JP2009280667A - Absorbent resin particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent resin particle suitable for easy preparation of an absorbent article that hardly allows leakage of urine etc. even in a case when a user is sitting or laying down wearing the article. <P>SOLUTION: The absorbent resin particle contains a crosslinked polymer particle (A), whose essential component units are a water soluble vinyl monomer (a1) and/or a hydrolyzable vinyl monomer (a2) as well as an internal crosslinking agent (b), and a hydrophobic resin particle (B), and has following characteristics, i.e. (a) kinematic friction (F) is 1,000-4,000 mJ, (b) surface tension (T) of the extract liquid is 65-72 mN/m, and (c) an absorbed amount of (S) of physiological salt solution after 1 min is 10-60 g/g. It is desirable that the content of the hydrophobic resin particle (B) based on the weight of the crosslinked polymer particle (A) is 0.01-1, and also desirable is that the hydrophobic resin particle (B) is a thermoplastic resin particle having a softning point of 50-180°C or a natural wax particle having a softning point of 50-180°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to absorbent resin particles.

An absorbent resin with improved absorption obtained by a method using a chain transfer agent such as hypophosphite or thiol is known (Patent Document 1).
JP-A-3-179008

When the conventional absorbent resin is applied to an absorbent article, the absorbent resin breaks due to friction between the absorbent resins in the absorbent article, and gel blocking is likely to occur. Absorbent articles (paper diapers, etc.) using a bag have a problem that leakage or the like tends to occur when the user sits or lies down while wearing.
An object of the present invention is to provide absorbent resin particles that can easily prepare an absorbent article that is less likely to cause leakage even when the user is sitting or lying down while wearing it.

The present inventor has reached the present invention as a result of intensive studies to achieve the above object.
That is, the characteristic of the absorbent resin particles of the present invention is that the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinked polymer particles (A) having the internal crosslinking agent (b) as essential constituent units. And hydrophobic resin particles (B),
(A) Dynamic friction (F) is 1000 to 4000 mJ,
(B) The surface tension (T) of the extract is 65 to 72 mN / m,
(C) Absorption (S) after 1 minute with respect to physiological saline is 10 to 60 g / g
This is the gist.

When the absorbent resin particles of the present invention are applied to an absorbent article, the absorbent resin is not broken by friction between the absorbent resins in the absorbent article, and therefore gel blocking is unlikely to occur.
Therefore, an absorbent article (paper diaper or the like) using the absorbent resin particles of the present invention is less likely to cause leakage even when the user is sitting or lying down.

  The water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) is not particularly limited, and the water-soluble vinyl monomer and / or described in JP-A No. 2001-200006 or JP-A No. 2001-220415 and the like. Hydrolyzable vinyl monomers can be used. The “hydrolyzable vinyl monomer” means a vinyl monomer that can be converted into a water-soluble vinyl monomer by hydrolysis.

  Among these, from the viewpoint of absorption performance, the water-soluble vinyl monomer (a1) is preferable, more preferably an anionic vinyl monomer, and particularly preferably a C3-C30 vinyl group-containing carboxylic acid (salt) {unsaturated monocarboxylic acid. Acids (salts) (such as (meth) acrylic acid, crotonic acid, cinnamic acid and their salts); unsaturated dicarboxylic acids (salts) (such as maleic acid, fumaric acid, citraconic acid, itaconic acid and their salts); and Monoalkyl (carbon number 1-8) ester of unsaturated dicarboxylic acid (maleic acid monobutyl ester, fumaric acid monobutyl ester, maleic acid ethyl carbitol monoester, fumaric acid ethyl carbitol monoester, citraconic acid monobutyl Ester and glycol itaconate monoester, etc.}, most preferably acrylic acid (salt) .

Examples of the salt include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, etc.), ammonium salts {ammonium salts, tetraalkyl (alkyl group having 1 to 8 carbon atoms) ammonium salts. (Tetramethylammonium etc.) etc.} and organic amine salt etc. are mentioned. The organic amine constituting the organic amine salt includes alkylamines having 1 to 8 carbon atoms, alkanolamines having 2 to 8 carbon atoms, polyalkylene (alkylene having 1 to 8 carbon atoms) polyamine (2 to 10 amino groups). Or a derivative of a polyalkylene polyamine {a compound alkylated with an alkyl group having 1 to 8 carbon atoms, or a compound to which an alkylene oxide having 2 to 12 carbon atoms is added (average number of moles added per amino group 1 to 30 Mol)} and the like.
"... acid (salt)" means "... acid" and "... acid salt", and "(meth) acrylic acid" means "methacrylic acid" and "acrylic acid". .

  When the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as constituent units, the content weight ratio (a1 / a2) of these units is preferably 75/25 to 99/1, more preferably 85/15 to 95/5, particularly preferably 90/10 to 93/7, and most preferably 91/9 to 92/8. Within this range, the absorption performance (absorption amount under normal pressure and absorption amount under load) is further improved.

The crosslinked polymer particles (A) are composed of, in addition to the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2), other vinyl monomers (a3) copolymerizable therewith. Can do.
Examples of other copolymerizable vinyl monomers (a3) include hydrophobic vinyl monomers, but are not limited thereto.
As the other vinyl monomer (a3), the following vinyl monomers (i) to (iii) are used.

(I) an aromatic ethylenic monomer having 8 to 30 carbon atoms;
Styrene such as styrene, α-methylstyrene, vinyltoluene, dichlorostyrene and hydroxystyrene, and vinylnaphthalene.
(Ii) an aliphatic ethylenic monomer having 2 to 20 carbon atoms;
Alkenes {ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.}; and alkadienes {butadiene, isoprene, etc.}.
(Iii) an alicyclic ethylenic monomer having 5 to 15 carbon atoms;
Monoethylenic monomers {pinene, limonene, indene and the like}; and polyethylene monomers {cyclopentadiene, bicyclopentadiene, ethylidene norbornene, etc.} and the like.

  When other copolymerizable vinyl monomer (a3) is used as the structural unit, the content (% by weight) of the (a3) unit is that of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit. Based on the total weight, 0.01 to 5 is preferable, more preferably 0.05 to 3, particularly preferably 0.08 to 2, and most preferably 0.1 to 1.5. Within this range, the absorption performance (absorption amount under normal pressure and absorption amount under load) is further improved.

The internal cross-linking agent (b) is not particularly limited, and for example, an internal cross-linking agent described in JP-A-2001-220415 can be used.
Among the internal cross-linking agents (b), from the viewpoint of absorption performance, the internal cross-linking agent (b1) having two or more ethylenically unsaturated groups is preferable, and triallyl cyanurate, triallyl isocyanurate, and carbon number are more preferable. Poly (meth) allyl ethers of 2 to 10 polyols, particularly preferably triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane and pentaerythritol triallyl ether, most preferably pentaerythritol triallyl ether.

