| 摘要 |
<p>PURPOSE:To enhance durability against a stroking force without any drop in resilience at the time of stroking a ball by composing a resin component forming a cover of specified potassium ionomer resin and specified magnesium ionomer resin, and maintaining the ratio of both components at a specified value. CONSTITUTION:A resin component forming a cover is formed out of potassium ionomer resin in which 20 to 70mol% of the carboxyl group of ethylene-alpha,beta- unsaturated carboxylic acid copolymer containing 10 to 20wt.% of alpha,beta-unsaturated carboxylic acid is neutralized, and a melt index is kept between 0.6 and 8 and Shore D hardness is kept between 55 and 70, and magnesium ionomer resin in which 20 to 70wt.% of the carboxyl group of ethylene-alpha,beta-unsaturated carboxylic acid copolymer containing 10 to 20wt.% of alpha,beta-unsaturated carboxylic acid is neutralized with magnesium ions, a melt index is kept between 0.6 and 8 and Shore D hardness is kept between 55 and 70. In addition, the ratio of these resin components is kept between 85:15 and 20:80.</p> |
