JPH07140063A - Method and device for molding tablet sample for infrared spectrophotometry - Google Patents

Abstract

PURPOSE:To mold a tablet sample into such shape as the quality of infrared absorption spectrum can be improved. CONSTITUTION:A head 42 secured to the forward end of a press 40 is provided, in its center with a columnar protrusion 44 having convex spherical end face 46. A tablet sample mold 34 comprises an annuiar lead frame 38 bonded to one surface of a copper base plate 36 and a small hole 37, having inner diameter equal to or smaller than that of the annular frame 38, is made through the base plate 36 in the center of the frame 38. The base plate 36 is set on a surface plate 32 having flat surface while touching the surface plate 32 on the opposite side to the frame 38. The inside of the frame 38 and the hole in the base plate are then filled with a sample powder 10 which is subsequently pressed from above by the protrusion 44 of the head 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared spectrophotometer such as FTIR (Fourier Transform Infrared Spectrophotometer) which comprises a solid sample powder and an infrared non-absorber such as KBr for measuring a solid sample. The present invention relates to a tablet sample molding device that pressurizes and molds a sample powder mixed with powder.

[0002]

2. Description of the Related Art To measure a solid sample by FTIR, K
A solid sample powder is mixed with Br powder in an amount of 0.1% to several%, and the mixture is pressed to form tablets. The molded tablet sample is mounted in the FTIR sample chamber and the infrared absorption is measured.

A tablet sample is a mixed powder containing the sample molded into a disk shape, and the tablet diameter is 10 mm or 20.
Two types are mainly made: a tablet sample having a size of mm and a small tablet called a micro tablet having a diameter of several mm.

To form a tablet having a large size, a tablet forming machine as shown in FIG. 1 is used. This tablet molding machine has a substrate 2 having a cylindrical protrusion 4 at the center of a disc,
A cylindrical inner cylinder 6 having an inner diameter equal to the outer diameter of the projection 4 is covered, and a plate 8 called a mirror surface plate having a flat surface is placed in the inner cylinder 6 and the flat surface of the plate 8 is covered. Sample powder and K on top
A mixed powder (hereinafter referred to as a sample powder) 10 with an infrared non-absorber powder such as Br is filled. A plate 12 called a mirror plate having a flat surface is placed on the sample powder 10 such that the flat surface is on the sample powder 10 side. The outer cylinder 14 is covered so as to cover the inner cylinder 6 laterally and upwardly.
A push rod 16 located on the mirror plate 12 is disposed at the center of the. The push rod 16 is slidably fitted in the center of the outer cylinder 14, and an O-ring 18 for keeping airtightness is provided between the push rod 16 and the outer cylinder 14. Further, the substrate 2 is provided with an exhaust hole 20 for exhausting the air in the sample powder 10,
It is exhausted by a vacuum pump through the exhaust hole 20.

The sample powder 10 sandwiched between the mirror-finished plates 8 and 12 is sucked out of air through an exhaust hole 20 and discharged.
By pressing with a pressing device from above via the push rod 16, a disk-shaped tablet whose upper and lower surfaces are parallel is molded.

As shown in FIG. 2, the molding machine for molding the micro tablets has push plates 24 and 26 fitted from above and below a circular hole at the center of a cylindrical outer cylinder 22. The push plate 26 arranged on the lower side is provided with a cylindrical convex portion 26 having the same size as the hole of the outer cylinder 22, and the push plate 28 arranged on the upper side has the same size as the hole of the outer cylinder 22. Cylindrical protrusion 30
Is provided, and the tips of both the convex portions 26 and 30 are processed to be flat.

In order to mold the micro tablets, the convex portion 26 of the lower push plate is fitted into the hole of the outer cylinder 22 from the lower side to form the outer cylinder 22.
The sample powder 10 in which the sample powder and the KBr powder are mixed is filled on the convex portion 26 in the hole of the press plate 28 from above the hole.
The convex portion 30 is fitted. Then, the lower push plate 24 is placed on a surface plate, and the sample powder 10 is pressed from the upper push plate 28 by a pressing device to form tablets.

