JP2001224959A - Method for manufacturing water-absorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a water-absorbent from polysaccharide. SOLUTION: Particles or powder of dried polysaccharide are added into the solution containing multivalent metal ions to form surface-cross-linked polysaccharide particles by cross-linking the vicinities of the surfaces of the particles or powder of the polysaccharide. The obtained particles are swelled in the solution of a cross-linking agent to form a cross-linked gel body, which is then dried to obtain the objective water-absorbent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a water-absorbing polymer composition suitably used for sanitary materials such as disposable diapers (disposable diapers), sanitary napkins and incontinence pads. More specifically, the present invention relates to a method for easily producing a water absorbing agent comprising a polysaccharide having high biodegradability and a polyvalent metal ion. More specifically, the present invention relates to a method for producing a water-absorbing agent comprising a polysaccharide and a polyvalent metal ion which is excellent in simplicity in the production process and has few troubles.

[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.

[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.

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).

[0008]

However, in the method for producing a water-absorbing agent comprising these polysaccharides and polyvalent metal ions, the polysaccharide powder is dissolved in water, and the swollen sol is added with the polyvalent metal ions to crosslink. A gel was prepared, dried and then crushed. In order to obtain a water-absorbing agent having a high gel strength that does not leak from a paper diaper or the like with such a method, it is necessary to produce a somewhat strong gel crosslinked body, and the strong gel body is sent by a pump or the like. Can not do it. For this reason, continuous production is impossible, and the method of adding the crosslinking agent to make the crosslinking uniform is complicated,
It is not an economically useful method because an expensive stirring device is required or a long time is required for uniform crosslinking.

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.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that dried polysaccharide particles are added to a solution containing polyvalent metal ions and crosslinked to form surface crosslinked polysaccharide particles. The method of producing a water-absorbing agent, in which the particles are sufficiently swollen in a cross-linking agent solution to form a cross-linked gel and then dried, is based on the conventional method in which a polysaccharide is swollen and then cross-linked with a polyvalent metal ion to form a cross-linked gel. It is simpler and superior in the manufacturing process compared to the method of manufacturing a water absorbing agent that forms and dries, has less trouble and is easy to maintain, and the water absorbing agent obtained by this method is equivalent to the water absorbing agent obtained by the conventional method The present invention has been found to have the performance described above.

That is, the first aspect of the present invention is to add a dried polysaccharide particle or powder to a solution containing a polyvalent metal ion and to crosslink the vicinity of the surface of the polysaccharide particle or powder to form a surface crosslinked polysaccharide particle. And a method for producing a water-absorbing agent, which comprises swelling the particles in a crosslinking agent solution to form a crosslinked gel, and then drying. Further, the second of the present invention is to add the dried polysaccharide particles or powder to a solution containing polyvalent metal ions, to form a cross-linked surface polysaccharide particles by cross-linking near the surface of the polysaccharide particles or powder, The particles are swollen in a cross-linking agent solution to form a cross-linked gel body, and then the cross-linked gel body is crushed by a mechanical method in a hydrophilic solvent. A gist of the present invention is a method for producing a water-absorbing agent, comprising crosslinking with a polyvalent metal ion, collecting the gel particles, and drying the gel particles.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The production method of the present invention comprises: (a) supplying a soluble polysaccharide into a cross-linking agent bath containing one or more polyvalent metal ions to cross-link the vicinity of the surface of the polysaccharide powder; The polysaccharide surface crosslinked particles are sufficiently swelled in a suspension containing surface crosslinked particles and a crosslinking agent to form a crosslinked gel body,
(C) drying the crosslinked gel body.

The soluble polysaccharide used in the step (a) is glucomannan, galactomannan, starch, sodium alginate, cellulose, xanthan gum, pullulan, dextran, curdlan, carrageenan, gum arabic, chitosan and derivatives thereof. It is not particularly limited as long as it can be cross-linked with a polyvalent metal and the cross-linked dried product has the ability to absorb water. For example, galactomannan (locust bean gum, guar gum), carboxymethyl galactomannan, carboxymethyl hydroxypropyl galactomannan or carboxymethyl starch, carboxymethyl cellulose, glucomannan, starch, carboxyethyl cellulose, xanthan gum, pullulan, dextran, curdlan, carrageenan, Examples include one or more soluble polysaccharides selected from the group of gum arabic, chitosan, sodium alginate and the like, preferably galactomannan or a derivative thereof, and more preferably galactomannan.

