Patent Application
20110319197
The present disclosure relates generally to the field of golf balls. Specifically, the present disclosure relates to a golf ball having a coating layer that is hydrophilic in such a manner as to cause the coating layer to swell.
The game of golf is an increasingly popular sport at both the amateur and professional levels. A wide range of technologies related to the manufacture and design of golf balls are known in the art. Such technologies have resulted in golf balls with a variety of play characteristics. A golfer may use different golf balls having different play characteristics depending on, for example, the golfer's preferences or the play conditions. For example, different dimple characteristics may affect the aerodynamic properties of the golf ball during flight, or a difference in the hardness of the cover layer may affect the rate of backspin.
A wide variety of dimple characteristics are known to affect the golf ball's aerodynamic properties, such as the dimple pattern, dimple shape and dimple depth. Ideally, the dimples should be designed to achieve the greatest possible flight distance by achieving reduced drag and increased lift. As is generally known, drag is the air resistance that opposes the golf ball's flight direction. Drag is caused by the difference between high air pressure in front of the golf ball and low air pressure in the golf ball's wake. The dimples cause a thin boundary layer of air bordering the golf ball's outer surface to flow in a turbulent manner. The turbulent boundary layer moves the separation point backward, so that the boundary layer stays adjacent to the golf ball further along the ball's outer surface. As a result, the area of the wake is reduced and the pressure behind the ball is increased. Drag is thereby reduced, and the golf ball achieves increased flight distance.
As is also generally known, lift is an upward force on the golf ball that is created by a difference in pressure between the top of the ball and the bottom of the ball. Due to the golf ball's backspin, the top of the ball moves in the same direction as the airflow, which moves the air separation point to a location further backward. Conversely, the bottom of the ball moves against the airflow, which moves the separation point forward. This asymmetrical separation creates an arch in the flow pattern, whereby air that flows over the top of the ball moves faster than the air that flows along the bottom of the ball. As a result, the air above the ball is at a lower pressure than the air underneath the ball. This pressure difference results in the overall force, lift, which is exerted upwardly on the ball. Lift therefore causes the golf ball to achieve increase flight distance, as the upward lift force keeps the golf ball in the air for a longer period of time.
Dimple depth, in particular, can significantly affect the aerodynamics of the golf ball's flight. As is generally known, shallower dimples tends to result in the golf ball rising higher during flight. Conversely, the deeper the golf ball dimples, the lower the golf ball's flight. It is believed that these tendencies are caused by decreased lift due to greater turbulence of the air inside deeper dimples, although many different aerodynamic phenomenon likely come into play.
Similarly, the hardness of the golf ball's outer layer(s) can also significantly affect a golf ball's play characteristics. Generally, a golf ball with a harder cover layer will achieve reduced spin, but will achieve greater distances. A golf ball with a harder cover layer will therefore be better for drives, but more difficult to control on shorter shots. On the other hand, a golf ball with a softer cover will generally experience more spin and therefore be easier to control and stop on the green, but will lack distance off the tee.
Consequently, a golfer may desire to use a golf ball having different dimple depths or different cover layer hardness, depending on a variety of factors. For example, weather conditions or the golfer's athletic abilities may affect whether shallow dimples or deeper dimples, or a harder cover layer or a softer cover layer, will better achieve the desired play characteristics.
In particular, wet play conditions due to rainy weather can significantly affect a golf ball's play characteristics. During wet weather, the presence of water on the surface of the golf ball decreases friction between the golf club face and the golf ball. This decreased friction causes the golf ball to experience a lower trajectory flight path, and also decreases spin on the ball. This decreased spin reduces the amount of control the golfer has over the golf ball's flight path and landing conditions. Wet weather conditions therefore present specific challenges to achieving optimal golf ball play characteristics.
Amateur golfers generally prefer to minimize the costs of purchasing new golf balls. However, a golfer may be required to purchase several sets of golf balls in order to achieve different play characteristics. Namely, a golfer may be required to purchase one set of golf balls for use in normal weather conditions and another separate set of golf balls for use in wet weather conditions. The need to purchase, store and carry several sets of golf balls in order to achieve a variety of play characteristics presents an inconvenience to the golfer, as well as increased costs.
Therefore, there is a need in the art for a golf ball and method that addresses the shortcomings of the prior art discussed above.
