JP2005095759A - Absorbent and absorbing article comprising the absorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent improved both in absorption scale factor and absorption rate of to-be-absorbed aqueous liquid (particularly blood, etc.). <P>SOLUTION: The absorbent is composed of a mixture comprising a crosslinked polymeric particle (S) comprising a (meth)acrylic acid (salt) as a principal component, a surface modifier (A) having surface tension of 40-80 dyn/cm, and a water-insoluble particle (B) having a volume mean particle diameter of 1-500 nm. As (A), a water-soluble polymer is preferable, and polyoxyalkylene glycol is further preferable. As (B), amorphous silicon oxide is preferable. Based on the weight of (S), (A), and (B), contents of (S), (A), and (B) are preferable to be respectively 99.9-98 wt.%, 0.001-1 wt.%, and 0.01-1.2 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an absorbent and an absorbent article using the same.

The higher the water-absorbing capacity of the water-absorbent resin, the stronger the affinity with the water-absorbed liquid (especially blood, etc.). There has been a problem that uniform penetration of liquid (particularly blood) into the water-absorbent resin particles is prevented (this phenomenon is called gel blocking). In addition, the solid content contained in the water-absorbed liquid (particularly blood) adheres to the surface of the water-absorbent resin particles, thereby preventing uniform penetration of the aqueous liquid-absorbed liquid (particularly blood) into the water-absorbent resin particles. There is a problem that the liquid permeability is lowered, and as a result, the absorption rate and the absorption amount of the water-absorbing liquid particles (particularly blood, etc.) to the water-absorbing resin particles themselves or the absorbent body containing the water-absorbing resin particles are reduced. . In order to improve these problems, for example, the following water absorbent resin particles have been proposed.
1. Water-absorbent resin particles obtained by mixing fine powdery hydrophobic silica having a volume average particle diameter of 0.05 microns or less and a specific surface area of 50 m ² / g or more (Patent Document 1).
2. Water-absorbent resin particles obtained by adding inorganic powder such as hydrous silicon dioxide (white carbon, kaolin, clay, etc.), hydrous aluminum, hydrous titanium, etc. (Patent Document 2).
3. Water-absorbent resin particles obtained by mixing stearic acid and inorganic powder and coating the surface with stearic acid (Patent Document 3).
4). Water-absorbent resin particles obtained by treating the surface of resin particles with organopolysiloxane to make them hydrophobic (Patent Document 4).
5). Water-absorbent resin particles whose surface is treated with polyoxyalkylene glycol (Patent Document 5).

JP-A-56-1333028 JP 59-80459 A JP-A-63-105064 Japanese Patent No. 3169133 Japanese Patent Laid-Open No. 3-184891

  However, although the water-absorbing resin particles 1 to 4 suppress the gel blocking between the particles and improve the amount of absorption, the surface of the water-absorbing resin particles becomes hydrophobic, so that the water-absorbing liquid (particularly blood, etc.) Absorption rate tends to decrease. On the other hand, the surface of the water-absorbing resin particles 5 is hydrophilic and the absorption rate is improved, but gel blocking between the particles tends to occur, and the absorbed amount of the liquid to be absorbed decreases. Thus, water-absorbing resin particles having a good absorption rate and absorption amount of an aqueous liquid to be absorbed (particularly blood and the like) are not known. In particular, when the aqueous liquid to be absorbed contains blood, the viscosity is high and ions and the like are contained in a high concentration. Therefore, it has been extremely difficult to balance the absorption amount and the absorption rate of the aqueous liquid to be absorbed containing blood. That is, an object of the present invention is to provide an absorbent that is excellent in both absorption capacity and absorption speed of an aqueous liquid to be absorbed (particularly blood or the like).

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that specific absorbents including crosslinked polymer particles, surface modifiers and water-insoluble particles are excellent in absorption rate and absorption amount. The present invention has been reached. That is, the absorbent of the present invention is characterized by the cross-linked polymer particles (S) having (meth) acrylic acid (salt) as the main constituent unit, and the surface modifier (A) having a surface tension of 40 to 80 dynes / cm. ) And a mixture of water-insoluble particles (B) having a volume average particle diameter of 1 to 500 nm.

  The absorbent of the present invention is excellent in the balance between the absorption capacity and the absorption rate of an aqueous liquid to be absorbed (particularly blood or the like), which has been a problem for water absorbent resins, and exhibits excellent performance. In particular, the blood absorption performance and the water absorption rate are remarkably excellent, so that they are optimal as a blood absorbent.

  (Meth) acrylic acid (salt) means acrylic acid, methacrylic acid, acrylate or methacrylate. As the acrylate and methacrylate, alkali metal (such as lithium, potassium and sodium) salts, alkaline earth metal (such as magnesium and calcium) salts and ammonium salts of acrylic acid or methacrylic acid are used. Of these, alkali metal salts are preferable, sodium salts, lithium salts and potassium salts are more preferable, sodium salts and lithium salts are particularly preferable, and sodium salts are most preferable.

  If the crosslinkable polymer particle (S) has (meth) acrylic acid (salt) as a main structural unit, it is possible to copolymerize other copolymerized vinyl monomers copolymerizable with (meth) acrylic acid (salt). Can be polymerized. Other copolymerized vinyl monomers include nonionic copolymerized vinyl monomer (i) and crosslinkable vinyl monomer (ii).

  Nonionic copolymerized vinyl monomer (i) includes (i-1) a hydroxyl group-containing vinyl monomer, (i-2) a vinyl monomer having a carbamoyl group or a mono- or di-alkyl carbamoyl group, and (i-3) Vinyl monomers having an epoxy group or an isocyanato group are included.

(I-1) As a hydroxyl group-containing vinyl monomer, a C3-C6 monoethylenically unsaturated alcohol {(meth) allyl alcohol, hexene alcohol, (meth) propenyl alcohol, etc.}, 2-6 valences or higher Monoethylenically unsaturated carboxylic acid of polyol {C2-C20 alkylene glycol, glycerin, diglycerin, tetraglycerin, trimethylolpropane, polyoxyalkylene (C2-C4) glycol (molecular weight 106-2000), etc.} Ester or monoethylenically unsaturated ether {hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, triethylene glycol (meth) acrylate, glycerin mono (meth) acrylate, trimethylolpropane mono (meth) acrylate And poly (oxyethylene / oxypropylene) (random and / or block) glycol mono (meth) allyl ether, etc.], and alkoxy having 1 to 3 carbon atoms (methoxy, ethoxy, i-propoxy, etc.) Or modified with acyloxy having 2 or 3 carbon atoms (acetyloxy and propionyloxy) can also be used.

(I-2) As a vinyl monomer having a carbamoyl group, a mono- or di-alkyl carbamoyl group, (meth) acrylamide, N-alkyl (1 to 8 carbon atoms) (meth) acrylamide (N-methylacrylamide and N -Hexyl (meth) acrylamide, etc.) and N, N-dialkyl (C1-C8) acrylamide (N, N-dimethylacrylamide and N, N-di-n- or i-propylacrylamide, etc.) Moreover, N-hydroxyalkyl (C1-C8) (meth) acrylamide {N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc.}, N, N-dihydroxyalkyl (C1-C8) (Meth) acrylamide {N, N-dihydroxyethyl (meth) acrylamide etc. And vinyl lactams {N- vinylpyrrolidone} and the like can be used.

(I-3) Examples of the vinyl monomer having an epoxy group or an isocyanato group include glycidyl (meth) acrylate, (meth) acryloyl isocyanate and (meth) acryloylethyl isocyanate.

  These nonionic copolymerized vinyl monomers may be used alone or in combination of two or more. Of these nonionic copolymerized vinyl monomers (i), a hydroxyl group-containing vinyl monomer is preferable, monoethylenically unsaturated carboxylic acid ester is more preferable, and hydroxyethyl (meth) acrylate is particularly preferable.

When the nonionic copolymerized vinyl monomer (i) is used, the content (% by weight) of the nonionic copolymerized vinyl monomer unit is 0.001 based on the weight of the (meth) acrylic acid (salt) unit. -20 is preferable, more preferably 0.04 to 2, particularly preferably 0.06 to 1, and most preferably 0.08 to 0.1.
That is, in this case, the upper limit of the content (% by weight) of the nonionic copolymerized vinyl monomer unit is preferably 20, more preferably 2, particularly preferably based on the weight of the (meth) acrylic acid (salt) unit. Is 1, and most preferably 0.1. Similarly, the lower limit is preferably 0.001, more preferably 0.04, particularly preferably 0.06, and most preferably 0.08. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  The crosslinkable vinyl monomer (ii) includes a crosslinkable vinyl monomer having 2 to 4 radical polymerizable groups selected from the group consisting of (meth) acryloyl group, vinyloxy group, allyloxy group and allyl group, Monomers having a (meth) acryloyl group {N, N′-methylenebis (meth) acrylamide, N, N′-ethylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, polyoxyethylene glycol (weight average molecular weight 200 to 4000 ) Di (meth) acrylate, propylene glycol di (meth) acrylate, glycerin di- or tri- (meth) acrylate, trimethylolpropane di- or tri- (meth) acrylate, pentaerythritol di- and tri- or tetra- ( (Meth) acrylate, etc. , Monomers having a vinyloxy group {vinyloxyethyl vinyl ether and vinyloxyhexyl vinyl ether and the like}, monomers having an allyloxy group {tetraallyloxyethane and pentaerythritol allyl ether, etc.} and monomers having an allyl group {di- or tri-allylamine, Triallyl cyanurate and triallyl isocyanurate etc.} Monomers {2-vinyloxyethyl (meth) acrylate and 2-allyloxyethyl (meth) acrylate etc.} containing two or more different groups are used.

