JP2001234087A - Water absorbent resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water absorbent resin composition comprising an aminoacetic acid-based chelating agent, excellent in urine resistance and further light resistance with slight discoloration and optionally having deodorant properties. SOLUTION: This water absorbent resin composition is characterized as comprising a water absorbent resin and the aminoacetic acid-based chelating agent which is contained in an amount of >=10 ppm based on the water absorbent resin with <=1 ppm content of nitrilotriacetic acid and its salt in the above composition based on the above composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a water-absorbing resin composition. More specifically, the present invention relates to a water-absorbent resin composition which is excellent in urine resistance and light resistance and has little coloring. Further, the present invention relates to a water-absorbent resin composition having excellent deodorizing properties.

[0002]

2. Description of the Related Art In recent years, water-absorbent resins have been widely used as sanitary materials such as disposable diapers, sanitary napkins, incontinence pads, etc. for the purpose of absorbing body fluids such as urine and menses. I have. Examples of the water-absorbing resin include a crosslinked product of a partially neutralized polyacrylic acid, a hydrolyzate of a starch-acrylonitrile graft polymer, a neutralized product of a starch-acrylic acid graft polymer, and vinyl acetate-acrylate copolymer. Combined saponified product, crosslinked carboxymethylcellulose, hydrolyzed product of acrylonitrile copolymer or acrylamide copolymer or crosslinked product thereof, crosslinked product of cationic monomer, crosslinked isobutylene-maleic acid copolymer, 2-acrylamide-2 -Crosslinked products of methylpropanesulfonic acid and acrylic acid are known.

[0003] When a water-absorbent resin is used as an absorbent for a disposable diaper, there have been problems in that the water-absorbent resin deteriorates with time, the liquid permeability decreases, the gel strength decreases, and urine leaks from the diaper. Has been pointed out. Since such deterioration of the water-absorbent resin due to urine is considered to be caused by a trace amount of metal ions and L-ascorbic acid contained in urine, a so-called chelating agent is added to the water-absorbent resin to capture the metal ions. In addition, a technique for improving the urine resistance of a water absorbent resin has been proposed. As such a chelating agent, for example, aminoacetic acid-based chelating agents such as sodium diethylenetriamine pentaacetate and sodium triethylenetetraamine hexaacetate are known (Japanese Patent Application Laid-Open No.
246,674, EP 940148A).

[0004]

The aminoacetic acid-based chelating agent is expected to improve not only the urine resistance but also the light resistance of the water-absorbing resin due to its structure. However, in the prior art, only improvement in urine resistance was observed, and light resistance was not different from the case of no addition. On the other hand, since the main use of the water-absorbent resin is as a sanitary material, it is desired that the water-absorbent resin be less colored with time (European Patent No. 942014). It is also desired to reduce the odor generated when the water-absorbent resin absorbs urine and the like (US Pat. No. 5,078,992, JP-A-9-85082).
No.).

Accordingly, a first object of the present invention is to provide a water-absorbent resin composition containing an aminoacetic acid-based chelating agent and having excellent urine resistance and also having excellent light resistance. It is in. A second object of the present invention is to provide a water-absorbing resin composition which is less colored and does not give off a bad odor during use.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies. As a result, the reason why the light resistance is not improved even when an aminoacetic acid-based chelating agent is added in the prior art is that aminoacetic acid is not improved. Nitrilotriacetic acid and / or a salt thereof containing several wt% or more (usually about 5 to 15 wt%) as impurities in the system chelating agent (hereinafter, for convenience, both are collectively referred to as “nitrilotriacetic acid (salt)”) There is). Nitrilotriacetic acid (salt) is also a substance of concern for carcinogenicity (I
Considering that ARC rank 2B) is used for applications in which the water-absorbent resin composition comes into contact with the human body, such as disposable diapers, the content must be reduced as much as possible from the viewpoint of safety.

The aminoacetic acid-based chelating agent generally reacts ammonia with ethylenedichloride or aziridine to obtain diethylenetriamine or triethylenetetraamine, which is then reacted with chloroacetic acid and an alkali agent such as sodium hydroxide. It is thought that unreacted ammonia remains in diethylenetriamine, triethylenetetraamine, etc., and this reacts with chloroacetic acid to produce nitrilotriacetic acid (salt) as an impurity. Can be According to the results confirmed by experiments by the present inventors, from the viewpoint of improving light resistance,
The content of nitrilotriacetic acid (salt) in the composition is 1 ppm or less, preferably 0.5 ppm or less with respect to the composition.
It is more preferably 0.1 ppm or less, and still more preferably 0.01 ppm or less (in the present specification, “ppm” is on a weight basis unless otherwise specified). In addition, it was found that if the content of nitrilotriacetic acid (salt) was reduced in this way, coloring was small. However, simply trying to reduce the content of nitrilotriacetic acid (salt) by reducing the amount of the aminoacetic acid-based chelating agent, although the light resistance is improved, the urine resistance is extremely reduced. I do. That is, it is difficult to maintain and improve urine resistance by adding a chelating agent. According to the results confirmed by experiments by the present inventors, from the viewpoint of maintaining and improving urine resistance, the amount of the aminoacetic acid-based chelating agent is at least 10 ppm, preferably at least 20 ppm, based on the water-absorbing resin. It turned out to be necessary.

From the above, the content of the aminoacetic acid-based chelating agent is set to 10 ppm or more based on the water-absorbing resin, and the content of nitrilotriacetic acid (salt) in the composition is set to 1 ppm or less based on the composition. , Preferably not more than 0.5 ppm, more preferably not more than 0.1 ppm, and still more preferably not more than 0.01 ppm, a water-absorbent resin composition which is excellent in urine resistance, excellent in light resistance, and less colored. Was obtained, and the present invention was completed.
The inventor further sets the above-mentioned composition, that is, the amount of the aminoacetic acid-based chelating agent to be 10 pp with respect to the water absorbent resin.
m or more, and nitrilotriacetic acid (salt) in the composition
In order to facilitate the implementation of a configuration in which the content of is 1 ppm or less with respect to the composition, a diligent study was conducted on a method for reducing the content of nitrilotriacetic acid (salt) contained in the aminoacetic acid-based chelating agent. As a result, both the aminoacetic acid-based chelating agent and the nitrilotriacetic acid are in the form of a salt (—COOX (X: alkali metal or the like)), and both have high solubility in water, so that separation of both is difficult, but the acid (—COOH) In the condition (1), the aminoacetic acid-based chelating agent has low solubility in water, whereas nitrilotriacetic acid has high solubility in water. Therefore, by utilizing the difference in solubility in water, an aqueous solution of an aminoacetic acid-based chelating agent containing nitrilotriacetic acid (salt) is adjusted to pH 1 to 3 to precipitate (an aminoacetic acid-based chelating agent in an acid state). After the precipitation, the precipitate is separated and collected, and if necessary, washed and dried,
The present inventors have found that an aminoacetic acid-based chelating agent for a water-absorbing resin in which the content of nitrilotriacetic acid (salt) is extremely reduced has been obtained, and completed the present invention.

As described above, the present invention employs the following means in order to solve the above-mentioned problems. (1) A water-absorbent resin composition comprising a water-absorbent resin and an aminoacetic acid-based chelating agent, wherein the compounding amount of the aminoacetic acid-based chelating agent is 10 ppm or more based on the water-absorbing resin, and A water-absorbent resin composition, wherein the content of nitrilotriacetic acid and its salt in the product is 1 ppm or less based on the composition. (2) A water-absorbent resin composition comprising a water-absorbent resin and an aminoacetic acid-based chelating agent, wherein the content of nitrilotriacetic acid and a salt thereof in the composition is 1000 ppm or less with respect to the aminoacetic acid-based chelating agent. Certain water absorbing resin compositions.

