Slurry composition and coating agent

Abstract

To provide a slurry composition and a coating agent having improved dispersibility of Ce-Mo-based composite oxide particles.SOLUTION: A slurry composition of the present invention comprises Ce-Mo-based composite oxide particles, a dispersion medium, and a dispersant, wherein the median particle diameter D50 (nm) of the Ce-Mo-based composite oxide particles satisfies the following condition: 1040<D50≤2000, and the content of the Ce-Mo-based composite oxide particles is 0.1 mass% or more and 50 mass% or less. Alternatively, a slurry composition of the present invention comprises Ce-Mo-based composite oxide particles and a dispersion medium, wherein the median particle diameter D50 (nm) of the Ce-Mo-based composite oxide particles satisfies the following condition: D50≤1040, and the content of the Ce-Mo-based composite oxide particles is 0.1 mass% or more and 50 mass% or less.SELECTED DRAWING: Figure 1

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, composite oxides containing cerium (Ce) and molybdenum (Mo) and having high antibacterial and antiviral activity have attracted attention as inorganic antibacterial and antiviral agents. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 014631 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, powders with antibacterial and antiviral properties, such as silver powder, have been made into a slurry and used as a coating agent, or mixed into paint to impart antibacterial and antiviral properties.

[0005] However, no such study has been carried out on the ceramic powder of the composite oxide containing cerium and molybdenum. The specific gravity of the composite oxide containing cerium and molybdenum is 5.0 g / cm 3 Since the particle size is large, there are problems such as poor dispersibility.

[0006] An object of the present invention is to provide a slurry composition and a coating agent in which the dispersibility of Ce-Mo based composite oxide particles is improved. [Means for solving the problem]

[0007] As a result of intensive studies to achieve the above object, the present inventors have found that (1) a slurry composition containing Ce-Mo composite oxide particles, a dispersion medium, and a dispersant, wherein the median particle diameter D50 (nm) of the Ce-Mo composite oxide particles satisfies 1040 < D50 ≤ 2000, and the content of the Ce-Mo composite oxide particles is 0.1% by mass or more and 50% by mass or less, and (2) a slurry composition containing Ce-Mo composite oxide particles and a dispersion medium, wherein the median particle diameter D50 (nm) of the Ce-Mo composite oxide particles satisfies D50 ≤ 1040, and the content of the Ce-Mo composite oxide particles is 0.1% by mass or more and 50% by mass or less, improve the dispersibility of the Ce-Mo composite oxide particles, and thus completed the present invention.

[0008] Means for solving the above problems are as follows. That is, <1> A slurry composition containing Ce-Mo composite oxide particles, a dispersion medium, and a dispersant, wherein the median particle diameter D50 (nm) of the Ce-Mo composite oxide particles satisfies 1040 < D50 ≤ 2000, and the content of the Ce-Mo composite oxide particles is 0.1% by mass or more and 50% by mass or less.

[0009] <2> A slurry composition containing Ce-Mo composite oxide particles and a dispersion medium, wherein the median particle diameter D50 (nm) of the Ce-Mo composite oxide particles satisfies D50 ≤ 1040, and the content of the Ce-Mo composite oxide particles is 0.1% by mass or more and 50% by mass or less.

[0010] <3> The slurry composition according to <1> or <2> above, containing a binder.

[0011] <4> The slurry composition according to <1> or <2> above, wherein the dispersion medium contains an aqueous solvent.

[0012] <5> The slurry composition according to <1> or <2> above, wherein the dispersion medium contains a non-aqueous solvent (alcohol-based solvent).

[0013] <6> The slurry composition according to <1> or <2> above, wherein the dispersion medium contains a resin-based solvent.

[0014] <7> A coating agent containing the slurry composition according to any one of <1> to <6> above.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a slurry composition in which the dispersibility of Ce-Mo composite oxide particles is improved, and a coating agent.

