Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
  • B01J20/26—Synthetic macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
  • C08L101/12—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
  • C08L101/14—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels

Definitions

• the present invention relates to a resin particle composition.
• the water-absorbent resin particles having the property of absorbing and retaining water which is an essential element in daily life, are sanitary materials such as paper diapers and sanitary products, agricultural and horticultural materials such as water retention agents and soil improvers, and stoppers. It is widely used in fields such as industrial materials such as water agents and anti-condensation agents. Since the water-absorbent resin particles are usually powders having no adhesive force, they are used as an absorber formed in a sandwich shape by spraying the water-absorbent resin particles on a fibrous base material such as a non-woven fabric in the above application. At this time, in order to fix the water-absorbent resin particles to the base material, a method of spraying the water-absorbent resin particles on the fibrous base material coated with the adhesive is performed (for example, Patent Document 1).
• An object of the present invention is to provide a resin particle composition that does not easily fall off from an absorber.
• the resin particle composition of the present invention has water-absorbent resin particles and a fixing member layer, and after the caking test performed in the order of (1) to (5) below, at least the particles are placed on a sieve having an opening of 850 ⁇ m. Some remain.
• a circular release paper having a diameter of 50 mm is laid on the bottom of a circular stainless steel petri dish having an inner diameter of 52 mm, and 2.0 g of a resin particle composition having a particle size of less than 850 ⁇ m is sprayed on the release paper.
• a measurement sample is obtained by stacking a circular release paper having a diameter of 50 mm, a circular stainless steel petri dish having an outer diameter of 50 mm and a mass of 20 g, and a cylindrical weight having a diameter of 45 mm, 780 g, on the sprayed resin particle composition in this order.
• the measurement sample is dried at 80 ° C. for 1 hour with a hot air dryer, and then allowed to cool to room temperature.
• the resin particle composition is removed from the release paper after cooling and recovered, and the entire amount of the recovered resin particle composition is placed on a sieve having an opening of 850 ⁇ m. (5) After shaking the above sieve with a low-tap type sieve shaker for 5 seconds, it is confirmed whether the resin particle composition remains on the sieve.
• the resin particle composition preferably has a caking index of 20% or more, which is measured by the caking test and is represented by the following formula.
• Caking index (%) [Mass of resin particle composition remaining on a sieve with an opening of 850 ⁇ m / (Resin particle composition remaining on a sieve with an opening of 850 ⁇ m and a resin particle composition passing through a sieve with an opening of 850 ⁇ m) Total mass)] x 100
• the fixing member layer may contain at least one selected from the group consisting of an ethylene-based polymer, a polyether-based polymer, a polyamide-based polymer, a polyurethane-based polymer, and a polyester-based polymer.
• the amount of the fixing member may be 0.01 to 10 parts by mass with respect to 100 parts by mass of the water-absorbent resin particles.
• the resin particle composition may have a physiological saline water retention amount of 30 g / g or more.
• the present invention provides a resin particle composition that does not easily fall off from the absorber.
• each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.
• Water-soluble means that it exhibits a solubility in water of 5% by mass or more at 25 ° C.
• Room temperature means 25 ⁇ 2 ° C.
• layer includes not only a structure having a shape formed on the entire surface but also a structure having a shape partially formed when observed as a plan view.
• the resin particle composition according to the present embodiment has water-absorbent resin particles and a fixing member layer.
• the resin particle composition has a caking property measured in the caking test performed in the order of (1) to (5) below. Having a caking property means that at least a part of the particles remains on the sieve having an opening of 850 ⁇ m used after the step (5) of the caking test below.
• a circular release paper having a diameter of 50 mm is laid on the bottom of a circular stainless steel petri dish having an inner diameter of 52 mm, and 2.0 g of a resin particle composition having a particle size of less than 850 ⁇ m is sprayed on the release paper.
• a measurement sample is obtained by stacking a circular release paper having a diameter of 50 mm, a circular stainless steel petri dish having an outer diameter of 50 mm and a mass of 20 g, and a cylindrical weight having a diameter of 45 mm, 780 g, on the sprayed resin particle composition in this order. As a result, the resin particle composition is pressurized at 4000 Pa.
• the measurement sample is dried at 80 ° C. for 1 hour with a hot air dryer, and then allowed to cool to room temperature.
• the resin particle composition is removed from the release paper after cooling and recovered, and the entire amount of the recovered resin particle composition is placed on a sieve having an opening of 850 ⁇ m. (5) After shaking the above sieve with a low-tap type sieve shaker for 5 seconds, it is confirmed whether the resin particle composition remains on the sieve.
