JP2001120992A - Water absorbing agent and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water absorbing agent having 80 times or larger capacity to absorb deionized water and an aqueous solution having not higher than 5 mass % sodium chloride and having a bio-degradable property and to provide a method for manufacturing the water absorbing agent. SOLUTION: This water absorbing agent consists of a crosslinked body obtained by crosslinking galactomannan with titanium ions and boron ions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a water-absorbing agent comprising a highly biodegradable polysaccharide, titanium and boron ions, which is suitably used for sanitary materials such as disposable diapers (disposable diapers), sanitary napkins and incontinence pads. The present invention relates to the manufacturing method.

[0002]

2. Description of the Related Art [Technical background of water-absorbent resin] A water-absorbent resin is a resin that can absorb water of several tens to several thousand times its own weight, and is used for sanitary products, disposable diapers, breast milk pads, disposable rags and the like. Supplies, dressings for wound protection, medical supplies such as medical underpads, cataplasms, pet seats, portable toilets, gel fragrances, gel deodorants, sweat-absorbent fibers, disposable warmers and other household items, shampoos, Set gels, toiletries such as moisturizers, water retention materials for agriculture and horticulture, life-extending agents for cut flowers, floral forms (fixed materials for cut flowers), nurseries for raising seedlings, hydroponics, vegetation sheets, seed tapes, fluids Agricultural and horticultural products such as agricultural sheets for preventing sowing and dew condensation, freshness-retaining materials for food trays, food packaging materials such as drip-absorbent sheets, cooling materials, and transport materials such as water-absorbent sheets for transporting fresh vegetables Building materials for preventing dew condensation, sealing materials for civil engineering and construction, anti-sludge agents for shielding methods, concrete admixtures, civil engineering and building materials such as gaskets and packing, sealing materials for electronic devices such as optical fibers, and waterproof materials for communication cables Used in a wide range of fields, including electrical equipment-related materials such as inkjet recording paper, coagulants for sludge, dewatering of gasoline and oils, water treatment agents such as water removers, printing pastes, water-swellable toys, and artificial snow. Have been. In addition, it is expected to be used for sustained-release fertilizers, sustained-release pesticides, sustained-release drugs, and the like by utilizing the sustained-release properties of the chemicals. Further, it is also expected to be used as a humidity control material utilizing its hydrophilicity, and as an antistatic agent utilizing its charge retention.

[Prior art relating to water-absorbing resin] Examples of the water-absorbing resin used in such applications include:
Crosslinked polyacrylic acid partially neutralized product (JP-A-55-8430)
No. 4, U.S. Pat. No. 4,625,001), a partially hydrolyzed starch-acrylonitrile copolymer (JP-A-46-439).
No. 95), a starch-acrylic acid graft copolymer (JP-A-51-125468), and a hydrolyzate of a vinyl acetate-acrylate copolymer (JP-A-52-14689).
No.), copolymerized crosslinked product of 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid (European patent 00681)
No. 89), a crosslinked product of a cationic monomer (US Pat.
No. 06717), a crosslinked isobutylene-maleic anhydride copolymer (US Pat. No. 4,389,513) and the like are known.

However, since these water-absorbent resin compositions do not have degradability, disposal after use is a problem. At present, these water-absorbent resins are incinerated at the time of disposal and landfilled.However, in the incinerator method, in addition to damage to furnace materials due to heat generated during incineration, It has been pointed out that it causes global warming and acid rain. Furthermore, when incinerating used paper diapers with a high water content, the combustion temperature inside the furnace decreases when charged into an incinerator, resulting in a combustion atmosphere in which furnace materials are likely to deteriorate and dioxins are generated. The burden on the equipment increases, and an exhaust gas treatment equipment with higher performance is required. In the landfill method, the plastic has a problem that the volume is bulky, the ground does not stabilize because it does not rot, and a major problem is that there is no longer a place suitable for landfill.

