JP2005206743A - Method for producing granular hydrous gel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing granular hydrous gel capable of producing a granular shaped article without detriment to characteristics as hydrous gel. <P>SOLUTION: This method for producing the granular hydrous gel is characterized in that a mixed liquid (I) comprising a polyurethane resin (C) having a terminal isocyanate group obtained by reacting a polyisocyanate (A) with a liquid polyol (B) containing ≥70 wt.% of a copolymer obtained by copolymerizing ethylene oxide (a) and propylene oxide (b) in a weight ratio (a)/(b)=50/50-90/10, a water-soluble high-molecular polysaccharide (D) capable of gelling on contact with a metallic ion and water (E) is gelled in a granular form in an aqueous medium containing a metallic ion to thereby produce the granular shaped article. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a granular hydrous gel.

  Conventionally, it is known that a hydrophilic polyurethane resin obtained by crosslinking and curing an isocyanate group-containing polyurethane resin, which is a reaction product of a polyol and a polyisocyanate, with water can be used as a hydrated gel for a microorganism support or the like (for example, Advances in Biochemical). Engineering / Biotechnology, Vol. 29). However, since this hydrophilic polyurethane resin uses a mixture of hydrophilic polyethylene glycol and hydrophobic polypropylene glycol as a raw material polyol, the resin is likely to be solid or very high in viscosity and mixed with water. It is difficult, and since there is no uniformity between the hydrophilic part and the hydrophobic part of the resin, there is a disadvantage that the supportability of microorganisms as a hydrous gel is poor.

  In Patent Document 1, an isocyanate group-containing polyurethane resin using a copolymer of ethylene oxide and propylene oxide as a raw material polyol and water are used in a weight ratio of about 0.5 to 5 higher than that of the former 1. A hydrogel having continuous vents obtained by swelling with water after a crosslinking reaction at a concentration is disclosed as a porous carrier for a bioreactor. However, since this hydrogel contains a large number of closed cells as well as continuous vents, the specific gravity is lower than 1.0, and when used as a microorganism carrier, it floats on the surface of the water and is stirred. Has the disadvantage of poor dispersion efficiency. Further, this gel has a drawback that it has a low strength because it has a large number of continuous air holes and bubbles, and the volume swelling rate due to water is limited to 1,000%. Furthermore, this gel must be reacted with an isocyanate group-containing polyurethane resin and water at a high concentration. In this case, the pot life involved in the reaction between the isocyanate group in the polyurethane resin and water is several tens of seconds. There are also disadvantages of being short and inconvenient to handle.

  Therefore, the present applicant has solved the above-mentioned conventional drawbacks, and the volume expansion coefficient can exceed 1,000%. Moreover, the applicant has substantially no voids such as bubbles and pores and has a specific gravity of 1 or higher. A water-containing gel that has high strength and is suitable for use as a microorganism support and as a water retention material has been proposed (see Patent Document 2). Patent Document 3 also proposes a hydrogel having a volume expansion coefficient exceeding 1,000%.

JP-A-9-51794

WO01 / 081442 pamphlet JP 10-136980 A

  However, the hydrated gel is produced by pouring a resin liquid into a mold and forming it into a cube shape, and cutting it into about 3 mm square, which requires man-hours such as a cutting step. There were also practical limitations in the use of water retaining materials.

  The objective of this invention is providing the manufacturing method of the granular water-containing gel which can manufacture a granular molding, without impairing the property as a water-containing gel.

