JP7260276B2 - Absorbent resin particles, absorbent bodies and absorbent articles containing the same - Google Patents

Description

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

A partially neutralized crosslinked product of polyacrylic acid is known as a body fluid-absorbing resin used in sanitary materials, and is widely used in paper diapers, sanitary napkins, and the like. When the object to be absorbed is blood, unlike urine, it contains a lot of solids such as protein components and blood cell components, so the amount of liquid is small. There is a problem that the absorption performance is lower than in the case.

Conventionally, as a technique for improving blood absorption performance, kaolinite is attached to the surface of an absorbent resin to improve blood absorption inhibition due to wetting of the absorbent resin surface, thereby improving blood absorption. A method for manufacturing a blood absorbing material having performance is known (see Patent Documents 1 and 2). In addition, by attaching a water-soluble cationic polymer to the absorbent resin and agglutinating red blood cells in the blood, it suppresses the formation of a film due to the accumulation of red blood cells on the surface of the absorbent resin, resulting in a physiological product with excellent blood absorption performance. An article is known (see Patent Document 3).

WO 00/10496 pamphlet JP-A-2000-51690 Japanese Unexamined Patent Application Publication No. 2016-107100

However, in the above-described conventional technology, there is a problem in that the absorber does not exhibit a sufficient ability to absorb blood, resulting in a dry feeling of the absorbent.

An object of the present invention is to provide absorbent resin particles that have high blood absorption performance and can exhibit excellent dry feeling when used in absorbent articles, and absorbent bodies and absorbent articles containing the same.

The present inventors arrived at the present invention as a result of intensive studies in order to solve the above problems.
That is, the present invention provides a crosslinked polymer (A) comprising a water-soluble vinyl monomer (a1) and/or a vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis, and a crosslinking agent (b) as essential structural units. and a phyllosilicate mineral (B) and a hemolytic agent (C), wherein the hemolytic agent (C) is one or more selected from the group consisting of ammonium chloride and benzalkonium chloride. absorbent resin particles; an absorbent body containing the absorbent resin particles; and an absorbent article containing the absorbent body.

The absorbent resin particles of the present invention exhibit good blood absorption performance. Therefore, the absorbent article using the absorbent resin particles of the present invention is excellent in the dry feeling of the absorbent against blood. Therefore, it exhibits stable and excellent absorption performance for blood even under various conditions of use.

The absorbent resin particles of the present invention comprise a water-soluble vinyl monomer (a1) and/or a vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis, and a cross-linking polymer having a cross-linking agent (b) as essential structural units. resin particles containing coalescence (A), phyllosilicate mineral (B) and hemolytic agent (C), wherein said hemolytic agent (C) is one selected from the group consisting of ammonium chloride and benzalkonium chloride The absorbent resin particles are as described above.

The water-soluble vinyl monomer (a1) in the present invention is not particularly limited. vinyl monomers having saturated groups (e.g., anionic vinyl monomers, nonionic vinyl monomers and cationic vinyl monomers), anionic vinyl monomers disclosed in paragraphs 0009 to 0024 of JP-A-2003-165883, nonionic a carboxy group, a sulfo group, a phosphono group, a hydroxyl group, a carbamoyl group, an amino group and an ammonio group disclosed in paragraphs 0041 to 0051 of JP-A-2005-75982; Any vinyl monomer having at least one of the following can be used.

A vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis [hereinafter also referred to as a 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 by hydrolysis disclosed in paragraphs 0024 to 0025 of Japanese Patent No. 3648553; At least one hydrolyzable substituent [1,3-oxo-2-oxapropylene (-CO-O-CO-) group, acyl group and cyano A vinyl monomer having a group, etc.} can be used. The term "water-soluble vinyl monomer" is a concept well known to those skilled in the art, but if expressed in terms of quantity, it means, for example, a vinyl monomer that dissolves in 100 g of water at 25° C. in an amount of at least 100 g. Further, 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.) to become water-soluble. The hydrolysis of the hydrolyzable vinyl monomer (a2) may be carried out during polymerization, after polymerization, or both. preferable.

Among these, the water-soluble vinyl monomer (a1) is preferable from the viewpoint of absorption performance and the like, and the above-described anionic vinyl monomer, carboxy (salt) group, sulfo (salt) group, amino group, and carbamoyl group are more preferable. , 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 (meth)acrylic acid (salt) and (meth)acrylamide, particularly preferred is (meth)acrylic acid (salt), most preferred is acrylic acid (salt).

In addition, "carboxy (salt) group" means "carboxy group" or "carboxylate group", and "sulfo (salt) group" means "sulfo group" or "sulfonate group". (Meth)acrylic acid (salt) means acrylic acid, acrylate, methacrylic acid or methacrylate, and (meth)acrylamide means acrylamide or methacrylamide. Examples of salts 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, alkali metal salts and ammonium salts are preferable, alkali metal salts are more preferable, and sodium salts are particularly preferable, from the viewpoint of absorption performance and the like.

When an acid group-containing monomer such as acrylic acid or methacrylic acid is used as the water-soluble vinyl monomer (a1), it is preferred that a portion of the acid group-containing monomer is neutralized with a base from the viewpoint of water absorption performance and residual monomers. . As the neutralizing base, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate, sodium hydrogencarbonate and potassium carbonate can usually be used. Neutralization may be carried out before, during, or after polymerization in the production of absorbent resin particles. A preferred example is a method of neutralizing an acid group-containing polymer in the state of a hydrous gel.

