Slurry composition and coating agent

Abstract

[Solution] A slurry composition according to the present invention contains a dispersion medium and particles of a complex oxide including La and at least one element selected from the group consisting of Mo and W. The central particle diameter of the particles is not more than 800 nm. The percentage content of the particles is 0.1-10 mass%.

Description

[Technical Field]

[0001] The present invention relates to a slurry composition and a coating agent. [Background technology]

[0002] As shown in Patent Document 1, ceramics made of composite oxides containing rare earth elements and molybdenum (Mo) are known as new types of inorganic materials with antibacterial and antiviral properties. Among such ceramics, those made of composite oxides containing lanthanum (La) as a rare earth element (for example, La2Mo2O9) have attracted particular attention because they use lanthanum, which is inexpensive and easily available among rare earth elements, and are therefore advantageous for industrial production.

[0003] Patent Document 1 discloses that a ceramic powder of a composite oxide containing lanthanum and molybdenum is combined with a known binder resin and a solvent, and the combined mixture is applied to the surface of a desired article as an ink or paste to form a film containing the composite oxide ceramic. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 017493

[0005] (Problem to be solved by the invention) Conventionally, antibacterial or antiviral properties have been imparted by forming a powder having antibacterial or antiviral properties, such as silver powder, into a slurry and using the slurry as a coating agent or by mixing it into a paint.

[0006] However, no such study has been conducted on ceramic powders such as the composite oxide containing lanthanum and molybdenum. The specific gravity of the composite oxide containing lanthanum and molybdenum is 5.5 / cm 3However, because the particle size is relatively large, the powder settles quickly, resulting in rapid solid-liquid separation. Summary of the Invention

[0007] An object of the present invention is to provide a slurry composition and a coating agent in which the settling rate of La-based composite oxide particles is retarded.

[0008] (Means for solving the problem) As a result of extensive research to achieve the above object, the present inventors have found that when particles of a composite oxide containing at least one element selected from the group consisting of Mo and W have a median particle diameter of 800 nm or less and the content of the particles is 0.1 to 10 mass %, the settling rate of the particles is slowed, making them applicable to an object, and have completed the present invention.

[0009] The means for solving the above problems are as follows: <1> A slurry composition comprising particles of a composite oxide containing La and at least one element selected from the group consisting of Mo and W, and a dispersion medium, wherein the particles have a median particle size of 800 nm or less, and the content of the particles is 0.1 to 10 mass %.

[0010] <2> The composite oxide is LaMo x W (2-X) O9 (0≦x≦2) <1> The slurry composition according to claim 1.

[0011] <3> The above-mentioned containing a binder <1> or <2> The slurry composition according to claim 1.

[0012] <4> The above-mentioned containing a dispersant <1> from <3> 10. The slurry composition according to claim 9, wherein the slurry composition is a mixture of 100% or more of the above-mentioned components.

[0013] <5> The above-mentioned material containing ultraviolet curable resin <1> from <4> 10. The slurry composition according to claim 9, wherein the slurry composition is a mixture of 100% or more of the above-mentioned components.

[0014] <6> The aforementioned <1> from <5> A coating agent comprising the slurry composition according to any one of the above.

[0015] (Effects of the Invention) According to the present invention, it is possible to provide a slurry composition and a coating agent in which the settling rate of La-based composite oxide particles is retarded. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 shows an SEM image of the La-Mo composite oxide particles of Example 2. [Figure 2] Photographs showing the appearance of the slurry compositions of Examples 1 and 2. [Figure 3] FIG. 1 is a photograph showing the appearance of the slurry composition of Comparative Example 1 filled in a small bottle. [Figure 4] FIG. 1 shows a photograph of the appearance of the slurry composition of Example 15. [Figure 5] 2 is a graph showing the transmittance (%) of the slurry composition of Example 2. [Figure 6] FIG. 1 shows an SEM image of La-Mo composite oxide particles of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0017] The slurry composition of this embodiment is a liquid composition containing La-based composite oxide particles and a dispersion medium.

[0018] In this specification, a composite oxide containing La and at least one element selected from the group consisting of Mo and W is referred to as an "La-based composite oxide." Such a La-based composite oxide has excellent antibacterial and antiviral properties.

[0019] The La-based composite oxide is, for example, LaMo x W (2-X) It is expressed as O9(0≦x≦2).

[0020] Specific La-based composite oxides include, for example, La-Mo-based composite oxides, La-Mo-W-based composite oxides, and La-W-based composite oxides.

[0021] From the viewpoints of antibacterial and antiviral properties, etc., it is preferable that the La-Mo-based composite oxide contains Mo as the element. That is, as the La-based composite oxide, La2Mo x W (2-X) represented by O9 (0 < x ≦ 2) is preferable.

