JP2008247949A - Absorbing resin particle, absorbent material and absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbing resin particle having excellent absorbing power to an aqueous liquid (especially blood). <P>SOLUTION: The absorbing resin particles contain (A) crosslinked polymer particles comprising (a1) a water-soluble vinyl monomer and/or (a2) a hydrolyzable vinyl monomer and (a3) an internal crosslinking agent as essential constitution units, (B) a coagulating agent and (C) water-insoluble inorganic porous fine particles. The method for producing the absorbing resin particles comprises a polymerization step to obtain a water-containing crosslinked polymer (A') by polymerizing (a1) a water-soluble vinyl monomer and/or (a2) a hydrolyzable vinyl monomer and (a3) an internal crosslinking agent as essential constitution units, a compounding step to obtain composite particles (AB) by mixing the water-containing crosslinked polymer (A') with the coagulation agent (B), and a mixing step to mix the composite particles (AB) with the water-insoluble inorganic porous fine particles (C) to obtain the absorbing resin particles. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to absorbent resin particles, an absorbent body using the same, and an absorbent article.

A water-absorbent resin composition comprising a specific water-absorbent resin and a non-volatile water-soluble compound {polyhydric alcohol, amino alcohol, water-soluble inorganic compound (such as carbonate and bicarbonate), etc.} is known ( Patent Document 1).
Japanese Patent Laid-Open No. 9-157534

However, since the conventional water-absorbent resin composition has hydrophilicity in the vicinity of the surface, the gel absorbs an aqueous liquid {body fluid (blood, urine, lymph, etc.), water, physiological saline, artificial blood, etc.}. There is a problem that blocking tends to occur, and the absorption performance (water retention amount, absorption amount under pressure, absorption magnification, absorption rate, etc.) of an aqueous liquid (particularly blood) is insufficient.
That is, an object of the present invention is to provide absorbent resin particles having excellent absorption performance of an aqueous liquid (particularly blood).

  The absorbent resin particles of the present invention are characterized by a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis, and an internal crosslinking agent (a3). The gist is that it contains crosslinked polymer particles (A) as essential constituent units, a flocculant (B), and water-insoluble inorganic porous fine particles (C).

Moreover, the absorber of this invention contains said absorbent resin particle and fiber.
Moreover, the absorbent article of this invention arrange | positions said absorber.
Moreover, the manufacturing method of the absorbent resin particles of the present invention is characterized by the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis, and internal crosslinking. A polymerization step of polymerizing the agent (a3) as an essential constituent unit to obtain a water-containing crosslinked polymer (A ′);
A compounding step of mixing the water-containing crosslinked polymer (A ′) and the flocculant (B) to obtain composite particles (AB);
The gist is that it includes a mixing step of mixing the composite particles (AB) and the water-insoluble inorganic porous fine particles (C) to obtain absorbent resin particles.

  The absorbent resin particles of the present invention are unlikely to cause gel blocking despite the fact that the vicinity of the surface is hydrophilic. Therefore, the absorbent resin particles of the present invention exhibit the effect of being excellent in the absorption performance (water retention amount, absorption amount under pressure, absorption rate, absorption rate, etc.) of an aqueous liquid (particularly blood).

  Water-soluble means the property of dissolving at least 100 g in 100 g of water at 25 ° C. The term “hydrolyzable” refers to the property of being hydrolyzed by the action of 50 ° C. water and, if necessary, the catalyst (acid or base) to make it water-soluble.

  There is no particular limitation on the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) which becomes the water-soluble vinyl monomer (a1) by hydrolysis, but is described in, for example, JP-A-2005-075982. Vinyl monomer (VM). Among these, water-soluble vinyl monomer (a1) {vinyl having at least one selected from the group consisting of a carboxy group, a sulfo group, a phosphono group, a hydroxyl group, a carbamoyl group, an amino group, and an ammonio group from the viewpoint of absorption performance and the like. Monomer}, more preferably vinyl monomer having at least one selected from the group consisting of carboxy group, sulfo group, phosphono group and carbamoyl group, particularly preferably (meth) acrylic acid (salt) and (meth) acrylamide, Most preferred is (meth) acrylic acid (salt). In addition, (meth) acrylic acid (salt) means (meth) acrylic acid and / or (meth) acrylate.

  When both the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as constituent units, the molar ratio {(a1) / (a2)} of these vinyl monomer units is 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 and the like are further improved. From the viewpoint of absorption performance and the like, it is preferable to use only a water-soluble vinyl monomer as a structural unit.

  As the internal cross-linking agent (a3), a known cross-linking agent or the like can be used. For example, the internal cross-linking agent (b1) described in JP-A No. 2003-225565 or the cross-linking described in JP-A No. 2005-075982 is used. Vinyl monomer (VM32) can be used. Among these internal cross-linking agents, an internal cross-linking agent having two or more ethylenically unsaturated groups is preferable from the viewpoint of absorption performance, and more preferably N, N′-methylenebisacrylamide, triallyl cyanurate, triallyl. Poly (meth) allyl ethers of isocyanurates and polyols having 2 to 10 carbon atoms, particularly preferably N, N'-methylenebisacrylamide, triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane and pentaerythritol triallyl ether Most preferred are N, N′-methylenebisacrylamide and pentaerythritol triallyl ether.

