GLASS COMPOSITION AND COMPOSITE POWDER MATERIAL

Abstract

The present invention relates to a glass composition including: Li.sub.2O; and, as represented by mol % based on oxides, from 60% to 67% of SiO; from 20% to 29% of B.sub.2O.sub.3; from 3% to 9% of CaO; and from 3% to 6% of Al.sub.2O.sub.3, in which a molar ratio (Li.sub.2O:Na.sub.2O:K.sub.2O) among a Li.sub.2O content, a Na.sub.2O content, and a K.sub.2O content is 1:(0-1.9):(0-0.9).

Claims

1. A glass composition comprising: Li.sub.2O; and, as represented by mol % based on oxides, from 60% to 67% of SiO; from 20% to 29% of B.sub.2O.sub.3; from 3% to 9% of CaO; and from 3% to 6% of Al.sub.2O.sub.3, wherein a molar ratio (Li.sub.2O:Na.sub.2O:K.sub.2O) among a Li.sub.2O content, a Na.sub.2O content, and a K.sub.2O content is 1:(0-1.9):(0-0.9).

2. The glass composition according to claim 1, which has a total content of Li.sub.2O, Na.sub.2O, and K.sub.2O, as represented by mol % based on oxides, of from 0.3% to 1.0%.

3. The glass composition according to claim 1, which has a shrinkage initiation temperature of 790° C. or higher.

4. The glass composition according to claim 1, which has a softening point of 900° C. or lower.

5. The glass composition according to claim 1, which has the Li.sub.2O content, as represented by mol % based on oxides, of from 0.2% to 1.0%.

6. A composite powder material comprising from 45 mass % to 55 mass % of a glass powder and from 45 mass % to 55 mass % of alumina filler, wherein the glass powder is a powder comprising the glass composition according to claim 1.

7. The composite powder material according to claim 6, which has a glass transition temperature of 650° C. or higher.

8. The composite powder material according to claim 6, which has a shrinkage initiation temperature of 820° C. or higher.

9. The composite powder material according to claim 6, which has a softening point of 900° C. or lower.

10. The composite powder material according to claim 6, wherein when a fired body obtained by firing the composite powder material at 870° C. for 20 minutes is referred to as a fired body (A) and a fired body obtained by firing the composite powder material at 870° C. for 60 minutes is referred to as a fired body (B), a proportion represented by {[a density of the fired body (B)]/[a density of the fired body (A)]}×100 is from 98.0% to 102.0%.

11. The composite powder material according to claim 6, wherein when a fired body obtained by firing the composite powder material at 870° C. for 60 minutes is referred to as a fired body (B) and a fired body obtained by firing the composite powder material at 900° C. for 60 minutes is referred to as a fired body (C), a proportion represented by {[a density of the fired body (B)]/[a density of the fired body (C)]}×100 is from 99.0% to 101.0%.

Description

EXAMPLES

[0114] The present invention is explained in detail below using Examples, but the present invention is not limited to the following Examples unless the invention departs from the spirit thereof.

[0115] [Production of Glass Compositions]

[0116] Raw materials for glass were mixed together in respective amounts so as to result in each of the glass compositions shown in Table 1. The mixtures were melted for 2 hours in an electric furnace of from 1,550° C. to 1,650° C. using platinum crucibles, and the melts were each formed into a thin glass sheet to obtain a glass composition. Thereafter, each glass composition was pulverized with a ball mill to obtain a powder thereof having a D50 of 2.0 μm. Examples 1-1 to 1-4 are Examples according to the present invention, and Examples 1-5 to 1-12 are Comparative Examples.

[0117] [Evaluation of the Glass Compositions]

[0118] The obtained powders of the glass compositions were each evaluated for shrinkage initiation temperature Sp and softening point Ts using a differential thermal analyzer. The results thereof are shown in Table 1.

TABLE-US-00001 TABLE 1 Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 1-10 1-11 1-12 Glass SiO.sub.2 64.61 64.61 64.61 64.61 64.61 64.61 68.89 69.41 60.93 60.93 66.53 65.00 composition B.sub.2O.sub.3 24.85 24.85 24.85 24.85 24.85 24.85 21.77 19.27 23.46 23.46 25.62 25.00 (mol %) Li.sub.2O 0.40 0.40 0.30 0.60 0.20 0.00 0.30 0.30 0.30 0.30 0.30 0.00 Na.sub.2O 0.20 0.10 0.30 0.00 0.20 0.00 0.30 0.30 0.30 0.30 0.30 0.00 K.sub.2O 0.00 0.10 0.00 0.00 0.20 0.60 0.00 0.00 0.00 0.00 0.00 0.00 CaO 4.97 4.97 4.97 4.97 4.97 4.97 4.37 5.36 10.34 4.67 5.16 5.00 Al.sub.2O.sub.3 4.97 4.97 4.97 4.97 4.97 4.97 4.37 5.36 4.67 10.34 2.09 5.00 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Shrinkage initiation temperature 801 819 797 823 786 813 831 843 864 811 797 835 Sp(° C.) Softening point Ts (° C.) 886 892 876 890 900 886 904 926 955 936 900 910

