KR20170106109A - Method for measuring of permeability of super absorbent polymer - Google Patents
Method for measuring of permeability of super absorbent polymer Download PDFInfo
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- KR20170106109A KR20170106109A KR1020160029836A KR20160029836A KR20170106109A KR 20170106109 A KR20170106109 A KR 20170106109A KR 1020160029836 A KR1020160029836 A KR 1020160029836A KR 20160029836 A KR20160029836 A KR 20160029836A KR 20170106109 A KR20170106109 A KR 20170106109A
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- cylinder
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- transmittance
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- 238000000034 method Methods 0.000 title claims abstract description 45
- 230000035699 permeability Effects 0.000 title claims abstract description 9
- 229920000247 superabsorbent polymer Polymers 0.000 title claims description 12
- 239000011347 resin Substances 0.000 claims abstract description 56
- 229920005989 resin Polymers 0.000 claims abstract description 56
- 238000002834 transmittance Methods 0.000 claims abstract description 35
- 239000000243 solution Substances 0.000 claims description 29
- 239000012267 brine Substances 0.000 claims description 24
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 24
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 17
- 239000002245 particle Substances 0.000 claims description 17
- 239000002250 absorbent Substances 0.000 claims description 8
- 230000002745 absorbent Effects 0.000 claims description 7
- 230000008859 change Effects 0.000 claims description 6
- 238000000691 measurement method Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 16
- 239000007788 liquid Substances 0.000 abstract description 4
- 239000000178 monomer Substances 0.000 description 31
- 229920000642 polymer Polymers 0.000 description 28
- 238000004132 cross linking Methods 0.000 description 16
- 238000001035 drying Methods 0.000 description 15
- 238000006116 polymerization reaction Methods 0.000 description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
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- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 6
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- 125000000524 functional group Chemical group 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 125000001424 substituent group Chemical group 0.000 description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 2
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-M Methacrylate Chemical compound CC(=C)C([O-])=O CERQOIWHTDAKMF-UHFFFAOYSA-M 0.000 description 2
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- -1 alkali metal salt Chemical class 0.000 description 2
- 125000003277 amino group Chemical group 0.000 description 2
- 150000007514 bases Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 2
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- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- 229920000536 2-Acrylamido-2-methylpropane sulfonic acid Polymers 0.000 description 1
- XHZPRMZZQOIPDS-UHFFFAOYSA-N 2-Methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonic acid Chemical compound OS(=O)(=O)CC(C)(C)NC(=O)C=C XHZPRMZZQOIPDS-UHFFFAOYSA-N 0.000 description 1
- OMIGHNLMNHATMP-UHFFFAOYSA-N 2-hydroxyethyl prop-2-enoate Chemical class OCCOC(=O)C=C OMIGHNLMNHATMP-UHFFFAOYSA-N 0.000 description 1
- GWZMWHWAWHPNHN-UHFFFAOYSA-N 2-hydroxypropyl prop-2-enoate Chemical class CC(O)COC(=O)C=C GWZMWHWAWHPNHN-UHFFFAOYSA-N 0.000 description 1
- VYVCCAVYYHVSFZ-UHFFFAOYSA-N 2-methyl-3-oxopent-4-ene-1-sulfonic acid Chemical compound OS(=O)(=O)CC(C)C(=O)C=C VYVCCAVYYHVSFZ-UHFFFAOYSA-N 0.000 description 1
- MJIFFWRTVONWNO-UHFFFAOYSA-N 3-oxopent-4-ene-1-sulfonic acid Chemical compound OS(=O)(=O)CCC(=O)C=C MJIFFWRTVONWNO-UHFFFAOYSA-N 0.000 description 1
- SVYPQURSUBDSIQ-UHFFFAOYSA-N 4-methyl-3-oxopent-4-ene-1-sulfonic acid Chemical compound CC(=C)C(=O)CCS(O)(=O)=O SVYPQURSUBDSIQ-UHFFFAOYSA-N 0.000 description 1
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001252 acrylic acid derivatives Chemical class 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 235000006708 antioxidants Nutrition 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- LDHQCZJRKDOVOX-NSCUHMNNSA-N crotonic acid Chemical compound C\C=C\C(O)=O LDHQCZJRKDOVOX-NSCUHMNNSA-N 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
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- 238000000227 grinding Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 150000002734 metacrylic acid derivatives Chemical class 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
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- 239000003381 stabilizer Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
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- 229920001059 synthetic polymer Polymers 0.000 description 1