• the resin particle composition according to the present embodiment has the caking property measured in the caking test, for example, when the absorber is produced, the resin particle composition and the fibrous base material are overlapped and heated under pressure. Therefore, it is possible to immobilize the resin particle composition on the fibrous base material without using a separate adhesive.
• the above caking test is a direct index of the binding property between the resin particle compositions, but the resin particle composition having such caking property is also bonded to the fibrous substrate by pressure heating. It is possible to wear it.
• the resin particle composition according to the present embodiment preferably has a caking index of 20% or more represented by the following formula.
• the caking index is measured by measuring the mass of the resin particle composition remaining on the sieve having an opening of 850 ⁇ m and the mass of the resin particle composition passing through the sieve having an opening of 850 ⁇ m after the step (5) of the caking test.
• Can be calculated by Caking index (%) [Mass of resin particle composition remaining on a sieve with an opening of 850 ⁇ m / (Resin particle composition remaining on a sieve with an opening of 850 ⁇ m and a resin particle composition passing through a sieve with an opening of 850 ⁇ m) Total mass)] x 100
• the caking index of the resin particle composition according to the present embodiment is 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, It may be 65% or more, 70% or more, 75% or more, 78% or more, 80% or more, 85% or more, 90% or more, or 95% or more.
• the caking index of the resin particle composition according to the present embodiment may be 100% or less, 99% or less, 98% or less, 97% or less, or 95% or less.
• the resin particle composition according to the present embodiment has water-absorbent resin particles and a fixing member layer.
• the resin particle composition according to the present embodiment may be provided with a fixing member layer on at least a part of the surface of the water-absorbent resin particles.
• the fixing member layer is preferably fixed to at least a part of the surface of the water-absorbent resin particles.
• the resin particle composition according to the present embodiment can maintain high water absorption performance originally possessed by the water-absorbent resin particles while having an immobilization ability on a fibrous base material used for an absorber or the like.
• the physiological saline water retention amount (hereinafter, may be simply referred to as “water retention amount”) according to the present embodiment is, for example, 30 g / g or more, 35 g / g or more, 38 g / g or more, or 40 g. It may be 50 g / g or less, 48 g / g or less, 45 g / g or less, or 43 g / g or less.
• the amount of water-absorbent resin particles used in the resin particle composition according to the present embodiment is, for example, 33 g / g or more, 35 g / g or more, 38 g / g or more, 40 g / g or more, or 42 g / g. It may be 55 g / g or less, 52 g / g or less, 50 g / g or less, 48 g / g or less, 45 g / g or less, or 43 g / g or less.
• the ratio of the water-retaining amount of the water-absorbent resin particles to the water-retaining amount of the resin particle composition according to the present embodiment is, for example, 60% or more. , 70% or more, 75% or more, 80% or more, or 85% or more, and may be 110% or less, 105% or less, 100% or less, 98% or less, 95% or less, or 90% or less. ..
• the medium particle size of the resin particle composition according to the present embodiment may be, for example, 20 ⁇ m or more, 60 ⁇ m or more, 80 ⁇ m or more, 100 ⁇ m or more, 150 ⁇ m or more, 200 ⁇ m or more, or 250 ⁇ m or more, and 800 ⁇ m or less, 700 ⁇ m or less. It may be 600 ⁇ m or less, 500 ⁇ m or less, 450 ⁇ m or less, 400 ⁇ m or less, or 380 ⁇ m or less.
• the fixing member layer preferably contains a heat-meltable resin.
• the fixing member may be 80% by mass, 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, or 100% by mass of a heat-meltable resin.
• the glass transition temperature of the heat-meltable resin forming the fixing member layer may be, for example, 20 ° C. or higher, 25 ° C. or higher, 30 ° C. or higher, 35 ° C. or higher, 40 ° C. or higher, or 50 ° C. or higher, and 90 ° C. or lower.
• the melting point of the heat-meltable resin forming the fixing member layer may be, for example, 70 to 175 ° C, 70 to 140 ° C, or 75 to 100 ° C.
• the resin (that is, the fixing member) forming the fixing member layer examples include polyethylene, polypropylene, an ethylene / butene copolymer, an ethylene / propylene copolymer, and an ethylene-based polymer such as an ethylene-acrylic acid copolymer; polyethylene.
• Polyether-based polymers such as glycol and polypropylene glycol; polyamide-based polymers such as nylon 6 and nylon 66; polyurethane-based polymers such as ether-based polyurethane, ester-based polyurethane and carbonate-based polyurethane; polyethylene terephthalate, polybutylene terephthalate and polyethylene.
• Polyester polymers such as naphthalate and polybutylene naphthalate; polyacetals such as polyoxymethylene, polyacetaldehyde, polypropionaldehyde and polybutylaldehyde; polyvinyl fluoride; vinylidene fluoride; polysiloxane; and the like can be mentioned. These resins may be used alone or in combination of two or more.