  The content (% by weight) of the internal crosslinking agent (b) unit is based on the total weight of the water-soluble vinyl monomer (a1) unit, the hydrolyzable vinyl monomer (a2) unit and the other vinyl monomer (a3) unit. 0.001-5 is preferable, More preferably, it is 0.002-2, Most preferably, it is 0.003-1.6. Within this range, the absorption performance (absorption amount under normal pressure and absorption amount under load) is further improved.

  The weight average particle size (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, handling properties after pulverization (powder fluidity of the crosslinked polymer particles, etc.) are further improved.

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

The smaller the content of fine particles, the better the absorption performance, and the content of fine particles of 106 μm or less (preferably 150 μm or less) in all particles is preferably 10% by weight or less, more preferably 3% by weight or less.
The content of the fine particles is determined using a plot created when determining the weight average particle size.

  Crosslinked polymer particles (A) are commercially available, for example, Sun Wet IM-930, Sun Wet IM-701, Sun Wet IM-717, Aqua Pearl DS-53K {Sundia Polymer Co., Ltd., "Sun Wet" and "Aqua Pearl" is a registered trademark of the company. }; Sunfresh ST-500D * {Sanyo Chemical Industry Co., Ltd., "Sunfresh" is a registered trademark of the company. }, Aquaric CA {Nippon Shokubai Co., Ltd., "Aquaric" is a registered trademark of the company. } And Aquakeep SA60S {Sumitomo Seika Co., Ltd., "Aquakeep" is a registered trademark of the same company. }.

  The softening point (° C.) of the hydrophobic resin particles (B) is preferably 50 to 180, more preferably 60 to 160, particularly preferably 70 to 150, and most preferably 80 to 140 ° C. Within this range, when the absorbent resin particles of the present invention are applied to an absorbent article, the leakage is more difficult to occur. In addition, a softening point is measured based on JISK6863-1994.

Examples of the hydrophobic resin particles (B) include thermoplastic resin particles and natural wax particles.
As the thermoplastic resin, polyolefin, modified polyolefin, olefin-unsaturated carboxylic acid copolymer, polyester, polyamide, polystyrene, polyurethane, vinyl acetate resin, and a mixture of two or more thereof can be used.

Examples of the polyolefin include polyethylene, polypropylene, polymethylpentene, and polybutene.
Examples of the polyolefin-modified product include maleic acid-modified polyethylene, chlorinated polyethylene, maleic acid-modified polypropylene, and maleic acid-modified polybutadiene.
Examples of the olefin-unsaturated carboxylic acid copolymer include ethylene-acrylic acid copolymer, ethylene-maleic anhydride copolymer, propylene-acrylic acid copolymer, propylene-maleic anhydride copolymer, and isobutylene-maleic anhydride. An acid copolymer etc. are mentioned.
Examples of the polyester include polyethylene terephthalate and polybutadiene terephthalate.
Nylon etc. are mentioned as polyamide.
Examples of polystyrene include polystyrene, sulfonated polystyrene, styrene-maleic anhydride copolymer, and the like.
Examples of the polyurethane include resins having polyol and isocyanate as essential constituent monomers. {Polyols and isocyanates can be known ones (for example, Yozo Hirano, “Practical Plastics Encyclopedia”, Industrial Research Council, May 1993) Monthly first edition 1st issue, 257-268))}.
Examples of the vinyl acetate resin include polyvinyl acetate and ethylene-vinyl acetate copolymer.

Examples of natural waxes include beeswax, spermaceti and beef tallow.
Of these, thermoplastic resins are preferred, more preferred are polyolefins and modified polyolefins, particularly preferred are polyolefins, and most preferred are polyethylene and polypropylene.

The weight average particle diameter (μm) of the hydrophobic resin particles (B) is preferably 0.5 to 250, more preferably 0.6 to 200, particularly preferably 0.8 to 150, and most preferably 1 to 100. is there. Within this range, when the absorbent resin particles of the present invention are applied to an absorbent article, it becomes more difficult for the leakage to occur.
In addition, a weight average particle diameter is measured like the case of an absorbent resin particle (A), when it is 38 micrometers or more. On the other hand, in the case of less than 38 μm, the relationship of “particle size-cumulative content (% by weight)” was obtained in accordance with the electrical resistance particle size measurement method described in JIS K1150-1994 5.7.2.1. Thereafter, it is obtained in the same manner as in the case of the absorbent resin particles (A).

  The hydrophobic resin particles (B) can be used in a form emulsified and dispersed in water. When used in a form emulsified and dispersed in water, the content (% by weight) of water is preferably 50 to 98, more preferably 60 to 95, particularly preferably based on the weight of the hydrophobic resin particles (B). Is 70-90.

  Hydrophobic resin particles (B) can be easily obtained from the market, and trade names (in the parentheses, in order, softening point, weight average particle size) are sun wax 161P (111 ° C., 75 μm), Umex 2000P (110 ° C., 85 μm). ), Viscol 660-P (145 ° C., 250 μm) {Sanyo Chemical Industries, Ltd., “Sun Wax”, “Yumex” and “Viscol” are registered trademarks of the company. }; Chemipearl WP100 (108 ° C., 3 μm, water content 60 wt% emulsion), Chemipearl W401 (102 ° C., 1 μm, water content 60 wt% emulsion), Chemipearl S200 (50 ° C., 0.5 μm, water content 73) Wt% emulsion), Chemipearl S100 (60 ° C., 0.6 μm, water content 73 wt% emulsion), Chemipearl S300 (70 ° C., 0.8 μm, water content 65 wt% emulsion) {above, Mitsui Chemicals, Inc. “Chemipearl” is a registered trademark of the company. }; Byron GM903P (105 ° C., 95 μm) {Toyobo Co., Ltd., “Byron” is a registered trademark of the company. }; Aronmelt PPET-2015 (80 ° C., 150 μm) {manufactured by Toagosei Co., Ltd., “Aronmelt” is a registered trademark of the same company. }; A-C307 (140 ° C., 150 μm), A-C1221P (150 ° C., 100 μm), ACumist B9 (130 ° C., 6 μm) {above, Honeywell International Inc. NOVALLOY B6508 (160 ° C., 200 μm) {Daicel Chemical Industries, Ltd., “NOVALOY” is a registered trademark of the company. }; Novatec MA3H (180 ° C., −: flake) {Nippon Polypro Co., Ltd., “Novatech” is a registered trademark of the company. } Pulverized product {such as those obtained by adjusting the weight average particle size by pulverization and sieving in the same manner as the absorbent resin particles (A) described later}.

  The content (% by weight) of the hydrophobic resin particles (B) is preferably 0.01 to 1, more preferably 0.02 to 0.5, particularly preferably based on the weight of the absorbent resin particles (A). Is 0.03-0.1. Within this range, when the absorbent resin particles of the present invention are applied to an absorbent article, the leakage is more difficult to occur.