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- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- LDHQCZJRKDOVOX-UHFFFAOYSA-N trans-crotonic acid Natural products CC=CC(O)=O LDHQCZJRKDOVOX-UHFFFAOYSA-N 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000009281 ultraviolet germicidal irradiation Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
- B01L3/56—Labware specially adapted for transferring fluids
- B01L3/567—Valves, taps or stop-cocks
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/14—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by dead weight, e.g. pendulum; generated by springs tension
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/44—Resins; Plastics; Rubber; Leather
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/44—Resins; Plastics; Rubber; Leather
- G01N33/442—Resins; Plastics
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/24—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by observing the transmission of wave or particle radiation through the material
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Medicinal Chemistry (AREA)
- Food Science & Technology (AREA)
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- Chemical Kinetics & Catalysis (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The present invention relates to a method for measuring the transmittance of a superabsorbent resin. More particularly, the present invention relates to a method of measuring the transmittance of a superabsorbent resin having high reproducibility and high accuracy. According to the method for measuring the transmittance of the superabsorbent resin of the present invention, subjective judgment of the measurer is eliminated, measurement error is reduced, and the liquid permeability can be evaluated by measuring the transmittance of the superabsorbent resin with high accuracy and high reproducibility.
Description
The present invention relates to a method for measuring the transmittance of a superabsorbent resin. More particularly, the present invention relates to a method of measuring the transmittance of a superabsorbent resin having high reproducibility and high accuracy.
Super Absorbent Polymer (SAP) is a synthetic polymer material capable of absorbing moisture of about 500 to 1,000 times its own weight. As a result, it is possible to develop a super absorbent polymer (SAM), an absorbent gel Material), and so on. Such a superabsorbent resin has started to be put into practical use as a sanitary article, and nowadays, in addition to sanitary articles such as diapers for children, there are currently used soil repair agents for horticultural use, index materials for civil engineering and construction, sheets for seedling growing, freshness- And it is widely used as a material for fomentation and the like.
As a method of producing such a superabsorbent resin, there are known methods such as reversed-phase suspension polymerization or aqueous solution polymerization. The reversed-phase suspension polymerization is disclosed in, for example, Japanese Unexamined Patent Publication No. 56-161408, Unexamined Japanese Patent Application No. 57-158209, and Japanese Unexamined Patent Publication No. 57-198714. Methods of aqueous solution polymerization include a thermal polymerization method in which a polymerization gel is polymerized while being broken and cooled in a kneading machine having a plurality of shafts and a photopolymerization method in which a high concentration aqueous solution is irradiated with ultraviolet rays or the like on a belt to simultaneously perform polymerization and drying Are known. The hydrogel polymer obtained through polymerization reaction as described above is generally marketed as a powdery product after being pulverized through a drying process.
Among the properties required for the superabsorbent resin, the liquid permeability is measured by evaluating the permeability to salt water by its ability to rapidly transfer the solution to another superabsorbent resin.
This transmittance can be measured by the method described in Buchholz, FL and Graham, AT, "Modern Superabsorbent Polymer Technology," John Wiley & Sons (1998), page 161. The 0.9% Can be evaluated by measuring the passing time. In this case, since the time taken for the brine solution to pass through the superabsorbent resin is measured by the eye and the time is measured by the timer, the measurement error may be largely measured Which is a cause of deteriorating reliability in evaluating the liquid permeability of the superabsorbent resin.
In order to solve the problems of the related art as described above, one aspect of the present invention provides a method of measuring the transmittance of the superabsorbent resin by reducing the measurement error and reproducibly and more accurately.
