JP2009242466A - Method for producing absorptive resin particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an absorptive resin particles including a material originating from vegetables and having excellent absorption performance. <P>SOLUTION: The method for producing the absorptive resin particles includes: a step (1) for copolymerizing monomers including a water-soluble vinyl monomer (a1) and/or a hydrolyzable vinyl monomer (a2) and a crosslinking agent (a3) as indispensable constituent monomers (a) to obtain a crossliked polymer (A) and then mixing the crosslinked polymer (A) and a cellulose (B) to obtain a crosslinked polymer/cellulose composite gel (A/B); or a step (2) for mixing the monomers including the water-soluble vinyl monomer (a1) and/or the hydrolyzable vinyl monomer (a2) and the crosslinking agent (a3) as indispensable constituent monomers (a) and the cellulose (B) with each other and then copolymerizing these to obtain a crosslinked polymer/cellulose composite gel (A/B); and a step (3) for subjecting the crosslinked polymer/cellulose composite gel (A/B) to after-treatment to obtain the absorptive resin particles. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing absorbent resin particles, 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 raw materials include crosslinked carboxymethyl cellulose (Non-patent Document 1, Patent Document 1), crosslinked alginate, 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.

  The objective of this invention is providing the manufacturing method of the absorbent resin particle which was excellent in the absorption performance including the plant-derived raw material.

The manufacturing method of the absorbent resin particles of the present invention is characterized in that the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinking agent (a3) are essential constituent monomers (a). After the monomer is copolymerized to obtain a crosslinked polymer (A), the crosslinked polymer (A) and cellulose (B) are mixed to obtain a crosslinked polymer / cellulose composite gel (A / B). Step (1); or a monomer having water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and cross-linking agent (a3) as essential constituent monomer (a), and cellulose (B ) And then copolymerizing them to obtain a crosslinked polymer / cellulose composite gel (A / B) (2);
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.

According to the method for producing absorbent resin particles of the present invention, it is possible to easily produce absorbent resin particles that exhibit high absorption performance despite the use of plant-derived materials (cellulose).
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.

  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, microbially produced polysaccharides, chitin and chitosan, etc.), regenerated cellulose (for example, cellophane and regenerated fibers, etc.) 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 ether (for example, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose), cellulose ester (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.

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

  As for the usage-amount (weight%) of a cellulose (B), 5-60 are preferable based on the weight of an essential structural monomer (a) and a cellulose (B), More preferably, it is 15-50, Especially preferably, 30- 40. Within this range, the absorption performance is further improved.

  The used amount (% by weight) of the essential constituent monomer (a) is preferably 40 to 95, more preferably 50 to 85, particularly based on the weight of the essential constituent monomer (a) and cellulose (B). Preferably it is 60-70. Within this range, the absorption performance is further improved.

  30-150 are preferable, as for the mixing temperature (degreeC) of a crosslinked polymer (A) and a cellulose (B), More preferably, it is 40-120, Most preferably, it is 50-100. 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 cellulose (B), known devices {double-arm kneader, internal mixer (Banbury mixer), self-cleaning mixer, gear compounder, screw-type extruder, screw Type kneader, minced machine, turbulizer, cylindrical mixer, V-shaped mixer, ribbon type mixer, screw type mixer, double arm type mixer, pulverizing type kneader, groove type mixer, vertical type mixer Etc.} can be used. These can be used in combination.

<Step (2)>
Mixing the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the monomer having the crosslinking agent (a3) as an essential constituent monomer (a) with cellulose (B) If it can mix uniformly, there will be no restriction | limiting in a method, It can carry out by a well-known method.

  As a mixing device of the monomer and cellulose (B), known devices {double-arm kneader, internal mixer (Banbury mixer), self-cleaning mixer, gear compounder, screw type extruder, screw type kneader, Mincing 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.

  As for the usage-amount (weight%) of a cellulose (B), 5-60 are preferable based on the weight of an essential structural monomer (a) and a cellulose (B), More preferably, it is 15-50, Especially preferably, 30- 40. Within this range, the absorption performance is further improved.

  The used amount (% by weight) of the essential constituent monomer (a) is preferably 40 to 95, more preferably 50 to 85, particularly based on the weight of the essential constituent monomer (a) and cellulose (B). Preferably it is 60-70. 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.}.

<Step (3)>
The crosslinked polymer / cellulose composite gel (A / B) obtained in the step (1) or (2) can be led 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, Japanese Patent Application Laid-Open Nos. 2003-225565 and 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 particles obtained by the production method of the present invention comprise the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinking agent (a3) as essential constituent monomers (a). When it contains a crosslinked polymer (A) and cellulose (B) but is obtained by copolymerizing a monomer containing the essential constituent monomer (a) in the presence of cellulose (B), It is preferable that the graft ratio of B) and 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 can be adjusted depending on the kind of the polymerization initiator, etc., and azo initiators (azobisisobutyronitrile, azobiscyanovaleric acid, 2,2′-azobis (2-aminodipropane) hydrochloride, and When 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propionamide or the like) is used, the graft rate tends to be low.

