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  Golf ballUSPTO Application #: 20080045357Title: Golf ball Abstract: The present invention provides a golf ball having a resilient core made of rubber, a cover of one or more layer encasing the core, and at least one intermediate layer disposed between the core and the cover, wherein the cover is made primarily of polyurethane, the intermediate layer is made primarily of ionomer, and the core has a surface hardness which is higher than the material hardnesses of the cover and the intermediate layer. The golf ball is able to limit the distance of travel more than official balls currently in use and, in spite of being a limited-distance golf ball, imparts a relatively soft and good ball feel on impact, in addition to which it has an excellent scuff resistance and, by minimizing the extent of decrease in the distance traveled by the ball when hit with an iron, minimizes the effect on golf play by amateur golfers. (end of abstract)
Agent: Sughrue Mion, PLLC - Washington, DC, US Inventor: Hideo Watanabe USPTO Applicaton #: 20080045357 - Class: 473371 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080045357. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001]The present invention relates to a multi-piece golf ball having at least a three-layer construction composed of a core, an intermediate layer, and a cover. More specifically, it relates to a golf ball having a reduced distance of travel compared with official balls in current use. [0002]There are primarily two sets of Rules of Golf: one issued by the Royal and Ancient Golf Club of St. Andrews (R&A) and one issued by the United States Golf Association (USGA). Both are revised every few years to maintain the integrity of golf competition. Investigations on limiting the distance of golf balls in these Rules of Golf are slowly being carried out. [0003]Of the golf balls that have been disclosed to date, a few are golf balls which intentionally limit the flight performance or are designed to travel a short distance. For example, JP-A 60-194967 describes a short distance golf ball which includes a foam-molded thermoplastic resin polymer and filler material, and has a density gradient that increases along the ball radius from the center to the surface of the ball. [0004]However, although this golf ball does lower the ball initial velocity by decreasing the rebound resilience of the core material, the controllability and scuff resistance leave something to be desired. [0005]U.S. Pat. No. 5,209,485 teaches a golf ball which has a low rebound and reduced distance. However, this ball has a high hardness and thus an unpleasant feel on impact. [0006]U.S. Pat. No. 5,273,287 discloses a large-diameter golf ball having a diameter of 1.70 to 1.80 inches (43.18 to 45.72 mm), a weight of not more than 1.62 ounces, and a dimple surface coverage of at least 70% relative to the spherical surface of the ball. Yet, because the ball is larger than normal, it feels strange to the player. Also, the feel on impact has not been improved. Furthermore, manufacturing such large-diameter balls would require that major modifications be made to the design and production equipment for golf balls having a conventional ball diameter, and would adversely impact the productivity. [0007]U.S. Pat. No. 6,248,028 (corresponding Japanese application: JP-A 11-104270), U.S. Pat. No. 6,663,507 (corresponding Japanese application: 2004-049913), U.S. Pat. No. 6,814,676 (corresponding Japanese application: 2003-190330) and U.S. Pat. No. 6,592,470 (corresponding Japanese application: 2002-315848) disclose multi-piece solid golf balls obtained by forming the cover of a thermoplastic polyurethane elastomer, and forming between the core and cover an intermediate layer of a thermoplastic polyester elastomer and a high-resilience ionomer. These golf balls have excellent overall ball properties, including not only flight, but also feel when played, controllability, spin stability, scuff resistance and durability to repeated impact. Yet, such multi-piece solid golf balls are all aimed primarily at achieving superior flight properties, and will often not be suitable for the limited-distance standardized balls which will be required in the future. SUMMARY OF THE INVENTION [0008]It is therefore an object of the present invention to provide a golf ball in which the distance traveled can be reduced compared with official golf balls in current use and which, in spite of being a limited-distance ball, has a relatively soft and good feel on impact, has an excellent scuff resistance and minimizes the extent of the decrease in the distance traveled by the ball when hit with an iron, thus having little adverse effect on play by the amateur golfer. [0009]The inventor has found from extensive investigations that by using a polyurethane cover as the outermost layer (cover), using a rubber-based core at the center, and disposing therebetween an intermediate layer composed primarily of a relatively soft ionomer, the ball compression will be soft and the actual initial velocity when the ball is hit, particularly with a number one wood (W#1) at a high head speed, can be lowered considerably, enabling a distance-limiting effect to be achieved when the ball is hit by a professionals and other skilled players, particularly with a W#1. [0010]That is, the present invention is based on the discovery, from repeated and extensive investigations conducted on the construction of the distance-limited golf balls which are likely to be required in the near future according to the USGA and R&A criteria, that in golf balls having at least the following four conditions or features the distance traveled by the ball when hit at a high head speed by professionals and other skilled golfers can be limited, while yet enabling golf play to remain enjoyable when the ball is used by amateur golfers. The four conditions or features are: (1) that the golf ball have a three-layer construction composed of a resilient core, a cover and an intermediate layer disposed therebetween, (2) to impart the ball with a controllability which allows it to be used even by professionals and other skilled golfers, and enable the ball to manifest an excellent scuff resistance, it is effective for the cover to be made primarily of a polyurethane such as a thermoplastic polyurethane elastomer; (3) making the intermediate layer primarily of an ionomer, particularly a low-resilience ionomer, enables the effect of imparting a soft feel on impact that is acceptable to the golfer to be achieved; and (4) by forming the core to a