  These crosslinkable vinyl monomers (ii) may be used alone or in combination of two or more. Among these crosslinkable vinyl monomers (ii), a monomer having a (meth) acryloyl group, a monomer having an allyloxy group, and a monomer having an allyl group are preferable, and N, N′-methylenebis (meth) acrylamide, ethylene is more preferable. Glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, glycerin di- or tri- (meth) acrylate, trimethylolpropane di- or trie (meth) acrylate, di- or tri Allylamine, triallyl cyanurello, triallyl isocyanurate, tetraallyloxyethane and pentaerythritol allyl ether, particularly preferably N, N′-methylenebis (meth) acrylamide, ethylene glycol Ruji - or tri - (meth) acrylate, trimethylolpropane di - or tri - (meth) acrylate, tetraallyloxyethane, pentaerythritol allyl ether and triallyl amine.

  When the crosslinkable vinyl monomer (ii) is used, the content (% by weight) of the crosslinkable vinyl monomer unit is based on the weight of the (meth) acrylic acid (salt) unit and the nonionic copolymerized vinyl monomer unit. 0.001-10 is preferable, More preferably, it is 0.005-5, Most preferably, it is 0.007-2, Most preferably, it is 0.01-1. That is, in this case, the upper limit of the content (% by weight) of the crosslinkable vinyl monomer unit is preferably 10, more preferably 5, particularly preferably 2, and most preferably 1 based on the weight of the vinyl monomer unit. Similarly, the lower limit is preferably 0.001, more preferably 0.005, particularly preferably 0.007, and most preferably 0.01. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  The crosslinked polymer particles (S) are obtained by (1) aqueous radical polymerization (adiabatic polymerization, thin film polymerization, spray polymerization, etc.) described in JP-A-55-133413 and (2) JP-B-54-30710. And can be produced by a known method such as reverse phase suspension radical polymerization described in JP-A-56-26909 or JP-A-1-5808.

  In the case of aqueous solution polymerization, the amount of water used (% by weight) is based on the total weight of the aqueous polymer solution from the viewpoints of industrial productivity, absorption capacity and absorption rate of the water-absorbed liquid (particularly blood) of the absorbent 55 to 80 is preferable, 60 to 77 is more preferable, and 65 to 75 is particularly preferable. That is, in this case, the upper limit of the amount of water used (% by weight) is preferably 80, more preferably 77, particularly preferably 75 based on the total weight of the polymerization aqueous solution, and similarly the lower limit is 55. More preferred is 60, and particularly preferred is 65. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  In the aqueous solution polymerization, a water-soluble organic solvent may coexist if necessary. Examples of the water-soluble organic solvent include alcohols having 1 to 4 carbon atoms (such as methanol, ethanol, isopropyl alcohol, ethylene glycol, and diethylene glycol). When a water-soluble organic solvent is used, the upper limit of the amount used (% by weight) is preferably 40 based on the weight of water, more preferably 30, and similarly, the lower limit is preferably 1, more preferably. 5. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  A polymerization initiator can be used for the aqueous solution polymerization. As the polymerization initiator, conventionally known polymerization initiators and the like can be used, and azo initiators, peroxide initiators, redox initiators, organic halogen initiators, and the like. included. Examples of the azo initiator include azobisisobutyronitrile, azobiscyanovaleric acid and salts thereof, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2′-azobis (2-methyl-N- ( 2-hydroxyethyl) propionamide, etc. As peroxide initiators, inorganic peroxides {hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.} and organic peroxides {benzoyl peroxide) , Di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide, di (2-ethoxyethyl) peroxydicarbonate, etc.} Examples of redox initiators include alkali metal sulfites or heavy metals. Sulfite, ammonium sulfite, ammonium bisulfite, ferric chloride, ferric sulfate or Examples thereof include a combination of a reducing agent such as ascorbic acid and an oxidizing agent such as an alkali metal persulfate, ammonium persulfate, hydrogen peroxide, or an organic peroxide. 15 and organic halides having 1 to 10 halogen atoms can be used. Alkyl halides (dichloromethane, trichloromethane, tetrachloromethane, trichlorobromomethane, trichloroiodomethane, etc.), halogenated alkylphenyl ketones (monochloromethylphenyl ketone) , Dichloromethylphenylketone and trichlorophenylketone), halogenated alkylcarboxylic acids (1-chloro-1-methylethylcarboxylic acid, 1-bromo-1-methylethylcarboxylic acid, 1-bromo-1-methylethylcarboxylic acid) , 2-bromo-1-me Ruethylcarboxylic acid and 2-chloro-1-methylethylcarboxylic acid), and halogenated alkylcarboxylic acid alkyl esters (methyl 1-bromo-1-methylethylcarboxylate, ethyl 1-bromo-1-methylethylcarboxylate) Octyl 1-bromo-1-methylethylcarboxylate, lauryl 1-bromo-1-methylethylcarboxylate, methyl 1-chloro-1-methylethylcarboxylate, ethyl 1-chloro-1-methylethylcarboxylate, 1 -Octyl-chloro-1-methylethylcarboxylate and lauryl 1-chloro-1-methylethylcarboxylate).

  These polymerization initiators may be used alone or in combination of two or more thereof. When azo initiators, peroxide initiators, redox initiators are used, the amount used (% by weight) is 0 based on the weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers. .0005 to 1 is preferable, and 0.01 to 0.5 is more preferable. That is, in this case, the upper limit of the amount (% by weight) of the polymerization initiator used is preferably 1, more preferably 0.5 based on the weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers. Similarly, the lower limit is preferably 0.0005, and more preferably 0.01. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  When an organic halogen initiator is used, the amount used (% by weight) is preferably 0.0005 to 10, more preferably, based on the weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers. Is 0.001 to 5, particularly preferably 0.005 to 3. That is, in this case, the upper limit of the amount (% by weight) of the polymerization initiator used is preferably 10 based on the weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers, more preferably 5, particularly Preferably, it is 3, and similarly, the lower limit is preferably 0.0005, more preferably 0.001, and particularly preferably 0.005. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  In aqueous solution polymerization, a conventionally known chain transfer agent may be used in combination, and examples thereof include thiol (such as n-lauryl mercaptan, mercaptoethanol, mercaptopropanol, and triethylene glycol dimercaptan), thiocarboxylic acid (thio). Glycolic acid and thiomalic acid), secondary alcohols (isopropanol etc.), amines (dibutylamine etc.) and hypophosphites (sodium hypophosphite etc.). When a chain transfer agent is used, the amount used (% by weight) is preferably 0.001-1 based on the weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers.

The polymerization temperature (° C.) of the aqueous solution polymerization is not particularly limited and can be variously changed depending on the type of the catalyst to be used, but is preferably 0 to 100, and more preferably 5 to 80. That is, the upper limit of the polymerization temperature (° C.) is preferably 100, more preferably 80, and similarly, the lower limit is preferably 0, and more preferably 5. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.
Moreover, a heavy metal catalyst can be used as a co-catalyst at the time of superposition | polymerization, As such a thing, the metal catalyst etc. which are described in WO01 / 79314 pamphlet or WO02 / 005949 pamphlet can be used.

  The crosslinked polymer particles (S) can be subjected to a surface crosslinking treatment with a surface crosslinking agent, if necessary. In the case of performing the surface crosslinking treatment, the polymer before the surface crosslinking treatment is referred to as a polymer particle before surface crosslinking (S ′) in order to distinguish from the crosslinked polymer particles (S) after the surface crosslinking treatment. Similarly, a water-containing resin (WA) composed of the crosslinked polymer particles (S) (after the surface cross-linking treatment) and a water-containing resin (WA ′) composed of the pre-surface cross-linked polymer particles (S ′) are distinguished. The crosslinked polymer particles (S) used in the present invention include both the crosslinked polymer particles (S) after the surface crosslinking treatment and the polymer particles (S ′) before the surface crosslinking. The water-containing resin (WA) includes both the water-containing resin (WA ′) after surface crosslinking and the water-containing resin (WA) before surface crosslinking.

  Examples of the surface cross-linking agent include polyhydric glycidyl described in JP-A-59-189103, polyhydric alcohol, polyhydric amine described in JP-A-58-180233, JP-A-61-16903, and the like. , Polyaziridines and polyisocyanates, silane coupling agents described in JP-A-61-211305 or JP-A-61-225212, and JP-A-51-136588 or JP-A-61. And polyvalent metals described in JP-A-257235. Of these surface cross-linking agents, polyvalent glycidyl, polyvalent polyhydric acid, polyhydric glycidyl, polyvalent polyhydric acid, polyhydric glycidyl and polyvalent Amine and silane coupling agents are preferred, more preferably polyvalent glycidyl and silane coupling agents, and particularly preferably polyvalent glycidyl.

  In the case of surface cross-linking treatment, the amount (% by weight) of the surface cross-linking agent is not particularly limited since it can be variously changed depending on the type of surface cross-linking agent, the conditions for cross-linking, the target performance, etc. From the viewpoint of the absorption capacity and the absorption speed of the water-absorbed liquid (particularly blood, etc.), 0.001 to 1 is preferable based on the weight of the pre-crosslinked polymer particles (S ′), and more preferably 0. 005 to 0.8, particularly preferably 0.01 to 0.6. That is, in this case, the upper limit of the amount (% by weight) of the surface crosslinking agent used is preferably 1, more preferably 0.8, particularly preferably 0.8, based on the weight of the polymer (S ′) before surface crosslinking. Similarly, the lower limit is preferably 0.001, more preferably 0.005, and particularly preferably 0.01. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  The surface cross-linking treatment is performed at any stage before drying the water-containing resin (WA ′) containing the pre-surface cross-linking polymer particles (S ′) and water, during drying of (WA ′), and after drying of (WA). However, from the viewpoint of easy adjustment of the crosslinking conditions with respect to the target performance, the stage during (WA ′) drying or after (WA ′) drying is preferable. As a method for performing this surface cross-linking treatment, a conventionally known method can be applied. For example, a mixed solution composed of a surface cross-linking agent, water and an organic solvent can be used as a pre-surface cross-linked polymer particle (S ′) or water-containing resin (WA ′). And a method of heating reaction. The amount (% by weight) of water used at the time of the surface cross-linking treatment is such that the surface pre-cross-linked polymer particles are used from the viewpoint of appropriate penetration of the surface cross-linking agent into the surface pre-cross-linked polymer particles (S ′). Based on the weight of (S ′), 1 to 10 is preferable, 1.5 to 8 is more preferable, and 2 to 7 is particularly preferable.

