Coated zirconium nitride particles and black ultraviolet-curable organic composition

Abstract

To provide a zirconium nitride particle that is less prone to a deterioration of visible light blocking properties even when stored in the air for a long time.SOLUTION: A coated zirconium nitride particle includes a zirconium nitride particle and an oxide layer covering at least a part of the surface of the zirconium nitride particle, with the thickness of the oxide layer being in a range from 10 nm to 40 nm inclusive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to coated zirconium nitride particles and black ultraviolet-curable organic compositions. [Background technology]

[0002] Insulating black pigments are used, for example, as materials for black patterns constituting the black matrix of color filters for displays and the light-shielding material in CMOS camera modules. A known method for forming a black pattern is photolithography using a black UV-curable organic composition containing a UV-curable resin and an insulating black pigment. In the photolithography method, a photoresist film is formed by applying a black UV-curable organic composition to a substrate. The photoresist film is then exposed to UV light in a pattern to create a pattern consisting of exposed and cured portions and unexposed and uncured portions. The uncured portions are then removed to form the black pattern. The insulating black pigment used to form the black pattern by this photolithography method needs to transmit the UV light that cures the photoresist film, i.e., it needs to be UV-transparent.

[0003] Zirconium nitride particles are known as an insulating black pigment that is ultraviolet-transmitting (Patent Document 1). Patent Document 1 describes a method for producing zirconium nitride particles, in which a mixture containing zirconium dioxide powder or silica-coated zirconium dioxide powder, metal magnesium powder, and magnesium nitride powder is fired at a temperature of 650 to 900°C in an atmosphere of nitrogen gas alone, a mixed gas of nitrogen gas and hydrogen gas, or a mixed gas of nitrogen gas and ammonia gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-222559 Summary of the Invention [Problem to be solved by the invention]

[0005] Zirconium nitride particles used as an insulating black pigment for a black ultraviolet-curable organic composition desirably have high storage stability. However, if the zirconium nitride particles are stored in the atmosphere for a long period of time, the visible light-shielding ability of the zirconium nitride particles may decrease.

[0006] The present invention has been made in view of the above circumstances, and aims to provide zirconium nitride particles that do not lose their visible light blocking ability even when stored in the atmosphere for a long period of time. Another aim of the present invention is to provide a black ultraviolet-curable organic composition that has high sensitivity to ultraviolet light and high visible light blocking ability even when stored in the atmosphere for a long period of time. [Means for solving the problem]

[0007] In order to solve the above problems, the coated zirconium nitride particles of the present invention comprise zirconium nitride particles and an oxide layer that coats at least a portion of the surface of the zirconium nitride particles, the oxide layer is a region containing zirconium oxide and zirconium oxynitride, with a zirconium content of 5 atm% or more and an atomic concentration ratio (O / N ratio) of oxygen (O) to nitrogen (N) greater than 1.0; The thickness of the oxide layer is in the range of 10 nm to 40 nm.

[0008] In the coated zirconium nitride particles having the above configuration, at least a portion of the surface of the zirconium nitride particles is coated with an oxide layer. Oxides are more stable against moisture than nitrides. Therefore, the coated zirconium nitride particles having the above configuration are less likely to come into contact with moisture in the atmosphere. Furthermore, since the thickness of the oxide layer is within the range of 10 nm to 40 nm, moisture is less likely to penetrate the zirconium nitride particles, and deterioration of the zirconium nitride particles due to moisture is less likely to occur. Therefore, the coated zirconium nitride particles having the above configuration maintain high ultraviolet transmittance and visible light blocking properties even when stored in the atmosphere for a long period of time.

[0009] The coated zirconium nitride particles of the present invention may have a ratio of the transmittance of light with a wavelength of 365 nm to the transmittance of light with a wavelength of 600 nm measured by the following method of 3.0 or more. (Measurement method) The coated zirconium nitride particles are left to stand for 72 hours in an environment with a temperature of 65°C and a relative humidity of 90%RH. After standing, the coated zirconium nitride particles are dispersed in propylene glycol monomethyl ether acetate (PGMEA) to prepare a dispersion with a concentration of 50 ppm by mass. The ratio of the transmittance of light with a wavelength of 365 nm to the transmittance of light with a wavelength of 600 nm for the prepared dispersion is measured.

