JP6908845B2 - Manufacturing method of gas generator for detecting fluorine-containing compound gas - Google Patents

Description

The present invention relates to a method for producing a detection gas generator used in a method for detecting a fluorine-containing compound gas capable of detecting a trace amount of fluorine-containing compound gas for a long period of time.

Among fluorocarbon compound gases such as chlorofluorocarbons, perfluorocarbons, and perfluorocompounds, there are many that have high ozone depletion potential (ODP) and global warming potential (GWP), which has become a major international problem in recent years. It has become. For this reason, alternative gases with low ODP and GWP have been developed, but many of them are flammable or toxic.

For the detection of these fluorine-containing compound gases, there are infrared type sensors that utilize the infrared absorption of the fluorine-containing compound gas and heat ray type sensors that utilize the resistance change of the heat ray coil, but the lower limit of detection is several hundred ppm in both cases. , It was impossible to detect several ppm of fluorine-containing compound gas. The alternative gases with low ODP and GWP that have been developed in recent years include many flammable or toxic gases, and it is necessary to detect a small amount of these gases on the order of several ppm.

As a method for detecting a trace amount of fluorine-containing compound gas on the order of several ppm, the applicant applies a contact reaction with a heated solid metal to convert the gas into a gas that is easy to detect, and the gas is detected by gas using electrolysis. A method for detecting a fluorine-containing compound gas, which is characterized by detecting by the output of a gas detector or a tape-type gas detector, has been disclosed (Patent Document 1). Further, as a method for obtaining the required reaction rate even when the reaction temperature is further lowered, a method using the solid metal in which an alkali metal fluoride is impregnated on the surface has been proposed (Patent Document 2). Then, as a method of uniformly holding the adhering material on the surface for a long period of time, it has been proposed to use the adhering material as an alkali metal hydroxide or a metal oxide (Patent Document 3).

Japanese Patent No. 3375072 Japanese Patent No. 3460601 Japanese Unexamined Patent Publication No. 2003-139760

However, in the method for detecting a fluorine-containing compound gas, when the solid drug in which an alkali metal fluoride is impregnated with a solid metal is used, the required reaction rate can be maintained for about one month, but the reaction occurs after one year or more. There was a problem that detection became difficult due to the decrease in speed. In order to solve this problem, we have developed a method for detecting a trace amount of fluorine-containing compound gas even after one year or more by using an alkali metal hydroxide or a metal oxide as the adhesive (Patent Document 3). However, the output of the gas detector may decrease by about 10%, and it is necessary to adjust the output of the amplifier in order to continuously obtain the same level of electric output. Although the cause of this is not clear, the locally melted deposit moves on the surface of the solid metal and a part of the solid metal disappears during the contact reaction by heating the solid metal to 100 ° C. or higher. It is probable that the adhering material could not be held uniformly on the metal surface, and the catalytic effect of the adhering material was reduced.

The present invention has been made with attention to such a point, and an object of the present invention is to provide a method for producing a detection gas generating agent capable of detecting a trace amount of fluorine-containing compound gas for a long period of time.

As a result of diligent studies on the above-mentioned problems, the present inventor has determined to use an adhering agent, which is obtained by forming fine irregularities on the surface of a solid metal and roughening the surface, and then adhering an adhering material, to detect a fluorine-containing compound gas. The present invention has been reached by finding that a trace amount of fluorine-containing compound gas can be detected for a long period of time.

That is, the present invention comprises a step of forming fine irregularities on the surface of a granular or massive solid metal to roughen it, and imposing an alkali metal fluoride or an alkali metal hydroxide on the roughened surface of the solid metal. Provided is a method for producing a detection gas generating agent used for detecting a fluorine-containing compound gas, which comprises a step.

The present invention can provide a method for producing a detection gas generating agent capable of detecting a trace amount of fluorine-containing compound gas for a long period of time.

It is the schematic of the experimental apparatus for detection confirmation of a fluorine-containing compound gas.

Hereinafter, the present invention will be described in detail.
In the method for producing a detection gas generator (hereinafter, also referred to as “ detection agent ”) used for detecting a fluorine-containing compound gas of the present invention, fine irregularities are formed on the surface of a granular or massive solid metal. It is characterized by including a step of roughening the surface of the solid metal and a step of adhering an alkali metal fluoride or an alkali metal hydroxide on the roughened surface of the solid metal.
Further, in the method for detecting a fluorine-containing compound gas of the present invention, the detection gas generator obtained by the above-mentioned production method and a gas containing a trace amount of the fluorine-containing compound gas are contact-reacted in a temperature range of 100 to 1000 ° C. It is characterized by including a step and a step of detecting the gas generated by the reaction.