[0022] In this specification, particles of La-based composite oxides (that is, particulate La-based composite oxides) are represented as "La-based composite oxide particles".

[0023] In this specification, a composite oxide of lanthanum (La) and molybdenum (Mo) is represented as "La-Mo-based composite oxide", and particles of La-Mo-based composite oxide (that is, particulate La-Mo-based composite oxide) are represented as "La-Mo-based composite oxide particles".

[0024] Also, in this specification, a composite oxide of lanthanum (La), molybdenum (Mo), and tungsten (W) is represented as "La-Mo-W-based composite oxide", and particles of La-Mo-W-based composite oxide (that is, particulate La-Mo-W-based composite oxide) are represented as "La-Mo-W-based composite oxide particles".

[0025] Also, in this specification, a composite oxide of lanthanum (La) and tungsten (W) is represented as "La-W-based composite oxide", and particles of La-W-based composite oxide (that is, particulate La-W-based composite oxide) are represented as "La-W-based composite oxide particles".

[0026] The La-based composite oxide particles have a median particle size of 800 nm or less, preferably 600 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. When the median particle size of the La-based composite oxide particles is within this range, the settling velocity of the La-based composite oxide particles in the dispersion medium is sufficiently slowed, thereby improving the dispersibility of the La-based composite oxide particles and enabling the slurry composition to be applied to an object.

[0027] The median particle size of the La-based composite oxide particles is determined as the particle size (D50) at which the cumulative frequency reaches 50% by laser diffraction. A specific method for measuring the median particle size using a laser diffraction particle size distribution analyzer will be described later.

[0028] In measuring the median particle diameter using the particle size distribution analyzer, if the measurement result is below the lower measurement limit, the accurate particle diameter (median particle diameter) cannot be determined. Therefore, if the measurement result using the particle size distribution analyzer is 100 nm or less, in addition to the measurement method using the particle size distribution analyzer, the particle diameter was measured using an FE-SEM (Field Emission-Scanning Electron Microscope). In a measurement method using FE-SEM, for example, the La-based composite oxide powder in the slurry composition may be adhered to the surface of an appropriate object, and the particle diameter may be determined from the La-based composite oxide powder contained in the adhered material. Note that a specific method for measuring particle diameter using FE-SEM will be described later.

[0029] The La-Mo based composite oxide is not particularly limited as long as it does not impair the object of the present invention, and examples thereof include La2Mo2O9. The La-Mo based composite oxide may consist of only La2Mo2O9, or may contain other components in addition to La2Mo2O9.

[0030] The La-Mo-W based composite oxide is not particularly limited as long as it does not impair the object of the present invention. For example, La2MoWO9, La2Mo 1.5 W 0.5 O9, La2Mo 0.5 W 1.5O9, etc. These may be used alone or in combination of two or more.

[0031] The La-W based composite oxide is not particularly limited as long as it does not impair the object of the present invention, and examples thereof include La2W2O9. The La-W based composite oxide may consist solely of La2W2O9, or may contain other components in addition to La2W2O9.

[0032] The La-based composite oxide particles such as the La-Mo-based composite oxide particles are produced, for example, through a preparation step, a first firing step, and a pulverization step.

[0033] When the La-based composite oxide particles are La-Mo-based composite oxide particles, the preparation step is a step of mixing a lanthanum compound and a molybdenum compound to prepare a mixed powder.

[0034] When the La-based composite oxide particles are La-Mo-W-based composite oxide particles, the preparation step is a step of mixing a lanthanum compound, a molybdenum compound, and a tungsten compound to prepare a mixed powder.

[0035] When the La-based composite oxide particles are La-W-based composite oxide particles, the preparation step is a step of mixing a lanthanum compound and a tungsten compound to prepare a mixed powder.

[0036] Lanthanum compounds are compounds containing lanthanum (La), which is necessary for producing La-based composite oxides such as La-Mo-based composite oxides, and examples thereof include La(OH)3, La2O3, and La2(CO3)3. As the lanthanum compound, for example, at least one selected from the group consisting of La(OH)3, La2O3, and La2(CO3)3 may be used. Note that La(OH)3 is preferred as the lanthanum compound.

[0037] The molybdenum compound is a compound containing molybdenum (Mo) necessary for producing a La-Mo based composite oxide or a La-Mo-W based composite oxide, and examples thereof include MoO3, MoO2, MoO, Mo(OH)3, and Mo(OH)5. As the molybdenum compound, for example, at least one selected from the group consisting of MoO3, MoO2, MoO, Mo(OH)3, and Mo(OH)5 may be used. Note that MoO3 is preferred as the molybdenum compound.

