Sri Sports Limited

Sumitomo Rubber Industries Limited

Masaaki Kikuchi

Masatoshi Yokota

Seiichiro Endo

Keiji Moriyama

Kazuhiko Isogawa

Koichi Fujisawa

Takashi Sasaki

Hiroaki Tanaka

Tsutomu Hirau

Satoshi Iwami

Akira Kato

Takeshi Asakura

Hideki Sano

Haruki Shinagawa

The present invention provides a golf ball having excellent rebound characteristics and flight performance, while maintaining good durability and appearance. The present invention relates to a golf ball comprising a center, an intermediate layer and a cover, the intermediate layer comprises an outermost layer and a second layer adjacent to the underside of the outermost layer, and the cover has many dimples on the surface thereof, wherein the second layer is formed from thermoplastic resin and has a thickness of 0.5 to 2.0 mm, the outermost layer is formed from thermosetting or thermoplastic resin and has a thickness of 1 to 100 &#x3bc;m, the intermediate layer has depressions on the surface thereof at the position and shape corresponding to the dimples through the cover, and the cover is formed from thermoplastic resin and has a thickness of 0.1 to 0.8 mm in land portion having no dimple.

Golf ball

The present invention provides a golf ball having excellent rebound characteristics and excellent flight performance, while maintaining good durability and good appearance. The present invention relates to a golf ball comprising a core composed of a center and at least one intermediate layer formed on the center, and a cover covering the core, and having many dimples on the surface thereof, wherein the outermost layer of the intermediate layer is formed from thermoplastic resin, has a thickness of 0.5 to 3.0 mm, and has depressions on the surface thereof at the position and shape corresponding to the dimples through the cover, and the cover is formed from thermoplastic resin and has a thickness of 0.1 to 0.8 mm in land portion having no dimple.

A method of producing a golf ball with uniform thickness by, eliminating defective air between the cover and the core, an insufficient thickness of the cover and an uneven thickness of the cover wherein in the step of heat and compression molding to cover the core or an intermediate layer with shells molded from a cover material mainly composed of a thermoplastic resin, if the mold has a temperature of T&#xb0; C. and the half shells start to flow at a temperature of T&#xb0; C., Tminus Tis set within a range of &#x2212;3&#xb0; C. to +10&#xb0; C.

Method of producing a golf ball

There is provided a method of producing a golf ball, capable of forming a cover to have a uniform thickness to produce a golf ball excellent in resistance to abrasion. The method includes a step to subject a cover material mainly composed of a thermoplastic resin to heat and compression molding to form a half shell, and a step to allow two such half shells to be arranged on a core or an intermediate layer, joined together, and heat and compression molded to mold the cover to have a thickness of 0.3 to 1.5 mm.

A golf ball is provided which contains a core and a cover. In the forming of the cover, two half shells made from a thermoplastic resinous composition are used to cover the core, the composite is put in a spherical mold, then, the mold is clamped. Thereafter, the thermoplastic resin where it is heated and pressurized at a pressure of 5 kgf/cmto 50 kgf/cm, and the excess thermoplastic resin composition flows out of the spherical cavity. Subsequently, the thermoplastic resin composition is heated in the spherical cavity and is pressurized at a pressure of 70 kgf/cmor more whereby the cover is formed. The total volume of the two half shells is 105% to 120% of the volume of the cover.

Golf ball manufacturing method

Half shellhas a bowl-like shape, and is composed of a thermoplastic resin composition. The half shellhas a top partand a side part. The thickness Tt of the top partis less than the thickness Ts of the side part. The difference (Ts&#x2212;Tt) between both thicknesses is 0.02 mm or greater and 0.30 mm or less. Two half shellsand a core covered by the half shellsare placed into a mold comprising an upper portion and a lower portion both of which having a semi hemispherical cavity. Upon clamping, the thermoplastic resin composition is compressed while being heated, resulting in outflow of the excess thermoplastic resin composition from the cavity. A cover is formed having the nominal thickness of 0.3 mm or greater and 1.0 mm or less with remained thermoplastic resin composition.

Process for producing golf ball

A golf ball printing ink is provided which ensures a sufficient pot life, requires a shortened drying time after printing, and yields a mark having a clear appearance and superior durability. Also provided are a printing method using the ink, a golf ball bearing a mark printed with the ink, and a method of manufacturing a golf ball. The golf ball printing ink includes a solvent, a resin in a solid state at ordinary temperature or a reactive curing resin which is curable through reaction with a curing agent, and an ultraviolet-curing resin. The method of manufacturing a golf ball includes the steps of: printing a mark on a surface of a golf ball body with use of the ink; irradiating the mark with ultraviolet ray after the printing; and applying a clear paint to the golf ball body after the ultraviolet ray irradiation.

Golf ball printing ink, golf ball bearing a mark printed with the ink, and method of manufacturing the golf ball

A method for manufacturing a golf ball in which the eccentricity of an inner core of the golf ball is greatly reduced. The method includes the steps of providing a mold which defines a mold cavity, positioning a vulcanized inner core in the mold cavity so as to define a shell space between the inner core and an inner surface of the mold cavity, introducing an unvulcanized rubber material into the shell space so that a layer of unvulcanized rubber covers the inner core, forming an intermediate product, removing the intermediate product from the mold, placing the intermediate product into a vulcanization mold cavity containing a dimple-forming interior surface and vulcanizing the layer of unvulcanized rubber and forming dimples in the rubber material during vulcanization.

Method for manufacturing golf ball

A cavity die ( ) has a flange part ( ), a body ( ), and a cavity surface ( ). An annular groove ( ) is formed on a periphery of the body ( ). A region surrounded with the annular groove ( ) and a retaining plate forms a boundary flow path. An inner flow path ( ) is formed inside the body ( ). The inner flow path ( ) is linear. Both ends of the inner flow path ( ) are open on a peripheral surface of the body ( ) to form openings ( ) thereon. A heating medium flows into the boundary flow path and the inner flow path ( ) through a flow path formed on the retaining plate. Thereby, the temperature of the cavity die ( ) is adjusted.

Golf ball-shaping mold and cavity die

A method for manufacturing a golf ball, wherein a grinding tool and a ball to be ground are rotated so that their adjacent points move toward opposite directions. A grinding face of the grinding tool is arranged to be Japanese Industrial Standard grain size #80 to 300. The ball is rotated at 100 to 600 mm/s and the grinding tool is rotated at 2400 to 6900 mm/s, and relative velocity of the grinding tool and the ball is 2500 to 7500 mm/s. Flash formed on a parting line of the ball is thereby removed by the grinding face of the rotating grinding tool.

Growing community of inventors

Kobe, Japan

Masaaki Kikuchi