The present invention
1. A copolymer obtained by copolymerizing polyisocyanate (A) with ethylene oxide (a) and propylene oxide (b) at a weight ratio of (a) / (b) = 50/50 to 90/10 is 70. Terminal isocyanate group-containing polyurethane resin (C), which is a reaction product with liquid polyol (B) containing at least% by weight, water-soluble polymer polysaccharide (D) and water (E) capable of gelation by contact with metal ions And a mixed liquid (I) containing a metal ion in a granular form in an aqueous medium containing metal ions to produce a granular molded product,
2. 2. The method for producing a granular hydrogel according to claim 1, wherein the number average molecular weight of the polyurethane resin (C) is in the range of 1,000 to 100,000.
3. The method for producing a granular hydrous gel according to claim 1, wherein the addition amount of the water-soluble polymer polysaccharide (D) is 0.5 to 15 parts by weight relative to 100 parts by weight of the polyurethane resin (C).
4). The method for producing a granular hydrous gel according to 1, wherein the amount of water (E) added is greater than 9 by weight relative to the polyurethane resin (C) 1.
5). The method for producing a granular hydrous gel according to 1, wherein at least the water-soluble polymer polysaccharide (D) and water (E) are adjusted to 0 to 10 ° C and used in the preparation of the mixed liquid (I),
A granular hydrous gel obtained by the production method according to any one of 6.1 to 5,
A microorganism-supporting body comprising the granular hydrous gel according to 7.6,
A water-retaining material comprising the particulate hydrous gel according to 8.6,
About.

  According to the method of the present invention, a granular molded product can be easily produced without impairing properties as a hydrogel such as volume expansion coefficient. The obtained granular hydrous gel is highly practical as a microorganism support or a water retaining material, and can be expected to be used in various ways.

  As the polyisocyanate (A) in the present invention, a number average molecular weight of 100 to 2, which contains an average of 2 or more, preferably 2 to 4 isocyanate groups in one molecule conventionally used in the production of polyurethane resins. About 000 compounds can be preferably used.

  Specific examples of the polyisocyanate (A) include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; cyclic aliphatic diisocyanates such as hydrogenated xylylene diisocyanate and isophorone diisocyanate; Organic diisocyanates such as isocyanates, aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, or adducts of these organic diisocyanates with polyhydric alcohols, low molecular weight polyester resins, water, etc., or the above organic diisocyanates And the isocyanurate biuret of the above organic diisocyanates.

  Moreover, as a typical commercial item of polyisocyanate (A), for example, "Bernock D-750", "Bernock-800", "Bernock DN-950", "Bernock-970", "Bernock 15-455" (Above, manufactured by Dainippon Ink & Chemicals, Inc., trade name), “Desmodule L”, “Desmodule N”, “Desmodule HL”, “Desmodule IL”, “Desmodule N3390” (above, Germany) Kokuyo Bayer, trade name), “Takenate D-102”, “Takenate-202”, “Takenate-110N”, “Takenate-123N” (above, Takeda Pharmaceutical Co., Ltd., trade name), “Coronate” L "," Coronate HL "," Coronate EH "," Coronate 203 "(above, Nippon Polyurethane Industry Co., Ltd., trade name), Duranate 24A-90CX "(Asahi Chemical Industry Co., Ltd., trade name), and the like.

  Copolymer obtained by copolymerizing ethylene oxide (a) and propylene oxide (b) in the ratio of (a) / (b) = 50/50 to 90/10 by weight ratio, particularly random copolymer As the liquid polyol (B) containing at least 70 wt%, those containing 70 to 100 wt%, particularly 80 to 100 wt% of the random copolymer are preferred. The copolymerization ratio of ethylene oxide (a) and propylene oxide (b) is preferably a ratio of (a) / (b) = 50/50 to 80/20 in weight ratio. The random copolymer may be linear or branched. The copolymer has an average of 2 or more, preferably 2 to 4 alcoholic hydroxyl groups in one molecule, a number average molecular weight of about 500 to 50,000, and a hydroxyl group equivalent of about 250 to 25,000. These hydrophilic materials can be suitably used.

  The liquid polyol (B) is preferable because it is a low-viscosity liquid at room temperature, is easy to handle, and is easy to adjust the degree of hydrophilicity. Specifically, the polyol (B) is, for example, a random copolymer of ethylene oxide and propylene oxide at the specific ratio described above, and the following low molecular polyol added at the time of or after the production of this copolymer. A mixture of the copolymer with the low-molecular-weight polyol, a mixture of the copolymer with a polyalkylene glycol, or the like can be used.

  Examples of the low molecular polyol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hex Diols such as diol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol; glycerin, trimethylolpropane, trimethylolethane, trimethylolmethane, diglycerin, triglyceride Examples include trivalent or higher alcohols such as glycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, and mannitol.