In order to achieve the above object, the present invention is characterized in that an upper limit and a lower limit are indicated, and an IR detector is provided at the upper and lower limits, and a cylinder having a stopcock at the lower end thereof is provided with a superabsorbent resin ;
Charging a 0.9% NaCl solution into the cylinder in which the stopcock is locked to bring the level of the brine solution to the upper limit;
Applying a load of 0.3 psi to the cylinder;
Opening the stopcock to measure the time (Ts) it takes for the brine solution to pass from the upper limit to the lower limit; And
Measuring the time (T 0 ) required for 0.9% of the saline solution to pass from the upper limit to the lower limit under a load of 0.3 psi without injecting the super absorbent resin into the cylinder,
The time (Ts, T 0 ) is detected by measuring the upper limit passing time (T 2) and the lower limit passing time (T 1) by an infrared detector provided at the upper and lower limits,
[Formula 1]
Transmittance (unit: second) = T S - T 0
According to the method for measuring the transmittance of the superabsorbent resin of the present invention, subjective judgment of the measurer is eliminated, measurement error is reduced, and the liquid permeability can be evaluated by measuring the transmittance of the superabsorbent resin with high accuracy and high reproducibility.
1 is a schematic diagram showing a conventional apparatus used for measuring transmittance.
2 is a schematic diagram showing an apparatus used in the measuring method of the present invention.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
In addition, throughout this specification, "comprising" or "containing ", unless specifically stated, refers to including any and all components (or components) Can not be interpreted as excluding.
Hereinafter, a method of measuring the transmittance of the super absorbent polymer according to one embodiment of the present invention will be described in detail.
A method of measuring a transmittance of a superabsorbent resin according to an aspect of the present invention includes displaying an upper limit line and a lower limit line, wherein an IR detector is installed on the upper and lower limits, and a stopcock is provided on a lower end thereof Injecting a superabsorbent resin into the cylinder; Charging a 0.9% NaCl solution into the cylinder in which the stopcock is locked to bring the level of the brine solution to the upper limit; Applying a load of 0.3 psi to the cylinder; Opening the stopcock to measure the time (Ts) it takes for the brine solution to pass from the upper limit to the lower limit; And measuring the time (T 0 ) required for the 0.9% brine solution to pass from the upper limit to the lower limit under 0.3 psi load without injecting the super absorbent resin into the cylinder, , the time (Ts, T 0) is characterized in that measurement to detect the upper limit passing point in time (T2) and a lower limit passing point in time (T1) by the infrared ray detector is installed on the upper and lower limits.
[Formula 1]
Transmittance (unit: second) = T S - T 0
In general, the permeability of a superabsorbent resin is a measure of how well a brine (0.9% NaCl aqueous solution) permeates a swollen superabsorbent resin and is described by Buchholz, FL and Graham, AT, "Modern Superabsorbent Polymer Technology," John Wiley & Sons (1998), page 161), 0.2 g of the superabsorbent resin powder was swollen for 30 minutes, and a pressure of 0.3 psi was applied, and the time taken for the 0.9% saline solution to pass through was measured and evaluated.
More specifically, 0.2 g of superabsorbent resin particles having a particle size of 300 to 600 탆 among the superabsorbent resin to be measured is taken and charged into a cylinder (? 20 mm). At this time, a stopcock is included at one end of the cylinder, and an upper limit line and a lower limit line are displayed. The upper limit line of the cylinder is displayed at the position when the 40 mL of the saline solution is filled, and the lower limit line is displayed when the 20 mL of the saline solution is filled Position.
50 g of 0.9% saline solution is placed in the cylinder in which the stopcock is locked and left for 30 minutes. Next, if necessary, additional salt solution is added to bring the salt solution level to the upper limit of the cylinder. Next, a load of 0.3 psi was applied to the cylinder containing the superabsorbent resin absorbing the brine, and the cylinder was allowed to stand for one minute. A stop cock located below the cylinder is then opened to measure the time it takes for the 0.9% brine solution to pass from the upper limit indicated in the cylinder through the lower limit. All measurements shall be made at a temperature of 24 ± 1 ° C and a relative humidity of 50 ± 10%.