That is, these resins are poorly decomposable and exist semipermanently in water and soil, which is a very serious problem in view of environmental conservation in waste treatment. For example, in the case of disposable resins represented by sanitary materials such as disposable diapers and sanitary articles, recycling the resin requires a great deal of cost, and the amount of incineration is large, so that the burden on the global environment is great. When a crosslinked polyacrylic acid resin is used as a water retention material for agriculture and horticulture, Ca ²⁺
It is reported that the complex forms a complex with polyvalent ions such as those described above to form an insoluble layer (Matsumoto et al., Polymer, 42
Vol., August issue, 1993). However, although such layers are said to have low toxicity per se, they are completely absent in nature, and the effects on ecosystems of long-term accumulation of these resins in soil are unknown. , Need to be thoroughly examined and its use requires a careful attitude. Similarly, in the case of a nonionic resin, a complex is not formed, but the nondecomposable resin may accumulate in soil due to its nondegradability, and its effect on the natural world is doubtful. Furthermore, these polymerization resins use monomers that are highly toxic to human skin, etc., and many studies have been made to remove them from products after polymerization. It is difficult. In particular, it is expected to be more difficult in production on an industrial scale.

[Technical background of water-absorbing resin having biodegradability] On the other hand, biodegradable polymers have recently attracted attention as "earth-friendly materials", and it has been proposed to use this as a water-absorbing resin. ing. Examples of the biodegradable water-absorbing resin used for such applications include, for example, a polyethylene oxide crosslinked product (JP-A-6-15779).
No. 5, etc.), cross-linked polyvinyl alcohol, cross-linked carboxymethyl cellulose (US Pat. No. 4,650,716),
Alginic acid crosslinked products, starch crosslinked products, polyamino acid crosslinked products, and the like are known. Among these, crosslinked polyethylene oxide and crosslinked polyvinyl alcohol have low water absorption, and are particularly used as materials for products requiring high water absorption such as freshness preserving material for fresh food, sanitary products, disposable diapers, disposable rags, and paper towels. If not useful. In addition, since these compounds can be biodegraded only by special bacteria, biodegradability is slow under general conditions,
Or they do not decompose at all. When the molecular weight is further increased, the decomposability extremely decreases. In addition, crosslinked saccharides such as crosslinked carboxymethylcellulose, crosslinked alginic acid, and crosslinked starch have many strong hydrogen bonds in their molecules, and therefore have strong interactions between molecules and between polymers. It cannot be opened widely and its water absorption capacity is not high.

[0007] Currently, water-absorbent resins commercially available are mainly of polyacrylic acid type having no biodegradability, and the water-absorbing agent has a very high deionized water-absorbing ability of several hundred to 1,000 times. I have. However, the water-absorbing capacity of these water-absorbing agents, such as sodium chloride aqueous solution, for example, physiological saline (0.9% by mass sodium chloride aqueous solution) is only about 50 to 75 g / g when quoted from numerical values in catalogs and the like. Most have only about 1/5 to 1/10. Furthermore, it has only about 20 to 25 g / g water absorption capacity for an aqueous solution having a high sodium chloride concentration, for example, seawater.

As a water absorbing agent comprising a polysaccharide and a polyvalent metal ion, a water absorbing agent comprising galactomannan and titanium or zirconium (US Pat. No. 5,532,350) or a polysaccharide containing cis-1,2-diol and sodium borate is used. There is a water absorbing agent (US Pat. No. 4,334,461).

[0009]

However, US patents
In No. 5532350, as an example, the carboxymethylated galactomannan is crosslinked with titanium or zirconium or both ions to reduce the amount of physiological saline absorbed by its own weight of 30 to 50.
Although it is disclosed that it has the ability to absorb water about twice as much, it does not show any water absorbing effect of a water absorbing agent comprising unmodified galactomannan and titanium and boron. According to the patent, a water-absorbing agent composed of carboxymethylated galactomannan and titanium has an excellent ability to absorb physiological saline, but has a low gel strength. On the other hand, it is described that a water absorbing agent comprising carboxymethylated galactomannan and zirconium has a high gel strength but a low water absorbing ability. For this reason, titanium and zirconium are crosslinked with carboxylmethylhydroxypropylated galactomannan to disclose a water-absorbing agent excellent in gel strength and water-absorbing ability, but the water-absorbing ability is as high as 38 g / g in physiological saline. There was no problem for practical use.

