WO2018117413A1 - Superabsorbent polymer and method for producing same - Google Patents

Abstract

The present invention relates to a superabsorbent polymer and a method for producing the same. According to the method for producing a superabsorbent polymer of the present invention, a superabsorbent polymer having an improved absorption capacity and permeability can be produced.

Description

 [Name of invention]

 Super Absorbent Resin and Method for Making the Same

Technical Field

 Reciprocal Citation with Related Application (s)

 This application claims the benefit of priority based on Korean Patent Application No. 10-2016-0174935 of December 20, 2016 and Korean Patent Application No. 10-2017-0146287 of January 3, 2017, the corresponding Korean patent All content disclosed in the literature of the applications is included as part of this specification.

 The present invention relates to a super absorbent polymer and a method for producing the same. More specifically, the present invention relates to a super absorbent polymer having improved water absorption and transmittance, and a method for preparing the same.

[Technique to become background of invention]

 Super Absorbent Polymer (SAP) is from 500 to 500

It is a synthetic polymer material that can absorb up to 1,000 times of water, and each developer names it with different names such as SAM (Super Absorbency Material) and AGM (Absorbent Gel Material). Such super absorbent polymers have been put into practical use as physiological tools, and are currently used in gardening soil repair agents, civil engineering, building index materials, seedling sheets, food fresheners in addition to sanitary products such as paper diapers for children, and It is widely used as a material for steaming.

 As a method for producing such a super absorbent polymer, a method by reverse phase suspension polymerization or a method by aqueous solution polymerization is known. Reverse phase suspension polymerization is disclosed, for example, in Japanese Patent Laid-Open Nos. 56-161408, 57-158209, and 57-198714. As a method of aqueous solution polymerization, a thermal polymerization method is carried out in a kneader having a plurality of shafts while breaking and angled, and a photopolymerization method in which a high concentration aqueous solution is irradiated with ultraviolet rays on a belt to perform polymerization and drying at the same time. Etc. are known.

 The hydrous gel polymer obtained through the polymerization reaction as described above is generally

article It is ground through a drying process and marketed as a powder product.

 Permeability in products using superabsorbent polymers is a measure of the fluidity of the liquid to be absorbed. Permeability may vary depending on the characteristics of the particle size distribution of the crosslinked resin, the particle shape and the connectivity of the openings between the particles, the surface modification of the swollen gel, and the like. The fluidity of the liquid passing through the swollen particles depends on the permeability of the super absorbent polymer composition. When the permeability is low, the liquid cannot easily flow through the super absorbent polymer composition.

 One method of increasing permeability in superabsorbent polymers is to perform surface crosslinking reaction after polymerization of the resin, in which silica or clay is added together with the surface crosslinking agent. For example, US Pat. Nos. 5,140,076 and C. 4,734,478 disclose the addition of silica during surface crosslinking of dry superabsorbent resin powders.

 However, as the silica or the clay is added, the permeability is improved, but in proportion thereto, there is a problem in that the water holding capacity or the pressure absorbing capacity is deteriorated and it is easy to be separated from the super absorbent polymer by external physical impact during movement.

[Content of invention]

 [Problem to solve]

 In order to solve the problems of the prior art as described above, an object of the present invention is to provide a method for preparing a super absorbent polymer having improved absorption and transmittance by adding a C6 or more aliphatic alcohol during surface crosslinking.

[Measures of problem]

 In order to achieve the above object, according to an aspect of the present invention, a hydrogel polymer by thermally polymerizing or photopolymerizing a monomer composition including an acrylic acid monomer having a acidic group and at least a portion of the acidic group is neutralized and a polymerization initiator Forming a;

 Drying the hydrogel polymer;

Pulverizing the dried polymer; Mixing a surface crosslinker and a C6 or higher aliphatic alcohol in the ground polymer; And

 It provides a method for producing a super absorbent polymer comprising the step of performing a surface modification by heating the polymer mixed with the surface cross-linking agent and C6 or more aliphatic alcohol.

 According to another aspect of the present invention,

 A crosslinked polymer obtained by polymerizing and internally crosslinking a monomer composition having an acidic group and containing an acrylic acid monomer in which at least a portion of the acidic group is neutralized; And a super absorbent polymer comprising a surface modification layer formed on the surface of the crosslinked polymer,

 The centrifugal water holding capacity (CRC) measured according to the EDANA method WSP 241.3 is 25 to 35 g / g, the pressure absorption capacity (AUL) of 0.7 psi measured according to the EDANA method WSP 242.3 is 20 to 30 g / g, It provides a super absorbent polymer having a surface tension of 65 to 73 mN / m.

【Effects of the Invention】

 According to the manufacturing method of the super absorbent polymer of the present invention, by adding a C6 or more aliphatic alcohol during the surface crosslinking process, the superabsorbent polymer having improved water absorption and permeability can be prepared by modifying the surface of the super absorbent polymer.

[Specific contents to carry out invention]

 As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Hereinafter, a super absorbent polymer and a method for preparing the same according to an embodiment of the present invention will be described in detail. The method for producing a super absorbent polymer of the present invention has an acid group and is Forming a hydrogel polymer by thermally polymerizing or photopolymerizing a monomer composition comprising at least a portion of an acidic group neutralized with an acrylic acid monomer and a polymerization initiator; Drying the hydrogel polymer; Pulverizing the dried polymer; Mixing a ground crosslinker and a C6 or higher aliphatic alcohol of a core-shell structure in the pulverized polymer; And heating the polymer in which the surface crosslinking agent and the C6 or higher aliphatic alcohol are mixed to perform surface modification.

 In the method for producing a super absorbent polymer of the present invention, the monomer composition which is a raw material of the super absorbent polymer has an acidic group and includes at least partly weighted acrylic acid monomer and a polymerization initiator of the acidic group.

 The acrylic acid monomer is a compound represented by the following formula (1):

[Formula 1]

R'-COO ¹

 In Chemical Formula 1,

R ¹ is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond,

M ¹ is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt. Preferably, the acrylic acid monomer includes at least one member selected from the group consisting of acrylic acid, methacrylic acid and monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof.

