JP2005345338A - Coating film pigment for hydrogen gas detection, coating film for hydrogen gas detection, and hydrogen gas detection tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating film pigment for hydrogen gas detection, a coating film for hydrogen gas detection, and a hydrogen gas detection tape capable of detecting a leak spot of hydrogen gas on a pipe, a container or the like with high sensitivity. <P>SOLUTION: The coating film for hydrogen gas detection and the hydrogen gas detection tape including a pigment constituted of an aggregate 6 of crystal particles mainly composed of tungstic oxide and including a catalyst metal 2 in the oxidation state on the surface of the crystal particle tungstic oxide are applied on the surface of a gas pipe, a container or the like containing hydrogen gas, and reduced by injection of protons generated by dissociation of the hydrogen gas, to thereby detect a hydrogen gas leak by a hue change. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrogen gas detection pigment, a hydrogen gas detection paint, and a hydrogen gas detection tape for use in containers, pipes, automobiles, fuel cells, hydrogen fuel reformers and the like that need to be monitored for hydrogen gas leakage for safety. Hydrogen gas leakage is detected by utilizing a hue change in which the color of tungsten oxide changes from light yellow to dark blue at the time of leakage.

Hydrogen gas sensors include semiconductor sensors, solid electrolyte sensors, contact heat conversion sensors, heat conduction sensors, light detection sensors, and other sensors that detect hydrogen optically in optical waveguides and optical fiber cladding. Although there is a surface sensor having a film, it is difficult to find a gas leak point containing hydrogen. With the liberalization of gas and the advent of the hydrogen fuel society, hydrogen gas leak detection is possible in the temperature range of -20 ° C to 50 ° C, environmental resistance that does not depend on temperature and humidity, etc. A hydrogen gas detection pigment and a hydrogen gas detection tape that are easy to handle are desired. As a conventional hydrogen gas leakage detection tape, a gas detection tape is used in which hydrogen gas is adsorbed and dissociated to generate protons, and a metal compound whose light absorption characteristics are changed by the protons is used as a pigment. As metal compounds that can be used in such hydrogen gas detection pigments, there have been examples in which metal chlorides have been used before, but currently solid oxides are the mainstream. In the hydrogen gas leakage detection material, palladium chloride (PdCl ₂ ) is used as a metal chloride that shows a change in hue when hydrogen gas leakage is detected. On the other hand, manganese oxide (MnO), copper oxide (Cu ₂ O), lead oxide (PbO), lead dioxide (PbO ₂ ), palladium oxide (PdO ₂ ), tungsten trioxide (WO ₃ ) are known as solid oxides. ing.

As a method for detecting leakage of hydrogen gas, it was common to use a filter paper immersed in a palladium chloride (PdCl ₂ ) solution and dried. Below, there is a defect that the detection speed of hydrogen gas is rapidly deteriorated by light, and in some cases, there is a problem that a light shielding function is required. This is because palladium oxide undergoes a photochemical reaction when exposed to light, chlorine is activated, palladium chloride is denatured, and reactivity due to hydrogenation deteriorates.

In view of the above disadvantages, there is a proposal of a hydrogen gas leakage detection paper in which a detection paper coated with palladium oxide (II) hydrate (PdO _x · H ₂ O) is coated with a film of plastic or the like and a plastic film is applied.

  In the case of the detection paper, the brown palladium oxide hydrate is reduced by hydrogen and turns black. However, in the case of hydrogen gas detection paper using palladium oxide hydrate, the degree of hue change of palladium oxide hydrate is small, and the hue change of palladium oxide is detected by the hue of the material to be coated or by the hiding power of the pigment of the paint. There is a problem that it is difficult to perform (see, for example, Patent Document 1; see Japanese Patent Publication No. 57-57977).

In order to make the proposed hue change clearer, a hydrogen gas leak detection agent in which the surface of white fine particle inorganic powder such as titanium oxide (TiO ₂ ) is coated with palladium oxide hydrate so as not to inhibit the discoloration of palladium oxide. An adhesive tape-like structure has been proposed. According to the disclosed example, hydrogen gas gas is formed by sequentially laminating a pressure-sensitive adhesive layer (A), a base sheet layer (B), and a hydrogen gas detection layer (C) containing titanium oxide coated with palladium oxide hydrate. The detection adhesive tape is proposed (for example, patent document 2; Unexamined-Japanese-Patent No. 8-253742). However, this hydrogen gas leakage paint has a problem that when used outdoors, titanium oxide is activated and altered due to ultraviolet rays, and the hydrogen gas sensitivity deteriorates.

In addition, there are a light detection type sensor using a hue change caused by hydrogen gas of tungsten oxide (WO ₃ ) and a gas sensor using a semiconductor type in which the electrical resistance of tungsten oxide changes by proton (H ⁺ ). Tungsten oxide is light yellowish green, but when protons are injected, tungsten bronze (H _x WO ₃ ) is generated, and tungsten oxide exhibits a hue change to dark blue. However, tungsten oxide (WO ₃ ) alone does not have a dissociation ability to generate protons from hydrogen gas at room temperature of 23 ° C. to 25 ° C., and the catalyst metal is changed to tungsten oxide with the aim of improving the detection ability of hydrogen gas leaking portions at room temperature. Attempts have been made to adhere to (WO ₃ ). John E.M. Benson, H.M. W. Kohn, and Michael Boudart et al. Have found that platinum oxide (Pt) is supported on tungsten oxide and that the amount of adsorbed hydrogen increases when exposed to hydrogen at room temperature. The crystalline state of tungsten oxide, the crystalline state of platinum, and the hydrogen gas Is not mentioned (Non-patent Document 1, JOUNAL OF CATALYSIS Vol. 5, pp 307-313 (1966)).

To realize a hydrogen gas leakage film that can operate at room temperature, a tungsten oxide thin film with an increased crystal plane of the tungsten oxide X-ray diffraction pattern (001) index was formed, focusing on the crystalline state of tungsten oxide. There has been disclosed a hydrogen gas sensor comprising a laminated structure in which an oxidation catalyst metal thin film is provided on a thin film. It is stated that the variation in the amount of light absorption at the time of hydrogen gas leakage can be reduced by forming a crystalline tungsten oxide thin film having high orientation in the X-ray diffraction pattern index (001). The X-ray diffraction intensity of the X-ray diffraction pattern index (001) increases with an increase in the calcining temperature of the tungsten oxide thin film, but the hydrogen gas sensitivity does not increase monotonously. Further, this patent does not disclose the relationship between the hydrogen gas sensitivity and the X-ray diffraction intensity of the crystal plane of the X-ray diffraction pattern index (001). Further, when a palladium thin film is used as the catalytic metal thin film, there is a problem that the hydrogen gas detection sensitivity deteriorates due to the weakness of the palladium thin film due to hydrogenation when the hydrogen leakage cycle test is performed. On the other hand, when a platinum thin film is used as a catalytic metal thin film according to another embodiment, there is a problem that variations in detection sensitivity of hydrogen gas occur. This is considered because the hydrogen gas which should be measured on a platinum thin film is oxidized and water is produced. (See JP-A-62-257047)
Concerning hydrogen gas leakage detection film, it contains multiple solid oxides that have a hue change when hydrogen gas leaks at different temperatures, using alkoxysilane as binder, hydrochloric acid as catalyst, ethyl alcohol, water and isopropyl alcohol as solvent There is a proposal of a fuel gas leak detection film that is stable from a normal temperature to a high temperature of 500 ° C. by manufacturing. However, this method has a problem that the detection speed of hydrogen gas is slow at room temperature, the detection sensitivity of hydrogen gas is low, and leakage of low concentration hydrogen gas cannot be detected. (See JP 2000-044840 A)
Japanese Patent Publication No.57-557977 JP-A-8-253742 John E.M. Benson, H.M. W. Kohn, and by Michel Boudart, JOUNAL OF CATALYSIS Vol. 5, 1966, pages 307-313 JP-A-62-257047 JP 2000-044840 A

  However, the gas leakage point detection agent and the leakage point detection tape containing hydrogen according to the conventional configuration have a practical problem that the hydrogen gas leakage detection sensitivity near room temperature is low and the response speed is very slow. It was.