Further, when the acid group-containing monomer is used, the neutralization degree of the acid group is preferably 50 to 80 mol %. If the degree of neutralization is less than 50 mol %, the resulting hydrous gel polymer will have high adhesiveness, and workability during production and use may deteriorate. Furthermore, the water retention capacity of the resulting absorbent resin particles may decrease. On the other hand, if the degree of neutralization exceeds 80%, the resulting resin will have a high pH and may be unsafe for human skin.

When either the water-soluble vinyl monomer (a1) or the hydrolyzable vinyl monomer (a2) is used as a structural unit, each one type may be used alone as a structural unit, and if necessary, two or more types may be used as a structural unit. good. The same applies to the case where the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as structural units. Further, when the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as structural units, the molar ratio [(a1)/(a2)] of these contents 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 is further improved.

In addition to the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), other vinyl monomers (a3) copolymerizable therewith are used as structural units of the crosslinked polymer (A). can be done. 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; Hydrophobic vinyl monomers such as the vinyl monomers disclosed in paragraph 0058 of JP-A-2005-75982) can be used, and specifically, the following vinyl monomers (i) to (iii) can be used.
(i) Aromatic ethylenic monomer having 8 to 30 carbon atoms Styrene such as styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, and halogen-substituted 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) C5-C15 alicyclic ethylenic monomers monoethylenically unsaturated monomers (pinene, limonene, indene, etc.); and polyethylene vinyl monomers [cyclopentadiene, bicyclopentadiene, ethylidenenorbornene, etc.], and the like.

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

The cross-linking agent (b) is not particularly limited and is known (for example, a cross-linking 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 cross-linking agent having at least one functional group and having at least one ethylenically unsaturated group and a cross-linking agent having at least two functional groups capable of reacting with a water-soluble substituent, JP-A-2003-165883 Cross-linking agents having two or more ethylenically unsaturated groups disclosed in paragraphs 0028 to 0031, cross-linking agents having ethylenically unsaturated groups and reactive functional groups, and cross-linking agents having two or more reactive substituents , the crosslinkable vinyl monomers disclosed in paragraph 0059 of JP-A-2005-75982 and the crosslinkable vinyl monomers disclosed in paragraphs 0015-0016 of JP-A-2005-95759) can be used. . Among these, from the viewpoint of absorption performance and the like, cross-linking agents having two or more ethylenically unsaturated groups are preferable, and more preferable are triallyl cyanurate, triallyl isocyanurate and polyols having 2 to 40 carbon atoms ( Meta)allyl ethers, particularly preferred are triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane, polyethylene glycol diallyl ether and pentaerythritol triallyl ether, most preferred is pentaerythritol triallyl ether. The crosslinking agent (b) may be used alone or in combination of two or more.

The content (mol%) of the cross-linking agent (b) units is water-soluble vinyl monomer (a1) units and hydrolyzable vinyl monomer (a2) units, and when other vinyl monomer (a3) units are also used, (a1) to It is preferably from 0.001 to 5, more preferably from 0.005 to 3, and most preferably from 0.001 to 1, based on the total number of moles of (a3) units.

As the polymerization method of the crosslinked polymer (A1), known solution polymerization (adiabatic polymerization, thin film polymerization, spray polymerization, etc.; JP-A-55-133413, etc.) and known reverse phase suspension polymerization 54-30710, JP-A-56-26909 and JP-A-1-5808).

The crosslinked polymer (A1) is obtained by polymerizing a monomer composition comprising a water-soluble vinyl monomer (a1) and/or a hydrolyzable vinyl monomer (a2) and an internal crosslinking agent (b1) as essential components. However, the preferred polymerization method is the solution polymerization method, which is advantageous in terms of production cost because it does not require the use of an organic solvent, etc., so the aqueous solution polymerization method is particularly preferred. In addition, the aqueous solution adiabatic polymerization method is most preferable because a water-absorbent resin composition with a small amount of water-soluble components can be obtained and temperature control during polymerization is unnecessary.

When aqueous polymerization is carried out, a mixed solvent containing water and an organic solvent can be used, and examples of the organic solvent include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutyl alcohol and t-butyl alcohol. , isopentyl alcohol, acetone, methyl ethyl ketone, N,N-dimethylformamide, dimethylsulfoxide and mixtures of two or more thereof. The amount (% by weight) of the organic solvent used is preferably 40 or less, more preferably 30 or less, based on the weight of water.

Further, when the suspension polymerization method or the reversed-phase suspension polymerization method is employed, the polymerization may be carried out in the presence of a conventionally known dispersant or surfactant. Moreover, in the case of the reversed-phase suspension polymerization method, the polymerization can be carried out using a hydrocarbon solvent such as xylene, normal hexane and normal heptane.

When an initiator is used for polymerization, radical polymerization initiators can be used, for example, azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid and 2,2'-azobis(2-amidinopropane) hydrochloride, etc. ], inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate, etc.), organic peroxides [benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide and di(2-ethoxyethyl) peroxydicarbonate, etc.] and redox catalysts (alkaline metal sulfites or bisulfites, ammonium sulfite, ammonium bisulfite and reducing agents such as ascorbic acid and alkali metal persulfates, persulfates, A combination with an oxidizing agent such as ammonium sulfate, hydrogen peroxide and organic peroxide). These catalysts may be used alone, or two or more of them may be used in combination.
The amount (% by weight) of the radical polymerization initiator used is the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and when the other vinyl monomer (a3) is used, (a1) to (a3). , preferably 0.0005 to 5, more preferably 0.001 to 2, based on the total weight.