[0038] The tungsten compound is a compound containing tungsten (W) necessary for producing a La-Mo-W based composite oxide or a La-W based composite oxide, and examples thereof include WO3, WO2, and W2O3. WO3 is preferred as the tungsten compound.

[0039] When preparing the La-Mo based composite oxide, the mixing ratio of the lanthanum compound and the molybdenum compound is preferably adjusted so that the molar ratio of La:Mo is 1:1.

[0040] When preparing the La-Mo-W based composite oxide, the mixing ratio of the lanthanum compound, the molybdenum compound and the tungsten compound is preferably adjusted to a molar ratio of La:Mo:W=2:1.5-0.5:0.5-1.5.

[0041] When preparing the La—W-based composite oxide, the mixing ratio of the lanthanum compound and the tungsten compound is preferably adjusted to a molar ratio of La:W=2:1.5-0.5:0.5-1.5.

[0042] The raw materials for the La-based composite oxide, such as lanthanum compounds, molybdenum compounds, and tungsten compounds, are each in the form of powder, and may be mixed together in powder form, or a solvent such as a lower alcohol (ethanol) may be added to the powders to perform wet mixing. The raw materials may be mixed together using, for example, alumina balls (alumina boulders). The wet-mixed mixture (wet mixture) is then dried as appropriate by water bath drying, spray drying, or the like.

[0043] By such a preparation process, a mixed powder of a lanthanum compound and a molybdenum compound, a mixed powder of a lanthanum compound, a molybdenum compound and a tungsten compound, or a mixed powder of a lanthanum compound and a tungsten compound can be obtained.

[0044] The first firing step is a step of firing the mixed powder obtained in the preparation step in order to react the lanthanum compound, the molybdenum compound, etc., in the mixed powder. In the first firing step, the mixed powder is fired, for example, at a temperature condition of 500°C to 900°C for 1 hour or more. Note that the first firing step does not need to be performed in a special synthetic air atmosphere, and is performed in a normal atmospheric pressure atmosphere.

[0045] When the mixed powder is a mixed powder of a lanthanum compound and a molybdenum compound, the lanthanum compound and the molybdenum compound in the mixed powder react with each other in the first firing step to produce a La-Mo-based composite oxide containing LaMoO and the like.

[0046] When the mixed powder is a mixed powder of a lanthanum compound, a molybdenum compound, and a tungsten compound, the lanthanum compound, the molybdenum compound, and the tungsten compound in the mixed powder react with each other to produce a La-Mo-W-based composite oxide including LaMoWO and the like.

[0047] When the mixed powder is a mixed powder of a lanthanum compound and a tungsten compound, the lanthanum compound and the tungsten compound in the mixed powder react with each other to produce a La-W based composite oxide containing La2W2O9 and the like.

[0048] The pulverization step is a step in which the La-based composite oxide after the first firing is pulverized using a media stirring pulverizer such as a bead mill so that the median particle size of the La-based composite oxide falls within a predetermined range. The pulverization conditions, such as the pulverization time, are appropriately set so that the median particle size of the La-based composite oxide falls within the predetermined range.

[0049] In this manner, La-based composite oxide particles such as La-Mo-based composite oxide particles having a predetermined median particle size, which are used in a slurry composition, are obtained.

[0050] The obtained La-based composite oxide particles may be granulated as necessary. For example, a solvent such as ethanol is added to the La-based composite oxide particles, and wet mixing and grinding is carried out using alumina balls or the like to prepare a slurry, and the dried slurry is passed through a sieve with a predetermined mesh size to obtain La-based composite oxide particles granulated to a predetermined size.

[0051] Furthermore, as long as it does not impair the scope of the present invention, the "La-based composite oxide particles" used in the slurry composition may be obtained by sintering La-based composite oxide particles and then pulverizing the resulting sintered body (pulverized product). The sintered body can be obtained, for example, by molding the La-based composite oxide particles before sintering into a predetermined shape and firing the resulting molded body under predetermined temperature conditions (e.g., 900°C or higher). In this specification, the firing step performed to sinter the La-based composite oxide particles is referred to as the "second firing step." This second firing step can be performed in an air atmosphere. Note that the La-based composite oxide obtained after the second firing step is, if necessary, adjusted to particles having a median particle size within a predetermined range by a pulverization step.

[0052] The dispersion medium used in the slurry composition may be water, ethanol, isopropyl alcohol (IPA), methyl ethyl ketone (MEK), ethyl acetate, toluene, etc. These may be used alone or in combination of two or more.

