JP2018131545A - Method for producing water absorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a water absorbent that allows 1-hydroxy-2-pyridone derivatives to be uniformly distributed near the surface of a water-absorbing resin, without impairing the powder flowability of the water-absorbing resin, and allows the functions of the 1-hydroxy-2-pyridone derivatives to be fully exhibited.SOLUTION: An addition liquid containing a polyhydric alcohol, water and a 1-hydroxy-2-pyridone derivative (In a solvent or dispersion medium of the addition liquid the polyhydric alcohol is 30 wt.% or more and 55 wt.% or less in concentrations), is added to a water-absorbing resin.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a water-absorbing agent.

  For hygiene materials such as paper diapers, sanitary napkins and so-called incontinence pads, water-absorbing agents comprising hydrophilic fibers such as pulp and water-absorbing resin are widely used for the purpose of absorbing body fluids. Yes.

  In recent years, these sanitary materials have been highly functionalized, and for example, by adding antibacterial agents such as 1-hydroxy-2-pyridone derivatives, highly functional absorbents have been developed.

  Patent Document 1 discloses an antibacterial hydrogel-forming absorbent polymer containing an antibacterial agent containing a 1-hydroxy-2-pyridone derivative. This document describes a method for producing absorbent polymer particles dissolved in a methyl alcohol solvent and coated with a 1-hydroxy-2-pyridone derivative.

  Patent Document 2 discloses a method for producing a superabsorbent having a coating of an antibacterial agent by bringing the antibacterial agent into contact with the superabsorbent in a state of being dissolved in a polyol.

  Patent Document 3 discloses an absorption process comprising applying an antibacterial agent solution obtained by dissolving an organic hydrophobic antibacterial agent in a hydrophilic and non-volatile organic solvent to a water-absorbing resin that is a raw material of an absorbent article material. A method for producing a material for a functional article is disclosed.

Special Table 2000-513408 Special table 2010-540004 gazette International Publication No. 2016/117523

  As described above, various methods for adding an antibacterial agent to a water-absorbent resin are known, but there is room for improvement particularly when a 1-hydroxy-2-pyridone derivative is blended in a water-absorbent resin.

  The present invention has been made in view of such circumstances, and the 1-hydroxy-2-pyridone derivative is more uniformly formed in the vicinity of the surface of the water absorbent resin without impairing the powder flowability of the water absorbent resin. It aims at providing the manufacturing method of the water absorbing agent which can be distributed so that it may approach and can fully exhibit the function which the said 1-hydroxy-2- pyridone derivative has.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, and as a result, have completed the following present invention.

  The method for producing a water-absorbing agent according to the present invention includes a step of adding an additive liquid in which a 1-hydroxy-2-pyridone derivative represented by the following general formula (I) is dissolved or dispersed to a water-absorbing resin, The additive liquid contains a polyhydric alcohol and water, and the concentration of the polyhydric alcohol in the solvent or dispersion medium of the additive liquid is 30 wt% or more and 55 wt% or less.

In the formula, R ₁ represents an alkyl group having 1 to 17 carbon atoms; an alkenyl group having 2 to 17 carbon atoms; a cycloalkyl group having 5 to 8 carbon atoms; a bicycloalkyl group having 7 to 9 carbon atoms; Is a cycloalkylalkyl group having an alkyl group of 1 to 4 (the cycloalkyl residue of the cycloalkylalkyl group may be substituted with an alkyl group of 1 to 4 carbon atoms); an aryl group (the aryl group May be substituted with an alkyl group having 1 to 4 carbon atoms); an aralkyl group having an alkyl group having 1 to 4 carbon atoms (the aryl residue in the aralkyl group has 1 to 4 carbon atoms). An arylalkenyl group having an alkenyl group having 2 to 4 carbon atoms (the aryl residue in the arylalkenyl group is substituted with an alkyl group having 1 to 4 carbon atoms) The An aryloxyalkyl group or arylmercaptoalkyl group having an alkyl group having 1 to 4 carbon atoms (the aryl residue in the aryloxyalkyl group or arylmercaptoalkyl group has 1 to 4 carbon atoms) A benzhydryl group (the aryl residue in the benzhydryl group may be substituted with an alkyl group having 1 to 4 carbon atoms); an alkyl having 1 to 4 carbon atoms; A phenylsulfonylalkyl group having a group (the aryl residue in the phenylsulfonylalkyl group may be substituted with an alkyl group having 1 to 4 carbon atoms); a furyl group or an alkenyl group having 2 to 4 carbon atoms; (Furyl residue in the furylalkenyl group is substituted with an alkyl group having 1 to 4 carbon atoms. It may be); alkoxy group having from 1 to 4 carbons; a nitro group; represents a halogen atom; a cyano group. R ₂ represents a hydrogen atom; an alkyl group having 1 to 4 carbon atoms; an alkenyl group having 2 to 4 carbon atoms; a halogen atom; a phenyl group; or a benzyl group. X ⁺ represents an organic base; an alkali metal ion; an ammonium ion; an alkaline earth metal ion; or a divalent to tetravalent cation ion.

