JPS6344703A - Moisture-sensitive device compound - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a moisture-sensitive element composition that detects relative humidity as a change in electrical resistance.

[Conventional technology]

Conventionally, moisture-sensitive element compositions include: ■ those using electrolyte salts such as lithium chloride, ■ those using organic polymer films such as polyamide and polyethylene, and ■ those using metal semiconductors such as Se and Ge. ■Metal oxide sintered bodies such as titanium oxide, aluminum oxide, and aluminum oxide are known. Among these, those using metal oxide sintered bodies have the advantage of being chemically and physically stable compared to other Fl, 4-element compositions such as organic polymer films, and are suitable for moisture-sensitive element compositions. It is said to be powerful.

However, metal oxide sintered bodies generally have high specific resistance values that are outside the practical resistance range, and the resistance of the moisture-sensitive element composition increases rapidly especially in low humidity regions, making measurements in low humidity regions difficult. Difficult, ■ High temperature dependence and requires temperature compensation, ■ Hysteresis in moisture-sensing characteristics when absorbing and desorbing moisture, ■ Weakness against thermal shock and deterioration of moisture-sensing characteristics.
(2) Hydroxide stains adhere to the surface of the metal oxide sintered body, deteriorating its moisture sensitivity, so it has drawbacks such as the need for periodic heating and cleaning as a countermeasure.

Therefore, it is desired to develop a highly reliable moisture-sensitive element composition.

[Problem that the invention seeks to solve]

The present invention has: 1) a low specific resistance value within a practical resistance value range, 2) extremely low temperature dependence and no need for temperature compensation, and 2) almost no hysteresis in the moisture sensitivity characteristics during moisture adsorption and desorption. The object of the present invention is to provide a highly reliable moisture-sensitive element composition that is free from heat, 1) resistant to thermal shock, and 2) does not require special heating cleaning.

Furthermore, the present invention aims to provide a moisture-sensitive element composition that can be particularly well measured in a low temperature range of 40X or less.

[Means for solving problems]

That is, the present invention provides a moisture-sensitive element composition formed by sintering a metal oxide, in which a chalcogen oxoacid salt represented by the general formula (1) is blended with the metal oxide, and the composition is sintered in the presence of molecular oxygen. Moisture-sensitive element compositions A, B, 0□ (1
) (In the formula, 8 represents an alkali metal or alkaline earth metal, B represents a sulfur, selenium or tellurium atom, 0 represents an oxygen atom, χ represents a number from 1 to 2, y represents a number from 1 to 5, and z represents a number from 2 to 7. ).

In the present invention, the metal oxide may be any metal oxide as long as it itself has moisture-sensitive properties, and those conventionally known as active ingredients of moisture-sensitive element compositions are suitably used. For example, Mg
O, TiO2, ZrO,, Nbz05, TaO, Ta2
09,CrzOi,Mo0=,WO3,MnO,,M
nz04, FeO, FezO3, CoO5CozO=,
NiO, N1zOx, N1z04, ZnO5A120
*, Gaz03, InzO3, TIzOi, 5iO
z, GeO2, SnO, 5nOz, PbO, 5bzOz
, BizO:+ and other oxides, Mg2Fe
z0n, ZnFezOn, MgAIzO4, MgCr
20i, ZnCrz03 (above, spine/L/), 3
Examples include composite oxides such as Alz(h 2SiOz (mullite). Among these, TiO2
, r -AlzOff, ZnO, MgO, Zr0z, N
iO, MgAIz04, etc. are particularly preferred. The metal oxide may be a product obtained by thermally decomposing a metal salt, metal hydroxide, alkoxide, or the like.

The chalcogen oxoacid salt is represented by the following general formula (I).

A, B, O, (1) (wherein A is an alkali metal, alkaline earth metal, B is a sulfur, selenium or tellurium atom, 0 is an oxygen atom, X is 1-2, y is 1-5, z represents a number from 2 to 7) Examples of sulfur oxo-acid salts include sulfoxylates, sulfites, bisulfites (metabisulfites, dithionites, disulfates (pyrosulfates) ), thiosulfate, and thionate.

Specific examples of selenium oxoacid salts include selenite and selenate, and specific examples of tellurium oxoacid salts include tellurite and tellurate.