  By appropriately adding a trivalent or higher polyol, which is the low molecular weight polyol, the crosslink density of the finally obtained gel can be increased and the strength can be further increased. However, adding too much is not preferable because the crosslinking density becomes too high and the volume expansion coefficient decreases. The amount of the trihydric or higher polyol is preferably 10% by weight or less in the liquid polyol (B).

  In addition, the low molecular polyol itself can be used in combination with the random copolymer of ethylene oxide (a) and propylene oxide (b) as appropriate.

  Furthermore, polyalkylene glycols such as polyethylene glycol can be used in combination with the random copolymer of ethylene oxide (a) and propylene oxide (b) as appropriate.

  The terminal isocyanate group-containing polyurethane resin (C), which is a reaction product of the polyisocyanate (A) and the liquid polyol (B) in the present invention, has an isocyanate group in the component (A) with respect to the hydroxyl group in the component (B). It mix | blends so that it may become excess, and it synthesize | combines by making it react normally at 10 degreeC or more, Preferably it is 20-200 degreeC for several minutes-several hours. The obtained resin (C) is usually a transparent solid or highly viscous liquid resin.

  The blending ratio of the polyisocyanate (A) and the liquid polyol (B) is usually about 1.01 to 2 mol of the isocyanate group in the component (A) with respect to 1 mol of the hydroxyl group in the component (B). Is a ratio in the range of about 1.1 to 2 moles. If the isocyanate group exceeds 2 moles, a large amount of unreacted polyisocyanate (A) remains, which is not preferable. On the other hand, if the isocyanate group is less than 1.01 mol, it is not preferable because it is too high in molecular weight and gelled.

  The number average molecular weight of the terminal isocyanate group-containing polyurethane resin (C) to be obtained is not particularly limited, but it is usually 1,000 to 100,000, preferably 2,000 to 8,000. In the present specification, the number average molecular weight is a value obtained by converting the molecular weight measured by gel permeation chromatography on the basis of the molecular weight of polystyrene.

  In the method of the present invention, a mixed solution containing a terminal isocyanate group-containing polyurethane resin (C) obtained as described above, a water-soluble polymer polysaccharide (D) capable of gelation by contact with metal ions, and water (E). A granular molded product is produced by gelling (I) into a granular form by dropping it into an aqueous medium containing metal ions.

  The water-soluble polymer polysaccharide (D) is a polymer polysaccharide that is water-soluble and has the ability to turn into a water-insoluble or sparingly soluble gel when contacted with metal ions in an aqueous medium. Having a number average molecular weight generally in the range of about 3,000 to about 2,000,000, and usually at least about 10 g / l (25 ° C.) in a water-soluble state prior to contact with the metal ion. Those showing solubility are preferably used.

  Specific examples of the water-soluble polymer polysaccharide (D) having such properties include alkali metal salts of alginic acid, carrageenan and the like. These water-soluble polymeric polysaccharides are dissolved in an aqueous medium, in the case of carrageenan, by contacting with alkali metal ions such as potassium ions and sodium ions, and in the case of alkali metal salts of alginic acid. Can be gelled by contact with at least one polyvalent metal ion selected from magnesium ion, calcium ion, strontium ion, barium ion, aluminum ion, cerium ion, nickel ion and the like. The concentration of the alkali metal ion or polyvalent metal ion at which gelation occurs varies depending on the type of water-soluble polymer polysaccharide, but is generally in the range of 0.01 to 5 mol / l. These water-soluble polymer polysaccharides can be used alone or in admixture of two or more.

  The amount of the water-soluble polymer polysaccharide (D) added is in the range of 0.5 to 15 parts by weight, preferably 1 to 8 parts by weight, based on 100 parts by weight of the terminal isocyanate group-containing polyurethane resin (C). It is desirable to obtain a granular molded product without impairing the properties of the produced hydrous gel.