  In the method for producing a water absorbing agent according to the present invention, the temperature of the additive liquid in the addition step is preferably 30 ° C. or higher and 90 ° C. or lower. Moreover, it is preferable that the temperature of the water-absorbing resin to be added is 20 ° C. or higher and 90 ° C. or lower.

  In the method for producing a water-absorbing agent according to the present invention, the concentration of the 1-hydroxy-2-pyridone derivative in the additive solution is preferably 1% by weight or more and 20% by weight or less.

  In the method for producing a water absorbent according to the present invention, the amount of the additive liquid added to the water absorbent resin in the addition step is 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the water absorbent resin. Preferably there is.

  In the method for producing a water-absorbing agent according to the present invention, the 1-hydroxy-2-pyridone derivative is preferably piroctone olamine.

  In the method for producing a water-absorbing agent according to the present invention, the polyhydric alcohol is ethylene glycol (1,2-ethanediol), propylene glycol (1,2-propanediol), 1,3-propanediol, 1,2- It is preferably at least one selected from the group consisting of butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol and glycerin (1,2,3-propanetriol). .

  According to the present invention, the 1-hydroxy-2-pyridone derivative is distributed in the vicinity of the surface of the water absorbent resin so as to approach the surface more uniformly without impairing the powder fluidity of the water absorbent resin. It is possible to provide a method for producing a water-absorbing agent that can sufficiently exhibit the function of a 2-pyridone derivative.

[1] Definition of terms (1-1) Water-absorbing agent In this specification, “water-absorbing agent” means a water-absorbing resin as a main component (preferably 60% by weight or more of the whole, more preferably 80% by weight or more, further In addition, water, inorganic fine particles, cationic polymer compound, water-soluble polyvalent metal cation-containing compound, surfactant, anti-coloring Agent, urine resistance improver, deodorant, fragrance, antibacterial agent, foaming agent, pigment, dye, fertilizer, oxidizing agent, reducing agent, etc., each of 0 wt% to 10 wt%, preferably 0.001 wt% % Or more and 5% by weight or less.

  The powder fluidity index of the water-absorbing agent is not particularly limited, but is preferably 75 or more, more preferably 80 or more, more preferably higher than 81, and more preferably 82 or more. 85 or more, more preferably 87 or more, and most preferably 90 or more. The upper limit value of the powder fluidity index is not particularly limited, and may be, for example, 100, 99, 98, 97, 96, or 95.

The powder flowability index was determined by measuring the repose angle index, spatula angle index, compressibility index, and uniformity index (or agglomeration index) of a water-absorbing agent using a powder tester PT-X manufactured by Hosokawa Micron Corporation. . It can be calculated from the powder flow index formula (Formula A below) proposed by Carr:
Powder flowability index = repose angle index + spatula angle index + compression degree index + (uniformity index or cohesion index) (formula A).

(1-2) “Water Absorbent Resin”
The water-absorbing resin in the present specification means a water-swellable water-insoluble polymer gelling agent. “Water swellability” means that the CRC (absorption capacity under no pressure) specified by ERT441.2-02 is 5 g / g or more, and “water insolubility” means ERT470.2- Extr (water-soluble component) specified by 02 is 0% by weight or more and 50% by weight or less.

(1-3) “EDANA” and “ERT”
“EDANA” is an abbreviation for European Disposables and Nonwovens Associations, and “ERT” is an abbreviation for a method of measuring water-absorbent resin of the European standard (almost the world standard) (EDANA Recommended Test Methods). . In the present invention, unless otherwise specified, the physical properties of the water-absorbent resin are measured according to the original ERT (revised in 2002 / known literature).

(1-3-1) “CRC” (ERT441.2-02)
“CRC” is an abbreviation for Centrifugation Retention Capacity (centrifugal retention capacity), and means the water absorption capacity of the water absorbent resin under no pressure (sometimes referred to as “water absorption capacity”).

  Specifically, 0.2 g of the water-absorbing resin was put in a non-woven bag, and then immersed in a large excess of 0.9 wt% sodium chloride aqueous solution for 30 minutes to freely swell, and then centrifuged (250 G ) Is the water absorption rate (unit: g / g) after draining.

(1-3-2) “AAP” (ERT442.2-02)
“AAP” is an abbreviation for Absorption Against Pressure, which means the water absorption capacity of a water absorbent resin under pressure.

Specifically, after swelling 0.9 g of water-absorbing resin with a large excess of 0.9 wt% sodium chloride aqueous solution for 1 hour under a load of 2.06 kPa (21 g / cm ² , 0.3 psi) Of water absorption (unit: g / g). In some cases, the load condition is changed to 4.83 kPa (49 g / cm ² , 0.7 psi).