In the absorbent resin particles of the present invention, known additives {preservatives, fungicides, antibacterial agents, antioxidants, ultraviolet absorbers, colorants, fragrances, deodorants, organic fibrous materials, etc.} It can be contained if necessary.
When these additives are contained, the content (% by weight) of the additives is preferably 0.001 to 10, more preferably 0.01 to 5, based on the weight of the crosslinked polymer particles (A). Particularly preferred is 0.05 to 1, and most preferred is 0.1 to 0.5.

“(A) Dynamic friction (F) (mJ)” of the absorbent resin particles of the present invention is 1000 to 4000, preferably 1500 to 3500, and more preferably 2000 to 3000.
Within this range, it is easy to produce an absorbent article that exhibits higher absorption performance in any state and that is less susceptible to leakage.

  The dynamic friction (F) is measured in accordance with the description in Japanese Patent Application Laid-Open No. 2007-040770 (the best mode for carrying out the invention) (measuring atmosphere: −25 ° C., 50% RH, sample amount: 160 ml split) 105 g in the container, rotational speed: 100 m / s, arithmetic average of 7 measurements).

When the content of the hydrophobic resin particles (B) is in the above range, “(a) dynamic friction (F)” is likely to be in a favorable range. When the content of the hydrophobic resin particles (B) is increased, “(a) dynamic friction (F)” is decreased. On the other hand, when the content is decreased, “(a) dynamic friction (F)” is increased.
In addition, if the content of the hydrophobic resin particles (B) is excessively increased, “(a) dynamic friction (F)” becomes less than 1000, and “(c) absorption amount after 1 minute with respect to physiological saline (S)”. Is less than 10 g / g. On the other hand, if the hydrophobic resin particles (B) are not included, “(a) dynamic friction (F)” is about 6000 to 7000 mJ, and when applied to an absorbent article, the friction between the absorbent resins in the absorbent article. The breakage of the absorbent resin occurs, and gel blocking is likely to occur {as a result, the leakage tends to occur. }.
Further, when the softening point of the hydrophobic resin particles (B) is in the above range, “(a) dynamic friction (F)” is easily set in a favorable range. For example, even if the hydrophobic resin particles (B) having a softening point exceeding 180 ° C. are used, “(a) dynamic friction (F)” is difficult to decrease. On the other hand, when the hydrophobic resin particles (B) having a softening point of less than 50 ° C. are used, the “(b) surface tension (T) of the extract” tends to be less than 65, and the surface tack of the absorbent resin particles is reduced. “(B) Surface tension (T) of the extract” tends to increase.

The “(b) surface tension of the extract (T) (N / m)” of the absorbent resin particles of the present invention is 65 to 72, preferably 67 to 72, and more preferably 69 to 72.
Within this range, it is easy to produce an absorbent article that exhibits higher absorption performance in any state and that is less susceptible to leakage.

  As for the surface tension (T) of the extract, 200 ml of 0.9 wt% sodium chloride aqueous solution (saline) and stirrer piece (total length 37 mm) are placed in a 250 ml glass beaker, and the stirrer piece is stirred at 600 ± 5 rpm. Then, 1.000 ± 0.005 g of sample was added to physiological saline, and the stirring was continued for 3 minutes. Then, the sample was allowed to stand for 15 minutes, and 25 g of the supernatant was transferred to a petri dish having a diameter of 58 mm and a height of 17 mm. The surface tension of the supernatant liquid is measured with a surface tension meter (for example, Denyu surface tension meter manufactured by Shimadzu Corporation). This operation is repeated three times, and these arithmetic average values are used as the surface tension of the extract.

  When the softening point of the hydrophobic resin particles (B) is in the above range, “(b) surface tension (T) (N / m) of the extract” is easily set in a favorable range. When the hydrophobic resin particles (B) having a low softening point are used, it becomes easy to lower the “(b) surface tension of the extract (T) (N / m)” and the hydrophobic resin particles (B) having a high softening point. Is used, it becomes easy to increase “(b) surface tension (T) (N / m) of the extract”. However, for example, when the hydrophobic resin particles (B) having a softening point of less than 50 ° C. are used, the “(b) surface tension (T) of the extract” tends to be less than 65. On the other hand, if the hydrophobic resin particles (B) are not included, “(a) dynamic friction (F)” is less than 1000 mJ. When the hydrophobic resin particles (B) having a softening point exceeding 180 ° C. are used, “(a) dynamic friction (F)” tends to exceed 4000 mJ.

  “(C) Absorption amount after 1 minute (S) (g / g) with respect to physiological saline” of the absorbent resin particles of the present invention is 10 to 60, preferably 15 to 60, more preferably 20 to. 60. Within this range, it is easy to produce an absorbent article that exhibits higher absorption performance in any state and that is less susceptible to leakage.

  The amount of absorption (S) after 1 minute with respect to physiological saline is measured in accordance with the DW (Demand Wettability) method {see the explanation page 3-4 of JIS K7224-1996, Fig. 1}, 25 ° C, humidity 50% The DW device {capacity of burette (1) 25 ml, length 55 cm, small hole (2) diameter 2 mm} is used, and the lowermost end of the air inflow tubule (3) and the uppermost end of the support plate (4) After adjusting the part to be on the same horizontal plane, with the valves (5) and (6) closed, about 25 ml of physiological saline was put into the burette (1) and a rubber stopper (7) was attached. After that, by opening the valves (5) and (6), the pipe (8) is filled with physiological saline, and the physiological saline overflows from the small hole (2) provided in the center of the support plate (4). After closing the valve (5), wipe off the overflowing saline. Read the liquid level (h1) of the uret (1). Subsequently, a plain weave nylon mesh (9) {aperture 63 μm, 5 cm × 5 cm} is placed on the support plate (4), and 1.0 g of the measurement sample (10) is placed on the plain weave nylon mesh (9). After spraying, the valve (5) is opened, and after 1 minute, the liquid level (h2) of the burette is read, and the liquid level difference {(h1)-(h2)} is defined as the amount of absorption (g / g). In addition, the temperature of the physiological saline used and measurement atmosphere is 25 degreeC +/- 2 degreeC.

  When the content of the hydrophobic resin particles (B) is in the above range, “(c) Absorption amount after 1 minute with respect to physiological saline (S)” is easily set in a favorable range. When the content of the hydrophobic resin particles (B) is increased, the “(c) absorption amount after 1 minute with respect to physiological saline (S)” is also increased. On the other hand, when the content is decreased, “(c) physiological saline” The amount of absorption (S) after 1 minute with respect to water also decreases. However, if the content of the hydrophobic resin particles (B) is excessively increased, the “(c) absorption amount after 1 minute with respect to physiological saline (S)” tends to be less than 10. On the other hand, if the hydrophobic resin particles (B) are not contained, the “(c) absorption amount after 1 minute (S) with respect to physiological saline” exceeds 60.

