WO2018174175A1 - Procédé de fabrication de résine absorbant l'eau - Google Patents

Procédé de fabrication de résine absorbant l'eau Download PDF

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WO2018174175A1
WO2018174175A1 PCT/JP2018/011453 JP2018011453W WO2018174175A1 WO 2018174175 A1 WO2018174175 A1 WO 2018174175A1 JP 2018011453 W JP2018011453 W JP 2018011453W WO 2018174175 A1 WO2018174175 A1 WO 2018174175A1
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water
absorbent resin
polymerization
hydrogel
crosslinked polymer
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PCT/JP2018/011453
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English (en)
Japanese (ja)
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裕一 小野田
健太 熊澤
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住友精化株式会社
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Application filed by 住友精化株式会社 filed Critical 住友精化株式会社
Priority to JP2019506978A priority Critical patent/JP7355646B2/ja
Priority to CN201880019427.2A priority patent/CN110402267A/zh
Publication of WO2018174175A1 publication Critical patent/WO2018174175A1/fr

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  • the present invention relates to a method for producing a water absorbent resin.
  • water-absorbent resins have been widely used in various absorbent articles such as sanitary materials such as disposable diapers and sanitary products, agricultural and horticultural materials such as water retention agents and soil conditioners, and industrial materials such as water-stopping agents and anti-condensation agents. in use.
  • Many types of water-absorbing resins are known depending on the application, and among them, a polymer having a crosslinked structure obtained by polymerizing a water-soluble ethylenically unsaturated monomer (hereinafter, A water-absorbing resin composed of a crosslinked polymer) is mainly used.
  • the production method include a method in which a hydrogel of a crosslinked polymer is produced by aqueous solution polymerization, suspension polymerization or the like and then dried.
  • Patent Document 1 as a production method thereof, for example, a water-containing gel of such a crosslinked polymer (hereinafter referred to as a water-containing gel of a cross-linked polymer) is prepared by an aqueous solution polymerization method, and the water content of the cross-linked polymer obtained as a lump is obtained. It is disclosed that a water-absorbent resin as a final product can be obtained by heating the gel to a temperature of 45 to 90 ° C., coarsely crushing, drying, crushing the dried product, and adjusting the particle size and surface cross-linking as necessary. ing.
  • a water-absorbent resin as a final product can be obtained by heating the gel to a temperature of 45 to 90 ° C., coarsely crushing, drying, crushing the dried product, and adjusting the particle size and surface cross-linking as necessary. ing.
  • Patent Document 2 in a method for producing a particulate hydrogel polymer in which a sheared force is applied to a hydrogel polymer having a crosslinked structure in a container, the temperature is set to 40 to 110 ° C.
  • a method for producing a particulate hydrogel polymer is disclosed, in which a shearing force is repeatedly applied to a heated hydrogel polymer while applying a load of 0.01 to 1.5 kg / cm 2 .
  • Patent Document 3 discloses a method for producing a particulate hydrogel polymer by extruding a hydrogel polymer having a crosslinked structure from a porous plate having a pore diameter of 3 to 20 mm and a thickness of 1 to 20 mm.
  • a gel crusher used for producing a water-absorbent resin which includes a screw, a supply port, an extrusion port, a perforated plate, and a barrel, is used at 40 ° C. to 120 ° C. in the gel crushing process. It is disclosed that a water-absorbing resin is produced by using a gel pulverizing apparatus characterized by:
  • the temperature of the hydrogel is set to a temperature higher than 35 ° C. or 40 ° C., and the hydrogel is roughly crushed using a specific device such as a perforated plate or a pressure lid. .
  • the crosslinked polymer obtained by polymerizing the water-soluble ethylenically unsaturated monomer is obtained as a mass of hydrous gel.
  • the water-containing gel of the obtained crosslinked polymer is coarsely crushed and then subjected to drying, and then the dried product is pulverized, and if necessary, particle size adjustment and surface crosslinking are performed to obtain a final product water-absorbent resin.