Here, the acrylic acid monomer may have an acid group and at least a part of the acid group may be neutralized. Preferably, those which have been partially neutralized with alkyl materials such as sodium hydroxide, potassium hydroxide, ammonium hydroxide and the like can be used. In this case, the neutralization degree of the acrylic acid-based monomer may be 40 to 95 mole _^0/0, or 40 to 80 mole _^0/0, or 45 to 75 mole _^0/0. The range of neutralization can be adjusted according to the final physical properties. However, if the degree of neutralization is too high, the neutralized monomer is precipitated and the polymerization proceeds smoothly. On the contrary, if the degree of neutralization is too low, the absorbency of the polymer may not only be greatly reduced, but may exhibit properties such as ^' elastic rubber ^{', which is} difficult to handle.

The concentration of the acrylic acid monomer is a raw material of the super absorbent polymer. And consider, such as from about 20 to about 60 weight _^0/0, preferably, may be about 40 to about 50 weight _^0/0, the polymerization time and banung conditions for monomer composition comprising a solvent may be an appropriate concentration . However, when the concentration of the monomer is too low, the yield of the superabsorbent polymer may be low and there may be a problem in economics. On the contrary, when the concentration is too high, a part of the monomer may be precipitated or the grinding efficiency of the polymerized hydrogel polymer may be low. Etc. may cause problems in the process and may decrease the physical properties of the super absorbent polymer.

 The polymerization initiator used in the polymerization in the method for producing a super absorbent polymer of the present invention is not particularly limited as long as it is generally used for producing the super absorbent polymer.

 Specifically, the polymerization initiator may use a thermal polymerization initiator or a photopolymerization initiator according to UV irradiation depending on the polymerization method. However, even with the photopolymerization method, since a certain amount of heat is generated by irradiation of ultraviolet radiation and some heat is generated in accordance with the progress of the polymerization reaction, which is an exothermic reaction, it may further include a thermal polymerization initiator.

 The photopolymerization initiator may be used without any limitation as long as it is a compound capable of forming radicals by light such as ultraviolet rays.

 Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, and benzyl dimethyl ketal. Ketal, acyl phosphine and alpha-amhwketone — one from the group — could be used. On the other hand, as a specific example of acylphosphine, a commercially available lucirin TPO, that is, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide can be used. . A wider variety of photoinitiators are well described in Reinhold Schwalm's book 'UV Coatings: Basics, Recent Developments and New Application' (Elsevier 2007) pi 15, but are not limited to the examples described above.

The photopolymerization initiator may be included in a concentration of from about 0.01 to about 1.0 weight _^0/0 for singgi monomer composition. The concentration of this photopolymerization initiator When too low, the polymerization rate may be slow, and when the concentration of the photopolymerization initiator is too high, the molecular weight of the superabsorbent polymer may be low and the physical properties may be uneven.

In addition, the thermal polymerization initiator may be used at least one selected from the group consisting of persulfate initiator, azo initiator, hydrogen peroxide and ascorbic acid. Specifically, examples of persulfate-based initiators include sodium persulfate (Na ₂ S ₂ 0 ₈ ), potassium persulfate (K ₂ S ₂ 0 ₈ ), and ammonium persulfate (NH ₄ ). ₂ S ₂ 0 ₈ ), and examples of azo initiators include 2, 2-azobis- (2-amidinopropane) dihydrochloride, 2, 2-azobis (2-amidinopropane) dihydrochloride, 2 2,2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride), 2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride

(Carbamoylazo) isobutyronitrile (2- (carbamoylazo) isobutylonitril), 2,2-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (2,2-azobis [ 2- (2-imidazolin-2-yl) propane] dihydrochloride), 4,4-azobis- (4-cyanovaleric acid) (4,4- azobis- (4-cyanovaleric acid)), and the like. More various thermal polymerization initiators are well specified in Odian's Principle of Polymerization (Wiley, 1981), p203, and are not limited to the examples described above.

 The thermal polymerization initiator may be included in a concentration of about 0.001 to about 0.5% by weight based on the monomer composition. When the concentration of the thermal polymerization initiator is too low, additional thermal polymerization hardly occurs, and the effect of the addition of the thermal polymerization initiator may be insignificant. When the concentration of the thermal polymerization initiator is too high, the molecular weight of the superabsorbent polymer may be small and the physical properties may be uneven. Can be.

 According to an embodiment of the present invention, the monomer composition may further include an internal gauze as a raw material of the super absorbent polymer. Examples of the internal crosslinking agent include a crosslinking agent having one or more ethylenically unsaturated groups while having at least one functional group capable of reacting with the acrylic acid monomer; Or the crosslinking agent which has a 2 or more functional group which can react with the substituent formed by the substituent of the said acrylic acid type monomer, and / or hydrolysis of a monomer can be used.

6 sets Specific examples of the internal crosslinking agent include Ν, Ν'-methylenebisacrylamide, trimethyl propane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, propylene glycol di (meth) Acrylate, polypropylene glycol (meth) acrylate, butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, nucleic acid diol di (meth) ) Acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri (meth) acrylate Pentaeryes, tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, At least one member selected from the ropil glycol, the group consisting of glycerin, and ethylene carbonate may be used.

These internal cross-linking agent is included at a concentration of about 0.01 to about 0.5 _^0/0 with respect to the monomer composition, it is possible to cross-link the polymerized polymer.

 In the production method of the present invention, the monomer composition of the super absorbent polymer may further include additives such as thickeners, plasticizers, storage stabilizers, antioxidants and the like as necessary.

 Raw materials such as acrylic acid monomers, photopolymerization initiators, thermal polymerization initiators, internal crosslinking agents, and additives having an acidic group and neutralized at least a portion of the acidic groups may be prepared in the form of a monomer composition solution dissolved in a solvent.

The solvent that can be used at this time can be used without limitation of the composition as long as it can dissolve the above-mentioned components, for example, water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanedi , Propylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclonucleanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene Glycol ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate and Ν, Ν-dimethylacetamide It can be used in combination of one or more selected from.