In one aspect, the present disclosure provides a golf ball comprising a core; a cover layer substantially surrounding the core, the cover layer including at least one dimple, and at least one land area adjacent to the dimple; and a coating layer overlapping at least a portion of the cover layer; wherein the coating layer is comprised of a hydrophilic water-swellable material, such that the coating layer is configured to undergo a physical change from a dry state to a wet state upon exposure to water.
In another aspect the present disclosure provides a golf ball comprising a core; a cover layer substantially surrounding the core, the cover layer including at least one dimple, and at least one land area adjacent to the dimple; and a coating layer overlapping at least a dimple portion of the cover layer; wherein the coating layer is comprised of a hydrophilic water-swellable material, such that the coating layer is configured to physically change from a dry state to a wet state upon exposure to water; the dry state is associated with a first a first dimple depth, the wet state is associated with a second dimple depth, wherein the second dimple depth is less than the first dimple depth; and the dry state is associated with the coating layer having a first hardness, the wet state is associated with the coating layer having a second hardness, wherein the second hardness is softer than the first hardness.
In yet another aspect, the present disclosure provides a method of manufacturing a golf ball, the method comprising (1) a step of receiving a golf ball core substantially surrounded by a cover layer, the cover layer having at least one dimple and at least one land area adjacent to the dimple; (2) a step of coating at least a dimple portion of the cover layer with a coating layer, the coating layer being comprised of a hydrophilic water-swellable material such that the coating layer is configured to physically change from a dry state to a wet state upon exposure to water; wherein the dry state is associated with a first a first dimple depth, the wet state is associated with a second dimple depth, and the second dimple depth is less than the first dimple depth; and the dry state is associated with the coating layer having a first hardness, the wet state is associated with the coating layer having a second hardness, and the second hardness is softer than the first hardness.
Other systems, methods, features and advantages of the invention will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the invention, and be protected by the following claims.
The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.
Generally, the present disclosure relates to a golf ball having a coating layer comprised of a hydrophilic, water-swellable material. Specifically, in embodiments, at least one of the dimples is coated with the hydrophilic water-swellable material, and the coating physically changes upon exposure to water. The physical change may be, for example, a change in dimple depth, or a change in the hardness of the coating layer. The physical change may allow the golf ball to compensate for undesirable play characteristics that would otherwise occur in wet weather conditions.
Golf ball 100 includes an outer coating layer 110. In the embodiment shown, coating layer 110 overlaps substantially the entirety of a cover layer 108.
The plurality of dimples 102 may generally be arranged on cover layer 108 in any pattern, as may be known in the art of golf balls. Various known dimple packing patterns are known in the art. Dimples 102 may generally be of any shape, such as circular, triangular, or multi-sided. Dimples 102 may be of uniform shape and size, or the dimple pattern may be made up of two or more different types of dimples having (for example) different sizes or different shapes. At least one land area 104 is a part of cover layer 108 that separates at least two dimples 102 and that is not indented or otherwise part of a dimple. Generally, land area 104 is the “ridge” or “fret” between adjoining dimples 102. Golf ball 100 may include one continuous land area 104 across the entire cover layer, as is shown in
As shown in
In the embodiment shown in
Dimple 102 has a first dimple depth 202 in the top portion of
As shown in the lower portion of
In the particular embodiment shown, the land portions 112 and the dimple portion 114 of coating layer 110 have the same linear swelling ratio. The linear swelling ratio, also referred to in the art as the linear swelling rate, is the ratio of the change in thickness to the original thickness, namely the ratio of distance 226 to distance 206, and the ratio of distance 222 to distance 204. In other embodiments, discussed below, the linear swelling ratios of the land portions and the dimple portion may be different.
More specifically, in particular embodiments, the expansion that occurs when the golf ball transitions from the dry state to the wet state may cause the dimple depth to change. In other words, the dry state may be associated with first dimple depth 202 while the wet state may be associated with a second dimple depth 218. Second dimple depth 218 is measured between wet state topmost land surface and wet state dimple bottom surface 216. Generally, second dimple depth 218 may be any dimple depth that is different from first dimple depth 202. However, in the particular embodiment shown, second dimple depth 218 is less than first dimple depth 202. In certain embodiments, second dimple depth 218 may be less than first dimple depth 202 by a specific percentage. For example, second dimple depth 218 may be 75% or less than dimple depth 202, or second dimple depth 218 may be 50% or less than first dimple depth 202, or second dimple depth 218 may be 33% or less than first dimple depth 202.