  As the type of organic solvent used in the surface cross-linking treatment, a conventionally known water-soluble organic solvent can be used. The degree of penetration of the surface cross-linking agent into the polymer particles (S ′) before surface cross-linking, the surface cross-linking agent The water-soluble organic solvent mentioned above can be used considering the reactivity etc. of these. Such a solvent may be used independently and may use 2 or more types together. Although the usage-amount (weight%) of an organic solvent can be variously changed with the kind of solvent, 1-20 are preferable based on the weight of surface cross-linking prepolymer particle (S '), More preferably, 1- 15, particularly preferably 1-10. Moreover, the usage-amount (weight%) of the organic solvent with respect to water can be changed arbitrarily, Based on the weight of water, 20-80 are preferable, More preferably, it is 25-75, Most preferably, it is 30-70. .

  The reaction temperature (° C.) of the surface crosslinking treatment is preferably 80 to 200, more preferably 90 to 180, and particularly preferably 100 to 160. That is, the upper limit of the reaction temperature (° C.) of the surface crosslinking treatment is preferably 200, more preferably 180, particularly preferably 160, and similarly the lower limit is preferably 80, more preferably 90, particularly preferably 100. It is. The reaction time (minutes) of the surface cross-linking treatment can be changed depending on the reaction temperature, but is preferably 3 to 60, more preferably 4 to 50, and particularly preferably 5 to 40. That is, the upper limit of the reaction time (minutes) of the surface cross-linking treatment is preferably 60, more preferably 50, particularly preferably 40, and similarly the lower limit is preferably 3, more preferably 4, particularly preferably 5. It is. In addition, when the crosslinked polymer particles (S) obtained by surface crosslinking with a surface crosslinking agent or a water-containing resin (WA) comprising this and water are used for this, the same type of surface crosslinking agent or a different type of surface crosslinking agent is used. Additional surface crosslinking can also be applied with the agent.

  The water-containing resin (WA) thus obtained is crushed (minced) and dried, and further pulverized and / or adjusted in particle size as necessary to obtain the crosslinked polymer particles (S). As a drying method, a normal method can be applied, for example, a method of drying with hot air at a temperature of 80 to 230 ° C., a thin film drying method by using a drum dryer or the like heated to 100 to 230 ° C., (heating) decompression A drying method, a freeze drying method, a drying method using infrared rays, or the like can be applied. There is no particular limitation on the pulverization method, and a method using a hammer pulverizer, an impact pulverizer, a roll pulverizer, or a shet airflow pulverizer can be applied. The pulverized pulverized product is sieved as necessary to adjust the particle size. The shape of the crosslinked polymer particles (S) after pulverization is not particularly limited, and may be irregularly crushed (as-crushed), flake-like, pearl-like, rice-grained, granulated or kitchen-like. Can be mentioned.

  In the case of the reverse phase suspension radical polymerization method, suspension polymerization can be carried out by supplying a part of the polymerization aqueous solution into a hydrophobic organic solvent containing a dispersant as required. In addition, the content (% by weight) of water in the polymerization aqueous solution is based on the weight of the polymerization aqueous solution from the viewpoints of industrial productivity, absorption capacity and absorption rate of the water-absorbed liquid (particularly blood, etc.) of the absorbent. 55-90 are preferable, More preferably, it is 60-88, Most preferably, it is 65-85. That is, in this case, the upper limit of the water content (% by weight) is preferably 90, more preferably 88, particularly preferably 85 based on the weight of the polymerization aqueous solution, and similarly the lower limit is preferably 55. More preferably, it is 60, and particularly preferably 65. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  As the hydrophobic organic solvent, known organic solvents can be used as long as they are hardly soluble in water, and hydrocarbons having 5 to 18 carbon atoms (pentane, cyclohexane, normal hexane, normal heptane, toluene, xylene). And octadecane). The use amount (% by weight) of the hydrophobic organic solvent is preferably 10 to 90, more preferably 20 to 80, particularly preferably based on the total weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers. Is 30-60. That is, the upper limit of the amount (% by weight) of the hydrophobic organic solvent used is preferably 90, more preferably 80, particularly preferably based on the total weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers. Is 60, and similarly, the lower limit is preferably 10, more preferably 20, and particularly preferably 30.

  In the case of the reversed-phase suspension radical polymerization method, a known dispersant (for example, “the latest technology of water-soluble polymers” published in CMC publication in May 2000 or “surfactant application technique” in CMC publication in December 2002 issuance. (Dispersants, protective colloids and surfactants) can be used. When a dispersant is used, the amount of use (% by weight) of the dispersant is preferably 0.0001 to 1, more preferably based on the total weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers. Is 0.005 to 0.5, particularly preferably 0.01 to 0.3. That is, in this case, the upper limit of the amount of use (% by weight) of the dispersant is preferably 1, more preferably 0.5, based on the total weight of (meth) acrylic acid (salt) and other copolymerized vinyl monomers. Particularly preferably, it is 0.3, and similarly, the lower limit is preferably 0.0001, more preferably 0.005, and particularly preferably 0.01.

  In the case of the reverse phase suspension radical polymerization method, the same polymerization initiator and chain transfer agent as in the case of the aqueous solution radical polymerization method can be used. When using a polymerization initiator and a chain transfer agent, the amount of these used is the same as in the case of the water-soluble radical polymerization method, and the preferred range is also the same.

  In the case of the reverse phase suspension radical polymerization method, the polymerization temperature (° C.) is not particularly limited, and can be variously changed depending on the type of the polymerization initiator to be used, but is preferably 10 to 100, more preferably 30 to 80. . That is, the upper limit of the polymerization temperature (° C.) is preferably 100, more preferably 80, and similarly, the lower limit is preferably 10, more preferably 30.

  The size of the crosslinked polymer particles (S) is not particularly limited, but most of the crosslinked polymer particles (S) (90% by weight or more of the total weight, preferably 93% by weight or more, more preferably 95% by weight or more). ) Is preferably 37 to 1000, more preferably 53 to 840, and particularly preferably 105 to 840. That is, the upper limit of the particle diameter (μm) of most of the crosslinked polymer particles (S) is preferably 1000, more preferably 840, and similarly the lower limit is preferably 37, more preferably 53, particularly preferably. Is 105. Moreover, 200-700 are preferable and, as for the weight average particle diameter (micrometer) of crosslinked polymer particle (S), Most preferably, it is 250-600. That is, the upper limit of the weight average particle diameter (μm) of the crosslinked polymer particles (S) is preferably 700, particularly preferably 600, and similarly, the lower limit is preferably 200, particularly preferably 250. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  In the present invention, the weight average particle size is determined by using a low-tap test sieve shaker and a JIS standard sieve specified in JIS Z8801-1976, Perry's Chemical Engineers Handbook 6th Edition (MacGlow-Hill Book)・ Measured by the method described in Company, 1984, page 21). Moreover, a weight average particle diameter combines a JIS standard sieve from the top in order of 840 micrometers, 710 micrometers, 500 micrometers, 420 micrometers, 350 micrometers, 250 micrometers, 149 micrometers, and a saucer. About 50 g of measurement sample particles are put in the uppermost 840 μm sieve and infiltrated with a low tap test sieve shaker for 5 minutes. The weight of the measurement sample particles on each sieve and the pan is weighed, and the total is taken as 100% to determine the weight fraction of the particles on each sieve. This value is logarithmic probability paper {the horizontal axis is the sieve opening (particle diameter ), 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.

  The absorption rate (g / g) of the crosslinked polymer particles (S) with respect to physiological saline (0.9% by weight sodium chloride aqueous solution) is preferably 30 or more, more preferably 35 to 80, and particularly preferably 40 to 70. It is. That is, the upper limit of the absorption capacity (g / g) of the crosslinked polymer particles (S) with respect to physiological saline is preferably 80, particularly preferably 70, and similarly the lower limit is preferably 30, more preferably 35. Particularly preferred is 40. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

The absorption ratio (X) is measured at 25 ± 2 ° C. as follows. That is, 1.00 g of a sample adjusted to a particle size of 840 to 149 μm with a JIS standard sieve is weighed and put into a tea bag (20 cm long, 10 cm wide) made of a nylon net having an opening of 63 μm (JIS Z8801-1976). And soaked in 500 ml of physiological saline (0.9 wt% sodium chloride aqueous solution) for 30 minutes. Thereafter, the tea bag is taken out from the physiological saline, hung for 15 minutes and drained, the weight (h1) is measured, and the absorption capacity (g / g) is calculated from the following formula. (H2) is the weight of the tea bag measured by the same operation as described above when there is no measurement sample.

The absorption capacity (g / g) of the crosslinked polymer particles (S) under pressure (20 g / cm ² ) against physiological saline is preferably 15 or more, more preferably 20 to 70, and particularly preferably 25 to 60. . That is, the upper limit of the absorption capacity (g / g) of the crosslinked polymer particles (S) under pressure (20 g / cm ² ) against physiological saline is preferably 70, particularly preferably 60, and likewise the lower limit. 15 is preferable, 20 is more preferable, and 25 is particularly preferable. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

The absorption capacity under pressure (20 g / cm ² ) is measured at 25 ± 2 ° C. as follows. That is, a sample of 0.10 g was weighed in a cylindrical plastic tube (inner diameter: 30 mm, height: 60 mm) with a nylon mesh of 63 μm (JIS Z8801-1976) attached to the bottom, and the plastic tube was placed vertically on the nylon mesh. The sample is arranged so as to have a substantially uniform thickness, and a weight having an outer diameter of 29.5 mm × 22 mm is placed on the sample so that a load of 20 g / cm ² is obtained. Next, a plastic tube containing a sample and a weight is immersed vertically in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration: 0.9% by weight) with the nylon mesh side facing down and left standing. To do. After 60 minutes, the plastic tube containing the sample and the weight is weighed, and the weight of the sample absorbed by the physiological saline is calculated. A value 10 times the increased weight is taken as an absorption capacity (g / g) under pressure against physiological saline.

