JPH0244845Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in membrane filters, and more particularly to improvements in cup-type membrane filters.

For example, membrane filters, well known under trade names such as MILLIPORE filters (registered trademark), are used today for various precision filtration, isolation of substances, fractionation of mixed components, and filtering of sterile water. Widely used for manufacturing purposes. This kind of filter includes, for example, the one disclosed in Japanese Utility Model Application Publication No. 58-6712 and various other types, but the cup-type filter, which is the subject of the present invention, is relatively inexpensive. Since it is suitable for handling small amounts of specimens and does not require special pressurization or depressurization equipment, it is being used for medical tests and other purposes such as deproteinization of serum.

By the way, this filter (see Figures 1 and 2 below, reference numeral 1) that is commonly used today is as follows:
A frusto-conical, hollow cup 2 made of thermoplastic synthetic resin and having a flange portion 3 on the periphery, and a disc-like support also made of thermoplastic resin and having a flange portion 5 on the periphery. A filter membrane 6 lined with a thin porous support material is sandwiched between the two members (member) 4, and the opposing flange portions of both members are welded. When using,
The sample liquid is injected into the cup 2 through the opening 7 at the top of the cup 2, and the sample liquid is injected into the cup 2 by pulling down the plunger P of the syringe S whose tip is inserted into the hole 8 bored in the center of the support 4. A groove 9 carved on the inner surface of the central part of the support 4 and a small hole 10 at the center of the support 4
, and is sucked into the cylinder C of S through the hole 8.

However, the above-described known filter has a drawback in that the peripheral portion of the filtration membrane 6, which is the main material, is extremely easy to tear. Needless to say, the root cause of this filter membrane damage is that this membrane is extremely thin, but it is also thought that the mechanical and thermal effects when welding the flange portions 3 and 5 cannot be ignored. However, since damage to the filtration membrane itself directly affects the success or failure of filtration, minimizing the damage is of great industrial significance.

In addition to the above, existing cup-type membrane filters have the disadvantage that the bond between the flange portions of the cup and the support is often poor. Although this drawback is not as fatal as the former, the ingress of air through the joints still reduces the filtration efficiency and in extreme cases even makes filtration impossible. Therefore, this is another point that should definitely be improved in order to increase the reliability of this filter. (Just for reference, in the past,
When a filtration membrane is sandwiched between two casings, it is known that a seal ring is interposed between the filtration membrane and the casing for the sole purpose of ensuring airtightness between the two casings, as disclosed in Japanese Patent Application Laid-Open No. This method was commonly practiced as disclosed in Japanese Patent No. 52-43784. ) The present invention solves the manufacturing problem of cup-type membrane filters, which can be manufactured at low cost by ultrasonic welding, namely, the problems caused by damage to the peripheral edge of the filter member during ultrasonic welding. The purpose of the present invention is to avoid over-deficiency, poor air-tightness, and poor air-tightness due to the occurrence of pinholes in the flange portions of the cup and support, and to exhibit stable filtration performance as a whole.

In order to achieve the above object, the present invention forms flange parts around a cup and a support made of thermoplastic resin, a filter member is sandwiched between these flange parts, and each of the flange parts is connected to the filter member. A cup-shaped membrane filter that is ultrasonically welded together with a member, wherein a flange portion of at least one of the cup and the support is provided with an annular step or groove, and the filter member is supported in the step or groove. an annular packing is attached as shown in FIG. This was the measure taken.

This prevents mechanical (including vibration) and thermal effects when welding the flange around the cup and support together with the filter member using ultrasonic waves.
First, it is added to the annular rib, and as the welding of this rib portion progresses, it extends to the entire flange, and therefore, the mechanical (including vibration) and thermal effects at the initial stage of welding are directly affected. As a result, damage to the filter member is reduced, and when welding progresses, the gaskets in the step or groove sandwich the filter member, and the gas is transferred inward from the outer periphery of the filter member. The transmitted mechanical (including vibration) and thermal effects are
The gas absorption is blocked by this gasket, and damage to the filter member can be further avoided. At the same time, the presence of the annular rib enables strong local welding, which prevents pinholes from occurring in the entire flange area where welding is performed, resulting in even more airtightness. It is.

The depth of the above-mentioned step or groove is preferably somewhat shallower than the thickness of the packing to be attached. As the gasket, a conventional O-ring is advantageously used, but other annular gaskets may of course be used. Ideally, steps or grooves should be provided on both flanges on the cup side and the support side, respectively, so that the peripheral edge of the filter membrane is supported by packing from both sides. According to the above, the problem of breakage can be virtually solved by simply attaching the seal to either one of the flanges.

As a result of research, the present inventor found that if a rib is provided protruding from one of the opposing flanges,
It has been found that the occurrence of pinholes during welding can be substantially suppressed. Therefore, the installation of this rib is
Together with the above-mentioned attachment of the gasket, this contributes to the prevention of leaks.

