ZIRCONIUM NITRIDE POWDER AND METHOD FOR PRODUCING SAME

Abstract

High ultraviolet transmittance and high blackness can be obtained, and also has high insulating property.

A zirconium nitride powder of the present invention has a volume resistivity of 10.sup.7 Ω.Math.cm or more in the state of the pressurized powder body hardened at a pressure of 5 MPa, and a particle size distribution D.sub.90 of 10 μm or less when ultrasonically dispersed for 5 minutes in a state of being diluted with water or an alcohol having a carbon number of which is in a range of 2 to 5. Also, the zirconium nitride powder is dispersed in an acrylic monomer or an epoxy monomer to prepare a monomer dispersion. Further, the zirconium nitride powder is dispersed in a dispersing medium as a black pigment and further a resin is mixed to prepare a black composition.

Claims

1. A zirconium nitride powder having a volume resistivity of 10.sup.7 Ω.Math.cm or more in a state of a pressurized powder body hardened at a pressure of 5 MPa, and a particle size distribution D.sub.90 of 10 μm or less when ultrasonically dispersed for 5 minutes in a state of being diluted with water or an alcohol having a carbon number is in a range of 2 to 5.

2. A method for producing a zirconium nitride powder which comprises: a step of generating a zirconium nitride crude powder by a thermite process or a plasma synthetic method, a step of fabricating a zirconium nitride precursor powder having a particle size distribution D.sub.90 of 10 μm or less when ultrasonically dispersed for 5 minutes in a state of being diluted with water or an alcohol having a carbon number in a range of 2 to 5 by subjecting the zirconium nitride crude powder to low temperature wet media pulverization at a temperature of a dispersing medium of 10° C. or lower or subjecting to jet mill pulverization at a gas pressure of 0.3 MPa or higher; and a step of producing a zirconium nitride powder having a volume resistivity of 10.sup.7 Ω.Math.cm or more in the state of the pressurized powder body hardened at a pressure of 5 MPa by firing the pulverized zirconium nitride precursor powder in an inert gas atmosphere.

3. A monomer dispersion wherein the zirconium nitride powder according to claim 1 is dispersed in an acrylic monomer or an epoxy monomer.

4. A black composition wherein the zirconium nitride powder according to claim 1 is dispersed as a black pigment in a dispersing medium and a resin is further mixed.

5. A method for producing a black film comprising: a step of forming a coating film by coating the monomer dispersion according to claim 3 onto a substrate; and a step of fabricating a black film by subjecting the coated film to heat curing or ultraviolet curing.

6. A method for fabricating a black film comprising: a step of forming a coating film by coating the black composition according to claim 4 onto a substrate; and a step of fabricating a black film by subjecting the coated film to heat curing or ultraviolet curing.

Description

EXAMPLES

[0050] Next, Examples of the present invention will be explained in detail together with Comparative Examples.

Example 1

[0051] First, a zirconium nitride crude powder was prepared by the thermite process. Specifically, to 7.4 g of a monoclinic zirconium dioxide powder having an average primary particle size of 50 nm calculated from the specific surface area measured by the BET method were added 7.3 g of a metallic magnesium powder having an average primary particle size of 150 μm and 3.0 g of a magnesium nitride powder having an average primary particle size of 200 nm, and the mixture was uniformly mixed by a reaction apparatus in which a graphite boat was inner packaged in a glass tube made of quartz. At this time, the added amount of the metallic magnesium was 5.0-fold mol of that of the zirconium dioxide, and the added amount of the magnesium nitride was 0.5-fold mol of that of the zirconium dioxide. This mixture was fired at a temperature of 700° C. for 60 minutes under an atmosphere of a nitrogen gas to obtain a fired product. This fired product was dispersed in 1 liter of water, 10% hydrochloric acid was gradually added to wash the mixture at a pH of 1 or more while maintaining the temperature to 100° C. or lower, and then, the mixture was adjusted to pH 7 to pH 8 with 25% aqueous ammonia and filtered. The filtered solid content was dispersed again in water with 400 g/liter, and once again, in the same manner as mentioned above, the mixture was subjected to acid washing and pH adjustment with aqueous ammonia, and then filtered. After acid washing and pH adjustment with aqueous ammonia were repeated twice in such a manner, the filtrate was dispersed in ion exchanged water with 500 g/liter in terms of a solid content, and after heating at 60° C. under stirring and adjusting to pH 7, filtered by a suction filtration apparatus and further washed with an equal amount of ion exchanged water, and dried in a hot air dryer at a setting temperature of 120° C. to obtain a zirconium nitride crude powder.

