JP6125318B2 - Thermal spray composition and thermal spray coating - Google Patents

Description

  The present invention manufactures a thermal spray composition (spraying material or spraying agent) useful for effectively decomposing and removing the burning of oil or boiling juice adhering to a heating cooker, a thermal spray coating, and a member provided with the thermal spray coating. Regarding the method.

  When oil, broth or the like adheres to a heating cooker or the like, scorching that is firmly adhered by heating occurs. As a prior art for decomposing and removing such burning of oil and soup, salmon has been proposed for adding an oxidation catalyst to exhibit a self-cleaning function. For example, Japanese Patent Laid-Open No. 2002-322575 (Patent Document 1) describes that scorching is removed with a glaze containing aluminum borate whiskers in a proportion of 1 to 30% by weight. In Japanese Patent Application Laid-Open No. 2004-50764 (Patent Document 2), a self-cleaning agent (one or more of iron oxide, manganese oxide, and copper oxide) made of an oxidation catalyst is added to the glaze and self-cleaning is performed on a stainless steel base material. Forming a layer is disclosed. Japanese Patent Application Laid-Open No. 2007-3186 (Patent Document 3) discloses a self-cleaning agent (one or more of iron oxide, manganese oxide, and copper oxide) made of an oxidation catalyst on a stainless steel plate in a heating chamber heated by a heater of a heating cooker. It is disclosed that a self-cleaning layer is formed with a glaze to which is added).

Japanese Patent Application Laid-Open No. 2010-249441 (Patent Document 4) discloses a cooking device in which a side surface of a cooking chamber is subjected to self-cleaning treatment (glazing treatment) by adding manganese oxide or manganese oxide and cerium oxide to the glaze. ing. Furthermore, Japanese Patent Laid-Open No. 10-23973 (Patent Document 5) discloses a cooking device provided with a heating means (burner) for applying a porous lining to the inner surface of a cooking chamber with a self-cleaning scissor and heating the porous lining. Is described. Japanese Patent Application Laid-Open No. 5-203165 (Patent Document 6) applies a paint containing a catalyst powder having good low-temperature activity, water, a surfactant and a heat-resistant binder to the inner wall of a heating chamber of a cooking device. A cooking device is described in which a film is formed, a path is formed with moisture and a surfactant that evaporates by firing, and a porous self-cleaning layer is formed. This document describes a catalyst powder in which 0.1 to 1% by weight of gold or platinum is mixed with manganese dioxide (γ-MnO ₂ ).

The burned decomposition reaction is represented by the following reaction formula, assuming that the deposit is CxHyOz and the oxidation catalyst is nO ₂ .

_{CxHyOz + nO 2 = xCO 2 +} y / 2H 2 O
In this decomposition reaction, in an ideal reaction, all attached dirt is decomposed and removed into carbon dioxide gas and water. However, at present, no soot processing technology has been established that completely decomposes and removes the attached dirt of a cooking device or the like by a self-cleaning action. The reason is not clear, but it is conceivable that the composition of the dirt is complicated, the temperature of the dirt and the adhesion surface is non-uniform and the catalytic action does not proceed uniformly, and the catalyst activity is temperature-dependent.

  And depending on the adhesion surface and the temperature inside the cooking device, the dirt remaining without being decomposed by the self-cleaning action increases coking (carbonization) and increases hardness and adhesion. Caulked dirt is generally removed by dipping in an aqueous solution of water or baking soda, or by burning and ashing. The method of immersion in water is a simple method, although it is necessary to make a member or part to which dirt easily adheres have a detachable structure, and can remove caulked dirt at low cost. However, in the above-mentioned immersion method, a chemical is required, and in the case of effective removal, the surface of the substrate (base material) needs to be hydrophilized so that water can easily enter between the dirt and the adhesion surface. There is. In Patent Document 5, dirt is effectively burned and ashed by a burner arranged in a cooker. However, in the method using the burner, not only the installation of the burner may be difficult depending on the structure of the cooker, but the structure of the cooker becomes complicated and the cost is inevitably increased.

  Furthermore, as described above, the cocoon processing frequently used in a cooking device includes many processes such as pickling of a metal substrate (base material), application of a base candy, application of a polishing candy, and baking. In addition, it is carried out with dedicated installation equipment. For this reason, dredging has a small degree of freedom with respect to the shape and dimensions of the object, and it can be applied to members built in existing structures (for example, buildings, bridges, ships, vehicles, machines, etc.) or on-site processing and construction. Is practically difficult. Further, the pickling is an indispensable treatment for increasing the adhesion strength between the cocoon and the substrate, and the countermeasure for treating sludge and waste water generated in this process has become a major issue in the cocoon processing industry.

In WO96 / 27694 (Patent Document 7), a sprayed material selected from metals, ceramics and cermets thereof is sprayed on the surface of a steel substrate to form a sprayed coating. It describes that a member having a composite coating that is excellent in corrosion resistance and molten metal resistance is formed by forming a quality coating and combining it with the thermal spray coating. This document describes 10% by weight B ₂ O ₃ -25% by weight Na ₂ O-5% by weight CaO-60% by weight SiO ₂ , 8% by weight ZnO-18% by weight CaO as a frit for a glassy film of a top coat. It is also described that coating and baking were performed using −10 wt% B ₂ O ₃ —64 wt% SiO ₂ . This document also mentions that a glassy film is formed by thermal spraying, but there is no description about the details.

  Further, in JP-A-10-288593 (Patent Document 8), a gas sensor in which a porous layer containing an oxidation catalyst is formed by plasma spraying an oxidation catalyst and a film-forming powder, and the oxidation catalyst are dispersed and held. A gas sensor in which a porous body layer containing an oxidation catalyst is formed with a soot coating is described. However, this document does not describe details of the soot coating.