At the time of polymerization, a polymerization control agent represented by a chain transfer agent may be used in combination as necessary. Specific examples thereof include sodium hypophosphite, sodium phosphite, alkyl mercaptans, alkyl halides. , thiocarbonyl compounds and the like. These polymerization control agents may be used alone, or two or more of them may be used in combination.
The amount (% by weight) of the polymerization control agent used is the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2). Preferably 0.0005 to 5, more preferably 0.001 to 2, based on total weight.

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.

A water-containing gel containing water in the crosslinked polymer (A1) (hereinafter abbreviated as water-containing gel) can be obtained by the above polymerization method, and the crosslinked polymer (A1) is obtained by drying the water-containing gel. Obtainable.

The hydrous gel obtained by polymerization can be chopped before drying, if desired. The size (maximum diameter) of the gel after shredding 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 property in the drying process is further improved.

Shredding can be performed by a known method, and can be performed using a shredding device (eg, Vex mill, rubber chopper, farmer mill, mincing machine, impact pulverizer, roll pulverizer) and the like.

As a method for distilling off the solvent (including water) of the hydrous gel and drying it, a method of distilling (drying) with hot air at a temperature of 80 to 230 ° C., a drum dryer heated to 100 to 230 ° C., etc. A thin film drying method, a (heating) vacuum drying method, a freeze drying method, an infrared drying method, decantation, filtration, and the like can be applied.

When the solvent contains water, the water content (% by weight) after drying is preferably 0 to 20, more preferably 1 to 10, particularly preferably 2 to 9, most preferably 2 to 9, based on the weight of the polymer (A). is 3-8. Within this range, the absorption performance is further improved. Further, when the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably 0 to 10, more preferably 0 to 5, based on the weight of the crosslinked polymer (A1). Especially preferably 0-3, most preferably 0-1. Within this range, the absorption performance of the absorbent resin particles is further improved.

The content and water content of the organic solvent were measured using an infrared moisture meter [JE400 manufactured by KETT Co., Ltd., etc.: 120 ± 5 ° C., 30 minutes, atmospheric humidity before heating 50 ± 10% RH, lamp specification 100 V, 40 W].

The crosslinked polymer (A) can be pulverized and classified as necessary to obtain resin particles containing the crosslinked polymer (A). The method of pulverization is not particularly limited, and a pulverizer (for example, a hammer pulverizer, an impact pulverizer, a roll pulverizer, and a jet pulverizer) or the like can be used. The pulverized crosslinked polymer can be adjusted in particle size by sieving or the like, if necessary.

The weight average particle diameter (μm) of the resin particles containing the crosslinked polymer (A) is preferably 100-500, more preferably 150-480, and particularly preferably 200-450. Within this range, the absorption performance of the absorbent resin particles is further improved. From the viewpoint of absorption performance, the content (% by weight) of fine particles of 150 μm or less in the total weight of the crosslinked polymer (A) is preferably 3 or less, more preferably 1 or less.

The shape of the resin particles containing the crosslinked polymer (A) is not particularly limited, and examples thereof include irregular pulverized shape, scaly shape, pearl-like shape, rice grain-like shape, and the like. Of these, irregularly crushed forms are preferred from the viewpoints of good entanglement with fibrous materials for use in paper diapers and the like, and no fear of falling off from fibrous materials.

The crosslinked polymer (A) may contain a small amount of other components such as a residual solvent and a residual crosslinked component within a range that does not impair its performance.

Moreover, it can have a structure in which the surfaces of the resin particles containing the crosslinked polymer (A) are crosslinked with the surface crosslinking agent (d). By cross-linking the surface of the cross-linked polymer (A), the gel strength of the absorbent resin particles can be improved, and the desired water retention capacity and absorption capacity under load of the absorbent resin particles can be satisfied, which is preferable. . As the surface cross-linking agent (d), known (polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds and polyvalent isocyanate compounds described in JP-A-59-189103, etc., JP-A-58-180233 And the polyhydric alcohol of JP-A-61-16903, the silane coupling agent described in JP-A-61-211305 and JP-A-61-252212, the JP-A-5-508425 described Alkylene carbonates, polyvalent oxazoline compounds described in JP-A-11-240959, and surface-crosslinking agents such as polyvalent metals described in JP-A-51-136588 and JP-A-61-257235 can be used. Among these surface cross-linking agents, polyhydric glycidyl compounds, polyhydric alcohols and polyhydric amines are preferred from the viewpoint of economy and absorption properties, more preferred are polyhydric glycidyl compounds and polyhydric alcohols, and particularly preferred is A polyhydric glycidyl compound, most preferably ethylene glycol diglycidyl ether, may be used alone or in combination of two or more surface cross-linking agents.

The amount (parts by weight) of the surface cross-linking agent (d) used is not particularly limited because it can be varied depending on the type of the surface cross-linking agent, cross-linking conditions, target performance, etc., but from the viewpoint of absorption characteristics and the like. , preferably 0.001 to 3, more preferably 0.005 to 2, particularly preferably 0.01 to 1.5, relative to 100 parts by weight of the resin particles.

