1. Field of the Invention
The present invention relates to a method for preparing a dehumidifying element and an apparatus thereof, and more particularly, to a method for preparing a dehumidifying element including a superabsorbent polymer and a hygroscopic salt, and an apparatus thereof capable of precisely controlling the amount of the hygroscopic salt, shortening time involved in the preparation thereof, thereby reducing the preparation cost.
2. Description of the Background Art
A dehumidifying element serves to remove moisture from surroundings by absorbing and holding water vapor, and is widely used in the rainy season or at a place where excessive moisture is undesirable or dry environment is required. To this end, although silica gel has been used, as the silica gel has a limited dehumidifying capacity of at maximum 45% of the dry weight mass thereof, the silica gel cannot maintain an excellent dehumidifying function for a long time.
Accordingly, the applicant of the present invention has devised a dehumidifying element having an absorbing capacity of 100 to 500 percent of the dry mass thereof by using a superabsorbent polymer (SAP), which is disclosed in Korean Patent Publication No. 2004-71246. According to the present invention, the SAP is bonded with a hygroscopic salt such as lithium chloride, thereby increasing the hygroscopic property.
As disclosed in the Korean Patent Publication No. 2004-71246, a method for preparing a dehumidifying element comprises selecting a salt solution, drying a superabsorbent polymer (SAP), contacting the dried SAP to the salt solution, thereby generating hydrogel, and drying the hydrogel. The dried hydrogel is used as the dehumidifying element by being packaged or by being attached according to the purpose of its use.
However, in the conventional method, a significant amount of solvent absorbed into the dehumidifying element (i.e., SAP with a salt) should be removed by an evaporation process, and thus, the conventional method requires a long time and a large energy consumption for the preparation. Furthermore, while the hydrogel is dried, the SAP particles cling to each other to form a large conglomerate. The large conglomerate has to be crushed back into small particles for proper usage.
Additionally, in case that a salt solution having a high concentration is absorbed into the SAP, the SAP absorbs the salt excessively thereby causing deliquescence during the dehumidifying process. On the other hand, if deliquescence occurs, the liquid tends to flow or be entrained into the air stream to cause a loss of the hygroscopic salt resulting in a gradual decrease in the dehumidifying capacity. If the amount of the salt solution contacting the SAP is reduced in order to limit the amount of the salt to be absorbed, the salt solution is not uniformly distributed in the SAP, thereby causing local deliquescence during the dehumidifying process. That is, if the amount of the inorganic salt for enhancing hygroscopic property is not controlled precisely, the dehumidifying element tends to deliquesce during the dehumidifying process.
Additionally, since the SAP comes in contact with the inorganic salt solution by soaking the SAP into the inorganic salt solution or by spraying the inorganic salt solution onto the SAP, it is difficult to check the exact amount of the inorganic salt solution absorbed into the SAP.
Therefore, in order to secure the reliability of the dehumidifying element, the amount of the inorganic salt absorbed into the SAP has to be controlled with precision and the mixing ratio between the SAP and the inorganic salt has to be uniformly maintained. To this end, a new method for preparing a dehumidifying element using superabsorbent polymer is highly in demand.