US-12617933-B2 - Glass filler powder

Abstract

A glass filler powder includes a bubble therein, a volume fraction of the bubble being from 0.2% to 2%.

Inventors

• Masashi Nakamura
• Jun Kinoshita
• Shigeyuki FUKUSAKA

Assignees

• NIPPON ELECTRIC GLASS CO., LTD.

Dates

Publication Date

20260505

Application Date

20210917

Priority Date

20201002

Claims (11)

1. 1 . A glass filler powder comprising a bubble therein, a volume fraction of the bubble being from 0.2% to 2%, from 40 to 80 mass % of SiO 2 , from 0 to 30 mass % of Al 2 O 3 , from 2 to 20 mass % of B 2 O 3 , from 0 to 25 mass % of CaO, from 0 to 10 mass % of ZnO, from 0 to 10 mass % of Li 2 O, from 0 to 30 mass % of Na 2 O, from 0 to 30 mass % of K 2 O, from 0 to 20 mass % of Nb 2 O 5 , from 0 to 20 mass % of WO 3 , from 0.1 to 30 mass % of Nb 2 O 5 +WO 3 , from 0.1 to 15 mass % of TiO 2 , and from 0 to 10 mass % of F.
2. 2 . The glass filler powder according to claim 1 , wherein the glass filler powder is substantially spherical.
3. 3 . The glass filler powder according to claim 1 , wherein the glass filler powder has a specific surface area of 2 m 2 /g 2 m 2 /g or less.
4. 4 . The glass filler powder according to claim 1 , wherein the glass filler powder has an average particle size of 8 μm or less.
5. 5 . The glass filler powder according to claim 1 , wherein the glass filler powder has a refractive index (nd) from 1.48 to 1.62.
6. 6 . The glass filler powder according to claim 1 , wherein the glass filler powder is blended with a resin.
7. 7 . A resin composition comprising the glass filler powder according to claim 1 and a resin.
8. 8 . A formed object comprising the resin composition according to claim 7 .
9. 9 . The formed object according to claim 8 , wherein the formed object has a thickness of 0.5 mm and a light transmittance at a wavelength of 600 nm from 60% to 89%.
10. 10 . A method for manufacturing the glass filler powder according to claim 1 , the method comprising: grinding and classifying a glass raw material to yield a glass powder; and heating and melting the glass powder to spheroidize the glass powder.
11. 11 . The method for manufacturing a filler powder according to claim 10 , wherein the glass raw material is ground by a ball mill.

Description

TECHNICAL FIELD The present invention relates to a glass filler powder used for improving the mechanical strength of a resin. BACKGROUND ART The addition of a filler powder to a resin material has been studied for the purpose of improving the mechanical strength of a formed object including a resin material such as a photocurable resin. An application that is under study is using such a formed object in denture. In order to give an artificial denture a similar appearance to a human tooth (aesthetic appearance), the filler powder must have suitable optical properties. As such, the use of a glass filler powder having excellent light-transmission properties as the filler powder is being studied (see, for example, Patent Document 1). CITATION LIST Patent Literature Patent Document 1: JP 2016-138180 A SUMMARY OF INVENTION Technical Problem Known glass filler powders have an excessively high light transmittance. As such, when a known glass filler powder is blended with a resin to prepare a resin composition, a formed object including the resulting resin composition also tends to have a high light transmittance. Accordingly, when the resulting resin composition is used to produce a denture, the denture also has an excessively high light transmittance. Such a denture deviates from the appearance of a human tooth and is less appealing aesthetically. Note that, although it is conceivable to reduce the light transmittance of the formed object by reducing the amount of the glass filler powder blended, this will make it difficult to ensure the mechanical strength necessary for a denture. In view of the above, an object of the present invention is to provide a glass filler powder capable of, when mixed with a resin, imparting suitable light-transmission properties and making a formed object more appealing aesthetically. Solution to Problem As a result of intensive studies by the present inventors, it was discovered that the above problems can be solved by a glass filler powder containing a predetermined amount of bubbles therein. That is, a glass filler powder according to an embodiment of the present invention includes a bubble therein, a volume fraction of the bubble being from 0.2% to 2%. In this way, the inclusion of a minute amount of bubbles inside the glass filler powder allows for suitable adjustment of the light-transmission properties of a formed object including a resin composition using the glass filler powder, making the formed object more appealing aesthetically and suitable for denture application. The glass filler powder according to an embodiment of the present invention is preferably substantially spherical. In this way, the contact interface with resin is reduced; as such, excessive light scattering in a formed object including a resin composition using the glass filler powder can be suppressed, and suitable light-transmission properties can be imparted to the formed object. In addition, an undesirable increase in the viscosity of the resin composition can be suppressed, and formability can be improved. The glass filler powder according to an embodiment of the present invention preferably has a specific surface area of 2 m2/g or less. In this way, the contact interface with resin is reduced; as such, excessive light scattering in a formed object including a resin composition using the glass filler powder can be suppressed, and suitable light-transmission properties can be imparted to the formed object. In addition, an undesirable increase in the viscosity of the resin composition can be suppressed, and formability can be improved. The glass filler powder according to an embodiment of the present invention preferably has an average particle size of 8 μm or less. In this way, dispersibility in resin can be increased. The glass filler powder according to an embodiment of the present invention preferably has a refractive index nd from 1.48 to 1.62. In this way, the refractive index of the glass filler powder according to an embodiment of the present invention easily matches with the refractive index of the resin, and suitable light-transmission properties can be imparted to a formed object including a resin composition using the glass filler powder. The glass filler powder according to an embodiment of the present invention preferably contains from 40 to 80 mass % of SiO2, from 0 to 30 mass % of Al2O3, from 2 to 20 mass % of B2O3, from 0 to 25 mass % of CaO, from 0 to 10 mass % of ZnO, from 0 to 10 mass % of Li2O, from 0 to 30 mass % of Na2O, from 0 to 30 mass % of K2O, from 0 to 20 mass % of Nb2O5, from 0 to 20 mass % of WO3, from 0.1 to 30 mass % of Nb2O5+WO3, from 0.1 to 15 mass % of TiO2, and from 0 to 10 mass % of F. The glass filler powder according to an embodiment of the present invention is preferably blended with a resin for use. A resin composition according to an embodiment of the present invention contains the glass filler powder described above and a resin. A formed object according to an emb