JP2004237142A - Tip filter and tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tip filter to which foreign matters such as burrs, dust, refuse and whiskers are prevented from being stuck at its manufacturing step, which is aligned correctly so that such a trouble is not aroused that its manufacturing apparatus is stopped, on which dust in the air is not adsorbed in use so that a bad influence is not exerted on measurement precision and which has an excellent effect that the precision of the amount of the liquid to be dispensed is prevented from being deteriorated by sucking the liquid slightly excessively or overflowing the liquid when a very small amount of the liquid is dispensed and to provide a tip having the tip filter. <P>SOLUTION: The porous resin-made tip filter is subjected to an antistatic treatment on its surface. It is preferable that the porous resin-made tip filter is further subjected to a water-repellent treatment. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tip filter applied to a tip to be used as a suction nozzle of a liquid suction device, for example, a pipette suction nozzle or to be attached to the tip of the nozzle, and a tip to which the tip filter is applied.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when dispensing and testing reagent solutions, body fluids (blood, etc.), urine, etc., a tip is attached to a tip portion of a suction nozzle of a liquid suction device or the like, and a predetermined amount of the sample solution is suctioned there. And dispensed from the reservoir into another container. This dispensing operation is performed by both manual and automatic methods. In particular, rapid and reliable dispensing operations have been demanded today as inspection medicine becomes automated and unmanned.
[0003]
In the dispensing operation, the tip of the suction nozzle is prevented from being contaminated by different reagents and reagents, and the suction device itself is contaminated by the passage of suction droplets (steam), or the suction device contaminated with the liquid is not affected. The tip is provided with a filter for the purpose of preventing splash (steam) from entering back.
[0004]
As the filter, a filter of a polypropylene fiber bundle or a polyethylene terephthalate fiber bundle or a urethane foam filter is generally used. Further, as an improvement of these filters, a porous sintered resin filter and a composite filter in which a porous resin sintered body and a nonwoven fabric are laminated are known (Patent Document 1).
[0005]
When a cylindrical filter is mounted on a chip, an apparatus is often used in which a filter is inserted from a hopper through a parts feeder so that the filter is aligned and easily inserted into the chip. In this case, the chips are aligned by the vibration, and if necessary, the operation of deciding the direction of the filter by auxiliary air injection and the operation of feeding the chips and mounting them are performed.
[0006]
[Patent Document 1]
JP 2001-121005 A [Problems to be Solved by the Invention]
However, when the porous sintered resin filter disclosed in Patent Document 1 or the like is placed in a parts feeder, when vibration is applied to align the filters, or when the filters are auxiliaryly aligned by jetting air, the filters are not combined with each other. Due to the dynamic contact of the filter and the dynamic contact between the filter and the component feeder components, the filter is charged by static electricity, causing a problem that the filter or chip itself sticks out, electrostatically attracts whiskers, foreign matter, and the like. In addition, due to the charging, the filters cannot be aligned, and the filters are mounted in a different direction from the normal product, or the filters are not properly mounted.
[0007]
Not only the environment of the filter mounting process at the time of the chip manufacturing described above, but also particularly the use environment is not always in a clean room. For example, in extreme cases, it could be used in developing countries in arid regions. Under such use conditions, the filter described in Patent Document 1 easily adsorbs dust and dust in the air due to static electricity, and biological dust that is a source of RNA and DNA is usually contained in the dust. Due to their presence, it was difficult to avoid the problem of affecting the measurement.
[0008]
In particular, in the case of a filter made of a material having a low polarity, such as UHMWPE and HDPE, which is a filter material described in Patent Document 1, and which is easily charged with static electricity, once charged, the charging half-life is too long to be measured, and the filter is mounted on a chip. May remain charged. If such charge remains, dust adsorption during use may affect measurement accuracy.
[0009]
An object of the present invention is to prevent the attachment of foreign substances such as burrs, dust, debris, and whiskers in a filter and chip manufacturing process and to cause a stop of a manufacturing apparatus due to misalignment of a filter, and dust in the air during use. It is an object of the present invention to provide a chip filter and a chip which do not affect the measurement accuracy due to the adsorption of the particles.
[0010]
Another object of the present invention is to provide a tip filter and a tip having an excellent effect of preventing a decrease in accuracy of an injection amount due to slight over-suction overflow or the like when a small amount of liquid is dispensed.
[0011]
[Means for Solving the Problems]
That is, the filter for chips of the present invention is a filter made of a porous resin whose surface is subjected to an antistatic treatment.
[0012]
The antistatic treatment has the effect of preventing burrs, dust, debris, whiskers and other foreign substances from adhering to the filter in the manufacturing process of filters and chips due to static electricity, and causing trouble in the production equipment due to misalignment of the filter. It has become possible to obtain a chip filter that does not affect the measurement accuracy due to the adsorption of dust in the air during use.
[0013]
In the above-mentioned filter for chips, it is preferable that the surface is further subjected to a water-repellent treatment.