Brief Description of the Drawings

[0016] [Figure 1] A diagram showing appearance photographs of the slurry composition of Example 1 (after 0 hours, after 20 hours) [Diagram 2] A diagram showing appearance photographs of the slurry composition of Comparative Example 1 (after 0 hours, after 20 hours)

Modes for Carrying Out the Invention

[0017] <Embodiment 1> The slurry composition of the present embodiment contains Ce-Mo composite oxide particles, a dispersion medium, and a dispersant, and the central particle diameter D50 (nm) of the Ce-Mo composite oxide particles is 1040 < D50 ≤ 2000, and the content of the Ce-Mo composite oxide particles is 0.1% by mass or more and 50% by mass or less, which is a liquid composition.

[0018] In this specification, a composite oxide of cerium (Ce) and molybdenum (Mo) is represented as "Ce-Mo composite oxide", and particles of the Ce-Mo composite oxide (that is, particulate Ce-Mo composite oxide) are represented as "Ce-Mo composite oxide particles". The Ce-Mo composite oxide has excellent antibacterial properties and antiviral properties.

[0019] The median particle diameter D50 (nm) of the Ce-Mo composite oxide particles satisfies 1040 < D50 ≤ 2000. When the median particle diameter is within such a range, the sedimentation rate of the Ce-Mo composite oxide particles in the dispersion medium is sufficiently delayed, thereby improving the dispersibility of the Ce-Mo composite oxide particles and enabling the application of the slurry composition to the object.

[0020] The median particle diameter (nm) of the Ce-Mo composite oxide particles is determined as the particle diameter (D50) at which the cumulative frequency by the laser diffraction method reaches 50%. The specific measurement method of the median particle diameter using a laser diffraction type particle size distribution measuring device will be described later.

[0021] The Ce-Mo composite oxide is not particularly limited as long as it does not impair the object of the present invention. For example, Ce2Mo3O 13 , Ce(MoO4)2, Ce2MoO6, Ce2(MoO4)3, Ce2Mo4O 15 , Ce5(MoO4)8, Ce6(MoO4)8(Mo2O7), Ce8Mo 12 O 49 and the like can be mentioned. These may be used alone or in combination of two or more.

[0022] The Ce-Mo composite oxide particles are produced, for example, through a preparation step, a first firing step, and a pulverization step.

[0023] The preparation step is a step of mixing a cerium compound and a molybdenum compound to prepare a mixed powder.

[0024] The cerium compound is a compound containing cerium (Ce) necessary for producing the Ce-Mo composite oxide. For example, CeO2, cerium nitrate, cerium chloride, cerium sulfate, cerium hydroxide, cerium carbonate, cerium acetate, etc. can be mentioned. As the cerium compound, for example, at least one selected from the group consisting of CeO2, cerium nitrate, cerium chloride, cerium sulfate, cerium hydroxide, cerium carbonate, and cerium acetate may be used. Note that CeO2 is preferable as the cerium compound.

[0025] The molybdenum compound is a compound containing molybdenum (Mo) necessary for producing a Ce-Mo 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. As the molybdenum compound, MoO3 is preferred.

[0026] The mixing ratio of the cerium compound and the molybdenum compound is not particularly limited as long as it does not impair the object of the present invention, and may be adjusted to, for example, a molar ratio of Ce:Mo=2:3, a molar ratio of Ce:Mo=1:2, a molar ratio of Ce:Mo=1:1, a molar ratio of Ce:Mo=2:1, a molar ratio of Ce:Mo=3:4, a molar ratio of Ce:Mo=3:5, or a molar ratio of Ce:Mo=5:8.

[0027] The cerium compound and the molybdenum compound are both powders, and may be mixed together in the powder state, or a solvent such as a lower alcohol (e.g., ethanol) may be added to the powders to perform wet mixing. The cerium compound and the molybdenum compound may be mixed by wet mixing using, for example, alumina balls (alumina boulders). The wet-mixed mixture (wet mixture) is appropriately dried by water bath drying, spray drying, or the like.

[0028] By such a preparation process, a mixed powder of a cerium compound and a molybdenum compound is obtained.