[0052] Next, 20 g of the above-mentioned zirconium nitride crude powder was dispersed in 5 liters of isopropanol, and low-temperature wet media pulverization (media: alumina) was carried out for 60 minutes to obtain a zirconium nitride precursor powder. The temperature of isopropanol (dispersing medium) at this time was 5° C. or lower. Further, the above-mentioned zirconium nitride precursor powder was dried and maintained in an N.sub.2 gas atmosphere at a temperature of 350° C. for 4 hours to fire the same to obtain a zirconium nitride powder. This zirconium nitride powder was designated as Example 1.

Examples 2 to 12 and Comparative Examples 1 to 10

[0053] Zirconium nitride powders of Examples 2 to 12 and Comparative Examples 1 to 10 were prepared by each generating a zirconium nitride crude powder, each pulverizing, and further each firing according to the method shown in Table 1. Incidentally, a zirconium nitride powder was fabricated in the same manner as in Example 1 except for the generating method, pulverization method and firing method shown in Table 1. Incidentally, in the column of the generating method of the zirconium nitride crude powder in Table 1, “TM” is the thermite process, and “PZ” is the plasma method. Also, in the column of the pulverization method of the zirconium nitride crude powder in Table 1, “BM” is the beads mill method, and “JM” is the jet mill method. Further, in the column of the firing time/gas of the zirconium nitride precursor powder in Table 1, “N.sub.2” is the nitrogen gas, “He” is the helium gas, and “Ar” is the argon gas.

[0054] <Comparative Test 1>

[0055] With regard to zirconium nitride powders of Examples 1 to 12 and Comparative Examples 1 to 10, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water were each measured. These results are shown in Table 1.

[0056] <Comparative Test 2>

[0057] With regard to 40 g of the zirconium nitride powders of Examples 1 to 11 and Comparative Examples 1 to 9, as shown in Table 1, each was dispersed in 200 ml of an acrylic monomer or an epoxy monomer to prepare a monomer dispersion. On the other hand, with regard to 40 g of the zirconium nitride powders of Example 12 and Comparative Example 10, as shown in Table 1, an amine-based dispersant was added thereto and dispersion treatment was carried out in 200 ml of propylene glycol monomethyl ether acetate (PGMEA) solvent to prepare a black pigment dispersed liquid, and then, an acrylic resin was added to these black pigment dispersed liquids with a mass ratio of black pigment:resin=3:7 and mixed to prepare a black composition. Then, 4 g of Irgacure 500 (photopolymerization initiator: manufactured by BASF) was added to the above-mentioned monomer dispersion or the black composition. Next, after the above-mentioned monomer dispersion or black composition was spin-coated on a glass substrate so that the film thickness after firing became the thickness as shown in Table 1, prebaking was carried out to evaporate the solvent to form a photoresist film. Further, after exposing the photoresist film to a predetermined pattern shape through a photomask, the photoresist film was developed by using an alkaline developer to dissolve and remove the unexposed portion thereof, thereafter, post-baking was carried out to form a black film, respectively. With regard to these black films, OD values of ultraviolet rays (center wavelength 370 nm) and visible light (center wavelength 560 nm) were measured using a densitometer of a product name of D200 manufactured by Macbeth Co., Ltd., based on the above-mentioned equation (1), respectively, and the volume resistivity (Ω.Math.cm) of each black film was also measured. These results were shown in Table 1.

