JP5188824B2 - Absorbent resin particles and method for producing the same - Google Patents

Description

  The present invention relates to absorbent resin particles, a production method thereof, an absorbent body including the same, and an absorbent article.

  Absorbent resin particles are resins that can absorb water several tens to several thousand times their own weight. For example, polyacrylic acid-based absorbent resins are known. These absorbent resins are widely used in disposable sanitary goods because of their high water absorption. However, it has been pointed out that conventional absorbent resin particles have a problem in terms of environmental load in the treatment method of sanitary products containing the resin particles, and the method of treatment in an incinerator causes global warming. . Under such circumstances, from the viewpoint of carbon neutral and the like, there is a strong demand for absorbent resin particles using plant-derived materials.

Examples of absorbent resins using plant-derived materials include crosslinked carboxymethyl cellulose (Non-patent Document 1, Patent Document 1), crosslinked alginic acid, crosslinked starch (Patent Document 2), and crosslinked polyamino acid (Patent Documents 3 to 3). 7), galactomannan-metal ion crosslinked bodies (Patent Documents 8 to 10) and the like are known.
US Pat. No. 4,650,716 JP 2004-010634 A Japanese Patent Laid-Open No. 55-15634 JP 7-224163 A JP 7-309943 A JP-A-8-59820 JP-A-8-504219 JP-A-9-169840 JP-A-8-59891 Japanese Patent Publication No. 3-66321 JP 56-97450 A

  However, when the absorbent resin using these plant-derived raw materials is compared with the polyacrylic acid-based absorbent resin, the absorbent resin using the plant-derived raw materials has lower productivity and lower absorption performance. Has not yet been put to practical use.

  An object of the present invention is to provide absorbent resin particles containing a plant-derived raw material and having excellent absorption performance, and a method for producing the same.

The feature of the method for producing absorbent resin particles of the present invention is that a monomer having (meth) acrylic acid (salt) (a1) and a crosslinking agent (a3) as essential constituent monomers (a) is copolymerized . A step (1) of obtaining a crosslinked polymer / cellulose composite gel (A / B) by mixing a hydrous gel comprising a crosslinked polymer (A) and water and a mercerized cellulose (C); or
(Meth) acrylic acid (salt) (a1) and a monomer having the cross-linking agent (a3) as essential constituent monomer (a) and mercerized cellulose (C) are mixed and then copolymerized. Step (2) of obtaining a crosslinked polymer / cellulose composite gel (A / B),
The gist of the present invention is to include a step (3) of post-treating the crosslinked polymer / cellulose composite gel (A / B) to obtain absorbent resin particles.

The feature of the absorbent resin particles of the present invention is the absorbent resin particles obtained by the above production method,
The gist is that it contains a crosslinked polymer (A) comprising (meth) acrylic acid (salt) (a1) and a crosslinking agent (a3) as essential constituent monomers (a) and cellulose (B).

The absorbent resin particles of the present invention exhibit high absorption performance despite using plant-derived materials (cellulose).
Moreover, according to the manufacturing method of the absorbent resin particle of this invention, although the plant-derived raw material (cellulose) is used, the absorbent resin particle which exhibits high absorption performance can be manufactured easily.
Moreover, since the absorber of this invention uses said absorbent resin particle, it exhibits high absorption performance.
Moreover, since the absorbent article of this invention uses said absorber, it exhibits high absorption performance.

<Step (1)>
The water-soluble vinyl monomer (a1) is not particularly limited, and known {e.g., vinyl monomers disclosed in Japanese Patent No. 3648553, Japanese Patent Laid-Open No. 2003-165883, Japanese Patent Laid-Open No. 2005-75982, Japanese Patent Laid-Open No. 2005-95759} can be used. .

  The hydrolyzable vinyl monomer (a2) means a vinyl monomer that becomes a water-soluble vinyl monomer (a1) by hydrolysis, and is not particularly limited (for example, Japanese Patent No. 3648553, Japanese Patent Application Laid-Open No. 2003-16583, Japanese Patent Application Laid-Open No. 2003-16583). 2005-75982, JP-A-2005-95759} vinyl monomers, and the like can be used. The hydrolysis of the hydrolyzable vinyl monomer may be performed either during polymerization, after polymerization, or both of them, but is preferably after polymerization from the viewpoint of the absorption performance of the resulting absorbent resin particles.

  Among these, from the viewpoint of absorption performance and the like, the water-soluble vinyl monomer (a1) is preferable, more preferably an anionic vinyl monomer, next preferably a vinyl monomer having a carboxy (salt) group or a sulfo (salt) group, Next, a vinyl monomer having a carboxy (salt) group is preferred, (meth) acrylic acid (salt) is particularly preferred, and acrylic acid (salt) is most preferred.

The “carboxy (salt) group” means “carboxy group” or “carboxylate group”, and the “sulfo (salt) group” means “sulfo group” or “sulfonate group”. Moreover, (meth) acrylic acid (salt) means acrylic acid, acrylate, methacrylic acid or methacrylate, and (meth) acrylamide means acrylamide or methacrylamide. Examples of the salt include an alkali metal (such as lithium, sodium and potassium) salt, an alkaline earth metal (such as magnesium and calcium) salt or an ammonium (NH ₄ ) salt. Among these salts, alkali metal salts and ammonium salts are preferable from the viewpoint of absorption performance and the like, more preferably alkali metal salts, and particularly preferably sodium salts.

  When either the water-soluble vinyl monomer (a1) or the hydrolyzable vinyl monomer (a2) is used as a structural unit, each may be used alone as a structural unit, or two or more kinds may be used as a structural unit if necessary. The same applies when the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as constituent units. Further, when the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as structural units, the content molar ratio (a1 / a2) is preferably 75/25 to 99/1, more preferably. 85/15 to 95/5, particularly preferably 90/10 to 93/7, and most preferably 91/9 to 92/8. Within this range, the absorption performance is further improved.

The cross-linking agent (a3) is not particularly limited, and known {eg, cross-linking agents disclosed in Japanese Patent No. 3648553, JP-A No. 2003-165883, JP-A No. 2005-75982, JP-A No. 2005-95759} can be used.
Among these, from the viewpoint of absorption performance and the like, a crosslinking agent having two or more ethylenically unsaturated groups is preferable, more preferably a poly (meth) allyl ether of a polyol having 2 to 10 carbon atoms, particularly preferably triallyl shea. Nurate, triallyl isocyanurate, tetraallyloxyethane and pentaerythritol triallyl ether, most preferably pentaerythritol triallyl ether.

  The use amount (mol%) of the crosslinking agent (a3) is preferably 0.001 to 5, more preferably 0.00, based on the number of moles of the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2). 005 to 3, particularly preferably 0.01 to 1. Within this range, the absorption performance is further improved.

  In addition to these monomers, the water-soluble vinyl monomer (a) and / or the hydrolyzable vinyl monomer (a2) and the crosslinking agent (a3) as essential constituent monomers (a) are copolymerized with them. Possible other vinyl monomers (a4) can be included.

  Other vinyl monomers (a4) that can be copolymerized are not particularly limited and are known {eg, hydrophobicity of Japanese Patent No. 3648553, Japanese Patent Laid-Open No. 2003-165883, Japanese Patent Laid-Open No. 2005-75982, Japanese Patent Laid-Open No. 2005-95759}. Vinyl monomers can be used.

  When the other vinyl monomer (a4) is included, the usage amount (mol%) of the other vinyl monomer (a4) is based on the number of moles of the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2). 0.01-5 is preferable, More preferably, it is 0.05-3, Next, Preferably it is 0.08-2, Most preferably, it is 0.1-1.5. In view of absorption performance and the like, it is most preferable not to use any other vinyl monomer (a4).