[0029] The first firing step is a step of firing the mixed powder obtained in the preparation step in order to react the cerium compound and the molybdenum compound in the mixed powder. In the first firing step, the mixed powder is fired, for example, at a temperature condition of 400° C. to 700° C. for 0.5 hours or more (preferably 1 hour or more). Note that the first firing step does not need to be performed under a special synthetic air atmosphere, and is performed under a normal atmospheric pressure atmosphere.

[0030] In the first firing step, the cerium compound and the molybdenum compound in the mixed powder react with each other to form CeMoO 13 The Ce-Mo based composite oxide containing the above can be obtained.

[0031] The pulverization step is a step in which the Ce-Mo based composite oxide after the first firing is pulverized using a media stirring pulverizer such as a bead mill or a pot mill so that the central particle diameter of the Ce-Mo based composite oxide falls within a predetermined range. The pulverization conditions, such as the pulverization time, are appropriately set so that the central particle diameter of the Ce-Mo based composite oxide falls within a predetermined range. The pulverization time is, for example, 1 hour to 10 hours.

[0032] In this manner, the Ce-Mo based composite oxide particles having a predetermined median particle size for use in the slurry composition are obtained.

[0033] The obtained Ce-Mo composite oxide particles may be granulated as necessary. For example, a solvent such as ethanol is added to the Ce-Mo composite oxide particles, and wet mixing and grinding is performed 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 Ce-Mo composite oxide particles granulated to a predetermined size.

[0034] In addition, as long as the object of the present invention is not impaired, the Ce-Mo composite oxide particles may be sintered, and then the sintered body obtained by pulverizing the sintered body (pulverized material) may be used as the "Ce-Mo composite oxide particles" to be used in the slurry composition. The sintered body may be obtained, for example, by forming the Ce-Mo composite oxide particles before sintering into a predetermined shape and firing the obtained molded body under a predetermined temperature condition (for example, 900°C or higher). In this specification, the firing step performed to sinter the Ce-Mo composite oxide particles is referred to as the "second firing step". This second firing step is performed in an air atmosphere. The Ce-Mo composite oxide obtained after the second firing step is, as necessary, prepared into particles having a median particle size within a predetermined range by a pulverization step.

[0035] The dispersion medium used in the slurry composition may be a resin-based solvent, water, ethanol, isopropyl alcohol, methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, etc. These may be used alone or in combination of two or more.

[0036] Examples of resin-based solvents include thermosetting resins such as phenol resins, epoxy resins, urea resins, melamine resins, unsaturated polyester resins, polyester resins, low-viscosity epomount resins, epomount resins, polyurethane resins, diallyl phthalate resins, allyl resins, silicone resins, alkyd resins, and furan resins.

[0037] The content of the Ce-Mo composite oxide particles in the slurry composition is 0.1% by mass or more and 50% by mass or less, and the upper limit of the content is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0038] The dispersant is used for the purpose of increasing the dispersibility of Ce-Mo composite oxide particles in a dispersion medium. There are no particular limitations on such dispersants as long as they do not impair the object of the present invention, and examples of such dispersants include water-soluble acrylic acid dispersants, anionic surfactants, cationic surfactants, nonionic surfactants, polyethylene glycol (PEG)-polypropylene glycol (PPG) block polymers, ammonium polyacrylates, polycarboxylic acid copolymers having alkyl chains or polyalkylene glycol (PAG) chains, etc. These may be used alone or in combination of two or more.

[0039] The content of the dispersant is not particularly limited as long as it does not impair the object of the present invention, but for example, it is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and preferably 5 mass% or less, more preferably 3 mass% or less, based on the total mass of the Ce-Mo composite oxide particles in the slurry composition. When the content of the dispersant is within such a range, the dispersibility of the Ce-Mo composite oxide particles in the slurry composition can be improved.

[0040] The slurry composition may contain other components in addition to the above-mentioned Ce-Mo based composite oxide particles, dispersion medium, and dispersant, so long as the object of the present invention is not impaired.

