JPH0464047A - Apparatus for thermal analysis - Google Patents

Abstract

PURPOSE:To make it possible to set the speed of rise and fall of the temperature of a sample at a desired speed by varying the degree of thermal contact of a heat-conductive member with heating and cooling means. CONSTITUTION:The temperature of a sample A is raised and lowered by heating and cooling means 10b and 20, a thermal change thereof is observed and the thermal characteristic of this sample A is determined. On the occasion, a heat- conductive furnace 10 holding a heat-sensitive plate 12 on which the sample A is set is supported by a holding means 11 so that it can be moved vertically, and it is constructed of a substantially cylindrical soaking block 10a of a heat- conductive material and of the means 10b outside the block. An outward-facing flange part 13 and an erected wall 14 being vritually perpendicular thereto are formed on the outer periphery in the upper part of the block 10a. They come into contact with the means 20 and detach therefrom with the vertical movement of the furnace 10. Thereby the degree of thermal contact of the means 20 with a heat-conductive member interposed between the means 20 and the sample A can be varied. The degree of heat transmission between the means 10b and 20 and the sample A is varied and the speed of rise and fall of the temperature of the sample A can be set at a desired speed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention particularly relates to a thermal analysis device that allows the rate of temperature rise and fall of a sample in a low temperature range to be set to a desired rate.

[Conventional technology]

A differential thermal analyzer (DTA; Di
fferBntial Thermal^nalysi
s ), or differential scanning calorimeter (D S C; Di
fferential Scanning Color
imeter) etc. are known. All of these are widely used as extremely effective means for qualitatively or quantitatively observing the thermal properties of a sample, such as its transition temperature and heat of transition. In this type of thermal analysis, it is necessary to analyze the sample under various temperature conditions, such as under two-speed cooling within a short time or under gradual cooling. It is necessary to conduct experiments under different temperature conditions. By the way, temperature control in a temperature range higher than room temperature is relatively easily possible by controlling the current flowing through the heating furnace using well-known PID control means, but control near room temperature or in a negative temperature range is difficult. However, it is not possible to perform arbitrary control using only such electrical control. In this temperature range, this is done by cooling the sample with a refrigerant such as liquid nitrogen and controlling the current flowing through the heating furnace, but conventionally,
The thermal coupling between this refrigerant and the sample was always fixed in the best condition. This is because if the sample is always cooled at the maximum cooling capacity, then by controlling the current flowing through the heating furnace, it would be theoretically possible to control the temperature to any desired temperature within the range of the maximum cooling capacity. It is based on the assumption that

[Problem to be solved by the invention]

However, for example, when cooling a sample from room temperature to minus temperature, there is no problem if the temperature is lowered at a cooling rate close to the cooling rate when cooling with the maximum cooling capacity of the refrigerant, but if the sample is cooled with the maximum cooling capacity of this refrigerant, When the temperature is lowered at a rate significantly lower than the cooling rate when cooling, the following problem occurs. That is, in this case, a large amount of current is passed through the heating furnace to prevent the sample from being rapidly cooled by the refrigerant. For this reason, the refrigerant is heated and boiled, resulting in significant wasted consumption, and vibrations caused by the boiling may be transmitted to the sample, causing measurement noise and the like. In addition, since the refrigerant is consumed rapidly, it becomes necessary to replenish the refrigerant during the measurement, and the replenishment may cause a sudden change in the cooling state, which may generate noise. Furthermore, the influence of mechanical vibration during replenishment is also considered. This situation is the same when the temperature is raised from a low temperature. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a thermal analysis apparatus that has a simple configuration and is capable of setting the rate of temperature rise and fall of a sample to a desired rate, especially in a low temperature range.

[Means to solve the problem]

The present invention solves the above problems by having the following configuration. In a thermal analysis device that determines the thermal characteristics of the sample by raising and lowering the temperature of the sample using a heating/cooling means and observing the thermal changes, a heat exchanger that is interposed in the heat transfer path between the heating/cooling means and the sample is used. The thermally conductive member that is heated and
By changing the degree of thermal contact with the cooling means, the degree of heat transfer between the heating/cooling means and the sample can be changed to raise or lower the sample.
A configuration characterized in that the temperature decreasing rate can be set to a desired rate.