The tablet sample molded by the molding machine of FIG. 1 is taken out from the inner cylinder 6 and mounted on the FTIR sample holder for measurement. The tablet sample molded by the molding machine of FIG.
It is mounted on a TIR sample holder and measured.

[0009]

When a transmission measurement is carried out by an infrared spectrophotometer such as FTIR using a tablet sample obtained by pressure molding with the molding machine of FIGS. 1 and 2, the red color of FIG. 8 is obtained. A periodic signal as indicated by the symbol R appears in the outer absorption spectrum, which may make the infrared absorption spectrum difficult to see.

One way to reduce such periodic signals is to increase the thickness of the sample. Increasing the thickness of the sample is to increase the amount of KBr, but if the amount of KBr is increased without changing the concentration of the sample with respect to KBr, the amount of sample is increased and the infrared absorption by the sample becomes too large. , Unable to make proper measurements. To keep the infrared absorption of the sample proper, KBr
The concentration of the sample must be reduced.

Lowering the concentration of the sample relative to KBr causes another problem. That is, the absorption indicated by symbol A in the infrared absorption spectrum of FIG. 8 is not absorption by the sample but absorption by the water contained in KBr powder, but the amount of KBr increases as the tablet thickness increases. As described above, the absorption due to other than the sample becomes relatively large with respect to the absorption of the sample, which deteriorates the quality of the infrared absorption spectrum.

The absorption of water contained in KBr powder causes
In the tablet molding machine of FIG. 1, the sample powder is sucked in vacuum, so it is relatively small, but in the tablet molding machine of the type in which the sample powder is not sucked in vacuum as in the micro tablet molding machine of FIG.

An object of the present invention is to provide a tablet sample molding method capable of reducing a periodic signal which deteriorates the quality of infrared absorption spectrum and infrared absorption due to other than a sample, and an apparatus therefor. Is.

[0014]

The inventor has determined that the periodic signal shown as R in the infrared absorption spectrum of FIG. 8 is an interference due to the parallelism of the tablet sample on the top and bottom surfaces. It has been found that the quality of the infrared absorption spectrum can be improved by locating and eliminating the interference.
Therefore, in the present invention, interference is eliminated by making the upper surface and the lower surface of the tablet sample obtained by molding into a non-parallel state.

The tablet sample molding method of the present invention is a tablet sample molding method which uses a device for pressurizing a sample powder in which the surface in contact with the upper surface of the sample powder and the surface in contact with the lower surface are not parallel to each other. is there. The upper surface and the lower surface correspond to a pair of circular surfaces of the disk-shaped tablet when the sample powder is molded into a tablet. In the measurement, the tablet sample may be held in the vertical direction, and in that case also, one of the pair of circular surfaces of the disk-shaped tablet is called the upper surface and the other is the lower surface. In a preferred embodiment, of the surfaces in contact with the upper surface and the lower surface of the sample powder, one is a flat surface and the other is a convex curved surface.

Pressing the sample powder into a tablet sample 1
As one method, the sample powder is filled in an annular frame and pressure-molded, the frame is attached to the tablet sample for measurement, and after the measurement, the frame is discarded together with the tablet sample. Methods using the body are being investigated. The tablet sample molding device applied to the method using such a frame is
This is a molding device that places an annular frame on the flat surface of the surface plate, fills the sample powder into the frame, and presses the sample powder from above with a pressing device to form a sample. The head surface that comes into contact with the powder is curved. In a preferred embodiment of such a tablet sample molding device, a head having a head surface that comes into contact with the sample powder is detachable from the press device.

A tablet sample molding apparatus applied to a tablet sample molding apparatus such as the tablet molding machine shown in FIG. 1 has at least one of an upper plate and a lower plate in contact with the sample powder, and a contact surface with the sample powder has a curved surface. Has become. In a tablet sample molding apparatus applied to a tablet sample molding apparatus such as the micro tablet molding machine in FIG. 2, at least one of the lower push plate and the upper push plate has a curved tip end surface.

[0018]

The tablet sample obtained by pressure molding according to the present invention has a pair of surfaces through which infrared rays are transmitted or reflected which are non-parallel to each other in the infrared absorption measurement, so that the infrared rays interfere with each other on the pair of surfaces. It can be suppressed.