The surface cross-linking method can be carried out by mixing the resin particles containing the cross-linked polymer (A) and the surface cross-linking agent (d), and heating if necessary. Examples of the method for mixing the resin particles and the surface cross-linking agent (d) include a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a double-arm kneader, a fluid mixer, Uniformly mixing the resin particles and the surface cross-linking agent (d) using a mixing device such as a V-type mixer, a mincing mixer, a ribbon-type mixer, an airflow-type mixer, a rotating disk-type mixer, a conical blender, and a roll mixer. method. At this time, the surface cross-linking agent (d) may be diluted with water and/or any solvent before use.

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

After mixing the resin particles and the surface cross-linking agent (d), heat treatment is usually performed. The heating temperature is preferably 100 to 180°C, more preferably 110 to 175°C, particularly preferably 120 to 170°C, from the viewpoint of breaking resistance of the resin particles. Heating at 180° C. or less enables indirect heating using steam, which is advantageous in terms of facilities. Heating temperatures below 100° C. may result in poor absorption performance. The heating time can be appropriately set depending on the heating temperature, but from the viewpoint of absorption performance, it is preferably 5 to 60 minutes, more preferably 10 to 40 minutes. Moreover, the surface-crosslinked resin particles can be further surface-crosslinked using a surface-crosslinking agent that is the same as or different from the surface-crosslinking agent used first.

The crosslinked polymer (A) obtained by surface cross-linking is sieved if necessary to adjust the particle size. The weight-average particle size of the obtained particles is the same as described above, preferably 100 to 500 μm, more preferably 200 to 450 μm. The content of fine particles is preferably as small as possible, the content of particles of 100 μm or less is preferably 3% by weight or less, and the content of particles of 150 μm or less is more preferably 3% by weight or less.

In the absorbent resin particles of the present invention, the crosslinked polymer (A) may be further treated with a hydrophobic substance, and the method described in JP-A-2013-231199 or the like is used as a method for treating with a hydrophobic substance. I can.

The absorbent resin particles of the present invention are characterized by containing resin particles containing the aforementioned crosslinked polymer (A), a phyllosilicate mineral (B) and a hemolytic agent (C).

The phyllosilicate mineral (B) is also called a layered silicate mineral, and has a porous structure in which unit layers in which SiO ₄ tetrahedrons are planarly bonded as the basic unit of the crystal structure are laminated. On the other hand, the hemolytic agent (C) is a compound that breaks down the surface membrane of red blood cells, which are blood cell components in blood, to release the contents. In the present invention, by including both the phyllosilicate mineral (B) and the hemolytic agent (C) in the absorbent resin particles, the blood absorption performance is synergistically improved compared to the case where each of them is included alone. show excellent effect. Although the mechanism by which the excellent synergistic effect is exhibited is not clear, the hemolytic agent (C) disrupts the red blood cells and suppresses the deposition of the red blood cells on the surface of the absorbent resin particles. B) adsorbs soluble components such as proteins in the blood and suppresses deposition of soluble components such as proteins on the surface of the absorbent resin particles, thereby improving the absorption performance of liquid components into the absorbent resin particles. is presumed to have improved synergistically.

Phyllosilicate minerals (B) include kaolinite, smectite, illite, vermiculite, mica, chlorite, halloysite, chrysotile, talc, sepiolite, palygorskite, imogolite, gypsite, zeolite, saponite, and the like. Among these phyllosilicate minerals (B), kaolinite, smectite and illite are preferable from the viewpoint of blood absorption capacity, and kaolinite is more preferable. The phyllosilicate mineral (B) may be used singly or in combination of two or more.

The content of the phyllosilicate mineral (B) is preferably 1 to 10% by weight, more preferably 3.0 to 8.0% by weight, based on the weight of the crosslinked polymer (A), from the viewpoint of blood absorption capacity. 0% by weight.

The hemolytic agent (C) is an ammonium salt and/or a quaternary ammonium salt from the viewpoint of hemolysis, specifically ammonium chloride, benzalkonium chloride, didecyldimethylammonium chloride, lauryltrimethylammonium chloride, hexachloride. Decyltrimethylammonium, decyltrimethylammonium chloride, decyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, nonyltrimethylammonium bromide and the like. The hemolytic agent (C) may be used singly or in combination of two or more.

From the viewpoint of blood absorption capacity, the content of the hemolytic agent (C) is preferably 0.1 to 10% by weight, more preferably 0.5 to 8.0% by weight, based on the weight of the crosslinked polymer (A). 0% by weight.

In the absorbent resin particles of the present invention, the phyllosilicate mineral (B) and the hemolytic agent (C) are preferably present on the surface of the absorbent resin particles from the viewpoint of blood absorption capacity. Since the phyllosilicate mineral (B) and the hemolyzing agent (C) are present on the surface of the absorbent resin particles, hemolysis and adsorption of proteins and the like are exhibited before blood is absorbed into the inside of the particles. effectively improves blood absorption properties. For this reason, the phyllosilicate mineral (B) is preferably added to the resin particles containing the crosslinked polymer (A), and when surface-crosslinked, it is preferably added after the surface-crosslinking step.

The absorbent resin particles of the present invention can be obtained by mixing the resin particles containing the crosslinked polymer (A) with the phyllosilicate mineral (B) and the hemolytic agent (C). Mixing methods include a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a twin-arm kneader, a fluid mixer, a V mixer, a mince mixer, and a ribbon mixer. A method of uniform mixing using a known mixing apparatus such as a mixer, an airflow mixer, a rotating disc mixer, a conical blender, and a roll mixer can be used.

