JP7448301B2 - Water absorbent resin particles, absorbent bodies and absorbent articles containing the same - Google Patents

Description

The present invention relates to water absorbent resin particles, absorbent bodies and absorbent articles containing the same.

Absorbent materials using water-absorbing resin particles used in absorbent articles (disposable diapers, etc.) are usually made by distributing the water-absorbing resin particles evenly in a matrix (also called a fibrous base material) made of cellulose fibers such as pulp. It is produced by holding it and covering it with organic synthetic fibers such as non-woven fabric. However, in actual use, water-absorbing resin particles easily fall off and move due to vibrations and shocks caused by body movement, resulting in uneven distribution within the absorbent body. As a result, efficient diffusion of absorbed substances such as urine is inhibited, leading to problems such as urine leakage and rash. In particular, efforts have been made to reduce so-called pulp (matrix reduction) in response to the increasing need for thinner absorbent articles in recent years, and there is a need for technology to efficiently immobilize water-absorbing resin particles within absorbent bodies.

Conventional techniques for immobilizing water-absorbing resin particles within an absorbent body include (1) a method of applying an adhesive to the surface of a fibrous base material and then adhering the water-absorbing resin particles; (2) a method of adhering water-absorbing resin particles to the surface of a fibrous base material; A known method includes dispersing water-absorbing resin particles in a solvent, coating or impregnating a fibrous base material with the dispersion, and then heating and drying the dispersion to vaporize the organic solvent and fix the dispersion. However, in method (1) above, the fibrous base materials are bonded together using an adhesive that does not participate in adhesion between the water absorbent resin particles and the fibrous base material, so the water absorbent resin particles absorb water and swell. In some cases, this hinders the swelling itself, resulting in problems such as deterioration of absorption performance and handling properties. In addition, method (2) not only deteriorates the absorber properties, but also involves a complicated process of heating and drying the organic solvent and vaporizing it, which is costly, and there are concerns about the safety of the remaining organic solvent.

In addition, as a method to solve the above problem, the surface of water-absorbing resin particles is coated in advance with a heat-fusible resin such as polyolefin resin or a thermoplastic resin containing a hydrophobic block of polyolefin and a block of hydrophilic polymer. However, water-absorbing resin particles that have adhesion to a fibrous base material are known (see Patent Document 1 and Patent Document 2). However, although the resin used for surface coating of these water-absorbing resin particles has a certain effect on immobilizing the water-absorbing resin particles from before to after water absorption, Since it has a high melting point, there is still a problem as to whether or not it will not cause deterioration of the water absorption performance, which is an original property.

Japanese Patent Application Publication No. 6-245958 International Publication No. 2015/178481 pamphlet

The object of the present invention is to provide water-absorbing resin particles that can exhibit sufficient adhesion to a fibrous base material without impairing the water-absorbing performance that is the original property of the water-absorbing resin particles, and The object of the present invention is to provide an absorbent body fixed to a base material, and an absorbent article using the absorbent body.

The present invention provides a crosslinked polymer (A) having as essential constituent units a water-soluble vinyl monomer (a1) and/or a vinyl monomer (a2) that becomes the water-soluble vinyl monomer (a1) upon hydrolysis, and an internal crosslinking agent (b). and a hydrophobic substance (c), the water-absorbing resin particles contain a polyether (d) having a polyoxyalkylene chain on the surface thereof, and the number average molecular weight of (d) is 2,000 or more water-absorbing resin particles; an absorbent body containing the water-absorbing resin particles fixed to a fibrous base material; and an absorbent article using the absorbent body.

The water-absorbing resin particles of the present invention have excellent adhesion to the fiber base material used in the absorbent body while maintaining excellent absorption performance. Therefore, the absorbent body using the water-absorbing resin particles of the present invention and the absorbent article using the same can prevent the water-absorbing resin particles from falling off or becoming uneven in the absorbent body, and can exhibit stable absorption performance.

FIG. 2 is a diagram schematically showing an apparatus for measuring absorption amount by the DW method.

The water-absorbing resin particles of the present invention are crosslinked with a water-soluble vinyl monomer (a1) and/or a vinyl monomer (a2) that becomes the water-soluble vinyl monomer (a1) upon hydrolysis, and an internal crosslinking agent (b) as essential constituent units. Contains a polymer (A) and a hydrophobic substance (c).

The water-soluble vinyl monomer (a1) in the present invention is not particularly limited, and may be a known monomer, for example, at least one water-soluble substituent and an ethylenically insoluble monomer disclosed in paragraphs 0007 to 0023 of Japanese Patent No. 3648553. Vinyl monomers having a saturated group (for example, anionic vinyl monomers, nonionic vinyl monomers, and cationic vinyl monomers), anionic vinyl monomers and nonionic vinyl monomers disclosed in paragraphs 0009 to 0024 of JP 2003-165883 A cationic vinyl monomers and cationic vinyl monomers, and carboxy groups, sulfo groups, phosphono groups, hydroxyl groups, carbamoyl groups, amino groups and ammonio groups disclosed in paragraphs 0041 to 0051 of JP-A No. 2005-75982. A vinyl monomer having at least one of the following can be used.

Vinyl monomer (a2) which becomes water-soluble vinyl monomer (a1) by hydrolysis [hereinafter also referred to as hydrolyzable vinyl monomer (a2)]. ] is not particularly limited, and is known {for example, a vinyl monomer having at least one hydrolyzable substituent that becomes a water-soluble substituent upon hydrolysis as disclosed in paragraphs 0024 to 0025 of Japanese Patent No. 3,648,553; At least one hydrolyzable substituent [1,3-oxo-2-oxapropylene (-CO-O-CO-) group, acyl group and cyano A vinyl monomer having a group such as a vinyl monomer having a vinyl group or the like can be used. Note that the water-soluble vinyl monomer is a concept well known to those skilled in the art, but when expressed in terms of quantity, it means, for example, a vinyl monomer that can dissolve at least 100 g in 100 g of water at 25°C. Moreover, the hydrolyzability of the hydrolyzable vinyl monomer (a2) means, for example, the property of being hydrolyzed by the action of water and, if necessary, a catalyst (acid, base, etc.) and becoming water-soluble. The hydrolyzable vinyl monomer (a2) may be hydrolyzed during polymerization, after polymerization, or both. However, from the viewpoint of the aqueous liquid absorption performance of the resulting water-absorbing resin particles, it is preferable to hydrolyze the hydrolyzable vinyl monomer (a2) after polymerization. preferable.

Among these, the water-soluble vinyl monomer (a1) is preferred from the viewpoint of absorption performance, etc., and the above-mentioned anionic vinyl monomers, carboxy (salt) groups, sulfo (salt) groups, amino groups, and carbamoyl groups are more preferred. , a vinyl monomer having an ammonio group or a mono-, di- or tri-alkylammonio group, more preferably a vinyl monomer having a carboxy (salt) group or a carbamoyl group, particularly preferably a (meth)acrylic acid (salt). and (meth)acrylamide, particularly preferred is (meth)acrylic acid (salt), most preferred is acrylic acid (salt).

Note that "carboxy (salt) group" means "carboxy group" or "carboxylate group", and "sulfo (salt) group" means "sulfo group" or "sulfonate group". Further, (meth)acrylic acid (salt) means acrylic acid, acrylate, methacrylic acid or methacrylate, and (meth)acrylamide means acrylamide or methacrylamide. Examples of the salt include alkali metal (lithium, sodium, potassium, etc.) salts, alkaline earth metal (magnesium, calcium, etc.) salts, ammonium (NH ₄ ) salts, and the like. Among these salts, from the viewpoint of absorption performance and the like, alkali metal salts and ammonium salts are preferred, alkali metal salts are more preferred, and sodium salts are particularly preferred.

When using an acid group-containing monomer such as acrylic acid or methacrylic acid as the water-soluble vinyl monomer (a1), it is preferable that part of the acid group-containing monomer is neutralized with a base from the viewpoint of water absorption performance and residual monomer. . As the base for neutralization, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate, sodium bicarbonate, and potassium carbonate can usually be used. Neutralization may be carried out before, during, after, or both of the above in the production of water-absorbing resin particles. Preferred examples include methods such as neutralizing the acid group-containing polymer in the form of a hydrogel.

Further, when the acid group-containing monomer is used, the degree of neutralization of the acid group is preferably 50 to 80 mol%. If the degree of neutralization is less than 50 mol%, the resulting hydrogel polymer will have high stickiness, and workability during production and use may deteriorate. Furthermore, the water retention amount of the obtained water-absorbing resin particles may decrease. On the other hand, if the degree of neutralization exceeds 80%, the pH of the resulting resin may become high and there may be concerns about safety for human skin.

When using either the water-soluble vinyl monomer (a1) or the hydrolyzable vinyl monomer (a2) as a structural unit, one type of each may be used alone, or two or more types may be used as a structural unit if necessary. good. The same applies when the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as the constituent units. In addition, when the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as constituent units, the molar ratio of their content [(a1)/(a2)] is preferably 75/25 to 99/1. , more preferably 85/15 to 95/5, particularly preferably 90/10 to 93/7. Within this range, the absorption performance will be even better.

In addition to the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), other vinyl monomers (a3) copolymerizable with these may be used as the constituent units of the crosslinked polymer (A). Can be done. The other vinyl monomers (a3) may be used alone or in combination of two or more.

Other vinyl monomers (a3) are not particularly limited and are known (for example, hydrophobic vinyl monomers disclosed in paragraphs 0028 to 0029 of Japanese Patent No. 3648553, paragraphs 0025 of JP 2003-165883, and Hydrophobic vinyl monomers such as the vinyl monomer disclosed in paragraph 0058 of Japanese Patent Publication No. 2005-75982 can be used, and specifically, for example, the following vinyl monomers (i) to (iii) can be used.
(i) Aromatic ethylenic monomers having 8 to 30 carbon atoms Styrene such as styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, and halogen substituted products of styrene such as vinylnaphthalene and dichlorostyrene.
(ii) Aliphatic ethylenic monomers having 2 to 20 carbon atoms Alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkadienes (butadiene, isoprene, etc.).
(iii) Alicyclic ethylenic monomers having 5 to 15 carbon atoms, monoethylenically unsaturated monomers (pinene, limonene, indene, etc.); and polyethylenic vinyl monomers [cyclopentadiene, bicyclopentadiene, ethylidene norbornene, etc.].

The content (mol%) of other vinyl monomer (a3) units is based on the total number of moles of water-soluble vinyl monomer (a1) units and hydrolyzable vinyl monomer (a2) units from the viewpoint of absorption performance, etc. The content of other vinyl monomer (a3) units is preferably from 0 to 5, more preferably from 0 to 3, particularly preferably from 0 to 2, particularly preferably from 0 to 1.5, and from the viewpoint of absorption performance etc. Most preferably, it is 0 mol%.

The internal crosslinking agent (b) is not particularly limited and is known (for example, a crosslinking agent having two or more ethylenically unsaturated groups disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 3648553, which reacts with a water-soluble substituent). A crosslinking agent having at least one functional group capable of reacting with a water-soluble substituent and at least one ethylenically unsaturated group, and a crosslinking agent having at least two functional groups capable of reacting with a water-soluble substituent, JP-A-2003-165883 A crosslinking agent having two or more ethylenically unsaturated groups, a crosslinking agent having an ethylenically unsaturated group and a reactive functional group, and a crosslinking agent having two or more reactive substituents disclosed in paragraphs 0028 to 0031 of the publication. A crosslinking agent such as a crosslinking vinyl monomer disclosed in paragraph 0059 of JP-A No. 2005-75982 and a cross-linking vinyl monomer disclosed in paragraphs 0015 to 0016 of JP-A No. 2005-95759 is used. can. Among these, from the viewpoint of absorption performance, etc., crosslinking agents having two or more ethylenically unsaturated groups are preferred, and more preferred are poly(meth)allyl ethers of polyhydric alcohols having 2 to 40 carbon atoms, and crosslinking agents having two or more ethylenically unsaturated groups. (meth)acrylates of polyhydric alcohols having 2 to 40 carbon atoms, (meth)acrylamides of polyhydric alcohols having 2 to 40 carbon atoms, particularly preferred are polyallyl ethers of polyhydric alcohols having 2 to 40 carbon atoms, most preferred are Pentaerythritol triallyl ether. The internal crosslinking agent (b) may be used alone or in combination of two or more.