  The content (mol%) of the internal crosslinking agent (a3) unit is 0.01 to 5 based on the number of moles of the water-soluble vinyl monomer (a1) unit and the vinyl monomer (a2) unit from the viewpoint of absorption performance and the like. Is more preferable, 0.02 to 2 is more preferable, and 0.05 to 1.6 is particularly preferable. Within this range, the absorption performance is further improved.

The crosslinked polymer particles (A) can further contain other vinyl monomers (a4) that can be copolymerized as structural units. {It is preferable not to include other vinyl monomers (a4) as structural units. }.
The other vinyl monomer (a4) is not limited as long as it is a monomer that can be copolymerized with the water-soluble vinyl monomer (a1) or the like. For example, other vinyl monomers (a3) described in JP-A-2003-225565 And a hydrophobic vinyl monomer (VM31) described in JP-A-2005-075982.
When the other vinyl monomer (a4) is used as a structural unit, the content (mol%) of the (a4) unit is selected from the water-soluble vinyl monomer (a1) unit and the vinyl monomer (a2) unit from the viewpoint of absorption performance and the like. Based on the number of moles, 0.01 to 30 is preferable, 0.05 to 20 is more preferable, and 0.1 to 15 is particularly preferable.

  The weight average particle diameter (μm) of the crosslinked polymer particles (A) 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.

  As will be described later, the crosslinked polymer particles (A) are preferably in the form of composite particles (AB) in which all or part of the flocculant (B) is present. For the same reason, the weight average particle diameter in the form of the composite particles (AB) is preferably in the above range. The composite particles (AB) are distinguished from a mixture obtained by simply mixing the crosslinked polymer particles (A) and the flocculant (B).

  The weight average particle size is measured using a conventional method, for example, a low-tap test sieve shaker and a standard sieve (JIS Z8801-1: 2006), Perry's Chemical Engineers Handbook, 6th edition (Mac Glow Hill Book). -It is measured by the method described in Kanbany, 1984, page 21). That is, the JIS standard sieve is 1000 μm, 850 μm, 710 μm, 500 μm, 425 μm, 355 μm, 250 μm and 150 μm from the top, and the order of the saucer, or 500 μm, 355 μm, 250 μm, 150 μm, 125 μm, 75 μm and 45 μm, and the saucer from the top. Combine in order. About 50 g of the measured particles are put in the uppermost screen and shaken for 5 minutes with a low-tap test sieve shaker. Weigh the measured particles on each sieve and pan, and calculate the weight fraction of the particles on each sieve by taking the total as 100% by weight. This value is the logarithmic probability paper {horizontal axis is sieve aperture (particle size ), The vertical axis is plotted in the weight fraction}, a line connecting the points is drawn, and the particle diameter corresponding to the weight fraction of 50% by weight is obtained, and this is defined as the weight average particle diameter.

Further, the smaller the content of fine particles, the harder gel blocking occurs and the better absorption performance. Therefore, the content of fine particles of 150 μm or less (preferably 106 μm or less) in all particles is preferably 3% by weight or less, and more preferably Is 1% by weight or less.
The content of the fine particles can be determined using a plot created when determining the above weight average particle diameter.

  The shape of the crosslinked polymer particles (A) is not particularly limited, and examples thereof include an irregular crushed shape, a flake shape, a pearl shape, and a rice grain shape. Of these, an irregularly crushed shape is preferred from the viewpoint of good entanglement with the fibers and less fear of dropping out of the fibers. Moreover, the shape of the composite particle (AB) described later is the same, and the preferable shape is also the same.

  The crosslinked polymer particles (A) or the composite particles (AB) to be described later may be surface-crosslinked by a known method (for example, JP-A-2003-225565) as necessary. By surface crosslinking, the absorption performance (especially the amount absorbed under load) is further improved.

  The flocculant (B) is a chemical for condensing colloidal particles, which are components of turbidity and color, into flocs and facilitating mechanical separation by sedimentation, flotation or filtration (Chemical Handbook Application, Japan Chemical Society) , Revised 2nd edition, p1591).

  As the flocculant (B), aluminum salt (B1), iron salt (B2), copper salt (B3), sulfite (B4), bisulfite (B5), low molecular weight organic compound (B6) and polymer (B7) ) Is included.

  Examples of the aluminum salt (B1) include polyaluminum chloride, sulfuric acid band, potassium alum and sodium aluminate.

  Examples of iron salts (B2) include polyferric sulfate, ferrous salts (such as ferrous chloride, ferrous bromide, ferrous iodide and ferrous sulfate), ferric chloride, and ferric chloride. 3 iron, chlorinated copper, etc. are mentioned.