(3) The water absorbent resin composition according to the above (1) or (2), further comprising a water-soluble deodorant. (4) The above-mentioned (1), wherein the absorption capacity under no load is 30 g / g or more, the dissolved soluble component elution amount is 20% by weight or less, the absorption capacity under 1.9 kPa load is 28 g / g or more, and the coloring degree is 26 or less. The water-absorbent resin composition according to any one of (1) to (3). (5) It contains a water-absorbent resin and a water-soluble deodorant, has an absorption capacity under load of 30 g / g or more, and has a degradable soluble component elution amount of 20 g / g.
Weight% or less, absorption capacity under load of 1.9 kPa: 28 g / g
As described above, the water-absorbent resin composition having an odor reduction rate of 40% or more.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The water-absorbent resin composition according to the present invention is a water-absorbent resin composition containing a water-absorbent resin and an aminoacetic acid-based chelating agent. The content is 10 ppm or more with respect to the water-absorbent resin, and the content of nitrilotriacetic acid (salt) in the composition is 1 ppm or less with respect to the composition. Such a configuration can be easily achieved by using an aminoacetic acid-based chelating agent having a nitrile triacetic acid (salt) content of 1000 ppm or less with respect to the aminoacetic acid-based chelating agent. However, it is not limited to this method.

The aminoacetic acid-based chelating agent having a very small content of nitrilotriacetic acid (salt) is not limited, but, for example, nitrilotriacetic acid (salt) as an impurity.
Aqueous aminoacetic acid-based chelating agent containing
The precipitate can be obtained by separating the precipitate and collecting the precipitate after adjusting to 3 and depositing the precipitate. An aqueous solution of an aminoacetic acid-based chelating agent containing nitrilotriacetic acid (salt) is p
The method of adjusting to H1 to 3 is not particularly limited, but sulfuric acid,
An acid such as nitric acid or hydrochloric acid may be added to the aqueous solution. The pH of the aqueous solution is preferably adjusted to 1.5 to 2.5,
It is more preferable to adjust to 1.8 to 2.0. It is convenient to separate and collect the precipitate by filtration. Washing of the separated and collected precipitate is preferably performed with pure water, and drying is preferably performed at 50 to 200 ° C.

According to this method, the content of nitrilotriacetic acid (salt) in the aminoacetic acid-based chelating agent can be reduced to 1,000 ppm or less, preferably 500 ppm or less, more preferably, to the aminoacetic acid-based chelating agent. 200 ppm or less, more preferably 100 ppm
It is as follows. By adding the aminoacetic acid-based chelating agent obtained as described above and having extremely reduced nitrilotriacetic acid (salt) content to the water-absorbing resin or its raw material, the nitrilotriacetic acid in the water-absorbing resin composition ( Salt) can be very low. Specifically, the content is preferably 1 ppm or less, more preferably 0.5 ppm or less, still more preferably 0.1 ppm or less based on the composition.
Or less, still more preferably 0.01 ppm or less.

The timing of adding the aminoacetic acid-based chelating agent to the water-absorbing resin or its raw material is not particularly limited.
(1) Add to monomer, (2) Add to gel during or after polymerization, (3) Add during surface cross-linking, (4) Add after surface cross-linking, (5) Recover to collect fine particles of water-absorbent resin It can be added in the process. Especially, it is preferable to add at the time of a surface cross-linking process or after a surface cross-linking process. The aminoacetic acid-based chelating agent can be dissolved or dispersed in water or an organic solvent (methanol, ethanol, isopropanol, acetone, etc.) and added to the water-absorbing resin or its raw material. It is preferable to add it after dissolving it in an alkaline solution because of its low solubility in water. As the concentration of the aminoacetic acid-based chelating agent solution,
0.1-40% by weight is preferred, and 1-4 is more preferred.
0% by weight.

The aminoacetic acid-based chelating agent can be added in an amount of 1 ppm to 10% by weight based on the water-absorbing resin, preferably 5 to 1000 ppm.
More preferably, it is 10 to 800 ppm. If the amount of the aminoacetic acid-based chelating agent is too small, no effect of improving urine resistance is obtained, and if it is too large, an effect commensurate with the use cannot be obtained. The compounded aminoacetic acid chelating agent is
Although it depends on the method of blending in the water-absorbent resin, the water-absorbent resin in the water-absorbent resin composition is contained in substantially the same amount as that described above.

Examples of the aminoacetic acid-based chelating agent include ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, cyclohexanediaminotetraacetic acid, and alkali metal salts, ammonium salts and amine salts thereof. Although it can be used, among them, diethylenetriamine 5
Acetic acid, triethylenetetraamine hexaacetic acid and their alkali metal salts are preferred. As the water-absorbing resin that can be used in the water-absorbing resin composition of the present invention, those that absorb a large amount of water in water to form a hydrogel and include those having a carboxyl group, specifically, Crosslinked product of partially neutralized polyacrylic acid, hydrolyzate of starch-acrylonitrile graft polymer, neutralized product of starch-acrylic acid graft polymer, saponified product of vinyl acetate-acrylate copolymer, crosslinked carboxymethyl cellulose , A hydrolyzate of an acrylonitrile copolymer or an acrylamide copolymer or a crosslinked product thereof, a crosslinked product of a cationic monomer, a crosslinked isobutylene-maleic acid copolymer, a mixture of 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid Crosslinked bodies and the like can be mentioned. Among these, a crosslinked product of a partially neutralized polyacrylic acid is most preferred.

In order to obtain a crosslinked product of partially neutralized polyacrylic acid, a hydrophilic monomer having acrylic acid and / or a salt thereof as a main component may be polymerized, and a simple monomer other than acrylic acid and / or a salt thereof may be used. The amount of the monomer is preferably 30 mol% or less in the monomer component. The neutralization rate is 50 to 9 of the acid groups.
Preferably, 5 mol% is neutralized,
More preferably, the mole% is neutralized. Examples of the salt include an alkali metal salt, an ammonium salt, an amine salt and the like. As the polymerization method, it is preferable to carry out aqueous solution polymerization or reverse phase suspension polymerization. In order to make the partially neutralized polyacrylic acid obtained by polymerization a crosslinked product, a self-crosslinking type not using a crosslinking agent may be used,
It is preferable to copolymerize or react an internal crosslinking agent having two or more polymerizable unsaturated groups or two or more reactive groups in one molecule.

Specific examples of the internal crosslinking agent include, for example,
N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, glycerin Acrylate methacrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallylamine, poly (Meth) allyloxyalkane, (poly) ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ethylene glycol, Examples thereof include ethylene glycol, propylene glycol, glycerin, pentaerythritol, ethylene diamine, ethylene carbonate, propylene carbonate, polyethylene imine, and glycidyl (meth) acrylate. These internal crosslinking agents may be used alone or in combination of two or more.

The amount of the internal crosslinking agent to be used is preferably 0.005 to 3 mol%, more preferably 0.01 to 1.5 mol%, based on the monomer components. If the amount of the internal crosslinking agent is too small, the liquid permeability and the absorption rate tend to decrease,
Conversely, if the amount of the internal crosslinking agent is too large, the absorption capacity tends to decrease. When the polymer obtained by the above polymerization is in the form of a hydrogel, it is desirable that the hydrogel is reduced to a predetermined particle size in order to dry the hydrogel later. The hydrous gel can be refined by, for example, performing polymerization while stirring with a double-arm kneader or the like, or by extruding the gel after polymerization from a die using a meat chopper or the like. Further, it can be made finer by a cutting mill or the like. The particle size of the finely divided gel can be appropriately set depending on the capacity of the dryer and the like, but is generally preferably in the range of 0.1 to 10 mm. If the gel is finer than 0.1 mm, the resulting water-absorbent resin may have low physical properties. 10m
If it is larger than m, the gel may not be easily dried.