When mixing the resin particles containing the crosslinked polymer (A) with the phyllosilicate mineral (B) and the hemolytic agent (C), it is preferable to add (B) and (C) while stirring the resin particles. The added (B) and (C) may be added at the same time as water and/or solvent. When (B) is added simultaneously with water and/or a solvent, a dispersion in which the phyllosilicate mineral (B) is dispersed in water and/or a solvent can be added, or a solution in which the phyllosilicate mineral (B) is dispersed in water can be added. preferable. When the dispersion is added, it is preferably added by spraying or dropwise. When (C) is added simultaneously with water and/or a solvent, a solution of (C) dissolved in water and/or a solvent or a dispersion of (C) dispersed in water and/or a solvent can be added, From the viewpoint of workability, it is preferable to add a solution, and it is more preferable to add a solution dissolved in water. It can also be added as a mixed solution or mixed dispersion of (B) and (C). When adding a solution or dispersion, it is preferably added by spraying or dropwise.

When using a dispersion in which the phyllosilicate mineral (B) is dispersed in water, the content of the phyllosilicate mineral (B) contained in the dispersion is 0.5 to 30% by weight with respect to the total weight of the dispersion. is preferred, and more preferably 1.0 to 15% by weight. If the concentration is lower than the above range, the amount of water added is increased and the resin particles tend to block each other.

When using an aqueous solution obtained by dissolving the hemolytic agent (C) in water, the content of the hemolytic agent (C) contained in the aqueous solution is preferably 5 to 70% by weight based on the total weight of the aqueous solution from the viewpoint of blood absorption speed. More preferably 10 to 60% by weight. If the concentration is lower than the above range, the hemolytic agent (C) permeates into the inside of the resin particles, lowering the blood absorption capacity.

The type of solvent is not particularly limited, but polyhydric alcohols (ethylene glycol, propylene glycol, 1,4-butanediol, etc.) are preferably used, and the solvent may be used alone or in combination of two or more. Also good.

The temperature at which the resin particles containing the crosslinked polymer (A), the phyllosilicate mineral (B) and the hemolytic agent (C) are mixed is preferably 30 to 150°C, more preferably 50 to 100°C. Within this range, uniform mixing is facilitated, and absorption characteristics are further improved.

When the resin particles containing the crosslinked polymer (A), the phyllosilicate mineral (B), and the hemolytic agent (C) are mixed and then heated, the heating time can be appropriately set depending on the heating temperature, but from the viewpoint of absorption performance. , preferably 5 to 60 minutes, more preferably 10 to 40 minutes.

If the crosslinked polymer (A) is contained, after mixing with the phyllosilicate mineral (B) and the hemolytic agent (C), it may be sieved and used after adjusting the particle size, if necessary. The weight-average particle size of particles obtained by adjusting the particle size is preferably 100 to 600 μm, more preferably 150 to 500 μm. If the weight-average particle size is less than 100 μm, the blood permeation performance may deteriorate, and if it exceeds 600 μm, the blood absorption rate may deteriorate, resulting in a dry feeling.

The absorbent resin particles of the present invention may optionally contain additives (for example, known (described in JP-A-2003-225565 and JP-A-2006-131767) preservatives, antifungal agents, antibacterial agents, oxidation inhibitors, ultraviolet absorbers, colorants, fragrances, deodorants, liquid permeability improvers, organic fibrous substances, etc.). When these additives are contained, the content (% by weight) of the additives is preferably 0.001 to 10, more preferably 0.01 to 5, especially 0.01 to 5, based on the weight of the crosslinked polymer (A). It is preferably between 0.05 and 1, most preferably between 0.1 and 0.5.

The water content of the absorbent resin particles of the present invention is preferably 1 to 10% by weight, more preferably 2 to 9% by weight, still more preferably 3 to 8% by weight, from the viewpoint of absorption properties.

The apparent density (g/ml) of the absorbent resin particles of the present invention is preferably 0.52 to 0.70, more preferably 0.54 to 0.68, particularly preferably 0.56 to 0.66. . Within this range, the gel of the absorbent resin particles swollen by the absorption of blood in the absorbent article is fixed, so that the shape retention of the absorbent article after absorption of blood is further improved. The apparent density of absorbent resin particles is measured at 25° C. in accordance with JIS K7365:1999.

The water retention capacity (g/g) per unit weight of the absorbent resin particles of the present invention can be measured by the method described later, and is preferably 20 or more, more preferably 22 or more, more preferably 24, from the viewpoint of blood absorption capacity. The above is even more preferable. Moreover, the upper limit is preferably 60 or less, more preferably 55 or less, from the viewpoint of absorption under load. The amount of water retention can be appropriately adjusted by the amount (% by weight) of the cross-linking agent (b) and the surface cross-linking agent (d) used during polymerization.

The blood absorption capacity of the absorbent resin particles of the present invention expressed as the weight of blood absorbed with respect to the weight of the absorbent resin particles can be measured by the method described later, and is 10 times or more from the viewpoint of the dryness of the absorbent. is preferred, and 13 times or more is more preferred. Moreover, the upper limit is preferably 30 times or less, more preferably 25 times or less, from the viewpoint of absorption under load.

The absorbent resin particles of the present invention constitute, for example, absorbent bodies used in sanitary materials such as paper diapers, sanitary napkins, incontinence pads, and medical pads, and are suitably used in absorbent articles containing absorbent bodies. and exhibit excellent absorption properties, especially for blood or menstrual absorption applications. Absorbent articles for blood or menstrual blood, for example, sanitary napkins, tampons, medical sheets, drip absorbents, wound protection materials, wound healing materials, surgical waste fluid treatment agents, etc., are required to have blood absorption properties. and goods.

