WO2020067662A1 - Manufacturing method for superabsorbent polymer sheet - Google Patents

Manufacturing method for superabsorbent polymer sheet Download PDF

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WO2020067662A1
WO2020067662A1 PCT/KR2019/011716 KR2019011716W WO2020067662A1 WO 2020067662 A1 WO2020067662 A1 WO 2020067662A1 KR 2019011716 W KR2019011716 W KR 2019011716W WO 2020067662 A1 WO2020067662 A1 WO 2020067662A1
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Prior art keywords
polymer sheet
super absorbent
foaming agent
absorbent polymer
superabsorbent polymer
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PCT/KR2019/011716
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French (fr)
Korean (ko)
Inventor
윤기열
강성균
김기철
최현
김주은
Original Assignee
주식회사 엘지화학
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Priority claimed from KR1020190110999A external-priority patent/KR102457232B1/en
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to CN201980004789.9A priority Critical patent/CN111225945B/en
Priority to US16/757,158 priority patent/US11773236B2/en
Priority to EP19867682.7A priority patent/EP3680285B1/en
Publication of WO2020067662A1 publication Critical patent/WO2020067662A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
    • C08J9/08—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
    • C08J9/14—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent organic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/10—Encapsulated ingredients

Definitions

  • the present invention relates to a method for producing a super absorbent polymer sheet.
  • Super Absorbent Polymer is a synthetic polymer material that has the ability to absorb about 500 to 1,000 times its own weight.Sam (Super Absorbency Material), AGM (Absorbent Gel) for each developer Material).
  • the superabsorbent polymer as described above began to be put into practical use as a sanitary tool, and now, in addition to sanitary products such as children's paper diapers and sanitary napkins, soil repair agents for horticulture, civil engineering, construction materials, nursery sheets, and freshness retention agents in the food distribution field , And is widely used as a material for poultice.
  • hygiene products such as various diapers, sanitary napkins, or incontinence pads include absorbents including superabsorbent polymer particles, and these absorbents are mainly the superabsorbent polymer particles and the superabsorbent polymer particles are properly fixed while the absorbent and hygiene It was common to use fluff pulp to maintain the shape of the article.
  • the current superabsorbent polymer is mostly used in the form of a powder.
  • the superabsorbent polymer in the form of powder has a portion that can be scattered or leaked when manufacturing hygiene materials or in actual use, and is limited in scope of use because it must be used with a specific type of substrate.
  • the present invention provides a method for producing a super absorbent polymer sheet exhibiting high flexibility and fast absorption speed and excellent texture.
  • the present invention to solve the above problems,
  • Preparing an monomer composition by mixing an acrylic acid-based monomer having an acidic group and at least a part of the acidic group being neutralized, an internal crosslinking agent containing polyol, an encapsulating foaming agent, an inorganic foaming agent, and a polymerization initiator;
  • It provides a method for producing a super absorbent polymer sheet comprising the step of drying the hydrogel polymer.
  • the polyol is ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl- 1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, at least one member selected from the group consisting of tripropylene glycol and glycerol It may include.
  • the polyol may be included in an amount of 10 to 80 parts by weight based on 100 parts by weight of the acrylic monomer.
  • the encapsulated foaming agent may have an average diameter of 2 to 50 ⁇ m.
  • the encapsulating blowing agent may have an expansion ratio of 3 to 15 times in air.
  • the encapsulated foaming agent may have a structure including a core including a hydrocarbon and a shell surrounding the core and formed of a thermoplastic resin.
  • the inorganic blowing agent is calcium carbonate (CaCO 3 ), sodium bicarbonate (NaHCO 3 ), ammonium bicarbonate (NH 4 HCO 3 ), ammonium carbonate ((NH 4 ) 2 CO 3 ), ammonium nitrite (NH 4 NO 2 ), hydrogen borohydride It may be one or more selected from sodium (NaBH 4 ) and sodium carbonate (Na 2 CO 3 ).
  • the encapsulated foaming agent and the inorganic foaming agent may be included in a weight ratio of 3: 1 to 1: 1.
  • the encapsulated foaming agent may be included in an amount of 0.3 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.
  • the inorganic blowing agent may be included in 0.2 to 10 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.
  • an acrylic acid-based monomer having an acidic group and neutralized at least a portion of the acidic group is crosslinked and polymerized in the presence of an internal crosslinking agent containing a polyol, an encapsulating foaming agent, and an inorganic foaming agent.
  • a superabsorbent polymer resin sheet is provided.
  • the superabsorbent polymer sheet may have a centrifugal water retention capacity (CRC) of 10 g / g to 40 g / g measured according to EDANA method WSP 241.2.
  • CRC centrifugal water retention capacity
  • the superabsorbent polymer sheet may have a pressure absorbing capacity (AUP) of 0.7 g to 20 g / g under 0.7 psi measured according to EDANA method WSP 242.2.
  • AUP pressure absorbing capacity
  • the superabsorbent polymer sheet obtained by the manufacturing method of the present invention is obtained in the form of a sheet or film, unlike the ordinary superabsorbent polymer in powder form, and can be applied directly to a product, and has no fear of scattering or leaking. It can show flexibility.
  • the superabsorbent polymer sheet obtained by the method of manufacturing the superabsorbent polymer sheet of the present invention has an open pore channel structure in which pores are connected to each other, whereby water is absorbed by capillary pressure. Since absorption is possible, absorption rate and permeability can be improved.
  • the superabsorbent polymer sheet can be used as a pulfree absorber.
  • SEM scanning electron microscope
  • Example 2 is a photograph of testing the flexibility of the superabsorbent polymer sheet of Example 1 and Comparative Example 2.
  • the monomer composition is obtained by mixing an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group being neutralized, an internal crosslinking agent containing polyol, an encapsulating foaming agent, an inorganic foaming agent, and a polymerization initiator. Preparing a; Thermally or photopolymerizing the monomer composition to form a hydrogel polymer; And it provides a method for producing a super absorbent polymer sheet comprising the step of drying the hydrogel polymer.
  • the monomer composition which is a raw material of the super absorbent polymer, has an acidic group, and at least a part of the acidic group is an acrylic acid-based monomer, a polyol, an internal crosslinking agent, an encapsulated foaming agent, an inorganic Foaming agents, and polymerization initiators.
  • the acrylic acid monomer is a compound represented by Formula 1 below:
  • 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.
  • the acrylic acid-based monomer includes at least one selected from the group consisting of acrylic acid, methacrylic acid and their monovalent metal salt, divalent metal salt, ammonium salt and organic amine salt.
  • the acrylic acid monomer may have an acidic group and at least a part of the acidic group may be neutralized.
  • the monomer may be partially neutralized with an alkali material such as sodium hydroxide, potassium hydroxide or ammonium hydroxide.
  • the degree of neutralization of the acrylic acid-based monomer may be 40 to 95 mol%, or 40 to 80 mol%, or 45 to 75 mol%.
  • the range of the neutralization degree can be adjusted according to the final physical properties. However, if the degree of neutralization is too high, the neutralized monomer may be precipitated and polymerization may be difficult to proceed smoothly. On the contrary, if the degree of neutralization is too low, it may exhibit properties such as elastic rubber that is not only poorly absorbed but also difficult to handle. have.
  • the concentration of the acrylic acid-based monomer may be about 20 to about 60% by weight, preferably about 40 to about 50% by weight relative to the monomer composition containing the raw material and solvent of the superabsorbent polymer, polymerization time and It may be an appropriate concentration in consideration of reaction conditions and the like. However, if the concentration of the monomer is too low, the yield of the superabsorbent polymer may be low and economic problems may occur. Conversely, if the concentration is too high, a part of the monomer precipitates or the grinding efficiency of the polymerized hydrogel polymer is low. Such problems may occur in the process, and physical properties of the super absorbent polymer may be deteriorated.
  • the monomer composition of the present invention contains a polyol as an internal crosslinking agent.
  • the polyol cross-links with the acrylic acid monomer to form a flexible polymer structure, and also contributes to increase the moisture content of the super absorbent polymer sheet due to hygroscopicity.
  • Examples of usable polyols are ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl -1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, tripropylene glycol or glycerol, preferably.
  • Glycerol can be used.
  • the content of the polyol may be 10 to 80 parts by weight, preferably 20 to 50 parts by weight, more preferably 30 to 40 parts by weight based on 100 parts by weight of the acrylic acid monomer. If the content of the polyol is too small, there may be no effect of improving the water content, and when it is included too much, the content range may be preferable from this point of view since absorption speed and absorption capacity may be lowered.
  • the monomer composition of the present invention may further include an internal crosslinking agent other than the polyol.
  • an internal crosslinking agent a poly (meth) acrylate-based compound of polyol, for example, a poly (meth) acrylate-based compound of polyol having 2 to 10 carbon atoms may be used. More specific examples include trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylic.
  • butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, tri Propylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri (meth) acrylate or pentaerythritol tetraacrylate may be used, preferably polyethylene Glycol diacrylate can be used.
  • the internal crosslinking agent may be included in a concentration of about 0.01 to about 2% by weight, or 0.1 to 0.5% by weight relative to the monomer composition, to crosslink the polymerized polymer.
  • the monomer composition of the present invention includes a blowing agent, wherein the encapsulating blowing agent and the inorganic blowing agent are simultaneously included.
  • a blowing agent wherein the encapsulating blowing agent and the inorganic blowing agent are simultaneously included.
  • two types of foaming agents are used in this way, high porosity and open porosity of the superabsorbent polymer sheet can be obtained. That is, when the encapsulated foaming agent and the inorganic foaming agent are used at the same time as the present invention, the main pores of an appropriate size are formed in the inside of the superabsorbent polymer sheet by the encapsulated foaming agent, and between these main pores In the microporous channel formed by the inorganic foaming agent is formed, it is possible to secure an open pore channel structure in which main pores are connected to each other.
  • the micro-pore channel structure due to the micro-pore channel structure, rapid absorption of water by capillary pressure is possible, and the centrifugal water retention capacity and the pressure absorption capacity of the superabsorbent polymer prepared compared to the case of using each blowing agent alone are excellent.
  • the flexibility of the superabsorbent polymer sheet can be greatly increased due to the above structure.
  • the encapsulated foaming agent exists in an encapsulated state during polymerization of the monomer composition, expands by heat, and foams by high temperature heat applied during the drying process described below, and accordingly, a suitable size between the polymer structures of the super absorbent polymer.
  • the superabsorbent polymer sheet can exhibit the structure of an open pore channel.
  • the encapsulated foaming agent may have a structure including a core comprising a hydrocarbon and a shell surrounding the core and formed of a thermoplastic resin.
  • the encapsulating foaming agent has different expansion characteristics depending on the weight and diameter of the components constituting the core and the shell, and can be expanded to a desired size by controlling it, and can control the porosity of the superabsorbent polymer sheet.
  • the expansion characteristics of the encapsulated blowing agent in order to determine whether pores of a desired size are formed, it is necessary to first grasp the expansion characteristics of the encapsulated blowing agent.
  • the form in which the foaming agent encapsulated in the superabsorbent polymer is foamed may vary depending on the manufacturing conditions of the superabsorbent polymer, so it is difficult to define it as one form. Therefore, by first foaming the encapsulated blowing agent in the air, the expansion ratio and size can be checked to confirm whether it is suitable for forming desired pores.
  • the encapsulated foaming agent may have an average diameter of 2 to 50 ⁇ m, or 5 to 30 ⁇ m, or 5 to 20 ⁇ m, or 7 to 17 ⁇ m. When the encapsulated foaming agent exhibits such an average diameter, it can be judged to be suitable for achieving an appropriate porosity.
  • the method of manufacturing the superabsorbent polymer sheet of the present invention It can be judged to be suitable for forming a suitable open pore structure.
  • the maximum expansion ratio and the maximum expansion diameter of the encapsulated foaming agent may be measured by a method of analyzing the shape of pores formed in the prepared superabsorbent polymer sheet with a scanning electron microscope (SEM).
  • the hydrocarbons constituting the core of the encapsulated blowing agent are n-propane, n-butane, iso-butane, cyclobutane, n-pentane, iso-pentane, cyclopentane, n-hexane, iso-hexane, cyclohexane, n- It may be one or more selected from the group consisting of heptane, iso-heptane, cycloheptane, n-octane, iso-octane and cyclooctane.
  • hydrocarbons having 3 to 5 carbon atoms are suitable for forming pores of the size described above, and iso- Butane may be the most suitable.
  • thermoplastic resin constituting the shell of the encapsulated foaming agent is formed from at least one monomer selected from the group consisting of (meth) acrylate, (meth) acrylonitrile, aromatic vinyl, vinyl acetate, vinyl halide, and vinylidene halide. It can be a polymer. Among them, a copolymer of (meth) acrylate and (meth) acrylonitrile may be most suitable for forming pores of the size described above.
  • the encapsulated blowing agent may contain 10 to 30% by weight of hydrocarbons based on the total encapsulated blowing agent weight. It may be best suited to form an open pore structure within this range.
  • the encapsulated foaming agent may be prepared and used, or a commercialized foaming agent satisfying the above-described conditions may be used.
  • the content of the encapsulated foaming agent may be 0.3 to 20 parts by weight, preferably 0.5 to 10 parts by weight, and more preferably 1 to 10 parts by weight based on 100 parts by weight of the acrylic acid-based monomer. If the content of the encapsulated foaming agent is too small, an open pore structure may not be properly formed, an adequate porosity may not be secured, and if it is included too much, the porosity is too high, so that the strength of the super absorbent polymer may be weakened. In this respect, the content range may be preferred.
  • the inorganic blowing agent preferably has a diameter of 10 to 1000 nm, and 20 to 500 nm, or 50 to 100 nm may be more preferable.
  • the inorganic foaming agent in the above range may serve to collapse the boundary between the pores generated by the encapsulated foaming agent by forming a microporous channel, thereby greatly improving the absorbent capacity of the superabsorbent polymer sheet.