  In addition, ERT442.2-02 describes “Absorption Under Pressure”, which has substantially the same content.

(1-3-3) "PSD" (ERT420.2-02)
“PSD” is an abbreviation for Particle Size Distribution, and means a particle size distribution of a water-absorbent resin measured by sieving classification.

  The weight average particle diameter (D50) and the logarithmic standard deviation (σζ) of the particle size distribution are described in US Pat. No. 7,638,570 “(3) Mass-Average Particle Diameter (D50) and Logical Standard Deviation (σζ) of”. It measures by the method similar to "Particle Diameter Distribution."

[2] Manufacturing method of water-absorbing agent The manufacturing method of the water-absorbing agent according to the present invention includes an adding step of adding an additive solution in which a 1-hydroxy-2-pyridone derivative is dissolved or dispersed to a water-absorbing resin.

(2-1) Addition step This step is a step of adding an additive solution in which the 1-hydroxy-2-pyridone derivative is dissolved or dispersed to the water absorbent resin.

(Additive solution)
The additive liquid is a liquid in which a 1-hydroxy-2-pyridone derivative is dissolved or dispersed, and is a liquid for adding to a water absorbent resin.

  The additive solution contains a 1-hydroxy-2-pyridone derivative as a solute or a dispersoid.

  The additive liquid uses a mixture of water and a polyhydric alcohol as a solvent or a dispersion medium. When a mixture of water and a polyhydric alcohol is used as a solvent or dispersion medium, the 1-hydroxy-2-pyridone derivative is easily distributed in the vicinity of the surface of the water-absorbent resin so as to approach more uniformly.

  The temperature of the additive liquid depends on conditions such as the type of polyhydric alcohol and the concentration of the polyhydric alcohol, but is preferably 20 ° C. or higher and 100 ° C. or lower. In the range of the preferable polyhydric alcohol concentration described later, the temperature of the additive solution is preferably 30 ° C. or higher and 90 ° C. or lower, and more preferably 40 ° C. or higher and 80 ° C. or lower. When the temperature of the additive liquid is 30 ° C. or higher, the 1-hydroxy-2-pyridone derivative can be sufficiently dissolved or dispersed without precipitating. On the other hand, when the temperature of the additive solution is 90 ° C. or lower, thermal degradation of the 1-hydroxy-2-pyridone derivative can be suppressed. Moreover, it is preferable that the temperature of the water-absorbing resin to be added is 20 ° C. or higher and 90 ° C. or lower.

  The pH of the additive solution is preferably 6 or more, more preferably 7 or more, and still more preferably 8 or more. When the pH is 6 or more, the solubility of the 1-hydroxy-2-pyridone derivative can be improved, and alteration of the water absorbent resin can be suppressed.

  The viscosity of the additive liquid is preferably 1 mPa · s or more and 20 mPa · s or less, more preferably 1 mPa · s or more and 15 mPa · s or less, and further preferably 1 mPa · s or more and 10 mPa · s or less. When the viscosity is in the above-described preferable range, it is easy to uniformly disperse the additive liquid with respect to the water absorbent resin.

  Further, the amount of the additive liquid added to the water absorbent resin is preferably 0.01 parts by weight or more and 20 parts by weight or less, more preferably 0.05 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the water absorbent resin. More preferred is 0.1 to 5 parts by weight. When the amount to be added is in the above-described preferable range, sufficient water absorption performance of the water absorbent resin can be obtained.

(Mixture of water and polyhydric alcohol)
As the solvent or dispersion medium of the additive liquid, a mixture of water and a polyhydric alcohol is used. The concentration of the polyhydric alcohol is preferably 30% by weight to 55% by weight in the solvent or dispersion medium of the additive solution (that is, when the total amount of water and the polyhydric alcohol is 100% by weight), and 30% by weight. % To 50% by weight is more preferred, 30% to 45% by weight is more preferred, and 30% to 40% by weight is most preferred.

  On the other hand, the concentration of water is preferably more than 45% by weight and less than 70% by weight in the solvent or dispersion medium of the additive liquid (that is, when the total amount of water and polyhydric alcohol is 100% by weight). More than 50% by weight and less than 70% by weight are preferred, more than 65% by weight and less than 70% by weight are more preferred, more preferably more than 60% by weight and less than 70% by weight.

  Since the 1-hydroxy-2-pyridone derivative is hardly soluble in water, when only water is used as the solvent (dispersion medium) of the additive solution, the additive solution becomes a suspension. Even if the suspension is added to the water absorbent resin, only water in the suspension may penetrate into the water absorbent resin and the 1-hydroxy-2-pyridone derivative may be detached from the surface of the water absorbent resin. There is. On the other hand, the polyhydric alcohol dissolves the 1-hydroxy 2-pyridone derivative. However, when only the polyhydric alcohol is used as the solvent (dispersion medium) of the additive solution, the additive solution cannot penetrate into the water absorbent resin. On the other hand, as described above, when the amount of the polyhydric alcohol is 30% by weight or more and 55% by weight or less, the 1-hydroxy-2-pyridone derivative is dissolved or dispersed in the additive liquid, and the water-absorbing resin. It is possible to achieve both a uniform distribution in the vicinity of the surface.

