MXPA99002053A

MXPA99002053A - Hygroscopic agent and its production process and

Info

Publication number: MXPA99002053A
Application number: MXPA/A/1999/002053A
Authority: MX
Inventors: Ueda Hiroko; Takahashi Naoko; Nagasuna Kinya; Miyake Koji; Fujita Yasuhiro; Hatsuda Takumi; Wada Katsuyuki
Original assignee: Nippon Shokubai Co Ltd
Priority date: 1998-03-03
Filing date: 1999-03-02
Publication date: 2000-04-24

Abstract

The present invention provides: a water absorbing agent, having excellent urine resistance; a water absorbing agent not only has excellent urine resistance, but also excellent absorption property which are stable to any urine composition and show little change over time, and production process and uses for these water absorbent. The water absorbing agent exhibits a specific or large value of absorption capacity under a load in a process in which the absorption capacity under a load is measured in a new manner using a specific liquid to be absorbed, and the present invention it provides an absorbent material and an absorbent article that exhibit a specific value higher than the new absorption index, since it is conducted, for example, from the absorption capacity under a load or from the resin concentration using the above water absorbing agent. The present invention further provides a production process for a water absorbing agent, having the specific parameter above.

Description

HIGROSCOPIC AGENT AND ITS PROCESS OF PRODUCTION AND USE BACKGROUND OF THE INVENTION A. TECHNICAL FIELD The present invention relates to a hygroscopic agent or water absorbing agent and to its production process and to its use, more particularly, it refers to a hygroscopic agent of excellent resistance to urine, especially a hygroscopic agent that can always exhibit excellent absorption properties despite the kind of liquids, such as urine, which is to be absorbed, and a production process for the hygroscopic agent, and refers additionally to the uses of the hygroscopic agent, specifically, to absorbent materials and articles, and still further refers to a process of measuring the absorption property, by which the absorption actions can be easily and accurately predicted when the hygroscopic agent and the absorbent materials and articles are practically used.

RF .: 29549 B. BACKGROUND OF THE INVENTION In recent years, hygroscopic resins (hygroscopic agents) are widely used as constituent materials of sanitary materials, such as paper diapers, sanitary napkins, and so-called incontinence pads, for the purpose of causing water absorbing resins to absorb body fluids such as urine and menstrual blood. The known examples of the water-absorbent resins, above, are as follows: partially neutralized cross-linked polyacrylic acid polymers; hydrolyzed products of starch-acrylic acid graft polymers, saponified products of vinyl acetate-acrylic acid ester copolymers; hydrolyzed products of acrylonitrile copolymers or acrylamide copolymers, and their crosslinked polymers; and cross-linked polymers of cationic monomers. It is said that the water-absorbent resins, above, should have, for example, the following properties: excellent amount and speed of water absorption, gel strength, the suction power to absorb water from a base material containing a aqueous liquid, in contact with the aqueous liquid such as body fluids. However, there are problems since the relationships between these properties do not necessarily exhibit positive correlations: for example, as the absorption capacity increases, some other properties such as liquid permeability, gel strength, and absorption speed deteriorate. As regards a method for improving these water absorption properties of the water-absorbent resin in good equilibrium, a technique is known, in which the vicinity of the surface of the water-absorbent resin is cross-linked, and They have proposed several methods like these. For example, methods are known, in each of which the following materials are used as the crosslinking agent: polyhydric alcohols (JP-A-58-180233 and JP-A-61-016903); polyglycidyl compounds, polyaziridine compounds, polyamine compounds, or polyisocyanate compounds JP-A-59-189103); polyvalent metals (JP-A-51-136588, JP-A-61-257235 and JP-A-62-007745); onoepoxy compounds (JP-A-61-098121; epoxy compounds and hydroxy compounds as used together (JP-A-02-132103); alkylcarbonate carbonates (DE4020780). that: the balance between the water absorption properties is being improved by the above surface treatments, but when the water absorbent resin is used for diaper absorbent materials, the water absorbing resin deteriorates over time, and the permeability Liquid or gel resistance fails, so that the urine from the diapers leaks.The deterioration of the water-absorbent resin occurs from the surface of the water-absorbing resin, and the soluble contents are eluted, and the liquid permeability or gel resistance This deterioration of the water-absorbent resin is considered due to a very small amount of the metal ion and by L-ascorbic acid as the content in the urine., the water-absorbent resin is in powder, and therefore, it can contain fine powders of 100 μm or less, and it is known to granulate when water is operated for the purpose of improving the handling capacity or the liquid permeability in the diapers. Granulation can prevent powder formation or improve flowability during moisture absorption. However, there are problems because the granulation by adding water to the water-absorbent resin, crosslinked on the surface, facilitates the destruction of the crosslinked layer on the surface. Especially, as regards water absorbing resins with high absorption capacity under load as desired in recent years, the elution of the soluble contents is prevented by crosslinking the surface vicinity of the water absorbing resins with high absorption capacity, so that the elution of the soluble contents can be suppressed in the case where the crosslinked layer on the surface is deteriorated by substances such as L-ascobic acid when urine is absorbed. Therefore, there are problems, since when the water-absorbent resin is used for diapers, the liquid permeability or the gel resistance deteriorates, so that the urine leaks from the diapers. On the other hand, with regard to the uses of the water-absorbent resin, a variety of absorbent materials or articles are proposed using water-absorbent resins, wherein the water-absorbent resins together have a plurality of the above-mentioned properties. previously and exhibit excellent performance (water absorption properties) when used for sanitary materials such as paper napkins and sanitary napkins. For example, the following is known: a water-absorbent resin comprising combinations of a gel capacity, a shear modulus of elasticity, and an extractive polymer content as specified (U.S.P. 4,654,039); a water-absorbent resin with a water absorption amount or rate and a gel strength as specified, and paper napkins and sanitary napkins using this water-absorbent resin (JP-A-60-18550, JP-A-60) -185551, and JP-A-6.0-18580); paper diapers using a water-absorbent resin having a specific amount or rate of water absorption and gel stability (JP-A-60-185805); water-absorbent articles using a water-absorbent resin with a water absorption amount, an absorption power, and a water-soluble content as specified. (JP-A-63021902); water-absorbent sanitary supplies containing a water-absorbent resin with an amount of water absorption, an amount of water absorption under a load, and a resistance to gel fracture as specified (JP-A-63-099861); paper diapers containing a water-absorbent resin with a water absorption amount and a water absorption rate as a filler as specified (JP-A-02-034167); a water absorption agent containing a water absorbing resin with a water absorption amount under a charge and a particle diameter as specified (EP 339,461); a water absorption agent which contains a specific or greater amount of water absorbing resin with a water absorption rate and a water absorption amount under a load in a short time as specified (EP 443,627); a combined water-absorbent material containing a specific or greater amount of water-absorbent resin with a strain under a load and a suction index as specified (EP 532,002); and an absorbent article using a resin with a pressure absorption index and an extractivity level of 16 hours as regulated (EP 615,735).

In recent years, absorbent articles such as paper diapers are becoming thinner, in the amount of water absorbent resin, as an absorbent layer of the absorbent articles is used, it tends to increase. That is, as regards the previous absorbent layer, having the weight ratio of 0.3 or more, particularly, 0.5 or more of water-absorbent resin to the total of the water-absorbent resin and the base, fibrous material ( this relationship can later be referred to as the "resin concentration") that becomes primarily ordinary. However, it becomes clear that problems still exist when previously known resins with a variety of regulated properties are used for these absorbent articles having high resin concentration. That is to say, the water absorption properties of the absorbent articles are being improved by combinations of the various previous properties, but it is being found that there are problems since, depending on the composition of the liquid to be absorbed, the absorption properties of The water in the resins can not be sufficiently exhibited in a special way when the resin concentration in the absorbent articles is high. It is said that there are problems since, when the absorbent article is, for example, a paper diaper, the composition of the urine varies with factors, such as the age of the users, food and drinks taken, prescribed medicines, and since the absorption action of the water-absorbent resin could therefore be greatly different from the expectation.

BRIEF DESCRIPTION OF THE INVENTION A. OBJECTS OF THE INVENTION Therefore, an object of the present invention is to provide: a water absorbing or hygroscopic agent, which undergoes little deterioration with time when it absorbs urine and thus has excellent resistance to urine; a water-absorbing agent that does not only have excellent resistance to urine, but also absorption properties that are stable to any urine composition and show little change over time, and which is therefore especially and favorably used for articles absorbers that have high concentration of resin; and production processes for these water-absorbent or hygroscopic agents. In addition, another object of the present invention is to make clear that absorption properties are required for water-absorbent resins when the resin ratio is a specific value, and to provide an absorbent article using the optimum water-absorbent resin for each ratio of water-absorbent resin, and to provide an absorbent material and an absorbent article, both of which exhibit a high absorption amount, always stable, especially, a high amount of absorption until leakage occurs in a used condition very close to the practical use Furthermore, still another object of the present invention is to provide a process of measuring the absorption property by which the absorption actions can be easily and accurately predicted when the hygroscopic water absorption agent and the absorbent materials and articles are absorbed. used in a practical manner, and which is very useful for producing a water absorbent, absorbent material, or absorbent article exhibiting excellent absorption properties.

B. DESCRIPTION OF THE INVENTION The present inventors studied with encouragement themselves and with great efforts to achieve the above object. As a result, the present inventors completed the present invention by developing new evaluation processes for (1) a deterioration absorption capacity under a load as seen using a specific liquid to be absorbed, (2) an absorption capacity of deterioration. under a load as seen after the execution of the specific procedure using a specific liquid to be absorbed, and (3) a deterioration absorption index under a load, and finding that the new problems could be solved by a new water-absorbing agent that exhibits a specific or greater value of absorption capacity or deterioration absorption index under this load in these evaluation processes. Parameter (1) is not provided with the specific procedure, so it is later referred to as the -capability of absorption of static deterioration under a load, includes four stages (1), (2), (3), (4) in view of the magnitude of the load, and particularly, steps (1) and (4) are important. The above parameter (2) is provided with the specific procedure, so that it is later referred to as the dynamic deterioration absorption capacity under a load. Then, the present inventors found a process for obtaining a water absorbing agent that exhibits the specific absorption capacities or indices, above (subsequently, these can be referred to generically as parameters), in which an ion blocking or chelating agent is used. which includes an amino-polycarboxylic acid is preferably added to a water-absorbent resin by a specific method. In addition, the present inventors studied and studied with encouragement themselves and with great efforts about the relationships between the ratio of resin in the absorbent material and the physical properties of the absorbent agent. As a result, the present inventors completed the present invention upon finding that the amount of absorption, maintained until the occurrence of the leak in a state used very close to practical use, depends on the specific relationships, since they lead from agent properties. of water absorption, such as absorption capacity under no load and the new specific absorption capacities above or index under a load, and of the resin ratio in the absorbent material, and that the amount of absorption of the absorbent material or article in a state used very close to the practical state it is increased if ratios of water absorbing agent and resin are selected to enlarge the volumes of the formulas of the above relations. The water absorbing agent, according to the present invention, can be any of 1 to 3 below. A water absorbing agent, having an absorption capacity of 30 (g / g) or more under no load and a static deterioration absorption capacity (1) of 20 (g / g) or more under a load. 2. A water-absorbing agent, having an absorption capacity of 30 (g / g) or more under no load and a dynamic deterioration absorption capacity of 20 (g / g) or more under a load. 3. A water absorbing agent having an absorption capacity of 30 (g / g) or less under no load and a static deterioration absorption capacity 4 of 23 (g / g) or more under a load. An absorbent material, according to the present invention, comprises the water-absorbing agent, above of the present invention, and a fibrous, base material, wherein the weight ratio and the water-absorbing agent to the total of the water-absorbing agent and the base, fibrous material is 0.4 or more. An absorbent article, according to the present invention, comprises: an absorbent layer including the above absorbent material, of the present invention; a sheet of liquid permeable surface; and a backing sheet impervious to liquids. A process for measuring the absorption property, according to the present invention, is characterized in that a liquid containing a reducible substance is used as a liquid to be absorbed in a process for measuring at least one selected absorption property at from the group consisting of: absorption properties under a load of a water absorbing agent; absorption properties of an absorbent material of which the weight ratio of a water absorbing agent to the total of the water absorbing agent and a fibrous base material is 0.4 or more; and the absorption properties of an absorbent article that includes the previous absorbent material. A production process for a water absorbing agent, according to the present invention, comprises the step of mixing an ion blocking agent and a surface crosslinking agent, which can be reacted in a carboxyl group, with a resin absorbent of water having a carboxyl group. Another production process for a water absorbing agent, according to the present invention, comprises the steps of: crosslinking the vicinity of the surface in the water absorbent resin that is obtained by polymerizing a monomer component including an unsaturated carboxylic acid in the presence of an internal crosslinking agent; and adding water and an ion blocking agent to the resultant surface-cross-linked water-absorbent resin, thereby granulating the water-absorbent resin. Still another water-absorbing agent, according to the present invention, is obtained by a process that includes the step of adding to a water-absorbent resin at least one chelating agent selected from the group consisting of compounds of the general formulas (1) and (2) and maleic hydrophilic polymers (including salts) (3), wherein the general Formula (1) is: R2 / Ri-CH- (CH2) n-CH-N (1) X * X * R-Y where: -n, X1, and R -R3 denote the following numbers and structures: n = 0, 1 X1 = COOM1 (M1 = H, Na, K, NH4). R1 = H, OH, Me R2 = H, -CH2COOM2- -CH2CH2COOM '(M ~ = H, Na, K, NH4 -CH-CH-R- »I I R3 = -CH2COOM3 / -CH2CH2COOM3, M3OOC COOM3 (M3 = H, Na, K, NHY (R4 = H, OH, Me and where the general formula (2) is: R6 R7 I / R5-CH- (CH2) m-CH-N-CH-CH N (2) I I \ X2 X2 R8 where: m, X2 and R5-R6 denote the following numbers and structures: = 0.1 X2 = COOM4 (M4 = H, Na, K, NH4) R5 = H, OH, Me R6 = H, -CH2COOM5, -CH2CH2COOM5 ( M5 = H, Na, K, NH4) R7 = H, -CH2COOM6, -CH2CH2C006 (M6 = H, Na, K, NH4 -CH-CH-R9 I I R8 = -CH2COOM7, -CH2CH2C00M7, M7OOC COOM * " (M7 = H, Na, K, NH4) (R9 = H, OH, Me).

The foregoing objects and others and the advantages of the present invention will become more fully apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 illustrates a measuring apparatus for the water absorption capacity under a load.

DETAILED DESCRIPTION OF THE INVENTION Subsequently, the present invention will be explained in detail.

"Water absorbing agent, or hygroscopic" The water-absorbing agent of the present invention has a specific value or greater capacity of absorption under no load and also has specific or greater values with respect to the following new properties. Absorption capacity of static deterioration under a load, absorption capacity- of dynamic deterioration under a load, and deterioration absorption index under a load. The absorption capacity under no load in the present invention is a numerical value as calculated by a method in which: 0.2 g of the water absorbing agent is uniformly placed in an elaborate non-woven bag (60 mm x 60 mm) and then it is immersed in a sodium chloride solution, aqueous, at 0.9% by weight (Physio-logical solution of sodium chloride); sixty minutes later, the bag is removed and then drained at 250 g for 3 minutes with a centrifuge, and then the weight of x (g) of the bag is measured; on the other hand, the same procedure is carried out using a non-water absorbing agent, and the resulting weight W0 (g) is measured, and in this way, the absorption capacity of the previous weights Wx and W0 and the weight of the water absorbing agent according to the following equation: absorption capacity (g / g) =. { (weight Wi- weight W0) / (weight of water absorbing agent)} -1 The ability to absorb static deterioration under a load in the present invention is an absorption capacity that is measured under a load for a water absorbing agent (resin) after carrying out a treatment in which: the absorbent agent of water is swelled for 15 minutes with a physiological solution of sodium chloride containing L-ascorbic acid at a predetermined concentration as the liquid to be absorbed, then the swollen agent is allowed to stand stationary for a predetermined period. This ability to absorb static deterioration under a load is a new evaluation point for a water absorbing agent. The following absorption properties of conventional water-absorbing resins (water-absorbing agents) are known, for example: absorption capacity, absorption capacity under a load, liquid permeability, suction power, and absorption rate. However, the measurement is generally made over a comparatively short period of time using a liquid with an electrolyte concentration similar to that of urine. However, in many cases, the actual use time of the diapers extends for a prolonged period of 6 hours or more. Therefore, the water-absorbent resins, which provide excellent results with respect to the above conventional evaluation points as proposed up to now, do not necessarily exhibit excellent performance in practical use as well. In addition, the urine contains compounds that change (deteriorate) the properties of the resin over time, and the existence of those compounds also greatly influences the absorption actions of the water-absorbent resin in practical use. The present inventors studied and studied with encouragement as well and with great efforts to develop an evaluation process that can correctly assess the absorptive capacities of the water-absorbent resin in practical use. As a result, the present inventors found that the absorption actions in practical use can be easily and accurately predicted by measuring the absorption capacity under a load after allowing the water-absorbent resin to be left stationary for a period of time. relatively long time in a physiological sodium chloride solution containing L-ascorbic acid in a predetermined concentration as the liquid to be absorbed. Conventional processes are known, in which the water-absorbent resin is solubilized using L-ascorbic acid or its salts, or the amount of soluble component as solubilized in this way is measured (eg, JP-A-05-247221, JP-A-07-059813, JP-A-08-337726, JP-A-10-067805). However, in these techniques, the water-absorbent resin is solubilized under saturated swelling conditions, and nothing is considered with respect to the ability to absorb a liquid, which is the inherent role of the water-absorbent resin changes when the resin is used, while the static deterioration absorption capacity under a load of the present invention is a new evaluation point that allows judgment of how the inherent distribution capacities remain in the resin that once the urine is absorbed will change due to the urine until the resin additionally absorbs urine next time. The static deterioration absorption capacity (1) under a load in the present invention is an absorption capacity of the water absorbing agent as determined by the following sequential steps of: forming a water-absorbing agent as it swells at 15 (g / g) with a physiological solution of sodium chloride containing L-ascorbic acid at a concentration of 0.005% by weight; leave the water absorbing agent in this swollen state for 6 hours; allowing the swollen water-absorbing agent to absorb the physiological sodium chloride solution for another hour in a state where a load of 50 g / cm 2 is mounted in the swollen, water-absorbing agent; and measuring the weight of the resulting swollen gel. The water absorbing agent of the present invention is characterized by having an absorption capacity of 30 (g / g) or more under no load and the capacity of absorption of static deterioration (1) of 20 (g / g) or more under a load. In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when the water absorbing agent is used for absorbent articles that have high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). Furthermore, in the case where the absorption capacity of static deterioration (1) under a load in less than 20 (g / g), in a similar manner, the absorption capacities of the absorbent article, and the leakage are insufficient and thus it is prone to occur, or the absorption actions vary greatly due to factors such as compositional changes of the liquids to be absorbed, so that stable absorption properties are not obtainable. The static deterioration absorption capacity (1) under a load is preferably 23 (g / g) or more. The static deterioration absorbing capacity (2) under a load in the present invention is an absorptive capacity of the water absorbing agent as removed by the following sequential steps of: forming a water absorbing or hygroscopic agent as it swells at 15 ° C. (g / g) as a physiological solution of sodium chloride containing L-ascorbic acid in a concentration of 0.05% by weight; leaving the water absorbing agent in this swollen state for 2 hours; allowing the swollen water absorbing agent to absorb the physiological solution of sodium chloride for an additional 1 hour in a state where a load of 50 g / cm 2 is mounted in the swollen water-absorbing agent; and measuring the weight of the swollen gel, resulting. The water absorbing agent of the present invention is characterized by having an absorption capacity of 30 (g / g) or more under no load and the capacity of absorption of previous static deterioration (2) of 23 (g / g) or more under a load. In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient and leakage and in this way is prone to occur especially when the water absorbing agent is used for articles Absorbents that have high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). In addition, in the case where the absorption capacity of static deterioration (2) under the load is less than 23 (g / g). In addition, in the case where the absorption capacity of static deterioration (2) under a load is less than 23 (g / g), similarly, the absorption capacities of the absorbent article are insufficient, and the leakage and things per Style are prone to occur, or absorption actions, vary greatly due to factors such as changes in the composition of the liquids to be absorbed, so that stable absorption properties are not obtainable. The static deterioration absorption capacity (2) under a load is preferably 25 (g / g) or more. The static deterioration absorbing capacity (3) under a load in the present invention is an absorptive capacity of the water absorbing or hygroscopic agent as determined by the following sequential steps of: forming a water absorbing agent as it swells at 15 ° C. (g / g) with a physiological solution of sodium chloride containing L-ascorbic acid at a concentration of 0.05% by weight; leaving the water absorbing agent in this swollen state for 2 hours; allowing the swollen water-absorbing agent to absorb the physiological sodium chloride solution for an additional 1 hour in a state where a load of 50 g / cm 2 is mounted in the swollen water-absorbing agent; and measuring the weight of the swollen gel, resulting. The water-absorbing agent of the present invention is characterized as having an absorption capacity of 30 (g / g) or more under no load and the static deterioration absorption capacity, above (3) of 20 (g / g) or lower a load. In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when the water absorbing agent is used. for absorbent articles that have high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). Furthermore, in the case where the absorption capacity of static deterioration (3) under a load is less than 20 (g / g), similarly, the absorption capacities of the absorbent article, and the leakage and things by the absorber are insufficient. style are prone to occur, or the absorption actions vary greatly due to factors such as changes in the composition of the liquids that are going to be absorbed, so that stable absorption properties are not obtainable. The absorption capacity of static deterioration (3) under a load is preferably 23 (g / g) or more. The static deterioration absorption capacity (4) under a load in the present invention is an absorption capacity of the water absorbing agent as determined by the following sequential steps of: forming a water absorbing agent as it swells at 15 (g / g) with a physiological solution of sodium chloride containing L-ascorbic acid in a concentration of 0.05% by weight; leaving the water absorbing agent in this swollen state for 6 hours; allowing the swollen water absorbing agent to absorb the physiological sodium chloride solution for another hour in a state where a 20 g / cm2 load is mounted in the swollen water-absorbing agent; and measuring the weight of the swollen gel, resulting. The water absorbing agent of the present invention is characterized by having an absorption capacity of 30 (g / g) or more under no load and the capacity of absorption of previous static deterioration (4) of 30 (g / g) or more. under a load. In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when the water absorbing agent is used for absorbent articles that have high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). In addition, in the case where the absorption capacity of static deterioration (4) under a load is less than 30 (g / g), in the similar manner, the absorption capacities of the absorbent article are insufficient, and the leakage and the style are prone to occur, or the absorption actions vary greatly, due to factors such as changes in the composition of the liquids to be absorbed, so that stable absorption properties can not be obtained. The static deterioration absorption capacity (4) under a load is preferably at least 32 (g / g), more preferably at least 34 (g / g). The present invention provides a new water-absorbing agent of which the above absorption capacity under no load and the static deterioration absorption capacities (1), (2), (3), (4) under a load are specific values or greater. This water-absorbent or hygroscopic agent is favorably used even for paper diapers having high resin concentration and low concentration of fibrous base material that accompanies the thinness of paper diapers in recent years, and this agent can further reduce the leakage in practical use. The present inventors found that the measurement value of the static deterioration absorption capacity (1) or (4) under a load was especially important. In this way, the present invention provides a new water-absorbing agent of which the absorption capacity under no load and the absorption capacity of static deterioration (1) or (4) under no load are specific or greater values, and the article Absorbent (e.g., paper diaper) using the water absorbing agent of the present invention can reduce leakage in practical use. The measurement value of the absorption capacity of static deterioration (1) under a load of the water absorbing agent is important for paper diapers that have high concentration of resin and low concentration of base, fibrous material that accompanies the thinness of the paper diapers in recent years. - The dynamic deterioration absorption capacity under a load in the present invention is an absorption capacity that is measured under a load for a water absorbing agent (resin) after carrying out the treatment in which: the absorbing agent of Water is swelled for 15 minutes with a physiological solution of sodium chloride containing L-ascorbic acid in a predetermined concentration as the liquid to be absorbed, and then the swollen agent is allowed to stand stationary for a predetermined time and then is damaged dynamically assuming movements in practical use. This ability to absorb static deterioration under a load is a new evaluation point for a water absorbing agent. The following absorption properties of conventional water absorbing resins (water absorbing agents) are known, for example: absorption capacity, absorption capacity under a load, liquid permeability, suction power, and absorption speed. In addition, a method is known, in which: the water-absorbing resin is allowed to absorb a physiological solution of sodium chloride and is formed in a gel in the form, and the resulting gel is sheared, and then the re-absorption capacity of the gel (USP 5,453,323). However, the measurement of the above properties is generally done in a comparatively short period of time using a liquid with an electrolyte concentration similar to that of the urine. Therefore, water-absorbent resin that provides excellent evaluation results does not necessarily exhibit excellent performance in practical use as well. In addition, the urine contains compounds that change (deteriorate) the properties of the resin over time, and the existence of these compounds also greatly influences the absorption actions of the water-absorbent resin in practical use. In addition, because users move in practical use, the dynamic force as well as the load acts on the resin. The present inventors studied and studied with encouragement themselves and with great efforts to develop an evaluation process that can correctly assess the absorption capacities of the water-absorbing resin in practical use. As a result, the present inventors found that the absorption actions, in practical use, can be easily and accurately predicted by measuring the absorption capacity under a load after carrying out a treatment in which: the water absorbing resin it is allowed to stand stationary for a comparatively long period of time in a physiological solution of sodium chloride containing L-ascorbic acid in a predetermined concentration as the liquid to be absorbed, then the resin is subjected to the dynamic force. Conventional processes are known, in which the water-absorbent resin is solubilized using L-ascorbic acid or its salts, or the amount of the soluble component is measured as it is solubilized in this way (for example, JP-A-05-247221, JP-A-07-059813, JP-A-08-337726, JP-A-10-067805). However, in these techniques, the water-absorbent resin is solubilized under saturation swelling conditions, and nothing is considered with respect to how the ability to absorb a liquid, which is the inherent role of the water-absorbent resin, changes when the resin is used, while the dynamic interior absorption capacity under a load in the present invention is a new evaluation point that allows the judgment of how the inherent absorption capabilities remain in the resin that once absorbed the Urine will change due to urine and dynamic force, as the resin is applied, until the resin additionally absorbs urine the next time. The ability to absorb static deterioration under a load in the present invention is an absorptive capacity of the water absorbing agent as determined by the following sequential steps of: forming a water-absorbing agent as it swells at 15 (g / g) with a physiological solution of sodium chloride containing L-ascorbic acid at a concentration of 0.005% by weight; leaving the water absorbing agent in this swollen state for 4 hours; dynamically damaging the swollen, water-absorbing agent; allowing the dynamically damaged water absorbing agent to absorb the physiological sodium chloride solution for another hour in a state where a load of 50 g / cm 2 is mounted in the swollen, water-absorbing agent; and measuring the weight of the swollen gel, resulting. The water absorbing agent of the present invention is characterized as having an absorption capacity of 30 (g / g) or more under no load and the dynamic deterioration absorption capacity, above of (209 (g / g) or lower In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when the water absorbing agent It is used for absorbent articles with high resin concentration The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). absorption of dynamic deterioration under a load is less than 20 (g / g), similarly, the absorption capacities of the absorbent article are insufficient, and leakage and things by style are prone to occur, or the absorption actions vary greatly due to factors, such as changes in the composition of the liquids to be absorbed, and the dynamic force as applied to the resin, so that stable absorption properties can not be obtained. The dynamic deterioration absorption capacity under a load is preferably 23 (g / g) or more. The present invention provides a new water-absorbing agent of which the above absorption capacity under no load and the ability to absorb static deterioration under a load are specific or greater values. This water-absorbing agent is favorably used even for paper diapers having high resin concentration and low concentration of more fibrous material that accompanies the thinness of paper diapers in recent years, and this agent can further reduce leakage in the use practical. The deterioration absorption index under a load in the present invention is the total of the static deterioration absorption capacities, above (l) - (4) and the static deterioration absorption capacity under a load. The rate of absorption of static deterioration under a load is an evaluation point at which damage in practical use is assumed. It is considered that as the total of the values as obtained by the previous evaluation points is greater, that the water absorbing agent always exhibits high performance even if it is subjected to a variety of damage as it occurs in practical use. - The water absorbing agent of the present invention has an absorption capacity of 30 (g / g) or more under a load and the previous deterioration absorption index of 110 (g / g) or more under a load. In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when the water absorbing agent is used for absorbent articles with high resin concentration. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). In addition, in the case where the absorption rate of deterioration under a load is less than 110 (g / g), in a similar manner, the absorption capacities of the absorbent article are insufficient, and leakage and the like are prone. to occur, or the absorption actions vary greatly due to factors, such as changes in the composition of the liquids that are absorbed and the dynamic force as the resin is applied, so that the stable absorption properties are not obtainable.