The absorbent body using the absorbent resin particles of the present invention has excellent absorption of body fluids such as blood, has excellent liquid uptake speed, and has excellent dry touch under pressure after absorption. Deformation can be suppressed.

An absorbent using absorbent resin particles is composed of, for example, absorbent resin particles and hydrophilic fibers. Specific examples of hydrophilic fibers include wood pulp fibers such as mechanical pulp, chemical pulp, semi-chemical pulp and dissolving pulp derived from wood, and artificial cellulose fibers such as rayon and acetate. Preferred hydrophilic fibers are wood pulp fibers. These hydrophilic fibers may partially contain synthetic fibers such as nylon and polyester.

The content of the absorbent resin particles in the absorbent body is preferably 5 to 95% by mass, more preferably 20 to 90% by mass, more preferably 30 to 80% by mass, from the viewpoint of lightness and thinning. It is even more preferable to have

The structure of the absorbent includes a mixed dispersion obtained by mixing absorbent resin particles and hydrophilic fibers so as to have a uniform composition, and absorbent resin particles sandwiched between layered hydrophilic fibers. a sandwich structure, a structure in which absorbent resin particles and hydrophilic fibers are wrapped in tissue, and the like. The absorber may contain other components such as heat-fusible synthetic fibers, hot-melt adhesives, and adhesive binders such as adhesive emulsions for enhancing shape retention of the absorber. .

In addition, an absorbent body using absorbent resin particles is held between a liquid permeable sheet (top sheet) through which liquid can pass and a liquid impermeable sheet (back sheet) through which liquid cannot pass. By, it can be an absorbent article. The liquid permeable sheet is arranged on the side in contact with the body, and the liquid impermeable sheet is arranged on the opposite side in contact with the body.

Examples of liquid-permeable sheets include air-through type, spunbond type, chemical bond type, needle punch type nonwoven fabrics and porous synthetic resin sheets made of fibers such as polyethylene, polypropylene and polyester. Examples of liquid-impermeable sheets include synthetic resin films made of resins such as polyethylene, polypropylene, and polyvinyl chloride.

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited to these. In addition, unless otherwise specified, parts indicate parts by weight and % indicates weight %. The water retention capacity of the absorbent resin particles in 0.9% by weight physiological saline, the blood absorption capacity, and the weight average particle size were measured by the following methods at a temperature of the measurement atmosphere of 25±2°C. Examples 3, 4, 9 and 11 are Reference Examples 3, 4, 9 and 11.

<Method for measuring water retention>
Put 1.00 g of the measurement sample in a tea bag (20 cm long, 10 cm wide) made of nylon mesh with an opening of 63 μm (JIS Z8801-1: 2006), and put it in 1,000 ml of physiological saline (salt concentration 0.9%). After being immersed for 1 hour without stirring, it was taken out and hung for 15 minutes to drain. After that, the whole tea bag was placed in a centrifuge and dehydrated by centrifugation at 150 G for 90 seconds to remove excess physiological saline. The physiological saline used and the temperature of the measurement atmosphere were 25°C ± 2°C. (h2) is the weight of the tea bag measured in the same manner as above without the measurement sample.
Water retention amount (g/g) = (h1) - (h2)

<Blood absorption ratio>
0.100 g of the sample to be measured was added to a tea bag (3.5 cm long, 3.5 cm wide) made of nylon mesh with an opening of 63 μm (JIS Z8801-1:2006), and the four sides were heat-sealed. 15.0 g of horse blood (equine EDTA whole blood, manufactured by Japan Lamb Co., Ltd.) was prepared in advance in a 100 ml beaker with a flat bottom defined in JIS R 3503, and the nylon mesh bag containing the measurement sample was immersed in the beaker for 15 minutes. . After 15 minutes, the nylon mesh was taken out, hung for 1 minute to remove excess blood, weighed (h3), and the blood absorption rate was determined from the following equation. The horse blood used and the temperature of the measurement atmosphere were 25°C ± 2°C. The weight (h4) is the weight of the tea bag measured in the same manner as above without the measurement sample.
Blood absorption rate (g / g) = ((h3) - (h4)) / 0.100

<Weight average particle size>
The weight average particle size is measured using a low-tap test sieve shaker and a JIS standard sieve (JIS Z8801-1: 2006), according to Perry's Chemical Engineers Handbook 6th Edition (McGraw-Hill Book Company, 1984, page 21). Specifically, JIS standard sieves of 710 μm, 500 μm, 300 μm, 150 μm and a tray are combined in this order from the top. Approximately 50 g of crosslinked polymer particles are placed in the top 710 μm sieve and shaken for 5 minutes on a Rotap test sieve shaker. The weight of the resin particles on each sieve and the tray was weighed, the total was taken as 100%, and the weight fraction was determined.

<Production Example 1>
Acrylic acid (a1-1) {manufactured by Mitsubishi Chemical Corporation, purity 100%} 270 parts, cross-linking agent (b-1) {pentaerythritol triallyl ether, manufactured by Daiso Co., Ltd.} 0.98 parts and ion-exchanged water 712 The parts were kept at 3°C while stirring and mixing. After nitrogen was introduced into this mixture to reduce the dissolved oxygen content to 1 ppm or less, 1.1 parts of a 1% aqueous hydrogen peroxide solution, 2.0 parts of a 2% ascorbic acid aqueous solution and 2% 2,2'-azobis were added. 13.5 parts of an aqueous amidinopropane dihydrochloride solution 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 hydrous gel.

