JP2013133399A - Water-absorbing polymer particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide water-absorbing polymer particles excellent in water-absorption ability and under pressure liquid permeability, to provide an absorption article having the water-absorbing polymer particles as a constituent member and to provide an improving method of under pressure liquid permeable speed of the water-absorbing polymer particles.SOLUTION: (1) The water-absorbing polymer particles include a crosslinked polymer (A) having an anionic group, an amino-modified silicone (B) having ≤2,000 g/mol functional group equivalent and water insoluble inorganic fine particles (C). (2) The water absorption article has the water-absorbing particles as the constituent member. (3) In the improving method of the under pressure liquid permeable speed of the water-absorbing polymer particles, the amino-modified silicone (B) having ≤2,000 g/mol functional group equivalent and the water insoluble inorganic fine particles are brought into contact with the particles of crosslinked polymer (A) having the anionic group to be water-absorbing polymer particles.

Description

  The present invention relates to a water-absorbing polymer particle, an absorbent article having the water-absorbing polymer particle, and a method for improving a liquid passing rate under pressure of the water-absorbing polymer particle.

Water-absorbing polymer particles are used in the sanitary products field as water-absorbing substances in absorbent articles such as disposable diapers for infants, adults or incontinent persons, and sanitary napkins for women.
Since the water-absorbing polymer is used for the purpose of absorbing and fixing the liquid, it is required to have an ability to absorb and retain a large amount of liquid, that is, a high water absorption. Also, the water absorption speed of how fast the liquid can be fixed is very important. However, in absorbent articles such as disposable diapers and sanitary napkins, it has been found that not only the water absorption amount and water absorption rate of the water-absorbing polymer but also the performance of the liquid diffusion rate is very important.
In absorbent articles such as disposable diapers and sanitary napkins, excretion fluid such as urine and menstrual blood is taken into the absorbent body through the surface layer (surface sheet), and in the absorbent body, for example, in the space formed by fiber materials such as pulp It is absorbed and held by an absorption mechanism that is once held and then fixed by the water-absorbing polymer in the absorbent body. That is, the absorption speed of the liquid in the absorbent article depends not only on the speed at which the water-absorbing polymer fixes the liquid, but also on the diffusion / permeation speed of the liquid in the absorbent body.

As an index of the rate at which the water-absorbing polymer fixes the liquid, there is a water absorption rate by the vortex method, and as an index of the diffusion / permeation rate of the liquid in the absorber, there is a liquid passing rate under pressure. A water-absorbing polymer with a slow liquid passing rate under pressure is prone to gel blocking, especially during repeated absorption of the liquid, and inhibits the diffusion of the liquid in the absorber. Therefore, the water absorption rate evaluated by the vortex method is sufficient. Even if it is too fast, the absorption rate of the liquid in the absorbent article using the water-absorbing polymer may be slow.
As described above, as the performance of the water-absorbing polymer particles, a plurality of physical properties such as a water absorption capacity (amount of water absorption), a water absorption speed and a liquid permeability under pressure or non-pressure are important. However, these physical properties are often difficult properties to be compatible with each other, and are one of the problems in developing a water-absorbing polymer. For example, in general, there is a problem that liquid permeability and the like decrease when the water absorption ratio is increased.

In order to improve these problems, various methods have been conventionally proposed.
For example, Patent Document 1 discloses a water-absorbing resin in which a water-absorbing resin containing a carboxylate as a constituent component is crosslinked with a crosslinking agent such as diglycidyl ether having two or more functional groups in water and an inert solvent. Water absorption improvement methods have been proposed.
Patent Document 2 proposes a method for producing a superabsorbent polymer in which a superabsorbent polymer particle containing a carboxyl group and / or a carboxylate group is grafted with an olefinically unsaturated silane coupling agent.
Patent Document 3 proposes a method for producing a highly water-absorbing polymer in which a water-soluble and / or water-absorbing polymer is treated with alkoxy titanium in the presence of water.

Japanese Patent Publication No. 60-18690 Japanese Patent Publication No. 5-19563 JP-A-6-306118

However, the methods described in Patent Documents 1 to 3 are insufficient to achieve both the water absorption performance such as the water absorption magnification and the water absorption speed and the liquid passing performance under pressure, and further improvement in performance has been desired.
The present invention provides a water-absorbing polymer particle excellent in water absorption performance, liquid passing performance under pressure, an absorbent article having the same as a constituent member, and a method for improving the liquid passing speed under pressure of the water-absorbing polymer particles. Let it be an issue.

That is, the present invention provides the following (1) to (3).
(1) Water-absorbing polymer particles comprising a crosslinked polymer (A) having an anionic group, an amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less, and water-insoluble inorganic fine particles (C).
(2) An absorbent article having the water-absorbing polymer particles of (1) as a constituent member.
(3) A water-absorbing polymer particle, wherein the crosslinked polymer (A) particle having an anionic group is brought into contact with an amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less and water-insoluble inorganic fine particles (C). For improving the flow rate of the conductive polymer particles under pressure.

  According to the present invention, a water-absorbing polymer particle that absorbs a large amount of aqueous liquid (urine, blood, etc.) quickly and has excellent liquid permeability, an absorbent article having the same as a constituent member, and the addition of the water-absorbing polymer particle A method for improving the reduction rate can be provided.

(A) is a schematic sectional drawing of the state which decomposed | disassembled the filtration cylindrical tube of the liquid-flow rate measurement apparatus under pressure of a super absorbent polymer, (b) is a schematic sectional drawing of the weight rod of this apparatus.

[Water-absorbing polymer particles, and method for improving the liquid passing speed under pressure of the water-absorbing polymer particles]
The water-absorbing polymer particles of the present invention include a crosslinked polymer (A) having an anionic group (hereinafter also simply referred to as “crosslinked polymer (A)”), an amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less. Hereinafter, it is characterized by comprising simply “amino-modified silicone (B)” and water-insoluble inorganic fine particles (C) (hereinafter also simply referred to as “inorganic fine particles (C)”).
In addition, the method for improving the liquid passing rate under pressure of the water-absorbing polymer particles of the present invention is a method of cross-linking polymer (A) particles having an anionic group that is water-absorbing polymer particles (hereinafter simply referred to as “cross-linking polymer (A) particles”). The amino-modified silicone (B) and the inorganic fine particles (C) are brought into contact with each other.
In addition, the water-absorbing polymer particle of the present invention is not limited to the cross-linked polymer (A) within the range not impairing the effects of the present invention, in addition to bringing the amino-modified silicone (B) and the inorganic fine particles (C) into contact with the cross-linked polymer (A). ) Can be subjected to a surface treatment with a surfactant, polyhydric alcohol, hydrophilic powder or the like.
In the present invention, when the crosslinked polymer (A) contacts with the amino-modified silicone (B), the anionic group of the crosslinked polymer (A) and the amino group of the amino-modified silicone (B) react to form a salt, It is considered that the water-absorbing polymer particles having excellent absorbability and liquid permeability are effectively formed by the presence of the inorganic fine particles (C).

<Crosslinked polymer having an anionic group (A)>
The crosslinked polymer (A) used in the present invention is not particularly limited as long as it is a crosslinked polymer having an anionic group.
Examples of the anionic group include a carboxy group, a sulfo group, a sulfuric acid group, a phosphoric acid group, or a salt thereof. In these, a carboxy group, a sulfo group, or those salts are preferable from a viewpoint of chemical stability, and a carboxy group or its salt is more preferable from a viewpoint of the raw material cost of the crosslinked polymer particle which has an anionic group.
Counter ions when the anionic group is a salt include alkali metal ions such as sodium ion, potassium ion and lithium ion; alkaline earth metal ions such as calcium ion, magnesium ion and barium ion; ammonium ion and ethanolamine 1 to 3 alkylamine protonated ions, ammonium ions such as quaternary alkylammonium ions, and the like. Among these, sodium ions are preferred from the viewpoint of raw material costs.