[0053] The content of the La-based composite oxide particles in the slurry composition is 0.1 to 10 mass %.

[0054] The slurry composition may contain other components in addition to the La-based composite oxide particles and the dispersion medium, as long as the object of the present invention is not impaired.

[0055] Examples of other components (compounds) include binders, dispersants, ultraviolet curable resins, colorants (pigments, dyes), etc. Components other than these may also be used as other components.

[0056] The binder is used for the purpose of improving the adhesion of the La-based composite oxide particles contained in the slurry composition to the target object. There are no particular limitations on such binders as long as they do not impair the object of the present invention, and examples thereof include polyvinyl alcohol (PVA) and polyvinyl butyral (PVB). These may be used alone or in combination of two or more.

[0057] The content of the binder in the slurry composition is not particularly limited as long as it does not impair the object of the present invention, but is preferably 0.05 to 5 mass % relative to the La-based composite oxide particles, for example.

[0058] The dispersant is used for the purpose of increasing the dispersibility of the La-based composite oxide particles in the dispersion medium. Such dispersants are not particularly limited as long as they do not impair the object of the present invention, and examples thereof include water-soluble acrylic acid-based dispersants, anionic surfactants, cationic surfactants, nonionic surfactants, polyethylene glycol (PEG)-polypropylene glycol (PPG) block polymers, ammonium polyacrylates, and polycarboxylic acid copolymers having alkyl chains or polyalkylene glycol (PAG) chains. These may be used alone or in combination of two or more.

[0059] The content of the dispersant in the slurry composition is not particularly limited as long as it does not impair the object of the present invention, but is preferably, for example, 5 mass % or less relative to the La-based composite oxide particles.

[0060] The slurry composition of this embodiment can be used as a coating agent by including a curing agent. Any curing agent can be selected as long as it does not impair the objectives of the present invention, such as a curing agent in which a synthetic resin is dissolved in a volatile solvent, a moisture-curing curing agent, a two-liquid mixture curing agent, or an ultraviolet-curing curing agent. The curing agent is used for purposes such as improving the adhesion of the La-based composite oxide particles contained in the slurry composition to a target object. Examples of ultraviolet-curing resins used in ultraviolet-curing curing agents include acrylic ultraviolet-curing resins.

[0061] The content of the ultraviolet curable resin in the slurry composition is not particularly limited as long as it does not impair the object of the present invention, but is preferably, for example, 5 mass % or less relative to the La-based composite oxide particles.

[0062] The slurry composition (coating agent) of this embodiment may also contain a pigment. The pigment is used for purposes such as coloring a coating film containing La-based composite oxide particles formed on the surface of an object. The pigment may be water-based or oil-based. There are no particular limitations on the pigment, and examples include carbon black, synthetic resin, metal powder, and minerals. These may be used alone or in combination of two or more.

[0063] The object to which the slurry composition is applied is not particularly limited, and examples of materials constituting the object include glass, ceramics, synthetic resins such as thermoplastic resins and thermosetting resins, rubber (natural rubber and synthetic rubber), genuine leather (natural leather), synthetic leather, metallic materials made of metals or alloys, wood, paper, fibers, nonwoven fabrics, silicon (silicon wafers, etc.), carbon materials, minerals, etc.

[0064] The slurry composition can be applied to the object by, for example, brushing, roller, blade casting, or dipping. The slurry composition can be dried after application by known methods such as natural drying or heating in a drying oven. It is preferable to select a method that prevents aggregation of the La-based composite oxide particles.

[0065] The present invention will be further described below with reference to examples, although the present invention is not limited to these examples in any way.

[0066] Example 1 La(OH)3 was prepared as the lanthanum compound, and MoO3 was prepared as the molybdenum compound. Then, raw material powders of the lanthanum compound and the molybdenum compound were weighed out so that the molar ratio was 1:1 (La:Mo=1:1). After weighing, the raw material powders were mixed with a predetermined amount of ethanol, and the resulting wet mixture was dried to obtain a mixed powder.

[0067] Next, the mixed powder was fired in an air atmosphere at a temperature of 700° C. for 10 hours to obtain a fired powder consisting of a reaction product of the lanthanum compound and the molybdenum compound.

[0068] The resulting fired powder was then pulverized in a bead mill for 4.5 hours to obtain La-Mo composite oxide particles. The La-Mo composite oxide particles of Example 1 had a median particle size of 100 nm or less. The method for measuring the median particle size will be described later.

[0069] The La-Mo composite oxide particles were mixed with water (dispersion medium) so that the solid content concentration in the final slurry composition would be 1 mass %, and the mixture was stirred to obtain the slurry composition of Example 1.