• Polyurethane is a reaction product of a polyol and a polyisocyanate.
• the polyol include polyether polyols, polyester polyols, polybutadiene polyols, hydrogenated polybutadiene polyols, and the like.
• polyisocyanate examples include aromatic isocyanates such as diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate and p-phenylenedi isocyanate; alicyclic isocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate; hexamethylene diisocyanate and the like. Examples include aliphatic isocyanates.
• the fixing member layer is chemically and / or physically bonded to the surface thereof so as not to easily fall off from the water-absorbent resin particles in the state before water absorption.
• the physical bond is realized, for example, by the anchor effect generated by the fixing member layer entering the fine recesses existing on the surface of the water-absorbent resin particles.
• the fixing member layer may be contained not only on the surface of the water-absorbent resin particles but also inside the water-absorbent resin particles. From the viewpoint of facilitating the manifestation of the effects of the present invention, it is preferable that most of the content of the fixing member layer is exposed and fixed in the vicinity of the surface.
• the amount of the fixing member layer fixed in the vicinity of the surface may be 70% by mass or more or 90% by mass or more with respect to the total amount of the fixing member layer contained in the resin particle composition.
• the heat-meltable resin of the fixing member layer may have a peeling adhesive strength of 1 to 500 N / 25 mm or 5 to 300 N / 25 mm as measured according to JIS Z0237.
• the occupancy ratio (that is, coverage) of the fixing member layer to the surface area of the water-absorbent resin particles is 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90. % Or more, 95% or more, 98% or more, or 99% or more, and may be 100% or less, 99% or less, 98% or less, 95% or less, 90% or less, or 80% or less.
• the coverage is calculated by RAMAN touch (manufactured by Nanophoton).
• the thickness of the fixing member layer of the resin particle composition may be 0.001 to 100 ⁇ m, 0.01 to 50 ⁇ m, or 0.1 to 30 ⁇ m.
• the amount of the fixing member layer is 0.01 part by mass or more, 0.05 part by mass or more, 0.1 part by mass or more, and 0.5 part by mass with respect to 100 parts by mass of the water-absorbent resin particles. It may be 1 part by mass or more, 1.5 parts by mass or more, 2 parts by mass or more, 3 parts by mass or more, 4 parts by mass or more, or 5 parts by mass or more, and 10 parts by mass or less, 8 parts by mass or less, or It may be 6 parts by mass or less.
• the water-absorbent resin particles may contain, for example, a crosslinked polymer formed by polymerizing a monomer containing an ethylenically unsaturated monomer.
• the crosslinked polymer can have a monomeric unit derived from an ethylenically unsaturated monomer.
• the water-absorbent resin particles can be produced, for example, by a method including a step of polymerizing a monomer containing an ethylenically unsaturated monomer. Examples of the polymerization method include a reverse phase suspension polymerization method, an aqueous solution polymerization method, a bulk polymerization method, a precipitation polymerization method and the like.
• the ethylenically unsaturated monomer may be a water-soluble ethylenically unsaturated monomer.
• water-soluble ethylenically unsaturated monomer include (meth) acrylic acid and its salt, 2- (meth) acrylamide-2-methylpropanesulfonic acid and its salt, (meth) acrylamide, N, N-dimethyl.
• the ethylenically unsaturated monomer has an amino group, the amino group may be quaternized.
• the ethylenically unsaturated monomer may be used alone or in combination of two or more.
• the acid group may be neutralized with an alkaline neutralizing agent and then used in the polymerization reaction.
• the degree of neutralization of the ethylenically unsaturated monomer by the alkaline neutralizing agent is, for example, 10 to 100 mol%, 50 to 90 mol%, or 60 to 80 mol% of the acidic group in the ethylenically unsaturated monomer. May be%.
• the ethylenically unsaturated monomer is at least one selected from the group consisting of (meth) acrylic acid and salts thereof, acrylamide, methacrylamide, and N, N-dimethylacrylamide. It may contain a compound of the species.
• the ethylenically unsaturated monomer may contain (meth) acrylic acid and a salt thereof, and at least one compound selected from the group consisting of acrylamide.
• a monomer other than the above-mentioned ethylenically unsaturated monomer may be used.
• Such a monomer can be used, for example, by mixing with an aqueous solution containing the above-mentioned ethylenically unsaturated monomer.
• the amount of the ethylenically unsaturated monomer used may be 70 to 100 mol% with respect to the total amount of the monomers.
• the ratio of (meth) acrylic acid and a salt thereof may be 70 to 100 mol% with respect to the total amount of the monomer.
