JPH0317937Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention allows a liquid sample, such as a plasma sample, to pass through a microporous filtration membrane (so-called ultrafiltration membrane) to separate proteins and produce protein-free plasma. This relates to a liquid filter used for obtaining liquids.

[Conventional technology]

In this type of liquid filter, the pore size of the filtration membrane is extremely small, and the liquid cannot be filtered under atmospheric pressure. Therefore, three main methods have been adopted in the past. The first is to integrally form an upper housing with an open top surface and a lower housing having a drain pipe through an ultrafiltration membrane, and provide a Lua taper in the drain pipe inner hole of the lower housing. A syringe tip nozzle is inserted into the syringe, and by suctioning the syringe, a negative pressure is created in the space below the ultrafiltration membrane, and the liquid sample injected into the upper housing is filtered by the suction force; The second is one that applies a centrifugal separation method, and the third is an upper casing that has a liquid injection pipe equipped with a check valve, as described in Japanese Utility Model Application Publication No. 1983-6712, which was filed by the applicant earlier. and a lower housing having a drainage pipe are integrally formed via an ultrafiltration membrane, a Luer taper is provided in the inner hole of the liquid injection pipe of the upper housing, and the tip nozzle of the syringe is inserted into this. There are three types in which a liquid sample is injected with air using a syringe to create a positive pressure in the space above the ultrafiltration membrane, and the liquid sample is filtered by that pressure.

Although there is no particular difference in the filtration effect between these methods, in the first case, the plunger of the syringe must be held in a suction state during filtration, and a special jig is required for this purpose. Summer,
Once the sample passes through the filtration membrane, it is collected in a syringe, and it is necessary to transfer the collected sample to a test tube, etc., which not only requires extra man-hours, but also wastes the sample that adheres to the syringe. There was a problem. In addition, in the second case, since it is necessary to install a centrifuge, there is a problem that it is not possible to easily filter the product, and it takes time and effort.

On the other hand, in the third case, the liquid sample and positive pressure air injected into the upper housing are retained within the upper housing by the action of the check valve, so the positive pressure remains even after the syringe is removed. It has the advantage that it can be maintained, there is no need to use special jigs, and the filtered liquid can be directly collected into test tubes etc. for sample testing.

However, in the case of liquid filters that adopt the third method above, the upper and lower casings are integrally formed by ultrasonic welding through an ultrafiltration membrane. There was a risk that the supporting part of the membrane would be torn due to the vibrations caused by the sound waves, and that the pore size of the membrane would be distorted due to the welding temperature (the pore size would increase, causing protein to leak).

[Purpose of invention]

This idea was designed to solve the above problems all at once, and by simply screwing together the upper and lower housings without using any welding means such as ultrasonic waves, the screwed parts can be completely airtight. It is an object of the present invention to provide a liquid filter capable of obtaining the same properties.

[Structure of the idea]

This idea screws together the bottom opening of the upper casing, which has a liquid injection pipe with a check valve on the top wall, and the top opening of the lower casing, which has a drainage pipe on the bottom. An annular shelf section on which the peripheral edge of the plate-like filtration membrane can be placed is provided around the bottom surface, and can be interposed between the annular shelf section and an annular step section provided on the inner surface of the top wall or inner circumferential wall of the upper casing that opposes the annular shelf section. A cylindrical member is provided, and the tightening force when the upper housing and the lower housing are screwed together can make the screwed part airtight and press the periphery of the plate-shaped filtration membrane to the annular shelf part. It is.

〔Example〕

Next, this invention will be explained based on an embodiment shown in the accompanying drawings.

1 is an upper casing with an open bottom;
is a transparent material (e.g. plastic, glass)
The top wall 1a is formed into a hemispherical shape, and the bottom portion 1b is formed into a cylindrical shape. The shape of the top wall of the upper housing 1 may be arbitrarily determined.