[0010] In this case, the zirconium nitride particles are coated with an oxide layer such that the ratio of the transmittance of light with a wavelength of 365 nm to the transmittance of light with a wavelength of 600 nm measured by the above method is 3.0 or more, making the particles less susceptible to deterioration by moisture. Therefore, the coated zirconium nitride particles maintain high levels of ultraviolet transmittance and visible light blocking properties even when stored in the atmosphere for long periods of time.

[0011] The black ultraviolet-curable organic composition of the present invention is a black ultraviolet-curable organic composition comprising an ultraviolet-curable organic material and a black pigment dispersed in the ultraviolet-curable organic material, wherein the black pigment is the coated zirconium nitride particles described above. The coated zirconium nitride particles used in the black ultraviolet-curable organic composition having the above-described configuration are resistant to deterioration of the zirconium nitride particles due to moisture, and therefore, even when stored in the atmosphere for a long period of time, the ultraviolet transmittance and visible light blocking ability are resistant to deterioration. Therefore, the black ultraviolet-curable organic composition having the above-described configuration has high sensitivity to ultraviolet light and high visible light blocking ability even when stored in the atmosphere for a long period of time.

[0012] Here, in the black ultraviolet-curable organic composition of the present invention, the ultraviolet-curable organic material may be at least one organic material selected from the group consisting of an acrylic monomer, an acrylic oligomer, an epoxy monomer, and an epoxy oligomer. In this case, since the acrylic monomer, acrylic oligomer, epoxy monomer, and epoxy oligomer have high reactivity to ultraviolet light, the sensitivity of the black ultraviolet-curable organic composition to ultraviolet light becomes higher. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide zirconium nitride particles that are resistant to deterioration in their visible light blocking ability even when stored in the atmosphere for a long period of time, and it is also possible to provide a black ultraviolet-curable organic composition that has high sensitivity to ultraviolet light and high visible light blocking ability even when stored in the atmosphere for a long period of time. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of a coated zirconium nitride particle according to one embodiment of the present invention. [Figure 2] 1 shows a STEM photograph and an element distribution image of coated zirconium nitride particles obtained in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, coated zirconium nitride particles and a black ultraviolet-curable organic composition according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] (Coated zirconium nitride particles) Fig. 1 is a cross-sectional view of a coated zirconium nitride particle according to one embodiment of the present invention. As shown in Fig. 1, the coated zirconium nitride particle 10 of this embodiment has a zirconium nitride particle 11 and an oxide layer 12 that coats at least a portion of the surface of the zirconium nitride particle 11.

[0017] The average primary particle diameter of the coated zirconium nitride particles 10 may be in the range of 30 nm to 270 nm. The average primary particle diameter of the coated zirconium nitride particles 10 is more preferably in the range of 40 nm to 250 nm, and particularly preferably in the range of 40 nm to 150 nm. The average primary particle diameter of the coated zirconium nitride particles 10 is the average Feret diameter measured by observing 100 particles with a STEM (scanning transmission electron microscope). Here, the Feret diameter of the coated zirconium nitride particles was measured as follows. First, 0.5 parts by mass of coated zirconium nitride particles and 0.1 parts by mass of an amine-based dispersant were added to 99.4 parts by mass of toluene and mixed to obtain a mixture. Next, this mixture was dispersed in a bead mill using 0.5 mm diameter zirconia beads to obtain a dispersion of coated zirconium nitride particles. Next, this dispersion was dropped onto a copper mesh and dried to obtain a sample for STEM observation. The obtained sample is observed by STEM to measure the Feret diameter.

[0018] The coated zirconium nitride particles 10 contain zirconium, nitrogen, and oxygen as main component elements. The coated zirconium nitride particles 10 may contain magnesium, chlorine, and hafnium as elements other than nitrogen, zirconium, and oxygen. The magnesium content may be in the range of 0.1% by mass to 5.0% by mass. The chlorine content may be in the range of 1 ppm by mass to 5000 ppm by mass. The hafnium content may be in the range of 0.1% by mass to 5.0% by mass.

