AGC Assigned Patent

AGC Inc., Chiyoda-ku, Japan, has been assigned a patent (10,766,806) developed by Maeda, Eriko, Hijiya, Hiroyuki, Nagai, Kensuke, Nakashima, Tetsuya, and Kuroiwa, Yutaka, Tokyo, Japan, for “glass for data storage medium substrate, glass substrate for data storage medium, and magnetic disk.“

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”The present invention pertains to a glass for a data storage medium substrate which contains a specific amount of each of SiO.sub.2, Al.sub.2O.sub.3, MgO, CaO, SrO, BaO, Li.sub.2O, Na.sub.2O, and K.sub.2O, in molar percentage based on the oxides, and does not substantially contain B.sub.2O.sub.3 or ZrO.sub.2, wherein the sum of the Li.sub.2O, Na.sub.2O, and K.sub.2O contents, R.sub.2O, the molar ratio of the SiO.sub.2 content to the Al.sub.2O.sub.3 content, SiO.sub.2/Al.sub.2O.sub.3, and the molar ratio of the sum of the SiO.sub.2 and Al.sub.2O.sub.3 contents, SiO.sub.2+Al.sub.2O.sub.3) to R.sub.2O[(SiO.sub.2+Al.sub.2O.sub.3)/R.sub.2O] fall within their specific ranges, formula, 1): 90<[SiO.sub.2]+2.times.[Al.sub.2O.sub.3]+0.8.times.[RO]-0.5.times.[R.s- ub.2O] [in formula, 1, RO represents the sum of the MgO, CaO, SrO, and BaO contents] is satisfied, and the glass transition point T.sub.g, the alkali resistance, and the acid resistance fall within their specific ranges.”

The patent application was filed on April 4, 2018 (15/945,144).