The ratio of the anionic group that is a salt in the total anionic group of the crosslinked polymer (A) (the number of moles of the anionic group that is the salt / the number of moles of the total anionic group. Hereinafter also referred to as “degree of neutralization”) is: From the viewpoint of water absorption performance under pressure and liquid permeation performance under pressure of the water-absorbing polymer particles of the present invention, it is preferably 30 to 90 mol%, more preferably 50 to 85 mol%, still more preferably 60 to 80 mol%.
The crosslinked polymer (A) preferably contains a repeating unit derived from a monomer having an anionic group and a polymerizable unsaturated group. Specific examples of the monomer include monomers having a carboxy group and a polymerizable unsaturated group such as (meth) acrylic acid, maleic acid, itaconic acid, fumaric acid, and salts thereof; vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid , Monomers having a sulfonic acid group and a polymerizable unsaturated group, such as 2- (meth) acrylamido-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, and the like Salts; monomers having a phosphate group and a polymerizable unsaturated group such as (meth) acryloyl (poly) oxyethylene phosphate; and salts thereof; monomers having a sulfate group and a polymerizable unsaturated group such as vinyl sulfate; It is done.
When the monomer is a salt, the counter ion is the same as the counter ion of the anionic group.
Among these, from the viewpoint of chemical stability, a monomer having a carboxy group, a sulfo group, or a salt thereof and a polymerizable unsaturated group is preferable. From the viewpoint of the raw material cost of the crosslinked polymer (A), a carboxy group or The salt and the monomer which has a polymerizable unsaturated group are more preferable.
The crosslinked polymer (A) may have two or more repeating units derived from a monomer having the anionic group and the polymerizable unsaturated group.

In the present invention, the repeating unit derived from a monomer having an anionic group and a polymerizable unsaturated group means a repeating unit structure formed when the monomer is polymerized. Further, (meth) acryl means acryl or methacryl, and (meth) acryloyl means acryloyl or methacryloyl.
The crosslinked polymer (A) may contain a repeating unit derived from a monomer having an anionic group and a polymerizable unsaturated group, a repeating unit derived from a non-anionic monomer, and a hydrophilic polysaccharide such as starch.
Examples of non-anionic monomers include monomers having hydroxyl groups and polymerizable unsaturated groups such as vinyl alcohol and 2-hydroxyethyl (meth) acrylate; polyethylene glycol groups such as methoxypolyethylene glycol (meth) acrylate and polymerizable unsaturated groups. Monomers having: Amides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, vinylmethylacetamide, and monomers having a polymerizable unsaturated group.

The composition of the repeating unit derived from the monomer having an anionic group and a polymerizable unsaturated group in the crosslinked polymer (A) is preferably 30% by mass or more from the viewpoint of water absorption performance under pressure of the water-absorbing polymer particles of the present invention. 50 mass% or more is more preferable, 80 mass% or more is still more preferable, and 90-100 mass% is still more preferable.
Specific examples of the crosslinked polymer (A) include a polyacrylate crosslinked body, a poly (vinyl alcohol / acrylate) copolymer (crosslinked body), a starch-acrylate graft copolymer (crosslinked body) and polyvinyl. Cross-linked products of polymer compounds having carboxyl groups or salts thereof such as alcohol-polyanhydride maleate graft copolymers (cross-linked products), cross-linked products of polysaccharides having anionic groups such as carboxymethyl cellulose salt cross-linked products, etc. Is mentioned. Among these, from the viewpoint of water absorption performance under pressure, it is preferable to use a cross-linked polyacrylate or a starch-acrylate graft copolymer (crosslinked), and in particular, a cross-linked polyacrylate. Most preferred. The crosslinked polymer (A) may be in a water-containing state.
The said crosslinked polymer (A) can be used individually or in combination of 2 types or more, respectively.

(Form of crosslinked polymer (A))
The form of the crosslinked polymer (A) is not particularly limited. The shape of the crosslinked polymer (A) is preferably particulate or fibrous, and more preferably particulate. As the shape of the particulate crosslinked polymer (A), any shape such as an indefinite shape, a lump shape, a bowl shape, an agglomerated sphere, and a sphere can be used.
When the crosslinked polymer (A) is in the form of particles, the average particle diameter of the dried crosslinked polymer (A) (hereinafter also referred to as “dried crosslinked polymer (A)”) particles is under pressure of the water-absorbing polymer particles of the present invention. From the viewpoint of water absorption performance and ease of handling of products such as diapers during manufacture and use, preferably 1 to 1000 μm, more preferably 10 to 800 μm, still more preferably 100 to 600 μm, still more preferably 200 to 450 μm. It is.
The dry crosslinked polymer (A) is a polymer in a state where the crosslinked polymer (A) is dried under the conditions of 80 ° C. and 20 kPa until the volume reduction rate per hour becomes 0.1 mass% or less. Say.
Further, in the present invention, the average particle diameter of the dry crosslinked polymer (A) particles means a particle diameter (D50) corresponding to 50% of the cumulative sieving mass percentage, and specifically measured by the method described in Examples. Is done.

<Method for producing crosslinked polymer (A)>
Although there is no restriction | limiting in particular in the manufacturing method of a crosslinked polymer (A), For example, the following method (i)-method (iii) are mentioned.
Method (i): Method of cross-linking a polymer having an anionic group using a cross-linking agent Method (ii): Method of cross-linking a polymer having no anionic group using a cross-linking agent and then introducing an anionic group (Iii): A method in which a raw material monomer containing a monomer having an anionic group and a polymerizable unsaturated group is polymerized, and a crosslinking agent is added before the polymerization, during the polymerization, and / or after the polymerization. Among them, the method (iii) in which the introduction amount of the anionic group and the crosslinking position can be easily controlled and the water absorption performance of the water absorbent polymer particles of the present invention can be easily controlled is preferable.
Hereinafter, the method (iii) will be described more specifically.

(Raw material monomer)
In the method (iii), the raw material monomer contains a monomer having an anionic group and a polymerizable unsaturated group. Specific examples and preferred examples of the monomer having an anionic group and a polymerizable unsaturated group are as described above.
The composition of the monomer in which the anionic group in the monomer having an anionic group and a polymerizable unsaturated group forms a salt is not particularly limited, but the composition of the monomer that forms the salt is the total anionic group and polymerization. In the monomer having a polymerizable unsaturated group, it is preferably 30 to 90 mol%, more preferably 50 to 85 mol%, still more preferably 60 to 80 mol%. If the composition of the monomer that forms the salt is within this range, it is preferable since the cross-linked polymer (A) is within the preferable neutralization range without any treatment such as neutralization after the production of the cross-linked polymer (A).
The raw material monomer can include a non-anionic monomer and a hydrophilic polysaccharide in addition to a monomer having an anionic group and a polymerizable unsaturated group. Specific examples and preferred examples of the non-anionic monomer and the hydrophilic polysaccharide are as described above.
In the raw material monomer, the composition of the monomer having an anionic group and a polymerizable unsaturated group is preferably 30% by mass or more, more preferably 50% by mass or more from the viewpoint of water absorption performance under pressure of the water-absorbing polymer particles of the present invention. 80 mass% or more is still more preferable, and 90-100 mass% is still more preferable.

(Crosslinking agent)
There is no restriction | limiting in particular in the crosslinking agent used for manufacture of a crosslinked polymer (A). For example, (a) a compound having two or more hydroxyl groups in the molecule, (b) a compound having two or more polymerizable double bonds in the molecule, (c) a compound having two or more epoxy groups in the molecule, etc. Is mentioned.
(A) Compounds having two or more hydroxyl groups in the molecule include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, diethanolamine, polyoxypropylene, sorbitan fatty acid ester, trimethylolpropane. , Pentaerythritol, 1,3-propanediol, sorbitol and the like.
(B) Polyols such as allyl (meth) acrylamide; bis (meth) acrylamide, diethylene glycol diacrylate, trimethylolpropane triacrylate, polyethylene glycol diacrylate, etc., as the compound having two or more polymerizable double bonds in the molecule And (meth) acrylic acid di- or polyester; ethoxylated trimethylolpropane triacrylate and other C1-C10 polyhydric alcohol alkylene oxide adducts and (meth) acrylic acid di- Or polyester etc. are mentioned.
(C) As a compound having two or more epoxy groups in the molecule, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol triglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether And polyglycidyl ethers such as trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, and hydrogenated bisphenol A type diglycidyl ether.

