KR20140114622A - Water absorbent resin containing the biopolymer useful for components of disposable diapers and preparation method thereof - Google Patents

Abstract

The present invention provides a method for producing various kinds of low toxic hydrogel using natural polymers and hydrogel produced through the same, wherein the low toxic hydrogel has a rapid absorbing speed and a high absorbing amount. Alginic acid hydrogel and k-carageenan/karaya gum hydrogel exhibiting rapid swelling properties can be applied to a diaper or a hygiene product. CMC hydrogel and amide pectin hydrogel having a slow swelling speed but exhibiting a high horizontal swelling degree can be utilized as a vegetation mat. The hydrogel produced in the present invention can be applied in various fields by producing pores and adjusting a composition rate using various natural polymers.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water absorbent resin containing natural polymers usable in disposable diapers,

The present invention relates to a method for producing an absorbent resin using a natural polymer, and more particularly, to a method for producing a water absorbent resin using a natural polymer, which comprises reacting acetic acid with a natural polymer solution mixed with sodium bicarbonate to form bubbles, To a method of producing an absorbent resin which is harmless to the water absorbent resin. The present invention is characterized in that a natural polymer is used without using polyacrylic acid or polyacrylamide which is mainly used in the production of the water absorbent resin. Such a manufacturing method can produce a water absorbent resin having no toxicity, so that it can be applied to disposable diapers and sanitary articles There is an advantage that it is useful.

Super Absorbent Polymer (SAP) is a synthetic polymer material capable of absorbing moisture of about 500 to 1,000 times its own weight. Super Absorbent Material (SAM), Absorbent Gel Material (AGM) And so on. The absorbent resin as described above has begun to be put to practical use as a sanitary article and is currently being used as a sanitary article for children's diapers and diapers, as well as a soil conditioner for gardening, an index material for civil engineering and construction, a sheet for seedling growing, And has been widely used as a material for various purposes.

The currently manufactured and sold absorbent structure is subjected to a process of separately containing the particles of the water absorbent resin to express the function of water absorption in the matrix, which is a fiber aggregate. Through this process, the concentration of the water absorbent resin particles is regulated and regulated to regulate the absorption performance.

Conventional superabsorbent resins are mainly composed of synthetic polymers such as polyacrylic acid and polyacrylamide. However, they are toxic, and when they are applied to disposable diapers or sanitary napkins for women, side effects such as itching are worried. Currently, studies on biodegradable polymers such as polyacrylic acid-starch graft polymers obtained by graft-polymerizing starch on polyacrylic acid and natural polymers and synthetic polymers have been actively conducted [kang, 2002], but the swelling characteristics are somewhat inferior It is necessary to develop a hygienic and safe absorbent that does not use synthetic polymers.

Hydrogel is a three-dimensional networked hydrophilic polymer that does not dissolve in an aqueous environment, but absorbs and swells a large amount of water [Omidian et al., 2005]. Hydrogels with various shapes and properties can be made depending on the constitution and manufacturing method, and have a property of being intermediate between a liquid and a solid because they contain a large amount of water. These properties are useful in a wide variety of fields, such as hygiene products based on absorbency, drug delivery systems, biomaterials, and tissue engineering.

In general, hydrogels swell due to diffusion, so they require a swelling time of several days or longer, ranging from a few minutes to a complete equilibrium swelling state, which begins to absorb water in a dry state and is no longer swollen [ Gemeinhart et al., 2000].

Korean Patent Application No. 10-2012-0018805 (filed on Feb. 14, 2012)

S. G. Kang, Polymer science and technology, 13, 4 (2002) H. Omidian, J.G. Rocca, and K. Park, J. Control. Release, 102, 3 (2005) R.A. Gemeinhart, H. Park, and K. Park, Polym, Adv. Technol., 11, 617 (2000)

Disclosure of Invention Technical Problem [8] In order to solve the problems of the conventional disposable diaper as described above, instead of the conventional absorbent resin using polyacrylic acid or polyacrylamide, carbon dioxide generated from the reaction between sodium bicarbonate and acetic acid is applied to a natural polymer, It is another object of the present invention to provide a method for manufacturing a water absorbent resin which can protect the wearer's skin by using a natural polymer having no toxicity.

