JP2002265672A - Absorbing material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-absorbing material which has biodegradability, has such an excellent water-absorbing rate as capable of being supplied for practical uses without causing a trouble, and has a high gel strength after the absorption of water. SOLUTION: This method for producing the absorbing material is characterized by dissolving and swelling galactomannan in water to form the 2 to 8 wt.% galactomannan sol, adding boric acid and a trivalent or more-valent metal ion except the boric acid to the sol to form the cross-linked product, mixing and crushing the cross-linked product with a hydrophilic organic solvent, and then drying the crushed product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable composition,
The present invention relates to an absorbent having excellent absorption performance, particularly excellent absorption speed, and a method for producing the same.

[0002]

2. Description of the Related Art [Technical Background of Absorbing Material] An absorbing material is a resin that can absorb water of several tens to several thousand times its own weight. For example, an acrylic absorbing material is known. These absorbents are widely used in disposable hygiene articles due to their high absorbency. However, the conventional absorbent has no decomposability, and there is a problem in a method for treating sanitary articles containing the absorbent.

[Technical background of biodegradable absorbents] As biodegradable absorbents, for example, crosslinked polyethylene oxide (Japanese Patent Laid-Open Publication No. 6-157795), crosslinked polyvinyl alcohol, crosslinked carboxymethylcellulose ( U.S. Pat. No. 4,650,716), crosslinked alginic acid,
Crosslinked starch (JP-A-55-15634), crosslinked polyamino acid (JP-A-7-224163, JP-A-7-309943, JP-A-8-59820, JP-A-8-504219) JP-A-9-169
840), a galactomannan-metal ion crosslinked product (JP-A-8-59891, JP-B-3-663)
No. 21, JP-A-56-97450, and the like are known.

By the way, when compared with a non-biodegradable synthetic polymer-based absorbent, the above-mentioned biodegradable absorbent has high production cost, low absorption performance, and low gel strength after absorption. There is a problem and it has not been put to practical use. Therefore, the present inventors have reported that the absorbent composed of galactomannan and boron or a polyvalent metal ion having a valence of 3 or more other than boron has biodegradation, and has excellent water absorption performance and gel strength after absorption. No. 2000-38005). Although this technique is extremely significant, it has not yet been fully satisfactory, and there has been a demand for a further improvement in the performance of the absorbent. In particular, a fast absorption rate has been desired.

[0005]

The absorbent used for sanitary articles is required to absorb a large amount of body fluids such as urine, blood, menstrual blood, sweat, etc. quickly. If the absorption capacity of the absorbent after 1 minute is 20 times or less, these bodily fluids are not quickly absorbed by sanitary articles such as disposable diapers, and leakage occurs.
Not practically preferable.

The gel strength at the time of 30-fold absorption is 1500.
When the concentration is 0 × 10 ⁻⁷ N / mm ² or less, the gel particles tend to stick to each other at the time of absorbing a body fluid, generating “mamako” and slowing down the absorption speed. In addition, absorption rates are also affected by surface area. When the total weight of the absorbent particles used is constant, the larger the particles, the smaller the sum of the surface areas, and the smaller the area in contact with water, the lower the absorption rate. Conversely, the finer the particles, the greater the sum of the surface areas and the faster the absorption rate. However, even if the particles of the absorbent are fine, when they come in contact with water, "Mamako" will occur,
This may not increase the absorption rate. When this absorbent material comes into contact with water, only the surface of the absorbent material absorbs, and the surface becomes tacky.
It is considered that water is prevented from penetrating into the interior of the particle aggregate.

An object of the present invention is to solve the conventional problems as described above, to have biodegradability, to have an excellent water absorption rate that can be provided without any practical problems, and to have a high water absorption rate after absorption. It is to provide a water-absorbing material having high gel strength.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have cross-linked galactomannan with boron and a trivalent or higher polyvalent metal ion other than boron, and obtained a crosslinked galactomannan with a hydrophilic organic compound. The inventors have found that excellent gel strength and absorptivity, particularly excellent absorptive speed can be exhibited by crushing in a solvent and drying the gel particles, thereby completing the present invention.