  As a method for copolymerizing a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a monomer having a crosslinking agent (a3) as an essential constituent monomer (a), a known aqueous solution is used. Polymerization {adiabatic polymerization, thin film polymerization, spray polymerization, etc .; JP-A-55-133413, etc.} and known reverse phase suspension polymerization (JP-B-54-30710, JP-A-56-26909, and JP-A-1) −5808 etc.}.

  Water-containing gel obtained by polymerization {consists of a crosslinked polymer and water. } Can be shredded as necessary. When chopping, the size (longest diameter) of the gel after chopping is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm.

  Shredding can be performed by a known method, and can be shredded using a normal shredding device {for example, a bex mill, rubber chopper, pharma mill, mincing machine, impact crusher and roll crusher}. .

  The crosslinked polymer (A) may be one type or a mixture of two or more types.

  Mercerized cellulose (C) means a product obtained by mercerizing cellulose (B). Mercerization means that cellulose (B) is treated with a mercerizing agent (alkali). That is, the mercerized cellulose (C) means a product obtained by treating cellulose (B) with a mercerizing agent (alkali). In addition, mercerization is performed using an excess mercerizing agent (alkali), and when there is an excess of alkali, the mercerizing agent (alkali) is included in the mercerized cellulose (however, a solvent such as water is not included) .)

  The cellulose (B) is not particularly limited, and may be a cellulose having a hydroxyl group that is unsubstituted or a cellulose having a substituted hydroxyl group, but from the viewpoint of absorption performance, unsubstituted cellulose is preferred.

  Unsubstituted cellulose includes natural polysaccharides (for example, cotton, wood-derived pulp, bacterial cellulose, lignocellulose, microbial-produced polysaccharides, chitin and chitosan, etc.), regenerated cellulose (for example, cellophane and regenerated fibers), and microcrystals. A cellulose etc. are mentioned. Among these unsubstituted celluloses, natural polysaccharides and microcrystalline cellulose are preferable, natural polysaccharides are more preferable, and wood-derived pulp is particularly preferable.

  Examples of the substituted cellulose include cellulose ethers (for example, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose), cellulose esters (for example, cellulose acetate, cellulose lactate, cellulose butyrate, cellulose acetobutyrate, and cellulose capronate). Etc.) and cellulose ether esters (for example, hydroxypropylcellulose lactate and hydroxyethylcellulose butyrate) and the like.

  1 type may be sufficient as the kind of substituent of substituted cellulose, and 2 or more types may be sufficient as it. Among these substituted celluloses, cellulose ether is preferable from the viewpoint of hydrolyzability of the substituent group, and carboxymethyl cellulose is more preferable.

  The degree of substitution of the substituted cellulose is preferably from 0.01 to 2, more preferably from 0.02 to 1, particularly preferably from 0.03 to 0.5, from the viewpoint of absorption performance and the like.

The degree of substitution of the substituted cellulose is a reactive agent (an etherifying agent and / or an esterifying agent) that forms a substituent among the three hydroxyl groups of the glucose ring (not including the hydroxyl groups at the 1-position and 4-position of the glucose ring). ) Means the number (average value) of hydroxyl groups modified by the reaction.
The degree of substitution is based on the 7.3 pyridine-acetyl chloride method of JIS K0070: 1992 “Testing method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products”. The front and back hydroxyl values are measured and determined from the following formula.

(Degree of substitution) = 3- (hydroxyl value after methylation / hydroxyl value before methylation) × 3

  These celluloses (unsubstituted cellulose and substituted cellulose) may be crosslinked. Crosslinking of cellulose (B) can be carried out by any known method, and may be cross-linked using a cross-linking agent, and may be cross-linked by radiation (for example, gamma ray, X-ray or electron beam radiation) and / or heat. You may let them. When using a cross-linking agent, the cross-linking agent includes N-methylol compounds having a cyclic portion in the molecule (such as dimethylol ethylene urea and dimethylol dihydroxy ethylene urea), polycarboxylic acids (tricarbaryl acid citrate and butanetetra). Carboxylic acids, etc.), epoxy compounds (ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerol diglycidyl ether, etc.), polyvalent metal ions (aluminum ions, chromium ions, etc.), polyfunctional amines (amino acids, polyamines, triamines) And diamine etc.). These crosslinking agents may be used alone or in combination of two or more.

  Examples of mercerizing agents (alkalis) include alkali amines and alkaline earth metal hydroxides or carbonates, organic amines, ammonia and quaternary ammonium salts. Of these, alkali metal hydroxides and quaternary ammonium salts are preferred, more preferably sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, benzyltrimethylammonium hydroxide (BTMOH), particularly preferably. Alkali metal hydroxides, most preferably sodium hydroxide. The mercerizing agent is preferably used as an aqueous solution.

  Mercerization is carried out by a known method {eg, “Pulping Processes” edited by Rydholm (Interscience Publishers, 1965) and “Cellulose and Cellulose Derivatives” edited by Ott, Spurlin and Grafflin. V, Part 1 (Interscience Publishers, 1954)}.

  Mercerization may be performed by immersing cellulose (B) in a mercerizing agent aqueous solution (alkaline aqueous solution) or by spraying a mercerizing agent aqueous solution (alkaline aqueous solution) on cellulose (B). It is preferable that the cellulose (B) is mixed and sprayed with a mercerizing agent aqueous solution (alkaline aqueous solution) while stirring.

  In mercerization, the amount of cellulose (B) used (% by weight) is preferably 11 to 35, more preferably 12 to 27, particularly preferably based on the weight of cellulose (B) and mercerizing agent (alkali). 14-24.

  The use amount (% by weight) of the mercerizing agent is preferably 65 to 89, more preferably 73 to 88, and particularly preferably 76 to 86, based on the weight of the cellulose (B) and the mercerizing agent (alkali). .

  The mixing temperature (° C.) of the mercerizing agent and cellulose (B) is preferably 0 to 50, more preferably 10 to 40, and particularly preferably 20 to 30.

  The mixing time of the mercerizing agent and cellulose (B) is preferably 10 minutes to 24 hours, more preferably 15 minutes to 12 hours, and particularly preferably 20 minutes to 90 minutes.

  As a mixing device for mercerization, known devices {double-arm kneader, internal mixer (Banbury mixer), self-cleaning mixer, gear compounder, screw-type extruder, screw-type kneader, minced machine, Turbu Riser, cylindrical mixer, V-shaped mixer, ribbon-type mixer, screw-type mixer, double-arm mixer, pulverizing kneader, groove-type mixer, vertical mixer, etc. can be used. These can be used in combination.

  Mercerization may be performed in air, but it is preferably performed in an atmosphere of an inert gas (such as nitrogen).

  After mercerization, a mercerizing agent aqueous solution (alkaline aqueous solution) may be separated from the mixture of mercerized cellulose by filtration, centrifugation, or the like. The mercerized cellulose may then be washed and / or neutralized to remove excess mercerizing agent.

  Cleaning agents used for cleaning include water, weak acids (acids having a pH of about 4.0 to about 6.9), solutions having weak mercerizing agents (having a pH of about 7.1 to about 10.0). Alkali) and mixtures thereof.

  Neutralizing agents used for neutralization include sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, oxalic acid, sulfur dioxide, (meth) acrylic acid, poly (meth) acrylic acid, crosslinked poly (meth) acrylic acid, ammonium sulfate , Ammonium chloride, ammonium nitrate, magnesium chloride, magnesium nitrate, zinc chloride, zinc nitrate, and mixtures thereof. Of these, (meth) acrylic acid, poly (meth) acrylic acid and a crosslinked poly (meth) acrylic acid are preferable, and a crosslinked poly (meth) acrylic acid is more preferable. In addition, the poly (meth) acrylic acid and the poly (meth) acrylic acid crosslinked body may be partially neutralized.

  When neutralizing mercerized cellulose, neutralized salts (such as sodium chloride) and excess neutralizing agents may be washed away after neutralization.

