[One]Cross-Citation with Related Application(s)
[2]This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0172495 on December 20, 2019 and Korean Patent Application No. 10-2020-0148078 on November 6, 2020, All content disclosed in the literature is incorporated as a part of this specification.
[3]
The present invention relates to a superabsorbent polymer composition. More specifically, it relates to a superabsorbent polymer composition prepared so that aggregation between resin particles is suppressed by including an additive having a specific structure, and thus an additional pulverization process is not required after the drying process.
background
[4]
Super Absorbent Polymer (SAP) is a synthetic polymer material that can absorb water 500 to 1,000 times its own weight. Material), etc., are named differently. The superabsorbent polymer as described above began to be put to practical use as a sanitary tool, and is now widely used as a soil repair agent for horticulture, water-retaining material for civil engineering and construction, sheets for seedlings, freshness maintenance agent in the food distribution field, and materials for poultice. .
[5]
Such superabsorbent polymers are mainly used in the field of sanitary materials such as diapers and sanitary napkins. In the sanitary material, the superabsorbent polymer is generally included in a state spread in the pulp. However, in recent years, efforts have been made to provide sanitary materials such as thinner diapers, and as a part of that, the content of pulp is reduced or, further, so-called pulpless diapers in which no pulp is used are used. Development is actively underway.
[6]
As such, in the case of a sanitary material in which the content of pulp is reduced or in which pulp is not used, the superabsorbent polymer is included in a relatively high ratio, so that the superabsorbent polymer particles are inevitably included in multiple layers in the sanitary material. In order for the entire superabsorbent polymer particles included in multiple layers to more efficiently absorb a large amount of liquid, such as urine, the superabsorbent polymer needs to exhibit not only high absorption performance but also a fast absorption rate.
[7]
On the other hand, such a superabsorbent polymer is generally prepared by polymerizing a monomer to prepare a hydrogel polymer containing a large amount of moisture, and drying the hydrogel polymer and then pulverizing the hydrogel polymer into resin particles having a desired particle size. However, as described above, when the hydrogel polymer is dried and then pulverized, a large amount of fine powder is generated, thereby deteriorating the physical properties of the superabsorbent polymer finally manufactured.
[8]
Accordingly, in addition to the improvement of the water holding capacity (CRC), which is a physical property representing the basic absorbency and water holding power of the superabsorbent polymer, and the absorbency under pressure (AUP), which shows the property of retaining the absorbed liquid well even under external pressure, the superabsorbent polymer is There is a continuous demand for the development of a technology that can manufacture the powder without the generation of fine powder.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[9]
Accordingly, the present invention relates to a superabsorbent polymer composition including an additive having a specific structure, specifically, to a superabsorbent polymer composition prepared by including an additive having a specific structure so that aggregation between resin particles is suppressed and thus an additional pulverization process is not required after the drying process. will be.
means of solving the problem
[10]
In order to solve the above problems, the present invention,
[11]
superabsorbent polymer particles comprising a water-soluble ethylenically unsaturated monomer having an acidic group at least partially neutralized and a crosslinked polymer of an internal crosslinking agent; and
[12]
a carboxylic acid-based additive,
[13]
The carboxylic acid-based additive provides at least one selected from the group consisting of a carboxylic acid represented by the following Chemical Formula 1 and a salt thereof, a superabsorbent polymer composition:
[14]
[Formula 1]
[15]

[16]
In Formula 1,
[17]
A is alkyl having 5 to 21 carbon atoms,
[18]
EO means ethylene oxide (-CH 2 CH 2 O-),
[19]
m is an integer from 1 to 8,
[20]
B 1 is -OCO-, -COO-, or -COOCH(CH 3 )COO-,
[21]
B 2 is alkylene having 3 to 5 carbon atoms, alkenylene having 3 to 5 carbon atoms, or alkynylene having 3 to 5 carbon atoms,
[22]
n is an integer from 1 to 3,
[23]
C is a carboxyl group.
Effects of the Invention
[24]
According to the superabsorbent polymer composition of the present invention, including the carboxylic acid-based additive, specifically, in the presence of the additive, the pulverized particles are pulverized to a desired particle size without agglomeration, so that an additional pulverization step is not required after the drying process. can
Brief description of the drawing
[25]
1 is a graph showing high-performance liquid chromatography (HPLC) of the superabsorbent polymer composition prepared in Example 1 and Comparative Example 1. FIG.
[26]
2 is a photograph showing a case corresponding to the evaluation criterion X when evaluating the particle aggregation characteristics.
[27]
3 is a photograph showing a case corresponding to the evaluation criteria △ when evaluating the particle aggregation characteristics.
[28]
4 is a photograph showing a case corresponding to the evaluation criteria ○ when evaluating the particle aggregation characteristics.
[29]
5 is a photograph showing a case corresponding to the evaluation criteria ◎ when evaluating the particle aggregation characteristics.
Modes for carrying out the invention
[30]
The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise", "comprising" or "having" are intended to designate the presence of an embodied feature, step, element, or a combination thereof, but one or more other features or steps; It should be understood that the possibility of the presence or addition of components, or combinations thereof, is not precluded in advance.
[31]
Since the present invention may have various changes and may have various forms, specific 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.
[32]
Since the present invention may have various changes and may have various forms, specific 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.
[33]
Hereinafter, a method for manufacturing a super absorbent polymer and a super absorbent polymer according to specific embodiments of the present invention will be described in more detail.
[34]
Before that, the terminology used herein is for the purpose of referring to particular embodiments only, and is not intended to limit the present invention. And, as used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite.
[35]
According to one embodiment of the invention, the superabsorbent polymer particles comprising a water-soluble ethylenically unsaturated monomer having an acidic group at least partially neutralized and a crosslinked polymer of an internal crosslinking agent; and a carboxylic acid-based additive, wherein the carboxylic acid-based additive is at least one selected from the group consisting of a carboxylic acid represented by the following Chemical Formula 1 and a salt thereof, and a superabsorbent polymer composition is provided:
[36]
[Formula 1]
[37]