That is, the first aspect of the present invention is that a galactomannan is formed of a gel crosslinked with boron and a trivalent or higher polyvalent metal ion other than boron. One minute later, the gel strength is 20 times or more of its own weight, and the gel strength in a state where a 0.9 mass% aqueous sodium chloride solution absorbs 30 times its own weight is 15000 × 10 ⁻⁷ N / mm ² or more. The gist is an absorbent material. In the second aspect of the present invention, galactomannan is dissolved and swelled in water to form a galactomannan sol of 2 to 8% by mass, and then boron and a trivalent or higher polyvalent metal ion other than boron are added. Forming a crosslinked body, mixing the crosslinked body with a hydrophilic organic solvent, crushing the mixture, and drying the mixture, followed by drying.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The method for producing an absorbent material according to the present invention comprises: (a) supplying galactomannan to water to hydrate and swell to produce a sol liquid having a galactomannan concentration of 2 to 8% by mass;
(B) adding a boron ion and a trivalent or higher polyvalent metal ion other than boron to the galactomannan sol solution to form a galactomannan crosslinked gel; (c) forming the galactomannan crosslinked gel in a hydrophilic organic solvent. It consists of each step of crushing and drying.

The galactomannan used in the step (a) can be crosslinked with titanium and boron ions, and the dried product has an absorption capacity after 1 minute of 20 times or more of its own weight, and a gel strength at the time of absorption of 30 times. Is 15000 × 10 ^-7 N /
There is no particular limitation as long as it is not less than mm ² . For example, locust bean gum, guar gum,
Gua gum is preferred because it is inexpensive. These may be used alone or as a mixture of two or more galactomannans or derivatives thereof. In this case, it is sufficient that 50% or more of the total galactomannan is guar gum. Examples of galactomannans or derivatives thereof that can be mixed with guar gum include carboxymethyl galactomannan, hydroxypropyl guar gum, carboxymethyl hydroxypropyl galactomannan and locust bean gum, and one or more galactomannans selected from these groups or Derivatives of all galactomannans
After the addition in an amount of 0% by mass or less, the mixture may be subjected to the following step (b) of cross-linking with boron and a trivalent or higher polyvalent metal ion other than boron. If necessary, other than galactomannan such as carrageenan, agar, pectin, alginic acid, tarragant gum, xanthan gum, pullulan, gellan gum, tamarind seed gum, curdlan, gum arabic, glucomannan, starch, cellulose, chitin, chitosan, hyaluronic acid, etc. May be mixed.

The molecular weight of galactomannan is preferably 10,000 or more, more preferably 50,000 or more. If the molecular weight is 10,000 or less, it is not suitable because no gel is formed even when crosslinked with metal ions.

The swelling concentration of galactomannan and its derivatives in water must be 2% by mass to 8% by mass, more preferably 3% by mass to 6% by mass. If it is less than 2% by mass, the production cost is increased, and it cannot be industrially adopted. On the other hand, if the content exceeds 8% by mass, swelling becomes insufficient, and a problem such as a decrease in water absorption and a water absorption speed occurs.

The swelling temperature at this time is not particularly limited as long as galactomannan can swell and the molecular weight is not reduced by thermal decomposition.
C. to 100.degree. C., more preferably 20 to 80.degree.

The time required for swelling of galactomannan varies depending on the swelling concentration and swelling temperature of galactomannan, but it takes at least 30 minutes to prepare a uniform sol solution.

Next, the crosslinking agent used in the step (b) of the present invention needs to contain at least boron ions and trivalent or higher polyvalent metal ions other than boron. Examples of the trivalent or higher polyvalent metal ion other than boron include titanium, zirconium, aluminum, yttrium, and cerium. Titanium and zirconium are most preferable because of their low cost and high safety. The form of boron ions, titanium ions and zirconium ions is not particularly limited,
The compound is not particularly limited as long as it is a compound having two or more functional groups capable of reacting with the functional group of galactomannan, but is preferably a hydrophilic, more preferably a water-soluble metal salt.

Examples of the titanium salt include titanium diisopropoxide bisacetylaminate, titanium
Tetra-2-ethylhexoxide, titanium tetraisopropoxide, titanium di-n-butoxybistriethanolaminate, titanium isopropoxyoctylene glycolate, titanium diisopropoxybistriethanolaminate, Tyzor131
(Manufactured by DuPont), TyzorGBA (manufactured by DuPont), and titanium chloride.

Examples of the zirconium salt include zirconium ammonium carbonate, zirconium chloride, sodium zirconium lactate, zirconium oxyacetate, zirconium acetate, zirconium oxynitrate, zirconium sulfate,
Tetrabutoxy zirconium, zirconium monoacetylacetonate, zirconium normal butyrate,
Zirconium normal propylate is exemplified.