The content (mol%) of internal crosslinking agent (b) units is the total number of moles of water-soluble vinyl monomer (a1) units and hydrolyzable vinyl monomer (a2) units, and when using other vinyl monomers (a3), Based on the total number of moles of (a1) to (a3), it is preferably 0.001 to 5, more preferably 0.005 to 3, particularly preferably 0.01 to 1. Within this range, the absorption performance will be even better.

Examples of the polymerization method for the crosslinked polymer (A) include known solution polymerization (adiabatic polymerization, thin film polymerization, spray polymerization, etc.; JP-A-55-133413, etc.), and known reverse-phase suspension polymerization (JP-A No. 55-133413, etc.). 54-30710, JP-A-56-26909, JP-A-1-5808, etc.).

The crosslinked polymer (A) is obtained by polymerizing a monomer composition containing a water-soluble vinyl monomer (a1) and/or a hydrolyzable vinyl monomer (a2) and an internal crosslinking agent (b) as essential components. However, the preferred polymerization method is the solution polymerization method, since it does not require the use of organic solvents and is advantageous in terms of production costs. In addition, the aqueous adiabatic polymerization method is most preferred because it yields a water-absorbing resin with a small amount of water-soluble components and does not require temperature control during polymerization.

When performing aqueous polymerization, a mixed solvent containing water and an organic solvent can be used, and examples of the organic solvent include methanol, ethanol, acetone, methyl ethyl ketone, N,N-dimethylformamide, dimethyl sulfoxide, and two or more of these. A mixture of
When carrying out aqueous solution polymerization, the amount (wt%) of the organic solvent used is preferably 40 or less, more preferably 30 or less, based on the weight of water.

The polymerization concentration, that is, the concentration of the water-soluble vinyl monomer (a1), the hydrolyzable vinyl monomer (a2), and other vinyl monomers (a3) used as necessary, in the polymerization solution is not particularly limited, but i.e., the water-soluble vinyl monomer (a1), the hydrolyzable vinyl monomer (a2), other vinyl monomers (a3) used as necessary, the solvent, the internal crosslinking agent (b), the polymerization catalyst described below, and the polymerization 10-55% is preferred, and 20-45% is more preferred, based on the total weight of control agent. If the polymerization concentration is lower than this range, productivity will be low, and if the polymerization concentration is higher than this range, side reactions such as self-crosslinking will occur, resulting in a decrease in the water retention capacity of the resulting water-absorbing resin particles.

When using a catalyst for polymerization, conventionally known radical polymerization catalysts can be used, such as azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid, and 2,2'-azobis(2-amidinopropane) hydrochloride]. etc.], inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.), organic peroxides [benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide, etc. oxide and di(2-ethoxyethyl) peroxydicarbonate, etc.) and redox catalysts (alkali metal sulfite or bisulfite, ammonium sulfite, ammonium bisulfite, and reducing agents such as ascorbic acid and alkali metal persulfates, ammonium persulfate, hydrogen peroxide, and combinations with oxidizing agents such as organic peroxides). These catalysts may be used alone or in combination of two or more thereof.
The amount (wt%) of the radical polymerization catalyst to be used is the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), or (a1) to (a3) when using the other vinyl monomer (a3). Based on the total weight, 0.0005-5 is preferred, more preferably 0.001-2.

At the time of polymerization, a polymerization control agent such as a chain transfer agent may be used in combination as necessary, and specific examples thereof include sodium hypophosphite, sodium phosphite, alkyl mercaptan, alkyl halide, and thiocarbonyl compounds. etc. These polymerization control agents may be used alone or in combination of two or more thereof.
The amount (wt%) of the polymerization control agent to be used is the amount of the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), or (a1) to (a3) when using the other vinyl monomer (a3). Based on the total weight, 0.0005-5 is preferred, more preferably 0.001-2.

When a suspension polymerization method or a reverse-phase suspension polymerization method is used as the polymerization method, the polymerization may be carried out in the presence of a conventionally known dispersant or surfactant, if necessary. Furthermore, in the case of reverse phase suspension polymerization, polymerization can be carried out using conventionally known hydrocarbon solvents such as xylene, n-hexane, and n-heptane.

The polymerization initiation temperature can be appropriately adjusted depending on the type of catalyst used, but is preferably 0 to 100°C, more preferably 2 to 80°C.

The hydrogel obtained by polymerization can be shredded as necessary before drying. The size of the gel after shredding (longest diameter) is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, particularly preferably 1 mm to 1 cm. Within this range, the drying properties in the drying step will be even better.

Shredding can be performed by a known method, using a shredding device (for example, a Bex mill, a rubber chopper, a Pharma mill, a mincer, an impact crusher, a roll crusher), or the like.

Methods for distilling off the solvent (including water) of the hydrogel and drying include distilling off (drying) with hot air at a temperature of 80 to 230°C, using a drum dryer heated to 100 to 230°C, etc. Thin film drying method, (heating) vacuum drying method, freeze drying method, infrared ray drying method, decantation, filtration, etc. can be applied.

When the solvent contains water, the water content (wt%) after drying is preferably from 0 to 20, more preferably from 1 to 10, particularly preferably from 2 to 9, most preferably from 2 to 9, based on the weight of the crosslinked polymer (A). Preferably it is 3-8. Within this range, the absorption performance will be even better. Further, when the solvent contains an organic solvent, the content (wt%) of the organic solvent after distillation is preferably 0 to 10, more preferably 0 to 5, based on the weight of the crosslinked polymer (A). Particularly preferably from 0 to 3, most preferably from 0 to 1. Within this range, the absorption performance of the water-absorbing resin particles becomes even better.

The organic solvent content and moisture content were determined using an infrared moisture meter [KETT JE400, etc.: 120±5°C, 30 minutes, atmospheric humidity before heating 50±10%RH, lamp specification 100V, 40W] from the weight loss of the measurement sample when heated.

The crosslinked polymer (A) can be crushed and classified as necessary to obtain resin particles containing the crosslinked polymer (A). There are no particular limitations on the pulverization method, and pulverizers (for example, hammer-type pulverizers, impact-type pulverizers, roll-type pulverizers, Schette air-flow pulverizers), etc. can be used. The particle size of the pulverized crosslinked polymer can be adjusted by sieving or the like, if necessary.

The weight average particle diameter (μm) of the resin particles containing the crosslinked polymer (A) is preferably 100 to 500, more preferably 150 to 480, particularly preferably 200 to 450. Within this range, the absorption performance of the water-absorbing resin particles becomes even better. Further, from the viewpoint of absorption performance, the content (% by weight) of fine particles of 150 μm or less in the total weight of the resin particles containing the crosslinked polymer (A) is preferably 3 or less, more preferably 1 or less.

The weight average particle diameter and the content of fine particles of 150 μm or less were determined using a low-tap test sieve shaker and a standard sieve (JIS Z8801-1:2006), according to Perry's Chemical Engineers Handbook 6th Edition (Mac). Grow-Hill Book Company, 1984, p. 21). That is, JIS standard sieves are assembled in the following order from the top: 1000 μm, 850 μm, 710 μm, 500 μm, 425 μm, 355 μm, 250 μm, 150 μm, 125 μm, 75 μm, and 45 μm, and a saucer. Approximately 50 g of the particles to be measured are placed in the top sieve and shaken for 5 minutes using a low-tap test sieve shaker. Weigh the particles to be measured on each sieve and saucer, take the total as 100% by weight, determine the weight fraction of particles on each sieve, and compare this value with logarithmic probability paper [the horizontal axis is the sieve opening (particle diameter ), the vertical axis is the weight fraction], a line is drawn connecting each point, the particle diameter corresponding to a weight fraction of 50% by weight is determined, and this is defined as the weight average particle diameter. Further, the content of fine particles can be determined using the graph created when determining the weight average particle diameter described above.

There is no particular limitation on the shape of the resin particles containing the crosslinked polymer (A), and examples thereof include amorphous crushed shapes, flaky shapes, pearl shapes, and rice grain shapes. Among these, amorphous crushed particles are preferable from the viewpoint of good entanglement with fibrous materials for use in disposable diapers, etc., and no fear of falling off from the fibrous materials.

Note that the resin particles containing the crosslinked polymer (A) may contain other components such as a residual solvent and a residual crosslinking component to some extent as long as their performance is not impaired.

The water absorbent resin particles of the present invention contain a hydrophobic substance (c). By containing the hydrophobic substance (c), it is possible to improve the deterioration of dryness caused by polyether, which will be described later. The hydrophobic substance (c) is preferably a hydrophobic substance (c1) containing a hydrocarbon group having 8 to 30 carbon atoms and/or a hydrophobic substance (c2) which is an organic polysiloxane.

Hydrophobic substances (c1) containing a hydrocarbon group having 8 to 30 carbon atoms include long-chain fatty acid esters, long-chain fatty acids and salts thereof, long-chain aliphatic alcohols, long-chain aliphatic amides, and surfactants with an HLB of 10 or less. These include agents, waxes, mixtures of two or more of these, and the like.

Long-chain fatty acid esters include esters of fatty acids with 8 to 30 carbon atoms and alcohols with 1 to 12 carbon atoms {for example, methyl laurate, ethyl laurate, methyl stearate, ethyl stearate, methyl oleate, oleic acid Ethyl, glycerin lauric acid monoester, glycerin stearic acid monoester, glycerin oleic acid monoester, pentaerythritol lauric acid monoester, pentaerythritol stearic acid monoester, pentaerythritol oleic acid monoester, sorbitol lauric acid monoester, sorbitol stearate monoester, sorbitoleate monoester, sucrose palmitate monoester, sucrose palmitate diester, sucrose palmitate triester, sucrose stearate and beef tallow.

Examples of long chain fatty acids and their salts include fatty acids having 8 to 30 carbon atoms (for example, lauric acid, palmitic acid, stearic acid, oleic acid, and behenic acid), and examples of their salts include zinc, calcium, magnesium or Examples include salts with aluminum (hereinafter abbreviated as Zn, Ca, Mg, Al) {for example, Ca palmitate, Al palmitate, Ca stearate, Mg stearate, Al stearate, etc.}.

Examples of the long-chain aliphatic alcohol include aliphatic alcohols having 8 to 30 carbon atoms (eg, lauryl alcohol, palmityl alcohol, stearyl alcohol, oleyl alcohol, etc.). From the viewpoint of leakage resistance of the absorbent article, palmityl alcohol, stearyl alcohol, and oleyl alcohol are preferred, and stearyl alcohol is more preferred.

Examples of the long-chain aliphatic amide include an amidation product of a long-chain aliphatic primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms, ammonia, or a primary amine having 1 to 7 carbon atoms. and a long-chain fatty acid having 8 to 30 carbon atoms; amidation products of a long-chain aliphatic secondary amine having at least one aliphatic chain having 8 to 30 carbon atoms and a carboxylic acid having 1 to 30 carbon atoms; and Examples include amidation products of secondary amines having two aliphatic hydrocarbon groups having 1 to 7 carbon atoms and long-chain fatty acids having 8 to 30 carbon atoms.

An amidated product of a long-chain aliphatic primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms includes a product obtained by reacting a primary amine and a carboxylic acid at a ratio of 1:1, and 1 :Divided into 2 reacted substances. Examples of substances reacted at a ratio of 1:1 include acetic acid N-octylamide, acetic acid N-hexacosylamide, heptacanoic acid N-octylamide, and heptacanoic acid N-hexacosylamide. Examples of those reacted at a ratio of 1:2 include diacetic acid N-octylamide, diacetic acid N-hexacosylamide, diheptacanoic acid N-octylamide, and diheptacanoic acid N-hexacosylamide. In addition, in the case of a product obtained by reacting a primary amine and a carboxylic acid at a ratio of 1:2, the carboxylic acids used may be the same or different.