JP 2002-322575 A (Claims, paragraph [0030]) JP 2004-50764 A (Claims) JP 2007-3186 (Claims) JP 2010-249441 A (Claims) JP-A-10-23973 (Claims) JP-A-5-203165 (Claims, paragraph [0010]) WO96 / 27694 (Claims, page 10, line 11 to line 14 and page 14, line 1 to line 7) JP 10-288593 A (claims, paragraphs [0041] [0042] [0078] [0079])

  Accordingly, an object of the present invention is to provide a thermal spray material useful for forming a soot-like self-cleaning layer capable of effectively decomposing and removing adhered dirt by a self-cleaning action, a thermal spray film (spray coating) using the thermal spray material, and It is in providing the manufacturing method.

  Another object of the present invention is to provide a sprayed material useful for forming a soot-like self-cleaning layer by a simple operation called spraying, a sprayed film (sprayed coating) using the sprayed material, and a method for producing the same. It is in.

  Yet another object of the present invention is a thermal spray useful for forming a self-cleaning layer that can be adhered to a substrate (base material) with high adhesion strength without being processed in many steps such as pickling. The object is to provide a material, a sprayed film (sprayed coating) using the sprayed material, and a manufacturing method thereof.

  Another object of the present invention is a thermal spray material capable of forming a coating in various atmospheres including the atmosphere at the factory and the field, with a large degree of freedom with respect to the shape and size of the object forming the soot-like self-cleaning layer and the material, An object of the present invention is to provide a sprayed film (sprayed coating) using this sprayed material and a method for manufacturing the same.

  The inventors of the present invention focused on the excellent features of the thermal spraying technology, and as a result of intensive studies to achieve the above-mentioned problems, the glass frit exhibited a high film forming ability by thermal spraying, and an inorganic oxidation catalyst was added to the glass frit. When sprayed, it is possible to form a sprayed coating that can be effectively decomposed and removed by a self-cleaning action to remove dirt adhered to a heating cooker, etc., and in addition to the oxidation catalytic action by an oxidation catalyst, it has been made hydrophilic. It has been found that when a functional film is formed, it has a catalytic action and a hydrophilic action effective in removing the burnt oil and boiled juice with scorch, and it can be easily removed even if it adheres to cooking equipment, especially caulked dirt. The present invention has been completed.

  That is, the thermal spray composition (thermal spray material or thermal spray agent) of the present invention includes a glass frit capable of forming a thermal spray coating and at least an inorganic oxidation catalyst.

  Thermal spraying, which is one of the coating techniques, is a complete dry process in which a coating is formed by spraying a particulate thermal spray material heated to a molten state or a state close to melting onto a substrate. Therefore, the degree of freedom with respect to the shape, size, and material of the object is extremely large, and it is possible to form a film in various atmospheres as well as in the atmosphere. Furthermore, it has an excellent feature that it can be installed in a factory and on-site. By applying these thermal spraying techniques, it is possible to easily form a thermal spray coating having a self-cleaning property by an oxidation catalytic action.

  Furthermore, since the basic properties of the thermal spray coating are derived from the chemical components of the thermal spray material that is the starting material, depending on the choice of thermal spray material, corrosion resistance, heat resistance, wear resistance, electrical insulation, water repellency, hydrophilicity, etc. These various functional coatings can be formed relatively easily. Thermal spraying with such characteristics is designated as one of the most important industrial basic technologies in the “Law on Advancement of Manufacturing Basic Technology for Small and Medium Enterprises” (enforced on June 13, 2006). Used in the field. From such a point, the present invention can be widely applied according to the use and has high utility.

  In the thermal spray composition of the present invention, the inorganic oxidation catalyst may contain a low temperature active oxidation catalyst and a high temperature active oxidation catalyst. Furthermore, the composition may contain (1) an inorganic oxidation catalyst composed of a hydrophilic metal oxide, or (2) an inorganic oxidation catalyst and a hydrophilic metal oxide. Furthermore, the thermal spray composition (spraying material or thermal spraying agent) of the present invention includes a glass frit capable of forming a thermal spray coating, an inorganic oxidation catalyst, and a hydrophilic metal oxide. An active oxidation catalyst and a high temperature active oxidation catalyst may be included.

  When the hydrophilic metal oxide is used as an oxidation catalyst or in addition to the oxidation catalyst, it can be oxidatively decomposed even with caulked dirt by the oxidation catalytic action and hydrophilization action of the sprayed coating, Water can easily enter between caulking dirt and dirt can be removed more effectively.

  The inorganic oxidation catalyst may be at least one selected from oxides and phosphates of transition metals belonging to Groups 3 to 12 of the periodic table. Further, the low temperature active inorganic oxidation catalyst may be at least one selected from oxides of metal elements belonging to Groups 6 to 11 of the periodic table. The high temperature active inorganic oxidation catalyst may be at least one selected from oxides and phosphates of metal elements belonging to Group 4, Group 5, Group 8, Group 11, Group 12 of the periodic table. Good. In addition, different types of oxidation catalysts are used as the low temperature active inorganic oxidation catalyst and the high temperature active oxidation catalyst. For example, in a low-temperature activated oxidation catalyst, the valence of the Group 8 metal element is often divalent, and the valence of the Group 11 metal element is often monovalent. Further, in a high-temperature active oxidation catalyst, the valence of the Group 8 metal element of the periodic table is often trivalent, and the valence of the Group 11 metal element is often divalent. The ratio of the low temperature active inorganic oxidation catalyst and the high temperature active inorganic oxidation catalyst may be, for example, the former / the latter (weight ratio) = about 5/95 to 97/3.