In the grain refining step, coarse gels larger than 10 mm and fine gels smaller than 0.1 mm can be formed. These polymers can be taken out and added to, for example, an aqueous monomer solution or a polymer gel. The gel refined in the above-mentioned fine-graining step is dried in the drying step. As a drying method, for example, a hot-air dryer, a flash dryer, a fluidized-bed dryer, a drum dryer, a microwave, a far-infrared ray, or the like can be used. The drying temperature is usually 120 ° C. or higher, preferably in the range of 150 to 250 ° C., and more preferably in the range of 160 to 220 ° C. The obtained dried product is pulverized as necessary and classified by a sieve having a predetermined size, so that the average particle size is about 10 to 1000 μm, preferably about 100 to 700 μm, and more preferably about 300 to 700 μm.
A water-absorbent resin powder having a content of fine particles of about 500 μm and less than 106 μm is 5% by weight or less, preferably 3% by weight or less, more preferably 1% by weight or less.

The fine particles of the water-absorbent resin removed by the classification can be collected, recycled, and added in any step of producing the water-absorbent resin. The particle size of the water-absorbent resin (fine particles) to be recovered is not particularly limited.
It is at most 00 μm, preferably at most 225 μm, more preferably at most 150 μm. The water absorbent resin to be recovered may be one before the surface crosslinking treatment or one after the surface crosslinking treatment, and any water absorbing resin can be used. In order to recycle the collected fine particles, water is added to the fine particles for granulation. The amount of water to be added is preferably in the range of 0.1 to 2000 parts by weight, more preferably 10 to 900 parts by weight, based on 100 parts by weight of the water-absorbent resin. When the amount of water added falls below the above range, recycling becomes difficult. If the amount of water exceeds the above range, the recycled water-absorbent resin tends to deteriorate.

When an aminoacetic acid-based chelating agent is added at the time of collecting the fine particles, the chelating agent may be added to the fine particles as an aqueous solution, or the chelating agent may be added to the fine particles mixed with water. After dry-blending the chelating agent and the fine particles, water can be mixed. By crosslinking the vicinity of the surface of the water-absorbent resin powder, the water-absorbing properties of the water-absorbent resin, particularly the absorption capacity under pressure, can be further increased. As the surface cross-linking agent, JP-A-58-1802
No. 33, JP-A-61-16903 and JP-A-5
9-189103, JP-A-52-117393, JP-A-51-136588, JP-A-61-1
JP-A-257235, JP-A-62-2745, JP-A-61-211305, JP-A-61-2522
No. 12, JP-A-61-264006, German Patent No. 4020780, WO99 / 42494, WO99 / 43720, WO00 / 3115
No. 3, JP-A-2000-197818, and the like. Specifically, it is only necessary to have two or more functional groups capable of reacting with the functional groups on the surface of the water-absorbing resin. Examples thereof include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol. 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentadiol, polypropylene glycol, glycerin, polyglycerin, glycerophosphoric acid, 2-butene-
1,4-diol, 1,3-butanediol, 1,4-
Butanediol, 1,5-pentanediol, 1,6-
Polyvalent such as hexanediol, 1,2-cyclohexanedimethanol, 1,2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol and sorbitol Alcohol compounds: (polyvalent) such as ethylene glycol diglycidyl ether, polyethylene diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycidol, etc. Epoxy compounds: ethylenediamine, diethylenetriamine, triethylenetetramine, tetra Polyvalent amine compounds such as tylenepentamine, pentaethylenehexamine, and polyethyleneimine, and inorganic or organic salts thereof (eg, aditinium salt); polyvalent isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate Polyvalent oxazoline compounds such as 1,2-ethylenebisoxazoline, polyisopropenyloxazoline and copolymers thereof; 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, , 5-Dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-
1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxane-2
-One, 4,6-dimethyl-1,3-dioxane-2-
Alkylene carbonate compounds such as on, 1,3-dioxopan-2-one; haloepoxy compounds such as epichlorohydrin, epibromohydrin, α-methylepichlorohydrin, and polyamine adducts thereof (eg, Hercules) Silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane; hydroxides and chlorides such as zinc, calcium, magnesium, aluminum, iron and zirconium And the like. Among these, polyhydric alcohol compounds, (polyvalent) epoxy compounds, polyamine compounds and salts thereof,
Alkylene carbonate compounds are preferred. These surface crosslinking agents may be used alone or in combination of two or more.

The amount of the surface cross-linking agent may be selected from water-absorbent resin 10
It is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 0 parts by weight. When the amount of the surface cross-linking agent is less than 0.01 part by weight, the surface cross-linking becomes insufficient. When used in an amount exceeding 10 parts by weight, the absorption capacity may be extremely reduced. After mixing the water-absorbing resin and the surface cross-linking agent, a heat treatment is performed if necessary. An ordinary dryer or heating furnace can be used for the heat treatment. For example, a channel-type stirring dryer, a rotary dryer, a disk dryer, a fluidized-bed dryer, a flash dryer, an infrared dryer, and the like. In that case, the heat treatment temperature is preferably 40 to 250.
° C, more preferably 90 to 230 ° C, still more preferably 120 to 220 ° C. When the heat treatment temperature is lower than 40 ° C., the heat treatment takes a long time and causes a decrease in productivity. On the other hand, when the heat treatment temperature exceeds 250 ° C.,
Depending on the type of water-absorbing resin used, there is a risk of causing thermal degradation. The heat treatment time is usually 1 to 120
Minutes is preferable, and 10 to 60 minutes is more preferable.

When an aminoacetic acid-based chelating agent is added at the time of the surface crosslinking treatment, the water-absorbing resin is mixed with the surface crosslinking agent and the aminoacetic acid-based chelating agent, and a heat treatment is performed if necessary. At the time of the mixing, it is preferable to use water. As the amount of water, with respect to 100 parts by weight of the water absorbent resin,
The range is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 3 parts by weight. If the amount of water is below the above range, it becomes difficult to fix the aminoacetic acid-based chelating agent on the surface of the water-absorbing resin particles. If the amount of water exceeds the above range, the absorption capacity of the water absorbent resin may be reduced. The conditions for the heat treatment are the same as in the case where no aminoacetic acid-based chelating agent is added.

When the aminoacetic acid-based chelating agent is added after the surface crosslinking treatment, the aminoacetic acid-based chelating agent and water are added to the surface-crosslinked water-absorbing resin by spraying or the like, and water is used as a binder. It is preferable to combine the particles of the water-absorbing resin and granulate them. Thereby, the aminoacetic acid-based chelating agent can be fixed on the surface of the water-absorbing resin. Since the deterioration of the water-absorbent resin due to urine occurs from the resin surface, urinating resistance can be improved by disposing an aminoacetic acid-based chelating agent near the surface of the water-absorbent resin. The amount of water used at this time is preferably in the range of 0.1 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, and still more preferably 0.5 to 4 parts by weight, per 100 parts by weight of the water absorbent resin.
Parts by weight. If the amount of water is less than the above range, it becomes difficult to granulate the water-absorbent resin particles, and it becomes difficult to fix the aminoacetic acid-based chelating agent on the surface of the water-absorbent resin particles. When the amount of water exceeds the above range, the desired granulated product cannot be obtained because the water swells to the inside of the water absorbent resin to form a gel, and the surface crosslinked layer on the surface of the water absorbent resin particles is broken. There is a possibility that it will.