As the amidated product of ammonia or a primary amine having 1 to 7 carbon atoms and a long chain fatty acid having 8 to 30 carbon atoms, a 1:1 reaction of ammonia or a primary amine with a carboxylic acid and a 1:2 reaction of ammonia or a primary amine with a carboxylic acid are available. It can be divided into reactants. Products reacted at a ratio of 1:1 include nonanoic acid amide, nonanoic acid methylamide, nonanoic acid N-heptylamide, heptacanoic acid amide, heptacanoic acid N-methylamide, heptacanoic acid N-heptylamide, and heptacosanoic acid N-hexacosylamide. etc. Those reacted at a ratio of 1:2 include dinonanoic acid amide, dinonanoic acid N-methylamide, dinonanoic acid N-heptylamide, dioctadecanoic acid amide, dioctadecanoic acid N-ethylamide, dioctadecanoic acid N-heptylamide, diheptacanoic acid amide , diheptacosanoic acid N-methylamide, diheptacosanoic acid N-heptylamide, diheptacosanoic acid N-hexacosylamide, and the like. In addition, as a product obtained by reacting ammonia or a primary amine with a carboxylic acid at a ratio of 1:2, the carboxylic acids used may be the same or different.

Examples of amidated products of long-chain aliphatic secondary amines having at least one aliphatic chain having 8 to 30 carbon atoms and carboxylic acids having 1 to 30 carbon atoms include acetic acid N-methyloctylamide, acetic acid N-methylhexacylamide, and acetic acid N-methyloctylamide. ruamide, acetic acid N-octylhexacosylamide, acetic acid N-dihexacosylamide, heptacanoic acid N-methyloctylamide, heptacanoic acid N-methylhexacosylamide, heptacanoic acid N-octylhexacosylamide and heptacosane Examples include acid N-dihexacosylamide and the like.

Examples of amidated products of a secondary amine having two aliphatic hydrocarbon groups having 1 to 7 carbon atoms and a long chain fatty acid having 8 to 30 carbon atoms include nonanoic acid N-dimethylamide, nonanoic acid N-methylheptylamide, Examples include nonanoic acid N-diheptylamide, heptacanoic acid N-dimethylamide, heptacanoic acid N-methylheptylamide, and heptacosanoic acid N-diheptylamide.

Examples of surfactants with an HLB of 10 or less include alkylene oxide (hereinafter abbreviated as AO) type nonionic surfactants and polyhydric alcohol type nonionic surfactants.
The HLB value means a hydrophilic-hydrophobic balance (HLB) value, and is determined by the Oda method (Introduction to Surfactants, p. 212, Takehiko Fujimoto, published by Sanyo Chemical Industries, Ltd., 2007).

AO-added nonionic surfactants are produced by directly adding AO to higher alcohols, higher fatty acids, or alkylamines, or by reacting higher fatty acids with polyalkylene glycols obtained by adding AO to glycols. Alternatively, it can be obtained by adding AO to an esterified product obtained by reacting a polyhydric alcohol with a higher fatty acid, or by adding AO to a higher fatty acid amide.

Examples of AO include ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), and butylene oxide (hereinafter abbreviated as BO). Preferred among these are EO single adducts and random or block adducts of EO and PO.

Specific examples of AO adduct type nonionic surfactants include oxyalkylene alkyl ethers (e.g., octyl alcohol EO adduct, lauryl alcohol EO adduct, stearyl alcohol EO adduct, oleyl alcohol EO adduct, lauryl alcohol EO/PO block adducts, etc.); polyoxyalkylene higher fatty acid esters (e.g., stearic acid EO adducts, lauric acid EO adducts, etc.); polyoxyalkylene polyhydric alcohol higher fatty acid esters (e.g., lauric acid diesters of polyethylene glycol, polyethylene glycol oleic acid diester of polyethylene glycol, stearic acid diester of polyethylene glycol, etc.); polyoxyalkylene alkylphenyl ether (e.g., nonylphenol EO adduct, nonylphenol EO/PO block adduct, octylphenol EO adduct, bisphenol A/EO adduct, dinonylphenol) EO adducts, styrenated phenol EO adducts, etc.); polyoxyalkylene alkylamino ethers (e.g. laurylamine EO adducts, stearylamine EO adducts, etc.); polyoxyalkylene alkyl alkanolamides (e.g. hydroxyethyl lauric acid); EO adducts of amide, EO adducts of hydroxypropyloleic acid amide, EO adducts of dihydroxyethyllauric acid amide, etc.).

Examples of polyhydric alcohol type nonionic surfactants include polyhydric alcohol fatty acid esters, polyhydric alcohol fatty acid ester AO adducts, polyhydric alcohol alkyl ethers, and polyhydric alcohol alkyl ether AO adducts.

Specific examples of polyhydric alcohol fatty acid esters include pentaerythritol monolaurate, pentaerythritol monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan monolaurate, sorbitan dilaurate, sorbitan diolate, sucrose monostearate, etc. can be mentioned.
Specific examples of polyhydric alcohol fatty acid ester AO adducts include ethylene glycol monooleate EO adduct, ethylene glycol monostearate EO adduct, trimethylolpropane monostearate EO/PO random adduct, and sorbitan monolaurate EO adduct. sorbitan monostearate EO adduct, sorbitan distearate EO adduct, sorbitan dilaurate EO/PO random adduct, and the like.
Specific examples of polyhydric alcohol alkyl ethers include pentaerythritol monobutyl ether, pentaerythritol monolauryl ether, sorbitan monomethyl ether, sorbitan monostearyl ether, methyl glycoside, lauryl glycoside, and the like.
Specific examples of polyhydric alcohol alkyl ether AO adducts include sorbitan monostearyl ether EO adducts, methyl glycoside EO/PO random adducts, lauryl glycoside EO adducts, stearyl glycoside EO/PO random adducts, and the like.

Examples of the wax include waxes having a melting point of 50 to 200° C. (eg, paraffin wax, beeswax, carnauba wax, beef tallow, etc.).

Examples of the hydrophobic substance (c2) which is an organic polysiloxane include polydimethylsiloxane, polyether-modified polysiloxane {polyoxyethylene-modified polysiloxane and poly(oxyethylene/oxypropylene)-modified polysiloxane, etc.}, carboxy-modified polysiloxane, Included are epoxy-modified polysiloxanes, amino-modified polysiloxanes, alkoxy-modified polysiloxanes, and mixtures thereof.

There is no particular limitation on the position of the organic group (modifying group) of modified silicone {polyether-modified polysiloxane, carboxy-modified polysiloxane, epoxy-modified polysiloxane, amino-modified polysiloxane, etc.}, but the side chain of polysiloxane, polysiloxane It may be at both ends of the polysiloxane, at one end of the polysiloxane, or at both the side chain and both ends of the polysiloxane. Among these, from the viewpoint of absorption characteristics, both the side chain of polysiloxane and the side chain and both ends of polysiloxane are preferred, and both the side chain and both ends of polysiloxane are more preferred.

The organic group (modified group) of the polyether-modified polysiloxane includes a group containing a polyoxyethylene group or a poly(oxyethylene/oxypropylene) group. The content (number) of oxyethylene groups and/or oxypropylene groups contained in the polyether-modified polysiloxane is preferably 2 to 40, more preferably 5 to 30, particularly preferably 5 to 30, per molecule of polyether-modified polysiloxane. 7-20, most preferably 10-15. Within this range, the absorption characteristics will be even better. When containing oxyethylene groups and oxypropylene groups, the content (wt%) of oxyethylene groups is preferably 1 to 30, more preferably 3 to 25, particularly preferably 5 ~20. Within this range, the absorption characteristics will be even better.

Polyether-modified polysiloxanes are easily available on the market, and the following products {position of modification, type of oxyalkylene} are preferred examples.
・Shin-Etsu Chemical Co., Ltd. KF-945 {side chain, oxyethylene and oxypropylene}, KF-6020 {side chain, oxyethylene and oxypropylene}, KF-351A {side chain, oxyethylene and oxypropylene}, X -22-6191 {side chain, oxyethylene and oxypropylene}, X-22-4952 {side chain, oxyethylene and oxypropylene}, X-22-4272 {side chain, oxyethylene and oxypropylene}, X-22 -6266 {side chain, oxyethylene and oxypropylene}

・Manufactured by Dow Corning Toray Co., Ltd. FZ-2110 {Both ends, oxyethylene and oxypropylene}, FZ-2122 {Both ends, oxyethylene and oxypropylene}, FZ-7006 {Both ends, oxyethylene and oxypropylene}, FZ-2166 {Both ends, oxyethylene and oxypropylene}, FZ-2164 {Both ends, oxyethylene and oxypropylene}, FZ-2154 {Both ends, oxyethylene and oxypropylene}, FZ-2203 {Both ends, oxy ethylene and oxypropylene} and FZ-2207 {both ends, oxyethylene and oxypropylene}

The organic group (modified group) of carboxy-modified polysiloxane includes a group containing a carboxy group, etc., and the organic group (modified group) of epoxy-modified polysiloxane includes a group containing an epoxy group, etc. The organic group (modified group) of polysiloxane includes a group containing an amino group (primary, secondary, or tertiary amino group). The content (g/mol) of organic groups (modified groups) in these modified silicones is preferably 200 to 11,000, more preferably 600 to 8,000, particularly preferably 1,000 to 4,000 as carboxy equivalent, epoxy equivalent, or amino equivalent. It is. Within this range, the absorption characteristics will be even better. Note that the carboxy equivalent is measured in accordance with "16. Total acid value test" of JIS C2101:1999. Further, the epoxy equivalent is determined in accordance with JIS K7236:2001. In addition, the amino equivalent is measured in accordance with "8. Potentiometric titration method (base number/hydrochloric acid method)" of JIS K2501:2003.

Carboxy-modified polysiloxanes are easily available on the market, and the following products (modification position, carboxy equivalent (g/mol)) are preferred examples.
・Manufactured by Shin-Etsu Chemical Co., Ltd. X-22-3701E {side chain, 4000}, X-22-162C {both ends, 2300}, X-22-3710 {one end, 1450}

・Dow Corning Toray Co., Ltd. BY16-880 {side chain, 3500}, BY16-750 {both ends, 750}, BY16-840 {side chain, 3500}, SF8418 {side chain, 3500}

Epoxy-modified polysiloxanes are easily available on the market, and the following products {modification position, epoxy equivalent} are preferred examples.
- Shin-Etsu Chemical Co., Ltd. X-22-343 {side chain, 525}, KF-101 {side chain, 350}, KF-1001 {side chain, 3500}, X-22-2000 {side chain, 620} , X-22-2046 {side chain, 600}, KF-102 {side chain, 3600}, X-22-4741 {side chain, 2500}, KF-1002 {side chain, 4300}, X-22-3000T {side chain, 250}, X-22-163 {both ends, 200}, KF-105 {both ends, 490}, X-22-163A {both ends, 1000}, X-22-163B {both ends, 1750}, X-22-163C {both ends, 2700}, X-22-169AS {both ends, 500}, X-22-169B {both ends, 1700}, X-22-173DX {one end, 4500} , X-22-9002 {side chain/both ends, 5000}

・Manufactured by Dow Corning Toray Co., Ltd. FZ-3720 {side chain, 1200}, BY16-839 {side chain, 3700}, SF8411 {side chain, 3200}, SF8413 {side chain, 3800}, SF8421 {side chain, 11000} }, BY16-876{side chain, 2800}, FZ-3736{side chain, 5000}, BY16-855D{side chain, 180}, BY16-8{side chain, 3700}

Amino-modified silicones are easily available on the market, and the following products {modification position, amino equivalent} are preferred examples.
・Manufactured by Shin-Etsu Chemical Co., Ltd. KF-865 {side chain, 5000}, KF-864 {side chain, 3800}, KF-859 {side chain, 6000}, KF-393 {side chain, 350}, KF-860 {side chain, 7600}, KF-880 {side chain, 1800}, KF-8004 {side chain, 1500}, KF-8002 {side chain, 1700}, KF-8005 {side chain, 11000}, KF-867 {Side chain, 1700}, X-22-3820W {Side chain, 55000}, KF-869 {Side chain, 8800}, KF-861 {Side chain, 2000}, X-22-3939A {Side chain, 1500} , KF-877 {side chain, 5200}, PAM-E {both ends, 130}, KF-8010 {both ends, 430}, X-22-161A {both ends, 800}, X-22-161B {both Terminal, 1500}, KF-8012 {Both ends, 2200}, KF-8008 {Both ends, 5700}, X-22-1660B-3 {Both ends, 2200}, KF-857 {Side chain, 2200}, KF -8001 {side chain, 1900}, KF-862 {side chain, 1900}, X-22-9192 {side chain, 6500}

・Manufactured by Dow Corning Toray Co., Ltd. FZ-3707 {side chain, 1500}, FZ-3504 {side chain, 1000}, BY16-205 {side chain, 4000}, FZ-3760 {side chain, 1500}, FZ- 3705{side chain, 4000}, BY16-209{side chain, 1800}, FZ-3710{side chain, 1800}, SF8417{side chain, 1800}, BY16-849{side chain, 600}, BY16-850{ Side chain, 3300}, BY16-879B{side chain, 8000}, BY16-892{side chain, 2000}, FZ-3501{side chain, 3000}, FZ-3785{side chain, 6000}, BY16-872{ side chain, 1800}, BY16-213{side chain, 2700}, BY16-203{side chain, 1900}, BY16-898{side chain, 2900}, BY16-890{side chain, 1900}, BY16-893{ Side chain, 4000}, FZ-3789 {side chain, 1900}, BY16-871 {both ends, 130}, BY16-853C {both ends, 360}, BY16-853U {both ends, 450}

Examples of these mixtures include mixtures of polydimethylsiloxane and carboxyl-modified polysiloxane, and mixtures of polyether-modified polysiloxane and amino-modified polysiloxane.