[0019]

EXAMPLE FIG. 3 shows an example in which the present invention is applied to the tablet molding machine of FIG. A cylindrical inner cylinder 6 having an inner diameter equal to the outer diameter of the protrusion 4 is placed on a substrate 2 having a cylindrical protrusion 4 at the center of the disc, and the inner cylinder 6 has a flat surface. The lower plate 8 thus prepared is put in, and the flat surface of the plate 8 is filled with the sample powder 10. On the sample powder 10 is placed an upper plate 12a whose surface in contact with the sample powder 10 is processed into a convex spherical surface. An outer cylinder 14 is covered so as to cover the inner cylinder 6 laterally and upward, and a push rod 16 located on the upper plate 12 is arranged at the center of the outer cylinder 14. Push rod 16
Is slidably fitted in the center of the outer cylinder 14, and an O-ring 18 for keeping airtightness is provided between the outer cylinder 14 and the outer cylinder 14. Further, the substrate 2 is provided with an exhaust hole 20 for exhausting the air in the sample powder 10, and the gas is exhausted by a vacuum pump through the exhaust hole 20.

The sample powder 10 sandwiched between the plates 8 and 12a is discharged from the exhaust hole 20 by sucking air, and is pressed by a pressing device from above via a push rod 16 so that one of It is molded into a disk-shaped tablet sample in which the surface is a flat surface and the other surface is a concave spherical surface.

Comparing the tablet forming apparatus of FIG. 3 with the conventional tablet forming apparatus of FIG. 1, the lower plate 8 sandwiching the sample powder 10 has the same flat surface in contact with the sample powder 10. However, the upper plate 12a is different in that the surface in contact with the sample powder 10 is a convex spherical surface. The plates 8 and 12a are made of steel. The portions of the plates 8 and 12a that come into contact with the sample powder 10 may be plated with chromium for the purpose of rust prevention.

In FIG. 3, the upper plate 12a has a flat surface in contact with the sample powder 10 as in the conventional case, while the contact surface of the lower plate 8 with the sample powder 10 is a convex spherical surface. It may be one. Further, both the lower plate and the upper plate may be convex spherical surfaces. Further, the spherical surface may be concave instead of being convex. further,
The spherical surface may be an elliptical surface or another curved surface.

FIG. 4 shows an embodiment in which the present invention is applied to the micro tablet molding machine shown in FIG. Cylindrical outer cylinder 2
Push plates 24 and 26 are fitted from above and below a hole having a circular diameter at the center of 2. The push plate 26 arranged on the lower side is provided with a cylindrical projection 26 having the same size as the hole of the outer cylinder 22, and the push plate 28a arranged on the upper side has the same size as the hole of the outer cylinder 22. The columnar convex portion 30a is provided. The tip of the lower convex portion 26 is processed into a flat surface, but the upper convex portion 30a
Is processed into a convex spherical surface. Push plates 24, 28
a is made of steel. Also in this case, the portion in contact with the sample powder 10 may be plated with chromium for the purpose of rust prevention.

To mold the micro tablets, the convex portion 26 of the lower push plate is fitted into the hole of the outer cylinder 22 from below, and the outer cylinder 22 is formed.
The sample powder 10 is filled on the tip surface of the convex portion 26 in the hole, and the convex portion 30a of the pressing plate 28a is fitted from the upper side of the hole. Then, the lower push plate 24 is placed on the surface plate, and pressure is applied from above the upper push plate 28a by a pressing device,
The sample powder 10 is pressed and molded into tablets. Also in this example, a disk-shaped tablet sample in which one surface is a flat surface and the other surface is a concave spherical surface is molded.

In FIG. 4 as well, both the convex portions 26 and 30a may be convex spherical surfaces, the tip surface of the upper convex portion may be a flat surface, and the tip surface of the lower convex portion may be a convex spherical surface. Further, the convex spherical surface may be replaced by a concave spherical surface, or the spherical surface may be replaced by an elliptic surface or another curved surface.