 In view of the above prior art, the present invention is composed of an aggregate of crystalline fine particle tungsten oxide containing a catalytic metal in an oxidized state on the surface in order to solve the problem of a paint film pigment for detecting a hue change type hydrogen gas. This makes it possible to increase the sensitivity of hydrogen gas detection and improve the response speed.

  The present invention also includes a hydrogen gas detection pigment that achieves both high sensitivity and high speed response of hydrogen gas leakage detection at around room temperature, and further includes a coating film pigment for hydrogen gas detection using the present invention. An object of the present invention is to provide a tape capable of easily detecting a minute leak location of a gas containing hydrogen by making the paint to be adhered into a tape-like shape.

  In order to solve the conventional problems, the coating film pigment for hydrogen gas detection of the present invention is applied to the surface of a gas pipe or container containing hydrogen gas, and protons generated by dissociating hydrogen gas are injected. A coating film pigment for detecting hydrogen gas that is reduced and changes its hue, the pigment comprising an aggregate of crystalline fine particles mainly composed of tungsten oxide, and a catalytic metal in an oxidized state on the surface of the crystalline fine particle tungsten oxide. It is characterized by containing.

  In addition, the hydrogen gas detection coating film of the present invention is applied to the surface of a gas pipe or container containing hydrogen gas, and protons generated by dissociating the hydrogen gas are injected and reduced to change the color of the hydrogen gas. In the coating film, the particulate tungsten oxide crystallized as a pigment component of the coating film, an oxidized catalytic metal on the surface of the particulate tungsten oxide, and a vehicle as a coating component of the coating film It is what.

  In addition, the hydrogen gas detection tape of the present invention is applied to the surface of a gas pipe or container containing hydrogen gas, and protons generated by dissociating the hydrogen gas are injected and reduced to change the hue of the hydrogen gas detection tape. The film contains fine particle tungsten oxide crystallized as a pigment component of the coating film, a catalytic metal in an oxidized state on the surface of the fine particle tungsten oxide, and includes a vehicle as a coating component of the coating film. Is.

  Further, the hydrogen gas detection tape of the present invention sequentially comprises an adhesive layer, a base sheet layer, and a hydrogen gas detection layer containing a pigment that is reduced by a proton injected by dissociating the hydrogen gas to change its hue. A hydrogen gas detection tape formed by laminating, wherein the pigment is composed of an aggregate of crystalline fine particles mainly composed of tungsten oxide, and contains a catalytic metal in an oxidized state on the surface of the crystalline fine particle tungsten oxide. It is a feature.

  Further, the hydrogen gas detection tape of the present invention sequentially comprises an adhesive layer, a base sheet layer, and a hydrogen gas detection layer containing a pigment that is reduced by a proton injected by dissociating the hydrogen gas to change its hue. A hydrogen gas detection tape that is laminated and further has a protective film laminated on the hydrogen gas detection layer, wherein the pigment comprises an aggregate of crystal fine particles mainly composed of tungsten oxide, and the crystal fine particles The surface of tungsten oxide contains an oxidized catalytic metal.

  In addition, the hydrogen gas detection tape of the present invention sequentially includes an adhesive layer, a hydrogen gas detection layer containing a pigment that is reduced by a proton injected by dissociating the hydrogen gas and undergoes a hue change, and a base sheet layer. A hydrogen gas detection tape formed by laminating a catalyst metal in an oxidized state on the surface of the crystalline fine particle tungsten oxide.

  As described above, according to the present invention, a coating film pigment for hydrogen gas detection that changes hue with high sensitivity to hydrogen gas in the vicinity of −20 ° C. to 50 ° C. is realized. By making the paint to be contained into a tape that can be adhered, it is possible to easily detect the location of hydrogen gas leakage. Moreover, the complexity of the painting work to the existing structure and piping part which has a complicated structure and shape can be eliminated by using a tape.

  As a result of various studies on the synthesis conditions of tungsten oxide, which is a coating pigment for hydrogen leakage detection, for the purpose of increasing the hue change due to hydrogen gas leakage, tungsten oxide was made into fine particles, the crystalline state of the fine tungsten oxide, Average particle diameter, oxygen defect state of fine particle tungsten oxide, atomic ratio of oxygen to tungsten of fine particle tungsten oxide, oxidation state of catalytic metal contained on fine particle tungsten oxide surface, type of catalytic metal, and catalytic metal The inventors have found that there is an optimum condition for the average particle diameter of the particles.

  The pigment of the coating film that changes its hue when hydrogen gas leakage is detected contains an aggregate of fine particles mainly composed of tungsten oxide having an average particle size of 15 nm to 80 nm. The surface area that can be supported can be increased.

By bringing the catalytic metal into an oxidized state, the catalytic metal has an increased ability to withdraw electrons (electron acceptor), increasing the rate of adsorption and dissociation of hydrogen gas (H ₂ ) on the catalytic metal, and protons (H ⁺ ). By increasing the generation rate of hydrogen, both hydrogen gas detection speed and detection sensitivity are improved. Therefore, high-speed response and high sensitivity can be realized in hydrogen gas detection. Furthermore, in the fine particle tungsten oxide, by controlling the structure of the tungsten oxide, the number of oxygen defects (vacancy) in the fine particle tungsten oxide can be optimized, and the hydrogen detection sensitivity can be improved. This oxygen defect acts as a proton conduction channel and causes an increase in the electron carrier concentration. Both effects increase the speed of the hue change of the coating pigment for hydrogen gas detection and the hydrogen gas detection tape, and increase the detection sensitivity. .

Protons and electrons generated on the catalyst metal respectively move through oxygen defects (vacancy) of the fine particle tungsten oxide, which is the main component of the hydrogen gas detection film, and at that time, tungsten (W) of the fine particle tungsten oxide becomes W ^6+. Is reduced to W ⁵⁺ to form tungsten bronze (H _x WO ₃ ). When tungsten bronze is formed from the tungsten oxide, the color of the gas detection film changes from light yellowish green to dark blue, so that hydrogen gas leakage detection by hue change is possible. When tungsten bronze is formed from this tungsten oxide, the electrical conductivity of the thin film composed of the fine particle tungsten oxide also increases by several orders of magnitude, so that hydrogen gas leakage can be detected by a change in electrical resistance.

  Below, the coating film pigment for hydrogen gas detection, the coating film for hydrogen gas detection, and the hydrogen gas detection tape using the same are demonstrated in detail using drawing.

  FIG. 1 shows that a hydrogen gas detection coating film 5 containing a hydrogen gas detection coating pigment 4 is applied to a surface to be measured (container or pipe) 7 at a place where there is a risk of hydrogen gas leakage in Example 1 of the present invention. It is the dried sectional view, Comprising: The coating film 5 for hydrogen gas detection is expanded for description. FIG. 1 shows a case where hydrogen gas 8 existing in a container or piping leaks and flows out to the hydrogen gas detection coating film 5 as indicated by an arrow 9.

  The hydrogen gas detection coating film 5 of the present invention comprises an assembly 6 of hydrogen gas detection coating pigments 4 and a coating film forming component vehicle 3. The film thickness of the coating film 5 for detecting hydrogen gas is suitably about 2 μm to 100 μm, particularly 5 μm to 30 μm. The coating film 5 for detecting hydrogen gas is composed of an aggregate 6 of fine particle tungsten oxide 1 having a particle diameter of 15 nm to 80 nm. The particle size of the aggregate 6 is 50 μm or less, and particularly preferably 10 μm or less. The surface of the fine particle tungsten oxide 1 has a catalyst metal 2 having a particle diameter of 2 nm to 35 nm. The particle size of the fine particle tungsten oxide 1 is preferably larger than the particle size of the fine particle of the catalyst metal 2. The larger the area of the catalyst metal 2 exposed on the surface of the fine particle tungsten oxide, the greater the adsorption / dissociation action of hydrogen gas, The amount of proton generation increases and the hue change increases. Although FIG. 1 shows that a plurality of metal catalysts 2 exist on the surface of the fine particle tungsten oxide 1, the number of catalyst metals on the surface of the fine particle tungsten oxide is not limited.