The concentration of metal ions used for crosslinking galactomannan sol is such that the absorption capacity after 1 minute is 20 times or more of its own weight, and the gel strength at 30 times absorption is 15000 × 10 5
May be in a range of dry matter can be produced with a ^-7 N / mm ² or more. For boron, galactomannan weight 1kg
10 to 2,000 mmol are preferable, and 50 to 1,
000 mmol is particularly preferred. Regarding trivalent or higher polyvalent metal ions other than boron, the galactomannan weight 1 k
About 1 to 300 mmol per g is preferable, and 10 to 1
50 mmol is particularly preferred.

The temperature at which a galactomannan crosslinked gel of galactomannan and boron or a trivalent or higher polyvalent metal ion other than boron is formed is not particularly limited, but is preferably 5 to 90 ° C. to promote the reaction. 20, 20
50 ° C. is more preferred. At 90 ° C. or higher, the molecular weight is reduced by thermal decomposition of galactomannan, and at 5 ° C. or lower, it does not swell.

The pH of the gel is determined by adding a crosslinking agent.
However, the final pH of the gel is preferably from 5 to 13, and more preferably from 7 to 10. Therefore, when the pH is out of this range, the pH of the gel may be adjusted by appropriately adding sodium hydroxide or hydrochloric acid. Particularly, since galactomannan is hydrolyzed in the presence of a strong acid to reduce the molecular weight, it is necessary to adjust the pH simultaneously with or immediately after the addition of the crosslinking agent when an acidic crosslinking agent solution is used. When such a cross-linking agent is used, it is preferable to add the galactomannan sol after cooling as much as possible in order to reduce the rate of the hydrolysis reaction. Cooling temperatures range from 1 to 10C. If the molecular weight of galactomannan is reduced, the texture of the gel after absorption is liable to deteriorate (slip occurs). Therefore, it is desirable to avoid as much as possible.

The hydrophilic organic solvent used for dehydration and crushing of the galactomannan crosslinked gel used in the step (c) of the present invention is not particularly limited as long as it does not affect the performance of the absorbent. Examples of such compounds include lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, and t-butyl alcohol; ketones such as acetone and methyl ethyl ketone. , Ethers such as dioxane and tetrahydrofuran, amides such as N, N-dimethylformamide, sulfoxides such as dimethylsulfoxide, and the like. However, methanol, ethanol, iso-propyl alcohol is preferred in view of cost and safety. Lower alcohols such as are preferred.

The amount of the hydrophilic organic solvent to be used is preferably 50 to 1000% by mass, more preferably 100 to 500% by mass with respect to 100% by mass of the water to be replaced in the galactomannan crosslinked gel. Particularly preferred. 5 used
When the amount is less than 0% by mass, the replacement of the water in the gel with the hydrophilic organic solvent is insufficient, and the absorption amount and the absorption rate may decrease. Further, if the amount exceeds 1000% by mass, the effect corresponding to the amount used cannot be obtained, and only the cost is increased, which is not industrially preferable.

As a mixing device for crushing the galactomannan crosslinked gel, a device having a large shearing force is preferable, but an ordinary mixer or kneader can be used. For example, a cylindrical mixer, a double-wall conical mixer, a high-speed stirring mixer, a V-shaped mixer, a ribbon mixer, a screw mixer, a fluidized-type rotary desk mixer, an air-flow mixer, Examples include a double-arm kneader, an internal mixer, a pulverizing kneader, a rotary mixer, and a screw extruder.

Next, the method for drying the gel crushed in the hydrophilic organic solvent is not particularly limited, and for example, room temperature drying, heating drying, freeze drying, reduced pressure drying, vacuum drying, etc. are used. . Heat drying at 30 to 100 ° C and vacuum drying are preferred.

FIG. 1 shows a scanning electron microscope (SEM) photograph of the absorbent obtained by the production method of the present invention. As shown in FIG. 1, the inside or the surface has irregularities and the surface area is large, so that a sufficient liquid conducting space for the transfer of the aqueous liquid into the absorbent material is secured. Therefore, the absorption speed can be improved by capillary action.

