JPWO2020111206A1 - Stirrer and stirrer - Google Patents

Abstract

The stirring rod 1 according to the present disclosure is made of an integrally molded ceramic product provided with a stirring portion having a cross section orthogonal to the axial center having a constant shape along the axial direction, and a plurality of convex portions 4 are formed in the cross section. It has a stirring unit 2 arranged in the circumferential direction. The plurality of convex portions 4 have a tapered shape whose width narrows toward the tip in the cross section.

Description

The present disclosure relates to a stirring rod for stirring a liquid and a stirring device provided with the stirring rod.

Conventionally, an analyzer that analyzes blood, urine, and other biochemical samples, mainly for medical purposes, is equipped with a stirrer that agitates the sample solution. This stirring device is provided with a stirring rod for stirring the sample solution. The stirring rod is required to have chemical resistance to sample solutions and reagents. Therefore, the stirring rod is formed of, for example, a metal material such as stainless steel whose surface is processed using a fluorine-based resin, or a resin material such as polyethylene or polypropylene. Among them, a stainless steel stirring rod whose surface is coated with a fluorine-based resin such as tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, and FEP (copolymer of tetrafluoroethylene and hexafluoropropylene) is durable and costly. (For example, Patent Documents 1 and 2).

JP-A-2009-145269, FIG. 3 Japanese Unexamined Patent Publication No. 8-136550

The stirring rod of the present disclosure is made of an integrally molded ceramic product having a stirring portion having a cross section orthogonal to the axial center having a constant shape along the axial direction, and in the above cross section, a plurality of convex portions are formed in the circumferential direction. Have been placed.

The stirring device of the present disclosure includes the above-mentioned stirring rod.

(A) and (b) are a front view and an X-ray sectional view thereof showing one embodiment of the stirring rod of the present disclosure, respectively. It is the schematic which shows the manufacturing process of the stirring rod of this disclosure. It is the schematic for demonstrating the warp of the stirring rod of this disclosure. It is the schematic which shows the use state of the stirring rod of this disclosure. (A) and (b) are front views showing other embodiments of the stirring rod of the present disclosure, respectively.

Hereinafter, the stirring rod according to the embodiment of the present disclosure will be described with reference to the drawings. As shown in FIG. 1A, the stirring rod 1 according to the present embodiment has a stirring unit 2 and a stirring unit A having the same axial center A as the stirring unit 2 on one end surface of the stirring unit 2 in the axial direction. It includes a shaft portion 3 integrally formed with 2.

The stirring unit 2 has a shape in which the cross section orthogonal to the axis A has a constant shape over the entire length of the stirring unit 2 along the axial direction. That is, as shown in FIG. 1B, the cross section of the stirring portion 2 has a shape in which a plurality of convex portions 4 are arranged in the circumferential direction. Since the stirring rod 1 according to the present embodiment includes a plurality of convex portions 4, it is possible to generate a flow in the axial direction and stir.

The stirring rod 1 is made of an integrally molded ceramic product having excellent chemical resistance. That is, the stirring portion 2 having a cross-sectional shape in which a plurality of convex portions 4 are arranged in the circumferential direction over the entire length can be obtained by, for example, extrusion molding.

Extrusion molding is performed according to the following procedure. First, water and a binder (binder) are added to and mixed with the raw material (powder), and continuously supplied into the cylinder to be heated and melted. Next, the molten material is extruded through a die at the front of the cylinder by rotation of a screw in the cylinder, cooled and molded. The extruded molded product 11 shown in FIG. 2 has the cross-sectional shape shown in FIG. 1 (b) over the entire length. After firing the molded product 11, one end is ground and polished while rotating the molded product 11 in the grinding / polishing step to form the shaft portion 3. At this time, the shaft portion 3 and the stirring portion 2 share the same shaft center A.

The cross-sectional shape of the shaft portion 3 is not particularly limited, and examples thereof include a circular shape, a quadrangular shape, and an elliptical shape.