  Examples of the copper salt (B3) include cuprous salts (such as cuprous chloride, cuprous bromide, cuprous iodide and cuprous sulfate).

  Examples of the sulfite (B4) include ammonium sulfite, sodium sulfite, potassium sulfite, and lithium sulfite.

  Examples of the bisulfite (B5) include ammonium bisulfite, sodium bisulfate, potassium bisulfate, and lithium bisulfate.

  Examples of the low molecular organic compound (B6) include ascorbic acid (L-ascorbic acid, D-ascorbic acid, D, L-ascorbic acid, isoascorbic acid, etc.), ascorbate (L-ascorbic acid soda, D-ascorbic acid) Soda, D, L-sodium ascorbate, isoascorbate soda, ammonium L-ascorbate and potassium L-ascorbate).

  As the polymer (B7), polytrimethylammonioethyl (meth) acrylate, CMC sodium salt, sodium polyacrylate, polyacrylamide partial hydrolyzed salt (sodium salt, etc.), maleic acid copolymer, water-soluble aniline resin, Examples include polythiourea, polyethyleneimine, polyvinylpyridine, polyacrylamide, polyoxyethylene, and catalyzed starch.

  Among these, aluminum salt (B1) and iron salt (B2) are preferable from the viewpoint of absorption performance and the like, more preferably polyaluminum chloride, potassium alum, sulfate band, polyferric sulfate and ferric chloride, Polyaluminum chloride, ferric chloride and polyferric sulfate are preferred, and polyaluminum chloride is most preferred.

  The content (% by weight) of the flocculant (B) is preferably 0.001 to 10, more preferably 0.05 to 8, particularly preferably 0.1 based on the weight of the crosslinked polymer particles (A). ~ 5. Within this range, the absorption performance is further improved.

  The flocculant (B) is a mixture obtained by simply mixing the crosslinked polymer particles (A) and the flocculant (B) {most of the flocculant (B) is present inside the crosslinked polymer particles (A). do not do. However, from the viewpoint of absorption performance and the like, it is preferable that all or part of the flocculant (B) is present inside the crosslinked polymer particles (A) {composite particles (AB)}.

  The water-insoluble inorganic porous fine particles (C) are porous fine particles that do not dissolve in water, and can be used without limitation as long as they do not react with the crosslinked polymer particles (A), and include natural inorganic substances and synthetic inorganic substances. . In addition, since a metal may decompose | disassemble a crosslinked polymer particle (A) by oxidation / reduction reaction of a metal when a crosslinked polymer particle (A) contacts with water, it is not preferable.

  Examples of the water-insoluble inorganic porous fine particles (C) include oxides {silicon oxide, aluminum oxide, iron oxide, titanium oxide, magnesium oxide, zirconium oxide, etc.}, carbides {silicon carbide, aluminum carbide, etc.}, nitrides {titanium nitride, etc. Etc.} and these are composites {zeolite and talc etc.} and the like. Of these, oxides are preferable, and silicon oxide is more preferable.

The volume average particle diameter (nm) of the insoluble inorganic fine particles (C) is preferably 1 to 500, more preferably 3 to 100, particularly preferably 5 to 75, and most preferably 9 to 50. Within this range, the absorption performance is further improved.
The volume average particle diameter is measured in a solvent by a dynamic light scattering method {for example, Nanotrack particle size distribution analyzer UPA-EX150, Nikkiso Co., Ltd., He—Ne laser, 25 ° C., cyclohexane}.

The specific surface area (m ² / g) of the water-insoluble inorganic porous fine particles (C) is preferably 20 to 400, more preferably 30 to 350, and particularly preferably 40 to 300. Within this range, the absorption performance is further improved.
The specific surface area is measured according to JIS Z8830: 2001 (nitrogen, volume method, multipoint method).

The water-insoluble inorganic porous fine particles (C) can be easily obtained from the market. For example, {hereinafter trade name (chemical composition, volume average particle diameter μm, specific surface area m ² / g)}, Aerosil 130 (silicon dioxide, 16 , 130), Aerosil 200 (silicon dioxide, 12, 200), Aerosil 300 (silicon dioxide, 7, 300), Aerosil R972 (hydrophobized silicon dioxide, 16, 110), Aerosil MOX80 (silicon dioxide, 30, 80), Aerosil COK84 (silicon dioxide, 12, 170), Aerosil OX50T (silicon dioxide, 7, 40), titanium oxide P25 (titanium oxide, 20, 30) and aluminum oxide C (aluminum oxide, 13, 100) {Nippon Aerosil Co., Ltd. }; Denka fused silica F-300 (silicon dioxide, 11, 16 0) {Electrochemical Co., Ltd.}; Microid 850 (silicon dioxide, 13, 150) {Tokai Chemical Co., Ltd.}; Amorphous silica SP-1 (silicon dioxide, 14, 45) {Nozawa Co., Ltd.}; Thyroid 622 (silicon dioxide, 17, 350); Thyroid ED50 (silicon dioxide, 8, 400) {Grace Japan, Inc.}; Admuffin SO-C1 (Compound oxide, 0.1, 20) {Admatex, Inc.}; Aerosil 200 (silicon dioxide, 100, 12) {Degussa AG: Germany}; Toxeal (silicon dioxide, 2.5, 120) and Leoroseal (silicon dioxide, 2.5, 110) {Tokuyama Co., Ltd.}; Silicon, 2.5, 130) {Nippon Silica Industry Co., Ltd.}; and clebosol 30CAL2 5 (silicon oxide, 12, 200) {Clariant Japan Co., Ltd.} and the like can be preferably exemplified.