The transmittance is calculated in accordance with the following formula 1 by measuring the time taken to pass from the upper limit line to the lower limit line with respect to each super absorbent resin (Ts) and without injecting the super absorbent resin (T 0 ).
[Formula 1]
Transmittance (sec) = T S - T 0
1 is a schematic diagram showing a conventional apparatus used for measuring transmittance according to the above method.
Referring to Figure 1, with the passage upper limit of the salt point (T2) and a lower limit passing point in time (T1) measured self-measurement by the timer watching with eyes calculating the time difference (T2-T1) and calculates the Ts and T 0, respectively. Therefore, it is difficult to accurately determine the upper limit passing time (T2) and the lower limit passing time (T1), and there is a possibility that the subjective judgment of the measurer will intervene. Therefore, the measurement error . This error is undesirable because it affects reproducibility and accuracy.
According to the present invention, since the upper limit passing time and the lower limit passing time of the brine are measured by using the infrared detector, the measurement error is remarkably reduced and subjective judgment of the measurer is eliminated, and high reproducibility and accuracy can be shown.
2 is a schematic diagram showing an apparatus used in the measuring method of the present invention.
Referring to FIG. 2, infrared detectors are installed on the upper and lower limits of the cylinder, respectively. Thus, by measuring the passing time of the upper limit of the salt (T2) and a lower limit passing point in time (T1) to the infrared detector and calculates the Ts and T 0 to the time difference.
That is, as the salt water passes through the cylinder, the medium in the cylinder changes from saline water to air, thereby causing a change in the refractive index. Therefore, when the infrared detector detects the change in the refractive index, the upper limit and the lower limit passing point can be accurately measured. Therefore, the subjective judgment of the measurer can not be intervened, and the same measurement result can be obtained for the same superabsorbent resin sample with almost no error, thereby ensuring high reproducibility and accuracy.
The superabsorbent resin is a polymer formed by subjecting a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator to thermal polymerization or photopolymerization, and is a polymer produced by a method of producing a general superabsorbent resin such as drying, crushing, And there is no particular limitation.
According to one embodiment of the present invention, there is provided a process for producing a water-soluble ethylenically unsaturated monomer, which comprises thermally polymerizing or photopolymerizing a monomer composition comprising a water-soluble ethylenically unsaturated monomer and a polymerization initiator to form a hydrogel polymer; Drying the hydrogel polymer; Pulverizing the dried polymer; And a surface cross-linking reaction is carried out by mixing and heating the ground polymer to a surface cross-linking solution containing a surface cross-linking agent and water to prepare a superabsorbent resin.
The monomer composition which is a raw material of the superabsorbent resin includes a water-soluble ethylenically unsaturated monomer and a polymerization initiator.
The water-soluble ethylenically unsaturated monomer may be any monomer conventionally used in the production of a superabsorbent resin without any particular limitations. Here, at least one monomer selected from the group consisting of an anionic monomer and its salt, a nonionic hydrophilic-containing monomer and an amino group-containing unsaturated monomer and a quaternary car- bon thereof may be used.
Specific examples thereof include acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2- methacryloylethanesulfonic acid, 2- acryloylpropanesulfonic acid, 2- Anionic monomers of 2-acrylamido-2-methylpropanesulfonic acid, or 2-methacrylamide-2-methylpropanesulfonic acid and salts thereof; Acrylamide, N-substituted acrylate, N-substituted methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2- Nonionic hydrophilic-containing monomers such as methacrylate, methoxypolyethylene glycol acrylate, methoxypolyethylene glycol methacrylate, polyethylene glycol acrylate, or polyethylene glycol methacrylate; And (N, N) -dimethylaminopropyl methacrylate, (N, N) -dimethylaminoethyl acrylate, (N, N) -dimethylaminoethyl methacrylate, At least one selected from the group consisting of an amino group-containing unsaturated monomer of amide and a quaternary product thereof can be used.