Further, in the grinding / polishing step, burrs and scratches on the fired stirring rod 1 are removed and smoothed. At this time, it is preferable that the peripheral surface of the stirring portion 2, particularly the convex portion 4, has a curved surface on the entire surface. As a result, partial stress concentration does not occur in the stirring rod 1, cracks and breakages are reduced, and durability is improved.

The raw material for such ceramics is not particularly limited as long as it has excellent chemical resistance, and examples thereof include high-purity alumina, zirconia, silicon nitride, silicon carbide, and alumina zirconia composite materials.

Returning to FIG. 1B, the plurality of convex portions 4 arranged in the circumferential direction of the stirring portion 2 extend radially from the axial center A, and the convex portions 4 are arranged at equal intervals. There is.

Further, the convex portion 4 has a tapered shape whose width narrows toward the tip end. With such a tapered shape, the resistance (stress) received by the tip of the convex portion 4 is reduced, and the durability is improved.

As described above, the entire surface of the convex portion 4 is formed in a curved surface shape. Therefore, the space between the adjacent convex portions 4 and 4, that is, the valley portion is also curved.

In the present embodiment, the angle between the adjacent convex portions 4 is larger than the angle obtained by dividing 360 ° by the number of convex portions 4. That is, each convex portion 4 is thinner than the base portion at a position away from the axis A. Therefore, there is an effect that reagents and the like are less likely to accumulate in the gaps between the convex portions 4. It also has the effect of being easy to polish during manufacturing.

The angle θ between the adjacent convex portions 4 and 4 may be larger than the angle α by 1/4 α or more, where α is the angle obtained by dividing 360 ° by the number of convex portions 4. As a result, the stress applied to the base portion of the convex portion 4 can be relaxed. Further, by adding R to the corner portion, the stress applied to the base portion of the convex portion 4 can be further relaxed.

Further, in the present embodiment, the angles θ of the adjacent convex portions 4 and 4 may form an obtuse angle of 90 ° or more. Specifically, the angle θ may be in the range of 90 ° ≦ θ ≦ 180 °. When the angle θ is formed at an obtuse angle, there is an effect that reagents and the like are less likely to accumulate due to the gaps between the convex portions 4. It also has the effect of being easier to polish during manufacturing.

Here, the angle θ means the angle formed by the tangents of the portions closest to the valley portion in the adjacent convex portions 4 and 4. In the case of the convex portion 4 having a shape as shown in FIG. 1B, it means the angle between the outer surface side tangent line of one convex portion 4 and the inner surface side tangent line of the other convex portion 4.

As shown in FIG. 3, the stirring rod 1 may have a shape in which the axis A is curved in a bow shape. In FIG. 3, for convenience, the stirring portion 2 is shown in a warped state, but the axial center A of the shaft portion 3 is also warped. The degree of warpage is preferably 0.2 mm or less when x (the distance most separated from the vertical line in the stirring unit 2) shown in FIG. 3 is 0.2 mm or less when the length of the stirring unit 2 is 40 mm. X shown in FIG. 3 can be measured by, for example, a feeler gauge. When the length of the stirring unit 2 is other than 40 mm, a distance x having a relationship proportional to this may be selected.

In this way, the stirring unit 2 has a warp, so that the stirring efficiency is improved. In order to impart warpage to the stirring unit 2, for example, the temperature and firing time of the molded product 11 at the time of firing may be controlled.

As shown in FIG. 4, the stirring rod 1 is inserted into the stirring tank 9 of the stirring device with the stirring unit 2 facing down. The upper part of the shaft portion 3 protrudes from the liquid surface of the sample solution 8. A drive unit (not shown) including a motor for rotating the stirring rod 1 is connected to the shaft portion 3 protruding from the liquid surface to rotate the stirring rod 1.

Since the stirring unit 2 of the stirring rod 1 in the present embodiment is located at least near the bottom of the stirring tank 9, the stirring rod 1 can be efficiently stirred regardless of the viscosity of the sample solution 8. In particular, when the stirring portion 2 is formed long in the axial direction, it is suitable for stirring the highly viscous sample solution 8. The stirring unit 2 may be half or less with respect to the depth of the sample solution 8 (height from the bottom surface of the stirring tank 9 to the liquid surface).

