JPH09229884A - Thermal analysis apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily observe a sample by preventing dewing at a glass window or an optical system in a cooling medium tank. SOLUTION: A stop valve 13 of a gas feed pipe 14 is opened to send dry nitrogen gas. Air remaining in a cooling medium tank 4 is replaced with the dry nitrogen gas. Then, the stop valve 13 is closed and a liquid nitrogen tank 11 is pressurized by a pressurizing pump 12 to feed liquid nitrogen to the cooling medium tank 4 through an introduction pipe 10. While a sample is cooled to a predetermined temperature in this manner, a glass window 5 or an objective lens 6a is not fogged by dews because of the presence of only the liquid nitrogen and nitrogen gas. A heating furnace 1 is connected to a heater and temperatures of a reference sample and the measuring sample are measured by thermocouples 3a, 3b. Meanwhile, the measuring sample is observed through a microscope 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal analyzer, and more particularly to a thermal analyzer for observing a cooled sample with a microscope or the like.

[0002]

2. Description of the Related Art Among thermal analyzers, a differential scanning calorimeter (DSC) is an apparatus for measuring the enthalpy change of a substance and is widely used in the field of materials as well as in the field of pharmaceuticals. This DSC measures the endothermic and exothermic changes that occur in the sample when the sample and the reference substance are placed in a heating furnace and the temperature of the heating furnace is raised and lowered. Data based on the temperature difference between the sample and the reference substance is used. A DSC curve can be obtained by plotting with the time (temperature) as a parameter.

In such a DSC measurement, when a change in crystal form (phase transition), a change such as melting, decomposition or sublimation occurs in the sample during the temperature raising / lowering process, a peak appears in the DSC curve, and the endothermic peak causes the phase change. It is possible to determine the temperature at which transition, melting, etc. occur, and it is also possible to calculate the amount of heat absorption and heat generation from the peak area.

By the way, in the DSC measurement, when the DSC curve becomes complicated, it may be difficult to estimate the content of the change occurring in the sample. For example, sulfathiazole is a substance known to have three crystal polymorphs called Form (I), Form (II) and Form (III), and this sulfathiazole (powder) is used as a sample for DSC measurement. If the DSC curve obtained at the time of performing is the curve shown in FIG. 4, for example, the large peak T2 on the high temperature side of the two endothermic peaks is Form (I) [melting point: 201.0
It can be assumed that this is due to melting of [C], but the small endothermic peak T1 on the low temperature side is Form (III) [melting point: 173.
It is difficult to determine that it was due to melting at 6 ° C.

That is, when the powder of Form (III) is heated, it changes to Form (I), and the endothermic peak of its crystal transition appears at a temperature slightly lower than the melting point of Form (III). It is difficult to specify whether the endothermic peak T1 on the low temperature side corresponds to the melting point of Form (III) or the crystal transition based only on the DSC curve shown in FIG.

Therefore, an optical system such as a microscope is arranged so that the crystal state of the sample can be specified by observing the sample placed in the heating furnace, and the microscope is equipped with an image pickup means such as a CCD camera. The characteristics of the sample are analyzed by comparing the image data with the DSC curve.

As a method of cooling the sample to a low temperature region (-100 ° C. or lower) in such a DSC, a refrigerant tank partially having a sample observation window is used to surround the heating furnace, and the refrigerant tank is provided with liquid nitrogen or the like. The sample is cooled by supplying the above refrigerant.

[0008]

However, when the sample is cooled below room temperature, the glass window for observation by the microscope and the objective lens of the microscope are also cooled, and the water vapor in the air is
There is a problem that it becomes difficult to observe the sample due to dew condensation on the glass window or the lens.

The present invention was devised to solve the above-mentioned problems, and its purpose is to prevent dew condensation on a glass window or an optical system in a refrigerant tank, and to provide a sample even in a low temperature region. The object of the present invention is to provide a thermal analysis device capable of observing.

[0010]

Therefore, in the thermal analysis apparatus of the present invention, a sample is placed inside and a heating furnace for heating the sample is surrounded by a refrigerant tank having an observation window for the sample. ,
Prior to cooling the sample by introducing the refrigerant into the refrigerant tank,
The dry gas is supplied to the refrigerant tank, and the air in the refrigerant tank is replaced with the dry gas to prevent the dew condensation of water vapor in the observation means and the sample observation window.