The rate of deterioration under a load is preferably at least 120 (g / g), ^ preferably at least 130 (g / g). The present invention provides a new water-absorbing agent of which the above absorption capacity under no load and the rate of absorption of deterioration under a load are specific or greater values. This water-absorbing agent is favorably used even for paper diapers having high resin concentration and low concentration of fibrous, base material that accompanies the thinness of paper diapers in recent years, and this agent can further reduce leakage in the practical use As mentioned above, the present inventors studied and studied with encouragement themselves and with great efforts to develop an evaluation process that can correctly assess the absorption capacities of the water-absorbent resin in practical use, so that the inventors found new properties of the static deterioration absorption capabilities, prior under a load, dynamic deterioration absorption capacity under a load, and deterioration absorption index under a load, but the inventors additionally found that the absorption actions in the use practical can be easily predicted some degree by swelling the resin with a physiological solution of sodium chloride, and then letting the resin stationary for a long time, and then measuring the absorption capacity under a load (ie, substantial absorption capacity) low or a load). . That is, it is possible to evaluate the absorption capacities in the water-absorbent resin as exhibited in the case where the amount of components that deteriorate the water-absorbent resin is small in practical use or where the variation of urine does not occur very much. greatly practical use. However, it is considered that, in practical use, the amount of components that deteriorate the water-absorbent resin is susceptible to make greater a variation of urine tendencies occurs, then the new property of the previous substantial absorption capacity under a load it appears to be an absorptive capacity of the water-absorbent resin as it is at least necessary in practical use.

This substantial absorption capacity under a load is an absorption capacity that is measured under a load for a water absorbing agent (resin) after carrying out a treatment in which: the water absorbing agent swells 15 times with a physiological solution of sodium chloride, the liquid to be absorbed, and then the swollen agent is allowed to stand stationary for a predetermined time. This substantial absorption capacity under a load is a new evaluation point for a water absorbing agent. The two substantial absorption capacities, mentioned above (1) and (2) under a load are exemplified according to the duration for which the swollen, water-absorbing agent is allowed to stand stationary. These absorption capacities (1) and (2) under a load allow the judgment of how the inherent absorption capacities remain in the resin that once the urine is absorbed will change due to the urine until the resin additionally absorbs urine the next time. To begin with, the substantial absorption capacity (1) under a load in the present invention is an absorptive capacity of the water absorbing agent as determined by the following sequential steps of: - forming a water-absorbing agent as it swells at 15 ° C; (g / g) with a physiological sodium chloride solution: leave the water absorbing agent in a swollen state for 2 hours; allowing the swollen water-absorbing agent to absorb the physiological sodium chloride solution for another hour in a state where a load of 50 g / cm 2 is mounted in the swollen, water-absorbing agent; and measuring the weight of the swollen gel, resulting. In the present invention, it is preferable that the water absorbing agent has an absorption capacity of 30 (g / g) or more under no load and the previous substantial absorption capacity (1 of 23). (g / g)) or more under a load. In this case, this allows the water absorbing agent to have any one or two or more of the new properties of the specific or higher values above of the static deterioration absorption capacities (1) - (4) under a load, capacity of absorption of dynamic deterioration under a load, and absorption rates of deterioration-low or a load. In the case where the absorption capacity under no load is less than 30 g / g, the absorption capacities are insufficient, and leakage and styling things are prone to occur especially when the water absorbing agent is used for absorbent articles. which have high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). In addition, in the case where the capacity of (1) substantial absorption under a load is less than 23 (g / g), similarly, the absorption capacities of the absorbent article are insufficient, and leakage and things by style are prone to occur, and stable absorption properties can not be obtained. The substantial absorption capacity (1) under a load is preferably at least 24 (g / g) or more, more preferably at least 25 (g / g). Then, the substantial absorption capacity (2) under a load in the present invention is an absorption capacity of the water absorbing agent as determined by the following sequential steps: forming a water absorbing agent as it swells at 15 (g / g) with a physiological solution of sodium chloride; leaving the water absorbing agent in a swollen state for 6 hours; allowing the swollen water-absorbing agent to absorb the physiological sodium chloride solution for another hour in a state where a load of 50 g / cm 2 is mounted in the swollen, water-absorbing agent; and measuring the weight of the swollen gel, resulting. In the present invention, it is also preferred that the water absorbing agent of the present invention have an absorption capacity of 30 (g / g) or more under no load and the previous substantial absorption capacity of (2) of 20 (g / g) or more under a load. Also, in this case, it is permissible for the water absorbing agent to have any one or two or more of the new properties of the above specific higher values of the static deterioration absorption capacities (1) - (4) under a load, capacity of absorption of dynamic deterioration, under no load, and deterioration absorption index under a load. In the case where the absorptive capacity under a load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when the water absorbing agent is used. for absorbent articles with high resin concentration. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). In addition, in the case where the substantial absorption capacity (2) under a load is less than 20 (g / g), similarly, the absorption capacities of the absorbent article are insufficient, and leakage and things by style are prone. to occur, and stable absorption properties can not be obtained. The substantial absorption capacity (2) under a load is preferably at least 23 (g / g). The present invention may additionally provide a new water-absorbing agent that preferably has specific or greater values of absorption capacity under no load and substantial absorption capacities (1) - (2) under a load. This water-absorbing agent is favorably used even for paper diapers having a high concentration of resin and low concentration of fibrous, base material - which accompanies the thinness of paper diapers in recent years, and this agent can further reduce the weight of the diaper. practical use The water-absorbing agent of the present invention preferably has an absorption rate of 20-80 (sec) and a water-soluble content of 1-15% by weight. The water soluble content is in the range of preferably 2-15% by weight, more preferably 2-10% by weight. In the case where the absorption speed exceeds 80 (sec), the absorption of the liquid by absorbent materials or articles including the water absorbing agent is so slow that 60 minutes pass which makes a large amount of liquid tend not to be absorbed. In the case where the absorption rate is less than 20 (sec.), The absorption of liquids by absorbent materials or articles that include the water absorbing agent is thus too rapid that gel blocks are easily formed. These phenomena occur largely in a special way to absorbent materials or articles with high weight ratio (resin concentration) of the water absorbing agent when treating the water absorbing agent and the base material, fibrous. In addition, a water-absorbing agent with a water-soluble content of less than 1% by weight costs more for its production and therefore is more difficult to produce, and additionally, when it reduces the water-soluble content, the absorption capacity under no load it usually tends to fall. In the case where the water soluble content is more than 15% by weight, it is difficult to obtain the water absorbing agent with the absorption capabilities of aesthetic deterioration under a load, dynamic deterioration absorption capacity under a load, and index of absorbing deterioration under a load falling within the scope of the present invention, or it is also difficult to obtain the water absorbing agent with the substantial absorption capacities under a load falling in the preferable range mentioned above. As regards the composition of the water-absorbing agent of the present invention, which includes a water-absorbent resin as an essential component, it is preferably used. The water-absorbing agent of the present invention with the specific parameters mentioned above can be obtained for example, by any of the following processes: 1. A process in which a specific amino-polycarboxylic acid and a cross-linking agent of surface that reactive in the carboxyl group of a water-absorbent resin are mixed with the water-absorbent resin to crosslink this resin; 2. A process in which a specific amino-polycarboxylic acid is added to a specific surface-crosslinked water-absorbent resin having an absorption capacity of 23 (g / g) or more under a load. However, the process for obtaining the water absorbing agent of the present invention is not limited to those mentioned above. Hereinafter, the production process for the water absorbing agent according to the present invention is explained in detail. The water-absorbent resin, which is used to produce the water-absorbing agent of the present invention, is a conventionally known resin that absorbs an amount of water as large as 50-1000 times the original in ion exchange water to form this way a nitrogel. Examples of this water-absorbent resin include: cross-linked polymers of partially neutralized polyacrylic acids; hydrolyzed products of starch-acrylonitrile graft polymers; hydrolyzed products of starch-acrylic acid graft polymers; saponification products of vinyl acetate copolymer acetate ester of acrylic acid ester; hydrolyzed products of acrylonitrile copolymers or acrylamide copolymers, or their crosslinked polymers; saponified products of cross-linked polyhydric alcohols containing a carboxylic group; and isobutylene-maleic anhydride copolymers. Among these, those having a carboxylic group are preferred and are typically obtained by polymerizing and crosslinking monomers of which the main component is acrylic acid and / or a salt (neutralized product) thereof. Further, as regards the water absorbent resin, above, those having a water-soluble, non-crosslinked content of 25% by weight or less, preferably 15% by weight or less, preferably 10% by weight or less are used. The content of carboxyl groups in the water-absorbent resin is not particularly limited, but is preferably -0.01 equivalents or more per 100 g of the water-absorbent resin. For example, the neutralization ratio of acid p? >I agree that it is in the range dably from 1-60% by mol, more dably from 10-50% by mol. Examples of the above salt of acrylic acid include: alkali metal salts (eg, sodium, potassium, and lithium) ammonium salts and amine salts of acrylic acid. It is preferred that the constituent units of the above water-absorbent r comprise acrylic acid of 0-50% by mol, more preferably 10-40% by mol, and its salt of 100-50% by mol, in more preferential 90-60% mol, (where the total of both is 100% mol). The neutralization can be carried out either to monomers before the polymerization or to the resulting polymer during or after the polymerization, but it is preferably carried out to monomers before polymerization in view of the cross-production, because the neutralization of the polymer requires a considerably prolonged time. The monomers for producing the water-absorbent r of the present invention may additionally comprise monomers other than the above acrylic acid (salt) if necessary. Monomers other than acrylic acid (salt) are not particularly limited, but specific examples thereof include: unsaturated, anionic monomers, such as methacrylic acid, maleic acid, vinylsulfonic acid, styrenesulfonic acid, 2- (meth) acrylamido acid -2-methylpropanesulfonic, 2- (meth) acryloylethanesulfonic acid, and 2- (meth) acryloylpropanesulfonic acid, and their salts; unsaturated, non-ionic monomers containing a hydrophilic group, such as acrylamide, methacrylamide, N-ethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (met) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, vinylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine, N-acryloylpyrrolidine; unsaturated, cationic monomers such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, (N, N-dimethylaminopropyl methacrylate, N, N-dimethylaminopropyl (meth) acrylamide, and its quaternary salts These monomers may be used either alone or in combinations with each other In the present invention, when monomers other than acrylic acid (salt) are used, the ratio of them is preferably 30% by mole or less, preferably 10% by mole or less, of the total with acrylic acid and its salt.If the above monomers other than acrylic acid (salt) are used in the above relationship, then the water absorption ratios of the resulting water-absorbent resin are further improved, and the water-absorbent resin can be obtained at a much lower cost.When the above monomer is polymerized to obtain the water-absorbent resin as used in the present and invention, block polymerization and precipitation polymerization can be carried out. However, considering the performance or ease of the polymerization control, it is preferable to carry out an aqueous solution polymerization or inverted phase suspension polymerization using the monomer in the form of its aqueous solution. Incidentally, when the monomer is used in the form of its aqueous solution, the concentration of the monomer in its aqueous solution (hereinafter referred to as the "aqueous monomer solution") is not particularly limited, but is preferably in the range of 10- 70% by weight, more preferably 20-40% by weight. Further, when the polymerization of aqueous solution or the inverted phase suspension polymerization is carried out, a solvent other than water can be used together if necessary, and the kind of solvent as used together is not particularly limited. When the above polymerization is initiated, the following radical polymerization initiators, for example, can be used: potassium persulfate, ammonium persulfate, sodium persulfate, t-butyl hydroperoxide, hydrogen peroxide and dihydrochloride of 2.20- azobis (2-aminodipropane). In addition, a redox initiator is also available by additionally using a producer to promote the decomposition of the above polymerization initiator and to combine both together. Examples of the above reductant include: salts of (bi) sulfuric acid such as sodium sulfite and sodium acid sulfite; L-ascorbic acid (or its salts); reducible metals (or their salts) such as ferrous salts; and amines. However, the reducer is not limited to these. The amount of the above polymerization initiator as used is usually in the range of 0.00-2% mol, more preferably 0.01-0.01 mol%. In the case where the amount of the polymerization initiator is less than 0.001 mol%, there are disadvantages in that a large amount of monomers remains unreacted, so that the amount of monomers, which remains in the water absorbent resin, results in , it increases. On the other hand, in the case where the amount of the polymerization initiator exceeds 2 mol%, there could be disadvantages since the water soluble content in the resulting water absorbing resin is increased. In addition, the polymerization reaction can be initiated by irradiating the reaction system with active energy rays, such as radiation, electron beam, and ultraviolet rays, instead of using the polymerization initiators. Incidentally, the reaction temperature in the above polymerization region is not particularly limited, but is preferably in the range of 20-90 ° C. Moreover, the reaction time is not particularly limited and can be established closely according to factors ta-1 - such as the respective class of polymerization monomers and initiators and the reaction temperature. The water-absorbent resin, used in the present invention, can be a type of self-crosslinking that does not use a crosslinking agent, but is preferably one that is copolymerized or reacted with an internal crosslinking agent having two or more polymerizable unsaturated groups or two or more Reactive groups per molecule. Specific examples of the above internal cross-linking agent include: N, N-met ilenbis (meth) acrylamide, (meth) acrylate (poly) ethylene glycol, di (meth) acrylate (poly) polypropylene glycol, trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, glycerol acrylate methacrylate, trimethylolpropane tri (meth) acrylate denatured with ethylene oxide, pentaetri tol (meth) acrylate, cyanurate of triallyl, triallyl isocyanurate, triallyl phosphate, triallylamin, poly (meth) allylxalkanes, diglycidyl ether of (poly) ethylene glycol, diglycidyl ether of glycerol, ethylene glycol, polyethylene glycol, propylene glycol, - glycerol, pentaerythritol, ethylenediamine, ethylene carbonate , propylene carbonate, polyethyleneimine, and glycidyl (meth) acrylate. These internal crosslinking agents may be used either alone or in combinations with each other. In addition, these internal crosslinking agents can be added to the reaction system either all at once or in a divisional manner. When two or more kinds of internal cross-linking agents are used, it is preferable to essentially use a compound with two or more polymerizable, unsaturated groups, considering the absorption properties of the resulting water-absorbent resin. The use of the internal crosslinking agent allows the soluble contents to be inhibited from eluting the inside of the swollen gel when the swollen gel is exposed to a deteriorating condition. The amount of the internal crosslinking agent, above, as used is preferably in the range of 0.005-2% mol, more preferably 0.02-0.5 mol%, even more preferably 0.03-0.3% _ mol, of the above hydrophilic monomers. In the respective cases, where the amount of the internal crosslinking agent is smaller than 0.005 mol%, and where the amount of the internal crosslinking agent exceeds 2 mol%, the water absorbing resin with the static deterioration absorption capacity dynamic, deterioration absorption index, or substantial absorption capacity at a desired level under a load or water absorbing resin exhibiting excellent resistance to urine can not be obtained. When introduced into the crosslinking structure in the inner portion of the water-absorbent resin using the above internal cross-linking agent, the internal cross-linking agent can be added to the reaction system during or after the polymerization, or after polymerization and neutralization, of the above hydrophilic materials. Incidentally, the above polymerization, the following materials can be added to the reaction system: various foaming agents such as carbonates (or bicarbonates), carbon dioxide, azo compounds, and inert organic solvents; hydrophilic polymers such as starch cellulose, derivative thereof, polyvinyl alcohol, polyacrylic acid (or its salts) and crosslinked polymers of polyacrylic acid (or its salts); several active agents on the surface; and chain transfer agents such as hypophosphorous acid (or its salts). When the water-absorbent resin as obtained by the above polymerization reaction is a gel, the above water-absorbent resin is usually dried, and if necessary, sprayed. The water content (on a wet basis) of the water-absorbent resin, useful in the present invention, is not particularly limited, but is preferably in the range of 1-40% (but not including 40%), more preferably 1-20%, even more preferably 1-10%. In addition, the particle diameter of the water-absorbent resin, within the present invention, is usually in the range of 10-1,000 μm, preferably 50-800 μm, more preferably 75-600 μm (but not including 75 μm), particularly preferably 150-500 μm (but not including 150 μm), on average. The particle shape of the water-absorbent resin as obtained in this way, for example, can be spherical, powdered, or irregular, and is not particularly limited, but those having irregularly pulverized forms, as obtained, and the polymerization step, are preferably used. As regards the water-absorbent resin as obtained by the previous steps of polymerization, drying and pulverization, before cross-linking the surface, it is preferable to use those that exceed a value of absorption capacity of 30 g / g. more, preferably 35 g / g or more, under no load, because the objects of the present invention are markedly marked by this resin. Of course, the above absorption capacity is closely adjusted according to the purpose.