The water-absorbent resin composition according to the present invention may contain a water-soluble deodorant in order to exhibit deodorant properties. The reason why a water-soluble deodorant is used is that the water-soluble deodorant imparts excellent deodorant performance to the water-absorbent resin composition without lowering the absorption performance of the water-absorbent resin composition. It is. Here, the water-soluble deodorant is one that can be dissolved in 100 g of deionized water at room temperature in an amount of 0.1 g or more, preferably 1 g or more, and more preferably 10 g or more. As such a deodorant, various known substances such as extracts from leaves of a camellia plant can be used. Camellia plants include, for example, camellia, tea tree, sasanqua,
Sakaki, Hisakaki, etc., using alcohol-based, ketone-based organic solvents, water or a mixed solvent thereof,
Deodorant components can be extracted from these leaves. The extracted components include flavonols, flavanols, organic polymers or tannins. The compounding ratio of the deodorant is preferably 0.0001% by weight (1 ppm) to 10% by weight with respect to the water absorbent resin. When the blending ratio of the deodorant falls below the above range, no deodorizing effect is exhibited, and when the blending ratio of the deodorant exceeds the above range, the effect corresponding to the cost increase cannot be obtained. The deodorant is, for example, 1) dissolved in water or an organic solvent such as alcohol and sprayed on the water-absorbing resin (or its composition), or 2) does not swell the water-absorbing resin (or its composition). Add to the solvent together with the water-absorbing resin, stir and mix, then remove the solvent or 3) powder or granulate and mix with the water-absorbing resin (or its composition)
It is blended into the water-absorbing resin composition. The deodorant is preferably added at the same time as the addition of the granulating or chelating agent.

Examples of the deodorant other than the extract from the leaves of the above Camellia plant include organic acids such as acetic acid, citric acid and lactic acid, sodium iron chlorophyllin, sodium copper chlorophyllin, cyclodextrin and flavonoid compounds. Can be The mixing ratio of these is 0.0001% by weight (1 ppm) to 10% by weight with respect to the water absorbent resin.
The degree is preferred. The water-absorbent resin composition of the present invention configured as described above has the following characteristics or properties. Absorption capacity under no load of 30 g / g or more, preferably 3
It is 4 g / g or more, more preferably 40 g / g or more, and the eluted amount of the deteriorated soluble component is 20 wt% or less, preferably 18 wt% or less, more preferably 16 wt% or less, and the absorption capacity under a load of 1.9 kPa. Is 28 g / g or more,
It is preferably at least 30 g / g, more preferably 32 g / g.
g or more, and the coloring degree is 26 or less, preferably 24 or less, more preferably 22 or less.

The absorption capacity under no load is 30 g / g or more,
It is preferably at least 34 g / g, more preferably 40 g / g.
g or more, and the eluted amount of the deteriorated soluble component is 20% by weight or less, preferably 18% by weight or less, more preferably 16% by weight or less.
% By weight or less, and the absorption capacity under a load of 1.9 kPa is 28.
g / g or more, preferably 30 g / g or more, more preferably 32 g / g or more, and the odor reduction rate is 40% or more, preferably 45% or more, more preferably 50% or more. When a water-absorbent resin composition having an absorption capacity under no load of less than 30 g / g is used for an absorbent article, the absorption amount of the absorbent article is small, and leakage tends to occur.

When a water-absorbent resin composition having an elution amount of the deteriorated soluble component exceeding 20% by weight is used for an absorbent article, the slimy feeling becomes large after long-term use. When a water-absorbent resin composition having an absorption capacity under a load of 1.9 kPa of less than 28 g / g is used for an absorbent article, the absorption amount of the absorbent article is small, and leakage tends to occur. When a water-absorbent resin composition having a coloring degree of more than 26 is used for an absorbent article such as a disposable diaper or a napkin, the water-absorbent resin composition tends to be colored during storage of the absorbent article, and as a result, the water-absorbent resin composition is absorbed. It becomes visible through the surface of the article. When the coloring degree is 26 or less, the ink is resistant to storage, and the water-absorbent resin composition cannot be identified through the surface of the absorbent article. As a result, complaints from consumers are reduced.

When a water absorbing resin composition having a malodor reduction rate of less than 40% is used for a diaper, the deodorizing effect is weak or not at all. However, when a water-absorbing resin composition having an odor reduction rate of 40% or more is used, a deodorizing effect can be obtained. The water-absorbent resin composition of the present invention can also be imparted with a new function by including a fragrance, a drug, a plant growth aid, a bactericide, a foaming agent, a pigment, a dye, a fertilizer, and the like. The water-absorbent resin composition of the present invention is irregularly crushed, spherical, rod-shaped, particles having various shapes such as granules, the weight average particle diameter thereof is preferably in the range of 100 to 600 μm, more preferably Is in the range of 200 to 500 μm. Further, the ratio of the water-absorbent resin in the water-absorbent resin composition,
Usually 75% by weight or more, preferably 85% by weight, based on the composition.
% By weight or more, more preferably 95% by weight or more.

The water-absorbent resin composition of the present invention absorbs not only water but also various liquids including water such as body fluids, physiological saline, urine, blood, cement water, and fertilizer-containing water. Sanitary materials such as sanitary napkins and incontinence pads, as well as various industrial fields such as civil engineering, agriculture and horticulture, etc., but with their excellent urine resistance, disposable diapers (for discipline infants to urinate and defecate) It is particularly suitably used as a sanitary material for absorbing urine, such as pants with a disposable diaper used in such cases, and incontinence pads. Next, an absorbent article using the water absorbent resin composition of the present invention will be described. Absorbent articles using the water-absorbent resin composition of the present invention,
Absorbent layer comprising the water-absorbent resin composition of the present invention and a fiber substrate,
An absorbent article comprising a liquid-permeable top sheet and a liquid-impermeable back sheet, wherein the weight ratio α of the water-absorbent resin composition to the total amount of the water-absorbent resin composition and the fiber base material is usually 0. .2 or more. α is preferably 0.
It is in the range of 3 to 1.0, more preferably 0.4 to 0.8.

When the weight ratio α is less than 0.2, the absorbent article is generally bulky and has a large amount of return. In particular, when the water-absorbent resin composition of the present invention is used, since the coloring during the initial stage of production and with the lapse of time is extremely small, even when the water-absorbent resin composition is mixed at a high concentration of α of 0.2 or more, Coloring is not a problem and is very preferable. When the water-absorbent resin composition of the present invention that satisfies the malodor reduction rate defined above is used at a high concentration of α of 0.2 or more, the deodorizing effect is high, and it is very preferable. According to the method for producing the absorbent article, an absorbent (absorbent core) is produced by blending or sandwiching a fiber base material and a water-absorbent resin composition, and the absorbent core is formed from a liquid-permeable surface material and a liquid-impermeable base material. An absorbent article, especially a sanitary napkin or an adult diaper may be formed by sandwiching with a material and providing an elastic member, a diffusion layer, an adhesive tape or the like as necessary. Such an absorbent core has a density of 0.06 to 0.5 g / cc and a basis weight of 0.01 to 0.20 g.
/ Cm ^{2 in} the range of compression molding. In addition, as a fiber base material to be used, hydrophilic fibers, for example, pulverized wood pulp, cotton linter, crosslinked cellulose fiber, rayon, cotton, wool, acetate, vinylon, and the like can be exemplified. Preferably, they are air-laid.