[0019] The zirconium nitride particles 11 have a relatively high content of zirconium and nitrogen compared to the oxide layer 12. The zirconium nitride particles 11 contain, for example, 15 atm% or more each of zirconium and nitrogen, and the atomic concentration ratio of oxygen (O) to nitrogen (N) (O / N ratio) is 1.0 or less.

[0020] The oxide layer 12 has a relatively high oxygen content compared to the zirconium nitride particles 11. The oxide layer 12 has, for example, an O / N ratio greater than 1.0. The oxide layer 12 may contain zirconium oxide (ZrO, ZrO2, Zr2O3, etc.) or zirconium oxynitride (ZrON). The thickness of the oxide layer 12 is in the range of 10 nm to 40 nm. The thickness of the oxide layer 12 can be determined by observing the particle shape using a scanning transmission microscope (STEM) and elemental analysis using an energy dispersive X-ray spectroscope (EDS). Specifically, based on the particle shape obtained by STEM photography and elemental analysis by EDS along an arbitrary line drawn from the center of the particle toward the periphery, a region where zirconium and nitrogen are detected at 15 atm% or more each and the O / N ratio is 1.0 or less is defined as zirconium nitride particle 11, and a region where zirconium is detected at 5 atm% or more and the O / N ratio is greater than 1.0 is defined as oxide layer 12. The thickness of oxide layer 12 is measured at 10 arbitrary locations on one particle. The thickness of oxide layer 12 is measured for 10 particles, and the average of the thicknesses is defined as the thickness of oxide layer 12. The ratio of the doubled thickness of oxide layer 12 to the average primary particle diameter of coated zirconium nitride particles 10 (double oxide layer thickness / average primary particle diameter) may be within a range of 0.3 to 0.7. This double oxide layer thickness / average primary particle diameter is an index indicating the proportion of oxide layer 12 in coated zirconium nitride particles 10.

[0021] The coated zirconium nitride particles 10 have a transmittance (T 600nm ) for the transmittance of light with a wavelength of 365 nm (T 365nm ) ratio (T 365nm / T 600nm ) may be 3.0 or more. 365nm / T 600nm may be 8.0 or less.

[0022] (Measurement method) The coated zirconium nitride particles are left to stand for 72 hours in an environment with a temperature of 65°C and a relative humidity of 90%. After standing, the coated zirconium nitride particles are dispersed in PGMEA to prepare a dispersion with a concentration of 50 ppm by mass. The prepared dispersion is placed in a quartz cell with an optical path length of 10 mm, and a transmittance spectrum is obtained using a spectrophotometer. The ratio of the transmittance of light with a wavelength of 365 nm to the transmittance of light with a wavelength of 600 nm is measured in the obtained transmittance spectrum.

[0023] The transmittance of light with a wavelength of 600 nm obtained by the above measurement method (T 600nm ) is an index of the transmittance of visible light. 600nm The lower the better. 600nm is preferably 10% or less, and more preferably 5% or less. 600nm The transmittance (T 365nm ) is an index of ultraviolet light transmittance. 365nm Higher is better. T 365nm may be, for example, 10% or more. 365nm may be 50% or less.

[0024] Before being left to stand in an environment at a temperature of 65°C and a relative humidity of 90%, the coated zirconium nitride particles had a transmittance of light with a wavelength of 600 nm (T 600nm ) for the transmittance of light with a wavelength of 365 nm (T 365nm ) ratio (T 365nm / T 600nm ) may be 2.0 or greater.

[0025] The coated zirconium nitride particles 10 of this embodiment can be produced by heating the zirconium nitride particles 11 in the atmosphere at a temperature of, for example, 100° C. or higher and 300° C. or lower. By heating the zirconium nitride particles 11 in the atmosphere at this temperature, the zirconium nitride on the surfaces of the zirconium nitride particles 11 is oxidized to produce zirconium oxide or zirconium oxynitride, and an oxide layer 12 is formed.