  • the diameter of the inorganic blowing agent can be measured through a scanning electron microscope (SEM).
  • the inorganic blowing agent may be used without limitation, a substance commonly known as a blowing agent, specifically, calcium carbonate (CaCO 3 ), sodium bicarbonate (NaHCO 3 ), ammonium bicarbonate (NH 4 HCO 3 ), ammonium carbonate ((NH 4 ) 2 CO 3 ), ammonium nitrite (NH 4 NO 2 ), one or more selected from sodium borohydride (NaBH 4 ) and sodium carbonate (Na 2 CO 3 ) may be used.
  • calcium carbonate can be preferably used when considering the stability characteristics in the neutralizing solution.
  • the content of the inorganic blowing agent may be used in an amount of 0.1 part by weight or more based on 100 parts by weight of the acrylic acid-based monomer, preferably 0.2 to 10 parts by weight, and more preferably 0.3 to 5 parts by weight. If the content of the inorganic foaming agent is too small, there may be a problem that closed pores are formed, and if too large, the mechanical strength may be lowered due to high porosity.
  • the mixing ratio of the encapsulated foaming agent and the inorganic foaming agent is preferably 3: 1 to 1: 1 by weight, and more preferably 2: 1 to 1: 1. Within this range, a high porosity and mechanical strength improvement effect can be obtained, and accordingly, the centrifugal water retention capacity and the pressure absorption capacity of the superabsorbent polymer sheet produced can be improved.
  • the encapsulated foaming agent and the inorganic foaming agent are contained in an amount of 20 parts by weight or less based on 100 parts by weight of the acrylic acid monomer, and more preferably in the range of 0.4 to 20 parts by weight, 0.7 to 10 parts by weight, or 1 to 5 parts by weight. .
  • the total content of the blowing agent is too large, the foaming degree is too high, so the strength of the superabsorbent polymer may be lowered, and if it is included too little, it is preferable to satisfy the above range because it is difficult to form an open pore structure.
  • the polymerization initiator used in polymerization in the method for producing a superabsorbent polymer sheet of the present invention is not particularly limited as long as it is generally used for the production of superabsorbent polymers.
  • the polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator according to UV irradiation depending on the polymerization method.
  • a thermal polymerization initiator may be additionally included.
  • the photopolymerization initiator is a compound capable of forming radicals by light such as ultraviolet rays
  • the composition may be used without limitation.
  • the photopolymerization initiator includes, for example, benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, and benzyl dimethyl ketal. Ketal), acyl phosphine (alpha) and one or more selected from the group consisting of alpha-aminoketone ( ⁇ -aminoketone).
  • acylphosphine a commercially available lucirin TPO, that is, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide (2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide) can be used.
  • Reinhold Schwalm's book "UV Coatings: Basics, Recent Developments and New Application (Elsevier 2007)" for more diverse photoinitiators p. It is well specified in 115, and is not limited to the above-described example.
  • the photopolymerization initiator may be included in a concentration of about 0.01 to about 1.0% by weight relative to the monomer composition. If the concentration of the photopolymerization initiator is too low, the polymerization rate may be slow, and if the concentration of the photopolymerization initiator is too high, the molecular weight of the super absorbent polymer may be small and the properties may be uneven.
  • thermal polymerization initiator one or more selected from the group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid may be used.
  • a persulfate-based initiator 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
  • examples of the azo-based initiator are 2,2-azobis- (2-amidinopropane) dihydrochloride (2,2-azobis (2-amidinopropane) dihydrochloride), 2 , 2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride (2-Azobis- (N, N-dimethylene) isobutyramidine dihydrochloride), 2- (carbamoyl azo) isobutyronit
  • the thermal polymerization initiator may be included in a concentration of about 0.001 to about 0.5% by weight relative to the monomer composition. If the concentration of the thermal polymerization initiator is too low, the additional thermal polymerization hardly occurs, so the effect of adding the thermal polymerization initiator may be negligible. If the concentration of the thermal polymerization initiator is too high, the molecular weight of the super absorbent polymer may be small and the physical properties may be uneven. have.
  • the monomer composition may further include additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.
  • Raw materials such as the acrylic acid-based unsaturated monomer, comonomer, internal crosslinking agent, polymerization initiator, and additives, may be prepared in the form of a solution of a monomer composition dissolved in a solvent.
  • the solvent may be included in the remaining amount excluding the above-mentioned components with respect to the total content of the monomer composition.
  • the solvent that can be used can be used without limitation of its composition as long as it can dissolve the aforementioned 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 ether , Toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, and N, N-dimethylacetamide.
  • the monomer composition is thermally polymerized or photopolymerized to form a hydrogel polymer.
  • the method of forming a hydrogel polymer by thermal polymerization or photopolymerization of such a monomer composition is not particularly limited as long as it is a polymerization method commonly used in the field of superabsorbent polymer production.
  • the polymerization method can be largely divided into thermal polymerization and photo polymerization depending on the polymerization energy source.
  • thermal polymerization it may be carried out in a reactor having a stirring shaft such as a kneader.
  • photopolymerization it may be performed in a reactor equipped with a movable conveyor belt, but the polymerization method described above is an example, and the present invention is not limited to the polymerization method described above.
  • the thermal polymerization or photopolymerization reaction temperature of the monomer composition is not particularly limited, but may be, for example, 80 to 120 ° C, preferably 90 to 110 ° C.
  • the normal water content of the hydrogel polymer obtained in this way may be about 40 to about 80% by weight.
  • the "water content" of the hydrogel polymer refers to a value obtained by subtracting the weight of the polymer in the dry state from the weight of the hydrogel polymer as the amount of moisture that accounts for the total weight of the hydrogel polymer. Specifically, it is defined as a calculated value by measuring the weight loss due to evaporation of water in the polymer during the drying process by raising the temperature of the polymer through infrared heating.
  • the drying condition is a method of raising the temperature from room temperature to about 180 ° C and then maintaining it at 180 ° C.
  • the total drying time is set to 20 minutes including 5 minutes of the temperature rise step to measure the water content.
  • the hydrogel polymer is molded into a sheet and dried to form a super absorbent polymer sheet.
  • foaming by the blowing agent may occur, and accordingly, microporous channels may be formed between the main pores in the superabsorbent polymer sheet, thereby forming open pore channels.
  • the drying temperature of the drying step may be about 120 to about 250 °C.
  • the drying temperature is less than about 120 ° C, the drying time is too long and there is a fear that the physical properties of the superabsorbent polymer finally formed are deteriorated.
  • the drying temperature exceeds about 250 ° C, only the polymer surface is excessively dried, resulting in final formation. There is a possibility that the physical properties of the superabsorbent polymer to be deteriorated. Therefore, preferably, the drying may be performed at a temperature of about 120 to about 250 ° C, more preferably at a temperature of about 140 to about 200 ° C.
  • process efficiency and the like may be considered, but may be performed for about 20 to about 90 minutes, but is not limited thereto.
  • the drying method of the drying step is also commonly used as a drying process of the hydrogel polymer, it can be selected and used without limitation of its configuration. Specifically, the drying step may be performed by a method such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation.
  • a process of exposing the dried superabsorbent polymer sheet to hot steam at 80 to 100 ° C. may be further performed to achieve a proper moisture content of the superabsorbent polymer sheet.
  • the moisture content of the superabsorbent polymer sheet after the drying step is performed may be about 10 wt% or more, for example, about 10 to about 40 wt%, or about 15 to about 30 wt%.
  • the method for measuring the moisture content of the superabsorbent polymer sheet may be more specific in the examples described below.
  • the thickness of the superabsorbent polymer sheet obtained by the above-described process may be about 100 ⁇ m or more, or 1,000 ⁇ m, or 5,000 ⁇ m, and may be about 10 cm or less, or about 5 cm or less, or about 1 cm or less. have. If the thickness of the superabsorbent polymer sheet is too thin, the strength may be low and the sheet may be torn, and if it is too thick, drying and processing may be difficult. From this point of view, it may be desirable to have the aforementioned thickness range.
  • the superabsorbent polymer sheet manufactured according to the above-described manufacturing method is in the form of a sheet having an open pore channel structure in which at least a portion of the pores are connected to each other, absorption of water by capillary pressure is possible. .
  • the absorption rate and permeability can be improved compared to the conventional superabsorbent resin in powder form, and can be used as it is as a pulfree absorbent.
  • a superabsorbent polymer sheet obtained by the above manufacturing method is provided.
  • the superabsorbent polymer sheet has an acidic group, and an acrylic acid monomer in which at least a portion of the acidic group is neutralized includes a crosslinked polymer crosslinked in the presence of an internal crosslinking agent containing polyol, an encapsulating foaming agent, and an inorganic foaming agent. do.
  • the superabsorbent polymer sheet has an open pore channel structure in which at least a portion of pores are connected to each other, whereby absorption of water by capillary pressure is possible.
  • the superabsorbent polymer sheet has a centrifugal water retention capacity (CRC) measured according to EDANA method WSP 241.2 of 10 g / g or more, 15 g / g or more, or 20 g / g or more, and 40 g / g or less, 30 g / g or less, or 25 g / g or less.
  • CRC centrifugal water retention capacity
  • the superabsorbent polymer sheet has a pressurized absorption capacity (AUP) of 0.7 g or more, 7 g / g or more, or 7 g / g or more, or 9 g / g or more, and 20 g / g or less, measured according to EDANA method WSP 242.2. , Or 15 g / g or less.
  • AUP pressurized absorption capacity
  • the superabsorbent polymer sheet has an expansion rate of 200% or more, 250% or more, or 300% or more, which is measured by comparing the areas before and after drying, and is high as 600% or less, 550% or less, or 500% or less. It exhibits excellent flexibility.
  • the monomer composition was mixed with high shear at a rate of 500 rpm for about 10 minutes using a mechanical mixer.
  • polymerization was performed through the supply of the polymerizer to form a hydrogel polymer.
  • the temperature of the polymerization reactor was maintained at 100 ° C, the highest temperature of polymerization was 110 ° C, and the polymerization time was 10 minutes.
  • Example 1 a superabsorbent polymer sheet was prepared in the same manner as in Example 1, except that 1.5% by weight of each of 100% by weight of acrylic acid and an encapsulated foaming agent and a calcium carbonate foaming agent were used.
  • Example 2 a superabsorbent polymer sheet was prepared in the same manner as in Example 2, except that the encapsulated blowing agent and the inorganic blowing agent were not used.
  • Example 2 a super absorbent polymer sheet was prepared in the same manner as in Example 2, except that an inorganic foaming agent was not used.
  • Example 2 a superabsorbent polymer sheet was prepared in the same manner as in Example 2, except that the encapsulated blowing agent was not used.
  • Example 2 instead of glycerol and polyethylene glycol diacrylate as an internal crosslinking agent, a superabsorbent polymer sheet was prepared in the same manner as in Example 2, except that only 12.09 g of polyethylene glycol diacrylate was used.
  • FIG. 1 A scanning electron microscope (SEM) photograph of a cross section of a super absorbent polymer sheet according to Example 1 of the present invention is shown in FIG. 1. Referring to Figure 1, it can be seen that an open pore channel structure is formed on the superabsorbent polymer sheet surface according to the first embodiment of the present invention.
  • Comparative Example 1 without a blowing agent does not have a porous structure.
  • Figure 2 is a result of testing the degree of flexibility by winding the sheets of Example 1 and Comparative Example 2 in a vial having a diameter of 25 mm.
  • the sheet of Example 1 is excellent in flexibility and adheres to the curved surface of the vial.
  • Comparative Example 2 it was confirmed that the flexibility was poor and the vial did not adhere.
  • the centrifugal water retention capacity was measured according to the method of EDANA method WSP 241.2.
  • Pressure absorption capacity (AUP) under 0.7 psi was measured according to the method of EDANA method WSP 242.2.
  • the superabsorbent polymer sheet of the embodiment has superior flexibility, superior porosity, and expansion coefficient characteristics compared to the sheet of the comparative example having a similar water content, and accordingly, the absorption properties of CRC, AUP, etc. are also compared to the comparative example. It can be confirmed that it is remarkably excellent.

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Abstract

The present invention relates to a preparation method for a superabsorbent polymer sheet. According to the manufacturing method for a super absorbent resin sheet of the present invention, a porous flexible superabsorbent polymer sheet can be prepared.

Description

고흡수성 수지 시트의 제조 방법Manufacturing method of super absorbent polymer sheet
관련 출원(들)과의 상호 인용Cross-citation with relevant application (s)
본 출원은 2018년 9월 27일자 한국 특허 출원 제10-2018-0115311호 및 2019년 9월 6일자 한국 특허 출원 제10-2019-0110999호에 기초한 우선권의 이익을 주장하며, 해당 한국 특허 출원의 문헌에 개시된 모든 내용은 본 명세서의 일부로서 포함된다.This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0115311 dated September 27, 2018 and Korean Patent Application No. 10-2019-0110999 dated September 6, 2019. All content disclosed in the literature is incorporated as part of this specification.
본 발명은 고흡수성 수지 시트의 제조 방법에 관한 것이다.The present invention relates to a method for producing a super absorbent polymer sheet.
고흡수성 수지(Super Absorbent Polymer, SAP)란 자체 무게의 5백 내지 1천 배 정도의 수분을 흡수할 수 있는 기능을 가진 합성 고분자 물질로서, 개발업체마다 SAM(Super Absorbency Material), AGM(Absorbent Gel Material) 등 각기 다른 이름으로 명명하고 있다. 상기와 같은 고흡수성 수지는 생리용구로 실용화되기 시작해서, 현재는 어린이용 종이기저귀나 생리대 등 위생용품 외에 원예용 토양보수제, 토목, 건축용 지수재, 육묘용 시트, 식품유통분야에서의 신선도 유지제, 및 찜질용 등의 재료로 널리 사용되고 있다.Super Absorbent Polymer (SAP) is a synthetic polymer material that has the ability to absorb about 500 to 1,000 times its own weight.Sam (Super Absorbency Material), AGM (Absorbent Gel) for each developer Material). The superabsorbent polymer as described above began to be put into practical use as a sanitary tool, and now, in addition to sanitary products such as children's paper diapers and sanitary napkins, soil repair agents for horticulture, civil engineering, construction materials, nursery sheets, and freshness retention agents in the food distribution field , And is widely used as a material for poultice.