  • the obtained water-absorbent resin has a problem that the production lot is likely to vary depending on the production conditions, and in particular, the reproducibility of the particle size distribution is low.
  • An object of the present invention is to provide a method for producing a water-absorbent resin with improved reproducibility of the particle size distribution of the water-absorbent resin and less variation between production lots.
  • the present inventors set the temperature of the water-containing gel of the crosslinked polymer to 35 ° C. or lower in the method for producing a water-absorbent resin, and coarsely crush the water-containing gel. It has been found that the reproducibility of the particle size distribution of the obtained water-absorbent resin is enhanced by including the step of performing the step.
  • the present invention is a method for producing a water-absorbent resin comprising a crushing step of crushing a hydrogel of a crosslinked polymer, wherein the water-absorbing resin has a temperature of 35 ° C. or less in the crushing step.
  • a manufacturing method is provided.
  • the reproducibility of the particle size distribution of the water-absorbent resin obtained can be improved by using the production method of the present invention.
  • the water-containing gel of the crosslinked polymer in the present invention includes, for example, a water-soluble ethylenically unsaturated monomer in an aqueous solution containing a water-soluble ethylenically unsaturated monomer (hereinafter also referred to as “monomer aqueous solution”). It can be obtained by polymerization.
  • water-soluble ethylenically unsaturated monomer examples include, for example, (meth) acrylic acid (in this specification, “acryl” and “methacryl” are collectively referred to as “(meth) acryl”.
  • carboxylic acid monomers such as ⁇ , ⁇ -unsaturated carboxylic acids such as maleic acid, maleic anhydride, fumaric acid and their salts; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, Nonionic monomers such as 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate; N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl Amino group-containing unsaturated monomers such as (meth) acrylate and diethylaminopropyl (meth) acrylamide and quaternized products thereof; Rusuruhon acid, styrene sulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid, 2- (meth) acryloyl ethane sul
  • the water-soluble ethylenically unsaturated monomer is preferably at least one selected from (meth) acrylic acid and salts thereof.
  • (Meth) acrylic acid and salts thereof may be used by copolymerizing other water-soluble ethylenically unsaturated monomers.
  • the total amount of the water-soluble ethylenically unsaturated monomer is preferably 70 to 100 mol%, more preferably 80 to 100 mol%, and more preferably 90 to 100 mol%. Further preferred.
  • the acid group is preliminarily alkaline if necessary. What was neutralized with the summing agent can be used.
  • alkaline neutralizer include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, potassium carbonate; ammonia and the like.
  • alkaline neutralizing agents may be used in the form of an aqueous solution in order to simplify the neutralization operation.
  • the alkaline neutralizing agent may be used alone or in combination of two or more.
  • the neutralization of the acid group may be performed before the polymerization of the water-soluble ethylenically unsaturated monomer as a raw material, or may be performed during or after the polymerization.
  • the degree of neutralization of water-soluble ethylenically unsaturated monomers with alkaline neutralizers increases the water absorption performance by increasing the osmotic pressure of the resulting water-absorbent resin, and is safe due to the presence of excess alkaline neutralizers From the viewpoint of preventing problems in properties and the like, it is usually preferably 10 to 100 mol%, more preferably 30 to 90 mol%, still more preferably 40 to 85 mol%, More preferably, it is 50 to 80 mol%.
  • the neutralization degree is defined as the neutralization degree for all acid groups of the water-soluble ethylenically unsaturated monomer.
  • the concentration of the water-soluble ethylenically unsaturated monomer in the monomer aqueous solution may be usually 20% by mass or more and saturated concentration or less, preferably 25 to 70% by mass, more preferably 30 to 50% by mass. .
  • the cross-linked polymer preferably has, as its internal cross-linked structure, cross-linking by an internal cross-linking agent in addition to self-cross-linking by a polymerization reaction.
  • an internal crosslinking agent for example, a compound having two or more polymerizable unsaturated groups is used.
