WO2010011016A1

WO2010011016A1 - Desiccant, dehumidifying element and methods for manufacturing the same

Info

Publication number: WO2010011016A1
Application number: PCT/KR2009/001897
Authority: WO
Inventors: Dae-Young Lee
Original assignee: Korea Institute Of Science And Technology
Priority date: 2008-07-24
Filing date: 2009-04-14
Publication date: 2010-01-28
Also published as: KR100963116B1; KR20100011214A

Abstract

Disclosed are a desiccant having a Superabsorbent Polymer (SAP) and a hygroscopic salt, in which the SAP includes a first element having an electrostatic repulsion and a second element having a hydrophilic property, a dehumidifying element using the same and methods for fabricating the same.

Description

DESICCANT, DEHUMIDIFYING ELEMENT AND METHODS FOR MANUFACTURING THE SAME

The present invention relates to a desiccant, a dehumidifying element, and methods for manufacturing the same.

A humidity exchanger element dehumidifies gas by sorption mechanism of the desiccants, such as aluminum oxide-silicate or titanium silicate/titanium-aluminum silicate.

According to U.S. Patent No. 5,505,769, the elements can be included within a sheet composed of inorganic fibers, or can be included within a device formed with the sheet.

However, the conventional humidity exchanger element necessitates regeneration at excessively elevated temperatures (approximately 90~150℃). In addition, the element has demerits that a sorption capacity thereof is limited and that it causes a large amount of pressure loss of air to be dehumidified. Also, the sorption capacity of the humidity exchanger element is gradually decreased in length of time, i.e., influenced by aging.

In addition, a nucleus and a bio-film are formed while the humidity exchanger element dehumidifies, thereby undesirably closing pores of the humidity exchanger element.

According to G. Heinrich's paper entitled sorption-supported air-conditioning published by the C. F. M ller Publishing Company (Heidelberg) in 1997, a dehumidifying element was fabricated by a corrugated cardboard containing lithium chloride therein, whereby hygroscopic characteristics of lithium chloride are used for dehumidifying.

However, lithium chloride is evaporated by a flow of air contacting the dehumidifying element, thus to deteriorate dehumidifying performance of the element.

It has been known that the humidity exchanger element limits an allowable humidity of air to be dehumidified. This is because lithium chloride tends to absorb moisture in the air to liquefy, especially under conditions of high humidity.

More specifically, a solid lithium chloride included in the element is changed into a liquid lithium chloride in a humid condition while cellulose comes to be unable to sufficiently absorb and retain the liquid lithium chloride due to its limited sorption capacity. By this, liquid lithium chloride is dripping away from the dehumidifying element, thus to have a reduced content of lithium chloride in the element.

Therefore, it is an object of the present invention to provide a desiccant capable of stably absorbing moisture greater than a certain level regardless of any changes in relative humidity of air to be dehumidified, a dehumidifying element using the same, and a method for fabricating the same.

To achieve the-above described object, the present invention is to highly enhance a sorption characteristic of a superabsorbent polymer (SAP) by an ion modification in which a hygroscopic salt is absorbed in the SAP. In addition, since the SAP includes a first element having an electrostatic repulsion and a second element having a hydrophilic property, the SAP may absorb a salt solution, regardless of the salt concentration of the salt solution formed by deliquescence of a hygroscopic salt according to relative humidity, thus to prevent the salt solution loss.

To achieve these objects, the present invention provides two methods:

A first method comprises a step of contacting a superabsorbent polymer (SAP) and a hygroscopic salt solution for ion modification of the superabsorbent polymer, and a step of drying a hydrogel formed by the contact of the superabsorbent polymer and the hygroscopic salt solution.

A second method comprises a step of coupling a superabsorbent polymer (SAP) to a carrier, a step of contacting the carrier to which the SAP is coupled to a hygroscopic salt solution for ion modification of the SAP, and a step of drying the carrier to which the SAP is coupled.

