JP3381644B2 - Thermogravimeter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermogravimetric device for analyzing the moisture contained in a sample and the behavior of pyrolysis. [0002] Water in a sample is classified into various types according to the form of water molecules binding to the sample and assembling. For example, phenomenologically, water is classified into free water and antifreeze water. it can. The former vaporizes at a temperature of 100 ° C. or lower, which is the boiling point of water under normal pressure, whereas the latter has a relatively strong binding force and often has a vaporization temperature exceeding 100 ° C. Taking advantage of this, thermogravimetry (T
G) allows the amounts of both to be measured. A specific method of thermogravimetry is to use a thermogravimeter, which is also called a thermobalance equipped with a heating function and a weighing function, to store a sample in a sample pan and heat it at a constant heating rate. The change in the weight of the sample over time is measured. In such thermogravimetric measurement, a closed sample pan closed with a lid is used to prevent spontaneous evaporation from the sample before the measurement, but the pan is kept at normal pressure to keep the air pressure in the pan at normal pressure. A method of forming a pinhole in the lid of the helmet is adopted. In the thermogravimetric measurement described above, a plurality of samples are stored in advance in respective sample pans, and these are sequentially heated by an automatic setting mechanism (autosampler). There is a case where the weighing device is transported to the measuring unit and set. In such a case, if a pinhole is previously pierced in the lid of each sample pan in order to maintain the atmospheric pressure in the pan at normal pressure, spontaneous evaporation from the sample proceeds with time, although slightly.
There is a problem in that the later the measurement order, the more the accuracy of the quantification is lost. In particular, when the number of samples is relatively large, some samples have a standby time of over ten hours, and accurate measurement results cannot be obtained for such samples. The present invention has been made in view of such circumstances. Even if a large number of samples previously stored in a closed sample pan are prepared and automatically subjected to thermogravimetric measurement,
An object of the present invention is to provide a thermogravimetric device capable of performing accurate measurement on all samples. In order to achieve the above object, a thermogravimetric measuring apparatus of the present invention measures a weight change of a sample while heating the sample at a predetermined heating rate. An automatic setting mechanism that automatically transports a plurality of samples contained in individual sample pans in advance and sets them in the thermogravimetric measurement unit, and a pan cover for each sample pan being transported by the automatic setting mechanism. Is characterized by having a punching mechanism for forming a pinhole at a predetermined time before being set in the thermogravimetric measuring section. According to the present invention, the pinholes are not drilled in advance in the closed sample pan, but the individual sample pans are panned at a predetermined timing until the thermogravimetric measurement section is set by the automatic setting mechanism. By forming a pinhole in the lid, eliminating the difference in the amount of spontaneous evaporation from the sample due to the measurement order, or substantially eliminating spontaneous evaporation,
It seeks to achieve its intended purpose. That is, according to the structure of the present invention, the closed sample pan containing the sample is transported to the thermogravimetric measuring section sequentially.
The waiting time becomes longer as the order is set, and the later the order is, the formation of the pinhole for the pan lid is performed before the measurement is started, for example, immediately before the individual sample pans are set in the thermogravimetric measuring unit. Since the measurement is performed based on the timing, the difference in spontaneous evaporation caused by the measurement order can be eliminated. Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the configuration of the embodiment of the present invention. The apparatus includes a thermogravimetric device including a weight measuring mechanism 1 and a heating furnace unit 2, an autosampler (automatic setting mechanism) including a sample pan standby tray 3, a transport mechanism 4, and a punching mechanism 5, and each of these components. It comprises a control unit for controlling the mechanism and a data processing unit (both not shown). Each sample is provided with a metal pan body 61 and a metal pan cover 62 for hermetically closing the opening thereof, as shown in the cross-sectional views of FIGS. 2 (A) and 2 (B). The sample is placed on the sample pan standby tray 3 in a state of being previously sealed in the closed sample pan 6, and is sequentially conveyed by the conveying mechanism 4 onto the sample measuring table 11 of the weight measuring mechanism 1. The weight measuring mechanism 1 outputs weight information acting on the sample measuring table 11 every moment. The heating furnace unit 2 moves back and forth in the direction indicated by the arrow A in the figure by driving the heating furnace drive mechanism 21, is separated from the sample measuring table 11 when retracted as shown in FIG.
The sample pan 1 on the sample measuring table 11 can be heated at a constant heating rate with the sample 1 placed in the furnace. In this example, DTA (differential thermal analysis)
The weight measuring mechanism 1 employs a horizontal balance mechanism having a sample measuring table 11 and a reference sample table 12 on which a reference sample is placed. Reference numeral 12 denotes a load state with a constant weight, and the weight measuring mechanism 1 outputs only the weight information on the sample measuring table 11. The transport device 4 moves the transport grip 41, a grip opening / closing mechanism 42 for opening and closing the grip 41, and the transport grip 41 up and down as shown by an arrow B in the figure, and also as shown by an arrow C in the figure. A transport drive unit 43 for rotating the sample pan 6 is provided, and the sample pan 6 placed at a predetermined grip position on the sample pan standby tray 3 is gripped one by one and transferred onto the sample measuring table 11. The sample pan standby tray 3 is rotated by a predetermined angle by a rotation mechanism 31 to sequentially transport a plurality of sample pans 6 placed on the upper surface thereof to a transport grip 41.