Reference numeral 2 denotes a liquid injection pipe that extends through the top wall 1a of the upper housing 1, and the inner hole 3 at the outer end of the liquid injection pipe 2 has a luer taper shape into which the tip nozzle 5 of the syringe 4 can fit. , a check valve 6 is provided at its inner end. The check valve 6 is shown in FIG. 1 as having a bottomed tubular rubber member 6a with a slit 6b on one side, and in FIG. 4 as shown in FIG.
Although a slit 6b' is shown at the tip of a', other structures may be employed at the same or different locations.

Reference numeral 7 denotes a female threaded portion carved into the inner circumferential wall of the bottom opening of the upper housing 1, and the female threaded portion 7 may be either a single-thread thread or a multi-thread thread.

8 is an upper casing with an open top surface;
is made of the same material as the upper casing 1 (or may be a different material), and has a mortar-shaped inner bottom to form a liquid collecting surface 9, and a liquid draining pipe 10 is connected to the liquid collecting surface 9. This lower housing 8 has a male threaded portion 11 cut into its outer peripheral wall, so that it can be screwed into the female threaded portion 7 of the upper housing 1. Further, an annular shelf 12 is provided around the inner bottom surface of the lower housing 8, and a plate-shaped filtration membrane (so-called ultrafiltration membrane) 1 having many fine pores is provided.
3 can be placed thereon, and the liquid collecting surface 9 has a large number of ribs 9a for supporting the central part of the plate-like filtration membrane 13 in a manner that does not obstruct the flow of the filtrate. It is provided.

Reference numeral 14 denotes a cylindrical member interposed between the annular shelf portion 12 and an annular step portion 15 provided on the inner circumferential wall of the upper housing 1 so as to oppose the annular shelf portion 12; By screwing the housing 8 together, its upper and lower edges are pressed between the annular shelf section 12 and the annular step section 15 . This serves to press the periphery of the plate-like filtration membrane 13 onto the annular shelf portion 12 and to maintain airtightness of the threaded portion between the upper housing 1 and the lower housing 8. Therefore, it is desirable that the cylindrical member 14 is made of a material such as plastic that has elasticity itself, and if the upper end edge is made triangular in cross section as shown in the figure, the annular stepped portion 15 of the upper housing 1 can be formed. When it is pressed into contact with the material, it is crushed and conforms to the material to further improve airtightness.

Further, the cylindrical member 14 is configured to be able to rotate together with the lower housing 8 when the upper housing 1 and the lower housing 8 are screwed together, thereby preventing the plate-shaped filtration membrane 13 from being twisted. As this means, in the illustrated case, a protrusion 16 is provided on the outer periphery of the cylindrical member 14, and a groove 17 into which the protrusion 16 fits is formed on the upper edge of the lower housing 8. Therefore, the plate-like filtration membrane 13 is placed on the annular shelf 12 of the inner circumferential wall of the lower casing 8, and the cylindrical member 14 is placed on the periphery of the plate-like filtration membrane 13, with its protrusion 16 touching the lower casing 8. If the lower housing 8 is screwed onto the hem of the upper housing 1, the cylindrical member 1
As the screwing progresses, the upper end edge of the cylindrical member 14 comes to come into sliding contact with the annular step 15 of the upper housing 1, and when tightened even more strongly, the upper end edge of the cylindrical member 14 deforms due to the elasticity of the material and contacts the annular step 15. 15, the inside and outside of the cylindrical member 14 are kept airtight, and the plate-shaped filtration membrane 13 is crimped onto the annular shelf 12.

It goes without saying that the upper end edge of the cylindrical member 14 may directly contact the inner surface of the top wall of the upper housing 1 without contacting the annular step portion 15.

Next, a case will be described in which a liquid sample such as a plasma sample is ultrafiltered using the filter of the above embodiment.