[0119] [Production of Composite Powder Materials]

[0120] Each of the obtained powders of the glass compositions was mixed with an alumina filler (purity of 99.9%; corundum single crystal) and a magnesia filler (purity of 99.9%) in the proportions shown in Table 2, and the mixtures were each mixed for 1 hour using a wet ball mill employing an alcohol solvent and were then filtered for dehydration and dried, thereby obtaining composite powder materials. The composite powder material of Example 2-1 was one obtained using the powder of the glass composition of Example 1-1, and the composite powder materials of Examples 2-2 to 2-12 are ones respectively obtained using the powder of the glass compositions of Examples 1-2 to 1-12. Examples 2-1 to 2-4 are Examples according to the present invention and Examples 2-5 to 2-12 are Comparative Examples.

[0121] [Evaluation of the Composite Powder Materials]

[0122] The obtained composite powder materials were evaluated for glass transition temperature Tg, shrinkage initiation temperature Sp, and softening point Ts using a differential thermal analyzer. The results thereof are shown in Table 2.

[0123] Meanwhile, 3 g of each of the composite powder materials was put in a mold having a diameter of 30 mm and compacted under a pressure of 200 MPa, and the resultant compacts were fired at 870° C. for 20 minutes, or at 870° C. for 60 minutes, or at 900° C. for 60 minutes to obtain fired bodies, which were examined for density, permittivity, and Q value. The examinations were made by the following methods, and the results thereof are shown in Table 2. In Table 2, “Fired body (A)” means one obtained through firing at 870° C. for 20 minutes, “Fired body (B)” means one obtained through firing 870° C. for 60 minutes, and “Fired body (C)” means one obtained through firing at 900° C. for 60 minutes.

[0124] (Determination of Density)

[0125] The density of each of the fired bodies obtained by firing the composite powder materials under each firing conditions was determined by Archimedes' method.

[0126] (Determination of Dielectric Properties)

[0127] The fired bodies of the composite powder materials were each formed into a given cylindrical shape (having a diameter of 20 mm and a thickness of 3 mm) and examined for dielectric property using an LCR meter (4192A, manufactured by Agilent Inc.) to determine the permittivity and dielectric loss at 20° C. and 1 MHz by a method according to JIS C 2138 (2007). The Q value was calculated as the reciprocal of the dielectric loss.

[0128] (Determination of Dielectric Properties in High-Frequency Range)

[0129] The composite powder materials of Examples 2-1 to 2-4 and 2-12 were fired at 870° C. for 20 minutes to obtain fired bodies (fired bodies (A)), which were examined for dielectric property in the high-frequency range. The composite powder materials of Examples 2-1 to 2-4 were materials which had given fired bodies (fired bodies (B)) through firing at 870° C. for 20 minutes and fired bodies (fired bodies (C)) through firing at 900° C. for 60 minutes, the fired bodies (B) and (C) having had satisfactory dielectric properties at 1 MHz and had satisfactory values of the proportion of the density of the fired body (B) to the density of the fired body (C).

[0130] The dielectric properties in the high-frequency range were determined using a PNA network analyzer N5227A, manufactured by Keysight Technologies, by a method according to JIS R 1627 (1996). The measuring frequencies are shown in Table 2 together with the results.