[0041] Examples of other components (compounds) include binders, ultraviolet curing resins, colorants (pigments, dyes), etc. Components other than these may also be used as other components.

[0042] The binder is used for the purpose of improving the adhesion of the Ce-Mo composite oxide particles contained in the slurry composition to the target object. There are no particular limitations on such binder as long as it does not impair the object of the present invention, and examples of such binder include polyvinyl alcohol (PVA) and polyvinyl butyral (PVB). These may be used alone or in combination of two or more kinds.

[0043] The content of the binder is not particularly limited as long as it does not impair the object of the present invention, but is preferably, for example, 0.05% by mass to 5% by mass based on the total mass of the Ce-Mo based composite oxide particles in the slurry composition.

[0044] The slurry composition of the present embodiment can be used as a coating agent by including a curing agent. As the curing agent, any curing agent can be selected as long as it does not impair the object of the present invention, such as a curing agent in which a synthetic resin is dissolved in a volatile solvent, a moisture-curing type curing agent, a two-liquid mixing type curing agent, or an ultraviolet-curing type curing agent. The curing agent is used for the purpose of improving the adhesion of the Ce-Mo-based composite oxide particles contained in the slurry composition to the target object. Examples of ultraviolet-curing resins used in ultraviolet-curing type curing agents include acrylic ultraviolet-curing resins.

[0045] 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.

[0046] The slurry composition (coating agent) of the present embodiment may contain a pigment. The pigment is used for the purpose of coloring a coating film containing Ce-Mo composite oxide particles formed on the surface of an object. The pigment may be water-based (hydrophilic) or oil-based (oleophilic). There is no particular limitation on the pigment, and examples of the pigment include carbon black, synthetic resin, metal powder, and minerals. These may be used alone or in combination of two or more.

[0047] There is no particular limitation on the object to which the slurry composition is applied. Examples of materials constituting the object include glass, ceramics, synthetic resins such as thermoplastic resins and thermosetting resins, rubber (natural rubber, synthetic rubber), genuine leather (natural leather), synthetic leather, metal materials made of metals or alloys, wood, paper, fibers, nonwoven fabrics, silicon (silicon wafers, etc.), carbon materials, minerals, etc.

[0048] The method of applying the slurry composition to the object may be, for example, brushing, roller, blade casting, or dipping. The method of drying the slurry composition after application to the object may be any known method, such as natural drying or heating in a drying oven. In this case, it is preferable to select a method that can suppress aggregation of the Ce-Mo composite oxide particles.

[0049] <Embodiment 2> The slurry composition of the present embodiment is a liquid composition that contains Ce-Mo-based composite oxide particles and a dispersion medium, in which the Ce-Mo-based composite oxide particles have a median particle diameter D50 (nm) of D50≦1040 and the content of the Ce-Mo-based composite oxide particles is 0.1 mass % or more and 50 mass % or less.

[0050] The slurry composition of this embodiment differs from the above-mentioned embodiment 1 in that the range of the median particle diameter D50 (nm) of the Ce-Mo-based composite oxide particles and that a dispersant is not used as an essential component, but otherwise is basically the same as embodiment 1. Therefore, here, the range of the median particle diameter D50 (nm) and the like will be mainly described.

[0051] As described above, the median particle diameter D50 (nm) of the Ce-Mo-based composite oxide particles in this embodiment is D50≦1040. When the median particle diameter is in this range, the settling velocity of the Ce-Mo-based composite oxide particles in the dispersion medium is sufficiently slowed without using a dispersant, improving the dispersibility of the Ce-Mo-based composite oxide particles and making it possible to apply the slurry composition to an object.

[0052] There is no particular restriction on the lower limit of the median particle size as long as it does not impair the object of the present invention, but it is preferably, for example, 100 nm or more.

[0053] The content of the Ce-Mo composite oxide particles in the slurry composition is 0.1% by mass or more and 50% by mass or less, and the upper limit of the content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0054] In the case of the slurry composition of the present embodiment, a dispersant is not an essential component as described above, but may be used as necessary.