  • (poly) ethylene glycol in this specification, for example, “polyethylene glycol” and “ethylene glycol” are collectively referred to as “(poly) ethylene glycol”; the same applies hereinafter), (poly) propylene glycol, trimethylolpropane.
  • Di- or tri (meth) acrylic esters of polyols such as glycerin polyoxyethylene glycol, polyoxypropylene glycol, and (poly) glycerin; reaction of the polyol with unsaturated acids such as maleic acid and fumaric acid Unsaturated polyesters obtained by reaction; bisacrylamides such as N, N′-methylenebis (meth) acrylamide; di- or tri (meth) acrylates obtained by reacting polyepoxides with (meth) acrylic acid; Tolylene diisocyanate Di (meth) acrylic acid carbamyl esters obtained by reacting polyisocyanates such as sulfonate and hexamethylene diisocyanate with hydroxyethyl (meth) acrylate; allylated starch; allylated cellulose; diallyl phthalate; N, N ' , N ′′ -triallyl isocyanurate; divinylbenzene and the like.
  • a compound having two or more reactive functional groups can be used as an internal crosslinking agent.
  • glycidyl group-containing compounds such as (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether; (poly) ethylene glycol, (poly) propylene glycol, (poly) Examples include glycerin, pentaerythritol, ethylenediamine, polyethyleneimine, and glycidyl (meth) acrylate.
  • (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether are preferable from the viewpoint of excellent reactivity at low temperatures.
  • These internal crosslinking agents may be used alone or in combination of two or more.
  • the amount used is 0.0001 with respect to 100 moles of the water-soluble ethylenically unsaturated monomer in order to sufficiently enhance the water-absorbing performance such as the water-holding ability of the resulting water-absorbent resin.
  • Mol or more is preferable, 0.001 mol or more is more preferable, 0.003 mol or more is more preferable, and 0.01 mol or more is more preferable.
  • an increase in the amount of internal cross-linking agent leads to a decrease in the water absorption capacity of the resulting water-absorbent resin.
  • the monomer aqueous solution may contain additives such as a chain transfer agent, a thickener, and an inorganic filler as necessary.
  • a chain transfer agent include thiols, thiolic acids, secondary alcohols, hypophosphorous acid, phosphorous acid and the like.
  • the thickener include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyethylene glycol, polyacrylic acid, polyacrylic acid neutralized product, polyacrylamide and the like.
  • inorganic fillers include metal oxides, ceramics, and viscous minerals. These may be used alone or in combination of two or more.
  • the water-soluble ethylenically unsaturated monomer in the aqueous solution is polymerized using a polymerization initiator in the presence of a crosslinking agent as necessary.
  • aqueous solution polymerization emulsion polymerization, reverse phase suspension polymerization and the like are used.
  • the polymerization method may be a static polymerization method in which the monomer aqueous solution is polymerized without stirring (for example, a static state), a stirring polymerization method in which the monomer aqueous solution is polymerized while stirring in the reaction apparatus, or the like. .
  • aqueous solution polymerization it is preferable to obtain a crosslinked polymer hydrogel by aqueous solution static polymerization, which is a static polymerization method.
  • the water-containing gel of the cross-linked polymer is obtained as a single block-like water-containing gel occupying substantially the same volume as the aqueous monomer solution present in the reaction vessel when the polymerization is completed.
  • the monomer aqueous solution may contain a water-soluble organic solvent other than water as appropriate.
  • the form of manufacture may be batch, semi-continuous, continuous, etc.
  • aqueous solution polymerization it is a stationary polymerization system, and in a continuous form, in aqueous solution stationary continuous polymerization, a polymerization reaction is performed while continuously supplying an aqueous monomer solution to a continuous polymerization apparatus.
  • a hydrogel (for example in the form of a band) can be obtained.
  • Polymerization initiator Polymerization is started by adding a polymerization initiator to the monomer aqueous solution and performing heating, light irradiation, etc. as necessary.