[38]
In Formula 1,
[39]
A is alkyl having 5 to 21 carbon atoms,
[40]
EO means ethylene oxide (-CH 2 CH 2 O-),
[41]
m is an integer from 1 to 8,
[42]
B 1 is -OCO-, -COO-, or -COOCH(CH 3 )COO-,
[43]
B 2 is alkylene having 3 to 5 carbon atoms, alkenylene having 3 to 5 carbon atoms, or alkynylene having 3 to 5 carbon atoms,
[44]
n is an integer from 1 to 3,
[45]
C is a carboxyl group.
[46]
As used herein, the term “polymer” or “polymer” refers to a polymerized state of a water-soluble ethylenically unsaturated monomer, and may cover all water content ranges or particle diameter ranges. Among the above polymers, a polymer having a moisture content (moisture content) of about 40% by weight or more in a state before drying after polymerization may be referred to as a hydrogel polymer, and particles of which the hydrogel polymer is pulverized and dried may be referred to as a crosslinked polymer. have.
[47]
In addition, the term "super absorbent polymer particle" refers to a particulate material comprising a crosslinked polymer comprising an acidic group and a water-soluble ethylenically unsaturated monomer in which at least a portion of the acidic group is neutralized and crosslinked by an internal crosslinking agent.
[48]
In addition, the term “super absorbent polymer” refers to a cross-linked polymer obtained by polymerizing a water-soluble ethylenically unsaturated monomer containing an acidic group and neutralized at least in part of the acidic group, or powder consisting of particles of a superabsorbent polymer obtained by pulverizing the cross-linked polymer, depending on the context. It means a base resin in the form of (powder), or the crosslinked polymer or the base resin is subjected to additional processes, such as surface crosslinking, fine powder reassembly, drying, pulverization, classification, etc., to a state suitable for commercialization. It is used to cover all. Accordingly, the term “super absorbent polymer composition” may be interpreted as including a composition including a super absorbent polymer, that is, a plurality of super absorbent polymer particles.
[49]
During the manufacturing process of the superabsorbent polymer, in the pulverization step essential for producing particles of the superabsorbent polymer having a desired particle size, when the dried polymer is pulverized, a large amount of fine powder is generated and the physical properties are deteriorated, which has been a problem. . However, in the non-dried hydrogel polymer state, it is possible to coarsely pulverize to the extent of having a particle diameter of approximately 1 to 10 mm, but it was impossible to pulverize to have a particle size of less than 1 mm due to aggregation of the pulverized particles.
[50]
Accordingly, the present inventors have found that when the hydrogel polymer is pulverized in the presence of the carboxylic acid-based additive, pulverized particles can be pulverized to have a desired particle size without agglomeration, and thus a separate pulverization process is not required after drying. By confirming not, the present invention was completed. In particular, the particles included in the superabsorbent polymer composition prepared according to the manufacturing method have a higher bulk density compared to the case in which the additive is not included, and exhibit the same level of surface tension.
[51]
Specifically, the carboxylic acid-based additive has a hydrophobic functional group and a hydrophilic functional group at the same time. On the other hand, the water-soluble ethylenically unsaturated monomers are acid groups (-COOH) and / or neutralized acid groups (-COO - ) contain the so, the function produced by the polymerization, the acid remaining without participating in polymerization the surface of the gel-based polymer (-COOH) and / or neutralized acid groups (-COO - ) the hydrophilic region due to a large amount is present. Therefore, when the additive is mixed with the hydrogel polymer, the hydrophilic functional group of the additive is adsorbed to at least a portion of the hydrophilic portion present on the surface of the hydrogel polymer, and the surface of the polymer to which the additive is adsorbed is different from the additive. Hydrophobicity is exhibited by the hydrophobic functional group located at the terminal. Accordingly, aggregation between the resin particles can be suppressed.
[52]
More specifically, in the carboxylic acid-based additive, the hydrophobic functional group is an alkyl group having 5 to 21 carbon atoms (part A), and the hydrophilic functional group is a C part, and in the case of a carboxyl group (COOH) or a salt, a carboxylate group (COO - ), the The hydrophobic functional group and the hydrophilic functional group are located at both ends of the additive, respectively. In particular, the carboxylic acid-based additive further includes an ethylene oxide (EO) linking group connected to an A substituent in addition to the A and C parts of both terminals and a (B 1 -B 2 ) part, such ethylene oxide and (B 1 -B 2 ) The part serves to improve the adsorption performance to the polymer surface, which may be insufficient with part C alone. Accordingly, the additive having the structure of Formula 1 has excellent adsorption performance on the surface of the polymer exhibiting hydrophilicity compared to the compound having an A-(EO) m -C structure without a (B 1 -B 2 ) moiety , Aggregation of the superabsorbent polymer particles can be effectively suppressed.
[53]
In addition, when the hydrogel polymer is pulverized in the presence of the carboxylic acid-based additive, part A, which is a hydrophobic functional group included in the additive, imparts hydrophobicity to the surface of the pulverized superabsorbent polymer particles to relieve friction between the particles, resulting in superabsorbent properties. While increasing the apparent density of the resin, the hydrophilic functional group C portion included in the additive is also bound to the superabsorbent polymer particles to prevent the surface tension of the resin from being lowered. Accordingly, the superabsorbent polymer composition including the carboxylic acid-based additive may exhibit an equivalent level of surface tension and have a higher apparent density than a composition not including the carboxylic acid-based additive.
[54]
Super absorbent resin composition
[55]
Hereinafter, the superabsorbent polymer composition of one embodiment will be described in more detail for each component.
[56]
The superabsorbent polymer composition according to one embodiment includes a plurality of superabsorbent polymer particles including a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups and a crosslinked polymer of an internal crosslinking agent. In this case, the cross-linked polymer is a water-soluble ethylenically unsaturated monomer having an acidic group at least partially neutralized by cross-linking polymerization in the presence of an internal cross-linking agent, and the main chains formed by polymerization of the monomers are cross-linked by the internal cross-linking agent. It has a dimensional network structure.
[57]
In other words, the superabsorbent polymer composition of one embodiment includes a plurality of superabsorbent polymer particles including a cross-linked polymer between a plurality of water-soluble ethylenically unsaturated monomers having at least partially neutralized acidic groups and an internal crosslinking agent. As such, when the cross-linked polymer has a three-dimensional network structure in which main chains formed by polymerization of the monomers are cross-linked by the internal cross-linking agent, compared to the case of having a two-dimensional linear structure that is not further cross-linked by the internal cross-linking agent The water holding capacity and absorbency under pressure, which are general physical properties of the superabsorbent polymer, can be significantly improved.
[58]
The water-soluble ethylenically unsaturated monomer may be any monomer commonly used in the preparation of super absorbent polymers. As a non-limiting example, the water-soluble ethylenically unsaturated monomer may be a compound represented by the following Chemical Formula 2:
[59]
[Formula 2]
[60]

