JP3267220B2 - Thermal analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal analyzer such as a differential scanning calorimeter (DSC).

[0002]

2. Description of the Related Art A differential scanning calorimeter is a device for measuring a change in enthalpy of a substance, and is widely used in fields such as a heat resistance test of a material, a screening test of a drug, and a study of storage conditions of food. This differential scanning calorimeter measures the temperature difference caused by the change in heat absorption and heat generated in the sample when the temperature of the heat sink is raised and lowered by placing the sample and the reference material (reference sample) at symmetric positions in the heat sink. The DSC curve can be obtained by plotting the heat flow (heat flow rate) data calculated from the temperature difference using the sample temperature (or time) as a parameter.

[0003]

By the way, in the differential scanning calorimeter, the heat sink for accommodating the sample is:
In order to suppress heat dissipation, a quasi-isolated structure insulated to a certain extent from the outside world is employed. Therefore, even if the energy supply of the heating means is reduced, the temperature of the heat sink does not follow this. As a result, sufficient cooling performance cannot be obtained, for example, the stabilization from the temperature rise / fall to the isothermal holding state deteriorates, and the system does not follow agile temperature control such as high-speed cooling.

In order to solve this problem, a cooling system for supplying a large amount of cooling gas to the vicinity of the heat sink and forcibly exchanging heat has been added. However, in a differential scanning calorimeter, the basic skeleton of the device is different. Despite being a quasi-isolated system, it is necessary to promote heat exchange with the outside world during cooling, so there are conflicting aspects. The cooling method has a problem of poor thermal efficiency. Further, since the heat sink is exposed to a large flow of low-temperature gas, there is a problem that noise is easily generated in measurement data (temperature and differential heat flow).

On the other hand, differential scanning calorimeters have been actively used in the field of polymers in recent years.

For a polymer, an apparatus capable of easily cooling a heat sink to a low temperature is required for pretreatment for raising and lowering the temperature to remove the influence of a heat history and for measuring glass transition in a low temperature range. In this case, it is convenient to use liquid nitrogen for low-temperature cooling, but it is not economical to always use liquid nitrogen (even at times other than low-temperature measurement). As a countermeasure,
A cooling system in which the cooling fin is cooled by an air-cooling fan when liquid nitrogen is not used and liquid nitrogen is used when necessary is conceivable. However, in this cooling system, the heat conduction path by the radiation fins and the heat conduction path by the liquid nitrogen must be connected. (Condensation) may occur, causing trouble such as measurement failure.

[0007] The present invention has been made in view of such circumstances, and provides a thermal analysis apparatus having both good settling property when shifting from a temperature rising and falling state to an isothermal holding state and good temperature followability in high-speed cooling control. With the goal. In addition, it is possible to prevent dew condensation on the radiating fins by adding a cooling system including a plurality of cooling units such as a cooling unit using liquid nitrogen and a cooling unit having a radiating fin and an air cooling fan. It is intended to provide a thermal analyzer having a simple structure.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, when a sample is placed in a heat sink and the temperature of the heat sink is raised or lowered, the sample is generated. In a thermal analyzer that measures changes (temperature changes or changes in heat absorption and heat generation, etc.) for high temperatures (generally above room temperature) thermally connected to a heat sink via a heat transfer plate
A cooling means, a cooling means for low temperature (generally below room temperature), and a temperature sensor for measuring the temperature of the cooling means for high temperature, and when the detected value of this temperature sensor exceeds a set value, only the cooling means for high temperature is used. It is characterized in that only the low-temperature cooling means is activated when the temperature detection value falls below the set value.

According to the thermal analyzer of the first aspect of the present invention, the heat of the heat sink is constantly and forcibly taken away by the heat conduction to the cooling means, so that the heat supply from the heating means is reduced. Following this, the rate of change of the heat sink temperature changes immediately.

In the measurement at a high temperature, for example, only the high-temperature cooling means having a simple structure using an air-cooling system without using a refrigerant is operated, and when the temperature of the high-temperature cooling means falls below a preset temperature, the operation is started. Is stopped and cooled only by the low-temperature cooling means, so that cooling from a high temperature to a low temperature can be performed economically.

According to a second aspect of the present invention, there is provided a method for measuring a change (such as a change in temperature or a change in heat absorption or heat generation) that occurs in a sample when the temperature of the heat sink is increased or decreased in a state where the sample is placed in the heat sink. In the analyzer, a plurality of cooling means for cooling the heat sink are provided, one of which is a high-temperature cooling means including a radiating fin and an air-cooling fan, and the air-cooling fan is provided by a temperature sensor provided on the radiating fin. The air-cooling fan is configured to operate when the detected value exceeds the set value, and to stop operation when the detected value becomes equal to or less than the set value. The shutter is opened by the wind pressure of the fan, closed when the fan stops, and provided with a shutter that seals the periphery of the radiation fin.

According to the thermal analyzer of the second aspect of the present invention, at the time of high temperature measurement without using a refrigerant such as liquid nitrogen, the air cooling fan operates, and the wind opens the shutter to cool the radiation fins. .