 The solvent may be included in the remaining amount except for the above-described components with respect to the total content of the monomer composition.

 On the other hand, if the method of forming a hydrogel polymer by thermally polymerizing or photopolymerizing such a monomer composition is also the polymerization method normally used, there will be no restriction | limiting in particular in a structure.

 Specifically, the polymerization method is largely divided into thermal polymerization and photopolymerization according to the polymerization energy source, when the thermal polymerization is usually carried out, it can be carried out in a semi-unggi with a stirring shaft such as kneader, when the polymerization proceeds, Although possible to proceed in a reactor with a conveyor belt, the above-described polymerization method is an example, and the present invention is not limited to the above-described polymerization method.

 For example, as described above, the hydrogel polymer obtained by thermal polymerization by supplying hot air or by heating the reaction machine may have a semi-unger, such as a kneader having a stirring shaft. The hydrogel polymer discharged to the mandrel outlet may be in the form of several centimeters to several millimeters. Specifically, the size of the water-containing gel polymer obtained may vary depending on the concentration and the injection rate of the monomer composition to be injected, a water-containing gel polymer having a weight average particle diameter of 2 to 50 mm can be obtained.

 In addition, when the photopolymerization is performed in a semi-unggi equipped with a movable conveyor belt as described above, the form of the hydrogel polymer generally obtained may be a hydrogel gel polymer on the sheet having a width of the belt. The monomer composition is then fed so as to obtain a polymer on a sheet having a thickness of about 0.5 to about 5 cm, which depends on the ancestors, the concentration of the monomer and the concentration and the rate of injection. It is desirable to. In the case of supplying the monomer composition to such an extent that the thickness of the polymer on the sheet is too thin, it is not preferable because the production efficiency is low, and when the thickness of the polymer on the sheet exceeds 5 cm, the polymerization reaction does not occur evenly over the entire thickness. You may not.

The normal water content of the gel-like function, the polymer obtained in this manner can be about 40 to about 80 wt. _^0/0. On the other hand, in the present specification, "water content"'

8 sets The content of water to the total weight of the hydrogel polymer is the weight of the hydrogel polymer, minus the weight of the dried polymer. Specifically, it is defined as a value calculated by measuring the weight loss due to moisture evaporation in the polymer in the process of raising the temperature of the polymer through infrared heating and drying. At this time, the drying condition is to increase the temperature to about 180 ^° C at room temperature and then maintained at 180 ^° C. The total drying time is set to 20 minutes, including 5 minutes of temperature rise step, the moisture content is measured.

 Next, the step of drying the obtained hydrogel polymer is performed.

 At this time, if necessary to coarse grinding before drying to increase the efficiency of the drying step may be more rough.

 At this time, the pulverizer used is not limited in configuration, specifically, a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, a cutting machine Includes any one selected from the group of grinding machines consisting of cutter mills, disc mills, shred crushers, crushers, choppers and disc cutters Although it is possible, it is not limited to the above-mentioned example. At this time, the grinding step may be pulverized so that the particle size of the hydrogel polymer is about 2 to about 10mm.

 Grinding to a particle diameter of less than 2 mm is not technically easy due to the high water content of the hydrogel polymer, and may also cause a phenomenon in which the crushed particles cross each other. On the other hand, when the particle size is pulverized in excess of 10mm, the effect of increasing the efficiency of the subsequent drying step is insignificant.

Drying is performed on the hydrous gel polymer immediately after the polymerization as described above or after the black has not undergone the grinding step. At this time, the drying temperature of the drying step may be about 150 to about 250 ^° C. If the drying temperature is less than 150 ^° C., the drying time is too long and there is a fear that the physical properties of the superabsorbent resin to be formed is lowered, if the drying temperature exceeds 250 ^° C, only the polymer surface is dried too much, Fine powder may generate | occur | produce in the grinding | pulverization process made and there exists a possibility that the physical property of the superabsorbent polymer formed finally may fall. Thus preferably the drying is ^at a temperature of about 150 to about 200 ^° C, more

9 Article 26 Preferably at a temperature of about 160 to about 180 ^° C.

 On the other hand, in the case of drying time, in consideration of the process efficiency, it may proceed for about 20 to about 90 minutes, but is not limited thereto.

 If the drying method of the drying step is also commonly used as a drying step of the hydrogel polymer, it can be selected and used without limitation of the configuration. Specifically, the drying step may be performed by a method such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation. The water content of the polymer after such a drying step may be about 0.1 to about 10% by weight.

 Next, the step of pulverizing the dried polymer obtained through this drying step is carried out.

 The polymer powder obtained after the grinding step may have a particle diameter of about 150 to about 850. Mills used to grind to such particle diameters are specifically pin mills, hammer mills, screw mills, mills, disc mills or jogs. Although a jog mill or the like may be used, the present invention is not limited to the above-described example.

 In addition, in order to manage the physical properties of the super absorbent polymer powder to be finalized after such a grinding step, a separate process of classifying the polymer powder obtained after grinding according to the particle diameter may be performed. Preferably, a polymer having a particle size of about 150 to about 850 may be classified, and only a polymer powder having such a particle size may be manufactured through a surface modification step.

 Next, the ground polymer is added to the ground polymer by adding a surface cross-linking agent and a C6 or higher aliphatic alcohol. Perform a surface modification step for.

 The surface modification is a step of inducing a crosslinking reaction on the surface of the pulverized polymer in the presence of a surface crosslinking agent, thereby forming a super absorbent polymer having more improved physical properties. Through such surface modification, a surface modification layer (surface crosslinked layer) is formed on the surface of the pulverized polymer particles.

 The surface modification may be carried out by a conventional method of increasing the crosslinking density of the surface of a polymer particle, for example, by mixing and crosslinking the pulverized polymer with a solution containing a surface crosslinking agent.

10 26 sets Can be performed.