  Moreover, the addition amount of the water (E) exceeds 9 times by weight with respect to the terminal isocyanate group-containing polyurethane resin (C) from the viewpoints of pot life, volume expansion coefficient, specific gravity and strength of the obtained hydrous gel. By adding an amount, preferably 10 to 20 times by weight, more preferably 12 to 15 times by weight, and mixing with stirring, a uniform liquid mixture of the resin and a large amount of water can be obtained. In the present invention, the polyurethane resin (C) undergoes a crosslinking reaction with a part of the water (E), whereby a hydrous gel containing a large amount of water is obtained. That is, the polyurethane resin (C) can be crosslinked and cured in the presence of a large amount of water exceeding 9 times by weight to obtain a hydrogel having a volume expansion coefficient exceeding 1,000%, for example. The water to be used may be pure water or water containing water-soluble components such as various salts as necessary. When the water-soluble polymer polysaccharide (D) is used as an aqueous solution, the amount of water in the aqueous solution is also appropriately converted as the amount of water (E) added.

  In the present invention, the granular molded product produced from the mixed solution (I) containing only the polyurethane resin (C), the water-soluble polymer polysaccharide (D) and water (E) usually has a specific gravity of 1 when containing water. Although it has a specific gravity in the range of 0.0 to 1.1, it can be adjusted to a desired specific gravity by adding a specific gravity adjusting material such as a pigment and hollow particles to the mixed liquid (I) as necessary. Is possible. In order to increase the specific gravity, a specific gravity adjusting material having a specific gravity of 1 or more such as glass beads, talc, mica, and barita is 50 parts by weight or less, preferably 0.1 to 50 parts by weight relative to 100 parts by weight of the polyurethane resin (C). By adding in the proportion of parts by weight, the specific gravity of the granular molded product can be adjusted to be in the range of 1.00 to 1.25. When it is desired to lower the specific gravity, a specific gravity adjusting material having a specific gravity of less than 1 such as hollow glass beads, hollow celite, and hollow polymer is 30 parts by weight or less, preferably 0.8 parts by weight relative to 100 parts by weight of the polyurethane resin (C). By adding 1-30 weight part, it can adjust so that the specific gravity of a granular molding may become the range of 0.90-1.00.

  Furthermore, fillers, such as activated carbon, can also be added as needed and this filler etc. can be mixed in a granular molding. In that case, the filler is first mixed in the mixed solution of only (D) and (E) at a ratio of about 1.0 to 20 parts by weight with respect to 100 parts by weight of the polyurethane resin (C), and then into this mixed solution. It is desirable to add polyurethane (C).

  From the point of pot life relating to the reaction between the isocyanate group in the polyurethane resin and water, the above mixed liquid (I) is at least water-soluble polymeric polysaccharide (D) and water ( It is desirable to adjust E) to 0 to 10 ° C, preferably 0 to 5 ° C. About a polyurethane resin (C), you may adjust to this temperature range as needed.

  The mixed liquid (I) thus prepared is then dropped into an aqueous medium containing the above-described types of metal ions, or when obtaining a granular material having an average particle diameter of 5 mm or more, The liquid mixture (I) is in a granular form by continuously pouring the surface of the aqueous medium for a predetermined time to grow the liquid droplets to a desired particle size and then allowing the liquid droplets to settle. Can be fooled.

  The liquid temperature of the aqueous medium containing metal ions is preferably adjusted in the range of 0 to 50 ° C., preferably 20 to 40 ° C., from the viewpoint of shortening the curing reaction time.

  The dropping of the mixed solution (I) into the aqueous medium containing metal ions is, for example, a method of dropping the mixed solution (I) from the tip of a syringe, or the mixed solution (I) is granulated using centrifugal force. The mixture liquid (I) is atomized from the tip of the spray nozzle and dropped into a granular form. Moreover, pouring of the liquid mixture (I) to the surface of the aqueous medium can be performed by continuously supplying it as a thin liquid flow from a nozzle opening having a desired pore diameter. The size of the droplets can be freely changed depending on the particle size desired for the final granular immobilization product, but in general, in the dropping method, the diameter is about 0.1 to about 10 mm, preferably about 0.5. It is convenient to drop the liquid droplets in the range of about 6 mm to about 6 mm, and in the case of the pouring method, the liquid droplets are in the range of about 0.5 to 3 cm, preferably about 1 to about 2 cm.

  The granular water-containing polyurethane gel produced as described above starts crosslinking and curing in the state of being dispersed in an aqueous medium as it is, and becomes a granular molded product. During the molding, the resin is sufficiently crosslinked and cured at room temperature, but if necessary, the crosslinking reaction may be accelerated by heating at 100 ° C. or lower.