  The content (% by weight) of the water-insoluble inorganic porous fine particles (C) is preferably 0.01 to 2.5, more preferably 0.05 to 2, based on the weight of the crosslinked polymer particles (A). Most preferably, it is 0.1-1. Within this range, the absorption performance is further improved.

  The weight ratio (B / C) between the flocculant (B) and the water-insoluble inorganic porous fine particles (C) is preferably 0.01 / 10 to 2.5 / 0.001, from the viewpoint of absorption performance, etc. The ratio is preferably 0.05 / 8 to 2 / 0.05, particularly preferably 0.1 / 5 to 1 / 0.1, and most preferably 0.3 / 3 to 0.8 / 0.5.

The absorbent resin particles of the present invention can further contain additives.
Examples of additives include those described in publicly known (eg, Japanese Patent Application Laid-Open No. 2003-225565) {preservatives, fungicides, antibacterial agents, antioxidants, ultraviolet absorbers, colorants, fragrances, quenchers, etc. Odorants, organic fibrous materials, etc.} can be used.
When an additive is contained, the content (% by weight) may be in a range where the function of the additive can be exhibited, but an amount which impairs the effect of the present invention should not be contained {if it is within a known range there is no problem. }.

  The water retention amount (g / g) of the absorbent resin particles of the present invention is preferably 35 to 50, more preferably 36 to 48, and particularly preferably 37 to 46.

In addition, the amount of water retention is measured as follows based on JIS K7223-1996.
<Measurement method of water retention amount>
1.00 g of a measurement sample is placed in 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 in 1,000 ml of physiological saline (salt concentration 0.9%). After soaking for 1 hour without stirring, take out the tea bag and hang it for 15 minutes to drain it. Then, put the tea bag together with the centrifuge, centrifuge at 150G for 90 seconds to remove excess water, and remove the tea bag. The included weight (h1) is measured, and the water retention amount is obtained from the following equation. The physiological saline used and the temperature of the measurement atmosphere are 25 ± 2 ° C. In the following formula, (h2) is the weight measured by the same operation as described above when no measurement sample is present.
(Water retention amount) = {(h1)-(h2) -1.00} /1.00

  The absorption amount under load (g / g) of the absorbent resin particles of the present invention is preferably 18 to 25, more preferably 19 to 24, and particularly preferably 20 to 23.

The absorption amount under load is measured as follows.
<Measurement method of absorption under load>
A cylindrical plastic tube (inner diameter: 30 mm, height: 60 mm) with a nylon mesh of 63 μm (JIS Z8801-1: 2006) pasted on the bottom is set up vertically, and 0.10 g of a measurement sample is placed in it uniformly. After that, a weight of 29.5 mm in outer diameter is placed on the measurement sample so that the load on the measurement sample is 60 g / cm ^2, and the weight (h3) of the entire cylindrical plastic tube is measured, and physiological saline is used. In a petri dish (diameter: 12 cm) containing 60 ml, immerse the plastic tube containing the measurement sample with the nylon mesh side as the bottom surface (side immersed in physiological saline) and let stand for 1 hour. Then, the weight (h4) of the whole plastic tube is measured, and the amount of absorption under load is obtained from the following equation. The temperature of the physiological saline used and the measurement atmosphere was 25 ± 2 ° C.
(Absorption under load) = {(h4) − (h3)} / 0.10

  The absorbent resin particles of the present invention may contain the crosslinked polymer particles (A), the flocculant (B), and the water-insoluble inorganic porous fine particles (C). The all or part of the flocculant (B) is preferably present inside the crosslinked polymer particles (A). That is, the absorbent resin particle of the present invention is a mixture of the composite particle (AB) composed of the crosslinked polymer particle (A) and the flocculant (B) and the water-insoluble inorganic porous fine particles (C). Is preferred.