  Further, the hydrophilic metal oxide is composed of oxides of metal elements belonging to Groups 1 to 4, Group 6, Group 7, Group 9, Group 10, Group 12, and Group 13 of the periodic table. It may be at least one selected. In addition, as a hydrophilic metal oxide, the kind of metal oxide different from an inorganic oxidation catalyst can be used. For example, the inorganic oxidation catalyst is at least one selected from oxides and phosphates of transition metals belonging to Groups 3 and 5 to 12 of the periodic table. It may be at least one selected from oxides of metal elements belonging to Group 1 to Group 4 and Group 13.

  The usage-amount of an inorganic oxidation catalyst and a hydrophilic metal oxide can be selected in the range which does not impair the characteristic of a sprayed coating. The content of the inorganic oxidation catalyst may be, for example, about 5 to 100 parts by weight with respect to 100 parts by weight of the glass frit, and the content of the hydrophilic metal oxide is based on 100 parts by weight of the glass frit. It may be about 5 to 60 parts by weight. The total amount of the inorganic oxidation catalyst and the hydrophilic metal oxide (the amount of the inorganic oxidation catalyst used when the inorganic oxidation catalyst is a hydrophilic metal oxide) is 10 to 100 with respect to 100 parts by weight of the glass frit. It may be about parts by weight. The ratio of the inorganic oxidation catalyst and the hydrophilic metal oxide may be, for example, the former / the latter (weight ratio) = about 10/90 to 90/10.

  The form of the thermal spray composition (thermal spray material) of the present invention is not particularly limited, and may be, for example, a powder form, a granule form, a pellet form, a rod form, or the like. The thermal spray composition (thermal spray material) may be filled in a hollow cylinder of a thermally decomposable resin.

  The present invention also includes a thermal spray coating (a thermal spray coating having a self-cleaning property, particularly a soot-like coating) formed of the thermal spray composition (thermal spray material).

  Furthermore, the present invention provides a method for spraying the thermal spray composition on a base material to form a thermal spray coating, and a method for spraying the thermal spray composition on the base material to produce a member provided with the thermal spray coating. Is also included.

  In the present specification, “hydrophilic metal oxide” means an oxide (or metal oxide) of an element having an electronegativity of 1.8 or less.

  The thermal spray composition (spray material) according to the present invention can easily decompose and remove dirt (burned oil, boiled juice, etc.) adhering to a heating cooker or the like by an oxidation catalytic action and a self-cleaning action. In addition, a simple operation called thermal spraying can not only form a cocoon-like film (self-cleaning layer), but it can adhere to the substrate (base material) with high adhesion strength without processing in many processes such as pickling. A self-cleaning layer can be formed. Furthermore, when a hydrophilic metal oxide is used as an oxidation catalyst or in addition to the oxidation catalyst, the scorch that has been difficult in the past can be more easily decomposed and removed by the synergistic effect of the catalytic action and the hydrophilic action. In particular, it is effective for removing caulked dirt not only by decomposition by catalytic action but also by hydrophilic action. In addition, the degree of freedom with respect to the shape and size of the object and the material is large, and the soot-like self-cleaning layer can be easily formed in various atmospheres including the atmosphere at the factory and the site.

It is a figure which shows the X-ray-diffraction pattern of the film formed with the thermal spray material of Example 1, 2, 8 and the comparative example 1. FIG. It is a figure which shows the change of a micro infrared ray (IR) spectrum when the stain | pollution | contamination on the film formed with the thermal spray material of the comparative example 1 is heat-processed at the temperature of 200 degreeC, 300 degreeC, and 350 degreeC for 2 hours. It is a figure which shows the change of microscopic IR spectrum when the stain | pollution | contamination on the film formed with the thermal spray material of Example 3 is heat-processed at the temperature of 200 degreeC, 300 degreeC, and 350 degreeC for 2 hours. It is a graph which shows the relationship between heat processing temperature and IR absorption intensity ratio (1740cm < ^-1 >) about the stain | pollution | contamination on the film formed with the thermal spray material of Example 1 and Example 2. FIG.

  The thermal spray composition (thermal spray material or thermal spray agent) of the present invention includes a glass frit capable of forming a thermal spray coating and at least an inorganic oxidation catalyst.

[Glass frit]
The kind of the glass frit is not particularly limited, and is a glass frit for glazing, for example, a silicon oxide frit containing silicon oxide SiO ₂ as a skeleton main component, a boron oxide frit containing boron oxide B ₂ O _3, and phosphorus oxide. Examples include glass frit for glazing such as phosphorous oxide-based frit containing P ₂ O ₅ (Non-patent Document 1, “Enamel Technology Guidebook” (1996) edited by the Japan Society of Food Industry). The glass frit is often a silicon oxide frit containing at least silicon oxide SiO ₂ and a boron oxide frit containing at least boron oxide B ₂ O ₃ . Particularly preferred glass frit is a silicon oxide frit. The main component of the glass frit may be a natural mineral. As the skeleton main component, a component that does not exhibit oxidation catalyst activity, such as SiO ₂ , is usually used.

  The glass frit for scissors may be classified into a ground coat (undercoat) and a cover coat (upward). The thermal spray material of the present invention may be a glass frit capable of forming the outermost layer (top coat) regardless of whether it is for ground coat or cover coat. The glass frit for glazing is a multi-component system composed of a skeleton main component and a secondary (modifying) component (Non-Patent Document 1), and it is not uncommon to add an unknown component as know-how in glazing processing. The composition of the coating is quite complex.