The fluorine-containing compound gas to be detected is chlorofluorocarbon, perfluorocarbon, hydrofluorocarbon, hydrochlorofluorocarbon, perfluorocompound, etc., and in particular, C ₅ F ₈ , C ₄ F ₈ , C ₄ F ₆ , C ₂ F ₆ , C ₃ F ₈ , CF ₄ , C ₅ HF ₇ , CH ₂ F ₂ , CHF ₃ , CCl ₃ F, CCl ₂ F ₂ , _{CCl F 3} , CCl ₄ , CHClF ₂ , CH ₃ Cl, CH _{3 Br, CHCl 3, CBr 2 F} 2, CBrF 3, CH 2 Br 2, CH 2 BrCl, CBr 3 F, CHBr 2 F, CHBrF 2, CBrClF 2, C 2 H 3 Cl, C 2 BrF 5, C 2 ClF ₅ , C ₂ Cl ₂ F ₄ , C ₂ Cl ₃ F ₃ , C ₂ BrF ₄ , C ₂ Br ₂ F ₄ , C ₂ H ₂ Br ₂ F ₄ , C ₂ Br ₂ ClF ₃ , NF ₃ . Regarding the gas targeted by the detection method of the present invention, the trace amount is a gas having a concentration of several thousand volume ppm or less of the fluorine-containing compound gas, and particularly a gas having a concentration range of 1 volume ppb or more and 1000 volume ppm or less. In particular, when C ₅ F ₈ is the target of detection, since the permissible exposure concentration is 2 volume ppm, it is preferable that it can be detected well in the concentration range of 0.01 volume ppm or more and 20 volume ppm or less, and 0.1 volume. It is more preferable that it can be detected well in the concentration range of ppm or more and 10 volumes by ppm or less.

In the present invention, a solid metal impregnated with an alkali metal fluoride or an alkali metal hydroxide to the above-described fluorine-containing compound gas and the surface is contacted reacted under heating conditions, it is more gas detection easy gas, SiF _4, It is converted into gas such as WF ₆ , MoF ₆ , and GeF _4. During the contact reaction, the solid metal is heated to 100-1000 ° C. This temperature range is preferably 200 to 500 ° C, more preferably 250 to 450 ° C.

The solid metal used in the present invention is preferably Si, W, Mo or Ge. The alkali metal fluoride as an adduct is preferably sodium fluoride or potassium fluoride, and the alkali metal hydroxide is preferably sodium hydroxide or potassium hydroxide.

In the present invention, Si, W, Mo, or Ge is preferably used as the solid metal, but commercially available ones have a granular or lumpy appearance. The purity of the solid metal is not particularly limited, but is preferably 90% by mass or more, more preferably 98% by mass or more, and further preferably 99% by mass or more. Most of these commercially available products are used in the fields of semiconductors, liquid crystals, and solar cells by being powdered or melted, and the cases where they are used in the form of granules or lumps are very limited. Therefore, the surface condition of these solid metals does not matter, and they are commercially available from the molded state without surface processing. Therefore, the surface state of many commercially available solid metals is flattened, and it is difficult to uniformly form and hold the deposit on the surface for a long period of time. The method for obtaining a commercially available granular or lumpy solid metal is not particularly limited, but a method for obtaining an ingot having a diameter of 1 cm or more by pulverization, a method for obtaining a molten metal by refining and cooling it, and a compound gas of a solid metal. A method of precipitating a solid from the above can be mentioned.

The solid metal is granular or lumpy, and its size is such that it has passed through a sieve having a mesh size of 9.5 mm and has not passed through a sieve having a mesh size of 0.5 mm. Larger ones that do not pass through a sieve with a mesh opening of 9.5 mm have problems such as a large filling space, a large amount of gas to be detected, and a decrease in the contact area with the gas, resulting in insufficient reaction. Therefore, it is not suitable. Further, a sieve having a mesh size of 0.5 mm is not suitable because it blocks the path of the gas to be measured and obstructs the flow.

When an alkali metal hydroxide is used as an adjunct, the alkali metal hydroxides such as NaOH and KOH form various metal fluorides by reacting with a fluorine-containing compound gas. For example, using the C ₅ F ₈ gas in the fluorine-containing compound gas, the use of NaOH in the alkali metal oxides, in the presence of oxygen at 200 to 500 ° C. (1) as shown in equation response is obtained ..
C ₅ F ₈ + 8 NaOH + 3O ₂ → 8NaF + 4H ₂ O + 5CO ₂ (1)
_{When Si is used as the solid metal, SiF 4} is produced in the NaF produced here at 200 to 500 ° C., which is the same temperature in the presence of water and oxygen, as shown in equation (2).
4NaF + Si + 2H ₂ O + O ₂ → SiF ₄ + 4NaOH (2)
_{That is, in the formula (2), SiF 4,} which is a gas to be measured that is easy to detect, is obtained, while the NaF produced in the formula (1) becomes NaOH again in the formula (2).
The reaction mechanism when the alkali metal hydroxide is attached to the solid metal surface is the above-mentioned two-stage reaction. As a result, the alkali metal hydroxide is used as a catalyst as shown in the formula (3). The reaction is as if it were working.
C ₅ F ₈ + 2Si + _{8 NaOH + 5O 2}
→ 2SiF ₄ + 5CO ₂ + 8 NaOH (3)