The content of the crosslinked polymer particles (S) is preferably 99.9 to 98 based on the total weight of the crosslinked polymer particles (S), the surface modifier (A) and the water-insoluble particles (B). It is preferably 99.5 to 98.5, particularly preferably 99.3 to 98.2, and most preferably 99 to 98.4. That is, the upper limit of the amount (% by weight) of the crosslinked polymer particles (S) used is preferably 99.9, more preferably 99.5, based on the total weight of (S), (A) and (B). Particularly preferred is 99.3, and most preferred is 99. Similarly, the lower limit is preferably 98, more preferably 98.5, particularly preferably 98.2, and most preferably 98.4. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  The surface tension (Dyne / cm) of the surface modifier (A) is preferably 40 to 80, more preferably 42 to 75, particularly preferably 45 to 70, and most preferably 50 to 65. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved. The surface tension is measured by the ring method {(25 ° C.), C. Hub, S. G. Mason, Colloid & Polymer Science, Vol. 253 (1974), page 566}.

The surface modifier (A) is for modifying the surface of the crosslinked polymer particles (S) by fixing (chemical bond) to the surface of the crosslinked polymer particles (S).
Examples of fixing (chemical bond) include hydrogen bonding and ionic bonding. Of these, hydrogen bonding is preferred.

  The surface modifier (A) preferably has a reactive group capable of chemically bonding to the crosslinked polymer particles (S), and not only those having one type of reactive group but also two or more types of reactive groups. You may have. When the reactive group capable of chemically bonding to the crosslinked polymer particles (S) is present, the surface modifier (A) can be stably present on the surface of the crosslinked polymer particles (S). It is easy to maintain the permeation effect between the gels when absorbing the absorbing liquid.

The reactive group includes a reactive group that can be chemically bonded by a hydrogen bond and / or an ionic bond.
Examples of the reactive group capable of chemically bonding with a hydrogen bond and / or an ionic bond include a nonionic group, a cationic group, and an anionic group. Nonionic groups include sulfo group (HO ₃ S—), phosphono group ((HO) ₂ OP—), hydroxyl group (—OH), oxyalkylene group (—OA—), amino group (—NH ₂ , —NRH). , —NR ₂ ), oxycarbonyl group (—COO—), aminocarbonyl group (—CONH—), oxycarbonylamino group (—NHCOO—) and the like. Examples of the cationic group include an ammonio group. The anionic groups, carboxylate groups ^(- OOC-), sulfonate groups ^(- O ₃ S-) and phosphonate groups ^((- O) ₂ OP-), and the like. Among these, a nonionic group and a cationic group are preferable, and a nonionic group is more preferable.
R in the parenthesis is an alkyl group having 1 to 30 carbon atoms (preferably 1 to 10, more preferably 1 to 5) (methyl, ethyl, i-propyl, t-butyl, pentyl, undecyl, octadel, eicosyl, etc. Represents an alkenyl group having 21 to 30 carbon atoms (such as vinyl, propenyl, butenyl, hexenyl and octadecenyl), an aryl group having 6 to 12 carbon atoms (such as phenyl, tolyl, xylyl and naphthalyl) or 7 to 12 carbon atoms. Or an alkenyl group (such as benzyl, phenylethyl and tolylethyl). OA represents an oxyalkylene group having 1 to 8 carbon atoms (oxymethylene, oxyethylene, oxypropylene, oxybutylene, oxyphenylethylene, etc.).

Of these reactive groups, reactive groups that can be chemically bonded by hydrogen bonds are preferred, more preferably sulfo groups, hydroxyl groups, oxyalkylene groups, and amino groups, particularly preferably hydroxyl groups, oxyalkylene groups, and amino groups, and more particularly Preferred are a hydroxyl group and an oxyalkylene group, and most preferred is an oxyalkylene group.

Examples of the surface modifier (A) include a surface modifier (A1) having a nonionic group, a surface modifier (A2) having an ammonio group as a cationic group, and a surface modifier (A3) having an anionic group. ) Is included. Of these, (A1) and (A2) are preferable, and (A1) is more preferable.

Examples of the surface modifier (A1) having a nonionic group include (A1-1) to (A1-9).
(A1-1) Surface modifier containing a sulfo group (HO ₃ S—): radical polymer of styrene sulfonic acid, radical polymer of allyl sulfonic acid, and the like.
(A1-2) Surface modifier containing phosphono group ((HO) ₂ OP-): radical polymer of allyl phosphate, and the like.
(A1-3) Surface modifier containing a hydroxyl group (—OH): polyvinyl alcohol (saponification rate: 99%) and the like.
(A1-4) Surface modifier containing an oxyalkylene group (—OA—): polyethylene glycol, polypropylene glycol, polytetraethylene glycol, polyoxyethyleneoxypropylene glycol, and the like.
(A1-5) Surface modifier containing an amino group (—NH ₂ , —NRH, —NR ₂ ): allylamine radical polymer, polyethylene polyamine, and the like.

(A1-6) Surface modifier containing an oxycarbonyl group (—COO—): a radical polymer of methyl (meth) acrylate, a polyester of diethylene glycol and terephthalic acid, and the like.
(A1-7) Surface modifier containing an aminocarbonyl group (—CONH—): (meth) acrylamide radical polymer, polyamide of ethylenediamine and terephthalic acid, and the like.
(A1-8) Surface modifier containing an oxycarbonylamino group (—NHCOO—): polyurethane of ethylene glycol and hexamethylene diisocyanate and the like.
(A1-9) Surface modifier containing two or more kinds of reactive groups: radical polymer of (meth) acrylamide di-t-butylsulfonic acid, sulfonic acid modified poval (acid value: 400), poly (oxy Ethylene) sulfonic acid, poly (oxyethylene) phosphonic acid, radical polymer of aminoethyl (meth) acrylate, radical polymer of 2-hydroxyethyl (meth) acrylate, anionic ring-opening polymer of glycidol, poly (oxyethylene) Ethylamine, bis (poly (oxyethylene)) ethylamine, tris (poly (oxyethylene)) ethylamine, and the like.

Among these surface modifiers (A1), (A1-1) a surface modifier containing a sulfo group, (A1-3) a surface modifier containing a hydroxyl group, and (A1-4) an oxyalkylene group. The surface modifier containing and the (A1-5) amino group-containing surface modifier are preferred, more preferably (A1-3), (A1-4) and (A1-5), particularly preferably (A1). -3) and (A1-5), most preferably (A1-5).

Examples of the surface modifier (A2) having a cationic group include a polymer having a quaternary ammonio group and a quaternary salt of polymethylene polyamine.
Examples of the polymer having a quaternary ammonio group include a polymer having a structure having a quaternary ammonio group-containing radical polymerizable monomer as an essential constituent unit. Then, another radical polymerizable monomer that can be copolymerized with the quaternary ammonio group-containing radical polymerizable monomer can be used as a constituent unit.

As the quaternary ammonio group-containing radical polymerizable monomer, an ammonium salt having 6 to 30 carbon atoms can be used, such as trimethylpropenyl ammonium salt (such as hydroxide salt), trimethylaminoethyl (meth) acrylate salt (such as chloride salt). Methyldiethylaminoethyl (meth) acrylate salts (such as methosulfate salts), trimethylaminoethyl (meth) acrylamide salts (such as chloride salts), and diethylbenzylaminoethyl (meth) acrylamide salts (such as chloride salts).

Although it does not specifically limit as another radically polymerizable monomer which can be copolymerized, (meth) acrylamide, N-alkyl (C1-C8) (meth) acrylamide (N-methylacrylamide etc.), N, N-dialkyl ( C1-C8) (meth) acrylamide (N, N-dimethylacrylamide and N, N-di-n- or i-propylacrylamide etc.) and N-hydroxyalkyl (C1-C8) (meth) acrylamide etc. Is mentioned.

The polymer having a quaternary ammonio group preferably has a weight average molecular weight of 200 to 1,000,000, more preferably 5,000 to 50,000, and particularly preferably 10,000 to 20,000. That is, the upper limit of the weight average molecular weight is preferably 1000000, more preferably 50000, particularly preferably 20000, and similarly the lower limit is preferably 500, more preferably 5000, particularly preferably 10,000. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

Examples of the quaternary salt of polymethylenepolyamine include N, N, N ′, N′-tetramethyltetramethylenediamine dihydrochloride.
Of these surface modifiers (A2), a polymer having a quaternary ammonio group is preferred, and a quaternary ammonio group using a trimethylpropenylammonium salt and / or trimethylaminoethyl (meth) acrylate salt is more preferred. It is a polymer having In addition, as a salt, a hydroxide salt, a chloride salt, etc. are contained.

As the surface modifier (A3) having an anionic group, a radical polymer of a radical polymerizable monomer having a carboxylate, a radical polymer of a radical polymerizable monomer having a sulfonate, and a radical of a radical polymerizable monomer having a phosphonate Polymers and the like are included.
Examples of the radical polymerizable monomer having a carboxylate include unsaturated monocarboxylates having 3 to 10 carbon atoms (such as (meth) acrylate, crotonate and cinnamate} and unsaturated dicarboxylic acids having 4 to 10 carbon atoms. Acid salts {maleic acid salts, fumarate salts, citraconic acid salts, itaconic acid salts, etc.} and the like.