  Considering the degree of gelation (crosslinking), the liquid temperature is 20 ° C., about 2 minutes from the start of mixing of the polyurethane resin (C) and water (E), and 0-4 ° C. within about 6 minutes from the start of mixing. It is desirable to finish the granulation in the aqueous medium in the meantime.

  The granular water-containing polyurethane gel thus obtained has a volume expansion coefficient of usually at least 900%, preferably more than 1,000%, more preferably 1,100 to 2,000%. Here, the volume expansion coefficient in the present invention is defined by the following equation.

Volume expansion rate (%) = (V / V ₀ ) × 100
In the formula, V ₀ represents the volume of the terminal isocyanate group-containing polyurethane resin (C) before adding water, and V represents the volume of the obtained water-containing polyurethane gel.

Further, since the hydrogel is obtained by crosslinking the polyurethane resin (C) in the presence of a large amount of water, CO ₂ generated during crosslinking is volatilized out of the system, so that voids such as bubbles and pores are substantially eliminated. The specific gravity when containing water is usually 1 or more. Further, the hydrogel has elasticity and high strength.

  The granular hydrous gel of the present invention can be suitably used for various microorganisms or water retention materials.

  The hydrated gel for microorganism carrier of the present invention is an elastic hydrated gel and is therefore suitable for adhesion of microorganisms, and can attach a large amount of microorganisms and their cells. The microorganisms that can be attached to the carrier are not particularly limited, and can be used for both anaerobic microorganisms and aerobic microorganisms. Moreover, it is suitable as a carrier for adhering one or two or more kinds of microorganisms, and is also suitable as a carrier for adhering a mixture of various microorganisms such as activated sludge.

  Specific examples of the microorganism include, for example, molds such as Aspergillus, Penicillium, and Fusarium; yeasts such as Saccharomyces, Faphia, and Candida; Zymomonas, Nitrosomonas, Nitrobacter, Paracoccus, Examples include bacteria such as genus, genus Methanosarcina, and Bacillus.

  The microorganisms can be attached to the granular hydrous gel as the carrier simply by, for example, putting them in a fermenter or bioreactor in which the microorganisms are suspended. In addition, the particulate hydrous gel as a carrier is put in the medium in advance, and the microorganism can be adhered by culturing the microorganism after inoculation. After attaching the microorganisms, they can be put into a bioreactor. The amount of the carrier to be introduced into a culture tank, fermenter, bioreactor or the like is not particularly defined, but is usually preferably in the range of about 1 to 60% by volume of the medium.

  The carrier is most suitable for use in a fluidized bed type bioreactor or a stirring type fermenter, but can also be applied to a fixed bed type bioreactor or fermenter. These can be used for alcohol production and wastewater purification.

  Moreover, since the water-containing gel for water-retaining materials of the present invention has high water-retaining properties, it can be suitably used for various water-retaining materials.

  For example, the water-retaining material of the present invention can be used as an indoor humidity adjusting material, a horticultural soil additive, an agricultural moisture adjusting material, a hydroponics medium, a desert greening material, and the like. In these uses, compared with the case where water is simply applied, the water can be retained on average for a considerably long period of time, so that its utility value is great.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Example 1
1 mol of random copolymer triol (number average molecular weight 3,000, hydroxyl group equivalent 1,000) of ethylene oxide / propylene oxide = 80/20 (weight ratio) branched with glycerin and 3 mol of tolylene diisocyanate are mixed, The reaction was carried out at 80 ° C. for 10 hours to obtain a trifunctional terminal isocyanate group-containing polyurethane resin (A-1) having a number average molecular weight of 4,000.

  To 9 g of this polyurethane resin (A-1), 30 g of a 2 wt% sodium alginate aqueous solution and 61 g of tap water were added and stirred well to obtain a cloudy resin solution. The liquid temperature of this resin liquid was about 20 ° C. When this resin solution was dropped into a 3 wt% calcium chloride aqueous solution adjusted to a liquid temperature of about 20 ° C. from the tip of the syringe from a liquid surface height of about 10 cm, a granular molded product having a particle size of about 4 mm was obtained. When this granular molded product was allowed to stand in the above calcium chloride aqueous solution for about 45 minutes, a pudding-like granular hydrous gel was obtained. This hydrogel had a specific gravity of 1.01 and a volume expansion coefficient of 1,200%.