• Cross-linking may occur by self-cross-linking during polymerization, but cross-linking may be performed by using an internal cross-linking agent.
• an internal cross-linking agent When an internal cross-linking agent is used, it is easy to control the water absorption characteristics (water retention amount, etc.) of the water-absorbent resin particles.
• the internal cross-linking agent is usually added to the reaction solution during the polymerization reaction.
• the water-absorbent resin particles may be crosslinked (surface crosslinked) in the vicinity of the surface. Further, the water-absorbent resin particles may be composed of only polymer particles (crosslinked polymers), but various types selected from, for example, gel stabilizers, metal chelating agents, fluidity improving agents (lubricants) and the like. It may further contain additional ingredients. Additional components may be placed inside the polymer particles, on the surface of the polymer particles, or both. The additional component may be a fluidity improver (lubricant).
• the fluidity improver may contain inorganic particles. Examples of the inorganic particles include silica particles such as amorphous silica.
• the shape of the water-absorbent resin particles may be, for example, substantially spherical, crushed or porous, and may be a shape in which primary particles having these shapes are aggregated. Above all, from the viewpoint of easy dispersion of the resin particles at the time of producing the absorber, a substantially spherical shape or an aggregated shape thereof is preferable.
• the resin particle composition according to the present embodiment may include, for example, a step of mixing the water-absorbent resin particles and the fixing member to form a fixing member layer on at least a part of the surface of the water-absorbent resin particles.
• the amount of the fixing member used for mixing is 0.1 part by mass or more, 0.5 part by mass or more, 1 part by mass or more, 2 parts by mass or more, or 3 parts by mass or more with respect to 100 parts by mass of the water-absorbent resin particles. It may be 10 parts by mass or less, 8 parts by mass or less, or 6 parts by mass or less.
• the fixing member is, for example, a heat-meltable resin capable of forming the above-mentioned fixing member layer.
• the resin usually contains a polymer composed of repeating units.
• the fixing member may contain not only the heat-meltable polymer itself but also a forming material such as a monomer or a precursor thereof.
• the fixing member layer contains polyurethane
• the fixing member may contain polyurethane itself, or may contain a polyol and a polyisocyanate which are materials for forming the polyurethane.
• the method for producing the resin particle composition according to the present embodiment is preferably after mixing the water-absorbent resin particles and the fixing member. It further comprises a step of polymerizing the members.
• a specific method for producing the resin particle composition will be described for each state of the fixing member.
• the fixing member can be fixed to the surface of the water-absorbent resin particles by using the particle composite device to form the fixing member layer. Specifically, a predetermined amount of water-absorbent resin particles and a solid (for example, powdery) fixing member are charged into the particle composite device. After that, stress (compressive stress and shear stress) is applied to the water-absorbent resin particles and the fixing member by the rotation of the stirring blade provided in the apparatus, and the fixing member is crimped to the surface of the water-absorbent resin particles by the stress.
• a particle composition is prepared.
• the thickness and coverage of the fixing member layer can be arbitrarily adjusted by appropriately adjusting the amounts of the water-absorbent resin particles and the fixing member to be charged into the particle composite device.
• the water-absorbent resin particles and the fixing member may be separately charged into the particle composite device, but since more uniform dispersion and coating can be expected, the particles are in a state where the water-absorbent resin particles and the fixing member are mixed in advance. It is preferable to put it in the composite device.
• the particle composite device it is easy to obtain a resin particle composition in which a fixing member layer is fixed to at least a part of the surface of the water-absorbent resin particles.
• the particle compounding device for example, the particle compounding device Novirta MINI (manufactured by Sugino Machine Limited) can be used.
• the liquid fixing member (hereinafter, simply referred to as "fixing member liquid”) can be obtained by melting the fixing member, or can be obtained by dissolving or dispersing the fixing member in an arbitrary solvent or dispersion medium. can. Since it is easy to form a fixing member layer having a uniform thickness, the fixing member liquid is preferably obtained by dissolving or dispersing the fixing member in an arbitrary solvent or dispersion medium. Whether the fixing member liquid becomes a solution or a dispersion liquid is determined by the properties of the fixing member and the medium used.
• the solvent or dispersion medium examples include water, a hydrophilic compound, a mixture of water and a hydrophilic compound, a hydrocarbon compound, and the like.
• the hydrophilic compound is a compound that dissolves substantially uniformly in water.
• examples of the hydrophilic compound include alcohols such as methanol and isopropyl alcohol; glycols such as ethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; ethers such as tetrahydrofuran. Can be mentioned.