[0055] When a dispersant is used, the content of the dispersant is not particularly limited as long as it does not impair the object of the present invention. For example, the content of the dispersant is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, and is preferably 5 mass % or less, more preferably 3 mass % or less, based on the total mass of the Ce-Mo-based composite oxide particles in the slurry composition.

[0056] Furthermore, when a binder is used, the content of the binder is not particularly limited as long as it does not impair the object of the present invention. For example, the binder content is preferably 0.05 mass % or more and 5 mass % or less with respect to the total mass of the Ce-Mo-based composite oxide particles in the slurry composition.

[0057] 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.

[0058] Example 1 CeO2 was prepared as the cerium compound, and MoO3 was prepared as the molybdenum compound. Then, the raw powder of the cerium compound and the raw powder of the molybdenum compound were weighed out so that the molar ratio was 2:3 (Ce:Mo=2:3). The weighed raw powders were mixed with a predetermined amount of ethanol, and the obtained wet mixture was dried to obtain a mixed powder. Next, the mixed powder was fired at a temperature of 475° C. for 1 hour in an air atmosphere to obtain a fired powder consisting of a reaction product of the cerium compound and the molybdenum compound. Then, the obtained fired powder was pulverized in a pot mill for 4.5 hours to obtain Ce-Mo-based composite oxide particles.

[0059] The median particle diameter of the Ce-Mo based composite oxide particles in Example 1 was 1040 nm. The method for measuring the median particle diameter will be described later.

[0060] The Ce-Mo composite oxide particles were mixed with water (dispersion medium) so that the content in the final slurry composition was 1 mass %, and the mixture was irradiated with ultrasonic waves for 10 minutes to obtain the slurry composition of Example 1.

[0061] 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 mass % based on the Ce-Mo-based composite oxide particles).

[0062] 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 added (0.1 mass % (binder) and 1 mass % (dispersant) relative to the Ce-Mo-based composite oxide particles).

[0063] Example 4 A fired powder was prepared in the same manner as in Example 1, and the fired powder was pulverized in a bead mill for 3 hours to obtain Ce-Mo-based composite oxide particles of Example 4. The Ce-Mo-based composite oxide particles of Example 4 had a median particle diameter of 100 nm. The method for measuring the median particle diameter will be described later.

[0064] The Ce-Mo composite oxide particles of Example 4 were mixed with water (dispersion medium) so that the content in the final slurry composition was 1 mass %, and the mixture was irradiated with ultrasonic waves for 10 minutes to obtain the slurry composition of Example 4.

[0065] Example 5 A slurry composition of Example 5 was obtained in the same manner as in Example 4, except that a dispersant was added (1 mass % based on the Ce-Mo based composite oxide particles).

[0066] Example 6 A slurry composition of Example 6 was obtained in the same manner as in Example 4, except that a binder and a dispersant were added (0.1 mass % (binder) and 1 mass % (dispersant) relative to the Ce-Mo-based composite oxide particles).

[0067] Example 7 A fired powder was prepared in the same manner as in Example 1, and the fired powder was pulverized in a pot mill for 3 hours to obtain Ce-Mo-based composite oxide particles of Example 7. The median particle size of the Ce-Mo-based composite oxide particles of Example 7 was 1640 nm.

[0068] The Ce-Mo composite oxide particles of Example 7 were mixed with water (dispersion medium) so that the content in the final slurry composition was 1 mass %, and a dispersant was also mixed (1 mass % relative to the Ce-Mo composite oxide particles), and the mixture was irradiated with ultrasonic waves for 10 minutes to obtain the slurry composition of Example 7.

[0069] Example 8 A slurry composition of Example 8 was obtained in the same manner as in Example 7, except that a binder was added (0.1% by mass relative to the Ce-Mo based composite oxide particles).

[0070] Example 9 A slurry composition of Example 9 was obtained in the same manner as in Example 2, except that the dispersion medium was changed to ethanol.