[61]
In Formula 2,
[62]
R is an alkyl group having 2 to 5 carbon atoms including an unsaturated bond,
[63]
M' is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.
[64]
Preferably, the monomer may be at least one selected from the group consisting of (meth)acrylic acid and monovalent (alkali) metal salts, divalent metal salts, ammonium salts and organic amine salts of these acids.
[65]
As such, when (meth)acrylic acid and/or its salt are used as the water-soluble ethylenically unsaturated monomer, it is advantageous because a super absorbent polymer with improved water absorption can be obtained. In addition, the monomer includes maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethane sulfonic acid, 2-methacryloylethanesulfonic acid, 2-(meth)acryloylpropanesulfonic acid, or 2-(meth) ) acrylamide-2-methyl propane sulfonic acid, (meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, methoxypolyethylene Glycol (meth)acrylate, polyethylene glycol (meth)acrylate, (N,N)-dimethylaminoethyl (meth)acrylate, (N,N)-dimethylaminopropyl (meth)acrylamide and the like can be used.
[66]
Here, the water-soluble ethylenically unsaturated monomer may have an acidic group, and at least a portion of the acidic group may be neutralized by a neutralizing agent. Specifically, in the mixing of the water-soluble ethylenically unsaturated monomer having the acidic group, the internal crosslinking agent, the polymerization initiator, and the neutralizing agent, at least a portion of the acidic groups of the water-soluble ethylenically unsaturated monomer may be neutralized. In this case, as the neutralizing agent, a basic material such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. that can neutralize an acidic group may be used.
[67]
In addition, the degree of neutralization of the water-soluble ethylenically unsaturated monomer, which refers to the degree of neutralization by the neutralizing agent among the acidic groups included in the water-soluble ethylenically unsaturated monomer, is 50 to 90 mol%, or, 60 to 85 mol%, or 65 to 85 mole %, or 65 to 75 mole %. The range of the degree of neutralization may vary depending on the final physical properties, but if the degree of neutralization is too high, the neutralized monomer may be precipitated and it may be difficult for polymerization to proceed smoothly. It can exhibit properties like elastic rubber, which is difficult to handle.
[68]
In addition, the term 'internal crosslinking agent' used in this specification is a term used to distinguish it from a surface crosslinking agent for crosslinking the surface of the superabsorbent polymer particles to be described later. serves to make The crosslinking in the above step proceeds without a surface or internal division, but when the surface crosslinking process of the superabsorbent polymer particles to be described later proceeds, the surface of the particles of the superabsorbent polymer finally produced has a structure crosslinked by a surface crosslinking agent, The inside has a structure crosslinked by the internal crosslinking agent.
[69]
As the internal crosslinking agent, any compound may be used as long as it enables the introduction of a crosslinking bond during polymerization of the water-soluble ethylenically unsaturated monomer. As a non-limiting example, the internal crosslinking agent is N,N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol (meth)acrylate, polyethylene glycol di( Meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol (meth) acrylate, butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylic Rate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentaacrylate, glycerin tri Polyfunctional crosslinking agents such as (meth)acrylate, pentaerythritol tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerin, or ethylene carbonate may be used alone or in combination of two or more, It is not limited.
[70]
The crosslinking polymerization of the water-soluble ethylenically unsaturated monomer in the presence of such an internal crosslinking agent may be performed by thermal polymerization, photopolymerization or hybrid polymerization in the presence of a polymerization initiator, optionally a thickener, plasticizer, storage stabilizer, antioxidant, etc. There, the specific details will be described later.
[71]
The superabsorbent polymer particles may have a particle diameter of about 150 to about 850 μm, and this particle diameter may be measured according to the European Disposables and Nonwovens Association (EDANA) standard EDANA WSP 220.3 method.
[72]
In addition, the superabsorbent polymer composition includes the carboxylic acid-based additive. As described above, the additive is mixed with the hydrogel polymer and added so that pulverization of the hydrogel polymer can be easily accomplished without agglomeration. In this case, the carboxylic acid-based additive is at least one selected from the group consisting of the carboxylic acid represented by Formula 1 and a metal salt thereof. Specifically, the carboxylic acid-based additive is a carboxylic acid represented by the formula (1), an alkali metal salt of the carboxylic acid represented by the formula (1), and an alkaline earth metal salt of the carboxylic acid represented by the formula (1). at least one selected from More specifically, the carboxylic acid-based additive is one of the carboxylic acid represented by the formula (1), an alkali metal salt of the carboxylic acid represented by the formula (1), and an alkaline earth metal salt of the carboxylic acid represented by the formula (1).
[73]
In Formula 1, A is a hydrophobic portion and may be a linear or branched alkyl group having 5 to 21 carbon atoms, but when A is an alkyl group having a linear structure, in terms of inhibiting aggregation of pulverized particles and improving dispersibility more advantageous When A is an alkyl group having less than 5 carbon atoms, there is a problem that the aggregation control of the pulverized particles is not effectively achieved due to the short chain length, and when A is an alkyl group having more than 21 carbon atoms, the mobility of the additive is reduced and the hydrogel It may not be effectively mixed into the polymer, and there may be a problem in that the cost of the composition increases due to an increase in the cost of the additive.
[74]
Specifically, in Formula 1, A is a linear alkyl having 5 to 21 carbon atoms, that is, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decanyl, n-undecanyl , n-dodecanyl, n-tridecanyl, n-tetradecanyl, n-pentadecanyl, n-hexadecanyl, n-heptadecanyl, n-octadecanyl, n-nonadecanyl, n- icosanil, or n-heticosanyl.
[75]
More specifically, A may be a linear alkyl having 6 to 18 carbon atoms, or a linear alkyl having 6 to 15 carbon atoms. For example, A is -C 6 H 13 , -C 10 H 21 , -C 11 H 23 , -C 12 H 25 , -C 13 H 27 , -C 14 H 29 , or -C 15 H 31 can be have.
[76]
In addition, in Formula 1, the ethylene oxide (EO) linking group and (B 1 -B 2 ) moiety serves to improve the adsorption performance on the polymer surface, which may be insufficient only with the C moiety, and the carbon number of B 2 is 5 If the number exceeds the number, the distance between the B 1 part and the C part increases, and the adsorption performance for the hydrogel polymer may be deteriorated. In addition, when m is 0, it is difficult to expect improvement in adsorption performance on the polymer surface, and when m is more than 8, hydrogen bonding between the hydrogel polymer and/or superabsorbent polymer particles may be induced, so that the particles agglomerate. This may not be suppressed.
[77]
Also, in Formula 1, n may be 1, 2, or 3. More specifically, (B 1 -B 2 n indicating the number of) is, (B 1 -B 2 ) a function part to a point and the acid-based additives for enhancing the adsorption capacity of the gel portion C Considering the molecular length for effectively adsorbing to the polymer, n is preferably 1.
[78]
Specifically, in Formula 1, B 1 may be , , or , where * is a binding site with a neighboring atom.
[79]
For example, B 1 is may be.
[80]
In addition, in Formula 1, B 2 may be linear propylene, butylene, or pentylene. At this time, from the viewpoint of improving the adsorption performance of the additive to the crosslinked polymer together with the C moiety, B 2 is preferably butylene.
[81]
In addition, in Formula 1, part C is a hydrophilic part and is a carboxyl group (COOH), but when the carboxylic acid-based additive is a salt, a part showing hydrophilicity is a carboxylate group (COO - ).
[82]
In other words, the carboxylic acid-based additive may be a compound represented by the following Chemical Formula 1a:
[83]
[Formula 1a]
[84]

[85]
In Formula 1a,
[86]
M is H + , a monovalent cation of an alkali metal, or a divalent cation of an alkaline earth metal,
[87]
k is 1 if M is H + or a monovalent cation of an alkali metal, and 2 if M is a divalent cation of an alkaline earth metal,
[88]
A, EO, m, B 1 , B 2 and n are the same as defined in Formula 1 above.
[89]
More specifically, when the carboxylic acid-based additive is an alkali metal salt of a carboxylic acid represented by Formula 1, the additive may be represented by Formula 1':
[90]
[Formula 1']
[91]

[92]
In Formula 1',
[93]
M 1 is an alkali metal, for example sodium or potassium,
[94]
A, EO, m, B 1 , B 2 and n are the same as defined in Formula 1 above.
[95]
In addition, when the carboxylic acid-based additive is an alkaline earth metal salt of a carboxylic acid represented by Formula 1, the additive may be represented by Formula 1”:
[96]
[Formula 1"]
[97]

[98]
In Formula 1", M 2 is an alkaline earth metal, for example, calcium,
[99]
A, EO, m, B 1 , B 2 and n are the same as defined in Formula 1 above.
[100]
Specifically, the carboxylic acid-based additive may be a carboxylic acid represented by the following Chemical Formula 1-A or 1-B:
[101]
[Formula 1-A]
[102]

[103]
[Formula 1-B]
[104]

[105]
In the above formulas 1-A and 1-B,
[106]
m1 is 3, 4, 5, 6, 7, or 8.
[107]
Alternatively, the additive represented by Formula 1' may be an alkali metal salt represented by Formula 1'-A or 1'-B below:
[108]
[Formula 1'-A]
[109]

[110]
[Formula 1'-B]
[111]

[112]
In the above formulas 1'-A and 1'-B,
[113]
m2 is 3, 4, 5, 6, 7, or 8;
[114]
M 1 is an alkali metal.
[115]
Alternatively, the additive represented by Formula 1" may be an alkaline earth metal salt represented by Formula 1"-A or 1"-B below:
[116]
[Formula 1"-A]
[117]

[118]
[Formula 1"-B]
[119]

[120]
In the above formulas 1"-A and 1"-B,
[121]
m3 is 3, 4, 5, 6, 7, or 8;
[122]
M 2 is an alkaline earth metal.
[123]
More specifically, the carboxylic acid-based additive may be a compound represented by any one of the following Chemical Formulas 1-1 to 1-3, but is not limited thereto:
[124]