[0026] The method for producing the zirconium nitride particles 11 is not particularly limited. For example, they can be produced by firing a raw material mixture containing zirconium dioxide powder, metallic magnesium powder, and magnesium nitride powder in a heating furnace under a nitrogen-containing gas atmosphere. An electric furnace can be used as the heating furnace. As the zirconium dioxide powder, silica-coated zirconium dioxide powder can also be used. The raw material mixture may have a metallic magnesium powder content of 2.0 moles to 6.0 moles and a magnesium nitride powder content of 0.3 moles to 3.0 moles, based on 1 mole of zirconium dioxide powder. As the nitrogen-containing gas, for example, nitrogen gas alone, a mixed gas of nitrogen gas and hydrogen gas, or a mixed gas of nitrogen gas and ammonia gas can be used. The firing temperature is, for example, 650°C to 900°C. After firing, the mixture may be allowed to cool to room temperature. During this cooling, when the temperature inside the heating furnace is in the range of 100°C or higher and 300°C or lower, the inside of the heating furnace may be opened to the atmosphere to oxidize the surfaces of the zirconium nitride particles 11, thereby forming an oxide layer 12.

[0027] In the coated zirconium nitride particles 10 of this embodiment configured as described above, at least a portion of the surface of the zirconium nitride particles 11 is coated with an oxide layer 12. Oxides are more stable against moisture than nitrides. Therefore, the coated zirconium nitride particles 10 of this embodiment make the zirconium nitride particles 11 less likely to come into contact with moisture. Furthermore, since the thickness of the oxide layer 12 is in the range of 10 nm to 40 nm, moisture is less likely to penetrate the zirconium nitride particles, and deterioration of the zirconium nitride particles due to moisture is less likely to occur. Therefore, the coated zirconium nitride particles 10 of this embodiment maintain high ultraviolet transmittance and visible light blocking properties even when stored in the atmosphere for a long period of time.

[0028] In addition, in the coated zirconium nitride particles 10 of this embodiment, the transmittance of light with a wavelength of 600 nm measured by the above method (T 600nm ) for the transmittance of light with a wavelength of 365 nm (T 365nm) ratio (T 365nm / T 600nm When the zirconium nitride particles 11 are coated with the oxide layer 12 so that the coefficient of thermal expansion (Tc) is 3.0 or more, the zirconium nitride particles 11 are less likely to be altered by moisture. Therefore, the coated zirconium nitride particles maintain high levels of ultraviolet transmittance and visible light blocking properties even when stored in the atmosphere for a long period of time.

[0029] (Black UV curable organic composition) The black ultraviolet-curable organic composition is a composition containing an ultraviolet-curable organic material and a black pigment dispersed in the ultraviolet-curable organic material, the coated zirconium nitride particles being used as the black pigment.

[0030] The ultraviolet-curable organic material may be a monomer or oligomer that polymerizes upon irradiation with ultraviolet light to form a polymer. Examples of the ultraviolet-curable organic material include acrylic monomers, acrylic oligomers, epoxy monomers, and epoxy oligomers. These organic materials may be used alone or in combination of two or more.

[0031] The acrylic monomer is a monomer having a (meth)acryloyl group. The (meth)acryloyl group includes an acryloyl group and a methacryloyl group. The acrylic monomer may be a monofunctional acrylic monomer having one (meth)acryl group in one molecule, or a polyfunctional acrylic monomer having two or more (meth)acryl groups in one molecule. Examples of monofunctional (meth)acrylic monomers include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isoamyl acrylate, tetrahydrofurfuryl (meth)acrylate, and isobornyl (meth)acrylate. Examples of difunctional (meth)acrylic monomers include 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, neopentyl triethylene glycol di(meth)acrylate, etc. Examples of polyfunctional (meth)acrylic monomers include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.