  It can be confirmed by a known method that all or part of the flocculant (B) is present inside the crosslinked polymer particles (A) {that is, the composite particles (AB)}. For example, a measurement particle is cut with a microtome or the like, and a specific atom of a flocculant {for example, an aluminum salt (B1) with an electron beam microanalyzer {for example, EPMA, JXA-8621MX, manufactured by JEOL Ltd.) on the cut surface. In the case of an aluminum atom, an iron atom in the case of an iron salt (B2), a copper atom in the case of a copper salt (B3), a sulfur atom in the case of a sulfite (B4), a sulfur atom in the case of a bisulfite (B5)} Can be confirmed. In the case of the low molecular weight organic compound (B6) and the polymer (B7), the cut surface is similarly subjected to microinfrared spectroscopy {for example, microscopic IR, AIM-8000 manufactured by Shimadzu Corporation), crosslinked polymer particles ( This can be confirmed by observing a specific reflection spectrum that does not exist in A).

The composite particles (AB) can be easily obtained by the following methods (1) and (2), for example.
(1) A water-containing resin is obtained by polymerizing water-soluble vinyl monomer (a1) and / or vinyl monomer (a2) which becomes water-soluble vinyl monomer (a1) by hydrolysis and internal cross-linking agent (a3) as essential constituent units. A method comprising a polymerization step; and a composite step of mixing the water-containing resin and the flocculant (B) to obtain composite particles (AB).

  In the polymerization step, a known method {Patent Document 1, JP 2003-225565 A, JP 2005-075982 A, JP 2005-186016 A, etc .; } It can superpose | polymerize similarly to.

  In the compounding step, the water-containing resin may be mixed with the flocculant as it is, but it is preferable to shred the water-containing resin from the viewpoint of mixing properties and the like. The shredding method is the same as a known method. The mixing of the water-containing resin and the flocculant (B) is not limited as long as it can be uniformly mixed, and a known method can be applied. After mixing the water-containing resin and the flocculant (B), the composite particles (AB) can be obtained by drying and grinding. In addition, before drying, it is preferable to shred in order to allow the viewpoint of drying efficiency and the like and the flocculant (B) to exist inside the crosslinked polymer particles (A). Known methods can be applied to the drying (including shredding) and pulverization methods. After pulverization, the particle size may be adjusted by a known method or the like.

(2) In the presence of the flocculant (B), the water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis and the internal cross-linking agent (a3) are essential. A method comprising a polymerization step of obtaining composite particles (AB) comprising a crosslinked polymer particle (A) and a flocculant (B) by polymerization as a constituent unit.
The polymerization is the same as the known method except that the flocculant (B) is present {after the polymerization, the shredding step, the drying step, the surface cross-linking step and / or the particle size adjustment step, etc. (in the order of each step) There is no limit.) }.

  The composite particles (AB) are preferably surface-crosslinked. By surface crosslinking, the absorption performance (especially the amount absorbed under load) is further improved. The surface crosslinking method is the same as a known method.

  The absorbent resin particles of the present invention are obtained by uniformly mixing the crosslinked polymer particles (A), the flocculant (B), and the water-insoluble inorganic porous fine particles (C). , Composite particles (AB) {all or part of the flocculant (B) is present inside the crosslinked polymer particles (A). } Is preferably mixed uniformly with the composite particles (AB) and the water-insoluble inorganic porous fine particles (C).

When mixing the crosslinked polymer particles (A), the flocculant (B), and the water-insoluble inorganic porous fine particles (C), or when mixing the composite particles (AB) and the water-insoluble inorganic porous fine particles (C). From the viewpoint of absorption performance and the like, the crosslinked polymer particles (A) or composite particles (AB) are preferably dried, more preferably 10% by weight or less, particularly preferably 8% by weight or less, most preferably Preferably, it is 5% by weight or less.
In addition, the moisture is when heated by an infrared moisture measuring device (for example, JE400 manufactured by KETT Co., Ltd .: 120 ± 5 ° C., 30 minutes, atmospheric humidity before heating 50 ± 10% RH, lamp specification 100V, 40W) Calculated from weight loss before and after heating.

In the mixing of the crosslinked polymer particles (A), the flocculant (B) and the water-insoluble inorganic porous fine particles (C), or in the mixing of the composite particles (AB) and the water-insoluble inorganic porous fine particles (C), the temperature ( C) is not particularly limited, but is preferably 10 to 130, more preferably 15 to 125, and particularly preferably 20 to 120.
The mixing apparatus may be an ordinary mixer, for example, a cylindrical mixer, a screw mixer, a screw extruder, a turbulator, a nauter mixer, a double-arm kneader, a fluid mixer, V Examples thereof include a mold mixer, a ribbon mixer, a fluid mixer, an airflow mixer, a rotary disk mixer, a conical blender, and a roll mixer.

The absorbent resin particles of the present invention can be applied to various absorbers by containing them together with fibers. Using such an absorbent body, an absorbent article having excellent absorption performance can be manufactured. The absorbent body and the absorbent article can be produced in the same manner as known methods.
Absorbent articles include sanitary products {paper diapers (children's disposable diapers and adult disposable diapers, etc.), napkins (sanitary napkins, etc.), vomit absorption etiquette bags, paper towels, pads (incontinence pads and surgical underpads) Etc.) and pet sheets (pet urine absorption sheets, heat insulation sheets, etc.)} and various household and industrial absorption sheets {freshness maintenance sheets, drip absorption sheets, paddy rice seedling sheets, concrete curing sheets and cables, etc. Running prevention sheet, etc.}. Among these, it is suitable for sanitary goods, and is most suitable for a paper diaper, a pad, and a napkin, especially a paper diaper and a napkin.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, parts indicate parts by weight and% indicates% by weight.

