Golf ball
AssigneeSRI Sports Limited
InventorsKeiji Ohama, Kazuya Kamino, Takahiro Sajima
Life of this patent
Estimating the term…
Abstract
A golf ball 2 includes a center 12, a mid layer 14, a reinforcing layer 6, a cover 8 and a paint layer 10. The golf ball 2 has a large number of dimples 16 on the surface thereof. The cover 8 is formed of a resin composition including thermoplastic polyurethane (A) and a polyisocyanate mixture (B). The polyisocyanate mixture (B) includes a urethane prepolymer (B1) having two or more isocyanate groups or an isocyanate compound (B2) having three or more isocyanate groups. The polyisocyanate mixture (B) further includes a thermoplastic resin (B3) which substantially does not react with an isocyanate group. The golf ball 2 is obtained by a mold having protrusions which project from the equator of the mold. Each protrusion includes a part of a pimple.
Claims9
A golf ball comprising a core, a cover positioned outside the core, and a large number of dimples formed on a surface of the cover, wherein,
- the core includes a center and a mid layer positioned outside the center,
- the cover is formed of a resin composition including thermoplastic polyurethane (A) and a polyisocyanate mixture (B),
- the polyisocyanate mixture (B) includes a urethane prepolymer (B1) having two or more isocyanate groups and a thermoplastic resin (B3) which substantially does not react with an isocyanate group,
- the golf ball is formed by a mold including a pair of mold halves and having a large number of pimples on a cavity face of the mold for forming the dimples,
- each mold half has a plurality of protrusions which project from the equator of the mold,
- each protrusion includes a part of one of the pimples, and
- when one of the mold halves is mated with the other mold half, a central angle between any two adjacent protrusions is equal to or greater than 10° and equal to or less than 20°.
A method for manufacturing a golf ball comprising the steps of:
- forming two half shells of a resin composition including thermoplastic polyurethane (A) and a polyisocyanate mixture (B) which includes a urethane prepolymer (B1) having two or more isocyanate groups and a thermoplastic resin (B3) which substantially does not react with an isocyanate group;
- covering a core, including a center and a mid layer, with the two half shells;
- placing the core and the two half shells into a mold which includes a pair of mold halves and has a large number of pimples on a cavity face of the mold for forming dimples, each mold half having a plurality of protrusions which project from the equator of the mold, each protrusion including a part of one of the pimples, a central angle between any two adjacent protrusions being equal to or greater than 10° and equal to or less than 20° when one of the mold halves is mated with the other mold half;
- and
- allowing the resin composition to flow in the mold, thereby forming the dimples having a shape inverted from the shape of the pimples and crosslinking the thermoplastic polyurethane (A) with the urethane prepolymer (B1).
Dependencies are inferred from the claim text.