JPS60116101A - Moisture sensitive element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of origin] The present invention relates to a moisture sensitive element.

[Technical background of the invention and its problems] What about atmospheric humidity? A large number of methods have been proposed for humidity sensing elements (1st degree sensors) that emit OS.
And it has been put into practical use. In particular, in recent years Humidity I!, a method that can directly detect humidity electrically, has been introduced. ``A number of sensors have been proposed. Humidity sensors are attracting attention because they not only detect humidity but also control humidity easily and can be processed using electrical signals.

One of these is a humidity sensing element that uses a totally bent oxide as a humidity sensing element to read changes in electrical resistance due to adsorption of moisture in the atmosphere.

However, although humidity sensors using metal oxide as a humidity sensing element have excellent initial sensitivity, they all have the drawback of large changes in resistance after long-term use. In order to overcome this problem, a heater is attached to the humidity sensor made of a sintered body of gold Jr. There are also known devices that detect humidity after playback.

That is, by utilizing the thermal stability of the moisture-sensitive element made of a metal oxide and raising the temperature to a high temperature immediately before detecting humidity, the moisture-sensitive element is returned to its initial state to ensure reproducibility. However, with such a humidity sensor, continuous humidity detection is impossible because it is necessary to perform heating immediately before humidity detection. Moreover, a cumbersome structure including a heater and 41 circuits for controlling the heater is required, which is a major cause of high cost.

For this reason, ZnO8 has recently been used as a humidity sensor.
5-9,9Mo#%, LiZrVO40,5=10
A method using a moisture-sensitive composite consisting of a metal oxide having a composition of mol % and Cr20a + Fe20a O, 5 to 5 moh% has been developed ('FG Kaisho No. 56-4201). This humidity sensor remains stable for a long time under normal environmental conditions (0 to 40°C, 30 to 90% RH) without any regeneration treatment such as a heater.

In addition, it can be used with a low resistance value, and when used under product temperature conditions, such as a φ5 sensor with a diameter of 0, which is sufficient for humidity control in air conditioners and humidifiers,
There were cases in which it was not always possible to obtain optical temporal characteristics and P+ characteristics.

``Purpose of the Invention'' The present invention has an electrical resistance that can be used stably with almost no change in resistance even when used for a long time under Ichiwarn yarn production, and that is easy to use even in a humidity range of ψ 4 and α. The object of the present invention is to provide a moisture-sensitive element having a high value.

“Summary of Invention 9” Book B Mei? 1 Cr20B 21-73-E:k%,
At least one of ZnO and MfO 25 to 55
Mol%, Zr020.5-8.0 mole ratio, Li2O0,
This is a moisture-sensitive element made of a sintered body containing 5 to 80 mol 2O50.5 to 8.0 mol 2O50 as an essential component. Such a moisture sensing element has a resistance value of about 500 Ω at an ambient temperature of 25°C and a relative humidity of 30%, and about 10 Ω at the same temperature and 90% relative humidity, which is easy to use in a wide range of wet ash regions. Long-lasting and long-term under high temperature conditions of 85℃ [1]
Even if left unused, it shows little change over time and has high reliability.

As described above, the excellent characteristics of the wet element according to I of the present invention include Cr20B, ZnO (or ZnO and MpO, Mp
These Cr20a and ZnO are present at the grain boundaries of crystal grains of
It is presumed that this is due to the structure in which small amounts of components such as Zr0J Li2O and V2O5 are present.

The reason for limiting the blending ratio of Cr20B is that when the amount is less than 21 moles, the resistance value as a moisture-sensitive characteristic increases overall, but on the other hand, when the amount exceeds 73 moles, it is impossible to leave it at high temperature. This is because the change over time becomes large.

The reason for limiting the blending ratio of at least 1@ of the above ZnO, Ml, and O is that if the amount is less than 25 mol, the change over time when left at high temperatures will be large, but on the other hand, the benshi did not use 55 mol. This is because, if it exceeds %'M<, the resistance value for mixed species becomes higher overall.

In this case, ZnO and Myo can exhibit the same effect even if they are used alone or in combination.

The reason for limiting the blending ratio of zrO2 is to
．． This is because if the amount is less than 5 molar ratio, the change in nail time when left at high temperature becomes severe, but if the amount exceeds 8.0 molar ratio, W fix will decrease on the low humidity side.

The combination of the above LizO and VzO5 is limited to 1.
yl L/ 7j j, lj! The reason is Lis+O, V2
When O5's plan is made into I-- by Tani 05 mole Amemi, fd
The resistance value as i'L special property is generally high, but J:: of Li2O and V20Fl are each 8
．． This is because, if the value exceeds 0 molar ratio, the change over time after one shot of high-temperature exposure becomes less pronounced.