- Addition of Amino-Polycarboxylic Acid The water-absorbing agent of the present invention with the aforementioned parameters can be obtained, for example, by mixing the specific amino-polycarboxylic acid mentioned above and a surface cross-linking agent with the water-absorbent resin, obtained above, resting prior to crosslinking the surface, and when crosslinking the resin, wherein the crosslinking agent on the surface can be reacted at the carboxyl group of the water absorbing resin. The specific amino-polycarboxylic acid useful in the present invention is an aminocarboxylic acid with three or more carboxyl groups or their salt. This amino polycarboxylic acid has a high ion chelation or blocking ability to Fe or Cu, and its constant stability to Fe ions is preferably at least 10, more preferably at least 20. Examples thereof are specified as follows: diethylenetriaminepentaacetate, triethylenetetraminehexacetate, cyclohexane-1,2-dianatetraacetate, N-hydroxyethylenediaminetriacetate, diaminetetraacetate of ethylene glycol diethyl ether, ethylenediaminetetrapropionate, N-alkyl-N'-carboxymethyl-aspartate, N-alkenyl-N0-carboxymethyl-asparatate, and its alkali metal salts, alkaline earth metal salts, ammonium salts, and amine salts. Among these, diethylenetriaminepentaacetate, triethylenetetraminehexacetate, N-hydroxyethylethylenediamine triacetate, and their salts are more preferable, because they have bulky structures or conformations. The amount of the above specific aminocarboxylic acid as used is different according to the surface crosslinking agent as used to crosslink the neighborhood of the surface, but is usually in the range of 0.00001-10 parts by weight, preferably 0.0001 -1 part by weight, per 100 parts by weight of the solid content of the water-absorbent resin. In the case where the amount exceeds 10 parts by weight, the effect corresponding to the use is not obtained, and not only this is economic, but also there are problems since the amount of absorption falls. Further, in the case where the amount is less than 0.0001 parts by weight, the substantial absorption capacity or the static interior under a load is strongly increased. Examples of the surface crosslinking agent useful in the present invention include: polyhydric alcohol compounds such as ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipropylene glycol, 2, 2, -trimethyl- l, 3-pentanediol, polypropylene glycol, glycerol, polyglycerol, 2-butane-1, -diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol , 1,2-cyclohexanol, trimethylolpriopane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol and sorbitol; epoxy compounds such as ethylene glycol diglycidyl ether, polyethylene diglycidyl ether, glycerol polyglycidyl ether, diglyceryl polyglycidyl ether, polyglycidyl ether of poly diglycerol, diglycidyl ether of propylene glycol, diglycidyl ether of polypropylene glycol, and glycidol, polyamine compounds, such as ethylene diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenetetramine and polyethyleneimine, and their inorganic or organic salts (for example, azetidinium salts), polyisocyanate compounds such as 2-tolylene diisocyanate, and hexamethylene diisocyanate, polyoxazole ina compounds such as 1 , 2-ethylenebisoxazoline, alkylene carbonate compounds such as 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2 ona, 4,4-dimeti 1-1, 3-dioxolan-2-one, 4-ethyl-l, 3-dioxolan-2-one, 4-hydroxymethyl-l, 3-dioxan-2-one and 1, 3-dioxopan-2-one; halo-epoxy compounds, such as epichlorohydrin, epibromohydrin, - and α-ethylepichlorohydrin, and their polyamine products, for example, Kymene manufactured by Hercules: registered trademark); silane coupling agents such as β-glycidoxypropyltrimethoxysilane and α-aminopropyltriethoxysilane; and polyvalent metal compounds such as zinc, calcium, magnesium, aluminum, iron and zirconium hydroxides and chlorides. In particular, polyhydric alcohols and alkylene carbonate compounds are preferable considering safety in the case where a portion of the surface crosslinking agent remains unreacted. The surface crosslinking agents, exemplified above can be used either alone or in combination with each other respectively. When two or more surface crosslinking agents are used together with each other, a water absorbing agent with even more excellent absorption properties can be obtained by combining a first and a second surface crosslinking agent having a solubility parameter (values of SP) different from each other. Incidentally, the solubility parameter mentioned above is a value as is commonly used as a factor that shows the polarity of the compounds. The first surface crosslinking agent, mentioned above, is a compound that is reactive in a carboxyl group of the water absorbing resin and has a solubility parameter of 12.5 (cal / cm 3) 1 2. Examples of the first crosslinking agent of surface include ethylene glycol, propylene glycol, glycerol, ethylene carbonate, and propylene carbonate. The second surface crosslinking agent mentioned above is a compound that is reactive in a carboxyl group of the water absorbing resin and has a solubility parameter of less than 12.5. (cal / cm3) 1/2. Examples of the second surface crosslinking agent include polyglycidyl ether glycerol, polyglycidyl ether (poly) glycerol, diglycidyl ether of ethylene glycol, 1,3-propanediol, trimethylolpropane, 1,3-propanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, and 1,4-butanediol. The ratio of the surface crosslinking agent as used to the water-absorbent resin depends on factors such as the combinations of the water-absorbent resin and the surface cross-linking agent, but the usual eij e-is the range of 0.005- 10 parts by weight, preferably 0.05-5 parts by weight per 100 parts by weight of the water-absorbent resin in a dry state. That is, the surface crosslinking agent is used in the above range, the water absorption properties of body fluids (aqueous liquids) such as urine, sweat, and menstrual blood can still be improved. In the case where the amount of surface crosslinking agent as used is smaller than 0.005 parts by weight, the crosslink density of the vicinity of the surface of the water absorbent resin can be heavily increased, and the deterioration capacity static or dynamic, the index of description of deterioration or the capacity of substantial absorption under a load could not be improved. Further, in the case where the amount of the surface crosslinking agent as used exceeds 10 parts by weight, the surface crosslinking agent is excessive, and this ineconomic, and in addition, it may be difficult to control the crosslink density to a value appropriate, so that the ability to absorb dynamic or static deterioration, the rate of deterioration, or the absorption capacity -substantial under a load could not be achieved. In the present invention, it is preferable to use water when the water-absorbent resin is mixed with the specific amino-polycarboxylic acid and the surface cross-linking agent. The amount of water, as used in the present invention, is different according to the kind, particle size, water content of the water-absorbent resin, but is usually in the range of 0.05-10 parts by weight, in Preferably 0.5-3 parts by weight, per 100 parts by weight of the solid content of the water-absorbent resin. In the case where the amount of water as used exceeds 10 parts by weight, the absorption capacity may fall. In the case where the amount of water is smaller than 0.5 parts by weight, it may be more difficult to fix the specific amino-polycarboxylic acid on the surface of water-absorbent resin, so that the absorption capacity of static or dynamic deterioration , the rate of absorption of deterioration, or the capacity of substantial absorption under a load could not be improved.

In addition, the present invention, a hydrophilic organic absorbent can be used - when the water-absorbent resin is mixed with the specific amino-polycarboxylic acid and the surface cross-linking agent. Examples of useful hydrophilic organic solvent include: alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, alcohol, isobutyl, t-butyl alcohol, and propylene glycol, ketones such as acetone; ethers such as dioxane, alkoxy (poly) ethylene glycol, and tetrahydrofuran; amides such as N, N-dimethylformamide; and sulfoxides such as dimethyl sulfoxide. The amount of the hydrophilic organic solvent as used is different from the kind or particle size of the water-absorbent resin, but is usually in the range of 0-10 parts by weight, preferably 0.1-5 parts by weight, per 100 parts by weight of the water-absorbent resin. In the present invention, the mixing of the water-absorbent resin with the specific amino-polycarboxylic acid and the surface cross-linking agent can be carried out in a state where the water-absorbent resin is dispersed in organic solvents such as cyclohexane and pentane. However, subsequent processes (l) - (5), for example, can be preferably exemplified with a means for exhibiting the features of the present invention to the fullest. (1) A process that includes the steps of: mixing the specific amino-polycarboxylic acid and the surface cross-linking agent together; including water and / or the hydrophilic organic solvent, if necessary; and then spray or drip the resulting mixture to the water-absorbent resin, mixing them in this manner. (2) A process that includes the steps of: mixing the water-absorbent resin with the amino-polycarboxylic acid or its aqueous solution; and then spraying or dripping the surface crosslinking agent, including water and / or the hydrophilic organic solvent if necessary, into the resulting mixture. (3) A process that includes the steps of: spraying or dripping the surface crosslinking agent, which includes water and / or the hydrophilic organic solvent if necessary, into the water-absorbent resin, mixing them in this manner; then mix the resulting mixture with the specific amino-polycarboxylic acid with its aqueous solution. (4) A process that includes the steps of: spraying or dripping the surface cross-linking agent and the specific amino-polycarboxylic acid, including water and / or the hydrophilic organic solvent if necessary, into the water-absorbent resin at the same time using a medium such as two nozzles. (5) A process that includes the steps of: adding the specific amino-polycarboxylic acid to the hydrogel of the water-absorbent resin; then dry or dehydrate the hydrogel; and spraying or mixing the resulting dry or dehydrated product with the surface crosslinking agent including water and / or hydrophilic organic solvent if necessary (in this process, the amino-polycarboxylic acid can be further added in the manner of the drying or dehydrating step of the hydrogel) Furthermore, as mentioned above, when the specific amino-polycarboxylic acid and surface cross-linking agent is Mix with the water-absorbent resin, it is preferable to mix a solution thereof as prepared using water or the hydrophilic organic solven.If the specific amino-polycarboxylic acid and the water-absorbent resin are mixed together in the presence of water, then the value of the absorption capacity of static deterioration or the capacity of substantial absorption under a load can be improved.It is incidentally, when water is used for mixing, it can be allowed to co-exist fine particle powders, insoluble in water or an active agent on the surface.The mixing apparatus favorable for the above mixing needs to be able to generate a greater force of mixed to ensure uniform mixing. Preferable examples of the mixing apparatus useful in the present invention include: cylinder type mixers, double wall cone type mixers, high speed agitator type mixers, V character mixers, ribbon type mixers, screw type mixers, mixers type rotary disk of fluidized furnace, gas-type mixers, double-arm mixers, internal mixers, spray-type kneaders, rotary mixers, and screw-type extruders. In the present invention, the specific amino-polycarboxylic acid and surface cross-linking agent are mixed with the water-absorbent resin (preferably, the specific amino-polycarboxylic acid and the surface cross-linking agent are mixed together and then added. to the water-absorbent resin), and the vicinity of the surface of the water-absorbent resin is then crosslinked by further carrying out the heat treatment. When the heat treatment is carried out in the present invention, it is preferable that the treatment temperature is in the range of 80-250 ° C. The heating temperature of less than 80 ° C can not only lengthen the heating treatment time and therefore impairs productivity, but also prevents uniform crosslinking from being achieved and therefore disables the production of a water absorbing agent with excellent absorption capacity of static deterioration, under a load, which is an object of the present invention. Furthermore, in the case where the treatment temperature is higher than 250 ° C, the water-absorbent resin could be damaged, so that it could be difficult to obtain the excellent absorption capacity of dynamic or static deterioration, deterioration absorption index, or the capacity for substantial absorption under a load. The heating treatment can be carried out using conventional dryers or heating ovens, and examples thereof include: channel-type mixing dryers, rotary dryers, bureau dryers, fluidized bed dryers, gas-type dryers, and infrared dryers. In addition, another production process for a water-absorbing agent, according to the present invention, comprises the step of adding the specific amino-polycarboxylic acid, prior to a surface-crosslinked water-absorbing resin, having a capacity of absorption of 23 (g /, g) or more under the load. The surface-crosslinked water-absorbent resin, as used in this case, is generally obtained by mixing the water-absorbent resin, as expected before surface crosslinking and obtained in the above manner, with the agent of cross-linking the anterior surface, thus crosslinking the resin. This water-absorbent, cross-linked resin on the surface needs to have an absorption capacity of 23 (g / g) or more under a load. In the case where the absorption capacity lowers a load is less than 23 (g / g), the absorption capacity of static deterioration under a load does not fall within the range of the present invention, or the respective absolute values of the capacities of The absorption of static and dynamic deterioration and the absorption capacity under a load are lower, so that the absorption of water in diapers can not be carried out sufficiently even if it is considered that they will be used for a prolonged time. The absorption capacity under a load is preferably at least 24 (g / g), more preferably at least 25 (g / g). In the present invention, the specific amino polycarboxylic acid, above, is added to the water absorbing resin, crosslinked on the surface having the absorption capacity of 23 (g / g) or more under a load, but the following process It is preferable. An aqueous solution of specific amino-polycarboxylic acid is prepared, and the particles of the water-absorbent resin are combined together using water as a binder, thereby granulating the resin. The granulation enlarges the average particle diameter of the water-absorbent resin, and improves the hygroscopic flowability of the resin and therefore facilitates the handling of the resin. The amount of water as added is usually in the range of 0.1-20 parts by weight, preferably 0.1-10 parts by weight, more preferably 0.5-4 parts by weight, per 100 parts by weight of the absorbent resin of water . The process for adding the specific amino-polycarboxylic acid and water is not particularly limited, and examples thereof include. A process in which the specific aqueous amino-polycarboxylic acid solution is added to the water-absorbent resin, thereby granulating the resin, and a process in which the specific amino-polycarboxylic acid is added to the water-absorbent resin. , and then water is added to the resin, thereby granulating the resin. A hydrophilic organic solvent, such as methanol, ethanol; Isopropyl alcohol, or propylene glycol, can be used additionally to improve the mixability of the specific amino-polycarboxylic acid and water with the water-absorbent resin. Additionally, an active agent on the surface or inorganic fine particles, such as silica or titanium oxide, can be added in advance simultaneously. The addition of the ion blocking agent (or gelation agent) is not limited to the processes mentioned above. As mentioned, the ion blocking agent (or chelating agent) selected from the specific amino carboxylic acids can be fixed only on the water absorbing surface by mixing the amino-polycarboxylic acid and the surface crosslinking agent with a water-absorbent resin prior to surface crosslinking of the water-absorbent resin, thereby crosslinking the surface of the water-absorbent resin, or adding the amino-polycarboxylic acid and water with a water-absorbent resin, crosslinking the surface, specific, granulating in this way this resin. Because deterioration of the water-absorbent resins occurs from their surfaces, it is preferable that the ion blocking agent (or chelating agent) be placed in the vicinity of the water-absorbing surface. The ion blocking agent (or chelating agent) can be added when the water soluble monomer to form the water absorbing resin is polymerized.

However, in the case where the polymerization of the above monomer is carried out in the presence of the ion blocking agent (or chelating agent), the polymerization of the monomer could be prevented by the ion blocking agent (or chelating agent). ) and therefore could not give the water absorbing resin with excellent absorbency, and additionally, the ion blocking agent (or chelating agent) could lose its ion blocking or chelating capacity. The water absorbing agent, as obtained in the above manner, is a water absorbing agent having excellent properties, as it has never been obtained, since the value of the absorption capacity under no load and the value of the capacity of Absorption of static and dynamic deterioration, the rate of absorption of deterioration, or the capacity of substantial absorption under a load are excellent. This water-absorbing agent is favorably used even for diapers having high concentration of resin and low concentration of pulp that accompanies the thinness of the diapers in recent years, and this agent can further reduce leakage in practical use.

In one of the production processes of the present invention, for example, ion-blocking agent and the surface crosslinking agent that can be reacted in a carboxyl group are mixed with the water absorbing resin, obtained above, having a carboxyl group, whereby the water absorbing agent with excellent urine resistance can be obtained. . Examples of the ion blocking agent, as used in the present invention, include the following compounds: (1) Aminocarboxylic acid and its salts; (2) monoalkylci traduced, monoalkenylci tramites, and their salts; (3) monoalkylmalonamides, monoalkenylmalonamides, and their salts; (4) monoalkyl phosphoric esters, and their salts; (5) N-acylated glutamic acid, N-acylated aspartic acids, and their salts; (6) ß-diketone derivatives; (7) tropolone derivatives; and (8) organic phosphoric acid compounds. With regard to (1) aminocarboxylic acids and their salts, those having at least three carboxyl groups are preferable with respect to their ion blocking capacity. Specific examples thereof include: nitrolotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexacetic acid, cyclohexane-1,2-diaminetetraacetic acid, N-hydroxyethylenediaminetriacetic acid, diaminetetraacetic acid of ethylene glycol diethyl ether, ethylenediaminetetrapropionic acid, N-alkyl- N-carboxymethylaspartic acid, N-alkenyl-N '-carboxy ethylespartic acid, and its alkali metal salts, alkaline earth metal salts, and ammonium salts, and amine salts. (2) Monoalkylcitramides, monoalkenylcitramides, and their salts are obtained, for example, by condensation with dehydration of alcohols with citric acid. (3) Monoalkylmalonamides, monoalkenylmalonamides, and their salts are obtained, for example, by adding α-olefins to methyl malonate and then hydrolyzing the resulting adducts. Examples of (4) monoalkyl phosphoric esters, monoalkenyl phosphoric esters, and their salts include laurylphosphoric acid, and stearylphosphoric acid.

Examples of (5) N-acylated glutamic acids, N-acylated aspartic acids, and their salts include Amisoft HS-11 and GS-11, as are commercially available from Ajino oto Co. , Ltd. Examples of (6) β-diketone derivatives include acetylacetone and benzoylacetone. Examples of (7) tropolone derivatives include tropolone ß-tuj aplicin t? -tuj aplicin. Examples of (8) organic phosphoric acid compounds include ethylidenephosphonic acid, 1-hydroxyethylidene, 1-diphosphonic acid, aminotrimethylenephosphonic acid, and etherendiaminetetra (methylenephosphonic meth) acid. And diethylenetriaminepenta (methylenephosphonic acid). Particularly, hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), and diethylenetriaminepenta (methylenephosphonic acid). Preferable examples of salts of organic phosphoric acid compounds include alkali metal salts such as Na and K, and ammonium salts, and amine salts. The above organic phosphoric acid compound is known as one of the metal blocking agents.

Preferable among the above ion blocking agents are the aminocarboxylic acids having at least three carboxyl groups and their salts, and particularly, the most preferable ones are diethylenetriaminepentaacetic acid, triethylenetetramidohexacetic acid, cyclohexane-1,2-diaminotetraacetic acid, N-acid. -hydroxyethylenediaminetriacetic acid, and its salts with respect to resistance to urine. The amount of the ion blocking agent as used in the present invention is different according to the surface crosslinking agent as used to crosslink the neighborhood of the surface, but the amount is usually in the range of 0.1001-10 parts. by weight, preferably 0.05-3 parts by weight, per 100 parts by weight of the solid content of the water-absorbent resin. In the case where the amount exceeds 10 parts by weight, there are problems because: no effect is obtained that responds to the quantity, it is ineconomic, and in addition, the amount of absorption falls. Furthermore, in the case where the amount is smaller than 0.01 parts by weight, the effect of improving the resistance to urine is not obtained.

The ratio of the surface crosslinking agent, as used, to the water absorbent resin depends on factors such as combinations of the water absorbent resin and the surface crosslinking agent, but is usually in the range of 0.01-10 parts. by weight, preferably 0.05-3 parts by weight, per 100 parts by weight of the water-absorbent resin that is in a dry state. If the surface crosslinking agent is used in the above range, the water absorption properties of body fluids (aqueous liquids) such as urine, sweat and menstrual blood can be further improved. In the case where the amount of the surface crosslinking agent as used is smaller than 0.01 parts by weight, the crosslink density in the surface density of the water absorbent resin can be strongly increased. Further, in the case where the amount of the surface crosslinking agent as used exceeds 5 parts by weight, the surface crosslinking agent is excessive, and this is uneconomical, and further, it can be difficult to control the crosslink density to a appropriate value.

In the present invention, it is preferred to use water when the water absorbing resin is mixed with the ion blocking agent and the surface crosslinking agent. The amount of water, as used in the present invention, is different according to the kind, particle size, or water content of the water-absorbent resin, but is usually in the range of 0.5-10 parts in water. weight, preferably 0.5-34 parts by weight, per 100 parts by weight of the solid content of the water-absorbent resin. In the case where the amount of water as used exceeds 10% by weight, the absorption capacity can fall. In the case where the amount is smaller than 0.5% by weight, it can be difficult to fix the ion blocking agent on the surface of the water-absorbent resin, so that urine resistance can not be improved. All the abovementioned modes for carrying out the mixing and addition of the amino-polycarboxylic acid, without modification but the aforementioned considerations, can be applied to the specific modes for carrying out the mixing of the ion blocking agent and the agent of Surface crosslinking with the water absorbing resin in the production process as mentioned immediately above. If the vicinity of the surface of the water absorbent is crosslinked in the above manner, the soluble contents can be prevented from eluting from within the water absorbent resin. However, when urine is absorbed and thus contains L-ascorbic acid, the water-absorbing resin deteriorates over time because its main chain and cross-linking structure are cut by the actions of L-ascorbic acid and an amount very small heavy metal ions, such as iron or copper, as they are intermingled in the production process for the water-absorbing resin or diapers or are contained in the urine. In particular, the vicinity of the surface of the water absorber deteriorates easily, so that the elution of the soluble contents can be suppressed. Therefore, the absorption of the water-absorbent resin falls over time when the resin absorbs urine. In the present invention, the surface crosslinking agent and the ion blocking agent are mixed with the water absorbing resin, whereby deterioration of the water absorbing resin, especially deterioration of its surface neighborhood, is prevented. , delete the elution of the soluble contents. In another production process of the present invention, the aforementioned water and ion blocking agent are added (for example, by spraying) to the water-absorbent resin (since it has been cross-linked on the surface with the prior art agent). ion blocking mentioned above) to bind the particles of the water-absorbent resin together using water as the binder, thereby making a granulation to give the water-absorbing agent with excellent resistance to urine. The aforementioned water-absorbent resin can be obtained by cross-linking the vicinity of the water-absorbent resin surface as obtained by spraying a monomer, which needs to include an unsaturated carboxylic acid, in the presence of an internal cross-linking agent. The use of the internal cross-linking agent may involve the soluble contents being eluted from within the swollen gel of the resin when the swollen gel is exposed to a condition having a property of deteriorating the gel. The numbering increases the average particle diameter of the water-absorbent resin and improves the hygroscopic fluidity of the resin, thus facilitating its handling. The amount of water, as added, is in the range of 0.1-20% by weight, preferably 0.1-10% by weight, more preferably 0.5-4% by weight, per 100 parts by weight of the water absorbent resin. In the case where the amount of water is smaller than 0.1% by weight, it is difficult to granulate the particles of water-absorbent resin, and in addition, the ion-blocking agent can not be fixed in the vicinity of the surface of the resin water absorbent. Further, in the case where the amount of water is greater than 20% by weight, the water-absorbent resin swells therein to form a gel, so that there is a possibility that the granulation product, as pursued in the present invention, could not be obtained, and that the cross-linked layer of the surface of the water-absorbent resin could be destroyed. In this process, the above water absorbing resin, since it has been surface crosslinked in advance, is recommended to have an absorption capacity of usually at least 20 (g / g) preferably at least 20 (g / g) ), more preferably at least 24 (g / g), for a sodium chloride solution, aqueous 0.9% by weight (physiological sodium chloride solution) under a load of 0.7 psi, because in the case of the absorption capacity under the load is less than 20 (g / g), there is a possibility that water absorbency could not be performed sufficiently in the diapers. The granulation method comprising the addition of the ion blocking agent is not limited in a special way, but examples thereof different from those mentioned above include a method in which the ion blocking agent is added to the absorbent resin of the ion. water, and then water is added, granulating the resin in this way. Hydrophilic organic solvents such as methanol, ethanol, and isopropyl alcohol can be used together for the purpose of improving the miscibility of the water ion blocking agent, and the water absorbing resin. further, active agents on the surface and fine inorganic particles such as silica and titanium oxide can be added beforehand or at the same time. In the present invention, the water-absorbent resin with excellent strength can be further obtained by adding a chelating agent of a specific structure while, and / or after the water-absorbent resin is polymerized in the manner mentioned above. The chelating agent of a specific structure, useful in the present invention, is one or more compounds selected from the group consisting of compounds of the following general formulas (1) and (2) and maleic hydrophilic polymers (including salts) ( 3), where the general formula (1) is: R2 / R * -CH- (CH2) n-CH-N (1) I \ Xi Xi R3 where n, xP and RX-RJ denote the following numbers and structures: n = 0, 1 X1 = COOM1 (M1 = H, Na, K, NH4). R1 = H, OH, Me R2 = H, -CH2COOM2, -CH2CH2COOM2 (M2 = H, Na, K, NH4) > , -CH-CH-R4 I I R3 = -CH2COOM3, -CH2CH2COOM3, M3QOC COOM3 (M3 = H, Na, K, NH4) (R4 = H, OH, Me) and wherein the general formula (2) is: R6 R7 I / R5-CH- (CH2) m-CH-N-CH2-CH2-N (2) X2 X2 R8 wherein: m, X2 and R5-R8 denote the following numbers and structures: m = 0.1 X2 = COOM4 (M4 = H, Na, K, NH4) R5-H, OH, Me Re H, -CH2COOMY -CH2CH2COOMb (M - H, Na, K, NH < R7 = H, -CH2COOMP -CH2CH2C006 (M6-H, Na, K, NH, -CH-CH-R9 R? = -CH2COOM7, -CH2CH2C00M7, M7OOC COOIvP (M7 = H, Na, K, NH4) (R9 = H, OH, Me) Examples of the chelating agent of the general formula (1) above include: N-carboxy-ethyl aspartic acid, N, N-dicarboxymethyl-aspartic acid, N-carbxyethyl-1-aspartic acid, N, N-dicarboxyethyl-aspartic acid , N- (1, 2-dicarboxyethyl) -aspartic acid, N- (1, 2-dicarboxy-2-hydroxyethyl) -aspartic acid, N-carboxymethyl-2-hydroxy-aspartic acid, N, N-dicarboxymethyl acid -2-hydroxy-aspartic acid, N-carboxyethyl-2-hydroxy-aspartic acid, N- (1,2-dicarboxyethyl) -2-hiroxy-aspartic acid, N-carboxymethyl-glutamic acid, N, N-dicarboxymethyl-glutamic acid , N-carboxyethyl-glutamic acid, N, N-dicarboxyethyl-glutamic acid, N- (1,2-dicarboxyethyl) -glutamic acid, N- (1, 2-dicarboxy-2-hydroxyethyl) -glutamic acid, and their salts of sodium, potassium and ammonium. Examples of the chelating agent of the general formula (2) above include: N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine, N, N'-bis (1,2-dicarboxy-2-hydroxyethyl) -ethylenediamine, N, N'-bis (1,2-dicarboxyethyl) -N, N'-dicarboxymethylethylene diamine, N, N'-bis (1,2-dicarboxy-2-hydroxyethyl) -N, N * -dicarboxymethylethylendia ina, and its sodium, potassium and ammonium salts. In addition, examples of the maleic hydrophilic polymers (including salts) (3) include: hydrophilic polymers which are obtained by polymerizing 211-100% mol of maleic acid, fumaric acid, itaconic acid, and its sodium, potassium, and potassium salts ammonium with 0-99% by mol acrylic acid, methacrylic acid, and its salts- sodium, potassium and ammonium and have an average molecular weight of 500-1,000,000; preferably, the hydrophilic polymers obtained by polymerizing 5-100 mol% of maleic acid and its salts with 0-95 mol% acrylic acid and its salts and having an average molecular weight of 1,000-200,000; and 'more preferably, hydrophilic polymers which are obtained by polymerizing 10-50 mol% maleic acid and its salts with 50-90 mol% acrylic acid and its salts and have an average molecular weight of 1,000-100,000. The chelating agents of the general formulas (1) and (2) are preferred among the above chelating agents in view of their safety and biodegradability. The chelating agents of the general formulas (1) and (2) can be favorably used in any form of their optical isomers and racemic modifications. Particularly preferable examples thereof include: N- (1, 2-dicarboxy-2-hydroxyethyl) -aspartic acid, N, N'-bis (21,2-dicarboxyethyl) -ethylenediamine acid, N, N'-bis acid (1,2-dicarboxy-2-hydroxyethyl) -ethylenediamine, and its sodium, potassium and ammonium salts. The amount of the above chelating agent, as used, is not particularly limited, and is different according to the kind and method of addition of the chelating agent, but the amount is in the range of usually 0.00001-30 parts by weight. weight per 100 parts by weight of the water-absorbent resin. Examples of the method of adding the chelating agent to the water-absorbent resin include: (1) (Addition during polymerization): a method in which the chelating agent is added to an aqueous solution of an ethylenically unsaturated, water-soluble monomer , which can form the water-absorbent resin by polymerization. The aqueous monomer solution could contain heavy metals that are eluted from the reaction tubes or vessels or contained in raw materials such as caustic soda. In the case where the polymerization is carried out in the presence of ions of these heavy metals, there is a possibility that water-absorbent resins could be obtained which deteriorate easily when swollen, or that the swollen gel could be easily damaged by heavy, residual metal ions. However, the polymerization of the above monomer in the presence of the above chelating agent could give water absorbing resins with excellent stability of their swollen gels with time. It is preferred that the chelating agent be added in advance to the aqueous monomer solution to carry out the polymerization. However, the chelating agent can be assigned after the initiation of the polymerization. The amount of the chelating agent, as added in the polymerization step, is in the range of usually 0.0000-1 parts by weight, preferably 0.00002-0.1 parts by weight, more preferably 0.00005-0.01 parts by weight, per 100 parts by weight of the solid content of the monomer. In the case where the amount of the chelating agent is smaller than 0.00001 parts by weight, the water-absorbing resin with excellent stability of its swollen gel with time can not be obtained. In the case where the amount of the chelating agent exceeds one part by weight, the polymerization of the monomer can be prevented. (2) (Addition to the polymer gel): A method in which the above chelating agent is. it adds to a hydrogel as obtained by polymerizing an ethylenically unsaturated monomer, soluble in water, which can form a water-absorbent resin by polymerization. The solid content of the hydrogel is generally in the range of 20-90% by weight, the gel to which the chelating agent was added can be dried by conventional means. The drying temperature is preferably 120 ° C or more. The amount of the chelating agent, as added, is in the range of usually 0.00001-30 parts by weight, preferably 0.00005-10 parts by weight, per 100 parts by weight of the solid content of the hydrogel. In the case where the amount of the chelating agent is smaller than 0.00001 parts by weight, the water-absorbing resin with excellent stability of its swollen gel with time can not be obtained. In the case where the amount of the chelating agent exceeds 30 parts by weight, effects that compensate this amount can not be obtained, or the water absorption capacity can decrease instead of increase.