[0032] Acrylic oligomers are low-molecular-weight polymers formed by polymerization of acrylic monomers, and examples thereof include acrylic acrylate, urethane acrylate, epoxy acrylate, and polyester acrylate. The molecular weight of the acrylic oligomer may be, for example, within the range of 1,000 to 10,000 in number average molecular weight. These (meth)acrylate monomers and oligomers can be used alone or in combination of two or more. Furthermore, the (meth)acrylic monomers and oligomers are not limited to those described above, and commonly available (meth)acrylic monomers and oligomers can be used.

[0033] The epoxy monomer has an epoxy group. The epoxy monomer may be a monofunctional epoxy monomer having one epoxy group in one molecule, or a multifunctional epoxy monomer having two or more epoxy groups in one molecule. Examples of the epoxy monomer include glycidyl ether and alicyclic epoxy.

[0034] Epoxy oligomers are low-molecular-weight polymers formed by polymerization of epoxy monomers. The number-average molecular weight of the epoxy oligomers may be, for example, in the range of 1,000 to 10,000.

[0035] The black ultraviolet-curable organic composition may contain other ultraviolet-curable organic materials. Examples of other ultraviolet-curable organic materials that can be used include styrene-based monomers, vinyl-based monomers, and cationically curable monomers. Examples of styrene-based monomers include styrene, vinyl toluene, and divinyl benzene. Examples of vinyl-based monomers include vinyl chloride and vinyl acetate. Examples of cationically curable monomers include oxetane.

[0036] The black UV-curable organic composition may contain a plasticizer. Examples of plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, aliphatic-basic ester plasticizers, aliphatic dibasic acid ester plasticizers, dihydric alcohol ester plasticizers, and oxyacid ester plasticizers. Examples of phosphate ester plasticizers include tributyl phosphate and 2-ethylhexyl phosphate. Examples of phthalate ester plasticizers include dimethyl phthalate and dibutyl phthalate. Examples of aliphatic-basic ester plasticizers include butyl oleate and glycerin monooleate. Examples of aliphatic dibasic acid ester plasticizers include dibutyl adipate and di-2-ethylhexyl sebacate. Examples of dihydric alcohol ester plasticizers include diethylene glycol dibenzoate and triethylene glycol di-2-ethyl butyrate. Examples of the oxyacid ester plasticizer include methyl acetylricinoleate and tributyl acetylcitrate.

[0037] The black ultraviolet-curable organic composition may contain a photopolymerization initiator. The photopolymerization initiator is preferably a compound that can absorb ultraviolet light, specifically light with a wavelength of 100 to 400 nm, and initiate a polymerization reaction. The photopolymerization initiator may be, for example, a radical generator or a photoacid generator. Examples of photopolymerization initiators that can be used include acetophenone-based compounds, benzophenone-based compounds, benzoin ether compounds, triazine compounds, phosphine oxide-based compounds, sulfonium-based compounds, and organic peroxides. Examples of acetophenone-based compounds include acetophenone, dimethylacetophenone, and 2-hydroxy-2-methylpropiophenone. Examples of benzophenone-based compounds include benzophenone and 2-chlorobenzophenone. Examples of phosphine oxide-based compounds include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. Examples of sulfonium compounds include bis(4-tert-butylphenyl)iodonium hexafluorophosphate, triphenylsulfonium tetrafluoroborate, tri-p-tolylsulfonium trifluoromethanesulfonate, etc. Examples of organic peroxides include benzoyl peroxide and cumene peroxide. The content of the photopolymerization initiator in the black ultraviolet-curable organic composition is preferably in the range of 0.5 parts by mass to 15 parts by mass relative to 100 parts by mass of the ultraviolet-curable organic material.

[0038] The content of the ultraviolet-curable organic material in the black ultraviolet-curable organic composition is preferably in the range of 50% by mass to 90% by mass, based on the solid content of the black ultraviolet-curable organic composition. By having the content of the ultraviolet-curable organic material in this range, the shielding properties of the resulting black pattern tend to be improved. The content of the ultraviolet-curable resin is more preferably in the range of 55% by mass to 85% by mass, and particularly preferably in the range of 60% by mass to 80% by mass. The content of the coated zirconium nitride particles in the black ultraviolet-curable organic composition is preferably in the range of 0.1% by mass to 50% by mass, based on the solid content of the black ultraviolet-curable organic composition. By having the content of the coated zirconium nitride particles in this range, it is possible to improve the balance between the shielding properties of visible light and the transmittance of ultraviolet light. The content of the coated zirconium nitride particles is more preferably in the range of 5% by mass to 45% by mass, and particularly preferably in the range of 20% by mass to 40% by mass.