Next, this water-containing gel was finely chopped with a mincing machine (12VR-400K manufactured by ROYAL), and 220 parts of a 49% sodium hydroxide aqueous solution was added and mixed and neutralized to obtain a neutralized gel. Furthermore, the neutralized hydrous gel is aerated and dried under the conditions of a temperature of 150° C. and a wind speed of 1.5 m/sec using an aerated dryer (manufactured by Inoue Metal Industry Co., Ltd.) until the water content reaches 4% to obtain a dry body. rice field. The dried product is pulverized with a juicer mixer (Osterizer Blender manufactured by Oster), sieved, and adjusted to a particle size range of 710 to 150 μm with an opening of 710 to 150 μm to obtain resin particles (A-1) containing a crosslinked polymer. Obtained.

Then, 100 parts of the obtained resin particles (A-1) were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Corporation: number of rotations: 2000 rpm), and ethylene glycol diglycidyl ether as a surface cross-linking agent (d) was added thereto. A mixture of 12 parts of propylene glycol, 1.0 parts of propylene glycol, and 1.7 parts of ion-exchanged water is added, mixed uniformly, and then heated at 135° C. for 30 minutes to obtain surface-crosslinked resin particles (A- 2) was obtained.

<Production Example 2>
In Production Example 1, the surface cross-linking agent (d) used in 100 parts of the resin particles (A-1) obtained was 0.12 parts of ethylene glycol diglycidyl ether to 0.20 parts, and 1.0 part of propylene glycol. A surface-crosslinked resin particle (A-3) was obtained by performing the same operation as in Production Example 1, except that the content was changed to 1.5 parts.

<Example 1>
While stirring 100 parts of the surface-crosslinked resin particles (A-2) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Corporation, rotation speed 2000 rpm), a phyllosilicate mineral (B) was obtained. 5.0 parts of kaolinite (manufactured by Junsei Chemical Co., Ltd.), 5.0 parts of ammonium chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a hemolytic agent (C), and 5.0 parts of deionized water were uniformly mixed. After that, it was heated at 80° C. for 30 minutes to obtain absorbent resin particles (P-1) of the present invention.

<Example 2>
Absorbent resin particles (P-2) of the present invention were obtained in the same manner as in Example 1, except that ammonium chloride in Example 1 was changed to benzalkonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.). .

<Example 3>
The same operation as in Example 1 was performed except that the ammonium chloride in Example 1 was changed to cationic DDC-80 (didecyldimethylammonium chloride, manufactured by Sanyo Chemical Industries, Ltd.), and the absorbent resin particles of the present invention (P -3) was obtained.

<Example 4>
Absorbent resin particles (P-4) of the present invention were obtained in the same manner as in Example 1, except that ammonium chloride in Example 1 was changed to lauryltrimethylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.). .

<Example 5>
Absorbent resin particles (P-5) of the present invention were obtained in the same manner as in Example 1, except that kaolinite in Example 1 was changed to Kunipia-F (smectite, manufactured by Kunimine Industries Co., Ltd.). .

<Example 6>
Absorbent resin particles (P-6) of the present invention were obtained in the same manner as in Example 1 except that kaolinite in Example 1 was changed to Illite (manufactured by GO Networks Co., Ltd.).

<Example 7>
While stirring 100 parts of the surface-crosslinked resin particles (A-3) obtained in Production Example 2 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Corporation, number of revolutions 2000 rpm), a phyllosilicate mineral (B) was obtained. 5.0 parts of kaolinite (manufactured by Junsei Chemical Co., Ltd.), 5.0 parts of ammonium chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a hemolytic agent (C), and 5.0 parts of deionized water were uniformly mixed. After that, it was heated at 80° C. for 30 minutes to obtain absorbent resin particles (P-7) of the present invention.

<Example 8>
While stirring 100 parts of the surface-crosslinked resin particles (A-2) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Corporation, rotation speed 2000 rpm), a phyllosilicate mineral (B) was obtained. 1.0 parts of kaolinite (manufactured by Junsei Chemical Co., Ltd.), 0.2 parts of ammonium chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a hemolytic agent (C), and 5.0 parts of deionized water were uniformly mixed. After that, it was heated at 80° C. for 30 minutes to obtain absorbent resin particles (P-8) of the present invention.

<Example 9>
The same operation as in Example 8 was performed except that the ammonium chloride in Example 8 was changed to cationic DDC-80 (didecyldimethylammonium chloride, manufactured by Sanyo Chemical Industries, Ltd.) to obtain the absorbent resin particles of the present invention (P -9) was obtained.

<Example 10>
While stirring 100 parts of the surface-crosslinked resin particles (A-2) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron Corporation, rotation speed 2000 rpm), a phyllosilicate mineral (B) was obtained. 9.0 parts of kaolinite (manufactured by Junsei Chemical Co., Ltd.), 9.0 parts of ammonium chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a hemolytic agent (C), and 5.0 parts of deionized water were uniformly mixed. After that, it was heated at 80° C. for 30 minutes to obtain absorbent resin particles (P-10) of the present invention.

<Example 11>
The same operation as in Example 10 was performed except that the ammonium chloride in Example 10 was changed to cationic DDC-80 (didecyldimethylammonium chloride, manufactured by Sanyo Chemical Industries, Ltd.), and the absorbent resin particles of the present invention (P -11) was obtained.

<Comparative Example 1>
The resin particles (A-2) obtained in Production Example 1 were directly used as absorbent resin particles (R-1) for comparison.