In the method for producing a water-absorbing agent according to the present invention, a polysaccharide is added to a crosslinking agent liquid containing one or more polyvalent metal ions without swelling and mixed as a powder. For the purpose of improving the water absorption rate and the gel strength, an inorganic compound such as salt, colloidal silica, white carbon, ultrafine silica, titanium oxide powder, or an organic compound such as a chelating agent may be added. In addition, plasticizers, oxidizers, antioxidants, reducing agents, ultraviolet absorbers, antibacterial agents, bactericides, fungicides, fertilizers,
Perfumes, deodorants, pigments, and the like may be mixed. In some cases, a crosslinking retarder may be added.

As the plasticizer used in the present invention, various hydrophilic compounds can be used. The purpose is to impart flexibility to the water absorbing agent. The plasticizer used in the present invention is not particularly limited, but may be water, alcohol, carboxylic acid, sulfonic acid, glycols, water-soluble synthetic polymer, amino alcohol, monosaccharide, disaccharide, trisaccharide, 20
Types 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, galactic 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, carboxymethyl cellulose, hydroxyethyl cellulose Cationized cellulose is preferred, sorbitol, pentaerythritol, gluconic acid, α-galactosamine hydrochloride, chondroitin-4-sulfate, chondroitin-6-sulfate, alginic acid, hyaluronic acid, chitosan, chitosan-co Particularly preferred are succinic acid modified products, cationized starch, carboxymethyl cellulose, and cationized cellulose. 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 preferably 0.1 to 70% by weight based on the water absorbing agent, and 0.1 to 3% by weight.
0% by weight is more preferred.

The crosslinking agent needs to contain at least one or more polyvalent metal ions. As the polyvalent metal ion selected in the present invention, calcium, magnesium, boron,
Titanium, zirconium, cerium, lanthanum, yttrium, iron, but preferably, boron, titanium,
Zirconium and cerium are more preferable, and boron and titanium are more preferable.

Examples of the form of the polyvalent metal ion include chlorides, sulfates, carbonates, acetates, formic oxides, milk oxides, alkoxides, and the like. There is. For example, chloride and alkoxide are preferable for titanium, and sodium borate is preferable for boron. It is necessary that the crosslinking agent used in the present invention contains at least one or more polyvalent metal ions, but other crosslinking agents such as aldehydes such as glutaraldehyde and glyoxal may be used as long as the water absorbing ability is not reduced. Compounds, amine compounds such as ethylenediamine, polyamide resin,
Aziridine compounds such as 2,2-bishydroxymethylbutanol tri [3- (1-aziridine)] propionic acid, tolylene diisocyanate, hexamethylene diisocyanate,
Isocyanate compounds such as toluene diisocyanate, glycerol, propylene glycol, polyhydric alcohols such as ethylene glycol, epichlorohydrin,
It is also possible to use a mixture with an epoxy compound such as ethylene glycol diglycidyl ether and diethylene glycol diglycidyl ether.

The concentration of the polyvalent metal ion used for crosslinking the polysaccharide powder is not particularly limited because it is appropriately selected depending on the amount of the polysaccharide powder to be added. However, the metal ion concentration is preferably 0.01 mM to 100 mM, and more preferably. Is 0.1 mM to 50 mM. The temperature at which the polyvalent metal ion surface-crosslinked particles of the soluble polysaccharide powder are formed is not particularly limited, but is preferably 5 to 90 ° C, more preferably 30 to 60 ° C, in order to promote the reaction. The solvent used at this time may be water, but may be a mixture of water and a low-boiling hydrophilic solvent such as alcohols and ketones.

According to this method, the surface of the polysaccharide particles contacts and reacts with the cross-linking agent at the moment of entering the cross-linking agent bath, and the particle surface is cross-linked. Because such surface crosslinked particles have a lower swelling speed than non-crosslinked particles,
The viscosity rise of the solution accompanying the swelling of the polysaccharide is delayed, and the fluidity is high. For this reason, it is easy to send this suspension into another device such as a heating tank by a continuous liquid sending device such as a pump, and the shape when gelling by swelling is arbitrary. Can control. This suspension can be sufficiently stirred even with a low-torque stirrer. For this reason, it is possible to continuously produce a crosslinked gel body and a water absorbing agent.