  The crosslinked polymer particles (A) can be prepared by a known method. For example, a solution polymerization method (JP-A-9-194541 and JP-A-8-120009, etc.), an emulsion polymerization method (JP-A-10-218944). And JP-A-5-170805), suspension polymerization methods (JP-A-7-133326 and JP-A-6-220109 etc.) and reverse-phase suspension polymerization methods (JP-A-2-153907) and JP 2001-31704 A, etc.) can be applied. Moreover, the polymerization liquid at the time of superposition | polymerization may be a thin film form, and may be a spray form. The polymerization control method may be any one of adiabatic polymerization method, temperature control polymerization method, isothermal polymerization method and the like.

When applying the suspension polymerization method or the reverse phase suspension polymerization method, a dispersant (sucrose ester, phosphate ester, sorbitan ester, etc .: JP-A-2-284927 etc.), hydrophobic solvent (if necessary) Cyclohexane, normal hexane, normal heptane, toluene, xylene, etc .: JP-A-2-284927, etc.) and protective colloids (Poval, α-olefin-maleic anhydride copolymer, polyethylene oxide, etc.): US Pat. No. 5,231,145 Etc.) can be used.
In any of the polymerization methods, since water is used as a solvent, the crosslinked polymer particles (A) are obtained as a hydrogel containing water {including the crosslinked polymer particles (A) and water}.

  Among the polymerization methods, the solution polymerization method is preferable, and an aqueous solvent polymerization method is more preferable because it is not necessary to use an organic solvent or the like and is advantageous in terms of production cost.

  A polymerization initiator can be used for the polymerization for obtaining the crosslinked polymer particles (A), and known polymerization initiators {azo initiators, peroxide initiators, redox initiators, organic halogen compounds, etc. (Japanese Patent Laid-Open No. 2001-200006, etc.)} can be used.

The water-containing gel {including the crosslinked polymer (A) and water} obtained by polymerization can be shredded as necessary. The size (longest diameter) of the hydrogel after shredding is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying process is further improved.
Shredding can be performed by a known method, and for example, usual apparatuses such as a Bex mill, a rubber chopper, a pharma mill, a mincing machine, an impact pulverizer, and a roll pulverizer can be used.

  When using a solvent (including water) for the polymerization of the crosslinked polymer particles (A), the solvent can be distilled off from the hydrogel after polymerization.

  When the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably 10 to 0.01, more preferably 5 to 0, based on the weight of the crosslinked polymer particles (A). .05, particularly preferably 3 to 0.1, most preferably 1 to 0.5. Within this range, the absorption performance (particularly the water retention amount) of the absorbent resin particles is further improved.

  When water is included in the solvent, the water content (% by weight) after distillation is preferably 0 to 20, more preferably 0 to 10, particularly preferably 0 to 5 based on the weight of the crosslinked polymer particles (A). Most preferably, it is 0-2. Within this range, the absorption performance (particularly the water retention amount) and the handling properties after drying (such as the powder flowability of the crosslinked polymer particles) are further improved.

In addition, the content and moisture of the organic solvent are an infrared moisture meter (JE400 manufactured by KETT Co., Ltd.): 120 ± 5 ° C., 30 minutes, atmospheric humidity before heating 50 ± 10% RH, lamp specification 100V, 40W ) Is obtained from the weight loss of the crosslinked polymer (A) before and after heating.
The method of distilling off the solvent is a method of distilling (drying) with hot air at a temperature of 80 to 230 ° C., a thin film drying method using a drum dryer or the like heated to 100 to 230 ° C., (heating) vacuum drying method, freeze drying Ordinary methods such as drying, infrared drying, decantation and filtration may be used.

  Further, the hydrogel {including the crosslinked polymer (A) and water} can be pulverized after drying (distilling off the solvent) to obtain crosslinked polymer particles (A). In addition, the particles may be obtained by further crushing the hydrogel and drying it.

The pulverization method is not particularly limited, and usual devices such as a hammer pulverizer, an impact pulverizer, a roll pulverizer, and a shet airflow pulverizer can be used. The obtained pulverized product is sieved as necessary to adjust the particle size.
The shape of the crosslinked polymer particles (A) is not particularly limited, and examples thereof include an irregularly crushed shape, a flake shape, a pearl shape, and a rice grain shape. Among these, from the viewpoint of good entanglement with the fibrous material in the use of paper diapers and the like and no fear of dropping off from the fibrous material, an irregular crushed shape is preferable.

The crosslinked polymer particles (A) can be surface-crosslinked (surface crosslinking treatment). The surface-crosslinked crosslinked polymer particles (A) are preferable because the amount of absorption under a load increases.
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 the like, and JP-A-51-136588 or JP-A-61- And multivalent metals described in Japanese Patent No. 257235. Of these surface cross-linking agents, form a strong covalent bond with a carboxyl (carboxylate) group to obtain a water-absorbing resin excellent in the amount of absorption under load, and allow the cross-linking reaction to be performed at a relatively low temperature. From the standpoint of being economical and economical, polyvalent glycidyl, polyvalent amine and silane coupling agent are preferred, polyvalent glycidyl and silane coupling agent are more preferred, and polyvalent glycidyl is particularly preferred.

  When using a surface cross-linking agent, known use amounts and methods can be applied as the amount of surface cross-linking agent used and the method of surface cross-linking.

The absorbent resin particles of the present invention are prepared by uniformly mixing (preferably powder mixing) the crosslinked polymer particles (A) and the hydrophobic resin particles (B).
As an apparatus for mixing the crosslinked polymer particles (A) and the hydrophobic resin particles (B), an ordinary mixing apparatus can be used. For example, a conical blender, a nauter mixer, a V-type mixer, a fluidized bed type mixer, Examples include turbulizers, screw type line blending devices, and honeycomb type static mixers. In the case where the hydrophobic resin particles (B) are emulsified and dispersed in water, the absorbent resin particles of the present invention are mixed with the hydrophobic resin particles (B) while stirring the crosslinked polymer particles (A). ) Of the emulsified / dispersed liquid.

The water content (% by weight) of the absorbent resin particles of the present invention is preferably from 1 to 12, more preferably from 2 to 10, particularly preferably from 4 to 8, from the viewpoints of workability, texture, moisture resistance and the like. Within this range, the absorbent resin particles are prevented from being destroyed by impact, and workability and the like are further improved.
The water content is not determined only by the drying process, but is adjusted by the surface cross-linking process and the hydration process. The moisture content is determined by heating with an infrared moisture measuring instrument {for example, JE400 manufactured by KETT Co., Ltd. (lamp specification 100V, 40W), etc.} (120 ± 5 ° C., 30 minutes, ambient humidity before heating 50 ± 10%) RH) from the weight loss of the measurement sample before and after heating.

