JP2003073443A - Biodegradable highly water-absorbing resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly water-absorbing resin which is disposable easily. SOLUTION: The biodegradable highly water-absorbing resin is obtained by crosslinking cellulose which may have a substituent, and starch which may have a substituent or a compound having a polyethylene glycol group, (hereinafter these are expressed as principal components), by using a biodegradable crosslinking agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable highly water-absorbent resin. More specifically, the present invention relates to a super absorbent for paper diapers, greening materials or water blocking agents.

[0002]

2. Description of the Related Art The water absorbent for paper diapers which is widely used in the world at present is a glycidyl cross-linked product of sodium polyacrylate, and the disposal method after use is a serious problem. In other words, in landfill disposal, the space at the disposal site is running out because it remains forever. In addition, in incineration, it is difficult to dispose of incinerated ash, because contact with water such as sodium oxide tends to generate heat or a dangerous substance showing strong alkalinity is generated. Further, the superabsorbent resin is often used in the field of greening or water stoppage, but it is inconvenient from an environmental point of view that it remains forever.

[0003]

SUMMARY OF THE INVENTION The present invention is for a disposable diaper,
When it is used as landfill or used in nature as a super absorbent for greening or water stoppage, it is biodegraded by bacteria in the soil and its capacity is greatly reduced, and when incinerated, sodium oxide is used. It is an object of the present invention to provide a water-absorbing agent that does not generate such dangerous substances.

[0004]

Means for Solving the Problems The present inventor has found that an acidic group, a basic group, an alkyl group, a hydroxyalkyl group, a cellulose which may have an acetyl group or an acetoacetyl group, an acidic group, a basic group, For disposable diapers, one or more substances selected from compounds having an alkyl group, a hydroxyalkyl group, an acetyl group or an acetoacetyl group, or a compound having a polyethylene glycol group are crosslinked with a biodegradable crosslinking agent. Thus, a biodegradable highly water-absorbent resin suitable for a water-absorbing agent for greening or water-stopping agent was obtained.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. In the present invention, examples of the acidic group include groups such as carboxyalkyl group and sulfoxyalkyl group.
As the counter ion of the carboxy group or the sulfoxy group, a hydrogen atom, ammonium, or an organic amine salt is preferable.

In the present invention, as the basic group, an amino group, a monoalkylamino group in which an alkyl group may be substituted with a hydroxy group, a dialkylamino group, a trialkylamino group, or an alkyl group with a hydroxy group is substituted. Groups such as optionally substituted tetraalkylammonium groups are mentioned. Specific examples include a monoethanolamino group, a diethanolamino group, a triethanolamino group, a trimethylhydroxyethylammonium group, and a trimethylhydroxypropylammonium group. In addition, a carboxymethylamino group having both an acidic group and a basic group is also included.

In the present invention, examples of the alkyl group include a methyl group and an ethyl group.

In the present invention, examples of the hydroxyalkyl group include hydroxymethyl group, hydroxyethyl group and hydroxypropyl group.

Examples of the compound having a polyethylene glycol group used in the present invention include polyethylene glycols such as polyethylene glycol # 1000 and polyethylene glycol # 6000, polyethylene glycol monoalkyl ethers such as polyethylene glycol monomethyl ether, and polyethylene. Glycol monoacetyl, polyethylene glycol monosuccinate (half ester half carboxylic acid) or polyethylene glycol both ends maleate (half ester half carboxylic acid)
By reacting a compound having a glycidyl group such as polyethylene glycol acyl ester such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether or sorbitol polyglycidyl ether with polyethylene glycol # 400 or # 600. The compound obtained, or a compound obtained by reacting a compound having an isocyanate group such as MDI or TDI with polyethylene glycol such as polyethylene glycol # 400 or # 600, bisoxazoline or 1,3
A compound obtained by reacting a compound having an oxazoline group such as benzobisoxazoline with a polyethylene glycol such as polyethylene glycol # 400 or # 600, a polyethylene glycol such as that described above for a compound having a triazine group such as trichlorotriazine Compound obtained by reacting, butane tetracarboxylic acid anhydride or a compound obtained by reacting an acid anhydride such as pyromellitic acid anhydride with polyethylene glycol as described above, polyethylene glycol monoallyl ether as a polymerization component Examples thereof include polymers having a hydroxy group, such as homo- or copolymers and homo- or copolymers having polyethylene glycol acrylic ester as a polymerization component.