(Polyhydric alcohol)
Examples of the polyhydric alcohol include ethylene glycol (1,2-ethanediol), diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, Dipropylene glycol, 2,2,4-trimethyl-1,3-pentadiol, polypropylene glycol, 2-butene-1,4-diol, 1,2-butylene glycol (1,2-butanediol), 1,3 -Butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol and glycerin (1,2,3-propanetriol), and selected from these Any polyhydric alcohol mixture It is. By using the polyhydric alcohol, the 1-hydroxy-2-pyridone derivative is more easily dissolved in a mixture of water and the polyhydric alcohol.

  Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, and glycerin. Etc. are preferred, propylene glycol, 1,3-propanediol and 1,3-butanediol are more preferred, and propylene glycol is more preferred. By using propylene glycol as the polyhydric alcohol, the 1-hydroxy-2-pyridone derivative is easily dissolved in a mixture of water and the polyhydric alcohol. In addition, a polyhydric alcohol may use together 1 type, or 2 or more types.

  The boiling point of the polyhydric alcohol is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. By being 100 degreeC or more, it is hard to volatilize during manufacture of a water absorbing agent.

(1-hydroxy-2-pyridone derivative)
The 1-hydroxy-2-pyridone derivative is dispersed or dissolved in the additive solution.

  The 1-hydroxy-2-pyridone derivative is represented by the following general formula (I).

[Wherein, R ₁ represents an alkyl group having 1 to 17 carbon atoms; an alkenyl group having 2 to 17 carbon atoms; a cycloalkyl group having 5 to 8 carbon atoms; a bicycloalkyl group having 7 to 9 carbon atoms; A cycloalkylalkyl group having an alkyl group of 1 to 4 (the cycloalkyl residue of the cycloalkylalkyl group may be substituted with an alkyl group of 1 to 4 carbon atoms); an aryl group (the aryl The group may be substituted with an alkyl group having 1 to 4 carbon atoms); an aralkyl group having an alkyl group having 1 to 4 carbon atoms (the aryl residue in the aralkyl group has 1 to 1 carbon atoms); An arylalkenyl group having an alkenyl group having 2 to 4 carbon atoms (the aryl residue in the arylalkenyl group is substituted with an alkyl group having 1 to 4 carbon atoms) Is Aryloxyalkyl group or arylmercaptoalkyl group having an alkyl group having 1 to 4 carbon atoms (the aryl residue in the aryloxyalkyl group or arylmercaptoalkyl group has 1 to 4 carbon atoms) A benzhydryl group (the aryl residue in the benzhydryl group may be substituted with an alkyl group having 1 to 4 carbon atoms); A phenylsulfonylalkyl group having an alkyl group (the aryl residue in the phenylsulfonylalkyl group may be substituted with an alkyl group having 1 to 4 carbon atoms); a furyl group or alkenyl having 2 to 4 carbon atoms; (Furyl residue in the furylalkenyl group is substituted with an alkyl group having 1 to 4 carbon atoms) Which may also be); a carbon number of 1 to 4 alkoxy groups; represents a halogen atom; a nitro group; a cyano group. R ₂ represents a hydrogen atom; an alkyl group having 1 to 4 carbon atoms; an alkenyl group having 2 to 4 carbon atoms; a halogen atom; a phenyl group; or a benzyl group. X ⁺ represents an organic base; an alkali metal ion; an ammonium ion; an alkaline earth metal ion; or a divalent to tetravalent cation ion].

  The molecular weight of the 1-hydroxy-2-pyridone derivative is preferably 50 or more and 800 or less, more preferably 50 or more and 600 or less, and even more preferably 50 or more and 400 or less because the preparation of the additive solution is easy. Examples of such 1-hydroxy-2-pyridone derivatives include piroctone olamine (1-hydroxy-4-methyl-6- (2,4,4-trimethylpentyl) -2 (1H) -pyridone-2. -Aminoethanol; sold in Japan by Clariant Japan Co., Ltd. under the trade name "Octopirox".

  In addition, piroctone olamine is preferable from the viewpoint of satisfying certain safety standards because it is listed in the cosmetics standards stipulated in the Pharmaceuticals and Medical Devices Act.

  The amount of the 1-hydroxy-2-pyridone derivative contained in the additive solution is 1 when the total amount of the 1-hydroxy-2-pyridone derivative, water, polyhydric alcohol and other optional components is 100% by weight. It is preferably from 20% by weight to 20% by weight, more preferably from 5% by weight to 20% by weight, and even more preferably from 5% by weight to 15% by weight.