More preferably, acrylic acid or a salt thereof, for example, an alkali metal salt such as acrylic acid or sodium salt thereof can be used. By using such a monomer, it becomes possible to produce a superabsorbent resin having superior physical properties. When the alkali metal salt of acrylic acid is used as a monomer, acrylic acid may be neutralized with a basic compound such as sodium hydroxide (NaOH). The basic compound may be used in an amount of about 20 to 60 parts by weight, preferably about 30 to 50 parts by weight, based on 100 parts by weight of the acrylic acid.
The concentration of the water-soluble ethylenically unsaturated monomer may be about 20 to about 60 wt%, preferably about 40 to about 50 wt%, based on the monomer composition. The monomer composition may contain a solvent and may be adjusted to an appropriate concentration in consideration of polymerization time and reaction conditions. However, if the concentration of the monomer is excessively low, the yield of the superabsorbent resin may be low and economical efficiency may be deteriorated. On the other hand, if the concentration is excessively high, a part of the monomer may precipitate or the pulverization efficiency may be low Problems such as the like may occur and the physical properties of the superabsorbent resin may be deteriorated.
The polymerization initiator used in the polymerization in the method for producing a superabsorbent resin is not particularly limited as long as it is generally used in the production of a superabsorbent resin.
Specifically, as the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator based on UV irradiation may be used depending on the polymerization method. However, even when the photopolymerization method is employed, a certain amount of heat is generated by irradiation of ultraviolet light or the like, and a certain amount of heat is generated as the polymerization reaction, which is an exothermic reaction, proceeds.
The photopolymerization initiator can be used without limitation in the constitution as long as it is a compound capable of forming a radical by light such as ultraviolet rays. Various photoinitiators are well described in Reinhold Schwalm, "UV Coatings: Basics, Recent Developments and New Application (Elsevier 2007) " p. 115, and are not limited to the above examples.
As the thermal polymerization initiator, at least one selected from persulfate-based initiators, azo-based initiators, initiators consisting of hydrogen peroxide and ascorbic acid can be used. Various thermal polymerization initiators are well described in the Odian book "Principle of Polymerization (Wiley, 1981) " p203, and are not limited to the above examples.
According to one embodiment of the present invention, the monomer composition may further include an internal cross-linking agent. As the internal crosslinking agent, a crosslinking agent having at least one functional group capable of reacting with the water-soluble substituent of the water-soluble ethylenically unsaturated monomer and having at least one ethylenic unsaturated group; Or a crosslinking agent having two or more functional groups capable of reacting with water-soluble substituents formed by hydrolysis of the water-soluble substituents and / or monomers of the monomers.
Further, the monomer composition of the superabsorbent resin may further contain additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.
The raw materials such as the water-soluble ethylenically unsaturated monomer, the photopolymerization initiator, the thermal polymerization initiator, the internal crosslinking agent and the additives described above can be prepared in the form of a monomer composition solution dissolved in a solvent.
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 commonly used polymerization method.
Specifically, the polymerization method is largely divided into thermal polymerization and photopolymerization depending on the polymerization energy source. In general, when thermal polymerization is carried out, it may proceed in a reactor having a stirring axis such as a kneader. In the case where light polymerization is proceeded, The polymerization method described above is merely an example, and the present invention is not limited to the polymerization method described above.
The normal water content of the hydrogel polymer obtained in this way may be from about 40 to about 80% by weight. On the other hand, throughout the present specification, the term "moisture content" means the moisture content of the total functional gelated polymer weight minus the weight of the hydrogel polymer in dry state. Specifically, it is defined as a value calculated by measuring the weight loss due to moisture evaporation in the polymer in the process of raising the temperature of the polymer through infrared heating. At this time, the drying condition is a method of raising the temperature from room temperature to about 180 ° C and then keeping it at 180 ° C, and the total drying time is set to 20 minutes including 5 minutes of the temperature raising step, and water content is measured.
Next, the step of drying the obtained hydrogel polymer is carried out.
At this time, if necessary, the step of coarse grinding may be further carried out before drying in order to increase the efficiency of the drying step.
