| 摘要 |
<p>PURPOSE:To improve the abrasion resistance of felt while maintaining the external appearance of the felt covering the core of a tennis ball, and suppressing the fuzz during the play. CONSTITUTION:As the constituent fiber of the felt covering a core, polyterephtharate fiber, which is the fiber consisting of polymer wherein 90% or more of all repeating units of a molecular chain are polyethylene terephtharate units and is equipped with the following properties at the same time, is used. (A): dry thermal shrinkage factor/intrinsic viscosity of polymer; S150 deg.C/IV=5.0%-7.5%. (B): birefringence; nD=170X10<-3>-185X10<-3>. (C): crystal orientation factor; fc=0.935-0.950. (D): noncrystal molecular orientation parameter; F-0.75-0.90.</p> |