surface hardness which is higher than the material hardnesses of the cover and the intermediate layer, in spite of the ball being distance-limited when hit with a W#1, the extent of the decrease in distance by the ball when hit with an iron can be minimized relative to the prior art, enabling golf play to remain enjoyable even when the ball is used by amateur golfers. [0011]Accordingly, the invention provides the following golf balls. [0012][1] A golf ball comprising a resilient core made of rubber, a cover of one or more layer encasing the core, and at least one intermediate layer disposed between the core and the cover, wherein the cover is made primarily of polyurethane, the intermediate layer is made primarily of ionomer, and the core has a surface hardness which is higher than the material hardnesses of the cover and the intermediate layer. [0013][2] The golf ball of [1], wherein, letting V be the initial velocity (m/s) of the ball as measured by a method set forth in the Rules of Golf using an initial velocity measuring apparatus of the same type as the USGA drum rotation-type initial velocity instrument and letting E be the deflection (mm) of the ball when subjected to compression from an initial load state of 98 N (10 kgf) to a final load of 1,275 N (130 kgf), the value of V/E is at most 28. [0014][3] The golf ball of [1], wherein the initial velocity V of the ball is at least 65 m/s but not more than 76.2 m/s. [0015][4] The golf ball of [1], wherein the deflection E of the ball is at least 2.8 mm. BRIEF DESCRIPTION OF THE DIAGRAMS [0016]FIG. 1 is a schematic sectional view of a golf ball (three-layer structure) according to one embodiment of the invention. [0017]FIG. 2 is a top view showing a dimple arrangement used in the same embodiment. DETAILED DESCRIPTION OF THE INVENTION [0018]The golf ball of the invention has a core, a cover of one or more layer which encases the core, and at least one intermediate layer which is disposed between the core and the cover. An example is the multi-piece solid golf ball G shown in FIG. 1. This golf ball has a multi-layer construction with a core 1 serving as the innermost layer, a cover 3 as the outermost layer, and a single intermediate layer 2 therebetween. The cover 3 has numerous dimples D formed on the outside surface thereof. The intermediate layer 2 and cover 3 may each be composed of a single layer or a plurality of layers. The construction of the inventive ball is not limited to that shown in FIG. 1. [0019]A detailed description is given below of the core, intermediate layer, cover and the dimples that are optionally formed. [0020]The core has a diameter of generally at least 35 mm but not more than 40 mm, preferably at least 36 mm but not more than 39 mm, and more preferably at least 37 mm but not more than 38 mm. If the core diameter is too much larger than the above range, the rebound becomes too high, which may result in an excessive distance when the ball is hit with a W#1. Conversely, if the core diameter is smaller than the above range, the spin rate may increase too much when hit with an iron, resulting in an excessive loss of distance. [0021]The core has a surface hardness as measured with a type D Durometer in accordance with ASTM D-2240 (referred to below as "Shore D hardness") of generally at least 45 but not more than 60, preferably at least 50 but not more than 58, and more preferably at least 52 but not more than 56. The core has a center hardness, expressed as the Shore D hardness, of generally at least 25 but not more than 50, preferably at least 30 but not more than 45, and more preferably at least 35 but not more than 40. If the surface hardness or center hardness of the core is too much smaller than the above range, the feel on impact may be too soft and the durability to cracking on repeated impact may worsen. On the other hand, if the value is too large, the feel on impact when a full shot is taken may be too hard and the spin rate may increase too much, resulting in a shorter than desirable distance. [0022]The difference between the two above hardnesses, i.e., the hardness difference obtained by subtracting the core center hardness from the core surface hardness, expressed in Shore D hardness units, is generally at least 10 but not more than 30, preferably at least 15 but not more than 25, and more preferably at least 17 but not more than 20. If this hardness difference is too small, the spin rate when hit with a W#1 may become too high, resulting in a trajectory that describes a high arc, so that the ball may be unduly subject to the influence of wind, making it more difficult to play golf. On the other hand, if the above hardness difference is too large, the rebound may become too low, as a result of which the distance traveled by the ball may decrease excessively not only when the ball is hit with a W#1 but even when it is hit with an iron, in addition to which the durability of the ball to repeated impact may become too poor. [0023]The deflection by the core, which is the measured amount of deformation by the core when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf), is generally at least 3.0 mm but not more than 5.5 mm, preferably at least 3.4 mm but not more than 5.0 mm, and more preferably at least 3.8 mm but not more than 4.5 mm. At a value which is too much higher than the above range, the feel may become too soft and the durability to cracking under repeated impact may worsen. Conversely, if the above value is too low, the feel on impact when a full shot is taken may be too hard and the ball may take on excessive spin, resulting in a shorter distance than desired when played with an iron. [0024]In the practice of the invention, it is critical that the core be formed so as to have a surface hardness which is higher than the subsequently described material hardnesses of the intermediate layer and the cover. This is done so that the ball does not fly too far due to a lower spin rate when the ball is hit with a W#1. The essential conditions in the invention are individually described below in the sections on the intermediate layer and the cover. Continue reading... Full patent description for Golf ball Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Golf ball patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Golf ball or other areas of interest. ### Previous Patent Application: Golf club head Next Patent Application: Adaptive golf ball Industry Class: Games using tangible projectile ### FreshPatents.com Support Thank you for viewing the Golf ball patent info. 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