• hydrocarbon compound examples include chain aliphatic hydrocarbons such as n-hexane, n-heptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, and n-octane; Alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, trans-1,2-dimethylcyclopentane, cis-1,3-dimethylcyclopentane, trans-1,3-dimethylcyclopentane; benzene , Aromatic hydrocarbons such as toluene and xylene, and the like. These may be used alone or in combination of two or more.
• the concentration of the fixing member in the fixing member liquid is not particularly limited, and can be appropriately adjusted in consideration of the amount of water-absorbent resin particles in order to obtain a fixing member layer having a desired thickness. It may be 3 to 30% by mass, or 5 to 20% by mass.
• the fixing member layer is, for example, (1) a method of adding the fixing member liquid to the hydrocarbon dispersion medium in which the water-absorbent resin particles are dispersed, and (2) the fixing member liquid and water absorption in the hydrocarbon dispersion medium.
• a method of adding the sex resin particles substantially at the same time (3) a method of bringing the fixing member liquid into contact with the water-absorbent resin particles in a dry state, (4) a method of polymerizing the fixing member in the presence of the water-absorbent resin particles, or ( 5)
• It can be formed by a method of cross-linking a fixing member (including a precursor) with a cross-linking agent in the presence of water-absorbent resin particles.
• each method will be specifically described.
• a separable flask equipped with a reflux condenser, a dropping funnel, a nitrogen gas introduction tube, and a stirrer is prepared.
• the hydrocarbon dispersion medium and the water-absorbent resin particles are put into the flask, and the flask is sufficiently stirred while maintaining a high temperature (for example, 60 to 80 ° C.).
• a solvent or a dispersion medium and a fixing member are added to the beaker and mixed to prepare a fixing member liquid.
• the flask After adding the fixing member liquid into the flask and stirring sufficiently, the flask is immersed in an oil bath set at a high temperature (for example, 100 to 125 ° C.), and the hydrocarbon dispersion medium and water are co-distilled. While refluxing the hydrocarbon dispersion medium, water that may be contained in the reaction system is extracted from the system. Then, by evaporating the hydrocarbon dispersion medium, a resin particle composition in which the fixing member is fixed on the surface of the water-absorbent resin particles can be obtained.
• a high temperature for example, 100 to 125 ° C.
• the above method (3) is various, but the following are typical examples thereof: (3-1) a method using an eggplant flask, (3-2) a method using an atomizer, and (3-3) various granulators. The method using the above will be described.
• the fixing member liquid is charged into the eggplant flask, and then the water-absorbent resin particles are charged.
• the eggplant flask is attached to an evaporator and heated while rotating to distill off the solvent or dispersion medium contained in the fixing member liquid under reduced pressure conditions.
• a resin particle composition in which the fixing member is fixed on the surface of the water-absorbent resin particles can be obtained.
• (3-2) Water-absorbent resin particles are added to a separable flask equipped with a stirring blade and stirred.
• the fixing member liquid is sprayed on the water-absorbent resin particles wound up by stirring with the stirring blade.
• the fixing member liquid can be sprayed, for example, by using a two-fluid type nozzle. Since uniform dispersion and coating can be expected, it is desirable that the fixing member liquid is atomized and sprayed by an air flow of an inert gas such as nitrogen. Then, the contents of the flask are taken out, heated by a hot air dryer, and then cooled to room temperature to obtain a resin particle composition.
• Examples of the granulator used for producing the resin particle composition include a rolling granulator, a stirring granulator, a fluidized bed granulator, and the like.
• a shallow, inclined circular container provided in the rolling granulator is rotated, water-absorbent resin particles are supplied to the circular container, and an appropriate amount of fixing member liquid is added. Then, a part of the water-absorbent resin particles during rolling is aggregated by the solvent or the dispersion medium contained in the fixing member liquid, and the fixing member layer is formed on the surface thereof.
• the step of adding the water-absorbent resin particles and the fixing member liquid may be performed a plurality of times if necessary.
• the water-absorbent resin particles When using a stirring granulator, the water-absorbent resin particles are put into a mixer installed in the stirring granulator, mixed by stirring, and the fixing member liquid is added. Then, a part of the water-absorbent resin particles during stirring is aggregated by the solvent or the dispersion medium contained in the fixing member liquid, and the fixing member layer is formed on the surface thereof.
• the step of adding the water-absorbent resin particles and the fixing member liquid may be performed a plurality of times if necessary. Excessive aggregation of the water-absorbent resin particles can be suppressed by controlling the shearing force of the mixer.
• the water-absorbent resin particles are put into a container equipped in the fluidized bed granulator that can send out hot air from the lower part, and the water-absorbent resin particles are fluidized in advance.