  As the hydrogen gas detection pigment 1 contained in the hydrogen gas detection coating film 5, a sol-gel method, a hydrothermal method, or the like is used, but a sol-gel method that easily forms a porous pigment is preferable.

Method for producing a coating pigment for hydrogen gas detection by sol-gel method, for example, tungstic acid (H ₂ WO ₄₎ 2.5g was dissolve in methanol 31 ml, and stirred at room temperature for 30 minutes, pure water 18ml was added Further, a predetermined amount of a catalytic metal salt aqueous solution is added to obtain a colloidal solution of tungstic acid (H ₂ WO ₄ ). For example, when platinum is used as a catalyst metal, a chloroplatinic acid aqueous solution (H ₂ [PtCl ₆ ] .xH ₂ O) is added to a tungsten acid colloid solution in a ratio of 0.3 to 30 mol% with respect to tungsten. Then, a tungstic acid colloidal solution containing a catalytic metal is obtained.

In the above sol-gel synthesis, methanol was used as the reducing agent, but it is not limited to methanol, and various reducing agents such as ethanol, propanol, and glucose can be used. Can be controlled. Here, the hydrogen of the tungstic acid and the hydroxyl group of the reducing agent react with each other to cause dehydration condensation, and the tungsten oxide starts to gel. Stabilization of the sol-gel state of tungsten oxide can be controlled by utilizing the difference in the dissociation rate of hydroxyl groups depending on each reducing agent. Further, as a precursor of tungstic acid, an aqueous solution of sodium tungstate (Na ₂ WO ₄ ) may be used, and tungstic acid may be obtained by H ⁺ ion exchange resin.

  Further, alkoxide tungsten may be used as a precursor of tungstic acid.

A colloidal solution of tungstic acid (H ₂ WO ₄ ) can be obtained from anhydrous chlorotungsten (WCl ₆ ) and anhydrous ethanol. Furthermore, the catalyst metal salt may be an inorganic salt or an organic salt. For example, inorganic salts include chloride salts, nitrate salts, sulfate salts, etc., and organic salts include carboxylate salts, dicarboxylate salts, and acetylacetone complex salts.

  After that, by calcining for 5 hours at a calcining temperature of 350 ° C. to 700 ° C. in a flow state of air of 50 ml / min, the platinum catalyst metal 2 is partially contained on the surface, and the tungsten oxide 1 is crystallized. The crystallized fine particle tungsten oxide aggregate 6 is formed.

  When the calcining temperature is 350 ° C. or lower, for example, 250 ° C. and calcining is performed for 5 hours in a flow state of air 50 ml / min, the particle size of the fine tungsten oxide 1 is smaller than that at 500 ° C. It becomes smaller and a polycrystalline fine particle tungsten oxide is obtained.

  On the other hand, if the calcination temperature is 700 ° C. or higher and the calcination treatment is performed for 5 hours in a flow state of air 50 ml / min, the particle size of the fine particle tungsten oxide 1 increases as the calcination temperature increases.

  Next, the manufacturing method of the coating film 5 for hydrogen gas detection is shown. A lump of fine crystalline tungsten oxide 1 containing platinum catalyst metal on the surface produced by the above sol-gel method is pulverized into an aggregate 6 having a particle size of 0.1 to 10 micrometers by a roll mill to detect hydrogen gas. A coating pigment is obtained.

  On the other hand, as the coating film forming component vehicle 3, various known ones can be used. For example, natural resins such as shellac and copal, processed resins such as rosin ester; synthetic resins such as phenol resin, urea resin, melamine resin, phthalic acid resin, acrylic resin, epoxy resin and vinyl resin, cell source derivatives such as acetyl cellulose Rubber derivatives such as chlorinated rubber and synthetic rubber, and water-soluble compounds such as polyvinyl alcohol, casein, and carboxymethyl cellulose can be used. Of these, acrylic resins and phthalic acid resins are preferred.

Moreover, you may contain a light-scattering agent in order to suppress the dependence of the hue of a to-be-measured surface, and to utilize external light. The light scattering agent is preferably an inorganic and / or organic fine particle having a particle size smaller than that of the pigment aggregate. As the inorganic light scattering agent, for example, SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , ZnO or the like can be used. Further, as the organic light scattering agent, fine particles made of a resin of the above-mentioned coating film forming component vehicle component can be used, and fine particles made of a resin having a component having a different optical refractive index from that of the vehicle main component are preferable.

  In addition, various additives known for dispersion of paints, drying and curing of coating films, and improvement of properties such as drying accelerators such as lead naphthenate, manganese naphthenate, cobalt naphthenate, etc., curing agents; plasticizers such as , Dibutyl phthalate, castor oil, etc .; dispersants such as surfactants, lecithin, etc .; emulsifiers; rust preventives such as zinc chromate, etc .; skin tension inhibitors such as methyl ethyl ketoxime, phenols, etc .; thickeners; Etc. can be added. As the solvent or diluent, a known solvent or dispersion medium suitable for forming a coating film such as mineral spirits, xylene, and toluene can be used. Specifically, the more specific composition ratio of the paint having a hydrogen gas detection pigment is 2 to 80% by weight, preferably 10 to 60% by weight of the coating gas pigment for hydrogen gas detection per 100% by weight of the resin component. % Range.

  An example of a specific composition of the hydrogen gas detection layer was blended based on the following coating composition.

Phthalic acid resin varnish (trade name: phthalit varnish manufactured by Kansai Paint) = 15% by weight,
Melamine resin liquid (trade name: Delicon # 300, manufactured by Dainippon Paint) = 20% by weight
SiO2 = 15 wt%, the present invention hydrogen detection pigment = 20 wt%,
Xylene / toluene, etc. Weight ratio = 29 wt%, Dispersant = 1 wt%
FIG. 5 shows a measurement system for evaluating the hydrogen gas leakage detection sensitivity of the hydrogen gas detection coating film 22 (22 in FIG. 5 is the same as the hydrogen gas detection layer 5 in FIG. 1). The hydrogen gas detection paint synthesized above was applied to the quartz substrate 21 by spin coating so as to have a film thickness of 5 μm. Thereafter, the sample 28 for evaluation was prepared by drying at 90 ° C. with a dryer. A white light source 23 and a photodetector 26 are provided in a sealed chamber 27 with an evaluation sample 28 sandwiched therebetween, and the incident light 24 is arranged to be perpendicularly incident on the hydrogen gas detection coating film 22 of the evaluation sample. Then, from the transmitted light 25, the optical spectral characteristics with and without 1% hydrogen gas were measured in the air.

  FIG. 6 shows the spectral characteristics of the coating film 22 for detecting hydrogen gas according to the present invention when exposed to 1% hydrogen gas in the air and without hydrogen gas. As can be seen from FIG. 6, optical absorption is exhibited in the wavelength region of optical wavelength of about 400 nm or more due to the 1% hydrogen gas concentration in the air. That is, since the transmittance decreases in the long wavelength region of optical wavelength of 400 nm or more, it can be seen that the color of the fine particle tungsten oxide of the hydrogen detection layer exhibits a hue change from light yellow green to dark blue. The hydrogen gas leakage sensitivity is calculated by using the evaluation system shown in FIG. 5 to calculate the amount of light absorption calculated from the light output of the photodetector 26 = (output at 1% hydrogen gas concentration in the air) / (output without hydrogen gas). And measured. As a measure of hydrogen gas leakage detection, a value capable of identifying the hue is 0.2 or more, preferably 0.3 or more.