[0070] Example 2 A slurry composition of Example 2 was obtained in the same manner as in Example 1, except that a dispersant was added (1% by mass relative to the La—Mo-based composite oxide particles).

[0071] Example 3 A slurry composition of Example 3 was obtained in the same manner as in Example 1, except that a binder and a dispersant were mixed (0.1 mass % (binder) and 1 mass % (dispersant) relative to the La-Mo-based composite oxide particles).

[0072] Example 4 The slurry composition of Example 4 was obtained in the same manner as in Example 1, except that an ultraviolet curable resin and a dispersant were mixed (0.1 mass % (ultraviolet curable resin) and 1 mass % (dispersant) relative to the La-Mo based composite oxide particles).

[0073] Example 5 The slurry composition of Example 5 was obtained in the same manner as in Example 1, except that the La-Mo composite oxide particles were mixed with water (dispersion medium) so that the solid content concentration in the final slurry composition would be 8 mass %, and a dispersant was also mixed (1 mass % relative to the La-Mo composite oxide particles).

[0074] Example 6 A calcined powder was prepared in the same manner as in Example 1, and the calcined powder was pulverized in a pot mill for 90 hours to obtain La-Mo-based composite oxide particles of Example 6. The La-Mo-based composite oxide particles of Example 6 had a median particle diameter of 600 nm. The method for measuring the median particle diameter will be described later.

[0075] The La-Mo composite oxide particles of Example 6 were mixed with water (dispersion medium) so that the solid content concentration in the final slurry composition would be 1 mass %, and a dispersant was further added (1 mass % relative to the La-Mo composite oxide particles), and the mixture was stirred to obtain the slurry composition of Example 6.

[0076] Example 7 A calcined powder was prepared in the same manner as in Example 1, and the calcined powder was pulverized in a bead mill for 4.5 hours to obtain La-Mo-based composite oxide particles of Example 7. The La-Mo-based composite oxide particles of Example 6 had a median particle size of 150 nm.

[0077] The La-Mo composite oxide particles were mixed with ethanol (dispersion medium) so that the solid content concentration in the final slurry composition would be 1 mass %, and a dispersant was further added (1 mass % relative to the La-Mo composite oxide particles), and the mixture was stirred to obtain the slurry composition of Example 7.

[0078] Example 8 A calcined powder was prepared in the same manner as in Example 1, and the calcined powder was pulverized in a pot mill for 75 hours to obtain La-Mo-based composite oxide particles of Example 8. The La-Mo-based composite oxide particles of Example 8 had a median particle size of 800 nm.

[0079] The La-Mo composite oxide particles were mixed with water (dispersion medium) so that the solid content concentration in the final slurry composition would be 1 mass %, and a dispersant was further added (1 mass % relative to the La-Mo composite oxide particles), and the mixture was stirred to obtain the slurry composition of Example 8.

[0080] Example 9 A calcined powder was prepared in the same manner as in Example 1, and the calcined powder was pulverized in a pot mill for 70 hours to obtain La-Mo-based composite oxide particles of Example 9. The La-Mo-based composite oxide particles of Example 9 had a median particle size of 800 nm.

[0081] The La-Mo composite oxide particles were mixed with water (dispersion medium) so that the solid content concentration in the final slurry composition would be 10 mass %, and a dispersant was further added (1 mass % relative to the La-Mo composite oxide particles), and the mixture was stirred to obtain the slurry composition of Example 9.

[0082] Example 10 La(OH)3 was prepared as the lanthanum compound, MoO3 as the molybdenum compound, and WO3 as the tungsten compound. The raw material powders of the lanthanum compound, the molybdenum compound, and the tungsten compound were weighed out in a molar ratio of 2:1:1 (La:Mo:W=2:1:1). The weighed raw material powders were mixed with a predetermined amount of ethanol, and the resulting wet mixture was dried to obtain a mixed powder.

[0083] Next, the mixed powder was fired in an air atmosphere at a temperature of 650° C. for 10 hours to obtain a fired powder consisting of a reaction product of a lanthanum compound, a molybdenum compound, and a tungsten compound.

[0084] The resulting fired powder was then pulverized in a bead mill for 6 hours to obtain La-Mo-W composite oxide particles, the median particle size of which was 100 nm or less in Example 10.

[0085] The La-Mo-W composite oxide particles were mixed with water (dispersion medium) so that the solid content in the final slurry composition was 1% by mass, and the mixture was stirred to obtain the slurry composition of Example 10.

[0086] Example 11 The slurry composition of Example 11 was obtained in the same manner as in Example 10, except that the raw material powder of the lanthanum compound, the raw material powder of the molybdenum compound, and the raw material powder of the tungsten compound were weighed out so as to have a molar ratio of 2:1.5:0.5 (La:Mo:W=2:1.5:0.5) to prepare the wet mixture.