The hydrogel resulting from the polymerization, for example, the hydrogel as obtained by polymerization of aqueous solution, can be dried as a plate. However, considering the drying efficiency or the performance of the water absorption agent to obtain, it is generally preferred to disintegrate or cut the hydrogel in the size of 0.1-100 mm. As regards the shape of the hydrogel, several can be preferably used for the present invention: for example, plate shape, approximately square, irregularly sprayed, spherical, fibrous, rod-shaped, approximately spherical, scaly. The hydrogel resulting from the polymerization can then be neutralized with alkalis. In addition, the chelating agent can be added to the hydrogel as obtained by inverted phase suspension polymerization and organic solvents are dispersed, it can be added in an azeotropic dehydration step. The above chelating agent can be added to the hydrogel at any step before the end of the hydrogel drying. For example, the chelating agent can be added to the hydrogel as it is formed in the reaction vessel, or it can be added in the disintegration step of the hydrogel, or it can be added to the disintegrated hydrogel, or it can be added in the manner of drying. Specifically, the following methods can be exemplified: a method in which the chelating agent is added when the hydrogel is disintegrated with tools such as kneaders or meat knives; and a method in which the chelating agent is added in the vicinity of the inlets of the dryers. The chelating agent can be used in a state where it is powder or dissolved or dispersed or other solvents. In addition, the chelating agent can be coated or sprayed on the surface of the hydrogel. The hydrogel, to which the chelating agent was added, can be dried, for example, with hot air dryers, gas stream dryers, fluidized bed dryers, drum dryers, microwaves, and far infrared rays. The drying temperature is usually 120 ° C or higher, preferably in the range 150-250 ° C, more preferably 160-220 ° C. In the case where the drying temperature is less than 120 ° C, drying takes a too long time, and additionally, the hydrogel is heated in a gel state for a long time and therefore deteriorates easily. (3) (Addition to the water-absorbent resin (case 1)): A method in which the above chelating agent is added (eg, by mixing) to the water-absorbent resin together with the surface cross-linking agent which has two or more functional groups that can react in the functional groups of the water-absorbent resin. • The amount of the above chelating agent, as used in this method, is different according to the surface crosslinking agent as it is used to crosslink the vicinity of the surface, but the amount of the chelating agent is in the range of usually 0.0001-10 parts by weight, preferably 0.0002-5 parts by weight, per 100 parts by weight of the solid content of the water-absorbent resin. In the case where the quantity exceeds 10 parts by weight, there will be problems since: no effect is obtained that rewards this amount, and therefore, there are economic disadvantages, and in addition, the amount of absorption falls. In addition, in the case where the amount is smaller than 0.0001 parts by weight, no effect is obtained to improve the resistance to urine.

As regards the surface crosslinking agent in this method, those which are explained above in the addition of the amino polycarboxylic acid can be used. The ratio of the surface crosslinking agent, as used, to the water absorbent resin depends on factors such as combinations of the water absorbent resin and the surface crosslinking agent, but is usually in the range of 0.01-10 parts. by weight, preferably 0.05-3 parts by weight, per 100 parts by weight of the water-absorbent resin that is in a dry state. If the surface crosslinking agent is used in the above range, the water absorption properties of body fluids (aqueous liquids) such as urine, sweat and menstrual blood can be further improved. In the case where the amount of the surface crosslinking agent as used is smaller than 0.01 parts by weight, the crosslink density in the vicinity of the surface of the water absorbent resin can be greatly increased. Further, in the case where the amount of the surface crosslinking agent as used exceeds 5 parts by weight, the surface crosslinking agent is excessive, and this is uneconomical, and further, it could be difficult to control the crosslink density to a appropriate value. In the present invention, it is preferred to use water when the water-absorbent resin is mixed with the chelating agent and the surface cross-linking agent. The amount of water, as used in the present invention, is different according to the kind, particle size, or water content of the water-absorbent resin, but is usually in the range of 0.05-10 parts by weight, preferably 0.5-10 parts by weight, per 100 parts by weight of the solid content of the water-absorbent resin. In the case where the amount of water as used exceeds 10 parts by weight, the absorption capacity may fall. In the case where the amount is smaller than 0.5 parts by weight, it could be difficult to fix the chelating agent on the surface of the water-absorbent resin, so that resistance to urine can not be improved. All the aforementioned modes for carrying out the mixing, the addition of the amino-polycarboxylic acid, without modification, but the considerations mentioned above, can be applied to the specific modes for carrying out the mixing of the chelating agent and the cross-linking agent of surface with resin. water absorbent in the method (3). (4) (Addition to the water-absorbent resin (case 2)): A method in which the above chelating agent is added to the water-absorbent resin, crosslinked on the surface. A water-absorbent resin, as favorably used, as the surface-crosslinked water-absorbent resin, has an absorption capacity of usually at least 20 (g / g), preferably at least 22 (g / g) , preferably at least 24 (g / g), for an aqueous solution of sodium chloride at 0.89% by weight (physiological sodium chloride solution) under a load of 0.7 psi. In the case where the absorption capacity under the load is less than 20 (g / g), there is a possibility that the water absorbency could not be performed sufficiently in the diapers. The amount of the chelating agent, as used in this method (4), is usually in the range of 0.00001-10 parts by weight, preferably 0.0001-5 parts by weight, per 100 parts by weight the solid content of the water absorbing resin. In the case where the amount exceeds 210 parts by weight, there are problems because: no effect is obtained that compensates the quantity, this is uneconomical, and in addition, the amount of absorption falls. In addition, in the case where the amount is smaller than 0.0001 parts by weight, no effect is obtained to improve the resistance to urine. Examples of the method for mixing the surface-crosslinked water-absorbent resin, above, and the chelating agent together in this method (4) include: a method in which the water-absorbent resin and the water-absorbing agent are mixed together under dry conditions; and a method in which a mixture of the chelating agent with water, an organic solvent, or a mixed solvent of water-organic solvent is added to the water-absorbent resin. In this method (4) is added in the water and the above chelating agent (for example, by spraying) to the water-absorbent resin, crosslinked on the surface to thereby join the particles in the water-absorbent resin together using water as the binder, whereby the resin can be granulated. The granulation increases the average particle diameter of the water-absorbent resin and improves the hygroscopic flowability of the resin, thereby facilitating its handling. The amount of water, as added, is in the range of usually 0-50% by weight, preferably 0.01-10% by weight, per 100 parts by weight of the water-absorbent resin. In the case where the amount of water is smaller than 0.01% by weight, it is difficult to granulate the particles of water-absorbent resin and, in addition, the chelating agent can not be fixed in the vicinity of the surface of the water-absorbent resin. . Furthermore, in the case where the amount of water is greater than 50% by weight, the water-absorbent resin swells inside to form a gel, so that there is a possibility that the granulation product, as pursued in the present invention could not be obtained and that the crosslinked layer of the water absorbing resin surface could be destroyed. The granulation method comprising the addition of the chelating agent is not particularly limited, but examples thereof different from those mentioned above include a method in which the chelating agent is added to the water-absorbent resin, and then the water it is added, granulating in this way the resin. Hydrophilic organic solvents such as methanol, ethanol and isopropyl alcohol can be used together for the purpose of improving the miscibility of the chelating agent, water, and the water-absorbent resin. In addition, active agents on the surface and inorganic fine particles such as silica and titanium oxide can be added beforehand or at the same time. (5) (Addition to the water-absorbent resin (case 3)): A method in which the above chelating agent is added when the fine powders of the water-absorbent resin are coated. In the production steps for the water-absorbent resin, for example, a polymer powder to form a water-absorbent resin could be classified with a screen of the predetermined size, and fine particles as removed from the water-absorbent resin in this. Classification could be added at any step of the production of the water-absorbent resin and thus be recovered. When this recovery of the fine particles is carried out, the chelating agent can be added. As regards the water-absorbent resin, it can be used either on the surface crosslinked and the non-crosslinked on the surface. The particle diameter of the water-absorbent resin, as used for recovery, is not particularly limited, but is generally 300 μm or less, preferably 225 μm or less, more preferably 150 μm or less. The amount of water, as added, is, for example, in the range of usually 0.1-2,000 parts by weight, preferably 10-900 parts by weight, per 100 parts by weight of water-absorbent resin. In the case where the amount of water is smaller than 0.1 parts by weight, recycling is difficult. In the case where the amount is greater than 2,000 parts by weight, the deterioration of the water-absorbing, recycled resin can not be prevented. The amount of the chelating agent, as added, is in the range of usually 0.0001-30 parts by weight, preferably 0.1-10 parts by weight, per 100 parts by weight of the dry, water-absorbent resin. In the case where the amount of the chelating agent is less than 0.00001 parts by weight, it is difficult to obtain the water absorbing agent that exhibits excellent gel stability over time. In the case where the amount of the chelating agent is greater than 30 parts by weight, an effect compensating this amount can not be obtained. The chelating agent may be added either in the form of an aqueous solution to the water-absorbent resin, or to the water-absorbent resin as it is mixed with water. In addition, it is also permissible to mix the water-absorbing agent with the water-absorbent resin under dry conditions and further mix with water with the resulting mixture. The recycling of the fine powders in the water-absorbent resin in the presence of the chelating agent in the above manner can prevent the water-absorbing resin from deteriorating in the recycling.

-Addition of Other Materials- If necessary, several functions can be given to the previous water-absorbing agent by adding the following materials: deodorants, antimicrobial agents, perfumes, various inorganic powders, foaming agents, pigments, dyes, hydrophilic short fibers, plasticizers, sensitive additives under pressure, active agents on the surface, manure, oxidants, reducers, water and salts. Examples of the inorganic powder include inactive substances (eg, inactive to aqueous liquids) such as fine particles of various inorganic compounds and clay minerals. It is preferred that the above inorganic powder has moderate affinity to water and insoluble or poorly water soluble salt. Specific examples thereof include: metal oxides such as silicon hydroxide and titanium oxide, salicylic acid (or its salts) such as natural zeolite and synthetic zeolite; kaolin; talc, clay; and Bentonite. Among these, silicon dioxide and salicylic acid (or its salts) are preferable and silicon dioxide and salicylic acid (or its salts) with average particle diameter of 200 μm or less as measured by The Coulter Counter Method. The ratio of the inorganic powder to the water-absorbent resin depends on factors such as combinations of the water-absorbent resin with the inorganic powder, but is in the range of usually 0.001-10 parts by weight, preferably 0.01-5 parts by weight. weight, per 100 parts by weight of the water-absorbent resin. The method for mixing the water-absorbent resin with the inorganic powder is not particularly limited, and dry mixing methods or wet mixing methods are available, for example, but dry mixing methods are preferred.

-Uses of the Water Absorbing Agent- The water absorbing agent, as obtained in the above manner, is formed in an absorbent article to be compounded, for example (combine) the resin with fibrous materials such as pulp. Examples of the absorbent article include: sanitary materials (absorbent articles for body fluids), such as paper diapers, sanitary napkins, incontinence pads, wound protection materials, and wound healing materials; absorbent articles for pet urine; materials for civil engineering and architecture, such as water retention materials, water cutting materials, packaging materials and hydrogel bags, for construction materials or soil; food items, such as drop-absorbent materials, freshness keeping materials, cold-keeping materials. Various industrial articles, such as oil-water separation materials, materials for preventing dew drops, solidification materials; and agricultural or horticultural articles, such as water retention materials for plants and soil; but the absorbent article is not limited in a special way. Incidentally, the paper diaper is formed, for example, by laminating a backing sheet of liquid impervious material, and the above water absorbent composition, and a topsheet of liquid permeable material in that order and securing them together, and then finishing the laminable product to the resultant with bonds such as folds, (elastic parts) or the tape clamp holders. In addition, the paper diaper may include pants with paper diapers as used to train infants for urination and dirt removal. Subsequently, a detailed explanation is made in the present invention of the absorbent material, which exhibits excellent absorption properties, as a use of the present invention of water-absorbing agent having the parameters mentioned above.

"Absorbent Matter" The water absorbing agent of the present invention, above, is useful in the form of an absorbent material. This absorbent material comprises the water absorbing agent of a base material, fibrous as a hydrophilic fiber. The weight ratio of the water absorbing agent to the total of the water absorbing agent and the fibrous base material is 0.4 or more. In the case where the absorbent material, for example, comprises the water-absorbing agent and the hydrophilic fiber, a constitution of the absorbent material comprising a homogeneous mixture of the water-absorbing agent and the hydrophilic fiber, is preferred, for example, for sufficiently exhibit the effects of the present invention. Examples of this constitution include: a constitution comprising a homogeneous mixture of the water absorbing agent and a hydrophilic fiber; a constitution comprising a layer of a homogeneous mixture of water-absorbing agent and the hydrophilic fiber of a hydrophilic fiber layer as laminated in the preceding layer, a constitution comprising a layer -of homogeneous mixture of the water-absorbing agent and the hydrophilic fiber, a layer of the hydrophilic fiber, and the water absorbing agent as interposed between these layers; in addition a constitution comprising the water absorbing agent as interposed between the layers of the hydrophilic fiber; and still further a constitution comprising a sheet of the water-absorbing agent as formed by combining a specific amount of water with the water-absorbing agent. Incidentally, the constitution of the absorbent material is not limited to the examples mentioned above therein. A preferable water absorbing agent as used for the absorbent material is any of the following: having an absorption capacity of 30 (g / g) or more under no load and static deterioration absorption capacity (1) of 20 ( g / g) or lower under a load, which has an absorption capacity of 30 (g / g) or more, under no load and a dynamic deterioration absorption capacity of 20 (g / g) or more under a load, and having an absorption capacity of 30 (g / g) or more under no load and static deterioration absorption capacity ((4) of 30 (g / g) or more under a load, because these absorbing agents of water can improve the absorptive capacities of the absorbent material in practical use.The reason why it is preferred to use the water absorbing agent having an absorption capacity of 30 (g / g) or more under no load and capacity of static deterioration absorption (1) of 20 (g / g) or more under a load is as follows. l case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when using the water absorbing agent for articles absorbers that include the absorbent material and that have a high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). In addition, in the case where the absorption capacity of static deterioration (1) under a load is less than 20 (g / g), similarly, the absorbent capacities of the absorbent article are insufficient, and the leak and things by the Style are prone to occur, or the absorption actions vary greatly due to factors such as changes in the composition of the liquids that are absorbed, so that stable absorption properties can not be obtained. The static deterioration absorption capacity (1) under a load is preferably 23 (g / g) or more. The reason why it is preferred to use the water absorbing agent having an absorption capacity of 30 (g / g) or more under no load and a dynamic deterioration absorption capacity of 20 (g / g) or more under a Load is as follows. In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and things from use are prone to occur especially when the water absorbing agent is used for absorbent articles that include the absorbent material and that have a high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). Furthermore, in the case where the dynamic deterioration absorption capacity under a load is less than 20 (g / g), similarly, the absorption capacities of the absorbent article are insufficient, and leakage and the like are prone to occur, or the absorption actions vary greatly due to factors such as changes in the composition of the liquids that are absorbed and the dynamic force as applied to the resin, so that stable absorption properties can not be obtained. The dynamic deterioration absorption capacity under a load is preferably 23 (g / g) or more. The reason why it is preferred to use the water absorbing agent having an absorption capacity of 30 (g / g) or more under no load and a static deterioration absorption capacity (4) of 30 (g / g) or the lower a charge is as follows. In the case where the absorption capacity under no load is less than 30 (g / g), the absorption capacities are insufficient, and leakage and the like are prone to occur especially when the water absorbing agent is used for absorbent articles that include the absorbent material and that have a high concentration of resin. The absorption capacity under no load is preferably at least 33 (g / g), more preferably at least 35 (g / g). In addition, in the case where the absorption capacity of static deterioration (4) under a load is less than 30 (g / g), similarly, the absorption capacities of the absorbent article, and the leakage and things by the absorber are insufficient. Style are prone to occur, or absorption actions vary greatly due to factors such as changes in the composition of the liquids that are absorbed, so that stable absorption properties can not be obtained. The static deterioration absorption capacity (4) under a load is preferably at least 32 (g / g), more preferably at least 34 (g / g). Examples of the base, fibrous material mentioned above include hydrophilic fibers, such as: cellulose fibers, for example, mechanical pulp, chemical pulp, semi-chemical pulp, digested pulp, as obtained from wood; and artificial cellulose fibers, for example, rayon, acetates. Among the fibers exemplified above, cellulose fibers are preferred. In addition, the hydrophilic fibers can comprise synthetic fibers such as polyamides, polyesters and polyolefins. Incidentally, the fibrous base material is not limited to the fibers exemplified above. If it is formed into a sheet such as a carpet or mesh or on a belt, the fibrous base material can be easily used as the absorbent layer, mentioned above.