The amount of chalcogen oxo acid salt is usually 0.01-9 based on the sum of metal oxide and chalcogen oxo acid salt.
The content is 9.99 mol%, preferably 0.1 to 99.9 mol%, and particularly preferably 50 mol% or less in consideration of economic efficiency and properties.

After mixing each component within the above composition range and applying appropriate sintering conditions, the sintered body obtained has extremely good moisture sensitivity characteristics compared to the metal oxide alone.

The moisture-sensitive element composition of the present invention can be manufactured as follows using ordinary porcelain manufacturing techniques.

First, a predetermined amount of each component is weighed, and then these are sufficiently mixed in a ball mill, vibration mill, etc. by a dry method or a wet method using a mixed solvent such as water and methyl alcohol. Thereafter, if necessary, the resulting mixture is dried, calcined at an appropriate temperature, and pulverized to prepare a raw material powder. These raw material powders may be dry-molded as they are, or may be kneaded together with a binder such as polyvinyl alcohol or polyethylene glycol to prepare a kneaded product, which may be dried and then shaped. This compact is sintered in the presence of molecular oxygen (usually in air) to form a sintered body. The sintered body usually preferably has a porous structure with a porosity of 10 to 55% and a pore diameter of 1 μm or less.

In the moisture-sensitive element composition of the present invention, the particle size of the raw material powder is usually 0.
1~3tt, molding pressure 50~1000Kg/cm2, sintering temperature of molded body 500~1200'C1 sintering time 0.5~
This can be obtained by setting conditions for 3 hours.

After polishing the sintered body thus obtained, if necessary, electrodes are formed using commonly used pastes such as gold paste l-1 platinum paste, ruthenium oxide paste, etc., and moisture-sensitive elements are formed. can be manufactured. Further, by using a thick film method, it is possible to increase mass productivity and reduce costs.

〔Example〕

Examples will be given and explained below.

Example 1 Titanium oxide and sodium pyrosulfate (9a2Sz07) were weighed so that the molar ratio was 96.5% and 3.5%, and mixed in a pound mill for 16 hours. 1 of the obtained mixture
It was dried at 40"C for 4 hours and granulated to prepare a raw material powder. This raw material powder was pressure-molded under conditions of 500 kg/cm2 to make a disc-shaped compacted body with a diameter of 12 mm and a thickness of about 2 mm. After sintering this compact at 900°C for 13 hours, a comb-shaped ruthenium oxide paste was screen printed on one side of the sintered body and baked at about 850°C.

The structure of the moisture-sensitive element thus manufactured is shown in FIG. In FIG. 1, 1 represents an electrode, and 2 represents a moisture-sensitive element composition.

Regarding this humidity sensing element, the ambient temperature was maintained at 25° C. in a constant temperature bath, the relative humidity was varied from 20 to 100%, and the change in resistance value at that time was examined. This result (number 1) is expressed as the resistance value change (number 1゛) of the moisture-sensitive element consisting only of titanium oxide component.
Figure 2 shows a comparison. As is clear from FIG. 2, the moisture-sensitive element composition of the present invention has a resistance of 1.04 x 106Ω at an ambient temperature of 25°C and a relative humidity of 30%, and a relative humidity of 80%.
It can be seen that the resistance value changes as low as 4.5×10'3 Ω over a wide temperature range, which is within an extremely practical resistance value range.

Example 2 Titanium oxide and barium selenite (Basest) were weighed so that the molar ratio was 96.5% and 3.5%, and mixed in a pot mill for 16 hours. 1 of the obtained mixture
It was dried at 40° C. for 4 hours and granulated to prepare a raw material powder.

This raw material powder was pressure-molded under conditions of 500 kg/cm2 to produce a disk-shaped compacted body with a diameter of 12 mm and a thickness of approximately 2+ nm. After sintering this compact at 1000°C for 13 hours, a comb-shaped ruthenium oxide paste was screen printed on one side of the sintered body and baked at about 850°C to form an electrode.

Regarding this humidity sensing element, the relative humidity was varied from 20 to 100% at an ambient temperature of 25°C in a constant temperature bath, and the change in resistance value (humidity sensitivity characteristics) at that time was investigated.