  • a polymerization initiator a water-soluble radical polymerization initiator is preferably used.
  • peroxide used as the polymerization initiator examples include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t Organic peroxides such as butyl cumyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, and t-butyl peroxypivalate; peroxides such as hydrogen peroxide.
  • persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate
  • methyl ethyl ketone peroxide methyl isobutyl ketone peroxide
  • di-t-butyl peroxide di-t-butyl peroxide
  • t Organic peroxides such as butyl cumyl peroxide,
  • potassium persulfate, ammonium persulfate, sodium persulfate, and hydrogen peroxide are preferably used from the viewpoint of obtaining a water-absorbing resin having good water absorption performance. It is more preferable to use ammonium sulfate or sodium persulfate.
  • These peroxides may be used alone or in combination of two or more. For example, persulfate and hydrogen peroxide can be used in combination.
  • Examples of the azo compound used as the polymerization initiator include 2,2′-azobis [2- (N-phenylamidino) propane] dihydrochloride, 2,2′-azobis ⁇ 2- [N- (4 -Chlorophenyl) amidino] propane ⁇ dihydrochloride, 2,2′-azobis ⁇ 2- [N- (4-hydroxyphenyl) amidino] propane ⁇ dihydrochloride, 2,2′-azobis [2- (N-benzyl) Amidino) propane] dihydrochloride, 2,2′-azobis [2- (N-allylamidino) propane] dihydrochloride, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′- Azobis ⁇ 2- [N- (2-hydroxyethyl) amidino] propane ⁇ dihydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2 , 2'-azobi [
  • 2,2′-azobis (2-amidinopropane) dihydrochloride 2,2′-azobis ⁇ 2- [1- (2-hydroxyethyl) ) -2-imidazolin-2-yl] propane ⁇ dihydrochloride and 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] tetrahydrate are preferred.
  • These azo compounds may be used alone or in combination of two or more.
  • the polymerization initiator is preferably used in combination of two or more of the above, and in particular, a peroxide and a water-soluble azo compound are combined. Is more preferable.
  • the polymerization initiator can be used in combination with a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, and L-ascorbic acid to be used as a redox polymerization initiator.
  • a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, and L-ascorbic acid to be used as a redox polymerization initiator.
  • the amount of the azo compound used relative to the whole polymerization initiator may be 10 to 100 mol%, more preferably 25 to 90 mol%, from the viewpoint of improving water absorption performance. 30 to 85 mol% is more preferable, and 35 to 80 mol% is still more preferable.
  • the total amount of the polymerization initiator used is 0.005 to 100 mol of the water-soluble ethylenically unsaturated monomer used for the polymerization from the viewpoint of avoiding a rapid polymerization reaction and shortening the polymerization reaction time. 1 mol is preferable, 0.01 to 0.5 mol is more preferable, 0.0125 to 0.1 mol is further preferable, and 0.015 to 0.05 mol is still more preferable.
  • the polymerization temperature varies depending on the polymerization initiator used, and cannot be determined unconditionally. However, the polymerization proceeds rapidly and the polymerization time is shortened to increase productivity and more easily remove the heat of polymerization. From the viewpoint of smoothly reacting, 0 to 130 ° C is preferable, and 10 to 110 ° C is more preferable.
  • the polymerization time is appropriately set according to the type and amount of the polymerization initiator used, the reaction temperature, etc., but is preferably 1 to 200 minutes, more preferably 5 to 100 minutes.
  • the crosslinked polymer obtained by polymerizing a water-soluble ethylenically unsaturated monomer is in the state of a hydrous gel.
  • the water content of the water-containing gel of the crosslinked polymer is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, and still more preferably 50 to 70% by mass from the viewpoint that the crushing step can be easily performed.
  • the water content is adjusted by the amount of water in the aqueous monomer solution or by operations such as drying and humidification after polymerization.
  • the water content of the hydrated gel polymer represents the content of water in mass% relative to the total mass of the hydrated gel polymer.