Mercerized cellulose may be dried to form a sheet, bale, powder, or the like.
Mercerized cellulose (C) may be used in any form of a dried product or a dispersion, but is preferably used in a dispersion from the viewpoint of easy mixing. When used in a dispersion, water is preferred as the solvent. The dispersion concentration (% by weight) is preferably 22 to 43, more preferably 24 to 36.

  Mercerized cellulose may be further crosslinked. Crosslinking is the same as that of cellulose (B).

  As a method of mixing the crosslinked polymer (A) and the mercerized cellulose (C), (1) a method of mixing the hydrogel containing the crosslinked polymer (A) and water and the mercerized cellulose (C); (2) A method of mixing the crosslinked polymer (A) (dry particles) and mercerized cellulose (C) is included. Among these, the method (1) is preferable from the viewpoint of absorption performance and the like.

  The used amount (% by weight) of mercerized cellulose (C) (amount not containing a solvent such as water) is 30 to 69 based on the weight of essential constituent monomer (a) and mercerized cellulose (C). More preferably, it is 38-62, Most preferably, it is 42-48. Within this range, the absorption performance is further improved.

  In addition, when mercerization is performed using an excess mercerizing agent (alkali) and an excess alkali exists, the amount of mercerized cellulose (C) used means an amount containing the mercerizing agent (alkali) ( However, it does not include solvents such as water.)

  The use amount (% by weight) of the essential constituent monomer (a) is preferably 31 to 70, more preferably 38 to 62, based on the weight of the essential constituent monomer (a) and mercerized cellulose (C). Especially preferably, it is 52-58. Within this range, the absorption performance is further improved.

  The mixing temperature (° C.) of the crosslinked polymer (A) and mercerized cellulose (C) is preferably from 30 to 150, more preferably from 40 to 120, particularly preferably from 50 to 100. Within this range, it becomes easier to mix evenly, and the absorption performance is further improved.

  As a mixing device of the cross-linked polymer (A) and mercerized cellulose (C), known devices {double-arm kneader, internal mixer (Banbury mixer), self-cleaning mixer, gear compounder, screw type extruder , Screw type kneader, mincing machine, turbulizer, cylindrical mixer, V-shaped mixer, ribbon type mixer, screw type mixer, double-arm type mixer, pulverizing type kneader, groove type mixer, saddle type Can be used. These can be used in combination.

  When an anionic vinyl monomer is included as the water-soluble vinyl monomer (a1), a crosslinked polymer / cellulose composite gel (A / B) is formed by mixing the crosslinked polymer (A) and mercerized cellulose (C). . That is, the alkali in the mercerized cellulose (C) and the anionic substituent {carboxy group, sulfo group, etc.) derived from the anionic vinyl monomer are neutralized by a neutralization reaction, and the crosslinked polymer (A) The anionic substituent forms a salt while mercerized cellulose (C) becomes cellulose (B). In this case, either complete neutralization or partial neutralization may be used, but partial neutralization may occur due to the relationship between the amount of the essential constituent monomer (a) and mercerized cellulose (C) used. preferable.

<Step (2)>
Mixing of a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2), a monomer having a crosslinking agent (a3) as an essential constituent monomer (a), and mercerized cellulose (C) The method is not limited as long as it can be uniformly mixed, and can be carried out by a known method.

  As a mixing device of monomer and mercerized cellulose (C), known devices {double-arm kneader, internal mixer (Banbury mixer), self-cleaning mixer, gear compounder, screw type extruder, screw type Kneaders, minced machines, turbulizers, cylindrical mixers, V-shaped mixers, ribbon-type mixers, screw-type mixers, double-armed mixers, grinding-type kneaders, groove-type mixers, vertical mixers, etc. } Etc. can be used. A plurality of these may be combined.

  When exothermicity is accompanied with the neutralization reaction during mixing, the monomer, mercerized cellulose (C) and / or a mixture thereof may be cooled as necessary. As cooling temperature (degreeC), 0-30 are preferable, More preferably, it is 0-10.

  The used amount (% by weight) of mercerized cellulose (C) (amount not containing a solvent such as water) is 30 to 69 based on the weight of essential constituent monomer (a) and mercerized cellulose (C). More preferably, it is 38-69, Most preferably, it is 42-48. Within this range, the absorption performance is further improved.

  The use amount (% by weight) of the essential constituent monomer (a) is preferably 31 to 70, more preferably 38 to 62, based on the weight of the essential constituent monomer (a) and mercerized cellulose (C). Especially preferably, it is 52-58. Within this range, the absorption performance is further improved.

  As a method for copolymerizing a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a monomer having a crosslinking agent (a3) as an essential constituent monomer (a), a known aqueous solution is used. Polymerization {adiabatic polymerization, thin film polymerization, spray polymerization, etc .; JP-A-55-133413, etc.} and known reverse phase suspension polymerization (JP-B-54-30710, JP-A-56-26909, and JP-A-1) −5808 etc.}.

  When an anionic vinyl monomer is included as the water-soluble vinyl monomer (a1), a cross-linked polymer / cellulose composite gel (A / B) is generated by this copolymerization. That is, the alkali in the mercerized cellulose (C) and the anionic substituents {carboxy group, sulfo group, etc.) derived from the anionic vinyl monomer are neutralized by a neutralization reaction, and the crosslinking weight obtained by copolymerization is obtained. The anionic substituent in the union (A) forms a salt, while the mercerized cellulose (C) becomes cellulose (B). In this case, either complete neutralization or partial neutralization may be used, but partial neutralization may occur due to the relationship between the amount of the essential constituent monomer (a) and mercerized cellulose (C) used. preferable.

<Step (3)>
The crosslinked polymer / cellulose composite gel (A / B) obtained in the step (1) or (2) can lead to absorbent resin particles by post-treatment.
Post-processing includes shredding, solvent evaporation (drying), pulverization, particle size adjustment, surface crosslinking, and mixing of additives. These post-processing may be performed in combination, or only one of them may be performed. Moreover, there is no restriction | limiting in the order of post-processing, Although it determines suitably, said order is preferable. Of these post-treatments, it is preferable to include drying. Moreover, when employ | adopting aqueous solution polymerization, it is preferable that a grinding | pulverization is included further.

<Shred>
Shredding can be performed by a known method, and can be shredded using a known shredding device {for example, a bex mill, rubber chopper, pharma mill, mincing machine, impact crusher and roll crusher}. .

  When shredding, the size (longest diameter) of the composite gel (A / B) after shredding is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, in addition to being easier to handle, when the solvent is subsequently distilled off, the solvent is further easily distilled off, and when pulverizing thereafter, the pulverization is further facilitated.

<Solvent evaporation (drying)>
In the copolymerization in the step (1) or (2), when a solvent (such as an organic solvent and water) is used, the solvent is preferably distilled off.
When the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably 10 to 0.01, more preferably 5 to 0.05, based on the weight of the absorbent resin particles. Particularly preferred is 3 to 0.1, and most preferred is 1 to 0.5. Within this range, the absorption performance is further improved.

  When water is contained in the solvent, the water content (% by weight) after distillation is preferably 0 to 20, more preferably 0 to 10, particularly preferably 0 to 7, most preferably based on the weight of the absorbent resin particles. Is 0-3. Within this range, the absorption performance and handling properties after drying (powder fluidity of the absorbent resin particles, etc.) are further improved.

  In addition, the content and moisture of the organic solvent are an infrared moisture measuring device {JE400 manufactured by Kett Science Laboratory Co., Ltd .: 120 ± 5 ° C., 30 minutes, atmospheric humidity before heating 50 ± 10% RH, lamp specification 100V, It is calculated | required from the weight loss of the measurement sample before and behind heating when heated by 40W}.

As a method of distilling off the solvent (including water), a method of distilling (drying) with hot air at a temperature of 80 to 230 ° C., a thin film drying method using a drum dryer heated to 100 to 230 ° C., (heating ) Vacuum drying, freeze drying, infrared drying, etc. can be applied.
Prior to distilling off the solvent, the solvent can be removed by decantation, filtration or the like.