  The intensity of the hue change depends on the composition ratio of the hydrogen gas detection pigment 4 which is a material of the hydrogen gas detection coating film 5 and the coating film forming component vehicle 3. If the hydrogen gas leakage detection sensitivity of the hydrogen gas detection pigment 4 is improved, the sensitivity of the hydrogen gas detection coating film 5 is naturally improved. Therefore, in order to investigate the optimum structure of the coating film 5 for detecting hydrogen gas, the following examination was conducted on the structure of the coating film pigment 4 for detecting hydrogen gas that does not contain the coating film forming component vehicle 3. That is, in FIG. 5, a coating film 22 for detecting hydrogen gas that does not contain the coating film forming component vehicle 3 is prepared and the sample 28 is used to measure the amount of light absorbed when exposed to a 1% hydrogen gas concentration in the air and the hydrogen gas detecting coating film. The relationship with the structure of the coating film pigment 4 for detecting hydrogen gas constituting the film 22 was clarified.

The hydrogen gas detection coating film 22 used for the measurement of the hydrogen gas sensitivity characteristics was prepared by dissolving 2.5 g of tungstic acid (H ₂ WO ₄ ) in 31 ml of methanol and agitating for 30 minutes at room temperature during sol-gel synthesis. A colloidal solution was prepared by adding 18 ml of water. Platinum is used as the catalyst metal, and 8 ml of 0.0125 mol / l of chloroplatinic acid aqueous solution is added to the colloidal solution of tungstic acid to spin the colloidal solution of tungstic acid containing the platinum catalyzed chlorinated solution onto the quartz substrate 21. The sample was applied by coating, and heated for 5 hours in the range of 300 ° C. to 800 ° C. in a flow state of 50 ml / min of air as the calcining treatment condition, to prepare Sample 28. The film thickness of the hydrogen gas detection coating film 21 is about 0.3 μm.

  When the sample 28 under each calcining treatment condition was observed using a scanning electron microscope (SEM), the coating film 22 for hydrogen gas detection formed an aggregate 6 composed of the fine particle tungsten oxide 1, and the fine particle tungsten oxide. It was found that the platinum catalyst metal 2 was contained on the surface.

  FIG. 7A shows the relationship between the average particle diameter of the fine particle tungsten oxide 1 and the detection sensitivity (light absorption amount) of hydrogen gas. The average particle size of the fine particle tungsten oxide 1 was calculated from the frequency distribution of the particle size of about 100 fine particles of tungsten oxide. The hydrogen gas detection sensitivity is a light absorption amount obtained from the photodetector 26 by introducing 1% hydrogen gas in the air into the chamber 27 using the measurement system of FIG. The average particle diameter of the fine particle tungsten oxide 1 can be controlled by the calcination temperature and the time in the sol-gel synthesis when forming the fine particle tungsten oxide. As can be seen from FIG. 7 (A), the fine tungsten oxide 1 constituting the hydrogen gas detection coating film 22 of the present invention is light generated by hydrogen gas when the average particle diameter (shorter length) is 15 nm to 80 nm. Absorption of 0.3 or more is obtained. The reason for improving the detection sensitivity of hydrogen gas is that the surface area on which the catalytic metal 2 can be adsorbed can be increased by increasing the average particle size of the particulate tungsten oxide from 15 nm to 80 nm, thereby realizing high sensitivity of the hydrogen gas. is there. On the other hand, when the average particle size of the fine particle tungsten oxide 1 is smaller than 15 nm, the surface area on which the catalytic metal 2 can be adsorbed decreases, and the amount of light absorption decreases and the hue changes because the scattering of protons and electrons in the tungsten oxide increases. Less.

FIG. 7B shows the average particle size of the fine particle tungsten oxide 1 and the detection response of hydrogen gas. In the hydrogen gas detection characteristic evaluation system of FIG. 5, the hydrogen gas detection responsiveness is the maximum light absorption amount obtained from the output of the photodetector 26 by introducing 1% hydrogen gas in the air from the gas inlet 29. The time to 90% was measured as T90. As can be seen from FIG. 7B, similarly to hydrogen gas detection sensitivity FIG. 7A, T90 = about 70 seconds or less can be obtained when the average particle diameter of the particulate tungsten oxide 1 is 15 nm to 80 nm. all right. The reason for speeding up is that, as in the case of high sensitivity, the catalytic metal 2 on the crystalline fine particle tungsten oxide 1 is brought into an oxidized state, whereby the catalytic metal 2 has an increased ability to withdraw electrons (electron acceptor), and hydrogen gas ( The rate at which H ₂ ) is adsorbed on the catalytic metal and dissociated into protons (H +) is increased, and the crystalline fine particle tungsten oxide 1 has oxygen vacancies described later, so that the dissociated proton (H +) is converted into tungsten oxide 1. This is thought to be easier to move inside.

  FIG. 8 shows the ratio of the number of oxygen atoms to the number of tungsten atoms constituting the fine-particle tungsten oxide determined by X-ray photoelectron spectroscopy (XPS) measurement | O | / | W | and the detection sensitivity dependence of hydrogen gas. Indicates. The ratio between the number of oxygen atoms and the number of tungsten atoms is 15 KV, 300 W using an X-ray electron spectrometer (model number AXIS-HSU) manufactured by Shimadzu, and MgKα: 1253.6 eV is used as the X-ray source. The hydrogen gas detection coating film 5 used for the evaluation was only a hydrogen gas detection coating film pigment not containing the coating film forming component vehicle 3, and a hydrogen gas detection coating film 22 was synthesized by the following sol-gel method.

2.5 g of tungstic acid (H ₂ WO ₄ ) is melted in 31 ml of methanol, stirred for 30 minutes at room temperature, and 18 ml of pure water is added to prepare a colloidal solution. Platinum is used as the catalyst metal, and 1.8 ml, 3.6 ml, and 11 ml of 0.1 mol / l chloroplatinic acid aqueous solution are added to the colloidal solution of tungstic acid, and the ratio of the platinum catalyst to tungsten is 1.8 mol. %, 3.6 mol%, and 11 mol% of a tungstic acid colloid solution containing a platinum catalyst were synthesized, applied to the quartz substrate 21 by spin coating, and then calcined. In the calcining treatment, calcining was performed for 5 hours at a calcining temperature of 350 ° C. to 700 ° C. in a flow state of 50 ml / min.

  From FIG. 8, the ratio | O | / | W | of the number of oxygen atoms and the number of tungsten atoms constituting the fine particle tungsten oxide is increased from 350 ° C. to 700 ° C. without depending on the molar ratio of the platinum catalyst. Increase with increasing In addition, since the ratio | O | / | W | of the number of oxygen atoms and the number of tungsten atoms constituting the fine-particle tungsten oxide is not an integer ratio of 3, the fine-particle tungsten oxide is understood to contain oxygen defects (vacancy). . In particular, when the ratio of the platinum catalyst to tungsten is 1.8 mol%, the ratio of the number of oxygen atoms to the number of tungsten atoms | O | / | W | is 2.54, and the light absorption amount is 0.3 or more. When | O | / | W | is 2.60, the maximum light absorption amount is 0.52, and then the light absorption amount decreases. Therefore, when the ratio of the platinum catalyst to tungsten is 1.8 mol%, the ratio of the number of oxygen atoms to the number of tungsten atoms | O | / | W | is for hydrogen gas detection when the ratio | O | / | W | The coating film pigment 4 is preferable as the coating film 22 for detecting hydrogen gas.

  When the ratio of the platinum catalyst to tungsten is 3.6 mol%, the ratio of the number of oxygen atoms to the number of tungsten atoms | O | / | W | is 2.54 to 2.63, and the light absorption amount is 0.4 or more. Is obtained.