  • the method for producing a water-absorbent resin of the present invention includes a crushing step for a hydrogel of a crosslinked polymer.
  • the size of the hydrogel after the roughing treatment is, for example, preferably about 0.1 to 10 mm, more preferably about 0.1 to 5 mm.
  • the size means the maximum size per hydrogel.
  • the temperature of the hydrogel in the crushing step is 35 ° C. or less, preferably 33 ° C. or less, more preferably 30 ° C. or less, and further preferably 25 ° C. or less.
  • the temperature of the hydrogel in the crushing step may be 0 ° C. or higher, for example, 5 ° C. or higher, preferably 10 ° C. or higher, more preferably 15 ° C. or higher.
  • the temperature of the hydrogel in the crushing step is within the above range, it may vary during the crushing step, and the temperature range in the case of variation is, for example, within ⁇ 10 ° C., preferably within a predetermined temperature. Within plus or minus 5 ° C, more preferably within plus or minus 3 ° C.
  • a method for adjusting the temperature of the hydrogel to the above temperature a method of allowing the high temperature hydrogel to stand for a predetermined time, a method of bringing the hydrogel into contact with a low temperature gas for a predetermined time, and a container holding the hydrogel to a refrigerant bath or the like
  • the method etc. which adjust to the said temperature by immersing for predetermined time are mentioned.
  • the water-containing gel after polymerization is at a high temperature, so that it is preferable that temperature adjustment is achieved by cooling.
  • a crushing apparatus such as a kneader (for example, a pressure kneader, a double-arm kneader, etc.), a meat chopper, a cutter mill, a pharma mill, or the like can be used. Of these, a double-arm kneader, a meat chopper, and a cutter mill are more preferable.
  • the crushing apparatus may be of the same type as the crushing apparatus for dried hydrogels described below.
  • the method for producing a water-absorbent resin of the present invention includes a drying step of drying the hydrated gel coarse product obtained in the roughing step. By removing the solvent containing water in the coarsely crushed material by heating or blowing, the crushed material is dried.
  • the solvent may be removed from the hydrogel by a general method such as natural drying, heat drying, spray drying, freeze drying and the like. Drying can be performed under normal pressure, under reduced pressure, or in an air stream such as nitrogen in order to increase drying efficiency, and these methods may be used in combination.
  • the drying temperature is preferably 70 to 250 ° C., more preferably 80 to 200 ° C.
  • the drying step is performed until the water content of the crosslinked polymer is 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less.
  • the method for producing the water absorbent resin of the present invention includes a pulverization step of pulverizing the dried product obtained in the drying step to obtain a pulverized product.
  • a known pulverizer can be used for the pulverization of the dried product.
  • a roller mill roll mill
  • stamp mill stamp mill
  • jet mill a high-speed rotary pulverizer
  • high-speed rotary pulverizer hammer mill, pin mill, rotor beater mill, etc.
  • container drive A mold mill (rotary mill, vibration mill, planetary mill, etc.)
  • a high speed rotary pulverizer is used.
  • the pulverizer may have an opening for controlling the maximum particle size of the pulverized particles, such as a perforated plate, a screen, and a grid, on the outlet side.
  • the shape of the opening may be polygonal or circular, and the maximum diameter of the opening may be 0.1 to 5 mm, preferably 0.3 to 3.0 mm, more preferably 0.5 to 1.5 mm. preferable.
  • the production method of the present invention may further include other steps such as a classification step for adjusting the particle size, a surface crosslinking step, and the like.
  • the method for producing a water absorbent resin of the present invention may include a classification step of classifying the pulverized product obtained in the pulverization step.
  • classification steps such as pulverizing the classified particles again and repeating the pulverization step and the classification step, or there may be a classification step after the surface cross-linking step described later.
  • classification means an operation of dividing a certain particle group into two or more particle groups having different particle size distributions depending on the particle size.
  • a known classification method can be used for the classification of the pulverized product.