Examples of the biodegradable crosslinking agent used in the present invention include polyalkylene polyols having a polyglycidyl ether group such as pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether or polyethylene glycol diglycidyl ether. , Reacts with the hydroxy group in the main agent to effect crosslinking. In addition, polyalkylene polyols having a polyisocyanate group such as polyethylene glycol diisocyanate, glycerol triisocyanate or trimethylolpropane triisocyanate or polyisocyanates derived from chitosan can be mentioned. Crosslinking occurs by reacting with a hydroxy group in the main agent. Be seen. In addition, polycarboxylic acid anhydrides such as butane tetracarbohydrate, ethylene glycol bisanhydrotrimellitate, and diphenyl sulfone tetracarbohydrate can be mentioned. Crosslinking occurs by reacting with hydroxy group or amino group in the main agent. Done.
In addition, oligoaldehydes such as glyoxal and adipine aldehyde are mentioned, and crosslinking is carried out by reacting with a hydroxy group in the main agent. Dimethylol urea,
An oligomethylol compound such as dimethylol melamine can be mentioned, which is crosslinked by reacting with a hydroxy group in the main agent. In addition, oligocarbohydrazides such as carbohydrazide and adipinehydrazide are mentioned, and they are crosslinked by reacting with an acetoacetyl group in the main agent.

In the present invention, the amount of the crosslinking agent used is 1 to 50 equivalent% based on the main agent. If it is 1% or less, the strength of the gel is insufficient and the usability is poor, and if it is 50% or more, the water absorption is insufficient. When the biodegradable highly water-absorbent resin of the present invention is used in the form of a sheet, the amount of the crosslinking agent used is 1 to 10 equivalent% with respect to the main agent. If it is 1% or less, the strength of the gel is insufficient, and if it is 10% or more, the sheet cannot be formed well.

The biodegradable highly water-absorbent resin of the present invention contains a biodegradable surfactant such as sugar ester in an amount of 0.1 to 3% by weight based on the total weight of the resin in order to improve its water absorption rate. It may be. Less than 0.1%, poor effect, 3%
Even if added above, the effect reaches the ceiling.

The biodegradable superabsorbent resin of the present invention can be used in the form of fine powder, but the particle size is 0.1 to 5 mm.
It is also possible to use it in the form of granules. By making it into a granular form, the water absorbing agent as a whole can maintain the water absorbing property for a long time, and the usability is improved depending on the application.

Since the biodegradable highly water-absorbent resin of the present invention has a film-forming ability, it is formed into a sheet by an ordinary casting method,
It can also be used in sheet form. In addition, in order to enhance mechanical strength or to make the product into a wide variety of forms, a biodegradable highly water-repellent resin of the present invention or a particle derived from a natural product such as starch, cellulose, silk or chitin was added to the resin. It is also possible to impregnate a material into a fibrous material derived from a natural material such as paper, cotton, rayon, wool and silk to form a sheet.

With respect to particles derived from natural products, the addition of this prevents the water-absorbing agent particles from stepping due to surface wetting, resulting in improved water absorption and mechanical strength of the sheet when formed into a sheet. It is thought that. Regarding the particle size, it is possible to properly adjust the particle size separately to about 1 to 500 μm by using a device for making fine particles such as a ball mill and a sand grinder. The addition amount thereof is about 1 to 30% by weight based on the biodegradable superabsorbent resin used in combination. It can be selected according to the required performance as a product such as film strength or film hardness.

[0016]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. The parts mean the meanings of parts by weight.

[Example 1] To 1,000 parts of dioxane,
Add 100 parts of methyl cellulose and 25 parts of diketene,
The mixture was stirred at 5 ° C for 8 hours. Adipine hydrazide 30
Parts were added and reacted at 50 ° C. for 24 hours. Then 100
Dioxane was distilled off by heating at 0 ° C. for 5 hours, and the obtained solid was pulverized to obtain 150 parts of a pale yellow powder. When 30 parts of this powder was added to 1,000 parts of physiological saline, the whole system became a gel and absorbed water in 6 minutes. When this gel was embedded in soil and confirmed one year later, the gel was assimilated to the soil.