[Inorganic oxidation catalyst]
As the inorganic oxidation catalyst, various inorganic oxidation catalysts that catalyze an oxidation reaction, particularly a gas phase contact reaction can be used. The inorganic oxidation catalyst can usually be selected from metal oxides and phosphates mainly composed of transition metals belonging to Group 3 to Group 12 of the periodic table (preferably Group 4 to Group 12 of the periodic table). Or it can be used in combination of two or more. The inorganic oxidation catalyst can be classified into a low-temperature active catalyst and a high-temperature active catalyst, and any type of oxidation catalyst may be used, but at least a low-temperature active oxidation catalyst is often included, and the catalyst is high in a wide temperature range. In order to express the activity, it is preferable to use both in combination. As for the low-temperature active catalyst and the high-temperature active catalyst, “Introduction to Catalytic Chemistry”, Sonami et al., Kyoritsu Shuppan (1971), pages 221 to 224 can be referred to. The low temperature active oxidation catalyst belongs to a p-type oxide semiconductor, and the high temperature active oxidation catalyst belongs to an n-type oxide semiconductor. The inorganic oxidation catalyst can be used in a powder form.

Examples of the low temperature active oxidation catalyst include, for example, Group 6 elements (Cr, Mo, etc.), Group 7 elements (Mn, etc.), Group 8 elements (Fe, Ru, etc.), Group 9 elements (Co, Ru, etc.). Rh, Ir, etc.), Group 10 elements (Ni, etc.), Group 11 elements (Cu, etc.) and other metal element oxides can be exemplified. In these metal oxides, the valence of the metal element may be about 1 to 4 depending on the type of element, the group 8 element is divalent, and the group 11 element is monovalent There are many. Examples of the low-temperature active oxidation catalyst include metal oxides classified as active catalysts at low temperatures (150 ° C. or lower) in the activity sequence for the oxidation of carbon monoxide in the above-mentioned document (“Introduction to Catalytic Chemistry”), for example, Examples thereof include CoO, Cu ₂ O, Cr ₂ O ₃ , NiO, MnO ₂ , MnO, FeO, Ag ₂ O, and Co ₃ O ₄ . These low-temperature oxidation catalysts can be used alone or in combination of two or more. Preferred low temperature active oxidation catalysts are CoO, Cu ₂ O, NiO, MnO ₂ and the like.

In addition, examples of the high-temperature active oxidation catalyst include, for example, Group 5 elements (V, Ce, etc.), Group 8 elements (Fe, Ru, etc.), Group 11 elements (Cu, etc.), Group 12 elements ( In many cases, oxides and phosphates of metal elements such as Zn). In these metal oxides and phosphates, the valence of the metal element is often divalent, trivalent or pentavalent (particularly divalent) depending on the type of the element. Trivalent and group 11 elements are often divalent. As the high-temperature active oxidation catalyst, metal oxides and phosphors classified as active catalysts at high temperatures (150 to 400 ° C.) in the activity sequence for the oxidation of carbon monoxide in the above-mentioned document (“Introduction to Catalytic Chemistry”). Examples of the acid salt include CuO, Fe ₂ O ₃ , ZnO, CeO ₂ , V ₂ O ₃ , V ₂ O _{5, and} FePO ₄ . These high-temperature active oxidation catalysts can also be used alone or in combination of two or more. Preferred high temperature active oxidation catalysts are CuO, Fe ₂ O ₃ , ZnO, CeO ₂ , FePO ₄ and the like.

Note that even if an oxide does not exhibit catalytic activity, the catalytic activity may be increased by compounding. Such complex oxides (for example, complex oxides such as Group 4 elements of the periodic table such as complex oxides of TiO ₂ and ZrO ₂ ) can be classified as oxidation catalysts (for example, high temperature active oxidation catalysts). .

  The amount of the oxidation catalyst used is, for example, 5 to 100 parts by weight, preferably 7 to 75 parts by weight (for example, 8 to 70 parts by weight), more preferably 10 to 60 parts by weight (100 parts by weight of the glass frit). For example, it may be about 12 to 55 parts by weight. The ratio of the oxidation catalyst can be selected from a range of about 1 to 50% by weight with respect to the total weight of the sprayed material, for example, 3 to 35% by weight (for example, 4 to 32% by weight), preferably 5 to 30%. It may be about 10% by weight (for example, 7 to 30% by weight), more preferably about 10 to 30% by weight (for example, 12 to 25% by weight). If the content of the oxidation catalyst is too small, the decomposition function of the soil is lowered, and if it is too much, the film becomes amorphous (a tendency to crystallize), depending on the type of catalyst and spraying conditions. In addition to this, there is a risk of lowering fluidity.

  The ratio between the low temperature active oxidation catalyst and the high temperature active oxidation catalyst can be selected from a wide range of the former / the latter (weight ratio) = 1/99 to 99/1, and is usually 5/95 to 97/3 (for example, 7/93 to 95/5), preferably 10/90 to 90/10 (for example, 15/85 to 80/20). In addition, when the ratio of the low temperature active type oxidation catalyst is increased, it becomes easier to remove dirt at a low temperature.

[Hydrophilic metal oxide]
The thermal spray composition (thermal spray material) of the present invention preferably contains a hydrophilic metal oxide and forms a soot-like film having a catalytic action and a hydrophilic action. That is, in a preferred embodiment, the thermal spray composition (thermal spray material or thermal spray agent) of the present invention includes a glass frit capable of forming a thermal spray coating, an inorganic oxidation catalyst, and a hydrophilic metal oxide. The glass frit (or glass frit for glazing) is a multi-component system including an adhesive, a flux, an opacifier, a colorant, and the like as a subcomponent (modifying component) in addition to a skeleton main component. That is, because of the characteristic of compositional freedom, the types of hydrophilic metal oxides to be added are wider than those of oxidation catalysts. For example, oxidation of elements (metal elements) present in Group 1 to Group 14 of the Periodic Table is possible. An example (metal oxide) can be illustrated. In selecting an inorganic oxide, it is necessary to consider safety to the human body and environment, durability, availability, cost, and the like.