일반적으로 각종 기저귀, 생리대 또는 실금용 패드 등의 위생용품에는 고흡수성 수지 입자를 포함한 흡수체가 포함되는데, 이러한 흡수체는 주로 상기 고흡수성 수지 입자와, 이러한 고흡수성 수지 입자를 적절히 고정하면서도 상기 흡수체 및 위생용품의 형태를 유지시키기 위해 플러프 펄프(fluff pulp)를 사용하는 것이 일반적이었다.In general, hygiene products such as various diapers, sanitary napkins, or incontinence pads include absorbents including superabsorbent polymer particles, and these absorbents are mainly the superabsorbent polymer particles and the superabsorbent polymer particles are properly fixed while the absorbent and hygiene It was common to use fluff pulp to maintain the shape of the article.
그러나, 이러한 플러프 펄프의 존재로 인해, 흡수체 및 위생용품의 슬림화 및 박형화가 어려웠고, 사용자의 피부와 위생용품의 사이에 땀이 차는 등 착용감이 떨어지는 문제점이 있었다. 더구나, 주로 목재를 원료로 얻어지는 상기 플러프 펄프의 다량 사용 필요성으로 인해, 최근의 환경보호 시류에 역행하는 점이 있었고, 상기 흡수층 및 위생용품의 제조 단가를 높이는 주원인 중에 하나가 되었다.However, due to the presence of the fluff pulp, it has been difficult to slim and thin the absorbent body and the hygiene product, and there is a problem in that the user feels poor, such as sweating between the skin and the hygiene product. Moreover, due to the necessity of using a large amount of the fluff pulp obtained mainly from wood, there has been a point that goes against the recent environmental protection trend, and has become one of the main reasons for increasing the manufacturing cost of the absorbent layer and sanitary products.
이 때문에, 상기 흡수층 및 위생용품에 있어서, 플러프 펄프의 사용량을 줄이거나, 플러프 펄프를 사용하지 않은 소위 펄프리스(pulpless) 기저귀 등의 위생용품을 제공하기 위해 많은 시도가 이루어지고 있다.For this reason, in the absorbent layer and the hygiene product, many attempts have been made to reduce the amount of fluff pulp or to provide a hygiene product such as a so-called pulpless diaper that does not use fluff pulp.
한편 현재의 고흡수성 수지는 대부분 분말(powder) 형태로 제조되어 사용되고 있다. 이러한 분말 형태의 고흡수성 수지는 위생재를 제조할 때나 실제 사용 시 비산되거나 누출될 수 있는 부분이 있고, 특정 형태의 기질(substrate)과 함께 사용되어야 하기 때문에 사용 범위의 제한이 있는 실정이다.Meanwhile, the current superabsorbent polymer is mostly used in the form of a powder. The superabsorbent polymer in the form of powder has a portion that can be scattered or leaked when manufacturing hygiene materials or in actual use, and is limited in scope of use because it must be used with a specific type of substrate.
이에 최근에는 고흡수성 수지를 섬유(fiber) 또는 부직포 형태로 제조하는 방법이 제안되고 있다. 그러나 흡수 성능의 저하가 없고 펄프리스 흡수체로 사용할 수 있으며, 충분한 유연성을 나타내는 고흡수성 수지를 확보하기 위한 방안이 미흡하여 이의 제조 방법에 대한 연구가 여전히 요구된다.Accordingly, recently, a method of manufacturing a super absorbent polymer in the form of a fiber or a nonwoven fabric has been proposed. However, there is no deterioration in the absorption performance, and it can be used as a pulfree absorber, and a method for securing a super absorbent polymer exhibiting sufficient flexibility is insufficient, and thus a study on its manufacturing method is still required.
상기와 같은 과제를 해결하기 위한 것으로, 본 발명은 높은 가요성 및 빠른 흡수 속도를 나타내고 감촉이 우수한 고흡수성 수지 시트의 제조 방법을 제공한다.In order to solve the above problems, the present invention provides a method for producing a super absorbent polymer sheet exhibiting high flexibility and fast absorption speed and excellent texture.
상기와 같은 과제를 해결하기 위하여 본 발명은,The present invention to solve the above problems,
산성기를 가지며 상기 산성기의 적어도 일부가 중화된 아크릴산계 단량체, 폴리올(polyol)을 포함하는 내부 가교제, 캡슐화된 발포제, 무기 발포제, 및 중합 개시제를 혼합하여 모노머 조성물을 제조하는 단계;Preparing an monomer composition by mixing an acrylic acid-based monomer having an acidic group and at least a part of the acidic group being neutralized, an internal crosslinking agent containing polyol, an encapsulating foaming agent, an inorganic foaming agent, and a polymerization initiator;
상기 모노머 조성물을 열중합 또는 광중합하여 함수겔 중합체를 형성하는 단계; 및Thermally or photopolymerizing the monomer composition to form a hydrogel polymer; And
상기 함수겔 중합체를 건조하는 단계를 포함하는 고흡수성 수지 시트의 제조방법을 제공한다.It provides a method for producing a super absorbent polymer sheet comprising the step of drying the hydrogel polymer.
상기 폴리올(polyol)은 에틸렌 글리콜, 프로필렌 글리콜, 1,3-프로판디올, 1,4-부탄디올, 1,6-헥산디올, 1,2-헥산디올, 1,3-헥산디올, 2-메틸-1,3-프로판디올, 2,5-헥산디올, 2-메틸-1,3-펜탄디올, 2-메틸-2,4-펜탄디올, 트리프로필렌 글리콜 및 글리세롤로 이루어진 군으로부터 선택되는 1종 이상을 포함할 수 있다.The polyol is ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl- 1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, at least one member selected from the group consisting of tripropylene glycol and glycerol It may include.
상기 폴리올(polyol)은 상기 아크릴산계 단량체 100 중량부에 대하여 10 내지 80 중량부로 포함될 수 있다.The polyol may be included in an amount of 10 to 80 parts by weight based on 100 parts by weight of the acrylic monomer.
상기 캡슐화된 발포제는 평균 직경이 2 내지 50 ㎛일 수 있다.The encapsulated foaming agent may have an average diameter of 2 to 50 μm.
상기 캡슐화된 발포제는 공기 중 팽창 비율이 3 내지 15 배일 수 있다.The encapsulating blowing agent may have an expansion ratio of 3 to 15 times in air.
상기 캡슐화된 발포제는 탄화수소를 포함하는 코어와 상기 코어를 둘러싸며 열가소성 수지로 형성되는 쉘을 포함하는 구조를 가지는 것일 수 있다.The encapsulated foaming agent may have a structure including a core including a hydrocarbon and a shell surrounding the core and formed of a thermoplastic resin.
이때, 상기 탄화수소는 n-프로판, n-부탄, iso-부탄, 사이클로부탄, n-펜탄, iso-펜탄, 사이클로펜탄, n-헥산, iso-헥산, 사이클로헥산, n-헵탄, iso-헵탄, 사이클로헵탄, n-옥탄, iso-옥탄 및 사이클로옥탄으로 구성된 군에서 선택된 1 종 이상일 수 있고, 상기 열가소성 수지는 (메트)아크릴레이트, (메트)아크릴로니트릴, 방향족 비닐, 초산 비닐, 할로겐화 비닐 및 할로겐화 비닐리덴으로 구성된 군에서 선택된 1 종 이상의 모노머로부터 형성되는 폴리머일 수 있다.In this case, the hydrocarbon is n-propane, n-butane, iso-butane, cyclobutane, n-pentane, iso-pentane, cyclopentane, n-hexane, iso-hexane, cyclohexane, n-heptane, iso-heptane, Cycloheptane, n-octane, iso-octane and cyclooctane may be one or more selected from the group consisting of, the thermoplastic resin is (meth) acrylate, (meth) acrylonitrile, aromatic vinyl, vinyl acetate, vinyl halide and It may be a polymer formed from one or more monomers selected from the group consisting of vinylidene halide.
상기 무기 발포제는 탄산칼슘(CaCO3), 중탄산나트륨(NaHCO3), 중탄산암모늄(NH4HCO3), 탄산암모늄((NH4)2CO3), 아질산암모늄(NH4NO2), 붕소화수소나트륨 (NaBH4) 및 탄산나트륨(Na2CO3) 중 선택되는 1종 이상일 수 있다.The inorganic blowing agent is calcium carbonate (CaCO 3 ), sodium bicarbonate (NaHCO 3 ), ammonium bicarbonate (NH 4 HCO 3 ), ammonium carbonate ((NH 4 ) 2 CO 3 ), ammonium nitrite (NH 4 NO 2 ), hydrogen borohydride It may be one or more selected from sodium (NaBH 4 ) and sodium carbonate (Na 2 CO 3 ).
상기 캡슐화된 발포제와 무기 발포제는 3:1 내지 1:1의 중량비로 포함될 수 있다.The encapsulated foaming agent and the inorganic foaming agent may be included in a weight ratio of 3: 1 to 1: 1.
상기 캡슐화된 발포제는 아크릴산계 단량체 100 중량부에 대하여 0.3 내지 20 중량부로 포함될 수 있다.The encapsulated foaming agent may be included in an amount of 0.3 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.
상기 무기 발포제는 아크릴산계 단량체 100 중량부에 대하여 0.2 내지 10 중량부로 포함될 수 있다.The inorganic blowing agent may be included in 0.2 to 10 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.
본 발명의 다른 일 측면에 따르면, 산성기를 가지며 상기 산성기의 적어도 일부가 중화된 아크릴산계 단량체가, 폴리올(polyol)을 포함하는 내부 가교제, 캡슐화된 발포제, 및 무기 발포제의 존재 하에 가교 중합된 가교 중합체를 포함하는 고흡수성 수지 시트가 제공된다.According to another aspect of the present invention, an acrylic acid-based monomer having an acidic group and neutralized at least a portion of the acidic group is crosslinked and polymerized in the presence of an internal crosslinking agent containing a polyol, an encapsulating foaming agent, and an inorganic foaming agent. A superabsorbent polymer resin sheet is provided.
상기 고흡수성 수지 시트는 EDANA 법 WSP 241.2에 따라 측정된 원심분리 보수능(CRC)이 10 g/g 내지 40 g/g일 수 있다.The superabsorbent polymer sheet may have a centrifugal water retention capacity (CRC) of 10 g / g to 40 g / g measured according to EDANA method WSP 241.2.
상기 고흡수성 수지 시트는 EDANA 법 WSP 242.2에 따라 측정된 0.7 psi 하에서의 가압 흡수능(AUP)이 5 g/g 내지 20 g/g일 수 있다.The superabsorbent polymer sheet may have a pressure absorbing capacity (AUP) of 0.7 g to 20 g / g under 0.7 psi measured according to EDANA method WSP 242.2.
상기 고흡수성 수지 시트는 가로 * 세로 * 두께 = 50 mm * 50 mm * 2 mm로 재단된 고흡수성 수지 시트의 가로 * 세로 면적과, 이를 180℃ 온도에서 5분 동안 건조한 후의 고흡수성 수지 시트의 가로 * 세로 면적으로 정의되는 팽창률이 200 % 이상일 수 있다.The superabsorbent polymer sheet is transverse * vertical * thickness = 50 mm * 50 mm * 2 mm transverse * vertical area of the superabsorbent polymer sheet, and the superabsorbent polymer sheet after drying at 180 ° C. for 5 minutes. * The expansion rate defined by the vertical area may be 200% or more.
본 발명의 제조방법에 의해 수득되는 고흡수성 수지 시트는 분말 상태의 통상의 고흡수성 수지와는 달리 시트 또는 필름 형태로 얻어지며, 제품으로 바로 적용이 가능하며 비산되거나 누출될 우려가 없고 우수한 감촉 및 유연성을 나타낼 수 있다.The superabsorbent polymer sheet obtained by the manufacturing method of the present invention is obtained in the form of a sheet or film, unlike the ordinary superabsorbent polymer in powder form, and can be applied directly to a product, and has no fear of scattering or leaking. It can show flexibility.
또한, 본 발명의 고흡수성 수지 시트의 제조방법에 의해 수득되는 고흡수성 수지 시트는 공극이 서로 연결되어 있는 열린 기공 채널(open pore channel) 구조를 가지며, 이에 의해 모세관 압력(capillary pressure)에 의한 물의 흡수가 가능하므로, 흡수 속도 및 투과성이 향상될 수 있다.In addition, the superabsorbent polymer sheet obtained by the method of manufacturing the superabsorbent polymer sheet of the present invention has an open pore channel structure in which pores are connected to each other, whereby water is absorbed by capillary pressure. Since absorption is possible, absorption rate and permeability can be improved.
이처럼, 유연성과 가요성을 가지면서 고흡수성 수지 본연의 물성으로 빠른 흡수 속도를 나타내어, 가요성 및 높은 흡수성을 필요로 하는 다양한 제품에 적용 가능하다.As described above, it has a flexibility and flexibility, and exhibits a high absorption rate as a natural property of a super absorbent polymer, and is applicable to various products requiring flexibility and high absorption.
또한, 상기 고흡수성 수지 시트는 펄프리스 흡수체로 이용할 수 있다.In addition, the superabsorbent polymer sheet can be used as a pulfree absorber.
도 1은 본 발명의 일 실시예에 따라 제조된 고흡수성 수지 시트의 단면을 촬영한 주사전자현미경(SEM) 사진이다.1 is a scanning electron microscope (SEM) photograph of a cross section of a super absorbent polymer sheet manufactured according to an embodiment of the present invention.
도 2는 실시예 1 및 비교예 2의 고흡수성 수지 시트의 유연성을 테스트한 사진이다.2 is a photograph of testing the flexibility of the superabsorbent polymer sheet of Example 1 and Comparative Example 2.