The moisture sensitivity characteristics (number 1) shown in FIG. 3 were obtained. For comparison, the humidity-sensitive characteristics of a moisture-sensitive element made only of titanium oxide are shown as number 1. As is clear from FIG. 3, the moisture-sensitive element composition of the present invention has an ambient temperature of 25°C.
At a relative humidity of 30%, it is 8. OX 105Ω, relative humidity 8
It can be seen that at 0%, the resistance value changes as low as 5.0×10 4 Ω over a wide temperature range, which is in an extremely practical resistance value range.

Examples 3 to 11 The compositions shown in Table 1 were sintered in the same manner as in Example 1, and the temperature-sensitive properties of the sintered bodies were examined.

The results are shown in Table 1. For comparison, the moisture absorption properties of the sintered body consisting only of titanium oxide components (Comparative Example 1) are also listed in Table 1.

Table 1 Examples 12 to 13 The compositions shown in Table 2 were sintered in the same manner as in Example 2, and the moisture sensitivity characteristics of the sintered bodies were examined.

The results are shown in Table 2. For comparison, the moisture sensitivity characteristics of the sintered body consisting only of titanium oxide components (Comparative Example 1) are also listed in Table 2.

Table 2 Example 14 In the same manner as in Example 1, titanium oxide and potassium selenite (KzSsCh) were added in mol% of 96.5% and 3.5%.
% composition was sintered and the moisture sensitive properties of the sintered body were investigated.

The results are shown in Table 3.

Table 3 Example 15 In the same manner as in Example 2, titanium oxide and potassium selenite (CaTeOs) were added in mol% of 96.5% and 3.5%.
% of the composition was sintered, and the temperature-sensitive properties of the sintered body were investigated.

The results are shown in Table 4.

Table 4 Examples 16 to 28 The compositions shown in Table 5 were sintered in the same manner as in Example 1, and the temperature-sensitive properties of the sintered bodies were examined.

The results are shown in Table 5.

Table 5 Examples 29 to 41 The compositions shown in Table 6 were sintered in the same manner as in Example 2, and the temperature-sensitive properties of the sintered bodies were examined.

The results are shown in Table 'f16.

Table 6 Examples 42 to 44 The compositions shown in Table 7 were sintered in the same manner as in Example 1, and the moisture sensitivity characteristics of the sintered bodies were examined.

The results are shown in Table 7. The results of Example 9 are also listed in Table 7.

Table 7 Examples 45 to 47 The compositions shown in Table 8 were sintered in the same manner as in Example 2, and the moisture sensitivity characteristics of the sintered bodies were examined.

The results are shown in Table 8. The results of Example 2 are also listed in Table 8.

Table 8 Example 48 The sintered body of the moisture-sensitive element composition used in Example 9 was heated at an ambient temperature of 25°C, 140°C, 160°C and 180'C, and the relative humidity was varied from 20 to 100%. The moisture sensitivity characteristics were investigated. The results are shown in Figure 4.

In the fourth recess, number L2, 3.4 has an ambient temperature of 25°C 1
Moisture sensitivity characteristics at 40°C, 60"C and 180°C are shown. In addition, the conventional product is shown with a dotted line in Figure 4 for reference. Dotted line numbers 1" and 2' indicate the humidity sensitivity at an ambient temperature of 25°C and 140°C, respectively. Exhibits moisture-sensitive properties. As is clear from FIG. 4, the temperature dependence is extremely small at an ambient temperature of 25 DEG C. to 40 DEG C., and there is no need for temperature compensation. In addition, in the humidity-sensitive element composition of the present invention, the total amount of change in the moisture-sensing properties at an ambient temperature of 25 to 80°C corresponds to the amount of change in the humidity-sensing properties of the conventional product at an ambient temperature of 25 to 40°C, and compared to the conventional product. It can be seen that the temperature characteristics are much smaller.

Example 49 A sintered body of the moisture-sensitive element composition used in Example 2 was heated at an ambient temperature of 25"C, 40°C, 160°C, and 180°C, and the relative humidity was varied from 20 to 100%, and the humidity sensitivity at that time was The characteristics were investigated and the results are shown in Figure 5.