Among these crosslinking agents, (b) a compound having two or more polymerizable double bonds in the molecule and (c) a compound having two or more epoxy groups in the molecule are preferred, and (c) in the molecule More preferred are compounds having two or more epoxy groups, and ethylene glycol diglycidyl ether and trimethylolpropane polyglycidyl ether are more preferred.
The above crosslinking agents can be used alone or in combination of two or more.
The amount of the crosslinking agent used is 0.001 to 10% by mass based on the polymer when the polymer having an anionic group is crosslinked or when the polymer having no anionic group is crosslinked. Is preferable, 0.005 to 2 mass% is more preferable, and 0.01 to 0.5 mass% is still more preferable.
There is no particular limitation on the addition timing of the crosslinking agent, and the crosslinking can be performed by adding before, during and / or after the polymerization of the raw material monomers.

(polymerization)
The cross-linked polymer (A) is prepared by using the above raw material monomer and cross-linking agent, for example, a reverse phase suspension polymerization method using an anionic surfactant described in Japanese Patent No. 2721658 as a dispersant, It can be obtained by polymerization by a known method such as an aqueous solution polymerization method described in Japanese Patent No. 235889. In addition, the surface of the polymer particles obtained by polymerization can be subjected to a crosslinking treatment with the crosslinking agent.
The crosslinked polymer (A) after polymerization can be neutralized, dried, pulverized and the like by a known method as necessary.

<Amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less>
As the amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less, —R ¹ NR ² R ³ (where R ¹ is an alkanediyl group having 1 to 12 carbon atoms; R ² ) in the organopolysiloxane molecule. , R ³ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, even if one or more of the hydrogen atoms of the alkanediyl group and / or the alkyl group are substituted with an OH group, a COOH group, an NH ₂ group, or the like. Well, when the carbon number of the alkanediyl group and / or the alkyl group is 2 or more, an ether bond containing an oxygen atom may be included between the carbon-carbon bonds.) Examples include modified silicone.
From the viewpoint of availability of the amino-modified silicone (B), R ¹ is preferably an alkanediyl group having 1 to 6 carbon atoms, more preferably an alkanediyl group having 2 to 4 carbon atoms, and a propane-1,3-diyl group being Further preferred. From the same viewpoint, R ² and R ³ are preferably a hydrogen atom, or an alkyl group having 1 to 6 carbon atoms in which one or more of the hydrogen atoms are substituted with an OH group, a COOH group, or an NH ₂ group. An alkyl group having 1 to 6 carbon atoms in which one of the hydrogen atoms is substituted with an NH ₂ group is more preferable, and a hydrogen atom or an aminoethyl group is still more preferable.
The position of the functional group may be any of the terminal, side chain, or both terminal and side chain of the organopolysiloxane.
As the organopolysiloxane, dimethylpolysiloxane is preferred.

When the functional group equivalent of the amino-modified silicone (B) is 2000 g / mol or less, the water-absorbent polymer particles of the present invention have high liquid permeability under pressure. From the viewpoint of liquid permeability under pressure, the functional group equivalent is preferably 100 to 2000 g / mol, and more preferably 200 to 1900 g / mol. The functional group equivalent can be calculated from the spectrum intensity of ¹ H-NMR (proton NMR) measured by a nuclear magnetic resonance measuring apparatus (NMR).
Here, “functional group equivalent” means the mass of the organopolysiloxane bonded per 1 mol of the functional group.
The molecular weight of the amino-modified silicone (B) is not particularly limited, but from the viewpoint of handleability, the number average molecular weight is preferably 100 to 100,000, more preferably 200 to 50,000, and 800 to 30. Is more preferable. The number average molecular weight of amino-modified silicone (B) is determined by acetylating active hydrogen in advance with acetic anhydride when the group represented by -R ¹ NR ² R ³ of amino-modified silicone (B) has active hydrogen. After that, when there is no active hydrogen, it can be measured by gel permeation chromatography (GPC) as it is, and in the present invention, it is a number average molecular weight in terms of standard polystyrene.
The viscosity of the amino-modified silicone (B) is not particularly limited, but is preferably 1 to 80,000 mm ² / s, more preferably 5 to 20,000 mm ² / s at ordinary temperature (25 ° C.) from the viewpoint of handleability. more preferably 8~2,000mm ² / s is, 10~1,000mm ² / s is more preferable and more. The viscosity of the amino-modified silicone (B) is measured by the method of JIS standard Z8803.
Amino-modified silicone (B) can be used individually by 1 type or in combination of 2 or more types.

The content of the amino-modified silicone (B) in the water-absorbing polymer particles of the present invention is such that when the crosslinked polymer (A) is obtained by the method (i), the liquid-absorbing performance of the water-absorbing polymer particles of the present invention under pressure is as follows. From the viewpoint of water absorption performance under pressure, and in other words, the total mass of the polymer having an anionic group and the crosslinking agent is preferably 0.01% by mass or more based on the dry crosslinked polymer (A). On the other hand, the upper limit of the content is preferably 5% by mass or less from the viewpoint of water absorption rate performance and production cost. Therefore, the content of the amino-modified silicone (B) is preferably 0.01 to 5% by mass, more preferably 0.04 to 3% by mass, and still more preferably 0.08 to 1.5% by mass.
When the cross-linked polymer (A) is obtained by the method (ii), from the same viewpoint, the content of the amino-modified silicone (B) is determined based on the polymer having no anionic group, the cross-linking agent, and the anionic group. In other words, with respect to the total mass of the anionizing agent used for the introduction, it is preferably 0.01 to 5% by mass, more preferably 0.04 to 3% by mass, and more preferably 0.08% to the dry crosslinked polymer (A). -1.5 mass% is still more preferable.
When the crosslinked polymer (A) is obtained by the method (iii), from the same viewpoint, the content of the amino-modified silicone (B) is, in other words, dry with respect to the total mass of the raw material monomer and the crosslinking agent. 0.01-5 mass% is preferable with respect to a crosslinked polymer (A), 0.04-3 mass% is more preferable, 0.08-2 mass% is still more preferable, 0.1-1.5 mass% is Even more preferred.

<Water-insoluble inorganic fine particles (C)>
Examples of the water-insoluble inorganic fine particles (C) include one or more selected from metal oxides such as silica, titanium oxide, aluminum oxide, magnesium oxide, and zinc oxide, and composite oxides such as zeolite. Among these, metal oxides are preferable, silica is more preferable, amorphous silica is preferable as silica, and fumed silica is more preferable. The inorganic fine particles (C) may be porous or non-porous.
An inorganic fine particle (C) can be used individually by 1 type or in combination of 2 or more types.
The average primary particle diameter of the inorganic fine particles (C) is preferably 30 nm or less, more preferably 20 nm or less, still more preferably 15 nm or less, from the viewpoint of the water absorption performance under pressure of the water-absorbing polymer particles of the present invention. Moreover, from a viewpoint of the handleability of inorganic fine particles (C), 3 nm or more is preferable and 5 nm or more is more preferable. The particles may be primary particles or may be particles in which primary particles are aggregated. The average primary particle diameter of the inorganic fine particles (C) can be measured by observation with a transmission electron microscope.