[0033]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. In the following, “parts”, “%”, and “water-absorbent resin (composition)” are used unless otherwise specified.
The terms “parts by weight”, “% by weight”, and “water-absorbent resin or water-absorbent resin composition” are respectively represented. (1) Absorption capacity under no load of water-absorbent resin (composition) 0.2 g of water-absorbent resin (composition) was added to a tea bag type bag (6
(cm × 6 cm), the opening was heat-sealed, and then immersed in a 0.9% aqueous sodium chloride solution (physiological saline) at room temperature. After 60 minutes, the tea bag type bag is pulled up, and 250 G (cm / sec ² ) is used using a centrifuge.
, And the weight W ₁ (g) of the bag was measured. The same operation was performed without using the water-absorbing resin (composition), and the weight W ₀ (g) at that time was measured.
The absorption capacity under no load (g / g) was calculated from the weights W ₁ and W ₀ according to the following equation.

Absorption capacity under no load (g / g) = (W ₁ -W
₀ ) / Weight (g) of water-absorbent resin (composition) (2) Elution amount of soluble component of water-absorbent resin (composition) In a 100 ml beaker, 1 g of water-absorbent resin (composition) is swollen into 25 ml of artificial urine And cover the beaker at 37 ℃
For 16 hours. Then 975 ml of swollen gel
Was dispersed in deionized water, and the eluted soluble matter was rinsed with deionized water. After stirring for 1 hour, the mixture was filtered with filter paper.
Next, 50 g of the obtained filtrate was placed in a 100 ml beaker, and 1 m of a 0.1 N aqueous solution of sodium hydroxide was added to the filtrate.
1, N / 200-methyl glycol chitosan aqueous solution 10
ml and 4 drops of an aqueous 0.1% toluidine blue solution were added. Next, the solution in the beaker is subjected to colloid titration with an N / 400-polyvinyl potassium sulfate aqueous solution,
The time when the color of the solution changed from blue to reddish purple was determined as the end point of the titration, and the titer B ₁ (ml) was determined. Further, the same operation was performed without using the water-absorbing resin (composition), and the titer C ₁ (ml) was obtained as a blank. Then, based on these titration amounts B ₁ and C ₁ and the molecular weight D ₁ of the repeating unit of the water-absorbing resin (for example, 88.5 in the case of polyacrylic acid having a neutralization ratio of 75%), water absorption is calculated according to the following equation. The soluble component elution amount (% by weight) of the hydrophilic resin (composition) was calculated.

Eluted amount of soluble component (% by weight) = (C₁-B
₁) × 0.005 × D₁ The composition of the artificial urine is shown below. Deionized water 97.1% Urea 1.9% Sodium chloride 0.8% Magnesium chloride 0.1% Calcium chloride 0.1% (3) Degradation of water-absorbent resin (composition) Amount of soluble component eluted L-ascorbic acid Using artificial urine containing 0.005% by weight
In a 100 ml plastic container with a lid
Swell 1 g of fat (composition) 25 times, cover the container,
It was left at 37 ° C. for 16 hours. Then, the resulting swollen gel is
Dissolved in 975g of deionized water and eluted
The minute was rinsed with deionized water. After stirring for 1 hour, filter paper
And filtered. Next, 50 g of the obtained filtrate was added to a 100 ml vial.
And the filtrate is added to a 0.1N aqueous solution of sodium hydroxide.
1 ml of solution, N / 200-methyl glycol chitosan water
10 ml of solution and 0.1% aqueous solution of toluidine blue 4
Drops were added. Next, the solution in the beaker was added to N / 4
Colloid using aqueous solution of 00-polyvinyl potassium sulfate
Titrate and titrate when the color of the solution changes from blue to magenta.
Titration B as the fixed end point_Two(Ml) was determined. Also suck
Perform the same operation without using the aqueous resin (composition),
Titration C as rank_Two(Ml) was determined. And this
Their titer B_TwoAnd C_TwoAnd water-absorbent resin
Molecular weight D _Two(For example, polyacrylic with a neutralization rate of 75%
Is 88.5 in the case of phosphoric acid).
Elution amount of soluble components (weight%) of aqueous resin (composition)
Was calculated.

Amount of dissolved soluble component eluted (% by weight) = (C ₂
−B ₂ ) × 0.005 × D ₂ (4) Absorption capacity under load The absorption capacity under load was determined using the measuring apparatus shown in FIG.
As shown in FIG. 1, the measuring device includes a balance 1, a container 2 having a predetermined capacity mounted on the balance 1, an outside air suction pipe 3, a conduit 4, a glass filter 6, and a measurement mounted on the glass filter 6. It consists of part 5. The container 2 has an opening 2a at the top and an opening 2b at the side. Opening 2a
Is fitted with an outside air suction pipe 3, and a conduit 4 is attached to the opening 2b. The container 2 contains a predetermined amount of a 0.9% aqueous sodium chloride solution (hereinafter, referred to as physiological saline) 12. The lower end of the outside air suction pipe 3 is submerged in the physiological saline 12. The outside air suction pipe 3 is provided to keep the pressure in the container 2 at substantially the atmospheric pressure. The above glass filter 6 has a diameter of 55 mm.
Is formed. Container 2 and glass filter 6
Are connected to each other by a conduit 4 made of silicone resin. Further, the position and height of the glass filter 6 with respect to the container 2 are fixed. The above measuring unit 5
Has a filter paper 7, a support cylinder 9, a wire mesh 10 attached to the bottom of the support cylinder 9, and a weight 11. The measuring unit 5 has a filter paper 7 and a support cylinder 9 (that is, a wire mesh 10) placed on a glass filter 6 in this order. The wire mesh 10 is made of stainless steel and has a mesh size of 400 mesh (mesh size 38 μm). The height of the upper surface of the wire mesh 10, that is, the height of the contact surface between the wire mesh 10 and the water absorbent resin (composition) 15 is set to be equal to the height of the lower end surface 3 a of the outside air suction pipe 3. A predetermined amount of a water-absorbent resin (composition) 15 is evenly spread on the wire mesh 10. Weight 1
The weight of 1 is adjusted so that a load of 4.83 kPa or 1.9 kPa can be uniformly applied to the wire net 10, that is, the water absorbent resin (composition) 15.

The absorption capacity under load was measured using the measuring apparatus having the above-mentioned structure. The measuring method will be described below. A predetermined preparation operation, such as putting a predetermined amount of physiological saline 12 into the container 2 and fitting the outside air suction pipe 3 into the container 2, was performed. Next, the filter paper 7 was placed on the glass filter 6.
In parallel with the placement, the inside of the support cylinder 9, that is, the wire mesh 1
Then, 0.9 g of the water-absorbent resin (composition) 15 was uniformly dispersed on the water-absorbent resin 15, and the weight 11 was placed on the water-absorbent resin (composition) 15. Next, on the filter paper 7, the supporting cylinder 9 on which the wire mesh 10, that is, the water-absorbent resin (composition) 15 and the weight 11 were placed, was placed so that the center part thereof coincided with the center part of the glass filter 6. . Next, the supporting cylinder 9 is placed on the filter paper 7.
The weight of the physiological saline absorbed by the water-absorbent resin (composition) 15 was determined from the measured value of the balance 1 over a period of 60 minutes from the time when the sample was placed. The same operation was performed without using the water-absorbent resin (composition) 15, and the weight of the physiological saline absorbed by the materials other than the water-absorbent resin (composition) 15 was determined from the measured value of the balance 1. Was taken as the blank value. The absorption capacity under load was determined by the following equation.