  When the ratio of the platinum catalyst to tungsten is increased to 11 mol% or more, the light absorption amount decreases. The inventors speculate that this is because as the ratio of the platinum catalyst to tungsten increases, the platinum particles 2 agglomerate and the particles become enormous, and the surface area of the catalytic metal 2 on which hydrogen gas is adsorbed decreases.

  The improvement in the hydrogen gas detection sensitivity due to the oxygen defects is because the change in hue increases because the electron carrier concentration increases due to the increase in oxygen defects in the fine-particle tungsten oxide.

  The reason why the hydrogen gas detection sensitivity decreases in a region where there are many oxygen defects, that is, where | O | / | W | is small, is that the particles of tungsten oxide are too small due to the low calcining temperature, and at the grain boundaries of tungsten oxide. It is presumed that the change in hue due to hydrogen gas is small because the proton and electron scattering of the hydrogen becomes dominant over the conduction.

  On the other hand, when | O | / | W | is increased, the hydrogen gas detection sensitivity decreases. When | O | / | W | is 2.60 or more, the calcining temperature is heated to 600 ° C. or more. At the calcining temperature within that range, as the temperature increases, the oxygen defects decrease due to the progress of oxidation, and the electron carrier concentration decreases, and the average particle diameter of the fine particle tungsten oxide 1 increases as the temperature increases. The increase is interpreted as agglomeration of the tungsten oxide 1 and a decrease in the surface area of the tungsten oxide 1, thereby reducing the amount of catalytic metal adsorbed on the tungsten oxide surface.

  Therefore, it is interpreted that there is an optimal ratio of the number of oxygen atoms to the number of tungsten atoms | O | / | W | for hue change caused by hydrogen gas.

  FIG. 9 shows an X-ray diffraction pattern of crystalline fine particle tungsten oxide constituting the hydrogen gas detecting coating film 22 used in the present invention. Here, the catalyst metal 2 is platinum, and the ratio with respect to tungsten is 3 mol%. The legend of each X-ray diffraction pattern is the calcining temperature when the hydrogen gas detection coating film 22 is manufactured. The X-ray diffraction measurement sample 28 does not include the coating film forming component vehicle 3. Specifically, a colloidal solution of tungstic acid in which the ratio of platinum to tungsten is 3 mol% is spin-coated on a quartz substrate 21 and applied as a calcining condition in a flow state of air 50 ml / min as shown in FIG. The sample for X-ray diffraction was produced by heating at each calcining treatment temperature for 5 hours. As can be seen from the X-ray diffraction pattern of FIG. 9, an X-ray diffraction main peak of tungsten oxide is seen at an X-ray diffraction angle 2θ = 20 ° to 30 °, and at a wider angle than the X-ray diffraction angle 2θ = 30 °, From the fact that high-order X-ray diffraction peaks are observed, it can be seen that the hydrogen gas detection coating film 22 has a crystal structure. In particular, 2θ = 24.2 ° corresponds to the triclinic main diffraction peak crystal lattice plane index (200) of tungsten oxide, and 2θ = 23.1 ° is a monoclinic system of tungsten oxide. The main diffraction peak crystal lattice plane index (001). In FIG. 3, a triclinic peak (020) of tungsten oxide is also shown.

  FIG. 10 shows the ratio of triclinic and monoclinic X-ray diffraction main peaks of tungsten oxide obtained from the X-ray diffraction pattern of tungsten oxide in FIG. 9 (= (001) / ( 200) and the light absorption amount at 1% hydrogen gas concentration in the air obtained using the evaluation system of Fig. 5. From Fig. 10, the ratio of the main peak (= (001) / (200)). Is set to 0.53 to 0.94, a light absorption amount of 0.3 or more at a 1% hydrogen concentration in the air can be obtained, and the mechanism for improving the hue change is estimated as follows. When the fine crystalline tungsten oxide has two crystal phases, a shear defect is formed at the interface between the crystal phases, and oxygen defects are easily formed in the altered layer, and the electron concentration increases. In addition, a proton transfer path is easily formed, so that a high mobility of proton conduction is obtained and the hue change is improved, where triclinic and monoclinic systems are used here. The ratio of the main peak of the X-ray diffraction pattern is an index indicating that at least two crystal phases are mixed, and the present invention is a triclinic main diffraction peak crystal lattice of the tungsten oxide hydrogen detection film 6. It is not limited to the plane index (200) and the monoclinic main diffraction peak crystal lattice plane index (001), that is, in the hydrogen gas detection pigment, an oxidized catalytic metal is formed on the surface. When the contained fine crystalline tungsten oxide contains at least two crystal phases, the hydrogen gas detection sensitivity increases. This is to explain this.

  Next, the state of the catalyst metal 2 in the hydrogen gas detection pigment 4 and the hydrogen gas leakage detection sensitivity were examined. Specifically, the oxidation state of the platinum catalyst metal contained in the crystalline fine particle tungsten oxide 1 was examined using X-ray photoelectron spectroscopy (XPS) measurement. The XPS apparatus used for the measurement is the same as the apparatus used for evaluating the oxygen defects of the fine-particle tungsten oxide. The sample did not contain the coating film forming component vehicle 3 but only the coating film pigment 4 for hydrogen gas detection, and was synthesized by the method described below.

2.5 g of tungstic acid (H ₂ WO ₄ ) is melted in 31 ml of methanol, stirred for 30 minutes at room temperature, and 18 ml of pure water is added to prepare a colloidal solution. Platinum is used as the catalyst metal, 4 ml of a chloroplatinic acid (H ₂ (PtCl ₆ )) solution having a concentration of 0.1 mol / l is added to the colloidal solution of tungstic acid, and the ratio of the platinum catalyst to tungsten is 4 mol%. A tungstic acid colloid solution containing a platinum catalyst was synthesized, and the tungstic acid colloid solution was applied onto the quartz substrate 21 by spin coating. In particular, the calcination treatment is performed in a flow state of 50 ml / min of air at a calcining temperature of 350 ° C. to 700 ° C. for 5 hours, and by optimizing oxygen defects of the fine particle tungsten oxide by the calcining temperature, The oxidation state of some platinum was controlled.

  The leakage detection sensitivity of hydrogen gas was evaluated by the presence or absence of a hydrogen gas concentration in the air of 1% by the light absorption measurement system used in FIG.

FIG. 11 shows an X-ray photoelectron spectroscopy (XPS) spectrum of the platinum catalyst metal contained in the surface of the fine crystalline tungsten oxide constituting the coating film 22 for detecting hydrogen gas. In the X-ray photoelectron spectroscopy (XPS) spectrum of FIG. 11, it has an electronic state 4f _2/7 peak (Pt ⁰ ) of metallic platinum that is not oxidized to a binding energy of 70.9 eV. Oxidized platinum chemically shifts to a higher energy side by bonding with oxygen, and exhibits a bivalent oxidized platinum (PtO) peak at a binding energy of 73.7 eV. Further, oxidation progresses, and a peak appears at a binding energy of 74.5 eV in platinum (PtO ₂ ) in a tetravalent oxidation state. X-ray photoelectron spectroscopy (XPS) spectrum of the obtained platinum catalyst metal is subjected to peak separation for each peak in the metal state (Pt ⁰ ), divalent oxidation state (PtO), and tetravalent oxidation state (PtO ₂ ). . An example of each peak separation is shown by dotted lines in FIG. Here, as the definition of the oxidation state of the platinum catalyst, the peak area appearing at the binding energy position 70.9 eV of the electronic state 4f _2/7 of platinum in FIG. 1 and the peak area of the binding energy 73.7 eV of the divalent oxidation state platinum are shown. And the sum of the peak areas appearing at 74.5 eV of the binding energy of tetravalent oxidation state platinum, that is, using the expression (XPS (1) / XPS (2)) × 100 (%), Calculate the percentage.

  Here, XPS (1) = XPS peak area in the platinum oxidation state, XPS (2) = XPS platinum metal state peak area + XPS oxidation state peak area.