FIG. 5 shows still another embodiment.
(A) shows the head part of the press machine,
(B) is a vertical cross-sectional view showing a surface plate and a tablet sample preparing unit 34 on the surface plate. A head 42 is fixed to the tip of a pressing device 40 for pressurizing the sample powder 10. A columnar convex portion 44 is provided in the center of the head 42, and a tip end surface 46 of the convex portion 44 is processed to be a convex spherical surface. The head 42 is made of steel.
Also in this case, the portion in contact with the sample powder 10 may be plated with chromium for the purpose of rust prevention.

The tip surface 46 of the convex portion 44 of the head 42 is machined into a spherical shape having a radius of curvature such that the diameter A of the cylinder is 12 mm and the height B of the spherical surface portion is 1 mm. However, the dimensions A and B are merely examples, and the dimensions are not limited thereto.

As a method of fixing the head 42 to the pressing device 40, the head 42 may be magnetized and fixed to the pressing device 40 by magnetic force. Further, the head 42 and the pressing device 40 may be bonded with a double-sided adhesive tape.

In the tablet sample generator 34, an annular lead frame 38 is fixed to one surface of a copper substrate 36, and whether the inner diameter of the ring of the frame 38 is the same as the inner diameter of the substrate 36 at the center of the frame 38. A hole 37 smaller than that is opened. This hole 37 serves as a hole for transmitting infrared rays in the transmission measurement. An example of the thickness of the substrate 36 is 0.2 mm, and an example of the thickness of the frame 38 is 0.2 mm.
At 5 mm, an example of the outer diameter of the ring of the frame 38 is 9 mm, and an example of the inner diameter is 5 mm. Substrate 3 at the center of frame 38
An example of the diameter of the hole 37 formed in 6 is 3 mm. The frame 38 can be fixed onto the substrate 36 by soldering or spot welding.

To make a tablet sample in the embodiment of FIG.
The substrate 36 is placed on the surface plate 32 having a flat surface so that the surface of the substrate 36 on the side where the frame body 38 is not adhered is in contact, and the sample powder 10 is placed inside the frame body 38 and in the holes 37 of the substrate 36. Fill. The sample powder 10 is pressed from above the sample powder 10 by the convex portion 44 of the head 42. Thereby, the sample powder 10
Are molded in the frame 38 and the holes 37 of the substrate 36 to form a tablet sample. At this time, the lead frame 38 is deformed so as to spread outward and absorbs the fluctuation of the pressing force of the press device,
The hole 37 of the substrate 36 is not deformed, and the shape of the molded sample in this hole 37 portion is stably maintained. In the embodiment of FIG. 5, the convex portion 44
The shape of the tip surface of is not limited to a convex spherical surface, and may be a concave spherical surface. Also, instead of a spherical surface, another curved surface such as an elliptical surface may be used.

The tablet samples obtained in the respective examples are summarized in FIG. In FIGS. 6A, 6B and 6C, the left diagram is a perspective view and the right diagram is a cross-sectional view of the tablet sample taken in the thickness direction. The cutting position in the cross-sectional view of (C) is the position along the line XX '. The tablet sample obtained by molding in the example of FIG. 3 is shown in FIG.
As shown in (A), one surface 52 is a flat surface and the other surface 54 is a concave spherical surface.

The microtablets obtained in the embodiment of FIG. 4 are in a state in which the tablet sample 56 is molded in the hole of the outer cylinder 22, as shown in FIG. 6B. One surface 58 of the tablet sample 56 is a flat surface and the other surface 60 is a concave spherical surface.

Tablet sample 62 obtained by the embodiment of FIG.
As shown in FIG. 6 (C), the sample powder is molded in the lead annular frame 38 fixed on the copper substrate 36 and the holes 37 of the substrate. The lower surface 63 of the tablet sample 62 has a constant diameter in the hole 37 of the substrate 36,
Inside, the upper surface is a concave spherical surface 64.