 Also, in general, the surface crosslinking agent is applied to the surface of the super absorbent polymer particles. Thus, this reaction occurs on the surface of the superabsorbent resin particles, which improves the crosslinkability on the surface of the particles without substantially affecting the interior of the particles. The surface crosslinked superabsorbent resin particles thus have a higher degree of crosslinking in the vicinity of the surface than in the interior. On the other hand, in order to increase the permeability of the super absorbent polymer in the prior art, a method of adding porous silica or clay to the surface crosslinking agent was used. However, since silica and clay have a porosity, the permeability is improved by adding them, but in proportion thereto, the water retention capacity or the pressure absorption capacity is deteriorated, and the superabsorbent polymer is not firmly bonded to the superabsorbent polymer. There is a problem that is easy to separate from the resin.

 However, in the production method of the present invention, by adding C6, that is, aliphatic alcohol having 6 or more carbon atoms, together with the surface crosslinking agent, the surface crosslinking reaction may be performed to obtain an effect of improving permeability without deterioration of water holding capacity or pressure absorbing ability.

 The hydroxyl group (-OH) of the C6 or higher aliphatic alcohol reacts chemically with the surface of the ground polymer and the C6 or higher alkyl chain is present on the surface of the polymer. Accordingly, when the superabsorbent polymer product is made of a polymer having C6 or more aliphatic alcohol bonded to the surface, when the superfine ZL high-absorbent water is absorbed by water-absorbing water, Due to the C6 or more and the long alkyl chain present on the surface, the hoeed resin particles can be prevented from agglomerating or agglomerating with each other under high pressure, and thus have improved permeability. In addition, the alkyl chains impart hydrophobicity to the polymer surface, making it easier to permeate and diffuse moisture.

According to one embodiment of the present invention, the C6 or higher aliphatic alcohols include C6 to C20 primary, secondary, or tertiary alcohols, and preferably C6 to C16 primary alcohols. More preferably stearyl alcohol, lauryl alcohol, And cetyl alcohol (cetyl alcohol) may be used one or more selected from the group consisting of, but the present invention is not limited thereto.

 The content of the C6 or more aliphatic alcohol is about 0.001 to about 2 parts by weight, or about 0.01 to about 1 parts by weight, preferably about 0.01 to about 0.5 parts by weight, more preferably, based on 100 parts by weight of the pulverized polymer. About 05 to about 0.3 parts by weight may be used. When the content of C6 or more aliphatic alcohol is too small, the effect of improving the permeability due to the addition of C6 or more aliphatic alcohol is hardly exhibited, and when it is included too much, it can prevent water from penetrating and lead to a decrease in water-retaining ability.

 The C6 or higher aliphatic alcohol may be added separately before mixing the surface crosslinking agent with the ground polymer, or may be added together with the surface crosslinking agent.

 In addition, there is no limitation in the structure about the method of adding the said surface crosslinking agent and C6 or more aliphatic alcohol to the said pulverized polymer. The surface crosslinking agent and C6 or more aliphatic alcohol and polymer powder are mixed in a reaction tank, or the surface crosslinking agent and C6 or more aliphatic alcohol are sprayed on the polymer powder, and the polymer and the surface crosslinking agent and C6 or more aliphatic alcohol are continuously added to the mixer which is operated continuously. Supplying and mixing can be used.

 Meanwhile, since the C6 or higher aliphatic alcohol has low solubility in water, it may be dryly mixed in a powder state, or may be mixed with a polymer by spraying after melting the mixture to a temperature above the melting point.

 According to one embodiment of the present invention, when mixing the surface crosslinking agent and C6 or more aliphatic alcohol to a polymer, before mixing the surface crosslinking agent, C6 or more aliphatic alcohol in powder or liquid form must first be mixed with the polymerizer. Can be.

 When the surface crosslinking agent is added, water may be further mixed together and added in the form of a surface crosslinking solution. When water is added, there is an advantage that the surface crosslinker can be evenly dispersed in the polymer. At this time, the amount of added water is used to induce even dispersion of the surface crosslinking agent, prevent aggregation of the polymer powder, and at the same time optimize the surface penetration depth of the surface crosslinking agent.

12 sets It is preferably added at a ratio of about 1 to about 10 parts by weight, relative to 100 parts by weight.

 Moreover, as said surface crosslinking agent, if the compound which can react with the functional group which a polymer has is not limited in the structure.

 Preferably, in order to improve the properties of the resulting super absorbent polymer, the surface crosslinking agent may be a polyhydric alcohol compound; Epoxy compounds; Polyamine compounds; Haloepoxy compound; Condensation products of haloepoxy compounds; Oxazoline compounds; Mono-, di- or polyoxazolidinone compounds; Cyclic urea compounds; Polyvalent metal salts; And it may be used one or more selected from the group consisting of alkylene carbonate compounds.

 Specifically, examples of the polyhydric alcohol compound include mono-, di-, tri-, tetra- or polyethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, 2,3,4-trimethyl-1,3 -Pentanediol, polypropylene glycol, glycerol, polyglycerol, 2-butene-1,4-diol, 1,4-butanediol, 1,3-butanedi, 1,5-pentanediol, 1,6- nucleic acid One or more selected from the group consisting of diols and 1,2-cyclonucleic acid dimethanol can be used.

 In addition, ethylene glycol diglycidyl ether and glycidol may be used as the epoxy compound, and ethylene diamine, diethylene triamine, triethylene tetraamine, tetraethylene pentamine, pentaethylene nucleomine may be used as polyamine compounds. , At least one selected from the group consisting of polyethyleneimine and polyamide polyamine can be used.

As the k-rigo-haloepoxy compound, ᅳ epi—chlorohydrin, epibromohydrin— and _α -methylepichlorohydrin can be used. In addition, 2-oxazolidinone etc. can be used as a mono-, di-, or a polyoxazolidinone compound, for example.

 And as an alkylene carbonate compound, ethylene carbonate etc. can be used. These may be used alone or in combination with each other. On the other hand, in order to improve the efficiency of a surface crosslinking process, 1 or more types of C2-C10 polyhydric alcohol compounds can be used including these 1 or more types in these surface crosslinking agents.

13 Article 26 The amount of the surface crosslinking agent to be added may be appropriately selected depending on the kind of the surface crosslinking agent to be added or the reaction conditions.