(Other optional ingredients)
The additive solution may contain other optional components in addition to water, polyhydric alcohol and 1-hydroxy-2-pyridone derivative. Specific examples of other optional components include deodorants, metal soaps, antibacterial agents, anti-coloring agents, urine resistance improvers, oxidizing agents and reducing agents.

  Specific examples of metal soaps include calcium laurate, magnesium laurate, zinc laurate, aluminum laurate, calcium myristate, magnesium myristate, zinc myristate, aluminum myristate, calcium palmitate, magnesium palmitate, palmitate Examples include, but are not limited to, zinc acid, aluminum palmitate, calcium stearate, magnesium stearate, zinc stearate and aluminum stearate, and any organic acid and metal salt can be combined. . Moreover, this metal soap may use together 1 type, or 2 or more types.

  Further, as coloring inhibitors and urine resistance improvers, chelating agents (especially organic phosphorus chelating agents and aminocarboxylic acid chelating agents), α-hydroxycarboxylic acid derivatives, and inorganic or organic reducing agents (especially sulfur inorganics). It is preferable to contain a coloring inhibitor or urine resistance improver selected from (reducing agents). A water-absorbing resin having a large surface area generally tends to be colored and deteriorated.

  Examples of the chelating agent include chelating agents disclosed in US Pat. Nos. 6,599,989, 6,469,080, and European Patent 2,163,302, such as non-polymer chelating agents, organophosphorus chelating agents, and aminocarboxylic acid chelating agents. Can be mentioned. Examples of the α-hydroxycarboxylic acid derivative include malate, oxalate and lactate disclosed in US Patent Application Publication No. 2009/0312183. Examples of the inorganic or organic reducing agent include sulfur-based reducing agents disclosed in US Patent Application Publication No. 2010/0062252 and the like, for example, sulfites and bisulfites.

  The amount of the coloring inhibitor or urine resistance improver used is preferably 0 part by weight or more and 3 parts by weight or less, more preferably 0.001 part by weight or more and 1 part by weight or less, based on 100 parts by weight of the water absorbent resin. The amount is more preferably from 0.5 parts by weight to 0.5 parts by weight.

  The amount of other optional components contained in the additive is 0.001% by weight when the total amount of the 1-hydroxy-2-pyridone derivative, water, polyhydric alcohol and other optional components is 100% by weight. The content is preferably 5% by weight or less and more preferably 0.005% by weight or more and 2% by weight or less. By being in the above-mentioned preferable range, the effect of the optional component can be exhibited without substantially impairing the water absorption performance of the water absorbent resin.

(Water absorbent resin)
Examples of the water-absorbing resin include polyacrylic acid (salt) -based crosslinked polymers, hydrolysates of starch-acrylonitrile graft polymers, starch-acrylic acid graft polymers, and saponified products of vinyl acetate-acrylic ester copolymers. , An acrylonitrile copolymer or an acrylamide copolymer hydrolyzate or a crosslinked product thereof, a carboxyl group-containing crosslinked polyvinyl alcohol modified product, a crosslinked isobutylene-maleic anhydride copolymer, and the like. You may use, and it can also use 2 or more types together. Among these, a polyacrylic acid (salt) -based crosslinked polymer having the highest versatility is preferable.

  The neutralization rate of the water absorbent resin is preferably 30 mol% or more and 90 mol% or less, and more preferably 40 mol% or more and 80 mol% or less. By being in the above-mentioned preferable range, it becomes a water-absorbent resin excellent in absorption performance.

  The water-absorbing resin may be a surface-crosslinked water-absorbing resin, or may be a water-absorbing resin that has not been surface-crosslinked, and has been surface-crosslinked from the viewpoint of enhancing the absorption performance under pressure. A water absorbent resin is preferred. Furthermore, as a general range of the water absorbent resin, CRC is 20 g / g or more and 50 g / g or less, AAP 2.06 kPa is 10 g / g or more and 40 g / g or less, and weight average particle diameter is 200 μm or more and 600 μm or less. The amount of 150 μm or less is preferably 10% by weight or less.

(Addition method)
Examples of the method of adding the additive liquid to the water absorbent resin include (1) a method of mixing the additive liquid and the water absorbent resin under stirring, (2) a method of immersing the water absorbent resin in the additive liquid, and ( 3) A method of dropping or spraying the additive liquid onto a water-absorbent resin in a fluidized state or a stirred state. From the viewpoint that the additive solution can be uniformly distributed in the vicinity of the surface of the water absorbent resin, the methods (1) and (3) are preferable. As a mixing apparatus used in (1), in order to mix a water absorbing resin and an additive liquid uniformly, what is equipped with big mixing power is preferable. Examples of such a mixing apparatus include a cylindrical mixer, a double wall conical mixer, a high-speed stirring mixer, a V-shaped mixer, a ribbon mixer, a screw mixer, a double-arm kneader, Pulverization type kneaders, rotary mixers, airflow type mixers, turbulizers, batch-type Redige mixers, continuous-type Redige mixers, and the like are preferably used.