[0071] Example 10 A slurry composition of Example 10 was obtained in the same manner as in Example 1, except that the dispersion medium was changed to an epoxy resin (Epomount resin).

[0072] Example 11 A fired powder was prepared in the same manner as in Example 1, and the fired powder was pulverized in a pot mill for 2 hours, and the Ce-Mo composite oxide particles were mixed with water (dispersion medium) so that the content in the final slurry composition was 0.1 mass %, and a dispersant was also mixed (0.1 mass % relative to the Ce-Mo composite oxide particles), to obtain a slurry composition of Example 11. The central particle diameter of the Ce-Mo composite oxide particles of Example 11 was 2000 nm.

[0073] Example 12 The slurry composition of Example 12 was obtained in the same manner as in Example 1, except that the Ce-Mo composite oxide particles were mixed with water (dispersion medium) so that the content in the final slurry composition was 20 mass %, and a dispersant was also mixed (1 mass % relative to the Ce-Mo composite oxide particles).

[0074] Example 13 CeO2 was prepared as the cerium compound, and MoO3 was prepared as the molybdenum compound. Then, the raw powder of the cerium compound and the raw powder of the molybdenum compound were weighed out so that the molar ratio was 5:8 (Ce:Mo=5:8). The weighed raw powders were mixed with a predetermined amount of ethanol, and the resulting wet mixture was dried to obtain a mixed powder. Next, the mixed powder was fired in an air atmosphere at a temperature condition of 700°C for 1 hour to obtain a fired powder consisting of a reaction product of the cerium compound and the molybdenum compound. The fired powder was then pulverized in a pot mill for 4.5 hours to obtain Ce-Mo-based composite oxide particles.

[0075] The median particle diameter of the Ce-Mo based composite oxide particles of Example 13 was 2000 nm. The method for measuring the median particle diameter will be described later.

[0076] The Ce-Mo composite oxide particles were mixed with water (dispersion medium) so that the content in the final slurry composition was 1 mass %, and a dispersant was also mixed (1 mass % relative to the Ce-Mo composite oxide particles), and the mixture was irradiated with ultrasonic waves for 10 minutes to obtain the slurry composition of Example 13.

[0077] Example 14 The slurry composition of Example 14 was obtained in the same manner as in Example 1, except that the Ce-Mo composite oxide particles were mixed with water (dispersion medium) so that the content in the final slurry composition was 50 mass %, and a dispersant was also mixed (1 mass % relative to the Ce-Mo composite oxide particles).

[0078] Comparative Example 1 A mixed powder was synthesized in the same manner as in Example 13, and then fired at 700° C. to obtain Ce-Mo-based composite oxide particles of Comparative Example 1. The Ce-Mo-based composite oxide particles of Comparative Example 1 had a median particle diameter of 5500 nm. The method for measuring the median particle diameter will be described later.

[0079] The Ce-Mo composite oxide particles of Comparative Example 1 were mixed with water (dispersion medium) so that the content in the final slurry composition was 1 mass %, and the mixture was irradiated with ultrasonic waves for 10 minutes to obtain the slurry composition of Comparative Example 1.

[0080] Comparative Example 2 A slurry composition of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that a dispersant was added (1% by mass relative to the Ce-Mo-based composite oxide particles).

[0081] Comparative Example 3 A slurry composition of Comparative Example 3 was obtained in the same manner as in Comparative Example 1, except that a binder and a dispersant were added (0.1 mass % (binder) and 1 mass % (dispersant) relative to the Ce-Mo-based composite oxide particles).

[0082] Comparative Example 4 A slurry composition of Comparative Example 4 was obtained in the same manner as in Example 7, except that no dispersant was added to the water (dispersion medium).

[0083] [Measurement of median particle size (D50) by laser diffraction method] The median particle diameter (D50) of the Ce-Mo based composite oxide particles of Examples 1 to 14 and Comparative Examples 1 to 4 was measured using a laser diffraction particle size distribution device (model "LA-950", manufactured by Horiba, Ltd.) The measurement conditions were as follows.

