JPH029871Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a filter element of a filter used for filtering chemicals such as strong acids and strong alkalis to almost eliminate fine particles contained in the chemicals. This relates to an element in which all elements are made of tetrafluoroethylene resin.

In a filter, it is necessary to install a filtration membrane with as wide a membrane area as possible between the stock liquid chamber and the permeate chamber, but in this case, the shape of the membrane becomes complicated, so it is impossible to use a single continuous membrane. .

For this purpose, it is known to stack filter elements covered with membranes on flat spacers for permeate passages, and to connect the permeate passages of these elements using packing, but the sealing properties of the packings have been a problem. There is.

Furthermore, when filtering chemicals such as strong acids and strong alkalines, it is important to use a material that will not be affected by the chemicals.

From this point of view, tetrafluoroethylene resin (hereinafter referred to as a material that can withstand the filtration of strong acids and strong alkaline chemicals and that does not elute from the material)
(abbreviated as PTFE) is considered.

However, even if a permeable membrane made of PTFE can be used, the filter body (housing)
It is difficult to mold PTFE due to its physical properties.

For this reason, up until now, the permeable membrane has been made of PTFE and the filter body has mostly been made of polyolefin resin.

Therefore, even if such a filter element has good workability, when a strong acid or strong alkali (eg, hydrofluoric acid) is filtered, the filter body becomes colored red and ruptures within a few hours.

In addition to hydrofluoric acid, such chemicals include concentrated sulfuric acid,
These include inorganic chemicals such as hydrochloric acid, nitric acid, and hydrogen peroxide, and organic solvents such as acetone, trichloroethylene, and methanol, which are all dangerous to the human body and should not be used if there is a risk of an accident as mentioned above. It's impossible.

There are also filters that use stainless steel for the body, but although this material does not pose any risk of bursting, it is undesirable because it may elute from the material.

However, filtration of such strong acid or strong alkaline chemicals is necessary because, for example, in the semiconductor industry, cleaning parts of semiconductor tips require more precise purity.

Therefore, the present inventor investigated the possibility of constructing the entire filter element using PTFE, which has high chemical resistance, and came up with this idea.

That is, this invention aims to achieve the objective by avoiding restrictions in processing the filter element so that the entire filter element is preferably made of PTFE.

A specific example of this invention will be explained below based on the drawings.

FIG. 1 is an external view of a filter element F of this invention, which has permeable membranes 1 welded on both sides at their peripheries.

This filter element F is formed by fitting spacers A and B, as shown in the enlarged cross-sectional view of one side taken along the line a-a in FIG. 1, in FIG. , ethylene-
It is preferably composed of a fluororesin such as a tetrafluoroethylene copolymer or PTFE, especially PTFE.

The structure of the spacer A is as shown in FIG. 3 as its front surface and in FIG. 4 as its back surface.

That is, in the center of the spacer A, there is a permeate discharge hole 2.
It has a plurality of fitting holes 4 near the outer peripheral surface.

Reference numeral 3 designates a sleeve for aligning the filter elements with the central axis when stacking them or installing them in equipment.

Further, the ring-shaped surface 5 and the circular frame 6 are welding parts for welding the thin permeable membrane 1 to both the front and back surfaces of the spacer.

A large number of circular narrow grooves 7 are provided concentrically on the surface of the spacer A.

Further, on the back surface of the spacer A, there are many radial grooves 8 as shown in FIG. It opens into an opening 9 to.

Note that 10 in the figure is a reinforcing rib on the surface of the spacer.

On the other hand, the structure of spacer B that fits into spacer A is shown in FIGS. 6 and 7, but the general structure is the same as that of spacer A shown in FIGS. 3 and 4. For this purpose, a protrusion 11 that fits into the fitting hole 4 of the spacer A is provided near the outer periphery corresponding to the position of the fitting hole 4.

Note that FIG. 5 is a sectional view of spacer A, and FIG. 8 is a sectional view of spacer B.

Thus, with this invention, spacers A and B made of PTFE are tightly connected and integrated at their respective fitting holes and protrusions, and a thin PTFE permeable membrane is thermally welded to both surfaces with a circular frame. It is now possible to obtain a filter element made entirely of PTFE, which was considered difficult to perform precision micro-molding due to poor melt flowability.A filter element with such a structure can be loaded into a filter to filter liquid. If this is done, the liquid will permeate the membrane due to the pressure difference, reach the internal spacer, pass through the narrow grooves and radial grooves that serve as flow paths, and be discharged from the central permeate drain hole.

Therefore, filtration is possible by blocking the gap between the central permeate discharge hole and the membrane surface, and a filter can be created by stacking multiple spacers, and the filtration area can also be increased. It can be increased or decreased freely.

In addition, the tight integration of spacers A and B means that all the binding sites are on the secondary side of the membrane, and there is no part that contacts the primary side of the membrane, so the binding mechanism has no relation to liquid leakage. It also has characteristics.

[Brief explanation of the drawing]

FIG. 1 is an overall external view of a filter element according to the present invention, FIG. 2 is an enlarged cross-sectional view of one side taken along line a-a in FIG. 1, and FIG. 3 is a surface perspective view of spacer A.
FIG. 4 is a partially cutaway rear perspective view of spacer A, FIG. 5 is a partially cutaway sectional view in direction b of FIG. 3, FIG. 6 is a front perspective view of spacer B, and FIG. Partially cutaway rear perspective view, Figure 8 is the 7th
It is a partially cutaway sectional view in the c direction of the figure. DESCRIPTION OF SYMBOLS 1... Permeable membrane, 2... Permeated liquid discharge hole, 4... Fitting hole, 6... Circular frame, 7... Thin groove, 8... Radial groove, 11... Projection, A, B... Spacer.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of ring-shaped flat plate spacers having a large number of concentric thin grooves on the front surface, radial grooves on the back side, and a gap at the intersection of the narrow grooves and the radial grooves. In a filter element made of stacked layers, fitting holes are provided at multiple locations on the outer periphery of one spacer, and protruding portions are provided at multiple locations on the outer periphery of the other spacer, and the protruding portions are fitted into the fitting holes to be integrated. A filter element made by welding a permeable membrane to both sides. (2) The filter element according to claim 1, wherein the spacer is made of fluororesin. (3) The filter element according to claim 1, wherein the permeable membrane is made of tetrafluoroethylene resin.