The bulk specific gravity of the inorganic fine particles (C) is preferably 300 g / L or less, more preferably 200 g / L or less, and even more preferably 100 g / L or less, from the viewpoint of water absorption performance under pressure of the water-absorbing polymer particles of the present invention. Further, the lower limit of the bulk specific gravity is preferably 3 g / L or more, more preferably 10 g / L or more, and further preferably 20 g / L or more from the viewpoint of handling of the inorganic fine particles (C) such as generation of static electricity. Here, the bulk specific gravity is a value measured by the method of JIS standard K6720-2.
Although the specific surface area of the inorganic fine particles (C) is not particularly limited, from the viewpoint of pressure water absorbency of the water absorbent polymer particles of the present invention, preferably at least 10 m ² / g, more preferably at least 50m ² / g, 100m ² / g or more is more preferable, and 200 m ² / g or more is more preferable. From the viewpoint of the strength of the inorganic fine particles (C), preferably 2000 m ² / g or less, more preferably 1200 m ² / g, more preferably not more than 1000 m ² / g.
In this specification, the specific surface area of the inorganic fine particles (C) covers the surface as a monomolecular layer from the adsorption amount of the gas adsorbed on the surface of the inorganic fine particles, the equilibrium pressure at that time, and the saturated vapor pressure of the adsorbed gas. This refers to the BET specific surface area calculated by obtaining the amount of gas and multiplying this by the average cross-sectional area of adsorbed gas molecules, and nitrogen gas is used as the adsorbed gas. According to this method, the surface area value including pores is measured.

The content of the inorganic fine particles (C) in the water-absorbing polymer particles of the present invention is such that, when the cross-linked polymer (A) is obtained by the method (i), the liquid-absorbing performance of the water-absorbing polymer particles under pressure, From the viewpoint of water absorption performance, the total mass of the polymer having an anionic group and the crosslinking agent is preferably 0.01% by mass or more with respect to the dry crosslinked polymer (A). On the other hand, the upper limit of the content of the inorganic fine particles (C) is preferably 5% by mass or less from the viewpoint of production cost. Therefore, the content of the inorganic fine particles (C) is preferably 0.01 to 5% by mass, more preferably 0.1 to 3% by mass, and still more preferably 0.2 to 1% by mass.
When the crosslinked polymer (A) is obtained by the method (ii), from the same viewpoint, the content of the inorganic fine particles (C) is determined by introducing a polymer having no anionic group, a crosslinking agent, and an anionic group. In other words, with respect to the total mass of the anionizing agent used in the step, 0.01 to 5% by mass is preferable, 0.1 to 3% by mass is more preferable, and 0.2 to 1% by mass is more preferable.
When the crosslinked polymer (A) is obtained by the method (iii), from the same viewpoint, the content of the inorganic fine particles (C) is, in other words, dry crosslinking with respect to the total mass of the raw material monomer and the crosslinking agent. 0.01-5 mass% is preferable with respect to a polymer (A), 0.1-3 mass% is more preferable, 0.2-1 mass% is still more preferable.

[Method for producing water-absorbing polymer particles]
The water-absorbing polymer particles of the present invention can be obtained by contacting and adhering the amino-modified silicone (B) and the inorganic fine particles (C) to the crosslinked polymer (A). If the crosslinked polymer (A) is larger than the desired shape of the water-absorbing polymer particles, the amino-modified silicone (B) and / or inorganic fine particles (C) can be attached and then pulverized by a known method. From the viewpoint of homogeneously treating the surface of the crosslinked polymer (A) with the amino-modified silicone (B) and the inorganic fine particles (C), before the adhesion of the amino-modified silicone (B) and the inorganic fine particles (C), the crosslinked polymer (B) It is preferable to make A) into a desired shape.
There is no particular limitation on the order of contacting the amino-modified silicone (B) and the inorganic fine particles (C). From the viewpoint of liquid passing speed under pressure, it is preferable that the inorganic fine particles (C) are contacted after the amino-modified silicone (B) is contacted.

<Method of contacting amino-modified silicone (B)>
When the amino-modified silicone (B) is brought into contact with the crosslinked polymer (A) after contacting the crosslinked polymer (A) or the inorganic fine particles (C), the form of the amino-modified silicone (B) during the contact operation is not particularly limited. Only the modified silicone (B) may be contacted and adhered, or the amino-modified silicone (B) may be diluted with a solvent and contacted to adhere. From the viewpoint of contact operation and cost, it is preferable that only the amino-modified silicone (B) is brought into contact and adhered. However, when the viscosity of the amino-modified silicone (B) is high, the amino-modified silicone (B) is uniformly attached to the cross-linked polymer (A), and the water-absorbing polymer particles have a liquid passing performance under pressure and a water absorbing performance under pressure. From the viewpoint of homogeneous expression, the amino-modified silicone (B) is preferably diluted with a solvent and brought into contact with the crosslinked polymer (A) for adhesion.
Although there is no limitation on the temperature at the time of contact and adhesion, from the viewpoints of quality such as coloring of the water-absorbing polymer particles, liquid passage performance under pressure and water absorption performance under pressure, and cost of contact operation, 0 to 200 ° C. It is preferable that it is 10-100 degreeC. When a solvent is used for the contact operation of the amino-modified silicone (B), it is preferably performed at a temperature equal to or lower than the boiling point of the solvent at normal pressure.

(solvent)
When the amino-modified silicone (B) is diluted with a solvent and brought into contact with the crosslinked polymer (A) after contact with the crosslinked polymer (A) or inorganic fine particles (C), the solvent at the time of dilution is not particularly limited. A solvent having a boiling point in the range of 0 to 200 ° C. at normal pressure, which is easy to handle and can be easily removed by decompression after the amino-modified silicone (B) is attached, is preferable.
Specifically, water; alcohol having 1 to 8 carbon atoms such as methanol, ethanol, isopropyl alcohol and cyclohexanol; ketone having 3 to 8 carbon atoms such as acetone and methyl isobutyl ketone; total carbon such as methyl acetate and ethyl acetate Esters having a number of 3 to 10; ethers having a total carbon number of 2 to 10 such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, dioxane, dibutyl ether; ethylene glycol; pentane, hexane, heptane, methylcyclohexane, octane, decane, etc. C5-C10 aliphatic hydrocarbons and C6-C10 aromatic hydrocarbons such as toluene.
Among these, from the viewpoint of uniformly expressing the water-absorbing polymer particles of the present invention in terms of liquid passing performance under pressure and water absorption performance under pressure, alcohols having 1 to 8 carbon atoms, ketones having 3 to 8 carbon atoms, total carbon An ester having 3 to 10 carbon atoms, an ether having 2 to 10 carbon atoms, ethylene glycol, and an aliphatic hydrocarbon having 5 to 10 carbon atoms are preferable.

  Although the amount of the solvent used at the time of dilution is not particularly limited, from the viewpoint of uniformly attaching the amino-modified silicone (B) to the crosslinked polymer (A) after the adhesion of the crosslinked polymer (A) or the inorganic fine particles (C), the amino-modified silicone It is preferable that it is 1 mass times or more with respect to silicone (B). On the other hand, an increase in the amount of solvent at the time of dilution leads to an increase in load when the solvent is removed after contact with the amino-modified silicone (B). It is preferable that it is 100 mass times or less. From the above viewpoint, the amount of the solvent used for dilution is preferably 1 to 100 times by mass, more preferably 2 to 50 times by mass, and more preferably 5 to 20 by mass with respect to the amino-modified silicone (B). More preferably, it is doubled.

(Contact method)
There is no particular limitation on the method in which the crosslinked polymer (A) or the crosslinked polymer (A) after adhering to the inorganic fine particles (C) is contacted with the amino-modified silicone (B) or a solution or dispersion containing the amino-modified silicone (B). Can be done by spraying.
The contact between the crosslinked polymer (A) or the inorganic modified fine particles (C) after adhesion of the crosslinked polymer (A) or the inorganic fine particles (C) is caused by contacting the crosslinked polymer (A) or the crosslinked polymer (A) after the inorganic fine particles (C) are adhered. ) Is preferably carried out while stirring the crosslinked polymer (A) or the crosslinked polymer (A) after the adhesion of the inorganic fine particles (C).