In the step (b) of the present invention, when the polyvalent metal ion surface-crosslinked particles of polysaccharide are swelled in a suspension with a crosslinking agent, the suspension is heated to increase the swelling speed. Is preferred. The heating temperature in this case is 30 to 10
0 ° C is preferred, and 50 to 80 ° C is preferred. The heating time is not particularly limited because it varies depending on the degree of crosslinking of the polysaccharide and the heating temperature, but is preferably 1 minute to 5 hours, more preferably 10 minutes to 2 hours. If the suspension is forcibly stirred with a stirrer or the like during further heating and swelling, a more uniform crosslinked gel can be obtained.

In the step (c), the crosslinked gel is dried, and any drying method is not limited as long as the method does not reduce the water absorption after drying.
For example, methods such as room temperature drying, heat drying, freeze drying, reduced pressure drying, and vacuum drying can be mentioned, and the freeze drying method is preferable.

The water-absorbing agent can also be obtained by drying the crosslinked gel in step (c) as described above. However, in order to obtain a water-absorbing agent having a higher gel strength and a high water absorption rate, the crosslinked gel is required to be obtained. After the formed step (b), the following steps are preferably performed. That is, (d) crushing the crosslinked gel obtained in the step (b) by a mechanical method in a hydrophilic solvent, and (e) one or more kinds of suspensions of the crushed gel particles and the hydrophilic solvent. Steps of adding a polyvalent metal ion and crosslinking the vicinity of the surface of the crushed gel particles with the polyvalent metal ion, and (f) collecting the gel particles and drying to obtain a water absorbing agent.

In the step (d), the crosslinked gel obtained in the step (b) may be crushed in a hydrophilic solvent by a roll mill, a pressure kneader, a homogenizer, an internal mixer, a Banbury mixer, a cell master. , Oster blender, mill, electric homogenizer,
Examples include batch types such as dispersers, and continuous types such as extruders, meat choppers, and continuous kneaders. Examples of the hydrophilic solvent include monovalent monohydric alcohols having 1 to 5 monohydric alcohols (such as methanol, ethanol, and isopropanol) and trivalent monohydric alcohols having 3 to 1 monovalent
Examples thereof include a hygroscopic, volatile anhydrous hydrophilic organic solvent such as six coutones (such as acetone) or a mixture thereof, and a mixture of these and water, and from the viewpoint of economic and environmental effects, Ethanol and isopropanol. The mixing ratio of such an anhydrous hydrophilic solvent and the internally crosslinked gel is preferably 3: 7 to 7: 3 by weight ratio, and 4: 6 to 7: 3.
6: 4 is more preferred. When water and an anhydrous hydrophilic solvent are mixed, the ratio is preferably 3: 7 to 7: 3, preferably 4: 6.
~ 6: 4 is more preferred. The ratio of water in this solvent may be high when crushing a gel with a high gel strength and a high polyvalent metal ion concentration in the crosslinked gel, but when crushing a gel with a low gel strength, anhydrous hydrophilic It is preferable that the mixing ratio of the solvent is high. In the case of a gel having a high gel strength, the gel is crushed in water, and then the gel particles are present in the form of particles even after the step (e), but the gel having a low gel strength is crushed in water or a solvent having a high water content. During the step (e), the gel particles adhere to each other to form a lump and cannot be recovered as gel particles. The ratio of water in these solvents and the mixing ratio of the solvent and the gel differ depending on the gel strength, and must be appropriately selected. After mixing these gels and the hydrophilic solvent, the internally crosslinked gel is crushed by the crusher to obtain gel particles, and the size of the gel particles is preferably 0.01 to 5 mm, and 0.1 to 2 mm. More preferred. If it is too small, it will become dust when dried, and the working environment will deteriorate. If it is too large, it will cause clogging of the piping and will wear in the subsequent process, and dry particles with a uniform diameter cannot be obtained.