<Crushing>
The pulverization is preferably performed after the solvent is distilled off.
The pulverization method is not particularly limited, and can be pulverized by a known pulverizer (for example, a hammer-type pulverizer, an impact-type pulverizer, a roll-type pulverizer, and a shet airflow-type pulverizer).

<Granularity control>
The size of the pulverized particles is adjusted by sieving or the like as necessary.
The weight average particle diameter (μm) of the pulverized particles is preferably 100 to 800, more preferably 200 to 500, and particularly preferably 300 to 400. Within this range, the absorption performance is further improved. Therefore, it is preferable to adjust the particle size so as to be in this range.

  In addition, the weight average particle size is obtained by measuring the particle size distribution of the measurement sample, and the logarithmic probability paper {horizontal axis: particle size, vertical axis: cumulative content (% by weight)} has a relationship between the cumulative content and the particle size. It is obtained by plotting and determining the particle size corresponding to a cumulative content of 50% by weight. The particle size distribution is measured in accordance with JIS Z8815-1994. For example, sieves with an inner diameter of 150 mm and a depth of 45 mm {openings: 710 μm, 500 μm, 300 μm, 150 μm and 106 μm} are used with a narrow opening sieve. Overlay, put 50 g of measurement sample on top of 710 μm sieve with widest opening, sieve for 10 minutes with sieve shaker, measure weight of measurement sample remaining on each sieve, It is measured by determining the weight percent of the measurement sample remaining on each sieve based on the weight of the measurement sample.

The smaller the content of fine particles, the better the absorption performance. Therefore, it is preferable to remove the fine particles by sieving or the like.
The content of fine particles of 106 μm or less (preferably 150 μm or less) in all particles is preferably 3% by weight or less, and more preferably 1% by weight or less.
The content of the fine particles can be determined using a plot created when determining the weight average particle diameter.

<Surface cross-linking>
The cut chopped gel or the pulverized particles can be subjected to surface cross-linking treatment with a surface cross-linking agent, if necessary.
As the surface crosslinking agent, known {for example, JP 59-189103, JP 58-180233, JP 61-16903, JP 61-2111305, JP 61-252212, Surface cross-linking agents {polyvalent glycidyl, polyhydric alcohol, polyvalent amine, polyvalent aziridine, polyvalent isocyanate, silane coupling agent and polyvalent metal of JP-A-51-136588 and JP-A-61-257235} Etc.} can be used. Of these surface cross-linking agents, from the viewpoint of economy and absorption performance, polyvalent glycidyl, polyhydric alcohol and polyvalent amine are preferable, more preferably polyvalent glycidyl and polyhydric alcohol, particularly preferably polyvalent glycidyl, Preferred is ethylene glycol diglycidyl ether.

  In the case of surface cross-linking, the amount (% by weight) of the surface cross-linking agent is not particularly limited because it can be changed variously depending on the type of surface cross-linking agent, cross-linking conditions, target performance, etc. From a viewpoint etc., based on the weight of an essential constituent monomer (a), 0.001-3 are preferable, More preferably, it is 0.005-2, Most preferably, it is 0.01-1.

  In the case of surface crosslinking, a known method {for example, Japanese Patent No. 3648553, Japanese Patent Laid-Open No. 2003-165883, Japanese Patent Laid-Open No. 2005-75982, Japanese Patent Laid-Open No. 2005-95759} can be applied.

<Mixing of additives>
For shredded gels, dry particles, pulverized particles or surface cross-linked particles, other additives (for example, known preservatives, fungicides, antibacterial agents (for example, JP-A No. 2003-225565 and JP-A No. 2006-131767)) Agent, antioxidant, ultraviolet absorber, colorant, fragrance, deodorant, inorganic powder, organic fibrous material, etc.}.
When other additives are mixed, the mixing method is not limited as long as uniform mixing is possible, and a known mixing method can be applied.

  The absorbent resin particle of the present invention comprises a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2), and a crosslinked polymer (A) having a crosslinking agent (a3) as an essential constituent monomer (a). ) And cellulose (B), for example, when copolymerized with a monomer containing the essential constituent monomer (a) in the presence of cellulose (B), cellulose (B) It is preferable that the graft ratio with the essential constituent monomer (a) is low. The graft ratio (% by weight) is preferably 70 or less, more preferably 50 or less, particularly preferably 30 or less, then preferably 15 or less, then preferably 5 or less, and most preferably 0.

The graft ratio is measured as follows.
After sieving with a sieve having an opening of 1 mm and adjusting to a size of 1 mm or less, drying is performed at 100 ° C. for 1 hour, and sieving with a sieve having an opening of 150 and 300 μm to prepare a measurement sample of 150 to 300 μm. Disperse 1.00 g (G1) of the measurement sample in 200 g of the solvent stirred at 50 ° C. and 500 rpm, maintain for 24 hours, filter, wash 3 times with 100 g of solvent, and further wash 3 times with 100 g of methanol. Then, after drying at 100 ° C. for 1 hour, the dry weight (G2) is measured, and the graft ratio is obtained from the following formula. In addition, (Z) is content (%) of a cellulose (B) based on the weight of a crosslinked polymer (A) and a cellulose (B).

  However, as the solvent, a solvent capable of dissolving cellulose (B) is used. For example, in the case of unsubstituted cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose ester, and cellulose ether ester, 1-ethyl-3-methylimidazolium chloride is used. In the case of ethyl cellulose, ethanol is used. In the case of carboxymethyl cellulose, a water / methanol mixed solvent (weight ratio 50/50) is used.

The absorbent resin particles of the present invention are produced by the above production method or the following method.
(1) A method of mixing a crosslinked polymer (A), a water-containing gel composed of water, and cellulose (B); (2) mixing a crosslinked polymer (A) (dry particles) and cellulose (B). Methods etc. are included.
Among these production methods, from the viewpoint of absorption performance and the like, the production method and the method (1) are preferable, more preferably the production method, and particularly preferably the step (1) of the production method. Is the method.

  The content (% by weight) of the crosslinked polymer (A) is preferably 40 to 95, more preferably 50 to 85, and particularly preferably 60 to 85, based on the weight of the crosslinked polymer (A) and cellulose (B). 70. Within this range, the absorption performance is further improved.

  The content (% by weight) of cellulose (B) is preferably 5 to 60, more preferably 15 to 50, and particularly preferably 30 to 40, based on the weight of the crosslinked polymer (A) and cellulose (B). is there. Within this range, the absorption performance is further improved.

  The absorbent resin particles of the present invention are represented by formulas (1), (2) and (3); formulas (4), (5) and (6); formulas (7), (8) and (9); It is preferable to satisfy any of (10), (11), and (12), and more preferably, the formulas (13), (14), and (15); the formulas (16), (17), and (18); (19), (20) and (21); or satisfying any of the formulas (22), (23) and (24).

33 ≦ (X) ≦ 40 (1)
20 ≦ (Y) ≦ 28 (2)
5 ≦ (Z) ≦ 15 (3)

30 ≦ (X) ≦ 37 (4)
15 ≦ (Y) ≦ 23 (5)
15 <(Z) ≦ 30 (6)

25 ≦ (X) ≦ 33 (7)
10 ≦ (Y) ≦ 20 (8)
30 <(Z) ≦ 50 (9)

21 ≦ (X) ≦ 28 (10)
7 ≦ (Y) ≦ 13 (11)
50 <(Z) ≦ 60 (12)

36 ≦ (X) ≦ 38 (13)
22 ≦ (Y) ≦ 26 (14)
5 ≦ (Z) ≦ 15 (15)

32 ≦ (X) ≦ 35 (16)
17 ≦ (Y) ≦ 21 (17)
15 <(Z) ≦ 30 (18)

27 ≦ (X) ≦ 31 (19)
12 ≦ (Y) ≦ 18 (20)
30 <(Z) ≦ 50 (21)

23 ≦ (X) ≦ 26 (22)
9 ≦ (Y) ≦ 11 (23)
50 <(Z) ≦ 60 (24)

  However, (X) is the water retention amount (g / g) of the absorbent resin particles after being immersed in physiological saline for 1 hour, and (Y) is the absorbency after being immersed in physiological saline under a load of 6.2 kPa for 1 hour. The absorption amount (g / g) and (Z) of the resin particles are the content (%) of cellulose (B) based on the weight of the crosslinked polymer (A) and cellulose (B).