In Figure 5, numbers 1, 2, and 3.4 indicate an ambient temperature of 25°C.
Moisture sensitivity characteristics at 240°C, 160°C and 180°C are shown. In addition, the conventional product is shown in dotted lines in FIG. 5 for reference. Dotted line numbers 1° and 2″ respectively indicate moisture sensitivity characteristics at an ambient temperature of 25°C and 140″C. As is clear from FIG. 5, the temperature dependence is extremely small at an ambient temperature of 25 DEG C. to 40 DEG C., and there is no need for temperature compensation.

Further, the humidity sensitive element composition of the present invention has an ambient temperature of 25 to 80°C.
It can be seen that the total amount of change in the sensitivity characteristics in 1 corresponds to the amount of change in the moisture sensitivity characteristics of the conventional product at an ambient temperature of 25 to 40° C., and the temperature characteristics are much smaller than that of the conventional product.

Example 50 The molar ratio of titanium oxide and potassium selenite (K2SeOi) was 89.5% and 10.5% in the same manner as in the above example.
The composition was sintered.

The obtained sintered body was left for 24 hours in an atmosphere with an ambient temperature of 25°C and a relative humidity of 98%, and then the hysteresis of the moisture sensitivity was examined at the same ambient temperature and relative humidity in the range of 20 to 80%. Further, in the same manner as above, the hysteresis of the moisture-sensitive characteristics of the sintered body of the composition of Example 9 was investigated.

The results are shown in FIG. In FIG. 6, numbers 1 and 2 indicate the results of Example 9.50, respectively.

As is clear from FIG. 6, the hysteresis in the moisture-sensitive characteristics of the sintered bodies of these compositions is about 3%R1+, and despite the load of leaving it for 24 hours at a relative humidity of 98%, the hysteresis is extremely small. It turns out that it is.

Example 51 The composition sintered body used in Example 2 and Example 13 was left for 24 hours in an atmosphere with an ambient temperature of 25°C and a relative humidity of 98%, and then at the same ambient temperature and a relative humidity of 20 to 80%.
The hysteresis of moisture sensitivity characteristics was evaluated eight times in the range of %.

The results are shown in FIG. In FIG. 7, numbers 1 and 2 indicate the results of Example 2.13, respectively.

As is clear from FIG. 7, the hysteresis in the moisture-sensitive characteristics of the sintered bodies of these compositions is within ±2%RH, and despite the load of leaving it for 24 hours at a relative humidity of 98%, the hysteresis is extremely small. It turns out that it is.

Example 52 The moisture-sensitive element composition of Example 9 was subjected to a thermal shock test for 50 cycles, with one cycle consisting of leaving it at an ambient temperature of 85°C for 30 minutes and then leaving it at an ambient temperature of -25°C for 30 minutes.
The moisture sensitivity characteristics of the moisture sensitive element composition before and after the thermal shock test were investigated in the same manner as in Example 1 above.

The results are shown in FIG. In FIG. 8, number 1 indicates the moisture sensitivity characteristics before the above test, and number 2 indicates the moisture sensitivity characteristics after the above test. For comparison, the moisture sensitivity characteristics of the conventional product before and after the above test are indicated by dotted line numbers 1" and 2", respectively.
As is clear from the figure, the moisture-sensitive element composition of the present invention shows a change in moisture-sensing properties before and after the thermal shock test of within 3%, indicating that it is much more resistant to thermal shock than conventional products.

Example 53 The composition sintered body used in Example 13 was heated to an ambient temperature of 8
After being left at 5°C for 30 minutes, a thermal shock test was performed for 50 cycles, with one cycle being left at an ambient temperature of -25°C for 30 minutes, and the W'1B characteristics before and after the thermal shock test were investigated in the same manner as in Example 2. Ta.

The results are shown in FIG. In FIG. 9, number 1 indicates the moisture sensitivity characteristics before the above test, and number 2 indicates the moisture sensitivity characteristics after the above test. For comparison, the moisture sensitivity characteristics of the conventional product before and after the above test are shown by dotted line numbers 1° and 2°, respectively. As is clear from FIG. 9, the moisture-sensitive element composition of the present invention exhibits a change in moisture-sensing properties before and after the thermal shock test of within 3%,
It can be seen that this product is extremely resistant to thermal shock compared to conventional products.

Example 54 The moisture-sensitive element composition of Example 50 was heated to an ambient temperature of 85°C.
1. The moisture-sensitive element composition was left in an environment with a relative humidity of 80% for one month, and the moisture-sensitivity characteristics of the moisture-sensitive element composition before and after the storage were examined in the same manner as in Example 1 above.