  If necessary, the absorbent resin particles of the present invention may be at any stage {polymerization step of crosslinked polymer particles (A), shredding step, drying step, pulverization step, surface cross-linking step and / or before and after these steps, etc.} In addition, a known additive can be added.

By applying the absorbent resin particles of the present invention to various absorbers, absorbent articles having excellent absorption performance can be produced.
As a method for applying the absorbent resin particles to the absorbent body, (1) a method in which the absorbent resin particles are dispersed between fibrous layers made of pulp or the like arranged in layers; (2) pulp, heat A method of mixing a fibrous material composed of fusible fibers and the like and an absorbent resin particle; (3) A method of sandwiching the absorbent resin particles together with the fibrous material, if necessary, using two or more water-absorbing papers and nonwoven fabrics. Etc. In addition, as a fibrous thing, a well-known thing {For example, the thing etc. which are described in patent 3648553} is mentioned.

  When the absorbent resin particles of the present invention are used in an absorbent body, the amount (% by weight) of the absorbent resin particles of the present invention can be varied depending on the type and size of the absorbent body and the target absorbent performance. However, it is preferably 30 to 95, more preferably 40 to 94, and particularly preferably 50 to 93, based on the total weight of the absorbent resin particles and the fibrous material. Within this range, the absorbent performance of the obtained absorbent body is further improved.

The absorbent body using the absorbent resin particles of the present invention has a light touch even when it absorbs liquids to be absorbed (body fluids such as sweat, urine and blood, and water such as seawater, groundwater and muddy water). Therefore, when applied to absorbent articles such as sanitary goods (paper diapers, sanitary napkins, etc.), it exhibits not only excellent absorption performance but also excellent characteristics that the liquid to be absorbed does not easily return even under pressure.
Therefore, by using the absorbent resin particles of the present invention, it is possible to easily manufacture an absorbent article that exhibits high absorption performance in any state.
That is, the absorbent article using the absorbent resin particles of the present invention does not decrease the absorption amount and the absorption speed even in a state where a load is applied such as sitting or lying down while the user is wearing it. As a result, problems such as gel blocking and leakage hardly 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.
Hygiene products include paper diapers (children's disposable diapers and adult disposable diapers, etc.), napkins (such as sanitary napkins), paper towels, pads (such as incontinence pads and surgical underpads), and pet sheets (pet urine absorbing sheets). Etc. Of these hygiene articles, they are more suitable for disposable diapers.

  The absorbent resin particles of the present invention are used not only for hygiene products as described above, but also for pet urine absorbent, urine gelling agent for portable toilets, freshness retaining agents such as fruits and vegetables, drip absorbents for meat and seafood, cold insulation It is also useful for various applications such as agents, disposable warmers, gelling agents for batteries, water retention agents for plants and soil, anti-condensation agents, water-stopping materials and packing materials, and artificial snow.

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>
Crosslinked polymer particles (A1) {Sandia Polymer Co., Ltd., cross-linked polyacrylic acid sodium salt, trade name “Sunwet IM-930”, weight average particle size 375 μm) 100 parts, hydrophobic resin particles (B1) {Sanyo Kasei Kogyo Co., Ltd., low molecular weight polyethylene, trade name “Sunwax 161P”, softening point 111 ° C., weight average particle size 75 μm} 0.1 parts are put into a V-type mixer (Irie Seisakusho Co., Ltd .: VK-2S) The mixture was uniformly mixed at about 25 ° C. for 20 minutes to obtain the water-absorbent resin particles (1) of the present invention.

<Example 2>
Absorbent resin particles (2) of the present invention were obtained in the same manner as in Example 1, except that the hydrophobic resin particles (B1) were changed from “0.1 part” to “0.01 part”.

<Example 3>
Absorbent resin particles (3) of the present invention were obtained in the same manner as in Example 1, except that the hydrophobic resin particles (B1) were changed from “0.1 part” to “1 part”.

<Example 4>
Absorbent resin particles (4) of the present invention were obtained in the same manner as in Example 1, except that the hydrophobic resin particles (B1) were changed from “0.1 part” to “0.02 parts”.

<Example 5>
Absorbent resin particles (5) of the present invention were obtained in the same manner as in Example 1 except that the hydrophobic resin particles (B1) were changed from “0.1 part” to “0.03 part”.

<Example 6>
Absorbent resin particles (6) of the present invention were obtained in the same manner as in Example 1, except that the hydrophobic resin particles (B1) were changed from “0.1 part” to “0.04 parts”.

<Example 7>
Absorbent resin particles (7) of the present invention were obtained in the same manner as in Example 1, except that the hydrophobic resin particles (B1) were changed from “0.1 part” to “0.08 part”.

<Example 8>
Absorbent resin particles (8) of the present invention were obtained in the same manner as in Example 1 except that the hydrophobic resin particles (B1) were changed from “0.1 part” to “0.5 part”.

<Example 9>
“Hydrophobic resin particles (B1)” are converted into “hydrophobic resin particles (B2) {manufactured by Sanyo Chemical Industries, Ltd., maleic acid-modified polyethylene, trade name“ Yumex 2000P ”, softening point 108 ° C., weight average particle size 85 μm}” Absorbent resin particles (9) of the present invention were obtained in the same manner as in Example 1 except that the above was changed.

<Example 10>
The absorbent resin particle (10 of the present invention) was changed in the same manner as in Example 1 except that the “hydrophobic resin particle (B1) 0.1 part” was changed to “hydrophobic resin particle (B2) 0.01 part”. )

<Example 11>
The absorbent resin particles (11) of the present invention were prepared in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1” were changed to “parts of hydrophobic resin particles (B2)”. Obtained.

<Example 12>
“Hydrophobic resin particles (B1)” was changed to “Hydrophobic resin particles (B3) {manufactured by Toyobo Co., Ltd., polyester resin, trade name“ Byron GM903P ”, softening point 133 ° C., weight average particle size 95 μm}”. Except for this, the absorbent resin particles (12) of the present invention were obtained in the same manner as in Example 1.

<Example 13>
The absorbent resin particles (13 of the present invention) were obtained in the same manner as in Example 1 except that “0.1 part of the hydrophobic resin particles (B1)” was changed to “0.01 part of the hydrophobic resin particles (B3)”. )

<Example 14>
The absorbent resin particles (14) of the present invention were obtained in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1” were changed to “parts of hydrophobic resin particles (B3)”. Obtained.

<Example 15>
“Hydrophobic resin particles (B1)” was changed to “Hydrophobic resin particles (B4) {manufactured by Honeywell International Inc., polyethylene oxide, trade name“ A-C307, softening point 140 ° C., weight average particle size 150 μm} ”. Except that, the absorbent resin particles (15) of the present invention were obtained in the same manner as in Example 1.