The desiccant and the dehumidifying element according to the present invention contain a superabsorbent polymer (SAP) consisting of an element having an electrostatic repulsion as well as an element having hydrophilic properties. Accordingly, regardless of any change in relative humidity of air to be dehumidified, the desiccant and the dehumidifying element may stably absorb moisture by complementary operations of the two elements.

Figure 1 is a graph showing respective absorption characteristics of polyacrylic acid and polyacrylamide in a salt solution according to salt concentrations thereof;

Figure 2 is a graph showing respective absorption characteristics of polyacrylic acid, polyacrylamide, and copolymers thereof in a salt solution according to salt concentrations thereof;

Figure 3 is a graph showing respective absorption characteristics when relative humidity is 40% and 95% according to a ratio of polyacrylamide;

Figure 4 is a graph showing a maximum ratio of ion modification obtained by fitting each graph of the absorption characteristics in a relative humidity of 40% and 95% in Fig. 3;

Figure 5 is a chemical structure of Carboxy Methyl Cellulose (CMC);

Figure 6 is a longitudinal sectional view showing a porous carrier consisting of fibers and granules containing a superabsorbent polymer (SAP), in which the granules are applied thereon;

Figure 7 is a longitudinal sectional view of a porous carrier having a wave shape of a trapezium and formed with a structured sheet;

Figure 8 is a perspective view of the porous carrier of Fig. 7; and

Figures 9(a), (b) and (c) are respective schematic views showing examples of arranging a plurality of structured and/or flat sheets by a method in which spatial 3-dimensional channels are formed.

Description will now be given in detail to the desiccant, the dehumidifying element and a method for fabricating the same according to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

The dehumidifying element according to the present invention includes a superabsorbent polymer (SAP) so as to absorb extremely large amounts of water or steam relative to its own weight. For instance, when relative humidity is more than 40%, the dehumidifying element may absorb more than 4 times larger amount of moisture as compared to silicate.

In exemplary embodiments of the present invention, a preferred superabsorbent polymer contains a first element having an electrostatic repulsion and a second element having hydrophilic properties. The first and second elements may be weakly cross-linked copolymers. More specifically, the first element includes polyacrylic acid or polymethacrylic acid. The second element may include at least one of polyacryl amide, polyvinyl alcohol, polyvinyl amine, ethylene oxide, starch and cellulose. The superabsorbent polymer may include Carboxy Methyl Cellulose (CMC) having both the electrostatic repulsion and hydrophilic properties in itself.

Validity of such described structures (the first and second elements) of the SAP according to one exemplary embodiment of the present invention will be described in detail.

If the superabsorbent polymer containing a hygroscopic salt therein is used as a desiccant or a dehumidifying element, the amount of moisture absorbed by the SAP itself is very minute. In a liquid material, the SAP has a high absorbency, but its absorbency is insignificant to a gaseous material. Therefore, the dehumidifying mechanism is performed in which a hygroscopic salt primarily absorbs a gaseous material (i.e., moisture) to be deliquesced, and the SAP absorbs and retains the salt solution prepared by the deliquescence.

The amount of moisture absorbed by the hygroscopic salt depends on relative humidity. As the relative humidity increases, the absorption amount is increased. The hygroscopic salt is deliquesced to form a greater amount of salt solution as compared to when the relative humidity is low. Accordingly, under conditions of low humidity, the amount of the salt solution formed is small and salt concentration of the salt solution is high. As the humidity increases, the amount of salt solution increases and the salt concentration is lowered.

According to salt concentration in the salt solution and/or a type of a superabsorbent polymer, the amount of the salt solution absorbed by the SAP may vary.

Figure 1 is a graph showing a change in an absorption amount of superabsorbent polymer according to concentration of a lithium chloride solution. In Fig. 1, lithium chloride was used as hygroscopic salt.

Referring to Fig. 1, polyacrylic acid had a great absorption amount of salt solution under low concentration of the salt solution. As the concentration thereof increased, the absorption amount of the salt solution was rapidly decreased. On the contrary, polyacryl amid was appeared to absorb an almost uniform amount of salt solution, without having any great change in absorption amount according to the concentration of salt solution.