[Example 2] To 500 parts of dioxane, 200 parts of hydroxypropylated starch, 20 parts of glycerol triglycidyl ether and 5 parts of tetrabutylammonium hydroxide were added, and after reacting at 80 ° C for 5 hours,
2 parts of sugar ester was added and dioxane was distilled off at 110 ° C. to obtain 215 parts of a yellow solid. Crush the solid,
Pelletized to a diameter of 2 mm. When 40 parts of the pellet was added to 1,000 parts of physiological saline, it gelled and absorbed water in 3 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

When the fine powder obtained in Example 2 was pelletized without adding sugar ester, gelation required 12 minutes. When it was used as a fine powder without pelletization, it became a step and partially gelled, but the whole system did not gel.

[0020]

Example 3 To 500 parts of dioxane, 200 parts of methyl-hydroxyethylated cellulose, 10 parts of polyethylene glycol (# 200) diglycidyl ether and 2 parts of choline hydroxide were added and reacted at 80 ° C. for 5 hours, and then at 110 ° C. Dioxane was distilled off with a pale yellow solid 210
I got a part. The solid was crushed, and 20 parts of the fine powder was added to 1,000 parts of physiological saline, which gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0021]

Example 4 To 500 parts of dioxane, 200 parts of carboxymethyl cellulose and 30 parts of dimethylolurea were added, and after reacting at 100 ° C. for 10 hours, dioxane was distilled off at 110 ° C. to obtain 228 parts of a pale yellow solid. The solid was crushed, and 25 parts of the fine powder was added to 1,000 parts of physiological saline, which gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0022]

Example 5 To 500 parts of dimethoxyethane, 200 parts of polyethylene glycol (# 2,000) and 20 parts of butanetetracarbohydride were added, and the mixture was reacted at 80 ° C. for 9 hours, and then dimethoxyethane was distilled off at 100 ° C. 215 parts of a pale yellow viscous solid was obtained. When 40 parts of the viscous solid was added to 1,000 parts of physiological saline, it gelled and absorbed water in 6 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0023]

Example 6 500 parts of dimethoxyethane and 200 parts of trimethyl-hydroxypropylammonium-modified cellulose
Parts and 15 parts of ethylene glycol bisanhydrotrimellitate were added and reacted at 80 ° C. for 8 hours, and then dimethoxyethane was distilled off at 100 ° C. to obtain 212 parts of a pale yellow solid. The solid was crushed, and 25 parts of the fine powder was added to 1,000 parts of physiological saline, which gelled and absorbed water in 7 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0024]

Example 7 To 500 parts of dimethoxyethane, 200 parts of hydroxyethyl cellulose and 20 parts of glyoxal were added, and after reacting at 90 ° C. for 48 hours, dimethoxyethane was distilled off at 100 ° C. to obtain 209 parts of a pale yellow solid. When the solid was crushed and 33 parts of the fine powder was added to 1,000 parts of physiological saline, it gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0025]

Example 8 To 500 parts of diethoxyethane, 200 parts of hydroxyethyl starch, 20 parts of polyethylene glycol diisocyanate and 1 part of triethanolamine were added, and 6 parts
After reacting at 0 ° C for 8 hours, diethoxyethane was distilled off at 100 ° C to obtain 210 parts of a pale yellow viscous solid. When 30 parts of the viscous solid was added to 1,000 parts of physiological saline, it gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0026]

Example 9 To 500 parts of dimethoxyethane, 200 parts of acetylcellulose and 20 parts of dimethylolmelamine were added, and after reacting at 90 ° C. for 8 hours, dimethoxyethane was distilled off at 100 ° C. to obtain 212 parts of a pale yellow viscous solid. Obtained. When 30 parts of the viscous solid was added to 1,000 parts of physiological saline, 7
It gelled and absorbed water in minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0027]

Example 10 To 500 parts of dimethoxyethane, 200 parts of hydroxyethyl cellulose and 15 parts of diphenylsulfone tetracarbohydride were added, and the mixture was mixed at 80 ° C. for 1 hour.
After reacting for 0 hour, dimethoxyethane was distilled off at 100 ° C. to obtain 209 parts of a pale yellow viscous solid. Saline 1,00
When 30 parts of the viscous solid was added to 0 part, gelation occurred in 6 minutes,
It absorbed water. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0028]