TABLE-US-00002 TABLE 2 Ex. Ex. Ex. Ex. Ex. Ex. 2-1 2-2 2-3 2-4 2-5 2-6 Composition of Glass composition 49.5 49.5 49.5 49.5 49.5 49.5 composite powder Alumina filler 49.5 49.5 49.5 49.5 49.5 49.5 material (mass %) Magnesia filer 1 1 1 1 1 1 Thermal Glass transition temperature Tg 700 710 682 707 699 709 analysis (° C.) Shrinkage initiation temperature 852 850 851 850 861 858 Sp (° C.) Softening point Ts (° C.) 894 887 885 889 900 905 Density of Density Fired body (A): 2.806 2.797 2.811 2.782 fired body 870° C., 20 min Fired body (B): 2.817 2.810 2.810 2.814 2.747 2.788 870° C., 60 min Fired body (C): 2.796 2.804 2.804 2.812 2.797 2.837 900° C., 60 min [(Density of fired body (B))/ 100.4% 100.5% 100.0% 101.1% (density of fired body (A))] × 100 [(Density of fired body (B))/ 100.8% 100.2% 100.2% 100.1% 98.2% 98.3% (density of fired body (C))] × 100 Measuring Fired body Permittivity 6.03 6.03 6.22 6.17 frequency, (A) Q value 3,333 5,000 3,333 2,000 1 MHz Fired body Permittivity 6.14 6.16 6.18 6.04 6.20 6.14 (B) Q value 2,500 3,333 3,333 2,500 2,500 5,000 Fired body Permittivity 6.15 6.19 6.17 6.06 6.10 6.26 (C) Q value 3,333 5,000 3,333 3,333 10,000 1,429 High- Fired body Measuring 14.8 GHz 14.8 GHz 14.7 GHz 14.9 GHz frequency (A) frequency measurement Permittivity 5.91 5.90 5.92 5.90 Q value 500 526 500 556 Ex. Ex. Ex. Ex. Ex. Ex. 2-7 2-8 2-9 2-10 2-11 2-12 Composition of Glass composition 49.5 49.5 49.5 49.5 49.5 59.5 composite powder Alumina filler 49.5 49.5 49.5 49.5 49.5 39.5 material (mass %) Magnesia filer 1 1 1 1 1 1 Thermal Glass transition temperature Tg 701 759 696 745 743 779 analysis (° C.) Shrinkage initiation temperature 859 879 817 870 885 883 Sp (° C.) Softening point Ts (° C.) 907 925 916 913 927 926 Density of Density Fired body (A): 2.544 fired body 870° C., 20 min Fired body (B): 2.789 2.698 2.863 2.584 2.800 2.645 870° C., 60 min Fired body (C): 2.876 2.792 2.789 2.628 2.729 2.670 900° C., 60 min [(Density of fired body (B))/ 104.0% (density of fired body (A))] × 100 [(Density of fired body (B))/ 97.0% 96.6% 102.7% 98.3% 102.6% 99.1% (density of fired body (C))] × 100 Measuring Fired body Permittivity frequency, (A) Q value 1 MHz Fired body Permittivity 5.97 5.94 6.59 9.78 6.10 5.61 (B) Q value 1,667 34 1,667 3 2,500 1,667 Fired body Permittivity 6.75 6.15 6.13 6.87 5.81 5.71 (C) Q value 1,667 1,250 1,429 7 1,667 3,333 High- Fired body Measuring 15.5 GHz frequency (A) frequency measurement Permittivity 5.5 Q value 67

[0131] The composite powder materials of Examples 2-1 to 2-4, which included the powders of the glass compositions of Examples 1-1 to 1-4, each satisfied that the fired body (B) obtained by firing the material at 870° C. for 60 minutes and the fired body (C) obtained by firing the material at 900° C. for 60 minutes each had a permittivity at 1 MHz of 6.5 or less and a Q value of 2,500 or larger and that the proportion of the density of the fired body (B) obtained by firing the material at 870° C. for 60 minutes to the density of the fired body (C) obtained by firing the material at 900° C. for 60 minutes was from 99% to 101%. It is deemed therefrom that homogeneous and dense fired bodies were formed at temperatures in a wide range. Furthermore, these composite powder materials each satisfied that the proportion of the density of the fired body (B) obtained by firing the material at 870° C. for 60 minutes to the density of the fired body (A) obtained by firing the material at 870° C. for 20 minutes was from 98% to 102% and that the fired body (A) obtained by firing the material at 870° C. for 20 minutes had a permittivity of 6.5 or less and a Q value of 500 or larger at a high frequency of about 15 GHz, showing excellent dielectric properties.

[0132] Meanwhile, the composite powder materials of Examples 2-5 to 2-12, which included the powders of the glass compositions of Examples 1-5 to 1-12, were inferior in at least one of the permittivity, Q value, and sinterability. Furthermore, with respect to the composite powder material of Example 2-12, which included the powder of the glass composition of Example 1-12, which contained no alkali metal oxide, the proportion of the density of the fired body (B) obtained by firing the material at 870° C. for 60 minutes to the density of the fired body (A) obtained by firing the material at 870° C. for 20 minutes was 104.0%, which was extremely poor, although the composite powder material had an increased proportion of the glass composition and a reduced proportion of the alumina filler. Thus, the composite powder material of Example 2-12 had far poorer sinterability than the Examples according to the present invention. In addition, the fired body (A) obtained by firing this material at 870° C. for 20 minutes had a considerably poor Q value of 67 at a high frequency of about 15 GHz.

[0133] While the invention has been described with reference to specific embodiments thereof, the invention is not limited to the embodiments, and various changes and replacements can be made in the embodiments within the scope of the invention.

[0134] This application is based on a Japanese patent application 2020-011937 filed on Jan. 28, 2020, the contents thereof being incorporated herein by reference.