[0039] The black ultraviolet-curable organic composition may contain a solvent. Examples of the solvent include glycol ethers such as ethyl carbitol, ethyl carbitol acetate, butyl carbitol acetate (BCA), butyl carbitol, methyl cellosolve, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, and triethylene glycol monoethyl ether; α-terpineol, methyl ethyl ketone (MEK), ethyl acetate, butyl acetate, n-propanol, isopropanol, methanol, ethanol, toluene, and water. The content of the solvent is preferably in the range of 0% by mass to 60% by mass relative to the black ultraviolet-curable organic composition. By containing the solvent within this range, the coatability of the black ultraviolet-curable organic composition is improved, and the thickness of the photoresist film formed on the substrate tends to be uniform. The content of the solvent is more preferably in the range of 5% by mass to 50% by mass, and particularly preferably in the range of 10% by mass to 40% by mass.

[0040] The coated zirconium nitride particles 10 used in the black ultraviolet-curable organic composition of this embodiment configured as described above are resistant to moisture-induced deterioration of the zirconium nitride particles 11, and therefore have high ultraviolet transmittance and high visible light blocking properties even when stored in the atmosphere for a long period of time. Therefore, the black ultraviolet-curable organic composition of this embodiment has high sensitivity to ultraviolet light and high visible light blocking properties even when stored in the atmosphere for a long period of time.

[0041] In the black ultraviolet-curable organic composition of the present embodiment, when the ultraviolet-curable organic material is at least one organic material selected from the group consisting of an acrylic monomer, an acrylic oligomer, an epoxy monomer, and an epoxy oligomer, these organic materials have high reactivity to ultraviolet light, and therefore the sensitivity of the black ultraviolet-curable organic composition to ultraviolet light becomes higher.

[0042] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of ​​the invention. [Example]

[0043] [Example 1 of the present invention] 9.5 g of zirconium oxide (ZrO) powder, 5.83 g of Mg powder, and 3.39 g of MgO powder, each with an average primary particle size of 53 nm, were weighed and mixed under a nitrogen gas atmosphere to obtain a raw material mixture. The average primary particle size of zirconium oxide was measured in the same manner as the average primary particle size of coated zirconium nitride particles described below. The resulting raw material mixture was placed in a SUS304 crucible and placed in an electric furnace. Next, while supplying nitrogen gas into the electric furnace, the mixture was heated at a furnace temperature of 700°C for 1 hour to reduce and nitride the raw material mixture, producing zirconium nitride particles. The electric furnace was then allowed to cool, and when the furnace temperature reached 150°C, the nitrogen gas supply was stopped, the electric furnace door was opened, and the electric furnace was opened to the atmosphere to produce coated zirconium nitride particles. The electric furnace was left open to the atmosphere until the furnace temperature reached approximately room temperature (30°C), after which the coated zirconium nitride particles were recovered from the electric furnace. The recovered coated zirconium nitride particles were dispersed in 300 g of a 5% aqueous hydrochloric acid solution to dissolve and remove impurities. The hydrochloric acid solution was then neutralized with an aqueous ammonia solution, and the supernatant was removed by decantation. Water was then added several times to obtain a coated zirconium nitride particle slurry. The obtained coated zirconium nitride particle slurry was filtered, and the recovered coated zirconium nitride particles were washed with pure water and then dried to obtain a coated zirconium nitride (ZrN) powder. The obtained coated zirconium nitride powder was stored in a sealed container at a temperature of 25°C and a relative humidity of 20% or less.