Examples of the radically polymerizable monomer having a sulfonate include a vinyl sulfonate having 3 to 10 carbon atoms {(meth) allyl sulfonate, styrene sulfonate, α-methylstyrene sulfonate, etc.}, 5 to 10 carbon atoms. (Meth) acryloyloxyalkyl sulfonate {{(meth) acryloxypropane sulfonate, 2-hydroxy-3- (meth) acryloxypropane sulfonate and 2- (meth) acryloxyethane sulfonate}, etc.} And (meth) acryloylaminoalkylsulfonic acid salt having 5 to 10 carbon atoms {2- (meth) acryloylamino-2,2-dimethylethanesulfonic acid salt, 2- (meth) acrylamino-2-methylpropanesulfonic acid salt And 3- (meth) acrylamino-2-hydroxypropanesulfonate, etc.} It is below.

Examples of the radically polymerizable monomer having a phosphonate group include an alkyl (meth) acrylate having 5 to 10 carbon atoms (an alkyl having 2 to 6 carbon atoms) phosphonate {2-acryloyloxyethylphosphonate and the like}. . In addition, as a salt, alkali metal (potassium, sodium, etc.) salt, ammonium salt, etc. are contained.

  Of these surface modifiers (A3), a radical polymer of a radical polymerizable monomer having a carboxylate and a radical polymer of a radical polymerizable monomer having a sulfonate are preferable, and a radical polymerizable monomer having a carboxylate is more preferable. The radical polymer of (meth) acrylate is particularly preferable.

  The number (number) of reactive groups in the surface modifier (A1), (A2) or (A3) is preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3. When the number of reactive groups is within this range, (A) is more likely to be present on the surface of the crosslinked polymer particles (S) more stably and uniformly. As a result, the absorption capacity of the aqueous liquid to be absorbed (particularly blood, etc.) The absorption rate is further improved.

  The weight average molecular weight of the surface modifier (A1), (A2) or (A3) is preferably 200 to 100,000, more preferably 400 to 50,000, particularly preferably 800 to 10,000, and most preferably 1,000 to 6,000. That is, the upper limit of the weight average molecular weight of (A1) is preferably 100,000, more preferably 50,000, particularly preferably 10,000, most preferably 6,000. Similarly, the lower limit is preferably 200, more preferably 400, particularly Preferably it is 800, most preferably 1000. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

  The viscosity (mPa · s) at 25 ° C. of the surface modifier (A) is 10 to 2, from the viewpoint of uniform mixing with the crosslinked polymer particles (S) and permeability to the inside of (S). 000 is preferable, more preferably 15 to 1,500, and particularly preferably 20 to 1000. That is, the upper limit of the viscosity (mPa · s) at 25 ° C. of the surface modifier (A) is preferably 2,000, more preferably 1,500, particularly preferably 1000, and similarly the lower limit is 10 Is more preferable, 15 is more preferable, and 20 is particularly preferable. The viscosity is measured with a rotary viscometer (for example, a BM viscometer manufactured by Tokimec, rotation speed 6 rpm, rotor No. 4).

  These surface modifiers (A) can be used in combination of two or more. The surface modifier (A) can also be used in a form dissolved or emulsified in water or a volatile solvent. The volatile solvent preferably has a vapor pressure at 20 ° C. of 17.5 to 700 mmHg, more preferably 20 to 600 mmHg, and particularly preferably 30 to 500 mmHg. That is, the upper limit of the vapor pressure (mmHg) at 20 ° C. of the volatile solvent is preferably 700, more preferably 600, particularly preferably 500. Similarly, the lower limit is preferably 17.5, more preferably. Is 20, particularly preferably 30.

Volatile solvents include alcohols (such as methanol, ethanol and isopropyl alcohol), hydrocarbons (such as hexane, cyclohexane and toluene), ethers (such as diethyl ether and tetrahydrofuran), ketones (such as acetone and methyl ethyl ketone), and esters (such as ethyl acetate). Isopropyl acetate and diethyl carbonate). When water or a volatile solvent is used, the amount (% by weight) of these used is preferably 1 to 900, more preferably 5 to 700, and particularly preferably 10 based on the weight of the surface modifier (A). ~ 400. That is, in this case, the upper limit of the amount used (% by weight) is preferably 900, more preferably 700, particularly preferably 400 based on the weight of (A). More preferably, it is 5, particularly preferably 10. When water and a volatile solvent are used, the amount of water used (% by weight) is preferably from 50 to 98, more preferably from 60 to 95, particularly preferably from 70 to 90, based on the weight of water and the volatile solvent. It is. That is, in this case, the upper limit of the amount of water used (% by weight) is preferably 98, more preferably 95, particularly preferably 90, and similarly the lower limit is preferably 50, more preferably 60, particularly preferably. Is 70.

  The content (% by weight) of the surface modifier (A) is 0.001-1 based on the total weight of the crosslinked polymer particles (S), the surface modifier (A) and the water-insoluble particles (B). Is more preferably 0.005 to 0.9, particularly preferably 0.07 to 0.8, and most preferably 0.1 to 0.7. That is, the upper limit of the amount (% by weight) of the surface modifier (A) used is preferably 1 based on the total weight of (S), (A) and (B), more preferably 0.9, especially Preferably, it is 0.8, most preferably 0.7, and similarly, the lower limit is preferably 0.001, more preferably 0.005, particularly preferably 0.07, and most preferably 0.1. Within this range, the absorption performance (particularly blood retention amount) and absorption rate of the absorbent are further improved.

  The volume average particle diameter (nm) of the water-insoluble particles (B) is preferably 1 to 500, more preferably 3 to 100, particularly preferably 5 to 75, and most preferably 9 to 50. That is, the upper limit of the volume average particle diameter (nm) of (B) is preferably 500, more preferably 100, particularly preferably 75, and most preferably 50. Similarly, the lower limit is preferably 1, more preferably. Is 3, particularly preferably 5 and most preferably 9. The volume average particle diameter is measured with a particle size distribution measuring apparatus (for example, manufactured by Nikkiso Co., Ltd .: Microtrac UPA) using cyclohexane as a solvent. Within this range, the absorption capacity and absorption rate of the aqueous liquid to be absorbed (especially blood) of the absorbent are further improved.

The specific surface area (m ² / g) of the water-insoluble particles (B) is preferably 20 to 400, more preferably 30 to 350, and particularly preferably 40 to 300, from the viewpoint of improving the absorption rate. That is, the upper limit of the specific surface area (m ² / g) of the water-insoluble particles (B) is preferably 400, more preferably 350, particularly preferably 300, and similarly the lower limit is preferably 20, more preferably. 30, particularly preferably 40. Within this range, the absorption rate of the absorbent tends to be even better. The specific surface area is measured according to JIS Z8830: 2001 (nitrogen, 6.3.1 volume method, 7.2 multipoint method).

The material of the water-insoluble particles (B) is not particularly limited as long as it is insoluble in water and non-reactive with the cross-linked polymer particles (S), excluding metals, and may be either organic or inorganic. In addition, since a metal may decompose | disassemble a crosslinked polymer particle (S) by oxidation / reduction reaction of a metal when it contacts with a crosslinked polymer particle (S) and water, it is not preferable.
As the organic substance, (i) an organic substance composed of a hydrocarbon, (ii) an organic substance composed of carbon, hydrogen and oxygen atoms, (iii) an organic substance containing a nitrogen atom, and (iv) other organic substances can be used.

(I) Examples of the organic substance composed of hydrocarbon include polyethylene, polypropylene, polystyrene, poly-p-xylylene, polybutadiene, and the like having a weight average molecular weight of 10,000 to 150,000.
(Ii) Examples of organic substances composed of carbon, hydrogen and oxygen atoms include polyacrylate, polymethacrylate, polyvinyl acetate, polyvinyl ether, thermoplastic polyester, polycarbonate, polyphenylene oxide and polyepoxy having a weight average molecular weight of 10,000 to 150,000. Is mentioned.
(Iii) Examples of the organic substance containing a nitrogen atom include polyacrylonitrile, polyamide and thermoplastic polyurethane having a weight average molecular weight of 10,000 to 150,000.
(Iv) Examples of other organic substances include polyvinyl chloride, polyvinylidene chloride, fluororesin, and polysulfone having a weight average molecular weight of 10,000 to 150,000.
Of these, (i) is preferable, more preferably polystyrene, and particularly preferably polystyrene having a weight average molecular weight of 7 to 130,000.

  The melting temperature of the organic material is preferably equal to or higher than the drying temperature in order to prevent the organic material from melting when the water-containing resin (WA) or the water-containing resin (WA ′) is dried. Although it is a balance with drying temperature, 130-300 are preferable and, as for the melting temperature (degreeC) of organic substance, 150-250 are more preferable. That is, the upper limit of the melting temperature (° C.) is preferably 300, more preferably 250, and the lower limit is preferably 130, more preferably 150.

The inorganic substance may be any of a natural inorganic substance and a synthetic inorganic substance, oxides such as silicon oxide, aluminum oxide, iron oxide, titanium oxide, magnesium oxide and zirconium oxide, carbides such as silicon carbide and aluminum carbide, and nitriding Examples thereof include nitrides such as titanium and carbon nitride. These may be used in combination of two or more, or may be a composite of two or more (zeolite, talc, etc.).
Of these, inorganic substances are preferable, oxides are more preferable, and silicon oxide is particularly preferable. Among silicon oxides, amorphous silicon oxide is preferable.

  The pH of the 10% by weight aqueous solution of the water-insoluble particles (B) is not particularly limited. However, from the viewpoint that (B) is stably present as primary particles and it is difficult to form secondary aggregates. Is more preferable, 2.5 to 10 is more preferable, and 3 to 9 is particularly preferable. That is, the upper limit of the pH in the 10% by weight aqueous solution of (B) is preferably 11, more preferably 10, particularly preferably 9, and similarly, the lower limit is preferably 2, more preferably 2.5, particularly Preferably it is 3.

  The content (% by weight) of the water-insoluble particles (B) is preferably 0.01 to 1.2 based on the total weight of the crosslinked polymer particles (S), the surface modifiers (A) and (B). More preferably, it is 0.2 to 1.1, particularly preferably 0.3 to 1, and most preferably 0.4 to 0.9. That is, the upper limit of the content (% by weight) of (B) is preferably 1.2, more preferably 1.1, particularly preferably based on the total weight of (S), (A) and (B). 1, most preferably 0.9. Similarly, the lower limit is preferably 0.01, more preferably 0.2, particularly preferably 0.3, and most preferably 0.4. Within this range, the absorption rate of the absorbent is further improved, and at the same time, the mechanical strength of the crosslinked polymer particles (S) is further increased.