FIG. 8 shows an example of the infrared absorption spectrum measured by the FTIR transmission method using the tablet sample molded as shown in FIG. 6 (C). This tablet is thinner than the tablet sample for which the infrared absorption spectrum of FIG. 7 was obtained, and the concentration of the sample in the mixed powder is doubled. In FIG. 8, a periodic signal based on interference like the R portion in FIG. 7 is small. Further, even if the tablet sample is made thin, a periodic signal due to interference is unlikely to be generated, so that the tablet thickness can be made thin, and accordingly, absorption by water contained in KBr can be made small. it can.

[0035]

The tablet sample molded by using the method and apparatus of the present invention does not have the upper surface and the lower surface parallel to each other, so that infrared interference is less likely to occur and the infrared absorption spectrum is caused by the interference. It is possible to improve the quality of infrared absorption spectrum by reducing absorption other than infrared absorption by the sample.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a conventional tablet molding machine.

FIG. 2 is a vertical sectional view showing a conventional micro tablet molding machine.

FIG. 3 is a vertical sectional view showing an embodiment in which the present invention is applied to the tablet molding machine of FIG.

FIG. 4 is a vertical sectional view showing an embodiment in which the present invention is applied to the tablet molding machine of FIG.

5A and 5B show an embodiment in the case where the present invention is molded using a frame 34, FIG. 5A is a perspective view showing a head portion thereof, and FIG. It is a vertical sectional view shown with a frame with which a body was filled up.

FIG. 6 is a diagram showing a tablet sample obtained by molding in Examples, and (A), (B), and (C) correspond to the Examples of FIGS. 3, 4, and 5, respectively. In each figure, the left side is a perspective view and the right side is a sectional view.

FIG. 7 is a diagram showing an infrared absorption spectrum using a conventional tablet sample.

FIG. 8 is a diagram showing an infrared absorption spectrum of the tablet sample shown in FIG. 6 (C) obtained by the present invention.

[Explanation of symbols]

 2 substrate 6 inner cylinder 8, 12a plate 10 sample powder 22 outer cylinder 24, 28a pressing plate 32 surface plate 36 metal substrate 38 lead annular frame 40 pressing device 42 head 44 convex portion 46 convex tip surface

Claims (6)

[Claims] 1. A method of pressurizing a mixed powder of a solid sample powder for infrared spectroscopy measurement and an infrared non-absorbent powder to form a tablet, wherein the mixed powder is pressed by a device for pressurizing the mixed powder. A tablet sample molding method, characterized in that the tablet sample molding method is characterized in that pressure molding is carried out by using those in which the surface in contact with the upper surface and the surface in contact with the lower surface are not parallel to each other. 2. The molding method according to claim 1, wherein one of the surface in contact with the upper surface and the surface in contact with the lower surface of the mixed powder is a flat surface and the other is a convex curved surface. 3. An annular frame body is placed on a flat surface of a surface plate, and a powder mixture of a solid sample powder and an infrared non-absorber powder is filled in the frame body and pressed from above the powder mixture. A molding apparatus for pressurizing and molding by a device, wherein a head surface of the pressing device which comes into contact with the mixed powder is a curved surface, and a tablet sample molding device. 4. The tablet sample molding device according to claim 3, wherein the head is detachable from the press device. 5. A cylindrical body is placed on a substrate, and a lower plate, a mixed powder of a solid sample powder and an infrared non-absorber powder, and an upper plate are placed in the hole of the cylindrical body in this order from the bottom, In a tablet molding apparatus in which pressure is applied by a pressing device from above the upper plate via a push rod, at least one of the upper plate and the lower plate is characterized in that a contact surface with the mixed powder is a curved surface. Tablet sample molding device. 6. An outer cylinder having a circular hole in the center, a lower push plate having a cylindrical convex portion which is inserted into the hole of the outer cylinder from the lower side, and a cylindrical convex portion which is inserted into the hole of the outer cylinder from the upper side. Micro pressurizing and compacting by filling the mixed powder of solid sample powder and infrared non-absorber powder between the tip surfaces of the convex parts of the upper and lower push plates inside the hole of the outer cylinder. In the tablet sample molding apparatus, the tip surface of the convex portion of at least one of the lower push plate and the upper push plate has a curved surface, and the micro tablet sample molding apparatus is characterized.