In US Pat. No. 4,334,461, a water-absorbing agent composed of galactomannan and sodium borate is prepared to measure the water-absorbing ability of a physiological saline solution. However, no effect is disclosed regarding the water-absorbing agent obtained by further crosslinking titanium. Not. The inventors also prepared a water-absorbing agent composed of galactomannan and boron based on the examples and measured the water-absorbing ability.Although the physiological saline had a water-absorbing ability of 50 to 70 times, the gel strength was very weak, Gel leakage occurred from the nonwoven fabric or the nylon bag, which was not practical. Furthermore, although these patents describe the ability to absorb physiological saline (0.9% by mass sodium chloride water), they disclose the ability to absorb water.
The sodium chloride aqueous solution having a concentration of 9% by mass or more has not been studied at all.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a water-absorbing agent having biodegradability and excellent water-absorbing ability of an aqueous sodium chloride solution, and a method for producing the same. It is.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, the present inventors have found that galactomannan is formed by drying a gel crosslinked with titanium ions and boron ions. The water-absorbing agent has a higher sodium chloride aqueous solution-absorbing ability than the water-absorbing agent cross-linked with only galactomannan and boron or titanium alone, and the gel strength is improved.
The inventors have found that they have a high water-absorbing ability that is almost the same as that of deionized water with respect to a 5% by mass aqueous sodium chloride solution, and have completed the present invention.

That is, the first aspect of the present invention is a summary, and the second aspect of the present invention is a summary.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, the first water absorbing agent of the present invention will be described. The water-absorbing agent of the present invention comprises a crosslinked product in which galactomannan is crosslinked by titanium ions and boron ions.
The origin of galactomannan used in the present invention is not particularly limited, and includes locust bean gum and guar gum, with guar gum being preferred. In addition to galactomannan, derivatives of galactomannan, such as carboxymethyl galactomannan, carboxymethyl hydroxypropyl galactomannan, and soluble polysaccharides other than galactomannan, such as carboxymethyl starch, carboxymethyl cellulose, glucomannan,
It is preferable to include starch, carboxyethylcellulose, xanthan gum, pullulan, dextran, curdlan, carrageenan, gum arabic, chitosan and the like because gel strength is improved. In this case, the concentration of these is 50% by weight of galactomannan.
The following range is preferable, but 10% by weight or less is preferable in order not to cause a decrease in water absorption capacity.

In the present invention, titanium ions and boron ions function as a crosslinking agent. As the ratio of titanium ions to boron ions, titanium: boron = 0.1: 99.
9-99.9: 0.1 is preferable, and titanium: boron =
1: 9 to 9: 1 is more preferred. Also, other crosslinking agents,
For example, calcium, zinc, strontium, salts of polyvalent metals such as magnesium, glutaraldehyde, aldehyde compounds such as glyoxal, ethylenediamine,
Amine compounds such as polyamide resins, aziridine compounds such as 2,2-bishydroxymethylbutanol tri [3- (1-aziridine)] propionic acid, isocyanates such as tolylene diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate It may contain a naat compound, polyhydric alcohols such as glycerol, propylene glycol and ethylene glycol, and epoxy compounds such as epichlorohydrin, ethylene glycol diglycidyl ether and diethylene glycol diglycidyl ether.

The water-absorbing agent of the present invention has the above structure, and is capable of absorbing a 5% by mass or less aqueous sodium chloride solution at least 80 times its own weight.
Here, the aqueous sodium chloride solution refers not only to an aqueous solution in which only sodium chloride is dissolved, but also to an aqueous solution in which another electrolyte (such as potassium chloride or magnesium sulfate) is dissolved together with sodium chloride.

Next, a method for producing the second water absorbing agent of the present invention will be described. In the present invention, it is necessary to dissolve the above galactomannan in water and swell.
The dissolution concentration is not particularly limited as long as galactomannan can be uniformly dissolved and swelled in water and a gel can be formed at the time of crosslinking, but is preferably 0.1% by mass or more.
10% by mass, more preferably 0.5% by mass to 5% by mass
It is. The dissolution temperature at this time is not particularly limited, but is preferably 15 ° C to 90 ° C, and more preferably 40 ° C to 70 ° C. The time required for dissolution and swelling varies depending on the dissolution concentration and dissolution temperature of galactomannan, but at least 30 minutes or more is required.