The absorbent of the present invention should contain the crosslinked polymer particles (S), the surface modifier (A) and the water-insoluble particles (B), but the (A) is in the vicinity of the surface of the crosslinked polymer particles (S). ) And (B) are preferably present, and after polymerization of the crosslinked polymer particles (S), it is desirable to mix the crosslinked polymer particles (S) with (A) and (B).
When the crosslinked polymer particles (S) are obtained by aqueous solution polymerization, the timing of mixing the surface modifiers (A) and (B) is not particularly limited, but during the polymerization step, immediately after the polymerization step, a water-containing resin (WA or WA ′) may be crushed (minced), immediately before the surface crosslinking treatment step, during the surface crosslinking treatment step, immediately after the surface crosslinking treatment step, and during the drying step. Among these, from the viewpoint of uniformly treating the particle surface of the crosslinked polymer particles (S), immediately after the polymerization step, during the crushing (mincing) step of the hydrous resin (WA or WA ′), immediately before the surface crosslinking treatment step, surface crosslinking In the treatment step, the step immediately after the surface cross-linking treatment step and the drying step are preferred, depending on the ease of bonding between the reactive group in the surface modifier (A) and the cross-linked polymer particles (S) and the water-insoluble particles (B). From the viewpoint of blocking prevention, etc., more preferably, immediately after the polymerization step, in the crushing (mincing) of the water-containing resin (WA or WA ′), during the surface crosslinking treatment step and immediately after the surface crosslinking treatment step, particularly preferably immediately after the surface crosslinking treatment step. is there.

  When the crosslinked polymer particles (S) are obtained by reverse phase suspension polymerization, the timing of mixing the surface modifier (A) and the water-insoluble particles (B) is not particularly limited, but during the polymerization process, immediately after the polymerization process. During the dehydration process (during the process of dehydrating to about 10% by weight of water), immediately after the dehydration process, during the process of separating the water-containing resin (WA or WA ′) obtained by polymerization and the organic solvent used for the polymerization, surface crosslinking Immediately before the treatment step, during the surface crosslinking treatment step, immediately after the surface crosslinking treatment step and during the drying step (step of drying to 10% by weight or less) and the like. Among these, from the viewpoint of uniformly treating the surface of the crosslinked polymer particles (S), immediately after the polymerization step, during the dehydration step, immediately after the dehydration step, the water-containing resin (WA or WA ′) obtained by the polymerization and the polymerization are used. The step of separating the used organic solvent, immediately before the surface cross-linking treatment step, during the surface cross-linking treatment step, immediately after the surface cross-linking treatment step and during the drying step are preferred, and the reactive group and the cross-linking weight in the surface modifier (A) are preferred. From the viewpoint of easy binding to the coalesced particles (S) and prevention of blocking by the water-insoluble particles (B), and the like, more preferably, immediately after the polymerization step, during the dehydration step, immediately after the dehydration step, and the water-containing resin (WA Or WA ′) and the organic solvent used for the polymerization, immediately before the surface crosslinking treatment step, during the surface crosslinking treatment step and immediately after the surface crosslinking treatment step, particularly preferably immediately after the surface crosslinking treatment step.

  The timing of mixing the surface modifier (A) and the water-insoluble particles (B) may be mixed at the same time, or after mixing the crosslinked polymer particles (S) and (A), mixing (B). Any method of mixing (S) and (B) and then mixing (A) can be applied. However, from the viewpoint of the absorption performance and absorption rate of the absorbent, (S) and (A The method of mixing this mixture with (B) after mixing is preferred.

  Crosslinked polymer particles (S or S ′), water-containing resin (WA or WA ′), (S or S ′) and water-insoluble particles (B) mixture (SB), or (WA or WA ′) and (B) As a method of mixing the mixture (WAB or WA′B) {hereinafter referred to as resin (WSB)} and the surface modifier (A), a part of (WSB) is used in advance (A) Is added to (WSB) at a high concentration (for example, 5 to 20% by weight with respect to (WSB)) at room temperature (20 to 30 ° C.), and mixed and stirred for 10 minutes or more to prepare a master batch. A method of adding the master batch to the remaining (WSB) at room temperature and mixing for 10 minutes or more, a method of adding (A) to (WSB) while stirring, or a method of mixing by spraying, and the like. It is not preferable to warm (heat) during mixing, and the mixing temperature (° C.) is preferably 15 to 30, more preferably 20 to 28, particularly preferably 22 to 26, and most preferably 23 to 25.

  The industrial apparatus for mixing the resin (WSB) and the surface modifier (A) is not particularly limited. For example, a conical blender, a nauter mixer, a double-arm kneader, a V-type mixer, a fluidized bed. A mechanical mixing device such as a mixer, a turbulizer, a screw type line blending device, a ribbon mixer and a mortar mixer is preferably used.

Crosslinked polymer particles (S or S ′), water-containing resin (WA or WA ′), (S or S) and surface modifier (A) mixture (SA), or (WA or WA ′) and (A) The method of mixing the mixture (WAA or WA′A) {hereinafter referred to as resin (WSA)} and the water-insoluble particles (B) is the same as the method of mixing (WSB) and (A). The method can be applied.
The water-insoluble particles (B) can be added in any form of powder, slurry, water dispersion or water-solubilized body. Although it does not specifically limit as a medium of a slurry, Water, methanol, ethanol, a cyclohexane, etc. are mentioned, The density | concentration of the water insoluble particle | grains in a slurry is 50 to 95 weight%. Moreover, the water-solubilized body shows a state where the particle diameter of (B) is apparently smaller than the wavelength of visible light and dissolved. Among these, from the viewpoint that (B) can be mixed in a single particle state, that is, in a non-aggregated state, an aqueous dispersion or a water-solubilized body is preferable.

  If necessary, an additive (C) can be added to the absorbent of the present invention. As the additive (C), antiseptics, fungicides, antibacterial agents, antioxidants, ultraviolet absorbers, colorants, fragrances, deodorants, inorganic powders, organic fibrous materials and the like can be used.

Examples of the preservative include preservatives such as salicylic acid, sorbic acid, dehydroacetic acid and methylnaphthoquinone, and bactericides such as chloramine B and nitrofurazone.
Antifungal agents include butyl p-oxybenzoate and the like, and antibacterial agents include benzalkonium chloride salt and chlorhexidine gluconate. Antioxidants include triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenylpropionate) and 3,5-di-tert-butyl-4-hydroxy Examples thereof include hindered phenol antioxidants such as benzyl phosphonate-diethyl ester, amine antioxidants such as n-butylamine, triethylamine and diethylaminomethyl methacrylate, and mixtures of two or more thereof.

Examples of the ultraviolet absorber include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di Benzotriazole-based ultraviolet absorbers such as -t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole and 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (4 , 6-Diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol and other triazine-based UV absorbers, and 2-hydroxy-4-n-octyloxybenzophenone and other benzophenones UV absorbers, oxalic anilide UV absorbers such as 2-ethoxy-2'-ethyloxalic acid bisanilide, and the like A mixture of two or more of the like.

Examples of the colorant include inorganic pigments such as carbon black, titanium oxide and ferrite, organic pigments such as azo lake, benzimidazolone and phthalocyanine, and dyes such as nigrosine and aniline. Examples of the fragrance include natural fragrances such as scent, abies oil and turpentine oil, and synthetic fragrances such as menthol, citral, p-methylacetophenone and floral.
Examples of the deodorant include zeolite, silica, flavonoid, cyclodextrin and the like.

Inorganic powders include calcium carbonate, kaolin, talc, mica, bentonite, clay, sericite, asbestos, glass fiber, carbon fiber, glass powder, glass balloon, shirasu balloon, coal powder, metal powder, ceramic powder, silica, zeolite And slate powder. The form of the inorganic powder may be arbitrary, and the volume average particle diameter determined by the light scattering method is preferably 0.1 μm to 1 mm. Organic fibers include natural fibers (cellulose (cotton, sawdust, straw, etc.), and other grass charcoal, wool, microfibrils, bacterial cellulose, etc.), artificial fibers (cellulosics such as rayon and acetate, etc.), synthetic fibers (Polyamide, polyester, acrylic, etc.), pulp [craft pulp (NKP, LKP, NBKP, LBKP), mechanical pulp (such as crushed wood pulp and asprund method ground wood pulp), chemical pulp (sulfite pulp, soda pulp, sulfate) Pulp, nitrate pulp, chlorine pulp, etc.), semi-chemical pulp, recycled pulp (mechanically crushed or pulverized paper made from pulp once, or recycled waste paper pulp that is mechanically crushed or pulverized waste paper) Etc.

  When the additive (C) is used, the amount (% by weight) of these additives varies depending on the application, but the total weight of the crosslinked polymer particles (S), the surface modifier (A) and the water-insoluble particles (B). Based on this, 0.01 to 20 is preferable, 0.02 to 10 is more preferable, and 0.03 to 8 is particularly preferable. That is, in this case, the upper limit of these addition amounts (% by weight) is preferably 20, more preferably 10, particularly preferably 8, based on the total weight of (S), (A) and (B). Similarly, the lower limit is preferably 0.01, more preferably 0.02, and particularly preferably 0.03.

When using an additive (C), it can add at arbitrary steps, The following 1-5 grade | etc., Etc. are mentioned.
1. A method in which the additive (C) is mixed with the crosslinked polymer particles (S) in advance.
2. A method in which (C) is mixed with the surface modifier (A) and / or the water-insoluble particles (B) and then mixed with (S).
3. A method of adding (C) while mixing (S) and (A) and / or (B).
4). A method of adding and mixing (C) after treating (S) with (A) and / or (B).
5). A method of mixing (A), (B), (S) and (C) simultaneously.
Among these methods, the methods 2, 3, and 4 are preferable, and the methods 3 and 4 are more preferable.