  • screen classification air classification, or the like may be used, and screen classification is preferable.
  • the screen classification include a vibration sieve, a rotary shifter, a cylindrical stirring sieve, a blower shifter, and a low-tap shaker.
  • Screen classification is a method of classifying particles on the screen into particles that pass through the screen mesh and particles that do not pass through by vibrating the screen.
  • Wind classification refers to a method of classifying particles using air flow.
  • 90% or more of the total weight of the water absorbent resin is preferably 850 ⁇ m or less, more preferably 700 ⁇ m or less, and even more preferably 600 ⁇ m or less.
  • the particle diameter means a value measured by a sieving method.
  • the water-absorbent resin preferably has a median particle size of 100 to 800 ⁇ m, more preferably 150 to 600 ⁇ m, further preferably 200 to 500 ⁇ m, and more preferably 240 to 450 ⁇ m. Even more preferred.
  • the median particle size is measured according to the method described in the examples below.
  • the production method of the present invention can obtain a pulverized product having a desired particle size distribution with good reproducibility even when the number of times of pulverizing the dried product is small or when the pulverization time of the dried product is short. Is advantageous. Further, by reducing the number or time of grinding, it is possible to avoid deterioration of the performance of the water-absorbent resin due to exposure to a mechanical load for a long time.
  • a crosslinking agent (referred to as a surface crosslinking agent) further containing two or more functional groups having reactivity with a functional group derived from a water-soluble ethylenically unsaturated monomer. .) May be added and reacted (referred to as surface cross-linking treatment).
  • surface cross-linking treatment By adding a surface cross-linking agent and performing surface cross-linking treatment, the cross-linking density near the surface of the water-absorbent resin is increased, so that the water-absorbing performance, gel strength or liquid permeability of the water-absorbent resin obtained is improved. be able to.
  • the surface cross-linking agent may be added at any time after the coarse crushing step.
  • the crosslinked polymer hydrogel, the hydrolyzed gel of the crosslinked polymer, the dried crude product, or the dried product is pulverized. In particular, it can be carried out on a dry product of a coarsely crushed product or a pulverized product of a dried product.
  • the method for adding the surface cross-linking agent for example, the surface cross-linking agent solution may be added to the water-absorbing resin, or the surface cross-linking agent solution may be spray-added to the water-absorbing resin.
  • the surface cross-linking agent is preferably added as a surface cross-linking agent solution by dissolving the surface cross-linking agent in a solvent such as water or / and alcohol.
  • the surface cross-linking step may be performed once or divided into two or more times.
  • the surface cross-linking agent examples include compounds having two or more reactive functional groups.
  • polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, polyglycerin; (poly) ethylene glycol diglycidyl ether, (poly) Polyglycidyl compounds such as ethylene glycol triglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, (poly) glycerol polyglycidyl ether; epichlorohydrin, epibromohydrin Haloepoxy compounds such as ⁇ -methylepichlorohydrin; 2,4-tolylene diisocyanate, hexamethylene diisocyanate and
  • polyethylene glycol diglycidyl ether (poly) ethylene glycol triglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, (poly) Polyglycidyl compounds such as glycerol polyglycidyl ether and / or polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, polyoxyethylene glycol, polyoxypropylene glycol are preferred, and polyglycidyl compounds are more preferred. preferable.
  • These surface crosslinking agents may be used alone or in combination of two or more. For example, a polyglycidyl compound and polyols may be used in combination.
  • the addition amount of the surface cross-linking agent is preferably 0 with respect to 100 mol of the total amount of the water-soluble ethylenically unsaturated monomer used for polymerization, from the viewpoint of appropriately increasing the cross-linking density in the vicinity of the surface of the water-absorbent resin. 0.0001 to 1 mol, more preferably 0.001 to 0.5 mol.
  • the surface cross-linking step is preferably performed in the presence of water in the range of 1 to 200 parts by mass with respect to 100 parts by mass of the water-soluble ethylenically unsaturated monomer.