Consequently, considering that relative humidity of a condition where the desiccant is placed cannot be specified as a certain value, the present inventor has recognized that it would be useful to mix, at an appropriate ratio, polyacrylic acid advantageous to high humidity (low concentration) and polyacryl amid advantageous to low humidity (high concentration) together. If a copolymer thereof and the like are prepared, absorption characteristics (further, dehumidifying characteristics) of the salt solution at a certain level may be obtained, regardless of any changes in relative humidity.

Referring to Fig. 2, a change in an absorption amount of the salt solution when a mixture ratio of a first element (with the electrostatic repulsion) and a second element (with hydrophilic properties) mixed in the SAP is changed, will be described.

A copolymer was comprised of polyacrylic acid as one of the first element of the SAP and polyacryl amid as one of the second element of the SAP in the ratio of 4: 1. In this case, the absorption characteristic of the salt solution thereof was very similar to that of the salt solution in case when polyacrylic acid only was used. More specifically, the copolymer in low concentration had the absorption characteristic less than polyacrylic acid, while the copolymer in high concentration had the absorption characteristic greater than polyacrylic acid by the operation of polyacryl amid.

If a copolymer was comprised of polyacrylic acid and polyacryl amid as the SAP in the ratio of 1:1, the absorption characteristic in low concentration was reduced as compared to when polyacrylic acid only was used. However, in high concentration, the absorption characteristic was greatly enhanced. In particular, the absorption characteristic in high concentration would be very close to the absorption characteristic of polyacryl amid.

If a copolymer was comprised of polyacrylic acid and polyacryl amid as the SAP in the ratio of 1:2, the absorption characteristic in low concentration was somewhat reduced as compared to the previous example, however, the absorption characteristic in high concentration was almost the same as the previous example. This is because the absorption amount of the salt solution in low concentration is reduced as the ratio of polyacrylic acid is decreased.

Based on such results, as the ratio of the second element was increased, the amount of the salt solution having been absorbed was increased in high concentration but reduced in low concentration.

Referring to Fig. 3, a ratio of the second element may appropriately be obtained with an assumption that relative humidity in a space where the dehumidifier is placed is 40% ~ 95%. In this example, the ratio of ion modification of the SAP is 1.

If the relative humidity was 40%, when polyacryl amid as the second element has an increasing percentage among the SAP, the absorption characteristic (allowable absorption amount/required absorption amount) rapidly increases in a tier shape. When the relative humidity was less than 40%, the absorption characteristic was very similar to when the relative humidity was 40%.

On the contrary, if the relative humidity was 95%, as the ratio of polyacryl amid increased, the absorption characteristic was gradually reduced.

Preferably, the absorption characteristic depending on the ratio of polyacryl amid is more than 1. This is to prevent a loss of the salt solution only if an amount greater than an absorption amount required can be absorbed.

Graphs showing the absorption characteristic of the desiccants each under relative humidity of 40% and 95%, and the straight line having the absorption characteristic of 1 would be crossed at where the ratios of polyacryl amid among the SAP are respectively 0.35 and 0.56. The absorption characteristic under each relative humidity is, preferably, more than 1. Accordingly, the ratio of polyacryl amid among the SAP in the desiccant is determined to be 0.35~0.56.

Referring to Fig. 4, description of a maximum ratio of ion modification of the SAP depending on the ratio of polyacryl amid will be given in detail.

Figure 4 is a graph showing a maximum ratio of ion modification obtained by fitting a portion having a small absorption characteristic in the graphs showing the absorption characteristics in the relative humidity of 40% and 95% in Fig. 3. This graph indicates a maximum ratio of ion modification when the SAP is able to entirely absorb the salt solution formed by which a hygroscopic salt absorbs moisture, regardless of a degree (high or low) of relative humidity.

First, the ion modification ratio is a mixture ratio of the SAP to hygroscopic salt. A low mixture ratio indicates a low rate of the hygroscopic salt in the desiccant. Such low rate of the salt also indicates that an amount of the salt solution formed by which the salt absorbs moisture is not great. In terms of the sorption amount, the higher ion modification ratio is better. However, since the amount of the salt solution to be formed is increased, the absorption capacity of the SAP should be enhanced to increase the ion modification ratio.