[125]
In addition, the superabsorbent polymer composition may further include, in addition to the carboxylic acid-based additive, a compound formed by decomposing the ester bond of B 1 while the additive is pulverized together with the hydrogel polymer and then dried .
[126]
Specifically, when the additive is a compound in which n is 1 and B 1 is -OCO-, the superabsorbent polymer composition is an alcohol of A-(EO) m -OH structure and a compound of HOOC-B 2 -C structure. may include more.
[127]
In addition, when the additive is a compound in which n is 1 and B 1 is -COO-, the superabsorbent polymer composition contains a carboxylic acid having a structure of A-(EO) m -COOH and a compound having a structure of HO-B 2 -C. may include more.
[128]
In addition, when the additive is a compound in which n is 1 and B 1 is -COOCH(CH 3 )COO-, the superabsorbent polymer composition includes a carboxylic acid having a structure of A-(EO) m -COOH and HOCH(CH 3 ) It may further include a compound of the structure COO-B 2 -C.
[129]
As such, since the superabsorbent polymer composition further includes a compound formed by decomposition of an ester bond in an additive molecule, mobility of the additives is increased, and re-agglomeration after pulverization can be further prevented.
[130]
In this case, the carboxylic acid-based additive may be included in an amount of 0.01 to 10% by weight based on the total weight of the superabsorbent polymer composition. When the content of the additive in the composition is too low, the agglomeration control effect by the additive is small and the composition may include superabsorbent polymer particles that have not been pulverized to a desired particle size. The physical properties of water holding capacity and absorbency under pressure may be reduced.
[131]
The content of the additive in the superabsorbent polymer composition is determined by first adding 1 g of the superabsorbent polymer composition to 1 ml of distilled water and then sufficiently mixing for 1 hour until swelling, then filtering to extract only the solution portion, and then performing HPLC analysis. In this way, it can be measured by analyzing the additive content dissolved in the solution part.
[132]
More specifically, the carboxylic acid-based additive is 0.01 wt% or more, 0.02 wt% or more, 0.05 wt% or more, 0.1 wt% or more, or 0.5 wt% or more, and 10 wt% or less, based on the total weight of the superabsorbent polymer composition; 8 wt% or less, 5 wt% or less, 3 wt% or less, 2 wt% or less, or 1 wt% or less.
[133]
Meanwhile, at least a portion of the carboxylic acid-based additive may be present on the surface of the superabsorbent polymer particles. Here, "at least some of the additives are present on the surface of the superabsorbent polymer particles" means that at least some of the additives are adsorbed or bonded to the surfaces of the superabsorbent polymer particles. Specifically, the additive may be physically or chemically adsorbed to the surface of the superabsorbent polymer. More specifically, the hydrophilic functional group of the additive may be physically adsorbed to the hydrophilic portion of the surface of the superabsorbent polymer by intermolecular force such as dipole-dipole interaction. As such, the hydrophilic portion of the additive is physically adsorbed to the surface of the superabsorbent polymer particle to surround the surface, and the hydrophobic portion of the additive is not adsorbed to the surface of the resin particle, so that the resin particle has a type of micelle structure. As an additive may be coated.
[134]
Accordingly, when at least a portion of the carboxylic acid-based additive is present on the surface of the superabsorbent polymer particles, compared to the case where all of the carboxylic acid-based additive is present inside the superabsorbent polymer particles, specifically, the crosslinked polymer , aggregation between the pulverized particles during the manufacturing process of the superabsorbent polymer composition can be more effectively suppressed.
[135]
In addition, since at least a portion of the carboxylic acid-based additive is present on the surface of the superabsorbent polymer particles, the superabsorbent polymer composition including the carboxylic acid-based additive has a higher apparent density than the composition not including the additive. It can exhibit high and equivalent surface tensions or higher.
[136]
On the other hand, when the superabsorbent polymer composition does not further include a surface crosslinking layer, which will be described later, a plurality of superabsorbent polymer particles, the carboxylic acid-based additive, and the additive are hydrolyzed during the manufacturing process of the superabsorbent polymer. Hydrophilic additives other than the hydrolyzate may not be included.
[137]
Specifically, the superabsorbent polymer composition of one embodiment may not include a compound having a plurality of hydroxyl groups-containing glucose units in a molecule, such as microcrystalline cellulose. For example, when the superabsorbent polymer composition includes microcrystalline cellulose having an average particle diameter of 1 to 10 μm, such as AVICEL ® PH-101 represented by the following formula 3 available from FMC, a plurality of hydroxy Due to the group, aggregation between the superabsorbent polymer particles cannot be suppressed, so the effect of the above-described additive may not be effectively expressed.
[138]
[Formula 3]
[139]