The absorption capacity (g / g) of the absorbent of the present invention with respect to physiological saline (0.9 wt% sodium chloride aqueous solution) is preferably 32 or more, more preferably 37 to 82, and particularly preferably 42 to 72. . That is, the upper limit of the absorption capacity (g / g) of the absorbent of the present invention with respect to physiological saline is preferably 82, particularly preferably 72, and similarly the lower limit is preferably 32, more preferably 37, particularly Preferably 42.
Further, the absorption capacity (g / g) under pressure (20 g / cm ² ) of the absorbent of the present invention against physiological saline is preferably 13 or more, more preferably 15 to 70, and particularly preferably 20 to 60. . That is, the upper limit of the absorption capacity (g / g) under pressure (20 g / cm ² ) of the absorbent of the present invention against physiological saline is preferably 70, particularly preferably 60, and similarly the lower limit is 13 Is more preferable, 15 is more preferable, and 20 is particularly preferable.

By applying the absorbent of the present invention to various absorbent bodies, an absorbent article excellent in absorption performance and absorption speed can be obtained.
As a method of applying the absorbent to the absorber, (1) a method in which the absorbent is granulated between layers of fibrous materials such as pulp arranged in layers; (2) pulp, heat-fusible fiber (3) A method of sandwiching the absorbent together with the fibrous material, if necessary, with two or more water-absorbing papers and nonwoven fabrics.

  Fibrous materials such as various fluff pulps and cotton-like pulps conventionally used in absorbent articles {raw materials (conifers and hardwoods, etc.), production methods [craft pulp, chemical pulp, semi-chemical pulp and Chemi-thermomechanical pulp (CTMP) etc.], bleaching method] etc. are not particularly limited. As the fibrous material, in addition to the organic fibrous material described above, a synthetic fiber that does not swell in water can be used alone or in combination with the above fluff pulp or cotton pulp, if necessary. Examples of synthetic fibers include polyolefin fibers (such as polyethylene fibers and polypropylene fibers), polyester fibers (such as polyethylene terephthalate fibers), polyolefin / polyester composite fibers, polyamide fibers, and polyacrylonitrile fibers.

The length and thickness of the fibrous material are not particularly limited. Usually, the length is preferably 1 to 200 mm, and the thickness is preferably 0.1 to 100 denier (0.11 to 110 dtex).
The shape is not particularly limited as long as it is fibrous, and examples thereof include a web shape, a thin cylindrical shape, a cut split yarn shape, a staple shape, and a filament shape.

  The amount (% by weight) of the absorbent of the present invention to the absorber can be variously changed according to the type and size of the absorber and the target absorption performance, but the total weight of the absorber and the fibrous material. Based on this, 30 to 95 is preferable, 40 to 94 is more preferable, and 50 to 93 is particularly preferable. Within this range, the absorption performance and absorption rate of the obtained absorbent body are further improved.

Since the absorbent of the present invention shows a light feel even when absorbing the liquid to be absorbed, when the absorbent of the present invention is applied to sanitary products such as disposable diapers and sanitary napkins, excellent absorbent performance In addition, it exhibits excellent characteristics that the liquid to be absorbed does not easily return even under pressure.
Therefore, by using the absorbent of the present invention, an absorbent article that exhibits high absorption performance in any state can be easily produced.
That is, even in a state where a load is applied such as when the user is sitting or lying down, the absorption performance and the absorption speed do not decrease, and as a result, problems such as leakage are extremely unlikely to occur.

  As an absorbent article, an absorbent article provided with an absorber, a liquid permeable sheet, and a breathable back sheet is preferable, and more preferably an absorbent article as a sanitary article.

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”. Further, the blood absorption rate and blood absorption rate were measured at 25 ± 2 ° C. by the following methods. Moreover, the measuring method of the absorption capacity | capacitance with respect to physiological saline and the absorption capacity under pressure with respect to physiological saline (20 g / cm < ² >) is the same as that of the above.

<Absorption rate of blood>
A tea bag (vertical 20 cm, horizontal 10 cm) made of 250 mesh (JIS Z8801-1976) nylon net is charged with 1.00 g of sample and 300 ml of horse blood (containing 3.8% citric acid; manufactured by Japan Lamb). The sample was dipped in for 60 minutes to absorb, then suspended for 15 minutes, drained, and then the increased weight of the tea bag containing the sample was measured to determine the blood absorption rate (g / g).

<Blood absorption rate>
A 0.50 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 a drop of equine blood drops from the surface of the sample. The time until disappearance was measured with the naked eye and was defined as the first blood absorption rate (seconds).
Ten minutes after the end of the first absorption rate measurement, 2.50 g of horse blood was dropped again, and the time until the horse blood droplet ceased was measured to obtain the second blood absorption rate (seconds).
In this measurement, the absence of droplets means that there is no blood flowing independently of the sample when the petri dish bottom surface is tilted 45 degrees with respect to the horizontal (the blood absorbed in the sample is If there is no blood flowing on the surface without being absorbed, it is judged that there is no droplet).

<Synthesis Example 1>
A reaction vessel was charged with 95 parts of sodium acrylate, 27 parts of acrylic acid, 0.3 part of N, N′-methylenebisacrylamide and 430 parts of deionized water, and the temperature of the contents was kept at 5 ° C. while stirring and mixing. . After the system was purged with nitrogen, 1 part of a 1% aqueous solution of hydrogen peroxide and 1 part of a 0.3% aqueous solution of ascorbic acid were added to initiate polymerization. Ten minutes after the addition of hydrogen peroxide and ascorbic acid, the temperature started to increase due to polymerization, and reached 40 ° C. 40 minutes after the temperature began to increase. Furthermore, it superposed | polymerized at 60 degreeC for 12 hours, and obtained the water-containing resin. This water-containing resin is crushed to a size of approximately 1 cm square, dried with hot air at 130 to 150 ° C. for 20 minutes, pulverized using a juicer mixer, and passed through a JIS standard sieve with an opening of 250 μm, and a JIS with an opening of 590 μm. By collecting particles passing through a standard sieve, resin particles of 250 to 590 μm were obtained. The moisture content of the resin particles measured with an infrared moisture meter (FD-100 type, manufactured by Kett, 180 ° C., 20 minutes) was 15%. While stirring 100 g of this resin particle at 50 rpm with a desktop kneader, 1 part of a 10% aqueous solution of ethylene glycol diglycidyl ether is sprayed, and the surface vicinity is crosslinked by heat treatment at about 140 ° C. for 30 minutes. Furthermore, the heat treatment was performed at about 140 ° C. to adjust the water content to 5% to obtain crosslinked polymer particles (S1). The weight average particle diameter of S1 was 380 μm, the absorption capacity with respect to physiological saline was 60 g / g, and the absorption capacity under pressure against physiological saline was 21 g / g.

<Synthesis Example 2>
145.4 parts of acrylic acid was diluted with 9.4 parts of water and neutralized by adding 242.3 parts of 25% aqueous sodium hydroxide while cooling to 30-20 ° C. 0.09 part of ethylene glycol diglycidyl ether (manufactured by Nagase Kasei Kogyo Co., Ltd., Denacol EX-810), 0.0146 part of sodium hypophosphite monohydrate and 0.0727 part of potassium persulfate are added to this solution. And dissolved in an aqueous monomer solution. Subsequently, 624 parts of cyclohexane was put into a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas introduction tube, and polyoxyethylene octylphenyl ether phosphate ester (Daiichi Kogyo Seiyaku Co., Ltd., trade name: (Blysurf A210G) 1.56 parts was added and dissolved, and then purged with nitrogen while stirring, and then heated to 70 ° C. Then, while maintaining the temperature at 70 ° C., the adjusted monomer aqueous solution was dropped at 6.6 parts / minute for 6 minutes and held at 75 ° C. for 15 minutes, and then the remaining monomer aqueous solution was added at 6.6 parts / minute for 54 minutes. It was dripped over. Thereafter, aging was performed at 75 ° C. for 30 minutes. Thereafter, water was removed by azeotropy with cyclohexane until the water content of the resin became about 20% (infrared moisture meter (FD-100 type, manufactured by Kett, measured at 180 ° C., 20 minutes). When the stirring was stopped after cooling, the resin particles settled, and the resin particles and cyclohexane were separated by decantation, and 80 parts of the resin particles and 140 parts of cyclohexane were put in a reaction vessel, and glycerin polyglycidyl ether ( Nagase Kasei Kogyo Co., Ltd., trade name: Denacol EX-314) After adding 3.4 parts of a cyclohexane solution containing 0.4%, the mixture was heated at 60 ° C. and held for 30 minutes, and further heated under reflux of cyclohexane. Next, the resin particles were obtained by filtration and dried under reduced pressure at 80 ° C. to obtain crosslinked polymer particles (S2). The average particle diameter is 360 .mu.m, absorption capacity for physiological saline absorption capacity under a load for 62 g / g, saline was 22 g / g.

<Example 1>
1. Colloidal aqueous solution of 100 parts of crosslinked polymer particles (S1) and spherical silicon oxide (Clevosol 30CAL25, 30% aqueous dispersion, pH 3.5, volume average particle size 25 nm, specific surface area 200 m ² / g manufactured by Clariant Japan KK) 6 parts were mixed and stirred (Hosokawa Micron high-speed stirring turbulizer: rotation speed 2000 rpm, feed rate 800 g / min), and further polyethylene glycol (PEG-1000, Sanyo Chemical Industries, Ltd., weight average molecular weight 1000, surface tension 65 dynes / 0.7 parts of (cm, viscosity 25 mPa · s) were mixed and stirred (high speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm, feed speed 800 g / min) to obtain the absorbent (1) of the present invention.