• the fixing member liquid is sprayed from the nozzle provided in the container, a part of the water-absorbent resin particles during stirring is aggregated by the solvent or the dispersion medium contained in the fixing member liquid, and the fixing member layer is formed on the surface thereof. It is formed.
• the fixing member liquid may be sprayed multiple times if necessary. Excessive aggregation of the water-absorbent resin particles can be suppressed by adjusting the spraying amount and spraying frequency of the fixing member liquid.
• a fluidized bed granulator FBD / SG manufactured by Mutual Co., Ltd.
• gel-like water-absorbent resin particles containing water in a separable flask are prepared by a known reverse-phase suspension polymerization method.
• the water-absorbent resin particles may be obtained by one-stage polymerization or may be obtained by two-stage or more multi-stage polymerization.
• a monomer aqueous solution of the fixing member containing the fixing member, the polymerization initiator, and, if necessary, the internal cross-linking agent is prepared.
• the fixing member contains, for example, a polyol and a polyisocyanate when the fixing member layer contains polyurethane.
• gel-like water-absorbent resin particles containing water in a separable flask are prepared by a known reverse-phase suspension polymerization method.
• the water-absorbent resin particles may be obtained by one-stage polymerization or may be obtained by two-stage or more multi-stage polymerization.
• a precursor aqueous solution containing a fixing member (including a precursor) and a cross-linking agent is prepared.
• the fixing member layer is formed using the fixing member liquid
• the fixing member is likely to come into uniform contact with the water-absorbent resin particles, so that it is considered that the obtained resin particle composition is likely to exhibit prevention of falling off in the absorber.
• the methods (1), (2), and (3) using the fluidized bed granulator, (4), and (5) have a more uniform thickness of the fixing member than the other methods. It is thought that the layer is easy to obtain.
• the resin particle composition according to the present embodiment may be used in fields such as disposable diapers, sanitary materials such as sanitary products, agricultural and horticultural materials such as water retention agents and soil conditioners, and industrial materials such as water blocking agents and dew condensation inhibitors. Suitable.
• Example 1 Preparation of water-absorbent resin particles
• 293 g of n-heptane was added as a hydrocarbon dispersion medium, and 0.736 g of a maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., High Wax 1105A) was added as a polymer-based dispersant.
• the mixture in the flask was heated to 80 ° C. with stirring to dissolve the dispersant, and then cooled to 50 ° C.
• hydroxyethyl cellulose (Sumitomo Seika Co., Ltd., HEC AW-15F) as a thickener
• 0.0736 g 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerization initiator
• ethylene as an internal cross-linking agent.
• 0.010 g (0.057 mmol) of glycol diglycidyl ether was added and dissolved to prepare a first-stage monomer aqueous solution.
• the inside of the flask system was cooled to 25 ° C. while stirring at a stirring speed of 1000 rpm, and then the entire amount of the second-stage monomer aqueous solution was added to the first-stage polymerized slurry liquid to add the system.
• the inside was replaced with nitrogen for 30 minutes.
• the flask was immersed in a water bath at 70 ° C. again to raise the temperature, and the polymerization reaction was carried out for 60 minutes to obtain a hydrogel-like polymer.
• hydrogel polymer 0.589 g of a 45% by mass diethylenetriamine-5 sodium acetate aqueous solution was added under stirring. Then, the flask was immersed in an oil bath set at 125 ° C., and 257.2 g of water was extracted from the system while refluxing n-heptane by azeotropic distillation of n-heptane and water. Then, 4.42 g (0.507 mmol) of a 2% by mass ethylene glycol diglycidyl ether aqueous solution was added to the flask as a surface cross-linking agent, and the mixture was kept at 83 ° C. for 2 hours.
• n-heptane and water were heated in an oil bath at 125 ° C. to evaporate and dried to obtain a dried product of polymer particles.
• the polymer particles were passed through a sieve having an opening of 850 ⁇ m to obtain 231.2 g of water-absorbent resin particles.
• the above operation was repeated, and the obtained water-absorbent resin particles were classified by a sieve having an opening of 250 ⁇ m, and 500 g or more of the water-absorbent resin particles (A) having a particle diameter of 250 to 850 ⁇ m were obtained.
• the water retention amount of the water-absorbent resin particles (A) was 41 g / g.
• Example 2 Same as Example 1 except that the fixing member liquid was changed to a solution obtained by diluting 57.1 g of a 35% aqueous dispersion emulsion of polyurethane (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210) with 342.9 g of ion-exchanged water. To obtain 508.1 g of a resin particle composition having a medium particle diameter of 345 ⁇ m.