[140]
In addition, the superabsorbent polymer composition of one embodiment includes polyethylene glycol, polypropylene glycol, poly(ethylene glycol)-poly(propylene glycol) copolymer, polyoxyethylene lauryl ether carboxylic acid, sodium polyoxyethylene lauryl ether carboxyl It may not contain hydrophilic additives such as lactate, lauryl sulfate, sodium lauryl sulfate, and the like. Since these additives do not have the (B 1 -B 2 ) moiety of Formula 1 in the molecule , they cannot be sufficiently adsorbed to the surface of the cross-linked polymer, so that aggregation between the superabsorbent polymer particles is not effectively suppressed. Accordingly, when the superabsorbent polymer composition contains the hydrophilic additive as described above instead of the carboxylic acid-based additive, aggregation between the particles is not suppressed after pulverizing the crosslinked polymer, so that the superabsorbent polymer composition contains a large amount of fine powder, It exhibits low water holding capacity and low apparent density.
[141]
Meanwhile, the superabsorbent polymer composition may further include a surface crosslinking layer formed by further crosslinking the crosslinked polymer through a surface crosslinking agent on at least a portion of the surface of the superabsorbent polymer particles. This is to increase the surface crosslinking density of the superabsorbent polymer particles. As described above, when the superabsorbent polymer particles further include a surface crosslinking layer, the superabsorbent polymer particles have a structure having a higher crosslinking density on the outside than on the inside.
[142]
As the surface cross-linking agent, any surface cross-linking agent that has been conventionally used in the production of superabsorbent polymers may be used without any particular limitation. For example, the surface crosslinking agent is ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2- One selected from the group consisting of methyl-1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, tripropylene glycol and glycerol or more polyols; at least one carbonate-based compound selected from the group consisting of ethylene carbonate, propylene carbonate, and glycerol carbonate; Epoxy compounds, such as ethylene glycol diglycidyl ether; oxazoline compounds such as oxazolidinone; polyamine compounds; oxazoline compounds; mono-, di- or polyoxazolidinone compounds; or a cyclic urea compound; and the like.
[143]
Specifically, one or more, or two or more, or three or more of the above-described surface crosslinking agents may be used as the surface crosslinking agent, for example, ethylene carbonate-propylene carbonate (ECPC), propylene glycol and/or glycerol carbonate can be used.
[144]
In addition, the superabsorbent polymer composition may be about 90% by weight, preferably 95% by weight or more of the superabsorbent polymer particles having a particle diameter of about 150 to 850 μm, based on the total weight, and less than about 10% by weight, more specifically As such, less than about 5% by weight may be fine powder having a particle diameter of less than about 150 μm.
[145]
In addition, the superabsorbent polymer composition has a water holding capacity (CRC) of 37 g/g or more, 38 g/g or more, or 39 g/g or more, and 50 g/g or less, 48 g/g or less, 45 g/g or less, or 43 g/g or less.
[146]
In addition, the superabsorbent polymer composition has an absorbency under pressure (AUP) of 18 g/g or more, or 19 g/g or more, or 20 g/g or more, at 0.7 psi measured according to EDANA method WSP 242.3, and 30 g/g/g or more. g or less, 28 g/g or less, or 26 g/g or less.
[147]
In addition, the superabsorbent polymer composition may have an apparent density (bulk density) of 0.69 to 0.73 g/ml. At this time, the apparent density was measured by placing about 100 g of the superabsorbent polymer composition into a funnel-shaped bulk density measuring device, flowing it down into a 100 ml container, and then measuring the weight of the super absorbent polymer in the container. That is, the apparent density is calculated as (weight of superabsorbent polymer composition)/(volume of container, 100 ml). More specifically, the superabsorbent polymer composition may have a bulk density of 0.70 to 0.72 g/ml.
[148]
In addition, the superabsorbent polymer composition may have a surface tension of 70 mN/m or more and less than 72 mN/m. At this time, the surface tension can be measured by adding 0.5 g of the superabsorbent polymer to 40 mL of 0.9% saline, stirring at 350 rpm for 3 minutes, and then measuring the brine containing the swollen superabsorbent polymer with a surface tension meter.
[149]
Method for preparing super absorbent polymer composition
[150]
On the other hand, the superabsorbent polymer composition can be prepared by crosslinking and polymerizing a water-soluble ethylenically unsaturated monomer having an acidic group at least partially neutralized in the presence of an internal crosslinking agent and a polymerization initiator to form a hydrogel polymer; mixing the water-containing gel polymer with the carboxylic acid-based additive and pulverizing the water-containing superabsorbent polymer particles to prepare a pulverized product including the water-containing superabsorbent polymer particles and the additive; and drying the pulverized product to prepare a superabsorbent polymer composition including the superabsorbent polymer particles and the additive.
[151]
Hereinafter, each step of the manufacturing method of the superabsorbent polymer according to one embodiment will be described in more detail.
[152]
In the method for producing a superabsorbent polymer according to an embodiment, first, in the presence of an internal crosslinking agent and a polymerization initiator, a step of crosslinking and polymerizing a water-soluble ethylenically unsaturated monomer having an acidic group at least partially neutralized to form a hydrogel polymer is performed. .
[153]
The step may include preparing a monomer composition by mixing the water-soluble ethylenically unsaturated monomer, an internal crosslinking agent, and a polymerization initiator, and thermally or photopolymerizing the monomer composition to form a hydrogel polymer. In this case, the description of the water-soluble ethylenically unsaturated monomer and the internal crosslinking agent refer to the above bar.
[154]
In the monomer composition, the internal crosslinking agent may be used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the water-soluble ethylenically unsaturated monomer. For example, the internal crosslinking agent is 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.1 parts by weight or more, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 It can be used in parts by weight or less, or 0.7 parts by weight or less. When the content of the upper internal crosslinking agent is too low, crosslinking does not occur sufficiently and it may be difficult to implement strength above an appropriate level.
[155]
In addition, the polymerization initiator may be appropriately selected depending on the polymerization method, and when using the thermal polymerization method, a thermal polymerization initiator is used, and when using the photopolymerization method, a photopolymerization initiator is used. both of the thermal polymerization initiator and the photopolymerization initiator can be used. However, even by the photopolymerization method, a certain amount of heat is generated by light irradiation such as ultraviolet irradiation, and a certain amount of heat is generated according to the progress of the polymerization reaction, which is an exothermic reaction, so a thermal polymerization initiator may be additionally used.
[156]
The photopolymerization initiator may be used without limitation as long as it is a compound capable of forming radicals by light such as ultraviolet rays.
[157]
As the photopolymerization initiator, for example, benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, benzyl dimethyl ketal Ketal), acyl phosphine and alpha-aminoketone may be used at least one selected from the group consisting of (α-aminoketone). On the other hand, specific examples of acylphosphine include diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide, ethyl (2,4,6- trimethylbenzoyl)phenylphosphinate etc. are mentioned. A more diverse photoinitiator is well described in Reinhold Schwalm's book "UV Coatings: Basics, Recent Developments and New Application" (Elsevier 2007) p115, but is not limited to the above-described examples.
[158]
In addition, as the thermal polymerization initiator, at least one selected from the group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid may be used. Specifically, examples of the persulfate-based initiator include sodium persulfate (Na 2 S 2 O 8 ), potassium persulfate (K 2 S 2 O 8 ), ammonium persulfate (Ammonium persulfate; (NH 4 ) 2 S 2 O 8) and the like, and examples of the azo-based initiator include 2,2-azobis-(2-amidinopropane) dihydrochloride (2,2-azobis(2-amidinopropane) dihydrochloride), 2,2-azobis -(N,N-dimethylene)isobutyramidine dihydrochloride (2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride), 2-(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 described in Odian's book 'Principle of Polymerization (Wiley, 1981)', p203, and are not limited to the above-described examples.
[159]
The polymerization initiator may be used in an amount of 2 parts by weight or less based on 100 parts by weight of the water-soluble ethylenically unsaturated monomer. That is, when the concentration of the polymerization initiator is too low, the polymerization rate may be slowed and the residual monomer may be extracted in a large amount in the final product, which is not preferable. Conversely, when the concentration of the polymerization initiator is higher than the above range, the polymer chain constituting the network is shortened, so that the content of the water-soluble component is increased, and the physical properties of the resin may be lowered, such as lowered absorbency under pressure, which is not preferable.
[160]
The monomer composition may further include additives such as a thickener, a plasticizer, a preservation stabilizer, and an antioxidant, if necessary.
[161]
In addition, the monomer composition including the monomer may be in a solution state dissolved in a solvent such as water, and the solid content in the monomer composition in the solution state, that is, the concentration of the monomer, the internal crosslinking agent, and the polymerization initiator is determined by polymerization. It may be appropriately adjusted in consideration of time and reaction conditions. For example, the solids content in the monomer composition may be 10 to 80% by weight, or 15 to 60% by weight, or 30 to 50% by weight.
[162]
When the monomer composition has a solid content in the range as described above, it is not necessary to remove unreacted monomers after polymerization by using the gel effect phenomenon that occurs in the polymerization reaction of a high concentration aqueous solution. It can be advantageous to control.
[163]
The solvent that can be used at this time can be used without limitation in its composition as long as it can dissolve the above-mentioned components, for example, water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, propylene Glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl At least one selected from ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate and N,N-dimethylacetamide may be used in combination.
[164]
On the other hand, crosslinking polymerization of a water-soluble ethylenically unsaturated monomer having at least a partially neutralized acidic group may be carried out without particular limitation on the configuration, as long as the hydrogel polymer can be formed by thermal polymerization, photopolymerization, or hybrid polymerization.
[165]
Specifically, the polymerization method is largely divided into thermal polymerization and photopolymerization depending on the polymerization energy source. In general, when thermal polymerization is performed, it may be carried out in a reactor having a stirring shaft such as a kneader, and in the case of photopolymerization, a movable The process may be carried out in a reactor equipped with a conveyor belt or in a flat-bottomed vessel, but the polymerization method described above is an example, and the present invention is not limited to the polymerization method described above.
[166]
For example, as described above, the hydrogel polymer obtained by thermal polymerization by supplying hot air or heating the reactor to a reactor such as a kneader having a stirring shaft is fed to the reactor outlet according to the shape of the stirring shaft provided in the reactor. The discharged hydrogel polymer may be in the form of several centimeters to several millimeters. Specifically, the size of the obtained hydrogel polymer may vary depending on the concentration and injection rate of the injected monomer composition, and a hydrogel polymer having a weight average particle diameter of 2 to 50 mm can be obtained.
[167]
In addition, as described above, when photopolymerization is performed in a reactor equipped with a movable conveyor belt or a flat-bottomed container, the form of the hydrogel polymer obtained may be a hydrogel polymer on a sheet having the width of the belt. At this time, the thickness of the polymer sheet varies depending on the concentration of the injected monomer composition and the injection rate or injection amount, but it is preferable to supply the monomer composition so that a polymer sheet having a thickness of usually about 0.5 to about 5 cm can be obtained. . When the monomer composition is supplied so that the thickness of the polymer on the sheet is too thin, the production efficiency is low, which is undesirable. it may not be
[168]
In this case, the hydrogel polymer obtained by this method may have a moisture content of 40 to 70 wt%. For example, the water content of the hydrogel polymer may be 40 wt% or more, 45 wt% or more, or 50 wt% or more, and 70 wt% or less, 65 wt% or less, or 60 wt% or less. When the water content of the hydrogel polymer is too low, it is difficult to secure an appropriate surface area in the subsequent pulverization step, and there is a fear that the drying efficiency decreases. Absorption capacity may be reduced, and there is a concern that a lot of energy and a long time may be required in the drying step after pulverization.