  As is well known, the hydrophilicity of a solid material depends on its chemical composition and surface roughness. When the surface roughness is constant, a compound having a large ionic bond ratio (a compound having a small covalent bond ratio) exhibits more remarkable hydrophilicity. For this reason, in selecting a hydrophilic metal oxide, the magnitude of the ionic bond ratio can be used as a guide.

The ratio of the ionic bonds is given by P _A−B = 1−exp {(− 1/4) (χ _A− χ _B ) ² }, where the electronegativity of the elements A and B is χ and χ _B , respectively. (Non-patent document 2, edited by the Ceramic Industry Association Editorial Board, "Chemistry of Ceramics" (1982)).

  As is apparent from the above calculation formula, it is the difference in electronegativity that dominates the ionic bond ratio between the two elements A and B. If the difference between the two is generally greater than 1.7, the ionic bond is 1.7. If it is smaller, it can be regarded as a covalent bond (when the difference in electronegativity is 1.7, the ionic bond ratio corresponds to 51%).

  The electronegativity is a value unique to each element. The value of fluorine “4.0” is the largest, followed by oxygen “3.5” and chlorine “3.0”. In the present invention, since an oxide of an element having a large electronegativity exhibits a large hydrophilicity, an oxide is used as the hydrophilic compound.

Taking titanium oxide TiO ₂ , which is known as the hydrophilic metal oxide, as an example, when the proportion of ionic bonds is calculated from the above formula, the electronegativity of Ti and O ₂ that are constituent elements of titanium oxide is 1.5 respectively. The difference in electronegativity between the two is 2.0. Substituting this value into the calculation formula gives 0.63 (that is, the ionic bond ratio of TiO ₂ is 63%).

  Elements having a difference from oxygen electronegativity of 3.5 or more, that is, elements having an electronegativity of 1.8 or less, range from Group 1 of the periodic table to Group 14 of the periodic table. As described above, in the multi-component glass frit for soot, the selection range of the hydrophilic metal oxide is quite wide.

  More specifically, the hydrophilic metal oxide is composed of a periodic table group 1 element (an alkali metal such as Li, Na, K), a group 2 element (Ca, Ba, Mg, etc.), a group 3 element (Y Group 4 elements (Ti, Zr, etc.), Group 6 elements (Cr, etc.), Group 7 elements (Mn, etc.), Group 9 elements (Co, etc.), Group 10 elements (Ni, etc.), It may be at least one selected from oxides of metal elements belonging to Group 12 elements (such as Zn) and Group 13 elements (such as Al). The hydrophilic metal oxide can usually be used in a powder form.

Examples of the oxide having a large ionic bond ratio obtained from the above calculation formula include K ₂ O (84%), Na ₂ O (82%), Ba ₂ O ₃ (82%), Li ₂ O (79%). , CaO (79%), Y ₂ O ₃ (73%), MgO (73%), ZrO (67%), TiO ₂ (63%), MnO ₂ (63%), Al ₂ O ₃ (63%) ZnO (59%), Cr ₂ O ₃ (59%), CoO (51%), NiO (51%) and the like can be exemplified (the ionic bond ratio is in parentheses, and the decimal part is rounded off in the calculation). These metal oxides can be used alone or in combination of two or more. Note that in the above oxides, K ₂ O, Na ₂ O, Ba ₂ O ₃ , Li ₂ O, CaO, and the like react with water, and thus care must be taken in handling. Many of lanthanoids and actinoids have a low electronegativity, and many oxides have a high ionic bond ratio.

In addition, components that do not substantially act as an oxidation catalyst by heating in air, for example, oxides that do not exhibit catalytic activity such as Al ₂ O ₃ (and very small catalytic activity even if there is catalytic activity) Oxides that show only catalytic activity unless irradiated with actinic rays, for example, ultraviolet rays (for example, ultraviolet rays of 380 nm or less) (such as TiO ₂ known as a photocatalyst) are not oxidation catalysts, It can be classified as a hydrophilic metal oxide.

The hydrophilic metal oxide is an oxide common to the inorganic oxidation catalyst, such as MnO ₂ , ZnO, Cr ₂ O ₃ , CoO, NiO, etc., as is clear from the comparison with the inorganic oxidation catalyst. There are many cases. In particular, MnO ₂ is promising from the viewpoint of safety and cost as a common oxide having a hydrophilic action and a catalytic action. Therefore, in order to impart hydrophilicity, the inorganic oxidation catalyst may be composed of (1) a hydrophilic metal oxide having both functions of oxidation catalyst activity and hydrophilization, and (2) oxidation catalyst. And an inorganic oxidation catalyst that functions as a hydrophilic metal oxide that does not substantially function as an oxidation catalyst.

In addition, when using an inorganic oxidation catalyst and a hydrophilic metal oxide together, a hydrophilic metal oxide may be the same kind as an inorganic oxidation catalyst, and a different kind of metal oxide may be sufficient as it. For example, when the inorganic oxidation catalyst is at least one selected from oxides and phosphates of transition metals belonging to Group 3, Group 5 to Group 12 of the periodic table, the hydrophilic metal oxide is a periodic table. It may be at least one selected from oxides of metal elements belonging to Group 1 to Group 4 and Group 13, and oxides of metal elements belonging to Groups 4 and 13 of the periodic table (TiO ₂ , Al ₂ O ₃ or the like may be used.