Example 11 500 parts of dioxane, 200 parts of polyethylene glycol # 4000, and adipic aldehyde 2
5 parts was added and reacted at 90 ° C. for 10 hours. 5 at 110 ° C
Dioxane was distilled off by heating for a while, and a pale yellow viscous solid 22
I got 0 copies. When 30 parts of the viscous solid was added to 1,000 parts of physiological saline, it gelled and absorbed water in 7 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil. Add 20 parts of roll triglycidyl ether and 5 parts of tetrabutylammonium hydroxide,
After reacting at 5 ° C for 5 hours, 2 parts of sugar ester was added and dioxane was distilled off at 110 ° C to obtain 215 parts of a yellow solid. The solid was ground and pelletized to a diameter of 2 mm.
When 40 parts of the pellet was added to 1,000 parts of physiological saline, it gelled and absorbed water in 3 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[Example 12] To 1,000 parts of dioxane, 100 parts of polyethylene glycol # 600 and 5 parts of diketene were added, and the mixture was stirred at 95 ° C for 8 hours. 10 parts of adipine hydrazide was added to this, and it was made to react at 50 degreeC for 24 hours. Then, the mixture was heated at 100 ° C. for 5 hours to distill off dioxane, and the obtained solid was pulverized to obtain 150 parts of a pale yellow powder. When 40 parts of this powder was added to 1,000 parts of physiological saline, the entire system became a gel and absorbed water in 5 minutes.
When this gel was embedded in soil and confirmed one year later, the gel was assimilated to the soil.

Example 13 To 500 parts of dioxane, 200 parts of acetic acid starch, 20 parts of erythritol polyglycidyl ether and 5 parts of tetrabutylammonium hydroxide were added, and after reacting at 80 ° C. for 5 hours, 2 parts of sugar ester was added. Dioxane was distilled off at 110 ° C,
215 parts of a yellow solid were obtained. The solid is crushed to have a diameter of 1 mm.
Pelletized. When 33 parts of the pellet was added to 1,000 parts of physiological saline, it gelled and absorbed water in 3 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

When the fine powder obtained in Example 13 was pelletized without addition of sugar ester, the fine powder was gelled.
It took a minute. When it was used as a fine powder without pelletization, it became a step and partially gelled, but the whole system did not gel.

[0032]

Example 14 To 500 parts of dioxane, 200 parts of methylated cellulose and 10 parts of polyethylene glycol diisocyanate were added and reacted at 50 ° C. for 5 hours, then at 110 ° C.
The dioxane was distilled off to obtain 208 parts of a pale yellow solid. The solid was crushed, and 20 parts of the fine powder was added to 1,000 parts of physiological saline, which gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0033]

Example 15 To 500 parts of dioxane, 200 parts of hydroxypropyltrimethylammonium cellulose and 30 parts of dimethylolurea were added, reacted at 100 ° C. for 10 hours, and then dioxane was distilled off at 110 ° C. to give a pale yellow solid 2
28 parts were obtained. The solid is crushed to obtain a physiological saline solution of 1,000.
When 25 parts of the fine powder was added to a part, gelation and water absorption occurred in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0034]

Example 16 To 500 parts of dimethoxyethane, 200 parts of carboxymethyl cellulose and 20 parts of butanetetracarbohydride were added, and after reacting at 80 ° C. for 9 hours, dimethoxyethane was distilled off at 100 ° C. to obtain 215 parts of a pale yellow solid. Got The viscous solid 4 in 1,000 parts of physiological saline
When 0 part was added, it gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0035]

Example 17: 500 parts of dimethoxyethane and 20 parts of trimethyl-hydroxypropylammonium-modified cellulose
After adding 0 part and 15 parts of glyoxal and reacting at 95 ° C for 12 hours, dimethoxyethane was distilled off at 100 ° C to obtain 212 parts of a pale yellow solid. The solid was crushed, and 33 parts of the fine powder was added to 1,000 parts of physiological saline, which gelled and absorbed water in 7 minutes. Buried this gel in the soil, one year later,
Upon confirmation, it was assimilated with the soil.

[0036]

Example 18 To 500 parts of dimethoxyethane, 200 parts of methyl cellulose and 20 parts of tannic acid were added, and after reacting at 90 ° C. for 48 hours, dimethoxyethane was distilled off at 100 ° C. to obtain 214 parts of a pale yellow solid. When the solid was pulverized and 33 parts of the fine powder was added to 1,000 parts of physiological saline,
It gelled and absorbed water in 5 minutes. Embed this gel in the soil and
A year later, when I confirmed, it was assimilated with the soil.