The water retention amount (X) is measured as follows.
<Measurement method of water retention>
1.00 g of a measurement sample is put into a tea bag (20 cm long, 10 cm wide) made of a nylon net having a mesh size of 63 μm (JIS Z8801-1: 2006), and 1,000 ml of physiological saline (saline concentration 0.9% by weight). After soaking for 1 hour without stirring, hang for 15 minutes and drain. Thereafter, each tea bag is placed in a centrifuge, centrifuged at 150 G for 90 seconds to remove excess physiological saline, and the weight (h1) including the tea bag is measured to obtain the water retention amount from the following equation. In addition, the temperature of the physiological saline used and measurement atmosphere is 25 degreeC +/- 2 degreeC.

Water retention amount (g / g) = (h1)-(h2)

  (H2) is the weight of the tea bag measured by the same operation as described above when there is no measurement sample.

In addition, the absorption amount (absorption amount under load) (Y) of the absorbent resin particles after being immersed in physiological saline under a load of 6.2 kPa for 1 hour is measured as follows.
<Absorption under load>
0.16 g of a measurement sample sieved to a particle diameter of 250 to 500 μm in a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) having a nylon mesh of 63 μm (JIS Z8801-1: 2006) pasted on the bottom. Were weighed and the cylindrical plastic tube was placed vertically so that the measurement sample had a substantially uniform thickness on the nylon mesh, and then a weight (weight: 310.6 g, outer diameter: 24. 5mm,). After measuring the weight (M1) of the entire cylindrical plastic tube, a cylindrical type containing a measurement sample and a weight in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration: 0.9% by weight). Stand the plastic tube vertically and immerse it with the nylon mesh side down, and let stand for 60 minutes. After 60 minutes, pull up the cylindrical plastic tube from the petri dish, tilt it diagonally, remove the dripping water drops, weigh the entire cylindrical plastic tube containing the measurement sample and weight (M2), and Obtain the amount absorbed under load. In addition, the temperature of the physiological saline used and measurement atmosphere is 25 degreeC +/- 2 degreeC.

Absorption under load (g / g) = {(M2)-(M1)} / 0.16

  The absorbent resin particles of the present invention may contain other additives (for example, known preservatives, fungicides, antibacterial agents, antioxidants, ultraviolet rays (for example, JP 2003-225565 A, JP 2006-131767 A). Absorbers, colorants, fragrances, deodorants, inorganic powders, organic fibrous materials, etc.}.

  100-800 are preferable, as for the weight average particle diameter (micrometer) of the absorptive resin particle | grains of this invention, More preferably, it is 200-500, Most preferably, it is 300-400. Within this range, the absorption performance is further improved.

  The smaller the content of fine particles, the better the absorption performance. Therefore, the content of fine particles of 106 μm or less (preferably 150 μm or less) in all particles is preferably 3% by weight or less, more preferably 1% by weight or less. .

  The shape of the absorbent resin particle of the present invention is not particularly limited, and examples thereof include an irregular crushed shape, a flake shape, a pearl shape, and a rice grain shape. Among these, when applied to a paper diaper or the like, from the viewpoint of good entanglement with the fibrous material, no fear of dropping off from the fibrous material, and from the viewpoint of absorption performance, an irregularly crushed shape and a pearl shape are preferable.

  The absorbent resin particles of the present invention can be used as an absorbent body together with a fibrous material. The structure and production method of the absorber are the same as those known in the art (Japanese Patent Laid-Open No. 2003-225565, Japanese Patent Laid-Open No. 2006-131767, Japanese Patent Laid-Open No. 2005-097569, etc.). Moreover, it is preferable that this absorber comprises absorbent articles {paper diapers, sanitary napkins, etc.}.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Unless otherwise specified, “part” means “part by weight” and “%” means “% by weight”. In addition, water retention amount (X) and absorption amount under load (Y) were measured by the method mentioned above.

<Production Example 1>
Water-soluble vinyl monomer (a1-1) {acrylic acid, manufactured by Mitsubishi Chemical Corporation, purity 100%} 108.5 parts (1.51 mol parts), cross-linking agent (a3-1) {pentaerythritol triallyl ether, diiso -Made by Co., Ltd.} 0.35 parts (0.0014 mol parts) and 389.9 parts deionized water were kept at 3 ° C. with stirring and mixing. Nitrogen was introduced into the mixture to bring the dissolved oxygen amount to 1 ppm or less, and then 0.43 part of 1% aqueous hydrogen peroxide solution and 0.81 part of 2% ascorbic acid aqueous solution were added and mixed to initiate polymerization. . After the temperature of the mixture reached 60 ° C., polymerization was performed at 60 ± 2 ° C. for about 8 hours to obtain a crosslinked polymer hydrogel (A1).

<Production Example 2>
Water-soluble vinyl monomer (a1-1) {acrylic acid, manufactured by Mitsubishi Chemical Corporation, purity 100%} 77.45 parts (1.08 mol part), cross-linking agent (b1) {pentaerythritol triallyl ether, dia-stock 0.25 parts (0.0010 mol part) made by company and 421.3 parts deionized water were kept at 3 ° C. with stirring and mixing. Nitrogen was introduced into the mixture to reduce the dissolved oxygen amount to 1 ppm or less, and then 0.31 part of 1% aqueous hydrogen peroxide solution and 0.58 part of 2% ascorbic acid aqueous solution were added and mixed to initiate polymerization. . After the temperature of the mixture reached 40 ° C., polymerization was performed at 40 ± 2 ° C. for about 8 hours to obtain a crosslinked polymer hydrated gel (A2).

<Production Example 3>
Water-soluble vinyl monomer (a1-1) {acrylic acid, manufactured by Mitsubishi Chemical Corporation, purity 100%} 62.00 parts (0.86 mol parts), cross-linking agent (b1) {pentaerythritol triallyl ether, dia-stock 0.20 part (0.0008 mole part) made by company and 437.0 parts deionized water were kept at 3 ° C. with stirring and mixing. Nitrogen was introduced into the mixture to bring the dissolved oxygen amount to 1 ppm or less, and then 0.25 part of a 1% aqueous hydrogen peroxide solution and 0.47 part of a 2% aqueous ascorbic acid solution were added and mixed to initiate polymerization. . After the temperature of the mixture reached 35 ° C., polymerization was performed at 35 ± 2 ° C. for about 8 hours to obtain a crosslinked polymer hydrated gel (A3).

<Production Example 4>
Water-soluble vinyl monomer (a1-1) {acrylic acid, manufactured by Mitsubishi Chemical Corporation, purity 100%} 131.5 parts (1.83 mol parts), crosslinking agent (b1) {pentaerythritol triallyl ether, dia-stock Company made} 0.43 parts (0.0017 mole part) and 366.5 parts deionized water were kept at 3 ° C. with stirring and mixing. Nitrogen was introduced into the mixture to bring the dissolved oxygen amount to 1 ppm or less, and then 0.53 parts of 1% aqueous hydrogen peroxide solution and 0.99 parts of 2% aqueous ascorbic acid solution were added and mixed to initiate polymerization. . After the temperature of the mixture reached 70 ° C., polymerization was performed at 70 ± 2 ° C. for about 8 hours to obtain a crosslinked polymer hydrogel (A4).

