Liquid purification or separation – With repair or assembling means
Patent
1993-03-23
1996-02-20
Spear, Frank
Liquid purification or separation
With repair or assembling means
210448, 210453, 21050025, B01D 7102
Patent
active
054926238
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a laminated filter material, its fabricating method and a filter using a laminated filter material having improved filterability.
BACKGROUND OF THE INVENTION
Recently, improvements in filtering precision is desired for the filtration of liquids to remove foreign materials of about several microns in the high polymer industrial field and filtration of gases to remove foreign materials of 0.1 .mu.m or less, for example, from process gas used in the electronics field mainly for semiconductors. A reduction of pressure loss in filtration is also demanded.
Specifically, filtration systems used to filter process gas used in manufacturing semiconductors must be heat resistant for baking treatment, and corrosion resistant, because a corrosive gas is often be used. Furthermore, characteristics such as toughness and flexibility, ease of mounting on a housing and ease in after-processing are also desired. Here, the baking treatment is to remove harmful moisture adhered to and existing in the filtration system by heating an entire filtration system, including the filter, for example, to about 200 to 400 deg. C.
Although high polymer materials, ceramics, metals and the like are used as filter materials, filter material made of high polymer materials are limited in use because of poor heat resistance and corrosion resistance. Filter material using ceramics are inferior in toughness and flexibility and easily crack. Moreover, such filter materials have the disadvantage in that the part of the filter material connected with the housing must be sealed using a non-heat resistant material, such as a high elasticity rubber, because it cannot be welded even when contained in a housing for use in filtration of a gas.
In addition, in a filter for precision filtration, whether for gas or for liquid, generation of impurities from the filter itself must be minimized. Such impurities considerably deteriorate the filtering precision by becoming entrained in the filtered liquid or gas. In addition to water, hydrocarbon and the like, which are generated from a high polymer filter itself when using a filter or packings of a high polymer material, are such impurities. Binders, such as organic binders that are mixed to preserve the shape of the filter when the filter is formed specifically by using powders and particles, are also sources of impurities.
Although such binders are mostly evaporated and removed by sintering and calcination of preliminary molding, binder present in a deeper part of the filter tend to be incompletely removed and remain therein. Thus, the binders may exist as carbides formed by sintering and calcination. Therefore, it is an essential requirement that such impurities are not included in a filter used for precision filtration, particularly a filter used for filtering process gas.
The so-called wet suction molding for forming a particle layer on an entire surface of a support member, by immersing a porous support member in a suspension with fine particles mixed therein and reducing the inner pressure is suggested, for example, in Japanese Patent Publication No. 56-8643 (hereinafter called "the former"), and Japanese Patent Publication No. 63-66566 (hereinafter called "the latter").
The former discloses a method of forming a particle layer on a support layer by preparing a suspension of powders without using a binder. The former also discloses a method of using powders as is without preparing a suspension.
It is required in the former, however, that a tubular body be used as a support member, wherein the support member is rotated for adhesion by centrifugal force. Moreover, when using a suspension, pressurization is required from inside by using an elastic rubber and static compression die to increase the adhesion strength of a powder layer (see line 33, column 5 to line 39, column 6 of the Patent Publication).
However, with such a method, it is difficult to obtain a high efficiency filter, since only a tubular shaped material having a filtering layer in the
REFERENCES:
patent: 2598818 (1952-06-01), Muirhead
patent: 3022187 (1962-02-01), Eyraud et al.
patent: 3127668 (1964-04-01), Troy et al.
patent: 4186100 (1980-01-01), Mott
patent: 4377409 (1983-03-01), Ishibe
patent: 4935139 (1990-06-01), Davidsoh et al.
"Pulvermetallurgische Bauelemente in der Verfahrenstechnik" by A. Fischer et al, Chemie. Ingenieur. Technik, vol. 62, No. 4, Apr. 1990, pp. 263-270.
Nippon Seisen Co., Ltd.
Spear Frank
LandOfFree
Laminated filter material, its fabricating method and filter usi does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Laminated filter material, its fabricating method and filter usi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Laminated filter material, its fabricating method and filter usi will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1354357