On the other hand, when low-temperature measurement is performed using a refrigerant such as liquid nitrogen, the operation of the air-cooling fan is stopped and the shutter is closed when the temperature of the radiation fin becomes lower than a predetermined temperature due to the cold heat. As a result, the periphery of the radiation fin is in a semi-sealed state. As a result, the supply of air to the radiating fins is shut off, and the frost generated on the radiating fins is only the condensation of moisture contained in the air existing in the semi-enclosed space.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment according to the first aspect of the present invention.

The thermal analyzer shown in FIG. 1 is a differential scanning calorimeter, which comprises a heat sink 1 and a heater 2 for controlling its temperature.
It has. In the heat sink 1, sample pans 1a and 1b for placing a sample and a reference sample, a DSC sensor (not shown) and the like are accommodated.

The heat sink 1 and the heater 2 are provided at one end of a heat transfer plate 3 made of a metal having good heat conductivity (silver, copper, etc.). The cooling means 4 and the low-temperature cooling means 5 are provided side by side.

The high-temperature cooling means 4 comprises a radiating fin 4a and two air-cooling fans 4b arranged on the upstream and downstream sides, respectively, and a temperature sensor 6 is mounted on the radiating fin 4a. . The detected value of the temperature sensor 6 is guided to a control circuit 7 described later.

The low-temperature cooling means 5 comprises a refrigerant tank 5a for storing liquid nitrogen L and a refrigerant supply system 5b for supplying liquid nitrogen L into the tank.

The control circuit 7 detects a value detected by the temperature sensor 6 and a preset value (for example, room temperature; 20 ° C.).
If the detected value exceeds the set value, the air-cooling fan 4b of the high-temperature cooling means 4 is driven. The operation of the refrigerant supply system 5b of the low-temperature cooling means 5 starts the supply of the refrigerant, and when the detected value of the temperature sensor 6 becomes equal to or less than the set value, the driving of the air cooling fan 4b is stopped.

According to the embodiment shown in FIG. 1, the heat of the heat sink 1 is transferred to the high-temperature cooling means 4 or the low-temperature cooling means 5 by heat conduction through the heat transfer plate 3,
Since the heat sink 1 is constantly cooled, if the heat supply from the heater 2 is reduced, the rate of change of the heat sink temperature immediately changes.

When measuring high temperature without using liquid nitrogen, only the high-temperature cooling means 4 operates to cool the heat sink 1 efficiently. When liquid nitrogen is used, the cooling fins of the high-temperature cooling means 4 are cooled by the cold heat. The operation of the high-temperature cooling means 4 is stopped when the temperature of the high-temperature cooling means 4 is lower than the set value.
Are not operated at the same time, and cooling from high temperature to low temperature can be performed economically.

In the thermal analyzer according to the first aspect of the present invention, the cooling means for high temperature is not particularly limited. In addition to the above-described air cooling system, for example, a device using a Peltier element,
Alternatively, a cooling means of a water cooling system may be applied. Also,
The supply of liquid nitrogen to the low-temperature cooling means may be performed manually without using a special refrigerant supply system. Further, in addition to the method using liquid nitrogen, an electric refrigerator or the like that circulates alternative Freon may be applied.

FIGS. 2 and 3 are block diagrams of an embodiment according to the second aspect of the present invention. The differential scanning calorimeter shown in FIGS. 2 and 3 is similar to the embodiment shown in FIG.
A heat sink 1 and a heater 2 for controlling the temperature thereof are provided at one end of a heat transfer plate 3, and a cooling means 4 for high temperature and a cooling means 5 for low temperature are provided at the other end of the heat transfer plate 3.

The present embodiment is characterized in that two shutters 11 are installed in an air passage 9 formed by the heat transfer plate 3 and the duct 8 and the like.

One of the shutters 11 is disposed between the upstream air-cooling fan 4b and the radiation fin 4a, and the other shutter 11 is disposed between the downstream air-cooling fan 4b and the radiation fin 4a.
a.

Each of the shutters 11 has a plurality of movable flaps 11a... 11 that can swing about a shaft 11b.
a. These movable flaps 11a
.. 11a is when the air cooling fan 4b is operating,
The air-cooling fan 4b is opened obliquely by the wind pressure (FIG. 2), and is closed by its own weight when the operation of the air-cooling fan 4b is stopped and the air-cooling fan 4b is in a windless state (FIG. 3).

Also in this embodiment, the temperature sensor 6 is provided on the radiating fin 4a of the high-temperature cooling means 4, and the detected value of the temperature sensor 6 is used as the air cooling fan 4b.
To the drive circuit 10.

The drive circuit 10 activates the air-cooling fan 4b when the detected value of the temperature sensor 6 exceeds the set value, and stops the operation of the air-cooled fan 4b when the detected value falls below the set value. It is configured as follows.

The set value used in this embodiment may be a value that can detect that the cold heat of the liquid nitrogen has been transmitted to the radiation fins 4a, and may be a value corresponding to room temperature (20 ° C.). , Or a value smaller than that.