[0037]

Example 19 To 500 parts of dimethoxyethane, 200 parts of methyl cellulose and 20 parts of butanetetracarbohydride were added, and the mixture was reacted at 80 ° C. for 9 hours and then at 100 ° C.
The dimethoxyethane was distilled off to obtain 215 parts of a pale yellow solid. When 40 parts of the viscous solid was added to 1,000 parts of physiological saline, it gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0038]

Example 20 To 500 parts of dimethoxyethane, 200 parts of carboxymethyl cellulose and 20 parts of tannic acid were added, and after reacting at 90 ° C. for 48 hours, dimethoxyethane was distilled off at 100 ° C. to obtain 214 parts of a pale yellow solid. . When the solid was crushed and 33 parts of the fine powder was added to 1,000 parts of physiological saline, it gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0039]

Example 21 To 500 parts of dimethoxyethane, 200 parts of methyl cellulose and 15 parts of glyoxal were added to give 95 parts.
After reacting at 12 ° C for 12 hours, dimethoxyethane was distilled off at 100 ° C to obtain 212 parts of a pale yellow solid. The solid was crushed, and 33 parts of the fine powder was added to 1,000 parts of physiological saline, which gelled and absorbed water in 7 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0040]

Example 22 To 500 parts of dioxane, 200 parts of hydroxypropyl starch and 30 parts of dimethylolurea were added,
After reacting at 100 ° C for 10 hours, dioxane was distilled off at 110 ° C to obtain 228 parts of a pale yellow solid. The solid was crushed, and 25 parts of the fine powder was added to 1,000 parts of physiological saline, which gelled and absorbed water in 5 minutes. When this gel was buried in soil and confirmed one year later, it was assimilated with soil.

[0041]

Example 23 To 500 parts of dioxane, 200 parts of methyl-hydroxyethylated cellulose, 2 parts of polyethylene glycol (# 200) diglycidyl ether and 0.2 part of choline hydroxide were added, and after reacting at 80 ° C. for 5 hours, Dioxane was distilled off at 110 ° C. to give a pale yellow solid 21.
I got 0 copies. 10 parts of this solid was kneaded with 100 parts of water to obtain a high-viscosity liquid, which was cast onto a biaxially oriented polypropylene film and dried to obtain a film having a thickness of 2 mm and being soft and flexible.

[0042]

Example 24 To 500 parts of dioxane, 200 parts of hydroxyethylated cellulose and 3 parts of dimethylolurea were added, and after reacting at 100 ° C. for 10 hours, dioxane was distilled off at 110 ° C. to obtain 200 parts of a pale yellow solid. It was This individual 1
A high-viscosity liquid was obtained by kneading 0 parts and 2 parts of rice starch particles (average particle size 2 μm) with 100 parts of water, and in the same manner as in Example 23, a film was obtained. The film was hard and brittle compared to the film obtained in Example 23.

[0043]

[Example 25] The high-viscosity liquid obtained in the same manner as in Example 24 was impregnated into three pieces of commercially available gauze for treating wounds and dried to obtain a film having a thickness of 2 mm. Example 24
The hardness was equivalent to that of the film obtained in 1. and the brittleness was improved.

[0044]

Industrial Applicability The superabsorbent resin of the present invention is suitable for a diaper, a greening material, a water blocking material, etc., and can be easily discarded.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 20/26 C08G 59/62 4F072 20/28 C08J 3/12 CEPZ 4G066 C08G 59/62 5/04 4J005 65 / 321 ZBP 5/18 4J034 C08J 3/12 CEP C08L 1:00 4J036 5/04 C08G 65/32 ZBP 5/18 A41B 13/02 D // A61L 15/60 A61F 13/18 307A C08L 1:00 F Term (Reference) 3B029 BA17 4C003 AA23 4C098 AA09 CC03 DD05 DD06 DD13 DD14 DD23 DD25 DD26 DD27 DD30 4F070 AA02 AA03 AA52 AB13 AC40 AC45 AC84 AC85 AC87 AC89 AE08 DA28 DA40 DC07 DC11 DC15 DC16 4F071 AA08 A80 A02 A02 A05 A05 A05 A02 A05 A05 A05 A05 A05 A05 A05 A02 A05 A05 A05 A05 A05 A02 A05 A02 A05 A02 A05 A05 A02 AA06 AA07 AB03 AD01 AD23 AD42 AD43 AG03 AH02 AH25 AL00 AL09 4G066 AC01A AC02A AC37B AC37D AD07B BA0 9 BA16 CA43 DA13 DA20 FA25 4J005 AA02 BC00 BD00 4J034 BA03 DA01 DB05 DB07 DC02 DC12 DC25 DC50 DG02 DG03 EA05 EA08 HA06 HB11 JA41 QB04 QB11 QC04 RA02 RA04 RA09 4J036 AE07 DB02 FB12 FB18 JA01 JA11 JA15 JA15 JA11 JA15