In this case, the pulverizer to be used is not limited in its constitution, but may be a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, A crusher, a disc mill, a disc mill, a shred crusher, a crusher, a chopper, and a disc cutter. However, the present invention is not limited to the above-described example.
The drying method in the drying step may be selected and used as long as it is usually used as a drying step of the hydrogel polymer. Specifically, the drying step can be carried out by hot air supply, infrared irradiation, microwave irradiation, ultraviolet irradiation, or the like. The water content of the polymer after such a drying step may be from about 0.1 to about 10% by weight.
Next, a step of pulverizing the dried polymer obtained through such a drying step is carried out.
The polymer powder obtained after the milling step may have a particle diameter of from about 150 to about 850 탆. The pulverizer used for crushing with such a particle size is specifically a pin mill, a hammer mill, a screw mill, a roll mill, a disc mill, A jog mill, or the like may be used, but the present invention is not limited to the above examples.
Further, in order to control the physical properties of the superabsorbent resin powder which is finally produced after the pulverization step, a separate process of classifying the polymer powder obtained after pulverization according to the particle size may be performed. Preferably, the polymer having a particle diameter of about 150 to about 850 탆 is classified, and the polymer powder having such a particle diameter can be produced through the surface cross-linking reaction step.
Next, the surface cross-linking reaction can be carried out by mixing the ground polymer with a surface cross-linking agent and a surface cross-linking solution containing water.
The surface cross-linking is a step of increasing the cross-linking density near the surface of the superabsorbent polymer particle in relation to the cross-linking density inside the particle. Generally, the surface cross-linking agent is applied to the surface of the superabsorbent resin particles. Thus, this reaction takes place on the surface of the superabsorbent resin particles, which improves the crosslinkability on the surface of the particles without substantially affecting the interior of the particles. Thus, the surface cross-linked superabsorbent resin particles have a higher degree of crosslinking in the vicinity of the surface than in the interior.
At this time, the surface cross-linking agent is not limited as long as it is a compound capable of reacting with a functional group contained in the polymer.
When the surface cross-linking agent is mixed, water may be further mixed together and mixed in the form of a surface cross-linking solution. When water is added, there is an advantage that the surface cross-linking agent can be uniformly dispersed in the polymer. In addition, the surface cross-linking solution may further include a metal salt, silica, or the like.
The composition of the surface cross-linking solution to the polymer is not limited. A method in which the surface cross-linking solution and the polymer powder are mixed in a reaction tank or spraying the surface cross-linking solution onto the polymer powder, a method in which the polymer and the surface cross-linking solution are continuously supplied to a mixer continuously operated and mixed have.
The temperature raising means for the surface cross-linking reaction is not particularly limited. A heating medium can be supplied, or a heating source can be directly supplied and heated. At this time, as the type of usable heat medium, it is possible to use a heated fluid such as steam, hot air or hot oil. However, the present invention is not limited thereto, and the temperature of the heat medium to be supplied can be controlled by means of heat medium, It can be appropriately selected in consideration of the target temperature. On the other hand, as a heat source to be directly supplied, a heating method using electricity or a heating method using gas may be mentioned, but the present invention is not limited to the above-mentioned examples.
The properties of the superabsorbent resin obtained by the above production method vary depending on the various process conditions in the production method, such as the transmittance, the water content, the water repellency, and the pressure absorption ability. It is possible to ensure high accuracy and reproducibility by applying the measuring method of the present invention to the transmittance which is evaluated by measuring the passing time of the test piece.
The present invention will be described in more detail in the following Examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.
<Examples>
<Measurement of transmittance>
Example 1
Measured under a 0.3 psi load using a 0.9% brine solution by the method described in the literature (Buchholz, FL and Graham, AT, "Modern Superabsorbent Polymer Technology," John Wiley & Sons (1998), page 161) And a cylinder equipped with an infrared detector at an upper limit and a lower limit, respectively.