The absorbent of the present invention can be produced by the above-mentioned production method, and comprises a crosslinked gel in which galactomannan is crosslinked with boron and a trivalent or higher polyvalent metal ion other than boron. The water absorption of the 9.9 mass% sodium chloride aqueous solution is 20 times or more of its own weight one minute after the start of the water absorption experiment from the dry state of the absorbent, and is 0.9%.
Mass% aqueous sodium chloride solution from the dry state to its own weight
Gel strength in the state of double absorption is 15000 × 10 ⁻⁷
N / mm ² or more.

The measurement of the water absorption here was performed by the tea bag method. That is, 1 g of absorbent is put into a 250-mesh nylon tea bag, the tea bag is immersed in 1 L of 0.9% by mass aqueous sodium chloride solution for 1 minute, the tea bag is pulled up, and water is drained for 10 minutes. It was measured. The amount of absorbent absorbed is determined by taking the weight of the tea bag containing no absorbent absorbed in water for 1 minute as a blank, and calculating the weight of the absorbent before swelling from the weight of the tea bag containing the absorbent swollen absorbent. The value obtained by dividing the value obtained by subtracting the weight of the blank and the weight of the absorbent before swelling is the absorption amount (g).
/ G resin).

The measurement of the gel strength at the time of 30-fold absorption was 50
While absorbing the absorbent particles sieved to 0 to 1,000 μm, a 30-fold amount of a 0.9% by mass aqueous sodium chloride solution is absorbed, and Rheometric S of Scientific Inc. is absorbed.
The viscoelasticity G * was measured at 1 Hz and room temperature using R-5000, and the numerical value was used as the gel strength.

The absorbent of the present invention may be further subjected to a surface cross-linking treatment, if necessary.
A metal salt containing a trivalent or higher polyvalent metal ion such as zirconium may be mentioned, but a functional group capable of reacting with a functional group of galactomannan as long as the biodegradability, absorption capacity and gel strength are not reduced. There is no particular limitation as long as the compound has two or more groups. Preferred are hydrophilic compounds, more preferably water-soluble compounds, and polyhydric aldehydes such as glutaraldehyde and glyoxal; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, Polyvalent glycidyl compounds such as polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether; ethane dichloride;
Tetramethylene chlorobromide, dibromopropane,
Examples include polyvalent halides such as dibromobutane, and haloepoxy compounds such as epichlorohydrin and α-methylchlorohydrin.

The amount of the surface cross-linking agent to be used with respect to the absorbent depends on the combination of the absorbent and the surface cross-linking agent.
And more preferably within the range of 0.05 to 3% by mass. By using the surface cross-linking agent within the above range, the water absorbing properties for body fluids (aqueous liquids) such as urine, sweat, menstrual blood, etc. can be further improved. If the amount of the surface cross-linking agent used is less than 0.01% by mass, the cross-linking density in the vicinity of the surface of the absorbent cannot be increased. Also,
When the use amount of the surface cross-linking agent is more than 5% by mass, the surface cross-linking agent becomes excessive, which is uneconomical and may make it difficult to control the cross-linking density to an appropriate value.

The treatment method for treating the absorbent with a surface cross-linking agent is not particularly limited. For example, a method of mixing an absorbent and a surface cross-linking agent without a solvent, a method of dispersing an absorbent in a hydrophobic solvent such as cyclohexane or pentane, and a method of mixing a surface cross-linking agent, and a method of mixing a surface cross-linking agent in a hydrophilic solvent. After dissolving or dispersing, a method of spraying or dropping the solution or dispersion liquid onto the absorbing material and mixing the solution or the dispersion may be mentioned. The hydrophilic solvent is preferably water or a mixture of water and an organic solvent soluble in water.

The absorbent material of the present invention thus obtained may further contain, if necessary, a deodorant, a fragrance, various inorganic powders, pigments, dyes, antibacterial agents, foaming agents, hydrophilic short fibers, plasticizers, adhesives. Agents, surfactants, fertilizers, oxidizing agents, reducing agents, water, salts and the like may be added to impart various functions to the absorbent.

Examples of the inorganic powder include substances inert to aqueous liquids and the like, for example, fine particles of various inorganic compounds and fine particles of clay minerals. The inorganic powder preferably has an appropriate affinity for water and is insoluble or hardly soluble in water. Specifically, for example, metal oxides such as silicon dioxide and titanium oxide, silicic acids (salts) such as natural zeolite and synthetic zeolite, kaolin, talc, clay,
Bentonite and the like can be mentioned. Among them, silicon dioxide and silicic acid (salt) are more preferable, and silicon dioxide and silicic acid (salt) having an average particle diameter of 200 μm or less as measured by the Coulter counter method are more preferable.