[0044] The average primary particle size, oxide layer thickness, and optical properties before and after storage of the obtained coated zirconium nitride particles were measured as follows. The results are shown in Table 1 below.

[0045] (Average primary particle size) 0.5 parts by mass of coated zirconium nitride particles and 0.1 parts by mass of an amine-based dispersant were added to 99.4 parts by mass of toluene and mixed to obtain a mixed solution. The resulting mixed solution was then dispersed and crushed in a bead mill using zirconia beads with a diameter of 0.5 mm to obtain a toluene dispersion of coated zirconium nitride particles. This dispersion was then dropped onto a copper mesh and dried to obtain a sample for STEM observation. The obtained sample was observed using a STEM (manufactured by Thermo Fisher Scientific, Titan G2 ChemiSTEM) at an accelerating voltage of 200 kV, and the Feret diameters of 100 particles were measured and the average was calculated.

[0046] (oxide layer thickness) The particle shape of the obtained coated zirconium nitride particles was observed using STEM and elemental analysis was performed using EDS (Velox, manufactured by Thermo Fisher Scientific). The results are shown in Figure 2. Figure 2(a) is a STEM photograph, Figure 2(b) is an elemental distribution image of zirconium (Zr), Figure 2(c) is an elemental distribution image of nitrogen (N), and Figure 2(d) is an elemental distribution image of oxygen (O). The results in Figure 2 show that oxygen is distributed in a layered form on the surface of the coated zirconium nitride particles. This result confirmed that the coated zirconium nitride particles are particles with an oxide layer formed on the surface of zirconium nitride particles. The thickness of the oxide layer was measured at 10 random locations on one coated zirconium nitride particle. The thickness of this oxide layer 12 was measured for 10 particles, and the average of the thicknesses was taken as the oxide layer thickness. Furthermore, the ratio of double the thickness of the oxide layer to the average primary particle diameter of the coated zirconium nitride particles (double the thickness of the oxide layer / average primary particle diameter) was calculated.

[0047] (Optical properties before storage) 10 parts by mass of the obtained coated zirconium nitride particles, 1 part by mass of an amine-based dispersant, and 29 parts by mass of PGMEA were mixed, and the resulting mixture was dispersed in a bead mill. PGMEA was added to the mixture after the dispersion treatment, and the mixture was stirred and mixed to dilute the dispersion, thereby preparing a dispersion with a concentration of 50 ppm by mass. The obtained dispersion was poured into a quartz cell with an optical path length of 10 mm, and the light transmittance was measured using a spectrophotometer (UH-4150, manufactured by Hitachi High-Tech Fielding Corporation) in the wavelength range of 240 nm to 1300 nm to obtain a spectral curve. From the obtained spectral curve, the transmittance of light at a wavelength of 365 nm (T 365nm ) and the transmittance of light with a wavelength of 600 nm (T 600nm ) and the ratio of the transmittance of light with a wavelength of 365 nm to the transmittance of light with a wavelength of 600 nm (T 365nm / T 600nm ) was calculated. As a result, T 365nm is 21.2%, T 600nm is 5.0%, and T 365nm / T 600nm was 4.2.

[0048] (Optical properties after storage) 10 g of the obtained coated zirconium nitride particles were placed in a petri dish, placed in a thermo-hygrostat, and stored at a temperature of 65°C and a relative humidity of 90%RH for 72 hours. Using the stored coated zirconium nitride particles, a dispersion with a concentration of 50 ppm by mass was prepared in the same manner as above, and a spectroscopic curve was obtained. 365nm and T 600nm Read and T 365nm / T 600nm As a result, T 365nm is 23.2%, T 600nm is 5.8%, and T 365nm / T 600nm was 4.0.