본 발명은 다양한 변경을 가할 수 있고 여러 가지 형태를 가질 수 있는 바, 특정 실시예들을 예시하고 하기에서 상세하게 설명하고자 한다. 그러나, 이는 본 발명을 특정한 개시 형태에 대해 한정하려는 것이 아니며, 본 발명의 사상 및 기술 범위에 포함되는 모든 변경, 균등물 내지 대체물을 포함하는 것으로 이해되어야 한다.The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosure form, and it should be understood that all modifications, equivalents, and substitutes included in the spirit and scope of the present invention are included.
이하, 본 발명의 일 구현예에 따른 고흡수성 수지 시트의 제조방법을 설명한다.Hereinafter, a method of manufacturing a super absorbent polymer sheet according to an embodiment of the present invention will be described.
본 발명의 일 구현예에 따르면, 산성기를 가지며 상기 산성기의 적어도 일부가 중화된 아크릴산계 단량체, 폴리올(polyol)을 포함하는 내부 가교제, 캡슐화된 발포제, 무기 발포제, 및 중합 개시제를 혼합하여 모노머 조성물을 제조하는 단계; 상기 모노머 조성물을 열중합 또는 광중합하여 함수겔 중합체를 형성하는 단계; 및 상기 함수겔 중합체를 건조하는 단계를 포함하는 고흡수성 수지 시트의 제조방법이 제공된다.According to an embodiment of the present invention, the monomer composition is obtained by mixing an acrylic acid-based monomer having an acidic group and at least a portion of the acidic group being neutralized, an internal crosslinking agent containing polyol, an encapsulating foaming agent, an inorganic foaming agent, and a polymerization initiator. Preparing a; Thermally or photopolymerizing the monomer composition to form a hydrogel polymer; And it provides a method for producing a super absorbent polymer sheet comprising the step of drying the hydrogel polymer.
본 발명의 제조방법에 있어, 상기 고흡수성 수지의 원료 물질인 모노머 조성물은 산성기를 가지며 상기 산성기의 적어도 일부가 중화된 아크릴산계 단량체, 폴리올(polyol)을 포함하는 내부 가교제, 캡슐화된 발포제, 무기 발포제, 및 중합 개시제를 포함한다.In the manufacturing method of the present invention, the monomer composition, which is a raw material of the super absorbent polymer, has an acidic group, and at least a part of the acidic group is an acrylic acid-based monomer, a polyol, an internal crosslinking agent, an encapsulated foaming agent, an inorganic Foaming agents, and polymerization initiators.
먼저, 상기 아크릴산계 단량체는 하기 화학식 1로 표시되는 화합물이다:First, the acrylic acid monomer is a compound represented by Formula 1 below:
[화학식 1][Formula 1]
R1-COOM1 R 1 -COOM 1
상기 화학식 1에서,In Chemical Formula 1,
R1은 불포화 결합을 포함하는 탄소수 2 내지 5의 알킬 그룹이고,R 1 is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond,
M1은 수소원자, 1가 또는 2가 금속, 암모늄기 또는 유기 아민염이다.M 1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt.
바람직하게는, 상기 아크릴산계 단량체는 아크릴산, 메타크릴산 및 이들의 1가 금속염, 2가 금속염, 암모늄염 및 유기 아민염으로 이루어진 군으로부터 선택되는 1종 이상을 포함한다.Preferably, the acrylic acid-based monomer includes at least one selected from the group consisting of acrylic acid, methacrylic acid and their monovalent metal salt, divalent metal salt, ammonium salt and organic amine salt.
여기서, 상기 아크릴산계 단량체는 산성기를 가지며 상기 산성기의 적어도 일부가 중화된 것일 수 있다. 바람직하게는 상기 단량체를 수산화나트륨, 수산화칼륨, 수산화암모늄 등과 같은 알칼리 물질로 부분적으로 중화시킨 것이 사용될 수 있다. 이때, 상기 아크릴산계 단량체의 중화도는 40 내지 95 몰%, 또는 40 내지 80 몰%, 또는 45 내지 75 몰%일 수 있다. 상기 중화도의 범위는 최종 물성에 따라 조절될 수 있다. 그런데, 상기 중화도가 지나치게 높으면 중화된 단량체가 석출되어 중합이 원활하게 진행되기 어려울 수 있으며, 반대로 중화도가 지나치게 낮으면 고분자의 흡수력이 크게 떨어질 뿐만 아니라 취급하기 곤란한 탄성 고무와 같은 성질을 나타낼 수 있다.Here, the acrylic acid monomer may have an acidic group and at least a part of the acidic group may be neutralized. Preferably, the monomer may be partially neutralized with an alkali material such as sodium hydroxide, potassium hydroxide or ammonium hydroxide. At this time, the degree of neutralization of the acrylic acid-based monomer may be 40 to 95 mol%, or 40 to 80 mol%, or 45 to 75 mol%. The range of the neutralization degree can be adjusted according to the final physical properties. However, if the degree of neutralization is too high, the neutralized monomer may be precipitated and polymerization may be difficult to proceed smoothly. On the contrary, if the degree of neutralization is too low, it may exhibit properties such as elastic rubber that is not only poorly absorbed but also difficult to handle. have.
상기 아크릴산계 단량체의 농도는, 상기 고흡수성 수지의 원료 물질 및 용매를 포함하는 모노머 조성물에 대해 약 20 내지 약 60 중량%, 바람직하게는 약 40 내지 약 50 중량%로 될 수 있으며, 중합 시간 및 반응 조건 등을 고려해 적절한 농도로 될 수 있다. 다만, 상기 단량체의 농도가 지나치게 낮아지면 고흡수성 수지의 수율이 낮고 경제성에 문제가 생길 수 있고, 반대로 농도가 지나치게 높아지면 단량체의 일부가 석출되거나 중합된 함수겔상 중합체의 분쇄 시 분쇄 효율이 낮게 나타나는 등 공정상 문제가 생길 수 있으며 고흡수성 수지의 물성이 저하될 수 있다.The concentration of the acrylic acid-based monomer, may be about 20 to about 60% by weight, preferably about 40 to about 50% by weight relative to the monomer composition containing the raw material and solvent of the superabsorbent polymer, polymerization time and It may be an appropriate concentration in consideration of reaction conditions and the like. However, if the concentration of the monomer is too low, the yield of the superabsorbent polymer may be low and economic problems may occur. Conversely, if the concentration is too high, a part of the monomer precipitates or the grinding efficiency of the polymerized hydrogel polymer is low. Such problems may occur in the process, and physical properties of the super absorbent polymer may be deteriorated.
본 발명의 모노머 조성물은 내부 가교제로 폴리올을 포함한다.The monomer composition of the present invention contains a polyol as an internal crosslinking agent.
상기 폴리올은, 상기 아크릴산계 단량체와 가교 반응하여 유연성 있는 고분자 구조를 형성하며, 또한 흡습성으로 인해 고흡수성 수지 시트의 함수율을 증가시키는데 기여할 수 있다.The polyol cross-links with the acrylic acid monomer to form a flexible polymer structure, and also contributes to increase the moisture content of the super absorbent polymer sheet due to hygroscopicity.
사용 가능한 폴리올의 예로는, 에틸렌 글리콜, 프로필렌 글리콜, 1,3-프로판디올, 1,4-부탄디올, 1,6-헥산디올, 1,2-헥산디올, 1,3-헥산디올, 2-메틸-1,3-프로판디올, 2,5-헥산디올, 2-메틸-1,3-펜탄디올, 2-메틸-2,4-펜탄디올, 트리프로필렌 글리콜 또는 글리세롤을 들 수 있으며, 바람직하게는 글리세롤을 사용할 수 있다.Examples of usable polyols are ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl -1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, tripropylene glycol or glycerol, preferably. Glycerol can be used.
상기 폴리올의 함량은 아크릴산계 단량체의 100 중량부에 대하여 10 내지 80 중량부, 바람직하게는 20 내지 50 중량부, 더욱 바람직하게는 30 내지 40 중량부를 사용할 수 있다. 상기 폴리올의 함량이 지나치게 적으면, 함수율 향상의 효과가 없을 수 있고, 너무 많이 포함되는 경우, 흡수 속도, 및 흡수능의 저하가 있을 수 있으므로 이러한 관점에서 상기 함량 범위가 바람직할 수 있다.The content of the polyol may be 10 to 80 parts by weight, preferably 20 to 50 parts by weight, more preferably 30 to 40 parts by weight based on 100 parts by weight of the acrylic acid monomer. If the content of the polyol is too small, there may be no effect of improving the water content, and when it is included too much, the content range may be preferable from this point of view since absorption speed and absorption capacity may be lowered.
본 발명의 모노머 조성물은 상기 폴리올 외에 다른 내부 가교제를 더 포함할 수 있다. 이때 내부 가교제로는 폴리올의 폴리(메트)아크릴레이트계 화합물, 예를 들어, 탄소수 2 내지 10의 폴리올의 폴리(메트)아크릴레이트계 화합물을 사용할 수 있다. 보다 구체적인 예로는, 트리메틸롤프로판 트리(메트)아크릴레이트, 에틸렌글리콜 디(메트)아크릴레이트, 폴리에틸렌글리콜 디(메트)아크릴레이트, 프로필렌글리콜 디(메트)아크릴레이트, 폴리프로필렌글리콜 디(메트)아크릴레이트, 부탄디올디(메트)아크릴레이트, 부틸렌글리콜디(메트)아크릴레이트, 디에틸렌글리콜 디(메트)아크릴레이트, 헥산디올디(메트)아크릴레이트, 트리에틸렌글리콜 디(메트)아크릴레이트, 트리프로필렌글리콜 디(메트)아크릴레이트, 테트라에틸렌글리콜 디(메트)아크릴레이트, 디펜타에리스리톨 펜타아크릴레이트, 글리세린 트리(메트)아크릴레이트 또는 펜타에리스톨 테트라아크릴레이트를 사용할 수 있으며, 바람직하게는, 폴리에틸렌글리콜 디아크릴레이트를 사용할 수 있다.The monomer composition of the present invention may further include an internal crosslinking agent other than the polyol. In this case, as the internal crosslinking agent, a poly (meth) acrylate-based compound of polyol, for example, a poly (meth) acrylate-based compound of polyol having 2 to 10 carbon atoms may be used. More specific examples include trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylic. Rate, butanediol di (meth) acrylate, butylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, tri Propylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerin tri (meth) acrylate or pentaerythritol tetraacrylate may be used, preferably polyethylene Glycol diacrylate can be used.
상기 내부 가교제는 모노머 조성물에 대하여 약 0.01 내지 약 2 중량%, 또는 0.1 내지 0.5 중량%의 농도로 포함되어, 중합된 고분자를 가교시킬 수 있다.The internal crosslinking agent may be included in a concentration of about 0.01 to about 2% by weight, or 0.1 to 0.5% by weight relative to the monomer composition, to crosslink the polymerized polymer.
본 발명의 모노머 조성물은 발포제를 포함하며, 이때 캡슐화된 발포제 및 무기 발포제를 동시에 포함한다. 이와 같이 두 종류의 발포제를 혼합 사용하는 경우 고흡수성 수지 시트의 높은 기공도 및 열린 기공을 얻을 수 있는 효과가 있다. 즉, 본 발명과 같이 캡슐화된 발포제 및 무기 발포제를 동시에 사용하는 경우, 캡슐화된 발포제에 의하여 고흡수성 수지 시트의 내부에 높은 기공도를 확보하기에 적절한 크기의 주 기공이 형성되며, 이러한 주 기공 사이에 무기 발포제에 의한 미세 기공 채널이 형성되면서 주 기공이 서로 연결되어 있는 열린 기공 채널(open pore channel) 구조를 확보할 수 있게 된다. 따라서, 미세 기공 채널 구조로 인해 모세관 압력(capillary pressure)에 의한 물의 신속한 흡수가 가능하며, 각 발포제를 단독 사용하는 경우에 비하여 제조되는 고흡수성 수지의 원심분리 보수능 및 가압 흡수능이 우수하게 나타난다. 뿐만 아니라, 상기 구조로 인하여 고흡수성 수지 시트의 유연성이 크게 증가할 수 있다.The monomer composition of the present invention includes a blowing agent, wherein the encapsulating blowing agent and the inorganic blowing agent are simultaneously included. When two types of foaming agents are used in this way, high porosity and open porosity of the superabsorbent polymer sheet can be obtained. That is, when the encapsulated foaming agent and the inorganic foaming agent are used at the same time as the present invention, the main pores of an appropriate size are formed in the inside of the superabsorbent polymer sheet by the encapsulated foaming agent, and between these main pores In the microporous channel formed by the inorganic foaming agent is formed, it is possible to secure an open pore channel structure in which main pores are connected to each other. Therefore, due to the micro-pore channel structure, rapid absorption of water by capillary pressure is possible, and the centrifugal water retention capacity and the pressure absorption capacity of the superabsorbent polymer prepared compared to the case of using each blowing agent alone are excellent. In addition, the flexibility of the superabsorbent polymer sheet can be greatly increased due to the above structure.
상기 캡슐화된 발포제는 모노머 조성물의 중합 시에는 캡슐화된 상태로 존재하며 열에 의하여 팽창하다가, 후술하는 건조 공정 시 가해지는 고온의 열에 의해 발포하게 되며, 이에 따라 고흡수성 수지의 고분자 구조 사이사이에 적절한 크기의 기공을 형성하여 고흡수성 수지 시트가 열린 기공 채널(open pore channel)의 구조를 나타낼 수 있도록 한다.The encapsulated foaming agent exists in an encapsulated state during polymerization of the monomer composition, expands by heat, and foams by high temperature heat applied during the drying process described below, and accordingly, a suitable size between the polymer structures of the super absorbent polymer. By forming the pores, the superabsorbent polymer sheet can exhibit the structure of an open pore channel.