In the particular embodiment shown in
With reference back to
In other embodiments, as shown in
In addition to the changes discussed above, coating layer 110 may undergo other physical changes when transitioning from the dry state to the wet state. For example, coating layer 110 may change hardness. The dry state may be associated with coating layer 110 having a first hardness, while the wet state may be associated with coating layer 110 having a second hardness. The first hardness and the second hardness may generally be of any hardness value commonly associated with golf ball outer layers, for example about 40 to about 80 on the Shore D scale. The first hardness and the second hardness may be different hardness values. In particular embodiments, the second hardness is softer (i.e. less hard) then the first hardness. In some embodiments, the second hardness is at least five units on the Shore D scale softer than the first hardness. In other embodiments, the second hardness is at least 10 units on the Shore D scale softer than the first hardness.
Coating layer 110 may be comprised of a hydrophilic water-swellable material. A hydrophilic water-swellable material may be any material that includes polar charges on the molecules therein capable of forming hydrogen bonds with water, and absorbs water so as to physically change dimension by swelling. The hydrophilic water-swellable material undergoes a physical change from the dry state to the wet state upon exposure to water. The nature of the hydrophilic water-swellable material is discussed in further detail below.
The embodiment of
Accordingly, when golf ball 300 transitions to the wet state, dimple portion 314 of coating layer 310 may swell a larger distance than land portions 312 swell. Specifically, dimple portion 314 swells from thickness 404 in the dry state to thickness 420 in the wet state. The difference between thickness 404 and thickness 420 is distance 422, as shown. On the other hand, land portions 312 swell from thickness 406 in the dry state to thickness 424 in the wet state. The difference between thickness 406 and thickness 424 is distance 426. In the particular embodiment shown, distance 422 may be larger than distance 426. The linear swelling ratio of dimple portion 314 is thus the ratio of distance 422 to distance 404, which is much larger than the linear swelling ratio of land portion 312 as defined by the ratio of distance 426 to distance 406. Therefore, dimple 302 has a first dimple depth 402 (as measured between dry state dimple bottom surface 410 and line 408 at dimple center 400) when in the dry state, and a second dimple depth 418 (as measured between wet state dimple bottom surface 416 and line 414, at center of dimple 400) when in the wet state. In the embodiment shown, second dimple depth 418 may be less than first dimple depth 402.
As in other embodiments discussed above, coating layer 510 may exist in a dry state as shown in the upper half of
Coating layer 510 may then undergo a physical change from the dry state to a wet state, as shown in the lower half of
In addition to the change in dimple depth discussed above, the embodiment shown in
In this embodiment, coating layer 710 has a uniform thickness and may be made of a uniform continuous material (thereby having a constant swelling ratio). As a result, the physical change from the dry state to the wet state does not change the dimple depth. The dry state is associated with first dimple depth 802, as measured between dry state dimple bottom surface 810 and line 808 at dimple center axis 800. The wet state is associated with second dimple depth 818, as measured between wet state dimple bottom surface 816 and line 814 defined by top surface of land areas 704. In this embodiment, distance 826 by which land portions 712 of coating layer 710 swell is the same as distance 822 by which dimple portion 714 of coating layer 710 swells. Therefore, first dimple depth 802 and second dimple depth 818 are substantially the same, as are all of thicknesses 804 and 806 (in the dry state) and thicknesses 820 and 824 (in the wet state).
Although this embodiment is not configured to change dimple depth, coating layer 710 may nonetheless undergo a desired change in hardness. The transition from the dry state to the wet state may, for example, uniformly decrease the hardness of coating layer 710. As discussed above, decreased hardness may increase the rate of spin and the degree of control that golf ball 700 experiences when hit by a golf club face.
In
In specific embodiments, the physical change from the dry state to the wet state may be reversible. Specifically, water molecules may enter into coating layer 110 through pores 912, and exit therefrom as well. Pores 912 are merely representative of the hydrophilic water-swellable material being porous, and are not to scale. Coating layer 110 may therefore transition from the dry state to the wet state upon exposure to water, and back again. The transition from the wet state back to the dry state may occur (for example) after a predetermined time period during which coating layer 110 is not exposed to water, or the transition may be effected by a specific stimulus such as heating.
