JP2015055630A - Powder dispersion method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To disperse particles uniformly.SOLUTION: A sample dispersion device for providing a substantially uniform dispersion of particles is disclosed. The device includes a surface for carrying a sample and a flow channel connecting an inlet to an outlet. The device can be operated so that the sample is dispersed when fluid passes the flow channel and flows on the surface from the inlet to the outlet. The surface faces the direction of the inlet, and is kept without damage during the dispersion.

Description

Detailed Description of the Invention

The present invention relates to an apparatus for dispersing powder, and more particularly to an apparatus and method for dispersing powder so that constituent particles of the powder can be analyzed.
Some methods for characterizing particulate samples require that the sample be first dispersed so that individual particles are spatially separated. For example, a characterization technique using a microscope may require the particles to be dispersed on the surface with the particles spatially separated. Parameters such as the size and shape of each particle can then be determined using, for example, automatic scanning techniques and image processing techniques. In order to obtain good results, it is advantageous to separate the sample particles in an appropriately repeatable manner.

  One configuration for dispersing the particles is that a powder sample is placed on a support and is disclosed in EP-A-2602604. A pressure differential is applied across the support, the support bursts, and the sample is dispersed in the dispersion chamber and deposited on the surface at the bottom of the dispersion chamber. The carrier (which may be in the form of a film or a disk) is a consumable part. Devices (and methods) that do not require consumable parts are advantageous. Furthermore, this method of dispersing the particles can in some circumstances cause the particles to break when they impact the collection surface. For certain types of samples (eg fragile samples), a sample dispersion that is less prone to breakage may be desirable.

  International Publication No. WO 03/074154 discloses an apparatus for dispersing particles in which a particle sample holder is mounted in a particle settling chamber above the particle collection surface. A high-pressure gas release device is oriented in the direction of the sample holder and settles from the sample holder so as to settle the particles on a collection surface (which may be a stub used in a scanning electron microscope). Used to supply high pressure gas to disperse particles into the chamber. In order to place the sample on the sample holder, the particle settling chamber must be disassembled and the sample can be dropped directly onto the sample holder (not dispersed) when the settling chamber is reassembled Is required.

  US 2009/0233636 and US 5,693,895 disclose sample collection devices in which particles carried by a gas stream impinge on a collection surface adjacent to a slot-shaped inlet. ing.

The object of the present invention is to overcome or at least ameliorate the above mentioned problems.
According to a first aspect of the present invention, there is provided a sample dispersion device comprising a surface for carrying a sample and a flow path connecting an inlet opening and an outlet opening, wherein the fluid passes through the flow path. Operable to disperse the sample as it flows across the surface from the inlet opening to the outlet opening, so that the surface faces in the direction of the inlet opening and remains intact during dispersion. A configured sample dispersion device is provided. The surface preferably remains substantially stationary during dispersion. The arrangement of this surface facing the inlet opening increases the entrainment of the sample into the moving fluid as it impinges on the sample.

  The flow direction of the fluid entering the flow path via the inlet opening and the flow direction of the fluid exiting the flow path via the outlet opening are substantially the same direction. The resulting change in fluid flow direction results in good dispersion. Furthermore, providing inflow and outflow in the same direction means that the dispersion device is straight to incorporate as part of the axial flow configuration. The axis of the inlet opening may be substantially coincident with the axis of the outlet opening. Aligning the inlet and outlet openings tends to result in a uniform distribution of particles around the axis.

The sample dispersion device may be configured to provide a substantially uniform dispersion of the particles.
The inlet opening may be configured to provide a uniform inflow of fluid across the sample carrying surface. For example, the inlet opening may be substantially circular. The inlet aperture may be rotationally symmetric higher than 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 10th, 12th, 20th, or 50th. The aspect ratio of the inlet opening may be approximately 1, or 1.5 or less, 2 or less, 2 or less. It may be 5 or less, or 3 or less. Such a configuration of the inlet opening helps to provide a uniform flow of fluid across the sample carrying surface and hence a more uniform distribution of the particles.

  The outlet opening may comprise a plurality of holes. The outlet opening may be appropriately arranged around the surface by providing a plurality of holes while leaving a material for supporting the surface. An outlet opening may be disposed around the surface.