[For use]

According to the above configuration, by changing the degree of thermal contact between the heating/cooling means and the thermally conductive member interposed in the heat transfer path between the heating/cooling means and the sample, the heating/cooling means and Since the degree of heat transfer with the sample can be changed, the rate of temperature rise and fall of the sample can be set to a desired rate.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic sectional view of a thermal analysis apparatus according to an embodiment of the present invention. The thermal analyzer has a heat sensitive plate 1 on which sample A and standard sample B are placed.
2 and a refrigerant such as liquid nitrogen to cover the periphery of the heat transfer furnace 10.
and a cooling means 20 for cooling the samples A and B. The heat transfer furnace 10 is supported by a holding means 11 that holds the heat transfer furnace 10 movably up and down, and is a heat soaking block made of a heat conductive material (for example, silver) and having a substantially cylindrical shape. 10a and a heating means 10b provided on the outer periphery of the 9 heat soaking block 10a.
and an upright wall 14 that stands up from the outward flange portion 13 at a substantially right angle. Furthermore, a heat transfer ring 24 made of a thermally conductive material such as stainless steel, copper, or fluororesin is provided in the notch 22 formed by the upright wall 14 and the outward flange 13. It is detachably attached. When the heat transfer furnace 10 is moved upward, the upright wall 1
4 and the upper surface of the heat transfer ring 24 contact the upper inner surface 20a of the cooling means 20, and when the heat transfer furnace 10 is moved downward, the upper surface of the heat transfer ring 24 separates from the upper inner surface 20a of the cooling means 20. In FIG. 1, the heat transfer furnace 10 is shown moved downwardly away from the upper inner surface 20a of the cooling means 20). That is, this changes the degree of thermal contact between the cooling means 2o and the thermally conductive members (heat transfer ring 24 and soaking block 10a) interposed between the cooling means 2o and the sample A. . Note that by changing the material of the heat transfer ring 24 to a material with different thermal conductivity, the degree of heat transfer upon contact can be adjusted, and a more appropriate state can be selected. Furthermore, the degree of heat transfer can also be changed by changing the ring width of the heat transfer ring 24. Now, the inner circumferential surface side of the heat equalizing block 10a is divided into an upper space 17 and a lower space 18 via a partition wall 16 having through holes 15 for guiding thermocouples 30 and 31, which will be described later. 17, a step 17c is formed between the upper large diameter portion 17a and the lower small diameter portion 17b, and the heat sensitive plate 12 is placed on this step 17c. Note that the heat-sensitive plate 12 is held in the heat-uniforming block 10a with its outer circumferential portion being clamped by a fixing ring 18 placed on the step 17c. In this case, a lid 1 is placed on the top of the fixing ring 18.
9 can be covered. The heat-sensitive plate 12 is formed of a thermally conductive material in the shape of a disc, and has two protrusions 12a and 12b that protrude in a circular shape symmetrically about the center of the heat-sensitive plate 12, respectively. is now placed. In addition, a slit-like cut (not shown) is formed in the annular region from the outer periphery in the radial direction of the heat-sensitive plate 12 from the outer periphery toward the center, and furthermore, the heat-sensitive plate 12 has a slit-like cut (not shown) formed in the annular region from the outer periphery in the radial direction. The tapered portion 12c is tapered on one side, that is, on the lower side in the drawing.
The cross section is protruded so as to have a trapezoidal shape. Furthermore, thermocouples 30 are provided as temperature detection means at approximately the center of the back side of the protrusions 12a and 12b of the heat-sensitive plate 12, respectively.
and 31 are connected, and these thermocouples 30, 31 are led to the outside through a through hole 15 bored in the partition wall 16 of the heat equalizing block 1'0, and are connected to the control circuit 32. The control circuit 32 has a built-in arithmetic processing circuit, a temperature control circuit, etc., and detects the electromotive force of the thermocouple 30 and converts a signal corresponding to the temperature of the sample A.
The difference in electromotive force of 0.31 is taken, converted into a signal corresponding to this difference, and these are sent to the recording/display means 33 to record sample A.