The stirring rod of the present disclosure is not limited to the embodiment shown in FIG. 1, and various modifications can be made. For example, as shown in FIG. 5A, the stirring unit 2 may be located at the lower part, and as shown in FIG. 5B, a plurality of stirring units 2a, 2b, and 2c are arranged along the shaft portion 3. It may be arranged in a row.

The number of the convex portions 4 provided on the shaft portion 3 is not limited to the four shown, and can be appropriately selected in the range of 2 to 5.

Further, in the above embodiment, the shaft portion 3 is integrally molded with the stirring portion 2 by extrusion molding or the like, but the shaft portion 3 is manufactured separately from the stirring portion 2 and is formed in a recess provided on the end face of the stirring portion 2. The shaft portion 3 may be attached and fixed. At this time, the shaft portion 3 may have a circular or elliptical cross section, or may have a rectangular shape to prevent idling.

Further, the ceramic has closed pores, and the value (A) obtained by subtracting the average value of the equivalent circle diameters of the closed pores from the distance between the centers of gravity of the adjacent closed pores may be 20 μm to 85 μm. When the value (A) is 20 μm or more, the void portions are dispersed and arranged without being densely arranged, so that the value (A) has high mechanical properties. When the value (A) is 85 μm or less, it is good when polishing or the like is performed from the outer peripheral surface of the stirring unit 2 in the axial direction, or from the end surface of the stirring unit 2 or the end surface of the shaft portion 3 toward the inside. Excellent workability can be obtained. Further, since the distance between the adjacent closed pores is narrowed, the expansion of microcracks caused by thermal shock can be suppressed.

The distance between the centers of gravity of the closed pores can be obtained by the following method.

First, for example, from the end face of the stirring unit 2 toward the inside, polishing is performed on a copper plate using diamond abrasive grains having _{an average particle diameter D 50 of 3 μm.} Then, a polished surface is obtained by polishing with a tin plate using diamond abrasive grains having an average particle size D _{50 of 0.5 μm.} By these polishings, the arithmetic mean roughness Ra of the polished surface can be set to 0.01 μm to 0.2 μm. The arithmetic mean roughness Ra of the polished surface can be obtained in accordance with JIS B 0601: 1994, and the radius of the stylus is 5 μm, the material of the stylus is diamond, the measurement length is 1.25 mm, and the cutoff value is set. It may be 0.25 mm.

Observe the polished surface at a magnification of 200 times and select an average range. For example, a range with an area of 0.105 mm ² (horizontal length 374 μm, vertical length 280 μm) is CCD. Take a picture with a camera and get an observation image. Using the image analysis software "A image-kun (ver2.52)" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.) for this observation image, the distance between the centers of gravity of the closed pores is measured by the distance between the centers of gravity. Just find the distance. Hereinafter, when the image analysis software "A image-kun" is described, the image analysis software manufactured by Asahi Kasei Engineering Co., Ltd. is shown.

As the setting conditions of this method, for example, a threshold value indicating the brightness of the image may be 86, the brightness may be dark, the small figure removal area may be 1 μm ² , and a noise removal filter may be provided. The threshold value may be adjusted according to the brightness of the observed image. The brightness is dark, the binarization method is manual, the small figure removal area is 1 μm ^2, and the noise removal filter is provided, and the threshold is set so that the marker appearing in the observation image matches the shape of the closed pores. You can adjust the value.

In the cross section including the wetted surface of the convex portion 4, the concentration of silicon on the wetted surface is preferably higher than the concentration of silicon on the internal virtual surface parallel to the wetted surface.

Since the contact angle of silicon with respect to pure water is small, it is possible to increase the efficiency of removing stains when cleaning with a water-soluble detergent with such a configuration.

The concentration of silicon is a color mapping image of silicon using an electron probe microanalyzer (EPMA) for a polished cross section including the wetted surface (horizontal length: 120 μm, vertical length: 90 μm). Should be observed.