<Method of contacting inorganic fine particles (C)>
There is no particular limitation on the method of contacting the inorganic fine particles (C) with the crosslinked polymer (A) after the cross-linked polymer (A) or amino-modified silicone (B) has been attached, and the inorganic fine particles (C) are dispersed and brought into contact with the solvent. However, from the viewpoint of contact operation and cost, it is preferable that only the inorganic fine particles (C) are brought into contact and adhered.
There is no particular limitation on the method of bringing the crosslinked polymer (A) or the dispersion polymer containing the inorganic fine particles (C) into contact with the crosslinked polymer (A) after adhering to the amino-modified silicone (B). In the case of only a), it can be simply added and mixed, and in the case of a dispersion containing inorganic fine particles (C), it can be contacted by dropping or spraying.
The contact between the crosslinked polymer (A) or the amino-modified silicone (B) after the cross-linked polymer (A) or the inorganic fine particles (C) is brought into contact with the cross-linked polymer (A) or the cross-linked polymer (A) after the amino-modified silicone is adhered. From the viewpoint of uniformly adhering the inorganic fine particles (C), it is preferable to carry out the stirring of the crosslinked polymer (A) or the crosslinked polymer (A) after the amino-modified silicone is adhered.
Although there is no limitation in the temperature at the time of contact, it is 0-200 degreeC from a viewpoint of the quality, such as coloring of a water-absorbing polymer particle, and the viewpoint of the liquid passage performance under pressure and water absorption performance under pressure, and the cost of contact operation. Is preferable, and it is preferable that it is 10-100 degreeC. When a solvent is used for the contact operation of the inorganic fine particles (C), it is preferably performed at a temperature equal to or lower than the boiling point of the solvent at normal pressure.
Between the step of bringing the amino-modified silicone (B) into contact with the step of bringing into contact with the inorganic fine particles (C), steps such as drying, pulverization, and surface treatment can be performed by a known method, if necessary.
The obtained water-absorbing polymer particles can be subjected to treatments such as drying and pulverization by a known method, if necessary, to reduce the solvent and moisture, and to control the average particle diameter. It can also be done.

<Physical properties of water-absorbing polymer particles>
(Average particle diameter of water-absorbing polymer particles)
The average particle diameter of the water-absorbing polymer particles in the dry state (hereinafter also referred to as “dried water-absorbing polymer particles”) is the water absorption performance under pressure of the water-absorbing polymer particles of the present invention, and the products such as diapers are manufactured and used. From the viewpoint of ease of handling, the thickness is preferably 1 to 1000 μm, more preferably 10 to 800 μm, still more preferably 100 to 600 μm, and still more preferably 200 to 450 μm. If the average particle size of the dried water-absorbing polymer particles is 1 μm or more, it is difficult to become “mako” even during water absorption, and if it is 1000 μm or less, the water absorption speed is high, and the feel when blended into a product such as a diaper is also good. It is good.
In the present invention, the dry water-absorbing polymer particles are a state in which the water-absorbing polymer particles are dried under the conditions of 80 ° C. and 20 kPa until the volume reduction rate per hour is 0.1% by mass or less. The polymer particles.
Moreover, the average particle diameter of the dry water-absorbing polymer particles means a particle diameter (D50) corresponding to 50% of the cumulative sieving mass percentage, and is specifically measured by the method described in the examples.

(Centrifuge retention of water-absorbing polymer particles)
The centrifugal retention amount of the water-absorbing polymer particles of the present invention is preferably 10 to 50 g / g, more preferably 15 to 40 g / g, from the viewpoint of liquid permeability under pressure and water absorption performance under pressure. Here, the centrifugal retention amount is the water retention amount under pressure after the water-absorbing polymer particles have absorbed water, and can be measured by a method based on JIS K 7223. Specifically, in the examples It is measured by the described measurement method.
The centrifugal retention amount of the water-absorbing polymer particles can be adjusted by adjusting the surface crosslinking degree of the water-absorbing polymer particles or the crosslinked polymer (A). Increasing the degree of surface cross-linking of the water-absorbing polymer decreases the centrifugal retention. Further, the amount of centrifugal retention can be adjusted by the degree of crosslinking of the entire water-absorbing polymer particles, and the amount of centrifugal retention can be lowered by increasing the degree of crosslinking of the entire water-absorbing polymer particles.

(Water absorption time of water-absorbing polymer particles)
The water absorption time of the water-absorbing polymer particles of the present invention is preferably 120 seconds or less from the viewpoint of avoiding leakage of urine when applied to products, for example, when applied to diapers, by the vortex method. In the present invention, the water absorption time obtained by the vortex method is used as an index of the water absorption rate, and the shorter the water absorption time, the higher the water absorption rate. In addition, from the viewpoint of achieving both the liquid passing rate under pressure of the water-absorbing polymer particles of the present invention and the amount absorbed under pressure, the water absorption time is preferably 5 seconds or more, more preferably 5 to 100 seconds, and still more preferably. It is 15 to 80 seconds, and more preferably 25 to 60 seconds. The water absorption time by the vortex method of the water-absorbing polymer particles of the present invention is specifically measured by the method described in the examples.
Adjustment of water absorption time by vortex method is the adjustment of particle size, primary cross-linking density, surface cross-linking degree (adjustment of cross-linking amount after polymerization), shape control, various surfactants, polyhydric alcohols, hydrophilicity of water-absorbing polymer particles. It can be carried out by surface treatment of the water-absorbing polymer with powder or the like.

(Liquid absorption speed of water-absorbing polymer particles under pressure)
The water-absorbing polymer particles of the present invention have a physiological saline flow rate under a pressure of 2.0 kPa, preferably 20 ml / min or more, more preferably from the viewpoint of absorption performance when used for absorbent articles. Is 25 to 500 ml / min, more preferably 30 to 300 ml / min, still more preferably 40 to 200 ml / min. If the liquid flow rate is within the above range, it is expected that the water absorption performance is improved in general such that water once absorbed from the water-absorbing polymer particles is not easily discharged and adhesion to the skin or liquid leakage hardly occurs. In addition, even if it is a case where this liquid flow rate exceeds 500 ml / min, performance required as an absorber can be ensured by using together with a pulp etc.
The flow rate of physiological saline under pressure at 2.0 kPa is measured using the measuring method and apparatus described in paragraphs [0008] and [0009] of FIGS. Can be measured. Specifically, the physiological saline flow rate under pressure of 2.0 kPa means that physiological saline containing a swollen absorbent polymer is placed in a filtration cylindrical tube having an inner diameter of 25.4 mm. The rate of fluid passage (ml / min) when 20 ml of physiological saline passes through the filtration cylindrical tube when a weight is placed so that a load of 2.0 kPa is applied. expressed.
Flow rate (ml / min) = 20 × 60 / (T ₁ −T ₀ ) (1)
(Where T ₁ (seconds) indicates the time required for 20 ml of physiological saline to pass with the absorbent polymer placed in the filtration cylindrical tube, and T ₀ (seconds) is absorbed in the filtration cylindrical tube. It shows the time required for 20 ml of physiological saline to pass through without the functional polymer.)
More specifically, the flow rate is measured by the method described in the examples.
In the present invention, when the amino-modified silicone (B) is brought into contact with the crosslinked polymer (A) particles which are water-absorbing polymer particles, a salt is formed, and the inorganic fine particles (C) are present therein, whereby the aforementioned It can improve so that the liquid passing rate under pressure of the water-absorbing polymer particles may be improved.

(Absorption of water-absorbing polymer particles under pressure)
The water-absorbing polymer particles of the present invention are 2.0 kPa at the time of product application, for example, from the viewpoint of the liquid absorption amount of the product under pressure such as body weight and the liquid absorption amount of the product under no pressure condition. Is preferably 5 to 40 g / g, more preferably 10 to 35 g / g. The absorption amount under pressure at 2.0 kPa is specifically measured by the method described in the examples.
Water-absorbing polymer particles of the present invention, from the viewpoint of water absorption rate, it is preferable that a bulk specific gravity of 0.5~0.8g / cm ^3, more preferably 0.55~0.7g / cm ³ .