[0087] Example 12 The slurry composition of Example 12 was obtained in the same manner as in Example 10, except that the raw material powder of the lanthanum compound, the raw material powder of the molybdenum compound, and the raw material powder of the tungsten compound were weighed out so as to have a molar ratio of 2:0.5:1.5 (La:Mo:W=2:0.5:1.5) to prepare the wet mixture.

[0088] Example 13 A calcined powder was prepared in the same manner as in Example 10, and the calcined powder was pulverized in a pot mill for 75 hours to obtain La-Mo-W-based composite oxide particles of Example 13. The median particle diameter of the particles of Example 13 was 800 nm.

[0089] The La-Mo-W composite oxide particles were mixed with water (dispersion medium) so that the solid content in the final slurry composition was 10 mass %, and the mixture was stirred to obtain the slurry composition of Example 13.

[0090] Example 14 La(OH)3 was prepared as the lanthanum compound, and WO3 was prepared as the tungsten compound. Then, the raw material powder of the lanthanum compound and the raw material powder of the tungsten compound were weighed out so that the molar ratio was 1:1 (La:W = 1:1). After weighing, each raw material powder was mixed with a predetermined amount of ethanol, and the resulting wet mixture was dried to obtain a mixed powder.

[0091] Next, the mixed powder was fired in an air atmosphere at a temperature of 700° C. for 10 hours to obtain a fired powder consisting of a reaction product of the lanthanum compound and the tungsten compound.

[0092] The resulting fired powder was then pulverized in a bead mill for 4.5 hours to obtain La—W-based composite oxide particles, the median particle size of which was 100 nm or less in Example 14.

[0093] The La-W-based composite oxide particles were mixed with water (dispersion medium) so that the solid content in the final slurry composition was 1% by mass, and the mixture was stirred to obtain the slurry composition of Example 14.

[0094] Example 15 A calcined powder was prepared in the same manner as in Example 14, and the calcined powder was pulverized in a pot mill for 75 hours to obtain La—W-based composite oxide particles of Example 15. The median particle diameter of the particles of Example 15 was 800 nm.

[0095] The La-W-based composite oxide particles were mixed with water (dispersion medium) so that the solid content in the final slurry composition was 1% by mass, and the mixture was stirred to obtain the slurry composition of Example 15.

[0096] Comparative Example 1 A calcined powder was prepared in the same manner as in Example 1, and the calcined powder was pulverized in a pot mill for 15 hours to obtain La-Mo-based composite oxide particles of Comparative Example 1. The La-Mo-based composite oxide particles of Comparative Example 1 had a median particle diameter of 2300 nm.

[0097] The La-Mo composite oxide particles were mixed with water (dispersion medium) so that the solid content concentration in the final slurry composition would be 1 mass %, and the mixture was stirred to obtain the slurry composition of Comparative Example 1.

[0098] Comparative Example 2 A calcined powder was prepared in the same manner as in Example 1, and the calcined powder was pulverized in a pot mill for 90 hours to obtain La-Mo-based composite oxide particles of Comparative Example 2. The La-Mo-based composite oxide particles of Comparative Example 2 had a median particle diameter of 600 nm.

[0099] The La-Mo composite oxide particles were mixed with water (dispersion medium) so that the solid content concentration in the final slurry composition would be 20 mass %, and a dispersant was further added (1 mass % relative to the La-Mo composite oxide particles), and the mixture was stirred to obtain the slurry composition of Comparative Example 2.

[0100] [Measurement of median particle size (D50) by laser diffraction method] The median particle diameters (D50) of the La-based composite oxides (La-Mo-based composite oxides, La-Mo-W-based composite oxides, and La-W-based composite oxides) of Examples 1 to 15 and Comparative Examples 1 and 2 were measured using a laser diffraction particle size analyzer (model "LA-950", manufactured by Horiba, Ltd.) under the following measurement conditions:

[0101] <Measurement conditions> An aqueous solution of sodium hexametaphosphate with a concentration of 2% by mass was designated Solution A. Furthermore, La-based composite oxide particles (measurement target) were added to the aqueous solution of sodium hexametaphosphate with a concentration of 2% by mass and stirred with a homogenizer to uniformly disperse the La-based composite oxide particles, which was designated Solution B. 0.5 mL of Solution B was added dropwise to Solution A to prepare Solution C, in which the La-based composite oxide particles had a concentration of 1% by mass or less and in which the La-based composite oxide particles were monodispersed. Then, using this Solution C, the particle diameter (D50) at which the cumulative frequency reached 50% was determined as the median particle diameter using a laser diffraction particle size analyzer. The measurement results of the median particle diameter (D50) for each example are shown in Table 1.