Superabsorbent resin samples A to E having different transmittances were prepared and 0.2 g of particles having a particle diameter of 300 to 600 mu m were taken for each sample and charged into a cylinder (? 20 mm). At this time, a stopcock is included at one end of the cylinder, and an upper limit line and a lower limit line are displayed. The upper limit line of the cylinder is displayed at the position when the 40 mL of the saline solution is filled, and the lower limit line is displayed when the 20 mL of the saline solution is filled Position. The upper limit line and the lower limit line are respectively provided with infrared detectors for detecting a change in the refractive index. The change in the refractive index of the medium when the brine passes through the upper and lower limits can be measured and the time difference can be measured with a timer.
50 g of a 0.9% saline solution (NaCl) was added to the cylinder in which the stopcock was locked, and left for 30 minutes. Further, a brine solution was added so that the level of the brine solution reached the upper limit of the cylinder. Next, the cylinder containing the brine-absorbent superabsorbent resin was then subjected to a load of 0.3 psi and left for one minute. The stop cock located below the cylinder was then opened and the time (Ts) it took for the 0.9% brine solution to pass from the upper limit indicated in the cylinder through the lower limit was measured with a timer connected to an infrared detector.
The other conditions are all the same except that the time (T 0 ) required for the 0.9% saline solution to pass through the lower limit from the upper limit indicated in the cylinder is measured with a timer connected to the infrared detector without the addition of the superabsorbent resin, The transmittance was calculated.
All measurements were carried out at a temperature of 24 ± 1 ° C and a relative humidity of 50 ± 10%.
[Formula 1]
Transmittance (sec) = T S - T 0
Each of the superabsorbent resins of Samples A to E was repeatedly measured three times.
Comparative Example 1
In the same manner as in Example 1, a 0.9% brine solution was used under a load of 0.3 psi, and a cylinder without an infrared detector was used in the upper and lower limits as shown in FIG. The time it takes for the brine to pass from the upper limit to the lower limit is measured by the measurer and the timer is manually set to T S and T 0 Respectively, and the transmittance was calculated according to the above formula (1).
All measurements were carried out at a temperature of 24 ± 1 ° C and a relative humidity of 50 ± 10%.
Four different samples for sample A, five different samples for sample B, and five different samples for sample C were measured once each.
Comparative Example 2
In the same manner as in Example 1, a 9% brine solution was used under a load of 0.3 psi, and a cylinder without an infrared detector was used in the upper and lower limits as shown in FIG. The time it takes for the brine to pass from the upper limit to the lower limit is measured by the measurer and the timer is manually set to T S and T 0 Respectively, and the transmittance was calculated according to the above formula (1).
All measurements were carried out at a temperature of 24 ± 1 ° C and a relative humidity of 50 ± 10%.
For each of the superabsorbent resins of Samples A to E, the same measurer was repeatedly measured three times.
The transmittance and the error range of the examples and comparative examples measured by the above method are shown in Table 1 below.
(Unit: second)
(unit:%)
(Unit: second)
(unit:%)
(Unit: second)
(unit:%)
Referring to Table 1, the measurement method of the present invention showed almost no change in transmittance according to the number of repetitions. However, according to the comparative example, which is a conventional measurement method for measuring the brine passage time by eye, even if the same measurer is used, the variation of the measurement value is large depending on the number of times of measurement, and the reproducibility and accuracy are degraded.
Claims (6)
Charging a 0.9% NaCl solution into the cylinder in which the stopcock is locked to bring the level of the brine solution to the upper limit;
Applying a load of 0.3 psi to the cylinder;
Opening the stopcock to measure the time (Ts) it takes for the brine solution to pass from the upper limit to the lower limit; And
Measuring the time (T 0 ) required for 0.9% of the saline solution to pass from the upper limit to the lower limit under a load of 0.3 psi without injecting the super absorbent resin into the cylinder,
The time (Ts, T 0) is the transmittance measurement method of the superabsorbent polymer, that are measured by detecting the upper limit passing point in time (T2) and a lower limit passing point in time (T1) by the infrared ray detector is installed on the upper and lower limits:
[Formula 1]
Transmittance (unit: second) = T S - T 0
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