At this time, for the purpose of improving the water absorption rate and the gel strength, salt, colloidal silica, white carbon,
An inorganic compound such as ultrafine silica or titanium oxide powder or an organic compound such as a chelating agent may be added. In addition, plasticizers, oxidizers, antioxidants, reducing agents, ultraviolet absorbers,
An antibacterial agent, a bactericide, a fungicide, a fertilizer, a fragrance, a deodorant, a pigment, and the like may be mixed. In some cases, a crosslinking retarder may be added. Various hydrophilic compounds can be used as the plasticizer used in the present invention. The purpose is to impart flexibility to the water absorbing agent. The plasticizer used in the present invention is not particularly limited, but water,
Alcohols, carboxylic acids, sulfonic acids, glycols,
Water-soluble synthetic polymers, amino alcohols, monosaccharides, disaccharides, trisaccharides, 20 kinds of essential amino acids, amino acids and amino acid derivatives, nucleic acids and their derivatives, phospholipids, vitamins and coenzymes. Of these, compounds having abundant hydrophilic groups in the molecule are preferable because they can be uniformly mixed. That is, sorbitol, pentaerythritol, iduronic acid, galactal acid, α-galacturonic acid,
Glucaric acid, β-glucuronic acid, gluconic acid, guluronic acid, 2-deoxygluconic acid, mannuronic acid-6,3-
Lactone, α-galactosamine hydrochloride, α-mannosamine hydrochloride, muramic acid, alginic acid, chondroitin-
4-sulfate, chondroitin-6-sulfate, hyaluronic acid, pekunanoic acid, chitosan, chitosan-succinic acid modified product, cationized starch, carboxymethylcellulose, hydroxyethylcellulose, cationized cellulose are preferable, and sorbitol, pentaerythritol,
Gluconic acid, α-galactosamine hydrochloride, chondroitin-4-sulfate, chondroitin-6-sulfate, alginic acid, hyaluronic acid, chitosan, chitosan-succinic acid modified product, cationized starch, carboxymethyl cellulose, and cationized cellulose are particularly preferred. . If necessary, the plasticizer used in the present invention may be used as a mixture with two or more other plasticizers. The use amount of these plasticizers is not particularly limited, but is 0.1 to 70% by mass based on the water absorbing agent.
Is preferable, and 0.1 to 30% by mass is more preferable.

In the present invention, it is necessary to add titanium ions and boron ions to crosslink galactomannan. Examples of the form of titanium ion or boron ion to be added include chloride, sulfate, carbonate, acetate, formate, lactate, alkoxide, and the like. For boron, it is sodium borate. The addition amount is 0.01 mM to 100 mM,
More preferably, it is 0.1 mM to 50 mM. The addition of titanium ions and boron ions may be added at the same time, but the titanium aqueous solution is strongly acidic when titanium is chloride or the like, and boron precipitates when it is a basic aqueous solution,
It is preferable to add them separately. As the order of addition, it is preferable that the gel does not become strongly acidic, so that it is sometimes preferable to add boron first. When adding the strongly acidic titanium first, the pH of the sol may be made basic with NaOH before adding titanium, and then boron may be added.
The cross-linking agent used in the present invention needs to contain at least one or more titanium and boron ions, but other cross-linking agents as described above may be added as long as the water-absorbing ability is not reduced. .

The temperature for forming the crosslinked product is as follows:
Although not particularly limited, 5 to 9 may be used to promote the reaction.
0 ° C is preferable, and 30 to 60 ° C is more preferable.

In the present invention, it is necessary to dry the crosslinked product (gel) obtained above. The method of drying is not limited to any drying method as long as it does not decrease the water absorption capacity after drying, for example, room temperature drying, heat drying or freeze drying, drying under reduced pressure,
In addition to methods such as vacuum drying, the water in the gel
Hygroscopicity, such as up to 5 monohydric alcohols (methanol, ethanol, isopropanol, etc.) or 3 to 6 crotons (e.g., acetone) or a mixture thereof;
Although there is a method of drying after replacing with a volatile anhydrous hydrophilic organic solvent, heating drying at 30 to 50 ° C. or freeze drying is preferable.