Further, the ceramics on the wetted surface of the convex portion 4 have a plurality of crystal particles and a grain boundary phase, and the width (w) of the grain boundary phase located between the adjacent crystal particles is 0.7 μm or more. It is 2.6 μm, and the ratio (d / w) of the depth (d) of the grain boundary phase to the width (w) of the grain boundary phase may be 0.06 to 0.18. If the width (w) of the grain boundary phase is in the above range and the ratio (d / w) of the depth (d) of the grain boundary phase is 0.06 or more, the contact angle with pure water becomes small. When washed with a water-soluble detergent, the dirt removal efficiency can be increased. When the width (w) of the grain boundary phase is in the above range and the ratio (d / w) of the depth (d) of the grain boundary phase is 0.18 or less, the bonding force between the crystal particles by the grain boundary phase Is sufficiently maintained, so that even if high-pressure washing is performed with a water-soluble detergent, the risk of grain separation is reduced.

For the width (w) and depth (d) of the grain boundary phase, an atomic force microscope (7500AFM / SPM manufactured by Keysight Technology) was used, the measurement mode was ACAFM mode, and the scanning speed of the probe used for measurement was 0.15 lines. With / sec, the measurement area being 20 μm × 20 μm, the length of the measurement target being 7 μm to 20 μm, and the resolution being 512 pixels × 512 pixels, the cross-sectional profile of the wetted surface was obtained, and the ratio (d / w) was the grain boundary phase. It may be calculated using each measured value of the width (w) and the depth (d) of.

Further, the average diameter of the crystal particles of the ceramics on the wetted surface of the convex portion 4 may be 2 μm to 8 μm. When the average diameter of the crystal particles is in the above range, the contact angle with pure water is further reduced, so that the dirt removal efficiency can be increased when cleaning with a water-soluble detergent.

Here, the average diameter of the crystal particles of the ceramics can be obtained as follows.

The polished surface is etched at a temperature of, for example, 1480 ° C. until the crystal grains and the grain boundary layer can be distinguished from each other to obtain an observation surface.

Using a scanning electron microscope, draw six straight lines of the same length, for example, 30 μm, radially around an arbitrary point in a range of 60 μm × 44 μm, which is a 2000-fold magnification of the reflected electron image on the observation surface. The average diameter can be obtained by dividing the total length of the straight line by the total number of crystals existing on the straight line.

In particular, the contact angle of the wetted surface of the convex portion 4 with respect to pure water may be 37 ° or less, and the coefficient of variation thereof may be 0.02 or less. As a result, when cleaning is performed with a water-soluble detergent, the efficiency of removing stains can be increased, and local stains can be suppressed from being left behind.

Further, the convex portion 4 may be covered with a film made of a compound containing fluorinated polysiloxane on at least one of the side surface and the end surface. After cleaning with a water-soluble detergent, the lotus effect of the water droplets adhering to the surface coated by the film adsorbing the dirt can be obtained, so that the dirt removal efficiency can be improved.

The contact angle of the wetted surface of the membrane with pure water may be 104 ° or more, and the coefficient of variation may be 0.01 or less. When washed with a water-soluble detergent, the efficiency of removing stains can be increased, and local stains can be suppressed from being left behind.

The contact angle of the wetted surface can be determined in accordance with JIS R 3257: 1999. For example, if a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model CA-X) is used and 5 or more points are measured. good.

Next, the method for manufacturing the stirring rod of the present disclosure will be described when the stirring rod is made of high-purity alumina ceramics.

An organic binder, a plasticizer, a lubricant, and ion-exchanged water are added to each of the main components, aluminum oxide powder (purity of 99.9% by mass or more) and magnesium hydroxide, silicon oxide, and calcium carbonate powder. , A universal stirrer, a rotary mill, a V-type stirrer or the like is used for stirring, and then a three-roll mill, a kneader or the like is used for kneading to obtain a plasticized clay.

Here, the content of magnesium hydroxide powder in a total of 100% by mass of the powder is 0.43 to 0.53% by mass, the content of silicon oxide powder is 0.02 to 0.04% by mass, and that of calcium carbonate powder. The content is 0.020 to 0.071% by mass, and the balance is aluminum oxide powder and unavoidable impurities. The organic binder is a water-soluble binder such as methyl cellulose and hydroxypropyl methyl cellulose.