The viscosity (mPa·s, 25° C.) of the organic polysiloxane hydrophobic substance is preferably 10 to 5,000, more preferably 15 to 3,000, particularly preferably 20 to 1,500. Within this range, the absorption characteristics will be even better. The viscosity is determined according to JIS Z8803-1991 "Viscosity of liquid" 9. Measured in accordance with the viscosity measurement method using a cone and a cone-plate rotational viscometer {for example, an E-type viscometer (RE80L manufactured by Toki Sangyo Co., Ltd., radius 7 mm) whose temperature is adjusted to 25.0 ± 0.5°C. , a conical cone with an angle of 5.24×10 ⁻² rad). }

Among these hydrophobic substances (c), from the viewpoint of drying properties of absorbent articles, long chain fatty acid esters, long chain fatty acid salts, long chain fatty acid alcohols, quaternary ammonium salt type surfactants, polysiloxane structures Hydrophobic substances having the following are preferred, and more preferred are glycerin stearate monoester, glycerin stearate diester, sucrose stearate, stearyl alcohol, dimethyl distearyl ammonium chloride, amino-modified polysiloxane, carboxy-modified polysiloxane, and polyether-modified Particularly preferred polysiloxanes are glycerin stearate diester, sucrose stearate, stearyl alcohol, dimethyl distearyl ammonium chloride, carboxy-modified polysiloxane, and polyether-modified polysiloxane.

The content (wt%) of the hydrophobic substance (c) is preferably 0.001 to 5.0, more preferably 0.008 to 1.0, particularly preferably 0.001 to 5.0, based on the weight of the crosslinked polymer (A). is 0.01 to 0.16. This range is preferable because the absorbent article has excellent drying properties.

The hydrophobic substance (c) may be added in any process such as the polymerization process, the gel crushing process, or the surface crosslinking process described below, but from the viewpoint of absorption characteristics, the hydrophobic substance should be added to the water-absorbing resin. It is preferably present inside the particles, and is added to the polymerization solution after the start of the polymerization process of the crosslinked polymer (A) but before the completion of the polymerization process, or before the completion of the drying process of the hydrogel after the completion of the polymerization process. It is preferable to mix the hydrophobic substance (c) into the hydrogel of the crosslinked polymer (A) at some point.

The hydrophobic substance (c) can also be used in dissolved and/or dispersed form in water and/or a volatile solvent.

The water-absorbing resin particles of the present invention preferably have a structure in which the resin particles containing the crosslinked polymer (A) are surface-crosslinked with at least one surface crosslinking agent. By crosslinking the surface of the resin particles, the gel strength of the water-absorbing resin particles can be improved, and the desired water retention amount and absorption amount under load of the water-absorbing resin particles can be satisfied. As the surface crosslinking agent, known (such as polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds, and polyvalent isocyanate compounds described in JP-A-59-189103, JP-A-58-180233 and JP-A Polyhydric alcohols disclosed in JP-A No. 61-16903, silane coupling agents described in JP-A-61-211305 and JP-A-61-252212, alkylene carbonates described in Japanese Patent Application Publication No. 5-508425, Surface crosslinking agents such as polyvalent oxazoline compounds described in JP-A-11-240959 and polyvalent metals described in JP-A-51-136588 and JP-A-61-257235 can be used. Among these surface crosslinking agents, polyglycidyl compounds, polyhydric alcohols, and polyhydric amines are preferred, polyglycidyl compounds and polyhydric alcohols are more preferred, and polyhydric alcohols are particularly preferred. most preferred is ethylene glycol diglycidyl ether. One type of surface crosslinking agent may be used alone, or two or more types may be used in combination.

The amount (wt%) of the surface crosslinking agent to be used is not particularly limited, as it can be varied depending on the type of surface crosslinking agent, conditions for crosslinking, target performance, etc.; Based on the weight of the water-absorbing resin particles containing aggregate (A), it is preferably 0.001 to 3, more preferably 0.005 to 2, particularly preferably 0.01 to 1.

As a method for surface treatment with a surface crosslinking agent, known methods {for example, Japanese Patent No. 3648553, Japanese Patent Application Publication No. 2003-165883, Japanese Patent Application Publication No. 2005-75982, and Japanese Patent Application Publication No. 2005-95759} can be applied. .

After performing the surface treatment step with a surface crosslinking agent, the particle size may be adjusted by further sieving.

The water-absorbing resin particles of the present invention contain polyether (d) (also simply referred to as polyether (d)) having a polyoxyalkylene chain on the surface of the water-absorbing resin particles. By containing polyether (d) on the surface of the water-absorbing resin particles, it exhibits adhesion to the fibrous base material in the absorber.

Examples of the polyether (d) having a polyoxyalkylene chain include those obtained by adding alkylene oxide to an active hydrogen compound. One or both terminals of the polyether (d) may be a hydroxyl group, or the hydroxyl group may be an ester with a monovalent aliphatic carboxylic acid having 1 to 32 carbon atoms.

Examples of the active hydrogen compound include a compound having at least one functional group selected from the group consisting of a hydroxyl group, an amino group, a carboxyl group, a thiol group, and an imino group, water, and ammonia. These may be used alone or in combination of two or more.

Examples of compounds having hydroxyl groups include monohydric alcohols, dihydric alcohols, trihydric alcohols, tetrahydric to octahydric alcohols, monohydric phenols, and polyhydric phenols. Examples of the monohydric alcohol include aliphatic monohydric alcohols having 1 to 24 carbon atoms (methanol, ethanol, propanol, butanol, 2-ethylhexanol, lauryl alcohol, cetyl alcohol, oleyl alcohol, etc.). Examples of the dihydric alcohol include aliphatic dihydric alcohols having 2 to 20 carbon atoms. Examples of aliphatic dihydric alcohols having 2 to 20 carbon atoms include straight chain aliphatic dihydric alcohols having 2 to 8 carbon atoms (ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5 -pentanediol and 1,6-hexanediol), branched aliphatic dihydric alcohols having 2 to 8 carbon atoms (1,2-propylene glycol, 1,2-, 1,3- or 2,3-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, etc.), alicyclic dihydric alcohol having 6 to 10 carbon atoms [1,4-bis(hydroxy cyclohexane and 2,2-bis(4-hydroxycyclohexyl)propane] and aromatic ring-containing dihydric alcohols having 8 to 20 carbon atoms [m- or p-xylylene glycol, bis(hydroxyethyl)benzene and bis( hydroxyethoxy)benzene] and the like. Examples of the trihydric alcohol include trihydric alcohols having 3 to 24 carbon atoms (glycerin, trimethylolpropane, etc.). Examples of the 4- to 8-hydric alcohol include 4- to 8-hydric alcohols having 5 to 24 carbon atoms (pentaerythritol, diglycerin, triglycerin, α-methylglucoside, sorbitol, xylit, mannitol, dipentaerythritol, tripentaerythritol, glucose). , fructose, sucrose, partial esterification products thereof, etc.). Monohydric phenols and polyhydric phenols include monohydric phenols with 6 to 24 carbon atoms (phenol, cresol, naphthol, etc.), divalent phenols with 6 to 100 carbon atoms [catechol, hydroquinone, and bisphenol (bisphenol H, bisphenol S, etc.) and bisphenol F), and trivalent or higher phenols having 6 to 100 carbon atoms (pyrogallol, hexahydroxybenzene, novolak resin, etc.).

Examples of compounds containing amino groups include monovalent amines, divalent amines, and trivalent or higher amines. Monovalent amines include aliphatic monoamines having 1 to 20 carbon atoms (methylamine, ethylamine, diethylamine, diisopropylamine, dibutylamine, etc.) and aromatic monoamines having 6 to 24 carbon atoms (aniline, naphthylamine, and 2,4,6 -trimethylaniline, etc.). Examples of divalent amines include aliphatic diamines having 2 to 24 carbon atoms (ethylene diamine, propylene diamine, hexamethylene diamine, etc.) and aromatic diamines having 2 to 24 carbon atoms (aniline, phenylene diamine, tolylene diamine, xylylene diamine, etc.). (diethyltoluene diamine, methylene dianiline, diphenyl ether diamine, naphthalene diamine, anthracene diamine, etc.). Examples of trivalent or higher valent amines include tri-, hexa-, or pentaamines having 2 to 24 carbon atoms; Examples include amines (aniline, 4-methylaniline, 1,4-phenylenediamine and 4,4'-diaminobiphenyl), and the like. In addition to these compounds, examples of compounds containing amino groups include heterocyclic polyamines (piperazine and N-aminoethylpiperazine, etc.), polyamide polyamines obtained by condensation of dicarboxylic acid and excess polyamine, and hydrazine (hydrazine and monoalkylhydrazine). etc.), dihydrazides (succinic acid dihydrazide, terephthalic acid dihydrazide, etc.), guanidine (butylguanidine, 1-cyanoguanidine, etc.), and dicyandiamide.

Examples of the compound having a carboxyl group include monovalent carboxylic acids, divalent carboxylic acids, and trivalent or higher carboxylic acids. Examples of monovalent carboxylic acids include monovalent carboxylic acids having 1 to 24 carbon atoms (such as formic acid, acetic acid, propionic acid, butyric acid, octanoic acid, lauric acid, oleic acid, and linoleic acid). Examples of divalent carboxylic acids include divalent carboxylic acids having 4 to 24 carbon atoms (maleic acid, succinic acid, adipic acid, phthalic acid, etc.). Examples of trivalent or higher carboxylic acids include trivalent or higher carboxylic acids having 6 to 24 carbon atoms (tricarballylic acid, trimellitic acid, pyromellitic acid, trimer to octamer of acrylic acid, etc.).

Examples of compounds having a thiol group include monovalent thiols having 1 to 24 carbon atoms (methanethiol, 1-propanethiol, phenylmethanethiol, thiophenol, etc.) and divalent or higher thiols having 1 to 24 carbon atoms (1,2 -ethanedithiol and 1,4-butanedithiol).

Examples of the compound having an imino group include monocarboxylic acid amides (oleic acid amide, etc.) and dimers to unsaturated monocarboxylic acid amides (monocarboxylic acid amides include acrylamide, methacrylamide, etc.).

Examples of the compound having at least one functional group selected from the group consisting of a hydroxyl group, an amino group, a carboxyl group, a thiol group, and an imino group include compounds having a hydroxyl group and an amino group. Examples of the compound having a hydroxyl group and an amino group include alkanolamines (monoethanolamine, diethanolamine, triethanolamine, etc.).

Among these active hydrogen compounds, from the viewpoint of water absorption properties, monohydric alcohols and dihydric alcohols are preferred, aliphatic monohydric alcohols and dihydric alcohols having 2 to 8 carbon atoms are more preferred, and ethylene is particularly preferred. Glycol, diethylene glycol.