In the graph, a ratio of polyacryl amid for a maximum ion modification ratio is approximately 0.4. The ion modification ratio becomes approximately 1.1.

If the ion modification ratio is 1, as shown in Fig. 3, it is preferable that the ratio of polyacryl amid has a value in the range of 0.35 to 0.56.

Referring to Fig. 5, the CMC in itself has COONa having an electrostatic repulsion and OH having hydrophilic properties.

If the CMC is employed as the SAP, it may be used as a desiccant by contacting a hygroscopic salt solution through ion modification.

The ion-modified SAP desiccant may be fabricated to have a certain shape in itself, or accommodated within a container formed of a material to enable gas to pass through. The ion-modified SAP desiccant may be contained in a porous carrier and/or attached onto an outer surface thereof so as to be appropriately modified according to its usage, thus to form a variety of dehumidifying elements.

The ion-modified SAP desiccant may be formed as granules. The granulated desiccant may be accommodated in a container where gas may pass through or fixed on a carrier having a certain shape.

If the desiccant is formed as granules, a particle diameter thereof is, preferably, selected in the range of 0㎛ and 10,000㎛, more preferably, grain fractions in the range of 1㎛ and 5,000㎛, and most preferably, grain fractions in the range of 20㎛ and 1,000㎛.

If the ion-modified SAP desiccant is implemented as a fiber, a dehumidifying element using the same may include a textile, mesh, knitted fabric, knit and/or a bonded fabric. Combination of the previous examples regarding the porous carrier may also be possible.

Preferred methods for applying the SAP desiccant in the carrier or on the surface of the carrier may include a method for coating the porous carrier with the dehumidifying element and/or a method for inserting the dehumidifying element in the porous carrier.

Preferably, the porous carrier may be implemented as a fiber composite comprised of a natural fiber and a synthetic fiber, thus to enhance a moisture-carrying characteristic by the natural fiber as well as a mechanical property of the porous carrier by the synthetic fiber.

If the porous carrier is formed as a single layer or multi-layers, and if the porous carrier is formed as one or plural sheets to be flat or structured, it may be formed as a dehumidifying body in which air flows along a periphery thereof and/or air passes therethrough. Preferably, the sheet is structured in which a waveform thereof is formed as a trapezoid or a triangle in a horizontal sectional surface. Then, in a manner in which spatial 3-dimensional channels are formed, a plurality of structured and/or smooth (flat) sheets may be arranged. Air to be dehumidified may be guided through the channels.

The sorption characteristics of the dehumidifying element may be achieved by selecting the salt solution. By drying the SAP first, the SAP can absorb the salt solution much more, thereby contacting a greater amount of hygroscopic salt to the SAP. The hydrogel formed by contacting the salt solution to SAP is dried to be converted into a state capable of absorbing moisture.

When the granules of the SAP are bonded (coupled) to each other and thereby to form a large agglomeration, it is preferable that the agglomeration of the SAP is crushed into pieces (granules) before contacting the salt solution. By this, the element having a uniform sorption characteristic may be formed. Likewise, if the granules form a large agglomeration after the step of a final drying, it is also desirable to crush the agglomeration of the SAP into pieces.

Another method for fabricating a dehumidifying element containing an ion-modified SAP desiccant is to contact the carrier containing the SAP with a salt solution. If the carrier containing the SAP is contacted to the salt solution and dried slowly at a slowly increasing drying temperature, a regeneration of a dehumidifying element may be smoothly performed, thus to guarantee an excellent absorption of the salt solution by the SAP. When the carrier was directly dried at a maximum regeneration temperature, the salt solution was found to be extracted on the surface of the carrier, instead of perfectly being absorbed by the SAP.

One of the important factors in preparation of the dehumidifying element is that a salt solution to be used for ion modification should include hygroscopic salt of 5~30wt%. If the salt solution with such concentration is to be used, the sorption characteristic of the SAP ion-modified by the hygroscopic salt may be optimized between a limit (restriction) of an ion concentration at a too high level and a limit of the absorption amount of the SAP.