<Example 1>
Water-soluble vinyl monomer (a11) {acrylic acid} 81.8 parts (1.14 mole part), internal crosslinking agent (a31) {N, N′-methylenebisacrylamide} 0.3 part (0.002 mole part) In addition, while stirring and mixing 241 parts of deionized water, the temperature was maintained at 1 to 2 ° C., and nitrogen was introduced into the mixed solution so that the amount of dissolved oxygen in the mixed solution was 0.02 ppm or less. Subsequently, 1 part of a 1% aqueous hydrogen peroxide solution, 1.2 parts of a 0.2% ascorbic acid aqueous solution and 2.8 parts of a 2% 2,2′-azobisamidinopropane dihydrochloride aqueous solution are added to the mixture. Polymerization was started by mixing, and after the reaction temperature reached 70 ° C., polymerization was performed at a polymerization temperature of 75 ± 5 ° C. for about 8 hours to obtain a water-containing resin (gel).

This water-containing resin (gel) was chopped into 3-7 mm sizes with an internal mixer to obtain a chopped gel, and then 67.5 parts of a 48% sodium hydroxide aqueous solution was added to 325 parts of the chopped gel. Then, 72 equivalent% of the carboxyl group was neutralized (mixed with an internal mixer) to obtain a neutralized chopped gel. In addition, the neutralization degree of the neutralized chopped gel calculated from the acid value measured according to JIS K0113-1997 (using 0.1 N potassium hydroxide aqueous solution as a titrant, potentiometric titration method, inflection point method) Was 70.1 equivalent%.
To 350 parts of the neutralized chopped gel, 0.01 part of a flocculant (b1) {polyaluminum chloride manufactured by Taki Chemical Co., Ltd., PAC250A} was added and mixed uniformly with an internal mixer to obtain a composite gel.

Next, this mixed gel is laminated to a thickness of about 5 cm on a stainless steel tray having a length of 20 cm × width of 20 cm × height of 10 cm, having no top plate, and having a 4 mm mesh wire mesh on the bottom plate. It dried with the ventilation type | mold band dryer (made by Inoue Metal) on the conditions of (degreeC) and the wind speed of 2.0 m / s, and obtained the composite dry polymer.
The composite dried polymer was pulverized with a juicer mixer (National MX-X53, manufactured by Matsushita Electric Industrial Co., Ltd.) and adjusted to a particle size range of 150 to 710 μm using a sieve having openings of 150 and 710 μm. Spray 1 part of 1% water / methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water / methanol = 60/40) while spraying at high speed (made by Hosokawa Micron, high speed stirring turbulizer mixer: 2000 rpm). While being added and mixed, the mixture was allowed to stand at 140 ° C. for 30 minutes and subjected to heat crosslinking (surface crosslinking) to obtain composite particles (ab1).

100 parts of composite particles (ab1) and water-insoluble inorganic porous fine particles (c1) {conical blender containing 0.01 parts of silicon dioxide manufactured by Tokuyama Corporation, Toxeal, volume average particle diameter 2.5 μm, specific surface area 120 m ^{2 /} g} The mixture was uniformly mixed with {manufactured by Hosokawa Micron Corporation} to obtain the absorbent resin particles (1) of the present invention.

<Example 2>
Example except that the amount of the flocculant (b1) was changed from 0.001 part to 0.05 part and the amount of the water-insoluble inorganic fine particles (c1) was changed from 0.01 part to 0.05 part. In the same manner as in No. 1, absorbent resin particles (2) of the present invention were obtained.

<Example 3>
Example except that the amount of the flocculant (b1) was changed from 0.001 part to 0.1 part and the amount of the water-insoluble inorganic fine particles (c1) was changed from 0.01 part to 0.1 part. In the same manner as in No. 1, absorbent resin particles (3) of the present invention were obtained.

<Example 4>
Except that the amount of the flocculant (b1) was changed from 0.001 part to 5 parts and the amount of the water-insoluble inorganic fine particles (c1) was changed from 0.01 part to 1 part, the same as in Example 1. Thus, absorbent resin particles (4) of the present invention were obtained.

<Example 5>
Except that the amount of the flocculant (b1) was changed from 0.001 part to 8 parts and that the amount of the water-insoluble inorganic fine particles (c1) was changed from 0.01 part to 2 parts, the same as in Example 1. Thus, absorbent resin particles (5) of the present invention were obtained.

<Example 6>
Example 1 except that the amount of the flocculant (b1) was changed from 0.001 part to 10 parts and the amount of the water-insoluble inorganic fine particles (c1) was changed from 0.01 parts to 2.5 parts. Similarly, the absorbent resin particle (6) of this invention was obtained.