[0102] The measurement results (median particle diameter) of the La-Mo-based composite oxide particles in Examples 1 to 5, the measurement results (median particle diameter) of the La-Mo-W-based composite oxide particles in Examples 10 to 12, and the measurement results (median particle diameter) of the La-W-based composite oxide particles in Example 14 were 100 nm or less. Therefore, for Examples 1 to 5, 10 to 12, and 14, the particle diameters were measured using FE-SEM as follows.

[0103] [Measurement of particle size using FE-SEM] The particle diameters of the La-based composite oxide particles of Examples 1 to 5, 10 to 12, and 14 were determined using FE-SEM according to the following procedure. Here, the slurry composition of Example 2 was dropped onto a carbon tape, which was then dried and used as the measurement object. To prevent particle aggregation during drying, the dropped slurry composition was diluted with an appropriate dispersion medium (e.g., water) to enable observation of individual particles in the slurry composition. Figure 1 shows an SEM image of the La-Mo-based composite oxide particles (La-based composite oxide particles) of Example 2. An SEM image (magnification: 100,000) of the La-Mo-based composite oxide particles of Example 2 was acquired, and multiple individual particles of the La-Mo-based composite oxide particles were extracted from the SEM image using predetermined image analysis software. The circle-equivalent diameter (μm) of each extracted individual particle was then calculated using analysis software WinROOF2018. From the results of the multiple equivalent circle diameters (μm) thus obtained, the particle diameter (average particle diameter) of the La-Mo composite oxide particles was calculated. As a result, the particle diameter (average particle diameter) of the La-Mo composite oxide powders of Examples 1 to 5 was 0.05 μm (50 nm, reference value).

[0104] Appearance of Slurry Composition and Redispersion As shown in Figure 2, 30 ml of each slurry composition was placed in a 50 ml small bottle and subjected to ultrasonic vibration for 10 minutes using a tabletop ultrasonic cleaner (product name "US-KS", manufactured by SND Corporation). The appearance of the slurry composition was then visually observed to check for color and the presence or absence of precipitation. Furthermore, the possibility of redispersion was determined based on the presence or absence of precipitation of the La-based composite oxide particles after dispersion. The results are shown in Table 1.

[0105] 2 shows a photograph of the appearance of each of the slurry compositions of Examples 1 and 2, and Fig. 3 shows a photograph of the appearance of the slurry composition of Comparative Example 1. Furthermore, Fig. 4 shows a photograph of the appearance of the slurry composition of Example 15.

[0106] [Precipitation] After applying ultrasonic vibration to each slurry composition as described above, the slurry composition was allowed to stand for 10 minutes, and the presence or absence of precipitation was determined by observing the appearance of each slurry composition.

[0107] [Transmittance of Slurry Composition] The transmittance τ of the slurry composition of Example 2 was determined by the following method. The transmittance τ of the composition of Example 2 was determined by the following method: -a In the formula, a is the absorbance of the solid content in the slurry composition. This absorbance a is calculated by a = a n -a0, where a n represents the absorbance of the slurry composition of Example 2, and a0 represents the absorbance of water alone (blank). n The absorbance a0 was measured using an ultraviolet-visible spectrophotometer under the measurement conditions shown below.

[0108] <Measurement conditions> Measurement equipment: UV-visible spectrophotometer (product number: Evolution 201) manufactured by LMS Corporation Measurement range: 360nm~800nm ​​(visible light range) Scan speed: 1200.00nm / min Data interval: 1 nm Integration time: 0.050 seconds Bandwidth: 1nm Baseline correction: 100%T

[0109] Figure 5 shows the transmittance (%) of the slurry composition of Example 2. The horizontal axis of Figure 5 represents wavelength (nm), and the vertical axis represents transmittance (%). The maximum transmittance (%) was 100%, and the minimum was 97.6%.

[0110] [Fixability] 2 ml of each slurry composition, such as that in Example 1, was dropped onto the surface of a glass substrate using a pipette, and the dispersion medium was allowed to evaporate. In Example 4, the slurry composition was attached to the surface of the substrate and then irradiated with ultraviolet light for 30 seconds. The adhesive side of an adhesive tape was attached to the slurry composition attached to the surface of the substrate, and the adhesive tape was then peeled off to confirm whether the slurry composition peeled off from the surface of the substrate using an SEM. This tape peeling test was performed up to 20 times for each slurry composition. If the slurry composition peeled off after three or fewer tape peeling tests, the result was designated "1." If the slurry composition peeled off after four to ten tape peeling tests, the result was designated "2." If the slurry composition did not peel off even after 11 or more tape peeling tests, the result was designated "3." The results are shown in Table 1.