The graft ratio is measured as follows.
Sieve with a sieve having a nominal aperture of 1 mm (JIS Z8801: 2006) and adjust to a size of 1 mm or less, then dry at 100 ° C. for 1 hour, sieve with an aperture of 150, 300 μm, and 150 to 300 μm. Prepare a measurement sample. 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. However, (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 obtained by the production method of the present invention are represented by formulas (1), (2) and (3); formulas (4), (5) and (6); formulas (7), (8) and ( 9); or any one of the formulas (10), (11) and (12) is preferably satisfied, more preferably the formulas (13), (14) and (15); the formulas (16), (17) and (18); satisfying any of the formulas (19), (20) and (21); or the formulas (22), (23) and (24).

29 ≦ (X) ≦ 38 (1)
17 ≦ (Y) ≦ 25 (2)
5 ≦ (Z) ≦ 15 (3)

21 ≦ (X) ≦ 34 (4)
8 ≤ (Y) ≤ 19 (5)
15 <(Z) ≦ 30 (6)

22 ≦ (X) ≦ 30 (7)
6 ≦ (Y) ≦ 19 (8)
30 <(Z) ≦ 50 (9)

18 ≦ (X) ≦ 26 (10)
6 ≦ (Y) ≦ 17 (11)
50 <(Z) ≦ 60 (12)

30 ≦ (X) ≦ 37 (13)
18 ≦ (Y) ≦ 24 (14)
5 ≦ (Z) ≦ 15 (15)

22 ≦ (X) ≦ 33 (16)
9 ≦ (Y) ≦ 18 (17)
15 <(Z) ≦ 30 (18)

23 ≦ (X) ≦ 29 (19)
7 ≤ (Y) ≤ 18 (20)
30 <(Z) ≦ 50 (21)

20 ≦ (X) ≦ 24 (22)
7 ≦ (Y) ≦ 16 (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

  In the absorbent resin particles obtained by the production method of the present invention, other additives (for example, known preservatives, fungicides, antibacterial agents (for example, JP-A No. 2003-225565, JP-A No. 2006-131767), Antioxidants, ultraviolet absorbers, colorants, fragrances, deodorants, inorganic powders, organic fibrous materials, etc.}.

  100-800 are preferable, as for the weight average particle diameter (micrometer) of the absorbent resin particle obtained by the manufacturing method 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 particles obtained by the production method 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 obtained by the production method of the present invention can be used as an absorbent body together with the fibrous material. The structure and production method of the absorber are the same as those known in the art (Japanese Patent Laid-Open Nos. 2003-225565, 2006-131767, and 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).

<Example 1>
While pulverizing 400 parts of the crosslinked polymer hydrogel (A1) obtained in Production Example 1 with a mincing machine (12VR-400K, manufactured by ROYAL), 99.2 parts of 35% aqueous sodium hydroxide and cellulose (B1) {KC Flock W-400G, Nippon Paper Chemicals Co., Ltd.} 45.3 parts was added, 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”, “35% aqueous sodium hydroxide solution 99” .2 parts "was changed to" 70.9 parts of 35% sodium hydroxide aqueous solution "and" Cellulose (B1) 45.3 parts "was changed to" Cellulose (B2) {Theolas TG-101, manufactured by Asahi Kasei Chemicals Corporation. } The absorbent resin particle (2) of the present invention was obtained in the same manner as in Example 1 except that it was changed to “75.6 parts”.

<Example 3>
“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”, “35% aqueous sodium hydroxide solution 99” .2 parts "was changed to" 56.7 parts of 35% sodium hydroxide aqueous solution "and" cellulose (B1) 45.3 parts "was changed to" cellulose (B3) {KC Flock W-100GK, Nippon Paper Chemicals Co., Ltd. " Absorbent resin particles (3) of the present invention were obtained in the same manner as in Example 1 except that the product was changed to "90.7 parts made by company".

<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”, “35% aqueous sodium hydroxide solution 99” .2 parts "was changed to" 120.5 parts of 35% sodium hydroxide aqueous solution "and" Cellulose (B1) 45.3 parts "was changed to" Cellulose (B4) {Theolas TG-F20, manufactured by Asahi Kasei Chemicals Corporation. } Except having changed to "22.7 parts", it carried out similarly to Example 1, and obtained the absorbent resin particle (4) of this invention.

<Example 5>
In the same manner as in Example 1, except that “cellulose (B1) 45.3 parts” was changed to “cellulose (B5) {KC Flock W-200G, manufactured by Nippon Paper Chemicals Co., Ltd.} 47.6 parts”. Absorbent resin particles (5) of the invention were obtained.

<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 (A3) obtained in Production Example 3”, “35% aqueous sodium hydroxide solution 99” .2 parts "was changed to" 56.7 parts of 35% sodium hydroxide aqueous solution "and" cellulose (B1) 45.3 parts "was changed to" cellulose (B6) {KC Flock W-300G, Nippon Paper Chemicals Co., Ltd. " Absorbent resin particles (6) of the present invention were obtained in the same manner as in Example 1 except that the product was changed to "63.0 parts by company".