  The elapsed time from mixing the polyurethane resin (A-1), sodium alginate aqueous solution and tap water to adding the resin liquid to the calcium chloride aqueous solution to obtain a granular molded product was about 200 seconds. It was.

Example 2
To 9 g of the polyurethane resin (A-1) obtained in Example 1 above, a mixture of 30 g of a 2 wt% sodium alginate aqueous solution and 61 g of tap water cooled to a liquid temperature of about 0 to 4 ° C. is added. The mixture was well stirred to obtain a cloudy resin solution. When this resin solution was dropped into a 3% calcium chloride aqueous solution adjusted to a liquid temperature of about 20 ° C. from the tip of the syringe from a liquid surface height of about 10 cm, a granular molded product having a particle size of about 5 mm was obtained. When this granular molded product was allowed to stand in the aqueous calcium chloride solution for about 45 minutes, a pudding-like granular hydrous gel was obtained. This hydrogel had a specific gravity of 1.01 and a volume expansion coefficient of 1,300%.

  The elapsed time from the mixing of the polyurethane resin (A-1), the aqueous solution of sodium alginate and tap water to the addition of the resin solution to the aqueous calcium chloride solution to obtain a granular molded product is about 400. Although it was second, there was no problem in the shape of the granular molded product, and long-term workability was ensured as compared with Example 1.

  Next, 20 ml of the above-mentioned granular hydrogel was added to a 500 ml Erlenmeyer flask, and then GY-10 medium (consisting of yeast extract 1 g / l and glucose 100 g / l) was added to a total volume of 100 ml. Thereafter, Zymomonas mobilis IFO 13756 was added to a concentration of 2% by weight, and static culture was performed at 30 ° C. for 24 hours. After culturing, PBS buffer (sodium chloride 8 g / l, disodium hydrogen phosphate dodecahydrate 2.9 g / l, potassium chloride 0.2 g / l, potassium dihydrogen phosphate, adjusted to pH 7.4) After washing with 0.2 g / l), the fermentation broth was replaced with a new GY-10 medium and static culture was performed for 6 hours. As a result, ethanol was produced well at an ethanol concentration of 5.0% by weight. did.

Comparative Example 1
In Example 1, except that 30 g of tap water was used instead of 30 g of the 2% by weight sodium alginate aqueous solution, the cloudy resin solution was poured into the aqueous solution from the tip of the syringe to a liquid level height of about 30 g. When dropped from 10 cm, the cloudy resin slowly diffused into the aqueous solution to form an amorphous solid, and no granular molded product was obtained.

Claims (8)

A copolymer obtained by copolymerizing polyisocyanate (A) with ethylene oxide (a) and propylene oxide (b) at a weight ratio of (a) / (b) = 50/50 to 90/10 is 70. Terminal isocyanate group-containing polyurethane resin (C), which is a reaction product with liquid polyol (B) containing at least wt%, water-soluble polymer polysaccharide (D) and water (E) capable of gelation by contact with metal ions And a mixed liquid (I) containing a metal ion in a granular form in an aqueous medium containing metal ions to produce a granular molded product. The method for producing a granular hydrogel according to claim 1, wherein the number average molecular weight of the polyurethane resin (C) is in the range of 1,000 to 100,000. The method for producing a granular hydrous gel according to claim 1, wherein the addition amount of the water-soluble polymer polysaccharide (D) is 0.5 to 15 parts by weight with respect to 100 parts by weight of the polyurethane resin (C). The method for producing a granular hydrous gel according to claim 1, wherein the amount of water (E) added is more than 9 by weight ratio to the polyurethane resin (C) 1. The method for producing a granular hydrous gel according to claim 1, wherein in preparing the mixed liquid (I), at least the water-soluble polymer polysaccharide (D) and water (E) are adjusted to 0 to 10 ° C. The granular hydrous gel obtained by the manufacturing method of any one of Claims 1 thru | or 5. A microbial support comprising the particulate hydrogel according to claim 6. A water-retaining material comprising the particulate hydrogel according to claim 6.