<Production Example 5>
While stirring 289.4 parts of 12% aqueous sodium hydroxide solution, 45.35 parts of cellulose (B1) {KC Flock W-400G, manufactured by Nippon Paper Chemicals Co., Ltd.} is added and mixed uniformly at 25 ° C. for 90 minutes. Thus, an aqueous dispersion (C1-1) of mercerized cellulose (C1) was obtained.

<Production Example 6>
While stirring 206.6 parts of 12% sodium hydroxide aqueous solution, 75.63 parts of cellulose (B2) {Theolas TG-101, manufactured by Asahi Kasei Chemicals Co., Ltd.} is added thereto and mixed uniformly at 30 ° C. for 20 minutes. An aqueous dispersion (C2-1) of mercerized cellulose (C2) was obtained.

<Production Example 7>
While stirring 165.4 parts of 12% sodium hydroxide aqueous solution, 90.74 parts of cellulose (B3) {KC Flock W-100GK, manufactured by Nippon Paper Chemicals Co., Ltd.} are added and uniformly mixed at 20 ° C. for 90 minutes. Then, an aqueous dispersion (C3-1) of mercerized cellulose (C3) was obtained.

<Production Example 8>
While stirring 168.6 parts of 25% aqueous sodium hydroxide solution, 22.70 parts of cellulose (B4) {Theolas TG-F20, manufactured by Asahi Kasei Chemicals Co., Ltd.} is added thereto, and mixed uniformly at 25 ° C for 90 minutes. An aqueous dispersion (C4-1) of mercerized cellulose (C4) was obtained.

<Production Example 9>
While stirring 144.7 parts of 12% sodium hydroxide aqueous solution, 45.35 parts of cellulose (B5) {KC Flock W-200G, manufactured by Nippon Paper Chemicals Co., Ltd.} is added thereto, and uniformly mixed at 25 ° C. for 90 minutes. Thus, an aqueous dispersion (C5-1) of mercerized cellulose (C5) was obtained.

<Production Example 10>
While stirring 182.9 parts of 12% aqueous sodium hydroxide solution, 22.70 parts of cellulose (B6) {KC Flock W-300G, manufactured by Nippon Paper Chemicals Co., Ltd.} is added and mixed uniformly at 25 ° C. for 90 minutes. Thus, an aqueous dispersion (C6-1) of mercerized cellulose (C6) was obtained.

<Production Example 11>
While stirring 86.93 parts of 48.5% sodium hydroxide aqueous solution, 6.80 parts of cellulose (B7) {NP fiber W-10MG2, manufactured by Nippon Paper Chemicals Co., Ltd.} was added thereto, and the mixture was stirred at 25 ° C. for 10 minutes. By mixing uniformly, an aqueous dispersion (C7-1) of mercerized cellulose (C7) was obtained.

<Production Example 12>
The amount of 12% sodium hydroxide aqueous solution was changed from “289.4 parts” to “351.3 parts”, and the amount of cellulose (B1) was changed from “45.35 parts” to “24.47 parts”. Except that, an aqueous dispersion (C8-1) of mercerized cellulose (C8) was obtained in the same manner as in Production Example 5.

<Production Example 13>
An aqueous dispersion (C9-1) of mercerized cellulose (C9) was prepared in the same manner as in Production Example 5 except that the amount of cellulose (B1) was changed from “45.35 parts” to “47.57 parts”. Obtained.

<Production Example 14>
The amount of 12% sodium hydroxide aqueous solution was changed from “289.4 parts” to “144.7 parts”, and the amount of cellulose (B1) was changed from “45.35 parts” to “47.57 parts”. Except that, an aqueous dispersion (C10-1) of mercerized cellulose (C10) was obtained in the same manner as in Production Example 5.

<Production Example 15>
The amount of 12% sodium hydroxide aqueous solution was changed from “289.4 parts” to “165.4 parts”, and the amount of cellulose (B1) was changed from “45.35 parts” to “62.97 parts”. Except that, an aqueous dispersion (C11-1) of mercerized cellulose (C11) was obtained in the same manner as in Production Example 5.

<Production Example 16>
The amount of 12% sodium hydroxide aqueous solution was changed from “289.4 parts” to “82.71 parts”, and the amount of cellulose (B1) was changed from “45.35 parts” to “90.74 parts”. Except that, an aqueous dispersion (C12-1) of mercerized cellulose (C12) was obtained in the same manner as in Production Example 5.

<Example 1>
Water dispersion of mercerized cellulose (C1) obtained in Production Example 5 while chopping 400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1 with a mincing machine (12VR-400K manufactured by ROYAL) 334.7 parts of liquid (C1-1) was added and mixed and neutralized to obtain a chopped gel. Further, the chopped gel was dried with a ventilation band dryer {90 ° C., wind speed 2 m / sec} to obtain a dried product. The dried product was pulverized with a juicer mixer (Osterizer BLENDER manufactured by Oster), and then sieved to adjust the particle size to a particle size range of 710 to 150 μm to obtain pulverized particles. Subsequently, 100 parts of the pulverized particles were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Co., Ltd .: rotation speed 2000 rpm), and a surface cross-linking agent {water / methanol mixture containing ethylene glycol diglycidyl ether at a concentration of 9% was added thereto. Solution (water / methanol = 70/30; weight ratio)} 5.5 parts was added, mixed uniformly, and then allowed to stand at 90 ° C. for 45 minutes to obtain absorbent resin particles (1) of the present invention. .

<Example 2>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A2) obtained in Production Example 2”, and “Manufacturing Example 5 The aqueous dispersion (C1-1) 334.7 parts of the obtained mercerized cellulose (C1) ”was obtained as“ the aqueous dispersion (C2-1) 282.3 of the mercerized cellulose (C2) obtained in Production Example 6. Absorbent resin particles (2) of the present invention were obtained in the same manner as in Example 1 except that the “parts” were changed.

<Example 3>
“400 parts of the crosslinked polymer hydrated gel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrated gel (A3) obtained in Production Example 3”, and “In Production Example 5” The aqueous dispersion (C1-1) 334.7 parts of the obtained mercerized cellulose (C1) ”was“ the aqueous dispersion (C3-1) 256.1 of the mercerized cellulose (C3) obtained in Production Example 7. Absorbent resin particles (3) of the present invention were obtained in the same manner as in Example 1 except that the “parts” were changed.

<Example 4>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A4) obtained in Production Example 4”, and “In Production Example 5” The aqueous dispersion (C1-1) 334.7 parts of the obtained mercerized cellulose (C1) "was obtained as" the aqueous dispersion (C4-1) 191.3 of the mercerized cellulose (C4) obtained in Production Example 8. " Absorbent resin particles (4) of the present invention were obtained in the same manner as in Example 1 except that the “parts” were changed.

<Example 5>
"334.7 parts of aqueous dispersion (C1-1) of mercerized cellulose (C1) obtained in Production Example 5" was obtained in 35.81 parts of 48.5% aqueous sodium hydroxide solution and Production Example 9 Absorbent resin particles (5) of the present invention were obtained in the same manner as in Example 1 except that it was changed to "190.0 parts of aqueous dispersion (C5-1) of mercerized cellulose (C5)".

<Example 6>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A4) obtained in Production Example 4”, and “In Production Example 5” The obtained mercerized cellulose (C1) in aqueous dispersion (C1-1) 334.7 parts ”was converted to“ 45.27 parts of 48.5% aqueous sodium hydroxide solution and mercerized cellulose (C6 Absorbent resin particles (6) of the present invention were obtained in the same manner as in Example 1, except that the aqueous dispersion (C6-1) was changed to 205.6 parts.

<Example 7>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A4) obtained in Production Example 4”, and “In Production Example 5” The obtained mercerized cellulose (C1) aqueous dispersion (C1-1) 334.7 parts "was obtained as" mercelized cellulose (C7) aqueous dispersion (C7-1) 93.72 obtained in Production Example 11. " Absorbent resin particles (7) of the present invention were obtained in the same manner as in Example 1 except that the “parts” were changed.