<Example 16>
The absorbent resin particles (16 of the present invention (16) were changed in the same manner as in Example 1 except that 0.1 part of the hydrophobic resin particles (B1) was changed to 0.01 part of the hydrophobic resin particles (B4). )

<Example 17>
The absorbent resin particles (17) of the present invention were changed in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1 part” was changed to “parts of hydrophobic resin particles (B4)”. Obtained.

<Example 18>
“Hydrophobic resin particles (B1)” are referred to as “hydrophobic resin particles (B5) {manufactured by Toagosei Co., Ltd., maleic acid-modified polyethylene, trade name“ Aronmelt PPET-2015, softening point 80 ° C., weight average particle size 150 μm} ”. Absorbent resin particles (18) of the present invention were obtained in the same manner as in Example 1 except that the above was changed.

<Example 19>
The absorbent resin particles (19 of the present invention) were used in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1 parts” were changed to “parts of hydrophobic resin particles (B5) 0.01”. )

<Example 20>
The absorbent resin particle (20) of the present invention was changed in the same manner as in Example 1 except that “hydrophobic resin particle (B1) 0.1 part” was changed to “hydrophobic resin particle (B5) 1 part”. Obtained.

<Example 21>
“Hydrophobic resin particles (B1)” was changed to “Hydrophobic resin particles (B6) {manufactured by Honeywell International Inc., maleic acid-modified polyethylene, trade name“ ACumist B9, softening point 130 ° C., weight average particle size 6 μm} ”. Except that, the absorbent resin particles (21) of the present invention were obtained in the same manner as in Example 1.

<Example 22>
Absorbent resin particles (22) of the present invention were obtained in the same manner as in Example 1 except that “hydrophobic resin particles (B1) 0.1 part” was changed to “hydrophobic resin particles (B6) 0.01 part”. )

<Example 23>
The absorbent resin particles (23) of the present invention were obtained in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1” was changed to “parts of hydrophobic resin particles (B6)”. Obtained.

<Example 24>
“Hydrophobic resin particle (B1)” is replaced with “Hydrophobic resin particle (B7) {manufactured by Honeywell International Inc., ethylene / maleic anhydride copolymer, trade name“ A-C1221P, softening point 150 ° C., weight average particle size ” Absorbent resin particles (24) of the present invention were obtained in the same manner as in Example 1 except that it was changed to “100 μm}”.

<Example 25>
In the same manner as in Example 1, except that the “hydrophobic resin particles (B1) 0.1 part” was changed to “hydrophobic resin particles (B7) 0.01 part”, the absorbent resin particles (25 )

<Example 26>
The absorbent resin particles (26) of the present invention were obtained in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1 part” was changed to “parts of hydrophobic resin particles (B7)”. Obtained.

<Example 27>
“Hydrophobic resin particles (B1)” are changed to “hydrophobic resin particles (B8) {manufactured by Daicel Chemical Industries, Ltd., styrene-maleic anhydride copolymer, trade name“ Novaloy B6508, softening point 160 ° C., weight average particle size ” Absorbent resin particles (27) of the present invention were obtained in the same manner as in Example 1 except that it was changed to “200 μm}”.

<Example 28>
The absorbent resin particles (28) of the present invention were obtained in the same manner as in Example 1 except that “0.1 part of the hydrophobic resin particles (B1)” was changed to “0.01 part of the hydrophobic resin particles (B8)”. )

<Example 29>
The absorbent resin particles (29) of the present invention were changed in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1 part” was changed to “parts of hydrophobic resin particles (B8)”. Obtained.

<Example 30>
“Hydrophobic resin particles (B1)” are changed to “hydrophobic resin particles (B9) {manufactured by Sanyo Chemical Industries, Ltd., maleic acid-modified polyethylene, trade name“ Biscol 660-P, softening point 45 ° C., weight average particle size 250 μm} ” The absorbent resin particles (30) of the present invention were obtained in the same manner as in Example 1 except that the above was changed.

<Example 31>
The absorbent resin particles (31 of the present invention) were obtained in the same manner as in Example 1 except that “0.1 part of the hydrophobic resin particles (B1)” was changed to “0.01 part of the hydrophobic resin particles (B9)”. )

<Example 32>
The absorbent resin particles (32) of the present invention were changed in the same manner as in Example 1 except that “parts of hydrophobic resin particles (B1) 0.1 part” was changed to “parts of hydrophobic resin particles (B9)”. Obtained.

<Example 33>
Hydrophobic resin particles (B10) {manufactured by Mitsui Chemicals, Inc. while stirring 100 parts of the crosslinked polymer particles (A1) at a high speed of about 25 ° C. {High-speed stirring turbulizer manufactured by Hosokawa Micron Corporation: rotation speed 2000 rpm} Low molecular weight polypropylene emulsion, trade name “Chemipearl WP100”, softening point 108 ° C., weight average particle size 3 μm, polypropylene concentration 40%} is sprayed with a two-fluid spray nozzle and stirred at high speed for another 20 minutes. Thus, absorbent resin particles (33) of the present invention were obtained.

<Example 34>
Absorbent resin particles (34) of the present invention were obtained in the same manner as in Example 33 except that the hydrophobic resin particles (B10) were changed from “0.3 parts” to “0.03 parts”.

<Example 35>
“Hydrophobic resin particles (B10)” are changed to “hydrophobic resin particles (B11) {manufactured by Mitsui Chemicals, low molecular weight polyethylene emulsion, trade name“ Chemipearl W401 ”, softening point 102 ° C., weight average particle size 1 μm, Absorbent resin particles (35) of the present invention were obtained in the same manner as in Example 33, except that the concentration was changed to 40%}.

<Example 36>
In the same manner as in Example 33, except that the “hydrophobic resin particle (B10) 0.3 part” was changed to “hydrophobic resin particle (B11) 0.03 part”, the absorbent resin particle (36 )

<Example 37>
“Hydrophobic resin particles (B10)” are changed to “hydrophobic resin particles (B12) {manufactured by Mitsui Chemicals, low molecular weight polyethylene emulsion, trade name“ Chemical S200 ”, softening point 50 ° C., weight average particle size 0.5 μm, Absorbent resin particles (37) of the present invention were obtained in the same manner as in Example 33 except that the polyethylene concentration was changed to 27 wt%}.

<Example 38>
The absorbent resin particle (38) of the present invention was obtained in the same manner as in Example 33 except that “hydrophobic resin particle (B10) 0.3 part” was changed to “hydrophobic resin particle (B12) 0.03 part”. )

<Example 39>
“Hydrophobic resin particles (B10)” are changed to “hydrophobic resin particles (B13) {manufactured by Mitsui Chemicals, low molecular weight polyethylene emulsion, trade name“ Chemical S100 ”, softening point 60 ° C., weight average particle size 0.6 μm, Absorbent resin particles (39) of the present invention were obtained in the same manner as in Example 33 except that the polyethylene concentration was changed to 27 wt%}.