Absorption capacity under load (g / g) = (water absorption after 60 minutes−blank value) / weight of water-absorbing resin (composition) (g) (5) Analysis of chelating agent Chelating agent is dissolved in water Then, the content of nitrilotriacetic acid (salt) in the chelating agent was analyzed using high performance liquid chromatography under the following conditions. (Eluent) 0.3ml of 0.4mol / L alum solution, 0.1NK
OH solution 450ml, 40% tetra n-butylammonium hydroxide aqueous solution 3ml, sulfuric acid 3ml, water 2550ml, ethylene glycol 1.5ml (column) Merck LichroCART 250-4 Supersphe
r 100 RP-18e (4 μm) (Flow rate) 1 ml / min (Detector) UV258 nm (Injection) 50 μl (6) Nitrilotriacetic acid (salt) content in the water-absorbent resin composition 1 g of the water-absorbent resin composition Stir and filter in 100 g of saline for 1 hour, and nitrilotriacetic acid (salt) contained in the filtrate
Was measured by the liquid chromatography of the above (5), and the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition was quantified.

(7) Method of evaluating coloring with time of water-absorbent resin composition Water-absorbent resin composition (particle size of 600 to 3 unless otherwise specified)
A dry container having a diameter of 55 μm and a height of 70 mm (made of Terraoka Co., Ltd., capacity: 12 μm).
Spray 2.000 g on the bottom of 0 cc, Pack-Ace, open the container without a lid, and use a constant temperature and humidity machine (PLATINOUSLUCIFE, manufactured by Tabai Espec Co., Ltd.).
R, model number PL-2G) in a 70 ° C., 80% RH atmosphere for 5 days. The amount of the water-absorbent resin composition applied per unit area (0.084 g / cm ² ) is a model amount applied to the high-concentration core.

After 5 days, all of the water-absorbent resin composition in the container was filled in the following powder / paste sample table (30 mmφ), and the degree of coloration (YI) was measured by the spectral color difference of Nippon Denshoku Industries Co., Ltd. Total (SZ- $ 80 COLOR ME
ASURING SYSTEM), set conditions (reflection measurement / attached powder / paste sample table (30 mm
φ) / Standard for powder and paste, standard round white plate NO2
/ 30 mmφ light-emitting pipe) to measure the surface color of the water-absorbent resin composition. (8) Deodorizing property measurement (method for evaluating offensive odor reduction rate) A water-absorbent resin was placed in a polypropylene container having a diameter of 69 mm, a lower diameter of 63 mm, a height of 97 mm and a sealable volume of 250 ml (Teraoka Co., Ltd., 250 cc Pack-Ace). 5 g of the composition was placed. Next, 30 g of artificial urine to which a 0.5% aqueous solution of a 15% by weight aqueous solution of methyl mercaptan (manufactured by Tokyo Chemical Industry Co., Ltd.) diluted with deionized water was added as a malodorous component was placed in a container, and gas did not leak. Cover and seal as described. 25 ° C, 55
After leaving for 4 hours under the condition of% RH, the concentration of methyl mercaptan in the space in the container was measured with a detector and a detector tube of Gastech Co., Ltd., and the obtained result was defined as G1. The detector tube is Gastech No. Using a total of 70 mercaptans (measurement range: 0.5 to 120 ppm), the measurement method was as follows according to the operation specified for the detector tube. The detection tube is suctioned once (100 ml, 2
Min). When measuring concentrations below 5 ppm, aspirate 2-10 times and divide the reading by the number of aspirations. Since the used detector tube is calibrated with ethyl mercaptan,
Conversion coefficient 0.7 for methyl mercaptan (number of suction = 1)
Was applied to measure the concentration.

Next, without placing the water-absorbent resin composition and artificial urine in a container, 0.5 ml of a 15% by weight aqueous solution of methyl mercaptan sodium (manufactured by Tokyo Chemical Industry Co., Ltd.) diluted 500 times with deionized water was used. The same operation as described above was carried out except for the insertion, and the methylmercaptan concentration in the space in the container was measured, and the obtained result was defined as G0. And the odor reduction rate was calculated by the following equation. Odor reduction rate (%) = (G0−G1) / G0 × 100 Reference Example 1 37% aqueous solution of sodium acrylate
0 part, 10.2 parts of acrylic acid, 0.079 part of polyethylene glycol diacrylate (average number of ethylene oxide units: 8) and 22.0 parts of water were mixed to prepare an aqueous monomer solution. Nitrogen was blown into the monomer aqueous solution in the vat to reduce the dissolved oxygen in the solution to 0.1 ppm or less.

Subsequently, the temperature of the aqueous monomer solution was adjusted to 18 ° C. under a nitrogen atmosphere, and then 0.16 parts of a 5% aqueous sodium persulfate solution and 5% 2,2′-azobis (2-amidinopropane) dihydrochloride aqueous solution were added. .16 parts, 0.5% L
-0.15 parts of an aqueous solution of ascorbic acid and 0.17 parts of a 0.35% aqueous hydrogen peroxide solution were added dropwise with stirring in order. Immediately after the dropwise addition of hydrogen peroxide, polymerization started. Thereafter, stirring was stopped, and after 10 minutes, the temperature of the monomer reached the peak temperature. The peak temperature was 85 ° C. Continue with 8 bats
It was immersed in a water bath at 0 ° C. and aged for 10 minutes. The resulting transparent hydrogel was crushed with a meat chopper and then dried at 180 ° C. for 30 minutes.

The dried product was pulverized with a pulverizer, passed through a 500 μm sieve, and classified into a residue remaining on a 105 μm sieve to obtain a water-absorbent resin (A). 100 parts of the water-absorbent resin (A) was mixed with a composition liquid comprising 0.05 parts of ethylene glycol diglycidyl ether, 1 part of propylene glycol, 3 parts of water and 1 part of isopropyl alcohol, and heated at 180 ° C. for 40 minutes. A surface crosslinked water-absorbent resin (B) was obtained. Table 1 shows the results of measuring the properties of the surface crosslinked water-absorbent resin (B). [Example 1] 60% sulfuric acid was added to a commercially available aqueous solution of pentasodium diethylenetriaminepentaacetate (solid content 40%) under stirring to adjust the pH to 1.8 to 2. This solution was left for a while, and the precipitated diethylenetriaminepentaacetic acid was filtered, washed with pure water, and dried at 60 ° C.

The commercially available diethylenetriaminepentaacetic acid 5
Sodium contained about 5% of nitrilotriacetic acid (salt). By the above treatment, the content of nitrilotriacetic acid (salt) in diethylenetriaminepentaacetic acid was reduced to 35 ppm based on the diethylenetriaminepentaacetic acid. . To 0.002 parts of diethylenetriaminepentaacetic acid having a reduced nitrilotriacetic acid (salt) content obtained above, 0.05 g of ethylene glycol diglycidyl ether was added.
Parts, 1 part of propylene glycol, 3 parts of water and 1 part of isopropyl alcohol were mixed with 100 parts of the water absorbent resin (A) obtained in Reference Example 1,
Heat-treated at 80 ° C. for 40 minutes to obtain a water-absorbent resin composition (1)
(The blending amount of diethylenetriaminepentaacetic acid with respect to the water absorbent resin (A) was 20 ppm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (1) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 1 shows the results of measuring the properties of the water-absorbent resin composition (1). Example 2 A water-absorbent resin composition (2) was obtained in the same manner as in Example 1 except that the amount of diethylenetriaminepentaacetic acid in the treating agent solution was changed to 0.01 part. Diethylene triamine 5 for the hydrophilic resin (A)
The amount of acetic acid is 100 ppm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (2) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 1 shows the results of measuring the properties of the water-absorbent resin composition (2). Example 3 The diethylenetriaminepentaacetic acid obtained in Example 1 and having a reduced nitrilotriacetic acid (salt) content was dissolved in water to prepare a 0.07% aqueous solution. 3 parts of this solution was sprayed on 100 parts of the water-absorbent resin (B) obtained in Reference Example 1, and then dried at 80 ° C. to obtain a water-absorbent resin composition (3) (water-absorbent resin (B)). The blending amount of diethylenetriaminepentaacetic acid with respect to the amount of 21 ppm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (3) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 1 shows the measurement results of the properties of the water-absorbent resin composition (3). Example 4 In Example 3, diethylenetriamine 5
A water-absorbent resin composition (4) was obtained in the same manner as in Example 3 except that the concentration of the acetic acid aqueous solution was changed to 0.5% (the blending amount of diethylenetriaminepentaacetic acid with respect to the water-absorbent resin (B) was 150 ppm). . When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (4) was measured, it was not more than 0.1 ppm with respect to the composition and could not be measured.
Table 1 shows the measurement results of the properties of the water-absorbent resin composition (4).