  The outlet opening may be configured to provide a uniform distribution of flow from the outlet and thus a uniform distribution of the particles. For example, the outlet opening may be substantially circular. The exit openings may be rotationally symmetric higher than 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 10th, 12th, 20th, or 50th. The aspect ratio of the outlet opening may be approximately 1, or 1.5 or less, 2 or less, 2.5 or less, or 3 or less. Such a configuration of the outlet opening helps to provide a uniform fluid flow from the outlet and hence a uniform distribution of particles.

The hole in the outlet opening may be substantially circular.
The inlet opening may have a smaller area than the surface. The projection of the inlet opening towards the surface along the axis of the inlet opening may be within the surface. This arrangement assists in directing the sample to the surface when the sample is placed and also assists in directing the fluid toward the sample during dispersion.

  The device may further comprise a funnel that tapers toward the inlet opening, the outlet of the funnel being the inlet opening. The funnel may act as a nozzle, which may increase the fluid velocity as it approaches the surface and assist in easily placing the sample on the surface.

  The device has a device axis and may be substantially cylindrical. This shape can be suitably mounted with other circular parts. The device axis may be substantially coincident with the axis of the inlet opening and the axis of the outlet opening, and may pass through the centroid of the surface. By arranging the inlet opening, the outlet opening and the surface coaxially, the sample is uniformly distributed along the device axis.

  Many features of the device as a whole may be relatively high order rotationally symmetric about the device axis, which increases the uniformity of particle distribution. The inlet opening, the sample carrying surface, and the outlet opening may be rotationally symmetric about the device axis. The rotational symmetry of these features about the device axis is higher than second, third, fourth, fifth, sixth, seventh, eighth, tenth, twelfth, twentieth, or fifty. It may be the following. The device may be substantially rotationally symmetric where the inlet opening, the sample carrying surface, and the outlet opening are (generally) homogeneous. The surface may form a channel wall.

  The device may have a lip around the surface. The lip may assist in holding the sample on the surface, or may assist in the dispersion of the sample by the moving fluid by affecting the direction of flow.

The surface may be substantially flat.
According to a second aspect of the invention, the housing forms a dispersion chamber at least when the base of the housing is closed, the device according to the first aspect of the invention, and the outlet opening of the device is the inlet to the dispersion chamber. A sample dispersion apparatus is provided comprising an adapter for positioning the device outside the dispersion chamber adjacent to the entrance to the dispersion chamber so as to communicate with the dispersion chamber.

  The apparatus further includes a fluid source (preferably a pressurized gas source) that acts to provide a positive pressure pulse through the device to entrain the particulate sample on the surface and disperse the sample in a dispersion chamber. ) May be provided.

  The pressure pulse may have a pressure between 0.2 bar (20 kPa) and 10 bar (1000 kPa) (gauge). The pressure pulse may have a duration between 1 and 300 milliseconds. Preferably, the pressure pulse may have a pressure between 0.75 bar (75 kPa) and 1.25 bar (125 kPa). Preferably, the pressure pulse may have a duration between 5 milliseconds and 100 milliseconds.

The apparatus may comprise a collection surface for collecting particles as they settle in the dispersion chamber.
The apparatus may further comprise a particle analysis assembly including an apparatus for analyzing particles deposited on the collection surface.

  According to a third aspect of the present invention, there is provided a method of dispersing a sample using the device according to the first aspect of the present invention, wherein the sample is disposed on the surface and when the fluid flows through the outlet opening. Flowing a fluid from the inlet opening to the outlet opening through the flow path such that the sample is entrained in the fluid.

The fluid may be a pressurized gas (such as filtered dry air).
Flowing the fluid may include applying a positive pressure pulse to the inlet opening.
The method may include using the device according to the first aspect as part of the sample dispersion apparatus according to the second aspect, and the sample may be dispersed in the dispersion chamber by a fluid.

  Embodiments of the present invention will be described below by way of example with reference to the accompanying drawings.

1 is a schematic cross-sectional side view of a device according to an embodiment of the first aspect of the present invention. FIG. FIG. 2 is a cross-sectional perspective view of the device of FIG. FIG. 2 is a perspective view of the device of FIG. 1 when viewed from the outlet side. FIG. 2 is a perspective view of the device of FIG. 1 when viewed from the entrance side. FIG. 2 is a schematic diagram of an apparatus according to an embodiment of the second aspect of the present invention, including the device of FIG. FIG. 3 is a graph showing a comparison of particle size distributions (by number) obtained using a sample dispersion device according to the prior art (using a rupture foil) and a sample dispersion device according to an embodiment of the first aspect of the invention, respectively; is there. 1 is a photomicrograph of a fluticasone propionate sample dispersed on a collection surface using a device with a rupture foil according to the prior art. FIG. 2 is a photomicrograph of a fluticasone propionate sample dispersed on a collection surface using a device according to an embodiment of the present invention. FIG.