<Example 7>
The flocculant (b1) was changed to the flocculant (b2) {polyferric sulfate manufactured by Nankai Chemical Industry Co., Ltd.}, and the water-insoluble inorganic fine particles (c1) were changed to the water-insoluble inorganic fine particles (c2) {Aerosil 200, Japan Absorbent resin particles (7) of the present invention were obtained in the same manner as in Example 1 except that Aerosil Co., Ltd., volume average particle diameter 100 μm, specific surface area 12 m ² / g} was changed.

<Example 8>
Water-soluble vinyl monomer (a11) 81.8 parts (1.14 mole part), internal crosslinking agent (a32) {pentaerythritol triallyl ether} 0.15 part (0.00059 mole part), flocculant (b1) 0 While stirring and mixing 008 parts and 241 parts of deionized water, the temperature was maintained at 1 to 2 ° C., and nitrogen was introduced into the mixed solution, so that the amount of dissolved oxygen in the mixed solution was 0.02 ppm or less. . Subsequently, 1 part of a 1% aqueous hydrogen peroxide solution, 1.2 parts of a 0.2% ascorbic acid aqueous solution and 2.8 parts of a 2% 2,2′-azobisamidinopropane dihydrochloride aqueous solution are added to the mixture. Polymerization was started by mixing, and after the reaction temperature reached 70 ° C., polymerization was performed at a polymerization temperature of 75 ± 5 ° C. for about 8 hours to obtain a water-containing resin (gel).

 The absorbent of the present invention was obtained in the same manner as in Example 1 except that a neutralized chopped gel was obtained using this water-containing resin (gel), and the flocculant (b1) was not added to the neutralized chopped gel. Resin particles (8) were obtained.

<Example 9>
In the same manner as in Example 1, except that the amount of the internal cross-linking agent (a31) was changed from 0.3 part (0.002 mol part) to 2.74 parts (1.6 mol part), the absorption of the present invention. Resin particles (9) were obtained.

<Example 10>
The absorption of the present invention was the same as in Example 1, except that the amount of the internal crosslinking agent (a31) was changed from 0.3 part (0.002 mol part) to 0.0857 part (0.05 mol part). Resin particles (10) were obtained.

<Example 11>
The flocculant (b1) was changed to the flocculant (b3) {ferric chloride manufactured by Rasa Industrial Co., Ltd.}, and the water-insoluble inorganic fine particles (c1) were changed to the water-insoluble inorganic fine particles (c2) {Aerosil 200, Nippon Aerosil Co., Ltd. Absorbent resin particles (11) of the present invention were obtained in the same manner as in Example 1, except that the company changed to a volume average particle diameter of 100 μm and a specific surface area of 12 m ² / g}.

<Comparative Example 1>
Resin particles were obtained in the same manner as in Example 1 except that the flocculant (b1) and the water-insoluble inorganic fine particles (c1) were not used.
By adding 0.069 parts of a non-volatile water-soluble compound {monoethanolamine} (corresponding to 3.45% of the resin particles) to 2 parts of the resin particles and mixing them uniformly, the absorbent resin particles for comparison ( H1) was obtained.

<Comparative example 2>
Absorbent resin particles (H2) for comparison were obtained in the same manner as in Example 1 except that the flocculant (b1) and the water-insoluble inorganic fine particles (c1) were not used.

<Comparative Example 3>
Absorbent resin particles for comparison in the same manner as in Example 1 except that the amount of the flocculant (b1) was changed from 0.001 part to 5 parts and the water-insoluble inorganic fine particles (c1) were not used. (H3) was obtained.

<Comparative Example 4>
Absorbency for comparison in the same manner as in Example 1 except that the flocculant (b1) was not used and the amount of the water-insoluble inorganic fine particles (c1) was changed from 0.01 part to 0.1 part. Resin particles (H4) were obtained.

  For the absorbent resin particles (1) to (11) and (H1) to (H4), the absorption performance (water retention amount, absorption amount under pressure, blood absorption rate and blood absorption rate) is measured, and the measurement results are shown. It was shown in 1.

<Absorption rate of blood>
The absorption rate of blood was measured in the same manner as the measurement of the water retention amount except that 1000 ml of physiological saline was changed to 300 ml of horse blood (containing 3.8% citric acid; manufactured by Japan Ram Co., Ltd.).

<Blood absorption rate>
A 0.5 g sample is uniformly spread over the petri dish with a diameter of 60 mm, and 2.50 g of equine blood is dripped in the center in 2 seconds. The equine blood is absorbed by the sample and drops of equine blood from the sample surface. The time until disappearance was measured with the naked eye and used as the first blood absorption rate (seconds). After 10 minutes from the end of the first absorption rate measurement, again, 2.50 g of horse blood was dropped in the same manner, and the time until the horse blood droplet disappeared was measured. did.
In this measurement, the absence of liquid droplets means that no reflected light from the blood surface is recognized.