[169]
Meanwhile, throughout the present specification, "moisture content" refers to a value obtained by subtracting the weight of the polymer in a dry state from the weight of the hydrogel polymer as the moisture content occupied with respect to the total weight of the hydrogel polymer. Specifically, it is defined as a value calculated by measuring the weight loss due to evaporation of moisture in the polymer during drying by raising the temperature of the polymer in the crumb state through infrared heating. At this time, the drying condition is set to 40 minutes including 5 minutes of the temperature rising step in such a way that the temperature is raised from room temperature to about 180°C and then maintained at 180°C, and the moisture content is measured.
[170]
Next, the hydrogel polymer is mixed with the carboxylic acid-based additive and then pulverized to prepare the water-containing superabsorbent polymer particles and a pulverized product including the additive. For specific details of the additive, refer to the above bar.
[171]
In a conventional method for preparing a superabsorbent polymer, a superabsorbent polymer is prepared by coarsely pulverizing the hydrogel polymer, drying it, and then pulverizing it to a desired particle size in a dried state. In this case, the pulverization is performed in a dry state, so that a large amount of fine powder having a particle diameter of less than 150 μm may be generated. Accordingly, there is a problem that a classification process of classifying the superabsorbent polymer particles according to the particle size is absolutely necessary.
[172]
However, as described above, when the pulverization is performed together with the additive having the structure of Formula 1 in the hydrogel polymer state, it is possible to prepare a group of particles having a desired particle size without aggregation between the pulverized particles. Accordingly, since the method of manufacturing the superabsorbent polymer composition according to the exemplary embodiment does not require a grinding process and a classification process after drying, the manufacturing cost of the superabsorbent polymer can be greatly reduced.
[173]
In the above step, the carboxylic acid-based additive may be added in an amount of 0.01 to 10% by weight based on the total weight of the superabsorbent polymer composition. This may be approximately implemented by using about 0.01 to about 10 parts by weight of the carboxylic acid-based additive based on 100 parts by weight of the hydrogel polymer. However, since the ester bond of B1 may be decomposed during pulverization and drying after the hydrogel polymer is formed, the amount of the added additive and the amount of the additive remaining in the final prepared superabsorbent polymer composition may not be the same. When the additive is used too little, it is not uniformly adsorbed on the surface of the hydrogel polymer, so that the particles may re-agglomerate after pulverization. can be
[174]
The method of mixing these additives with the hydrogel polymer is not particularly limited as long as they can be evenly mixed with the hydrogel polymer, but may be appropriately adopted and used.
[175]
For example, the additive may be mixed in a solution state dissolved in a solvent, specifically water. At this time, the solution is mixed by putting the additive and the hydrogel polymer in a reaction tank, or by putting the hydrogel polymer in a mixer and spraying the solution, or by continuously supplying the hydrogel polymer and the solution to a continuously operated mixer and mixing them. etc. can be used.
[176]
After mixing the hydrogel polymer and the additive, the mixture may be pulverized to prepare a pulverized product in which the water-containing superabsorbent polymer particles and the additive are mixed. Specifically, the pulverizing step may be performed so that the pulverized superabsorbent polymer particles have a particle diameter of 150 μm to 850 μm. Here, "water-containing superabsorbent polymer particles" are particles having a moisture content (moisture content) of about 40 wt% or more, and since the hydrogel polymer is pulverized into particles without a drying process, 40 to 70 wt% of the hydrogel polymer is It can have moisture content.
[177]
At this time, the pulverizer used for pulverization is a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, and a cutter mill. , a disc mill, a shred crusher, a crusher, a chopper, and a disc cutter may include any one selected from the group consisting of a grinding device, but Examples are not limited.
[178]
Alternatively, as a grinder, a pin mill, a hammer mill, a screw mill, a roll mill, a disk mill, or a jog mill may be used. , but is not limited to the above example.
[179]
Meanwhile, at least some of the additives included in the pulverized material may be present on the surface of the water-containing superabsorbent polymer particles. As described above, “at least some of the additives are present on the surface of the water-containing superabsorbent polymer particles” means that at least some of the additives are adsorbed or bonded to the surface of the water-containing superabsorbent polymer particles. . This is because the carboxylic acid-based additive is not added during the polymerization process of the water-soluble ethylenically unsaturated monomer, but is added after the polymer is formed. Re-agglomeration between the superabsorbent polymer particles may be suppressed.
[180]
Next, drying the pulverized material to prepare a super absorbent polymer composition including the super absorbent polymer particles and the additive is performed. In particular, after the drying step of the pulverized product, it is possible to prepare a superabsorbent polymer composition including superabsorbent polymer particles having desired physical properties without an additional pulverization step.
[181]
The drying of the pulverized product may be performed so that the moisture content of each of the plurality of superabsorbent polymer particles included in the prepared superabsorbent polymer composition is about 10 wt% or less, specifically, about 0.1 to about 10 wt%.
[182]
At this time, the drying temperature may be about 60 ℃ to about 250 ℃. In this case, when the drying temperature is too low, the drying time may be too long. When the drying temperature is too high, only the surface of the polymer is dried, and there is a risk that the physical properties of the superabsorbent polymer finally formed may be deteriorated. Therefore, preferably, the drying may be carried out at a temperature of about 100 °C to about 240 °C, more preferably at a temperature of about 110 °C to about 220 °C.
[183]
In addition, the drying time may be performed for about 20 minutes to about 12 hours in consideration of process efficiency and the like. For example, it may be dried for about 10 minutes to about 100 minutes, or about 20 minutes to about 60 minutes.
[184]
If the drying method of the drying step is also commonly used as a drying process, it may be selected and used without limitation in its configuration. Specifically, the drying step may be performed by a method such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation.
[185]
The superabsorbent polymer composition prepared as described above may contain, in addition to the plurality of superabsorbent polymer particles and additives, less than about 10% by weight, more specifically, less than about 5% by weight of fine powder having a particle diameter of less than 150 μm relative to the total weight. can This is in contrast to having about 10 wt% to about 20 wt% of fine powder when the hydrogel polymer is dried and then pulverized to prepare a super absorbent polymer.
[186]
Thereafter, if necessary, the method may further include forming a surface crosslinking layer on at least a portion of the surface of the superabsorbent polymer particles in the presence of a surface crosslinking agent. Through the above step, the crosslinked polymer included in the superabsorbent polymer particles may be further crosslinked through the surface crosslinking agent to form a surface crosslinking layer on at least a portion of the surface of the superabsorbent polymer particles.
[187]
The surface crosslinking agent may be used in an amount of about 0.001 to about 5 parts by weight based on 100 parts by weight of the superabsorbent polymer particles. For example, the surface crosslinking agent is 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.05 parts by weight or more, and 5 parts by weight or less, 4 parts by weight or less, or 3 parts by weight or less based on 100 parts by weight of the superabsorbent polymer particles. content can be used. By adjusting the content range of the surface crosslinking agent to the above-mentioned range, a superabsorbent polymer having excellent absorbent properties can be prepared.
[188]
In addition, the step of forming the surface crosslinking layer may be performed by adding an inorganic material to the surface crosslinking agent. That is, in the presence of the surface crosslinking agent and the inorganic material, the step of further crosslinking the surface of the superabsorbent polymer particles to form a surface crosslinking layer may be performed.
[189]
As the inorganic material, at least one inorganic material selected from the group consisting of silica, clay, alumina, silica-alumina composite, titania, zinc oxide, and aluminum sulfate may be used. The inorganic material may be used in powder form or liquid form, and in particular, may be used as alumina powder, silica-alumina powder, titania powder, or nano silica solution. In addition, the inorganic material may be used in an amount of about 0.001 to about 1 part by weight based on 100 parts by weight of the super absorbent polymer particles.
[190]
In addition, there is no limitation on the composition of the method of mixing the surface crosslinking agent with the superabsorbent polymer composition. For example, a method of mixing the surface crosslinking agent and the superabsorbent polymer composition in a reaction tank, spraying the surface crosslinking agent to the superabsorbent polymer composition, or continuously supplying and mixing the superabsorbent polymer composition and the surface crosslinking agent to a continuously operated mixer. method and the like can be used.
[191]
When the surface crosslinking agent and the superabsorbent polymer composition are mixed, water and methanol may be mixed together and added. When water and methanol are added, there is an advantage that the surface crosslinking agent can be uniformly dispersed in the superabsorbent polymer composition. In this case, the content of the added water and methanol may be appropriately adjusted to induce even dispersion of the surface crosslinking agent, prevent agglomeration of the superabsorbent polymer composition, and at the same time optimize the surface penetration depth of the crosslinking agent.
[192]
The surface crosslinking process may be performed at a temperature of about 80 °C to about 250 °C. More specifically, the surface crosslinking process may be performed at a temperature of about 100° C. to about 220° C., or about 120° C. to about 200° C., for about 20 minutes to about 2 hours, or about 40 minutes to about 80 minutes. . When the above-described surface crosslinking process conditions are satisfied, the surface of the superabsorbent polymer particles may be sufficiently crosslinked to increase absorbency under pressure.
[193]
A means for increasing the temperature for the surface crosslinking reaction is not particularly limited. It can be heated by supplying a heating medium or by directly supplying a heat source. At this time, as the type of heating medium that can be used, a fluid with increased temperature such as steam, hot air, or hot oil may be used, but the present invention is not limited thereto. Considering it, it can be appropriately selected. On the other hand, the directly supplied heat source may be a heating method through electricity or a heating method through a gas, but is not limited to the above-described example.
[194]
Hereinafter, preferred embodiments are presented to help the understanding of the invention. However, the following examples are only for illustrating the invention, and do not limit the invention thereto.
[195]
Example - Preparation of super absorbent polymer composition
[196]
Example 1
[197]
In a 3L glass container equipped with a stirrer and a thermometer, 100 g (1.388 mol) of acrylic acid, 0.16 g of internal crosslinking agent polyethylene glycol diacrylate (Mn=508), and photopolymerization initiator diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide 0.008 g, sodium persulfate 0.12 g, a thermal polymerization initiator, and 123.5 g of a 32% caustic soda solution were mixed at room temperature to prepare a monomer composition (neutralization degree of acrylic acid: 70 mol%, solid content: 45 wt%).
[198]
Thereafter, the monomer composition was supplied at a rate of 500 to 2000 mL/min on a conveyor belt in which a belt having a width of 10 cm and a length of 2 m was rotated at a speed of 50 cm/min. Then, at the same time as the supply of the monomer composition, the polymerization reaction was carried out for 60 seconds by irradiating ultraviolet rays having an intensity of 10 mW/cm 2 to obtain a hydrogel polymer having a water content of 55 wt%.
[199]
Next, laureth-3-adipate (manufactured by Afcona) represented by the following Chemical Formula 1-1 was added to the hydrogel polymer obtained through the polymerization reaction by 1 weight based on 100 parts by weight of the hydrogel polymer. After dissolving and mixing in 3.5 parts by weight of water so as to be added, it was pulverized using a meat chopper. Thereafter, the pulverized product was dried by flowing hot air at 185° C. from the bottom to the top for 20 minutes using a convection oven capable of transferring the air volume up and down, and again flowing from the top to the bottom for 20 minutes to dry, A resin was prepared.
[200]
Next, a mixed solution of 4.8 g of water, 0.1 g of propylene glycol, 0.8 g of ethylene carbonate, 0.8 g of propylene carbonate, and 0.87 g of a 23% aluminum sulfate aqueous solution was added to 100 g of the obtained superabsorbent polymer and mixed for 2 minutes, and this After drying at 185° C. for 60 minutes, a final superabsorbent polymer composition was prepared.
[201]
[Formula 1-1]
[202]