Further, in the case of the ratio of the base, fibrous material such as the hydrophilic fiber in the absorbent material is relatively small, the materials and solvents, specifically, the hydrophilic fibers can be allowed to adhere together using adhesive binders. If the hydrophilic fibers are allowed to adhere together, the strength and shape retention capacity of the absorbent material can be improved before or during the use thereof. Examples of the aforementioned adhesive binders include: heat sealable fibers such as polyolefin fibers (e.g., polyethylene, polypropylene, ethylene-polypropylene, ethylene-propylene, 1-butene-ethylene copolymers); and adhesive emulsions. These adhesive binders can be used either alone or in combinations with each other. The weight ratio of the hydrophilic fiber and the adhesive binder is preferably in the range of 50/50 to 99/1, more preferably 70/30 to 95/5, even more preferably 809/20 to 95/5 . It is preferred that the absorbent material including the water absorbing agent of the present invention above satisfy a static deterioration concentration absorption index of equation (1) below: static deterioration concentration absorption index = < X (1 a) and a = 23 (1) wherein X is the absorption capacity (g / g) under no load of the water absorbing agent; Y is a capacity for absorbing static deterioration (1) (g / g) under a load of the water absorbing agent; and a is the weight ratio of the water-absorbing agent to the total of the water-absorbing agent and the fibrous, base material (a > 0.4). The absorption index of the static deterioration concentration in the present invention is the sum of: the product of the absorption capacity under no load, X (g / g), the water absorbing agent with the weight ratio of the base material, fibrous in the absorbent material; and the product of the static deterioration absorbing capacity (1) under a load, Y (g / g), of the water absorbing agent with the weight ratio of the water absorbing agent in the absorbent material. This static deterioration concentration absorption index is a scale as was recently found by the present inventors as the index for predicting the absorptive capacities of the absorbent material in practical use. If the weight ratio, a, of the water absorbing agent to the total of the water absorbing agent and the fibrous base material is selected together with the water absorbing agent such that the absorption index of the static deterioration concentration of the equation (1) above may be 23 or more, then the amount of absorption in a state near practical use of the resulting absorbent material may be increased. Additionally, the water-absorbing agents of which the absorption capacity under no load, X (g / g), and the absorption capacity of static deterioration (1) under a load, and Y (g / g), gives the value of the absorption index of concentration of static deterioration, same, among themselves, are selected, then the absorbent materials having almost the same amount of absorption with each other in a state close to practical use they can be produced even if their absorption capacity values are different from each other. Furthermore, as mentioned above, the static deterioration absorption capacity (1) under a load in this case is a value as measured by a new, specific evaluation process. As mentioned above, there are many prior art documents which describe the evaluation of the absorption capacity under a load, in which the measurement is generally made in a comparatively short period of time using a liquid with an electrolyte concentration. similar to that of urine. However, in many cases, the actual use time of the diapers extends for a prolonged period of 6 hours or more. Thus, the water absorbing resins or (water absorbing agents), which provide excellent results with respect to the above conventional evaluation points, as has been proposed up to now, do not necessarily exhibit excellent performance in practical use as well. In addition, the urine contains compounds that change (deteriorate) the properties of the resin over time, and the existence of these compounds also greatly influences the absorption actions of the water-absorbent resin in practical use. In addition, the present inventors have clarified that the degree of significance for these properties varies with the weight ratio, a, of the water-absorbing agent to the total of the water-absorbing agent and the fibrous, base material, ie, looking only after the The value of the absorption capacity under a load could not improve the amount of absorption in a state similar to the practical use of the absorbent materials such as paper diapers containing fibrous base materials. For this improvement, it is necessto select the resin such that the rate of absorption and concentration of static deterioration as defined in the present invention can satisfy the value of 23 or more. As regards the absorbent material of the present invention, according to the weight ratio, a, of the water absorbing agent to the total of the water absorbing agent and the fibrous base material, becomes smaller, the capacity of Absorption under no load, X, tends to be more important for water absorbent agents, useful, but, considering the value of the absorption index of concentration of static deterioration, resins having high absorption capacity value (1), of low static deterioration - a charge, Y, can also be used. In addition, as it becomes larger, the static interior absorption capacity (1) under a load, and tends to be more important for water-absorbing agents, useful, but, considering the value of the absorption rate of deterioration concentration Static, resins having a high absorption capacity value under no load, X can also be used. Preferably, when a is 0.4 or more, the effects of the present invention are greatly exhibited. More preferably, a is 0.6 or more. In the case where a is less than 0.4, the differences in the physical properties of some water-absorbing agents are not greatly shown as differences in the performance of the absorbent materials. In the present invention, the weight ratio a, of the water absorbing agent to the total of the water absorbing agent and the fibrous base material, are determined together with the water absorbing agent such that the value of the concentration absorption index of static deterioration in equation (1) will be 23 or more. In the case where the absorption index of static deterioration concentration is less than 23, the amount of absorption in a state similar to the practical use of ordinmatter is low, for example, in the case of paper diapers that include the material Absorbing, the probability of leakage is high. Preferably, the value of the static deterioration concentration absorption index is 26 or more. In addition, even if the value of the static deterioration concentration absorption index is 23 or more, the amount of the water absorbing agent as used is preferably 8 (g) or more. An absorbent article, of which the amount of water absorbing as used is smaller than (8), could lack dry sensation as a product and exhibit a very large amount of absorption. The amount of the water absorbing agent as used is more preferably in the range of 10-20 (g). In addition, the basis weight of the water absorbing agent in the absorbent material is preferably 100 (g / m2) or more. It is also preferred that the absorbent material including the water absorbing agent of the present invention, above, satisfies a dynamic deterioration concentration absorption index of equation (2) below: dynamic deterioration concentration absorption index = X (1 -?) + A? = 23 (2) wherein: X is the absorption capacity (g / g) under no load the water absorbing agent; A is an absorption capacity of the dynamic deterioration (g / g) under a load of the water absorbing agent; Y ? is the weight ratio of the water absorbing agent to the total of the water absorbing agent and the fibrous base material (?> 0.4). The dynamic deterioration concentration absorption index of the present invention is the sum of: the product of the absorption capacity under no load, X (g / g), the water absorbing agent with the weight ratio of the base material, fibrous in the absorbent material; and the product of the absorption capacity, of dynamic deterioration under a load, A (g / g), of the water absorbing agent with the weight ratio of the water absorbing agent in the absorbent material.

This dynamic deterioration concentration absorption index is a scale as was recently found by the present inventors as the index for predicting the absorption capacities of the absorbent material in practical use. If the weight ratio,?, Of the water absorbing agent to the total of the water absorbing agent and the fibrous base material is selected together with the water absorbing agent such that the dynamic deterioration concentration absorption index of the equation (2) above may be 23 or more, then the amount of absorption in a state similar to practical use of the resulting absorbent matter may be increased. Additionally, if the water-absorbing agents, of which the absorption capacity under no load, X (g / g), and the absorption capacity of dynamic deterioration under a load, A (g / g), gives the value of the static absorption concentration absorption index same as the others, are selected, then absorbent materials having almost the same amount of absorption with each other in a similar state to practical use can be produced even if their absorption capacity values are different each. Furthermore, as mentioned above, the absorption capacity of dynamic deterioration under a load in this case is a value as measured by a new specific evaluation process. As mentioned above, there are many prior art documents that describe the evaluation of the absorption capacity under a load, in which the measurement is generally made in a comparatively short period of time using a liquid with a concentration of electrolytes near of urine. However, in many cases, the actual use time of the diapers extends for a prolonged period of 6 hours or more. Therefore, water-absorbent resins (water-absorbing agents), which provide excellent results with respect to conventional, prior evaluation articles, as has been proposed up to now, do not necessarily exhibit the excellent performance of practical use as well. In addition, the urine contains compounds that change (deteriorate) the properties of the resin over time, and the strength of these compounds also greatly influences the absorption actions of the water-absorbent resin in practical use. In addition, because users move in practical use, dynamic forces also act as charges on the resin. In addition, the present inventors have clarified that the degree of significance for these properties varies with the weight ratio,?, The water absorbing agent to the total of the water absorbing agent and the base, fibrous material, that is, looking after only the value of the absorption capacity under a load could not improve the amount of absorption in a state similar to the practical state of the absorbent materials such as paper diapers containing fibrous, base materials. For this improvement, it is necessary to select the resin such that the static deterioration concentration absorption index as defined in the present invention can satisfy the value of 23 or more. As regards the absorbent material of the present invention, according to the relation in weight? from the water-absorbing agent to the total water-absorbing agent and the base material, fibrous becomes smaller, the absorption capacity under no load, X, tends to be more important for water-absorbing agents, useful, but, considering the value of the absorption index of dynamic deterioration concentration, resins can also be used that have a high value of absorption capacity of dynamic deterioration under a load, A. In addition, as it becomes - to be larger?, the absorption capacity of dynamic deterioration under a load, A, tends to be more important for water-absorbent agents, useful, but, considering the value of the absorption index of concentration of dynamic deterioration, resins having a high value of water capacity can also be used. Absorption under no load, X, preferably, when? is 0.4 or more, the effects of the present invention are greatly exhibited. More preferably,? It is 0.6 or more. In the case where? is less than 0.4, differences in the physical properties of some water-absorbing agents are not mostly shown, as differences in the performance of the absorbent materials. In the present invention, the weight ratio,?, Of the water absorbing agent to the total of the water absorbing agent and the fibrous base material is determined together with the water absorbing agent such that the value of the concentration absorption index of Dynamic deterioration of equation (2) will be 23 or more. In the case where the dynamic deterioration concentration absorption index is less than 22, the amount of absorption in a state similar to the practical use of the absorbent material is low.; for example, in the case of paper diapers that include absorbent material, the probability of leakage occurrence is high. Preferably, the value of the dynamic deterioration concentration absorption index is 23 or more. Furthermore, even if the value of the static deterioration concentration absorption index is 23 or more, the water absorbing amount as used is preferably 8 (g) or more. An absorbent article, of which the amount of the water absorbing agent as used is smaller than 8 (g), could lack dry sensation as a product and exhibit a large amount of desorption. The amount of the water absorbing agent as used is more preferably in the range of 10-24 (g). In addition, the basis weight of the water absorbing agent in the absorbent material is preferably 100 (g / m2) or more. The water absorbing agent, as used for the absorbent material of the present invention, preferably has an absorption rate of 20-80 (sec.) And a water-soluble content of 1-15% by weight for the reason as mentioned above to explain the water absorbing agent. Incidentally, it is permissible to offer various functions to the absorbent material or article by additionally adding materials, such as deodorants, perfumes, various inorganic powders, foaming agents, pigments, dyes, hydrophilic short fibers, fertilizers, oxidants, reducers, water, and salts, to the absorbent matter mentioned above.

"Absorbing Article" The water absorbing agent, above of the present invention is useful for the absorbent article. This absorbent article comprises an absorbent layer, which includes the absorbent material, and a surface sheet with liquid permeability and a backing sheet with liquid impermeability. The absorbent layer that is interposed between the surface sheet with liquid permeability and the backing sheet with liquid impermeability. Because the absorbent article comprises the absorbent layer including the absorbent material of the aforementioned constitution, the absorbent article has. the excellent water absorption properties, mentioned above. Specific examples of the absorbent articles include sanitary materials such as paper diapers, sanitary napkins, and so-called incontinence pads, but the absorbent article is not particularly limited. Because the absorbent article has excellent water absorption properties, it can prevent urine from leaking out and can offer the so-called dry sensation in the case where the absorbent article is, for example, a paper diaper. If necessary, it is permissible for an absorption layer, which helps spreading the liquid, and for example, comprising non-woven fabrics, cellulose, or cross-linked cellulose, to be placed on the upper surface of the absorbent layer or on the surface of the absorbent layer. upper backrest of the surface sheet. The constitution of the absorbent layer is not particularly limited if it has the absorbent material mentioned above. At least, the process for producing the absorbent layer is not limited in a special way. In addition, the method for interposing the absorbent layer between the liquid-permeable sheet and the liquid-permeable sheet, specifically, is not particularly limited to the process for producing the absorbent article. The absorbent material, as included in the absorbent layer, comprises the above water absorbing agent of the present invention and the fibrous base material. The explanation of the respective amounts of material, constitutions, weight ratios, and other properties of the water absorbing agent and the fibrous base material are omitted in this portion of the specification because they are the same as those mentioned above to explain the absorbent material. The aforementioned sheet with liquid permeability (hereinafter referred to as the liquid permeable sheet) comprises a material that is permeable with aqueous liquids. Examples of the liquid permeable sheet forming material include: non-woven fabrics, woven fabrics; synthetic resin films, porous polyethylene, polypropylene, polyester, polyamide. The aforesaid sheet with liquid permeability (hereinafter referred to as the liquid impervious sheet) comprises a material that is impermeable by aqueous liquids. Examples of the material forming the liquid impervious sheet include: polyethylene synthetic resin films, polypropylene, ethylene vinyl acetate, polyvinyl chloride, films of combined materials of these synthetic resins with non-woven fabrics; films of combined materials of the synthetic resins mentioned above with woven fabrics. Incidentally, the liquid permeable sheet can be permeable with steam. Incidentally, it is permissible to offer various functions to the absorbent material or article by additionally adding materials such as deodorants, perfume, various inorganic powders, foaming agents, pigments, dyes, hydrophilic short fibers, fertilizers, oxidants, reducers, water and salts, the absorbent matter mentioned above. The absorbent article of the present invention includes a water absorbing agent having an absorption capacity of 30 (g / g) or more under no load and a substantial absorption capacity (2) of 20 (g / g) or lower a load, and additionally this absorbent article has a substantial concentration absorption index of 23 or more, wherein when the absorption capacity under no load of the water absorbing agent is referred to as X (g / g) and when the absorption capacity is substantial (2) under a load of the water absorbing agent is referred to as Z (g / g) and when the weight ratio of the water absorbing agent to the total of the water absorbing agent and the base, fibrous material is referred to as β, the Substantial concentration absorption index is shown by equation (2) below: Substantial concentration absorption index = X (1 - ß) + Zß (2) The substantial concentration absorption index in the present invention is the sum of values as given by multiplying the absorption capacity under no load, X (g / g), and the substantial absorption capacity (2) under a load, Z (g / g), of the water-absorbing agent by specific ratios respectively, and these specific ratios determine from the weight ratio, β, of the water-absorbing agent to the total of the water-absorbing agent and the base material, -fibrous .

If the weight ratio, β, of the water absorbing agent to the total of the water absorbing agent and the fibrous base material is selected together with the water absorbing agent such that the substantial concentration absorption index of the equation (2) ) above can be 23 or more, then the amount of absorption in a state similar to practical use of the resulting absorbent article can be increased. Additionally, if the water absorbing agents, of which the absorption capacities under no load, X (g / g), and the capacities of substantial absorption (2) under a load (g / g), gives the value of the absorption index of the same substantial concentration, with each other, are selected, then the absorbent articles that have almost the same amount of absorption among themselves in a state similar to practical use can occur even if their absorption capacity values are different from each other. Furthermore, as mentioned above, the substantial absorption capacity (2) under a load in this case needs to be a value as measured by a new specific evaluation process. As mentioned above, there are many prior art documents that describe the evaluation of absorption capacity under a load, in which the measurement is generally made in a comparatively short period of time using a liquid with a similar electrolyte concentration to that of urine. However, in many cases, the actual use time of the diapers extends for a prolonged time of 6 hours or more. Therefore, the water-absorbent resins (water-absorbing agents), which provide excellent results with respect to the lower conventional evaluation points as proposed so far, do not necessarily exhibit excellent performance in practical use as well. In addition, the present inventors have clarified that the degree of significance for these properties varies with the weight ratio, ß, of the water-absorbing agent to the total of the water-absorbing agent and the base, fibrous material, ie, looking after only the value of absorption capacity under a load could be improved the absorption capacity in a state similar to the practical use of absorbent articles such as paper diapers containing fibrous, base materials. For this improvement, it is necessary to select the resin such that the substantial concentration absorption index as defined in the present invention can satisfy the range of the present invention. The absorbent article of the present invention comprises an absorbent material of which the weight ratio of the water absorbing agent to the total of the water absorbing agent and the fibrous base material is β. When ß is small, the absorption capacity under a load, X tends to be more important for water absorbent agents, useful, but, considering the value of the absorption index, of substantial concentration, resins having a high capacity value Substantial absorption (2) under a load, Z, can also be used. Furthermore, when ß is greater is large, the substantial absorption capacity (2) under a load, Z, tends to be more important for water-absorbing agents, useful, but, considering the value of the absorption index of substantial concentration, also it is possible to use resins having an absorption capacity value under no load, X. Preferably, when ß is 0.4 or more, the effects of the present invention are greatly exhibited. Preferably, β is 0.6 or more. In the case where ß is less than 0.4, the differences in the physical properties of some water-absorbing agents are not greatly displayed, as differences in the performance of the absorbent articles. In the present invention, the weight ratio, ß, the water absorbing agent to the total water absorbing agent, the base, fibrous material, is determined such that the value of the substantial absorption index of equation (2) will be 23 or plus. In the case where the absorption index of substantial concentration is less than 22, the amount of absorption in a state similar to practical use of the absorbent article is low, and when the absorbent article is, for example, a paper diaper, the plurality of Leak occurrence is high. Preferably, the value of the absorption index of substantial concentration is 26 or more. In addition, even if the value of the absorption index of substantial concentration is 23 or more, the amount of the water absorbing agent as used is preferably 8 (g) or more. An absorbent article, in which the amount of water absorbing agent as used is smaller than 8 (g) It may lack the dry feeling as a product and exhibit a very large amount of absorption. The amount of the water absorbing agent as used is more preferably in the range of 10-20 (g). In addition, the basis weight of the water absorbing agent in the absorbent material is preferably 100 (g / m2) or more. This absorbent article of the present invention can be easily produced by using the water absorbing agent of the present invention which satisfies the parameters mentioned above such as absorption capacity under no load, absorption capacity of deterioration under a load, absorption capacity of shear stress of deterioration under a load, and substantial absorption capacity under a load. In addition, as regards the absorbent article of the present invention, an absorbent layer comprising the aforementioned absorbent material is interposed between a liquid-permeable surface sheet and a liquid-impermeable backsheet, but it is permissible that a layer diffusion, which aids in the diffusion of a liquid, and for example, comprising non-woven fabrics, celluloses, or cross-linked cellulose, is placed on the upper surface of the absorbent layer or on the back or top surface of the sheet surface.

The absorbent article of the present invention comprises the absorbent layer that includes the absorbent material of the aforesaid constitution and is interposed between the sheet with liquid permeability and the sheet with liquid impermeability. Then, because the absorbent article comprises the absorbent layer including the absorbent material of the aforementioned constitution, the absorbent article has the excellent water absorption properties mentioned above. Specific examples of the absorbent article include sanitary materials such as paper diapers, sanitary napkins, so-called incontinence pads, but the absorbent article is not specially limited. Because the absorbent article has excellent water absorption properties, it can prevent urine from leaking and may offer the so-called dry sensation in the case where the absorbent article is, for example, a paper diaper. The aforementioned sheet with liquid permeability (hereinafter referred to as a liquid permeable sheet) comprises a material that is permeable with aqueous liquids. Examples of the material forming the liquid permeable sheet include: non-woven fabrics, woven fabrics, synthetic resin films, porous polyethylene, polypropylene, polyester, polyamide. The aforesaid sheet with liquid impermeability (hereinafter referred to as the liquid impervious sheet) comprises a material that is impermeable with aqueous liquids. Examples of the liquid permeable sheet forming material include: synthetic polyethylene film, polypropylene, ethylene vinyl acetate, polyvinyl chloride; films of combined materials of these synthetic resins with non-woven fabrics, films and composite materials of synthetic resins mentioned above with woven fabrics. Incidentally, it can be permeable, by the liquid permeable sheet. The constitution of the absorbent layer is not particularly limited if it has the absorbent material mentioned above. In addition, the process for producing the absorbent layer is not limited in a special way. In addition, the method for interposing the absorbent layer between the liquid permeable sheet and the liquid impervious sheet, specifically, the process for producing the absorbent article, is not particularly limited. Incidentally, it is permissible to offer various functions to the material or absorbent article by additionally adding materials, such as deodorants, perfume, various inorganic powders, foaming agents, pigments, dyes, hydrophilic short fibers, fertilizers, oxidants, reducers, water and salts, to the absorbent material mentioned above.

"Process of Measurement of Property Absorption" A process for measuring absorption property, according to the present invention, is a new evaluation process characterized in that a liquid containing a reducible substance is used as a liquid to be absorbed in a process to measure at least an absorption property selected from the group consisting of: absorption properties under a load of a water absorbing agent; absorption properties of an absorbent material of which the weight ratio of a water-absorbing agent to the total of the water-absorbing agent and the fibrous-base material is 0.4 or more, and absorption properties of an absorbent article that includes the material Previous absorbent. Examples of the reducible substance as used above include: L-ascorbic acid; salts of ascorbic acid such as sodium L-ascorbate; isoascorbic acid, salts of isoascobic acid; salts of (bi) sulfuric acid such as sodium sulfite and sodium hydrogensulfite, reducible metals (or salts thereof) such as ferrous salts and amines. L-ascorbic acid (or its salts) and isoascorbic acid (or its salts) are preferred. The concentration of liquid containing the reducible substance is different according to the kind-of the reducible substance as used or in accordance with the proposed form of use, but is usually in the range of from about 0.001 to about 0.5% by weight when L-ascorbic acid is used, for example, as the reducible substance. The liquid to be absorbed is not particularly limited if it contains the reducible substance, but examples thereof include artificial urine, physiological sodium chloride solution, and human urine.

As for the conditions under which the absorption properties of the water absorbing agent, the absorbent material and the absorbent article are measured, it is preferred that they are measured at a temperature of for example 34-42 ° C, more preferably 35-39 ° C, and in the presence of oxygen, for the purpose of predicting the absorption actions of the absorbent article in practical use. The absorption properties of the water absorbing agent, as measured by the measurement process of the present invention, include all absorption properties under a load, in which examples include the absorption capacity under a load and the permeability to liquids under a load. The present invention is especially useful for measuring the absorption capacity under a load. The conditions for measuring the absorption capacity under a load may, except the need for the step of absorbing the previous liquid containing the reducible substance, be those where the factors, such as loading conditions, resin weight, particle size of resin, and presence or absence of liquid diffusion conditions are optimized considering the proposed form of use in the measurement processes for the conventional absorption capacity under a load and the diffusion absorption capacity under a load as described in documents such as EP 339,461, EP 605,150, EP 640,330 and EP 712,659. In a preferable embodiment, the resin is allowed to absorb the liquid containing the reducible substance and is then reposed in a stationary manner for a predetermined time, preferably 1-12 hours, and then the absorption capacity is measured under a load, because the absorption actions in practical use can be judged in this way more correctly. Examples of measuring liquid permeability under a load include measuring the permeability of the gel under a load as described in WO 95/26209. The absorption properties of the absorbent material, as measured by the measurement process of the present invention, include all the absorption properties under no load and under a load, of which the examples include the absorption property (amount of absorption ) of the absorbent material under a load as described in WO 95 &; 26209, EP 339,461; and EP 712,659, and the wet absorption or return rate of the absorbent material under a load as described in EP-761,241. The absorption properties of the absorbent article, as measured by the process of measurement of the present invention, include all absorption properties under no load and under a load, of which examples include the rate of absorption and the amount of the absorbent article as described in EP 339,461, and the absorption property ( amount of absorption) of the absorbent article as described in EP 712,659. By the measurement process of the present invention, the water absorbing agent, the absorbent material, and the absorbent article exhibiting almost stable melting actions despite variations in the liquid to be absorbed can be designed, selected and collected. In addition, the measurement process of the present invention can be preferably used for quality management on the production side of the water-absorbent resin.

"Effects and Advantages of the Invention" The water absorbing agent, of which the absorption capacity under no load and the absorption capacity of static and dynamic deterioration under a load satisfy the respective values as specified in the present invention, has absorption properties that are stable to any composition urine and show little change over time. Therefore, this water-absorbing agent is still favorably used for absorbent articles having a high concentration of resin. The above water-absorbing agent is preferably obtained by adding the ion-blocking agent and / or the chelating agent to a water-absorbent resin in a specific manner, by adding the ion-blocking agent and / or the chelating agent to the water-absorbing resin. a specific water-absorbing resin, and by mixing them, or by adding the chelating agent of a specific structure to a water-absorbent resin, so that this water-absorbing agent suffers little deterioration due to urination over time and exhibits excellent properties of absorption.