Hydrophilic water-swellable polymer materials are generally known in the art of polymer chemistry. Information regarding hydrophilic water-swellable polymer materials may be found in, for example. U.S. Pat. No. 6,787,487, titled “Water Vapor-permeable and Waterproof Material and Method for Manufacturing the Same” and issued Sep. 7, 2004, to Takeda et al, the disclosure of which is hereby incorporated by reference in its entirety. Additionally, U.S. Pat. No. 5,266,669, titled “Softening Non-swelling Polyurethane” and issued Nov. 30, 1993 to Onwunaka, et al. also provides relevant information regarding hydrophilic water-swellable polymer materials, although the specific polymers disclosed therein are non-swelling. The disclosure of U.S. Pat. No. 5,266,669 is hereby incorporated in its entirety.
In specific embodiments, the hydrophilic water-swellable material is a thermoplastic polyurethane (TPU). Although thermoplastic polyurethane materials are known to be used in golf ball construction, the thermoplastic polyurethane used to form coating layer 110 must be hydrophilic and water-swellable, properties for which the polymer must specifically be manufactured.
Suitable hydrophilic water-swellable thermoplastic polyurethanes are disclosed in, for example, U.S. Pat. No. 5,334,691, titled “Hydrophilic Polyurethanes of Improved Strength,” issued Aug. 2, 1994, to Gould, et al., the disclosure of which is hereby incorporated by reference in its entirety.
Other suitable hydrophilic water-swellable thermoplastic polyurethanes are disclosed in, for example, U.S. Pat. No. 6,017,625, titled “Water-absorptive polyurethane fiber and method of producing the same” issued Jan. 25, 2000 to Sato, et al., the disclosure of which is hereby incorporated by reference in its entirety.
Finally, other suitable hydrophilic water-swellable thermoplastic polyurethanes are disclosed in, for example, U.S. Patent Application Publication No. 2009/0291120, titled “Hydrophilic Polyurethane Compositions,” published Nov. 26, 2009, to Tuominen et al., the disclosure of which is hereby incorporated by reference in its entirety.
The above reference are merely exemplary, and persons having ordinary skill in the art may substitute other known hydrophilic water-swellable thermoplastic polyurethane compositions, as may be suitable for the construction and purposes of the golf ball coating layers disclosed herein.
The present disclosure also provides a method of manufacturing a golf ball. Generally, the method of manufacturing a golf ball includes (1) a step of receiving a golf ball core substantially surrounded by a cover layer, the cover layer having at least one dimple and at least one land area adjacent to the dimple; and (2) a step of coating at least a dimple portion of the cover layer with a coating layer, the coating layer being comprised of a hydrophilic water-swellable material such that the coating layer is configured to physically change from a dry state to a wet state upon exposure to water.
The method produces a golf ball configured to physically change from a dry state to a wet state upon exposure to water. Specifically, the method produces a golf ball wherein the dry state is associated with a first a first dimple depth, the wet state is associated with a second dimple depth, and the second dimple depth is less than the first dimple depth; and wherein the dry state is associated with the coating layer having a first hardness, the wet state is associated with the coating layer having a second hardness, the second hardness being softer than the first hardness.
As has been discussed above with respect to the various embodiments of
In contrast, golf ball 100 in the wet state compensates for the reduced friction by having a reduced dimple depth and a softer outermost layer. The reduced dimple depth causes golf ball 100 to experience a flight path 1006 that is otherwise higher than the reduced friction would otherwise cause it to have. Furthermore, the softer outermost layer causes golf ball 100 to experience more spin than the reduced friction would otherwise cause, resulting in golf ball 100 having better control upon landing. Accordingly, the present disclosure provides golf balls which may be used equally well in both fair weather conditions and wet weather conditions.
Commonly-owned U.S. Pat. No. ______, currently application serial no. [Attorney Docket No. 72-1100], titled “Golf Ball with Changeable Dimples”, and filed on even date herewith, discloses additional features of a golf ball with varying outer diameters of layers that may affect the dimple depth, and the disclosure of which is hereby incorporated in its entirety.
While various embodiments of the invention have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.