  FIG. 12 shows the relationship between the oxidation state of the platinum catalyst metal and the light absorption obtained from FIG. As can be seen from FIG. 12, the light absorption amount is 0.3 or more when the oxidation state of the platinum metal catalyst is 28% to 78%.

  Furthermore, the average particle diameter of the platinum catalyst metal obtained by measuring the average particle diameter of 100 platinum catalyst metals to be baked using a scanning electron microscope (SEM) and the light absorption at 1% hydrogen gas concentration in the air The relationship with quantity was investigated. As a result, it was found that the light absorption amount was 0.3 or more when the average particle diameter of the platinum catalyst metal was 2 to 35 nm. Note that the average particle diameter of the platinum catalyst metal also increases with an increase in the calcining temperature, and also increases with the ratio of the platinum catalyst metal to tungsten.

  The additive as the catalyst metal is not limited to the chloride salt as in Example 1, but may be an inorganic salt or an organic salt such as nitrate or sulfate. Organic salts include carboxylates, dicarboxylates and acetylacetone complex salts. Furthermore, the additive as the catalyst metal is preferably one that dissolves in the tungstic acid colloid solution.

When palladium is added as a catalyst metal, palladium hydrate is added to a colloidal solution of tungstic acid (H ₂ WO ₄ ). Specifically, 2.5 g of tungstic acid (H ₂ WO ₄ ) is melted in 31 ml of methanol, stirred at room temperature for 30 minutes, and 18 ml of pure water is added to prepare a colloidal solution of tungstic acid. As catalyst metal, colloid of tungstic acid so that the concentration of 0.0125 mol / l dinitrodiamine palladium nitrate water Pd (NH ₃ ) 2 (NO ₂ ) solution is 1.8 mol% to 11 mol% with respect to tungsten. Add to the solution to obtain a colloidal solution of tungstic acid containing palladium catalyst metal. Thereafter, the colloidal solution of tungstic acid containing the palladium catalyst metal was heated and held at a temperature of 400 ° C. to 600 ° C. for 5 hours with air at 50 ml / min, so that the palladium catalyst metal was partially contained on the surface. Tungsten oxide is crystallized, and the crystallized particulate tungsten oxide aggregates to obtain a lump of crystalline particulate tungsten oxide containing palladium on the surface. A lump of crystalline fine particle tungsten oxide containing palladium on the surface is made into an aggregate 6 having a particle diameter of 0.1 to 10 micrometers by a roll mill, and a hydrogen gas detection pigment can be produced. The other method for producing the coating film for detecting hydrogen gas is the same as described above.

In the case of iridium (Ir) as the catalyst metal, a 0.0125 mol / l iridium nitrate Ir (NO ₃ ) ₄ solution is added so that the ratio to tungsten is 1.8 mol% to 11 mol%. A hydrogen gas sensor element was prepared in the same manner as described above, and the hydrogen gas detection sensitivity was evaluated.

Alternatively, an aqueous solution of 0.0125 mol / l chlorinated iridium acid (H ₂ [IrCl ₆ ] · 6H ₂ O) may be added so that the ratio to tungsten is 1.8 mol% to 11 mol%.

  Further, in the case of osmium (Os) as the catalyst metal, except that an osmium oxide (VIII) aqueous solution having a concentration of 0.0125 mol / l is added so that the ratio to tungsten is 1.8 mol% to 11 mol%. A device was fabricated in the same manner.

  Further, in the case of rhodium (Rh) as the catalyst metal, a rhodium nitrate solution (III) aqueous solution having a concentration of 0.0125 mol / l is added so that the ratio to tungsten is 1.8 mol% to 11 mol%. A device was fabricated in the same manner.

  In the case of ruthenium (Ru) as the catalyst metal, an aqueous solution of ruthenium (III) nitrate having a concentration of 0.0125 mol / l is added so that the ratio to tungsten is 1.8 mol% to 11 mol%. A device was fabricated in the same manner.

  As described above, platinum group metals have almost the same electronegativity, and although there are differences in hydrogen gas detection sensitivity and speed, the effects on hydrogen adsorption and dissociation are almost the same, and hydrogen gas leakage detection with 1% hydrogen gas concentration in the air The sensitivity was improved, and an increase in light absorption due to hydrogen gas leakage was observed.

  Metals as dopants added to tungsten oxide have a work function, which is the minimum energy required to extract one electron from the crystal surface of a metal or semiconductor to the outside, because the ionic radius is close to that of tungsten. Close to tungsten, vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), Ni (nickel), copper (Cu), niobium (Nb), molybdenum (Mo), rhenium (Re) and titanium (Ti) can be used and added so that the ratio to tungsten is 0.25 mol% to 5 mol%.

  As a result, minute distortion occurs in the tungsten oxide, oxygen defects are generated in the tungsten oxide, and thus the proton conductivity and the electron carrier concentration are increased, and the hue change at the time of hydrogen gas leakage can be improved.

  For example, in the case of vanadium (V) as a metal additive, a hydrogen gas detection pigment was prepared in the same manner except that 2 ml of 0.0125 mol / l ammonium metavanadate aqueous solution was added to the colloidal solution of tungstic acid.

  In the case of chromium (Cr) as a metal additive, a hydrogen gas detection pigment was prepared in the same manner except that 2 ml of a 0.0125 mol / l concentration chromium nitrate (III) nonahydrate aqueous solution was added. The addition amount of chromium (Cr) is preferably 0.25 mol% to 2 mol% with respect to tungsten.

  In the case of manganese (Mn) as a metal additive, a hydrogen gas detection pigment was prepared in the same manner except that 2 ml of 0.0125 mol / l manganese nitrate aqueous solution was added.

Further, in the case of iron (Fe) as a metal additive, a hydrogen gas detection pigment is similarly obtained except that 2 ml of 0.0125 mol / l ferrous chloride (FeCl ₂ (H ₂ O)) 4 aqueous solution is added. Was made.

In the case of cobalt (Co) as the metal additive, a hydrogen gas detection pigment was prepared in the same manner except that 2 ml of 0.0125 mol / l concentration cobalt chloride (CoCl ₂ .6H ₂ O) aqueous solution was added.

In the case of nickel (Ni) as a metal additive, hydrogen gas detection is performed in the same manner except that 2 ml of 0.0125 mol / l nickel hydrated oxide (Ni ₂ O ₃ .2H ₂ O) aqueous solution is added. A paint film pigment was prepared.

Moreover, in the case of copper (Cu) as a metal additive, except that 2 ml of 0.0125 mol / l concentration copper (II) acetate hydrate (Cu (CH ₃ COO) 2 .H ₂ O) aqueous solution is added. Similarly, a coating film pigment for detecting hydrogen gas was prepared.

  In the case of niobium (Nb) as a metal additive, a coating film pigment for detecting hydrogen gas was prepared in the same manner except that 2 ml of 0.0125 mol / l niobium chloride aqueous solution was added.

  In the case of molybdenum (Mo) as a metal additive, a coating pigment for hydrogen gas detection was prepared in the same manner except that 2 ml of 0.0125 mol / l concentration molybdenum (I) hydrate aqueous solution was added.

  In the case of rhenium (Re) as the metal additive, a coating film pigment for hydrogen gas detection was prepared in the same manner except that 2 ml of 0.0025 mol / l concentration rhenium oxide hydrate aqueous solution was added.

Further, if the metal additive titanium (Ti), except that the addition of 0.0025 mol / l concentration titanate alkoxide 2ml ethanol 5 X 10- ⁵ moles diethanolamine 4X 10- ⁶ mol similarly hydrogen A coating film pigment for gas detection was prepared.

  In any of the above cases, when the light absorption amount was measured at a hydrogen gas concentration of 1% in the air by the hue change characteristic evaluation at the time of hydrogen gas leakage shown in FIG. 5, the hue was compared with the case where the additive was not added. Improvement in change characteristics was observed.