When alkali metal fluoride is used as an adjunct, treatment is required in advance. For example, when NaF is used as the alkali metal fluoride and Si is used as the solid metal, SiF ₄ is produced at 200 to 500 ° C. as shown in the formula (2) in the presence of water and oxygen. NaF is replaced with NaOH with the formation of SiF _{4 , and it is necessary to separately discharge SiF 4} to the outside of the system until this is completed. After the replacement, detection of fluorine-containing compound gas is performed from (1) to (3). ) The reaction mechanism is the same as the equation. It is considered that the same reaction as the above equations (1) to (3) occurs even in the temperature range of 100 to 1000 ° C.

As a method of forming fine irregularities on the surface of the solid metal, which is a detection agent for fluorine-containing compound gas, to roughen the surface, (A) a method of scraping off a part of the surface of the solid metal by machining, (B) etching. A method of removing a part of the solid metal surface with a liquid, a method of (C) removing a part of the solid metal surface with an etching gas, and (D) a method of adhering a fine powdery solid metal to the solid metal surface. Can be mentioned. By adhering the adhering material to the roughened solid metal surface, the coagulant can be uniformly held on the solid metal surface for a long period of time.

(A) As a method of scraping off a part of the surface of the solid metal by machining, there is a method of using a tool or a machine tool, but considering the size of the solid metal as an object, a large amount of these are aggregated. Processing individual objects is inefficient and unsuitable because of differences in their shapes. Therefore, in the present invention, the aggregate of the solid metal is enclosed in a cylindrical cylinder, and the central axis of the cylinder is aligned with the rotation axis while maintaining the range within ± 60 ° in the horizontal direction. It is preferable to adopt a method in which the solid metals come into contact with each other by rotating the cylinder from the outside to form fine irregularities on the surface and roughen the surface. The rotation speed of the cylinder is preferably 10 rpm or more and 100 rpm or less, and the rotation time is preferably 30 minutes or more and 5 hours or less. If the rotation speed of the cylinder is less than 10 rpm, the impact force between the solid metals is small and it is not possible to obtain the fine irregularities on the surface, and if it exceeds 100 rpm, the centrifugal force is large and the number of collisions increases. Similarly, the number of fine irregularities required on the surface cannot be obtained because the number is reduced. If the rotation time of the cylinder is less than 30 minutes, the number of collisions between the solid metals is small, and the number of fine irregularities required on the surface cannot be obtained. It is not suitable because the amount of processed powder generated increases and the shape of the solid metal becomes smaller.

(B) In the method of removing a part of the surface of the solid metal with an etching solution, for example, if the solid metal is Si, the aggregate of the solid metal is immersed in a mixed solution of nitrate and hydrofluoric acid, and the surface of the solid metal is used. A method of reaction-removing a part of Si is adopted. Nitric acid undergoes an oxidation reaction of Si as shown in equation (4), and hydrofluoric acid undergoes a chemical reaction with a dissolved substance of silicon oxide as shown in equation (5).
Si + HNO ₃ + H ₂ O → SiO ₂ + HNO ₂ + H ₂ (4)
SiO ₂ + 6HF → H ₂ SiF ₆ + 2H ₂ O (5)

If the compound is W, a method of immersing the aggregate of the solid metal in an aqueous solution of potassium hydroxide to react and remove a part of W on the surface of the solid metal is adopted. Potassium hydroxide becomes a compound of W as shown in equation (6) and dissolves in an aqueous solution.
W + 2KOH + 2H ₂ O → K ₂ WO ₄ + 3H ₂ (6)

If the solid metal is Mo, a method of immersing the aggregate of the solid metal in a mixed solution of nitric acid and hydrochloric acid or a mixed solution of nitric acid and sulfuric acid to react and remove a part of Mo on the surface of the solid metal is adopted. Nitric acid carries out an oxidation reaction of Mo as shown in the formula (7), and hydrochloric acid or sulfuric acid carries out a chemical reaction with a dissolved substance of molybdenum oxide as shown in the formulas (8) and (9), respectively.
Mo + 2HNO ₃ + H ₂ O → MoO ₃ + 2HNO ₂ + H ₂ (7)
MoO ₃ + 2HCl → MoCl ₂ O ₂ + 1 / 2O ₂ (8)
MoO ₃ + 2H ₂ SO ₄ → Mo (SO ₄ ) ₂ + 2H ₂ O + 1 / 2O ₂ (9)