The thermoplastic material of the cup and support of the present invention may be similar to that used for conventional filters. However, good compatibility with the filter membrane or its supporting material and transparency are important conditions when selecting this material. Incidentally, styrene resin and acrylic resin, which have been conventionally used as materials for this filter, both satisfy the above two conditions, and therefore can be suitably used for the purpose of the invention.

Which of the above-mentioned steps or grooves is employed in the flange portion is determined primarily by design considerations. Generally, a groove requires a wider width than a step, so if there is no margin in the width of the flange, a step structure is appropriate. Further, in cases where the flange portion and the main body portion are on substantially the same plane as in the case of a support member, it is structurally difficult to provide a step portion, so a groove structure is mainly adopted.

Hereinafter, the contents of the present invention will be explained in more detail with reference to the drawings, but the examples are strictly for explanation and do not mean a limitation on the spirit of the invention.
3 to 5 show an embodiment of the present invention described above. In this example, the cup member 2 made of styrene resin has a concentric rib 11 on the back surface 3a of the flange portion 3, and a concentric step 12 on the inside thereof (see FIGS. 3 and 4). (see figure), the O-ring 13 is placed on the stepped portion 12.
is embedded. The flange portion 3 of this cup member 2 is made to face the flange portion 5 of the support member 4 shown in FIGS. After sealing with sound waves, the cup-shaped membrane filter shown in Figure 5 is completed.

In the filter of the present invention obtained as described above, the bonded portions are completely bonded due to the presence of the ribs 11, and there are no pinholes in these portions. Moreover, since mechanical vibrations and thermal shocks generated during adhesion are absorbed or blocked by the O-ring 13, the filter membrane 6 sandwiched between both flanges is completely spared from damage. Therefore, the filter of this example exhibits stable filtration performance without fear of damage to the periphery of the filtration membrane due to suction or of air entering through the joints.

FIG. 6 shows an example in which a groove 14 corresponding to the stepped portion 12 provided on the cup member 2 in the previous example is also formed in the support member 4, and an O-ring 13 is also installed in this groove. In the embodiment of this example, the filter membrane 6 is completely supported between the O-rings 13, 13.
The protection and air-tightness effect of the membrane is more perfect.

Above, we have explained two suitable examples of the invention.
It should be understood that the embodiments of the invention are of course not limited to the above, and that various other modifications may be made. For example, ribs on the flanges do not prevent them from being placed on opposite flanges, if desired.

As explained above, the present invention is a simple and practical solution to the problems associated with cup-type membrane filters, which can be manufactured at low cost by ultrasonic welding, and can be manufactured at low cost. However, it avoids poor filtration and airtightness caused by damage to the peripheral edge of the filter member during ultrasonic welding, as well as poor airtightness caused by pinholes in the flanges of the cup and support, resulting in stable filtration performance as a whole. This has led to the remarkable effect that it can achieve, and it will make an important contribution in the field of precision filtration.

[Brief explanation of the drawing]

1 is a sectional view taken along line A-A in FIG. 2 showing the structure of a conventional cup-type membrane filter; FIG. 2 is a plan view of the support member portion of the filter in FIG. 1; The figure is a sectional view of the cup member of the cup-type membrane filter according to the present invention, FIG. 4 is a plan view of the member in FIG. 3 seen from the back side, and FIG. A sectional view similar to that shown in FIG. 1 of a cup-shaped membrane filter made using the support members shown in FIGS. 1 and 2, and a similar sectional view shown in FIG. 3 is a sectional view similar to FIGS. 1 and 3 of the cup member and support member of the filter; FIG. The meanings of the main symbols in each figure are as follows: - 1: Cup-type membrane filter, 2: 1
cup member, 3:2 flange part, 4:1 support member, 5:4 flange part, 6: filter membrane,
7: opening, 8: 4 opening (syringe mounting hole),
9:4 groove (liquid passage groove), 10:4 small hole (liquid passage hole), 11:3 upper rib, 12:3 upper step, 1
3: O-ring, 14: groove on 5, C: cylinder of syringe S, P: plunger of S, S: syringe.

Claims (1)

[Scope of utility model registration request] A cup-shaped membrane in which flange parts are formed around a cup and a support made of thermoplastic resin, a filter member is sandwiched between the flange parts, and each of the flange parts is welded together with the filter member by ultrasonic waves.・The filter is provided with an annular step or groove on the flange portion of at least one of the cup and the support, and an annular packing is attached to the step or groove so as to support the filter member, and A cup-shaped membrane filter, characterized in that an annular rib is provided on opposing surfaces of the flange portions of at least one of the cup and the support before welding, positioned outside the step portion or the groove portion.