[0111] [Aggregation after application and drying] 2 ml of each slurry composition such as that of Example 1 was dropped onto the surface of a glass substrate using a pipette, and the dispersion medium was then evaporated. Images were taken using a scanning electron microscope at an acceleration voltage of 5 kV. The magnification was adjusted appropriately depending on the size of the aggregated particles. In the image taken using the scanning electron microscope, particles that were continuous and 50 μm or larger were defined as "aggregated." The results are shown in Table 1. FIG. 6 is an SEM image (magnification: 500) showing the La-Mo-based composite oxide particles (La-based composite oxide particles) of Comparative Example 2 adhered to the surface of the substrate.

[0112] [Table 1]

[0113] As shown in Table 1, each of the slurry compositions of Examples 1 to 9 was redispersible after applying ultrasonic vibrations for 10 minutes. The slurry compositions of Examples 2, 3, and 4 were transparent, the slurry compositions of Examples 1, 5, and 7 were translucent, and the slurry compositions of Examples 6, 8, and 9 were cloudy. Each of the slurry compositions of Examples 1 to 9 was applicable to an object. Furthermore, no precipitation of the La-Mo composite oxide particles was observed in each of the slurry compositions of Examples 1 to 9, even after they were allowed to stand for 10 minutes. Furthermore, for each of the slurry compositions of Examples 1 to 9, after application to an object and evaporation of the dispersion medium, no continuous particles of 50 μm or more were observed, and no aggregation of the La-Mo composite oxide particles was observed.

[0114] On the other hand, in the case of the slurry composition of Comparative Example 1, after applying ultrasonic vibration for 10 minutes, the La-Mo composite oxide particles and the dispersion medium separated into two layers, and re-dispersion was impossible. Therefore, the slurry composition of Comparative Example 1 could not be applied to the target object. This is thought to be due to the fact that the median particle diameter of the La-Mo composite oxide particles of Comparative Example 1 was 2300 nm.

[0115] Furthermore, the slurry composition of Comparative Example 2 was cloudy after 10 minutes of application of ultrasonic vibrations, and redispersion of the La-Mo composite oxide particles was possible. However, after the application of ultrasonic vibrations was stopped and the composition was left to stand for 10 minutes, precipitation of the La-Mo composite oxide particles was observed. Furthermore, as shown in FIG. 5, aggregation of the La-Mo composite oxide particles was observed after application to the object and drying. This is thought to be due to the fact that the concentration of the La-Mo composite oxide particles in the slurry composition of Comparative Example 2 was 20 mass%.

[0116] It was also confirmed that the slurry composition of Example 4, which contained an ultraviolet curable resin, had the best fixability (adhesion) to the object, and that the slurry composition of Example 3, which contained a binder, also had a good degree of fixability (adhesion).

[0117] Furthermore, as shown in Table 1, each of the slurry compositions of Examples 10 to 15 was redispersible after applying ultrasonic vibrations for 10 minutes, similar to Example 1 and the like. The slurry compositions of Examples 10, 11, 12, and 14 were translucent, similar to Example 1 and the like, and the slurry compositions of Examples 13 and 15 were cloudy, similar to Example 9 and the like. Each of the slurry compositions of Examples 10 to 15 was applicable to an object, similar to Example 1 and the like. Furthermore, no precipitation of La-based composite oxide particles (La-Mo-W-based composite oxide particles, La-W-based composite oxide particles) was observed in each of the slurry compositions of Examples 10 to 15, even after being left to stand for 10 minutes. Furthermore, for each of the slurry compositions of Examples 10 to 15, after application to an object and evaporation of the dispersion medium, no continuous particles of 50 μm or more were observed, and no aggregation of the La-based composite oxide particles was observed.

Claims

1. Comprising particles of a composite oxide containing La and at least one element selected from the group consisting of Mo and W, and a dispersion medium; The particles have a median particle size of 150 nm or more and 800 nm or less, The slurry composition has a particle content of 0.1 to 10 mass %.

2. The composite oxide is La ２ Mo ｘ W （２－Ｘ） O ９ 2. The slurry composition according to claim 1, wherein x is 0≦x≦2.

3. The slurry composition according to claim 1 or claim 2, which comprises a binder.

4. The slurry composition according to any one of claims 1 to 3, further comprising a dispersant.

5. The slurry composition according to claim 1 , further comprising an ultraviolet curable resin.

6. A coating agent comprising the slurry composition according to any one of claims 1 to 5.

Images