The present invention provides a composition for a water absorbent resin comprising a natural polymer, sodium bicarbonate (NaHCO ₃ ) for forming bubbles and acetic acid, and an aqueous calcium chloride solution for crosslinking. Preferably, the natural polymer is selected from the group consisting of sodium alginate, kappa-carrageenan / karaya gum, amide pectin and carboxymethylcellulose (CMC), and the composition is a foam stabilizer, Bovine serum albumin ). ≪ / RTI > The composition may comprise a 0.34 M aqueous solution of calcium chloride containing 1 to 2 wt% of natural polymers, 0.9 wt% sodium bicarbonate, 0.15 wt% bovine serum albumin, and 10 (v / v) acetic acid.

The present invention also relates to a method for forming a foam, comprising: forming a composition comprising a natural polymer, a foam stabilizer and a foam stabilizer; Subjecting the composition to thermal polymerization to form a polymer; Crosslinking and forming air bubbles; And drying the polymer using a thermal drying method or a freeze drying method. Preferably, the natural polymer is selected from the group consisting of sodium alginate, kappa-carrageenan / karaya gum, amide pectin and carboxymethylcellulose (CMC), which is a mixture of sodium bicarbonate (NaHCO ₃ ) and acetic acid , And the foam stabilizer is bovine serum albumin (BSA). The composition comprises a 0.34 M aqueous solution of calcium chloride containing 1 to 2 wt% of a natural polymer, 0.9 wt% of sodium bicarbonate, 0.15 wt% of bovine serum albumin, and 10 (v / v)% acetic acid, .

In addition, the present invention provides a disposable absorbent article which is manufactured by including the water absorbent resin and the water absorbent resin produced by the above production method. Preferably, the disposable absorbent article is a diaper or a feminine hygiene article.

Hereinafter, a method for producing an water absorbent resin according to a specific embodiment of the present invention will be described.

Forming a composition comprising a natural polymer, a foam stabilizer, and a foam stabilizer; Subjecting the composition to thermal polymerization to form a polymer; Crosslinking and forming air bubbles; And drying the polymer using a thermal drying or freeze-drying method at 50 占 폚; The present invention also provides a method of producing an absorbent resin comprising the steps of:

Since it is a water-absorbent resin produced using a natural polymer, it is safer than an absorbent resin made of a synthetic polymer in the prior art, and the fear of irritating the user's skin is reduced.

The present invention relates to a method for producing a water absorbent resin, and more particularly, to a method for producing a water absorbent resin using a natural polymer, unlike a water absorbent resin made of a conventional synthetic polymer, having a large amount of water without toxicity to human body.

According to the present invention, it is possible to manufacture an absorbent resin using a natural polymer having no toxicity instead of a synthetic polymer, thereby protecting the wearer's skin.

1 is a graph showing swelling ratios of alginate hydrogel in distilled water and artificial urine. Alginic acid hydrogel without bubble formation was used as a control.
2 shows a photograph of a freeze-dried alginic acid hydrogel. (a) an alginic acid hydrogel not forming pores, (b) an alginic acid hydrogel in which pores are formed.
Figure 3 shows the swelling ratio graph of the carrageenan / karaya gum hydrogel. As a control group, a hydrogel composed of only carrageenan free of karaya gum was used.
Figure 4 shows the swelling ratio graph under various conditions of the amide pectin hydrogel. As a control, amide pectin hydrogel without pore formation was used.
FIG. 5 is a graph showing swelling ratios observed in amide pectin hydrogels at pH 5.5, 6.3, and 8.1 artificial urine.
FIG. 6 is a graph showing swelling ratios observed in distilled water of CMC hydrogels and amide pectin hydrogels. FIG.
Figure 7 shows a graph of cytotoxicity of the hydrogel. PAA: poly (acrylic acid); Al: alginic acid hydrogel; K / K: carrageenan / karaya gum hydrogel; AP: amide pectin hydrogel; CMC: CMC hydrogel.

Best Mode for Carrying Out the Invention Hereinafter, the functions and effects of the present invention will be described in more detail through specific embodiments of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

[ Experimental Example  One] Hydrogel  Structure analysis

The internal structure of the hydrogel was observed with a digital microscope (AM-413ZT; AnMo Electronics co.).

[ Experimental Example  2] Measurement of swelling behavior

The swelling degree of each sample was measured in distilled water and artificial urine. The artificial urine was Na ₂ SO ₄ (0.2 wt%), KCl (0.2 wt%), MgCl ₂ (0.05 wt%), CaCl ₂ (0.025 wt%), NH ₄ H ₂ PO ₄ (0.085 wt% ₄ ) ₂ HPO ₄ (0.015 wt%).