  Example 2 of the hydrogen gas detection tape is shown in FIG. In FIG. 2, the hydrogen gas detection tape includes an adhesive layer 11, a base sheet layer 10, and a hydrogen gas detection layer 5 containing a pigment that is reduced by changing the hue by being injected with protons generated by dissociating hydrogen gas. It is constructed by stacking sequentially. Furthermore, a release sheet (not shown) may be provided on the mask side of the pressure-sensitive adhesive layer 11. The manufacturing method of a hydrogen gas detection tape can be performed as follows.

  First, a hydrogen gas detector 4 and a coating film according to the composition described in Example 1 are formed on one side of a base sheet layer 10 such as a polyethylene terephthalate resin having a thickness of about 13 to 200 μm, particularly preferably about 50 to 100 μm. A coating film composed of the forming component vehicle 3 is applied to form a hydrogen gas detecting coating film layer 5. The coating film thickness is preferably about 3 to 100 μm, particularly about 5 to 50 μm in consideration of the dry or cured film thickness. The coating film can be dried and cured at 120 ° C. for 30 minutes to form a hydrogen detection layer 5 of about 2 to 70 μm, preferably about 3 to 30 μm. The film thickness of the pressure-sensitive adhesive layer 11 is preferably about 5 to 100 μm, particularly about 10 to 20 μm. In contrast to the above process, the hydrogen detection layer 5 may be formed after the pressure-sensitive adhesive layer 6 is formed. As the pressure-sensitive adhesive layer 11, a known pressure-sensitive adhesive can be used. Specifically, acrylic resin-based, ethylene vinyl acetate copolymer system, vinyl chloride vinyl acetate copolymer system, vinyl chloride resin system, rubber system, polyamide Non-crosslinking adhesive resin compositions such as resin-based, polyurethane-resin-based, polyester-resin-based, etc., curing agents such as urea resins, melamine resins, polyisocyanate compounds, base resins such as acrylic resins, epoxy resins, phenol resins, polyester resins An ultraviolet curable resin composition mixed with can be used.

  The base sheet layer 10 is a support having hydrogen gas permeability, such as acrylic resin, ABS resin, epoxy resin, phenol resin, vinyl chloride resin, or other thermosetting or thermoplastic plastic sheet, polyurethane resin, polyethylene terephthalate. Synthetic resin sheets such as resin, polycarbonate resin, polybutylene terephthalate resin, nylon and polyethylene resin, and fiber reinforced plastic sheets obtained by reinforcing these plastics with organic fibers such as nylon fibers, and metal sheets such as aluminum and steel, Examples thereof include paper sheets, cloth sheets, and laminate sheets thereof. Although the thickness of the base sheet layer 10 will not be specifically limited if it is flexible, For example, about 10-500 micrometers, Preferably, 50-200 micrometers is used. Further, the sheet 5 may be transparent or colored, and the coloring may be performed as long as the hue change of the hydrogen detection layer 5 can be recognized. Further, the base sheet layer 10 can detect gas leakage including hydrogen gas at a higher speed by providing appropriate holes so that the hydrogen gas can easily reach the hydrogen detection layer 5. If the hole diameter is 0.074 nm or more, which is the size of the hydrogen gas, the hydrogen gas can sufficiently diffuse in the base sheet layer.

  Specifically, a more specific composition ratio of the paint having a hydrogen gas detection pigment is 2 to 80% by weight, preferably 10 to 60% by weight of the hydrogen gas detection pigment per 100% by weight of the resin component. It is a range.

  An example of a specific composition of the coating film for detecting hydrogen gas was blended based on the following coating composition.

Phthalic acid resin varnish (trade name: phthalit varnish manufactured by Kansai Paint) = 15% by weight,
Melamine resin liquid (trade name; Delicon # 300, manufactured by Dainippon Paint) = 25% by weight
The present invention hydrogen detection pigment = 15 wt%,
Xylene / toluene, etc. Weight ratio = 44 wt%, Dispersant = 1 wt%
In addition, as a hydrogen gas detection pigment contained in a coating film, the particle diameter of the aggregate 6 of the fine particle tungsten oxide 1 constituting the hydrogen detection pigment is set to 50 μm or less, and particularly preferably 10 μm or less.

  Next, an example in which the coating film for detecting hydrogen gas is used for containers, piping, etc. will be described below.

  As shown in FIG. 2, the hydrogen gas detection tape of the present invention was adhered to a portion of the container 7 where there was a concern about leakage of hydrogen gas, and was dried and heated with a dryer and fixed. When the container 8 was filled with hydrogen gas 8 after being left for about 3 months, a hue change from light yellow green to dark blue was observed in the coating film in the range of 5 mm centering on the pinhole portion of about 500 μm.

  FIG. 3 shows a hydrogen gas detection tape as another embodiment. In FIG. 3, a protective film 12 is provided on the hydrogen detection layer 5 with respect to the hydrogen gas detection tape shown in FIG. The manufacturing method other than the protective film 12 is the same as that in the second embodiment. The protective film 12 is preferably a transparent and weather resistant material. Specifically, a transparent resin having a film thickness of about 12 to 200 μm, preferably about 3 to 50 μm, a fluororesin such as a polycarbonate resin, a polytetrafluoroethylene (PTFE) resin or a perfluoroalkyl vinyl ether (PFA) resin, a fluororesin Vinylidene chloride resin and silicone resin are preferred. Specifically, 10 μm of a silicone resin (trade name; manufactured by Fine Silicone Varnish, Fine Chemical Japan) was applied, dried at room temperature, and cured. Hydrogen gas detection tape having a protective film FIG. 3 is particularly effective for detecting a gas leak location including hydrogen in the outdoors. The hydrogen gas detection tape of the present invention was adhered to the outside of the gas pipe 8 of the gas 9 containing hydrogen gas outdoors, and after standing for about 3 months, the pipe was filled with hydrogen gas. It was confirmed that gas leakage including hydrogen gas could be detected since the hue changed to blue over a diameter range of about 5 mm.

  An example of a hydrogen gas detection tape which is another embodiment is shown in FIG. In FIG. 4, a coating film for detecting hydrogen gas 5 is formed on a base sheet layer 10 by applying, drying, and curing using a paint having the same composition as in Example 1, and thereafter, the pressure-sensitive adhesive layer 11 This is a hydrogen gas detection tape formed. In this embodiment, the stacking order of the hydrogen gas tape is different from that in Embodiment 2, but the materials and the manufacturing method are the same. The hydrogen gas detection tape of FIG. 4 is adhered to the outside of the gas pipe 8 of the gas 9 containing hydrogen gas, and after standing for about three months, the pipe is filled with hydrogen gas. The pinhole portion of about 100 μm is centered. A hue change to blue was observed over a range of about 5 mm in diameter, and the hydrogen gas detection location was confirmed.

  The coating film pigment for hydrogen gas detection according to the present invention increases the hue change at the time of gas leakage containing hydrogen, and at the same time, speeds up the response of the hue change at the time of gas leakage containing hydrogen. While providing a pigment, it can utilize for the tape which detects easily the gas leak location containing the hydrogen using the hydrogen gas detection pigment, or a gas sensor.

In addition, since the present invention utilizes changes in physical properties due to hydrogen element protons (H ⁺ ), a paint, tape, or gas sensor for detecting a reducing gas such as hydrogen sulfide gas (H ₂ S) or nitrogen oxide (NO _x ). Available to:

  It can also be used in chemical sensors such as a PH sensor that detects protons and a chemical indicator based on proton detection.

Since the present invention utilizes changes in physical properties caused by hydrogen element protons (H ⁺ ), it can also be applied as an electrobook (EC) display material having a wide dynamic range at high speed and an ink material for electronic books such as e-ink.

  Furthermore, it is also useful as a light control glass by applying a paint containing the coating film pigment for detecting hydrogen gas of the present invention to a window glass provided with a transparent electrode and further sandwiching it between the transparent electrodes.