and the temperature difference between sample A and standard sample B, and further controls the heating/cooling means 20 to control the temperature. Note that the thermocouple 30, 31 and the control circuit 32 constitute a temperature difference measuring device that measures the temperature difference between the sample A and the standard sample B. It is a graph showing a cooling curve obtained as a result of a temperature lowering experiment conducted using the above-mentioned apparatus using an indirect refrigerant (for example, alcohol, etc.) cooled by a fluorocarbon gas refrigerator. In FIG. 2, the vertical axis is temperature (unit: °C), the horizontal axis is time (unit: minutes), and the bottom of the curve is when the heat transfer ring 24 is moved upward to the top of the cooling means 20. Inner surface 20a
This is the case where the heat transfer ring 24 is brought into contact with the upper inner surface 2 of the cooling means 20 by moving the heat transfer member 10 downward.
This is the case when it is separated from 0a (the state shown in FIG. 1). The temperature decreasing rate (unit: °C/m1n) in each temperature range was read from each curve shown in FIG. 2 and compared and listed as follows. Temperature range Non-contact Contact (℃)
('C/min) ('C/min)15
0~100 21 37100~50
15 3050~0918 0~-5036 Moreover, FIG. 3 is a graph showing a cooling curve obtained as a result of a temperature reduction experiment conducted with the above-mentioned apparatus using liquid nitrogen (direct refrigerant) as the refrigerant supplied to the cooling means 20. It is. In FIG. 3, the vertical axis is temperature (unit: °C), the horizontal axis is time (unit: minutes), and the curve ■ moves the heat transfer class 10 upwards to move the heat transfer ring 24 to the upper part of the cooling means 20. Inner surface 20a
This is the case where the heat transfer ring 24 is brought into contact with the upper inner surface 2 of the cooling means 20 by moving the heat transfer member 10 downward.
This is the case when it is separated from 0a (the state shown in FIG. 1). From each curve shown in Figure 3, the temperature decreasing rate in units of "C/l1in" in each temperature range was read and compared and listed as follows.Temperature range Non-contact Contact ('C)
('C/min) ('C/min >1
50～100 31 58100～
50 24 -5250~0
18 380~-50 13
26-50~-100 8
15-ioo~-15034 As is clear from the above results, according to this example,
With an extremely simple configuration in which the heat transfer furnace 10 is brought into contact with the cooling means 20 or not, the temperature reduction rate can be made to be significantly different. In addition, in this embodiment, since a removable heat transfer ring 24 is provided as a thermally conductive member, it is possible to change the material or ring width to reduce the temperature drop when they are brought into contact. It is also possible to adjust the speed to a more appropriate speed. In the above embodiments, an example is given in which the heat conductive member is in contact or not in contact with the cooling means, but it goes without saying that a means capable of heating may be used instead of the cooling means. Effects of the Invention As detailed above, the present invention basically provides thermal contact between a thermally conductive member interposed in a heat transfer path between the heating/cooling means and the sample and the heating/cooling means. By changing the degree of heat transfer between the heating/cooling means and the sample, it is possible to set the rate of temperature rise and fall of the sample to a desired rate. This provides a thermal analysis device in which the rate of temperature rise and fall of a sample in a low temperature range can be set to a desired rate.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a thermal analysis apparatus according to an embodiment of the present invention, FIG. 2 is a graph showing a cooling curve using an indirect refrigerant, and FIG. 3 is a graph showing a cooling curve using liquid nitrogen. A... Sample, B... Standard sample, 10... Heat transfer furnace, 12... Heat sensitive plate, 13... Outward flange portion, 1
4... Standing wall, 20... Cooling means, 22... Notch, 24... Heat transfer ring, 30... Thermocouple. Entrance examination shaft 20 Cooling means 14 Standing wall Applicant Mac Science Co., Ltd. Figure 1

Claims (1)

[Scope of Claims] A thermal analysis apparatus for determining the thermal characteristics of the sample by raising and lowering the temperature of the sample using a heating/cooling means and observing the thermal changes, comprising: By changing the degree of thermal contact between the thermally conductive member interposed in the heat transfer path and the heating/cooling means, the degree of heat transfer between the heating/cooling means and the sample can be changed to raise or lower the temperature of the sample. A thermal analysis device characterized in that the speed can be set to a desired speed.