<Comparative Example 2>
Absorbent resin particles (R-2) for comparison were obtained in the same manner as in Example 1, except that ammonium chloride was not added.

<Comparative Example 3>
Absorbent resin particles (R-3) for comparison were obtained in the same manner as in Example 5, except that ammonium chloride was not added to Example 5.

<Comparative Example 4>
Absorbent resin particles (R-4) for comparison were obtained in the same manner as in Example 1 except that kaolinite was not added to Example 1.

<Preparation and Evaluation of Absorbent Article>
100 parts of the fluff pulp and 100 parts of the evaluation sample {each absorbent resin particles obtained in Examples and Comparative Examples} were mixed with an airflow mixer {a pad former manufactured by Autec Co., Ltd.} to obtain a mixture. Thereafter, this mixture was uniformly laminated on an acrylic plate (thickness 4 mm) so as to have a basis weight of about 500 g/m ² and was pressed at a pressure of 5 kg/cm ² for 30 seconds to obtain an absorbent. This absorber was cut into a rectangle of 10 cm x 40 cm, and water-absorbing paper (basis weight: 15.5 g/m ² , manufactured by Advantech, filter paper No. 2) of the same size as the absorber was placed above and below it, and further polyethylene was applied. An absorbent article was prepared by placing a sheet (polyethylene film UB-1 manufactured by Tamapoly Co., Ltd.) on the back side and a nonwoven fabric (basis weight 20 g/m ² , Eltas Guard manufactured by Asahi Kasei Co., Ltd.) on the surface, and the surface was subjected to the SDME method described later. The dryness value was evaluated

<Evaluation of surface dryness value by SDME method>
The detector of the SDME (Surface Dryness Measurement Equipment) tester (manufactured by WK system) was soaked in an absorbent article {horse blood (Japan Lamb EDTA whole blood, 25 ° C.)), and the absorbent article was soaked in 60 Prepared in minutes. } and set the 0% dryness value, then set the detector of the SDME tester to a dry absorbent article {prepared by heating and drying the absorbent article at 80° C. for 2 hours. } and set 100% dryness to calibrate the SDME tester. Next, set a metal ring (inner diameter 70 mm, length 50 mm) in the center of the absorbent article to be measured, inject 80 ml of horse blood, and when it has finished absorbing {until the luster of horse blood cannot be confirmed}, Remove the ring, place the SDME detector on the center of the absorbent article, start measuring the surface dryness value, read the value 5 minutes after the start of measurement, 85% or more ◎, 70% or more and less than 85% was rated as ◯, and less than 70% was rated as x. The horse blood, the measurement atmosphere, and the leaving atmosphere were 25±5° C. and 65±10% RH.

Table 1 shows the surface dryness value evaluation results for each absorbent article obtained. Table 1 also shows the water retention capacity, weight average particle size, and blood absorption capacity of the absorbent resin particles.

As is clear from the results shown in Table 1, in Examples 1 to 11 containing phyllosilicate mineral (B) and hemolytic agent (C), either phyllosilicate mineral (B) or hemolytic agent (C) Alternatively, it can be seen that the blood absorption capacity is superior and the surface dryness value is high as compared with Comparative Examples 1 to 4 that do not contain both.

The absorbent resin particles of the present invention have high blood absorption performance and are useful for sanitary napkins, tampons, medical sheets, drip absorbents, wound protection materials, wound healing materials, surgical waste fluid treatment agents, and the like.

Claims (12)

Resin particles containing a water-soluble vinyl monomer (a1) and/or a vinyl monomer (a2) that becomes water-soluble vinyl monomer (a1) by hydrolysis and a crosslinked polymer (A) having a crosslinking agent (b) as essential structural units and a phyllosilicate mineral (B) and a hemolytic agent (C), wherein the hemolytic agent (C) is one or more selected from the group consisting of ammonium chloride and benzalkonium chloride . 2. The absorbent resin particles according to claim 1, wherein the phyllosilicate mineral (B) and the hemolytic agent (C) are present on the surface of the absorbent resin particles. 3. The absorbent resin particles according to claim 1 or 2, wherein the phyllosilicate mineral (B) is at least one selected from the group consisting of kaolinite, smectite and illite. 4. The absorbent resin particles according to any one of claims 1 to 3, wherein the water retention capacity of 0.9% by weight physiological saline is 20 to 60 g/g per unit weight. The absorbent resin particles according to any one of claims 1 to 4, having a weight average particle diameter of 150 to 500 µm. 6. The absorbent resin particles according to any one of claims 1 to 5, wherein the blood absorption capacity expressed by the weight of blood absorbed with respect to the weight of the absorbent resin particles is 10 to 30 times. 7. The absorbent resin particles according to any one of claims 1 to 6, containing 1 to 10% by weight of the phyllosilicate mineral (B) based on the weight of the crosslinked polymer (A). 8. The absorbent resin particles according to any one of claims 1 to 7, containing 0.1 to 10% by weight of the hemolytic agent (C) based on the weight of the crosslinked polymer (A). 9. The absorbent resin particles according to any one of claims 1 to 8, having a structure in which the surfaces of the resin particles containing the crosslinked polymer (A) are crosslinked with a surface crosslinking agent (d). The absorbent resin particles according to any one of claims 1 to 9, which are for absorbing blood or menstrual blood. An absorbent body comprising the absorbent resin particles according to any one of claims 1 to 10. An absorbent article comprising the absorbent body of claim 11 .