In addition, active hydrogen compounds include the above-mentioned compounds having a hydroxyl group, compounds having an amino group, compounds having a carboxyl group, compounds having a thiol group, and compounds having an imino group, as well as hydroxyl groups, amino groups, carboxyl groups, and thiol groups. It is also possible to use a polymeric active hydrogen compound, which is a polymeric compound having at least one functional group selected from the group consisting of groups and imino groups.

Examples of the alkylene oxide include ethylene oxide, alkylene oxide having 3 or 4 carbon atoms, and alkylene oxide having 5 to 8 carbon atoms.

Examples of the alkylene oxide having 3 or 4 carbon atoms include 1,2- or 1,3-propylene oxide, 1,2-, 1,3- or 2,3-butylene oxide, tetrahydrofuran, and styrene oxide. Examples of the alkylene oxide having 5 to 8 carbon atoms include 1,2-pentylene oxide and styrene oxide. One type of alkylene oxide may be used alone or two or more types may be used in combination, and when two or more types are used in combination, they may be added in a block form (chip type, balanced type, active secondary type, etc.). , may be added in a random format, or a block format and a random format may be mixed. As for whether the addition format is random or block format when two or more alkylene oxides are used together, various NMR analyzes applying Without-NOE measurement ( ^1H , ^13C , DEPT, HMQC), and It can be analyzed by mass spectrometry (ionization method: ESI-MS).

Examples of the polyoxyalkylene chain contained in the polyether (d) in the present invention include polyoxyethylene chains, polyoxypropylene chains, polytetramethylene chains, and copolymer chains thereof.

Among these polyoxyalkylene chains, polyoxyethylene chains and copolymer chains of polyoxyethylene and polyoxypropylene are preferred, and polyoxyethylene chains are more preferred, from the viewpoint of water absorption properties and fixing properties.

Examples of the polyether (d) having a polyoxyalkylene chain include, for example, polyethers using one type of alkylene oxide include polyethylene glycol, polypropylene glycol, polyoxetane, polytetramethylene glycol, and polystyrene glycol; Examples of polyethers that use a combination of alkylene oxides include polyoxyethylene/polyoxypropylene glycol, polyoxyethylene/polyoxytetramethylene glycol, and polyoxypropylene that are added in block form or random form using two types of alkylene oxides. - Polyoxytetramethylene glycol, polyoxyethylene/polyoxetane, polyoxyethylene/polystyrene glycol, polyoxypropylene/polystyrene glycol, polyoxetane/polystyrene glycol, polyoxytetramethylene/polystyrene glycol, etc.

Among these polyethers (d) having a polyoxyalkylene chain, polyethers having a polyoxyethylene chain are preferred from the viewpoint of water absorption properties and fixing properties, and more preferably polyethylene glycol, polyoxyethylene alkyl ether, and polyoxyethylene chain. A block copolymer of ethylene/polyoxypropylene glycol, particularly preferably polyethylene glycol.

The number average molecular weight (hereinafter abbreviated as Mn) of the polyether (d) is 2,000 or more, preferably 5,000 to 100,000, and more preferably 6,000 to 20,000. If Mn is less than 2000, the melting point will be low, and the adhesion and absorption performance of the water absorbent resin will be reduced, and the handleability will be deteriorated due to stickiness. On the other hand, although there is no upper limit, if Mn is greater than 100,000, hydrophilicity may decrease and absorption characteristics may decrease.

Mn of polyether (d) can be measured using gel permeation chromatography (hereinafter abbreviated as GPC), for example, under the following conditions.
・Device: "Waters Alliance 2695" [manufactured by Waters]
・Column: "Guardcolumn Super HL" (1 column), "TSKgel SuperH2000, TSKgel SuperH3000, and TSKgel SuperH4000 connected one each" [all manufactured by Tosoh Corporation]
・Sample solution: 0.25% by weight tetrahydrofuran solution ・Solution injection amount: 10 μL
・Flow rate: 0.6mL/min ・Measurement temperature: 40℃
・Detection device: Refractive index detector ・Reference material: Standard polyethylene glycol

The polyether (d) in the present invention is preferably water-soluble. By being water-soluble, it is possible to impart adhesion properties without reducing the original water-absorbing properties of the water-absorbing resin particles. In the present invention, the term "water-soluble polyether" refers to a polyether having a solubility in water at 25° C. of 5 g or more per 100 g of water.

The melting point (hereinafter abbreviated as Tm) of the polyether (d) is preferably 50 to 150°C, more preferably 50 to 100°C. If the Tm is less than 50°C, there is a concern that it will melt near room temperature and the adhesion will be reduced. If the Tm is greater than 150°C, the polyether will need to be melted in the high-speed line of diapers that are actually manufactured. There is a concern that the temperature will not be reached.

The melting point of polyether is determined by the endotherm when the temperature is raised from -20°C to 200°C at a heating rate of 20°C/min using differential scanning calorimetry [DSC20, SSC/580 manufactured by Seiko Instruments Inc.]. It is determined by measuring the peak [°C].

The content (wt%) of polyether (d) is preferably 0.5 to 5.0, more preferably 0.8 to 4.0, particularly preferably 1.0 to 5.0, based on the weight of the water-absorbing resin particles. It is 0 to 3.0. If the content of polyether (d) is less than 0.5, the adhesion of the water-absorbing resin will decrease, and if it is more than 5.0, the absorption performance will decrease, which is not preferable.

The water-absorbing resin particles of the present invention can be obtained by mixing resin particles containing a crosslinked polymer (A) and a hydrophobic substance (c) with a polyether (d). Mixing equipment includes cylindrical mixers, screw mixers, screw extruders, turbulizers, Nauta mixers, double-arm kneaders, fluid mixers, V-type mixers, mincing mixers, and ribbon mixers. Examples include a method of uniformly mixing using a known mixing device such as a mold mixer, an air flow mixer, a rotating disk mixer, a conical blender, and a roll mixer.

When mixing the resin particles and the polyether (d), it is preferable to add the polyether (d) to the resin particles while stirring, from the viewpoint of uniform treatment of the surface. The polyether (d) to be added may be added simultaneously with water and/or a solvent, if necessary. When polyether (d) is added simultaneously with water and/or solvent, it is preferable to add a solution of polyether (d) in water and/or solvent, or a dispersion of polyether (d) in water and/or solvent. . When adding a solution or dispersion, it can also be added by spraying or dropping.

When a solution or dispersion of polyether (d) is added, the concentration of polyether (d) is preferably 5 to 70% by weight, more preferably 10 to 60% by weight.

The temperature at which the resin particles and polyether (d) are mixed is not particularly limited, but is preferably 10 to 150°C, more preferably 20 to 100°C, particularly preferably 25 to 80°C.

After mixing the resin particles and polyether (d), a heat treatment may be further performed. The heating temperature is preferably 25 to 180°C, more preferably 30 to 175°C, particularly preferably 35 to 170°C. If the temperature is 180° C. or lower, indirect heating using steam is possible, which is advantageous in terms of equipment. In addition, if heating is not performed, water and solvent used in combination may remain excessively in the water-absorbing resin, resulting in poor absorption performance. When heat treatment is performed, the heating time can be appropriately set depending on the heating temperature, but from the viewpoint of absorption characteristics, it is preferably 5 to 60 minutes, more preferably 10 to 40 minutes.

The water-absorbing resin particles of the present invention may further contain a surface treatment agent such as a cationic polymer, inorganic fine particles, or a polyvalent metal salt on the surface of the particles.

The cationic polymer is not particularly limited, but known cationic polymers exemplified in International Publication No. 2017-57709 can be used. Specific examples of cationic organic polymers include polyallylamine, polydiallylamine, poly(N-alkylallylamine), poly(alkyldiallylamine), monoallylamine-diallylamine copolymer, N-alkylallylamine-monoallylamine copolymer, and monoallylamine. Allylamine-dialkyl diallylammonium salt/copolymer, diallylamine-dialkyl diallylammonium salt/copolymer, polyaminoethyl (meth)acrylate, polydimethylaminoethyl (meth)acrylate, polydiethylaminoethyl (meth)acrylate, polydimethylaminoethyl (Meth)acrylamide, homopolymer of alkylaminoethyl (meth)acrylate quaternary salt, alkylaminoethyl (meth)acrylate quaternary salt-acrylamide copolymer, linear polyethyleneimine, branched polyethyleneimine, polyethylene Examples include polyamine, polypropylene polyamine, polyamide polyamine, polyether polyamine, polyvinylamine, polyamide polyamine/epichlorohydrin resin, and polyamidine. Also included are aminated modified products obtained by reacting polyacrylamide or polymethacrylamide with formaldehyde and diethylamine. Among these, polyaminoethyl (meth)acrylate, polydimethylaminoethyl (meth)acrylate, polydimethylaminoethyl (meth)acrylate, Homopolymers of alkylaminoethyl (meth)acrylate quaternary salts and alkylaminoethyl (meth)acrylate quaternary salt-acrylamide copolymers are preferred.

The cationic polymer may also be in the form of a salt with an anion that is a conjugate base of a strong acid. Examples of the strong acid include inorganic acids and organic acids, and suitable strong acids include hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, perchloric acid, tetrafluoroboric acid, hexafluorophosphoric acid, Examples include trifluoroacetic acid, methanesulfonic acid, para-toluenesulfonic acid, trifluoromethanesulfonic acid, camphorsulfonic acid, and the like. In addition, as a method for forming a salt of a cationic group, for example, an amino group or an ammonio group may be neutralized with an acidic compound, or an amino group and an electrophilic reagent {organic halide (methyl chloride, ethyl chloride, methyl bromide, ethyl bromide, etc.), dialkyl carbonates (dimethyl carbonate, diethyl carbonate, etc.), and sulfuric esters (dimethyl sulfate, diethyl sulfate, etc.).

Examples of the inorganic fine particles include silica, alumina, zirconia, titania, zinc oxide, and talc. Among these, silica and alumina are preferred. These may be used alone or in combination of two or more.

The polyvalent metal salt is not particularly limited, but includes at least one metal selected from the group consisting of magnesium, calcium, zirconium, aluminum, and titanium and an inorganic or organic acid, such as the above-mentioned inorganic or organic acids. , salts, etc. Among these, from the viewpoint of availability and solubility, inorganic acid salts of aluminum and inorganic acid salts of titanium are preferred, and aluminum sulfate, aluminum chloride, potassium aluminum sulfate, and sodium aluminum sulfate are more preferred. These may be used alone or in combination of two or more.

When surface-treating water-absorbing resin particles with a surface-treating agent such as a cationic polymer, inorganic fine particles, or polyvalent metal salt, the step of mixing with the surface-treating agent is not particularly limited; Preferably, it is present on the surface from the viewpoint of adhesion, and is preferably carried out before or simultaneously with the step of adding the polyether described above.

The water-absorbing resin particles of the present invention may contain other additives {for example, known preservatives (JP-A No. 2003-225565, JP-A No. 2006-131767, etc.), fungicides, antibacterial agents, antioxidants, and ultraviolet rays. It may also contain absorbents, colorants, fragrances, deodorants, organic fibrous materials, etc. When these additives are included, the content (wt%) of the additives is preferably 0.001 to 10, more preferably 0.01 to 5, particularly 0.001 to 10, based on the weight of the crosslinked polymer (A). Preferably it is from 0.05 to 1, most preferably from 0.1 to 0.5.

Examples of the shape of the water-absorbing resin particles of the present invention include amorphous crushed shapes, flaky shapes, pearl shapes, and rice grain shapes. Among these, amorphous crushed particles are preferable from the viewpoint of good entanglement with fibrous materials for use in disposable diapers, etc., and no fear of falling off from the fibrous materials.

The apparent density (g/ml) of the water absorbent resin particles of the present invention is preferably 0.52 to 0.67, more preferably 0.55 to 0.65, particularly preferably 0.57 to 0.63. . Within this range, the absorption properties of the absorbent article will be even better. Note that the apparent density is measured at 25°C in accordance with JIS K7365:1999.

The weight average particle diameter (μm) of the water absorbent resin particles of the present invention is preferably 200 to 420, more preferably 250 to 410, particularly preferably 300 to 400, most preferably 350 to 390. If it is larger than this range, the absorption rate in the DW method described below will decrease, and if it is smaller than this range, spot absorption or gel blocking will easily occur. Note that the weight average particle diameter can be measured in the same manner as described above.