The shape of the water-absorbing agent after drying is not particularly limited, but may be various shapes according to the purpose of use. For example, granules, sheets, powders,
Fragments, flakes, rods, lines, etc. These shapes may be formed after drying, or at the time of drying, the gel may be placed in a forming device having such a shape and dried.

The thus obtained water-absorbing agent of the present invention may further contain, if necessary, a deodorant, a fragrance, various inorganic powders, a foaming agent, a pigment, a dye, an antibacterial agent, a hydrophilic short fiber, a plasticizer, an adhesive. An agent, a surfactant, a fertilizer, an oxidizing agent, a reducing agent, water, salts, and the like may be added to thereby impart various functions to the water absorbing agent. 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. Specific examples include metal oxides such as silicon dioxide and titanium oxide, silicic acids (salts) such as natural zeolites and synthetic zeolites, kaolin, talc, clay, bentonite and the like. 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 water-absorbing agent of the present invention depends on the combination of the water-absorbing agent and the inorganic powder, but is preferably in the range of 0.001 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the water-absorbing agent.
The amount may be in the range of 01 to 5 parts by mass. The method of mixing the water-absorbing agent and the inorganic powder is not particularly limited. For example, a dry blending method, a wet mixing method, or the like can be used, but a dry blending method is preferably used.

The water-absorbing agent 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, etc .; absorbent articles such as urine for pets; building materials and water retention materials for 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. In addition, for example, a disposable diaper includes a back sheet (back surface material) made of a liquid-impermeable material, a core layer containing the water-absorbent resin of the present invention, and a top sheet (surface material) made of a liquid-permeable material. They are laminated in this order and fixed to each other, and are formed by attaching gathers (elastic portions), so-called tape fasteners, and the like to the laminate. Further, the disposable diaper also includes pants with a disposable diaper used when disciplining urination and defecation for infants.

In particular, the water-absorbing agent of the present invention has a stable water-absorbing ability which is hardly affected by the sodium chloride concentration with respect to a high-concentration aqueous solution of sodium chloride. It is useful to use it for dry batteries and the like.

[0026]

The present invention will be described more specifically with reference to the following examples. Reference Example 1 [Measurement of absorption amount] The absorption amount was measured by a tea bag method using deionized water and a 0.9% by weight aqueous solution of sodium chloride (sodium chloride), 5% by mass.
The test was performed on a saline (sodium chloride) aqueous solution and artificial urine (1.94% by mass urea, 0.8% by mass sodium chloride, 840 ppm calcium chloride, and 2050 ppm magnesium sulfate). That is, 1 g of a water-absorbing agent is put into a 250-mesh nylon tea bag, and the tea bag is immersed in 1 L of deionized water, 0.9% by mass saline, 5% by mass saline, and artificial urine for 3 hours, and the tea bag is pulled up. , 1
After draining for 0 minutes, the weight was measured. The amount of water absorbed by the water-absorbing agent before the swelling is calculated from the weight of the tea bag containing the water-absorbing agent swollen by absorbing the water, taking the weight of the tea bag without the water-absorbing agent soaked in water for 3 hours 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 water absorbing agent before swelling was defined as the water absorption (g / g resin).

Example 1 2 g of guar gum (PF-20, manufactured by Sansei Co., Ltd.) was added to 200 ml of pure water heated to 50 ° C. with stirring to dissolve and swell to prepare a sol solution. After swelling for 1 hour, the sol liquid 200m
To the sol solution was added 0.85 ml of a TyzorTE (titanium IV triethanolaminate isopropoxide) solution (manufactured by DuPont; titanium content of the stock solution was 15% by mass) five-fold diluted with isopropanol to 200 ml of the sol solution (3 mM as titanium). ) And gelled. Next, 2 ml of a 5% by mass aqueous solution of sodium tetraborate heptahydrate was added to the gel.
(5.3 mM as boron) and sufficiently crosslinked while crushing and mixing with a blender. The pH of this gel is 9.
It was one. This gel was freeze-dried, and the obtained dried product was crushed to 1 mm or less with a file under a stream of nitrogen to obtain a water-absorbing agent of the present invention. The water absorption and the water absorption rate of the obtained fragments were measured. As a result, the water absorption of deionized water was 102 g / g, and the water absorption of 0.9 wt% saline was 98 g / g.
g, 5% by mass saline water absorption was 102 g / g, artificial urine water absorption was 95 g / g, and there was no gel leakage from the bag.

