of acetic acid was dissolved in 50 mL of pure water, and the seedlings were additionally administered. The measurement was carried out 14 days after seedlings were raised from sowing. The results are shown in Table 2.

[Comparative Example 6] Except for using the water-absorbent resin b-0, the production and measurement of a rice seedling raising box were performed in the same manner as in Example 13. The results are shown in Table 3.

[Comparative Example 7] 1.2 g of potassium sulfate was mixed with 48 g of water-absorbent resin b-0. Except for using this mixture (hereinafter referred to as "mixture b-1"), production and measurement of a rice seedling raising box were performed in the same manner as in Example 13. The results are shown in Table 3.

[Comparative Example 8] 3.1 g of diammonium hydrogen phosphate and 1.2 g of potassium sulfate were mixed with 48 g of water-absorbent resin b-0. Except for using this mixture (hereinafter referred to as "mixture b-2"), the production and measurement of a rice seedling raising box were performed in the same manner as in Example 13. The results are shown in Table 3.

[Comparative Example 9] 1.2 g of potassium sulfate was mixed with 48 g of water-absorbent resin a-0. Except for using this mixture (hereinafter, referred to as "mixture a-1"), the production and measurement of a rice seedling raising box were performed in the same manner as in Example 13. The results are shown in Table 3.

[Comparative Example 10] Except that no water-holding material was used, only 3000g of granular soil B (containing 0.33-0.42-0.5g/kg of phosphorus-potassium-nitrogen as fertilizer, with an average particle size of 3.0mm) was used in the same manner as in Example 13, and rice was used. Production and determination of nursery boxes. The results are shown in Table 3.

[Comparative Example 11] Except that the water-absorbing resin b-0 was used instead of the water-retaining material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Comparative Example 12] A mixture (hereinafter referred to as "mixture b-3") was obtained by mixing 20 g of the water-absorbent resin b-0 and 0.04 g of ethyl p-hydroxybenzoate. Except having used the mixture b-3 instead of the water holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Comparative Example 13] In [Synthesis of water-absorbent resin b-0], the mixture after washing 4 (the content of water-absorbent resin is 20 g) is mixed with a solution in which 5 g of ethyl p-hydroxybenzoate is dissolved in 60 g of methanol, and Vacuum drying was performed at 40°C for 12 hours to obtain a mixture (hereinafter referred to as "mixture b-4"). Except for using the mixture b-4 instead of the water-holding material b-15, the production and evaluation of the rice seedling box were performed in the same manner as in Example 23. The results are shown in Table 4.

[Comparative Example 14] Except that the water-absorbing resin a-0 was used instead of the water-retaining material b-15, the production and measurement of the rice seedling box were carried out in the same manner as in Example 23. The results are shown in Table 4.

[Table 2] Water retention material The content of one or more compounds selected from acetic acid or acetic acid derivatives in the water-retaining material [mass%] Survival rate (14 days after sowing) [%] Moisture rate [mass%] Crop height (14 days after sowing) [cm] Example 1 a-1 0.3 36 12.4 10.3 Example 2 a-2 1.1 41 12.1 11.6 Example 3 a-3 6.2 55 11.8 12.1 Example 4 a-4 15.7 71 13.1 12.5 Example 5 a-5 52.8 62 13.0 12.3 Example 6 b-1 0.01 39 13.4 10.2 Example 7 b-2 0.3 40 13.1 10.4 Example 8 b-3 0.9 56 13.8 11.4 Example 9 b-4 15.6 74 12.9 12.6 Example 10 c-1 15.8 61 10.1 11.1 Example 11 d-1 15.7 60 9.7 11.8 Example 12 b-5 0.004 37 13.4 9.9 Comparative example 1 Water-absorbent resin a-0 0 32 12.3 9.5 Comparative example 2 Water-absorbing resin b-0 0 36 13.7 9.8 Comparative example 3 no - 7 3.4 9.1 Comparative example 4 no - 0 3.2 7.5 Comparative example 5 no - 15 3.4 10.1