About 100 parts by weight, about 0.001 to about 5 parts by weight, preferably about 0.01 to about 3 parts by weight, more preferably about 0.05 to about 2 parts by weight may be used.

 If the content of the surface crosslinking agent is too small, the surface crosslinking reaction hardly occurs, and if 100 parts by weight of the polymer exceeds 5 parts by weight, excessive phenomenon of surface crosslinking reaction may cause deterioration of absorption capacity and physical properties. .

 The superabsorbent polymer obtained according to the production method of the present invention has improved permeability by preventing the swollen resin particles from crowding with each other by distributing C6 or more aliphatic alcohol on the surface. In addition, unlike the case of adding silica or clay, the super absorbent polymer according to the manufacturing method of the present invention minimizes the deterioration of physical properties of the super absorbent polymers such as water retention and pressurized absorbent capacity, and has a relatively strong physical bond with the polymer resin, thereby impacting the movement. Due to the small number of separations, the variation of physical properties is small even during long-term transportation and storage.

About 20 to about 100 minutes, preferably about 30 to about at a temperature of about 160 to about 200 ° C, preferably about 170 to about 190 ^° C for the polymer particles to which the surface crosslinking agent and C6 or more aliphatic alcohol is added By heating for 90 minutes, the surface crosslinking reaction by the surface crosslinking agent, the binding reaction of C6 or more aliphatic alcohol, and drying can be simultaneously performed. The cross-linking reaction temperature of 160 ^° C meoman acres and the reaction time is too short, if the surface cross-linked banung does not occur because it is possible lower the transmission rate, exceeding 200 ^° C, or the banung time may experience so the beam SAT decreases when the road correctly have.

 The temperature raising means for surface crosslinking reaction is not specifically limited. It can be heated by supplying a heat medium or by directly supplying a heat source. At this time, as the type of heat medium that can be used may be a heated fluid such as steam, hot air, hot oil, etc., but the present invention is not limited thereto, and the temperature of the heat medium to be supplied is the means of the heat medium, the temperature increase rate and the temperature increase It may be appropriately selected in consideration of the target temperature. On the other hand, the heat source directly supplied is electricity

14 sets Heating, gas heating method, but the present invention is not limited to the above-described examples.

 The super absorbent polymer prepared by the manufacturing method of the present invention may have improved permeability without deteriorating physical properties such as water-retaining capacity and pressure-absorbing capacity.

 For example, in the superabsorbent polymer prepared by the above method, P defined by Equation 1 below may satisfy a range of 0.85 to 1.20.

[Equation ^1]

P = SFC * 10 ⁷ / (CRC + AUL)

 In Formula 1,

 CRC means the water capacity (unit: g / g) measured according to EDANA WSP 241.3,

 AUL stands for absorbed pressure of 0.7 psi (unit: g / g) measured according to EDANA method WSP 242.3,

SFC means solution permeability (Saline Flow Conductivity, cm ³ * sec / g).

 P of Equation 1 is a parameter for evaluating the balance of water holding capacity, pressure absorbing ability, and liquid permeability, and the closer to 1, the physical properties of the water holding capacity, pressure absorbing ability, and liquid permeability are harmonized. .

 The super absorbent polymer prepared by the production method of the present invention, wherein P calculated by the formula 1 is about 0.85 or more, or about 0.90 or more, or about 0.95 or more, and about 1.2 or less, or about 1.15 or less. Or about 1.10 or less.

 In addition, the super absorbent polymer prepared by the above method has a water retention capacity (CRC) of about 25 g / g or more, or about 26 g / g or more, or about 27 g / g or more, measured according to the EDANA method WSP 241.3. , Up to about 35 g / g, or up to about 30 g / g, or up to about 29 g / g.

In addition, the super absorbent polymer prepared by the above production method has a pressure absorption capacity (AUL) of 0.7 psi measured according to the EDANA method WSP 242.3 of about 20 g / g or more, or about 12 g / g or more, or about 24 g / at least about 30 g / g, or at most about 28 g / g, Or about 27 g / g or less.

In addition, the superabsorbent polymer prepared by the above method is about 45 * ΚΓ ⁷ cm ³ * sec / g or more, or about 48 * 10 ^"7 cm ³ * sec / g or more, or about 50 * 10 ⁷ cm ³ * about 80 * 1 (T ⁷ cm ³ * sec / g or less, or about 70 * 1 (T ⁷ cm ³ * sec / g or less, or about 65 * l (T ⁷ cm ³ * sec /) It may have a solution permeability (SFC: Saline Flow Conductivity) of less than or equal to g.

 The solution permeability is US published patent No. It can be measured according to the method disclosed in [0184] to [0189] of column 16 of 2009-0131255.

 According to another embodiment of the present invention, a crosslinked polymer having an acidic group and polymerized and internally crosslinked a monomer composition comprising an acrylic acid monomer in which at least a portion of the acidic group is neutralized; And a super absorbent polymer comprising a surface modification layer formed on the surface of the crosslinked polymer, wherein the centrifugal water retention capacity (CRC) measured according to EDANA method WSP 241.3 is 25 to 35 g / g, and measured according to EDANA method WSP 242.3. It provides a super absorbent polymer having a pressure absorption capacity (AUL) of 20 to 30 g / g and a surface tension of 65 to 73 mN / m.

 The crosslinked polymer obtained by polymerizing and internally crosslinking the monomer composition including the acidic group and the monomer composition including the acrylic acid monomer in which at least a portion of the acidic group is neutralized is the same as described above in the method for preparing the super absorbent polymer of the present invention.

 The superabsorbent resin of the present invention has improved absorption ability and permeability by adding C6 or more aliphatic alcohol to modify the surface of the superabsorbent resin in the surface crosslinking process for the crosslinked polymer.

 The hydroxyl groups of the C6 or higher aliphatic alcohols are chemically bound to the surface of the polymer and an alkyl chain of C6 or more is present on the surface of the polymer. Accordingly, when the polymer bound to the C6 or higher aliphatic alcohol absorbs moisture and swells, the swelling ¾ resin particles are swollen or aggregated with each other due to the high pressure due to the C6 or longer alkyl chain present on the polymer surface. Can be prevented to have improved transmittance.