• Example 3 Example 1 and the fixing member liquid were changed to those obtained by diluting 62.5 g of a 40% aqueous dispersion emulsion of a nylon copolymer (Sumitomo Seika Co., Ltd., Sepoljon PA200) with 187.5 g of ion-exchanged water. The same procedure was carried out to obtain 502.3 g of a resin particle composition having a medium particle diameter of 336 ⁇ m.
• Example 4 The fixing member liquid was changed to one obtained by dissolving 20.0 g of polyethylene glycol (Fujifilm Wako Pure Chemical Industries, Ltd., polyethylene glycol 6,000) in 180.0 g of ion-exchanged water, and warm air in a fluidized bed granulator. The same procedure as in Example 1 was carried out except that the temperature and the drying temperature were changed to 60 ° C. to obtain 508.3 g of a resin particle composition having a medium particle diameter of 347 ⁇ m.
• polyethylene glycol Flujifilm Wako Pure Chemical Industries, Ltd., polyethylene glycol 6,000
• Example 5 The fixing member liquid was changed to one in which 25.0 g of an ethylene-sodium acrylate copolymer (SK particle chemical, primacol) was dissolved in 225.0 g of tetrahydrofuran, and the temperature and drying of hot air in a fluidized bed granulator. The same procedure as in Example 1 was carried out except that the temperature was changed to 40 ° C. to obtain 502.0 g of a resin particle composition having a medium particle diameter of 337 ⁇ m.
• SK particle chemical, primacol ethylene-sodium acrylate copolymer
• a 2 L volume, round-bottomed cylindrical separable flask with four side wall baffles (baffle length: 10 cm, baffle width: 7 mm) was prepared.
• the mixture in the flask was heated to 50 ° C. while stirring at a rotation speed of 300 rpm to dissolve the surfactant, and then cooled to 40 ° C.
• the polymer solution containing the produced hydrogel-like polymer, n-heptane and a surfactant was mixed for 10 minutes while stirring at a stirring speed of 1000 rpm.
• the flask containing the reaction solution was immersed in an oil bath at 125 ° C., and 97.0 g of water was extracted from the system while refluxing n-heptane by azeotropic distillation of n-heptane and water.
• sorbitan monolaurate (trade name: Nonion LP-20R, HLB value 8.6, manufactured by Nichiyu Co., Ltd.), which is a surfactant, in 6.62 g of n-heptane. did.
• the surfactant solution was added into the flask.
• the water-absorbing resin particles (B) had a water retention amount of 38 g / g and a medium particle diameter of 205 ⁇ m.
• the fixing member liquid was changed to 100.0 g of a 25% aqueous dispersion emulsion of an ethylene-sodium acrylate copolymer (Sumitomo Seika Co., Ltd., Zyxen N) diluted with 150.0 g of ion-exchanged water.
• the same operation as in Example 1 was carried out except that the water-absorbent resin particles (B) were used instead of the water-absorbent resin particles (A), and 506.3 g of a resin particle composition having a medium particle diameter of 213 ⁇ m was obtained. ..
• Example 7 (Preparation of water-absorbent resin particles)
• 293 g of n-heptane was added as a hydrocarbon dispersion medium, and 0.736 g of a maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals, Inc., High Wax 1105A) was added as a polymer-based dispersant.
• the mixture in the flask was heated to 80 ° C. with stirring to dissolve the dispersant, and then cooled to 50 ° C.
• hydroxyethyl cellulose (Sumitomo Seika Co., Ltd., HEC AW-15F) as a thickener
• 0.0736 g 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerization initiator
• ethylene as an internal cross-linking agent.
• 0.010 g (0.057 mmol) of glycol diglycidyl ether was added and dissolved to prepare a first-stage monomer aqueous solution.
• a surfactant solution was prepared by heating and dissolving 0.736 g of sucrose stearic acid ester (HLB: 3, Mitsubishi Chemical Foods Co., Ltd., Ryoto Sugar Ester S-370) as a surfactant in 6.62 g of n-heptane. ..
• HLB sucrose stearic acid ester
• the surfactant solution is added to the flask, and the inside of the system is stirred while stirring at a stirring speed of 500 rpm. Was sufficiently replaced with.
• the flask was immersed in a water bath at 70 ° C. to raise the temperature, and the polymerization was carried out for 60 minutes to obtain a first-stage polymerization slurry liquid.
• the inside of the flask system was cooled to 44 ° C. while stirring at a stirring machine rotation speed of 1000 rpm. Then, the whole amount of the aqueous solution of the second stage was added to the polymerized slurry solution of the first stage, and the inside of the system was replaced with nitrogen for 30 minutes. Then, the flask was immersed in a water bath at 70 ° C. again to raise the temperature, and the polymerization reaction was carried out for 60 minutes to obtain a hydrogel polymer.
