Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2002-08-07
2004-03-09
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S150000, C525S301000, C525S296000, C525S327400, C525S327500, C525S329400, C525S329900, C525S330400
Reexamination Certificate
active
06703432
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to materials adsorbing/desorbing water in gases. Particularly, the present invention relates to desiccants used for controlling the humidity in air-conditioners.
PRIOR ART
Desiccant air-conditioners incorporating an equipment capable of continuously adsorbing/desorbing water with a desiccant have been commercialized.
Performance of such desiccant air-conditioners greatly depends on the performance of the desiccant used therein. Conventional desiccants for this purpose were inorganic desiccants such as silica gel and zeolite. Such desiccants are used to adsorb water at room temperature, and after they are used for a period, they should desorb water by passing high temperature air therethrough to regenerate adsorption performance. The above inorganic materials could attain a reasonable performance in a wide temperature range from 20° C. for water adsorption to 100° C. for water desorption because they are heat-resistant enough to endure air flow at a high temperature of 100° C. or more fed to desiccants.
However, further improvement in performance of desiccants is required from the social background of resource saving, energy saving and global environmental protection. Namely, there is an urgent need for measures against the heating temperature of the regenerating air, the heat capacity of desiccants, formability, selection of readily disposable materials, etc.
As one of measures, the use of organic polymer materials having a water adsorbing/desorbing function has been proposed and suggested to be capable of lowering the heating temperature of the regenerating air. Representative examples of such organic polymer materials having a water adsorbing/desorbing function are ion exchange resins.
Water adsorbing/desorbing performance of organic polymer materials greatly depends on the nature of the functional group (hydrophilic group) and the polymer structure. Hydrophilic groups can adsorb water by coordinating water around them, but sufficient water adsorbing/desorbing performance cannot be expected unless organic polymers have a polymer structure in which water molecules can readily diffuse around hydrophilic groups.
In all desiccants comprising organic polymer materials so far proposed including ion exchange resins, the polymer chain has a crosslinked structure, which blocks diffusion of water molecules so that these desiccants could not attain sufficient water adsorbing/desorbing performance though they have a hydrophilic group, whereby they had to be charged in considerable amounts in desiccant air-conditioners or involved high costs.
DISCLOSURE OF THE INVENTION
The present invention solves the problems of desiccants comprising conventional organic polymer materials as described above and provides a water adsorbing/desorbing organic polymer material having excellent water adsorbing/desorbing performance.
The present invention relates to a water adsorbing/desorbing material characterized by having a polymer side chain containing a hydrophilic group on the backbone of an organic polymer base.
Generally, water adsorbing/desorbing materials comprising an organic polymer contain a hydrophilic group on their polymer backbones to confer a water adsorbing/desorbing function and the polymer backbones are crosslinked to each other to compensate for deterioration of physical strength due to introduction of this hydrophilic group. Typical examples thereof are ion exchange resins, in which an ion exchange group such as a sulfone or quaternary ammonium group has been generally introduced into the backbone of a polystyrene obtained by polymerizing a styrene monomer. However, these ion exchange groups become bulky by coordinating several water molecules around them once they adsorb water, so that the resins are insufficient in physical strength and dissolve even in water. In order to solve this problem with ion exchange resins, polystyrene backbones are crosslinked to each other with a crosslinker such as divinylbenzene. This enhances physical strength of the resins, which no more dissolve in water at the expense of lowered absorption/desorption functions such as absorption speed or diffusion speed due to the formation of a crosslinked structure.
According to the present invention, it was found that excellent water adsorbing/desorbing performance can be conferred on an organic polymer base while keeping physical strength of the polymer backbone by introducing a side chain in the form of a polymer chain containing a hydrophilic group onto the polymer backbone of the base. Water adsorbing/desorbing materials of the present invention can considerably keep adsorption/desorption speed and diffusion speed because their polymer backbones have no more crosslinked structure. In water adsorbing/desorbing materials of the present invention, their polymer backbones have the role of keeping physical strength or shape.
THE MOST PREFERRED EMBODIMENTS OF THE INVENTION
In water adsorbing/desorbing organic polymer materials of the present invention, suitable means for introducing a side chain in the form of a polymer chain containing a hydrophilic group onto the polymer backbone include graft polymerization. Especially, radiation-induced graft polymerization is most preferred for the purpose of the present invention, because a desired graft polymer side chain can be introduced into an organic polymer base by irradiating the base to produce a radical and reacting it with a graft monomer and the number or length of the graft chain can be relatively freely controlled and the polymer side chain can be introduced into existing polymer materials in various shapes.
In the present invention, materials that can be used as bases into which is introduced a side chain in the form of a polymer chain containing a hydrophilic group include elemental polymer fibers and woven and nonwoven fabrics comprising an assembly thereof. Woven
onwoven fabric materials can be suitably used as bases for radiation-induced graft polymerization and they have a large surface area and are light and easy to process. Water adsorbing/desorbing materials prepared from woven
onwoven fabrics can be easily handled during disposal and readily incinerated, in contrast to conventional ion exchange resins having a crosslinked structure that are hard to incinerate.
Radiations that can be used in radiation-induced graft polymerization well suitable for the purpose of the present invention include &agr;-rays, &bgr;-rays, &ggr;-rays, electron rays, UV ray, etc., among which &ggr;-rays and electron rays are preferred for use in the present invention. Radiation-induced graft polymerization includes preirradiation graft polymerization involving preliminarily irradiating a graft base and then bringing it into contact with a polymerizable monomer (graft monomer) for reaction, and simultaneous irradiation graft polymerization involving irradiating a system containing a base and a monomer, and either method can be used in the present invention. Radiation-induced graft polymerization includes various manners of contact between a monomer and a base, such as liquid phase graft polymerization performed with a base immersed in a monomer solution, gas phase graft polymerization performed with a base in contact with the vapor of a monomer, or immersion gas phase graft polymerization performed by immersing a base in a monomer solution and then removing it from the monomer solution for reaction in a gas phase, and any method can be used in the present invention.
Fibers and woven
onwoven fabrics comprising a fiber assembly are the most preferred materials for use as organic polymer bases for water adsorbing/desorbing materials of the present invention, and are well suitable for use in the immersion gas phase graft polymerization because they tend to retain monomer solutions.
The hydrophilic group as a functional group for adsorbing/desorbing water in water adsorbing/desorbing organic polymer materials of the present invention can be selected from ion exchange groups such as cation exchange groups and anion exchange groups
Arimitsu Hidenobu
Fujiwara Kunio
Takeda Kazuyoshi
Yokota Hiroshi
Asinovsky Olga
Ebara Corporation
Seidleck James J.
Wenderoth , Lind & Ponack, L.L.P.
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