If the solid metal is Ge, a method of immersing the aggregate of the solid metal in a mixed solution of nitric acid and hydrofluoric acid to react and remove a part of Ge on the surface of the solid metal is adopted. Nitric acid undergoes an oxidation reaction of Ge as shown in equation (10), and hydrofluoric acid undergoes a chemical reaction of germanium oxide as in equation (11).
Ge + HNO ₃ + H ₂ O → GeO ₂ + HNO ₂ + H ₂ (10)
GeO ₂ + 6HF → H ₂ GeF ₆ + 2H ₂ O (11)

(C) In the method of removing a part of the surface of the solid metal with an etching gas, for example, if the solid metal is Si, an aggregate of the solid metal is sealed in a closed container and fluorine gas is supplied thereto. a part of Si of the solid metal surface by, to employ a method of reacting removed as SiF ₄ gas. The reaction formula of Si and fluorine gas is as shown in formula (12).
Si + 2F ₂ → SiF ₄ (12)
If the solid metal is W, Mo, or Ge, a part of the surface of the solid metal can be reacted and removed as _{WF 6} gas, MoF ₆ gas, and GeF _{4 gas, respectively, as in the case of Si described above.}

Further, chlorine trifluoride gas or nitrogen trifluoride gas can also be used as the fluorine supply source. If the solid metal is Si, the reaction formulas are as shown in formulas (13) and (14), respectively.
Si + 4/3 ClF ₃ → SiF ₄ + 2/3 Cl ₂ (13)
Si + 4/3NF ₃ → SiF ₄ + 2 / 3N ₂ (14)
If the solid metal is W, Mo, or Ge, the reaction can be removed as _{WF 6} gas, MoF ₆ gas, or GeF _{4 gas in the same manner as described above.}

(D) In the method of adhering a fine powdery solid metal to the surface of the solid metal, for example, if the solid metal is Si, fine powdery Si is obtained from a lumpy Si or the like using a crusher or the like, and heat resistance thereof is obtained. A method of adhering an adhesive-added material to the massive Si is adopted. In order to form fine irregularities by this method, the average particle size of fine powder Si (meaning the median diameter in the volume-based particle size distribution based on the general laser diffraction / light scattering method) should be 10 μm or more and 500 μm. Is preferable. The heat-resistant adhesive preferably has a heat-resistant temperature of 1000 ° C. or higher, and a ceramic-based adhesive containing ceramic of one selected from the group consisting of silica, alumina, zircon, and zirconia or a mixture thereof can be used.

The alkali metal fluoride or alkali metal hydroxide is dispersed and adhered to the entire surface of the solid metal, but the adhering material adhered as fine particles to the concave portion can reduce the surface energy in the concave portion. It stabilizes, such as making it difficult to move on the surface of solid metal even under heating conditions. Therefore, by forming fine irregularities on the surface of the solid metal and roughening the surface, the adhering material adheres to the concave portion of the surface of the solid metal, and the adhering material is long on the solid surface even under a heated state. It can be held stably and uniformly for a period of time. The diameter of the deposit on the surface of the solid metal is preferably 1 nm or more and 500 nm or less, and preferably 10 nm or more and 200 nm or less.

The diameter of the concave portion of the unevenness (the length of the ridge line connecting the tops of the convex portions in the cross section) is 10 nm or more and 500 nm or less, and preferably 50 nm or more and 200 nm or less. Further, the depth of the concave portion of the unevenness (the distance between the bottom of the concave portion and the ridgeline connecting the top of the convex portion) is 10 nm or more and 500 nm or less, and preferably 50 nm or more and 200 nm or less. If it is smaller than this range, the amount of the adhering material permeating on the surface of the solid metal cannot be sufficiently obtained, and the effect cannot be obtained. If it becomes larger than this range, the amount of adhesion obtained for each concave portion becomes large, but it cannot be uniformly held on the surface of the solid metal and is locally held, so that no effect can be obtained.

Further, in the reaction between the fluorine-containing compound gas and the solid metal, the reaction temperature and the amount of produced gas depend on the amount of alkali metal fluoride or alkali metal hydroxide adhering to the solid metal. It should be adjusted within the range of the optimum amount of fluoride shown in. That is, the amount of alkali metal fluoride or alkali metal hydroxide to be adhered to the solid metal surface is at least 1 ppm by weight, and if it is less than this, a sufficient effect cannot be expected. On the other hand, it can be said that there is essentially no upper limit to the amount of alkali metal fluoride or alkali metal hydroxide, but when the weight ratio exceeds 50,000 ppm, alkali metal fluoride or alkali metal hydroxide covers the solid metal surface. Therefore, contact with the fluorine-containing compound gas is hindered and the treatment effect is reduced. In the reaction between the fluorine-containing compound gas and the solid metal, the amount of alkali metal fluoride or alkali metal hydroxide that maximizes the reaction rate is 200 to 20000 ppm by weight, and a large amount is unnecessarily attached. However, the effect corresponding to it cannot be expected. The amount of alkali metal fluoride or alkali metal hydroxide attached as a weight ratio is as the solid metal is consumed by reacting with the fluorine-containing compound gas (alkali metal fluoride or alkali metal hydroxide). The value gradually increases (because it is not consumed), but it goes without saying that the amount of alkali metal fluoride or alkali metal hydroxide attached here is for the initial state.