TABLE-US-00001 TABLE 1 Zirconium nitride Zirconium nitride precursor powder crude powder Calcination Calcination Forming Pulverization Pulverization temperature time/gas method method conditions (° C.) (hr) Example 1 TM BM 5° C. or 350   4/N.sub.2 lower Example 2 PZ BM 5° C. or 350   4/N.sub.2 lower Example 3 TM JM 0.5 MPa 350   4/N.sub.2 Example 4 PZ BM 5° C. or 350   4/N.sub.2 lower Example 5 TM BM 10° C. 350   4/N.sub.2 Example 6 TM BM  5° C. 250   4/N.sub.2 Example 7 TM BM  5° C. 350   1/N.sub.2 Example 8 TM BM  5° C. 550   1/N.sub.2 Example 9 TM BM  5° C. 350 4/He Example 10 TM BM  5° C. 350 4/Ar Example 11 TM JM 0.3 MPa 350   4/N.sub.2 Example 12 TM BM 5° C. or 350   4/N.sub.2 lower Comparative TM None — 350   4/N.sub.2 example 1 Comparative PZ None — 350   4/N.sub.2 example 2 Comparative TM BM 5° C. or None None example 3 lower Comparative PZ BM 5° C. or None None example 4 lower Comparative TM BM 12° C. 350   4/N.sub.2 example 5 Comparative TM BM  5° C. 200   4/N.sub.2 example 6 Comparative TM BM  5° C. 350 0.5/N.sub.2 example 7 Comparative TM BM  5° C. 600   1/N.sub.2 example 8 Comparative TM JM 0.2 MPa 350   4/N.sub.2 example 9 Comparative TM None — 350   4/N.sub.2 example 10 Zirconium nitride powder Volume resistivity of pressurized Particle Black film powder size Monomer or Film Volume body distribution dispersing thickness OD resistivity (Ω .Math. cm) (μm) medium μm value (Ω .Math. cm) Example 1 1 × 10.sup.8  7 Acryl 100 2.1 5 × 10.sup.13 Example 2 1 × 10.sup.7  5 Epoxy 100 2.2 2 × 10.sup.13 Example 3 2 × 10.sup.8  6 Epoxy 100 2.2 2 × 10.sup.14 Example 4 1 × 10.sup.7  5 Acryl 100 2.3 1 × 10.sup.13 Example 5 8 × 10.sup.7 10 Acryl 100 2.0 3 × 10.sup.13 Example 6 3 × 10.sup.7  8 Acryl 100 2.0 2 × 10.sup.13 Example 7 1 × 10.sup.7  7 Acryl 100 2.0 1 × 10.sup.13 Example 8 1 × 10.sup.8  8 Acryl 100 2.4 1 × 10.sup.14 Example 9 8 × 10.sup.7  7 Acryl 100 2.2 3 × 10.sup.13 Example 10 8 × 10.sup.7  9 Acryl 100 2.2 3 × 10.sup.13 Example 11 2 × 10.sup.7 10 Epoxy 100 2.4 1 × 10.sup.13 Example 12 1 × 10.sup.8  7 PGMEA  2 2.1 5 × 10.sup.13 Comparative 1 × 10.sup.5 30 Acryl 100 1.0 1 × 10.sup.6  example 1 Comparative 3 × 10.sup.4 14 Epoxy 100 1.2 2 × 10.sup.6  example 2 Comparative 1 × 10.sup.6  9 Acryl 100 2.1 5 × 10.sup.11 example 3 Comparative 2 × 10.sup.4  5 Epoxy 100 2.0 2 × 10.sup.10 example 4 Comparative 7 × 10.sup.6 10 Acryl 100 2.0 4 × 10.sup.12 example 5 Comparative 1 × 10.sup.6  8 Acryl 100 2.0 1 × 10.sup.12 example 6 Comparative 3 × 10.sup.6  7 Acryl 100 2.0 2 × 10.sup.12 example 7 Comparative 4 × 10.sup.6 14 Acryl 100 1.2 1 × 10.sup.9  example 8 Comparative 2 × 10.sup.6 14 Epoxy 100 1.3 1 × 10.sup.11 example 9 Comparative 1 × 10.sup.5 30 PGMEA  2 1.9 6 × 10.sup.12 example 10