  Referring to FIGS. 1-4, a device 100 is shown comprising a fixed surface 4 for carrying a sample, an inlet opening 1, an outlet opening 2, and a channel 9. The flow path 9 connects the inlet opening 1 to the outlet opening 2 so that fluid can enter the flow path 9 via the inlet opening 1 and exit the flow path via the outlet opening 2.

  Since the fluid entering the flow path 9 through the inlet opening 1 tends to collide with the fixed surface, the fixed surface is arranged so that the particulate sample on the fixed surface 4 is easily caught in the moving fluid. 4 is arranged facing the inlet opening 1. In this embodiment, the fixing surface 4 is flat and the normal direction from the surface 4 is parallel to the axis of the circular inlet opening 1. In other embodiments, the surface 4 may not be flat. For example, the surface 4 may be concave or other suitable shape.

  When viewed along the axis of the inlet opening 1, the outer area of the inlet opening 1 lies completely within the area of the surface 4. This arrangement ensures that any sample that falls into the flow path 9 through the inlet opening 1 in a direction substantially parallel to the axis of the inlet opening 1 will land on the lower surface 4. Around the surface 4 is provided a lip 5 that assists in holding the sample on the surface 4. Furthermore, the lip 5 may be configured to increase the entrainment of the sample in the moving fluid. The lip 5 in the present embodiment has a shape that matches a part of the ring.

  The device 100 further comprises a funnel 6 that guides the sample to the inlet opening 1 and provides a nozzle for increasing the velocity of the sample flowing through the funnel 6 toward the inlet opening 1. . The funnel portion 6 is tapered toward the inlet opening 1.

  In this embodiment, the center of the surface 4 coincides with the axis of the inlet opening 1, the inlet opening 1 and the surface 4 are both circular, and the radius of the inlet opening 1 is smaller than the radius of the surface 4. In other embodiments, the inlet opening 1 and the surface 4 may be different shapes and may not be circular.

  The outlet opening 2 has a plurality of circular openings arranged at equal intervals on a circle having an axis coinciding with the axis of the inlet opening 1. Each circular opening may be arranged in front of the chamfered portion into which the fluid flowing from the flow path 9 through the outlet opening 2 flows. The fact that the outlet opening 2 and the inlet opening 1 have a common axis means that the fluid entering the device 100 through the inlet opening 1 exits the device 100 while flowing in the substantially same direction through the outlet opening 2. . In this embodiment, a plurality of circular openings are used as the outlet openings 2, but in other embodiments, the outlet openings 2 may include multiple annular slots (eg, a single annular slot).

  In the present embodiment, the main body of the device 100 has a substantially right cylindrical shape, the first opening 1 is at one circular end of the main body, and the outlet opening 2 is at the other circular end of the main body. The fluid flowing through the device 100 enters through the inlet opening 1 while flowing in a substantially axial direction, impinges on the surface 4 and entrains the sample as the flow direction changes, so that the flow direction is outward. It changes to a substantially radial flow. Thereafter, when the fluid exits through the outlet opening 2, the direction of the fluid flow changes again, and the fluid again becomes a substantially axial flow.

  Referring to FIG. 5, the device 100 of FIGS. 1-4 installed as part of the sample dispersion apparatus 200 is shown. Apparatus 200 includes device 100, housing 201, adapter 203, clamp 205, and fixture 204.

  The housing 201 is configured to form a dispersion chamber in which the sample is dispersed by the sample dispersion device 100. The dispersed sample is collected on a collection surface so that the particles of the sample can be analyzed using, for example, a microscope. In the present embodiment, the housing is substantially cylindrical. The first end (base) of the housing is open and is intended to be closed by a collection surface. The second end of the housing 201 has a threaded opening 210 for receiving the adapter 203.