In the step (e), a polyvalent metal ion is added to the suspension of the hydrophilic organic solvent containing the crushed gel particles obtained in the step (d), and the vicinity of the surface of the crushed gel particles is crosslinked again. . Polyvalent metal ions used at this time include calcium, magnesium, boron, titanium, zirconium, cerium, lanthanum, yttrium, and iron, preferably calcium, boron, titanium, zirconium, and cerium, and more preferably boron. , Titanium. These modes and the like are described in the step (a). The polyvalent metal ion concentration used for cross-linking near the surface of the crushed gel particles is not particularly limited because it is appropriately changed depending on the polysaccharide concentration, but is preferably 0.01 mM to 100 mM, more preferably 0.1 mM as the metal ion concentration. It is 1 mM to 50 mM. The temperature at which the surface of the gel crushed particles is crosslinked with the polyvalent metal ion is not particularly limited.
C. is preferable, and 30 to 60 C. is more preferable. The time required for the cross-linking of the polyvalent metal ion to proceed from the surface to the inside varies depending on conditions such as the temperature at this time, the size of the gel particles, and the ratio of the hydrophilic solvent to the gel. But 1 minute to 5 hours is preferred, and 10 minutes
Minutes to one hour are more preferred. By this surface cross-linking treatment, the surface of the gel particles is more strongly cross-linked with polyvalent metal ions in addition to the cross-linking performed in the steps (a) and (b), thereby improving the gel strength. On the other hand, the inside of the particles may be only internal cross-linking such that the water absorption is improved, and the reaction time, the degree of cross-linking between the surface vicinity and the inside of the gel particles can be arbitrarily changed by appropriately selecting the cross-linking agent concentration, Water absorption capacity and gel strength can be arbitrarily controlled.

In the step (f), any drying method is not limited as long as the method does not reduce the water absorption capacity after drying. Examples of the drying method include room temperature drying, heat drying, freeze drying, reduced pressure drying, and vacuum drying. Other than methods such as drying, the surface cross-linked gel particles are washed with the hydrophilic solvent used in the step (d), and the water in the gel is replaced with a volatile anhydrous hydrophilic organic solvent. There is a method of hot air drying. Preferably, a hot air drying method by substitution with a hydrophilic organic solvent is used from the viewpoint of energy efficiency.

The water-absorbing agent thus produced according to 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, Adhesives, surfactants, fertilizers, oxidants, reducing agents,
Water, salts and the like may be added to 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 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 weight, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of the water-absorbing agent.
It may be in the range of 01 to 5 parts by weight.

The water-absorbing agent produced according to the present invention is made into an absorbent article by, for example, compounding (combining) with a fibrous material such as pulp. Examples of absorbent articles include disposable diapers, sanitary napkins, incontinence pads,
Sanitary materials (body fluid absorbing articles) such as wound protection materials, wound healing materials, urine and other absorbent articles for pets, construction materials and soil water retention materials, waterproof materials, packing materials, gel construction materials such as gel sac, Food products such as drip absorbents, freshness preserving materials, cold insulators, etc., various industrial articles such as oil-water separators, anti-condensation materials, and coagulants, and agricultural and horticultural articles such as water retaining materials such as plants and soil. However, there is no particular limitation. For example, a disposable diaper is made of a back sheet (back surface material) made of a liquid-impermeable material, a core layer containing a water-absorbing resin manufactured according to the present invention, and a top sheet (surface material) made of a liquid-permeable material. ) Are laminated in this order and fixed to each other, and a gather (elastic portion), a so-called tape fastener, or the like is attached to the laminate.
Further, the disposable diaper also includes pants with a disposable diaper used when disciplining urination and defecation for infants.

[0028]

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. Example 1 Tyzor 131 solution (Du Po
nt: 0.25 ml of a 5 times diluted solution of titanium stock in deionized water (0.3 mM as titanium) and 2.5 ml of an aqueous solution of sodium tetraborate heptahydrate ( (6.6 mM as boron) to prepare a crosslinking agent bath in advance. Then, the crosslinking agent bath was heated to 50 ° C. and stirred, and 4 g of guar gum was gradually added. At this time, the guar gum was instantaneously crosslinked to form flakes. This suspension was gently stirred with a magnetic stirrer at 50 ° C. for 37 minutes, and then allowed to stand at 80 ° C. for 2 hours to obtain a massive gel cross-linked body. 100 g of the crosslinked gel and 100 ml of ethanol are mixed, crushed by a blender until the gel becomes 1 mm in size, collected by filtration, and the collected product is dried with hot air at 50 ° C. to obtain a powdery water-absorbing agent. Was. About the obtained water absorbing agent, the water absorption amount and the water absorption speed were measured.