Various generally known methods can be applied to impregnate the surface of the solid metal with alkali metal fluoride or alkali metal hydroxide. For example, (a) a method of adhering an alkali metal fluoride or an alkali metal hydroxide to the surface of the solid metal by a vacuum vapor deposition method, and (b) mixing the solid metal with an alkali metal fluoride or an alkali metal hydroxide. A method of melting and adhering to the surface of the solid metal in a high temperature environment of an inert atmosphere such as nitrogen, (c) Dissolving alkali metal fluoride or alkali metal hydroxide in a solvent, mixing with the solid metal, and then There are a method of evaporating and removing the solvent and depositing it on the surface of the solid metal, and the like, but any method is effective.

FIG. 1 shows a schematic view of an experimental device for detecting and confirming a fluorine-containing compound gas according to the method of the present invention. Sample gas 1 containing a trace amount of fluorine-containing compound gas in the atmosphere to be detected, and this gas is introduced into ^{a solid metal filling cylinder 2 impregnated with alkali metal fluoride or alkali metal hydroxide at about 500 cm 3 / min.} , Contact with solid metal. The solid metal filling cylinder 2 is heated by the heating heater 3 to heat the solid metal inside the filling cylinder. From the outlet of the solid metal filling cylinder 2, the gas detector 4 using electrolysis and the tape type gas detector 5 are introduced, and these gas detectors obtain the electric output required for detection.

In the gas detector 4 using electrolysis, _{gas such as SiF 4} , WF ₆ , MoF ₆ , and GeF _{4 is} electrolyzed on the electrode, and the current generated at that time is proportional to the gas concentration. The density is detected by the output. Further, in the tape-type gas detector 5, which is another type of gas detector, a breathable tape made of a material such as nitrocellulose impregnated with a color former is coated with SiF ₄ , WF ₆ , MoF ₆ , and so on. The _{concentration is detected by passing a gas such as GeF 4} and converting the reflected light from the color development formed by the reaction into a current output and measuring it.

Hereinafter, description will be made in detail with reference to Examples, but the present invention is not limited to such Examples. In addition, Examples and Comparative Examples are summarized in the table.

[Example 1]
_{Atmosphere of C 5} F ₈ = 10 volume ppm was used as the gas to be detected, and Si was used as the solid metal. The Si is a mass obtained by crushing an ingot, and its size is such that it has passed through a sieve having a mesh size of 2.0 mm and has not passed through a sieve having a mesh size of 1.0 mm. The aggregate of the massive Si is enclosed in a ceramic cylindrical cylinder, and the cylinder placed so that the central axis of the cylinder is horizontal is 50 rpm from the outside so that the central axis of the cylinder coincides with the rotation axis. By rotating the surface for 1 hour, fine irregularities were formed on the surface and the surface was roughened. Since fine processed powder was generated in the aggregate after machining, these processed powders were removed by sieving.

NaF, which is an alkali metal fluoride, was used as an adhering material, and NaF was adhered to the Si so as to have a weight ratio of 1000 ppm, and these were filled in a filling cylinder and heated to 400 ° C.

After the introduction of the gas to be detected, an electric output of 2.88 V was obtained at the initial stage of measurement in the gas detector using electrolysis due to the components of the gas generated by the reaction with the solid metal as shown in Table 1. In the tape type gas detector, a current output of 3.69 V was obtained at the initial stage of measurement. Here, the output of the gas detector is adjusted so that the minimum value is 0V and the maximum value is 5V, and the concentration of the gas to be detected and the voltage output are in a proportional relationship. When the concentration of the detection target gas is 0 volume ppm, it becomes 0 V, and if there is an output of 4 V at 10 volume ppm, it is adjusted so that an output of 2 V can be obtained at 5 volume ppm. After that, the filling cylinder was continuously heated to 400 ° C., the atmosphere was ^{introduced at about 500 cm 3} per minute and left for 1 year, and after that, _{the atmosphere of C 5} F ₈ = 10 volume ppm was used again as the detection target gas. A gas detector using electrolysis has a current output of 2.78 V, and a tape-type gas detector has a current output of 3.56 V, both of which have a decrease in output of 3.5% or less and little change over time. It was confirmed that.

[Example 2]
Gas detection was confirmed by the same method as in Example 1 except that an etching solution was used instead of machining to roughen the Si surface. As the etching solution, a mixed aqueous solution of 1% by weight of nitric acid and 1% by weight of hydrofluoric acid was used, and the solid metal was immersed in the etching solution at a temperature of 50 ° C. for 1 hour in a stainless steel container to remove a part of Si on the surface of the solid metal. The reaction was removed and the surface was roughened.
As a result of the measurement, an electric output of 2.84V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 3.66 V was obtained at the initial stage of measurement. Similar to Example 1, after one year has passed, a current output of 2.75 V is obtained in the gas detector using electrolysis, and a current output of 3.53 V is obtained in the tape type gas detector, both of which are reduced in output. Was 3.5% or less, and it was confirmed that the change with time was small.