The refrigerant introduced into the refrigerant tank is usually
Liquid nitrogen is used, and an inert gas such as nitrogen gas is used as the dry gas.

[0012]

1 is a diagram showing a schematic configuration of a differential scanning calorimeter according to the present invention.

Reference numeral 1 denotes a heating furnace. Inside the heating furnace 1, a reference sample cell 2a and a measurement sample cell 2b, and temperature measuring thermocouples 3a and 3b are provided.

Reference numeral 4 denotes a coolant tank, and a recess 4a surrounding the heating furnace 1 is formed on the bottom surface thereof. And the concave portion 4a
A glass window 5 for observing the sample on the heating furnace 1 is fitted to the horizontal portion of the so as to keep a sealed state with the inside of the coolant tank 4. Instead of the glass window 5, a quartz window having a light transmitting property and heat resistance may be used.

Reference numeral 6 denotes a microscope, which is attached to a support pipe 7 that moves up and down with respect to the refrigerant tank 4, and the support pipe 7 has an exhaust port 7a.
Are formed. Further, the coolant tank 4 is provided with a light source 6A for the sample to facilitate observation of the sample by the microscope 6. In this embodiment, the light source 6A is inserted and attached to the refrigerant tank, but the sliding portion 7b of the support tube 7 may be made of transparent acrylic resin and the light source 6A may be provided outside the refrigerant tank 4. In this case, the mounting structure of the light source 6A in the refrigerant tank 4 is simplified.

The microscope 6 is moved up and down by an elevating mechanism (not shown), and the objective lens 6a in the coolant tank 4 is moved up and down with respect to the sample for focusing. Since the support pipe 7 slides up and down the O-ring 8 provided in the refrigerant tank 4, the support tube 7 is kept in a sealed state with the refrigerant tank 4. Note that FIG.
As shown in FIG. 6, even if a part of the support tube 7 is expanded and contracted by the bellows 16 and attached to the refrigerant tank 4, the support tube 7 is sealed with the refrigerant tube 4 as in the present embodiment. Can be raised and lowered freely.

Further, a CCD camera 9 or the like is attached as an image pickup device to the eyepiece side 6b, and this image pickup information can be displayed on a CRT and processed by a computer (not shown).

On the other hand, an inlet 4b is formed in the refrigerant tank 4, and an inlet pipe 10 for supplying liquid nitrogen to the refrigerant tank 4 is attached to the inlet 4b. A liquid nitrogen tank 11 is attached to the other end 10a of the introduction pipe 10, and the introduction pipe 10 is driven by air pressure of a pressure pump 12 provided in the liquid nitrogen tank 11 or by heating a heater (not shown). Liquid nitrogen is fed into the refrigerant tank 4 through. Further, a gas supply pipe 14 is connected via a connector 15 in the middle of the introduction pipe 10 so that the dry nitrogen gas is fed into the refrigerant tank via the stop valve 13.

Next, the operation of the differential scanning calorimeter of FIG. 1 will be described. After placing the reference sample and the measurement sample in the reference sample cell 2a and the measurement sample cell 2b, respectively, and setting the heating furnace 1 in the concave portion 4a of the coolant tank 4, the surface of the measurement sample can be observed so that the surface of the microscope 6 can be observed. Focus the subject. And
First, in order to expel the water vapor contained in the air remaining in the refrigerant tank 4, the stop valve 13 provided in the gas supply pipe 14 is opened and the dry nitrogen gas is sent out. Then, the dry nitrogen gas passes through the connector 15 and the introduction pipe 10,
It is supplied into the refrigerant tank 4 through the inlet 4b. Eventually, the refrigerant tank 4 is filled with dry nitrogen gas, and a part of the dry nitrogen gas is discharged into the atmosphere through the exhaust port 7a. for a while,
By continuing to supply such dry nitrogen gas,
The residual air in the refrigerant tank 4 is also expelled to the atmosphere, so that the entire refrigerant tank 4 is replaced with dry nitrogen gas. Although dry nitrogen gas is used in this embodiment, other dry inert gas (He, Ar, etc.) may be used.

