| 摘要 |
PURPOSE:To provide a ball having a high brake function without any deterioration in the feeling of shooting, a shooting sound and the function of a straight forward motion. CONSTITUTION:At least the surface layer of a ball 1 is formed out of a viscoelastic material, and the surface of the ball 1 has a deformable element to undergo deformation at the time of rolling. In this case, the viscoelastic material is formed to have surface hardness above 10 but less than 40 when measured by ASTM-D method. In addition, a loss tangent (tandelta) at an angular velocity, epsilon=110Hz, shows a maximum value of 0.3 or more at a temperature between 0 and 50 deg.C. |