When the carrier containing the granulated SAPs is contacted to the salt solution, if the absorption capacity of the salt solution is very high, the granule particles tend to be agglomerated and thereby to form a large lump after a step of drying. Therefore, it is preferable that the carrier is contacted to the salt solution in several steps. In each step, the carrier should be contacted with only a portion of the salt solution. Here, the contact may be performed by drizzling, sprinkling, spraying, and the like.

Figure 6 is a longitudinal sectional view of the dehumidifying element according to the present invention.

As shown in Fig. 6, the dehumidifying element according to the present invention is comprised of a porous carrier 2 having granular particles 1.

The granular particles 1 include the SAP, and the SAP is contacted to a hygroscopic salt (not shown). Here, the carrier 2 consists of a fiber formed of a natural and/or composite polymer, and a filament. In addition, the carrier 2 includes fibers 3 containing the SAP therein. The fibers 3, similar to the granules 1, may be minutely distributed to contact the hygroscopic salt, as well as applied on the surface of the porous carrier 2.

A particle diameter of each granule 1 is almost the same, which is in the range of 20 ~ 1,000㎛. Less preferred but always acceptable, a diameter of a grain fraction is in the range of 1㎛ ~ 5,000㎛, among which particles of 0.1㎛m ~ 20㎛ are basically considered. The SAP forming the granules includes a polymer and a copolymer of weakly cross-linked acryl acid, or cross-linked starch and cellulose derivatives.

The granules 1 having the minutely distributed hygroscopic salt therein may form the carrier in itself (i.e., without having a separate carrier) so as to perform a dehumidifying function. In addition, the granules 1 may be coated on the surface of the porous carrier 2. The granules 1 may also be included in the porous carrier 2, and in case the porous carrier 2 is a fiber composite, the SAP may be integrated within the carrier 2 as a part of the fibers.

Such fiber composite has a matrix structure and includes natural fibers, or one or plural artificial fiber materials as reinforcing fibers. Here, the artificial fiber material enhances mechanical characteristics of the porous carrier 2 or the fiber composite, while the natural fiber performs a function of carrying humidity.

In addition, the natural fiber stores its humidity, i.e., water vapor, water or an aqueous solution. The porous carrier is a fiber composite consisting of a fiber and/or a filament. Examples of such porous carrier may include textile, meshed textile, knitted fabric, knit, a combination thereof, a bonded fabric, and the like.

The contact between the SAP and the hygroscopic salt is performed by soaking the SAP granules or fibers into a water-based solution of the hygroscopic salt, drizzling, sprinkling, or by other techniques, while the SAP absorbs the salt solution by its own absorption characteristic.

Another method for contacting the SAP to the salt solution is to contact the SAP granules or the SAP fibers to the salt solution when the SAP granules or the SAP fibers have already positioned inside the porous carrier or attached onto the surface of the carrier before ion modification.

If the porous carrier is to be modified, structured, or arranged in several fabrication steps, the modification for contacting the SAP to the salt solution may be performed at any of the multiple fabrication steps for the porous carrier by considering a time point when the modification for contacting the SAP to the salt solution occurs best.

For the ion modification of the SAP granules or the SAP fibers, a salt solution needs to be selected first. The salt solution may include a strong hygroscopic salt (e.g., lithium chloride, magnesium chloride, calcium chloride or lithium bromide), and water as a solvent.

There is a need to dry the granules or fibers before contacting the salt solution such that a minimum residual content of moisture in the SAP is retained to enable the SAP to absorb the salt solution as much as possible later when contacting the salt solution. For this, a vacuum drier is preferred. This is because thermal loads minutely exerted by the vacuum drier are applied to the granules at the time of drying, thus to prevent deterioration in temperature stability of the SAP in the long term.

Next, the dried SAP granules are ion-modified by the salt solution, which may be variously processed. For instance, the SAP granules may be put into the salt solution or the solution may be added to the SAP granules.