[0084] <Measurement conditions> A sodium hexametaphosphate aqueous solution with a concentration of 2% by mass was used as solution A. Ce-Mo composite oxide particles (measurement subject) were added to a sodium hexametaphosphate aqueous solution with a concentration of 2% by mass, and the mixture was stirred with a homogenizer to uniformly disperse the Ce-Mo composite oxide particles, which was used as solution B. 0.5 mL of solution B was dropped into solution A to prepare solution C in which the concentration of the Ce-Mo composite oxide particles was 1% by mass or less and the Ce-Mo composite oxide particles were monodispersed. Then, using this solution C, a particle diameter (D50) at which the cumulative frequency was 50% was determined as the median particle diameter by a laser diffraction particle size distribution device. The measurement results of the median particle diameter (D50) in each example are shown in Table 1.

[0085] [Evaluation of Dispersibility] The dispersibility of the Ce-Mo composite oxide particles was evaluated for each of the slurry compositions of Examples 1 to 14 and Comparative Examples 1 to 4, based on the following criteria, while visually observing the composition at the time of preparation (0 hours) and 20 hours after preparation. The results are shown in Table 1.

[0086] <Judgment criteria> No precipitation. "◎" Although some precipitation was observed, the slurry composition did not separate into solid and liquid. Precipitation has occurred and the slurry composition has separated into solid and liquid.

[0087] [Table 1]

[0088] As shown in Table 1, it was confirmed that the slurry compositions of Examples 1 to 14 suppressed the precipitation of Ce-Mo composite oxide particles and had excellent dispersibility (maintained dispersibility) even after 20 hours had passed since preparation. Fig. 1 shows external photographs of the slurry composition of Example 1 (after 0 hours and 20 hours).

[0089] In all of Comparative Examples 1 to 3, the median particle diameter of the Ce-Mo composite oxide particles was too large. In the cases of Comparative Examples 1 to 3, no particle precipitation was observed when the slurry composition was prepared (0 hours later). However, after 20 hours, precipitation occurred in all of Comparative Examples 1 to 3, resulting in solid-liquid separation. In other words, in the slurry composition after 20 hours, a layer of precipitated Ce-Mo composite oxide particles was formed on the bottom, and a transparent solvent layer was formed on the top of it.

[0090] Comparative Example 4 is a case where the median particle diameter of the Ce-Mo based composite oxide particles is 1640 nm and no dispersant is included. In the case of Comparative Example 4, no precipitation of particles was observed when the slurry composition was prepared (0 hours later). However, after 20 hours, precipitation occurred and solid-liquid separation occurred. Therefore, it was confirmed that in the case of such a median particle diameter, precipitation of the Ce-Mo based composite oxide particles cannot be suppressed unless a dispersant is included.

Claims

1. The composition includes Ce—Mo-based composite oxide particles, a dispersion medium, and a dispersant, The Ce—Mo-based composite oxide particles have a median particle diameter D50 (nm) of 1040<D50≦2000, The content of the Ce-Mo based composite oxide particles in the slurry composition is 0.1% by mass or more and 50% by mass or less.

2. The composition includes Ce—Mo-based composite oxide particles and a dispersion medium, The Ce—Mo-based composite oxide particles have a median particle diameter D50 (nm) of D50≦1040; The content of the Ce-Mo based composite oxide particles in the slurry composition is 0.1% by mass or more and 50% by mass or less.

3. The slurry composition of claim 1 or claim 2, further comprising a binder.

4. The slurry composition according to claim 1 or 2, wherein the dispersion medium comprises an aqueous solvent.

5. The slurry composition according to claim 1 or 2, wherein the dispersion medium comprises a non-aqueous solvent (an alcohol-based solvent).

6. The slurry composition according to claim 1 or 2, wherein the dispersion medium comprises a resin-based solvent.

7. A coating agent comprising the slurry composition according to claim 1 or 2.

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