Next, the clay is molded by an extrusion molding machine, and a precursor of a stirring portion having a plurality of convex portions and a precursor of a shaft portion having the same axial center as the precursor on one end surface in the axial direction of the precursor. Obtain a molded body with and. Then, the stirring rod of the present disclosure can be obtained by firing the molded product at a firing temperature of 1500 ° C. to 1700 ° C. and a holding time of 4 hours to 6 hours.

After firing, at least one of the side surface and the end surface of the convex portion may be polished, and then the temperature may be set to 1600 ° C. to 1700 ° C. and held for 1 hour to 4 hours for heat treatment. It is possible to obtain a stirring rod having a contact angle of the wetted surface of the portion with pure water of 37 ° or less and a coefficient of variation of 0.02 or less. For polishing, for example, a lapping machine made of diamond abrasive grains and copper having an average particle size of 1 μm to 2 μm may be used, in which the surface pressure applied to the side surface or end surface to be polished is 0.03 MPa to 0.05 MPa.

Here, the convex portion is at least subject to coating in order to obtain a stirring rod coated with a film composed of a compound containing a polysiloxane having fluorinated at least one of a side surface and an end surface or a composition containing a silicone oligomer. The surface of the convex portion may be coated by a method such as flow coating, dipping, or spraying, and then dried at, for example, 130 ° C. to 150 ° C.

In order to obtain a stirring rod having a contact angle of the wetted surface of the membrane with pure water of 104 ° or more and a coefficient of variation of 0.01 or less, for example, it may be dried at the above temperature for 20 to 40 minutes. ..

The present disclosure is not limited to the above-described embodiment, and various changes and improvements can be made within the scope of the claims.

1 Stirring rod 2, 2a, 2b, 2c Stirring part 3 Shaft part 4 Convex part 8 Sample solution 9 Stirring tank A Axial center

Claims (13)

It is made of an integrally molded ceramic product having a stirring portion having a cross section orthogonal to the axial center having a constant shape along the axial direction, and is characterized in that a plurality of convex portions are arranged in the circumferential direction in the cross section. Stirring rod. The stirring rod according to claim 1, wherein the stirring portion has a curved axis. The stirring rod according to claim 1 or 2, wherein the plurality of convex portions have a tapered shape whose width narrows toward the tip in the cross section. The stirring rod according to any one of claims 1 to 3, wherein the plurality of convex portions have a curved surface shape in the cross section. 2. The stirring rod according to any one. Any of claims 1 to 5, wherein the concentration of silicon on the wetted surface is higher than the concentration of silicon on the internal virtual surface parallel to the wetted surface in the cross section including the wetted surface of the convex portion. Stir bar described in Crab. The ceramics on the liquid contact surface of the convex portion has a plurality of crystal particles and a grain boundary phase, and the width (w) of the grain boundary phase located between the adjacent crystal particles is 0.7 μm. The claim is that the ratio (d / w) of the depth (d) of the grain boundary phase to the width (w) of the grain boundary phase is 0.06 to 0.18. The stirring rod according to any one of 1 to 6. The stirring rod according to claim 7, wherein the average diameter of the crystal particles of the ceramics on the wetted surface of the convex portion is 2 μm to 8 μm. The stirring rod according to any one of claims 6 to 8, wherein the contact angle of the wetted surface of the convex portion with pure water is 37 ° or less, and the coefficient of variation thereof is 0.02 or less. The method for manufacturing a stirring rod according to any one of claims 6 to 9, after polishing at least one of the side surface and the end surface of the convex portion, the temperature is set to 1600 ° C. to 1700 ° C. for 1 hour to 4 hours. A method for manufacturing a stirring rod, which is held and heat-treated. The stirring rod according to any one of claims 1 to 5, wherein the convex portion is coated with a film composed of a compound containing a fluorinated polysiloxane or a composition containing a silicone oligomer, at least one of a side surface and an end face. .. The stirring rod according to claim 11, wherein the contact angle of the wetted surface of the membrane with pure water is 104 ° or more, and the coefficient of variation thereof is 0.01 or less. A stirring device including the stirring rod according to any one of claims 1 to 9, claim 11 or 12.

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