[0058] As clearly seen from Table 1, in the zirconium nitride powders of Comparative Examples 1 and 10, i.e., whereas the zirconium nitride crude powder was prepared by the thermite process, in the zirconium nitride powder in which the zirconium nitride was not pulverized and was fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was each 1×10.sup.5 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was each 30 μm, which was larger than the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 1 in an acrylic monomer was small as 1.0 than the appropriate range (2.0 or more), and the volume resistivity was 1×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 or more), and the coating film did not become uniform. Further, the OD value of the black film prepared by dispersing the zirconium nitride powder of Comparative Example 10 in propylene glycol monomethyl ether acetate (PGMEA) was 1.9, which was smaller than the appropriate range (2.0 or more), and the volume resistivity was 6×10.sup.12 Ω.Math.cm which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0059] In the zirconium nitride powder of Comparative Example 3, i.e., in the zirconium nitride powder in which the zirconium nitride precursor powder was not fired whereas the zirconium nitride crude powder was fabricated by the thermite process, and the zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C. or lower, the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 9 μm, which was within the appropriate range (10 μm or less), but the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 1×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 3 in an acrylic monomer was 2.1, which was within the appropriate range (2.0 or more), but the volume resistivity was 5×10.sup.11 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0060] Contrary to these, in the zirconium nitride powders of Examples 1 and 12, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C. or lower, and then, fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivities in the state of the pressurized powder body hardened at a pressure of 5 MPa were each 1×10.sup.8 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distributions D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water were each 7 μm, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 1 in an acrylic monomer was 2.1, which was within the appropriate range (2.0 or more), and the volume resistivity was 5×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 or more). Further, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 12 in propylene glycol monomethyl ether acetate (PGMEA) was 2.1, which was within the appropriate range (2.0 or more), and the volume resistivity was 5×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0061] In the zirconium nitride powder of Example 9, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., and then, fired by retaining the temperature at 350° C. for 4 hours in the helium gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 8×10.sup.7 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 7 μm, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 9 in an acrylic monomer was 2.2, which was within the appropriate range (2.0 or more), and the volume resistivity was 3×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0062] In the zirconium nitride powder of Example 10, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., and then, fired by retaining the temperature at 350° C. for 4 hours in the argon gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 8×10.sup.7 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 9 μm, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 10 in an acrylic monomer was 2.2, which was within the appropriate range (2.0 or more), and the volume resistivity was 3×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0063] On the other hand, in the zirconium nitride powder of Comparative Example 2, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the plasma method, but the zirconium nitride was not pulverized and fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 3×10.sup.4 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 14 lam, which was larger than the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 2 in an epoxy monomer was 1.2, which was smaller than the appropriate range (2.0 or more), and the volume resistivity was 2×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0064] In the zirconium nitride powder of Comparative Example 4, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the plasma method, this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C. or lower, but the zirconium nitride precursor powder was not fired, the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 5 μm, which was within the appropriate range (10 μm or less), but the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 2×10.sup.4 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 4 in an epoxy monomer was 2.0, which was within the appropriate range (2.0 or more), but the volume resistivity was 2×10.sup.10 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0065] Contrary to these, in the zirconium nitride powders of Examples 2 and 4, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the plasma method, and this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C. or lower, and then, fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivities in the state of the pressurized powder body hardened at a pressure of 5 MPa were each 1×10.sup.7 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distributions D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water were each 5 μm, which was within the appropriate range (10 μm or less). Also, the OD value of the black film prepared by dispersing the zirconium nitride powder of Example 2 in an epoxy monomer was 2.2, which was within the appropriate range (2.0 or more), and the volume resistivity was 2×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 or more). Further, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 4 in an acrylic monomer was 2.3, which was within the appropriate range (2.0 or more), and the volume resistivity was 1×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0066] On the other hand, in the zirconium nitride powder of Comparative Example 5, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, but the zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 12° C. which was higher than the appropriate dispersing medium temperature range (10° C. or lower), and then, fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 10 μm, which was within the appropriate range (10 μm or less), but the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 7×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 5 in an acrylic monomer was 2.0, which was within the appropriate range (2.0 or more), but the volume resistivity was 4×10.sup.12 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0067] To the contrary, in the zirconium nitride powder of Example 5, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and the zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 10° C. which was within the appropriate dispersing medium temperature range (10° C. or lower), and then, fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 8×10.sup.7 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 10 μm, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 5 in an acrylic monomer was 2.0, which was within the appropriate range (2.0 or more), and the volume resistivity was 3×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0068] On the other hand, in the zirconium nitride powder of Comparative Example 6, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., but fired by retaining at the firing temperature of 200° C. which was lower than the appropriate range (250° C. to 550° C.) for the firing time of 4 hours which was within the appropriate range (1 hour to 5 hours) in the nitrogen gas atmosphere, the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 8 μm, which was within the appropriate range (10 μm or less), but the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 1×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 6 in an acrylic monomer was 2.0, which was within the appropriate range (2.0 or more), but the volume resistivity was 1×10.sup.12 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0069] In the zirconium nitride powder of Comparative Example 7, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., but fired by retaining at the firing temperature of 350° C. which was within the appropriate range (250° C. to 550° C.) and the firing time of 0.5 hour which was shorter than the appropriate range (1 hour to 5 hours) in the nitrogen gas atmosphere, the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 7 μm, which was within the appropriate range (10 μm or less), but the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 3×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 7 in an acrylic monomer was 2.0, which was within the appropriate range (2.0 or more), but the volume resistivity was 2×10.sup.12 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0070] In the zirconium nitride powder of Comparative Example 8, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., but fired by retaining at the firing temperature of 600° C. which was a temperature higher than the appropriate range (250° C. to 550° C.) for the firing time of 1 hour which was within the appropriate range (1 hour to 5 hours) in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 4×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 14 μm, which was larger than the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 8 in an acrylic monomer was 1.2, which was smaller than the appropriate range (2.0 or more), and the volume resistivity was 1×10.sup.9 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0071] Contrary to these, in the zirconium nitride powder of Example 6, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., and then, fired by retaining the temperature at 250° C. which was the firing temperature within the appropriate range (250° C. to 550° C.) for 4 hours which was the firing time within the appropriate range (1 hour to 5 hours) in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 3×10.sup.7 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 8 lam, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 6 in an acrylic monomer was 2.0, which was within the appropriate range (2.0 or more), and the volume resistivity was 2×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0072] In the zirconium nitride powder of Example 7, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., and then, fired by retaining the temperature at 350° C. which was the firing temperature within the appropriate range (250° C. to 550° C.) for 1 hour which was the firing time within the appropriate range (1 hour to 5 hours) in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 1×10.sup.7 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 7 lam, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 7 in an acrylic monomer was 2.0, which was within the appropriate range (2.0 or more), and the volume resistivity was 1×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0073] In the zirconium nitride powder of Example 8, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and this zirconium nitride crude powder was pulverized (low temperature wet media pulverization) by the beads mill method at the temperature of the dispersing medium of 5° C., and then, fired by retaining the temperature at 550° C. which was the firing temperature within the appropriate range (250° C. to 550° C.) for 1 hour which was the firing time within the appropriate range (1 hour to 5 hours) in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 1×10.sup.8 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 8 lam, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 8 in an acrylic monomer was 2.4, which was within the appropriate range (2.0 or more), and the volume resistivity was 1×10.sup.14 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0074] On the other hand, in the zirconium nitride powder of Comparative Example 9, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, but the zirconium nitride crude powder was pulverized by jet mill pulverization with the pulverization pressure of 0.2 MPa which was smaller than the appropriate range (0.3 MPa or more), and then, fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 2×10.sup.6 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 14 μm, which was larger than the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Comparative Example 9 in an epoxy monomer was 1.3, which was smaller than the appropriate range (2.0 or more), and the volume resistivity was 1×10.sup.11 Ω.Math.cm, which was smaller than the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0075] To the contrary, in the zirconium nitride powder of Example 3, i.e., in the zirconium nitride powder in which the zirconium nitride crude powder was fabricated by the thermite process, and the zirconium nitride crude powder was pulverized by jet mill pulverization with the pulverization pressure of 0.5 MPa, which was within the appropriate range (0.3 MPa or more), and then, fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 2×10.sup.8 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 6 lam, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 3 in an epoxy monomer was 2.2, which was within the appropriate range (2.0 or more), and the volume resistivity was 2×10.sup.14 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

