Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article
Reexamination Certificate
2002-01-14
2003-12-16
Lechert, Jr., Stephen J. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
C264S109000
Reexamination Certificate
active
06663814
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing an adsorbent block and a cleaning filter. The adsorbent block obtained by the process is preferably used in the cases where an offensive odor and harmful components are removed from a gas, such as air, and impurity ions are removed from a liquid, such as water. Therefore, the adsorbent block can be used as a cleaning filter in an air cleaning apparatus, such as an air cleaner, an air conditioner, in an water cleaning apparatus or the like, used in automobiles, home and factories.
BACKGROUND ART
For example, an air cleaner and the like are required to remove an offensive odor and the like from the air. Therefore, an adsorbent block removing an offensive odor and the like from the air is preferably used in a cleaning filter used therefor. As the adsorbent block, one having a honeycomb form formed by binding active carbon powder to have cells is known (Japanese Patent Laid-Open No. 5-242).
The conventional adsorbent block is produced roughly in the following manner. That is, a paste is prepared as a dispersion system having active carbon powder as a solid disperse phase in water as a liquid dispersion medium and containing a binder capable of dispersing various kinds of active carbon powder, and the paste is extruded to mold into a molded block in a honeycomb form. Water is then removed from the molded block to obtain an adsorbent block in a honeycomb form mainly comprising active carbon powder thus bound.
The resulting adsorbent block has continuous flow paths extending in a straight form as cells ascribed to the honeycomb form. Therefore, when the adsorbent block is used as a cleaning filter, for example, in an air cleaner, the air flows in the continuous flow paths, during which an offensive odor component and the like for having high adsorption efficiency in the resulting adsorbent in the air are adsorbed in minute pores to be removed.
DISCLOSURE OF THE INVENTION
However, in order to increase the contact area with an offensive odor component and the like in the foregoing conventional production process, the number of the continuous flow paths per unit area or unit volume is necessarily increased. In this case, when an adsorbent block in a honeycomb form is to be obtained, the number of the continuous flow paths per unit area or unit volume of the molded block of a honeycomb form itself is necessarily increased, and the production of an extruding die becomes difficult, so as to cause increase of the production cost.
This invention is made in view of the foregoing conventional circumstances, and has a problem to be solved to provide an adsorbent block having a high adsorption efficiency and can be produced at a low cost.
The first invention is a process for producing an adsorbent block comprising a first step of preparing a dispersion system comprising a liquid dispersion medium mainly having porous material powder as a solid disperse phase, and forming a molded block from said dispersion system, and
a second step of removing said liquid dispersion medium from said molded block to bind mainly said porous material powder, so as to obtain an adsorbent block formed to have continuous flow paths,
characterized in that said dispersion system contains a shrinkage agent that is capable of shrinking said molded block in said second step, and said shrinkage agent is capable of being swelled in a state of said dispersion system.
According to the test result of the inventors, in the case where a water absorbing resin or an agar component that are commercially available is employed as the shrinkage agent, and water is employed as the liquid dispersion medium, the water absorbing resin or the agar component is swelled with the liquid dispersion medium in the dispersion system. Accordingly, when the shrinkage agent is capable of being swelled in the state of the dispersion system, the molded block formed with the dispersion system is shrinked by removing the liquid dispersion medium in the second step. Therefore, according to the production process of the first invention, in the case where an adsorbent block in a honeycomb form is to be obtained, the molded block is shrinked in the second step even though the number of the continuous flow paths per unit area or unit volume of the molded block of a honeycomb form itself is not so increased, and the resulting adsorbent block has a number of the continuous flow paths per unit area or unit volume that is larger than the molded block.
Therefore, according to the production process of the first invention, the resulting adsorbent block has a large contact area with an offensive odor component and the like to have a high adsorbing efficiency. According to the production process of the first invention, since the mesh of a die for obtaining the molded block is not necessarily be fine, the production of the molded block is not difficult, and reduction of the production cost is realized.
Furthermore, when the shrinkage agent is contained in the dispersion system, the shrinkage of the molded block uniformly proceeds, and the dimensional stability of the molded block can be easily maintained.
According to a test result of the inventors, in the production process of the first invention, it is preferred that the shrinkage agent is employed in such a manner that the molded block is shrinked to a linear shrinkage ratio of from 5 to 25% per a molded block containing no shrinkage agent. The shrinkage agent that shrinks the molded block only to less than 5% per a molded block containing no shrinkage agent can exhibit substantially no effect of the invention. On the other hand, in the case of the shrinkage agent that shrinks the molded block to 25% or more per a molded block containing no shrinkage agent, molding becomes difficult, and the dimensional stability of the adsorbent block is difficult to be maintained due to distortion on shrinkage. A shrinkage agent capable of shrinking the molded block to from 7 to 20% per a molded block containing no shrinkage agent is preferred.
In the production process of the first invention, a high water absorbing resin having a large water holding ratio can be used as the shrinkage agent. As the high water absorbing resin, an acrylic series water absorbing resin, such as a starch-acrylic acid graft polymer, a crosslinked polyacrylate, a saponified product of a vinyl acetate-acrylate copolymer and the like, can be used. More specifically, a high water absorbing resin that can absorb water in a mass of from 100 to 1,000 times per unit mass is preferred. A high water absorbing resin that can absorb water in a mass of from 200 to 800 times per unit mass is more preferred, and a high water absorbing resin that can absorb water in a mass of from 400 to 700 times per unit mass is further preferred.
On the other hand, according to a test result of the inventors, in the case where a commercially available high water absorbing resin is employed as the shrinkage agent, and water is employed as the liquid dispersion medium, the high water absorbing resin can be swelled only in the dispersion system. It is considered that such a phenomenon occurs because high water adsorbing resin is crosslinked, even when a large amount of water is involved, the network structure of the linear molecules is stretched at all. In this case, therefore, the molded block is shrinked only at a low shrinkage ratio, and the improvement of the adsorption efficiency is limited. In order to avoid the phenomenon, it is necessary that the average particle diameter of the high water absorbing resin is decreased to solve the crosslinking of the high water absorbing resin, but the molded block is still shrinked at a low shrinkage ratio, and such a step is necessary that the high water absorbing resin is pulverized, whereby increase of the production cost occurs.
On the other hand, in the case where an agar component is employed as the shrinkage agent, and water is employed as the liquid dispersion medium, the agar component can be infinitely swelled in the dispersion system since it is easily dissol
Andou Masao
Kamei Akira
Kondou Syouko
Murase Kazuhisa
Kabushikikaisha Equos Research Co., Ltd.
Lechert Jr. Stephen J.
Lorusso, Loud & Kelly
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