[Example 3]
Gas detection was confirmed by the same method as in Example 1 except that etching gas was used instead of machining to roughen the Si surface. The etching gas used was diluted with nitrogen of 1% by volume of fluorine, and the solid metal and the etching gas were brought into contact with each other at a temperature of 50 ° C. for 1 hour in a sealed stainless steel container to form a part of the surface of the solid metal. the Si reacts removed as SiF ₄ gas was roughened.
As a result of the measurement, an electric output of 2.88V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 3.66 V was obtained at the initial stage of measurement. Similar to Example 1, after one year has passed, a current output of 2.78 V is obtained in the gas detector using electrolysis, and a current output of 3.56 V is obtained in the tape type gas detector, both of which are reduced in output. Was 3.5% or less, and it was confirmed that the change with time was small.

[Example 4]
Si was roughened by the same method as in Example 3 except that a nitrogen-diluted chlorine trifluoride of 1% by volume was used as the etching gas, and the detection of the gas was confirmed by the same method as in Example 1.
As a result of the measurement, an electric output of 2.78 V was obtained at the initial stage of the start of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 3.63 V was obtained at the initial stage of measurement. Similar to Example 3, after one year has passed, a current output of 2.69 V is obtained in the gas detector using electrolysis, and a current output of 3.50 V is obtained in the tape type gas detector, both of which are reduced in output. Was 3.5% or less, and it was confirmed that the change with time was small.

[Example 5]
A nitrogen-diluted etching gas of 1% by volume of nitrogen trifluoride is used as the etching gas, and the solid metal and the etching gas are brought into contact with each other at a temperature of 500 ° C. for 1 hour in a sealed stainless steel container in the same manner as in Example 3. it makes reacted removing a portion of Si in the solid metal surface as a SiF ₄ gas, roughened. Here, since the reaction of nitrogen trifluoride gas with Si does not proceed at room temperature, the reaction was carried out at a higher temperature than the fluorine gas and chlorine trifluoride gas shown in Examples 3 and 4. Using Si roughened by the above method, gas detection was confirmed by the same method as in Example 1.
As a result of the measurement, an electric output of 2.75 V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 3.59 V was obtained at the initial stage of measurement. Similar to Example 3, after one year has passed, a current output of 2.66 V is obtained in the gas detector using electrolysis, and a current output of 3.50 V is obtained in the tape type gas detector, both of which are reduced in output. Was 3.5% or less, and it was confirmed that the change with time was small.

[Examples 6 to 39]
The measurement was carried out by changing the detection target gas in the same manner as in Example 1. The concentration of the gas to be detected was 10 volumes ppm in the atmosphere. As shown in Table 1, the measurement results for each detection target gas vary slightly depending on the type of detection target gas, but the decrease in output was 5.0% or less, confirming that the change over time was small.

[Examples 40 to 42]
In the same manner as in Example 1, W, Mo, and Ge were used for the solid metal, and the surface was roughened by the same machining to carry out the measurement. As shown in Table 1, the measurement results for each solid metal were slightly different depending on the type of the solid metal, but the decrease in output was 5.0% or less, confirming that the change with time was small.

[Example 43]
Gas detection was confirmed by the same method as in Example 2 by using W for the solid metal and using an etching solution to roughen the surface. As the etching solution, an aqueous solution of potassium hydroxide in an amount of 1% by weight was used, and the solid metal was immersed in the etching solution at a temperature of 50 ° C. for 1 hour in a stainless steel container to remove a part of W on the surface of the solid metal by reaction. Surfaced.
As a result of the measurement, an electric output of 1.28V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 1.38 V was obtained at the initial stage of measurement. Similar to Example 2, after one year has passed, a current output of 1.22 V is obtained in the gas detector using electrolysis, and a current output of 1.31 V is obtained in the tape type gas detector, both of which are reduced in output. Was 5.0% or less, and it was confirmed that the change with time was small.

[Example 44]
Using Mo for the solid metal and an etching solution for roughening the surface by the same method as in Example 2, gas detection was confirmed by the same method as in Example 2. As the etching solution, a mixed aqueous solution of 1% by weight of nitric acid and 1% by weight of hydrochloric acid is used, and the solid metal is immersed in the etching solution at a temperature of 50 ° C. for 1 hour in a stainless steel container to react a part of Mo on the surface of the solid metal. It was removed and roughened.
As a result of the measurement, an electric output of 1.19V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 1.13 V was obtained at the initial stage of measurement. Similar to Example 2, after one year has passed, a current output of 1.16V is obtained in the gas detector using electrolysis, and 1.09V is obtained in the tape type gas detector, both of which are reduced in output. Was 3.0% or less, and it was confirmed that the change with time was small.