After the ion modification, a hydrogel formed by the SAP granules is dried to re-granulate. The hydrogel is applied on a plate as thin as possible so as to prevent any lump formation in the drying step. Nevertheless, if there is any lump formation, it needs to be crushed using an impact crusher or a breaker.

When the SAP granules or the SAP fibers have already been coupled (bonded) to the carrier, and if the SAP ion modification is to be performed, the carrier containing the SAP should be dried so as to reduce the water content therein to a minimum extent. The selection of the salt solution is carried out similar to the aforementioned methods.

When the porous carrier 2 containing the

SAPs

1 and 3 is contacted to the salt solution, such contact process should be considered to be carried out in multiple steps. This is because when the SAPs absorb the salt solution too strong, similar to the modification in the granules, the lump formation may occur within the porous carrier 2 or thereon due to the coupling between the granulate particles 1. Differently from the ion modification of the SAP itself, the lump formed by the ion modification of the SAP included in the carrier cannot be crushed into pieces. Therefore, it is very important to prevent the lump formation in the process of contacting the salt solution. The solution can be prudently contacted with the SAP-containing carrier in multiple steps through drizzling, sprinkling, spraying, or the like.

Lastly, the carrier 2 containing the SAP is dried slowly, and a drying temperature gradually increases until it rises to almost the maximum regeneration temperature.

The step of drying the SAP-contained carrier 2 at slowly increasing temperature serves to maintain the structure of the modified SAP. That is, the SAP is not decomposed. Examples of such drying method include a freeze drying, a microwave drying, a normal drying, or a combination thereof.

In order to increase a contact area between the dehumidified air and the dehumidifying element containing the ion-modified SAP granules or SAP fibers, a method for fabricating a dehumidifying element may also be carried out. Examples of a structured dehumidifying element may include, as shown in Figs. 7 and 8, a trapezoid corrugation as a structured sheet. The sheet of a corrugated reed shape has a ripple of 2.5~7㎜, an interval length (a), a ripple of 1 ~ 5㎜, and a wave height (b).

Here, the formation process is implemented as an embossing process using a rippling or a stamping under a heat reaction at 180℃.

Figures 9(a), (b) and (c) are respective schematic views showing examples in which the plural sheets according to Figs. 6 and 7 are arranged by a method in which 3-dimensional channels are formed.

Here, gas to be dehumidified, e.g., air, may pass through the channels or flow at a periphery thereof.

In Fig. 9(a), a combination of a structured sheet and a flat sheet forms a structure. This structure may easily be wound onto or stacked on a dehumidifying body, thereby properly being arranged similar to a general humidity exchanging body.

Figure 9(b) shows two sheets structured as a trapezoid. The sheets having a honeycombed structure may form 3-dimensional channels as shown in Fig. 9(a). The channels allow gas to be dehumidified to pass therethrough.

Figure 9(c) illustrates a plurality of layers based on the arrangement in Fig. 9(b), by which a dehumidifying body having 3-dimensional channels may be formed.

Regardless of a time point when the ion modification is performed, i.e., regardless of whether or not the SPA granules or the SAP fibers are contacted to the hygroscopic salt, whether or not the SPA granules or the SAP fibers are contacted to the hygroscopic salt while being positioned in the porous carrier or thereon (Fig. 6), or whether or not the modification is started after the various transformation steps of the porous carrier (Figs. 8, 9(b) and 9(c)), lithium chloride adjacent onto the surface of the SAP permits water to be added as well as water to be guided to the inside of the superabsorber.

Preferably, the salt is spontaneously regenerated as water is guided into the superabsorber, while humidity is moved into the superabsorber thus not to remain on the surface any longer.

It will also be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

The desiccant and the dehumidifying element according to the present invention may stably absorb moisture greater than a certain level regardless of a change in relative humidity of air, by having the SAP consisting of the element having the electrostatic repulsion and the element having the hydrophilic property, thus to have a high industrial applicability in the fields of air conditioning, and the like.