[203]
Example 2
[204]
In Example 1, instead of laureth-3-adipate represented by Formula 1-1, laureth-8-adipate represented by Formula 1-2 below (laureth-8-adipate, Afcona) A superabsorbent polymer composition was prepared in the same manner as in Example 1, except that) was used.
[205]
[Formula 1-2]
[206]

[207]
Example 3
[208]
In Example 1, instead of laureth-3-adipate represented by Chemical Formula 1-1, monohex-3-adipate represented by the following Chemical Formula 1-3 (monohexeth-3-adipate, A superabsorbent polymer composition was prepared in the same manner as in Example 1, except that Afcona) was used.
[209]
[Formula 1-3]
[210]

[211]
Comparative Example 1
[212]
A superabsorbent polymer composition was prepared in the same manner as in Example 1, except that laureth-3-adipate represented by Formula 1-1 was not used in Example 1 did.
[213]
Comparative Example 2
[214]
Except for using dodecanoic acid (manufactured by Sigma Aldrich) represented by the following formula X-1 instead of laureth-3-adipate represented by the formula 1-1 in Example 1 Then, a superabsorbent polymer composition was prepared using the same method as in Example 1.
[215]
[Formula X-1]
[216]

[217]
Comparative Example 3
[218]
Except for using stearic acid (manufactured by Sigma Aldrich) represented by the following formula X-2 instead of laureth-3-adipate represented by the formula 1-1 in Example 1 Then, a superabsorbent polymer composition was prepared using the same method as in Example 1.
[219]
[Formula X-2]
[220]

[221]
Comparative Example 4
[222]
In Example 1, a nonionic surfactant compound represented by the following formula X-3 (PLURONIC ® L35, manufactured by BASF) was used instead of laureth-3-adipate represented by the formula 1-1. A super absorbent polymer composition was prepared in the same manner as in Example 1, except that it was used.
[223]
[Formula X-3]
[224]

[225]
In the formula (X-3),
[226]
EO means ethylene oxide, PO means propylene oxide.
[227]
Comparative Example 5
[228]
In Example 1, instead of laureth-3-adipate represented by Formula 1-1, laureth-3-adipate (Afcona) represented by the following Formula X-4 A superabsorbent polymer composition was prepared in the same manner as in Example 1, except that ) was used.
[229]
[Formula X-4]
[230]

[231]
Comparative Example 6
[232]
In Example 1, instead of laureth-3-adipate represented by Formula 1-1, laureth-3-suberate represented by the following Formula X-5 (laureth-3-suberate, Afcona) A superabsorbent polymer composition was prepared in the same manner as in Example 1, except that) was used.
[233]
[Formula X-5]
[234]

[235]
Comparative Example 7
[236]
Except that in Example 1, monolauryl adipate represented by the following formula X-6 was used instead of laureth-3-adipate represented by the formula 1-1. , A superabsorbent polymer composition was prepared using the same method as in Example 1. At this time, the monolauryl adipate represented by the following formula (X-6) was prepared by mixing adipic acid anhydride and 1-hexanol in a molar ratio of 1:1 and then reacting at 60°C for 3 hours. was used.
[237]
[Formula X-6]
[238]

[239]
Comparative Example 8
[240]
In Example 1, instead of laureth-3-adipate represented by Formula 1-1, polyoxyethylene (20) sorbitan monostearate (polyoxyethylene (20) sorbitan monostearate, Polysorbate 60, Sigma A superabsorbent polymer composition was prepared in the same manner as in Example 1, except that Aldrich Co., Ltd.) was used.
[241]
Comparative Example 9
[242]
In Example 1, sodium polyoxyethylene (3) lauryl ether carboxylate (LCA-30D, manufactured by Sanyo chemical) represented by the following formula X-7 instead of monolauryl maleate represented by the formula 1-1 was used. Except for that, a superabsorbent polymer composition was prepared in the same manner as in Example 1.
[243]
[Formula X-7]
[244]

[245]
Comparative Example 10
[246]
Except for using sodium lauryl sulphate represented by the following formula (X-8) instead of monolauryl maleate (monolauryl maleate) represented by the formula (1-1) in Example 1, Example 1 and A superabsorbent polymer composition was prepared using the same method.
[247]
[Formula X-8]
[248]

[249]
Test Example 1
[250]
With respect to the superabsorbent polymer composition prepared in Examples 1, 2 and Comparative Example 1, using high-performance liquid chromatography (HPLC), additives contained in the composition as follows Each content was measured, and the results are shown in Table 1 below. In addition, among them, graphs of high-performance liquid chromatography (HPLC) of the superabsorbent polymer compositions prepared in Example 1 and Comparative Example 1 are shown together in FIG. 1 .
[251]
① After adding 1 ml of distilled water to 1.0±0.0001 g of the final prepared superabsorbent polymer composition, it was sufficiently swollen for 1 hour.
[252]
② 6 mL of solvent (MeOH:Methylene chloride = 2:1 v/v) was added to the swollen superabsorbent polymer composition, and then filtered after 4 hours to extract only the solution portion, which was used as a sample solution.
[253]
③ The content of the additive dissolved in the sample solution was quantified by passing the sample solution through high-performance liquid chromatography (HPLC) to determine the residual material content.
[254]
At this time, the measurement conditions of high performance liquid chromatography (HPLC) are as follows:
[255]
- column: Acquity BEH C 18 (2.1 mm ID × 50 mm L, particle size: 1.7㎛)
[256]
- Mobile phase A: ACN (Acetonitrile (0.1% trifluoroacetic acid))
[257]
- Mobile phase B: DI Water (0.1% trifluoroacetic acid)
[258]
- column temp.: 40℃
[259]
- Flaw rate: 0.4 mL/min
[260]
[Table 1]
[261]
1) Weight % based on the total weight of the superabsorbent polymer composition
[262]
Referring to Table 1 and FIG. 1, unlike the superabsorbent polymer composition prepared in Comparative Example 1, the superabsorbent polymer composition prepared in Example 1 contains laureth-3- represented by Formula 1-1. It can be confirmed that adipate (laureth-3-adipate) is present. Specifically, laureth-3-adipate represented by Formula 1-1 was confirmed at a retention time of 9.551 minutes when measured under the measurement conditions of high performance liquid chromatography (HPLC). do.
[263]
Test Example 2
[264]
For the superabsorbent polymer compositions prepared in Examples and Comparative Examples, particle agglomeration characteristics, centrifugation retention capacity (CRC), absorbency under pressure (AUP), surface tension, apparent density and amount of fine powder were measured in the following manner, respectively. , the results are shown in Table 3 below.
[265]
(1) Evaluation of particle aggregation properties
[266]
① After taking out 20 g of the hydrogel polymer prepared in each Example and Comparative Example, cut it into 6 equal parts so that at least one edge of 2 cm or more is included using scissors, and then, the carboxylic acid-based additive or the corresponding comparative compound was mixed in the form of an aqueous solution according to the type and content used in each Example and Comparative Example.
[267]
② The mixture was pulverized for 15 seconds at 7200 rpm using a homomixer.
[268]
③ The pulverized product was visually evaluated by applying the evaluation criteria in Table 2 below. In addition, photographs showing cases meeting the evaluation criteria X, Δ, ○ and ◎ according to the evaluation criteria of Table 2 are shown in FIGS. 2, 3, 4 and 5, respectively.
[269]
[Table 2]
[270]
(2) Centrifuge Retention Capacity (CRC)
[271]
The water holding capacity of each resin composition according to the absorption magnification under no load was measured according to the European Disposables and Nonwovens Association (EDANA) standard EDANA WSP 241.3.
[272]
Specifically, in the resin compositions obtained in Examples and Comparative Examples, respectively, a resin composition classified through a sieve of #30-50 was obtained. This resin composition W 0 (g) (about 0.2 g) was uniformly put in a non-woven bag and sealed, and then immersed in physiological saline (0.9 wt %) at room temperature. After 30 minutes, the bag was drained of water for 3 minutes under the conditions of 250G using a centrifuge, and the mass W 2 (g) of the bag was measured. Further, after the same operation without the use of resin, then the mass W of the first to (g) was measured.
[273]
CRC (g/g) was calculated according to Equation 2 below using each obtained mass.
[274]
[Equation 2]
[275]