[Example 45]
In the same manner as in Example 44, a mixed aqueous solution of 1% by weight of nitric acid and 1% by weight of sulfuric acid was used as an etching solution, and the solid metal was immersed in the etching solution at a temperature of 50 ° C. for 1 hour in a stainless steel container. A part of Mo on the surface was reaction-removed to roughen the surface. Using Mo roughened by the above method, gas detection was confirmed by the same method as in Example 44.
As a result of the measurement, an electric output of 1.22V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 1.19 V was obtained at the initial stage of measurement. Similar to Example 44, after one year has passed, a current output of 1.19 V is obtained in the gas detector using electrolysis, and a current output of 1.16 V is obtained in the tape type gas detector, both of which are reduced in output. Was 3.0% or less, and it was confirmed that the change with time was small.

[Example 46]
Gas detection was confirmed by the same method as in Example 2 by using Ge for the solid metal and using an etching solution for roughening the surface. As the etching solution, a mixed aqueous solution of 1% by weight of nitric acid and 1% by weight of hydrofluoric acid is used, and the solid metal is immersed in the etching solution at a temperature of 50 ° C. for 1 hour in a stainless steel container to obtain a part of Ge on the surface of the solid metal. The reaction was removed and the surface was roughened.
As a result of the measurement, an electric output of 3.22V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 3.31 V was obtained at the initial stage of measurement. Similar to Example 2, after one year has passed, a current output of 3.09 V is obtained in the gas detector using electrolysis, and a current output of 3.19 V is obtained in the tape type gas detector, both of which are reduced in output. Was 4.0% or less, and it was confirmed that the change with time was small.

[Examples 47 to 49]
In the same manner as in Example 1, KF, which is an alkali metal fluoride, and NaOH, KOH, which are alkali metal hydroxides, are used as the adhering material, and the Si is impregnated so as to have a weight ratio of 1000 ppm, and the measurement is performed. carried out. As shown in Table 1, the measurement results for each of the attachments vary slightly depending on the type of the attachment, but the decrease in output was 4.0% or less, confirming that the change with time was small.

[Examples 50 to 52]
Gas detection was confirmed by the same method as in Example 1 except that the rotation speed and rotation time of the cylinder were changed.
As shown in Table 1, the measurement results for each of the attachments showed a slight change due to the difference in the rotation speed and rotation time of the cylinder, but the decrease in output was 4.0% or less, confirming that the change over time was small. .. The conditions of each embodiment are as follows.
In Example 50, the rotation speed of the cylinder is 10 rpm and the rotation time is 30 minutes, in Example 51, the rotation speed of the cylinder is 50 rpm and the rotation time is 10 hours, and in Example 52, the rotation speed of the cylinder is 100 rpm and the rotation time is 10 hours. And said.

[Example 53]
Gas detection was confirmed by the same method as in Example 1 except that fine powdery Si was used instead of machining to roughen the Si surface. Fine powder Si crushed to an average particle size of several tens of μm is added to the massive Si so as to be 20 wt% of the total weight, and a ceramic adhesive (alumina is the base component) as an adhesive is added to 2 wt% of the total weight. Added as. After drying, the fine powdery Si that did not adhere to the surface of the massive Si was removed by sieving. Finally, the fine powder Si was completely fixed and roughened by heat treatment at 1000 ° C. or higher. NaF, which is an alkali metal hydroxide, was used as an adhering material, and the Si was adhered to the Si so as to have a weight ratio of 1000 ppm, and the measurement was carried out. As a result of the measurement, an electric output of 3.20 V was obtained at the initial stage of the measurement in the gas detector using electrolysis. In the tape type gas detector, a current output of 3.46 V was obtained at the initial stage of measurement. Similar to Example 1, after one year has passed, a current output of 3.15 V is obtained in the gas detector using electrolysis, and 3.34 V is obtained in the tape type gas detector, both of which are reduced in output. Was 3.5% or less, and it was confirmed that the change with time was small.

[Comparative Examples 1 to 3]
The measurement was carried out in the same manner as in Example 1 without roughening. NaF, which is an alkali metal fluoride, was used as an adhering material, and NaF was adhered to the Si so as to have a weight ratio of 1000 ppm, and C ₅ F ₈ , C ₄ F ₆ , and C ₅ HF ₇ were used as the gas to be measured. .. As shown in Table 2, the measurement results vary slightly depending on the type of gas to be detected, but the decrease in output is 60% or more, confirming that the change over time is extremely large.

[Comparative Examples 4 to 6]
The measurement was carried out in the same manner as in Example 1 without roughening. NaOH, which is an alkali metal hydroxide, is used as the adhering material, and it is adhered to the Si so as to have a weight ratio of 1000 ppm, and C ₅ F ₈ , C ₄ F ₆ , and C ₅ HF ₇ are used as the gas to be measured. did. As shown in Table 2, although the measurement results vary slightly depending on the type of gas to be detected, the decrease in output was 10 ± 1%, confirming that the change over time was large.