Example 2 A 1% by weight guar gum sol solution was prepared in the same manner as in Example 1, and a Tyzor 131 solution (Du
Pont (titanium content: 6% by mass) was diluted 5-fold with deionized water, and 0.6 ml of a solution was added (0.9 mM as titanium) to gel. Next, 2 ml (5.3 mM as boron) of a 5% by mass aqueous solution of sodium tetraborate heptahydrate was added to the gel, and the gel was sufficiently crosslinked by crushing and mixing with a blender. The pH of this gel was 9.1. This gel was lyophilized and crushed in the same manner as in Example 1 to obtain a water absorbing agent. The water absorption of the obtained fragment was measured. As a result, the water absorption of deionized water was 120 g / g and the water absorption was 0.1 g.
The 9 mass% saline water absorption was 124 g / g, the 5 mass% saline water absorption was 120 g / g, and the artificial urine water absorption was 115 g / g, and there was no gel leakage from the bag.

Example 3 A 1% by weight guar gum sol solution was prepared in the same manner as in Example 1, and 200 ml of the sol solution was used in a TyzorAA (titanium IV diisopropoxide acetylacetonate) solution (manufactured by DuPont). 0.4 ml of a solution obtained by diluting 10% by mass with isopropanol was added (0.9 mM as titanium) to gel. Next, 2 ml (5.3 mM as boron) of a 5% by mass aqueous solution of sodium tetraborate heptahydrate was added to the gel, and the gel was sufficiently crosslinked by crushing and mixing with a blender. The pH of this gel was 9.0. This gel was lyophilized and crushed to obtain a water absorbing agent. The water absorption of the obtained fragment was measured. As a result, the water absorption of deionized water was 112 g / g, 0.9 g.
The water absorption of mass% saline was 115 g / g, the water absorption of 5 mass% saline was 109 g / g, and the water absorption of artificial urine was 101 g / g, and there was no gel leakage from the bag.

Example 4 A 1% by mass guar gum sol solution was prepared in the same manner as in Example 1, and a 17% titanium tetrachloride solution (manufactured by Wako Pure Chemical Industries, Ltd.) was diluted 5-fold with isopropanol to 200 ml of the sol solution. 175 ml was added (1 mM as titanium) and gelled. Next, 2 ml of a 5% by mass aqueous solution of sodium tetraborate heptahydrate (5.3 m as boron) was added to the gel.
M) and sufficiently crosslinked while crushing and mixing with a blender. The pH of this gel was 7.7. The gel pH was adjusted to 8. while adding 1N sodium hydroxide solution to the gel.
After adjusting to 3, the mixture was freeze-dried and crushed to obtain a water-absorbing agent. The water absorption of the obtained fragment was measured. As a result, the water absorption of deionized water was 86 g / g, the water absorption of 0.9% by mass saline was 91 g / g, and the water absorption of 5% by mass saline was 83 g / g. The artificial urine absorption was 85 g / g, and there was no gel leakage from the bag.

Comparative Example 1 A 1% by mass guar gum sol solution was prepared in the same manner as in Example 1, and 200 ml of the sol solution was TyzorAA (titanium IV diisopropoxide acetylacetonate) solution (manufactured by DuPont). 0.4 ml of a solution obtained by diluting 10% by mass with isopropanol was added (0.9 mM as titanium) to gel. The pH of this gel was 7.5. This gel was lyophilized and crushed to obtain a water absorbing agent. The water absorption of the obtained fragment was measured. As a result, the water absorption of deionized water was 47 g / g and the water absorption was 0.4 g / g.
The 9 mass% saline water absorption was 42 g / g, the 5 mass% saline water absorption was 45 g / g, and the artificial urine water absorption was 50 g / g, but a large amount of gel leaked from the bag.

