Showa Denko Assigned Four Patents

Magnetic recording medium substrate and hard disk drive
Showa Denko K.K., Tokyo, Japan, has been assigned a patent (10,593,359) developed by Murase, Isao, Tochigi, Japan, and Sugimoto, Kiminori, Osaka, Japan, for a “magnetic recording medium substrate and hard disk drive.“

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A magnetic recording medium substrate is provided in which a NiP type plating film is formed on a surface of an aluminum alloy substrate that includes Si in a range of 9.5 mass % or more and 11.0 mass % or less, Mn in a rage of 0.45 mass % or more and 0.90 mass % or less, Zn in a range of 0.32 mass % or more and 0.38 mass % or less, Sr in a range of 0.01 mass % or more and 0.05 mass % or less. In the alloy structure of the aluminum alloy substrate, an average particle diameter of Si particles is 2 .mu.m or less, the film thickness of the NiP type plating film is 7 .mu.m or more. An outer diameter of the magnetic recording medium substrate is 53 mm or more, the thickness is 0.9 mm or less, and the Young’s modulus is 79 GPa or more.”

The patent application was filed on June 13, 2017 (15/621,319).

Base for magnetic recording medium, and HDD
Showa Denko K.K., Tokyo, Japan, has been assigned a patent (10,573,342) developed by Murase, Isao, Tochigi, Japan, and Sugimoto, Kiminori, Osaka, Japan, for “base for magnetic recording medium, and HDD.“

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A base for a magnetic recording medium, includes a substrate made of an Al alloy and having a surface, and a film made of a NiP-based alloy and plated on the surface of the substrate. The film has a thickness of 7 .mu.m or greater, and a ratio E/.rho. is 29 or greater, where E [GPa] denotes the Young’s modulus of the substrate, and .rho. [g/cm.sup.3] denotes a density of the substrate.”

The patent application was filed on January 10, 2018 (15/866,831).

Magnetic recording medium and magnetic recording/reproducing
Showa Denko K.K., Tokyo, Japan, has been assigned a patent (10,559,320) developed by Nakamura, Satoru, Hung, Taining, Kuo, Evance, and Endo, Daizo, Hsinchu, Taiwan, for “magnetic recording medium and magnetic recording/reproducing apparatus.“

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”The present invention relates to a magnetic recording medium in which a lubricant layer contains a compound A represented by general formula, 1) and a compound B represented by general formula, 2, satisfying, A/B)=0.2 to 3.0, and has an average thickness of 0.8 nm to 2 nm. R.sup.1–C.sub.6H.sub.4OCH.sub.2CH(OH)CH.sub.2OCH.sub.2–R.sup.2–CH.sub.- 2OCH.sub.2CH(OH)CH.sub.2OH . . ., 1, R.sup.1 is an alkoxy group having 1 to 4 carbon atoms. R.sup.2 is –CF.sub.2O(CF.sub.2CF.sub.2O).sub.x(CF.sub.2O).sub.yCF.sub.2–, x, y=0 to 15, –CF.sub.2CF.sub.2O(CF.sub.2CF.sub.2CF.sub.2O).sub.zCF.sub.2CF.su- b.2–, z=1 to 15, –CF.sub.2CF.sub.2CF.sub.2O(CF.sub.2CF.sub.2CF.sub.2CF.sub.2O).sub.nCF.su- b.2CF.sub.2CF.sub.2–, n=0 to 4). HOCH.sub.2CF.sub.2CF.sub.2O(CF.sub.2CF.sub.2CF.sub.2O).sub.mCF.sub.2CF.su- b.2CH.sub.2OCH.sub.2CH(OH)CH.sub.2OH . . ., 2, m is an integer).”

The patent application was filed on December 16, 2015 (15/535,982).

Heat-assisted magnetic recording medium and magnetic storage
Showa Denko K.K., Tokyo, Japan, has been assigned a patent (10,553,242) developed by Zhang, Lei, Fukushima, Takayuki, Xu, Chen, Niwa, Kazuya, Shibata, Hisato, Yamaguchi, Takehiro, Kanbe, Tetsuya, and Shige, Tomoo, Chiba, Japan, for “heat-assisted magnetic recording medium and magnetic storage apparatus.“

The abstract of the patent published by the U.S. Patent and Trademark Office states: ”A heat-assisted magnetic recording medium includes: a substrate, an underlayer, and a magnetic layer that is (001)-oriented. In the magnetic layer, a first magnetic layer and a second magnetic layer are stacked in this order from the underlayer side. The first magnetic layer and the second magnetic layer include an alloy having an L1.sub.0 structure. The second magnetic layer includes a ferrite at grain boundaries of magnetic grains. The ferrite is one or more kinds selected from the group consisting of NiFe.sub.2O.sub.4, MgFe.sub.2O.sub.4, MnFe.sub.2O.sub.4, CuFe.sub.2O.sub.4, ZnFe.sub.2O.sub.3, CoFe.sub.2O.sub.4, BaFe.sub.2O.sub.4, SrFe.sub.2O.sub.4, and Fe.sub.3O.sub.4. A Curie temperature of the magnetic grains is lower than a Curie temperature of the ferrite.”

The patent application was filed on June 19, 2019 (16/445,801).