상기 캡슐화된 발포제는 탄화수소를 포함하는 코어와 상기 코어를 둘러싸며 열가소성 수지로 형성되는 쉘을 포함하는 구조를 가질 수 있다. 이러한 캡슐화된 발포제는 상기 코어와 쉘을 이루는 성분과 각 성분의 중량, 직경에 따라 팽창 특성이 달라지며 이를 조절함으로써 원하는 크기로 팽창이 가능하며 상기 고흡수성 수지 시트의 다공성을 조절할 수 있다.The encapsulated foaming agent may have a structure including a core comprising a hydrocarbon and a shell surrounding the core and formed of a thermoplastic resin. The encapsulating foaming agent has different expansion characteristics depending on the weight and diameter of the components constituting the core and the shell, and can be expanded to a desired size by controlling it, and can control the porosity of the superabsorbent polymer sheet.
한편 원하는 크기의 기공이 형성되는지 여부를 파악하기 위해 먼저 캡슐화된 발포제의 팽창 특성을 파악할 필요가 있다. 그러나, 고흡수성 수지 내에서 캡슐화된 발포제가 발포된 형태는 고흡수성 수지의 제조 조건에 따라 달라질 수 있으므로 하나의 형태로 정의하기가 어렵다. 따라서, 먼저 캡슐화된 발포제를 공기 중에서 발포시켜 팽창 비율 및 크기를 확인함으로써, 원하는 기공을 형성하기에 적합한지 확인할 수 있다.Meanwhile, in order to determine whether pores of a desired size are formed, it is necessary to first grasp the expansion characteristics of the encapsulated blowing agent. However, the form in which the foaming agent encapsulated in the superabsorbent polymer is foamed may vary depending on the manufacturing conditions of the superabsorbent polymer, so it is difficult to define it as one form. Therefore, by first foaming the encapsulated blowing agent in the air, the expansion ratio and size can be checked to confirm whether it is suitable for forming desired pores.
구체적으로, 유리 페트리 접시 위에 캡슐화된 발포제를 도포한 뒤 공기 중에서 180 ℃의 열을 5 분 동안 가하여 캡슐화된 발포제를 팽창시킨다. 이때, 캡슐화된 발포제가 3 내지 15 배, 5 내지 15 배 혹은 8.5 내지 10 배의 공기 중에서의 최대 팽창 비율을 나타낼 때, 본 발명 고흡수성 수지 시트의 제조방법에 있어 적절한 열린 기공 구조를 형성하기에 적합한 것으로 판단할 수 있다.Specifically, after applying the encapsulated foaming agent on a glass petri dish, 180 ° C. of heat was added in the air for 5 minutes to expand the encapsulated foaming agent. At this time, when the encapsulated foaming agent exhibits a maximum expansion ratio in air of 3 to 15 times, 5 to 15 times, or 8.5 to 10 times, it is necessary to form an appropriate open pore structure in the method of manufacturing the superabsorbent polymer sheet of the present invention. You can judge it as appropriate.
상기 캡슐화된 발포제는 평균 직경이 2 내지 50 ㎛, 또는 5 내지 30 ㎛, 또는 5 내지 20 ㎛, 또는 7 내지 17 ㎛일 수 있다. 상기 캡슐화된 발포제가 상기와 같은 평균 직경을 나타낼 때 적절한 공극률을 달성하기에 적합한 것으로 판단할 수 있다.The encapsulated foaming agent may have an average diameter of 2 to 50 μm, or 5 to 30 μm, or 5 to 20 μm, or 7 to 17 μm. When the encapsulated foaming agent exhibits such an average diameter, it can be judged to be suitable for achieving an appropriate porosity.
또한, 상기 캡슐화된 발포제가 공기 중에서의 20 내지 190 ㎛, 또는 50 내지 190 ㎛, 또는 70 내지 190 ㎛, 또는 75 내지 190 ㎛의 최대 팽창 직경을 나타낼 때 본 발명 고흡수성 수지 시트의 제조방법에 있어 적절한 열린 기공 구조를 형성하기에 적합한 것으로 판단할 수 있다.In addition, when the encapsulated foaming agent exhibits a maximum expansion diameter of 20 to 190 μm, or 50 to 190 μm, or 70 to 190 μm, or 75 to 190 μm in air, the method of manufacturing the superabsorbent polymer sheet of the present invention It can be judged to be suitable for forming a suitable open pore structure.
캡슐화된 발포제의 최대 팽창 비율 및 최대 팽창 직경은 제조된 고흡수성 수지 시트에 형성된 기공의 형상을 주사전자현미경(SEM)으로 분석하는 방법에 의하여 측정될 수도 있다.The maximum expansion ratio and the maximum expansion diameter of the encapsulated foaming agent may be measured by a method of analyzing the shape of pores formed in the prepared superabsorbent polymer sheet with a scanning electron microscope (SEM).
상기 캡슐화된 발포제의 코어를 구성하는 탄화수소는 n-프로판, n-부탄, iso-부탄, 사이클로부탄, n-펜탄, iso-펜탄, 사이클로펜탄, n-헥산, iso-헥산, 사이클로헥산, n-헵탄, iso-헵탄, 사이클로헵탄, n-옥탄, iso-옥탄 및 사이클로옥탄으로 구성된 군에서 선택된 1 종 이상일 수 있다. 이 중에서도 탄소수 3 내지 5의 탄화수소(n-프로판, n-부탄, iso-부탄, 사이클로부탄, n-펜탄, iso-펜탄, 사이클로펜탄)가 상술한 크기의 기공을 형성하기에 적합하고, iso-부탄이 가장 적합할 수 있다.The hydrocarbons constituting the core of the encapsulated blowing agent are n-propane, n-butane, iso-butane, cyclobutane, n-pentane, iso-pentane, cyclopentane, n-hexane, iso-hexane, cyclohexane, n- It may be one or more selected from the group consisting of heptane, iso-heptane, cycloheptane, n-octane, iso-octane and cyclooctane. Among them, hydrocarbons having 3 to 5 carbon atoms (n-propane, n-butane, iso-butane, cyclobutane, n-pentane, iso-pentane, cyclopentane) are suitable for forming pores of the size described above, and iso- Butane may be the most suitable.
그리고, 상기 캡슐화된 발포제의 쉘을 구성하는 열가소성 수지는 (메트)아크릴레이트, (메트)아크릴로니트릴, 방향족 비닐, 초산 비닐, 할로겐화 비닐 및 할로겐화 비닐리덴으로 구성된 군에서 선택된 1 종 이상의 모노머로부터 형성되는 폴리머일 수 있다. 이 중에서도 (메트)아크릴레이트 및 (메트)아크릴로니트릴의 공중합체가 상술한 크기의 기공을 형성하기에 가장 적합할 수 있다.In addition, the thermoplastic resin constituting the shell of the encapsulated foaming agent is formed from at least one monomer selected from the group consisting of (meth) acrylate, (meth) acrylonitrile, aromatic vinyl, vinyl acetate, vinyl halide, and vinylidene halide. It can be a polymer. Among them, a copolymer of (meth) acrylate and (meth) acrylonitrile may be most suitable for forming pores of the size described above.
상기 캡슐화된 발포제는 전체 캡슐화된 발포제 중량에 대하여 탄화수소를 10 내지 30 중량%로 포함할 수 있다. 이러한 범위 내에서 열린 기공 구조를 형성하는데 가장 적합할 수 있다.The encapsulated blowing agent may contain 10 to 30% by weight of hydrocarbons based on the total encapsulated blowing agent weight. It may be best suited to form an open pore structure within this range.
상기 캡슐화된 발포제는 제조하여 사용하거나, 또는 상술한 조건을 만족하는 것으로 상용화된 발포제를 사용할 수 있다.The encapsulated foaming agent may be prepared and used, or a commercialized foaming agent satisfying the above-described conditions may be used.
또한 상기 캡슐화된 발포제의 함량은 아크릴산계 단량체의 100 중량부에 대하여 0.3 내지 20 중량부, 바람직하게는 0.5 내지 10 중량부, 더욱 바람직하게는 1 내지 10 중량부를 사용할 수 있다. 상기 캡슐화된 발포제의 함량이 지나치게 적으면 열린 기공 구조가 제대로 형성되지 않을 수 있고, 적절한 기공도를 확보할 수 없으며, 너무 많이 포함되는 경우, 다공성이 너무 높아 고흡수성 수지의 강도가 약해질 수 있으므로 이러한 관점에서 상기 함량 범위가 바람직할 수 있다.In addition, the content of the encapsulated foaming agent may be 0.3 to 20 parts by weight, preferably 0.5 to 10 parts by weight, and more preferably 1 to 10 parts by weight based on 100 parts by weight of the acrylic acid-based monomer. If the content of the encapsulated foaming agent is too small, an open pore structure may not be properly formed, an adequate porosity may not be secured, and if it is included too much, the porosity is too high, so that the strength of the super absorbent polymer may be weakened. In this respect, the content range may be preferred.
상기 무기 발포제는 직경이 10 내지 1000 nm인 것이 바람직하며, 20 내지 500 nm, 또는 50 내지 100 nm가 보다 바람직할 수 있다. 상기 범위의 무기 발포제는 미세 기공 채널을 형성함으로써 캡슐화된 발포제에 의하여 생성된 기공 사이의 경계를 붕괴시키는 역할을 할 수 있으며, 이에 따라 고흡수성 수지 시트의 흡수능을 크게 향상시킬 수 있다. 무기 발포제의 직경은 주사전자현미경(SEM)을 통해 측정될 수 있다.The inorganic blowing agent preferably has a diameter of 10 to 1000 nm, and 20 to 500 nm, or 50 to 100 nm may be more preferable. The inorganic foaming agent in the above range may serve to collapse the boundary between the pores generated by the encapsulated foaming agent by forming a microporous channel, thereby greatly improving the absorbent capacity of the superabsorbent polymer sheet. The diameter of the inorganic blowing agent can be measured through a scanning electron microscope (SEM).
상기 무기 발포제는 통상 발포제로 알려진 물질이 제한 없이 사용 가능하며, 구체적으로는 탄산칼슘(CaCO3), 중탄산나트륨(NaHCO3), 중탄산암모늄(NH4HCO3), 탄산암모늄((NH4)2CO3), 아질산암모늄(NH4NO2), 붕소화수소나트륨 (NaBH4) 및 탄산나트륨(Na2CO3) 중 선택되는 1종 이상이 사용 가능하다. 이 중, 중화액 내에서의 안정성 특성을 고려할 때, 탄산칼슘이 바람직하게 사용될 수 있다.The inorganic blowing agent may be used without limitation, a substance commonly known as a blowing agent, specifically, calcium carbonate (CaCO 3 ), sodium bicarbonate (NaHCO 3 ), ammonium bicarbonate (NH 4 HCO 3 ), ammonium carbonate ((NH 4 ) 2 CO 3 ), ammonium nitrite (NH 4 NO 2 ), one or more selected from sodium borohydride (NaBH 4 ) and sodium carbonate (Na 2 CO 3 ) may be used. Among these, calcium carbonate can be preferably used when considering the stability characteristics in the neutralizing solution.
상기 무기 발포제의 함량은 아크릴산계 단량체의 100 중량부에 대하여 0.1 중량부 이상 사용될 수 있으며, 바람직하게는 0.2 내지 10 중량부, 더욱 바람직하게는 0.3 내지 5 중량부를 사용할 수 있다. 상기 무기 발포제의 함량이 지나치게 적으면 닫힌 기공이 형성되는 문제가 있을 수 있고, 너무 많이 포함되는 경우 높은 기공도에 의해서, 기계적 강도가 낮아지는 문제가 있을 수 있다.The content of the inorganic blowing agent may be used in an amount of 0.1 part by weight or more based on 100 parts by weight of the acrylic acid-based monomer, preferably 0.2 to 10 parts by weight, and more preferably 0.3 to 5 parts by weight. If the content of the inorganic foaming agent is too small, there may be a problem that closed pores are formed, and if too large, the mechanical strength may be lowered due to high porosity.
상기 캡슐화된 발포제 및 무기 발포제의 혼합 사용 비율은 3:1 내지 1:1 중량비가 바람직하고, 2:1 내지 1:1 범위가 더욱 바람직하다. 상기 범위 내에서 높은 기공도 및 기계적 강도 향상 효과를 얻을 수 있고, 이에 따라 제조되는 고흡수성 수지 시트의 원심분리 보수능 및 가압 흡수능이 향상될 수 있다.The mixing ratio of the encapsulated foaming agent and the inorganic foaming agent is preferably 3: 1 to 1: 1 by weight, and more preferably 2: 1 to 1: 1. Within this range, a high porosity and mechanical strength improvement effect can be obtained, and accordingly, the centrifugal water retention capacity and the pressure absorption capacity of the superabsorbent polymer sheet produced can be improved.
또한, 상기 캡슐화된 발포제 및 무기 발포제는 아크릴산 단량체 100 중량부에 대하여 20 중량부 이하로 포함되며, 0.4 내지 20 중량부, 0.7 내지 10 중량부 또는 1 내지 5 중량부 범위로 포함되는 것이 보다 바람직하다. 발포제의 총 함량이 지나치게 많을 경우 발포도가 너무 높아 고흡수성 수지의 강도가 저하될 수 있으며, 너무 적게 포함될 경우 열린 기공 구조가 형성되기 어려우므로 상기 범위를 만족함이 바람직하다.In addition, the encapsulated foaming agent and the inorganic foaming agent are contained in an amount of 20 parts by weight or less based on 100 parts by weight of the acrylic acid monomer, and more preferably in the range of 0.4 to 20 parts by weight, 0.7 to 10 parts by weight, or 1 to 5 parts by weight. . When the total content of the blowing agent is too large, the foaming degree is too high, so the strength of the superabsorbent polymer may be lowered, and if it is included too little, it is preferable to satisfy the above range because it is difficult to form an open pore structure.