In the embodiment shown in FIGS. 2 and 3, when the liquid nitrogen L is not used, since the detection value of the temperature sensor 6 exceeds the set value, the air-cooling fan 4b operates, and the As a result, the shutter 11 is pushed and opened (FIG. 2), and the radiation fins 4a are air-cooled.

Next, the liquid nitrogen L is supplied to the refrigerant tank 5a of the low-temperature cooling means 5 by the operation of the refrigerant supply system (see FIG. 1) or the like, and the cold heat is supplied to the temperature sensor 6 of the radiation fin 4a.
, The operation of the air-cooling fan 4b is stopped, the air flow path 9 is in a calm state, and the shutter 11 is closed. By closing the shutter, the peripheral portion of the radiation fin 4a is maintained in a semi-sealed state by the heat transfer plate 3, the duct 8, and the shutter 11, and in this state, the moisture contained in the air in the sealed space is removed by the radiation fin 4a. However, since the supply of the moist air to the radiating fins 4a is shut off, a large amount of frost does not occur on the radiating fins 4a.

The shutter used in the thermal analyzer according to the second aspect of the present invention is not particularly limited as long as it has a structure that can be opened and closed by wind pressure to maintain a semi-closed state when closed. In addition to a shutter using a movable swingable flap, for example, a shutter having a structure incorporating a flexible blade plate deformed by wind pressure of a fan may be used.

Here, in each of the above embodiments, an example is shown in which the present invention is applied to a differential scanning calorimeter, but the present invention is not limited to this, and a differential thermal analyzer, a thermogravimetric Alternatively, the present invention can be applied to other thermal analyzers such as a thermomechanical analyzer.

[0034]

As described above, according to the first aspect of the present invention, since the heat sink is forcibly cooled by heat conduction, the settability at the time of transition from the temperature rising / falling state to the isothermal holding state is improved. At the same time, the temperature follow-up performance in the case of fast temperature control, for example, when the temperature is periodically changed is improved. Further, since the cooling is performed by heat conduction, the heat exchange efficiency is good and the consumption of the refrigerant is small. In addition, since the temperature gradient around the heat sink is smaller and more stable than in the gas spray cooling system, noise is reduced.

In the thermal analyzer according to the first aspect of the present invention, even when only the measurement at room temperature or higher is performed, the above-mentioned effects can be achieved without supplying the refrigerant, and the natural cooling rate is increased. There is also an advantage that the lower limit temperature of the high-speed cooling control decreases.

According to the second aspect of the present invention, there is provided a cooling system in which a heat sink is cooled by air cooling of a radiation fin when a refrigerant such as liquid nitrogen is not used, and a refrigerant such as liquid nitrogen is used for measurement at a low temperature. It is possible to provide an apparatus having a cooling system in which a large amount of frost is prevented from being generated on the radiation fins.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the invention described in claim 1;

FIG. 2 is a configuration diagram of an embodiment of the invention described in claim 2;

FIG. 3 is a configuration diagram of the same embodiment.

FIG. 4 is a perspective view of a movable flap used in the embodiment of the invention described in claim 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat sink 2 Heater 3 Heat transfer plate 4 High temperature cooling means 4a Radiating fin 4b Air cooling fan 5 Low temperature cooling means 5a Refrigerant tank 5b Refrigerant supply system L Liquid nitrogen 6 Temperature sensor 7 Control circuit 8 Duct 9 Air flow path 10 Drive circuit 11 Shutter 11a Movable flap

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-244003 (JP, A) JP-A-4-60452 (JP, A) JP-A-53-142290 (JP, A) 99655 (JP, U) Japanese Utility Model Hei 6-78857 (JP, U) JP50-19960 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 25/20 G01N 25 / 00

Claims (2)

(57) [Claims] 1. A thermal analyzer for measuring a change occurring in a sample when the temperature of the heat sink is increased or decreased while a sample is placed in the heat sink, wherein the heat sink is thermally connected to the heat sink via a heat transfer plate. A high-temperature and low-temperature cooling means connected thereto and a temperature sensor for measuring the temperature of the high-temperature cooling means are provided, and when the detected value of this temperature sensor exceeds a set value, only the high-temperature cooling means operates. A thermal analyzer configured to operate only the low-temperature cooling means when the detected temperature value becomes equal to or less than a set value. 2. A thermal analyzer for measuring a change occurring in a sample when the temperature of the heat sink is raised and lowered in a state where the sample is placed in the heat sink, wherein a plurality of cooling means for cooling the heat sink are provided. One of the cooling means is a high-temperature cooling means including a radiating fin and an air-cooling fan, and the air-cooling fan is activated when a detected value of a temperature sensor provided on the radiating fin exceeds a set value. While the operation is configured to stop when the value becomes equal to or less than the value, the air flow path formed for the radiation fins is opened by the wind pressure of the air-cooling fan, and closed when the fan stops, A thermal analyzer, wherein a mechanism for sealing a peripheral portion of the radiation fin is provided.