[Absorbent articles]
The absorbent article of the present invention has the water-absorbing polymer particles of the present invention as a constituent member.
By applying the water-absorbing polymer particles of the present invention as a constituent member to various absorbent articles, an article having an excellent absorbent capacity can be obtained. The form in which the water absorbent polymer particles are applied to the absorbent article may be any form in which the water absorbent polymer particles are held in the absorbent article. For example, (i) a form in which water-absorbing polymer particles are dispersed between layers of fibrous materials such as pulp and heat-fusible fibers arranged in layers, (ii) fibers such as pulp and heat-fusible fibers And (iii) a form sandwiched between two or more water-absorbing sheets or non-woven fabrics.
Typical examples of the above (iii) include a liquid-permeable top sheet, a liquid-impermeable or water-repellent back sheet, and a form in which water-absorbing polymer particles are held between both sheets. Examples of the liquid permeable sheet include a nonwoven fabric made of polyethylene, polypropylene, polyester, or a porous synthetic resin sheet, and examples of the liquid impermeable or water repellent sheet include synthetic materials made of polyethylene, polypropylene, polyvinyl chloride, and the like. Examples include, but are not limited to, a resin film or a film made of a composite material of a synthetic resin and a nonwoven fabric.
The absorptive article may be provided with various members according to a specific use. For example, when the absorbent article is a disposable diaper, a sanitary napkin, or the like, a pair or two or more pairs of three-dimensional guards can be arranged on the left and right side portions on the top sheet.
The amount of water-absorbing polymer particles added to the absorbent article can be appropriately determined according to the type and size of the absorbent article and the target absorption performance. For example, when the absorbent article is a paper diaper or incontinence pad, it is usually 3 to 20 g / sheet, and when the absorbent article is a sanitary napkin, panty liner, etc., it is usually 0.2 to 3 g / piece. When applied to a sheet-like material sandwiched between two or more water-absorbing sheets or non-woven fabric, it is usually about 10 to 80 g / m ² .

  The conditions of various analysis methods used in Examples and Comparative Examples are shown below. In the examples, “%” means “% by mass” unless otherwise specified.

<Calculation method of average particle diameter of crosslinked polymer (A)>
Combine the test sieve (see JIS-Z8801-1) from the top in the order of 850 μm, 600 μm, 500 μm, 355 μm, 106 μm, tray, and put about 50 g of the dry cross-linked polymer (A) on the top sieve. Shake for 10 minutes on an automatic sieve shaker.
After measuring the weight of the dried crosslinked polymer (A) particles remaining on each sieve, the size of each sieve opening and the particles that could not pass through the sieve (particles remaining on the sieve and larger The mass ratio (residual percentage) R relative to the total of the particles remaining on the sieve with a mesh opening is plotted on a semilogarithmic graph (horizontal axis: particle size (logarithmic scale), vertical axis: residual percentage), R = 50 The particle diameter corresponding to% was obtained and used as the average particle diameter.
<Calculation method of average particle diameter of water-absorbing polymer particles>
In the contact between the amino-modified silicone (B) and the inorganic fine particles (C) and the drying operation, operations such as pulverization are not performed. Therefore, the average particle size of the dried crosslinked polymer (A) is the average particle size of the water-absorbing polymer particles. Considered.

<Measurement of centrifugal retention>
Nylon woven fabric (mesh opening 255, sold by Sanriki Manufacturing Co., Ltd., product name: nylon net, standard: 250 x mesh width x 30 m) is cut into a rectangle with a width of 10 cm and a length of 40 cm and folded in the middle in the longitudinal direction Then, both ends were heat-sealed to prepare a nylon bag having a width of 10 cm (inner dimension: 9 cm) and a length of 20 cm. 1.00 g of water-absorbing polymer particles are precisely weighed and placed uniformly in the bottom of the produced nylon bag, and the nylon bag is conditioned at 25 ° C. with physiological saline (0.9% by mass sodium chloride water). Soaked. After 30 minutes from the start of soaking, the nylon bag was taken out from the physiological saline, suspended in a vertical state for 1 hour, drained, and then dehydrated using a centrifugal dehydrator (model H-130C, manufactured by Kokusan Co., Ltd.). The dehydrating condition was 143 G (800 rpm) for 10 minutes. After dehydration, the mass of the sample was measured, and the centrifugal retention amount (g / g) was calculated by the following formula (2).
Centrifugal retention amount (g / g) = (a′−bc) / c (2)
In the formula (2), a ′ represents the total mass (g) of the sample and the nylon bag after centrifugal dehydration, b represents the mass (g) of the nylon bag before water absorption (when dried), and c represents the water absorption of the sample. The mass (g) before (when dried) is shown. The amount of centrifugal retention was measured 5 times (n = 5), the values at each of the upper and lower points were deleted, and the average value of the remaining three points was taken as the measured value.

<Measurement method of water absorption time by vortex method>
A 100 mL glass beaker, 50 mL of physiological saline (0.9% by mass sodium chloride water) and a magnetic stirrer chip (center diameter 8 mm, both ends diameter 7 mm, length 30 mm, surface coated with fluororesin ) And the beaker was placed on a magnetic stirrer (manufactured by As One Co., Ltd., HPS-100). The rotational speed of the magnetic stirrer was adjusted to 600 ± 5 rpm, and the physiological saline was stirred. 2.0 g of the water-absorbing polymer particles as a measurement sample was put into the liquid at the center of the vortex of the saline solution being stirred, and the water absorption rate (seconds) of the water-absorbing polymer particles in accordance with JIS K 7224 (1996). ) Was measured. Specifically, the stopwatch is started when the absorption of the water-absorbing polymer into the beaker is completed, the stopwatch is stopped when the vortex disappears after the stirrer chip is covered with the test solution, and the time ( Seconds) was recorded as the water absorption time by vortex method. The measurement was repeated 5 times, the value at each of the upper and lower points was deleted, and the average value of the remaining three points was taken as the measured value. These measurements were performed at 25 ± 2 ° C. and a humidity of 50 ± 5%, and the samples were stored for 24 hours or more in the same environment before the measurement.

<Measurement method of liquid flow rate under pressure>
The liquid passing rate under pressure of the water-absorbing polymer particles can be measured using the measuring apparatus shown in FIG. FIG. 1A is a schematic cross-sectional view of a state in which a filtration cylindrical tube of a liquid flow rate measuring device under pressure is disassembled, and FIG. 1B is a schematic cross-sectional view of a weight bar of the device. This measuring device is composed of a cylindrical tube (1), a wire mesh (2), a filtration cylindrical tube (a) composed of a narrow tube (4) with a cock (3), and a weight bar (b).
The procedure for measuring the flow rate under pressure using this measuring apparatus is as follows.
In a 100 mL glass beaker, an amount of physiological saline (0.9 mass% chloride) sufficient to swell the water-absorbing polymer particles 0.32 ± 0.005 g as a measurement sample (more than 5 mass times the water-absorbing polymer particles). (Sodium water) and left for 30 minutes. Separately, at the lower end of an opening of a vertically standing cylinder (inner diameter 25.4 mm), a wire mesh (mesh opening 150 μm, biocolumn sintered stainless steel filter 30SUS sold by Sansho Co., Ltd.) and a capillary (with an inner diameter of 2 mm) ( A filtration cylindrical tube having an inner diameter of 4 mm and a length of 8 cm) was prepared, and the contents of the beaker including the swollen measurement sample after being allowed to stand for 30 minutes were put into the cylindrical tube with the cock closed. . Next, a cylindrical rod having a diameter of 2 mm with a wire mesh having an opening of 150 μm and a diameter of 25 mm is inserted into the filtration cylindrical tube so that the wire mesh and the measurement sample are in contact with each other. The weight was placed so that the load of.
After standing in this state for 1 minute, the cock is opened to flow the liquid, and the time until the liquid level in the filtration cylindrical tube reaches the 40 mL scale line from the 60 mL scale line (that is, 20 mL of liquid passes) (T ₁ ) (Seconds). Using the measured time T ₁ (seconds), the flow rate under a pressure of 2.0 kPa was calculated from the equation (1).
The measurement was performed 5 times (n = 5), the values at each of the upper and lower points were deleted, and the average value of the remaining three points was taken as the measured value. This measurement was performed at 25 ± 2 ° C. and a relative humidity of 50 ± 5%, and the sample was stored in the same environment for 24 hours or more before the measurement.