Comparative Example 2 A 1% by mass guar gum sol solution was prepared in the same manner as in Example 1, and 2 ml of a 5% by mass aqueous solution of sodium tetraborate heptahydrate (5.3 m as boron) was added to 200 ml of the sol solution.
M) and sufficiently crosslinked while crushing and mixing with a blender. The pH of this gel was 8.6. This gel was lyophilized and crushed to obtain a water absorbing agent. The water absorption of the obtained fragment was measured, and as a result, the water absorption of deionized water was 75%.
g / g, water absorption of 0.9% by mass saline is 76 g / g, water absorption of 5% by mass saline is 74 g / g, and water absorption of artificial urine is 75 g.
/ G, but a large amount of gel was leaking from the bag.

Comparative Example 3 In the same manner as in Example 1, 1% by mass of carboxymethylhydroxypropyl guar gum (manufactured by Sanseki: Jaguar 860)
0) Prepare a sol solution and add Tyz to 200 ml of the sol solution.
orAA (titanium IV diisopropoxide acetylacetonate) solution (manufactured by DuPont): The titanium content of the stock solution is 1
0 mass%) diluted 5-fold with isopropanol
0.4 ml was added (0.9 mM as titanium) to gel. Next, 2 ml of a 5% by mass aqueous solution of sodium tetraborate heptahydrate (5.3 m as boron) was added to the gel.
M) and sufficiently crosslinked while crushing and mixing with a blender. The pH of this gel was 9.1. This gel was lyophilized and crushed to obtain a water absorbing agent. The water absorption of the obtained fragment was measured, and as a result, the water absorption of deionized water was 1
50 g / g, water absorption of 0.9 mass% saline is 51 g / g,
5% by mass saline water absorption is 38 g / g, artificial urine water absorption is 5
It was 5 g / g and there was no gel leakage from the bag.

Comparative Example 4 A sol solution of 1% by weight of carboxymethyl guar gum (manufactured by Sansei Corporation: Mayploid Gum HT-8) was prepared in the same manner as in Example 1, and TyzorAA (titanium IV dilute) was added to 200 ml of the sol solution. An isopropoxide acetylacetonate) solution (manufactured by DuPont; the titanium content of the stock solution was 10% by mass) was added to 0.4 ml of a 5-fold diluted solution with isopropanol (0.9 mM as titanium) to gel. Next, 2 ml (5.3 mM as boron) of a 5% by mass aqueous solution of sodium tetraborate heptahydrate was added to the gel, and the gel was sufficiently crosslinked by crushing and mixing with a blender. The pH of this gel was 9.1. This gel was lyophilized and crushed to obtain a water absorbing agent. The water absorption of the obtained fragment was measured. As a result, the water absorption of deionized water was 45 g / g, the water absorption of 0.9% by mass saline was 46 g / g, and the water absorption of 5% by mass saline was 40 g / g. The artificial urine absorption was 44 g / g, and there was no gel leakage from the bag.

Comparative Example 5 A 1% by weight guar gum sol solution was prepared in the same manner as in Example 1, and 0.4 ml of 117 g / L zirconium tetrachloride was added to 200 ml of the sol solution (1 m as zirconium).
M) and gelled. Next, 2 ml (5.3 mM as boron) of a 5% by mass aqueous solution of sodium tetraborate heptahydrate was added to the gel, and the gel was sufficiently crosslinked by crushing and mixing with a blender. The pH of this gel was 4.5.
This gel was lyophilized and crushed to obtain a water absorbing agent. The water absorption of the obtained fragment was measured. As a result, the water absorption of deionized water was 47 g / g, and the water absorption of 0.9% by mass saline was 45 g / g.
g / g, water absorption of 5% by mass saline was 42 g / g, and artificial urine absorption was 43 g / g, and there was no gel leakage from the bag.