<Example 40>
The absorbent resin particle (40) of the present invention (40) was changed in the same manner as in Example 33 except that the “hydrophobic resin particle (B10) 0.3 part” was changed to “hydrophobic resin particle (B13) 0.03 part”. )

<Example 41>
“Hydrophobic resin particles (B10)” are changed to “hydrophobic resin particles (B14) {manufactured by Mitsui Chemicals, low molecular weight polyethylene emulsion, trade name“ Chemical S300 ”, softening point 70 ° C., weight average particle size 0.8 μm, Absorbent resin particles (41) of the present invention were obtained in the same manner as in Example 33 except that the polyethylene concentration was changed to 35% by weight}.

<Example 42>
The absorbent resin particle (42) of the present invention (42) was changed in the same manner as in Example 33 except that the "hydrophobic resin particle (B10) 0.3 part" was changed to "hydrophobic resin particle (B14) 0.03 part". )

<Example 43>
“Crosslinked polymer particles (A1)” is changed to “Crosslinked polymer particles (A2) {Sandia Polymer Co., Ltd., cross-linked polyacrylic acid sodium salt, trade name“ Sunwet IM-701 ”, weight average particle size 375 μm}” Except having carried out, it carried out similarly to Example 1, and obtained the absorbent resin particle (43) of this invention.

<Example 44>
“Crosslinked polymer particles (A1)” was changed to “Crosslinked polymer particles (A2)”, and hydrophobic resin particles (B1) were changed from “0.1 part” to “0.01 part”. Except that, the absorbent resin particles (44) of the present invention were obtained in the same manner as in Example 1.

<Example 45>
“Crosslinked polymer particle (A1)” is changed to “Crosslinked polymer particle (A3) {Sandia Polymer Co., Ltd., cross-linked polyacrylic acid sodium salt, trade name“ Aqua Pearl DS-53K ”, weight average particle size 350 μm}”. Except having changed, it carried out similarly to Example 1, and obtained the water absorbing agent (45) of this invention.

<Example 46>
Except for changing the “crosslinked polymer particles (A1)” to “crosslinked polymer particles (A3)” and changing the hydrophobic resin particles (B1) from “0.1 part” to “1 part”, In the same manner as in Example 1, absorbent resin particles (46) of the present invention were obtained.

<Example 47>
“Crosslinked polymer particle (A1)” was changed to “Crosslinked polymer particle (A4) {manufactured by Nippon Shokubai Co., Ltd., crosslinked polyacrylic acid sodium salt, trade name“ AQUALIC CA ”, weight average particle size 380 μm}”. Except that, the absorbent resin particles (47) of the present invention were obtained in the same manner as in Example 1.

<Example 48>
“Crosslinked polymer particle (A1)” is changed to “Crosslinked polymer particle (A5) {Sandia Polymer Co., Ltd., crosslinked polyacrylic acid sodium salt, trade name“ Sunwet IM-717 ”, weight average particle size 375 μm}”. Except having changed, it carried out similarly to Example 1, and obtained the absorbent resin particle (48) of this invention.

<Example 49>
“Crosslinked polymer particle (A1)” was changed to “crosslinked polymer particle (A5)” and hydrophobic resin particle (B1) was changed from “0.1 part” to “0.01 part”. Except that, the absorbent resin particles (49) of the present invention were obtained in the same manner as in Example 1.

<Example 50>
Except for changing the “crosslinked polymer particles (A1)” to “crosslinked polymer particles (A5)” and changing the hydrophobic resin particles (B1) from “0.1 part” to “1 part”, In the same manner as in Example 1, absorbent resin particles (50) of the present invention were obtained.

<Example 51>
The “hydrophobic resin particles (B1)” were adjusted to the “hydrophobic resin particles (B15) {manufactured by Nippon Polypro Co., Ltd., polypropylene, trade name“ NOVATEC MA3H ”, softening point 180 ° C., flakes” to a weight average particle size of 250 μm. Absorbent resin particles (51) of the present invention were obtained in the same manner as in Example 1 except that they were changed to "Things (sieved and prepared by mixing each particle size)."

<Comparative Example 1>
The crosslinked polymer particles (A1) were directly used as comparative absorbent resin particles (H1).

<Comparative Example 2>
The crosslinked polymer particles (A2) were directly used as comparative absorbent resin particles (H2).

<Comparative Example 3>
The crosslinked polymer particles (A3) were directly used as comparative absorbent resin particles (H3).

<Comparative example 4>
The crosslinked polymer particles (A4) were directly used as comparative absorbent resin particles (H4).

<Comparative Example 5>
The crosslinked polymer particles (A5) were directly used as comparative absorbent resin particles (H5).

<Comparative Example 6>
Example 1 except that “hydrophobic resin particles (B1)” was changed to “hydrophobic particles {manufactured by Nippon Seiwa Co., Ltd., paraffin wax, trade name 115, softening point 47 ° C., weight average particle size 60 μm}”. Similarly, comparative absorbent resin particles (H6) were obtained.

<Comparative Example 7>
Absorption for comparison was carried out in the same manner as in Example 1 except that “hydrophobic resin particles (B1)” was changed to “hydrophobic liquid {manufactured by Shin-Etsu Chemical Co., Ltd., amino-modified silicone oil, trade name KF-877}”. Resin particles (H7) were obtained.

<Comparative Example 8>
“Hydrophobic resin particles (B1)” is “hydrophilic liquid {manufactured by Sanyo Chemical Industries, Ltd., palm oil fatty acid amidopropyl betaine, trade name Levon 2000,“ Levon ”are registered trademarks of the company. Absorbent resin particles (H8) for comparison were obtained in the same manner as in Example 1, except that the change was made to "}".

  For the absorbent resin particles (1) to (51) and (H1) to (H8), the dynamic friction (F), the surface tension (T) of the extract, and the absorbed amount (S) after 1 minute with respect to physiological saline are measured. These results are shown in Tables 1 and 2. Moreover, about the absorptive resin particles (1) to (51) and (H1) to (H8), the particle breakage rate and the blocking rate were evaluated and are shown in Tables 1 and 2.

<Particle breakage rate (%)>
The difference (% ratio) in the content (%) of fine particles of 150 μm or less before and after the measurement of dynamic friction (F) was defined as the particle breakage rate (%). The content (%) of fine particles of 150 μm or less is determined using a plot created when determining the weight average particle diameter.

(Particle breakage rate (%)) = (AR) − (BR)

(AR) is the content (%) of fine particles of 150 μm or less after measurement of dynamic friction (F), and (BR) is the content (%) of fine particles of 150 μm or less before measurement of dynamic friction (F).