The amount of the inorganic powder used in the absorbent of the present invention depends on the combination of the absorbent and the inorganic powder.
The amount may be in the range of 0.001 to 10% by mass, more preferably in the range of 0.01 to 5% by mass, based on 100% by mass of the absorbent. The method of mixing the absorbent and the inorganic powder is not particularly limited, and for example, a dry blending method, a wet mixing method, or the like can be employed, but a dry blending method is preferred.

The absorbent of the present invention is made into an absorbent article by, for example, compounding (combining) with a fibrous material such as pulp. Examples of the absorbent articles include sanitary materials (body fluid absorbent articles) such as disposable diapers, sanitary napkins, incontinence pads, wound protection materials, wound healing materials; absorbent articles such as urine for pets; water-retaining materials for construction materials and soil; Waterproof material, packing material,
Materials for civil engineering and construction such as gel sac; Food products such as drip absorbing material, freshness preserving material, and cold insulating material; Various industrial products such as oil-water separating material, anti-condensation material, solidifying material; Water retaining material such as plants and soil And the like, but are not particularly limited.

[0037]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples. The water absorption and the gel strength in the examples were measured as follows. The amount of water absorption was measured using the tea bag method.
This was performed using a 9% by mass aqueous solution of sodium chloride. That is, 1 g of absorbent is put into a 250-mesh nylon tea bag, the tea bag is immersed in 1 L of 0.9% by mass aqueous sodium chloride solution for 1 minute, the tea bag is pulled up, and water is drained for 10 minutes. It was measured.
The amount of water absorbed by the absorbent is defined as the weight of the absorbent bag before swelling, based on the weight of the tea bag containing the absorbent material swollen as the blank, with the weight of the tea bag containing no absorbent material soaked in water for 1 minute as a blank. The value obtained by dividing the value obtained by subtracting the weight of the blank and the blank by the weight of the absorbent before swelling was defined as the water absorption (g / g resin). In addition to the water absorption after one minute, the water absorption after 60 minutes was measured in the same manner.

The measurement of the gel strength at the time of 30 times water absorption is 50
While absorbing the absorbent particles sieved to 0 to 1,000 μm, a 30-fold amount of a 0.9% by mass aqueous sodium chloride solution was absorbed, and the mixture was subjected to absorption.
The viscoelastic G * was measured at room temperature and 1 Hz using R-5000, and the value was used as the gel strength.

Example 1 6 g of guar gum (manufactured by Sanei Pharmaceutical Trading Co., Ltd.) was added to 200 ml of pure water (solid content: 3% by mass) heated at 50 ° C. with stirring to dissolve and swell to prepare a sol solution. After swelling for 1 hour, 200 ml of the sol solution was mixed with a titanium diisopropoxy bistriethanol aminate (TEAT, manufactured by Mitsubishi Gas Chemical Company) solution having a final titanium content of 100 mmol / kg of guar gum weight and 0.5 M sodium tetraborate. The aqueous solutions were each added so that the final boron content was 500 mmol, and sufficiently crosslinked while being crushed by a blender. Next, the water contained in 200 ml of the gel was replaced with 200 ml of ethanol, and crushed with a blender. After filtration, the reaction product was washed twice with 50 ml of ethanol, suction filtered, and the solid content was dried with hot air at 50 ° C. for 6 hours to obtain an absorbent. As a result of measuring the water absorption and the gel strength of the obtained absorbent, as shown in Table 1, the water absorption after 1 minute was 24 g / g, and the water absorption after 60 minutes was 45 g / g.
g, gel strength at 30 times water absorption is 18000 × 10 ⁻⁷ N /
mm ² .

[0040]

[Table 1]

Further, the BET specific surface area of the obtained absorbent was measured. The specific surface area is 200 to 1000 with a JIS standard sieve.
After degassing the absorbent material classified into μm at 80 ° C. for 180 minutes,
BE using nitrogen gas as standard gas while cooling with liquid nitrogen
It measured by the specific surface area by T (Brunauer-Emmett-Teller) adsorption method. The BET specific surface area was 50.3 m ² / g.