  When using a different kind of hydrophilic metal oxide from the oxidation catalyst, the amount of the hydrophilic metal oxide used is, for example, 5 to 55 parts by weight, preferably 10 to 50 parts by weight with respect to 100 parts by weight of the glass frit ( For example, it may be about 10 to 45 parts by weight), more preferably about 15 to 40 parts by weight (for example, 15 to 35 parts by weight). Further, the ratio of the hydrophilic metal oxide is about 5 to 35% by weight, preferably about 10 to 30% by weight, and more preferably about 15 to 25% by weight with respect to the total weight of the thermal spray composition (spraying material). . If the content of the hydrophilic metal oxide is too small, the hydrophilic action cannot be sufficiently exerted, and if it is too much, depending on the type and thermal spraying conditions, the coating becomes amorphous as in the case of the oxidation catalyst. There exists a possibility of causing the fall of fluidity while showing the tendency to fall (the tendency of crystallization).

  The total amount of the inorganic oxidation catalyst and the hydrophilic metal oxide (when the inorganic oxidation catalyst is a hydrophilic metal oxide, the amount used of the inorganic oxidation catalyst (or hydrophilic metal oxide) means glass) 10 to 150 parts by weight, preferably 20 to 130 parts by weight (for example, 35 to 125 parts by weight), more preferably 50 to 120 parts by weight (for example, 65 to 100 parts by weight) with respect to 100 parts by weight of the frit. is there. The total amount of the inorganic oxidation catalyst and the hydrophilic metal oxide (when the inorganic oxidation catalyst is a hydrophilic metal oxide, the amount of the inorganic oxidation catalyst (or hydrophilic metal oxide) used) is applied to the entire thermal spray material. On the other hand, it may be 10 to 60% by weight (for example, 15 to 57% by weight), preferably 25 to 55% by weight (for example, 30 to 50 parts by weight), and more preferably about 40 to 50% by weight. The total amount of glass frit, inorganic oxidation catalyst and hydrophilic metal oxide is 100% by weight.

  Further, the ratio between the oxidation catalyst and the hydrophilic metal oxide is the former / the latter (weight ratio) = 15/85 to 90/10, preferably 27/75 to 85/15 (for example, 40/60 to 85/15). ), More preferably about 50/50 to 80/20 (for example, 65/35 to 80/20).

In selecting an inorganic oxidation catalyst and a hydrophilic metal oxide, safety, durability, availability, cost as well as influence on the properties of the coating must be considered. For example, K ₂ O, Na ₂ O, and Li ₂ O act as fluxes to increase the coefficient of thermal expansion, while B ₂ O ₃ increases fluidity, while reducing the corrosion resistance, weather resistance, chemical resistance, and thermal expansion coefficient. CaO acts as a flux to promote opacification, but there is a risk of generating bubbles in the coating due to thermal decomposition during thermal spraying. Further, MnO ₂ , NiO, and CoO act as adhesion agents and colorants, and Cr ₂ O ₃ , Cu ₂ O, FeO, and Fe ₂ O ₃ act as colorants (Non-Patent Document 1, Japan Corporation). “Enamel Technology Guidebook” (1996) edited by Sakai Industry Association.

[Form of thermal spray composition]
The form of the thermal spray composition of the present invention is not particularly limited, and may be, for example, a powder form, a granule form, a pellet form, a rod form, or the like. These forms may be a mixture of a glass frit, an oxidation catalyst, and a hydrophilic metal oxide (powder-like mixture), and a form of the molded body formed from this mixture and a binder (the powder form, In the form of granules, pellets, rods, etc., and in the form of a melt or melt-cooled body in which the mixture is melt-mixed (forms such as powder, granules, pellets, rods, etc.) There may be.

  The form of the thermal spray composition is usually in the form of a powder (such as a mixed powder of glass frit, an oxidation catalyst and a hydrophilic metal oxide) or a rod. In particular, in order to facilitate use in a thermal spraying apparatus, the thermal spray composition (thermal spray material) may be a rod-shaped molded body molded into a rod (rod) shape, or a hollow body (such as a thermally decomposable resin). A cylindrical molded body (a thermal spray composition on a thermally decomposable resin tube) composed of a resin hollow cylinder and a thermal spray composition (for example, powder thermal spray material such as mixed powder) filled in the hollow body It may be a tube-shaped molded product filled with a product. In addition, in the powdery composition, there is a possibility that the fluidity may be reduced due to each component, size and shape, and stable spraying may not be performed. There is an advantage that it can be thermally sprayed stably.

  The binder for forming the hollow body and the mixture is preferably formed of a material that is completely decomposed by thermal spraying heat and does not leave residues such as carbides. The type of resin and binder forming the hollow body is not particularly limited. For example, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl ether, polyethylene, polypropylene, Non-aromatic resins such as (meth) acrylic resins (resins containing monomers selected from olefins not containing fluorine atoms, vinyl esters, and (meth) acrylic monomers, for example, resins having a large oxygen index) Etc.). For example, a resin hollow body can be formed of polypropylene, polyethylene, or the like, and polytetrafluoroethylene PTFE or tetrafluoroethylene PFA may cause a residue with thermal spraying. In selecting the resin hollow body and the binder, it is desirable to grasp the thermal characteristics of the material by thermogravimetry TG / differential thermal analysis DTA or the like.

  The outer diameter of the hollow body is not particularly limited, and may be, for example, about 1 to 5 mm, preferably about 2.5 to 4.0 mm, and more preferably about 2.7 to 3.5 mm. The outer diameter of the hollow body may be an outer diameter that can be directly applied to a torch nozzle that is normally used in a commercially available wire (melting wire) type gas flame spraying apparatus, for example, about 3.0 to 3.2 mm. The inner diameter of the hollow body may be, for example, about 0.7 to 4.5 mm depending on the amount of the desired thermal spray material, and is usually 1.5 to 3.5 mm, preferably 1.7 to It may be about 3 mm (for example, 1.7 to 2.7 mm).