<Blocking rate (%)>
Among the particles after measuring the dynamic friction (F), particles that passed by tapping a metal sieve having an opening of 850 μm five times were used as measurement samples. 10 g of this measurement sample was placed uniformly in an aluminum cylindrical dish having a diameter of 5 cm, and the cylindrical dish was allowed to stand in a constant temperature and humidity chamber of 40 ± 1 ° C. and 80 ± 5% RH for 3 hours. After 3 hours, after measuring the weight (TW) of the measurement sample, tapping it 5 times with a 850 μm metal sieve, measuring the weight (OW) of the measurement sample remaining on the metal sieve, the blocking rate ( %) Was calculated.

(Blocking rate (%)) = (OW) × 100 / (TW)

<Example 52>
A mixture obtained by mixing 100 parts of fluff pulp and 100 parts of the absorbent resin particles (1) of the present invention obtained in Example 1 with an airflow type mixing apparatus {manufactured by Autech Co., Ltd.} is a nylon net {JIS Z8801-1: 2000} was laminated uniformly so as to have a basis weight of about 400 g / m ² and pressed at a pressure of 5 Kg / cm ² for 30 seconds to obtain the absorbent body (1) of the present invention.
This absorbent body (1) is cut into a rectangle of 14 cm × 36 cm, and water absorbent paper having the same size as the absorbent body at the top and bottom (basis weight 15.5 g / m ² , manufactured by Advantech Toyo Co., Ltd., filter paper No. 2) And a polyethylene sheet (polyethylene film UB-1 manufactured by Kumapoly Co., Ltd.) on the back, non-woven fabric made of polyethylene (basis weight 20.0 g / m ² , Ertas Guard manufactured by Asahi Kasei Fibers Co., Ltd. The absorbent article {paper diaper (1)} according to the present invention was prepared by placing the product on the surface.

<Examples 53 to 102>
Except having changed "absorbent resin particle (1)" into either of "absorbent resin particle (2)-(51)", it carried out similarly to Example 52, and the absorber (2)-( 51) was prepared, and in the same manner, absorbent articles {paper diapers (2) to (51)} of the present invention were prepared.

<Comparative Examples 9-16>
Except having changed "absorbent resin particle (1)" into either of the "absorbent resin particle for comparison (H1)-(H8)" obtained in Comparative Examples 1-8, it carried out similarly to Example 52. Comparative absorbent bodies (H1) to (H8) were prepared, and in the same manner, comparative absorbent articles {paper diapers (H1) to (H8)} were prepared.

  For the absorbent articles {paper diapers (1) to (51) and (H1) to (H8)}, the amount of absorption until leakage, the surface dryness, and the surface dryness value by SDME are measured by the following methods, and these measurement results are obtained. The results are shown in Tables 3 and 4.

<Absorption amount until leakage>
After placing an absorbent article {paper diaper (140 mm x 360 mm)} on an acrylic board (140 mm x 360 mm, weight 0.5 kg), one end (upper end) of the short side (140 mm) of the absorbent article is covered with gummed tape. (The overlap between the absorbent article and the gum tape: 1 cm width from one end), and the acrylic plate is fixed in a state inclined at 45 degrees so that one end (upper end) to which the absorbent article is fixed is at the top. Next, artificial urine (calcium chloride 0.03%, magnesium sulfate 0.08%, sodium chloride 0.8) is 30 mm from the upper end {330 mm from the other end (lower end)} and 70 mm from both ends of the long side. % And ion-exchanged water 99.09%) were added at a rate of 100 g / min with a dropping pump (manufactured by Sakai Sangyo Co., Ltd., trade name CP-21). The point in time when the artificial urine leaked from the lower end of the absorbent article was taken as the end point, the amount of artificial urine input until it leaked was determined, and this was taken as the amount of absorption up to the leak.

<Dry surface>
Using the absorbent article after measuring the amount of absorption until leakage, the dry feeling of the surface of the absorbent article was judged by 10 panelists and evaluated in the following four stages. The average of 10 persons was calculated | required and it was set as surface dry feeling. In addition, it means that a surface dry feeling is excellent, so that a numerical value is large.
3: Good dry feeling 2: Slightly moist but satisfactory level of dry feeling 1: Poor dry feeling, moist condition 0: No dry feeling, wet condition

<Surface dryness value by SDME method>
Measurement was performed by the following procedure using an SDME (Surface Dryness Measurement Equipment) tester (manufactured by WK system).
Place the detector of the SDME tester on a fully moistened absorbent article (soaked in artificial urine to cover the absorbent article and let stand for 60 minutes), set the 0% dryness value, then The detector of the SDME tester was placed on a dry absorbent article (the absorbent article was heated and dried 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 at the center of the absorbent article to be measured, and after injecting 80 ml of artificial urine, the metal ring is immediately removed, and the center of the absorbent article is removed. The SDME detector was set in contact with the absorbent article and measurement was started. And the value 5 minutes after a measurement start was made into the surface dryness value by SDME.

The absorbent resin particle of the present invention can be made into an absorbent article in which the liquid to be absorbed is difficult to be absorbed by being applied to various absorbers. In particular, absorption of paper diapers (children's disposable diapers, adult disposable diapers, etc.), napkins (sanitary napkins, etc.), paper towels, pads (incontinence pads, surgical underpads, etc.) and pet sheets (pet urine absorbing sheets) Suitable for sexual articles (hygiene products), and most suitable for disposable diapers.
The absorbent resin particles of the present invention are not only sanitary products, but also pet urine absorbents, urine gelling agents for portable toilets, freshness-preserving agents such as fruits and vegetables, meat and seafood drip absorbents, cold insulation agents, disposable warmers It is also useful for various applications such as battery gelling agents, water retention agents such as plants and soil, anti-condensation agents, water-stopping materials and packing materials, and artificial snow.

It is the vertical sectional view showing typically the DW device {device by the Demand Wettability method} for measuring the amount of absorption (S) after 1 minute to the physiological saline.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Viewlet 2 Small hole 3 Air inflow thin tube 4 Support plate 5 Valve 6 Valve 7 Rubber stopper 8 Piping 9 Plain weave nylon mesh 10 Measurement sample

Claims (5)

Containing water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and crosslinked polymer particles (A) and hydrophobic resin particles (B) having an internal crosslinking agent (b) as essential constituent units; Become
(A) Dynamic friction (F) is 1000 to 4000 mJ,
(B) The surface tension (T) of the extract is 65 to 72 mN / m,
(C) Absorption (S) after 1 minute with respect to physiological saline is 10 to 60 g / g
Absorbent resin particles characterized by being. The absorbent resin particle according to claim 1, wherein the content of the hydrophobic resin particle (B) is 0.01 to 1 based on the weight of the crosslinked polymer particle (A). The absorbent resin particles according to claim 1 or 2, wherein the hydrophobic resin particles (B) are thermoplastic resin particles having a softening point of 50 to 180 ° C or natural wax particles having a softening point of 50 to 180 ° C. The absorber formed by containing the absorptive resin particle in any one of Claims 1-3, and a fibrous material. An absorbent article comprising the absorber according to claim 4.

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