  The temperature of the water-absorbent resin before adding the additive liquid is preferably room temperature (23 ° C.) or higher and 100 ° C. or lower, preferably 30 ° C. or higher and 90 ° C. or lower, more preferably 40 ° C. or higher and 80 ° C. or lower. When the temperature of the water absorbent resin is 100 ° C. or lower, it is possible to suppress the 1-hydroxy-2-pyridone derivative from being thermally decomposed. Therefore, a production method that does not include a step in which the temperature of the water absorbent resin exceeds 100 ° C. after adding the additive liquid to the water absorbent resin is preferable. On the other hand, when the temperature of the water-absorbent resin is room temperature or higher, productivity is improved because a long time is not required for the diffusion of the additive solution.

(Process after addition of additive liquid)
In addition, the manufacturing method of the water absorbing agent which concerns on this invention may further have the drying process etc. which dry or heat the water absorbing resin after adding an addition liquid. By heating, penetration of the solvent or dispersion medium in the additive liquid into the water-absorbent resin is promoted, and the surface can be dried and rapidly formed into particles. The heating temperature is preferably 30 ° C. or higher and 150 ° C. or lower, preferably 40 ° C. or higher and 120 ° C. or lower, and more preferably 50 ° C. or higher and 100 ° C. or lower. The time is also preferably 1 second or longer and 3 hours or shorter, and more preferably 1 minute or longer and 1 hour or shorter.

  Moreover, the manufacturing method of the water absorbing agent which concerns on this invention may have the crushing process which further crushes, classifies, or granulates the water absorbing agent which became particulate by being heated.

(Other additive addition process)
The method for producing a water absorbent according to the present invention may include a step of adding other additives in order to give various functions to the water absorbent resin after surface crosslinking. Additives include inorganic fine particles, deodorants, metal soaps, antibacterial agents, anti-coloring agents, urine resistance improvers, oxidizing agents, reducing agents, surfactants, fragrances, foaming agents, pigments, dyes, fertilizers, etc. It may contain an additive and impart or enhance a function.

  Unless otherwise specified, the amount of the additive is less than 10% by weight, preferably less than 5% by weight, more preferably less than 1% by weight with respect to 100% by weight of the water-absorbent resin after surface crosslinking. Moreover, you may perform these additive addition processes simultaneously with the addition process of the addition liquid containing a 1-hydroxy-2- pyridone derivative, or another process.

(Preparation of precursor water-absorbing resin)
As a water-absorbing resin (A) to which an additive liquid containing a 1-hydroxy-2-pyridone derivative is added, “Aquaric” is a polyacrylic acid (partially neutralized salt) -based crosslinked polymer manufactured by Nippon Shokubai Co. CA "was used. The water absorbent resin (A) had a CRC of 35 g / g, an AAP of 2.06 kPa of 32 g / g, and a weight average particle size of 370 μm.

[Example 1]
In a solvent obtained by mixing 4.95 g of propylene glycol and 4.05 g of water, 1.0 g of piroctone olamine (“Octopirox” manufactured by Clariant) as a 1-hydroxy-2-pyridone derivative (concentration in the additive solution) Was dissolved at 50 ° C. to prepare an additive solution. Next, 1 part by weight of the additive solution was added dropwise with stirring to 100 parts by weight of the water absorbent resin (A), and the water absorbent resin (A) and the additive solution were mixed. After mixing, the mixture was dried at 60 ° C. for 1 hour. The obtained dried product was pulverized until it passed through a JIS standard sieve having an opening of 850 μm to obtain a water absorbing agent.

Next, the powder fluidity of the water absorbing agent was evaluated. The evaluation of the powder fluidity is to measure the repose angle index, spatula angle index, compressibility index, and uniformity index (or cohesion index) of the water-absorbing agent using a powder tester PT-X manufactured by Hosokawa Micron Corporation, DR. The calculation was carried out by calculating from the powder flowability index formula (the following formula A) proposed by Carr.
Powder flowability index = angle of repose index + spatula angle index + compressibility index + (uniformity index or cohesion index) (formula A)
The measurement was performed under ambient conditions of room temperature (23 ° C.) and humidity of 40%. The relationship between the powder fluidity index and the powder fluidity evaluation is as follows.
Powder fluidity index: Evaluation of powder fluidity 80 or more: Very good powder fluidity 70-79: Good powder fluidity 60-69: Slightly poor powder fluidity 59 or less: Powder fluidity Sex is bad.

  Table 1 shows the evaluation of powder flowability of the water-absorbing agent.