Example 2 An absorbent was produced in the same manner as in Example 1 except that the guar gum solid content was changed to 6% by mass. The water absorption and gel strength of the obtained absorbent were measured and are shown in Table 1.

Example 3 In Example 1, the reaction product was washed twice with 50 ml of ethanol, suction-filtered, and instead of drying the solid content with hot air at 50 ° C. for 6 hours, the reaction product after filtration was washed with ethanol. An absorbent was produced in the same manner as in Example 1 except that the material was vacuum-dried at 80 ° C. for 3 hours while containing water. The water absorption and gel strength of the obtained absorbent were measured and are shown in Table 1.

Example 4 Example 1 was repeated except that zirconyl ammonium carbonate (Zircosol AC-7 manufactured by Nutex) was used instead of titanium diisopropoxy bistriethanolamine (TEAT manufactured by Mitsubishi Gas Chemical Company) as a titanium source. In the same manner as in Example 1, an absorbent was produced. The water absorption and the gel strength of the obtained absorbent were measured.
It was shown to.

Comparative Example 1 The procedure of Example 1 was repeated except that the crosslinked gel was cast without dewatering and pulverization in ethanol so that the gel had a thickness of 1 cm or less, and then dried with hot air at 50 ° C. for 6 hours. In the same manner as in Example 1, an absorbent was produced. The water absorption and gel strength of the obtained absorbent were measured and are shown in Table 1. The BET specific surface area measured in the same manner as in Example 1 was 0.1 m ² / g.

Comparative Example 2 An absorbent was produced in the same manner as in Example 1 except that the guar gum solid content was changed to 10% by mass. The water absorption and the gel strength of the obtained absorbent were measured.
It was shown to.

Comparative Example 3 An absorbent was produced in the same manner as in Example 1, except that the guar gum solid content concentration was changed to 0.5% by mass.
The water absorption and gel strength of the obtained absorbent were measured and are shown in Table 1.

As is evident from Table 1, the absorbent of the present invention has improved absorption performance, especially the absorption rate after one minute. Moreover, it turns out that the absorber of this invention has a large surface area.

[0049]

According to the present invention, an excellent water-absorbing material having a high absorption rate and a high gel strength can be produced using an inexpensive raw material, so that it can be used in the fields of sanitary materials such as sanitary goods and disposable diapers. The present invention can be suitably used for various applications requiring water absorption or water retention, such as a food field such as maintaining freshness and an industrial field such as dew condensation prevention and a cold insulator.

[Brief description of the drawings]

FIG. 1 is a scanning electron microscope (SEM) of the absorber of the present invention.
It is a photograph (magnification x 300).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B01J 20/26 C08K 3/38 4J002 20/30 A41B 13/02 D C08J 3/24 A61F 13/18 307A C08K 3/38 (72) Inventor Riko Wada 23 Uji Kozakura, Uji-city, Kyoto, Japan Unitika Central Research Laboratories (72) Inventor Takemasa Yoshino 23 Uji Kozakura, Uji-shi, Kyoto Unitika Central Research Laboratory F-term ( Reference) 3B029 BA18 4C003 AA11 AA24 HA04 4C098 AA09 CC02 DD05 DD17 DD30 4F070 AA01 AB01 AB13 GA03 GA10 4G066 AA02B AA03B AA56B AB06D AB23B AC01B AC11B AC35B AD15B AE05D AE06B BA12 FA26 FA38 FA38 FA38 FA38 GB00 GD03

Claims (3)

[Claims] 1. A gel in which galactomannan is crosslinked with boron and a trivalent or higher polyvalent metal ion other than boron. The water absorption of a 0.9% by mass aqueous sodium chloride solution is 20% of its own weight after one minute from the start of water absorption. And a gel strength of 15,000 × 10 ⁻⁷ N / m when a 0.9 mass% aqueous solution of sodium chloride absorbs 30 times its own weight.
m ² or more. 2. The trivalent or higher polyvalent metal ion other than boron ion is at least one metal ion selected from the group consisting of titanium ion, zirconium ion and yttrium ion. Absorbent. 3. Galactomannan is dissolved and swelled in water to form a galactomannan sol of 2 to 8% by mass, and then boron and a trivalent or higher polyvalent metal ion other than boron are added to form a crosslinked product. The method for producing an absorbent material according to claim 1, wherein the absorbent is formed, the crosslinked product is mixed with a hydrophilic organic solvent, crushed, and dried.