[276]
(3) Absorbency under Pressure (AUP)
[277]
The absorbency under pressure of 0.7 psi of the superabsorbent polymer compositions of Examples and Comparative Examples was measured according to the EDANA method WSP 242.3.
[278]
First, at the time of measuring the absorbency under pressure, the resin fraction at the time of the CRC measurement was used.
[279]
Specifically, a stainless steel 400 mesh wire mesh was mounted on the bottom of a plastic cylinder having an inner diameter of 25 mm. Under the conditions of room temperature and humidity of 50%, the water absorbent resin composition W 0 (g) (0.16 g) is uniformly sprayed on the wire mesh , and the piston that can further uniformly apply a load of 0.7 psi thereon is slightly more than 25 mm in outer diameter. It is small, there is no gap with the inner wall of the cylinder, and the vertical movement is not disturbed. At this time, the weight W 3 (g) of the device was measured.
[280]
A glass filter having a diameter of 90 mm and a thickness of 5 mm was placed inside a petro dish having a diameter of 150 mm, and physiological saline composed of 0.9 wt% sodium chloride was placed at the same level as the upper surface of the glass filter. One filter paper having a diameter of 90 mm was loaded thereon. The measuring device was placed on the filter paper, and the liquid was absorbed under load for 1 hour. After 1 hour, the measuring device was lifted and the weight W 4 (g) was measured.
[281]
The absorbency under pressure (g/g) was calculated according to the following Equation 3 using each of the obtained masses.
[282]
[Equation 3]
[283]

[284]
(4) Surface tension (S/T)
[285]
In order to measure the surface tension of the superabsorbent polymer compositions of Examples and Comparative Examples, 0.5 g of each superabsorbent polymer composition was added to 40 mL of 0.9% saline, stirred at 350 rpm for 3 minutes, and then stopped stirring, followed by swelling A brine containing superabsorbent polymer was obtained. Using the brine as a measurement sample, the surface tension of each superabsorbent polymer composition was measured using a surface tension meter (product name: Force Tensiometer-K100, manufactured by KRUSS).
[286]
(5) Bulk density (BD)
[287]
100 g of the superabsorbent polymer compositions of Examples and Comparative Examples were flowed through the orifice of a standard flow measuring device, received in a container with a volume of 100 ml, and the superabsorbent polymer composition was shaved to be horizontal, and the volume of the superabsorbent polymer composition was 100 ml After adjusting to , the weight of only the superabsorbent polymer composition excluding the container was measured. Then, the weight of the superabsorbent polymer composition alone was divided by 100 ml of the volume of the superabsorbent polymer composition to obtain an apparent density corresponding to the weight of the superabsorbent polymer composition per unit volume.
[288]
(6) The amount of fines generated
[289]
The amount of fine powder generated in the superabsorbent polymer compositions of Examples and Comparative Examples is less than 150 μm based on the total weight after passing the prepared superabsorbent polymer composition through a coarse grinder (2800rpm, 0.4mm clearance, 1mm bottom mesh condition) once. It was calculated as the ratio of the weight of the resin having a particle size.
[290]
[Table 3]
[291]
Referring to Table 3, when the superabsorbent polymer composition is prepared by adding the carboxylic acid-based additive to the hydrogel polymer, compared to the case where such an additive is not used or a compound that does not conform to the structure is used, after pulverization It can be seen that the aggregation between the particles is suppressed, so that it is possible to prepare a composition including the super absorbent polymer particles having a desired particle size without an additional pulverization process after drying, and thus the amount of fine powder is reduced.
[292]
In addition, the superabsorbent polymer composition including the carboxylic acid-based additive has higher water retention capacity and absorbency under pressure than the superabsorbent polymer composition that does not include the additive or includes a compound that does not conform to the structure of the additive. It can be confirmed that while still having a high bulk density without a decrease in surface tension at the same time.

WE CLAIMS

superabsorbent polymer particles comprising a water-soluble ethylenically unsaturated monomer having an acidic group at least partially neutralized and a crosslinked polymer of an internal crosslinking agent; And an acid-based additive, the acid-based additive to formula (I) selected from the group consisting of carboxylic acids and salts thereof represented by at least one member, and the water absorbent resin composition: Formula 1 Formula 1 In, A is an alkyl of 5 to 21 carbon atoms, EO means ethylene oxide (-CH 2 CH 2 O-), m is an integer of 1 to 8, B 1 is -OCO-, -COO-, or -COOCH(CH 3 )COO-, B 2 is alkylene having 3 to 5 carbon atoms, alkenylene having 3 to 5 carbon atoms, or alkynylene having 3 to 5 carbon atoms, n is an integer of 1 to 3, and C is is a carboxyl group.
[Claim 2]
The superabsorbent polymer composition according to claim 1, wherein at least a portion of the carboxylic acid-based additive is present on the surface of the superabsorbent polymer particles.
[Claim 3]
According to claim 1, wherein in Formula 1, A is -C 6 H 13 , -C 10 H 21 , -C 11 H 23 , -C 12 H 25 , -C 13 H 27 , -C 14 H 29 , or -C 15 H 31 , the superabsorbent polymer composition.
[Claim 4]
The superabsorbent polymer composition of claim 1, wherein in Formula 1, B 1 is , where * is a bonding site with a neighboring atom.
[Claim 5]
The superabsorbent polymer composition of claim 1, wherein in Formula 1, B 2 is propylene, butylene, or pentylene.
[Claim 6]
The superabsorbent polymer composition of claim 1, wherein the carboxylic acid-based additive is at least one selected from the group consisting of a carboxylic acid represented by Formula 1, an alkali metal salt thereof, and an alkaline earth metal salt thereof.
[Claim 7]
The superabsorbent polymer composition according to claim 1, wherein the carboxylic acid-based additive is represented by any one of the following Chemical Formulas 1-1 to 1-3:
[Claim 8]
The superabsorbent polymer composition of claim 1, wherein the carboxylic acid-based additive is included in an amount of 0.01 to 10% by weight based on the total weight of the superabsorbent polymer composition.
[Claim 9]
The superabsorbent polymer composition according to claim 1, further comprising a surface crosslinking layer formed by further crosslinking the crosslinked polymer via a surface crosslinking agent on at least a portion of the surface of the superabsorbent polymer particles.