Comparing Example 1 and Comparative Example 1, the surface of the massive Si that reacts with the fluorine-containing compound gas is roughened even though the adhering substance is NaF and the adhering amount is the same as 1000 mass ppm with respect to Si. As a result, the life of the detection agent could be extended. It is considered that this is because the adhering material acting as a catalyst in the detection agent of Example 1 is held in the fine recesses on the surface of the roughened massive Si and remains on the surface of the massive Si. On the other hand, in the detection agent of Comparative Example 1, the adhering material moved on the surface of the solid metal and a part of the adhering material disappeared, the adhering material could not be held uniformly on the surface of the solid metal, and the catalytic effect of the coagulant was lowered. It is considered to be. This is the same not only when the surface is roughened by machining but also when the surface is roughened by an etching solution or an etching gas (Examples 1 to 4), and the same is true even if the adhering material is changed to NaOH. (Comparison of Example 48 and Comparative Example 4).

As described in detail above, according to the method of the present invention, in the method for detecting a fluorine-containing compound gas, a gas containing a trace amount of the fluorine-containing compound gas and a solid metal having an alkali metal fluoride or an alkali metal hydroxide impregnated on the surface thereof. In the method of detecting the generated gas by contacting with and in a heated state, fine irregularities are formed on the surface of the solid metal to roughen the surface, and alkali metal fluoride or alkali metal hydroxide is impregnated therein. , A trace amount of fluorine-containing compound gas can be detected for a long period of time.

1 ... Sample gas (fluorine-containing compound gas)
2 ... Solid metal filling cylinder 3 ... Filling cylinder heater 4 ... Gas detector using electrolysis 5 ... Tape type gas detector

Claims (10)

As a method for detecting a fluorine-containing compound gas, a gas containing a trace amount of the fluorine-containing compound gas is introduced into a filling cylinder filled with a detection gas generator made of a solid metal in which an adhering substance is dispersed over the entire surface. In the method for producing a gas generating agent for detection, which is used in a method for detecting a gas generated by contacting a solid metal in a heated state.
The adhesive is an alkali metal fluoride or an alkali metal hydroxide.
The solid metal is a solid metal having a size that has passed through a sieve having a mesh size of 9.5 mm and has not passed through a sieve having a mesh size of 0.5 mm, which is granular or lumpy and has not been surface-processed from the molded state . ,
A step of forming fine irregularities on the surface of the solid metal to roughen the surface, and
To the impregnated product of solid metal on the roughened surface of the solid metal, or 200ppm in a weight ratio, comprising the steps of impregnated below 50000 ppm, to hold the impregnating material to the concave portion of the concavo-convex,
A method for producing a detection gas generator used for detecting a fluorine-containing compound gas, which comprises. The production of the detection gas generating agent according to claim 1, wherein a part of the surface of the solid metal is removed by machining as a method of forming fine irregularities on the surface of the solid metal to roughen the surface. Method. The production of the detection gas generating agent according to claim 1, wherein a part of the surface of the solid metal is removed with an etching solution as a method of forming fine irregularities on the surface of the solid metal to roughen the surface. Method. The production of the detection gas generating agent according to claim 1, wherein a part of the surface of the solid metal is removed with an etching gas as a method of forming fine irregularities on the surface of the solid metal to roughen the surface. Method. The detection device according to claim 1, wherein a fine powdery solid metal is adhered to the surface of the granular or lumpy solid metal as a method of forming fine irregularities on the surface of the solid metal to roughen the surface. A method for producing a gas generating agent. Claims 1 to 5 are characterized in that the step of holding the adhering material is a step of adhering an alkali metal fluoride or an alkali metal hydroxide to a roughened surface of a solid metal by a vacuum vapor deposition method. The method for producing a detection gas generating agent according to any one of the above items. Claims step of holding the impregnated material is the solid metal and an alkali metal fluoride or an alkali metal hydroxide are mixed, characterized in that it is a step of adhering by melting the solid metal surface in an inert atmosphere Item 8. The method for producing a detection gas generating agent according to any one of Items 1 to 5. The step of holding the adhesive is a step of dissolving alkali metal fluoride or alkali metal hydroxide in a solvent, mixing with the solid metal, and then evaporating and removing the solvent to deposit on the surface of the solid metal. The method for producing a detection gas generating agent according to any one of claims 1 to 5 , wherein the method is characterized by the above. The method for producing a detection gas generating agent according to any one of claims 1 to 8 , wherein the solid metal is at least one metal selected from the group consisting of Si, W, Mo and Ge. The method for producing a detection gas generating agent according to claim 1 , wherein the solid metal is silicon, which is obtained by pulverizing the silicon ingot.

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