[0014]
The antistatic treatment in the above-described invention is usually a hydrophilic treatment using surface activity or the like, and thus, only the charging treatment imparts hydrophilicity to the entire filter. As a result, there is a case where the water pressure resistance of the filter is reduced and the effect of preventing the overflow of the dispensed liquid is reduced. The filter having both water repellency and antistatic properties was obtained by further performing a water repellent treatment on the filter subjected to the antistatic treatment.
[0015]
Such a filter can prevent the overflow of the dispensed liquid of the filter by increasing the water resistance due to the water repellent effect. Further, since the filter does not have wettability, the liquid is less likely to be contaminated even when the pipette is pushed and discharged to recover the liquid, even if the filter overflows. Further, the effect of preventing adhesion of dust including biological residue which is a source of dust and RNA and DNA was also obtained by the water repellent effect.
[0016]
A chip according to the present invention is provided with the chip filter according to the first or second aspect.
[0017]
Such a chip has few troubles in the manufacturing process, such as prevention of foreign matter such as burrs, dirt, debris, and whiskers, and stoppage of the manufacturing apparatus due to misalignment of a filter, and measurement by adsorption of dust in the air during use. It does not affect accuracy.
[0018]
Furthermore, the chip is excellent in preventing the accuracy of the injection amount from lowering due to a slight over-suction overflow or the like when dispensing a small amount of liquid.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
The filter of the present invention comprises a porous resin having a compression elastic modulus of 100 to 1000 kg / cm ² , preferably 200 to 400 kg / cm ² , and the porous resin has an average pore size of 10 to 100 μm, preferably 20 to 40 μm. Is preferred. The air permeability (Fragile method) is preferably 0.5 to ²⁰ cm ³ / cm ² · s, more preferably 1 to 5 cm ³ / cm ² · s.
[0020]
The resin constituting the filter is not particularly limited, but is excellent in solvent resistance, acid resistance, alkali resistance, hygiene, dust-free, radiation resistance, autoclave resistance, rigidity, air permeability, etc. In, polyolefin, it is preferable to be a sintered porous body of resin particles selected from fluorine-based resin, as the polyolefin, ultra-high molecular weight PE, ultra-high molecular weight polyolefin such as ultra-high molecular weight PP is preferably used As the fluororesin, use of polytetrafluoroethylene (PTFE), polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene / hexafluoropropylene copolymer (FEP) and the like are available. preferable. These resins may be used in combination of two or more as necessary. For example, ultrahigh molecular weight polyethylene is a polyethylene having a viscosity average molecular weight of 500,000 to 10,000,000, preferably 1,000,000 to 7,000,000. As ultra high molecular weight polyethylene, commercially available products such as HIZEX Million (Mitsui Chemicals) and Hostalen GUR (Taikona) can be used.
[0021]
In the production of an ultra-high molecular weight porous sintered filter having a compression elastic modulus of 200 to 400 kg / cm ² , an average pore diameter of 20 to 40 μm, and air permeability (Fragile method) of 1 to ⁵ cm ³ / cm ² · s, a known porous resin is used. Can be used without limitation. As a method for producing such an ultra-high molecular weight porous sintered filter, for example, the production method described in Japanese Patent No. 2020026 can be exemplified. In the case of the sintering method, the compression modulus and the average pore size of the obtained porous sheet can be controlled by the average particle size of the powder. In the present invention, powder having an average particle diameter of preferably 25 to 170 μm, more preferably 100 to 170 μm is used.
[0022]
As the antistatic agent for treating the porous resin filter, known antistatic agents can be used without limitation, and examples thereof include a cationic antistatic agent, an anionic antistatic agent and a nonionic antistatic agent. These antistatic agents may be either aqueous or solvent-based. Commercially available antistatic agents can be used. For example, Electonone OR-W (New Fine Chemical) as a cationic antistatic agent, Electrostripper F (Kao) as an anionic antistatic agent, and nonionic antistatic agent Is Emulgen 109P (Kao).
[0023]
In the present invention, as the water repellent for treating the porous resin, known water repellents can be used without limitation, and examples thereof include a fluorine-based water repellent and a silicon-based water repellent. As the water repellent, commercially available products can be used. For example, TG-500 (Daikin Industries) is exemplified as a fluorine-based water repellent, and KM740 (Shin-Etsu Chemical) is exemplified as a silicon-based water repellent. .
[0024]
The shape of the porous resin filter in the present invention may be any shape as long as it can be mounted without any gap inside the chip having a circular cross section, and may be formed simultaneously with sintering using a mold, and may be formed into a sheet or block. After sintering, a cutting process, a punching process, a cutting process, or the like may be performed to form the sheet. Examples of the shape include a sphere, a truncated cone, and a column. The shape of the filter is preferably a column having a thickness of 0.5 to 5 mm. The thickness of the cylinder is generally between 0.5 and 5 mm, especially between 2 and 5 mm, but can be greater than 5 mm. A filter formed by punching a porous resin sheet manufactured by a sintering method has compression elasticity that allows it to be pressed into the inside of the chip tube without any gaps, and has the advantage of being dust-free and free of dust. are doing.
[0025]
In a preferred embodiment, the filter has a cross-linking density increased by electron beam irradiation for the purpose of improving heat resistance and the like.