Claims (19)

[Claims] 1. Cellulose optionally having a substituent, starch optionally having a substituent, or a compound having a polyethylene glycol group (hereinafter referred to as a main component) is crosslinked with a biodegradable crosslinking agent. A biodegradable highly water-absorbent resin characterized in that 2. A cellulose having an alkyl group, a hydroxyalkyl group or an acetyl group, or a starch having an alkyl group, a hydroxyalkyl group or an acetyl group, which is crosslinked with a biodegradable crosslinking agent. The biodegradable highly water-absorbent resin according to claim 1. 3. The biodegradable superabsorbent resin according to claim 1, wherein cellulose having an acetoacetyl group or starch having an acetoacetyl group is crosslinked with a biodegradable crosslinking agent. . 4. A polyalkylene polyol having a polyglycidyl ether group as a biodegradable crosslinking agent, a polyalkylene polyol having a polyisocyanate group, an acid anhydride compound, an oligoaldehyde compound, an oligomethylol compound or tannic acid. The biodegradable highly water-absorbent resin according to claim 2, wherein 5. The biodegradable superabsorbent resin according to claim 3, wherein the biodegradable crosslinking agent is an oligocarbohydrazide compound. 6. Cellulose which may have an acidic group or a basic group or starch which may have an acidic group or a basic group may be used as an acid anhydride compound, an oligoaldehyde compound or an oligomethylol compound. Alternatively, the biodegradable superabsorbent resin according to claim 1, which is crosslinked with tannic acid. 7. A biodegradable highly water-absorbent resin according to claim 1, wherein a compound having a polyethylene glycol group is cross-linked with acid anhydride compounds, oligoaldehyde compounds, oligomethylol compounds or tannic acid. . 8. The biodegradable highly water-absorbent resin according to any one of claims 1, 2, 3, 4, 5, 6 or 7, which comprises a biodegradable surfactant. 9. The biodegradable highly water-absorbent resin according to any one of claims 1, 2, 3, 4, 5, 6, 7 or 8 having a particulate matter derived from a natural product. 10. The biodegradable highly water-absorbent resin according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, which is in the form of granules. 11. Claims 1, 2, 3, 4, 5, 6, 7,
A disposable diaper characterized by using the biodegradable highly water-absorbent resin described in 8, 9, or 10. 12. Claims 1, 2, 3, 4, 5, 6, 7,
A material for revegetation, characterized by using the biodegradable highly water-absorbent resin described in 8, 9, or 10. 13. Claims 1, 2, 3, 4, 5, 6, 7,
A water-stop agent comprising the biodegradable highly water-absorbent resin described in 8, 9, or 10. 14. Claims 1, 2, 3, 4, 5, 6, 7,
A dehydrating agent for cooking, characterized by using the biodegradable highly water-absorbent resin according to 8, 9 or 10. 15. The biodegradable superabsorbent resin according to claim 9, wherein the particulate matter derived from a natural product is starch particles, cellulose particles, silk particles or chitin particles. 16. Claims 1, 2, 3, 4, 5, 6, 7, 8
Alternatively, a sheet-like material, which uses the biodegradable highly water-absorbent resin described in 9. 17. Claims 1, 2, 3, 4, 5, 6, 7, 8
Alternatively, a sheet-like product characterized by using the biodegradable superabsorbent resin according to 9 and a particulate product derived from a natural product. 18. Claims 1, 2, 3, 4, 5, 6, 7, 8
Alternatively, a sheet-shaped article, characterized in that the biodegradable superabsorbent resin according to 9 is impregnated into a fibrous substance made of a natural material. 19. Claims 1, 2, 3, 4, 5, 6, 7, 8
Alternatively, a sheet-like material, characterized in that the biodegradable highly water-absorbent resin according to 9 and a particulate material derived from a natural material are impregnated into a fibrous substance made of a natural material.