First, the plunger 4a of the syringe 4 is pulled in the air to draw a certain amount of air into the syringe barrel, and then an appropriate amount of plasma sample is collected. After that, the tip nozzle 5 of the syringe 4 is tightly connected to the Luer taper part of the inner hole 3 at the outer end of the liquid injection pipe 2 of the upper housing 1, and the plunger 4a is fully pushed in, so that the sample in the syringe 4 is released together with air. , the space created by the upper housing 1, the cylindrical member 14, and the plate-like filtration membrane 13 (hereinafter referred to as
(simply referred to as the upper space), in addition to its internal air, and once the air is injected, it will not flow back due to the action of the check valve 6 provided in the injection pipe, and will be completely captured. The upper space has a positive pressure due to the lower housing 8 and the plate-shaped filter membrane 13. Therefore, the sample is pressed by the pressure in the upper space, passes through the plate-shaped filtration membrane 13, which is an ultrafiltration membrane, over time (within approximately 30 to 60 minutes), oozes into the lower space, and is collected. The liquid flows along the liquid surface 9 and is received into a certain container (not shown) through the drain pipe 10, and is subjected to a certain test. In this case, the upper casing 1 and the lower casing 8 are firmly screwed together, and the threaded portion is completely airtightly maintained by the cylindrical member 14, and the degree of compression of the plate-shaped filtration membrane 13 is also increased. The air in the upper space effectively functions as a force to press the sample. Note that as the sample is filtered, the air pressure in the upper space decreases for a while, but in such a case, by reinjecting only air with the syringe 4, the upper space can be easily restored to a positive pressure state again. is possible.

[Effect of idea]

As described above, the liquid filter according to this invention has a bottom opening of the upper casing having a liquid injection pipe with a check valve on the top wall, and an upper opening of the lower casing having a drain pipe on the bottom. An annular shelf is screwed together and the peripheral edge of the plate-like filtration membrane can be placed around the inner bottom surface of the lower casing, and an annular shelf is provided on the inner surface of the top wall or the inner peripheral wall of the lower casing opposite to the annular shelf. A cylindrical member that can be inserted between the annular step part is provided, and the tightening force when the upper and lower casings are screwed together makes the threaded part airtight and the periphery of the plate-shaped filtration membrane to the annular shelf part. Since it is constructed so that it can be crimped, it has a higher degree of completeness than conventional products in which the upper and lower casings are manufactured by welding using ultrasonic waves or the like. This has the excellent effect of being able to perform rapid and reliable liquid filtration.

[Brief explanation of the drawing]

The figures show one embodiment of this invention, in which Figure 1 is a cross-sectional view when a sample is press-fitted, Figure 2 is an exploded perspective view of the lower housing, and Figure 3A is where the cylindrical member slides on the inner surface of the upper housing. A partial cross-sectional view showing the state before contact, Figure B is a partial cross-sectional view showing the state in which the upper edge of the cylinder member is pressed against the inner surface of the upper housing, and Figure 4 shows another example of the check valve. FIG. DESCRIPTION OF SYMBOLS 1... Upper housing, 1a... Top wall, 1b... Hem, 2... Liquid injection pipe, 6... Check valve, 8... Lower housing, 10... Drain pipe, 12... Annular shelf, 13...
... Plate-shaped filtration membrane, 14 ... Cylindrical member, 15 ... Annular step part.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) The bottom opening of the upper casing, which has a liquid injection pipe with a check valve on the top wall, and the top opening of the lower casing, which has a drain pipe on the bottom, are screwed together. An annular shelf part on which the peripheral edge of the plate-like filtration membrane can be placed is provided around the inner bottom surface of the lower housing, and an annular shelf part and an annular shelf part provided on the inner surface of the top wall or the inner circumferential wall of the upper housing opposite thereto are provided. A liquid filter characterized in that a cylindrical member that can be inserted between the stepped portion and the stepped portion is provided. (2) The liquid filter according to claim 1, wherein the cylindrical member is locked so that it can rotate integrally with the lower casing when the upper casing and the lower casing are screwed together. (3) The liquid filter according to claim 1 or 2, wherein the upper edge of the cylindrical member has a triangular cross section.