Example 5 The diethylenetriaminepentaacetic acid having a reduced nitrilotriacetic acid (salt) content obtained in Example 1 was dissolved in water to prepare a 0.1% aqueous solution. In Reference Example 1, drying, pulverization, and surface treatment were performed in the same manner as in Reference Example 1 except that 3.5 parts of the above aqueous solution was added when pulverizing 100 parts of the gel after polymerization with a meat chopper. A resin composition (5) was obtained (the blending amount of diethylenetriaminepentaacetic acid with respect to the solid content (substantially water-absorbent resin) in the gel was 100 ppm). When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (5) was measured, it was 0.1 ppm or less with respect to the composition and could not be measured. Table 1 shows the results of measuring the properties of the water-absorbent resin composition (5).

Example 6 The diethylenetriaminepentaacetic acid having a reduced nitrilotriacetic acid (salt) content obtained in Example 1 was mixed with sodium hydroxide and water to give 35% of diethylenetriaminepentaacetic acid tetrasodium. %
An aqueous solution was prepared. This aqueous solution was diluted 200 times with water. 3 parts of this diluted solution was spray-mixed with 100 parts of the water-absorbent resin (B) obtained in Reference Example 1 and heated at 80 ° C. to obtain a water-absorbent resin composition (6) (water-absorbent resin (B) ), The amount of diethylenetriaminepentaacetic acid tetrasodium is 5
2.5 ppm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (6) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 1 shows the measurement results of the properties of the water-absorbent resin composition (6). Example 7 A treating agent solution comprising 3 parts of the diluted solution obtained in Example 6, 0.05 part of ethylene glycol diglycidyl ether, 1 part of propylene glycol, and 1 part of isopropyl alcohol was obtained in Reference Example 1. The mixture was mixed with 100 parts of the water-absorbent resin (A) and heat-treated at 180 ° C. for 40 minutes to obtain a water-absorbent resin composition (7). 52.5 ppm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (7) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 1 shows the results of measuring the properties of the water-absorbent resin composition (7). Example 8 Commercially available triethylenetetraamine-6-acetic acid 6
60% sulfuric acid was added to the aqueous sodium solution (solid content 40%) under stirring to adjust the pH to 1.8 to 2. The solution was left for a while, and the precipitated triethylenetetraamine hexaacetic acid was filtered, washed with pure water, and dried at 60 ° C.

The content of nitrilotriacetic acid (salt) in the obtained triethylenetetraamine hexaacetic acid was 20 ppm based on the triethylene tetraamine hexaacetic acid. This triethylenetetraamine hexaacetic acid having a reduced nitrilotriacetic acid (salt) content, sodium hydroxide and water are mixed to form triethylene tetraamine hexaacetic acid 5
A 35% aqueous solution of sodium was prepared. This aqueous solution was diluted 200 times with water. 3 parts of this diluted solution was spray-mixed with 100 parts of the water-absorbent resin (B) obtained in Reference Example 1,
To obtain a water-absorbent resin composition (8) (triethylenetetraamine-6-acetic acid 5 based on water-absorbent resin (B)).
The content of sodium is 52.5 ppm).

When the content of nitrilotriacetic acid (salt) in the water absorbent resin composition (8) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 1 shows the measurement results of the properties of the water-absorbent resin composition (8). Comparative Example 1 The procedure of Example 2 was repeated, except that a commercially available aqueous solution of pentasodium diethylenetriaminepentaacetate was used in place of diethylenetriaminepentaacetic acid having a reduced nitrilotriacetic acid (salt) content in Example 2. In the same manner as in the above, a comparative water-absorbent resin composition (1) was obtained.

The content of nitrilotriacetic acid (salt) in the comparative water absorbent resin composition (1) was 5 ppm based on the composition. Table 1 shows the results of measuring the properties of the comparative water absorbent resin composition (1). [Reference Example 2] 37% aqueous solution of sodium acrylate 76
Parts, acrylic acid 7 parts, polyethylene glycol diacrylate (average number of ethylene oxide units 8) 0.0
5 parts and 15 parts of water were mixed to prepare a monomer aqueous solution.
In a double-armed kneader equipped with a jacket, nitrogen was blown into the aqueous monomer solution to remove dissolved oxygen in the solution.
Subsequently, the temperature of the aqueous monomer solution was adjusted to 22 ° C.

Next, 1 part of a 5% aqueous solution of sodium persulfate and 0.5% of an aqueous L-ascorbic acid solution were added with stirring.
04 parts were added. One minute after the addition, the aqueous monomer solution began to become cloudy and the temperature began to rise. After 20 minutes, the peak temperature was reached, and the mixture was aged for 20 minutes with further stirring. The peak temperature was 94 ° C. Take out the gel obtained after aging,
Dry at 170 ° C. for 65 minutes. The dried polymer was pulverized, passed through an 850 μm sieve, and classified into a material remaining on a 105 μm sieve to obtain a water-absorbent resin (C). Water absorbent resin (C)
100 parts was mixed with a composition solution consisting of 0.05 part of ethylene glycol diglycidyl ether, 1 part of propylene glycol, 3 parts of water and 1 part of isopropyl alcohol,
Heat treatment was performed at 80 ° C. for 40 minutes to obtain a surface crosslinked water-absorbent resin (D).

Table 1 shows the measurement results of the physical properties of the surface crosslinked water-absorbent resin (D). Example 9 A mixture of diethylenetriaminepentaacetic acid having a reduced nitrilotriacetic acid (salt) content obtained in Example 1, sodium hydroxide and deionized water, and a 35% aqueous solution of tetrasodium diethylenetriaminepentaacetate were prepared. Was prepared. This aqueous solution was diluted 200 times with deionized water, and 3 parts of the diluted solution was used as the water-absorbent resin (D) 1 obtained in Reference Example 2.
The mixture was spray-mixed into 00 parts and heated at 80 ° C. to obtain a water-absorbent resin composition (9) (the mixing amount of tetrasodium diethylenetriaminepentaacetate with respect to the water-absorbent resin (D) was 52.5 p
pm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (9) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 1 shows the results of measuring the properties of the water-absorbent resin composition (9). [Comparative Example 2] The commercially available aqueous solution of pentasodium diethylenetriaminepentaacetate used in Example 1 was deionized water for 200 hours.
Diluted 1-fold. 3 parts of this diluted solution was spray-mixed with 100 parts of the water-absorbent resin (D) obtained in Reference Example 2 and heated at 80 ° C. to obtain a comparative water-absorbent resin composition (2).

The content of nitrilotriacetic acid (salt) in the comparative water absorbent resin composition (2) was 3 ppm based on the composition.
Met. Table 1 shows the results of measuring the properties of the comparative water absorbent resin composition (2). <Comparison of light resistance>: water-absorbent resin composition (9) obtained in Example 9, comparative water-absorbent resin composition (2) obtained in Comparative Example 2,
Each 1 g of the water-absorbent resin (D) obtained in Reference Example 2 was swollen in 100 g of deionized water in a polypropylene container. The container was capped and left inside a sunny window for 5 days.