注１（含有量）；架橋重合体粒子（Ａ）の重量に基づく、含有量（重量％）

Note 1 (content); content (% by weight) based on the weight of the crosslinked polymer particles (A)

<Example 12>
100 parts of fluff pulp and 10 parts of the absorbent resin particles (1) obtained in Example 1 were mixed with an airflow mixing device {Pad Former manufactured by Autech Co., Ltd.} to obtain a mixture. This mixture is uniformly laminated on water-absorbing paper (basis weight 15.5 g / m ² , manufactured by Advantech, filter paper No. 2, 14 cm × 6 cm) so that the basis weight is about 1.3 g / cm ^2, and 5 kg After pressing at a pressure of / cm ² for 30 seconds, it was cut into a 14 cm × 36 cm rectangle and covered with water-absorbing paper to prepare an absorbent body.
And 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 20.0 g / m ² : Eltas guard manufactured by Asahi Kasei Co., Ltd.) on the surface of the absorbent, the absorbent article. (1) obtained {2 sets were made. }.

<Examples 13 to 22>
An absorbent body was prepared in the same manner as in Example 12 except that the “absorbent resin particles (1)” was changed to “any of the absorbent resin particles (2) to (11)”. Articles (2) to (11) were created {two sets were created respectively. }.

<Comparative Examples 5-8>
An absorbent body was prepared in the same manner as in Example 12 except that the “absorbent resin particles (1)” was changed to “any of the absorbent resin particles (H1) to (H4)”. Articles (H1) to (H4) were created {two sets were created respectively. }.

  With respect to the absorbent articles (1) to (11) and (H1) to (H4), the surface dryness and surface dry feeling by SDME were measured, and the measurement results are shown in Table 2.

<Surface dryness value by SDME method>
A detector of an SDME (Surface Dryness Measurement Equipment) tester (manufactured by WK system) was immersed in a sufficiently wet measurement sample {horse blood covering the measurement sample, and left for 60 minutes to prepare. }, A 0% dryness value was set, and then the detector of the SDME tester was prepared by drying the measurement sample {measurement sample by heating at 80 ° C. for 2 hours. }, 100% dryness was set, and the SDME tester was calibrated.
Next, a metal ring (inner diameter 70 mm, outer diameter 80 mm length 50 mm, weight 300 g) is set in the center of the measurement sample, 80 ml of horse blood is injected, and the metal ring is removed immediately after the injection. The measurement was started with an SDME detector placed in the center. The value 5 minutes after the start of measurement was defined as the surface dryness value by SDME.

<Dry surface>
Ten panelists evaluated the surface of the measurement sample after measuring the surface dryness by the SDME method according to the following criteria. The arithmetic average value of 10 people was defined as the surface dry feeling.
3: No moisture at all (no discomfort)
2: Slight feeling (slight discomfort)
1: State of getting wet after getting wet

The absorbent performance of the absorbent resin particles of the present invention (water retention amount, absorbed amount under pressure, blood absorption rate and blood absorption rate) was significantly superior to the comparative absorbent resin particles.
Moreover, the surface dryness and surface dry feeling by SDME of the absorbent article using the absorbent resin particles of the present invention were remarkably superior to the comparative absorbent article.

Claims (8)

Water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) that becomes water-soluble vinyl monomer (a1) by hydrolysis, and crosslinked polymer particles (A) having an internal crosslinking agent (a3) as essential constituent units ), An aggregating agent (B), and water-insoluble inorganic porous fine particles (C). The absorbent resin particle according to claim 1, wherein the water retention amount is 35 to 50 g / g, and the absorption amount under load is 18 to 25 g / g. The absorptive resin particles according to claim 1 or 2, wherein all or part of the flocculant (B) is present inside the crosslinked polymer particles (A). Based on the weight of the crosslinked polymer particles (A), the content of the flocculant (B) is 0.001 to 10% by weight, and the content of the water-insoluble inorganic porous fine particles (C) is 0.01 to 2.5. The absorbent resin particle according to any one of claims 1 to 3, which is in wt%. The absorber formed by containing the absorbent resin particle and fiber in any one of Claims 1-4. An absorbent article comprising the absorbent body according to claim 5. Water-containing crosslinked polymer obtained by polymerizing water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) which becomes water-soluble vinyl monomer (a1) by hydrolysis and internal crosslinking agent (a3) as essential constituent units A polymerization step to obtain (A ′);
A compounding step of mixing the water-containing crosslinked polymer (A ′) and the flocculant (B) to obtain composite particles (AB); and mixing the composite particles (AB) and the water-insoluble inorganic porous fine particles (C). And a mixing step for obtaining the absorbent resin particles. Based on the weight of the crosslinked polymer particles (A), the amount of the flocculant (B) used is 0.001 to 10% by weight, and the amount of the water-insoluble inorganic porous fine particles (C) used is 0.01 to 2.5. The production method according to claim 7, wherein the production method is wt%.