[0076] In the zirconium nitride powder of Example 11, i.e., in the zirconium nitride powder of Example 11 in which the zirconium nitride crude powder was fabricated by the thermite process, and the zirconium nitride crude powder was pulverized by jet mill pulverization with the pulverization pressure of 0.3 MPa, which was within the appropriate range (0.3 MPa or more), and then, fired by retaining the temperature at 350° C. for 4 hours in the nitrogen gas atmosphere, the volume resistivity in the state of the pressurized powder body hardened at a pressure of 5 MPa was 2×10.sup.7 Ω.Math.cm, which was within the appropriate range (1×10.sup.7 Ω.Math.cm or more), and the particle size distribution D.sub.90 when ultrasonically dispersed for 5 minutes in the state of being diluted with water was 10 lam, which was within the appropriate range (10 μm or less). Also, the OD value of the black film fabricated by dispersing the zirconium nitride powder of Example 11 in an epoxy monomer was 2.4, which was within the appropriate range (2.0 or more), and the volume resistivity was 1×10.sup.13 Ω.Math.cm, which was within the appropriate range (1×10.sup.13 Ω.Math.cm or more).

UTILIZABILITY IN INDUSTRY

[0077] The zirconium nitride powder of the present invention can be used as a black pigment for obtaining a black film having high blackness and high insulating property.