Tennis ball
AssigneeSumitomo Rubber Industries, Ltd.
InventorsMasao Nakamura, Ichiro Tominaga
Life of this patent
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Abstract
A tennis ball having a felt covering which has superior abrasion resistance, felt appearance and resistance to fuzzing which may occur during the use of ball, the felt covering being made of a polyethylene terephthalate fiber including a polyethylene terephthalate (PET) polymer containing at least 90 mole % of recurring ethylene terephthalate units which satisfies the following parameters: (a) a value of hot air shrinkability/intrinsic viscosity of polymer falling within the range of 5.0 to 7.5%, (b) birefringence of 170.times.10.sup.-3 to 185.times.10.sup.-3, (c) Orientation factor for crystallites fc=0.935 to 0.950, and (d) amorphous molecular orientation parameter of 0.75 to 0.90.
Claims3
A tennis ball comprising a core and a woven felt covering affixed thereto, wherein said felt covering consists essentially of 5 to 50% by weight of a fiber of a polyethylene terephthalate polymer containing at least 90% by mole of recurring units of ethylene terephthalate, 50 to 95% by weight of a wool fiber and 0 to 45% by weight of a nylon fiber, said fiber of polyethylene terephthalate polymer satisfying the following conditions:
- (a) hot air shrinkability/intrinsic viscosity of the polymer .DELTA.S.sub.150.degree. C. /IV=5.0 to 7.5%,
- (b) birefringence .DELTA.n.sub.D =170.times.10.sup.-3 to 185.times.10.sup.-3,
- (c) Orientation factor for crystallites fc=0.935 to 0.950, and
- (d) amorphous molecular orientation parameter F=0.75 to 0.90.
A Tennis ball comprising a core and a woven felt covering affixed thereto, wherein said felt covering consists essentially of 5 to 50% by weight of a fiber of a polyethylene terephthalate polymer containing at least 90% by mole of recurring units of ethylene terephthalate, and 50 to 95% by weight of wool fiber, said fiber of polyethylene terephthalate polymer satisfying the following conditions:
- (a) hot air shrinkability/intrinsic viscosity of the polymer .DELTA.S.sub.150.degree. C. /IV=5.0 to 7.5%,
- (b) birefringence .DELTA.n.sub.D =170.times.10.sup.-3 to 185.times.10.sup.-3,
- (c) Orientation factor for crystallites fc=0.935 to 0.950, and
- (d) amorphous molecular orientation parameter F=0.75 to 0.90.
A Tennis ball comprising a core and a woven felt covering affixed thereto, wherein said felt covering consists essentially of 15 to 40% by weight of a fiber of a polyethylene terephthalate polymer containing at least 90% by mole of recurring units of ethylene terephthalate, 60 to 85% by weight of a wool fiber and 0 to 25% by weight of a nylon fiber, said fiber of polyethylene terephthalate polymer satisfying the following conditions:
- (a) hot air shrinkability/intrinsic viscosity of the polymer .DELTA.S.sub.150.degree. C. /IV=5.0 to 7.5%,
- (b) birefringence .DELTA.n.sub.D =170.times.10.sup.-3 to 185.times.10.sup.-3,
- (c) Orientation factor for crystallites fc=0.935 to 0.950, and
- (d) amorphous molecular orientation parameter F=0.75 to 0.90.
Dependencies are inferred from the claim text.