In addition, the superabsorbent polymer of the present invention has a surface tension of 65 mN / m or more, or 67 mN / m or more, or 70 mN / m or more, and may have a range of 73 mN / m or less, or 72 mN / m or less.

The surface tension of the superabsorbent polymer is a measure for evaluating urine leakage in a diaper containing the superabsorbent polymer due to its physical properties different from the water-retaining capacity, pressure-absorbing capacity, and permeability. The surface tension swells the superabsorbent polymer in saline, and means the surface tension measured for the saline, and when the surface tension of the superabsorbent polymer is low, urine leakage is likely to occur in a diaper manufactured therein. . According to the superabsorbent polymer of the present invention, it is possible to produce a high-quality sanitary article by reducing the possibility of leakage by having an appropriate range of surface tension while maintaining a high water retention and permeability. In addition, the superabsorbent polymer of the present invention is about 45 * ΐσ ⁷ cm ³ * sec / g or more, or about 48 * 10 ^"7 cm ³ * sec / g or more, or about 50 * KT ⁷ cm ³ * sec / g or more While about 80 * 10 ^-7 cm ³ * sec / g or less, or about 70 * 10 ^-7 cm ³ * sec / g or less, or about 65 * 1 ( ⁷ cm ³ * sec / g or less) It may have Saline Flow Conductivity.

 The solution permeability is US published patent No. Of column 16 of 2009-0131255

It can be measured according to the method disclosed in [0184] to [0189].

 In addition, the super absorbent polymer of the present invention has a water retention capacity (CRC) of about 25 g / g or more, or about 26 g / g or more, or about 27 g / g or more, measured according to the EDANA method WSP 241.3, and about 35 g. up to / g, or up to about 30 g / g, or up to about 29 g / g.

 The centrifugal conservative capacity (CRC) is measured according to EDANA method WSP 241.3, which can be represented by Equation 1:

 [Equation 1]

CRC (g / g) = {[W ₂ (g)-W, (g)] AV ₀ (g)}-1

In the equation ^" 1,

W ₀ (g) is the weight of the resin (g),

W _t (g) is the device weight (g) measured after dehydration at 250G for 3 minutes using a centrifuge without using resin,

W ₂ (g) was immersed in 0.9 mass% of physiological saline at room temperature for 30 minutes, and then dehydrated at 250 G for 3 minutes using a centrifuge.

Article 26 It is the measured device weight (g).

 In addition, the superabsorbent polymer of the present invention has a pressurized absorption capacity (AUL) of 0.7 psi measured according to the EDANA method WSP 242.3 of about 20 g / g or more, or about 22 g / g or more, or about 24 g / g or more, About 30 g / g or less, or about 28 g / g or less, or about 27 g / g or less.

 The pressure absorption capacity (AUL) may be represented by the following Equation 2:

 [Equation 2]

 AUL (g / g) = [W4 (g)-W3 (g)] / W0 (g)

 In Equation 2,

 W0 (g) is the weight of resin (g),

 W3 (g) is the sum of the weight of the resin and the weight of the device capable of applying a load to the resin (g),

 W4 (g) is the sum of the weight (g) of the weight of the absorbed resin and the weight of the device capable of applying a load to the absorbent resin after hydrating the resin for 60 minutes under a load (0.7 psi).

 In addition, the super absorbent polymer of the present invention may have improved transmittance without deteriorating physical properties such as water-retaining capacity and pressure-absorbing capacity.

 For example, P of the superabsorbent polymer of the present invention can satisfy the range of 0.85 to 120 defined by the following formula (1).

 [Equation 1]

P = SFC * 10 ⁷ / (CRC + AUL)

 In the above formula -1,

 CRC means the water holding capacity (unit: g / g) measured according to EDANA method WSP 24L3,

 AUL means the absorbency under pressure of 0.7 psi (unit: g / g) measured according to EDANA method WSP 242.3,

SFC means solution permeability (Saline Flow Conductivity, cm ³ * sec / g).

 P in Equation 1 is a parameter for evaluating the balance of water retention capacity, pressure absorption capacity, and liquid permeability, and the closer to 1, the water retention capacity, pressure absorption capacity, and

18 sets It can be seen that the physical properties are in harmony with the liquidity.

 The superabsorbent polymer of the present invention has a P of about 0.85 or more, or about 0.90 or more, or about 0.95 or more, and P calculated by Equation 1 is about 1.20 or less. 1.15 or less. Or about 1.10 or less.

 As described above, the super absorbent polymer of the present invention has improved permeability due to the alkyl chain present in the surface modification layer, and does not deteriorate physical properties such as water holding capacity and pressure absorbing capacity, and there is no separation phenomenon due to impact during movement. Even less variation in physical properties appears, it is possible to have improved permeability by preventing the particles from being packed or aggregated with each other. In addition, the alkyl chain imparts hydrophobicity to the polymer surface, thereby making it easier to permeate and diffuse moisture.

 The invention is explained in more detail in the following examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

<Example>

 Preparation of Super Absorbent Resin

 Example 1

500 g of acrylic acid, 3 g of ethoxylated (15) trimethylolpropanetriacrylate, and diphenyl (2,4,6-trimethylbenzoyl) in a 3 L glass vessel equipped with a stirrer, a nitrogen injector and a thermometer After dissolving by adding 0:04 g of phosphine oxide, 896.4 g of 24.5% sodium hydroxide solution was added thereto to continuously add nitrogen to prepare a water-soluble unsaturated monomer solution. The aqueous unsaturated monomer aqueous solution was quenched to 70 ^° C. 500 g of this aqueous solution was added to a stainless steel container having a width of 250 mm, a length of 250 mm, and a height of 30 mm, followed by UV polymerization (irradiation: 10 mV / cm ² ) to perform UV polymerization for 90 seconds to obtain a hydrous gel polymer. After the obtained hydrogel polymer was pulverized to a size of 2mm * 2mm, the water content was measured, it was 40.1%.