Claims

A method for fabricating a desiccant, comprising:

contacting a Superabsorbent Polymer (SAP) to a hygroscopic salt solution for an ion modification of the SAP; and

drying a hydrogel formed by the contact between the SAP and the hygroscopic salt solution,

wherein the SAP includes a first element having an electrostatic repulsion and a second element having a hydrophilic property.
The method of claim 1, wherein the first element includes polyacrylic acid or polymethacrylic acid, and the second element includes at least one of polyacryl amide, polyvinyl alcohol, polyvinyl amine, ethylene oxide, starch and cellulose.
The method of claim 1, wherein the SAP includes Carboxy Methyl Cellulose (CMC).
The method of claim 1, wherein the hygroscopic salt includes at least one of lithium chloride, magnesium chloride, calcium chloride and lithium bromide.
The method of claim 1, wherein the concentration of the hygroscopic salt solution is in the range of 5~30wt%.
The method of claim 1, further comprising:

drying the SAP before the SAP contacts the hygroscopic salt solution.
A method for fabricating a dehumidifying element, comprising:

coupling a Superabsorbent Polymer (SAP) to a carrier;

contacting the carrier to which the SAP is coupled to a hygroscopic salt solution for an ion modification of the SAP; and

drying the carrier to which the SAP is coupled,

wherein the SAP includes a first element having an electrostatic repulsion and a second element having a hydrophilic property.
The method of claim 7, further comprising:

drying the SAP coupled to the carrier before the SAP-coupled carrier contacts the hygroscopic salt solution.
The method of claim 7, wherein the first element includes polyacrylic acid or polymethacrylic acid, and the second element includes at least one of polyacryl amide, polyvinyl alcohol, polyvinyl amine, ethylene oxide, starch and cellulose.
The method of claim 7, wherein the SAP includes Carboxy Methyl Cellulose (CMC).
The method of claim 7, wherein the hygroscopic salt includes at least one of lithium chloride, magnesium chloride, calcium chloride and lithium bromide.
The method of claim 7, wherein the concentration of the hygroscopic salt solution is in the range of 5~30wt%.
The method of claim 7, wherein the hygroscopic salt solution includes water as a solvent.
The method of claim 7, wherein the contact between the carrier and the hygroscopic salt solution is performed by soaking the carrier into the hygroscopic salt solution, or sprinkling the hygroscopic salt solution on the carrier.
The method of claim 7, wherein the contact between the carrier and the hygroscopic salt solution is performed twice or more.
A desiccant, comprising:

a Superabsorbent Polymer (SAP) consisting of a first element having an electrostatic repulsion and a second element having a hydrophilic property; and

a hygroscopic salt.
The desiccant of claim 16, wherein the first element includes polyacrylic acid or polymethacrylic acid, and the second element includes at least one of polyacryl amide, polyvinyl alcohol, polyvinyl amine, ethylene oxide, starch and cellulose.
The desiccant of claim 16, wherein the SAP includes Carboxy Methyl Cellulose (CMC).
The desiccant of claim 16, wherein the SAP is formed with granules.
The desiccant of claim 19, wherein a particle diameter of the granule is up to 1,000㎛.
The desiccant of claim 16, wherein the SAP is comprised of a fiber or a filament.
The desiccant of claim 16, wherein the hygroscopic salt includes at least one of lithium chloride, magnesium chloride, calcium chloride and lithium bromide.
A dehumidifying element comprised of the desiccant only according to claim 16.
A dehumidifying element in which a surface of a carrier is coated with the desiccant according to claim 16.
The dehumidifying element of claim 24, wherein the carrier is formed to permit gas to pass through.
The dehumidifying element of claim 24, wherein the desiccant is included in the carrier.
The dehumidifying element of claim 24, wherein the desiccant is formed with granules or fibers.
The dehumidifying element of claim 24, wherein the carrier is formed by one or more combinations of textile, mesh, knitted fabric, knit and a bonded fabric.
The dehumidifying element of claim 24, wherein the carrier is formed by one or more combinations of a fiber and a filament.
The dehumidifying element of claim 29, wherein the fiber and the filament are formed by one or more combinations of a natural fiber and a composite polymer.
The dehumidifying element of claim 24, wherein the carrier is implemented as a sheet formed in a single layer or multiple layers.