[Example of Yuko Yuko] Next, the present invention will be explained in detail.

Example 1 First, was it used as a starting material? Zinc oxide.

Fine powders of zirconium oxide, lithium carbonate, and vanadium oxide were used. These starting materials were converted into CrzOa.

The molar ratio of ZnO, ZrO2, Li2O, VgO5 is 45
%, 45%, 4%, '3 (fo, 3%), and then wet-mixed in a pot mill for 24 hours.Subsequently, this mixture was dried at 120 °C for 12 hours. After that, it was calcined at 800℃.Subsequently, the calcined product was wet-milled for 24 hours at the same time in a pot mill, and then crushed at 120℃ for 1 hour.
A raw material powder was prepared by drying at a 2:1'4'' angle.

Next, a double coat of polyvinyl alcohol (binder) was added to the raw material powder, granulated using a Leica machine, and the granulated product was press-molded at 500 Ky/cJ to give a diameter of 8 r.
A disk-shaped compact with a thickness of about 21 mm was made.

Next, this molded body was heated at 1300' COgL degree for 2
After completing the 1/11 plan, the two king sides of the force-strapped body were polished to a thickness of 1 inch. Continuing, this sintered body (moisture-sensitive leaf)
A paste of ruthenium chloride (C4ψ) was printed on a screen on both main surfaces of the substrate, and then baked at about 700° C. to form an electric body, thereby producing a moisture-sensitive element having the structure shown in Figure 51.

In addition, 1 in FIG. 1 is a sensing element body, and 2 is an electrode.

Therefore, for the humidity sensing element of Example 1, the ambient temperature was
When the resistance value (moisture sensitivity characteristics) was examined at a constant temperature of 5 DEG C. and the relative humidity was varied from 30 to 90 degrees, the characteristic diagram shown in FIG. 2 was obtained. As is clear from FIG. 2, the humidity sensing element of the present invention has a temperature of 530°C at an ambient temperature of 25°C and a relative humidity of 30%.
It can be seen that the resistance value is 14Ω at the same temperature and 90% relative humidity, which is a low resistance value that is extremely easy to use in a wide range of humidity.

In addition, the resistance value (/ l
<Q fMi characteristics)? , I obtained the characteristic diagram shown in FIG. As is clear from FIG. 3, the characteristics of the moisture sensitive element of the present invention hardly change after being left at high temperatures, and it has stable characteristics over time.

Examples 2 to 7 Six types of humidity sensing elements having sintered bodies (humidity sensing elements) having the compositions shown in Table 1 below were manufactured in the same manner as in Example 1 above.

Therefore, the humidity sensing elements of Examples 2 to 7 were tested at an ambient temperature of 25°C, a relative humidity of 30%, a resistance value of 90% (initial moisture sensitivity characteristics), and after being left in a constant temperature bath at 85°C for 1000 hours. The resistance value (humidity sensitivity characteristics after being left at high temperature) was investigated at an ambient temperature of 25° C. and a relative humidity of 30% and 90%. The results are also listed in Table 1. In addition, in the first category, reference examples 1 to 2 include moisture sensitive elements having moisture sensitive elements that are out of the composition range of the present invention.
As is clear from Table 1 above, the humidity sensing element of the present invention has a resistance value that is extremely easy to use in a wide range of humidity, and has stable aging characteristics even under high temperature conditions. Recognize. In contrast, the moisture-sensitive elements (Reference Examples 1 to 6) made of sintered bodies outside the composition range of the present invention have resistance values that are easy to use in the wide range of humidity and stable aging under high temperature conditions. does not satisfy both characteristics.

Example 8 First, chromium oxide, magnesium carbonate,
Fine powders of zirconium oxide, lithium carbonate, and vanadium oxide were used. These starting materials are Cr2O5, Mho
, ZrO2, LiBo, V2O5 molar ratio is 45
%, 45%, 491t, 3%, 39g, and then mixed in a pot mill for 24 hours.

Subsequently, this mixture was dried at 120'C for 12 hours and then calcined at sooC. Subsequently, the calcined product was ground in a pot mill for 24 hours, and then dried at 120° C. for 12 hours to prepare a raw material.

Next, using the above raw material powder, a moisture sensing element having the same structure as that shown in FIG. 1 was manufactured by the same method as in Example 1.
When the resistance value (moisture sensitivity characteristic) was examined when the relative humidity K was varied from 30 to 90 degrees at a constant temperature of 5 DEG C., the characteristic diagram shown in FIG. 4 was obtained. As is clear from this FIG.
It can be seen that it exhibits a low resistance value that is extremely easy to use in a wide range of humidity, such as Ω at the same temperature and 90% relative humidity.