• the flask was immersed in an oil bath set at 125 ° C., and 260.1 g of water was extracted from the system while refluxing n-heptane by azeotropic distillation of n-heptane and water. Then, 4.42 g (0.507 mmol) of a 2% by mass ethylene glycol diglycidyl ether aqueous solution was added to the flask as a surface cross-linking agent, and the mixture was kept at 83 ° C. for 2 hours.
• the water-absorbing resin particles (C) had a water retention amount of 43 g / g and a medium particle diameter of 72 ⁇ m.
• the fixing member liquid was changed to 100.0 g of a 25% aqueous dispersion emulsion of an ethylene-sodium acrylate copolymer (Sumitomo Seika Co., Ltd., Zyxen N) diluted with 150.0 g of ion-exchanged water.
• the same procedure as in Example 1 was carried out except that the water-absorbent resin particles (C) were used instead of the water-absorbent resin particles (A), and 504.8 g of a resin particle composition having a medium particle diameter of 86 ⁇ m was obtained.
• the obtained resin particle composition was evaluated according to the following items. Unless otherwise specified, the measurements were carried out in an environment with a temperature of 25 ⁇ 2 ° C. and a humidity of 50 ⁇ 10%.
• a release paper (KA-4G white BD manufactured by Lintec Corporation) coated with silicone on one side was cut into a circle having a diameter of 50 mm.
• a circular release paper was laid in a circular stainless steel petri dish with an inner diameter of 52 mm so that the silicone-coated surface was on top.
• 2.0 ⁇ 0.002 g of a resin particle composition excluding particles having a particle size of 850 ⁇ m or more was uniformly sprinkled on the release paper.
• a release paper similar to the above is placed on the resin particle composition so that the silicone-coated surface is in contact with the resin particle composition, and a circular stainless steel canyon having an outer diameter of 50 mm and a mass of 20 g and a columnar diameter of 45 mm are placed.
• a measurement sample was prepared by stacking 780 g of the weights in this order.
• the measurement sample was placed in a hot air dryer set to an internal temperature of 80 ° C. and allowed to stand for 1 hour.
• the measurement sample was taken out from the hot air dryer and allowed to cool to room temperature.
• the resin particle composition is taken out from the measurement sample together with the release paper, and the resin particle composition is carefully removed from the release paper on a sieve (inner diameter 200 mm) having an opening of 850 ⁇ m with a saucer at the bottom, and the total amount of the resin particle composition is obtained.
• a sieve inner diameter 200 mm
• the water retention amount of the water-absorbent resin particles and the physiological saline of the resin particle composition was measured by the following procedure. First, a cotton bag (Membrod No. 60, width 100 mm ⁇ length 200 mm) from which 2.0 ⁇ 0.002 g of measurement particles were weighed was placed in a beaker having an internal volume of 500 mL. After pouring 500 g of physiological saline into a cotton bag containing the measurement particles at a time so that maco could not be formed, the upper part of the cotton bag was tied with a rubber band and allowed to stand for 30 minutes to swell the measurement particles.
• the cotton bag after 30 minutes was dehydrated for 1 minute using a dehydrator (manufactured by Kokusan Co., Ltd., product number: H-122) set to have a centrifugal force of 167 G, and then contained the swollen gel after dehydration.
• the mass Wc [g] of the cotton bag was measured. Perform the same operation without adding the water-absorbent resin particles or the resin particle composition, measure the empty mass Wd [g] when the cotton bag is wet, and use the following formula to measure the physiology of the water-absorbent resin particles and the resin particle composition.
• the above-mentioned medium particle size of the resin particle composition was measured by the following procedure. That is, from the top of the JIS standard sieve, a sieve with an opening of 600 ⁇ m, a sieve with an opening of 500 ⁇ m, a sieve with an opening of 425 ⁇ m, a sieve with an opening of 300 ⁇ m, a sieve with an opening of 250 ⁇ m, a sieve with an opening of 180 ⁇ m, and a sieve with an opening of 150 ⁇ m. , And the saucer in that order. 50 g of the resin particle composition was put into the combined best sieve and shaken for 10 minutes using a low-tap type shaker to classify.
• the mass of the particles remaining on each sieve was calculated as a mass percentage with respect to the total amount, and the particle size distribution was obtained.
• the relationship between the mesh size of the sieve and the integrated value of the mass percentage of the particles remaining on the sieve was plotted on a logarithmic probability paper by integrating the particles on the sieve in order from the one having the largest particle size with respect to this particle size distribution. By connecting the plots on the probability paper with a straight line, the particle size corresponding to the integrated mass percentage of 50% by mass was obtained as the medium particle size.
• a resin particle composition having a caking index of a certain level or higher was obtained.

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