<Example 2>
Instead of Clariant Japan Co., Ltd., clebosol 30CAL251.6 parts, Clariant Japan Co., Ltd. clebosol 40CAL12 (40% aqueous dispersion, pH 9.0, volume average particle size 12 nm, specific surface area 200 m ² / g) for 1.25 Except for the above, an absorbent (2) was obtained in the same manner as in Example 1.

<Example 3>
The same procedure as in Example 1 was performed except that 0.5 part of Aerosil 200 (volume average particle diameter 12 nm, specific surface area 200 m ² / g) manufactured by Nippon Aerosil Co., Ltd. was used in place of 251.6 parts of Clevosol 30CAL manufactured by Clariant Japan Co., Ltd. Thus, an absorbent (3) was obtained.

<Example 4>
Except that 0.7 part of PEG-1000 was used, 0.1 part of PEG-6000 (manufactured by Sanyo Chemical Industries, Ltd., weight average molecular weight 6000, surface tension 65 dynes / cm, viscosity 45 mPa · s) was used. In the same manner as in Example 1, an absorbent (4) was obtained.

<Example 5>
The same procedure as in Example 1 was performed except that 5 parts of a 10% aqueous solution (viscosity: 100 mPa · s) of Kuraray Poval PVA505 (Kenka degree 73%, surface tension 56 dynes / cm) was used instead of 0.7 parts of PEG1000. Thus, an absorbent (5) was obtained.

<Example 6>
In place of 0.7 part of PEG1000, except that 1 part of 50% aqueous solution (viscosity 100 mPa · s) of Santellose 90L (water-soluble hydroxypropylcellulose, surface tension 55 dynes / cm) manufactured by Daido Kasei Kogyo Co., Ltd. was used. In the same manner as in Example 1, an absorbent (6) was obtained.

<Example 7>
An absorbent (7) was obtained in the same manner as in Example 1 except that the crosslinked polymer particles (S2) were used instead of the crosslinked polymer particles (S1).

<Example 8>
Other than using crosslinked polymer particle (S2) in place of crosslinked polymer particle (S1), 1.25 parts of Clariant Japan Co., Ltd. clebosol 40CAL12 in place of 1.6 parts of Clariant Japan Co., Ltd. Obtained an absorbent (8) in the same manner as in Example 1.

<Example 9>
Instead of the crosslinked polymer particles (S1), the crosslinked polymer particles (S2) are replaced with 1.6 parts of Clevosol 30CAL25 manufactured by Clariant Japan Co., Ltd. Aerosil 200 (volume average particle diameter 12 nm, specific surface area 200 m) manufactured by Nippon Aerosil Co., Ltd. ^The absorbent (9) was obtained in the same manner as in Example 1 except that 0.5 part of ² / g) was used.

<Example 10>
An absorbent (10) was obtained in the same manner as in Example 1 except that the crosslinked polymer particle (S2) was used instead of the crosslinked polymer particle (S1), and PEG-6000 was used instead of PEG-1000.

<Example 11>
The crosslinked polymer particle (S2) was replaced with the crosslinked polymer particle (S1), and the same procedure as in Example 1 was conducted except that 0.7 part of PEG 1000 was used and 5 parts of a 10% aqueous solution of Kuraray Poval 102 was used. Thus, an absorbent (11) was obtained.

<Example 12>
The cross-linked polymer particles (S2) were replaced with 0.7 parts of PEG1000 instead of the cross-linked polymer particles (S1), and 1 part of a 50% aqueous solution of Sanjirose 90L manufactured by Daido Kasei Kogyo Co., Ltd. was used. In the same manner as in Example 1, an absorbent (12) was obtained.

<Example 13>
Instead of 0.7 parts of PEG-1000, a trimethylammonioethyl acrylate / chloride-acrylamide copolymer (weight average molecular weight 15000, molar ratio of trimethylammonioethyl acrylate chloride to acrylamide 1: 1, surface tension 60 dynes / cm) An absorbent (13) was obtained in the same manner as in Example 1 except that 0.7 part was used.

<Example 14>
Absorbent (14) in the same manner as in Example 1 except that 0.7 part of polyacrylic acid (weight average molecular weight 1000, surface tension 65 dynes / cm) was used instead of 0.7 part of PEG-1000. Got.

<Comparative Examples 1 and 2>
The crosslinked polymer particles (S1) obtained in Synthesis Example 1 and the crosslinked polymer particles (S2) obtained in Synthesis Example 2 are used as they are in the absorbent (15) of Comparative Example (1) and the absorbent of Comparative Example (2). (16).

<Comparative Example 3>
Absorbent (17) was obtained in the same manner as in Example 1 except that Clevosol 30CAL25 manufactured by Clariant Japan Co., Ltd. was not added.

<Comparative example 4>
An absorbent (18) was obtained in the same manner as in Example 1 except that PEG1000 was not added.

For the absorbents (1) to (18), blood absorption rate, blood absorption rate, weight average particle diameter, absorption rate with respect to physiological saline and absorption rate under pressure with respect to physiological saline are evaluated. The results are shown in Table 1.

<Example 15>
A basis weight of about 1.3 g / cm was obtained by mixing 100 parts of fluff pulp and 10 parts of the absorbent (1) of the present invention obtained in Example 1 with an airflow type mixing device (manufactured by Autech, basic type). ² uniformly, pressed at a pressure of 5 Kg / cm ² for 30 seconds, then cut into a 14 cm × 6 cm rectangle, water-absorbing paper (14 cm × 6 cm) (Advantech, filter paper No. 2 ) After sandwiching the two sheets, a polyethylene sheet (14 cm × 6 cm, Tamapoly polyethylene film UB-1) is applied to one water absorbent paper, and a polyethylene non-woven fabric (14 cm × 6 cm, Asahi Kasei Eltguard) is absorbed to the other water. The absorbent body for napkin (1) was created by arranging on a paper.

<Examples 16 to 29>
Napkin absorbent bodies (2) to (15) were prepared in the same manner as in Example 15 except that the absorbents (2) to (15) were used in place of the absorbent (1).

<Comparative Examples 5, 6, 7 and 8>
Using the comparative absorbents (16) to (19) obtained in Comparative Examples 1 to 4 instead of the absorbent (1), in the same manner as in Example 15, the absorbent bodies for napkins (16) to (19) It was created.

  About the napkin absorbers (1) to (19), the surface dryness value by SDME was measured by the following method, and the measurement results are shown in Table 2.

<SDME dryness>
Place the scanner (detector) of the SDME tester (Systems Engineering) on the polyethylene nonwoven fabric of the absorbent body for napkin soaked in 500ml of horse blood (3.8% citric acid; made by Japan Lamb). The 100% dryness value was set, and then the SDME tester scanner was placed on the polyethylene nonwoven fabric of the absorbent article for napkin dried at 100 ° C. for 5 hours to set the 0% dryness, and the SDME tester was calibrated. .
Place a cylinder (200 g) with an inner diameter of 6 cm and a height of 4 cm at the center of the polyethylene nonwoven fabric (3 cm from the end of 14 cm, 7 cm from the end of 6 cm) of the absorbent fabric for napkin, and 10 ml of horse blood is placed inside it. The napkin absorber is used to absorb horse blood. Leave for 30 minutes as it is, and again add 10 ml of equine blood in the same way. The second time horse blood is absorbed by the napkin absorber, and 1 second after the horse blood drops are removed, the cylinder is removed and a scanner is set at that position. The light reflectance was measured for 5 minutes, and the absolute value after 5 minutes was defined as SDME dryness (%).

As can be seen from Table 1, when the absorbents of the present invention (Examples 1 to 12) and the absorbents of Comparative Examples 1 to 4 are compared, the absorption capacity and absorption rate of blood of the absorbent of the present invention are comparative examples. Compared with those of or better than.
Moreover, the absorbent body for napkin created using the absorbent of this invention is excellent in the dryness property of the absorber surface at the time of absorbing blood.

The absorbent of the present invention is suitable for absorbent articles and the like that require water absorption and / or water retention (particularly, absorbent articles that are required to absorb and / or retain aqueous absorbed liquids including blood). (Children's disposable diapers and adult disposable diapers), sanitary napkins, incontinence pads, breast milk pads, surgical underpads, pet sheets, and other sanitary articles (especially sanitary napkins). In addition, freshness-keeping materials, cold insulation materials, desiccants, drip absorbents, anti-condensation agents, water retention agents for plants and soil, coagulants such as sludge, water-stopping and packing materials for civil engineering and construction, electric cables and optical fiber cables It is also useful for various applications such as waterstops and artificial snow. In other words, the liquid to be absorbed that can be absorbed by the absorbent of the present invention is not particularly limited, but urine, blood, and / or other body fluids, and / or water-based absorbed liquids including drip, seawater, industrial wastewater, and / or muddy water. Liquid. Of these, aqueous absorbent liquids containing urine, blood and / or other body fluids are preferred, and aqueous absorbent liquids containing blood are more preferred.

Claims (8)

Crosslinked polymer particles (S) having (meth) acrylic acid (salt) as a main constituent unit, a surface modifier (A) having a surface tension of 40 to 80 dynes / cm, and a volume average particle diameter of 1 to 500 nm. An absorbent comprising a mixture of water-insoluble particles (B). The absorbent according to claim 1, wherein the surface modifier (A) is a water-soluble polymer. The absorbent according to claim 1 or 2, wherein the surface modifier (A) is polyoxyalkylene glycol. The absorbent according to any one of claims 1 to 3, wherein the water-insoluble particles (B) are amorphous silicon oxide. Based on the weight of the crosslinked polymer particles (S), the surface modifier (A) and the water-insoluble particles (B), the content of (S) is 99.9 to 98% by weight, and the content of (A) is The absorbent according to any one of claims 1 to 4, wherein the content of 0.001 to 1% by weight and (B) is 0.01 to 1.2% by weight. A method for producing an absorbent, comprising the step of mixing the surface modifier (A) and the crosslinked polymer particles (S) and then mixing the mixture and the water-insoluble particles (B). An absorbent article using the absorbent according to any one of claims 1 to 5. The absorbent article according to claim 7, which is used for blood absorption.