[0049] [Invention Examples 2 to 8, Comparative Examples 1 and 2] Coated zirconium nitride particles were obtained in the same manner as in Example 1 of the present invention, except that the zirconium oxide powder used as the raw material had an average primary particle diameter as shown in Table 1 below, and that the temperature at which the electric furnace was opened to the atmosphere during cooling after producing the zirconium nitride particles in the electric furnace was also as shown in Table 1 below. In Comparative Example 1, the electric furnace was not opened to the atmosphere during cooling, but was cooled to 30°C while nitrogen gas was supplied into the electric furnace. The average primary particle diameter and oxide layer thickness of the obtained coated zirconium nitride particles were measured in the same manner as in Example 1 of the present invention, and the ratio (2x oxide layer thickness / average primary particle diameter) was calculated. Furthermore, the optical properties were measured before and after storage. The results are shown in Table 1.

[0050] [Table 1]

[0051] From the results in Table 1, the coated zirconium nitride particles obtained in Examples 1 to 8 of the present invention, which have oxide layer thicknesses within the range of the present invention, exhibited T 365nm / T 600nm In contrast, the coated zirconium nitride particles obtained in Comparative Example 1, in which the oxide layer thickness was thinner than the range of the present invention and the ratio of twice the oxide layer thickness of the coated zirconium nitride particles to the average primary particle diameter was less than 0.3, exhibited a T 365nm / T 600nm was 3.1, but T after storage 365nm / T 600nm The T value decreased to 2.4. This is because the surface of the zirconium nitride particles was locally hydrolyzed by moisture during storage, and oxidation progressed deep into the particles, reducing the visible light blocking ability. 600nm Furthermore, the coated zirconium nitride particles obtained in Comparative Example 2, in which the oxide layer thickness was greater than the range of the present invention and the ratio of twice the oxide layer thickness to the average primary particle diameter exceeded 0.8, showed a T 600nm is 40.0%, and T 365nm / T 600nmThe oxide layer on the coated zirconium nitride particles was found to be too thick, i.e., the surface of the zirconium nitride particles was excessively oxidized, resulting in a decrease in the proportion of zirconium nitride components in the particles. [Industrial Applicability]

[0052] The black UV-curable organic composition of this embodiment contains the coated zirconium nitride particles of this embodiment. Therefore, the black UV-curable organic composition of this embodiment can be used, for example, as a black pattern-forming material used as a black matrix of an image-forming element used in a display such as a liquid crystal display or an organic EL display, or as a light-blocking material in an image sensor such as a CMOS sensor. Furthermore, the black UV-curable organic composition of this embodiment can be used as a light-blocking material for optical components, a light-blocking filter, an IR-cut filter, or a coverlay film. [Explanation of symbols]

[0053] 10 Coated zirconium nitride particles 11 Zirconium nitride particles 12 oxide layer

Claims

1. The present invention comprises zirconium nitride particles and an oxide layer covering at least a portion of the surface of the zirconium nitride particles, the oxide layer is a region containing zirconium oxide and zirconium oxynitride, with a zirconium content of 5 atm% or more and an atomic concentration ratio (O / N ratio) of oxygen (O) to nitrogen (N) greater than 1.0; Coated zirconium nitride particles, wherein the oxide layer has a thickness in the range of 10 nm or more and 40 nm or less.

2. 2. The coated zirconium nitride particles according to claim 1, wherein the ratio of the transmittance of light with a wavelength of 365 nm to the transmittance of light with a wavelength of 600 nm measured by the following method is 3.0 or more. (Measurement method) The coated zirconium nitride particles are allowed to stand for 72 hours in an environment at a temperature of 65°C and a relative humidity of 90% RH. The coated zirconium nitride particles are then dispersed in propylene glycol monomethyl ether acetate to prepare a dispersion with a concentration of 50 ppm by mass. The ratio of the transmittance of the prepared dispersion at a wavelength of 365 nm to that at a wavelength of 600 nm is measured.

3. A black ultraviolet-curable organic composition comprising an ultraviolet-curable organic material and a black pigment dispersed in the ultraviolet-curable organic material, 3. A black ultraviolet-curable organic composition, wherein the black pigment is the coated zirconium nitride particles according to claim 1 or 2.

4. 4. The black ultraviolet-curable organic composition according to claim 3, wherein the ultraviolet-curable organic material is at least one organic material selected from the group consisting of an acrylic monomer, an acrylic oligomer, an epoxy monomer, and an epoxy oligomer.

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