The weight of the swollen sample was measured at predetermined time intervals after the weight of the dried sample was measured before swelling. When weighing, the excess water on the surface was wiped off with filter paper. Three samples were measured and averaged. The degree of swelling was calculated using the following equation.

Swelling ratio = (W _s - W _d / W _d

W _s : Weight of swollen sample

W _d : Weight of dried sample

[ Example  One] Hydrogel  Bubble formation

Hydrogels are synthesized by ionic crosslinking of hydrophilic polymers under aqueous environment. The composition and the preparation conditions of the hydrogel thus prepared are summarized in Table 1.

CO ₂ using a bubbling agent NaHCO ₃ to generate the porous structure Gas was generated, and BSA was added as a foam stabilizer so that the formed bubbles could be stably maintained. The bubble size depends on the amount of acetic acid and NaHCO _{3. In} order to produce a hydrogel having uniformly distributed gas bubbles, the crosslinking process and the bubbling process must occur at the same time. The hydrogel prepared without the addition of the bubbling agent was used as a control hydrogel.

[ Example  2] Alginic acid Hydrogel  Produce

Alginic acid hydrogel preparation was partially modified by Sriamornsak et al. (Srimornsak et al., J. Pharmaceutics, 434, p. 72 (2006). After dissolving sodium alginate (2 wt%), NaHCO ₃ (0.9 wt%) and BSA (0.15 wt%) in distilled water, the solution was placed in a cell strainer (pore size: 40 μm, SPL Lifesciences co. v) acetic acid and 0.34M CaCl ₂ Solution. The prepared hydrogel was immersed in distilled water and distilled water was changed. After that, the hydrogel was taken out, left at room temperature for a while, and then taken out and lyophilized. The control hydrogel was prepared by dissolving sodium alginate (2 wt%) in distilled water in 0.34M CaCl ₂ Crosslinked to the solution, and then the same procedure was followed to obtain a dried hydrogel [Table 1].

FIG. 1 shows changes in swelling degree of alginate hydrogel in distilled water or artificial urine according to drying method, pore formation, or the like. Compared with the thermally dried hydrogel, the lyophilized hydrogel showed rapid swelling that reached the swelling state within two hours. It is believed that the hydrogel in a swollen state is vacuum dried and some closed pores on the surface of the hydrogel are opened into open pores and absorb more moisture than the thermally dried hydrogel . In addition, alginate hydrogels formed with pores showed high swelling rate and fast swelling rate in both distilled water and artificial urine when compared with alginic acid hydrogel not forming pores. It can be seen that the water absorption amount is increased because the continuous open connected structure formed by forming the pores is connected to the outside through the fine pores of the surface and smooth movement of water is performed. Alginic acid hydrogel showed higher degree of swelling in artificial urine than in distilled water. In the case of alginic acid hydrogel, a cation such as Na ⁺ or K ⁺ existing in an excessive amount of salt aqueous solution is ion-bonded to COO ^- of alginic acid hydrogel and its cation is ion-exchanged with Ca ^{2 +} of alginic acid hydrogel, Absorption capacity.

FIG. 2 is a photograph of the internal structure of alginic acid hydrogels formed with pores and alginic acid hydrogels not forming pores with a digital microscope. FIG. 2 (a) is a photograph of the internal structure of alginic acid hydrogel not containing a bubbling agent, showing a structure in which a layered structure is formed. FIG. 2 (b) is a photograph of the internal structure of the alginic acid hydrogel to which the bubbling agent is added. It can be seen that pores of 500 μm or more are connected to each other to form a three-dimensionally open channel porous structure. In the capillary phenomenon, the height of the liquid surface and the inner diameter of the pore are in inverse proportion, so that it is assumed that if the pore size is smaller, it will have faster absorption rate and higher absorption amount.

[ Example  3] kappa - Carrageenan / Karaya  sword Hydrogel  Produce

The hydrogels prepared with Kappa-carrageenan alone were added with karaya gum to show an iris phase. After dissolving kappa-carrageenan (1.75 wt%), NaHCO ₃ (0.9 wt%) and BSA (0.15 wt%) in the distilled water, they are mixed with the appropriate concentration of Karaya gum solution. 20 g of the mixed aqueous solution was poured into a petri-dish (50 mm x 12 mm) and left for a while. And then immersed in a 0.1M KOH aqueous solution for 5 minutes. The hydrogel thus prepared was washed with ethanol and then dried or lyophilized to obtain a kappa-carrageenan / karaya gum hydrogel (Table 1).