<Example 8>
Water-soluble vinyl monomer (a1-1) {acrylic acid, manufactured by Mitsubishi Chemical Corporation, purity 100%} 62.00 parts (0.86 mole parts), cross-linking agent (a3-1) {pentaerythritol triallyl ether, diiso -Made by Co., Ltd. While stirring and mixing 0.20 parts (0.0008 mole part), 282.3 parts of an aqueous dispersion (C2-1) of mercerized cellulose (C2) and 155.2 parts of deionized water. Maintained at 3 ° C. Nitrogen was introduced into the mixture to bring the dissolved oxygen amount to 1 ppm or less, and then 0.25 part of a 1% aqueous hydrogen peroxide solution and 0.47 part of a 2% aqueous ascorbic acid solution were added and mixed to initiate polymerization. . After the temperature of the mixture reached 40 ° C., polymerization was performed at 40 ± 2 ° C. for about 8 hours to obtain a crosslinked polymer hydrated gel (A5).

  400 parts of the obtained crosslinked polymer hydrogel (A5) was chopped with a mincing machine (12VR-400K manufactured by ROYAL) to obtain a chopped gel. Further, the chopped gel was dried with a ventilation band dryer {90 ° C., wind speed 2 m / sec} to obtain a dried product. The dried product was pulverized with a juicer mixer (Osterizer BLENDER manufactured by Oster), and then sieved to adjust the particle size to a particle size range of 710 to 150 μm to obtain pulverized particles. Subsequently, 100 parts of the pulverized particles were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Co., Ltd .: rotation speed: 2000 rpm). Solution (water / methanol = 70/30; weight ratio)} 5.0 parts was added, mixed uniformly, and then allowed to stand at 90 ° C. for 45 minutes to obtain absorbent resin particles (8) of the present invention. .

<Example 9>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A4) obtained in Production Example 4”, “obtained in Production Example 5” The obtained mercerized cellulose (C1) in aqueous dispersion (C1-1) 334.7 parts "was obtained as 93.72 parts of mercerized cellulose (C7) aqueous dispersion (C7-1) obtained in Production Example 11. The absorbent resin particles (9) of the present invention were obtained in the same manner as in Example 1 except that the “surface cross-linking agent 5.5 parts” was changed to “surface cross-linking agent 5 parts”. It was.

<Example 10>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A4) obtained in Production Example 4”, “obtained in Production Example 5” The obtained mercerized cellulose (C1) in aqueous dispersion (C1-1) 334.7 parts "was obtained as 93.72 parts of mercerized cellulose (C7) aqueous dispersion (C7-1) obtained in Production Example 11. The absorbent resin particles (10) of the present invention were changed in the same manner as in Example 1 except that "Surface crosslinking agent 5.5 parts" was changed to "Surface crosslinking agent 4.5 parts". Got.

<Example 11>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A4) obtained in Production Example 4”, and “In Production Example 5” The aqueous dispersion (C1-1) 334.7 parts of the obtained mercerized cellulose (C1) ”was“ the aqueous dispersion (C8-1) 193.1 of the mercerized cellulose (C8) obtained in Production Example 12. Absorbent resin particles (11) of the present invention were obtained in the same manner as in Example 1 except that the “parts” were changed.

<Example 12>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A4) obtained in Production Example 4”, “obtained in Production Example 5” The aqueous dispersion (C1-1) 334.7 parts of the obtained mercerized cellulose (C1) "was 193.1 parts of the aqueous dispersion (C8-1) of the mercerized cellulose (C8) obtained in Production Example 12. The absorbent resin particles (12) of the present invention were obtained in the same manner as in Example 1, except that the "surface crosslinking agent 5.5 parts" was changed to "surface crosslinking agent 5 parts". It was.

<Example 13>
"334.7 parts of aqueous dispersion (C1-1) of mercerized cellulose (C1) obtained in Production Example 5" was obtained in 35.81 parts of 48.5% aqueous sodium hydroxide solution and Production Example 9 Implemented except that it was changed to 190.0 parts of an aqueous dispersion (C5-1) of mercerized cellulose (C5) and that "5.5 parts of surface cross-linking agent" was changed to "5 parts of surface cross-linking agent". In the same manner as in Example 1, absorbent resin particles (13) of the present invention were obtained.

<Example 14>
"334.7 parts of the aqueous dispersion (C1-1) of the mercerized cellulose (C1) obtained in Production Example 5" is referred to as "the aqueous dispersion of the mercerized cellulose (C9) obtained in Production Example 13 (C9- 1) Absorbent resin particles (14) of the present invention were obtained in the same manner as in Example 1 except that the content was changed to “337.0 parts”.

<Example 15>
"334.7 parts of the aqueous dispersion (C1-1) of the mercerized cellulose (C1) obtained in Production Example 5" is referred to as "the aqueous dispersion of the mercerized cellulose (C9) obtained in Production Example 13 (C9- 1) Absorption of the present invention in the same manner as in Example 1 except that it was changed to 337.0 parts and that "surface crosslinking agent 5.5 parts" was changed to "surface crosslinking agent 4.5 parts". Resin particles (15) were obtained.

<Example 16>
"334.7 parts of an aqueous dispersion (C1-1) of mercerized cellulose (C1) obtained in Production Example 5" was obtained in "35.81 parts of 48.5% aqueous sodium hydroxide solution and Production Example 14". Absorbent resin particles (16) of the present invention were obtained in the same manner as in Example 1 except that it was changed to "192.2 parts of aqueous dispersion (C10-1) of mercerized cellulose (C10)".

<Example 17>
“400 parts of the crosslinked polymer hydrated gel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrated gel (A3) obtained in Production Example 3”, and “In Production Example 5” The obtained mercerized cellulose (C1) aqueous dispersion (C1-1) 334.7 parts "was obtained by adding" mercelized cellulose (C 11 ) aqueous dispersion (C 11 -1) 228 obtained in Production Example 15 ". Absorbent resin particles (17) of the present invention were obtained in the same manner as in Example 1 except that the content was changed to “.3 parts”.

<Example 18>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A3) obtained in Production Example 3”, “obtained in Production Example 5” aqueous dispersion (C1-1) 334.7 parts "and" aqueous dispersion mercerized cellulose obtained in production example 15 (C 11) of the resulting mercerized cellulose (C1) (C 11 -1) 228. Absorbent resin particles (18) of the present invention in the same manner as in Example 1, except that it was changed to "3 parts" and that "surface crosslinking agent 5.5 parts" was changed to "surface crosslinking agent 5 parts". Got.

<Example 19>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A3) obtained in Production Example 3”, “obtained in Production Example 5” aqueous dispersion (C1-1) 334.7 parts "and" aqueous dispersion mercerized cellulose obtained in production example 15 (C 11) of the resulting mercerized cellulose (C1) (C 11 -1) 228. Absorbent resin particles (19) of the present invention in the same manner as in Example 1, except that "3 parts" was changed and "5.5 parts of surface cross-linking agent" was changed to "6 parts of surface cross-linking agent". Got.

<Example 20>
“400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1” was changed to “400 parts of the crosslinked polymer hydrogel (A3) obtained in Production Example 3”, “obtained in Production Example 5” The obtained mercerized cellulose (C1) in aqueous dispersion (C1-1) (334.7 parts) "was converted to" 20.46 parts of 48.5% aqueous sodium hydroxide and mercerized cellulose (C12) obtained in Production Example 16. " Absorbent resin particles (20) of the present invention were obtained in the same manner as in Example 1 except that the aqueous dispersion (C12-1) was changed to 173.4 parts.