본 발명의 고흡수성 수지 시트의 제조 방법에서 중합 시 사용되는 중합 개시제는 고흡수성 수지의 제조에 일반적으로 사용되는 것이면 특별히 한정되지 않는다.The polymerization initiator used in polymerization in the method for producing a superabsorbent polymer sheet of the present invention is not particularly limited as long as it is generally used for the production of superabsorbent polymers.
구체적으로, 상기 중합 개시제는 중합 방법에 따라 열중합 개시제 또는 UV 조사에 따른 광중합 개시제를 사용할 수 있다. 다만, 광중합 방법에 의하더라도, 자외선 조사 등의 조사에 의해 일정량의 열이 발생하고, 또한 발열 반응인 중합 반응의 진행에 따라 어느 정도의 열이 발생하므로, 추가적으로 열중합 개시제를 포함할 수도 있다.Specifically, the polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator according to UV irradiation depending on the polymerization method. However, even by the photopolymerization method, since a certain amount of heat is generated by irradiation with ultraviolet rays or the like and a certain amount of heat is generated as the polymerization reaction that is an exothermic reaction proceeds, a thermal polymerization initiator may be additionally included.
상기 광중합 개시제는 자외선과 같은 광에 의해 라디칼을 형성할 수 있는 화합물이면 그 구성의 한정이 없이 사용될 수 있다.If the photopolymerization initiator is a compound capable of forming radicals by light such as ultraviolet rays, the composition may be used without limitation.
상기 광중합 개시제로는 예를 들어, 벤조인 에테르(benzoin ether), 디알킬아세토페논(dialkyl acetophenone), 하이드록실 알킬케톤(hydroxyl alkylketone), 페닐글리옥실레이트(phenyl glyoxylate), 벤질디메틸케탈(Benzyl Dimethyl Ketal), 아실포스핀(acyl phosphine) 및 알파-아미노케톤(α-aminoketone)으로 이루어진 군에서 선택되는 하나 이상을 사용할 수 있다. 한편, 아실포스핀의 구체예로, 상용하는 lucirin TPO, 즉, 2,4,6-트리메틸-벤조일-트리메틸 포스핀 옥사이드(2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide)를 사용할 수 있다. 보다 다양한 광개시제에 대해서는 Reinhold Schwalm 저서인 "UV Coatings: Basics, Recent Developments and New Application(Elsevier 2007년)" p. 115에 잘 명시되어 있으며, 상술한 예에 한정되지 않는다.The photopolymerization initiator includes, for example, benzoin ether, dialkyl acetophenone, hydroxyl alkylketone, phenyl glyoxylate, and benzyl dimethyl ketal. Ketal), acyl phosphine (alpha) and one or more selected from the group consisting of alpha-aminoketone (α-aminoketone). Meanwhile, as a specific example of acylphosphine, a commercially available lucirin TPO, that is, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide (2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide) can be used. . Reinhold Schwalm's book "UV Coatings: Basics, Recent Developments and New Application (Elsevier 2007)" for more diverse photoinitiators p. It is well specified in 115, and is not limited to the above-described example.
상기 광중합 개시제는 상기 모노머 조성물에 대하여 약 0.01 내지 약 1.0 중량%의 농도로 포함될 수 있다. 이러한 광중합 개시제의 농도가 지나치게 낮을 경우 중합 속도가 느려질 수 있고, 광중합 개시제의 농도가 지나치게 높으면 고흡수성 수지의 분자량이 작고 물성이 불균일해질 수 있다.The photopolymerization initiator may be included in a concentration of about 0.01 to about 1.0% by weight relative to the monomer composition. If the concentration of the photopolymerization initiator is too low, the polymerization rate may be slow, and if the concentration of the photopolymerization initiator is too high, the molecular weight of the super absorbent polymer may be small and the properties may be uneven.
또한, 상기 열중합 개시제로는 과황산염계 개시제, 아조계 개시제, 과산화수소 및 아스코르빈산으로 이루어진 개시제 군에서 선택되는 하나 이상을 사용할 수 있다. 구체적으로, 과황산염계 개시제의 예로는 과황산나트륨(Sodium persulfate; Na2S2O8), 과황산칼륨(Potassium persulfate; K2S2O8), 과황산암모늄(Ammonium persulfate;(NH4)2S2O8) 등이 있으며, 아조(Azo)계 개시제의 예로는 2,2-아조비스-(2-아미디노프로판) 이염산염(2,2-azobis(2-amidinopropane) dihydrochloride), 2,2-아조비스-(N,N-디메틸렌)이소부티라마이딘 디하이드로클로라이드(2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride), 2-(카바모일아조)이소부티로니트릴(2-(carbamoylazo)isobutylonitril), 2,2-아조비스[2-(2-이미다졸린-2-일)프로판] 디하이드로클로라이드(2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride), 4,4-아조비스-(4-시아노발레릭 산)(4,4-azobis-(4-cyanovaleric acid)) 등이 있다. 보다 다양한 열중합 개시제에 대해서는 Odian 저서인 'Principle of Polymerization(Wiley, 1981)', p203에 잘 명시되어 있으며, 상술한 예에 한정되지 않는다.In addition, as the thermal polymerization initiator, one or more 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 are 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 examples of the azo-based initiator are 2,2-azobis- (2-amidinopropane) dihydrochloride (2,2-azobis (2-amidinopropane) dihydrochloride), 2 , 2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride (2-Azobis- (N, N-dimethylene) isobutyramidine dihydrochloride), 2- (carbamoyl azo) 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)). More various thermal polymerization initiators are well specified in the Odian book 'Principle of Polymerization (Wiley, 1981)', p203, and are not limited to the above-described examples.
상기 열중합 개시제는 상기 모노머 조성물에 대하여 약 0.001 내지 약 0.5 중량%의 농도로 포함될 수 있다. 이러한 열중합 개시제의 농도가 지나치게 낮을 경우 추가적인 열중합이 거의 일어나지 않아 열중합 개시제의 추가에 따른 효과가 미미할 수 있고, 열중합 개시제의 농도가 지나치게 높으면 고흡수성 수지의 분자량이 작고 물성이 불균일해질 수 있다.The thermal polymerization initiator may be included in a concentration of about 0.001 to about 0.5% by weight relative to the monomer composition. If the concentration of the thermal polymerization initiator is too low, the additional thermal polymerization hardly occurs, so the effect of adding the thermal polymerization initiator may be negligible. If the concentration of the thermal polymerization initiator is too high, the molecular weight of the super absorbent polymer may be small and the physical properties may be uneven. have.
본 발명의 제조방법에서, 상기 모노머 조성물은 필요에 따라 증점제(thickener), 가소제, 보존안정제, 산화방지제 등의 첨가제를 더 포함할 수 있다.In the production method of the present invention, the monomer composition may further include additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.
상술한 아크릴산계 불포화 단량체, 공단량체, 내부 가교제, 중합 개시제, 및 첨가제와 같은 원료 물질은 용매에 용해된 모노머 조성물 용액의 형태로 준비될 수 있다. 상기 용매는 모노머 조성물의 총 함량에 대하여 상술한 성분을 제외한 잔량으로 포함될 수 있다.Raw materials, such as the acrylic acid-based unsaturated monomer, comonomer, internal crosslinking agent, polymerization initiator, and additives, may be prepared in the form of a solution of a monomer composition dissolved in a solvent. The solvent may be included in the remaining amount excluding the above-mentioned components with respect to the total content of the monomer composition.
사용할 수 있는 상기 용매는 상술한 성분들을 용해할 수 있으면 그 구성의 한정이 없이 사용될 수 있으며, 예를 들어 물, 에탄올, 에틸렌글리콜, 디에틸렌글리콜, 트리에틸렌글리콜, 1,4-부탄디올, 프로필렌글리콜, 에틸렌글리콜모노부틸에테르, 프로필렌글리콜모노메틸에테르, 프로필렌글리콜모노메틸에테르아세테이트, 메틸에틸케톤, 아세톤, 메틸아밀케톤, 시클로헥사논, 시클로펜타논, 디에틸렌글리콜모노메틸에테르, 디에틸렌글리콜에틸에테르, 톨루엔, 크실렌, 부틸로락톤, 카르비톨, 메틸셀로솔브아세테이트 및 N,N-디메틸아세트아미드 등에서 선택된 1종 이상을 조합하여 사용할 수 있다.The solvent that can be used can be used without limitation of its composition as long as it can dissolve the aforementioned 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 ether , Toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, and N, N-dimethylacetamide.
다음에, 상기 모노머 조성물을 열중합 또는 광중합하여 함수겔 중합체를 형성한다.Next, the monomer composition is thermally polymerized or photopolymerized to form a hydrogel polymer.
한편, 이와 같은 모노머 조성물을 열중합 또는 광중합하여 함수겔 중합체를 형성하는 방법은 고흡수성 수지 제조 기술분야에서 통상 사용되는 중합 방법이면, 특별히 구성의 한정이 없다.On the other hand, the method of forming a hydrogel polymer by thermal polymerization or photopolymerization of such a monomer composition is not particularly limited as long as it is a polymerization method commonly used in the field of superabsorbent polymer production.
구체적으로, 중합 방법은 중합 에너지원에 따라 크게 열중합 및 광중합으로 나뉠 수 있다. 통상 열중합을 진행하는 경우, 니더(kneader)와 같은 교반축을 가진 반응기에서 진행될 수 있다. 반면, 광중합을 진행하는 경우, 이동 가능한 컨베이어 벨트를 구비한 반응기에서 진행될 수 있으나, 상술한 중합 방법은 일 예이며, 본 발명은 상술한 중합 방법에 한정되지는 않는다.Specifically, the polymerization method can be largely divided into thermal polymerization and photo polymerization depending on the polymerization energy source. In general, when performing thermal polymerization, it may be carried out in a reactor having a stirring shaft such as a kneader. On the other hand, when photopolymerization is performed, it may be performed in a reactor equipped with a movable conveyor belt, but the polymerization method described above is an example, and the present invention is not limited to the polymerization method described above.
상기 모노머 조성물의 열중합 또는 광중합 반응 온도는 특별히 제한되지 않으나, 일례로 80 내지 120 ℃, 바람직하기로 90 내지110 ℃일 수 있다.The thermal polymerization or photopolymerization reaction temperature of the monomer composition is not particularly limited, but may be, for example, 80 to 120 ° C, preferably 90 to 110 ° C.
이때 이와 같은 방법으로 얻어진 함수겔 중합체의 통상 함수율은 약 40 내지 약 80 중량%일 수 있다. 한편, 상기 함수겔 중합체의 "함수율"은 전체 함수겔 중합체 중량에 대해 차지하는 수분의 함량으로 함수겔 중합체의 중량에서 건조 상태의 중합체의 중량을 뺀 값을 의미한다. 구체적으로는, 적외선 가열을 통해 중합체의 온도를 올려 건조하는 과정에서 중합체 중의 수분증발에 따른 무게감소분을 측정하여 계산된 값으로 정의한다. 이때, 건조 조건은 상온에서 약 180℃까지 온도를 상승시킨 뒤 180℃에서 유지하는 방식으로 총 건조시간은 온도상승단계 5분을 포함하여 20분으로 설정하여, 함수율을 측정한다.At this time, the normal water content of the hydrogel polymer obtained in this way may be about 40 to about 80% by weight. On the other hand, the "water content" of the hydrogel polymer refers to a value obtained by subtracting the weight of the polymer in the dry state from the weight of the hydrogel polymer as the amount of moisture that accounts for the total weight of the hydrogel polymer. Specifically, it is defined as a calculated value by measuring the weight loss due to evaporation of water in the polymer during the drying process by raising the temperature of the polymer through infrared heating. At this time, the drying condition is a method of raising the temperature from room temperature to about 180 ° C and then maintaining it at 180 ° C. The total drying time is set to 20 minutes including 5 minutes of the temperature rise step to measure the water content.
다음에 상기 함수겔 중합체를 시트상으로 성형하고 건조하여 고흡수성 수지 시트를 형성한다. 상기 건조 단계에서 발포제에 의한 발포가 일어날 수 있으며, 이에 따라 고흡수성 수지 시트에 주 기공 사이에 미세 기공 채널이 형성되어, 열린 기공 채널이 형성될 수 있다.Next, the hydrogel polymer is molded into a sheet and dried to form a super absorbent polymer sheet. In the drying step, foaming by the blowing agent may occur, and accordingly, microporous channels may be formed between the main pores in the superabsorbent polymer sheet, thereby forming open pore channels.
이때 상기 건조 단계의 건조 온도는 약 120 내지 약 250℃일 수 있다. 건조 온도가 약 120℃ 미만인 경우, 건조 시간이 지나치게 길어지고 최종 형성되는 고흡수성 수지의 물성이 저하될 우려가 있고, 건조 온도가 약 250℃를 초과하는 경우, 지나치게 중합체 표면만 건조되어, 최종 형성되는 고흡수성 수지의 물성이 저하될 우려가 있다. 따라서 바람직하게 상기 건조는 약 120 내지 약 250℃의 온도에서, 더욱 바람직하게는 약 140 내지 약 200℃의 온도에서 진행될 수 있다.At this time, the drying temperature of the drying step may be about 120 to about 250 ℃. When the drying temperature is less than about 120 ° C, the drying time is too long and there is a fear that the physical properties of the superabsorbent polymer finally formed are deteriorated. When the drying temperature exceeds about 250 ° C, only the polymer surface is excessively dried, resulting in final formation. There is a possibility that the physical properties of the superabsorbent polymer to be deteriorated. Therefore, preferably, the drying may be performed at a temperature of about 120 to about 250 ° C, more preferably at a temperature of about 140 to about 200 ° C.
한편, 건조 시간의 경우에는 공정 효율 등을 고려하여, 약 20 내지 약 90분 동안 진행될 수 있으나, 이에 한정되지는 않는다.Meanwhile, in the case of a drying time, process efficiency and the like may be considered, but may be performed for about 20 to about 90 minutes, but is not limited thereto.