Figure 3 shows the swelling behavior of kappa-carrageenan / karaya gum hydrogel in distilled water. The control group, kappa-carrageenan hydrogel, showed a swelling degree of up to 16 g / g due to a rapid increase in the degree of swelling after 35 g / g in 60 minutes, And the degree of swelling was observed to be greatly reduced even after 120 minutes. This seems to maintain a high degree of swelling as the affinity between the gum particles and water increases as the karaya gum hydrates. It can be seen that the optimal composition ratio is a hydrogel mixed with a ratio of 1.75: 0.5 wt% and 2: 0.25 wt% of kappa-kappa and kaolin having swelling degrees of 40 g / g or more from 60 minutes to 120 minutes have.

On the other hand, the hydrogel to which the bubbling agent was added exhibited an unstable swelling behavior when compared with the hydrogel not containing the bubbling agent, and the kappa-carrageenan / karaya gum hydrogel was an aqueous solution containing a salt such as saline or artificial urine In the preliminary experiment, it was confirmed that the swelling degree is lower than that of distilled water. In general, when the hydrogel is immersed in a salt solution instead of distilled water, the osmotic pressure difference between the inside of the hydrogel and the external environment, that is, the salt solution, decreases due to the osmotic pressure of the salt solution. Therefore, the final degree of swelling of hydrogel in salt solution is smaller than in distilled water.

[ Example  4] Amide pectin Hydrogel  Produce

The preparation process of the amide pectin hydrogel was similar to that of the alginic acid hydrogel, and the preparation of the control hydrogel was also carried out as described above.

FIG. 4 shows the degree of swelling of amide pectin hydrogel according to the drying method with respect to time in distilled water, physiological saline, and artificial urine. As shown in the figure, the freeze-dried amide pectin hydrogels exhibited rapid swelling in 10 to 30 minutes compared to the thermally dried amide pectin hydrogel, reaching equilibrium swelling state. In addition, swelling behavior in distilled water, saline solution and artificial urine was observed in the order of distilled water, saline solution and artificial urine in that order. This is because the osmotic pressure of the hydrogel in distilled water greatly influences the swelling behavior in saline solution and artificial urine Seems to be. On the other hand, the hydrogel not containing the bubbling agent showed a swelling degree higher than that of the hydrogel in which the bubbling agent was formed by adding the bubbling agent. This is because the shape of the pores formed in the lyophilizing process of the pore- And the structure is collapsed.

FIG. 5 is a graph showing the swelling ratio of amide pectin hydrogel over time in artificial urine buffer having pH 5.5 and pH 6.2. FIG. The swelling ratio was higher at pH 8.1 than at 6.2 or 5.5. When the pH is slightly acidic, the carboxyl group in the hydrogel takes up COOH, and as the pH increases, the swelling ratio increases due to COO ^- repulsion.

[ Example  5] CMC Hydrogel  Produce

After dissolving CMC (2 wt%), NaHCO ₃ (0.9 wt%) and BSA (0.15 wt%) in distilled water, Alum (0.3 wt%) was added and the mixture was treated with a homogenizer (Basic T25; IKA co. Homogenized and then dried at 50 ° C to obtain a dried hydrogel.

Composition of manufactured natural polymer hydrogel Component Sodium alginate κ-carrageenan /
karaya gum Carboxymethylcellulose (CMC) Amide pectin Cross linker (gelling agent) CaCl ₂ KOH Alum CaCl ₂ Surfactant BSA BSA BSA BSA Foam maker NaHCO ₃ /
Acetic acid NaHCO ₃ /
Acetic acid NaHCO ₃ /
Acetic acid NaHCO ₃ /
Acetic acid

* BSA (Bovine serum albumin)

Fig. 6 shows swelling degrees of thermally dried CMC hydrogels and amide pectin hydrogels in distilled water. The CMC hydrogel reached a swelling state after 9 hours and showed a swelling degree of about 70 g / g. The amide pectin hydrogel reached a swelling state after 48 hours and showed a high degree of swelling of about 125 g / g. The amide pectin hydrogel has a low crosslinking density due to the reduction of the free carboxyl group crosslinked with the calcium ion due to the amide group, but the amide pectin forms a stable gel through the hydrogen bond formation with the amidated portion even with the decrease of the calcium binding ability . Compared to amide pectin hydrogels, CMC hydrogels exhibit a faster swelling behavior due to the high hydrophilicity of the CMC molecule, and the amide pectin hydrogel has a higher degree of swelling because of its lower crosslink density, It is absorbed. Amide pectin hydrogel or CMC hydrogel appears to be useful as a vegetation mat.