[Sprayed coating]
The thermal spray coating of the present invention can be formed by spraying a thermal spray composition on a substrate, and a member provided with the thermal spray coating can be manufactured by such thermal spraying. The sprayed coating forms a soot-like coating and has at least self-cleaning properties with an inorganic oxidation catalyst. In such a sprayed coating, the oxidation catalyst and / or the hydrophilic metal oxide are uniformly complexed in the coating mainly composed of glass frit, not only having a catalytic action by the oxidation catalyst, Hydrophilization of the coating surface is promoted by the hydrophilic metal oxide. For this reason, even caulked dirt can be easily removed by the synergistic effect of catalytic oxidative decomposition and hydrophilic action due to increased water penetration between the caulked dirt and the coating interface.

  A highly hydrophilic sprayed coating has a small contact angle with water. Therefore, the contact angle is a hydrophilic index. The contact angle of the sprayed coating with respect to water may be, for example, about 5 to 55 ° at a temperature of 20 ° C. and a relative humidity of 55%, and is usually 8 to 45 ° (for example, 10 to 40 °), preferably 10 It may be about -35 ° (for example, 10-30 °), more preferably about 10-20 ° (for example, 10-15 °). In addition, as the content of the hydrophilic metal oxide increases, a sprayed coating with small contact with water can be formed.

  The type of the substrate is not particularly limited, and may be, for example, metal (steel, stainless steel, aluminum, etc.), ceramics, or the like. Moreover, as long as a sprayed coating can be formed, the dimension and shape of the substrate are not particularly limited, and may be a flat plate shape, a curved surface shape, a bent shape, or the like.

  The substrate is preferably subjected to a surface roughening treatment in order to enhance the adhesion with the sprayed coating. The surface roughening treatment may be a conventional surface roughening treatment such as a chemical solution or plasma treatment, but can be performed by a shot blast method or the like. Further, in order to form an amorphous coating, it is preferable to spray the substrate on a preheated substrate. Since the preheat treatment temperature varies depending on the material of the base material and the nature of the glass frit, it can be selected according to the type of the base material and the glass frit, and may be, for example, about 600 to 750 ° C., preferably about 650 to 700 ° C. . Thermal spraying can be performed by a conventional method depending on the type of thermal spraying apparatus.

  The thickness of the thermal spray coating is not particularly limited, and can be selected according to the use. For example, the thickness may be 10 to 1000 μm, preferably 20 to 800 μm, and more preferably about 100 to 500 μm.

  The sprayed coating formed in this way has high adhesion to the substrate, stably exhibits at least an oxidation catalytic action, and decomposes dirt. Further, when a hydrophilic metal oxide is used, even caulked dirt can be easily removed as the sprayed coating becomes hydrophilic.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Examples 1-8, Reference Examples 1-2 and Comparative Example 1
[Spraying composition (spraying material)]
In the examples, commercially available silicon oxide glass frit is used, commercially available reagent first grade products are used for the oxidation catalyst and the hydrophilic metal oxide, and the components shown in Table 1 are mixed at a predetermined ratio to obtain a powdered spray material. Was prepared. A polyethylene PE resin tube (outer diameter: 3 mm, inner diameter: 2 mm) was filled with the powdered thermal spray material of each example , reference example and comparative example, and a tube-shaped molded body was also prepared. In Comparative Example 1, a silicon oxide glass frit was used.

[Formation of sprayed coating]
A mild steel SS400 substrate (50 × 50 × 4.5 mm) is roughened in advance by an alumina grid blasting method, and the mild steel SS400 substrate preheated to 600 ° C. by powder gas flame spraying (oxygen-acetylene gas combustion flame) Thermal spray materials shown in Table 1 were sprayed to form a 200 μm thick coating. The main spraying conditions were set to gas pressure: oxygen O ₂ (0.4 MPa), acetylene C ₂ H ₂ (0.1 MPa), spraying distance: 100 mm, and spraying speed: 700 mm / second. Prior to thermal spraying, pre-heat treatment was performed using the gas flame spraying torch without supplying the thermal spray material, and the temperature of the substrate surface was measured and controlled with a radiation thermometer. The preheating temperature was 660 ° C.

[Crystal structure of thermal spray coating]
In FIG. 1, the X-ray-diffraction (XRD) pattern of the thermal spray coating formed with the thermal spray material of Example 1, 2, 8, and the comparative example 1 is shown. As is clear from the figure, in the thermal spray materials of Examples 1 and 2 and Comparative Example 1, an amorphous film is formed. On the other hand, the film formed from the thermal spray material of Example 8 shows weak diffraction, and amorphization is slightly reduced.

[Evaluation of self-cleaning properties]
Dirt that actually adheres in a heat cooker or the like is diverse, and the dirt components are not constant, and there is a risk of variations in the evaluation of the self-cleaning effect. In the examples of the present invention, commercially available edible salad oil (canola oil) with a clear composition is used for the simulated dirt, and the self-cleaning effect is obtained from the results of microscopic infrared spectroscopic analysis (microscopic IR) and visual observation. evaluated.

Degradation evaluation of dirt by microscopic IR analysis The salad oil was dropped on the coating formed with the thermal spray material of Comparative Example 1 and the coating formed with the thermal spray material of Example 3, and heated at 200 to 350 ° C. for 2 hours. Slow cooling was conducted in the air, and infrared (IR) absorption spectra were measured for simulated soil. FIG. 2 shows the IR absorption spectrum of the coating of Comparative Example 1, and FIG. 3 shows the IR absorption spectrum of the coating of Example 3. In Comparative Example 1, the spectrum of 2000～2500Cm ^-1 region from stretching vibration of 1500～2000Cm ^-1, and C≡C bonds derived from stretching vibration of C = C bonds with increasing heating temperature increases Salad oil polymerization and caulking are in progress. On the other hand, in Example 3, there is no large change in the spectrum accompanying the increase in heating temperature, indicating that a phenomenon different from coking, that is, decomposition by an oxidation catalyst occurs.