The absorbent article of the present invention is specified by the static absorption decay concentration absorption index considering the resin concentration, so that this absorbent article exhibits a high amount of always stable absorption, especially, a high amount of absorption up to that leakage occurs in a state- very similar to practical use. The process of measuring the absorption property of the present invention allows easy and accurate prediction of the absorption actions of the water absorbing agent or the absorbent article in practical use, so that this process is very useful for producing an agent Water absorbent or absorbent article, which exhibits excellent absorption properties.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Subsequently, the present invention is specifically illustrated by the following examples of some preferred embodiments compared to comparative examples not according to the invention. However, the invention is not limited to these examples. Incidentally, the performances of the water absorbing agent were measured by the following methods: (a) Absorption Capacity Under No Load First, 0.2 g of the water absorbing agent (water-absorbent resin) was uniformly placed in an elaborate bag of non-woven fabric (60 mm x 60 mm) and then immersed in an aqueous solution at 09.9% sodium chloride (solution physiological sodium chloride). Sixty minutes later, the bag was removed and then filled to 250 G for 3 minutes with a centrifuge, and Wi weight (g) of the bag was then measured. On the other hand, a procedure was carried out not using the water absorbing agent, and the resulting weight W0 (G) was measured. In this way, the absorption capacity (g / g) was calculated under no load, from its weights i and W0 according to the following equation: Absorption capacity (g / g) =. { (Wa weight (G) - weight W0 (G) / (weight (G) of the water absorbing agent)} - 1. (b) Absorption Capacity Under Load The absorption capacity under a load was measured under a load of 50 g / cm2 in accordance with ABSORBENCY AGAINST PRESSURE, ABSORBENCY III 442.1-99 (October 1997) of EDANA. That is, 0.9 g of the water-absorbing agent (water-absorbent resin) was evenly spread on a 4500 mesh steel wire net (mesh size: 38 μm) as it is melt-bonded to the bottom of a plastic backing. inner diameter of 60 mm. Then, a piston (cover plate) (which has an outer diameter only a little smaller than 60 mm and does not make a separation with the wall surface of the support cylinder, but is not prevented from moving up and down) it is mounted in the water absorbing agent, and the total weight (Wa (g)) of the support cylinder, the water absorbing agent and the piston is measured. Then, a charge, as it is adjusted to uniformly apply a load of 50 g / cm2 (including the weight of the piston) to the water absorbing agent, it is mounted on the piston, thereby ending an assembly of the measuring apparatus. A 90 mm diameter glass filter is mounted inside a 150 mm diameter petri dish, and 0.9% by weight aqueous sodium chloride solution is added to the same level as the upper surface of the filter. glass, in which a filter paper with a diameter of 9 cm (No. 2, made by Toyo Filter Paper Co., Ltd) is then mounted so that its wet surface is wetted, and then the excess liquid is removed. The assembly of the above measuring apparatus is mounted on the wet, anterior filter paper, thereby allowing the water absorbing agent to absorb the liquid under a load. After the liquid surface has descended below the top of the glass filter, the liquid is operated to keep the level of the liquid surface constant. After 1 hour, the assembly of the measuring apparatus is removed when lifting, and the weight (Wb g) (the total weight of the supporting cylinder of the water absorbing agent, swelling and the piston) is measured again as when it is free of charge. load. In this way, the absorption capacity (g / g) under a load was calculated from the previous weights Wa and Wb according to the following equation: Absorption capacity under a load (g / g) = (Wb (g) - Wa (g)) / (weight of the water absorbing agent) (g). (c) Absorption capacity of static deterioration (1) under a load: The absorption capacity of static deterioration (1) under a load was measured, using the same measuring apparatus as described in the previous point of the absorption capacity under a load. The measurement process is described below. First of all, 0.9 g of the water-absorbing agent (water-absorbent resin) is uniformly spread inside the support cylinder, specifically, in the 400-mesh steel wire net, and the weight as given by adding to this the Anterior piston (cover plate) is referred to as Wl (g). Then, 13.5 g of a 0.9% by weight aqueous solution of sodium chloride, containing L-ascorbic acid at a concentration of 0.005% by weight, in the 90 mm diameter Petri dish, as prepared in a manner separate, in which the support cylinder, with the water-absorbing resin, above, spread in the bottom wire net and provided without load, then assembled, thus allowing the resin to uniformly absorb the aqueous solution to 0.9% by weight of sodium chloride containing L-ascorbic acid at a concentration of 0.005% by weight in the Petri dish and to thereby form a gel as it swells 15 times and then stand stationary at 37 ° C for 6 hours. After 6 hours, the previous piston (cover plate) and the load, as adjusted to uniformly apply a 5 / cm2 plate to the swollen, water-absorbing agent, above, are mounted in the water-absorbing agent, swollen in this order. Then, a 909 mm diameter glass filter is mounted inside a Petri dish of 150 mm in diameter, and an aqueous 0.9% by weight sodium chloride solution is added at the same level as the surface of the glass filter. , in which a 9 cm filter paper (No. 2 made by Toyo Filter Paper Co., Ltd) is then mounted so that its entire upper surface will be wetted, and the excess liquid is removed.

Then, the above assembly of the measuring apparatus, applying a pressure to the gel as it is swelled 15 times, is mounted to the wet filter paper, above, thus allowing the gel to absorb the liquid under a load. After the liquid surface has dropped below the top of the glass filter paper, liquid is added to keep the level of the liquid surface constant. After 1 hour, the assembly of the measuring apparatus is lifted to be removed in this way from the filter paper, and then released from the load to measure the resulting weight (W2 (g)). Then, the static deterioration absorption capacity (1) under a load was calculated from the previous weights W1 and W2 according to the following equation: Static impairment absorption capacity (1) under a load (g / g) = (2 (g) - Wl (g)) / (weight of water absorbing agent) (g / g). (d) Static deterioration absorption capacity (2) under a load: The static deterioration absorption capacity (2) under a load was calculated in the same way as the previous measurement of static deterioration absorption capacity (1) under a load, except that the duration of 6 hours for which the gel , as it was inflated to 15 times, it was allowed to stand stationary was changed to 2 hours. (e) Static deterioration absorption capacity (3) under a load: The absorption capacity of static deterioration (3) under a load was calculated in the same manner as the aforementioned one of the static deterioration absorption capacity (2) under a load, except that the concentration, 0.005% by weight, of the acid L-ascorbic in the physiological sodium chloride solution was changed to 0.005% by weight (f) Static deterioration absorption capacity (4) under a load: The absorption capacity of static deterioration (4) under a load was calculated in the same way as the previous measurement of the static deterioration absorption capacity (1) under a load, except that the concentration, 0.005% by weight, of the acid L-ascorbic in the physiological solution of sodium chloride was changed to 0.5% by weight, and that the load of 50 g / cm2 to uniformly apply the water absorbing agent was changed to 20 g / cm2. (g) Dynamic deterioration absorption capacity under a load: First, 0.9 g of the water-absorbing agent (water-absorbent resin) was placed in a 5 cm x 10 cm polyethylene bag, and then 13.5 of a solution as prepared by dissolving L-ascorbic acid was added to the bag. in an aqueous solution at 0.9% by weight of sodium chloride (% by weight is based on the weight of the solution) at a concentration of 0.005% by weight, thereby preparing a gel as it was swelled 15 times, and then the bag was sealed. The temperature of the resulting sealed product was maintained at 37 ° C for, 4 hours. Subsequently, the air was extracted from the bag. The bag was sealed again, dynamic damage was done to the gel with a 5 kg weight roller (diameter 9 cm, width 20 cm) together with the bag when the roller was run back and forth 50 times to 5 seconds per revolution. The gel, to which the dynamic damage has been done in the above manner, was taken out of the bag, and the absorption capacity of this gel under a load was measured with the same measuring device as indicated in the previous point (b) ) of the absorption capacity under a load, and the resulting measurement value was considered as the absorption capacity of static deterioration under a load. The process was as follows. The dynamically damaged gel, removed from the previous bag, was evenly spread within the support cylinder, specifically, the 400 mesh steel wire net, and the weight was measured (WA (g)) as it is when adding to it the anterior piston (cover plate). Then, a load was mounted on the piston, as it is adjusted to uniformly apply a load of 50 g / cm2 (including the weight of the anterior piston) to the gel. Then, a 90 mm diameter glass filter was mounted inside a Petri dish of 150 mm diameter, and a 0.9% by weight aqueous sodium chloride solution was added to the same level as the filter surface of glass, on which a filter paper with a diameter of 9 cm (No. 2 made by Toyo Filter Paper Co., Ltd.) was then mounted, such that its entire upper surface of the filter paper will moisten and remove excess liquid. . Then, the anterior assembly of the prior apparatus of the measuring apparatus, by applying a pressure to the gel as it swells 15 times, was mounted on the wet, anterior filter paper, thereby allowing the gel to absorb the liquid under a load. After the liquid surface has fallen below the top of the glass filter the liquid was added to keep the level of the liquid surface constant. After 1 hour, the assembly of the measuring apparatus was lifted to be removed in this way from the filter paper, and then released from the load to measure the resulting weight (WB (g)) again. Then, the absorption capacity of static deterioration under a load was calculated from the previous weights WA and WB according to the following equation: - absorption capacity of dynamic deterioration under a load (g / g) = ( WB (g) - WA (g) + 13.5) g / (weight of the water absorbing agent) g. (h) Dynamic absorption capacity under load: The dynamic absorption capacity under a load was calculated from the previous weights WA and WB according to the equation mentioned below in the same way as the previous measurement (g) of the dynamic deterioration absorption capacity under a load, except that an aqueous solution at 0.9% by weight of sodium chloride (by weight is based on the weight of the solution) free of L-ascorbic acid was used as the solution to swell the water-absorbing agent before doing the dynamic damage, and that the sealed product of the gel as swelled 15 times was maintained at 37 ° C for 30 minutes.

Dynamic absorption capacity under load (g / g) = - (WB (g) - WA (g) + 13.5) g / (weight of the water absorbing agent) g. (i) Substantial absorption capacity (1) under a load: The substantial absorption capacity (1) was measured under a load using the same measuring apparatus as described in the previous point of the absorption capacity under a load. The measurement process is described later. First of all, 0.9 g of the water-absorbing agent is spread evenly (water-absorbent resin) within the support cylinder, specifically, the steel mesh network of 400 mesh, and the weight as given by adding this the anterior piston (cover plate) is referred to as Wl (g). Then, 13.5 g of a 0.9% by weight aqueous solution of sodium chloride are added in a 909 mm diameter petri dish as prepared separately, in which the support cylinder, with the water-absorbent resin, above , spread in the bottom wire net and one provided with filler, then assembled, thereby allowing the resin to uniformly absorb the 0.9% by weight aqueous solution of sodium chloride in the Petri dish to thereby form a gel as it swells 15 times and then to stand stationary at 37 ° C for 2 hours. After 2 hours, the anterior piston (cover plate) and the load, as adjusted to uniformly apply a load of 50 g / cm2 to the swollen, water-absorbing agent, above, are mounted in the swollen, water-absorbing agent , in this order. Then, a glass filter of 8909 mm in diameter is mounted inside a Petri dish of 150 mm in diameter, and is added to a solution of sodium chloride, aqueous at 0.9% by weight up to the same level as the surface of the glass filter, on which is then mounted a 9 cm diameter filter paper (No. 2 made by Toyo Filter Paper Co., Ltd) that its entire upper surface will be wetted, and the excess liquid is removed. Then, the above assembly of the measuring apparatus, applying a pressure to the gel as it is swelled 15 times, is mounted to wet, anterior filter paper, thereby allowing the gel to absorb the liquid under a load. After the liquid surface has fallen below the top of the fluid filter, the liquid is added to keep the level of the liquid surface constant. After 1 hour, the assembly of the measuring apparatus is lifted to be thus removed from the filter paper, and then released from the load to measure the resulting weight (W2 (g)) again. Then, the substantial absorption capacity (1) under a load was calculated from the previous weights W1 and W2 according to the following equation: Substantial absorption capacity (1) under a load (g / g) = '(W2 (g) - Wl (g) / (weight of water absorbing agent) (g). (j) Substantial absorption capacity (2) under a load: The substantial absorption capacity (2) under a load was calculated in the same manner as the previous measurement and the substantial absorption capacity (1) under a load, except that the duration of 2 hours for which the gel, as it swells 15 times stationary standing was changed to 6 hours. (k) Absorption speed: The measurement of the absorption rate was carried out in accordance with JIS K7224. Next, the process is described. First, 50.0 g of physiological sodium chloride solution (0.9% by weight aqueous solution of sodium chloride) were placed, as adjusted for 30 minutes, and a stirring piece (having a central diameter of 8 mm, a diameter of 7 mm, and a length of 30 mm and it has been coated with fluororesin) in a 100 ml beaker with a flat bottom as regulated by JIS R3503, and then stirred at a speed of 600 rpm with a shaker magnetic. Then, 2 g of the water absorbing agent is added to the beaker, so that the gelation was caused by the swelling action and when the fluidity decreased and finally the vortex of water from the mixing center disappeared, specifically, when a being invisible the piece of agitation, it was preferred as the final point. The time, from the addition of the sample to the disappearance of the vortex, was measured and considered as the speed of absorption. (1) Water soluble content First, 0.500 g of water-absorbent resin was dispersed in 1,000 ml of deionized water and stirred for 16 hours, and then filtered with filter paper. Then, 50 g were placed in the resulting filtrate in a 100 ml beaker, and 1 ml of a 0.1 N aqueous sodium hydroxide solution, 10.00 ml of a solution of chitosan of methyl glycol, aqueous, N / 200 , and 4 drops of a solution of Toluidine blue, aqueous at 0.1% by weight, were added to the filtrate. Then, the solution resulting from the beaker was subjected to the trituration of colloid with aqueous solution of potassium polyvinyl sulfate N / 400 to determine the amount of titration Y (ml) assuming that the time at which the color of the solution changed from blue to red purple was the completion of the titration. In addition, the titration amount Z (ml) was determined by carrying out a blank titration in the same manner as mentioned above, except that the 50 g of the filtrate was replaced with 50 deionized water. Then, the water-soluble content (% by weight) was calculated from the titration amounts Y and Z and from the neutralization ratio W (mol%) of the acrylic acid, as provided for the production of the resin Absorbent water, according to the following equation: water soluble content (% by weight) = (Z (ml) - Y (ml)) x 0.01 x 72 x (100-S in mol)) + (94W (% in mol) / 100). (m) Water content (on a wet basis) About 1 g of water-absorbent resin was heated in a 105 ° C oven for 3 hours, and the weight W (g) of the water-absorbent resin before and after heating was measured, and the water content was calculated ( % by weight) (on a wet basis) according to the following equation: water content (% by weight) = (Wantes (g) - Wdespues (g) / Wantes (g) where: Wantes is the weight of the resin Water absorbent before drying; Water is the weight of the water absorbing resin after drying.

EXAMPLE 1 A reaction solution was prepared by dissolving 9.25 g of polyethylene glycol diacrylate (average molar number of added ethylene oxide: 8) in 5,500 g of an aqueous solution of sodium acrylate with a neutralization ratio of 65 mol% (monomer concentration) : 30% by weight). Then, this solution was degassed under a nitrogen gas atmosphere for 30 minutes, and then it was supplied in a reaction vessel as prepared by plugging a double-arm type kneader, made of stainless steel and a capacity of 10 liters having two sigma vanes and a jacket. While the reaction solution is maintained at 30 ° C, the atmosphere within the system was replaced with a nitrogen gas. Then, while stirring the reaction solution, 1.91 g of 2,2'-azobis (2-amidinopropane) dihydrochloride, 0.96 g of sodium persulfate, and 0.10 g of L-ascorbic acid were added so that a reaction was initiated of polymerization about 1 minute later. The polymerization was carried out at 30-80 ° C, and the resulting hydrogel polymer was removed 60 minutes after the start of the polymerization. The resulting hydrogel polymer had a finely divided diameter of about 5 mm. This finely divided hydrogel polymer was spread on a 50 mesh wire mesh and dried at 150 ° C with hot air for 90 minutes. Then, the resulting dry product was pulverized with a vibration mill and further classified with a 20-mesh wire net, thereby obtaining precursor (a) of water-absorbent resin as the irregular shape is sprayed with an average diameter of 300 μm particle. A surface crosslinking agent, comprising 0.005 parts by weight of pentasodium diethylenetriaminepentaacetate, 1 part by weight of propylene glycol, 0.05 parts by weight diglycidyl ether of ethylene glycol, 3 parts by weight of water, and 1 part by weight of isopropyl alcohol, and was mixed with 100 parts by weight of the precursor (a) of water absorbing resin as obtained above. The resulting mixture was heated at 210 ° C for 45 minutes, thereby obtaining the water absorbing agent (1), for which the measurement results of the following properties are shown in Table 1: absorption capacity under no load , absorption capacity under load, absorption capacities (l) - (4) of static deterioration under load, dynamic absorption capacity under load, absorption capacity of dynamic deterioration under load, substantial absorption capacities (l) - (2) under load, absorption speed, and water soluble content.

EXAMPLE 2 A reaction solution was prepared by charging 720 g of acrylic acid, 3.08 g of N, N'-methylene-sisacrylamide as the internal cross-linking agent, and 2.718 g of deionized water as the solvent in a reaction vessel as prepared by plugging a double arm type mixer, made of stainless steel with a capacity of 10 liters that has two sigma type vanes and a jacket. Then, while maintaining the temperature of this reaction solution at 15 ° C, the atmosphere within the system was replaced with a nitrogen gas. Then, while the reaction solution was stirred, 21.6 g of a 10% by weight aqueous solution of 2,2'-azobis (2-amidinopropane) dihydrochloride, 18.0 g of a 1% strength by weight aqueous solution were added. L-ascorbic acid, 20.6 g of a 3.5% aqueous solution of hydrogen peroxide, to initiate the polymerization reaction. The reaction was stopped at the same time as the initiation of the polymerization reaction. Then, the polymerization reaction was carried out while the temperature of the jacket was adequately raised with the increasing temperature of the reaction solution such that the temperatures of the reaction solution and the jacket would be almost the same with each other. Then, after the temperature of the reaction solution has reached its maximum temperature, the temperature of the reaction solution was maintained at not less than 55 ° C by controlling the temperature of the jacket. After 3 hours, the resulting hydrogel crosslinking polymer was pulverized by rotating the vanes of the double arm type kneader. Additionally, the temperature was maintained at about 50 ° C while the vanes of the double-arm kneader were turned, and 750 g of an aqueous solution at 40 I by weight of sodium hydroxide were dripped and mixed, thereby obtaining a polymer of hydrogel with a neutralization ratio of 75% in mol when the time as necessary for the neutralization was 6 hours. This hydrogel polymer was spread on a 50 mesh wire net and then dried with hot air at 60 ° for 16 hours. Then, the resulting dry product was pulverized with a vibration mill and further classified with a 20-mesh wire net, thereby obtaining the precursor (b) of water-absorbent resin, as it was sprayed in the irregular form with a average particle diameter of 300 μm. A surface crosslinking agent, comprising one part by weight of propylene glycol, 0.05 parts by weight of ethylene glycol dichlycidyl ether, 3 parts by weight in water, and one part by weight of isopropyl alcohol, was mixed with 100 parts by weight of the precursor (b) of water absorbing resin, as obtained above. The resulting mixture was heated at 205 ° C for 50 minutes, thus obtaining the water absorbing b resin, of which the absorption capacity under load was 26.9 (g / g) and the water content (on a wet basis ) was 1% mol. - Then, 100 parts by weight of this water-absorbent resin b was spread with a mixed solution, comprising 0.005 parts by weight of diethylenetriaminepentaacetate sodium, and 3 parts by weight of water, and then dried at 80 ° C, obtaining from this way the water absorbing agent (2) according to the present invention, for which the measurement results of the following properties are shown in the Table: absorption capacity under no load, absorption capacity under a load, capacities ( l) - (4) absorption of static deterioration under load, dynamic absorption capacity under load, absorption capacity of dynamic deterioration under load, capacities (l) - (2) of substantial absorption, absorption speed, and content soluble in Water.

COMPARATIVE EXAMPLE 1 A reaction solution was prepared by dissolving 1.52 parts by weight of trimethylolpropane triacrylate in 5.500 parts by weight of an aqueous solution of sodium acrylate with a neutralization ratio of 75% by mol (monomer concentration: 33% by weight). ThenThis solution was degassed under an atmosphere of nitrogen gas for 30 minutes, and then supplied into a reaction vessel as prepared by capping a kneader type double arm, made of stainless steel with a capacity of 10 liters having two vanes Sigma type and a jacket. While maintaining the reaction mixture at 30 ° C, the atmosphere within the system was replaced with a nitrogen gas. Then, while the reaction solution was stirred, 2.46 parts by weight were added sodium persulfate and 0.10 parts by weight of L-ascorbic acid, so that the polymerization reaction started about 1 min after. The polymerization was carried out at 30-80 ° C, and the resulting hydrogel polymer was removed 60 minutes after the initiation of the polymerization. The resulting hydrogel polymer had a finely divided diameter of about 5 mm. This finely divided hydrogel polymer was spread on a 50 mesh wire mesh and dried at 150 ° C with hot air for 90 minutes. Then, the resultant dried product was pulverized with a vibration mill and further classified with a wire net of 20 mesh, thus obtaining fetter the precursor (c) of water-absorbent resin as sprayed and irregular shape with a diameter of average particle of 350 μm. A crosslinker surface comprising 1 part by weight of glycerol, 0.05 parts by weight of ethylene glycol diglycidyl ether, 3 parts by weight of water, and 1 part by weight of isopropyl alcohol, was mixed with 100 parts by weight of precursor (c) of water absorbing resin as obtained above. The resulting mixture was heated at 195 ° C for 40 minutes, thereby obtaining the water absorbing resin c, of which the absorption capacity under load was 22.3 (g / g) and the water content (on a wet basis). ) was 1% by weight or less. Then, 100 parts by weight of this absorbent resin c water was sprayed with a mixed solution comprising 0,005 parts by weight of sodium diethylenetriaminepentaacetate and 3 weight parts of water and then dried at 80 ° C, thereby obtaining the comparative water absorbing agent (a), for which the measurement results of the following properties are shown in Table 1: absorption capacity under no load, absorption capacity under load, capacities (1) - (4) of absorption of static deterioration under load, capacity of dynamic absorption under load, capacity of absorption of dynamic deterioration under load, capacities (l) - (4) of substantial absorption under load, speed of absorption and content soluble in water.

COMPARATIVE EXAMPLE 2 A reaction solution was prepared by dissolving 4.5 parts by weight of polyethylene glycol diacrylate (average molar number of added ethylene oxide: 8) in 5,500 parts by weight of an aqueous solution of sodium acrylate with a neutralization ratio of 75%. in mol (monomer concentration: 33% by weight). Then, this solution was degassed under a nitrogen gas atmosphere for 30 minutes, and then it was supplied in a reaction vessel as prepared by plugging a double-arm type kneader, made of stainless steel with a capacity of 10 liters having two Sigma type vanes and a jacket. While the reaction solution is maintained at 30 ° C, the atmosphere within the system was replaced with a nitrogen gas. Then, the reaction solution was stirred, 2.46 parts by weight of sodium persulfate and 0.10 parts by weight of L-ascorbic acid were added, so that the polymerization reaction was started close to. 1 minute later The polymerization was carried out at 30-80 ° C, and the resulting hydrogel polymer was removed 60 minutes after the initiation of the polymerization. The resulting hydrogel polymer had a finely divided diameter of about 5 mm. This finally divided hydrogel polymer was spread on a 50 mesh wire mesh and dried at 150 ° C with hot air for 92 minutes. Then, the resulting dry product was pulverized with a vibration mill and further classified with a 20-mesh wire net, thereby obtaining the precursor (d) of water-absorbent resin as sprayed into the irregular shape with an average diameter of 280 μm particle. A surface crosslinking agent, comprising one part by weight of propylene glycol, 0.05 part by weight of diglyceryl ether of ethylene glycol, 3 parts by weight of water, and one part by weight of isopropyl alcohol, is mixed with 100 parts of the precursor (d) Water absorbent resin as obtained above. The resulting mixture was heated at 210 ° C for 40 minutes, thereby obtaining the comparative water-absorbing agent (2), for which the measurement results of the following properties are shown in table 1: absorption capacity under no load, absorption capacity under load, absorption capabilities of static deterioration ((1) ~ (4) under load, dynamic absorption capacity under load, absorption capacity of dynamic deterioration under load, substantial absorption capacities (1) ~ (4) under load, absorption speed and water soluble content.