In addition, the resistance value (humidity sensitivity characteristics) when the humidity sensing element of Example 8 was exposed to a constant temperature bath at a temperature of 85°C for 1000 hours, and the relative humidity was changed from 30 to 90% at an ambient temperature of 25°C.
After investigating, the characteristic diagram shown in Figure 5 is 10. As is clear from FIG. 5, the moisture-sensing element of the present invention shows almost no change in its moisture-sensing characteristics after being left at high temperatures, indicating that it has stable characteristics over time.

Examples 9 to 14 Six types of humidity sensing elements each having a sintered body (moisture sensing element) having the composition shown in Table 2 below were manufactured in the same manner as in Example 1.

Therefore, the humidity sensing elements of Examples 9 to 14 were tested at an ambient temperature of 25°C, a relative humidity of 30%, a resistance value of 90% (initial humidity sensitive characteristics), and after being left in a constant temperature bath at 85°C for 1000 hours. The resistance value (humidity sensitivity characteristics after being left at high temperature) of 90% of the temperature was investigated at an ambient temperature of 25° C. and a relative humidity of 30%. The results are also listed in Table 2.

In addition, in Table 2, reference examples 7 to 12 also include moisture-sensitive elements having moisture-sensitive elements outside the composition range of the present invention.

As is clear from Table 2 above, the humidity sensing element of the present invention has a resistance value that is extremely easy to use in a wide range of humidity, and has stable aging characteristics even under high temperature conditions. On the other hand, the humidity sensing elements (Reference Examples 7 to 12) made of sintered bodies outside the composition range of the present invention have resistance values that are easy to use in the wide range of humidity and stable aging characteristics under high temperature conditions. Don't satisfy both.

Examples 15 to 19 Six types of I moisture elements each having a sintered body (moisture sensitive element) having a composition shown in Table 3 below were manufactured in the same manner as in Example 1 above.

Therefore, the humidity sensing elements of Examples 15 to 19 (two of them were placed at an ambient temperature of 25°C, a relative humidity of 30%, and a resistance value of 90% (initial moisture sensitivity characteristics)) and were placed in a constant temperature bath at ζ285°C for 1000 hours. Ambient temperature 25℃, relative humidity 30%, 9
The resistance value (moisture sensitivity characteristics after being left at high temperature) at 0% was investigated. The results are also listed in Table 3.

In addition, in Table 3, reference examples 13 and 14 are also listed as reference examples 13 to 14, which refer to moisture-sensitive elements having moisture-sensitive elements outside the composition range of the present invention.

As is clear from Table 3 above, the humidity sensing element of the present invention has a resistance value that is extremely easy to use in a wide range of humidity, and has stable aging characteristics even under high temperature conditions. In contrast, the humidity sensing elements (Reference Examples 13 to 14) made of sintered bodies outside the composition range of the present invention have resistance values that are easy to use in the wide range of humidity and stable aging characteristics under high temperature conditions. Don't satisfy both.

[Effects of the Invention] As described in detail above, according to the present invention, an electrical resistance value (humidity sensitive 9'1' note) which is easy to use even in a wide range of 1i1 humidity can be achieved, and moreover, it can be maintained for a long time under high temperature conditions 1. It is possible to provide a highly reliable moisture sensing element that can be used stably with almost no change in resistance even when used.

, 4. Brief explanation of the drawings No. 1N shows one form of the moisture-sensitive element of the unexploded sword;
FIG. 2 is a diagram showing the initial moisture sensitivity characteristics of the humidity sensing element of Example 1 (2), FIG. 3 is a diagram showing the moisture sensitivity characteristics of the humidity sensing element of Example 1 after being left at high temperatures, and This figure is a diagram showing the initial humidity sensitivity characteristics of the humidity sensing element of Example 8, and FIG. 5 is a diagram showing the humidity sensitivity characteristics of the humidity sensing element of Example 8 after being left at high temperatures.

1...Sintered body (moisture sensitive element) 2...Electrode agent Patent attorney Nori Chika Isuke (and 1 other person) m1 figure 2 figure 3 figure 30,! , D70? D30 AD 70'?
D Aiyu・↑1Watari tz) JaJ↑Eiyu<'t) Figure 4

Claims (1)

[Claims] Cr20B 21-73 moi% 1Zoo and Mp
At least one of O 25-55 mol,%; Zr0Z 0.5-g, Q mol% V2O50.5-8. Orno1%; Li 20 0
．． 5 = 8. A moisture sensing element comprising a sintered body containing On1OJ%.