Preparation Example 1 (Preparation of phosphate ester compound)
In a 500 mL four-necked round bottom flask equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet tube, “polyoxyalkylene (ethylene oxide / propylene oxide / ethylene oxide = 5/4/5 (molar ratio conversion) Of triblock type) alkyl [carbon number 12 / carbon number 14 = 7/3 (in terms of mass ratio of raw material alcohol)] ether (hydroxyl value: 63.8 mgKOH / g) ”was charged. Subsequently, stirring was performed at 200 rpm while introducing nitrogen gas at 50 mL / min, and the temperature increase was started. Nitrogen substitution was performed for 40 minutes after the temperature of the oil bath reached the set value of 40 ° C. (inner temperature was 35 to 38 ° C.). To this, 17.75 g of phosphoric anhydride was added while keeping the internal temperature from exceeding 60 ° C. After completion of the addition, the internal temperature was raised to 60 ° C. and stirred for 1 hour. Furthermore, the internal temperature was raised to 80 ° C. and stirred for 15 hours. To this was added 9.53 g of ion-exchanged water, and the mixture was further stirred for 4 hours to prepare a phosphate ester compound.

Example 1
(1) Production of Crosslinked Polymer (A-1) In Preparation Example 1 as a 5 L reaction vessel (using anchor blades) made of SUS304 equipped with a stirrer, reflux condenser, monomer dropping port, nitrogen gas inlet tube, thermometer, and dispersant. 0.59 g of the obtained phosphoric ester compound was charged, and 1440 mL of normal heptane was added. The temperature was raised to 90 ° C. while stirring in an atmosphere of nitrogen gas.
On the other hand, after diluting 506.2 g of 80.6% acrylic acid (manufactured by Toa Gosei Co., Ltd.) in a 2 L three-necked flask with 212.8 g of ion-exchanged water, cooling and stirring so that the internal temperature does not exceed 30 ° C. Then, 330.8 g of a 49.3% aqueous sodium hydroxide solution was added dropwise to obtain 1049.8 g of sodium acrylate (72% neutralized product) as an aqueous monomer solution. To this aqueous monomer solution, 0.25 g of N-acylated glutamic acid soda (trade name: Amisoft PS-11, manufactured by Ajinomoto Co., Inc.) diluted and dispersed in 4.41 g of ion-exchanged water was added and mixed. The solution was equally divided into an aqueous solution A and a monomer solution B.
Then, 2,2′-azobis (2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-50) 0.053 g, polyethylene glycol (manufactured by Kao Corporation, K-PEG6000LA) 0. 204 g, ammonium iron citrate (III) (manufactured by Kanto Chemical Co., Inc.) 0.55 mg, and ion-exchanged water 7.0 g were mixed and dissolved to prepare an initiator (A) solution. Further, 0.57 g of sodium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 10 g of ion-exchanged water to prepare an initiator (B) solution. Furthermore, a 50% citric acid aqueous solution and a titanyl sulfate aqueous solution (7.6% concentration in terms of TiO ₂ ) were mixed at a mass ratio of 20/27 to prepare a titanium citrate aqueous solution.
Monomer A was prepared by adding the initiator (A) solution to the monomer aqueous solution A, and the monomer B was prepared by adding the initiator (B) solution and 2.36 g of the titanium citrate aqueous solution to the monomer aqueous solution B.
Subsequently, the monomer A was dripped over 30 minutes from the monomer dropping port in the 5 L reaction vessel described above, and then the monomer B was dropped over 30 minutes for polymerization. Subsequently, 269 g of water was dehydrated by azeotropic dehydration, and after adjusting the water content of the generated particles (hydrogel), ethylene glycol diglycidyl ether (trade name: Denacol EX-810, manufactured by Nagase ChemteX Corporation) as a crosslinking agent. ) A solution prepared by dissolving 0.265 g in 10 g of ion-exchanged water was added. Thereafter, 140 g of water was dehydrated by azeotropic dehydration, and 1.58 g of a 60% 1-hydroxyethylidene-1,1′-diphosphonic acid aqueous solution (trade name Bride ADPA-60A, manufactured by Rhodia) was added. After cooling, normal polymer was removed by removing normal heptane.
The crosslinked polymer (A-1) was dried with an 80 ° C. vacuum dryer (20 kPa) for 14 hours to obtain a dried crosslinked polymer (A-1). The average particle size was 398 μm.

(2) Production of water-absorbing polymer particles (1) To 15 g of the dried crosslinked polymer (A-1) obtained above, amino-modified silicone (trade name: KF-393, manufactured by Shin-Etsu Silicone Co., Ltd., functional group equivalent: 350 g / mol, viscosity 70 mm ² / s, number average molecular weight 3500) 0.03 g was sprayed and mixed well at room temperature. Thereafter, 0.075 g of fumed silica (trade name: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd., average primary particle size 12 nm, bulk specific gravity 50 g / L, specific surface area 200 m ² / g) is added and mixed well at room temperature. Thus, water-absorbing polymer particles (1) were obtained.
Table 1 shows the measurement results of the centrifugal retention amount of the water-absorbent polymer particles (1), the water absorption time by the vortex method, and the liquid passing speed under pressure.

Example 2
To 15 g of the crosslinked polymer (A-1) obtained in Example 1 (1) before drying, amino-modified silicone (trade name: KF-8010, manufactured by Shin-Etsu Silicone Co., Ltd., functional group equivalent: 430 g / mol, viscosity: 12 mm ² / S, number average molecular weight 860) A solution obtained by diluting 0.015 g to 1.5 g with normal heptane was sprayed, mixed well at room temperature, and dried in a vacuum dryer at 80 ° C. for 14 hours. Thereafter, 0.075 g of fumed silica (Aerosil 200) used in Example 1 was added and mixed well at room temperature to obtain water-absorbing polymer particles (2). The results are shown in Table 1.
Example 3
0.075 g of fumed silica (Aerosil 200) used in Example 1 was added to 15 g of the dried crosslinked polymer (A-1) obtained in Example 1 (1), and mixed well at room temperature. Thereafter, 0.03 g of amino-modified silicone (KF-393) used in Example 1 was sprayed and mixed well at room temperature to obtain water-absorbing polymer particles (3). The results are shown in Table 1.
Example 4
Except having changed the quantity of fumed silica (Aerosil 200) into 0.045g, it carried out similarly to Example 1 and obtained the water absorbing polymer particle (4). The results are shown in Table 1.
Example 5
Except having changed the quantity of fumed silica (Aerosil 200) into 0.12g, it carried out similarly to Example 1 and obtained the water absorbing polymer particle (5). The results are shown in Table 1.

Comparative Example 1
The centrifugal retention amount of the dried crosslinked polymer (A-1) obtained in Example 1 (1), the water absorption time by the vortex method, and the liquid passing speed under pressure were measured in the same manner as in Example 1. The results are shown in Table 1.
Comparative Example 2
By spraying 0.03 g of the amino-modified silicone (KF-393) used in Example 1 to 15 g of the dry crosslinked polymer (A-1) obtained in Example 1 (1) and mixing well at room temperature, Water-absorbing polymer particles (6) were obtained. The results are shown in Table 1.
Comparative Example 3
By adding 0.075 g of fumed silica (Aerosil 200) used in Example 1 to 15 g of the dried crosslinked polymer (A-1) obtained in Example 1 (1), and mixing well at room temperature, water absorption Polymer particles (7) were obtained. The results are shown in Table 1.