The obtained gel-shaped resin was spread out on a stainless wire gauze having a pore size of 600 / mm3 in a thickness of about 30 mm, and in a 180 ^° C hot air oven for 30 minutes. Dried. The dry polymer thus obtained is pulverized using a grinder,

Classification was carried out to standard meshes of ASTM specifications to obtain a base resin powder having a particle size of 150 to 850 zm.

0.1 parts by weight of stearyl alcohol was dryly mixed with 100 parts by weight of the base resin powder, followed by mixing by spraying a surface crosslinking solution including 1 part by weight of ethylene carbonate, 4 parts by weight of water, and 0.02 parts by weight of silica, and mixing the mixture with a stirrer and a double jacket. Put into a container consisting of proceeded the surface crosslinking reaction at 185 ^° C for 60 minutes. Then, the surface-treated powder was classified into a standard mesh of ASTM standard to obtain a super absorbent polymer powder having a particle size of 150 to 850. Example 2

 In Example 1, a superabsorbent polymer powder was obtained in the same manner as in Example 1 except that 0.05 parts by weight of stearyl alcohol was mixed with 100 parts by weight of the base resin powder. Example 3

 Base resin was prepared in the same manner as in Example 1.

To 100 parts by weight of the base resin powder by spraying a surface crosslinking solution containing 1 part by weight of ethylene carbonate, 0.1 part by weight of stearyl alcohol, 4 parts by weight of water, 0.02 parts by weight of silica, and mixed in a container consisting of a stirrer and a double jacket The surface crosslinking reaction was performed for 60 minutes at 185 ^° C. Since surface eu-eu-cost powder processing eu ASTM standard一-the-body and to the classification standard eu network having a grain size of 850 ^u ΙΤΰ to obtain a water-absorbent resin powder. Example 4

In Example 1, a super absorbent polymer powder was obtained in the same manner as in Example 1 except that 0.1 part by weight of lauryl alcohol was dry mixed instead of 0.1 part by weight of stearyl alcohol to 100 parts by weight of the base resin powder. Example 5 In Example 1, a super absorbent polymer powder was obtained in the same manner as in Example 1, except that 0.1 part by weight of stearyl alcohol and π part of lauryl alcohol were dryly mixed together with 100 parts by weight of the base resin powder. Example 6

 In Example 1, a superabsorbent polymer powder was obtained in the same manner as in Example 1 except that 2 parts by weight of stearyl alcohol was dryly mixed with 100 parts by weight of the base resin powder. Example 7

 In Example 1, a super absorbent polymer powder was obtained in the same manner as in Example 1, except that 0.1 part by weight of cetyl alcohol was dry mixed with 100 parts by weight of base resin powder instead of stearyl alcohol ι part by weight. Comparative Example 1

 In Example 1, except that the stearyl alcohol was not mixed in the same manner as in Example 1 to obtain a super absorbent polymer powder. Comparative Example 2

 In Comparative Example 1, except that the temperature of the surface crosslinking reaction was 195 ° C. was prepared in the same manner as in Comparative Example 1 to obtain a super absorbent polymer powder. Comparative Example 3

 In Example 1, a super absorbent polymer powder was obtained in the same manner as in Example 1 except that 0.05 parts by weight of silica filler (DM30S) was dry mixed instead of stearyl alcohol.

Experimental Example

Regarding the super absorbent polymers prepared in Examples and Comparative Examples, The physical properties were evaluated in the following manner.

(1) Centrifuge Retention Capacity (CRC) Centrifuge Retention Capacity (CRC) was measured according to EDANA WSP 241.3.

Specifically, the resin Wo (g) (about 0.2g) obtained through Examples and Comparative Examples was uniformly sealed in a non-woven bag and then immersed in physiological saline (0.9% by weight) at room temperature. . After 30 minutes had elapsed, water was removed from the bag for 3 minutes under the conditions of 250 G using a centrifuge, and the mass W ₂ (g) of the bag was measured. Moreover, the mass Wg) at that time was measured after performing the same operation without using resin. Using each mass obtained, CRC (g / g) was computed according to the following formula.

 [Equation 1]

CRC (g / g) = {[W ₂ (g)-\ ν! ( ₈ )] Αν ₀ ( _§ )}-1

(2) Absorbency under Load (AUL)

 0.7 psi of pressure-absorbing capacity of each resin was measured according to the EDANA method WSP 242.3. Specifically, stainless steel is formed on the cylindrical bottom of plastic having an inner diameter of 25 mm.

400 mesh wire mesh was mounted. The piston, which is able to evenly spread the absorbent resin W ₀ (g) (0.16 g) on the wire mesh under the conditions of room temperature and 50% humidity, and has a load of 0.7 psi on it even more, is slightly smaller than the outer diameter of 25 mm The inner wall of the cylinder has no gap and the up and down movement is not disturbed. At this time, the weight W ₃ (g) of the apparatus was measured.

A 90 mm diameter and 5 mm thick glass filter was placed inside a 150 mm diameter petri dish, and physiological saline consisting of 9 wt% sodium chloride was brought to the same level as the top surface of the glass filter. One sheet of filter paper having a diameter of 90 mm was placed thereon. The measuring device was placed on the filter paper and the liquid was absorbed for 1 hour under load. After 1 hour raise the measuring device and remove its weight W ₄ (g). Measured.

 Using each mass obtained, the pressure absorption capacity (g / g) was computed according to following Formula.

 [Equation 2]

AUL (g / g) = [W ₄ (g)-W ₃ (g)] / W ₀ (g)

(3) Saline Flow Conductivity (SFC)

 Saline Flow Conductivity (SFC) is described in US published patent no. It was measured according to the method disclosed in [0184] to [0189] of column 16 of 2009-0131255.

(4) Surface tension

All procedures were conducted in a constant temperature and humidity room (temperature 23 ± 2 ^° C, relative humidity 45 ± 10%).

 150 g of physiological saline consisting of 0.9 wt% sodium chloride was placed in a 250 mL beaker and stirred with a magnetic bar. The superabsorbent polymer l.Og was added to the stirring solution, stirred for 3 minutes, the stirring was stopped, and left for at least 15 minutes to allow the swollen superabsorbent resin to settle to the bottom.