  The adapter 203 is configured to be attached to the opening 210 at the second end of the housing 201, and a threaded portion 230 is provided for this purpose. The adapter 203 further includes a collar 231 by which the apparatus can be movably gripped. The adapter 203 has a shoulder 232 for engaging with the main body of the device 100 and a seal 233 that can be hermetically engaged with the main body of the device 100. The adapter 203 has a through hole that communicates from the device 100 to the dispersion chamber.

  When the device 100 is engaged with the adapter 203, the device 100 is hermetically engaged with the adapter 203 with the outlet opening 2 of the device 100 facing the dispersion chamber and the inlet opening 1 facing the clamp 205. Is clamped by the clamp 205.

  The clamp 205 is engaged with the adapter 203 using a screw arrangement on the adapter 203 and the clamp 205. The clamp 205 engages a fixture 204 that can be connected to a fluid source. The clamp 205 includes a through hole that communicates from the fluid supply source to the dispersion chamber. A seal is provided for engagement between the clamp 205 and the device 100, and another seal is provided for engagement between the clamp 205 and the adapter 203.

  A method for dispersing a sample using the apparatus includes the following steps. The sample is placed on the sample carrying surface 4 via the inlet opening 1 of the device 100. During this process, the clamp 205 is not engaged with the adapter 203 so that the user can access the inlet opening 1 of the device 100. Thereafter, the clamp 205 is engaged with the adapter 203 so that a sealing engagement occurs between the device 100 and the adapter 203, between the device 100 and the clamp 205, and between the clamp 205 and the adapter 203. A sample collection surface (not shown) is brought into contact with the base of the housing 201 to close the housing 201 and form a dispersion chamber.

  A fluid source is connected to the fixture 204 and is used to supply a predetermined amount of fluid to the device 100 at positive pressure, thereby allowing the sample to enter the dispersion chamber for collection on the sample collection surface. Disperse. The fluid source may be operable to provide fluid for a predetermined time at a predetermined pressure. By such control, dispersion of various samples can be performed highly repeatably and effectively.

The test was conducted using the sample dispersion apparatus shown in FIG. A comparative test was performed against a conventional design of a sample dispersion device that uses a sample-carrying membrane that bursts under a positive pressure pulse.
The performance of the device according to one embodiment of the present invention is qualified using quality audit standards, including polydisperse glass bead migration standards that have been used to determine whether the performance of the dispersion device is eligible. It was recognized that there was. The fluid used was filtered compressed dry air.

  The apparatus 200 with the device 100, according to one embodiment of the present invention, is very effective for quality audit standards that employ a fluid injection time of 20 milliseconds, a pressure of 1 bar (100 kPa), a settling time of 60 seconds. It has been found to provide dispersion. These parameters provide results that are in good agreement with those obtained with conventional designs of sample dispersion devices.

  FIG. 6 shows some exemplary results obtained using the sample dispersion apparatus 200 according to one embodiment of the present invention. The percentage of particles by number of particles (as a percentage) is plotted on the Y axis and the CE particle size is plotted on the X axis. The CE (equivalent to circle) diameter is the diameter of a circle having the same area as the projected particle image. A curve 402 obtained using one embodiment of the present invention at a pressure of 1 bar (100 kPa), an injection time of 20 milliseconds, a settling time of 60 seconds was obtained using a prior art device. It is in good agreement with the reference curve 401. Some variation between samples is inevitable, but the variation is within an acceptable range of variation.

  Various sample types were subsequently tested, including sertraline hydrochloride, lactose, cement, fluticasone propionate. Compared to the prior art design, a broadly similar dispersion result was obtained, but as shown in FIGS. 7 (a) and 7 (b), particle breakage resulting from impact on the sample collection surface was not observed. Less evidence is available, and therefore dispersion using one embodiment of the present invention is advantageous.

  FIG. 7 (a) shows a sample of fluticasone propionate dispersed using a prior art sample dispersion device. An injection pressure of 4 bar (400 kPa), an injection time of 10 milliseconds and a settling time of 60 seconds were used. The sample was placed on a 25 μm thick foil and another 25 μm thick foil was placed upstream of the sample carrying surface. The resulting dispersed sample contains particulates 301 that appear to be the result of the larger particles 302 being destroyed upon impact at the sample collection surface.

  This was dispersed using one embodiment of the present invention using the same dispersion setting (4 bar (400 kPa) injection pressure, 10 milliseconds injection time, 60 seconds sedimentation time), FIG. This is in contrast to FIG. 7B, which shows a sample of the same material as a). A group of particles cannot be seen on the sample collection surface and all particles 302 are well separated.