[table 3] Water retention material The content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives in the water-retaining material [mass%] The content of elements that do not constitute the polymer backbone of the resin but exist in the resin Fi [mass%] The content of the element that does not exist in the resin but exists in the water-retaining material Fo [mass%] The total amount of the elements in the water-retaining material Fi+Fo [mass%] Survival rate (9 days after sowing) [%] Germination rate (2 days after sowing) [%] Crop height (9 days after sowing) [cm] phosphorus Potassium nitrogen phosphorus Potassium nitrogen Example 13 b-6 0.08 0 0.11 0 0 0 0 0.11 88 85.5 7.1 Example 14 b-7 0.2 0 1.08 0 0 0 0 1.08 90 92.7 7.5 Example 15 b-8 0.1 0 0.75 0 0 0.33 0 1.08 88 96.2 7.8 Example 16 b-9 0.2 0 1.08 0 0.67 0 1.25 3.00 87 87.3 9.2 Example 17 b-10 0.08 0.33 0.54 0.63 0.33 0.54 0.63 3.00 85 90.4 9.4 Example 18 b-11 0.2 0.67 1.08 1.25 0.33 0.54 0.63 4.50 86 87.9 9.2 Example 19 b-12 0.07 0.33 0.54 0.63 0.33 0.54 0.63 3.00 85 88.9 9.3 Example 20 b-13 0.07 0.33 0.54 0.79 0.33 0.54 0.82 3.35 84 96.2 9.5 Example 21 b-14 0.2 0 1.08 1.25 0.33 0.54 0.63 3.83 86 86.3 8.9 Example 22 a-6 0.1 0 0.66 0 0 0.42 0 1.08 83 95.5 7.4 Comparative example 6 Water-absorbing resin b-0 0 0 0 0 0 0 0 0 81 84.1 5.2 Comparative example 7 Mixture b-1 0 0 0 0 0 1.08 0 1.08 80 84.8 5.8 Comparative example 8 Mixture b-2 0 0 0 0 0.67 1.08 1.25 3.00 79 81.3 6.7 Comparative example 9 Mixture a-1 0 0 0 0 0 1.08 0 1.08 79 83.6 5.6 Comparative example 10 - 0 - - - - - - - 65 83.2 7.0

[Table 4] Water retention material The content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives in the water-retaining material [mass%] Pharmacy Characteristics of water-retaining materials Evaluation after nursery species The amount contained in the resin Ei [mass%] The amount Eo that does not exist in the resin but exists in the water-retaining material [mass%] The proportion of water that can be absorbed by plants [mass%] Water absorption time [sec] Powder scattering rate [mass%] Germination rate (2 days after sowing) [%] Production of molds, etc. Crop height (21 days after sowing) [cm] Survival rate (21 days after sowing) [%] 2 days after sowing 21 days after sowing Example 23 b-15 0.3 Ethyl p-hydroxybenzoate 0.011 0 53.1 - - 62.0 no less 9.4 93 Example 24 b-16 0.3 0.047 0.004 53.7 - - 61.2 no no 9.3 93 Example 25 b-17 0.3 0.097 0.011 53.1 31 7.7 57.8 no no 8.8 92 Example 26 b-18 0.3 0.49 0.042 57.0 - - 57.9 no no 8.6 90 Example 27 b-19 0.3 8.3 0.12 62.2 - - 53.3 no no 8.5 89 Example 28 b-20 0.3 Potassium Sorbate 0.095 0.007 59.8 - - 59.8 no no 8.9 92 Example 29 b-21 0.3 Glutaraldehyde 0.096 0.001 57.7 - - 57.8 no no 8.9 93 Example 30 b-22 0.3 Sodium dichlorotrimeric isocyanate 0.097 0.003 59.4 - - 57.4 no no 8.6 91 Example 31 a-7 0.3 Ethyl p-hydroxybenzoate 0.094 0.002 8.2 - - 47.1 no no 8.2 91 Example 32 b-23 0.2 0.093 0.009 63.7 20 5.1 54.1 no no 8.9 91 Example 33 b-24 0.2 0.095 0.012 64.9 12 4.7 55.5 no no 9.0 92 Comparative example 11 Water-absorbing resin b-0 0 no 0 0 52.1 31 7.7 62.7 many many 9.2 86 Comparative example 12 Mixture b-3 0 Ethyl p-hydroxybenzoate 0 0.20 53.2 - - 53.5 no many 8.1 85 Comparative example 13 Mixture b-4 0 19.2 0.71 63.7 - - 34.2 no no 6.8 83 Comparative example 14 Water-absorbent resin a-0 0 no 0 0 7.5 - - 48.2 many many 8.2 83

As in Examples 1-12, the water-retaining material containing a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives has a high survival rate of plants even under dry conditions. In addition, it is known that if acetic acid is directly administered to plants as in Comparative Examples 3 and 5, the growth of plants tends to be poor compared with Examples 1-12.

Furthermore, if a compound containing a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, and a polymer backbone that does not form the aforementioned resin in the resin is used, selected from the group consisting of phosphorus elements, potassium elements, and In addition to the survival rate under dry conditions, the water-retaining materials of Examples 13-22 with one or more elements of the nitrogen element group, the germination rate (the growth index in the early stage of plant growth) and the crop height (the later stage of plant growth) The value of the growth indicator) is also excellent. On the other hand, the water-retaining material does not contain one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives and the resin does not contain the aforementioned elements in Comparative Examples 6-9, and does not contain the water-retaining material but contains fertilizer in the culture medium In Comparative Example 10 of the composition, the survival rate, the germination rate, and the crop height are all low values.

