Granules and method for their production, method for producing molten glass, and method for producing glass product

摘要

Granules of a glass raw material mixture, for producing alkali-free glass containing substantially no alkali metal oxides, such that the glass composition of glass obtained from the granules comprises, as represented by mol % based on oxides, 60-75 mol % of SiO2, 5-15 mol % of Al2O3, 1-9 mol % of B2O3, 0-15 mol % of MgO, 0-20 mol % of CaO, 0-12 mol % of SrO and 0-21 mol % of BaO, provided that the total of CaO, SrO and BaO is more than 0, and in an X-ray diffraction spectrum of the granules obtained by means of a CuKα ray, when the diffraction peak area of quartz (100) in a range of 2θ being 19.85-21.71 degrees is taken as 1, the total of the relative values of the diffraction peak areas of strontium borate hydrate, calcium borate hydrate and barium borate hydrate, is at least 0.005.

主权项

1. Granules of a glass raw material mixture, such that glass obtained from the granules is alkali-free glass having the following glass composition containing substantially no alkali metal oxides,
Glass composition (represented by mol % based on oxides):
SiO2: from 60 to 75 mol %,Al2O3: from 5 to 15 mol %,B2O3: from 1 to 9 mol %,MgO: from 0 to 15 mol %,CaO: from 0 to 20 mol %,SrO: from 0 to 12 mol %,BaO: from 0 to 21 mol %, provided that the total of CaO, SrO and BaO is more than 0 mol %; the granules contain at least one member selected from the group consisting of strontium borate hydrate, calcium borate hydrate and barium borate hydrate; and in an X-ray diffraction spectrum of the granules obtained by means of a CuKα ray, when the diffraction peak area of quartz (100) in a range of 2θ being from 19.85 to 21.71 degrees is taken as 1, the total of the relative value of the diffraction peak area of strontium borate hydrate in a range of 2θ being from 10.81 to 13.01 degrees, the relative value of the diffraction peak area of calcium borate hydrate in a range of 2θ being from 11.11 to 13.49 degrees, and the relative value of the diffraction peak area of barium borate hydrate in a range of 2θ being from 10.91 to 13.27 degrees, is at least 0.005.