Example 6
(1) Production of crosslinked polymer (A-2) Monomer A and monomer B were prepared in the same manner as in Example 1.
Subsequently, the monomer A was dripped over 30 minutes from the monomer dropping port in the 5 L reaction vessel described above, and then the monomer B was dropped over 30 minutes for polymerization. Subsequently, 269 g of water was dehydrated by azeotropic dehydration, and after adjusting the water content of the generated particles (hydrogel), ethylene glycol diglycidyl ether (trade name: Denacol EX-810, manufactured by Nagase ChemteX Corporation) as a crosslinking agent. ) 0.245 g dissolved in 10 g of ion exchange water was added. Thereafter, 140 g of water was dehydrated by azeotropic dehydration, and 1.58 g of a 60% 1-hydroxyethylidene-1,1′-diphosphonic acid aqueous solution (trade name: Brite ADPA-60A, manufactured by Rhodia) was added. After cooling, normal polymer was removed by removing normal heptane.
The crosslinked polymer (A-2) was dried with an 80 ° C. vacuum dryer (20 kPa) for 14 hours to obtain a dried crosslinked polymer (A-2). The average particle size was 397 μm.
(2) Production of water-absorbing polymer particles (8) 0.15 g of amino-modified silicone (KF-8010) used in Example 2 was added to 15 g of the crosslinked polymer (A-2) obtained in (1) before drying. A solution diluted with normal heptane to 1.5 g was sprayed, mixed well at room temperature, and dried in a vacuum dryer at 80 ° C. for 14 hours. Thereafter, 0.075 g of fumed silica (Aerosil 200) used in Example 1 was added and mixed well at room temperature to obtain water-absorbing polymer particles (8). Table 2 shows the measurement results of the centrifugal retention amount, the water absorption time by the vortex method, and the flow rate under pressure of the water absorbent polymer particles (8).

Example 7
To 15 g of the crosslinked polymer (A-2) obtained in Example 6 (1) before drying, amino-modified silicone (trade name: KF-880, manufactured by Shin-Etsu Silicone Co., Ltd., functional group equivalent: 1800 g / mol, viscosity: 650 mm ² / S, number average molecular weight 20,000) 0.03 g diluted with normal heptane to 1.5 g was sprayed, mixed well at room temperature, and dried in a vacuum dryer at 80 ° C. for 14 hours. Thereafter, 0.075 g of fumed silica (Aerosil 200) used in Example 1 was added and mixed well at room temperature to obtain water-absorbing polymer particles (9). The results are shown in Table 2.
Example 8
Water-absorbing polymer particles (10) were obtained in the same manner as in Example 7 except that the amount of amino-modified silicone (KF-880) was changed to 0.15 g. The results are shown in Table 2.
Example 9
Water-absorbing polymer particles (11) were obtained in the same manner as in Example 7 except that the amount of amino-modified silicone (KF-880) was changed to 0.24 g. The results are shown in Table 2.

Comparative Example 4
The centrifugal retention amount of the dried crosslinked polymer (A-2) obtained in Example 6 (1), the water absorption time by the vortex method, and the liquid passing rate under pressure were measured in the same manner as in Example 1. The results are shown in Table 2.
Comparative Example 5
Except that the amino-modified silicone was changed to KF-8012 (manufactured by Shin-Etsu Silicone Co., Ltd., functional group equivalent 2200 g / mol, viscosity 90 mm ² / s, number average molecular weight 4400), water-absorbing polymer particles were obtained in the same manner as in Example 6. (12) was obtained. The results are shown in Table 2.
Comparative Example 6
The same procedure as in Example 6 was followed, except that the amino-modified silicone was changed to a polyether-modified silicone (trade name: KF-6017, manufactured by Shin-Etsu Silicone Co., Ltd., viscosity 530 mm ² / s, number average molecular weight 15,000). Polymer particles (13) were obtained. The results are shown in Table 2.

  From Table 1 and Table 2, the water-absorbing polymer particles of the examples were compared with the water-absorbing polymer particles of the comparative example not containing amino-modified silicone (B) and / or inorganic fine particles (C), and the centrifugal retention amount and vortex water absorption time. Is equivalent, but it is found that the solution is remarkably superior in terms of the flow rate under pressure.

  In the sanitary product field, the water-absorbent polymer particles and absorbent articles of the present invention are disposable diapers for infants, adults or incontinents, sweat-absorbing sheets, sanitary napkins for women, panty liners, breast pads, pet sheets, It can be used as a water-absorbing substance in absorbent articles such as food drip absorbent sheets such as meat and fish.

a: Filtration cylindrical tube of measuring device for measuring the flow rate of superabsorbent polymer under pressure b: Weight bar 1: Cylinder Wire mesh Cock 4. 4. Tubular with cock Wire mesh Cylindrical bar 7. Weight W: Saline P: Superabsorbent polymer 10: Measuring device for water absorption rate of superabsorbent polymer 11: Polymer spray table 12: Burette

Claims (12)

  Water-absorbing polymer particles comprising a crosslinked polymer (A) having an anionic group, an amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less, and water-insoluble inorganic fine particles (C).   The cross-linked polymer (A) having an anionic group is obtained by bringing an amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less into contact with water-insoluble inorganic fine particles (C). Water-absorbing polymer particles as described in 1.   The water-absorbing polymer particles according to claim 1 or 2, wherein the anionic group is a carboxy group and / or a salt thereof.   The water-absorbent polymer particle according to any one of claims 1 to 3, wherein the crosslinked polymer (A) having an anionic group contains a structural unit derived from acrylic acid and a salt thereof.   The water-absorbing polymer particles according to any one of claims 1 to 4, wherein the water-insoluble inorganic fine particles (C) are silica fine particles.   The water-absorbing polymer particles according to claim 5, wherein the silica fine particles are amorphous.   The water-absorbing polymer particles according to any one of claims 1 to 6, wherein the content of the amino-modified silicone (B) is 0.01 to 5% based on the dry mass of the crosslinked polymer (A) having an anionic group. .   The water-absorbing polymer according to any one of claims 1 to 7, wherein the content of the water-insoluble inorganic fine particles (C) is 0.01 to 5% based on the dry mass of the crosslinked polymer (A) having an anionic group. particle.   The water-absorbing polymer particles according to any one of claims 1 to 8, wherein the amino-modified silicone (B) has a number average molecular weight of 100 to 100,000.   The water-absorbing polymer particles according to any one of claims 1 to 9, wherein the water-insoluble inorganic fine particles (C) have an average primary particle size of 3 to 30 nm.   An absorbent article comprising the water-absorbent polymer particles according to claim 1 as a constituent member. An amino-modified silicone (B) having a functional group equivalent of 2000 g / mol or less and water-insoluble inorganic fine particles (C) are brought into contact with the crosslinked polymer (A) particles having an anionic group, which are water-absorbing polymer particles, under the following conditions. A method for improving the flow rate of water-absorbing polymer particles under pressure.
(Flow rate under pressure)
Physiological saline when physiological saline containing swollen water-absorbing polymer particles is put in a filtration cylindrical tube having an inner diameter of 25.4 mm and a weight is placed on the water-absorbing polymer particles so that a load of 2.0 kPa is applied. This is a liquid passing speed (mL / min) when 20 mL of water passes through the filtration cylindrical tube, and is represented by the following formula (1).
Flow rate (mL / min) = 20 × 60 / (T ₁ −T ₀ ) (1)
(In the formula, T ₁ (second) indicates the time required for 20 mL of physiological saline to pass with the water-absorbing polymer particles in the filtration cylindrical tube, and T ₀ (second) indicates the time required for the filtration cylindrical tube. Indicates the time required for 20 mL of physiological saline to pass without water-absorbing polymer particles.)

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