<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”, “35% aqueous sodium hydroxide solution 99” .2 parts "was changed to" 120.5 parts of 35% sodium hydroxide aqueous solution "and" cellulose (B1) 45.3 parts "was changed to" cellulose (B7) {NP fiber W-10MG2, Nippon Paper Chemicals Co., Ltd. " Absorbent resin particles (7) of the present invention were obtained in the same manner as in Example 1 except that the product was changed to "6.8 parts made by company".

<Example 8>
“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”, “35% aqueous sodium hydroxide solution 99” .2 parts "was changed to" 120.5 parts of 35% sodium hydroxide aqueous solution "and" Cellulose (B1) 45.3 parts "was changed to" Cellulose (B4) {Theolas TG-F20, manufactured by Asahi Kasei Chemicals Corporation. } Except having changed to "24.5 parts", it carried out similarly to Example 1, and obtained the absorbent resin particle (8) of this invention.

<Example 9>
Absorbent resin particles (9) of the present invention were obtained in the same manner as in Example 1 except that “5.5 parts of the surface crosslinking agent” was changed to “3 parts of the surface crosslinking agent”.

<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 (A2) obtained in Production Example 2”, “35% aqueous sodium hydroxide solution 99” .2 parts "was changed to" 70.9 parts of 35% sodium hydroxide aqueous solution ", and" cellulose (B1) 45.3 parts "was changed to" cellulose (B2) {Theolas TG-101, manufactured by Asahi Kasei Chemicals Corporation} " The absorbent resin particles of the present invention (in the same manner as in Example 1, except that “75.6 parts” and “5.5 parts of the surface cross-linking agent” were changed to “3 parts of the surface cross-linking agent”) 10) was obtained.

<Example 11>
“Cellulose (B1) 45.3 parts” was changed to “Cellulose (B5) {KC Flock W-200G, manufactured by Nippon Paper Chemicals Co., Ltd.} 47.6 parts”, and “Surface crosslinking agent 5.5 parts” The absorbent resin particles (11) of the present invention were obtained in the same manner as in Example 1 except that was changed to “3 parts of the surface cross-linking agent”.

<Example 12>
Water-soluble vinyl monomer (a1-1) {acrylic acid} 21.7 parts (0.30 mol part), water-soluble vinyl monomer (a1-2) {sodium acrylate} 72.9 parts (0.78 mol part) 3) While stirring / mixing 0.17 part (0.00097 mole part) of cross-linking agent (a3-2) {ethylene glycol diglycidyl ether}, 94.5 parts of cellulose (B1) and 421.4 parts of deionized water. Kept at ℃. Nitrogen gas is allowed to flow into this mixture so that the amount of dissolved oxygen in the mixture is 1 ppm or less, and then 0.31 part of 1% aqueous hydrogen peroxide solution and 0.58 part of 2% aqueous ascorbic acid solution are added and mixed. Polymerization was started. 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).

  While chopping 400 parts of the resulting crosslinked polymer hydrogel (A5) with a mincing machine (12VR-400K manufactured by ROYAL), 70.9 parts of 35% aqueous sodium hydroxide solution was added, mixed and neutralized, A chopped gel was obtained. 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. 3.0 parts of a solution (water / methanol = 70/30; weight ratio)} was added, mixed uniformly, and then allowed to stand at 90 ° C. for 45 minutes to obtain the absorbent resin particles (12) of the present invention. .

<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), the surface cross-linking agent {ethylene glycol diglycidyl ether was concentrated Water / methanol mixed solution containing 9% (water / methanol = 70/30; weight ratio)} 5.0 parts was added, mixed uniformly, and then allowed to stand at 90 ° C. for 45 minutes for absorption for comparison. 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 1-12 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 12) of the present invention were remarkably superior in the water retention amount and the absorbed amount under load as compared with the absorbent resin particles of Comparative Examples 1 to 3.

  Using the absorbent resin particles obtained in Examples 1 to 12 and Comparative Examples 1 to 3, an absorber and an absorbent article (paper diaper) were prepared as follows, and the surface dryness value by the SDME method was 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) % 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 was significantly superior in surface dryness value compared to the absorbent article using comparative absorbent resin particles. 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 (4)

A water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a monomer having the crosslinking agent (a3) as an essential constituent monomer (a) are copolymerized to form a crosslinked polymer (A). Step (1) for obtaining a crosslinked polymer / cellulose composite gel (A / B) by mixing the crosslinked polymer (A) and cellulose (B), or the water-soluble vinyl monomer (a1) and After mixing the hydrolyzable vinyl monomer (a2) and the monomer having the crosslinking agent (a3) as an essential constituent monomer (a) with cellulose (B), these are copolymerized and crosslinked. A step (2) of obtaining a 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 essential constituent monomer (a) and cellulose (B), the amount of essential constituent monomer (a) used is 40 to 95% by weight, and the amount of cellulose (B) used is 5 to 60% by weight. The manufacturing method according to claim 1.   The absorber containing the absorptive resin particle obtained by the manufacturing method of Claim 1 or 2.   An absorbent article using the absorber according to claim 3.