  • the amount of water can be adjusted appropriately by using water or / and a water-soluble organic solvent such as alcohol.
  • the solid content of the water-absorbent resin in the hydrogel can be calculated from the amount of the water-soluble ethylenically unsaturated monomer used in the polymerization reaction, and the water content contained in the aqueous monomer solution can be calculated at the same time.
  • the amount of water contained in the water-containing gel in each step after the water-containing gel production step can be calculated by subtracting the amount of water removed from the water-containing gel after polymerization from the amount of water contained in the monomer aqueous solution.
  • the amount of water during the surface cross-linking step cross-linking in the vicinity of the particle surface of the water-absorbent resin can be more suitably performed.
  • the treatment temperature of the surface crosslinking agent is appropriately set according to the surface crosslinking agent to be used, and may be 20 to 250 ° C.
  • the treatment time is preferably 1 to 200 minutes, more preferably 5 to 100 minutes.
  • the water content of the water-containing gel of the crosslinked polymer in each example and comparative example was evaluated by the following method.
  • a JIS standard sieve was combined in the order of a sieve having an opening of 850 ⁇ m, a sieve having an opening of 500 ⁇ m, a sieve having an opening of 250 ⁇ m, a sieve having an opening of 180 ⁇ m, a sieve having an opening of 150 ⁇ m, and a tray.
  • the mass of the water-absorbent resin remaining on each sieve was calculated as a mass percentage with respect to the total amount to obtain the particle size distribution.
  • the relationship between the sieve aperture and the accumulated mass percentage of the water absorbent resin remaining on the sieve is logarithmic probability paper. Plotted. By connecting the plots on the probability paper with a straight line, the particle size corresponding to an integrated mass percentage of 50% by mass was defined as the median particle size.
  • Example 1 A 2 L separable flask was charged with 195.36 g of 100% acrylic acid. While stirring the inside of the separable flask, 135.13 g of ion-exchanged water was added, and 357.93 g of 30% sodium hydroxide was further added dropwise in an ice bath. Thereafter, 104.73 g of 100% acrylic acid was added to prepare a partially neutralized acrylic acid solution.
  • aqueous monomer solution In a 2 L plastic bottle, 780 g of the above-mentioned partially neutralized acrylic acid solution, 43.78 g of an aqueous 2% polyethylene glycol diacrylate (average repeating unit of ethylene oxide: 9) solution as an internal crosslinking agent solution, 180.7 g of ion-exchanged water, Were mixed to prepare an aqueous monomer solution.
  • This monomer aqueous solution was charged into a stainless steel circular vat (inner diameter 200 mm, depth 60 mm), sealed with a film from the top, and then blown with nitrogen to make dissolved oxygen in the solution 0.1 ppm or less. Subsequently, the temperature of the monomer aqueous solution was adjusted to 18 ° C.
  • thermometer was inserted into the water-containing gel taken out from the vat, and left still in a room at 23 ° C. for 50 minutes to adjust to a predetermined temperature (30 ° C.).
  • the water content of the water-containing gel of the crosslinked polymer after cooling was 63%.
  • the water-containing gel of the crosslinked polymer was crushed with a 1 L double arm kneader and then dried at 180 ° C. for 30 minutes to obtain a dried product. Thereafter, the dried product was pulverized with a screen hole size of 1 mm using a pulverizer (rotor beater mill).
  • Example 2 In the same manner as in Example 1, a crosslinked polymer hydrogel was obtained. The resulting crosslinked polymer hydrogel was allowed to stand in a 23 ° C. room for 50 minutes, and then left on an ice-water bath for 5 minutes to adjust to a predetermined temperature (20 ° C.). The water content of the water-containing gel of the crosslinked polymer after cooling was 63%. Thereafter, as in Example 1, coarse crushing, drying and crushing were performed. After the pulverization, the pulverized product of 850 ⁇ m or more and the pulverized product of less than 150 ⁇ m were removed to obtain a water absorbent resin (2) having a median particle size of 250 ⁇ m. The same operation as described above was performed 5 times, and the average of the particle size distribution and the coefficient of variation CV for each sieve of the water absorbent resin (2) were obtained. The results are shown in Tables 1 and 2.