[Example 2]
In a solvent in which 4.68 g of 1,3-propanediol and 3.82 g of water are mixed, 1.5 g of piroctone olamine (concentration in the additive solution is 15% by weight) is dissolved at 50 ° C. to prepare an additive solution. did. Next, 1 part by weight of the additive solution was added with stirring to 100 parts by weight of the water absorbent resin (A) obtained in Production Example 1, and the water absorbent resin (A) and the additive solution were mixed. After mixing, a water absorbing agent was produced in the same manner as in Example 1. The powder fluidity of the water absorbing agent was evaluated and shown in Table 1.

[Example 3]
In Example 1, the same operation was performed except that the amount of propylene glycol was changed to 4.50 g, the amount of water was changed to 4.50 g, and the dissolution temperature of piroctone olamine was changed to 60 ° C. The powder fluidity of the agent was evaluated and shown in Table 1.

[Example 4]
In Example 1, the same operation was performed except that the amount of propylene glycol was changed to 3.60 g, the amount of water was changed to 5.40 g, and the dissolution temperature of piroctone olamine was changed to 60 ° C. The powder fluidity of the agent was evaluated and shown in Table 1.

[Example 5]
In Example 4, the same operation was performed except that the polyhydric alcohol was changed to 1,3-butanediol, and the powder fluidity of the obtained water-absorbing agent was evaluated.

[Example 6]
In Example 1, the same operation was performed except that the amount of propylene glycol was changed to 2.70 g, the amount of water was changed to 6.30 g, and the dissolution temperature of piroctone olamine was changed to 80 ° C. The powder fluidity of the agent was evaluated and shown in Table 1.

[Example 7]
In a solvent in which 2.85 g of glycerin and 6.65 g of water were mixed, 0.50 g of piroctone olamine (concentration in the additive solution was 5% by weight) was dissolved at 80 ° C. to prepare an additive solution. Next, 1 part by weight of the additive solution was added with stirring to 100 parts by weight of the water absorbent resin (A) obtained in Production Example 1, and the water absorbent resin (A) and the additive solution were mixed. After mixing, a water absorbing agent was produced in the same manner as in Example 1. The powder fluidity of the water absorbing agent was evaluated and shown in Table 1.

[Example 8]
In Example 4, the same operation was performed except that the addition amount of the additive liquid was changed to 2 parts by weight with respect to 100 parts by weight of the water absorbent resin (A), and the powder fluidity of the obtained water absorbent was changed. The results are shown in Table 1.

[Example 9]
In Example 5, the same operation was performed except that the addition amount of the additive liquid was changed to 4 parts by weight with respect to 100 parts by weight of the water absorbent resin (A), and the powder fluidity of the obtained water absorbent was changed. The results are shown in Table 1.

[Example 10]
In Example 1, 0.4 parts by weight of silica (Reorosil manufactured by Tokuyama Co., Ltd.) as inorganic fine particles was added to and mixed with the obtained water-absorbing agent with respect to 100 parts by weight of the water-absorbing agent. The powder fluidity of the obtained silica-containing water-absorbing agent was evaluated and is shown in Table 1.

[Example 11]
In Example 7, 0.7 parts by weight of silica as inorganic fine particles was added to 100 parts by weight of the water-absorbing agent and mixed with the obtained water-absorbing agent. The powder fluidity of the obtained silica-containing water-absorbing agent was evaluated and is shown in Table 1.

[Comparative Example 1]
When 9.0 g of water was mixed with 1.0 g of piroctone olamine (concentration in the liquid was 10% by weight), it did not dissolve even at 80 ° C. and a uniform dispersion could not be prepared.

[Comparative Example 2]
When mixed with 1.25 g of 1,3-propanediol and 6.75 g of water, 1.0 g of piroctone olamine (concentration in the liquid is 10% by weight) was not dissolved even at 80 ° C. A uniform dispersion could not be prepared.

[Comparative Example 3]
In a solvent in which 5.40 g of propylene glycol and 3.60 g of water were mixed, 1.0 g of piroctone olamine (concentration in the additive solution was 10% by weight) was prepared to prepare an additive solution. Other conditions produced the water absorbing agent similarly to Example 1. The powder fluidity of each water absorbing agent was evaluated and shown in Table 1.

[Comparative Example 4]
A water-absorbing agent was produced in the same manner as in Comparative Example 3 except that the polyhydric alcohol was changed to glycerin. The powder fluidity of the obtained water-absorbing agent was evaluated and shown in Table 1.

[Comparative Example 5]
In 9.00 g of 1,3-butanediol, 0.10 g of piroctone olamine (concentration in the additive solution was 10% by weight) was dissolved at room temperature to prepare an additive solution. Other conditions produced the water absorbing agent similarly to Example 1. The powder fluidity of the obtained water-absorbing agent was evaluated and shown in Table 1.