[0026]
The antistatic treatment and the water-repellent treatment are performed utilizing the permeability of the liquid due to the capillary phenomenon. These treatments are performed on the entire surface of the resin constituting the porous resin. When the filter is formed from a porous resin sheet by punching or the like, the filter may be formed in a sheet state or may be formed after processing into a predetermined filter shape.
[0027]
FIG. 1 shows an example of a chip equipped with the filter of the present invention. The tip 3 is composed of a straight pipe portion attached to the mouth tube portion 2 of the nozzle of the suction device and a tapered portion that becomes thinner toward the opening. It is attached to the diameter part. The tip 3 generally has a tapered shape (a spoid shape) or a shape including a tapered portion and a straight pipe portion. The chip 3 can be manufactured by injection molding of a resin excellent in solvent resistance, acid resistance, alkali resistance, hygiene, dust-free, radiation resistance, autoclave resistance, mechanical strength, and the like, for example, polycarbonate. Further, as a general-purpose chip, a polyolefin resin such as polypropylene can be used.
[0028]
In order to dispense a test solution or a reagent using a chip provided with the chip filter 6 of the present invention, as shown in FIG. 1, the chip body 3 is attached to the mouth tube 2 of the nozzle of the suction device. The sample solution 5 and the like are sucked into the chip by the operation of the piston 1 of the suction device. In this case, the filter 6 has an effect of preventing the aerosol 4 which is a droplet of the test solution 5 from passing therethrough, and also has an effect of preventing the sample solution 5 from overflowing during excessive suction.
[0029]
As shown in FIG. 1, the shape of the filter for the chip is a shape corresponding to the shape of the inner peripheral surface of the chip body 3, but is generally cylindrical as described above. The filter 6 is slightly deformed by being attached (fitted) to the chip main body 3, and is fixed to the inner peripheral surface of the chip main body 3 by the elastic restoring force at that time.
[0030]
【Example】
Hereinafter, examples that specifically show the configuration and effects of the present invention will be described.
(Example 1)
Using ultra-high molecular weight polyethylene having a viscosity average molecular weight of about 4 million, a thickness of 3.5 mm formed by a sintering method, a compression modulus of 250 kg / cm ² , and a gas permeability (Fragile method) A porous sheet having 5 cm ³ / cm ² · s, a porosity of 30%, and an average pore diameter of 35 μm is impregnated with a pure aqueous solution of a cationic antistatic agent Elecnon OR-W (New Fine Chemical) having a solid content of 0.5% and dried. After having done it, 4. It was punched out into a 7 mmφ cylindrical shape to obtain a filter a. Using 5000 of the filters a, a mounting experiment was continuously performed on a PP chip having the shape shown in FIG.
[0031]
(Example 2)
The porous sheet made of ultrahigh molecular weight polyethylene used in Example 1 was impregnated with a pure aqueous solution of a cationic antistatic agent Elecnon OR-W (New Fine Chemical) having a solid concentration of 0.5% and dried. A filter was punched out into a 4.7 mmφ cylindrical shape. This filter was further impregnated with a liquid having a solid concentration of 0.5% of a fluorine-based water repellent TG-500 (Daikin Industries) and dried to obtain a filter b. Using 5000 filters b, a hopper type feeding machine and a vibration type aligning machine were used to carry out a continuous mounting experiment on a PP chip.
[0032]
(Comparative Example 1)
The ultra-high molecular weight polyethylene porous sheet used in Example 1 was neutralized only by an electrostatic blower without performing an antistatic treatment, to obtain a filter c. Using 5000 filters c, a hopper type feeding machine and a vibration type alignment machine were used to carry out a continuous mounting experiment on a PP chip.
[0033]
<Evaluation test>
1) It was visually confirmed whether the filters a to c were mounted on the chip without mistake. (Evaluation of mounting failure due to static electricity)
In addition, it was confirmed whether there was a machine stop due to defective feeding or mounting of the filter.
[0034]
2) The filter chip mounted without mistake was visually checked for dust and foreign matter. (Evaluation of foreign matter adhesion failure due to static electricity)
<Evaluation results>
(Evaluation of mounting failure due to static electricity)
In Examples 1 and 2, the mounting of the built-in device occurred only once when 5,000 filters a and b were mounted, respectively. On the other hand, in the comparative example, the built-in machine was stopped several times, and the evaluation was impossible.
[0035]
Regarding the mounting of the filters, there was no mounting error for the filters a and b of the example, but the filter c of the comparative example could not be evaluated because the machine stopped several times.
[0036]
(Evaluation of foreign matter adhesion failure due to static electricity)
No adhesion of dust and foreign matter was visually observed in the chips of Examples 1 and 2. As for the chip after the filter c of the comparative example was attached, many chips with burrs were found.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a state in which a tip provided with a filter for a tip is attached to a mouth portion of a nozzle of a suction device.

Claims (3)

A chip filter made of porous resin whose surface has been subjected to antistatic treatment. The chip filter according to claim 1, wherein the surface is further subjected to a water-repellent treatment. A chip provided with the chip filter according to claim 1.

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