EXAMPLE 3 An aqueous monomer solution was prepared by mixing 67.0 parts by weight of a 37% by weight aqueous solution of sodium acrylate, 10.2 parts by weight of acrylic acid, 0.097 parts by weight of polyethylene glycol diacrylate (average number of units of polyethylene acid: 8), and 22.0 parts by weight of water together. Nitrogen was blown into the aqueous monomer solution, above in a vat, thereby reducing the concentration of dissolved oxygen in the solution to 0.1 ppm or less. Then, the temperature of the solution was adjusted to 18 ° C under nitrogen atmosphere. Then, 0.16 parts by weight of a 5% by weight aqueous solution of sodium persulfate, 0.016 parts by weight of a 5% by weight aqueous solution of 2,2'-azobis hydrochloride (2) were dripped in sequence under stirring. -aminopropane), 0.15 parts by weight of a 0.5% by weight aqueous solution of L-ascorbic acid, and 0.17 parts by weight of a 0.35% by weight aqueous solution of hydrogen peroxide. Immediately after the dripping of the hydrogen peroxide, a polymerization reaction was started, and after another 10 minutes, the temperature of the monomer reached the maximum temperature. The maximum temperature was 85 ° C. Then, the tub was immersed in a hot water bath of 80 ° C and aged for 15 minutes. The resulting transparent hydrogel was crushed with a meat blade, and the resulting, finally divided, hydrogel polymer was spread on a 50 mesh wire mesh and dried at 160 ° C with hot air for 65 minutes. Then, the resulting dry product was pulverized with a spraying machine and then classified into what passed through a 85.0 μm sieve, but remained on a 106 μm sieve, thus obtaining the resin precursor (e) Water absorbent as pulverized in irregular shape with average particle diameter of 320 μm. A surface crosslinking agent, comprising one part by weight of propylene glycol, 0.05 parts by weight of 1,4-butanediol, 3 parts by weight of water, 1 part by weight of isopropyl alcohol, was mixed with 100 parts by weight of the precursor (e) of water absorbing resin as obtained above. The resulting mixture was heated at 210 ° C for 40 minutes, thereby obtaining the water-absorbent resin in which the absorption capacity under the load was 26.6. (g / g) and the water content (on a wet basis) was 1% by weight or less. Then, 100 parts by weight of this water-absorbent resin was dispersed, with a mixed solution, comprising 0.005 parts by weight of pentasodium diethylene diamine pentaacetate and 3 parts by weight of water, then dried at 80 ° C, obtaining from this The water absorbing agent 3 according to the present invention, for which the measurement results of the following properties are shown in Table 1: absorption capacity under no load ^. absorption capacity under load, absorption capabilities of static deterioration, (1) ~ (4) under load, dynamic absorption capacity under load, absorption capacity of dynamic deterioration under load, substantial absorption capacities (1) ~ (4) under load, absorption speed, and water soluble content.

COMPARATIVE EXAMPLE 3 A reaction solution was prepared by dissolving 10.6 g of polyethylene glycol diacrylate in 6570 g of a 30% by weight aqueous solution of partially neutralized sodium acrylate with a neutralization ratio of 75% mol. Then, this reaction solution was provided to a reactor having a structure such that a cover was equipped to a steel arms-type kneader, of 10 L capacity having two sigma-type veins and a jacket. The internal atmosphere of the reactor was replaced with nitrogen while the temperature of the reaction solution was maintained at 30 ° C by circulating 30 ° C air in the jacket. Then, 15.6 g of a solution of sodium persulfate, aqueous, al- 20% by weight, and 14.9 g of aqueous 0.1% by weight of L-ascorbic acid, were added as polymerization initiators in the reactor as long as stirred a blade of the kneader at 40 rpm, thereby initiating polymerization. When the initiation of the polymerization was confirmed from the clouding of the reaction mixture, the blade was stopped, and the reaction mixture was left as is until the internal temperature dropped to 60 ° C due to the heat removal using the jacket. When the internal temperature fell further below 60 ° C, the blade rotated to disintegrate the resulting gel, and then the polymerization was further carried out such that the maximum value of the internal temperature would be 75 ° C. Then, the temperature of the jacket was increased to 60 ° C, and while the gel was integrated, the polymerization system was maintained at 65 ° C or higher for 20 minutes, thus ending the polymerization. The resulting hydrogel polymer was dried at 160 ° C with hot air for 65 minutes. Then, the resulting dry product was pulverized with a vibration mill, thereby obtaining the precursor (f) of water absorbing resin as pulverized in the regular form with an average particle diameter of 450 μm. A surface crosslinking agent, comprising 0.5 weight parts of glycerol, 0.05 weight parts of diglycidyl ether of ethylene glycol, 3 parts by weight of water, and 0.75 parts by weight of isopropyl alcohol, was mixed with 100 parts by weight of the precursor (f) of water absorbing resin as obtained above. The resulting mixture was heated at 200 ° C for 50 minutes, thereby obtaining the water-absorbing agent, comparative, for which the measurement results of the following properties are shown in table 1: absorption capacity under no load , absorption capacity, static deterioration absorption capabilities (1) ~ (4) under load, dynamic absorption capacity under load, dynamic deterioration absorption capacity under load, substantial absorption capacities (1) ~ (4) under load, absorption speed, and water soluble content.

Table 1 EXAMPLE 4 First, 50 parts by weight of the water absorbing agent (1), as obtained in Example 1, and 50 parts by weight of pulverized wood pulp were mixed together in a dry manner with a mixer. Then, the resulting mixture was formed into a mesh size of 120 mm x 380 mm by pneumatically molding the mixture on a 400 mesh wire screen (mesh size: 38 μm) with a batch type pneumatic device. In addition, the mesh was pressed for 5 seconds under a pressure of 2 kg / cm2, thereby obtaining an absorbent material weighing approximately 626 g / m2. Then, a backing sheet (liquid impervious sheet) of the liquid impervious polypropylene with a so-called leg fold, the absorbent material, mentioned above, and the top sheet (liquid permeable sheet) of a liquid permeable polypropylene were bonded between yes in this order with double coated tapes, and two so-called tape fasteners, then provided to the resulting bonded product, thereby obtaining an absorbent article (i.e., paper diaper). The weight of this absorbent article was 47 g. ^ - This absorbent article was adjusted to each of the four units of the so-called kewpie dolls (three units of which have a body length of 55 cm and a weight of 5 kg, and the other unit has a body length of 65 cm and a weight of 6 kg), and these wrists were placed on their surfaces at room temperature of 37 ° C. Then, a tube was inserted between the absorbent article and the wrists, and 50 g of a physiological chloride solution was added. Sodium containing L-ascorbic acid at a concentration of 0.005 by weight is injected through the tube every 90 minutes to a position corresponding to where the urine is discharged from the human body. Then, this injection operation was completed when the injected sodium chloride physiological solution started to play without being absorbed by the absorbent article, and the amount of the physiological sodium chloride solution, as injected then, was measured, and the average value thereof for the four Kewpie doll units mentioned above was related to the absorption amount of the absorbent article in a state that gives the surface down. The result of the amount of absorption (g) in a state that gives the surface down is shown in table 2 together with values of the absorption index of deterioration under load, absorption index of substantial concentration and absorption rates of concentration of dynamic and static deterioration.

EXAMPLES 5 AND 6 Articles were obtained in the same manner as in Example 4 except that the liquid absorbing agent (1) was replaced with the water absorbing agents (2) (3) as obtained in Examples 2 and 3, respectively. Both resulting absorbent articles weighed 47 g. The amount of absorption of each of these absorbent articles in a state that gives the surface down was determined in the same manner as for example 4. The result of the amount of absorption (g) in a state giving the surface to below is shown in table 2 together with values of the absorption index of deterioration under load, absorption index of substantial concentration, and absorption rates of concentration of static and dynamic deterioration.

COMPARATIVE EXAMPLES 4, 5, and 6 The comparative absorbent articles were obtained in the same manner as in Example 4 except that the water absorbing agent (1) was replaced with the water absorbing agents (1), (2) and (3), comparative, as obtained in comparative examples 1, 2, and 3, respectively. All the resulting absorbent articles weighed 47 g. The amount of absorption of each of these absorbent articles in a state giving the surface down was determined in the same manner as for example 4. The result of the amount of absorption (g) in a state giving the surface down is shown in table 2 together with values of the absorption index of deterioration under load, absorption index of substantial concentration, and absorption rates of concentration of static and dynamic deterioration.

Table 2 (tab e): All the water absorbing agents used have their weight ratios of 0.5 to total with the base, fibrous material.

EXAMPLE 7 First, 75 parts by weight of the water absorbing agent (1), as obtained in Example 1, and 25 parts by weight of pulverized wood pulp were mixed together in a dry manner with u? mixer. Then, the resulting mixture was formed into a mesh size of 120 mm x 350 mm by pneumatically molding the mixture on a 400 mesh wire screen (mesh size: 38 μm) with a batch type pneumatic device. In addition, the mesh was pressed for 5 seconds under a pressure of 2 kg / cm2, thereby obtaining an absorbent material weighing approximately 500 g / m2. Then, a backing sheet (liquid impervious sheet) of a liquid impervious polypropylene with a so-called leg fold, the absorbent material, mentioned above, and the top sheet (liquid permeable sheet) of a liquid permeable polypropylene were joined together. each other in this order with double coated tapes, and two so-called tape fasteners, were then provided to the resultant bonded product, thereby obtaining an absorbent article (i.e., paper diaper). The weight of this absorbent article was 44 g. This absorbent article was adjusted to each of the four units of the so-called kewpie dolls (three units of which have a body length of 55 cm and a weight of 5 kg, and the other unit has a body length of 65 cm and a weight of 6 kg), and these dolls were placed on their surfaces at room temperature of 37 °. C- Then, a tube was inserted between the absorbent article and the wrists, and 50 g of a physiological solution of sodium chloride containing L-ascorbic acid at a concentration of 0.005 by weight was injected through the tube every 90 minutes to a position which corresponds to where the urine of the human body is discharged. Then, this injection operation was completed when the injected sodium chloride physiological solution started to play without being absorbed by the absorbent article, and the amount of the physiological sodium chloride solution, as injected then, was measured, and the average value thereof for the four Kewpie doll units mentioned above was related to the absorption amount of the absorbent article in a state that gives the surface down. The result of the amount of absorption (g) in a state that gives the surface down is shown in table 2 together with values of the absorption index of deterioration under load, absorption index of substantial concentration and absorption rates of concentration of dynamic and static deterioration.

EXAMPLES 8 AND 9 - Articles were obtained in the same manner as in Example 7 except that the liquid absorbing agent (1) was replaced with the water absorbing agents (2) (3) as obtained in Examples 2 and 3, respectively. Both resulting absorbent articles weighed 44 g. The amount of absorption of each of these absorbent articles in a state that gives the surface down was determined in the same manner as for example 7. The result of the absorption amount (g) in a state giving the surface towards below is shown in table 3 together with values of the absorption index of deterioration under load, absorption index of substantial concentration, and absorption rates of concentration of static and dynamic deterioration.

COMPARATIVE EXAMPLES 7, 8, AND 9 The comparative absorbent articles were obtained in the same manner as in Example 7 except that the water absorbing agent (1) was replaced with the water absorbing agents (1), (2) and (3), comparative, as obtained in comparative examples 1, 2, and 3, respectively. All the resulting absorbent articles weighed 44 g. The amount of absorption of each of these absorbent articles in a state that gives the surface down was determined in the same manner as for example 7. The result of the absorption amount (g) in a state giving the surface towards below is shown in Table 3 together with values of the deterioration absorption index under load, substantial concentration absorption index, and absorption rates of static and dynamic deterioration concentration.

Table 3 not to the water absorbing agents used their weight ratio of 0.75 to the total with the fibrous material.

EXAMPLE 10 First, 60 parts by weight of (1), as obtained in Example 1, and 40 parts by weight of pulverized wood pulp were mixed together in a dry manner with the mixer. Again, the resulting mixture was formed into a mesh size of 120 mm by 380 mm by pneumatically molding the mixture on a 400 mesh wire screen (mesh size: 38 μm) with a batch type pneumatic device. In addition, this mesh was pressed for 5 seconds under a pressure of 2 kg / cm2, thereby obtaining an absorbent material weighing approximately 530 g / m2. Then, a backing sheet (liquid impervious sheet) of a liquid impervious polypropylene with a so-called leg fold, in the aforementioned absorbent material, and an upper sheet (liquid permeable sheet) of a liquid permeable polypropylene were joined together. each other in this order with double coated tapes, and then two so-called tape fasteners were provided to the resulting bonded product, thereby obtaining an absorbent article (i.e., paper diaper). The weight of this absorbent article was approximately 47 g. - COMPARATIVE EXAMPLE 10 An absorbent, comparative article was obtained in the same manner as in Example 10 except that the water absorbing agent (1) was replaced with the water absorbing agent (2), comparative, as obtained in Comparative Example (2) . The resulting absorbent article weighed about 47 g. A test was conducted for 5 children of the age ranging from 1 year and 8 months to 2 years and 4 months as follows. Ten absorbent articles (as obtained in Example 10) and ten absorbent, comparative articles (as obtained in comparative example 10) were distributed to each child. After each of the diapers has been used for one night, the diapers were collected to examine the amounts of urine as absorbed by the diapers and whether the urine leaked or not while the children carried the diapers. The treatment of the data was carried out by making calculations for absorbent articles that absorbed 150 g or more of urine, thus excluding leakage that was caused, for example, by the deviation of the diapers from their adjusted positions when they used The results are shown in Table 4. The average amount of urine is, with respect to paper diapers that absorbed 150 g or more of urine, a value a value as given by dividing the total amount of urine, as absorbed by these diapers, by the number of diapers. The average amount of urine in the case of leakage is, with respect to paper diapers that absorbed 150 g or more of urine, a value a value as given by dividing the total amount of urine, as absorbed by these diapers, until the leak happens, due to the number of diapers that suffered the leak. The leakage ratio is a ratio (percentage) of the number of paper diapers that leaked, between paper diapers that absorbed 150 g or more of urine, to the number of paper diapers that absorbed 150 g or more of urine.

Table 4 absorbent agent used water absorbing agent used water absorber, water (1) comparative (2) Amount 258 261 average (g) of urine Amount 355 324 average (g) of urine in case of leak Leakage ratio 8 12 (_ % _) With respect to commercially available diapers (which were purchased in the period from April to September 1998) as shown in Table 5, the following properties were calculated and are shown in Table 5: The weight ratio of the absorbent resin of water to the total of the water-absorbent resin and the fibrous material, specifically, the concentration of water-absorbing resin; the properties of the water-absorbent resin, such as absorption capacity under no load, absorption capacity under load, absorption rate, water-soluble content, substantial absorption capacities (1) ~ (2) under load, absorption capacities of aesthetic deterioration (1) ~ (4) under load, dynamic absorption capacity under load, absorption capacity of dynamic deterioration under load, and deterioration absorption index under load; and the properties of the absorbent material, such as absorption index of substantial concentration and absorption rates of concentration of static and dynamic deterioration. The way to measure each property is as follows: (1) concentration of water absorbing resin each of the above commercially available diapers was dried under vacuum at 60 ° C for 16 hours. Then, the backsheet, the topsheet, the non-woven fabric sheet, the paper, and the acquisition layer if any (some of the inner diapers additionally included this acquisition layer consisting of fibrous material) were all removed of each diaper to obtain an absorbent layer that consists mainly of water-absorbent resin and fibrous material. Then, the weight X (g) of the absorbent layer was measured, and then the weight Y (g) of the water absorbent resin, as included in the absorbent layer, was quantified, thereby calculating the concentration of absorbent resin of water from the following equation: concentration of water-absorbent resin = X / Y. (2) properties of the water-absorbent resin: The water-absorbent resin and the fibrous material, as included in the absorbent material of each commercially available diaper, were separated from each other then dried under vacuum at 60 ° C for 16 hours. Then, the measurement was made for the properties of the water-absorbent resin, such as absorption capacity under no load, absorption capacity under load, absorption rate, water soluble content, substantial absorption capacity (1) ~ (2) ) under load, static deterioration absorption capacity (1) - (4) under load, dynamic absorption capacity under load, and dynamic deterioration absorption capacity under load, and dynamic deterioration absorption capacity in the manner mentioned above. In addition, the deterioration absorption index under load of the water-absorbent resin is the total of the measurement values resulting from the absorption capacities of static deterioration (1) ~ (4) under load and dynamic absorption capacity under load. (3) Properties of absorbent material.

The water-absorbent resin and the fibrous material, as included in the absorbent material of each commercially available diaper, were separated from each other and then dried under vacuum at 60 ° C for 16 hours. Then, the calculation was made for the rate of absorption of circumstantial concentration and the absorption rates of concentration of static and dynamic deterioration.

Table 5 Table 5 (continued) Hereinafter, examples of some preferred embodiments of the present invention of the water absorbing agent with excellent resistance to urine and those of the production process therefor are described in detail. However, the present invention is not limited to these examples. In addition, in the examples and comparative examples, unless otherwise indicated, the units "%" and "part (s)" denote these by weight. Incidentally, the properties of the water absorbing agent, such as water absorption amount, water soluble content, and soluble content as eluted in artificial urine, were measured by the methods below: (1) Amount of water absorption of the water absorbing agent First, 0.2 g of the water-absorbent resin was uniformly placed in a tea-bag type bag (6 cm by 6 cm), from which the opening was then sealed with heating, and the bag was then immersed in a physiological solution of sodium chloride. Sixty minutes later, the bag was removed and then drained at 250 G for 3 minutes with a centrifuge, and then the Wi (g) weight of the bag was measured. On the other hand, the same procedure was carried out not using water-absorbent resin, and the resulting weight W0 (g) was measured. In this way, the amount of water absorption (g / g) was calculated from these weights Wa and W0 according to the following equation: Amount of water absorption (g / g) = (Wi and W0 / (weight (g ) of water-absorbent resin) (2) Soluble content as eluate of the water-absorbing agent: First of all, a gel of the water-absorbing agent was swollen, with 25 ml of artificial urine in a 100-ml beaker, the beaker was left to stand stationary 37 ° C for 16 hours. Then, the resulting swollen gel was dispersed in 975 ml of deionized water and stirred for 1 hour, and then filtered with a filter paper. The resulting filtrate was titrated by colloidal titration to determine the soluble content (%) as eluted from the water absorbing agent.

The composition of the artificial urine is as follows: Urea 1.9% sodium chloride 0.8% magnesium chloride 0.1% calcium chloride 0.1% (3) Soluble content as it deteriorates and elutes from the water-absorbing agent: First of all, a gel of the water-absorbing agent was swollen, with 25 ml of artificial urine, containing L-ascorbic acid in a concentration of 0.005%, in a 100 ml beaker, then left standing at 37 ° C. ° C for 16 hours. Then, the resulting swollen gel was dispersed in 975 ml of deionized water to rinse the soluble contents diluted with deionized water. The dispersion was stirred for 1 hour and then filtered with a filter paper. The resulting filtrate was titrated by colloidal titration to determine the soluble content (%) as deteriorated and eluted the water absorbing agent. (4) absorption capacity under load: The absorption capacity under a load was determined using a measuring apparatus of Figure 1. As shown in Figure 1, the measuring apparatus comprises: a balance 1; a container 2 of a predetermined capacity, as mounted on the balance 1; a sheet 3 of air inhalation pipe; an introduction tube 4; a glass filter 6; and a measuring part 5 as mounted on the glass filter 6. The container 2 has an opening part 2a in the upper part and a part of the opening 2b in the side. The air inhalation tube 3 is inserted into the opening part 2a, and the introduction tube 4 is fitted to the opening part 2b. In addition, the container 2 contains a predetermined quantity of aqueous solution at 0.9% by weight of sodium chloride (later preferred as the physiological solution of sodium chloride). The lower part of the air inhalation tube 3 is immersed in the physiological solution 12 of sodium chloride. The air inhalation tube 3 is adjusted to maintain the internal pressure of the sodium chloride container 12. The air inhalation tube 3 is adjusted to maintain the internal pressure of the container 2 close to atmospheric. The glass filter 6 is formed with a diameter of 5 mm. The container 2 and the glass filter 6 are connected to each other through the introduction tube 4 made of silicone resin. In addition, the position and level of the glass filter 6 are adjusted relative to the container 2. The measurement part 5 comprises: a filter paper 7; a support cylinder 9; a wire net 10 as it joins the bottom of the support cylinder 9; and a weight 11. The measuring part 5 is formed when mounting the filter paper 7 and the support cylinder 9 (i.e., wire net 10) in this order in the glass filter 6. The wire net 10 is made of stainless steel and has a mesh size of 100 mesh. The level of the top surface of the wire net 10, specifically , of the contact surface of the wire net 10 with a water absorbing agent 15, is adjusted to be as high as the level of the lower end surface 3a of the air surface inhalation tube 3. In the wire net 10, a predetermined amount of the water absorbing agent is spread uniformly. The weight 11 is adjusted by weight such that a 0.7 psi load can be applied uniformly to the wire net 10, specifically, to the water absorbing agent 15. The absorption capacity under a load was measured with the measuring apparatus having the aforementioned constitution. The measurement method is explained later in the present. First, the predetermined preparatory operations are made, in which, for example, a predetermined amount of the physiological sodium chloride solution 12 was placed in the container 2, and the air inhalation tube 3 was inserted into the container 2. Then, the filter paper 7 was mounted on the glass filter 6. On the other hand, in parallel with these assembly operations, 0.9 g of the water absorbing agent was uniformly spread inside the support cylinder 9, specifically, in the wire 10, and weight 11 was placed in water-absorbing agent 15. Then, the wire net 10, specifically, the support cylinder 9 (in which the water absorbing agent 15 and the weight 11 were put on), was mounted on the filter paper 7 such that the center line of the support cylinder 9 will be adjusted with that of the glass filter 6. Then, the weight of the physiological sodium chloride solution, as absorbed by the water absorbent agent during a period of 60 minutes since the support cylinder 9 has been mounted on the filter paper 7, was determined from a value as measured with the balance 1. In addition, the same procedure as the previous one was carried out not using the water absorbing agent 15, and the weight of the physiological solution of sodium chloride, as absorbed by materials other than the water-absorbing agent, such as filter paper 7, was determined from a co-value or measured with balance 1 and considered as the blank value. The amount of absorption under the load was calculated from the following equation: absorption capacity (g / g) under load = (amount of water absorption after 60 minutes-white) / (weight of water-absorbing agent) (5) Average particle diameter of the water absorbing agent The water absorbing agent was sieved and classified with 850 μm, 600 μm, 500 μm, 425 μm, 300 μm, 220 μm, 150 μm, and 105 μm sieves, and the percentage of the residue, R, was plotted on a paper of logarithmic probability to estimate a particle diameter corresponding to R = 50% as the average particle diameter. (6) water content (on a wet basis) of the water-absorbent resin; About one gram of the water-absorbent resin was heated in an oven of 105 ° C for 3 hours, and the weight W (g) of the water-absorbent resin was measured before and after heating, and the water content (% by weight) (on a wet basis) was calculated according to the following equation: Water content (% by weight) = (before (g) -wdespues (g)) / wantes (g) where: Wantes is the weight of the water absorbing resin before drying; and W afterwards is the weight of the water-absorbent resin after drying.

REFERENCE EXAMPLE 1 An aqueous monomer solution was prepared by mixing 67.0 parts of a 37% aqueous sodium acrylate solution, 10.2 parts of acrylic acid, 0.079 parts of polyethylene glycol diacrylate (average number of polyethylene oxide units: 8), and 22.0 parts of water together. Nitrogen was blown into the above aqueous monomer solution in a vat, thereby reducing the concentration of dissolved oxygen in the solution to 0.1 ppm or less. Then, the temperature of the solution was adjusted to 18 ° C under nitrogen atmosphere. Then, 0.16 parts of a 5% aqueous solution of sodium persulfate, 0.16 parts of a solution of 2, 2 '-a zobi s- (2-aminopropionate) aqueous, were dripped in sequence under stirring. %, 0.15 parts of a 0.5% aqueous solution of L-ascorbic acid, aqueous, and 0.17 parts of a 0.35% aqueous solution of hydrogen peroxide. Immediately after the dripping of the hydrogen peroxide, the polymerization reaction began, and after another 10 minutes, the temperature of the monomer reached the maximum temperature. The maximum temperature was 85 ° C. Then, the tub was immersed in a hot water bath of 80 ° C and aged for 10 minutes.