  • Example 1 In the same manner as in Example 1, a crosslinked polymer hydrogel was obtained. The obtained crosslinked polymer hydrogel was allowed to stand in a room at 23 ° C. for 1 minute and adjusted to a predetermined temperature (70 ° C.). The water content of the water-containing gel of the crosslinked polymer after cooling was 64%. Thereafter, as in Example 1, coarse crushing, drying and crushing were performed. After pulverization, a pulverized product of 850 ⁇ m or more and a pulverized product of less than 150 ⁇ m were removed to obtain a comparative water absorbent resin (1) having a median particle size of 330 ⁇ m. The same operation as described above was performed 5 times, and the average particle size distribution and the coefficient of variation CV for each sieve of the comparative water absorbent resin (1) were obtained. The results are shown in Tables 1 and 2.
  • Example 2 In the same manner as in Example 1, a crosslinked polymer hydrogel was obtained. The obtained crosslinked polymer hydrogel was allowed to stand in a room at 23 ° C. for 20 minutes and adjusted to a predetermined temperature (45 ° C.). The water content of the water-containing gel of the crosslinked polymer after cooling was 64%. Thereafter, as in Example 1, coarse crushing, drying and crushing were performed. After pulverization, a pulverized product of 850 ⁇ m or more and a pulverized product of less than 150 ⁇ m were removed to obtain a comparative water absorbent resin (2) having a median particle size of 250 ⁇ m. The same operation as described above was performed 5 times, and the average of the particle size distribution and the coefficient of variation CV for each sieve of the comparative water absorbent resin (2) were obtained. The results are shown in Tables 1 and 2.
  • sanitary materials such as paper diapers and sanitary products
  • agricultural and horticultural materials such as water retention agents and soil conditioners
  • industrial materials such as water-stopping agents and anti-condensation agents.

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  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)

Abstract

L'invention concerne un procédé de fabrication de résine absorbant l'eau qui inclut une étape de broyage au cours de laquelle un gel aqueux d'un polymère réticulé est broyé, la température dudit gel aqueux lors de l'étape de broyage étant inférieure ou égale à 35°C. Une résine absorbant l'eau obtenue à l'aide de ce procédé présente une reproductibilité améliorée de répartition granulométrique.
PCT/JP2018/011453 2017-03-24 2018-03-22 Procédé de fabrication de résine absorbant l'eau WO2018174175A1 (fr)

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WO2021246243A1 (fr) * 2020-06-04 2021-12-09 住友精化株式会社 Procédé de production de particules polymères réticulées et procédé de production de particules de résine absorbant l'eau
WO2022024787A1 (fr) * 2020-07-28 2022-02-03 住友精化株式会社 Procédé de production de particules de résine absorbant l'eau
WO2022071503A1 (fr) * 2020-10-02 2022-04-07 住友精化株式会社 Procédé de fabrication de particules de polymère réticulé
WO2022265466A1 (fr) * 2021-06-18 2022-12-22 주식회사 엘지화학 Procédé de préparation d'un polymère superabsorbant

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WO2021246243A1 (fr) * 2020-06-04 2021-12-09 住友精化株式会社 Procédé de production de particules polymères réticulées et procédé de production de particules de résine absorbant l'eau
WO2022024787A1 (fr) * 2020-07-28 2022-02-03 住友精化株式会社 Procédé de production de particules de résine absorbant l'eau
WO2022071503A1 (fr) * 2020-10-02 2022-04-07 住友精化株式会社 Procédé de fabrication de particules de polymère réticulé
WO2022265466A1 (fr) * 2021-06-18 2022-12-22 주식회사 엘지화학 Procédé de préparation d'un polymère superabsorbant

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