The results are shown in Table 9. As is clear from Table 9, even though the moisture-sensitive element composition of the present invention was placed in a harsh environment of high temperatures for a long period of time, the change in its moisture-sensitive characteristics was extremely small. Therefore, it can be seen that under normal atmosphere, it can be used for a long period of time without special heating cleaning. .

Table 9 Example 55 The sintered body of the composition used in Example 2 and Example 13 was immersed in distilled water at a temperature of 25°C for one month, and then air-dried.
The moisture sensitivity characteristics before and after the above-mentioned storage test were investigated in the same manner as in Example 2.

In Figure 1O, the number 1.1'' indicates the moisture sensitivity characteristics of the sintered body of Example 2 before and after the above test, and the number 2.2'' indicates the moisture sensitivity characteristics of the sintered body of Example 13 before and after the above test. shows.

As is clear from FIG. 10, there is almost no change in the moisture sensitivity characteristics of the sintered bodies of these compositions before and after the above test, and it can be seen that the water resistance is generally good. Therefore, it can be seen that the moisture-sensitive element composition of the present invention can be used for a long period of time without the need for special heating cleaning since there is no fear of deterioration of the moisture-sensing properties even under the harsh environment of dew condensation.

[Effects] According to the present invention, compared to conventional moisture-sensitive element compositions, the specific resistance value is low and within a practical range, temperature dependence is extremely small and temperature compensation is unnecessary, and moisture It is possible to provide a highly reliable moisture-sensitive element composition that has almost no hysteresis in its moisture-sensitive characteristics during adsorption and desorption, is resistant to thermal shock, and does not require special heating cleaning.

Furthermore, when an alkaline earth metal salt is used as the chalcogen oxo acid salt, a moisture-sensitive element composition with excellent water resistance can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing one form of a moisture sensitive device using the sensitive device composition of the present invention. Figures 2 to 10 are graphs showing the characteristics of the wet/temperature element composition of the present invention;
Figure 3 shows the humidity-sensitive characteristics, Figures 4-5 show the temperature dependence of the humidity-sensitive characteristics,
6 and 7 are graphs showing the hysteresis of the moisture sensitivity characteristics after being left at high temperatures, FIGS. 8 and 9 are graphs showing the moisture sensitivity characteristics before and after the thermal shock test, and FIG. 10 is a graph showing the moisture sensitivity characteristics before and after the water resistance test. In the figure, 1 indicates an electrode, and 2 indicates a humid composition proboscis. Patent Applicant Mitsubishi Gas Chemical Co., Ltd. Agent Patent Attorney Sada Kobori Text 11-sided sexual growth r9ty, > 4 years old Kilogram par Off map wq: Wako, -(% Nmeri Oncho,; 1 spelling [(221g)
Mouth t-ONN13 (%) Procedural amendment May 26, 1988

Claims (1)

[Claims] 1. In a moisture-sensitive element composition formed by sintering a metal oxide, a chalcogen oxoacid salt represented by the general formula (I) is blended with the metal oxide, and the presence of molecular oxygen Moisture-sensitive element composition A_xB_yO_2(I) (wherein A is an alkali metal or alkaline earth metal, B is a sulfur, selenium or tellurium atom, O is an oxygen atom, x is 1 to 2, y is 1 to 5, and z is a number from 2 to 7) 2. The amount of chalcogen oxo acid salt is 0.01 based on the sum of metal oxide and chalcogen oxo acid salt. ~9
Moisture sensitive element composition 3 of claim 1 in which the amount is 9.99 mol %; moisture sensitive element composition 4 in claim 1 in which the chalcogen oxoacid salt is an alkali metal salt; claim 1 in which the chalcogen oxoacid salt is a salt of tellurium. Moisture-sensitive element composition 5, the metal oxides are TiO_2, γ-Al_2O_3, Z
nO, MgO, ZrO_2, NiO, MgAl_2O_
Moisture sensitive element composition 6 of Claim 1 which is at least one selected from the group consisting of 4, Moisture sensitive element composition 7 of Claim 1 whose metal oxide is TiO_2, Claim 1 whose sintering temperature is 500 to 1200 ° C. Moisture sensitive element composition