Comparative Example 6 A guar gum sol solution was prepared in the same manner as in Comparative Example 5, a yttrium chloride solution was added so that the yttrium concentration became 1 mM, and then a sodium borate solution was added so that the yttrium concentration became 5.3 mM, thereby causing gelation. After freeze-drying and crushing, a water-absorbing agent was obtained. As a result of measuring the absorption of the obtained water-absorbing agent, the absorption of deionized water was 70 g / g, the absorption of 0.9% by mass saline was 65 g / g, and the absorption of 5% by mass saline was 60 g / g.
g, artificial urine absorption was 72 g / g, and no gel leaked from the bag.

Comparative Example 7 A guar gum sol was prepared in the same manner as in Comparative Example 5, and a calcium chloride solution was added so that the calcium concentration was 1 mM.
Next, a sodium borate solution was added to a concentration of 5.3 mM to cause gelation, followed by freeze-drying and crushing to obtain a water-absorbing agent.
As a result of measuring the water absorption of the obtained water absorbing agent, the water absorption of deionized water was 30 g / g, the water absorption of 0.9% by mass saline was 25 g / g, and the water absorption of 5% by mass saline was 28 g / g. The artificial urine water absorption was 30 g / g, and a large amount of gel leaked from the bag.

As can be seen in Examples 1 to 4, the water-absorbing agent comprising guar gum, boron and titanium, which is the water-absorbing agent of the present invention, contains 80 g / g or more of deionized water, 0.9% by mass saline,
5% by mass saline and artificial urine can be stably absorbed. Further, as can be seen from a comparison between Example 1 and Comparative Examples 1 and 2, the water absorbing ability of the water absorbing agent consisting of guar gum and titanium and guar gum and boron alone is as low as 80 g / g or less. The gel was low in gel strength such that leakage of water occurred, but the water absorbing agent of the present invention was 80 g / g.
It had the above-mentioned water absorbing ability and an appropriate gel strength such that gel leakage from the bag after water absorption did not occur. Further, in Comparative Examples 3 and 4, when carboxymethylated guar gum was prepared with a water absorbing agent crosslinked with boron and titanium,
The water-absorbing agent of Comparative Example 3 showed a high water-absorbing capacity of 150 g / g in deionized water, but 51 g / g in 0.9% by mass saline.
And it was not high water absorption. Comparative Examples 5 to 7
As apparent from the above, the metal ion added to guar gum and boron must be titanium, and it is clear that zirconium, calcium, and yttrium do not reduce the water absorption or improve the gel strength.

[0039]

According to the present invention, a water-absorbing agent having a biodegradability of more than 80 times that of deionized water and an aqueous solution of sodium chloride of 5% by mass or less can be easily produced using inexpensive raw materials. Since it can be easily disassembled at the time of disposal, it can be used as sanitary articles such as disposable diapers and sanitary articles, civil engineering and building materials, and coagulants. Further, the gel strength after water absorption is increased to such an extent that the gel does not leak from the nonwoven fabric or the nylon bag, and the water-absorbing agent is hardly affected by the sodium chloride concentration of the liquid to be absorbed, and has a stable water-absorbing ability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) A61F 5/44 C08L 1:02 5/443 A41B 13/02 D 13/15 A61F 13/18 307B C08L 1: 02 F term (reference) 3B029 BA17 4C003 AA24 4C098 AA09 CD05 DD05 DD29 DD30 4F070 AA02 AB13 AC14 AC15 AC16 AC18 AC20 AC36 AC40 AE08 GA08 GB02 GB06 GB09 GC02 GC03 GC04 4G066 AC02A AC35B AE06B AE20 DA13 FA13 DA07 FA36

Claims (3)

[Claims] 1. A water-absorbing agent comprising a crosslinked product of galactomannan crosslinked by titanium ions and boron ions. 2. The water-absorbing agent according to claim 1, which has an ability to absorb deionized water and a 5% by mass or less aqueous sodium chloride solution at least 80 times its own weight. 3. The method according to claim 1, wherein after dissolving galactomannan in water and swelling, galactomannan is cross-linked by adding titanium ions and boron ions, and the obtained gel is dried. A method for producing a water absorbing agent, characterized by obtaining a water absorbing agent.