Feed to the gripping position. A piercing mechanism 5 is arranged above the sample pan standby tray 3, and is provided with a piercing pin 51 and an arrow E in FIG.
As shown in the figure, it is constituted by a punching mechanism drive unit 52 that moves up and down. The punching mechanism 5 is configured to form a pinhole in the pan lid 62 of the sample pan 6 immediately before being fed to the holding position by the transport grip 41 on the sample pan standby tray 3. Next, an operation procedure of the above embodiment of the present invention at the time of automatic operation will be described. Prior to the start of the operation, each sample is placed on the sample pan standby tray 3 in a state of being sealed in the sample pan 6. When an automatic operation start command is given, first, the punching mechanism driving unit 52 operates to lower the punching pin 51 and punch a pinhole in the pan lid 62 of one sample pan 6 on the sample pan standby tray 3. Next, the sample pan standby tray 3 is rotated to feed the sample pan 6 having the pinhole to the gripping position by the transport grip 41, and the transport grip 41 is lowered to grip the sample pan 6 and measure the sample. It is transferred onto the table 11. After that, the heating furnace unit 2 moves forward, accommodates the sample on the sample measuring table 11 in the furnace, starts heating, and starts thermogravimetry. When the sample reaches a predetermined set temperature, the thermogravimetry is ended, and the heating operation of the heating furnace unit 2 is stopped. After the temperature in the furnace has decreased to a preset temperature, the heating furnace unit 2 retreats, and the sample pan 6 whose measurement has been completed by the operation of the transport grip 41 is transferred from the sample table 11 to a separately determined position. Then, one cycle is completed, and the process proceeds to the next cycle. In the next cycle, first, the punching mechanism driving unit 52 operates to lower the punching pin 51 to make a pinhole in the pan cover 62 of one sample pan 6, and then the sample pan standby tray 3 is removed. After rotation, the sample pan 6 is fed to the gripping position by the transport grip 41, transferred to the sample measuring table 11 by the sample grip 41, measured for thermogravimetry, transferred to the specified position after the measurement is completed, and then further To the cycle of As described above, according to the embodiment of the present invention, each sample pan 6 placed on the sample pan standby tray 3
Respectively, a pinhole is automatically formed in the pan lid 62 immediately before being transferred to the sample measuring table 11 which is a thermogravimetric measuring unit. Therefore, even if a large number of sample pans 6 are placed on the sample pan standby tray 3 and the automatic operation is started, the spontaneous evaporation of the samples in all the sample pans 6 is constant or substantially zero, which is caused by the measurement order. Accurate thermogravimetry can be performed for all samples without causing a difference in spontaneous evaporation. In the above embodiment, an example is shown in which the present invention is applied to an autosampler provided with a disk-shaped sample pan standby tray 3 and a swing arm type transfer grip 41. For example, a rectangular sample pan is used. Needless to say, the present invention can be applied to an autosampler having an arbitrary structure, such as a combination of a standby tray and an XY movable transfer mechanism. The weight measuring mechanism 1 is also a dedicated thermogravimetric device using, for example, a suspended (lower plate type) balance mechanism, in addition to the horizontal balance mechanism also serving as DTA as described above. Needless to say, this may be done. Further, the structure of the sample pan 6 is not limited to the one illustrated in FIG. 2, but may be any structure as long as the sample inside can be hermetically sealed. Of course. As described above, according to the present invention, an automatic setting mechanism for sequentially transporting and setting a plurality of sample pans containing a sample in advance to the thermogravimetric measuring unit is provided, and each sample pan is provided with an automatic setting mechanism. Since a pinhole is punched in the pan lid at a predetermined timing, such as immediately before being conveyed and set to the thermogravimetric measuring unit, the sample can be sealed in the sample pan in advance. Measurement can be performed by night unmanned operation, etc., not only can time be used effectively, but also the natural evaporation of the sample in the sample pan is minimized, and the natural evaporation of each sample Therefore, even if a large number of samples are automatically measured in sequence, no error occurs due to the measurement order, and the quantitativeness and reproducibility of the measurement are improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a configuration of an embodiment of the present invention. FIGS. 2A and 2B are cross-sectional views each showing a structural example of a sample pan 6 used in an embodiment of the present invention. [Description of Signs] 1 Weight measuring mechanism 11 Sample measuring table 2 Heating furnace unit 21 Heating furnace drive mechanism 3 Sample pan standby tray 31 Rotating mechanism 4 Transport mechanism 41 Transport grip 42 Grip opening / closing mechanism 43 Transport drive unit 5 Punching mechanism 51 Punching Pin 52 Drilling mechanism drive unit 6 Sample pan 60 Sample 61 Pan body 62 Pan lid

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-203957 (JP, A) JP-A-8-219970 (JP, A) JP-A-10-132767 (JP, A) JP-A-11- 72426 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 5/04

Claims (1)

(57) [Claim 1] In a thermogravimetric measuring device for measuring a change in weight of a sample while heating the sample at a predetermined heating rate, a plurality of samples previously stored in individual sample pans are measured. An automatic setting mechanism for automatically transporting and setting the thermogravimetric measurement unit sequentially, and a pan lid of each sample pan being transported by the automatic setting mechanism, at a predetermined time before being set in the thermogravimetric measurement unit. A thermogravimetric device, comprising a punching mechanism for forming a pinhole.