The amount of water absorption was measured by the tea bag method using deionized water, a 0.9% by weight aqueous solution of sodium chloride (sodium chloride), a 5% by weight aqueous solution of sodium chloride (sodium chloride), artificial urine (1.94% by weight urea, 0.8% by weight sodium chloride,
840 ppm calcium chloride, 2050 ppm magnesium sulfate). That is, 1 g of a water absorbing agent was put into a 250 mesh nylon tea bag,
The tea bag was immersed in L of deionized water, 0.9% by weight saline, 5% by weight saline, and artificial urine for 3 hours. The tea bag was pulled up, drained for 10 minutes, and the weight was measured. The amount of water absorption of the water-absorbing agent was determined by taking the weight of the tea bag containing no water-absorbing agent soaked in water for 3 hours as a blank and calculating the weight of the tea bag containing the water-absorbing agent swollen by absorbing water.
The value obtained by subtracting the weight of the water absorbing agent before swelling and the weight of the blank is
The value obtained by dividing by the weight of the water absorbing agent before swelling was defined as the water absorption (g / g resin).

As a result, the water-absorbing agent obtained in this example had a water absorption of deionized water of 75 g / g, a water absorption of 0.9% by weight saline solution of 70 g / g, and a water absorption of 5% by weight saline solution of 68 g. /
g, artificial urine water absorption was 65 g / g.

Example 2 A guar gum-titanium-boron suspension was prepared in the same manner as in Example 1, and the suspension was sent to a stainless steel container with a peristaltic pump, and was allowed to stand at 80 ° C. for 1 hour in the stainless steel container. To obtain a massive gel cross-linked body. The crosslinked gel was dried with hot air in a stainless steel container at 50 ° C., and the obtained dried product was crushed to a size of 1 mm with a file to obtain a powdery water-absorbing agent. The water-absorbing agent obtained in this example has a water absorption of 50 g / g of deionized water and a water absorption of 0.5 g / g.
The 9% by weight saline water absorption was 56 g / g, the 5% by weight saline absorption was 52 g / g, and the artificial urine absorption was 50 g / g.

Example 3 Instead of Tyzor 131, Tyzor AA (titanium IV diisopropoxide acetylacetonate) solution (manufactured by Du Pont; the titanium content of the stock solution is 10% by weight) diluted 0.2 times with isopropanol in 0.2 ml. Was added (0.45 mM as titanium) to adjust the bath for the crosslinking agent with boron. Thereafter, a powdery water-absorbing agent was obtained in the same manner as in Example 1.

The water absorbing agent obtained in this example has a water absorption of deionized water of 55 g / g and a water absorption of 0.9% by weight of salt solution of 52%.
g / g, 5% by weight saline water absorption was 55 g / g, and artificial urine water absorption was 50 g / g.

Example 4 Suspension 2 of the crosslinked gel obtained in Example 1 and ethanol
00 ml was heated to 50 ° C. and further TyzorTE (Du
Pont: titanium stock in the stock solution was 15% by weight), and 0.4 ml (1.3 mM as titanium) of a solution diluted 5-fold with isopropanol was added, followed by stirring for 30 minutes. This solution was filtered through a gauze to recover a crushed gel crosslinked body,
It dried with hot air at ° C.

The water-absorbing agent obtained in this example has a water absorption of 53 g / g of deionized water and a water absorption of 0.9% by weight of a saline solution of 50%.
g / g, 5% by weight saline water absorption was 50 g / g, and artificial urine water absorption was 51 g / g.

Example 5 Zirconium chloride (manufactured by Nacalai Tesque) was used instead of sodium tetraborate as a crosslinking agent, and after swelling, a 1N aqueous sodium hydroxide solution was added to the gel to adjust the pH to 8.5. By operating in the same manner as in Example 2, a powdery water-absorbing agent was obtained. The water-absorbing agent obtained in this example has a water absorption of deionized water of 35 g / g and a water absorption of 0.9% by weight of saline solution of 28 g / g.
g, 5% by weight saline water absorption was 25 g / g, and artificial urine water absorption was 27 g / g.

Example 6 Zirconium chloride was used instead of sodium tetraborate heptahydrate as a crosslinking agent, and cerium chloride heptahydrate (manufactured by Nacalai Tesque) was used instead of Tyzor 131.
7. An aqueous solution of N sodium hydroxide is added to the gel to adjust the pH to 8.
The same operation as in Example 2 was carried out except that the value was adjusted to 5, to obtain a powdery water-absorbing agent. The water-absorbing agent obtained in this example had a water absorption of 30 g / g of deionized water and a water absorption of 0.9% by weight of a saline solution of 32.
g / g, 5% by weight saline water absorption was 25 g / g, and artificial urine water absorption was 22 g / g.