The smaller the content of fine particles in the water-absorbing resin particles of the present invention, the better the absorption performance.The content of fine particles of 106 μm or less in the total particles is preferably 3% by weight or less, and more preferably the content of fine particles of 150 μm or less in the total particles. The content of fine particles is 3% by weight or less. Note that the content of fine particles can be measured in the same manner as described above.

The absorption amount (M) (ml/g) of the water-absorbent resin particles of the present invention according to the Demand Wettability test method (DW method) is determined from the viewpoint of drying properties of the absorbent article, and the absorption amount (M1) after 30 seconds is 3. -8 is preferable, and 3-7 is more preferable. Further, the absorption amount (M2) after 10 minutes is 39 to 47, preferably 41 to 47. Within this range, the surface drying properties of the absorbent article will be good. The absorption pattern determined by the DW method, that is, the early absorption amount (indicated by M1) and the late absorption amount (indicated by M2), can be adjusted to a preferable range by adjusting the balance of hydrophilicity and hydrophobicity on the surface of the water-absorbing resin particles. . In the present invention, in order to impart adhesion to the water-absorbing resin particles, polyether (d) having a polyoxyalkylene chain is included as an essential component on the surface of the water-absorbing resin particles. The absorption amount (M1) tends to increase. On the other hand, regarding the late absorption amount (M2), due to the high hydrophilicity of the surface, gel blocking may occur in the early absorption stage, resulting in poor liquid diffusivity and may become low. In order to keep the absorption pattern by the DW method within the above range, it can be controlled by the type and content of the hydrophobic substance (c) described above.

If the absorption amount (M1) after 30 seconds of DW is less than 3, the initial absorption amount is insufficient and the dryness deteriorates, and if it is higher than 8, the initial absorption amount is too high and the absorption is poor when used as an absorbent. This may result in uneven dryness and worsen dryness. If the absorption amount after 10 minutes is less than 39, the dryness may deteriorate due to insufficient absorption, and if it is higher than 47, the absorption amount in the absorbent body may be uneven and the dryness may deteriorate. be. The dryness can be evaluated by a surface dryness test using the SDME method described below.

<Measurement method of absorption amount by DW method>
The DW (Demand Wettability) method is a measurement method performed using the apparatus shown in FIG. 1 in a room at 25±2° C. and 50±10% humidity. The measuring device shown in FIG. 1 consists of a burette part (2) {scale capacity 50 ml, length 86 cm, inner diameter 1.05 cm}, a conduit {inner diameter 7 mm}, and a measuring table (6). The burette part (2) is connected to a rubber stopper (1) at the top, an intake introduction pipe (9) {tip inner diameter 3 mm} and a cock (7) at the bottom, and the upper part of the intake introduction pipe (9) is connected to the cock (7). There is a cook (8). A conduit is attached from the burette part (2) to the measurement stand (6). A hole with a diameter of 3 mm is opened in the center of the measuring table (6) as a physiological saline supply part, and a conduit is connected to the hole.

Using a measuring device with this configuration, first close the cock (7) of the buret part (2) and the cock (8) of the air introduction tube (9), and then add a predetermined amount of physiological saline (salt water) adjusted to 25°C. 0.9% by weight) from the top of the burette part (2), plug the top of the burette with the rubber stopper (1), and then close the cock (7) of the burette part (2) and the cock of the air introduction pipe (9). Open (8). Next, after wiping off the physiological saline that overflowed onto the measuring table (6), the top surface of the measuring table (6) and the surface of the saline coming out from the conduit port in the center of the measuring table (6) are connected. Adjust the height of the measuring table (6) so that they are at the same height. While wiping off the physiological saline from the saline supply section, adjust the water level of the saline in the burette section (2) to the top of the scale (0 ml line) of the burette section (2).

Next, close the cock (7) of the burette part (2) and the cock (8) of the air introduction tube (9), and place the plain-woven nylon mesh ( 5) (opening 63 μm, 5 cm x 5 cm), and then on top of this plain-woven nylon mesh (5), 0.50 g was placed in an area of 2.7 cm in diameter around the physiological saline supply part of the measuring table (6). The water-absorbing resin particles (4) are uniformly scattered. Then, open the cock (7) of the burette part (2) and the cock (8) of the air introduction pipe (9).

When the water-absorbing resin particles (4) begin to absorb water and the first bubble introduced from the air introduction tube (9) reaches the water surface of the physiological saline in the burette part (2) (buret part (2) The measurement start time is the time when the water level of the physiological saline in the burette part (2) has dropped (the time when the water level of the physiological saline in the buret part (2) has fallen). Read the amount of saline solution M (ml). The amount absorbed by the water-absorbing resin particles (4) after a predetermined period of time has elapsed from the start of water absorption is determined by the following formula.

Absorption amount (ml/g) by DW method = M÷0.50

The water-absorbing resin particles of the present invention preferably have a physiological saline water retention amount (g/g) of 25 to 45, more preferably 30 to 43. Within this range, a sufficient amount of absorption can be ensured as an absorber. If the water retention amount is 25 or less, leakage tends to occur during repeated use, which is not preferable. Moreover, if it exceeds 45, it is not preferable because blocking tends to occur. The water retention amount of physiological saline can be appropriately adjusted by the type and amount of the internal crosslinking agent (b) and the surface crosslinking agent. Therefore, for example, if it is necessary to increase the water retention amount of physiological saline, this can be easily achieved by increasing the amounts of the internal crosslinking agent (b) and the surface crosslinking agent. Note that the water retention amount of physiological saline is measured by the following method.

<Method for measuring water retention amount of physiological saline>
Put 1.00 g of the measurement sample into a tea bag (length 20 cm, width 10 cm) made of nylon mesh with an opening of 63 μm (JIS Z8801-1:2006), and add 1,000 ml of physiological saline (salt concentration 0.9% by weight). After immersing in the water for 1 hour without stirring, hang it up for 15 minutes to drain. Thereafter, each tea bag is placed in a centrifuge, centrifuged at 150 G for 90 seconds to remove excess physiological saline, the weight (h1) including the tea bag is measured, and the water retention amount is determined from the following formula.
Water retention amount (g/g) = (h1) - (h2)
Note that the temperature of the physiological saline used and the measurement atmosphere was 25°C±2°C. The weight of the tea bag after centrifugal dehydration is measured (h2) in the same manner as above except that no measurement sample is used.

The water-absorbing resin particles of the present invention preferably have an absorption amount of physiological saline under load of 15 to 30 g/g. Within this range, the absorbent body can sufficiently absorb liquid even when placed under load. If it is less than 15, leakage tends to occur during repeated use, which is not preferable. Further, the upper limit value is preferably higher and is not particularly limited, but from the viewpoint of performance balance with other physical properties and productivity, it is more preferably 27 or less, and still more preferably 25 or less. The amount of absorption under load can be adjusted as appropriate by the type and amount of the internal crosslinking agent (b) and the surface crosslinking agent. Therefore, for example, if it is necessary to increase the amount of absorption under load, this can be easily achieved by increasing the amounts of the internal crosslinking agent (b) and the surface crosslinking agent. In addition, the absorption amount of physiological saline under load is measured by the following method.

<Method for measuring absorption under load>
Measurement using a standard sieve in a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) with a nylon mesh with an opening of 63 μm (JIS Z8801-1:2006) attached to the bottom, and sieved into a range of 250 to 500 μm. Weigh 0.16 g of the sample, arrange the cylindrical plastic tube vertically on the nylon net so that the sample has a nearly uniform thickness, and place a weight (weight: 210.6 g, external) on top of the sample. Diameter: 24.5mm). After weighing the entire weight (h3) of this cylindrical plastic tube, place the cylindrical plastic tube containing the measurement sample and weight in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration 0.9%). Stand the tube vertically, immerse it with the nylon mesh side facing down, and let it stand for 60 minutes. After 60 minutes, remove the cylindrical plastic tube from the Petri dish, tilt it diagonally, collect the water that has adhered to the bottom in one place, and let it drip as drops to remove excess water. Weigh the entire weight (h4) of the cylindrical plastic tube, and calculate the amount of absorption under load from the following formula. Note that the temperature of the physiological saline used and the measurement atmosphere was 25°C±2°C.
Absorption amount under load (g/g) = {(h4)-(h3)}/0.16

The absorbent body of the present invention contains the above-mentioned water-absorbing resin particles fixed to a fibrous base material.

The fibrous base material is preferably at least one selected from the group consisting of cellulose fibers, organic synthetic fibers, and mixtures of organic synthetic fibers and cellulose fibers. Examples of cellulose fibers include natural fibers such as fluff pulp, and cellulose chemical fibers such as viscose rayon, acetate, and cupra. There are no particular limitations on the raw material (softwood, hardwood, etc.), manufacturing method (chemical pulp, semi-chemical pulp, mechanical pulp, CTMP, etc.), bleaching method, etc. of this cellulosic natural fiber. Examples of organic synthetic fibers include polypropylene fibers, polyethylene fibers, polyamide fibers, polyacrylonitrile fibers, polyester fibers, polyvinyl alcohol fibers, polyurethane fibers, heat-fusible composite fibers (for example, Examples include fibers in which at least two of the above fibers are combined into a sheath-core type, eccentric type, parallel type, etc., fibers in which at least two of the above fibers are blended, fibers in which the surface layer of the above fibers is modified, etc. . Among these fibrous base materials, preferred are cellulose natural fibers, polypropylene fibers, polyethylene fibers, polyester fibers, heat-fusible conjugate fibers, and these. More preferred are fluff pulp, heat-fusible conjugate fibers, and mixtures thereof.

The length and thickness of the above-mentioned fibrous base material are not particularly limited, and it can be suitably used as long as the length is usually in the range of 1 to 200 mm and the thickness is in the range of 0.1 to 100 denier. The shape is not particularly limited as long as it is fibrous, and examples include a thin cylinder, split yarn, staple, filament, and web.

The ratio of the water-absorbing resin particles to the fibrous base material is preferably (20:80) to (95:5), more preferably (30:70) by weight. ~(90:10), more preferably (35:65) ~(80:20). If the ratio of water-absorbing resin particles is less than 20, the resulting absorbent body will not exhibit sufficient absorption performance, and if it exceeds 95, the adhesion of the water-absorbing resin particles may decrease.

As a method for fixing the water-absorbing resin particles to the fibrous base material, any known appropriate method can be employed depending on the properties of the fibrous base material used. In this case, the organic synthetic fiber is at least one type selected from a sheath-core type, an eccentric type, and a parallel type, contains multiple (two or more) components with different melting points, and has a low A heat-fusible conjugate fiber whose melting point component has a melting point of 50 to 180° C. is preferred because a simple method of heating can be used to achieve fixation.

The method for producing the absorbent body is as follows: (1) Water-absorbing resin particles are mixed with a fibrous base material or dispersed on the fibrous base material, and then the water-absorbing resin particles are heated to a temperature higher than the melting point of the polyether (d) contained on the surface of the water-absorbing resin particles. (2) mixing water-absorbing resin particles with a fibrous base material at a temperature equal to or higher than the melting point of (d), and partially fixing the water-absorbing resin particles to the fibrous base material at the same time as mixing; (3) a method in which the water-absorbing resin particles are kept at a temperature higher than the melting point of (d) and then dispersed, coated, or adhered to a fibrous base material; (4) the water-absorbing resin particles are kept at a temperature of (d) or higher; Examples include a method of spraying or mixing onto a fibrous base material maintained at a temperature above.

As the device for mixing the water-absorbing resin particles and the fibrous base material, a normal mixing device may be used, such as a conical blender, a Nauta mixer, a V-type mixer, a fluidized bed mixer, an air flow mixer, and a powder/granular mixer. Examples include an airflow type mixing device equipped with a spray nozzle, and a fibrous material crushing device equipped with a powder spray nozzle. Examples of equipment for processing at temperatures above the melting point of (d) include hot air heating machines, Nauta heating machines, fluidized bed heating machines, air flow heating machines, heated calender rolls, infrared heating machines, and high frequency heating machines. Can be mentioned.