Furthermore, in the case of using a water-absorbent resin, one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, and a water-retaining material that further contains a prescribed amount of a drug inside (Examples 23 to 33), except for In addition to the good survival rate under dry conditions, the production of mold and the like is suppressed not only in a short period of time but also in a long period of use, and the growth of plants is also good. In addition, the water-retaining material of the present invention is also excellent in stability during storage. On the other hand, from the results of Comparative Examples 11-14 in which the water-retaining material does not contain one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives, it is known that the survival rate under dry conditions is not good. The following situation. In the case of using a water-absorbent resin that does not contain a drug (Comparative Examples 11 and 14), the production of molds, etc., was not suppressed even in a short period of time after seedlings were raised. In addition, in the case where the water-retaining material contains a chemical but the water-absorbent resin does not contain the chemical mixture b-3 (Comparative Example 12), the generation of molds and the like cannot be suppressed for a long period of time. It is believed that it is due to the medicament that exists in the water-holding material but does not exist in the water-absorbent resin, which flows out of the rice seedling box through irrigation in the seedling raising. Furthermore, in the case of using the mixture b-4 containing an excessive amount of the drug in the resin (Comparative Example 13), the growth of the plant was hindered. In the case of using a water-retaining material containing compound (Y) in addition to the medicine (Examples 32 and 33), in addition to inhibiting the production of molds and the like and the good growth of plants, it also achieved an increase in water absorption speed and a reduction in dust generation. [Possibility of Industrial Use]

Since the water-retaining material of the present invention can impart sufficient drying tolerance to plants and can promote the growth of plants, it can be suitably used for agricultural purposes, especially for seedling raising.

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Claims (20)

A water-retaining material comprising a water-absorbent resin and one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives. The water-retaining material of claim 1, wherein the content of one or more compounds selected from the group consisting of acetic acid and acetic acid derivatives is 0.001% by mass to 70% by mass relative to the mass of the water-retaining material. The water retaining material of claim 1 or 2, wherein the acetic acid derivative is one or more compounds selected from the group consisting of sodium acetate, magnesium acetate, potassium acetate, ammonium acetate, and calcium acetate. The water-retaining material of any one of claims 1 to 3, wherein the water-absorbent resin contains selected from the group consisting of vinyl alcohol polymers, acrylic polymers, acrylamide polymers, methacrylic polymers, and starch-based polymers. Polymers of the group of polymers. The water retaining material of claim 4, wherein the vinyl alcohol-based polymer contains a copolymer containing a monomer structural unit having a vinyl alcohol structural unit and an ionic group or a derivative thereof. The water retaining material of claim 4 or 5, wherein the vinyl alcohol polymer contains potassium ion or ammonium ion as the relative cation of the ionic group. The water retaining material according to any one of claims 4 to 6, wherein the vinyl alcohol-based polymer has a cross-linked structure. For example, the water-retaining material in any one of claims 1 to 7 is for agricultural use. For example, the water-holding material in any one of Claims 1 to 8, which is used for nursery. The water-retaining material of any one of claims 1 to 9, wherein the water-absorbent resin is inside the resin and contains an element that does not constitute the polymer skeleton of the resin, and the element is selected from the group consisting of phosphorus, potassium, and nitrogen One or more elements in a group of elements. Such as the water-retaining material of claim 10, wherein the content of one or more elements selected from the group consisting of phosphorus, potassium and nitrogen present in the resin is 0.001% by mass or more relative to the mass of the resin 50% by mass or less. The water-retaining material of claim 10 or 11, wherein the water-retaining material further contains at least one element selected from the group consisting of phosphorus, potassium, and nitrogen that is not present in the resin but is present in the water-retaining material. The water-retaining material of any one of claims 10 to 12, wherein the content of one or more elements selected from the group consisting of phosphorus element, potassium element, and nitrogen element that is not present in the resin but is present in the water-retaining material , Relative to the mass of the resin, it is 0.001% by mass or more and 50% by mass or less. The water-retaining material of any one of claims 1 to 13, wherein the water-absorbent resin contains one or more kinds of killing microorganisms or inhibiting microorganisms in an amount of 0.00001 mass% or more and 10 mass% or less relative to the mass of the resin Medicament for the proliferation of microorganisms. The water-retaining material of claim 14, wherein the water-retaining material further contains one or more kinds of the agent that is not present in the water-absorbing resin but is present in the water-retaining material. The water-retaining material of claim 15, wherein the content of one or more medicaments that are not present in the water-absorbing resin but are present in the water-retaining material is 0.00001 mass% or more and 10 mass% or less relative to the mass of the resin. The water-retaining material of any one of claims 1 to 16, wherein in the water-retaining material in the water-absorbing state of water 50 times the mass of the water-retaining material, the proportion of water that can be absorbed by the plant is based on the water-absorbing material The quality of the water-retaining material in the state is 7.6% by mass or more based on the standard. Such as the water-retaining material of any one of claims 1 to 17, wherein the water-retaining material further contains a compound having an SP value of 6.0 (cal/cm ³ ) ^1/2 or more and 30.0 (cal/cm ³ ) ^1/2 or less (Y ). The water-retaining material of claim 18, wherein the compound (Y) is selected from the group consisting of water, glycerol, methanol, dimethyl sulfoxide, ethanol, acetonitrile, isopropanol, N-methyl-2-pyrrolidone, One or more compounds in the group of methyl acetate, tetrahydrofuran, diethyl ether, N,N-dimethylformamide and ethylene glycol. The water-retaining material of claim 18 or 19, wherein the content of the compound (Y) relative to the mass of the water-retaining material is 0.001% by mass or more and 98% by mass or less.