Therefore, paying attention to 1740 cm ⁻¹ derived from stretching vibration of C—O bond, which is one of peak spectra seen in microscopic IR, measurement was performed for each coating formed with the thermal spray material of Example 1 and Example 2. The absorption intensity (absorbance) ratio was determined from the microscopic IR spectrum. The results are shown in FIG. The vertical axis in FIG. 4 represents the rate of decrease based on the absorption intensity at a heating temperature of 200 ° C. The influence of the added amount of manganese oxide on the absorption intensity ratio is relatively small at 250 ° C., but becomes considerably large at 300 ° C.

Evaluation of hydrophilicity For coatings that were not sufficiently decomposed and removed by catalysis, they were immersed in water at 20 ° C. for 1 hour, and the state of removal of dirt (mainly caulked dirt) was visually observed. The removal of dirt by immersion in water is achieved by the water that has entered between the dirt and the adhesion surface floating the dirt. In order to facilitate the infiltration of water, it is effective to hydrophilize the dirt adhesion surface. For hydrophilicity, water droplets (1.8 mm ³ ) are dropped on the sprayed coating, and the contact angle with water (temperature 20 ° C.). And relative humidity 55%).

Degradation and removal effect of dirt In Table 2, for each of the coatings formed in Examples 1 to 8, Reference Examples 1 and 2 and Comparative Example 1, the degradation effect of the dirt by the oxidation catalyst and the measurement results of the contact angle (of 10-point measurement) Average value) and the effect of removing dirt by immersion in water. In addition, the decomposition | disassembly effect of stain | pollution | contamination and the removal effect of the stain | pollution | contamination by immersion in water were evaluated by the following judgment criteria.

++++: Complete decomposition removal effect ++ (+): Large decomposition removal effect ++: Medium decomposition removal effect
+: Slight decomposition removal effect 0: No change

As shown in Table 2, all of Examples show high removal ability against dirt ((mainly caulked dirt)). In particular, the thermal spray coating of Example 4 shows the most effective results for the decomposition and removal of dirt. This is probably because manganese dioxide MnO ₂ effectively removes dirt not only by catalytic action but also by hydrophilic action.

  The present invention is useful for removing dirt by applying it to members, parts, and devices that easily adhere to dirt. In particular, since it has a high ability to remove caulked stubborn dirt, it can be applied to cooking utensils, heating utensils, etc., and is effective in preventing the adhesion of dirt and removing dirt.

Claims (11)

A thermal spray composition comprising a glass frit capable of forming a thermal spray coating, and at least an inorganic oxidation catalyst and a hydrophilic metal oxide , wherein the inorganic oxidation catalyst comprises a low temperature active inorganic oxidation catalyst and a high temperature active inorganic oxidation catalyst. Including
The low-temperature active inorganic oxidation catalyst is an oxide of a metal element belonging to Group 7, Group 9, Group 10 and Group 11 of the Periodic Table (however, the valence of the Group 11 metal element is monovalent) Including at least one selected from
The high-temperature active inorganic oxidation catalyst is an oxide or phosphate of a metal element belonging to Group 5, Group 8, Group 11 and Group 12 of the periodic table (however, the valence of Group 8 metal element of the periodic table) Is trivalent, and the valence of the Group 11 metal element is divalent).
The hydrophilic metal oxide includes at least one selected from oxides of metal elements belonging to Groups 4 and 13 of the periodic table;
The thermal spray composition whose total amount of an inorganic oxidation catalyst and a hydrophilic metal compound is 15 to 60 weight% with respect to the whole thermal spray material . The low-temperature active inorganic oxidation catalyst includes at least one selected from oxides of metal elements belonging to Groups 7 and 10 of the periodic table;
The thermal spray composition according to claim 1 , wherein the high-temperature active inorganic oxidation catalyst contains at least one selected from oxides and phosphates of metal elements belonging to Groups 8 and 11 of the periodic table . The thermal spray composition according to claim 1 or 2 , wherein the total amount of the inorganic oxidation catalyst and the hydrophilic metal compound is 40 to 60% by weight based on the entire thermal spray material . The thermal spray composition according to any one of claims 1 to 3, wherein a ratio of the low temperature active inorganic oxidation catalyst to the high temperature active inorganic oxidation catalyst is the former / the latter (weight ratio) = 5/95 to 97/3. . The content of the inorganic oxidation catalyst is 5 to 100 parts by weight with respect to 100 parts by weight of the glass frit, and the content of the hydrophilic metal oxide is 5 to 60 parts by weight with respect to 100 parts by weight of the glass frit. The thermal spray composition according to any one of claims 1 to 4 , wherein the total amount of the inorganic oxidation catalyst and the hydrophilic metal oxide is 20 to 150 parts by weight with respect to 100 parts by weight of the glass frit. The thermal spray composition according to any one of claims 1 to 5 , wherein the ratio of the inorganic oxidation catalyst and the hydrophilic metal oxide is the former / the latter (weight ratio) = 10/90 to 90/10. The thermal spray composition according to any one of claims 1 to 6 , which is in the form of powder, granules, pellets or rods. The thermal spray composition according to any one of claims 1 to 7 , which is filled in a hollow cylinder of a thermally decomposable resin. The thermal spray coating formed with the thermal spray composition in any one of Claims 1-8 . The thermal spray coating according to claim 9 , which has self-cleaning properties. A method for producing a member having a thermal spray coating by thermally spraying the thermal spray composition according to any one of claims 1 to 7 on a substrate.