Comparative 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. while stirring, and dissolved and swelled to prepare a sol solution. After swelling for 1 hour, the sol liquid 200m
Then, 0.25 ml of a solution prepared by diluting a Tyzor 131 solution (manufactured by Du Pont; titanium content of the stock solution is 6% by weight) 5 times with deionized water was added to 200 ml of the sol solution (0.3 mM as titanium) to form a gel. I let it. Next, 2.5 ml of a 5% by weight aqueous solution of sodium tetraborate heptahydrate was added to the gel.
(6.6 mM as boron) and sufficiently crosslinked while crushing and mixing with a blender to obtain a crosslinked gel. Since the gel cross-linked body was massive and it was impossible to feed the gel with a peristaltic pump, the gel cross-linked body in the container was manually replaced with a stainless steel container. The crosslinked gel was dried with hot air at 50 ° C., and the dried product was crushed with a file to obtain a powdery water-absorbing agent.

The water-absorbing agent obtained in this comparative example has a water absorption of 60 g / g of deionized water and a water absorption of 0.9% by weight of a saline solution of 53%.
g / g, 5% by weight saline water absorption was 50 g / g, and artificial urine absorption was 52 g / g.

Comparative Example 2 In the same manner as in Comparative Example 1, 100 g of a crosslinked gel was obtained, mixed with 100 ml of ethanol, and reduced to 1 gel particle with a blender.
The crushed gel was collected by filtration with gauze and dried with hot air at 50 ° C. to obtain a water absorbing agent.

The water absorbing agent obtained in this comparative example has a water absorption of deionized water of 72 g / g and a water absorption of 0.9% by weight of saline solution of 70%.
g / g, 5% by weight saline water absorption was 68 g / g, and artificial urine water absorption was 65 g / g.

The water-absorbing agent of Example 2 prepared by the method of the present invention substantially matches the water-absorbing performance as compared with the water-absorbing agent of Comparative Example 1, and there is no particular difference in performance. When the crosslinked gel of (1) is transferred to a container, the liquid can be easily sent by a pump or the like in a state of high fluidity, so that it is obviously advantageous compared with the method of the conventional comparative example 1. It is. Further, as in Example 1, the obtained bulk gel cross-linked body is manually transferred to a blender, crushed with an organic solvent, and surface cross-linked as in Conventional Comparative Example 2 to obtain a powdery water-absorbing agent. It is possible.

[0043]

According to the present invention, when a polysaccharide sol is cross-linked with polyvalent metal ions, it is necessary to uniformly cross-link while forcibly stirring with a high-torque stirrer or the like. Does not need to be transported in a lump, and it can be easily transferred to another device or container in the state of a highly fluid suspension solution and gelled to produce a biodegradable water-absorbing agent. It can be used as sanitary goods, civil engineering building materials, coagulants, etc.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // A61F 13/53 A61F 5/44 H 4G066 13/49 A41B 13/02 D 5/44 A61F 13/18 307B 13/15 F term (reference) 3B029 BA18 4C003 AA24 4C090 AA05 BA12 BA13 BA19 BA23 BA40 BA47 BA61 BA70 BA72 BA92 BA93 BB67 BD03 CA35 DA01 DA22 4C098 AA09 CC02 DD05 DD29 DD30 4F070 AA01 AA02 AA08 BB08 GB06 GB09 4G066 AA38D AA56D AB23D AC01A AC35B BA09 BA28 BA36 CA43 DA11 EA05 FA12 FA21

Claims (2)

[Claims] 1. A method of adding dried polysaccharide particles or powder to a solution containing a polyvalent metal ion to form crosslinked particles near the surface of the polysaccharide particles or powder to form surface crosslinked polysaccharide particles. A method for producing a water-absorbing agent, comprising swelling in a crosslinking agent solution to form a crosslinked gel, followed by drying. 2. Addition of the dried polysaccharide particles or powder to a solution containing a polyvalent metal ion to crosslink the vicinity of the surface of the polysaccharide particles or powder to form surface crosslinked polysaccharide particles. After swelling in a crosslinking agent solution to form a crosslinked gel body, and then crushing the crosslinked gel body by a mechanical method in a hydrophilic solvent, adding a polyvalent metal ion to add a polyvalent metal to the vicinity of the surface of the crushed gel particles. A method for producing a water-absorbing agent, comprising crosslinking with an ion, collecting the gel particles, and drying.