The resulting transparent hydrogel was ground with a meat blade and then dried at 180 ° C for 30 minutes. The resulting dry product was sprayed with the spraying machine and then classified into what passed through a 500 μm sieve, but remained on a 105 μm sieve, thereby obtaining the water absorbing resin (A).

EXAMPLE 2-1 A composition solution, comprising 0.001 part of diethylbenthosane pentasodium acetate, 0.05 parts of diglycidyl ether of ethylene glycol, one part of propylene glycol three parts of water, and one part of isopropyl alcohol, was mixed with 100 parts of resin water absorbent (A) as obtained in the above Reference Example, and the resulting mixture was heated at 180 ° C for 40 minutes, thereby obtaining water absorbing agent. The performance evaluation results of the resulting water absorbing agent (E2-1) are shown in Table 2-1.

EXAMPLE 2-2 A water-absorbing agent according to the present invention was obtained in the same manner as in Example 2-1 except that the amount of pentasodium diethylamine pentamine was changed to 0.01 parts. The performance evaluation results of the resulting water absorbing agent (E2-2) are shown in Table 2-1.

EXAMPLE 2-3 A water-absorbing agent according to the present invention was obtained in the same manner as in Example 2-1 except that the amount of pentasodium diethylbenzathine was changed to 0.1 parts. The performance evaluation results of the resulting water absorbing agent (E2-3) are shown in Table 2-1.

EXAMPLE 2-4 A water-absorbing agent according to the present invention was obtained in the same manner as in Example 2-1 except that 0.01 part of triethylamine amine hexahydrate hexaacetate was used in place of diethylene glycine pentamine. pentasodium. The performance evaluation results of the resulting water absorbing agent (E2-4) are shown in Table 2-1.

EXAMPLE 2-5 A water-absorbing agent was obtained in accordance with the present invention in the same manner as in Example 2-1 except that 0.01 part of cyclohexanediamineteacetate was used, instead of diethylene glycol acetaminophenacetate. The performance evaluation results of the resulting water absorbing agent (E2-5) are shown in Table 2-1.

COMPARATIVE EXAMPLE 2-1 A water-absorbing agent was obtained, comparative in the same manner as in Example 2-1 except that diethyl pentene diamine pentanamine was not added. The performance evaluation results of the resulting water absorbing agent (R2-1) are shown in Table 2-1.

REFERENCE EXAMPLE 2 An aqueous monomer solution was prepared by mixing 81.8 parts of a solution of 38% aqueous sodium acrylate, 7.7 acrylic acid, 0.038 parts of trimethylolpropane triacrylate, and 9.8 parts of conjunctive water. Nitrogen was blown into the aqueous monomer solution, above, in a double-arm kneader as it is equipped with a liner, thereby removing dissolved oxygen from the solution. Then, the temperature of the aqueous monomer solution was adjusted to 22 ° C.

Then, 0.60 parts of a 10% aqueous solution of sodium persulfate and 0.30 parts of a 0.1% aqueous solution of L-ascorbic acid were added under stirring. One minute later than this addition, the aqueous monomer solution began to cloud and its temperature began to increase. After another 20 minutes, the temperature reached the maximum temperature, and the solution was then aged for 20 minutes under agitation. The maximum temperature was 96 ° C. After the aging has ended the resulting gel was obtained and dried at 170 ° C for 65 minutes. The resulting dry polymer was pulverized and then sieved with a 850 μm mesh, thereby obtaining water absorbing resin (B).

EXAMPLE 2-6 A composition solution, comprising 0.001 parts of cyclohexanediaminetetraacetate, 0.5 parts of ethylene carbonate, 3 parts of water, and 3 parts of isopropyl alcohol, was mixed with 100 parts of water-absorbent resin (B), and the resulting mixture was heated at 190 ° C for 50 minutes, thereby obtaining a water absorbing agent. The performance evaluation results of the resulting water absorbing agent (E2-6) are shown in Table 2-1.

EXAMPLE 7 A water-absorbing agent according to the present invention was obtained in the same manner as in Example 2-6 except that 0.5 parts of 1,4-but-anodiol were used in place of ethylene carbonate. The performance evaluation results of the resulting water absorbing agent (E2-7) are shown in Table 2-1.

COMPARATIVE EXAMPLE 2-2 A comparative water absorbing agent was obtained in the same manner as in Example 2-6 except that the cyclohexanediamine e raacetate was not added. The performance evaluation results of the resulting water absorbing agent (R2-2) are shown in Table 2-1.

COMPARATIVE EXAMPLE 2-3 A comparative water-absorbing agent was obtained in the same manner as in Example 2-7 except that the cyclohexanediamine-t-acetate did not add. The performance evaluation results of the resulting water absorbing agent (R2-3) are shown in Table 2-1.

Table 2-1 EXAMPLE 3-1 One hundred parts by weight of the water-absorbing agent, comparative (R2-1), as obtained in comparative example 2-1, was sprayed with a mixed solution, comprising 0.001 parts of pentosodium diethylene glycamine and 3 parts. of water, and was granulated in this way, then dried at 80 ° C, thereby obtaining a water-absorbing agent. The results of evaluation of the resulting water absorbing agent (E3-1) are shown in Table 3-1.

EXAMPLE 3-2 A water absorbing agent was obtained in the same manner as in Example 3-1 and except that the amount of diethyl ether aminepentaacet a pentasodium was changed to 0.1 parts. The results of evaluation of the resulting water absorbing agent (E3-2) are shown in Table 3-1.

EXAMPLE 3-3 A water absorbing agent was obtained in the same manner as in Example 3-1 and except that 0.001 part of triethylene glycine and hexasodium hexaacetate were used in place of diethyltriaminepent a pentasodium acetate. The results of evaluation of the resulting water absorbing agent (E3-3) are shown in Table 3-1.

COMPARATIVE EXAMPLE 3-1 The water absorbing agent (A) was considered as the water absorbing agent, comparative (R3-1) as was. The results of evaluation of the resulting water absorbing agent (R3-1) are shown in Table 3-1.

COMPARATIVE EXAMPLE 3-2 The comparative water-absorbent agent was obtained in the same manner as in Example 3-1 except that 100 parts by weight of the water-absorbing comparative agent (R2-1) was mixed with only three parts by weight of water. The results of evaluation of the resulting water absorbing agent (R3-2) are shown in Table 3-1.

Table 3-1 EXAMPLE 4-1 A composition solution, comprising 0.01 parts of N, N'-bis (1,2-dicarboxyetyl) -ethylenediamine, 0.05 parts of diglycidyl ether of ethylene glycol, 1 part of propylene glycol, 3 parts of water, and 1 part of alcohol isopropyl, was mixed with 100 parts with water-absorbent resin (A) as obtained in Reference Example 1, and the resulting mixture was heated at 180 ° C for 40 minutes, thereby obtaining a water-absorbing agent. The performance evaluation results of the resulting water absorbing agent (E4-1) are shown in Table 1.

COMPARATIVE EXAMPLE 4-1 A water absorbing agent was obtained, comparative in the same manner as in Example 4-1 except that neither 0.01 part of N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine or 0.05 part of diglycidyl ether was added. of ethylene glycol. The performance evaluation results of the resulting water absorbing agent (R4-1) are shown in Table 4-1. The water content of the water-absorbing agent, comparative (R4-1) was 1% by weight or less.

EXAMPLE 4-2 A composition solution, comprising 0.01 parts of (S, S) -N, '-bis (1,2-dicarboxyethyl) -ethylenediamine trisodium, 3 parts of water, was mixed with 100 parts with the comparative water-absorbing agent ( R4-1) as obtained in Comparative Example 4-1, and the resulting mixture was dried at 80 ° C for 20 minutes, thereby obtaining a water-absorbing agent. The performance evaluation results of the resulting water absorbing agent (E4-2) are shown in Table 4-1.

EXAMPLE 4-3 A water-absorbing agent was obtained in the same manner as in Example 4-2, except that the amount of (S, S) -N, N'-bis (1,2-dicarboxylethyl) -ethylenediamine was changed to 0.01. parts. The performance evaluation results of the resulting water absorbing agent (E4-3) are shown in Table 4-1.

EXAMPLE 4-4 A water absorbing agent was obtained in the same manner as in Example 4-2, except that a solution of composition comprises 0.1 part of N- (1,2-dicarboxy-2-hydroxyethyl) -tetrasodium tetraparate and 5 parts of water, was mixed with 100 parts of the water absorbing agent, comparative (R4-1). The performance evaluation results of the resulting water absorbing agent (E4-4) are shown in Table 4-1.

EXAMPLE 4-5 A water absorbing agent was obtained in the same manner as in Example 4-2, except that 0.001 part of (S, S) -N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine trisodium was replaced with 0.01 parts of N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine tetrasodium. The performance evaluation results of the resulting water absorbing agent (E4-5) are shown in Table 4-1.

EXAMPLE 4-6 A water absorbing agent was obtained, in the same manner as in Example 4-2 except that 0.001 part of (S, S) -N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine trisodium was replaced with 0.1 parts of sodium polymaleate with a molecular weight of approximately 10,000. The performance evaluation results of the resulting water absorbing agent (E4-6) are shown in Table 4-1.

EXAMPLE 4-7 A water absorbing agent was obtained in the same manner as in Example 4-2 except that 0.001 part of (S, S) -N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine trisodium was replaced with 0.01 parts of N, N'-dicarboximatilL-tetrasodium glutamate. The performance evaluation results of the resulting water absorbing agent (E4-57 are shown in Table 4-1.

EXAMPLE 4-8 A water absorbing agent was obtained in the same manner as in Example 4-2 except that 0.001 part of (S, S) -N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine trisodium was replaced with ( R, S) -N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine. The performance evaluation results of the resulting water absorbing agent (E4-8) are shown in Table 4-1.

COMPARATIVE EXAMPLE 4-2 A water absorbing agent, comparative in the same manner as Example 4-2 except that 0.001 parts of (S, S) -N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine trisodium were replaced with 0.01 parts. of acetyl 1 acetone. The performance evaluation results of the resulting water absorbing agent (R4-2) are shown in Table 4-1.

EXAMPLE 4-9 A composition solution, comprising 0.01 parts of (S, S) -N, N'-bis (1,2-di-carboxy-yl) -ethylenediamine trisodium, 0.5 parts of ethylene carbonate, 3 parts of water, 3 parts of isopropyl alcohol, was mixed with 100 parts of water-absorbent resin (B) as obtained in Reference Example 2, and the resulting mixture was heated to 190 ° C for 50 minutes, thereby obtaining a water absorbing agent. The performance evaluation results of the resulting water absorbing agent (E4-9) are shown in Table 4-1.

EXAMPLE 4-10 A water absorbing agent was obtained in the same manner as in Example 4-9 except that the ethylene carbonate was replaced with 0.5 parts of 1,4-butanediol. The performance evaluation results of the resulting water absorbing agent (E4-10) are shown in Table 4-1.

COMPARATIVE EXAMPLE 4-3 A water-absorbing agent was obtained, comparative in the same manner as in Example 4-9 except that 0.01 part of (S, S) -N, N'-bis (1,2-dicarboxyethyl) -ethylenediamine trisodium was not added. . The performance evaluation results of the resulting water absorbing agent (R4-3) are shown in Table 4-1.

COMPARATIVE EXAMPLE 4-4 A comparative water-absorbing agent (R4-4) was obtained in the same manner as in Example 4-10 except that 0.01 part of (S, S) -N, N'-bis (1-2) was not added. tricarboxylate) -ethylenediamine. The performance evaluation results of the resulting water absorbing agent (R4-4) are shown in Table 4-1.

EXAMPLE 4-11 First of all, 2 g of the absorbent agent (E4-2), as obtained in Example 4-2, was evenly spread and interposed between two sheets of laminated pulp (weight 150 g / m2, density 0.1 g / cm3, size 200 mm x 140 mm), thus obtaining an absorbent material. This absorbent material was interposed between a sheet of polyethylene film and a nonwoven sheet of polypropylene, thereby obtaining a body fluid absorbent article. Then, 100 g of artificial urine containing L-ascorbic acid at a concentration of 0.005% was poured onto the non-woven fabric side of the resulting body fluid absorbent article, allowed to be absorbed. This bodily fluid absorbent article was left stationary at 37 ° C for 8 hours, and then a 23 cm x 23 cm paper towel was laminated to the side of the non-woven fabric in the body fluid absorbent article. The pressure of 40 g / -cm 2 was applied for 1 minute, and the amount of artificial urine as absorbed by the walls of the paper was measured as the amount of desorption. In addition, the state of the swollen, resulting gel was observed with the naked eye to evaluate the deteriorated state of the gel in three classes of O, γ, X. The results are shown in Table 4-2.

COMPARATIVE EXAMPLE 4-5 An absorbent bodily fluids article was obtained, comparative in the same manner as in Example 4-11 except that the comparative water absorbing agent (R4-1) was used in place of the water absorbing agent (E4-2). The results of evaluation of the bodily fluid absorbent article, comparative, resulting, are shown in Table 4-2.

COMPARATIVE EXAMPLE 4-6 An absorbent bodily fluids article, comparative was obtained in the same manner as in Example 4-11 except that the comparative water absorbing agent (R4-2) was used in place of the water absorbing agent (E4-2) . The results of evaluation of the bodily fluid absorbent article, comparative, resulting, are shown in Table 4-2.

Table 4-1 Table 4-2 (Note) 0: The swollen gel stays in shape. ?: The swollen gel is partially out of shape. X: The swollen gel is out of shape and in a fluidized state.

Various details of the invention can be changed without departing from its spirit or scope. In addition, the above description of the preferred embodiments in accordance with the present invention are provided for the purpose of illustration only, and not for the purpose of limiting the invention as defined by the appended claims - and their equivalents.

It is noted that in relation to this date, the best method known by the applicant to carry out the present invention is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property:

Claims

1. A water absorbing agent, having an absorption capacity of 30 g / g or more under no load and a static deterioration absorption capacity (1) of 20 (g / g) or more under a load, characterized in that the capacity of static interior absorption (1) under a load is an absorption capacity of the water solvent as determined by the following sequential steps of: swelling a water absorbing agent at 15 (g / g) with a physiological solution of sodium chloride containing L-ascorbic acid in a concentration of 0.005% by weight; leaving the water absorbing agent in this swollen state for 6 hours; allowing the swollen, water-absorbing agent to absorb the physiological sodium chloride solution for another hour in a state where a load of 50 g / cm.sup.2 mounted on the swollen, water-absorbing agent is mounted; and measuring the weight of the swollen gel, resulting.

2. A water absorbing agent according to claim 1, characterized in that the static deterioration absorption capacity (1) under a load is 23 (g / g) or more.

3. A water absorbing agent according to claim 1 or 2, characterized in that the absorption capacity under no load is 33 (g / g) or more.

4. A water absorbing agent, having an absorption capacity of 30 (g / g) or more under no load and a dynamic deterioration absorption capacity of 20 (g / g) or more under a load, characterized in that the capacity of Dynamic deterioration absorption under a load is an absorption capacity of the water absorbing agent as determined by the following sequential steps of: swelling a water absorbing agent at 15 (g / g) with a physiological solution of sodium chloride containing L-ascorbic acid in a concentration of 0.005% by weight; leaving the water absorbing agent in this swollen state for 4 hours; dynamically damaging the swollen, water-absorbing agent; allowing the dynamically damaged water-absorbing agent to absorb the physiological solution of sodium chloride for another hour in a state where a load of 50 g / cm 2 mounted on the swollen water-absorbing agent is mounted; and measuring the weight of the swollen gel, resulting.

5. A water absorbing agent according to claim 4, characterized in that the absorption capacity of static deterioration under a load is 23 (g / g) or more.

6. A water absorbing agent according to claim 4 or 5, characterized in that the absorption capacity under no load is 33 (g / g) or more.

7. A water absorbing agent, having an absorption capacity of 3X) (g / g) or more under no load and a static deterioration absorption capacity (4) of 30 (g / g) or more under a load, characterized because the ability to absorb static deterioration under a load is an absorptive capacity of the water absorbing agent as determined by the following sequential steps of: inflating a water absorbing agent to 15 (g / g) with a physiological solution of sodium chloride containing L-ascorbic acid in a concentration of 0.005% by weight; leaving the water absorbing agent in this swollen state for 6 hours; allowing the swollen water-absorbing agent to absorb the physiological solution of sodium chloride for another hour in a state where a 20 g / cm.sup.2 load is mounted mounted on the swollen water-absorbing agent; and measuring the weight of the swollen gel, resulting.

8. A water absorbing agent according to claim 7, characterized in that the absorption capacity of static deterioration (4) under a load is 32 (g / g) or more.

9. A water-absorbing agent according to claim 7 or 8, characterized in that the absorption capacity of static deterioration (4) under no load is 33 (g l g) or more.

10. A water-absorbing agent according to any one of claims 1 to 9, characterized in that the absorption rate of 20 ~ 80 (sec) and a water-soluble content of 1 ~ 15% by weight.

11. An absorbent material, characterized in that it comprises the water-absorbing agent as recited in claim 1 and a base, fibrous material, wherein the weight ratio of the water-absorbing agent to the total of the water-absorbing agent and the base, fibrous material is 0.4 or more.

12. An absorbent material, according to claim 11, characterized in that it comprises the water absorbing agent has a static deterioration concentration absorption index of 23 or more of equation (1) below: static absorption concentration absorption index = X (1 - a) + Y a (1) wherein: X is the absorption capacity (g / g) under no load of the water absorbing agent; Y is a static deterioration absorption capacity (1) (g / g) under a shroud as cited in claim 1 of the water absorbing agent; and a is the weight ratio of the water absorbing agent to the total of the water absorbing agent and fibrous base material.

13. An absorbent material according to claim 11, characterized in that the water-absorbing agent has an absorption rate of 20 ~ 80 (sec) and a water-soluble content of 1-15% by weight.

14. An absorbent material, characterized in that it comprises the water absorbing agent as cited in claim 4 and the base, fibrous material wherein the weight ratio of the water-absorbing agent to the total of the water-absorbing agent of the base, fibrous material is 0.4 or more.

15. An absorbent material according to claim 14, characterized in that the water absorbing agent has a dynamic deterioration absorption absorption index of 23 or more of the equation (2) below: dynamic deterioration concentration absorption index = X (1 -?) + A? ( 2 ) wherein: X is the absorption capacity (g / g) under no load of the water absorbing agent; A is a dynamic deterioration absorption capacity (g / g) under a load as recited in claim 4 of the water absorbing agent; Y ? is the weight ratio of the water absorbing agent to the total of the water absorbing agent and the fibrous base material.

16. An absorbent material according to claim 14 or 15, characterized in that the water absorbing agent has an absorption rate of 20-80 (sec) and a water-soluble content of 1-15% by weight.

17. An absorbent material characterized in that it comprises the water-absorbing agent as cited in claim 7, a base, fibrous material, wherein the weight ratio of the water-absorbing agent to the total of the water-absorbing agent and the fibrous, base material is 0.4 or more.

18. An absorbent material according to claim 17, characterized in that the water-absorbing agent has an absorption rate of 20-80 (sec) and a water-soluble content of 1-15% by weight.

19. An absorbent article, characterized in that it comprises: an absorbent layer including the absorbent material as cited in any of claims 11 to 18; a sheet of liquid permeable surface; and a liquid impermeable backing sheet.

20. A measurement process of absorption property, characterized in that a liquid containing a reducible substance is used as a liquid to be absorbed in a process for measuring at least one absorption property selected from the group consisting of: absorption of the water absorbing agent under a load; absorption properties of an absorbent material of which the weight ratio of the water absorbing agent to the total of the water absorbing agent and the fibrous base material is 0.4 or more; and the absorption properties of an absorbent article that includes the previous absorbent material.

21. A process of measuring. absorption property according to claim 20, characterized in that the reducible substance is an ascorbic acid or its salts.

22. A production process for a water absorbing agent, characterized in that it comprises the step of mixing an ion blocking agent and a surface crosslinking agent, which can be selected in a carboxyl group, with a water absorbing resin having a carboxyl group.

23. A production process for a water absorbing agent according to claim 22, characterized in that 0.001-10 parts by weight of the ion blocking agent and 0.01-10 parts by weight of the surface crosslinking agent are mixed with 100 parts. by weight of the water-absorbent resin.

24. A production process for a water absorbing agent according to claim 22 or 23, characterized in that the ion blocking agent is at least one compound selected from the group consisting of aminocarboxylic acids, with minus three carboxyl groups and their salts.

25. A production process for a water-absorbing agent according to any of claims 22 to 24, characterized in that 0.01-10 parts by weight of water is further mixed with 100 parts by weight of the water-absorbent resin in the step of I zelado.

26. A production process for a water absorbing agent according to any of claims 22 to 25, characterized in that it also comprises the step of heating the mixture, resulting from the mixing step, at 100-230 ° C.

27. A production process for a water absorbing agent, characterized in that it comprises the steps of: crosslinking the vicinity of the surface of a water-absorbent resin that is obtained by polymerizing a monomer component including a saturated carboxylic acid in the presence of a internal crosslinking agent; and adding water and an ion blocking agent to the resultant surface-cross-linked water-absorbent resin, thereby granulating the water-absorbent resin.

28. A production process for a water-absorbing agent according to claim 27, characterized in that 0.1-20 parts by weight of water and 0.0001-10-parts by weight of the ion blocking agent are added to 100 parts by weight of water. the solvent resin of water, cross-linked on the surface.

29. A production process for a water absorbing agent according to claim 27, characterized in that the ion blocking agent is at least one compound selected from the group consisting of aminocarboxylic acids with at least three carboxyl groups and its salts.

30. A production process for a water-absorbing agent according to any of claims 27 to 29, characterized in that the surface-crosslinked water-absorbent resin has a water content of 20% by weight or less (in the wet base) ).

31. A production process for a water-absorbing agent according to any of claims 27 to 30, characterized in that the water-absorbing resin, crosslinked on the surface has an absorption capacity of at least 20 (g / g) under a load .

32. A water absorbing agent, characterized in that it is obtained by a process including the step of adding to a water-absorbent resin at least one chelating agent selected from the group consisting of compounds of the general formulas (1) and (2) and hydrophilic, maleic polymers (including salts) (3), wherein the general formula (1) is: R2 / Ri-CH- (CH2) n-CH (1) \ Xi Xi Ra¬ where: n, X1, and Rx-R3 denote the following numbers and structures: n = 0, 1 X1 = COOM1 (M1 = H, Na, K, NH "). R1 = H, OH, Me R2 = H, -CH2COOM2, -CH2CH2COOM2 (M2 = H, Na, K, NH4) -CH-CH-R- * I I R3 = -CH2COOM3, -CH2CH2COOM3, M3OOC COOM3 (M3 = H, Na, K, NH4) (R4 = H, OH, Me) and where the general formula (2) is: R6 R7 I / R5-CH- (CH2) m-CH-N-CH2-CH2-N (2) I I \ X2 X2 R8 wherein: m, X2 and R5-R8 denote the following numbers and structures: m = 0.1 X2 = COOM4 (M4 = H, Na, K, NH4) R5 = H, OH, Me Rfc H, -CH2COOM5, -CH2CH2COOMb ( Mb = H, Na, K, NH 4 R 'H, -CH 2 COOM' -CH 2 CH 2 COOe: M < H, Na, K, NH 4) -CH-CH-R 9 I I R 8 = -CH 2 COOM 7, -CH 2 CH 2 COOM 7, M "OOC COOM" (M7 = H, Na, K, NH4) (R9 = H, OH, Me).

33. A water-absorbing agent according to claim 32, characterized in that 0.00001-30 parts by weight of the chelating agent are added to 100 parts by weight of the water-absorbent resin.

34. An absorbent article for body fluids, characterized in that it comprises the water absorbing agent as recited in claims 32 or 33.