After all the residual air in the refrigerant tank 4 is replaced with the dry nitrogen gas, the stop valve 13 is closed, and then the pressurizing pump 12 is used to drive the liquid nitrogen tank 11 into the liquid nitrogen tank 11.
The inside of the refrigerant tank 4 is pressurized and liquid nitrogen is introduced through the introduction pipe 10.
Supply to After supplying a predetermined amount of liquid nitrogen, the operation of the pressure pump 12 is stopped and the sample is cooled to a predetermined temperature. Here, since only liquid nitrogen and nitrogen gas are present in the refrigerant tank 4, the glass window 5 and the objective lens are not fogged by dew condensation. Further, since the surface of the heating furnace 1 of the glass window 5 is in an atmosphere of high-purity inert gas (He, Ar, N2), dew condensation due to water vapor does not occur. Furthermore, by introducing a dry inert gas into the inside of the microscope 6, it is possible to prevent dew condensation on the lens inside the microscope 6.

Then, the heater of the heating furnace 1 is energized,
The reference sample and the measurement sample are heated to a predetermined temperature. At this time, the temperature information of the reference sample and the measurement sample is the thermocouple 3a,
3b, the DSC curve is obtained as in the conventional case. On the other hand, the change in the state of the measured sample is observed in real time through the microscope 6, and the change in the crystal structure of the measured sample can be traced while measuring the DSC curve. In addition, the change of the state of the sample is measured by the CCD camera 9.
Since it is imaged by a CRT or the like, it can be displayed on a CRT or the like, and by a process of a computer or the like, the DSC curve and the imaging information can be displayed on the CRT in an overlapping manner as shown in FIG. Various analyzes used are also possible. It can also be stored in a storage device.
Furthermore, in the present embodiment, an example of application to a differential scanning calorimeter has been described, but other thermal analysis devices can be used.

As modifications of the present invention, the following aspects are also included.

(1) A heating furnace for heating a sample placed inside, and a heating furnace surrounding the heating furnace, and having an observation window for the sample in a part thereof, by introducing a refrigerant, the sample in the heating furnace is removed. In a thermal analysis device comprising a cooling medium tank for cooling and an observing means for observing a sample through an observation window, means for replacing the cooling medium tank with a dry gas prior to supplying the cooling medium to the cooling medium tank,
A thermal analyzer provided in the introduction path of the refrigerant. That is, by providing the dry gas replacement means in the introduction path of the refrigerant, the number of pipes connected to the refrigerant tank is reduced, the structure is simplified, and the sealing performance of the refrigerant tank is improved.

[0024]

According to the thermal analyzer of the present invention, when a sample is cooled to room temperature or lower, air remaining in the refrigerant tank is replaced with dry nitrogen gas, and then cooling with liquid nitrogen is started. The water vapor inside does not condense on the glass window or the objective lens of the microscope, and the sample can be easily observed.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a differential scanning calorimeter according to the present invention.

FIG. 2 is a diagram showing a modified example of the differential scanning calorimeter according to the present invention.

FIG. 3 is a diagram showing a superimposed display of a DSC curve and imaging information on a CRT.

FIG. 4 is a diagram showing an example of a DSC curve.

[Explanation of symbols]

 1 ... Heating furnace 4 ... Refrigerant tank 4a ... Recess 5 ... Glass window 6 ... Microscope 6a ... Objective lens 10 ... Introduction Pipe 11 ・ ・ ・ ・ Liquid nitrogen tank 14 ・ ・ ・ ・ ・ ・ Gas supply pipe 15 ・ ・ ・ ・ Connector

Claims (1)

[Claims] 1. A heating furnace that heats a sample placed inside, and a heating furnace that surrounds the heating furnace and has a sample observation window in a part thereof to cool the sample in the heating furnace by introducing a refrigerant. In the thermal analysis device comprising a cooling medium tank for observing and a observing means for observing the sample through the observation window, a means for replacing the cooling medium tank with the dry gas is provided prior to supplying the cooling medium to the cooling medium tank. Characteristic thermal analysis device.