 The supernatant (the solution just below the surface) was then pipetted and transferred to another clean cup and surface tension was measured using a surface tensionmeter Kruss K11 / K100. Physical property values for the wicking room—calligraphy and comparative examples are shown in Table 1 below.

Table 1

23 trillion Example 4 27.4 24.8 50 71.44 0.96 Example 5 26.9 25.3 60 71.53 1.15 Example 6 27 25.0 60 71.53 1.06 Example 7 27.2 24.9 52 71.55 1.00 Comparative Example 1 27.1 24.0 42 71.57 0.82 Comparative Example 2 26.3 25.0 62 71.64 1.21 Comparative Example 3 26.4 24.3 85 71.34 1.68

* In Table 1, Ρ is a value calculated by Equation 1 below.

 [Equation 1]

P = SFC * 10 ⁷ / (CRC + AUL)

 Referring to Table 1, it can be seen that the super absorbent polymer prepared according to the method of the present invention as in Examples 1 to 7 exhibits excellent absorption and permeability properties.

Comparative Example 1 was not satisfactory when the C6 or more aliphatic alcohol is not used. In Comparative Example 2, the permeability was improved by increasing the surface crosslinking temperature, but the CRC was decreased. On the other hand, when the surface crosslinking reaction was carried out ^' mixing the inorganic filler as in Comparative Example 3, the permeability was improved, but both CRC and AUL were not good.

 In general, when the permeability is high, the water holding capacity and the absorbing pressure tend to be lowered. That is, when the degree of crosslinking is high and the strength of the hydrogel is high, the permeability is high. Therefore, it is difficult to simultaneously increase the water retention capacity Γ pressure absorption capacity and transmittance. However, as can be seen from the results of the above examples and comparative examples, the superabsorbent polymer prepared by the manufacturing method of the present invention can be seen that not only high water holding capacity and high pressure absorbing capacity but also high permeability. These results can be analyzed that the C6 or more aliphatic alcohol added to the surface crosslinking reaction is located on the surface of the absorbent resin to prevent the polymers from agglomerating, thereby increasing the permeability. In addition, it can be seen that the surface tension is also increased to prevent urine leakage.

Claims

[Patent Claims]

 [Claim 1]

 Forming a hydrogel polymer by thermally polymerizing or photopolymerizing a monomer composition including an acrylic acid monomer and a polymerization initiator having an acidic group and at least a portion of the acidic group neutralized;

 Drying the hydrogel polymer;

 Pulverizing the dried polymer;

 Mixing a surface crosslinker and a C6 or higher aliphatic alcohol in the pulverized polymer; And

 Method for producing a super absorbent polymer comprising the step of heating the surface cross-linking agent and C6 or more aliphatic alcohol up to the polymer mixture.

[Claim 2]

 The method of claim 1,

 The C6 or higher aliphatic alcohol comprises a C6 to C20 primary, secondary, or tertiary alcohol, a method for producing a super absorbent polymer.

[Claim 3]

 The method of claim 2,

 The C6 or higher aliphatic alcohol comprises stearyl alcohol, lauryl alcohol, and C. 1 type of subphase selected from the group consisting of cetyl alcohol.

[Claim 4]

 In that U term,

 The C6 or more aliphatic alcohol is mixed with 0.001 to 2 parts by weight with respect to 100 parts by weight of the pulverized polymer, a method for producing a super absorbent polymer. [Claim 5]

25 Alternative Sites (Article 26) The method of claim 1,

 Wherein said C6 or higher aliphatic alcohol is added separately or together with said surface crosslinking agent before mixing said surface crosslinking agent to the pulverized polymer.

[Claim 6]

 According to claim 11,

The step of performing the surface modification is carried out by heating the polymer particles to which the surface crosslinking agent and C6 or more aliphatic alcohol is added to 160 to 200 ^° C., the method of producing a super absorbent polymer.

[Claim 7]

 The method of claim 1,

 The superabsorbent polymer, P is defined by the following formula 1, the range of 0.85 to 1.20, manufacturing method of superabsorbent resin:

 [Equation 1]

P- SFC * 10 ⁷ / (CRC + AUL)

 In Formula 1,

 CRC means the water capacity (unit: g / g) measured according to EDANA WSP 241.3,

 AUL means a pressure absorbing capacity of 0.7 psi (unit: g / g) measured according to the EDANA WSP 242.3.

SFC means solution permeability (Saline Flow Conductivity, cm ³ * sec / g).

[Claim 8]

 A crosslinked polymer having an acidic group and polymerized and internally crosslinked in a monomer composition comprising an acrylic acid monomer in which at least a portion of the acidic group is neutralized; And a super absorbent polymer comprising a surface modification layer formed on the surface of the crosslinked polymer,

26 Alternative Sites (Article 26) The centrifugal water holding capacity (CRC) measured according to the EDANA method WSP 241.3 is 25 to 35 g / g, the pressure absorption capacity (AUL) of 0.7 psi measured according to the EDANA method WSP 242.3 is 20 to 30 g / g, and the surface Superabsorbent polymer having a surface tension of 65 to 73 mN / m.

[Claim 9]

 The method of claim 8,

 The surface modification layer comprises a C6 or more alkyl group, a method for producing a super absorbent polymer.

[Claim 10]

 The method of claim 8,

The super absorbent polymer has a solution permeability (SFC: Saline Flow Conductivity) of 45 * 10 ⁷ to 80 * ΐσ ⁷ cm ³ * sec / g.

【Claim 11】

 The method of claim 8,

 A superabsorbent polymer, wherein P defined by the following formula 1 is in the range of 0.85 to 1.20: [Formula 1]

P = SFC * 10 ⁷ / (CRC + AUL)

 In Formula 1,

 CRC means the water capacity (unit: g / g) measured according to the EDANA Act WSP—241: 3,

 AUL means the absorbency under pressure of 0.7 psi (unit: g / g) measured according to EDANA method WSP 242.3,

SFC means solution permeability (Saline Flow Conductivity, cm ³ * sec / g).

27 Alternative Sites (Article 26)