상기 건조 단계의 건조 방법 역시 함수겔 중합체의 건조 공정으로 통상 사용되는 것이면, 그 구성의 한정이 없이 선택되어 사용될 수 있다. 구체적으로, 열풍 공급, 적외선 조사, 극초단파 조사, 또는 자외선 조사 등의 방법으로 건조 단계를 진행할 수 있다.If the drying method of the drying step is also commonly used as a drying process of the hydrogel polymer, it can be selected and used without limitation of its configuration. Specifically, the drying step may be performed by a method such as hot air supply, infrared irradiation, microwave irradiation, or ultraviolet irradiation.
한편, 상기 건조 단계 이후 적절한 고흡수성 수지 시트의 함수율을 달성하기 위하여, 80 내지 100 ℃의 고온 스팀에 상기 건조된 고흡수성 수지 시트를 노출시키는 과정을 더 수행할 수 있다.Meanwhile, after the drying step, a process of exposing the dried superabsorbent polymer sheet to hot steam at 80 to 100 ° C. may be further performed to achieve a proper moisture content of the superabsorbent polymer sheet.
이와 같은 건조 단계 진행 후의 고흡수성 수지 시트의 함수율은 약 10 중량% 이상으로, 예를 들어 약 10 내지 약 40 중량%, 또는 약 15 내지 약 30 중량%일 수 있다. 상기 고흡수성 수지 시트의 함수율이 상술한 범위에 있을 때 시트의 유연성을 확보할 수 있다. 상기 고흡수성 수지 시트의 함수율 측정방법은 후술하는 실시예에서 보다 구체화될 수 있다.The moisture content of the superabsorbent polymer sheet after the drying step is performed may be about 10 wt% or more, for example, about 10 to about 40 wt%, or about 15 to about 30 wt%. When the moisture content of the superabsorbent polymer sheet is in the above-described range, flexibility of the sheet can be secured. The method for measuring the moisture content of the superabsorbent polymer sheet may be more specific in the examples described below.
본 발명의 일 실시예에 따르면, 상기와 같은 공정으로 수득된 고흡수성 수지 시트의 두께는 약 100㎛ 이상, 또는 1,000㎛, 또는 5,000㎛이면서 약 10cm 이하, 또는 약 5cm 이하, 또는 약 1cm 이하일 수 있다. 상기 고흡수성 수지 시트의 두께가 너무 얇으면 강도가 낮아 시트가 찢어질 수 있으며, 너무 두꺼울 경우 건조 및 가공이 어려울 수 있다. 이러한 관점에서 상술한 두께 범위를 갖는 것이 바람직할 수 있다.According to one embodiment of the present invention, the thickness of the superabsorbent polymer sheet obtained by the above-described process may be about 100 μm or more, or 1,000 μm, or 5,000 μm, and may be about 10 cm or less, or about 5 cm or less, or about 1 cm or less. have. If the thickness of the superabsorbent polymer sheet is too thin, the strength may be low and the sheet may be torn, and if it is too thick, drying and processing may be difficult. From this point of view, it may be desirable to have the aforementioned thickness range.
상기와 같은 제조방법에 따라 제조된 고흡수성 수지 시트는 공극의 적어도 일부분이 서로 연결되어 있는 열린 기공 채널(open pore channel) 구조의 시트 상태이기 때문에 모세관 압력(capillary pressure)에 의한 물의 흡수가 가능하다. 이에, 종래의 분말 형태의 고흡수성 수지보다 흡수 속도 및 투과성이 향상될 수 있으며, 펄프리스 흡수체로 그대로 이용될 수 있다.Since the superabsorbent polymer sheet manufactured according to the above-described manufacturing method is in the form of a sheet having an open pore channel structure in which at least a portion of the pores are connected to each other, absorption of water by capillary pressure is possible. . Thus, the absorption rate and permeability can be improved compared to the conventional superabsorbent resin in powder form, and can be used as it is as a pulfree absorbent.
본 발명의 일 구현예에 따르면, 상기 제조방법에 의하여 수득된 고흡수성 수지 시트가 제공된다.According to one embodiment of the present invention, a superabsorbent polymer sheet obtained by the above manufacturing method is provided.
상기 고흡수성 수지 시트는 산성기를 가지며 상기 산성기의 적어도 일부가 중화된 아크릴산계 단량체가, 폴리올(polyol)을 포함하는 내부 가교제, 캡슐화된 발포제, 및 무기 발포제의 존재 하에 가교 중합된 가교 중합체를 포함한다.The superabsorbent polymer sheet has an acidic group, and an acrylic acid monomer in which at least a portion of the acidic group is neutralized includes a crosslinked polymer crosslinked in the presence of an internal crosslinking agent containing polyol, an encapsulating foaming agent, and an inorganic foaming agent. do.
상기 고흡수성 수지 시트는 공극(pore)의 적어도 일부분이 서로 연결된, 열린 기공 채널(open pore channel) 구조를 가지며, 이에 의해 모세관 압력(capillary pressure)에 의한 물의 흡수가 가능하다.The superabsorbent polymer sheet has an open pore channel structure in which at least a portion of pores are connected to each other, whereby absorption of water by capillary pressure is possible.
상기 고흡수성 수지 시트는 EDANA 법 WSP 241.2에 따라 측정된 원심분리 보수능(CRC)이 10 g/g 이상, 15 g/g 이상, 또는 20 g/g 이상이면서, 40 g/g 이하, 30 g/g 이하, 또는 25 g/g 이하일 수 있다.The superabsorbent polymer sheet has a centrifugal water retention capacity (CRC) measured according to EDANA method WSP 241.2 of 10 g / g or more, 15 g / g or more, or 20 g / g or more, and 40 g / g or less, 30 g / g or less, or 25 g / g or less.
또한, 상기 고흡수성 수지 시트는 EDANA 법 WSP 242.2에 따라 측정된 0.7 psi 하에서의 가압 흡수능(AUP)이 5 g/g 이상, 7 g/g 이상, 또는 9 g/g 이상이면서, 20 g/g 이하, 또는 15 g/g 이하일 수 있다.In addition, the superabsorbent polymer sheet has a pressurized absorption capacity (AUP) of 0.7 g or more, 7 g / g or more, or 7 g / g or more, or 9 g / g or more, and 20 g / g or less, measured according to EDANA method WSP 242.2. , Or 15 g / g or less.
상기 고흡수성 수지 시트는 건조 전 및 후의 면적을 비교하여 측정되는 팽창률이 200 % 이상, 250 % 이상, 또는 300 % 이상이면서, 600 % 이하, 550 % 이하, 또는 500 % 이하로 높게 나타나며, 이에 따라 우수한 가요성을 나타낸다. 상기 팽창률은 재단기를 이용하여 함수겔상 중합체를 가로 * 세로 * 두께 = 50 mm * 50 mm * 2 mm의 시트상으로 재단하여 고흡수성 수지 시트를 얻고, 이를 180 ℃ 온도에서 5분 동안 건조하여, 건조 전 재단된 고흡수성 시트의 가로 * 세로 면적과 건조 후 고흡수성 수지 시트의 가로 * 세로 면적을 비교하는 방법에 의하여 측정될 수 있다.The superabsorbent polymer sheet has an expansion rate of 200% or more, 250% or more, or 300% or more, which is measured by comparing the areas before and after drying, and is high as 600% or less, 550% or less, or 500% or less. It exhibits excellent flexibility. The expansion rate was cut into a sheet shape of horizontal * vertical * thickness = 50 mm * 50 mm * 2 mm by cutting the hydrogel polymer using a cutting machine to obtain a super absorbent polymer sheet, dried at a temperature of 180 ° C. for 5 minutes, and dried. It can be measured by comparing the horizontal * vertical area of the pre-cut superabsorbent sheet with the horizontal * vertical area of the superabsorbent polymer sheet after drying.
이하 발명의 구체적인 실시예를 통해 발명의 작용, 효과를 보다 구체적으로 설명하기로 한다. 다만, 이는 발명의 예시로서 제시된 것으로 이에 의해 발명의 권리범위가 어떠한 의미로든 한정되는 것은 아니다.Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, this is provided as an example of the invention, and the scope of the invention is not limited in any way.
<실시예><Example>
고흡수성 수지 시트의 제조Preparation of super absorbent polymer sheet
실시예 1Example 1
아크릴산 30 g, 가성소다(NaOH, 30 중량% 용액) 38.9g 및 물 6.2 g을 혼합하여상기 아크릴산의 약 70 몰%가 중화된 중화액(고형분 함량: 50 중량%)을 준비하였다.30 g of acrylic acid, 38.9 g of caustic soda (NaOH, 30 wt% solution) and 6.2 g of water were mixed to prepare a neutralizing solution (solid content: 50 wt%) in which about 70 mol% of the acrylic acid was neutralized.
상기 중화액에 글리세롤(glycerol) 12 g, 폴리에틸렌글리콜 디아크릴레이트(MW=330 제조사: aldrich사) 0.09 g, 과황산나트륨(sodium persulfate) 0.06g, 캡슐화된 발포제(Akzonobel사, Expancel 031 DU 40, 평균 직경 10 내지 16 ㎛) 0.3 g, 탄산칼슘(CaCO3) 발포제(직경 50 내지 100 nm) 0.3 g을 첨가하여, 모노머 조성물을 제조하였다.12 g of glycerol in the neutralization solution, polyethylene glycol diacrylate (MW = 330 manufacturer: aldrich) 0.09 g, sodium persulfate 0.06 g, encapsulated blowing agent (Akzonobel, Expancel 031 DU 40, average A monomer composition was prepared by adding 0.3 g of a diameter of 10 to 16 μm) and 0.3 g of a calcium carbonate (CaCO 3 ) blowing agent (50 to 100 nm in diameter).
상기 모노머 조성물을 메케니컬 믹서(mechanical mixer)를 이용하여 500 rpm의 속도로 약 10 분간 고전단 혼합하였다.The monomer composition was mixed with high shear at a rate of 500 rpm for about 10 minutes using a mechanical mixer.
이후, 중합기의 공급부를 통해 투입하여 중합을 실시하여 함수겔 중합체를 형성하였다. 이때 중합기의 온도는 100℃로 유지하였으며, 중합의 최고 온도는 110℃, 중합 시간은 10분이었다.Subsequently, polymerization was performed through the supply of the polymerizer to form a hydrogel polymer. At this time, the temperature of the polymerization reactor was maintained at 100 ° C, the highest temperature of polymerization was 110 ° C, and the polymerization time was 10 minutes.
이어서, 상기 함수겔 중합체를 재단기를 이용하여 시트 형태(가로 * 세로 * 두께 = 50 mm * 50 mm * 2 mm)로 절단하고, 180℃ 온도에서 5분 동안 건조하여, 고흡수성 수지 시트를 제조하였다. 그런 다음, 제조된 고흡수성 수지 시트를 고온의 스팀(80 ℃, 85 %)에 10분간 노출시켜, 함수율을 높인 고흡수성 수지 시트를 제조하였다.Subsequently, the hydrogel polymer was cut into a sheet form (horizontal * vertical * thickness = 50 mm * 50 mm * 2 mm) using a cutting machine, and dried at a temperature of 180 ° C. for 5 minutes to prepare a super absorbent polymer sheet. . Then, the prepared superabsorbent polymer sheet was exposed to hot steam (80 ° C., 85%) for 10 minutes to prepare a superabsorbent polymer sheet having a high water content.
실시예 2Example 2
상기 실시예 1에서, 아크릴산 100 중량% 대비 캡슐화된 발포제 및 탄산칼슘 발포제를 각각 1.5 중량%를 사용한 것을 제외하고는, 실시예 1과 동일한 방법으로 고흡수성 수지 시트를 제조하였다.In Example 1, a superabsorbent polymer sheet was prepared in the same manner as in Example 1, except that 1.5% by weight of each of 100% by weight of acrylic acid and an encapsulated foaming agent and a calcium carbonate foaming agent were used.
비교예 1Comparative Example 1
상기 실시예 2에서, 캡슐화된 발포제 및 무기 발포제를 사용하지 않은 것을 제외하고는 실시예 2와 동일한 방법으로 고흡수성 수지 시트를 제조하였다.In Example 2, a superabsorbent polymer sheet was prepared in the same manner as in Example 2, except that the encapsulated blowing agent and the inorganic blowing agent were not used.
비교예 2Comparative Example 2
상기 실시예 2에서, 무기 발포제를 사용하지 않은 것을 제외하고는 실시예 2와 동일한 방법으로 고흡수성 수지 시트를 제조하였다.In Example 2, a super absorbent polymer sheet was prepared in the same manner as in Example 2, except that an inorganic foaming agent was not used.
비교예 3Comparative Example 3
상기 실시예 2에서, 캡슐화된 발포제를 사용하지 않은 것을 제외하고는 실시예 2와 동일한 방법으로 고흡수성 수지 시트를 제조하였다.In Example 2, a superabsorbent polymer sheet was prepared in the same manner as in Example 2, except that the encapsulated blowing agent was not used.
비교예 4Comparative Example 4
상기 실시예 2에서, 내부 가교제로 글리세롤 및 폴리에틸렌글리콜 디아크릴레이트 대신, 폴리에틸렌글리콜 디아크릴레이트만을 12.09 g 사용한 것을 제외하고는 실시예 2와 동일한 방법으로 고흡수성 수지 시트를 제조하였다.In Example 2, instead of glycerol and polyethylene glycol diacrylate as an internal crosslinking agent, a superabsorbent polymer sheet was prepared in the same manner as in Example 2, except that only 12.09 g of polyethylene glycol diacrylate was used.
<실험예><Experimental Example>
실험예 1: 고흡수성 수지 시트의 특성 평가Experimental Example 1: Characterization of superabsorbent polymer sheet
(1) 고흡수성 수지 시트의 단면(1) Cross section of super absorbent polymer sheet
본 발명의 실시예 1에 따른 고흡수성 수지 시트 단면의 주사전자현미경(SEM) 사진을 도 1에 나타내었다. 도 1을 참조하면, 본 발명의 실시예 1에 따른 고흡수성 수지 시트 표면에는 열린 기공 채널 구조가 형성되어 있음을 확인할 수 있다.A scanning electron microscope (SEM) photograph of a cross section of a super absorbent polymer sheet according to Example 1 of the present invention is shown in FIG. 1. Referring to Figure 1, it can be seen that an open pore channel structure is formed on the superabsorbent polymer sheet surface according to the first embodiment of the present invention.