<Comparative Example 1>
4000 parts of a 5% aqueous solution of carboxymethyl cellulose (Aldrich, substitution degree 0.7) and 1000 parts of a 5% aqueous solution of polyvinyl alcohol (Wako Pure Chemical Industries, Ltd., weight average molecular weight 44000, saponification degree 88 mol%) Was stirred and mixed at 80 ° C. for 5 hours to obtain a mixed aqueous solution. Next, 50 parts of 40% glyoxal aqueous solution and 2.5 parts of concentrated sulfuric acid were added to this mixed aqueous solution, stirred uniformly, and then allowed to stand in a hot air dryer at 100 ° C. for 7 hours to dry the crosslinking reaction. As a result, a dried product was obtained. The dried product was pulverized with a juicer mixer (Osterizer BLENDER, manufactured by Oster Co., Ltd.) and then sieved with a sieve having openings of 710 μm and 150 μm to obtain comparative absorbent resin particles (H1).

<Comparative example 2>
While 100 parts of the absorbent resin particles (H1) obtained in Comparative Example 1 were stirred at high speed (high speed stirring turbulizer manufactured by Hosokawa Micron Corporation: rotation speed 2000 rpm), a surface crosslinking agent {ethylene glycol diglycidyl ether was added thereto. 5.0 parts of water / methanol mixed solution (water / methanol = 70/30; weight ratio) contained at a concentration of 9% was added, mixed uniformly, and then allowed to stand at 90 ° C. for 45 minutes for comparison. Absorbent resin particles (H2) were obtained.

<Comparative Example 3>
Absorbent resin particles (H3) for comparison were obtained in the same manner as in Comparative Example 1 except that the standing time in the hot air dryer was changed from “7 hours” to “10 hours”.

  About the absorptive resin particle obtained in Examples 1-20 and Comparative Examples 1-3, the amount of water retention and the amount of absorption under load were evaluated, and these results are shown in Table 1.

  As can be seen from Table 1, the absorbent resin particles (Examples 1 to 20) of the present invention contain water content, absorbed amount under load, and cellulose (B) content compared to the absorbent resin particles of Comparative Examples 1 to 3. The balance of quantity was remarkably excellent.

  Using the absorbent resin particles obtained in Examples 1 to 20 and Comparative Examples 1 to 3, absorbers and absorbent articles (paper diapers) were prepared as follows, and surface dryness values by the SDME method were evaluated. The results are shown in Table 2.

<Preparation of absorbent articles (paper diapers)>
120 parts of fluff pulp and 80 parts of an evaluation sample {absorbent resin particles} were mixed with an airflow type mixing apparatus {Pad former manufactured by Autech Co., Ltd.} to obtain a mixture. m ² and so as to uniformly acrylic plate stacked on (thickness 4 mm), and pressed for 30 seconds at a pressure of 5Kg / cm ^2, to obtain an absorbent. The absorbent body is cut into a 14 cm × 36 cm rectangle, and water absorbent paper (basis weight: 15.5 g / m ² , manufactured by Advantech Co., Ltd., filter paper No. 2) having the same size as the absorbent body is arranged above and below each. A paper diaper was prepared by arranging a polyethylene sheet (polyethylene film UB-1 manufactured by Tamapoly Co., Ltd.) on the back surface and a non-woven fabric (basis weight 20 g / m ² , Eltas Guard manufactured by Asahi Kasei Co., Ltd.) on the surface.

<Surface dryness value by SDME method>
A disposable diaper (artificial urine (0.03% by weight of potassium chloride, 0.08% by weight of magnesium sulfate, 0.08% by weight of magnesium sulfate, 0.8% by weight of sodium chloride) in which the detector of the SDME (Surface Dryness Measurement Equipment) tester (manufactured by WK system) is sufficiently moistened. % And deionized water 99.09% by weight) and a paper diaper was soaked for 60 minutes. }, A 0% dryness value was set, and then the detector of the SDME tester was prepared by drying a paper diaper {paper diaper at 80 ° C. for 2 hours by heating. } Was set to 100% dryness, and the SDME tester was calibrated. Next, set a metal ring (inner diameter 70 mm, length 50 mm) in the center of the paper diaper to be measured, inject 80 ml of artificial urine, and absorb the artificial urine {until no gloss can be confirmed by artificial urine}, immediately The metal ring was removed, an SDME detector was placed in the center of the paper diaper, and measurement of the surface dryness value was started. The value 5 minutes after the start of measurement was taken as the surface dryness value. The artificial urine, measurement atmosphere, and standing atmosphere were 25 ± 5 ° C. and 65 ± 10% RH.

  As can be seen from Table 2, the absorbent article using the absorbent resin particles of the present invention has a surface dryness value and a cellulose (B) content as compared with an absorbent article using comparative absorbent resin particles. The balance was remarkably excellent. Therefore, it is easily predicted that the absorbent article to which the absorbent resin particles of the present invention are applied has little environmental load and there is no fear of leakage or fog.

  The absorbent resin particles of the present invention can be applied to an absorbent body containing absorbent resin particles and a fibrous material, and absorbent articles {paper diapers, sanitary napkins, and medical blood retaining bodies comprising the absorbent body. It is useful for the agent}. In addition, pet urine absorbent, urine gelling agent for portable toilets, freshness preservation agent for fruits and vegetables, drip absorbent for meat and seafood, cooler, disposable warmer, battery gelling agent, water retention agent for plants and soil, dew condensation It can also be used in various applications such as inhibitors, water-stopping agents, packing agents and artificial snow.

Claims (7)

A hydrogel comprising a crosslinked polymer (A) obtained by copolymerizing a monomer having (meth) acrylic acid (salt) (a1) and a crosslinking agent (a3) as an essential constituent monomer (a), and water Step (1) of mixing with mercerized cellulose (C) to obtain a crosslinked polymer / cellulose composite gel (A / B); or
(Meth) acrylic acid (salt) (a1) and a monomer having the cross-linking agent (a3) as essential constituent monomer (a) and mercerized cellulose (C) are mixed and then copolymerized. Step (2) of obtaining a crosslinked polymer / cellulose composite gel (A / B),
And a step (3) of obtaining absorptive resin particles by post-treating the crosslinked polymer / cellulose composite gel (A / B). Based on the weight of the essential constituent monomer (a) and mercerized cellulose (C), the amount of the essential constituent monomer (a) used is 30 to 85% by weight, and the amount of mercerized cellulose (C) used is 15. The production method according to claim 1, which is ˜70 wt%. Absorbent resin particles obtained by the production method according to claim 1 or 2,
Absorption characterized by containing (meth) acrylic acid (salt) (a1) and cross-linking polymer (A) having cross-linking agent (a3) as essential constituent monomer (a) and cellulose (B). Resin particles. Formulas (1), (2) and (3); Formulas (4), (5) and (6); Formulas (7), (8) and (9); or Formulas (10), (11) and ( The absorptive resin particles according to claim 3 satisfying any one of 12).

33 ≦ (X) ≦ 40 (1)
20 ≦ (Y) ≦ 28 (2)
5 ≦ (Z) ≦ 15 (3)

30 ≦ (X) ≦ 37 (4)
15 ≦ (Y) ≦ 23 (5)
15 <(Z) ≦ 30 (6)

25 ≦ (X) ≦ 33 (7)
10 ≦ (Y) ≦ 20 (8)
30 <(Z) ≦ 50 (9)

21 ≦ (X) ≦ 28 (10)
7 ≦ (Y) ≦ 13 (11)
50 <(Z) ≦ 60 (12)

However, (X) is the water retention amount (g / g) of the absorbent resin particles after being immersed in physiological saline for 1 hour, and (Y) is the absorbency after being immersed in physiological saline under a load of 6.2 kPa for 1 hour. The absorption amount (g / g) and (Z) of the resin particles are the content (%) of cellulose (B) based on the weight of the crosslinked polymer (A) and cellulose (B). The content of the crosslinked polymer (A) is 40 to 95% by weight and the content of the cellulose (B) is 5 to 60% by weight based on the weight of the crosslinked polymer (A) and the cellulose (B). The absorbent resin particle according to 3 or 4.   The absorber containing the absorptive resin particle in any one of Claims 3-5.   An absorbent article using the absorbent body according to claim 6.