  Embodiments of the present invention have been presented to provide a useful alternative to prior art dispersion devices that rely on a sample-bearing surface to burst under a positive pressure pulse. Embodiments of the present invention do not require a consumable foil for each test, thereby overcoming the problems associated with prior art configurations. Embodiments of the invention have been shown to provide a good dispersion that at least corresponds to the dispersion obtained using prior art methods, and in some situations exhibits improved dispersion. . In particular, embodiments of the present invention show a less severe dispersion mechanism, resulting in less particle breakage upon impact at the sample collection surface. Furthermore, embodiments of the present invention provide greater flexibility and control sample dispersion. When a disc that bursts is used, the discs that can be used are limited by variations in disc thickness. Since the number of available disk types may be relatively limited, the degree of control over dispersion is limited. Prior art embodiments provide improved flexibility and control by allowing both injection pressure and injection time to be adjusted over a continuous range.

  While several specific embodiments have been described, the invention is not so limited, and many modifications and variations are within the scope of the invention as defined by the appended claims. It will be appreciated that variations are possible.

Claims (23)

  A sample dispersion device for providing a substantially uniform dispersion of particles comprising a surface for carrying a sample and a flow path connecting an inlet opening and an outlet opening, wherein the device is configured to allow fluid to enter the inlet. It can be actuated to disperse the sample as it flows through the flow path from the opening to the outlet opening and across the surface, the surface facing in the direction of the inlet opening, A device that is configured to remain intact.   The device according to claim 1, wherein a flow direction of fluid entering the flow path through the inlet opening and a flow direction of fluid exiting the flow path through the outlet opening are substantially the same direction.   The device of claim 2, wherein an axis of the inlet opening substantially coincides with an axis of the outlet opening.   The device according to claim 1, wherein the outlet opening comprises a plurality of holes.   The device according to claim 1, wherein the outlet opening is arranged around the surface.   The device according to claim 1, wherein the inlet opening has an area smaller than the area of the surface.   The device of claim 6, wherein a projection along the axis of the inlet opening toward the surface of the outlet opening is within the surface.   The device of claim 7, further comprising a funnel section tapered toward the inlet opening, wherein the outlet of the funnel section is the inlet opening.   The device according to claim 1, wherein the device is substantially cylindrical and has a device axis.   The device of claim 9, wherein the device axis substantially coincides with the inlet opening axis and the outlet opening axis and passes through a centroid of the surface.   The device according to claim 1, wherein the surface forms a wall of the flow path.   12. A device according to any preceding claim, further comprising a lip around the surface.   The device according to claim 1, wherein the surface is substantially flat.   14. A device according to any one of the preceding claims, wherein at least one of the inlet opening and the outlet opening is rotationally symmetric greater than second order or third order.   15. A device according to any one of the preceding claims, wherein at least one of the inlet opening and outlet opening comprises a circular hole. A housing for forming a dispersion chamber when closed at least at the base of the housing;
The device according to any one of claims 1 to 15,
A sample dispersion apparatus comprising: an adapter for positioning the device outside the dispersion chamber adjacent to the entrance to the dispersion chamber such that the outlet opening of the device communicates with the entrance to the dispersion chamber.   17. The fluid source of claim 16, further comprising a fluid source operable to provide a positive pressure pulse through the device to entrain a particulate sample on the surface and disperse the sample in the dispersion chamber. apparatus.   The apparatus of claim 17, comprising a collection surface for collecting particles as they settle in the dispersion chamber.   The apparatus of claim 18, further comprising a particle analysis assembly including an apparatus for analyzing particles deposited on the collection surface. A method of dispersing a sample using the device of any one of claims 1-15, comprising:
Placing a sample on the surface;
Flowing the fluid through the flow path from the inlet opening to the outlet opening so that the sample is entrained in the fluid as it flows through the outlet opening;
Including methods.   21. The apparatus of claim 20, wherein the fluid is a gas.   22. A method according to claim 20 or 21, wherein flowing the fluid comprises applying a positive pressure pulse to the inlet opening.   The device is used as a part of a sample dispersing apparatus according to any one of claims 16 to 19, and the sample is dispersed in the dispersion chamber by the fluid. The method described in 1.