In the present invention, it is not necessary that all of the water-absorbing resin particles are fixed to the fibrous base material, but only partially, for example, 60% or more by weight of the water-absorbing resin particles are fixed to the fibrous base material. Bye. By selecting preferable conditions, the proportion of fixed water-absorbing resin particles becomes 80% by weight or more. If the adhesion rate is less than 60% by weight, when applied to absorbent products such as disposable diapers and sanitary products, the water-absorbing resin particles may move, be ubiquitous, separate, or fall off during the storage, transportation, etc. processes of these products. be. In addition, in the absorber of the present invention, it is preferable that the above-mentioned fixation rate is a value after a vibration test. The detailed test method for the adhesion rate will be described later.

The absorbent body of the present invention can be subjected to treatments normally applied to fibrous materials, such as crushing, lamination, compression, cold calendering, heat calendering, needle punching, stretching, and paper forming, if necessary.

Additives to the absorber of the present invention include organic powders (e.g., pulp powder, cellulose derivatives, natural polysaccharides, etc.), inorganic powders (e.g., zeolite, silica, alumina, bentonite, activated carbon, etc.), glass fibers, antioxidants, Preservatives, bactericidal agents, surfactants, coloring agents, fragrances, etc. may be added as necessary, and the amount of these is usually 10% by weight or less, preferably 5% by weight or less, based on the weight of the absorbent body.

The absorbent article of the present invention uses the absorbent body of the present invention. Examples of the above-mentioned absorbent articles include various sanitary materials and absorbent articles such as paper diapers, sanitary products, postpartum mats, and medical underpads. It is particularly useful for thin paper diapers and thin sanitary products in which the ratio of water-absorbent resin/fiber (pulp and/or heat-adhesive fiber) is high. In addition, sheet or tape-like water-absorbing materials such as freshness-keeping materials for fruits and vegetables, drip absorbing materials, moisture or humidity control sheets, dew prevention materials, seedling sheets for paddy rice, concrete curing sheets, and water-stopping materials for communication cables and optical fiber cables are also available. It is also useful when manufacturing. The composition and structure of these absorbent articles are well known to those skilled in the art.

The present invention will be further explained below with reference to Examples , Reference Examples , and Comparative Examples, but the present invention is not limited thereto. In addition, unless otherwise specified, "part" means part by weight, and "%" means percent by weight. However, in the following, Example 2 shall be read as Reference Example 2.

<Manufacture example 1>
Acrylic acid (a1-1) {manufactured by Mitsubishi Chemical Corporation, purity 100%} 270 parts, internal crosslinking agent (b-1) {pentaerythritol triallyl ether, manufactured by Daiso Corporation} 0.98 parts (acrylic acid 0.10 mol%) and 712 parts of ion-exchanged water were kept at 3° C. while stirring and mixing. After nitrogen was introduced into this mixture to reduce the amount of dissolved oxygen to 1 ppm or less, 1.1 parts of a 1% aqueous hydrogen peroxide solution, 2.0 parts of a 2% aqueous ascorbic acid solution, and 2% 2,2'-azobis 13.5 parts of an aqueous solution of amidinopropane dihydrochloride was added and mixed to initiate polymerization. After the temperature of the mixture reached 80°C, it was aged at 80±2°C for about 5 hours to obtain a hydrogel.

Next, while shredding this water-containing gel with a mincing machine (12VR-400K manufactured by ROYAL), 220 parts of a 49% aqueous sodium hydroxide solution was added to mix and neutralize, and then sucrose was added as a hydrophobic substance (c). A neutralized gel was obtained by adding 0.12 parts of stearic acid ester. Furthermore, the neutralized hydrogel was placed on a ventilation type dryer (manufactured by Inoue Metal) and dried under conditions of a temperature of 150°C and a wind speed of 1.5 m/sec until the moisture content reached 4%. I got a body. After pulverizing the dried body with a juicer mixer (OSTERIZER BLENDER, manufactured by Oster), it was sieved and adjusted to a particle size range of 710 to 150 μm to obtain resin particles (A-1) containing 380 parts of crosslinked polymer. ) was obtained.

Next, 100 parts of the obtained resin particles (A-1) were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), and 0.12 parts of ethylene glycol diglycidyl ether as a surface crosslinking agent was added thereto. , 1.0 parts of propylene glycol, and 1.7 parts of ion-exchanged water were added, mixed uniformly, and heated at 135°C for 30 minutes to form surface-crosslinked resin particles (A-2). Obtained.

<Production example 2>
In Production Example 1, sucrose stearate was changed to polyether-modified polysiloxane (trade name: KF-6020, side chains: oxyethylene and oxypropylene, manufactured by Shin-Etsu Chemical Co., Ltd.) as the hydrophobic substance (c). The same operation was carried out except for that, to obtain surface-crosslinked resin particles (A-3).

<Manufacture example 3>
Acrylic acid (a1-1) {manufactured by Mitsubishi Chemical Corporation, purity 100%} 270 parts, internal crosslinking agent (b-1) {pentaerythritol triallyl ether, manufactured by Daiso Corporation} 0.98 parts (acrylic acid 0.10 mol%) and 712 parts of ion-exchanged water were kept at 3° C. while stirring and mixing. After nitrogen was introduced into this mixture to reduce the amount of dissolved oxygen to 1 ppm or less, 1.1 parts of a 1% aqueous hydrogen peroxide solution, 2.0 parts of a 2% aqueous ascorbic acid solution, and 2% 2,2'-azobis 13.5 parts of an aqueous solution of amidinopropane dihydrochloride was added and mixed to initiate polymerization. After the temperature of the mixture reached 80°C, it was aged at 80±2°C for about 5 hours to obtain a hydrogel.

Next, while this hydrous gel was shredded using a mincing machine (12VR-400K manufactured by ROYAL), 220 parts of a 49% aqueous sodium hydroxide solution was added to mix and neutralize to obtain a neutralized gel. Furthermore, the neutralized hydrogel was placed on a ventilation type dryer (manufactured by Inoue Metal) and dried under conditions of a temperature of 150°C and a wind speed of 1.5 m/sec until the moisture content reached 4%. I got a body. The dried product was pulverized with a juicer mixer (OSTERIZER BLENDER manufactured by Oster), then sieved and adjusted to a particle size range of 710 to 150 μm to obtain resin particles (A-4) containing 380 parts of crosslinked polymer. ) was obtained.

Next, 100 parts of the obtained resin particles (A-4) were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), and 0.12 parts of ethylene glycol diglycidyl ether as a surface crosslinking agent was added thereto. , 1.0 part of propylene glycol, 1.7 parts of ion-exchanged water, 0.02 part of carboxy-modified polysiloxane (model number X-22-3701E, manufactured by Shin-Etsu Chemical Co., Ltd.) as the hydrophobic substance (c), and polyether-modified polyester. A mixed solution containing 0.002 parts of siloxane (model number KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, mixed uniformly, and heated at 135°C for 30 minutes to form surface-crosslinked resin particles (A-5). ) was obtained.

<Manufacture example 4>
Acrylic acid (a1-1) {manufactured by Mitsubishi Chemical Corporation, purity 100%} 270 parts, internal crosslinking agent (b-1) {pentaerythritol triallyl ether, manufactured by Daiso Corporation} 0.68 parts (acrylic acid 0.07 mol%) and 712 parts of ion-exchanged water were kept at 3° C. while stirring and mixing. After nitrogen was introduced into this mixture to reduce the amount of dissolved oxygen to 1 ppm or less, 1.1 parts of a 1% aqueous hydrogen peroxide solution, 2.0 parts of a 2% aqueous ascorbic acid solution, and 2% 2,2'-azobis 13.5 parts of an aqueous solution of amidinopropane dihydrochloride was added and mixed to initiate polymerization. After the temperature of the mixture reached 80°C, it was aged at 80±2°C for about 5 hours to obtain a hydrogel.

Next, while shredding this water-containing gel with a mincing machine (12VR-400K manufactured by ROYAL), 220 parts of a 49% aqueous sodium hydroxide solution was added to mix and neutralize, and then sucrose was added as a hydrophobic substance (c). A neutralized gel was obtained by adding 0.6 part of stearic acid ester. Furthermore, the neutralized hydrogel was placed on a ventilation type dryer (manufactured by Inoue Metal) and dried under conditions of a temperature of 150°C and a wind speed of 1.5 m/sec until the moisture content reached 4%. I got a body. The dried product was pulverized with a juicer mixer (OSTERIZER BLENDER manufactured by Oster), then sieved and adjusted to a particle size range of 710 to 150 μm to obtain resin particles (A-6) containing 380 parts of crosslinked polymer. ) was obtained.

Next, 0.06 part of ethylene glycol diglycidyl ether as a surface crosslinking agent was added to 100 parts of the obtained resin particles (A-6) while stirring at high speed (High speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm). , 1.0 parts of propylene glycol, and 1.7 parts of ion-exchanged water were added, mixed uniformly, and heated at 135°C for 30 minutes to form surface-crosslinked resin particles (A-7). Obtained.

<Manufacture example 5>
Acrylic acid (a1-1) {manufactured by Mitsubishi Chemical Corporation, purity 100%} 270 parts, internal crosslinking agent (b-1) {pentaerythritol triallyl ether, manufactured by Daiso Corporation} 0.98 parts (acrylic acid 0.07 mol%) and 712 parts of ion-exchanged water were kept at 3° C. while stirring and mixing. After nitrogen was introduced into this mixture to reduce the amount of dissolved oxygen to 1 ppm or less, 1.1 parts of a 1% aqueous hydrogen peroxide solution, 2.0 parts of a 2% aqueous ascorbic acid solution, and 2% 2,2'-azobis 13.5 parts of an aqueous solution of amidinopropane dihydrochloride was added and mixed to initiate polymerization. After the temperature of the mixture reached 80°C, it was aged at 80±2°C for about 5 hours to obtain a hydrogel.

Next, while shredding this water-containing gel with a mincing machine (12VR-400K manufactured by ROYAL), 220 parts of a 49% aqueous sodium hydroxide solution was added to mix and neutralize, and then sucrose was added as a hydrophobic substance (c). A neutralized gel was obtained by adding 0.45 parts of stearic acid ester. Furthermore, the neutralized hydrogel was placed on a ventilation type dryer (manufactured by Inoue Metal) and dried under conditions of a temperature of 150°C and a wind speed of 1.5 m/sec until the moisture content reached 4%. I got a body. After pulverizing the dried body with a juicer mixer (OSTERIZER BLENDER manufactured by Oster), it was sieved and adjusted to a particle size range of 710 to 150 μm to obtain resin particles (A-8) containing 380 parts of crosslinked polymer. ) was obtained.

Next, 0.12 parts of ethylene glycol diglycidyl ether as a surface crosslinking agent was added to 100 parts of the obtained resin particles (A-8) while stirring at high speed (High speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm). , 1.0 parts of propylene glycol, 1.7 parts of ion-exchanged water, and 0.03 parts of polyether-modified polysiloxane were added, mixed uniformly, and heated at 135°C for 30 minutes to coat the surface. Crosslinked resin particles (A-9) were obtained.

<Manufacture example 6>
The same operation as in Production Example 5 was performed except that 0.03 part of polyether-modified polysiloxane was changed to 0.002 part and 0.02 part of carboxy-modified polysiloxane was added, and surface-crosslinked resin particles (A- 10) was obtained.

<Manufacture example 7>
The same operation as in Production Example 1 was performed except that sucrose stearate was not used as the hydrophobic substance (c) to obtain surface-crosslinked resin particles (A-11).

<Manufacture example 8>
Block polymer (B) was obtained by performing the same operation with reference to Production Example 2 described in International Publication No. 2015/178481 pamphlet. Mn of (B) was 28,000. Further, the average repetition number Nn of (B) determined from this Mn and ¹ H-NMR analysis was 3.4.

<Example 1>
100 parts of the surface-crosslinked resin particles (A-2) obtained in Production Example 1 were mixed with polyethylene glycol 20,000 (trade name: PEG-) while stirring at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Co., Ltd., rotation speed 2000 rpm). 20,000 (manufactured by Sanyo Chemical Industries, Ltd., Mn=20,000) and 4.0 parts of ion-exchanged water were uniformly mixed. Thereafter, it was heated at 80° C. for 30 minutes to obtain water absorbent resin particles (P-1) of the present invention.