[Comparative Example 6]
In Comparative Example 3, 0.7 parts by weight of silica (Reorosil manufactured by Tokuyama Corporation) as inorganic fine particles was added to 100 parts by weight of the water absorbent and mixed with the obtained water absorbent. The powder fluidity of the obtained silica-containing water-absorbing agent was evaluated and is shown in Table 1.
(Performance of water absorbent)
In Examples 1 to 9 and Comparative Examples 1 to 6, the CRC of the obtained water-absorbing agent was 34 g / g to 35 g / g, AAP 2.06 kPa was 29 g / g to 32 g / g, and the weight average particle diameter was 360 μm. It was 390 micrometers, and the property of the water absorbing resin (A) which is a precursor was substantially maintained.

  From Table 1, if the concentration of the polyhydric alcohol in the solvent or dispersion medium of the additive solution is within the range of the examples (30 wt% or more and 55 wt% or less), the water-absorbing agent obtained has good powder flowability. It was shown that. Conversely, when the concentration of polyhydric alcohol is below the above range (Comparative Examples 1 and 2), it is difficult to dissolve piroctone olamine, while when the concentration of polyhydric alcohol is above the above range (Comparative Example). 3, 4, 5), the powder fluidity decreases.

  The present invention is suitable for the production of water absorbents for sanitary materials such as paper diapers, sanitary napkins, and incontinence pads.

Claims (6)

An addition step of adding an additive solution in which a 1-hydroxy-2-pyridone derivative represented by the following general formula (I) is dissolved or dispersed to a water absorbent resin;
The additive solution contains a polyhydric alcohol and water,
The method for producing a water-absorbing agent, wherein the concentration of the polyhydric alcohol in the solvent or dispersion medium of the additive liquid is 30% by weight or more and 55% by weight or less.

[Where:
R ₁ is an alkyl group having 1 to 17 carbon atoms; an alkenyl group having 2 to 17 carbon atoms; a cycloalkyl group having 5 to 8 carbon atoms; a bicycloalkyl group having 7 to 9 carbon atoms; A cycloalkylalkyl group having 4 alkyl groups (the cycloalkyl residue of the cycloalkylalkyl group may be substituted with an alkyl group having 1 to 4 carbon atoms); an aryl group (the aryl group is carbon An aralkyl group having an alkyl group having 1 to 4 carbon atoms (the aryl residue in the aralkyl group is an alkyl group having 1 to 4 carbon atoms) An arylalkenyl group having an alkenyl group having 2 to 4 carbon atoms (the aryl residue in the arylalkenyl group may be substituted with an alkyl group having 1 to 4 carbon atoms) Good); an aryloxyalkyl group or arylmercaptoalkyl group having an alkyl group having 1 to 4 carbon atoms (the aryl residue in the aryloxyalkyl group or arylmercaptoalkyl group is an alkyl group having 1 to 4 carbon atoms) A benzhydryl group (the aryl residue in the benzhydryl group may be substituted with an alkyl group having 1 to 4 carbon atoms); an alkyl group having 1 to 4 carbon atoms; A phenylsulfonylalkyl group (the aryl residue in the phenylsulfonylalkyl group may be substituted with an alkyl group having 1 to 4 carbon atoms); a furyl group or an alkenyl group having 2 to 4 carbon atoms; A furyl alkenyl group (the furyl residue in the furyl alkenyl group is substituted with an alkyl group having 1 to 4 carbon atoms). May also be); carbon atoms 1 to 4 alkoxy groups; represents a halogen atom, a nitro group, a cyano group
R ₂ represents a hydrogen atom; an alkyl group having 1 to 4 carbon atoms; an alkenyl group having 2 to 4 carbon atoms; a halogen atom; a phenyl group; or a benzyl group,
X ⁺ represents an organic base; an alkali metal ion; an ammonium ion; an alkaline earth metal ion; or a divalent to tetravalent cation ion]   The temperature of the said addition liquid in the said addition process is 30 degreeC or more and 90 degrees C or less, The manufacturing method of the water absorbing agent of Claim 1 characterized by the above-mentioned.   The method for producing a water-absorbing agent according to claim 1 or 2, wherein the concentration of the 1-hydroxy-2-pyridone derivative in the additive solution is 1 wt% or more and 20 wt% or less.   The amount of the additive liquid added to the water absorbent resin in the addition step is 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the water absorbent resin. 4. The method for producing a water absorbing agent according to any one of 3 above.   The method for producing a water-absorbing agent according to any one of claims 1 to 4, wherein the 1-hydroxy-2-pyridone derivative is piroctone olamine.   The polyhydric alcohol is ethylene glycol (1,2-ethanediol), propylene glycol (1,2-propanediol), 1,3-propanediol, 1,2-butylene glycol (1,2-butanediol), It is at least one selected from the group consisting of 1,3-butanediol, 1,4-butanediol, 2,3-butanediol and glycerin (1,2,3-propanetriol), The manufacturing method of the water absorbing agent of any one of Claims 1-5.