[ Example  6] Hydrogel  Cytotoxicity experiment ( MTT assay )

To evaluate the cytotoxicity of hydrogels, 3- (4,5-dimethylthiazol-2-yl) -2,5-dipheny-ltetrazolium bromide (MTT) assay was performed. Macrophage RAW 264.7 cells were used and purchased from Korean Cell Line Bank (KCLB). RAW 264.7 cells are 10% fetal bovine serum (FBS, Gibco) and 1% antibiotic (Gibco) a Dulbecco's modified Eagle's medium (DMEM , Gibco) 37 ℃ in a culture medium, 5% CO ₂ containing , And subcultured at intervals of 2 to 3 days. RAW 264.7 cells were plated at a density of 1 × 10 ⁵ cells / ml in a 96-well tissue culture plate in a volume of 100 μl per well, and cultured for 24 hours. Each hydrogel eluate prepared at concentrations of 1,000 ppm, 500 ppm, 250 ppm, 100 ppm, and 50 ppm was treated with RAW 264.7 cells and incubated at 37 ° C in 5% CO ₂ Lt; / RTI > After 24 hours, the medium containing the eluate was treated with MTT solution and reacted at 37 ° C for 4 hours. After the medium was removed, dimethyl sulfoxide (DMSO) was added, and ELISA reader (ELX808; Biotek Instruments ) Was used to measure the cytotoxicity. Each experiment was repeated 3 times and the absorbance was measured and cell viability was calculated using the following equation to determine cytotoxicity.

Cell viability (%) = Abs _test / Abs _contro

Abs _test = absorbance of the _test group

Abs _control = absorbance of _control group

FIG. 7 shows the cytotoxicity test results of the hydrogel. The MTT assay used is to measure absorbance as a method of determining toxicity through the RAW 264.7 cells grown. The cytotoxicity of polyacrylic acid was found to be high, and the cytotoxicity of alginic acid, kappa-carrageenan / karaya gum, amide pectin and CMC hydrogel was found to be very low at all concentrations.

Claims (12)

A natural polymer, sodium bicarbonate (NaHCO ₃ ) for forming bubbles and acetic acid, and an aqueous calcium chloride solution for crosslinking. The absorbent resin composition according to claim 1, wherein the natural polymer is selected from the group consisting of sodium alginate, kappa-carrageenan / karaya gum, amide pectin and carboxymethyl cellulose (CMC). The absorbent resin composition according to claim 1, wherein the composition further comprises Bovine serum albumin (BSA) as a foam stabilizer. The composition according to claim 3, characterized in that it comprises a 0.34M aqueous solution of calcium chloride containing 1 to 2 wt% of a natural polymer, 0.9 wt% of sodium bicarbonate, 0.15 wt% of bovine serum albumin, and 10 (v / v) By weight. Forming a composition comprising a natural polymer, a foam stabilizer and a foam stabilizer; Subjecting the composition to thermal polymerization to form a polymer; Crosslinking and forming air bubbles; And drying the polymer using a thermal drying or lyophilizing method. 6. The method of claim 5, wherein the natural polymer is selected from the group consisting of sodium alginate, kappa-carrageenan / karaya gum, amide pectin, and carboxymethylcellulose (CMC). The method of claim 5, wherein the bubbling agent is a mixture of sodium bicarbonate (NaHCO ₃ ) and acetic acid, and the foam stabilizer is bovine serum albumin (BSA). The composition according to claim 7, characterized in that the composition comprises a 0.34 M aqueous solution of calcium chloride containing 1 to 2 wt% of a natural polymer, 0.9 wt% of sodium bicarbonate, 0.15 wt% of bovine serum albumin, and 10 (v / v) By weight based on the weight of the water absorbent resin. The method according to claim 5, wherein the water absorbent resin is a hydrogel. 9. An absorbent resin produced by the method of any one of claims 5 to 9. A disposable absorbent article comprising a water absorbent resin according to claim 10. 12. The disposable absorbent article of claim 11, wherein the disposable absorbent article is a diaper or a feminine hygiene article.

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