<Example 2>
The same operation as in Example 1 was carried out, except that polyethylene glycol 20000 in Example 1 was changed to polyethylene glycol 2000 (trade name: PEG-2000, manufactured by Sanyo Chemical Industries, Ltd., Mn = 2000), and the water absorbent resin of the present invention was prepared. Particles (P-2) were obtained.

<Example 3>
The same operation as in Example 1 was performed except that the amount of polyethylene glycol 20,000 added in Example 1 was changed from 1.0 parts to 3.0 parts to obtain water-absorbing resin particles (P-3) of the present invention. Ta.

<Example 4>
The same operation as in Example 1 was performed except that polyethylene glycol 111000 (trade name: Polyethylene glycol 111000, manufactured by Aldrich, Mn = 96500) was changed from polyethylene glycol 20000, and water absorbent resin particles (P-4) of the present invention were obtained. I got it.

<Example 5>
Example 1 except that polyethylene glycol 20,000 in Example 1 was changed to a block copolymer of polyoxyethylene/polyoxypropylene glycol (trade name: Newpol PE-68, manufactured by Sanyo Chemical Industries, Ltd., Mn = 8,000). A similar operation was performed to obtain water absorbent resin particles (P-5) of the present invention.

<Example 6>
The same operation as in Example 1 was carried out except that the surface-crosslinked resin particles (A-2) of Example 1 were changed to surface-crosslinked resin particles (A-3), and the water-absorbing resin particles of the present invention ( P-6) was obtained.

<Example 7>
The same operation as in Example 1 was carried out except that the surface-crosslinked resin particles (A-2) of Example 1 were changed to surface-crosslinked resin particles (A-5), and the water-absorbing resin particles of the present invention ( P-7) was obtained.

<Example 8>
The same operation as in Example 1 was carried out except that the surface-crosslinked resin particles (A-2) of Example 1 were changed to surface-crosslinked resin particles (A-7), and the water-absorbing resin particles of the present invention ( P-8) was obtained.

<Example 9>
The same operation as in Example 1 was carried out except that the surface-crosslinked resin particles (A-2) of Example 1 were changed to surface-crosslinked resin particles (A-9), and the water-absorbing resin particles of the present invention ( P-9) was obtained.

<Example 10>
The same operation as in Example 1 was carried out except that the surface-crosslinked resin particles (A-2) of Example 1 were changed to surface-crosslinked resin particles (A-10), and the water-absorbing resin particles of the present invention ( P-10) was obtained.

<Example 11>
The surface-crosslinked resin particles (A-2) of Example 1 were added to the surface-crosslinked resin particles (A-10), and polyethylene glycol 20000 was added to Newport PE-128 (trade name: Newport PE-128, Sanyo Chemical). Water-absorbing resin particles (P-11) of the present invention were obtained by carrying out the same operation as in Example 1, except for changing to Mn=31000 (manufactured by Kogyo Co., Ltd.).

<Comparative example 1>
The same operation as in Example 1 was performed except that polyethylene glycol 1000 (trade name: PEG-1000, manufactured by Sanyo Chemical Industries, Ltd., Mn = 1000) was changed from polyethylene glycol 20000 in Example 1, and a water-absorbing resin for comparison was prepared. Particles (R-1) were obtained.

<Comparative example 2>
The same operation as in Example was performed except that the surface-crosslinked resin particles (A-2) in Example 1 were changed to resin particles (A-4), and water-absorbing resin particles (R-2) for comparison were prepared. Obtained.

<Comparative example 3>
In Example 1, the same operation as in Example 1 was performed except that the surface crosslinked resin particles (A-2) were changed to resin particles (A-4) and polyethylene glycol 20000 was not used. Water absorbent resin particles (R-3) were obtained.

<Comparative example 4>
The same operation as in Example 1 was performed except that polyethylene glycol 20,000 in Example 1 was changed to the block polymer (B) obtained in Production Example 8 to obtain water-absorbing resin particles (R-4) for comparison. .

Using the water-absorbing resin particles obtained in Examples 1 to 11 and Comparative Examples 1 to 4, the water retention amount (g/g), absorption amount under load (g/g), and absorption amount by DW method were determined by the above-mentioned method. (ml/g) was measured (after 30 seconds and after 10 minutes). The results are shown in Table 1. Subsequently, using the water absorbent resin particles obtained in Examples 1 to 11 and Comparative Examples 1 to 4, the adhesion rate of the absorber and the surface drying property of the absorbent article were evaluated as follows.

<Evaluation of adhesion rate of absorber>
100 parts of fluff pulp and 100 parts of the evaluation sample {water-absorbing resin particles of each example and comparative example} were mixed in an airflow type mixing device {pad former manufactured by Autech Co., Ltd.} to obtain a mixture. The mixture was uniformly laminated on an acrylic plate (thickness: 4 mm) so that the basis weight was approximately 500 g/m ² and pressed for 30 seconds at a pressure of 5 kg/cm ² to obtain an absorbent body. A 10 cm x 10 cm test piece of this absorbent body was cut into pieces, and then the weight (ml) of the test piece was measured. Next, this was placed on a metal vat, left to stand for 10 minutes in a temperature-controlled circulating dryer set at 80°C, and then allowed to cool to room temperature. I got a body. However, for the absorbent body made from the water-absorbing resin particles (R-4) obtained in Comparative Example 4, the temperature setting of the circulation dryer was changed from 80°C to 150°C. Thereafter, the fixed absorbent body was placed on a wire mesh of a JIS standard sieve with an opening of 4 mm. This wire mesh was placed in a low-tap test sieve shaker (low-tap type, manufactured by Iida Seisakusho Co., Ltd.) and shaken for 5 minutes.Finally, the test piece was turned upside down and fixed to the fluff pulp. After removing the water-absorbing resin particles that were not attached, the weight (m2) of the test piece remaining on the wire mesh was measured, and the adhesion rate was calculated using the following formula. However, calculations were made assuming that the weight of water-absorbing resin particles contained in a 10 cm x 10 cm test piece was 2.5 g.
(Fixing rate [%]) = {2.5[g]-(m1[g]-m2[g])}/2.5[g]×100

<Preparation of absorbent article (disposable diaper)>
The above-mentioned absorbent body in which the water-absorbing resin is adhered to fluff pulp is cut into rectangles of 10 cm x 40 cm, and on the top and bottom of each piece of paper (basis weight 15.5 g/m ² , manufactured by Advantech, Inc.), the same size as the absorbent body is placed. Filter paper No. 2) is placed, a polyethylene sheet (polyethylene film UB-1 manufactured by Tamapoly Co., Ltd.) is placed on the back side, and a nonwoven fabric (basis weight 20 g/m ² , Eltas Guard manufactured by Asahi Kasei Co., Ltd.) is placed on the surface. Prepared. The weight ratio of water-absorbing resin particles to fibers (weight of water-absorbing resin particles/weight of fibers) was 50/50.

<Surface dryness evaluation by SDME method>
A paper diaper (artificial urine (potassium chloride 0.03% by weight, magnesium sulfate 0.08% by weight), sodium chloride 0.8% % and deionized water (99.09% by weight) and left for 60 minutes. } and set the 0% dryness value, and then placed the detector of the SDME tester on a dry paper diaper (prepared by heating and drying the paper diaper at 80° C. for 2 hours). } and set the 100% dryness value, and calibrated the SDME tester. Next, set a metal ring (inner diameter 70 mm, length 50 mm) in the center of the disposable diaper to be measured, inject 80 ml of artificial urine, and immediately after absorbing the artificial urine {when the gloss caused by the artificial urine can no longer be confirmed}. Remove the metal ring, place three SDME detectors in the center of the disposable diaper and on its left and right {three locations equally spaced 10cm from the edge of a 40cm disposable diaper} to start measuring the surface dryness value (unit: %). Among the three SDME detectors, the dryness value of the center detector is the surface dryness value (SD1-1) {center}, and the dryness value of the remaining two SDME detectors is the surface dryness. Value (SD1-2) {left} and surface dryness value (SD1-3) {right}. Note that the artificial urine, measurement atmosphere, and leaving atmosphere were 25±5° C. and 65±10% RH.

Table 1 shows each characteristic value of the water-absorbing resin particles obtained in each Example and Comparative Example, as well as the results of evaluation of adhesion and surface dryness of the absorbent body prepared using these water-absorbing resin particles.

As is clear from the results shown in Table 1, the water-absorbing resin particles of the present invention are superior in adhesion to absorbers and in surface drying properties of absorbent articles, compared to the water-absorbing resin particles of comparative examples. In particular, when comparing comparative examples in detail regarding the surface dryness evaluation results of absorbent articles, we find that when polyether has a small molecular weight, as in Comparative Example 1, not only does the adhesion rate of the absorbent material decrease, but also the DW method The initial absorption amount (DW method 30 second value) is large, and the DW method late absorption amount (DW method 10 minute value) is small. As a result, in the dryness evaluation of the absorbent article, it can be seen that the amount of water absorbed at the center of the liquid injection part increases, and the surface dryness at the center deteriorates. In addition, in Comparative Example 2, the adhesion rate of the absorber is improved by using polyether with a specific molecular weight, but since no hydrophobic substance is used, the initial absorption amount by DW method is large, and compared to Comparative Example 1. Similarly, the surface dryness in the center area has decreased. In addition, when a block polymer is used in Comparative Example 4, although the adhesion rate of the absorber becomes good due to an appropriate adhesion temperature, the hydrophobic portion of the block polymer has a strong influence, and both the initial and late absorption amount of the DW method is It can be seen that the dryness of the absorbent article is decreased as a whole.

The water-absorbing resin particles of the present invention can be applied not only to an absorbent body containing water-absorbing resin particles and a nonwoven fabric, but also to an absorbent body containing water-absorbing resin particles and a fibrous material. It is useful for absorbent articles (disposable diapers, sanitary napkins, medical blood preservation agents, etc.). In addition, pet urine absorbents, urine gelling agents for portable toilets, freshness preservation agents for fruits and vegetables, drip absorbers for meat and seafood, ice packs, disposable body warmers, gelling agents for batteries, water retention agents for plants and soil, and condensation. It can also be used in various applications such as preventive agents, water-stopping agents, packing agents, and artificial snow.

1 Rubber stopper 2 Buret part 3 Physiological saline 4 Water-absorbing resin particles 5 Plain weave nylon mesh 6 Measuring table 7 Cock 8 Cock 9 Air introduction tube

Claims (8)

Water-soluble vinyl monomer (a1) and/or vinyl monomer (a2) that becomes water-soluble vinyl monomer (a1) by hydrolysis, crosslinked polymer (A) whose essential constituent units are internal crosslinking agent (b), and hydrophobic substance (c), the water-absorbing resin particles contain a polyether (d) having a polyoxyalkylene chain on the surface thereof, and the number average molecular weight of (d) is 2000 or more. Water-absorbing resin particles, in which the number average molecular weight of polyether (d) is 5,000 to 100,000, and the amount absorbed after 30 seconds by the Demand Wettability test method (DW method) is 3 to 8 ml/g. resin particles. The water-absorbing resin particles according to claim 1 , wherein the polyether (d) is water-soluble. The water-absorbing resin particles according to claim 1 or 2, wherein the polyether (d) is a polyether having a polyoxyethylene chain. According to any one of claims 1 to 3, the polyether (d) is at least one selected from the group consisting of polyethylene glycol, polyoxyethylene alkyl ether, and a block copolymer of polyoxyethylene/polyoxypropylene glycol. water-absorbing resin particles. The water-absorbing resin particles according to any one of claims 1 to 4, wherein the content of polyether (d) is 0.5 to 5.0% by weight based on the weight of the water-absorbing resin particles. Any one of claims 1 to 5 , wherein the hydrophobic substance (c) is a hydrophobic substance (c1) containing a hydrocarbon group having 8 to 30 carbon atoms and/or a hydrophobic substance (c2) which is an organic polysiloxane. Water-absorbing resin particles as described. An absorbent body comprising the water-absorbing resin particles according to any one of claims 1 to 6 fixed to a fibrous base material. An absorbent article using the absorbent body according to claim 7 .

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