After standing for 5 days, the gel was dispersed in 900 ml of deionized water, and the eluted soluble matter was rinsed with deionized water. After stirring for 1 hour, the mixture was filtered with filter paper, and the obtained filtrate was titrated by colloid titration to determine the amount of soluble matter (%) eluted from each water absorbent resin (composition). The smaller the amount of soluble matter (%), the higher the light resistance. The results were as follows. Water-absorbent resin composition (9) 32% Comparative water-absorbent resin composition (2) 50% Water-absorbent resin (D) 50% From the above results, it was found that the aminoacetic acid-based chelating agent containing a large amount of nitrilotriacetic acid (salt) has light resistance. It can be seen that light resistance can be improved by reducing the content of nitrilotriacetic acid (salt).

Example 10 The diethylenetriaminepentaacetic acid obtained in Example 1 and having a reduced nitrilotriacetic acid (salt) content was mixed with sodium hydroxide and deionized water to obtain diethylenetriaminepentaacetic acid. A 40% aqueous solution of sodium was prepared. The resulting diethylenetriaminepentaacetic acid pentasodium aqueous solution (solid content 40%)
0% sulfuric acid was added under stirring to adjust the pH to 1.8-2. This solution was left for a while, and the precipitated diethylenetriaminepentaacetic acid was filtered, washed with pure water, and dried at 60 ° C.

The content of nitrilotriacetic acid (salt) in the obtained diethylenetriaminepentaacetic acid was 0.1 ppm or less with respect to the diethylenetriaminepentaacetic acid, and could not be measured. The diethylenetriaminepentaacetic acid having a reduced nitrilotriacetic acid (salt) content obtained above was mixed with sodium hydroxide and deionized water to prepare a 35% aqueous solution of tetrasodium diethylenetriaminepentaacetate. This aqueous solution was diluted 200 times with deionized water.
3 parts of this diluted solution was spray-mixed with 100 parts of the water-absorbent resin (B) obtained in Reference Example 1 and heated at 80 ° C. to obtain a water-absorbent resin composition (10) (water-absorbent resin (10)). The blending amount of diethylenetriaminepentaacetic acid tetrasodium with respect to B) is 52.5 ppm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (10) was measured, it was not more than 0.1 ppm with respect to the composition and could not be measured. Table 2 shows the results of measuring the properties of the water-absorbent resin composition (10). Example 11 Example 10 was the same as Example 10 except that the water absorbent resin (D) obtained in Reference Example 2 was used instead of the water absorbent resin (B) obtained in Reference Example 1. Thus, a water-absorbent resin composition (11) was obtained (the amount of tetrasodium diethylenetriaminepentaacetate added to the water-absorbent resin (D) was 52.5 ppm).

When the content of nitrilotriacetic acid (salt) in the water-absorbent resin composition (11) was measured, it was not more than 0.1 ppm relative to the composition and could not be measured. Table 2 shows the results of measuring the properties of the water-absorbent resin composition (11). [Example 12] A commercially available water-soluble deodorant (15% aqueous solution of leaf extract of Camellia plant) in a 200-fold diluted aqueous solution
Was prepared to be present at 16.7% and the resulting aqueous solution 3
Parts were mixed with 100 parts of the water-absorbent resin (B) obtained in Reference Example 1, and the mixture was heated at 80 ° C., and then 0.5% of silicon dioxide (Nippon Aerosil Co., Ltd., Aerosil 200) was added as an inorganic powder. Except for the above, the same operation as in the method of manufacturing the water absorbent resin composition (10) in Example 10 was performed, to obtain a water absorbent resin composition (12).

Example 13 A commercially available water-soluble deodorant (leaf extract 1 of Camellia planta) was added to a 200-fold diluted aqueous solution.
5% aqueous solution) was prepared so as to have 16.7%, and 3 parts of the obtained aqueous solution was mixed with the water-absorbent resin (D) obtained in Reference Example 2.
A water-absorbent resin composition (13) was obtained in the same manner as in the method for producing the water-absorbent resin composition (11) in Example 11, except that the mixture was stirred and mixed with 100 parts. [Example 14] A commercially available water-soluble deodorant (manufactured by Taiyo Fragrance Co., Ltd .; Oak Clean EX) was added to a 200-fold diluted aqueous solution.
6.7% of the water-absorbent resin composition in Example 10 except that 3 parts of the obtained aqueous solution was spray-mixed with 100 parts of the water-absorbent resin (B) obtained in Reference Example 1. The same operation as in the production method of 10) was performed to obtain a water-absorbent resin composition (14).

Example 15 To 100 parts of the water-absorbent resin composition (10) obtained in Example 10, 0.5% of a commercially available water-soluble deodorant (Eporion, manufactured by Aiko Co., Ltd.) was added and mixed. Thus, a water-absorbing resin composition (15) was obtained.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

The water-absorbent resin composition of the present invention contains an aminoacetic acid-based chelating agent and has a very low content of nitrilotriacetic acid (salt), so that it has excellent urine resistance and light resistance. It is excellent in color, less colored and highly safe. In the case where a water-soluble deodorant is also contained, the problem of sucking urine or the like can be solved. The water-absorbent resin composition of the present invention exhibits excellent absorption capacity under no load, elution amount of deteriorated soluble component, and absorption capacity under load.

[Brief description of the drawings]

FIG. 1 shows an apparatus for measuring an absorption capacity under load.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Balance 2 Container 2a Opening 2b Opening 3 Open air suction pipe 4 Conduit 5 Measurement part 6 Glass filter 7 Filter paper 9 Support cylinder 10 Wire net 11 Weight 12 Physiological saline 15 Water-absorbing resin (composition)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masatoshi Nakamura 1 at 992, Nishioki, Okahama-ku, Abashiri-ku, Himeji-shi, Hyogo Japan Nippon Shokubai Co., Ltd. 4J002 AB031 BB181 BF021 BG011 BG101 BG131 BN011 EC038 EJ018 EN116 ET007 FD206 FD208 GB01

Claims (5)

[Claims] 1. A water-absorbent resin composition comprising a water-absorbent resin and an aminoacetic acid-based chelating agent, wherein the compounding amount of the aminoacetic acid-based chelating agent is 10 ppm based on the water-absorbing resin.
A water-absorbent resin composition, wherein the content of nitrilotriacetic acid and its salt in the composition is 1 ppm or less with respect to the composition. 2. A water-absorbent resin composition comprising a water-absorbent resin and an aminoacetic acid-based chelating agent, wherein the content of nitrilotriacetic acid and its salt in the composition is 1000 ppm with respect to the aminoacetic acid-based chelating agent. The following water-absorbent resin composition. 3. The water-absorbent resin composition according to claim 1, further comprising a water-soluble deodorant. 4. An absorption capacity under no load of 30 g / g or more, an eluted amount of a deteriorated soluble component of 20% by weight or less, an absorption capacity under a load of 1.9 kPa of 28 g / g or more, and a coloring degree of 26 or less. 4. The water-absorbent resin composition according to any one of 1 to 3. 5. An absorbent containing a water-absorbent resin and a water-soluble deodorant, having an absorption capacity under no load of 30 g / g or more, an elution amount of deteriorated soluble components of 20 wt% or less, and an absorption capacity under a load of 1.9 kPa of 2
A water-absorbent resin composition having a odor reduction rate of at least 8 g / g and an odor reduction rate of at least 40%.