그러나 발포제를 포함하지 않은 비교예 1은 다공성 구조를 가지지 못하는 것으로 확인되었다.However, it was confirmed that Comparative Example 1 without a blowing agent does not have a porous structure.
(2) 유연성(2) Flexibility
고흡수성 수지 시트를 반으로 접은 후 다시 펼쳤을 때 원래의 시트 상태로 돌아오는 경우를 O로 하고, 접었을 때 접은 부분이 갈라지거나 부서져서 원래의 시트 상태로 돌아오지 않는 경우 X로 평가하였다.When the superabsorbent polymer sheet was folded in half and then unfolded again, the case where it returned to the original sheet state was set to O, and when folded, the folded part was cracked or broken to return to the original sheet state and evaluated as X.
한편, 도 2는 실시예 1 및 비교예 2의 시트를 직경 25 mm의 바이알에 감아 유연성 정도를 테스트한 결과로, 도 2를 참조하면 실시예 1의 시트는 유연성이 우수하여 바이알의 곡면에 밀착되나, 비교예 2의 경우 유연성이 떨어져 바이알에 밀착되지 않는 것을 확인할 수 있다.On the other hand, Figure 2 is a result of testing the degree of flexibility by winding the sheets of Example 1 and Comparative Example 2 in a vial having a diameter of 25 mm. Referring to Figure 2, the sheet of Example 1 is excellent in flexibility and adheres to the curved surface of the vial. However, in the case of Comparative Example 2, it was confirmed that the flexibility was poor and the vial did not adhere.
(3) 팽창률(3) Expansion rate
가로 * 세로 * 두께 = 50 mm * 50 mm * 2 mm 로 재단된 시트 형태의 함수겔 중합체의 가로 * 세로 면적과, 이를 180℃ 온도에서 5분 동안 건조한 다음 제조된 고흡수성 수지 시트의 가로 * 세로 면적을 비교하여 팽창률을 측정하였다.Horizontal * Vertical * Thickness = 50 mm * 50 mm * 2 mm The width * length area of the hydrogel polymer in the form of a sheet cut and the width * length of the superabsorbent polymer sheet prepared after drying at 180 ° C. for 5 minutes. The expansion rate was measured by comparing the areas.
(4) 고흡수성 수지 시트의 함수율(4) Water content of the super absorbent polymer sheet
각 실시예 및 비교예에서 제조된 고흡수성 수지 시트(재단, 건조 및 스팀 노출이 완료된 상태) 5 g을 150 ℃ 에서 30 분간 가열 건조하여, 초기 무게 대비 날아간 수분량을 계산하여, 함수율을 측정하였다.5 g of the superabsorbent polymer sheet (cutting, drying, and steam exposure completed) prepared in each of the Examples and Comparative Examples was dried by heating at 150 ° C. for 30 minutes, and the moisture content compared to the initial weight was calculated to measure the water content.
실험예 2: 고흡수성 수지 시트의 흡수능 평가Experimental Example 2: Evaluation of absorbency of the super absorbent polymer sheet
(1) 원심분리 보수능 (CRC)(1) Centrifugal water retention capacity (CRC)
EDANA 법 WSP 241.2의 방법에 따라 원심분리 보수능(CRC)을 측정하였다.The centrifugal water retention capacity (CRC) was measured according to the method of EDANA method WSP 241.2.
(2) 가압 흡수능(AUP)(2) Pressurized absorption capacity (AUP)
EDANA 법 WSP 242.2의 방법에 따라 0.7 psi 하에서의 가압 흡수능(AUP)을 측정하였다.Pressure absorption capacity (AUP) under 0.7 psi was measured according to the method of EDANA method WSP 242.2.
실시예 1 내지 2 및 비교예 1 내지 3에서 제조한 고흡수성 수지 시트의 특성을 평가하여 하기 표 1에 나타내었다.To evaluate the properties of the superabsorbent polymer sheet prepared in Examples 1 to 2 and Comparative Examples 1 to 3 are shown in Table 1 below.
Figure PCTKR2019011716-appb-T000001
Figure PCTKR2019011716-appb-T000001
상기 표 1을 참조하면, 실시예의 고흡수성 수지 시트는 유사한 함수율을 갖는 비교예의 시트에 비하여 유연성이 우수하고, 다공성, 팽창률 특성이 우수하며, 이에 따라 CRC, AUP 등의 흡수 물성 또한 비교예에 비하여 현저히 우수함을 확인할 수 있다.Referring to Table 1, the superabsorbent polymer sheet of the embodiment has superior flexibility, superior porosity, and expansion coefficient characteristics compared to the sheet of the comparative example having a similar water content, and accordingly, the absorption properties of CRC, AUP, etc. are also compared to the comparative example. It can be confirmed that it is remarkably excellent.

Claims (16)

  1. 산성기를 가지며 상기 산성기의 적어도 일부가 중화된 아크릴산계 단량체, 폴리올(polyol)을 포함하는 내부 가교제, 캡슐화된 발포제, 무기 발포제, 및 중합 개시제를 혼합하여 모노머 조성물을 제조하는 단계;Preparing an monomer composition by mixing an acrylic acid-based monomer having an acidic group and at least a part of the acidic group being neutralized, an internal crosslinking agent containing polyol, an encapsulating foaming agent, an inorganic foaming agent, and a polymerization initiator;
    상기 모노머 조성물을 열중합 또는 광중합하여 함수겔 중합체를 형성하는 단계; 및Thermally or photopolymerizing the monomer composition to form a hydrogel polymer; And
    상기 함수겔 중합체를 건조하는 단계를 포함하는 고흡수성 수지 시트의 제조방법.Method of producing a super absorbent polymer sheet comprising the step of drying the hydrogel polymer.
  2. 제1항에 있어서,According to claim 1,
    상기 폴리올(polyol)은 에틸렌 글리콜, 프로필렌 글리콜, 1,3-프로판디올, 1,4-부탄디올, 1,6-헥산디올, 1,2-헥산디올, 1,3-헥산디올, 2-메틸-1,3-프로판디올, 2,5-헥산디올, 2-메틸-1,3-펜탄디올, 2-메틸-2,4-펜탄디올, 트리프로필렌 글리콜 및 글리세롤로 이루어진 군으로부터 선택되는 1종 이상을 포함하는, 고흡수성 수지 시트의 제조방법.The polyol is ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl- 1,3-propanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, at least one member selected from the group consisting of tripropylene glycol and glycerol The method of manufacturing a super absorbent polymer sheet comprising a.
  3. 제1항에 있어서,According to claim 1,
    상기 폴리올(polyol)은 상기 아크릴산계 단량체 100 중량부에 대하여 10 내지 80 중량부로 포함되는, 고흡수성 수지 시트의 제조방법.The polyol (polyol) is contained in 10 to 80 parts by weight based on 100 parts by weight of the acrylic acid-based monomer, a method for producing a super absorbent polymer sheet.
  4. 제1항에 있어서,According to claim 1,
    상기 캡슐화된 발포제는 평균 직경이 2 내지 50 ㎛인, 고흡수성 수지 시트의 제조방법.The encapsulated foaming agent has an average diameter of 2 to 50 μm, a method for producing a super absorbent polymer sheet.
  5. 제1항에 있어서,According to claim 1,
    상기 캡슐화된 발포제는 공기 중 팽창 비율이 3 내지 15 배인, 고흡수성 수지 시트의 제조방법.The encapsulated foaming agent has an expansion ratio of 3 to 15 times in air, and a method for producing a super absorbent polymer sheet.
  6. 제1항에 있어서,According to claim 1,
    상기 캡슐화된 발포제는 탄화수소를 포함하는 코어와 상기 코어를 둘러싸며 열가소성 수지로 형성되는 쉘을 포함하는 구조를 가지는, 고흡수성 수지 시트의 제조방법.The encapsulated foaming agent has a structure including a core comprising a hydrocarbon and a shell surrounding the core and formed of a thermoplastic resin, the method of manufacturing a super absorbent polymer sheet.
  7. 제6항에 있어서,The method of claim 6,
    상기 탄화수소는 n-프로판, n-부탄, iso-부탄, 사이클로부탄, n-펜탄, iso-펜탄, 사이클로펜탄, n-헥산, iso-헥산, 사이클로헥산, n-헵탄, iso-헵탄, 사이클로헵탄, n-옥탄, iso-옥탄 및 사이클로옥탄으로 구성된 군에서 선택된 1 종 이상인, 고흡수성 수지 시트의 제조방법.The hydrocarbon is n-propane, n-butane, iso-butane, cyclobutane, n-pentane, iso-pentane, cyclopentane, n-hexane, iso-hexane, cyclohexane, n-heptane, iso-heptane, cycloheptane , n-octane, iso-octane and cyclooctane, at least one member selected from the group consisting of a method for producing a super absorbent polymer sheet.
  8. 제6항에 있어서,The method of claim 6,
    상기 열가소성 수지는 (메트)아크릴레이트, (메트)아크릴로니트릴, 방향족 비닐, 초산 비닐, 할로겐화 비닐 및 할로겐화 비닐리덴으로 구성된 군에서 선택된 1 종 이상의 모노머로부터 형성되는 폴리머인, 고흡수성 수지 시트의 제조방법.The thermoplastic resin is a polymer formed from one or more monomers selected from the group consisting of (meth) acrylate, (meth) acrylonitrile, aromatic vinyl, vinyl acetate, vinyl halide, and vinylidene halide. Way.
  9. 제1항에 있어서,According to claim 1,
    상기 무기 발포제는 탄산칼슘(CaCO3), 중탄산나트륨(NaHCO3), 중탄산암모늄(NH4HCO3), 탄산암모늄((NH4)2CO3), 아질산암모늄(NH4NO2), 붕소화수소나트륨 (NaBH4) 및 탄산나트륨(Na2CO3) 중 선택되는 1종 이상인, 고흡수성 수지 시트의 제조방법.The inorganic blowing agent is calcium carbonate (CaCO 3 ), sodium bicarbonate (NaHCO 3 ), ammonium bicarbonate (NH 4 HCO 3 ), ammonium carbonate ((NH 4 ) 2 CO 3 ), ammonium nitrite (NH 4 NO 2 ), hydrogen borohydride Method for producing a super absorbent polymer sheet, at least one selected from sodium (NaBH 4 ) and sodium carbonate (Na 2 CO 3 ).
  10. 제1항에 있어서,According to claim 1,
    상기 캡슐화된 발포제와 무기 발포제는 3:1 내지 1:1의 중량비로 포함되는, 고흡수성 수지 시트의 제조방법.The encapsulated foaming agent and the inorganic foaming agent are contained in a weight ratio of 3: 1 to 1: 1, a method for producing a super absorbent polymer sheet.
  11. 제1항에 있어서,According to claim 1,
    상기 캡슐화된 발포제는 아크릴산계 단량체 100 중량부에 대하여 0.3 내지 20 중량부로 포함되는, 고흡수성 수지 시트의 제조방법.The encapsulated foaming agent is contained in 0.3 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer, a method for producing a super absorbent polymer sheet.
  12. 제1항에 있어서,According to claim 1,
    상기 무기 발포제는 아크릴산계 단량체 100 중량부에 대하여 0.2 내지 10 중량부로 포함되는, 고흡수성 수지 시트의 제조방법.The inorganic foaming agent is contained in 0.2 to 10 parts by weight based on 100 parts by weight of the acrylic acid-based monomer, a method for producing a super absorbent polymer sheet.
  13. 산성기를 가지며 상기 산성기의 적어도 일부가 중화된 아크릴산계 단량체가, 폴리올(polyol)을 포함하는 내부 가교제, 캡슐화된 발포제, 및 무기 발포제의 존재 하에 가교 중합된 가교 중합체를 포함하는 고흡수성 수지 시트.A superabsorbent polymer sheet having an acidic group, wherein at least a portion of the acidic group is neutralized, and the acrylic acid-based monomer comprises a crosslinked polymer crosslinked in the presence of an internal crosslinking agent containing polyol, an encapsulating foaming agent, and an inorganic foaming agent.
  14. 제13항에 있어서,The method of claim 13,
    EDANA 법 WSP 241.2에 따라 측정된 원심분리 보수능(CRC)이 10 g/g 내지 40 g/g인, 고흡수성 수지 시트.A superabsorbent polymer sheet having a centrifugal water retention capacity (CRC) of 10 g / g to 40 g / g measured according to EDANA method WSP 241.2.
  15. 제13항에 있어서,The method of claim 13,
    EDANA 법 WSP 242.2에 따라 측정된 0.7 psi 하에서의 가압 흡수능(AUP)이 5 g/g 내지 20 g/g인, 고흡수성 수지 시트.A super absorbent polymer sheet having a pressure absorption capacity (AUP) of 0.7 g to 20 g / g under 0.7 psi measured according to EDANA method WSP 242.2.
  16. 제13항에 있어서,The method of claim 13,
    가로 * 세로 * 두께 = 50 mm * 50 mm * 2 mm로 재단된 고흡수성 수지 시트의 가로 * 세로 면적과, 이를 180℃ 온도에서 5분 동안 건조한 후의 고흡수성 수지 시트의 가로 * 세로 면적으로 정의되는 팽창률이 200 % 이상인, 고흡수성 수지 시트.Defined by the horizontal * vertical * horizontal = vertical area of the superabsorbent polymer sheet cut to a thickness = 50 mm * 50 mm * 2 mm, and the horizontal * vertical area of the superabsorbent polymer sheet after drying at 180 ° C for 5 minutes. A super absorbent polymer sheet having an expansion rate of 200% or more.
PCT/KR2019/011716 2018-09-27 2019-09-10 Manufacturing method for superabsorbent polymer sheet WO2020067662A1 (en)

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