Sectional drawing for demonstrating typically the coating film for hydrogen gas detection in Example 1 of this invention Sectional drawing for demonstrating typically the hydrogen gas detection tape in Example 2 of this invention Sectional drawing for demonstrating typically the other hydrogen gas detection tape in Example 3 of this invention Sectional drawing for demonstrating typically the other hydrogen gas detection tape in Example 4 of this invention The figure for demonstrating the hue change evaluation system at the time of the hydrogen gas leak of the coating-film pigment for hydrogen gas detection in the Example of this invention The figure for demonstrating the optical transmittance | permeability of the coating film pigment for hydrogen gas detection in the Example of this invention The figure which shows the relationship between the average particle diameter of the fine particle tungsten oxide in the coating-film pigment for hydrogen gas detection in the Example of this invention, the light absorption amount at the time of hydrogen gas leak (A), and a response speed (B). The figure which shows the relationship between the oxygen / tungsten number ratio of the fine particle tungsten oxide in the coating film pigment for hydrogen gas detection in the Example of this invention, and the light absorption amount at the time of hydrogen gas leak The figure which shows the calcining process temperature dependence of the X-ray-diffraction peak of fine particle tungsten oxide in the coating film pigment for hydrogen gas detection in the Example of this invention. The figure which shows the relationship between the X-ray-diffraction peak (001/200) ratio of the fine particle tungsten oxide in the coating-film pigment for hydrogen gas detection in the Example of this invention, and the light absorption amount at the time of hydrogen gas leak. The figure which shows the X-ray photoelectron spectroscopy spectrum of the platinum catalyst metal contained in the fine particle tungsten oxide in the coating film pigment for hydrogen gas detection in the Example of this invention The figure which shows the relationship between the oxidation state of the platinum catalyst metal contained in the fine particle tungsten oxide in the coating pigment for hydrogen gas detection in the Example of this invention, and the light absorption amount at the time of hydrogen gas leak The figure which shows the relationship between the ratio mol% of the platinum catalyst metal with respect to tungsten of the fine-particle tungsten oxide in the coating film pigment for hydrogen gas detection of this invention, and the light absorption amount at the time of hydrogen gas leak

Explanation of symbols

1 Fine Particle Tungsten Oxide 2 Catalytic Metal 3 Paint Forming Component Vehicle 4 Hydrogen Gas Detection Coating Pigment 5, 22 Hydrogen Gas Detection Coating 6 Aggregation of Fine Tungsten Oxide 7 Surface to be Measured (Container or Pipe)
8 Gas containing hydrogen gas 9 Hydrogen gas leakage path 10 Base sheet layer 11 Adhesive layer 12 Protective film 21 Transparent substrate 23 White light source 24 Incident light 25 Transmitted light 26 Photo detector 27 Chamber 28 Sample 29 Gas inlet

Claims (21)

A coating film pigment for hydrogen gas detection that is applied to the surface of a gas pipe or container containing hydrogen gas, protons generated by dissociating hydrogen gas are injected and reduced, and the hue changes, and the pigment is oxidized A coating pigment for hydrogen gas detection, which is composed of an aggregate of crystalline fine particles mainly composed of tungsten, and contains a catalytic metal in an oxidized state on the surface of the crystalline fine particle tungsten oxide. 2. The coating pigment for hydrogen gas detection according to claim 1, wherein the crystalline fine particle tungsten oxide has an average particle diameter of 15 nm to 80 nm. The coating pigment for hydrogen gas detection according to claim 1, wherein the crystalline fine particle tungsten oxide has a predetermined ratio of oxygen defects. The coating film pigment for hydrogen gas detection according to claim 1, wherein the ratio of the number of oxygen atoms to the number of tungsten atoms in the fine crystalline tungsten oxide is 2.54 to 2.63. The coating pigment for hydrogen gas detection according to claim 1, wherein the crystalline fine particle tungsten oxide includes at least two crystal structures. Vanadium (V), chromium (Cr),
Manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu),
Niobium (Nb), molybdenum (Mo), rhenium (Re), titanium (Ti), or a mixture of any of these metals is doped at a concentration of 0.25 mol% to 5 mol% 2. The coating film pigment for detecting hydrogen gas according to claim 1, wherein 2. The coating gas pigment for hydrogen gas detection according to claim 1, wherein the catalytic metal is in an oxidized state of 28% to 78% of the total amount of the catalytic metal contained in the fine particle tungsten oxide. The coating gas pigment for hydrogen gas detection according to claim 1, wherein the catalyst metal has a ratio of 1.8 mol% to 11 mol% with respect to the fine particle tungsten oxide. The coating gas pigment for hydrogen gas detection according to claim 1, wherein the catalyst metal has an average particle diameter of 2 nm to 35 nm. The catalyst metal is any one of platinum, (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), or any of these metals. The paint film pigment for hydrogen gas detection according to claim 1, which is a mixture. In a coating film for hydrogen gas detection that is applied to the surface of a gas pipe or container containing hydrogen gas, protons generated by dissociating hydrogen gas are injected and reduced, and the hue changes.
Hydrogen gas detection characterized in that it contains crystallized particulate tungsten oxide as a pigment component of the coating film, an oxidized catalytic metal on the surface of the particulate tungsten oxide, and a vehicle as a coating component of the coating film Coating film. A hydrogen gas detection tape in which an adhesive layer, a base sheet layer, and a hydrogen gas detection layer containing a pigment that is reduced by being injected with protons generated by dissociating hydrogen gas and changing hue are sequentially laminated. The hydrogen gas detection tape is characterized in that the pigment is composed of an aggregate of crystal fine particles mainly composed of tungsten oxide, and contains a catalytic metal in an oxidized state on the surface of the crystal fine particle tungsten oxide. An adhesive layer, a base sheet layer, and a hydrogen gas detection layer containing a pigment that is converted by being injected with protons generated by dissociating hydrogen gas and changed in hue are sequentially laminated, and further on the hydrogen gas detection layer. A hydrogen gas detection tape having a protective film laminated thereon, wherein the pigment is composed of an aggregate of crystalline fine particles mainly composed of tungsten oxide, and a catalytic metal in an oxidized state is formed on the surface of the crystalline fine particle tungsten oxide. A hydrogen gas detection tape characterized by containing. A hydrogen gas detection tape comprising an adhesive layer, a hydrogen gas detection layer containing a pigment that is injected with protons generated by dissociating hydrogen gas and reduced in hue, and a base sheet layer sequentially laminated. A hydrogen gas detection tape comprising a catalytic metal in an oxidized state on the surface of the crystalline fine particle tungsten oxide. The hydrogen gas detection tape according to claim 12, wherein the crystalline fine particle tungsten oxide has an average particle diameter of 15 nm to 80 nm. 15. The hydrogen gas detection tape according to claim 12, wherein the crystalline fine particle tungsten oxide includes at least two crystal structures. Vanadium (V), chromium (Cr),
Manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu),
Niobium (Nb), molybdenum (Mo), rhenium (Re), titanium (Ti), or a mixture of any of these metals is doped at a concentration of 0.25 mol% to 5 mol% The hydrogen gas detection tape according to claim 12, wherein the hydrogen gas detection tape is provided. The hydrogen gas detection tape according to any one of claims 12 to 14, wherein the catalyst metal is in an oxidized state of 28% to 78% of the total amount of the catalyst metal contained in the particulate tungsten oxide. The hydrogen gas detection tape according to claim 12, wherein the catalyst metal has a ratio of 1.8 mol% to 11 mol% with respect to tungsten. The hydrogen gas detection tape according to any one of claims 12 to 14, wherein the catalyst metal has an average particle diameter of 2 nm to 35 nm. The catalyst metal is any one of platinum, (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), or any of these metals. The hydrogen gas detection tape according to any one of claims 12 to 14, which is a mixture.

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