| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a black key having natural woodgrain appearance at low cost. <P>SOLUTION: A black key 10 is integrally molded by injection molding with a metallic mold from a hygroscopic resin based on an AS (acrylonitrile styrene) resin, and a left side surface 12a, right side surface 12b, and upper surface 12d of the mold article having the outer shape of the black key are manually worked to grind with sandpaper within the range of number 60-120 along a key longitudinal direction. Then, a plurality of irregular grooves are formed along the key longitudinal direction, and an arithmetic average roughness Ra of the surfaces where the grooves are formed is made to be within the range of 0.52-4.00 μm and the maximum height Ry is made to be within the range of 2.7-13.8 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT |
