Golf ball with cover layer having zones of differing materials

Generally disclosed is a golf ball having a core and a cover layer. The cover layer includes areas that are hard corresponding to the dimples, and areas that are soft corresponding to the land between the dimples. The cover layer may comprise two different materials, such as polyurethane and ionomer, that are laterally adjacent to each other in the cover layer. Alternatively, the cover layer may be selectively coated with a coating material having a different hardness, such as polyurethane or ionomer. As a result of the arrangement of the hard dimples and the soft land, the golf ball achieves reduced spin, and greater distances, when struck with a larger force (such as during a dive) while also achieving increased spin, and better control, when struck with a smaller force (such as during a chip).

BACKGROUND

The present invention relates generally to a golf ball, and a method of manufacturing the golf ball. In particular, a cover layer on the golf ball includes areas having a higher hardness and areas having a lower hardness.

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. For example, different golf balls are manufactured and marketed to players having different golfing abilities, such as different swing speeds.

Similarly, a golfer may use different golf balls having different play characteristics depending on the golfer's preferences. For example, different dimple patterns 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. With regard to hardness in particular, a golfer may choose to use a golf ball having a cover layer and/or a core that is harder or softer. A golf ball with a harder cover layer will generally achieve reduced driver spin, and achieve greater distances. However, a harder cover layer will generally cause a lower rate of spin, such that the golf ball will 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.

A wide range of golf balls having a variety of hardness characteristics are known in the art. Generally, the hardness of a golf ball is determined by the chemical composition and physical arrangement of the various layers making up the golf ball. Accordingly, a number of different golf ball materials are mixed and matched in various combinations and arrangements to create golf balls having different hardness values and different hardness profiles.

However, designing golf balls to achieve desired hardness characteristics suffers from at least several difficulties. Generally, the construction of known golf balls requires that a wide range of design variables such as layer arrangement, materials used in each layer, and layer thickness be balanced against each other. Changes to any of these variables may therefore improve a desired hardness only at the expense of other play characteristics. Additionally, materials costs and design costs associated with known golf ball constructions may unduly increase the cost of the golf ball to the end consumer. Perhaps most importantly, known golf balls generally cannot simultaneously achieve the advantageous play characteristics associated with high cover hardness (greater distances) while also achieving the advantageous play characteristics associated with low cover hardness (greater spin).

Therefore, there is a need in the art for a system and method that addresses the shortcomings of the prior art discussed above.

SUMMARY

Generally, this disclosure provides golf balls having a cover layer where certain portions of the cover layer are made from an ionomer material, and other portions of the cover layer are made from a polyurethane material. The different materials may have different physical properties, such as hardness or compressibility, that result in the golf ball exhibiting various play characteristics.

In one aspect, this disclosure provides a golf ball comprising: a core; and a cover layer, the cover layer substantially surrounding the core and including a plurality of dimples and at least one land area separating the dimples; wherein the cover layer includes a first portion, the first portion of the cover layer having a first hardness, and a second portion, the second portion of the cover layer having a second hardness; the first portion and the second portion being laterally adjacent to each other within the cover layer; the first portion comprising a polyurethane material; the second portion comprising a ionomer material; and the first hardness is different from the second hardness.

In another aspect, this disclosure provides a golf ball comprising: a core; and a cover layer substantially surrounding the core, the cover layer being formed of a first material having a first hardness, and the cover layer having a plurality of dimples and at least one land area thereon; the plurality of dimples being arranged on the cover layer in a first pattern; the at least one land area being arranged on the cover layer in a second pattern, the first pattern and the second pattern being non-overlapping patterns; wherein the cover layer is coated with a second material, the second material having a second hardness, such that the coating material overlaps at least a portion of one of the first pattern and the second pattern but substantially does not overlap the other of the first pattern and the second pattern; the second hardness is different from the first hardness; the first material comprises a material that is selected from the group consisting of: an ionomer material, and a polyurethane material; the second material comprises a material that is selected from the group consisting of: an ionomer material, and a polyurethane material; and the second material is different from the first material.

In yet another aspect, this disclosure provides a golf ball comprising: a core; a cover layer substantially surrounding the core; the cover layer being formed of a cover material; the cover material comprising a material that is selected from the group consisting of: an ionomer material, and a polyurethane material; the cover material having a first hardness and a first compressibility; the cover layer including one or more grooves extending radially inward from an outer surface of the cover layer; and a groove material disposed within the one or more grooves; the groove material having a second hardness and a second compressibility; wherein the groove material comprises a material that is selected from the group consisting of: an ionomer material, and a polyurethane material; the groove material being different from the cover material; the first hardness being different from the second hardness, and the first compressibility is different from the second compressibility.

DETAILED DESCRIPTION

Generally, the present disclosure relates to a golf ball having areas on the cover layer that are relatively hard and areas on the cover layer that are relatively soft. The hard areas may be made of a ionomer material, and the soft areas may be made of a polyurethane material.

The relatively hard areas may correspond to at least some of the dimples in the cover layer, and the relatively soft areas may correspond to at least part of at least one land area between the dimples. Alternatively, the hard areas (or soft areas) may be configured in one or more grooves in the otherwise soft (or hard, respectively) cover layer.

As a result of these arrangements, the golf ball may experience a lower rate of spin when struck with a larger force (such as during a drive) while also experiencing a higher rate of spin and increased control when struck with a smaller force (such as during a chip). The golf ball therefore achieves improved play characteristics associated with harder cover layers (such as longer distance) during drives, while also achieving improved play characteristics associated with softer cover layers (such as higher spin) during short shots.

This disclosure further relates to methods of manufacturing such a golf ball.

FIG. 1shows an exemplary golf ball100in accordance with this disclosure. Golf ball100is made up of a cover layer having thereon a plurality of dimples104and at least one land area106. Golf ball100may generally be any type of golf ball having a core and a cover layer substantially surrounding the core. For example, golf ball100may be of a two-piece construction, having only a core and a cover layer, or golf ball100may have one or more intermediate layers located between the core and the cover layer. Except as otherwise herein discussed, each layer of golf ball100may be formed of any material or construction as is generally known in the art of golf ball manufacturing. For example, various layers of golf ball100may be comprised of rubber, rubber composites, thermoplastic polyurethane, highly-neutralized polymers, ionomers, and other polymer materials as are known in the art of golf ball manufacturing.

The plurality of dimples104may generally be arranged on the cover layer in any pattern, as may be known in the art of golf balls. Various known dimple packing patterns are known in the art. Dimples104may generally be of any shape, such as circular, triangular, or multi-sided. Dimples104may 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 area106is a part of the cover layer that separates at least two dimples104and that is not indented or otherwise part of a dimple. Generally, land area106is the “ridge” or “fret” between adjoining dimples104. Golf ball100may include one continuous land area106across the entire cover layer, as is shown inFIG. 1, or a plurality of separate land areas between the plurality of dimples104.

As shown inFIG. 1, golf ball100undergoes selective treatment of land area106. In the embodiment shown inFIG. 1, the selective treatment changes the entirety of land area106from a first state into land area108in a second state. In other embodiments, the selective treatment may be applied to a portion of land area106. This selective treatment may comprise a heating step, discussed in further detail below.

FIG. 2shows a cross section of golf ball100, before and after the selective treatment. In particular, golf ball100includes core202and cover layer200. Cover layer200includes dimples104and land areas106thereon. Prior to the selective treatment, cover layer200is made up of several sections204having at least one dimple104thereon, and several sections206having at least a part of at least one land area106forming the top boundary thereof. After the selective treatment, the sections206having a part of at least one land area106thereon are changed into a second state208as discussed above with respect to land areas in a second state108.

After the selective treatment, cover layer200generally includes a first portion having a first hardness, and a second portion having a second hardness. The first portion generally includes those sections204of cover layer200having at least one dimple104thereon. The first portion may include all sections204of cover layer200having dimples104thereon, or the first portion may include some of the sections204but not others. In other words, the first portion as a whole may include all of the dimples104thereon, or a subset of fewer than all of the plurality of dimples104thereon. Generally, the first portion of cover layer200can be made up of any number and arrangement of the sections204. Similarly, the second portion of cover layer200generally includes those sections208having at least a part of at least one land area108thereon. The second portion may also be made up of all sections208, or fewer than all of the sections208. In other words, the second portion as a whole may include the entirety of all of the land area(s) thereon, or may include less than the entirety of all of the land area(s) thereon.

Either of the first or the second portion may extend through the entire cross-sectional thickness of the cover layer200, as shown inFIG. 2, or only though a portion of the cross section of cover layer200, as shown inFIG. 5. Referring again toFIG. 2, specifically, the second portion may extend from an outer surface250of cover layer200to an inner surface252of cover layer200. Alternatively, as shown inFIG. 5, the second portion may extend from an outer surface250of the cover layer200to an intermediate point254between the outer surface250and the inner surface252of cover layer200.

Each of the first portion and the second portions are non-overlapping portions of a continuous cover layer material. Namely, as shown inFIG. 2, the portions204and the portions206are defined by the dimples104and the land106but are otherwise parts of the same continuous cover layer200. In particular embodiments, the first portion and the second portion of cover layer200have the same material composition, i.e. there is no difference in the chemical composition of the materials making up the first portion and the second portion.

The first hardness, associated with the first portion of cover layer200, is higher than the second hardness, associated with the second portion of cover layer200. Accordingly, the portions of cover layer200associated with dimples104are generally relatively hard, while the portions of cover layer200associated with land areas108are generally relatively soft. The degree of difference in hardness between the first portion and the second portion may be any non-trivial difference in hardness. In certain embodiments, the hardness of the first portion may be at least about 3 units on the Shore D scale harder than the hardness of the second portion. In other embodiments, the first portion may be at least about 5 units on the Shore D scale harder than the second portion.

Generally, the present disclosure encompasses two or more zones of differing hardness of the cover layer. For example, a golf ball may have three zones of hardness. In such an embodiment, cover layer200includes a third portion. The first portion, the second portion, and the third portion are all non-overlapping portions of the continuous cover layer material.

For example, a second embodiment of a dimple pattern that may be used in conjunction with the present disclosure is shown inFIG. 3. In this embodiment, cover layer200again includes dimples104and land areas106separating at least two dimples104. Here, each dimple104is made up of a center dimple section152and a radial edge dimple section150. Cover layer200includes portions206underlying the land areas (as in the embodiment shown inFIG. 2, discussed above), portions214underlying radial edge dimple sections150, and portions216underlying center dimple sections152. Portions214and216are collectively equivalent to portion204in the embodiment shown inFIG. 2, discussed above.

This cover layer200as shown inFIG. 3may then undergo selective treatment so as to change the hardness of certain portions of the cover layer. Specifically, first, portions206may undergo selective treatment so as to change into portions208in a second state. Portions208thereby achieve a second hardness, as discussed above. Furthermore, portions216also undergo selective treatment so as to change into portions218in a second state. Portions218have a third hardness. The third hardness may be different from or equal to the second hardness. Finally, portions214may remain unchanged, and have a fourth hardness. The fourth hardness may be greater than the third hardness. Accordingly, after undergoing selective treatment, cover layer200achieves three zones of hardness: land areas106having a second hardness, center dimple sections152having a third hardness, and radial edge dimple section150having a fourth hardness. In this case, the “first portion” discussed above includes at least one dimple104having a center dimple section152and a radial edge dimple section150, and the “first hardness” discussed above may be considered as the effective average of the third hardness and the fourth hardness based on the relative proportions of center dimple section152and radial edge dimple section150in the dimple104.

Cover layer200is generally made of any material that can change in hardness in response to a selective treatment. In particular embodiments where the selective treatment comprises heating, cover layer200may comprise a phase transition material as described in U.S. Patent Application Publication No. 2008/0081710 (hereinafter referred to as “the '710 Publication”), the disclosure of which is hereby incorporated in its entirety. Specifically, the phase transition material described in the '710 Publication is an acid copolymer that comprises copolymerized residues of at least one alpha olefin having from two to six carbon atoms and copolymerized residues of at least one α,β-ethylenically unsaturated carboxylic acid having from 3 to 8 carbon atoms.

As described in the '710 Publication, this phase transition material changes hardness in response to heating. Specifically, heat energy decreases the hardness by disrupting the material's secondary crystal structure. As is generally known in the arts of polymer science, the hardness of a semi-crystalline polymer material can be proportional to the degree of crystallinity of the polymer material. The degree of crystallinity is the amount of the material that is in a crystalline phase, as compared to the amount of the material that is in an amorphous phase. The crystalline phase is generally harder than the amorphous phase, due to the close-packing crystal structure of the polymer molecules therein.

Therefore, golf ball100may be heated in a heating device300as shown inFIG. 4in order to achieve the desired difference in hardness. The heating device300is fully described in U.S. Pat. No. 7,926,645, entitled Device for Heating a Golf Ball, and filed on Oct. 23, 2009, the disclosure of which is hereby incorporated by reference in its entirety. Heating device300is held by a user's hand302and moved, as shown, such that heating surface106is brought into contact with the golf ball100.

Specifically, as shown inFIG. 5, cover layer200may be selectively heated by a heating element306in order to achieve the desired difference in hardness. Specifically, heating element306may be brought into contact with the land areas106of cover layer200. The sections of cover layer200closest to the surface of land areas106touching heating element306are therefore heated. These sections form the second portion of the cover layer, as described above. In the embodiment described here, and as shown inFIG. 5, the second portion extends from the outer surface250of the cover layer200to an intermediate point254between the outer surface250and the inner surface252, depending on the nature and extent of the heat applied by the heating element306. As a result of the selective heating applied to the land areas106, the first portion of cover layer200(encompassing untreated sections204) has a first hardness that is higher than the second hardness of the second portion (encompassing treated sections208). Specifically, the secondary crystal structure of the second portion has been disrupted, and so the degree of crystallinity of the first portion is higher than the degree of crystallinity of the second portion.

AlthoughFIG. 5only shows this selective heating process being applied to a particular cross section of the cover layer200, this selective heating process may be applied to the entire surface of golf ball100, such that all land areas106are heated. Alternatively, the selective heating process may be applied to certain land areas106on different locations on golf ball100, but not others, as may be desired. In either case, the second portion of cover layer200will encompass only those portions of cover layer200that are heated, and therefore have a difference in hardness from the first portion of cover layer200.

In another embodiment, the cover layer220may comprise a semi-crystalline thermoplastic material. Methods for changing the hardness of semi-crystalline thermoplastic materials are fully described in U.S. Pat. No. 8,602,914, entitled Methods and Systems for Customizing a Golf Ball, and filed on Jan. 20, 2010, the disclosure of which is hereby incorporated by reference in its entirety.

Specifically, as is shown inFIG. 6, heating element308may be used to heat sections210of the cover layer220associated with the dimples104. In accordance with the methods described in the '493 application, these sections210may be heated to increase the movement of the polymer molecules in the semi-crystalline thermoplastic material, and subsequently slowly cooled such that the degree of crystallinity in these sections210increases. Sections210therefore collectively make up the first portion of cover layer200, as described above, and have a hardness that is higher than the un-heated sections212collectively making up the section portion. In such embodiments, again, the degree of crystallinity of the first portion of cover layer200is higher than the degree of crystallinity of the second portion. In other words, the first portion has a first degree of crystallinity, and the second portion has a second degree of crystallinity, where the first degree of crystallinity is higher than the second degree of crystallinity.

Heating element306or heating element308, as used in the methods described above, may generally be any heating mechanism that is capable of selectively heating the desired portions of the cover layer. In a particular embodiment, as mentioned above and shown inFIG. 4, the heating element may be a component of the heating apparatus described fully in U.S. patent application Ser. No. 12/304,830 (hereinafter referred to as “the '830 application”). In such embodiments, the heating element306or the heating element308may be the internal heating surface as described in the '830 application. Similarly, the heating element backing304, shown inFIGS. 5 and 6, may be the external housing described in the '830 application. The device described in the '830 application allows a consumer to create a desired difference in hardness in accordance with the present disclosure through the use of a particular pattern on the internal heating surface.

FIGS. 7-10show a second category of embodiments within the scope of this disclosure. InFIGS. 7-10, the golf ball cover layer comprises two different materials. Generally, one of these materials may be an ionomer material, and the other may be a polyurethane material. A first portion of the golf ball cover layer may be made of the ionomer material, while a second portion of the golf ball cover layer may be made of the polyurethane material.

In particular,FIG. 7shows a first embodiment of a cover layer400that is made up of two different materials. Cover layer400includes dimples104and land areas108, as discussed above with respect to other embodiments. As shown inFIG. 7, portions404of cover layer400that correspond to dimples104may be made from a first material. Portions408of cover layer400that correspond to land areas108may be then made from a second material.

In the embodiment shown inFIG. 7, each material extends the full thickness of cover layer400. That is, each material comprises the entire cross section of cover layer400from inner surface452to outer surface450. Furthermore, as shown, each material makes up the entire lateral width of the dimple104or land area108. For example, portion404made of the first material extends laterally from boundary470at the edge of dimple104to the other corresponding edge of dimple104. Therefore, portions404made of the first material and portions408made of the second material are laterally adjacent to each other. In the particular embodiment shown inFIG. 7, portions404and408are entirely laterally adjacent to each other, and do not overlap each other in any manner.

As mentioned, portions404may be comprised of a first material, while portions408may be comprised of a second material. In embodiments, the first material may be a polyurethane material or an ionomer material, while the second material may also be a polyurethane material or an ionomer material, where the first material and the second material are different materials. For example, the first material may be a polyurethane while the second material is an ionomer. Alternatively, the first material may be an ionomer while the second material is a polyurethane.

Polyurethane materials are known to be used in golf ball construction. Generally, polyurethane polymers are formed from the reaction of a long-chain polyol and a polyisocyanate. Polyurethane includes thermosetting urethane and thermoplastic polyurethanes. A wide range of polyurethane formulations are known to a person having ordinary skill in the art of golf ball manufacturing. Example representative polyurethane compositions are disclosed in: U.S. Pat. No. 6,392,002 to Wu, entitled “Urethane Golf Ball” and issued on May 21, 2002; U.S. Pat. No. 6,835,793 to Yokota et al., entitled “Golf Ball having a Polyurethane Cover” and issued on Dec. 2, 2004; and U.S. Pat. No. 6,422,954 to Dewanjee, entitled “Golf Ball having a Polyurethane Cover” and issued on Jul. 23, 2002. The disclosures of these three U.S. patents are hereby incorporated by reference.

Ionomer materials are also known to be used in golf ball construction. Generally, ionomer polymers include any polymer formed from both an electrically neutral monomer and an ionized monomer. Ionomer polymers that are commonly used in golf ball construction are often formed from an short-chain alkene and an organic acid. Ionomer materials include the category of materials referred to as high acid ionomers, and includes the category of materials referred to as highly-neutralized polymers, among many others. Example representative ionomer materials are disclosed in: U.S. Pat. No. 5,994,472 to Egashira et al., entitled “Ionomer Covered Golf Ball” and issued on Nov. 20, 1999; U.S. Pat. No. 5,873,796 to Cavallaro et al., entitled “Multi-Layer Golf Ball Comprising a Cover of Ionomer Blends” and issued on Feb. 23, 1999; and U.S. Pat. No. 6,433,094 to Nesbitt et al., entitled “Golf Ball Covers Containing High Acid Ionomers” and issued on Aug. 13, 2002. The disclosures of these three U.S. patents are hereby incorporated by reference. In particular, commonly used ionomer materials include the Surlyn® line of materials commercially available from E.I. du Pont de Nemours and Company.

Polyurethane materials and ionomer materials may have different physical properties, and this difference in physical properties may be used in the construction of the present golf ball to achieve desired play characteristics. In particular, polyurethane materials and ionomer materials may have different hardnesses. Hardness is generally measure in accordance with ASTM D-2240, and is given in units of Shore D unless otherwise noted.

Generally, polyurethane materials used in golf ball construction may have a hardness of from about 20 to about 60 Shore D. Ionomer materials used in golf ball construction may have a hardness of from about 40 to about 80 Shore D. Generally, the two materials used should have different hardness values. Typically, in some embodiments, polyurethane materials used in golf ball construction have a lower hardness than ionomer materials used in golf ball construction.

The degree of difference in hardness between the polyurethane material and the ionomer material may be any non-trivial difference in hardness. In certain embodiments, the hardness of the ionomer material may be at least about 3 units on the Shore D scale harder than the hardness of the polyurethane material. In other embodiments, the ionomer material may be at least about 5 units on the Shore D scale harder than the polyurethane material, or at least about 10 units, or at least about 15 units.

FIG. 8shows a second embodiment of a cover layer that is comprised of two different materials. Here, cover layer500includes portions504that correspond to a part of each dimple104. Portions504may be comprised of a first material. Cover layer500also includes portions508that correspond to land areas108and part of each dimple104. Portions5008may be comprised of a second material. Portions508are wider than portions408, as shown inFIG. 7. Portions508and portions504are laterally adjacent to each other, at boundary570. In this embodiment, boundary570is located in dimple104. In contrast, boundary470in cover layer400is located at the interface between dimple104and land108. Each of portions504and portions508may extend through the entire thickness of cover layer500, from bottom surface552to top surface550.

FIG. 9shows a third embodiment of a cover layer that is comprised of two different materials. Cover layer600may include portions604that correspond to each dimple104. Portions604may be made of a first material. Portions604may extend from an outer surface656of the cover layer600at dimple104to an intermediate point654that is between outer surface656and an inner surface652of cover layer600. Intermediate point654may be located so that portion604has depth662. Located beneath portion604may be portion605. Portion605may be made of a second material, and may have thickness664. Thickness664and thickness662may be any value within the total thickness660of cover layer600. Portions608may also be made of the second material, and may be laterally continuous with portions605as shown.

Portions604and portions608may be laterally adjacent to each other at boundary670. In the particular embodiment shown inFIG. 9, boundary670may extend vertically from top surface650to intermediate point654. This is in contrast to the above discussed embodiments where the boundary line extends through the entire thickness of the cover layer.

FIG. 10shows a fourth embodiment of a cover layer that is comprised of two different materials. The configuration of dimples104inFIG. 10is substantially similar to the configuration of dimples104inFIG. 3, discussed above. Namely, cover layer700may include portions714that correspond to the radial edge dimple section150. Portions714may be comprised of a first material. Cover layer700may also include portions718that correspond to center dimple section152. Portions718may be comprised of a second material. Collectively, portions714and portions718may correspond to dimple104. Cover layer700may then also include portions708that correspond to land areas106. Portions708may also be comprised of the second material.

In the embodiment shown inFIG. 10, portions714may have thickness766. Thickness766may extend through the entire thickness of cover layer700, as shown. However, in other embodiments not shown, thickness766may extend from a top surface152of cover layer700to an intermediate point between the top surface and inner surface752, as was discussed with respect to the embodiment ofFIG. 9above. Portions718may have thickness769, and portions708may have thickness768. Generally, thickness769may be less than thickness768.

Generally, in each ofFIGS. 7-10discussed various above, the first material may be either polyurethane or ionomer, and the second material may be either polyurethane or ionomer, as long as the second material is different from the first material. Namely, in some embodiments the first material may be polyurethane and the second material may be ionomer. In other embodiments, the first material may be ionomer and the second material may be polyurethane.

In different embodiments than those discussed variously above, the difference in hardness between the dimples and the land areas can be achieved through the use of a coating material.FIG. 11shows a golf ball800in accordance with these embodiments, and a general process for making such a golf ball. Generally, a golf ball800may comprise a core and a cover layer substantially surrounding the core, where the cover layer is formed of a material having a first hardness and has a plurality of dimples804and at least one land area806thereon. The plurality of dimples804may be arranged on the cover layer in a first pattern, and the at least one land806area may be arranged on the cover layer in a second pattern, where the first pattern and the second pattern are non-overlapping patterns. Then, the cover layer may be coated with a coating material808having a second hardness, such that coating material808overlaps at least a portion of one of the first pattern and the second pattern, but substantially does not overlap the other of the first pattern and the second pattern. The second hardness may be different from the first hardness.

In the embodiment shown inFIG. 11, the coating material808is selectively applied on the first pattern corresponding to the dimples804. In such an embodiment, the second hardness (i.e., the hardness of the coating material) is higher than the first hardness (i.e., the hardness of the cover material). Therefore, coating material808makes the dimples804hard while the cover layer, exposed on the land areas806, is soft. AlthoughFIG. 11shows all of the dimples804being coated with the coating material808, coating material808may alternatively coat only a portion of the first pattern.

FIG. 12shows a cross-sectional view of the dimples804and land areas806shown inFIG. 11. InFIG. 12, coating material808is coated on top of each of the dimples804, forming a thin layer of coating material808on a cover layer802. The thickness of the coating material808may generally be any thickness that fits within a dimple. Coating material808should generally not be so thick as to significantly affect the aerodynamics of the golf ball, however coating material808may be applied in such a way as to achieve a desired dimple depth configuration. In certain embodiments, cover layer802may have a thickness of about 2 mm or less. Accordingly, in these embodiments coating material808may have a thickness that is, for example, on the order of 0.5 mm or less, or 0.3 mm or less, or 0.1 mm or less.

FIG. 13shows another embodiment, wherein land areas806are coated with a coating material810. In this embodiment, coating material810covers at least a part of the second pattern, the second pattern corresponding to the land areas806. As mentioned above with respect to the embodiment inFIG. 12, in the embodiment ofFIG. 13coating material810may generally cover all of the second pattern or less than all of the second pattern in any arrangement as may be desired. In embodiments where coating material810covers at least a part of the second pattern, the second hardness (i.e., the hardness of coating material810) is less than the hardness of the cover layer material. Accordingly, land areas806coated with coating material810are relatively soft, while dimples804are relatively hard.

FIGS. 14 and 15show a further feature of the coating that may be used in conjunction with any of the above discussed embodiments. Specifically,FIG. 14shows several pockets812in the surface of the cover layer802. AlthoughFIG. 14shows pockets812as being located on cover layer802corresponding to land area806, pockets812may equally be located on cover layer802corresponding to dimples804, as shown inFIGS. 16 and 17. Generally, pockets812are small indentations or abrasions intentionally formed in the surface of cover layer802. Pockets812generally have a depth820that is at least less than the depth of dimple804, and, in some embodiments, significantly less than the depth of dimples804. In embodiments where cover layer802has a thickness of about 2.0 mm, the pockets812may have a depth820of less than about 0.5 mm, less than about 0.3 mm, or less than about 0.1 mm. Pockets812may enable coating material808,310to better adhere to cover layer802. Pockets812may also allow more flexibility in the design of the golf ball, such as by achieving a desired difference in hardness without, for example, changing the dimple depth or total diameter of the golf ball.

When coating material810is coated on cover layer802having pockets812therein, coating material810fills the pockets812as well as coats the surface of cover layer802with a top section814of coating material810. The top section814of coating material810may be left in place on the second pattern on top of land areas806, if desired, or may be removed to leave coating material810only in the pockets812.FIG. 15show coating material present only the pockets812. As shown inFIG. 15, the coating material is located in the pockets, but does not otherwise substantially overlap the surface of cover layer802.

FIGS. 16 and 17show an embodiment wherein pockets816are made in the surface of cover layer802located on dimple804. Similar to as discussed above, coating material808may include a top section818as well as fill the pockets816. The top section818of coating material808may then be removed, if so desired, leaving coating material808only in pockets816. Pockets816in dimple804have a depth822that may be the same as or different from depth820of pockets812associated with land area806.

In these embodiments including pockets812and/or pockets816, generally, the coating material may be used to change the hardness of the second pattern in accordance with this disclosure, without changing the diameter or aerodynamic performance of the golf ball. Therefore a wider range of golf ball designs may be used in accordance with the present disclosure, without the need to redesign the physical structure of the golf ball or sacrifice advantageous aerodynamic properties.

The coating material may generally be selected in accordance with the desired hardness. In embodiments, such as are shown inFIGS. 11 and 12, wherein the coating material has a hardness higher than the hardness of the cover layer material, the coating material may be a hard polymer or a metal plating. A wide range of hardness of a polymer material may generally be controlled by, for example, the degree of cross-linking, the degree of crystallinity, and the chain length. In a specific embodiment, for example, the cover layer material may be a thermoplastic polyurethane (TPU) having a hardness of about 45 to 60 on the Shore D scale, and the coating material may be a thermoplastic polyurethane having a hardness of about 65 on the Shore D scale. Generally, the polymer coating material may be any thermoplastic, thermoset, ionomer, copolymer, or other polymer material known and used in the art of golf balls.

In other embodiments, the coating material may be polyurethane or an ionomer in particular. For example, cover layer802may be comprised of a polyurethane or an ionomer, while the coating material may be comprised of the other of a polyurethane or an ionomer. In the embodiment ofFIG. 12, for example, cover layer802may be comprised of an ionomer while coating material804may be a polyurethane. When the hardness of the ionomer is greater than the hardness of the polyurethane, this configuration would result in hard land areas and soft dimples. Conversely, in other embodiments, cover layer802may be comprised of a polyurethane while coating808may be comprised of an ionomer.

Similarly, in the embodiment ofFIG. 13the cover layer802may be comprised of a polyurethane, while coating810may be comprised of an ionomer. When the hardness of the ionomer is greater than the hardness of the polyurethane, this configuration would again result in hard land areas (due to the coating on the land) and soft dimples. In other embodiments in accordance withFIG. 13, cover layer802may be comprised of an ionomer while coating810may be comprised of a polyurethane. Polymers are known in the art that have high hardness values.

Additionally, the coating material may be a metal plating. Nearly any typical metal may be used, as most metals have a hardness at conventional temperatures that is higher than polymer materials conventionally used to form golf ball cover layers. Exemplary metals that may be used as the coating material include aluminum, steel, tungsten, titanium, magnesium, and iron alloys, among a variety of others. The metal coating material may be selected based on hardness, workability, and cost effectiveness.

FIG. 18is a flowchart detailing a method of manufacturing the golf ball discussed above, including optional steps. Generally, a method900of manufacturing a golf ball includes first step902of receiving a golf ball having a core and a cover layer with a plurality of dimples and at least one land area thereon. The golf ball may then undergo an optional preliminary step of treating the cover layer so as to create pockets812in the cover layer. This preliminary treatment step may be, for example, a physical surface roughening, or a chemical etching that etches only a small portion of the cover layer such as an unmasked portion of the surface of the golf ball.

Next, method900of manufacturing the golf ball may take either of two general routes. In a first step906of a first route, the entire cover layer is coated with the coating mater. The coating may be a physical coating step, such as by brushing, dipping, spraying or other physical application means. Alternatively, the coating may be a chemical coating step, such as chemical vapor deposition (CVD), plasma spray coating, or other chemical application means. The coating material is then selectively removed in step908, such that the coating layer remains only on either of the first or second pattern, as desired. The removal of the coating material may be a physical grinding away of the coating, or may be a chemical removal such as by chemical etching using a mask to protect selected coated areas to prevent the removal of selected coated areas.

Alternatively, in step910a mask may be applied over the golf ball. The mask may be a physical mask having a pattern of holes corresponding to either of the first pattern or the second pattern. The coating material is then912applied on top of the mask, after which914the mask is removed, leaving the coating material on only the pattern corresponding to the holes in the mask.

Finally, if the golf ball underwent step904to create pockets, the surface portion of the coating material814may be removed in step916. This step leaves the coating material in only the pockets, and not otherwise substantially overlapping the surface of the cover layer.

FIGS. 19-38show another category of embodiments within the scope of this disclosure. Generally,FIGS. 19-38refer to embodiments where the golf ball cover has a groove therein, and the groove contains a material that is different from the material of the cover layer. Associated methods of making these golf balls are detailed inFIGS. 35-38in particular.

For purposes of this disclosure, the terms “compressible,” “compressibility,” and the like refer to the amount deformation exhibited by an object when compressed under a predetermined set of loading parameters. As used in the present disclosure, compressibility shall refer to compression deformation, which is the deformation amount (in millimeters) of an object when compressed by a force, specifically, the deformation of the object when the compression force is increased from 10 kg to 130 kg. The deformation amount of the object under the force of 10 kg is subtracted from the deformation amount of the object under the force of 130 kg to obtain the compression deformation value of the object. While compressibility (and compression deformation) is a parameter that may be measured for entire golf balls, compressibility can also be measured for individual components of golf balls. In the present disclosure, compressibility of a golf ball groove material is measured and discussed in detail.

As mentioned above, these embodiments may be applicable to golf balls having any internal structural configuration.FIGS. 19 and 20illustrate exemplary 3-layer and 4-layer golf ball constructions, respectively.

FIG. 19illustrates a cutaway, partial cross-sectional view of an exemplary three-layer golf ball construction. As shown inFIG. 19, a golf ball1100may include a cover layer1105, an outer core layer1110disposed radially inward of cover layer1105, and an inner core layer1115disposed radially inward of outer core layer1110. The dimensions and materials of each layer may be selected to achieve desired performance characteristics.

Cover layer1105may be formed of a relatively soft but durable material. For example, cover layer1105may be formed of a material that compresses/flexes when struck by a golf club, in order to provide spin of the ball and feel to the player. Although relatively soft, the material may also be durable, in order to withstand scuffing from the club and/or the golf course. Generally, the cover layer may be formed of either a polyurethane material or an ionomer material. Polyurethane materials and ionomer materials are discussed above, and are well known to a person having ordinary skill in the art.

In addition,FIG. 19illustrates the outer surface of cover layer1105as having a generic dimple pattern. While the dimple pattern on golf ball1100may affect the flight path of golf ball1100, any suitable dimple pattern may be used with the disclosed embodiments. In some embodiments, golf ball1100may be provided with a dimple pattern including a total number of dimples between approximately 300 and 400.

Outer core layer1110may be formed of a relatively firm and suitably resilient material. Outer core layer1110may be configured to provide a relatively high launch angle and a relatively low spin rate when the ball is struck by a driver, and a relatively higher spin rate and increased control when struck with irons. This may provide distance off the tee with spin and control around the greens. Inner core layer1115may be formed of a relatively firm material in order to provide distance.

The thickness of the golf ball layers may be varied in order to achieve desired performance characteristics. In some embodiments, inner core layer1115may have a diameter in the range of about 19 mm to 30 mm. For example, in some embodiments, inner core layer1115may be spherical with a diameter120of approximately 24 mm to 28 mm.

FIG. 20is a cutaway, partial cross-sectional view of a golf ball1200having a four-piece construction. As shown inFIG. 20, golf ball1200may have four layers that are positioned adjacent one another. For example, in some embodiments, golf ball1200may include an outer cover layer1205and an inner cover layer1210disposed radially inward of outer cover layer1205. Golf ball1200may also include an outer core layer1215disposed radially inward of inner cover layer1210, and an inner core layer1220disposed radially inward of outer core layer1215. Any layer may surround or substantially surround any layers disposed radially inward of that layer. For example, outer core layer1215may surround or substantially surround inner core layer1220.

As shown inFIG. 20, golf ball1200may dimples1230which may be formed in outer cover layer1205. As noted above, dimples1230may have any suitable configuration.

In the present disclosure and drawings, golf ball1200is described and illustrated as having four layers. In some embodiments, at least one additional layer may be added. For example, in some embodiments, a mantle layer may be added between outer core layer1215and inner cover layer1210. In some embodiments, an intermediate cover layer may be inserted between inner cover layer1210and outer cover layer1205. Further, in some embodiments, an intermediate core layer may be inserted between inner core layer1220and outer core layer1215. Other layers may be added on either side of any disclosed layer as desired to achieve certain performance characteristics and/or attributes.

In some embodiments, golf ball1200may have a diameter of at least 42.67 mm (1.680 inches), in accordance with the Rules of Golf. For example, in some embodiments, golf ball1200may have a ball diameter between about 42.67 mm and about 42.9 mm, and may, in some embodiments, have a ball diameter of about 42.7 mm. Golf ball1200may have a ball weight between about 45 g and about 45.8 g and may, in some embodiments, have a ball weight of about 45.4 g.

The thickness of the layers of golf ball1200may be varied in order to achieve desired performance characteristics. In some embodiments, outer cover layer1205may have a thickness of approximately 0.5 mm to 2 mm. In addition, in some embodiments, inner cover layer1210may have a thickness of approximately 0.5 mm to 2 mm. In some embodiments, outer cover layer1205and/or inner cover layer1210may have a thickness of approximately 0.8 mm to 2 mm. In some embodiments, outer cover layer1205and/or inner cover layer1210may have a thickness of approximately 1 mm to 1.5 mm.

In some embodiments, outer core layer1215may have a thickness of at least about 5 mm. In some embodiments, inner core layer1220may be a sphere having a diameter1225in the range of approximately 21 mm to 30 mm. In some embodiments, diameter1225of inner core layer1220may be in the range of approximately 24 mm to 28 mm. For example, in some embodiments, diameter1225may be 24 mm. In other embodiments, diameter1225may be 28 mm.

In some embodiments, the inner core layer may be formed by any suitable process, such as injection molding or compression molding. Further the inner core layer may be formed of any suitable material, such as a thermoplastic material, for example. In some embodiments, suitable thermoplastic materials may include, for example, an ionomer resin, such as Surlyn®, produced by E. I. Dupont de Nemours and Company. In some embodiments, the inner core layer may be formed from a highly neutralized acid polymer composition. Exemplary highly neutralized acid polymer compositions suitable for forming the inner core layer may include, for example, HPF resins such as HPF1000, HPF2000, HPF AD1024, HPF AD1027, HPF AD1030, HPF AD1035, HPF AD1040, all produced by E. I. Dupont de Nemours and Company.

The acid polymer may be neutralized to 80% or higher, including up to 100%, with a suitable cation source, such as magnesium, sodium, zinc, or potassium. Suitable highly neutralized acid polymer compositions for use in forming the inner core layer may include a highly neutralized acid polymer composition and optionally additives, fillers, and/or melt flow modifiers.

Suitable additives and fillers may include, for example, blowing and foaming agents, optical brighteners, coloring agents, fluorescent agents, whitening agents, UV absorbers, light stabilizers, defoaming agents, processing aids, antioxidants, stabilizers, softening agents, fragrance components, plasticizers, impact modifiers, acid copolymer wax, surfactants. In some embodiments, the additives and fillers may include, for example, inorganic fillers, such as zinc oxide, titanium dioxide, tin oxide, calcium oxide, magnesium oxide, barium sulfate, zinc sulfate, calcium carbonate, zinc carbonate, barium carbonate, mica, talc, clay, silica, lead silicate, and other types of organic fillers. In some embodiments, the additives and fillers may include, for example, high specific gravity metal powder fillers, such as tungsten powder, molybdenum powder, and others. In some embodiments the additives and fillers may include regrind, that is, core material that is ground and recycled.

Any suitable melt flow modifiers may be included in the highly neutralized acid polymer composition. Exemplary suitable melt flow modifiers may include, for example, fatty acids and salts thereof, polyamides, polyesters, polyacrylates, polyurethanes, polyethers, polyureas, polyhydric alcohols, and combinations thereof.

The outer core layer may be formed by any suitable method, such as compression molding. Further, the outer core layer may be formed of any suitable material, such as a thermoset material. For example, in some embodiments, outer core layer1215may be formed by crosslinking a polybutadiene rubber composition. When other rubber is used in combination with a polybutadiene, polybutadiene may be included as a principal component. For example, a proportion of polybutadiene in the entire base rubber may be equal to or greater than 50% by weight and, in some embodiments, may be equal to or greater than 80% by weight. In some embodiments, outer core layer215may be formed of a polybutadiene rubber composition including a polybutadiene having a proportion of cis-1,4 bonds of equal to or greater than 60 mol %. For example, in some embodiments, the proportion may be equal to or greater than 80 mol %.

In some embodiments, cis-1,4-polybutadiene may be used as the base rubber and mixed with other ingredients. In some embodiments, the amount of cis-1,4-polybutadiene may be at least 50 parts by weight, based on 100 parts by weight of the rubber compound. Various additives may be added to the base rubber to form a compound. The additives may include a cross-linking agent and a filler. In some embodiments, the cross-linking agent may be zinc diacrylate, magnesium acrylate, zinc methacrylate, or magnesium methacrylate. In some embodiments, zinc diacrylate may provide advantageous resilience properties.

In some embodiments, the filler may include zinc oxide, barium sulfate, calcium carbonate, or magnesium carbonate. In some embodiments, zinc oxide may be selected for its advantageous properties. In some embodiments, the filler may be used to increase the specific gravity of the material. For example, metal powder, such as tungsten, may alternatively be used as a filler to achieve a desired specific gravity. In some embodiments, the specific gravity of outer core layer215may be in the range of about 1.05 g/cm^3 to about 1.35 g/cm^3.

In some embodiments, a polybutadiene synthesized using a rare earth element catalyst is preferred. Using this polybutadiene may provide golf ball200with increased resilience. Examples of rare earth element catalysts include lanthanum series rare earth element compound, organoaluminum compound, and almoxane and halogen containing compound. A lanthanum series rare earth element compound is preferred. Polybutadiene obtained by using lanthanum rare earth-based catalysts usually employ a combination of a lanthanum rare earth (atomic number of 57 to 71) compound, but particularly preferred is a neodymium compound.

One or more cover layers may be molded to enclose the outer core layer. Generally, the cover layers may be formed of any suitable materials. For example, in some embodiments, cover layers may be formed from thermoplastic or thermoset materials. In some embodiments, inner cover layer1210and/or outer cover layer1205may be made from a thermoplastic material including at least one of an ionomer resin, a highly neutralized acid polymer composition, a polyamide resin, a polyester resin, and a polyurethane resin. In some embodiments, inner cover layer1210may be formed of the same type of material as outer cover layer1205. In other embodiments, inner cover layer1210may be formed of a different type of material from outer cover layer1205. In some embodiments, outer cover layer may be comprised of either polyurethane or ionomer, in particular. For example, the outer cover layer may be comprised of an ionomer such as Surlyn®.

The disclosed concepts may be implemented in golf balls having three-layer construction, four-layer construction, five-layer construction, or any other suitable configuration. Exemplary such concepts are discussed below.

In some embodiments, an exemplary disclosed golf ball may include features that provide increased spin and/or feel when struck. In order to provide such characteristics, the golf ball may be provided with one or more components formed of a material having an increased compressibility. That is, the material may deflect a greater amount when exposed to a given amount of force than a relatively less compressible material. In order to provide increased spin and/or feel, such compressible material may be disposed radially outward from the center of the ball, for example at or near the outer surface of the ball.

It is generally desirable for a golf ball to exhibit minimal spin when struck with a driver. Further, when a golf ball is struck with a club moving at a relatively high club head speed, such as a driver, the amount of deformation of the ball is significant, such that the properties of the core and other inner layers of the ball determine the playing characteristics, particularly distance. For these reasons, it may be desirable to provide a golf ball with a relatively hard and incompressible outer cover layer. An outer cover layer that is too compressible may be too “grippy” and thus produce more spin, even when struck with a driver. Further, a compressible outer cover layer would tend to absorb some of the energy of the impact with the club head and, therefore, reduce the distance achievable with the ball.

During short game play, however, it may be desirable for a golf ball to exhibit greater amounts of spin and feel. Greater amounts of spin facilitate greater control of the ball. During short game play, where club head speeds are relatively slower, the compressibility of the cover layers of the ball determine the playing characteristics, since the ball is not typically struck hard enough to compress the inner layers of the ball. Increased spin may be provided by a compressible outer cover layer material. Further, such a compressible outer cover layer may also provide improved feel of the ball when struck at relatively slow club head speeds. Thus, the desirability of having a compressible cover for short game play (e.g., playing with irons) may be in conflict with the desirability of having a relatively incompressible cover for long game play (e.g., hitting with a driver).

The present disclosure provides ball configurations, which implement both compressible and incompressible materials in the cover in order to produce a ball that has both good distance with low spin when struck with a driver, and increased spin and feel when struck with a short game club (e.g., irons, pitching wedge, sand wedge). In some embodiments, an exemplary disclosed golf ball may include one or more core layers and one or more cover layers. In some embodiments, an outermost cover layer, formed of a first material, having formed therein one or more grooves. For example, such grooves may include one or more channels, which may be formed in any suitable configuration. In some embodiments, for example, the outermost cover layer may include at least one spiral channel. In some embodiments, the cover layer may include circular grooves or circumferential grooves, which may be arranged in a grid about the outer surface of the ball.

In order to provide the increased spin and/or feel, a relatively compressible material may be disposed within the one or more grooves. Such material may have a compressibility that is less than the compressibility of the outermost cover layer material. In some embodiments, the outer cover layer material may constitute a substantial majority of the outer surface area of the golf ball and the outer surface of the material disposed in the grooves may constitute a substantial minority of the outer surface area of the golf ball. In some embodiments, the compressible material in the grooves, i.e. the groove material, may be selected from a polyurethane and an ionomer. Specifically, in some embodiments, the groove material may be polyurethane.

Similarly, in some embodiments, the outermost cover layer material may also be selected from a polyurethane and an ionomer, so long as the groove material and the cover material are different. For example, when the groove material is polyurethane the cover material may be an ionomer. However, in other embodiments, the groove material may be an ionomer while the cover material may be a polyurethane.

In some embodiments, the golf ball may include features that affect the aerodynamics of the ball. For example, in some embodiments, the outer surface of the material disposed in the grooves may extend beyond or may be recessed from the outer surface of the outermost cover layer. Therefore, the ball may include either bulges and/or recesses in the outer surface, which may have an effect on aerodynamics. In some embodiments the aerodynamic effect may be a reduction in drag coefficient, to improve distance and/or spin. In other embodiments, the effect may be an increase in drag coefficient, possibly in exchange for increased or decreased spin and/or control. In some embodiments, the orientation of the bulges and/or recesses may induce spin during flight. For example, a spiral arrangement of elongate bulges and/or recesses may cause a particular spin of the ball during flight.

FIG. 21illustrates an exemplary golf ball1300. Ball1300may include an inner core layer1310and an outer core layer1315disposed radially outward of inner core layer1310. In addition, ball1300may include an inner cover layer1320disposed radially outward of outer core layer1315, and an outer cover layer1325disposed radially outward of inner cover layer1320. These layers may be configured generally as discussed above with respect toFIGS. 19 and 20. In some embodiments, ball1300may have more or fewer layers. Suitable materials for inner core layer1310, outer core layer1315, inner cover layer1320, and outer cover layer1325are discussed above. Other suitable materials will be recognized by those having ordinary skill in the art.

For purposes of this disclosure and claims, the outer cover layer shall be referred to, in some cases, as the “outermost layer” of the golf ball. Similarly, the term “outermost surface area” of the golf ball is used in reference to the outer surface of the disclosed layers. It will be understood by those having ordinary skill in the art, however, that one or more finish coatings, including paint or other colorations, as well as one or more topcoats or clearcoats may be applied to an outer surface of the disclosed layers. These finish coatings have relatively insignificant thickness and, therefore, the outer surfaces of the disclosed layers are effectively the outermost surfaces of the golf ball, from a structural standpoint.

According to exemplary disclosed embodiments, spin and/or feel of the golf ball may be increased by the inclusion of a relatively compressible material at and/or near the outer surface of the outer cover layer. In some embodiments, a second material may be molded into the grooves of the outer cover layer, wherein the second material has a compressibility that is different than the compressibility of the outer cover layer material. For example, in some embodiments, a material that is more compressible than the outer cover layer material may be molded into the grooves. In other embodiments, the outer cover layer material may be more compressible than the material molded into the grooves. Although the material molded into the grooves (“groove material”) may be more or less compressible than the outer cover layer, for purposes of discussion, the embodiments discussed below, unless otherwise noted, will be described as having a groove material that is more compressible than the outer cover layer material.

In some embodiments, the outer surface of the groove material forms a portion of the outer surface of the ball. The surface area and thickness of the groove material may be factors in the extent to which the groove material affects the spin and feel of the ball. Generally, the greater the amount of exposed surface area and/or thickness of a compressible material, the greater the increases in spin and feel will be. A compressible material will exhibit more grip against the club face, much like a soft compound tire provides more road grip. Therefore the amount of compressible material surface area will affect the amount of grip the ball will have against the club face. This increase in grip provides more spin and feel when striking the ball. In addition, the thickness of the compressible material has a similar effect on grip, the thickness of the compressible material is related to the amount of compressible material present at the outer portion of the ball. The more compressible material present at the outer portion of the ball, the more the outer portion deforms when struck, even on short game strikes, which tend to be less forceful.

In order to limit the increase in spin provided by the inclusion of compressible groove material, the groove material may constitute a limited amount of the outer surface area of the ball. For example, in some embodiments, the outer surface of the outer cover layer may constitute a substantial majority of the overall surface area of the ball, and the outer surface of the groove material may constitute a substantial minority of the outer surface of the ball. In other embodiments, the outer surface of the groove material may constitute a substantial majority of the outer surface area of the ball, and the outer surface of the outer cover layer may constitute a substantial minority of the outer surface area of the ball. This configuration may be advantageous, for example, when the outer cover layer material is more compressible than the groove material.

In addition, the extent to which the groove material extends radially beyond the outer surface of the outer cover layer may also influence the spin and feel. In some embodiments, the groove material may partially fill the grooves, and thus, may have an outer surface that is recessed from the outer surface of the outer cover layer. In some embodiments, the groove material may completely fill the grooves. For example, in some embodiments, the outer surface of the groove material may be substantially flush with the outer surface of the outer cover layer. In some embodiments, the outer surface of the groove material may overfill the grooves, bulging out such that the outer surface of the groove material extends radially outward beyond the outer surface of the outer cover layer. Generally, the greater the distance of a groove material from the center of the ball (relative to the outer surface of the outer cover layer), the greater the increases in spin and feel. The further the groove material extends radially, the more surface area of the groove material will be engaged by the club face and the less surface area of the outer cover layer will be engaged by the club face, thus providing increased grip against the club face, resulting in increased spin and feel.

In some embodiments, outer cover layer1325may include a groove1330extending radially inward from an outer surface1340of outer cover layer1325. In some embodiments, groove1330may have the form of an elongate channel. Such channels may have any suitable configuration, such as, for example a spiral arrangement, as shown inFIG. 21. As further illustrated inFIG. 21, groove1330may be a continuous spiral groove encircling golf ball1300and extending substantially from one side of the golf ball to an opposite side of the golf ball. Other embodiments may incorporate more than one channel, such as a plurality of spiral grooves. Other arrangements are also possible. In addition, groove330may have any suitable shape, length, width, and depth. Exemplary alternative groove configurations are shown in the figures and discussed below.

Ball1300may include a groove material1335disposed within groove1330. In some embodiments, groove material1335may have a compressibility that is different from the compressibility of the material from which outer cover layer1325is formed. In some embodiments, groove material1335may be more compressible than the material of outer cover layer1325. In other embodiments, groove material1335may be less compressible than outer cover layer1325. In particular embodiments, groove material1335may be selected from an ionomer and a polyurethane, while outer cover layer1325may be made of a material selected from an ionomer and a polyurethane, where outer cover layer1325is made from a different material than the groove material1335. Accordingly, in a particular embodiment, outer cover layer1325may comprise an ionomer while groove material1335may comprise a polyurethane. Generally, as is known to a person having ordinary skill in the art, a polyurethane material may be more compressible than an ionomer material.

In some embodiments, groove material1335may have a hardness that is different than the hardness of outer cover layer1325. For example, in some embodiments, groove material1335may have a hardness that is lower than the hardness of outer cover layer material1325. Specifically, in one embodiment, groove material1335may comprise a polyurethane while outer cover layer1325may comprise an ionomer. As discussed variously above, a polyurethane may have a hardness that is less than a hardness of an ionomer.

In such embodiments, the harder outer cover layer material may provide durability to the outer surface1345of ball1300, while the softer groove material1335may provide increased spin and/or feel. In other embodiments, groove material1335may have a hardness that is greater than the hardness of outer cover layer1325.

The placement of the relatively compressible groove material1335in the cover region of ball1300, radially displaced from the center of ball1300, may enhance the increase in spin and/or feel provided by compressible groove material1335. In addition, the compressible groove material1335may further enhance the increase in spin and/or feel in some embodiments where groove material1335extends radially outward beyond outer surface1340of outer cover layer1325. For example, as shown inFIG. 21, an outer surface1350of groove material1335may extend radially outward beyond outer surface1340of outer cover layer1325. A bulge dimension1355, shown inFIG. 21, illustrates an exemplary amount by which outer surface1350of groove material1335may extend beyond outer surface1340. Exemplary alternative configurations with respect to the relative placement the outer surfaces of the groove material and the outer cover layer are shown and discussed in greater detail in conjunction with other disclosed embodiments.

The cross-sectional shape and the depth of groove1330within outer cover layer1325may have a number of possible configurations, as shown and discussed with respect to several exemplary disclosed embodiments. In one possible configuration shown inFIG. 21, groove1330may have a curved cross-sectional shape, such that a bulged groove material1335appears to have an American football-shaped cross-sectional shape. In addition, in some embodiments, groove1330may extend partially through outer cover layer1325, thus forming a recess in outer cover layer1325, such that a portion1360of outer cover layer1325may extend between an inner surface1365of groove material1335and an outer surface1370of inner cover layer1320, which may be a different material than outer cover layer1325and groove material1335.

The bulging of groove material1335beyond outer surface1340of outer cover layer1325may provide at least two benefits. First, the bulging groove material1335may provide ball1300with a different surface area when struck hard, such as with a driver, than when struck more easily, such as on short game strokes. When struck hard, the compressibility of groove material1335may allow groove material1335to deflect (compress) such that outer surface1350of groove material1335becomes substantially flush with outer surface1340of outer cover layer1325. Thus, the surface area of outer surface1345of ball1300that contacts the club face when struck hard, will be constituted of all of outer surface1340and outer surface1350in the area of ball1300struck by the club face. In such situations, since the surface area of outer cover layer1325may constitute a substantial majority of outer surface1345of ball1300, when ball1300is struck hard, more of the contact area between ball1300and the club face will be constituted by outer surface1340of outer cover layer1325. Since outer cover layer1325may be less compressible than groove material1335, this may be beneficial when driving the ball, because less spin is desired for drives.

When struck lightly, groove material1335may not compress completely. Accordingly, a larger proportion of the surface area of ball1300contacting the club face will be constituted by outer surface1350of groove material1335. This may provide a grippier surface of ball1300, thus producing more spin and providing increased feel.

A second benefit is that the bulging of groove material1335may provide an aerodynamic effect. The bulges of groove material1335may disrupt airflow around ball1300, disrupting airflow in much the same way dimples do on a conventional golf ball. In addition, the pattern of bulging groove material1335may induce other aerodynamic effects. For example, a spiral arrangement, such as that shown inFIG. 21, may induce a particular spin during flight. In some embodiments, this induced spin may enhance spin generated at club face contact. For example, a spiral groove material configuration may induce backspin, which enhances the backspin produced by the club face. In some embodiments, the induced spin may be counter to, or off angle from, the spin generated by the club face. For example, in some embodiments, the spiral configuration may produce a rotation about the axis of ball flight (like an American football).

In addition to aerodynamic effects provided by groove material1335, ball1300may be provided with other aerodynamic effects by other structural features. For example, in some embodiments, ball1300may include dimples1375on outer surface1340of at least a portion of outer cover layer1325. Alternatively, or additionally, in some embodiments, ball1300may have dimples in outer surface1350of groove material1335(not shown). Dimples1375may have any suitable configuration. In some embodiments, dimples1375may have an arrangement that is based on one or more dimple patterns known to those having ordinary skill in the art.

FIG. 22shows an enlarged cross-sectional view of a portion of an exemplary golf ball having an alternative groove configuration.FIG. 22illustrates an exemplary golf ball1400. Ball1400may include an inner core layer1410and an outer core layer1415disposed radially outward of inner core layer1410. In addition, ball1400may include an inner cover layer1420disposed radially outward of outer core layer1415, and an outer cover layer1425disposed radially outward of inner cover layer1420. These layers may be configured generally as discussed above with respect toFIGS. 19 and 20, as well asFIG. 21.

As shown inFIG. 22, outer cover layer1425of ball1400may include groove1430extending radially inward from an outer surface1440of outer cover layer1425. Ball1400may also include a groove material1435disposed within groove1430. Groove1430may have any suitable configuration, such that the outer surface of groove material1435may have any suitable shape, including for example, round, elongate, rectangular, oval, polygonal, or any other suitable shape. Groove material1435may have performance characteristics, such as compressibility, that are the same or similar to those discussed above with respect to groove material1335.

Similar to the embodiment shown inFIG. 21, groove material1435may be bulged beyond an outer surface1440of outer cover layer1425, as shown inFIG. 22. Groove material1430may be formed as a recess, such that a portion1460of outer cover layer1425may extend between an inner surface1465of groove material1435and an outer surface1470of inner cover layer1420.

Groove1430may have side walls1445. In some embodiments, side walls1445may be angled with respect to outer surface1440of outer cover layer1425. For example, as shown inFIG. 22, side walls1445may be oriented substantially radially, that is, substantially perpendicular to outer surface1440. Other similar embodiments may implement side walls that are parallel to one another and, therefore, not precisely radial. Such radial and parallel configurations may provide durability under shear loads (loads on groove material1435that are substantially tangential to the outer surface of the ball). Radially oriented side walls1440may retain groove material1435in groove1430under shear loads by providing lateral support against groove material1435.

Also unlike groove1330inFIG. 21, groove1430may have a substantially planar bottom surface1480, as shown inFIG. 22. A planar bottom surface (as opposed to a curved bottom surface as shown inFIG. 21) may accommodate a larger amount of groove material, which may be desirable to provide increased spin and/or feel. Additionally, a planar bottom surface may be easier to manufacture, for example, via molding or machining.

FIG. 23illustrates a similar embodiment to that shown inFIG. 22.FIG. 23shows a golf ball1500having an inner core layer1510, an outer core layer1515, an inner cover layer1520, and an outer core layer1525. Ball1500may also include a groove1530, and a groove material1535disposed within groove1530. As shown inFIG. 23, groove material1535may be bulged beyond an outer surface1540of outer cover layer1525, and thus, may have an outward facing surface that is substantially similar to groove material1435inFIG. 22.

As illustrated inFIG. 23, ball1500may include side walls1545that are angled with respect to outer surface1540of outer cover layer1525. In some embodiments, opposing side walls1545may be angled closer to one another near outer surface1540of outer cover layer1525. Having side walls1545angled in this manner may increase durability by providing additional retention of groove material1535in groove1530under loading.

As also illustrated inFIG. 23, an inner surface1565of groove material1535and mating bottom surface1580of groove1530may be curved in an arc about the center of ball1500. Accordingly, the thickness of the portion1560of outer cover layer1525may be consistent across substantially the entire groove1530. This may provide predictability regarding the structural properties of the assembly.

In some embodiments, grooves may extend completely through the outer cover layer of the golf ball. In some such embodiments, the inner surface of the groove material may be in contact with the outer surface of the inner cover layer. In other embodiments, a portion of an underlying, inner cover layer may extend radially outward into (and in some cases through) the groove to form the groove material. These configurations may provide still further increases in manufacturability and/or durability of the assembly.

FIG. 24is an enlarged, partial cross-sectional view of a golf ball having a bulged groove material disposed within a groove that extends completely through the outer cover of the ball.FIG. 24shows a golf ball1600, having an inner core layer1610, an outer core layer1615, an inner cover layer1620, and an outer core layer1625. Ball1600may also include a groove1630, and a groove material1635disposed within groove1630. As shown inFIG. 24, an outer surface1650of groove material1635may extend radially outward beyond an outer surface1640of outer cover layer1625. As illustrated inFIG. 24, groove1630may extend completely through outer cover layer1625. Accordingly, an inner surface1665of groove material1635may be in contact with an outer surface1670of inner cover layer1620.

FIG. 25illustrates an enlarged, partial cross-sectional view of another golf ball embodiment featuring a bulging groove material disposed within a groove that extends completely through the outer cover layer.FIG. 25shows a golf ball1700, having an inner core layer1710, an outer core layer1715, an inner cover layer1720, and an outer core layer1725. Ball1700may also include a groove1730, and a groove material1735disposed within groove1730. As shown inFIG. 25, in some embodiments, groove material1735may be formed by a portion1760of the inner cover layer material that extends radially outward into groove1730. For purposes of illustration,FIG. 17includes a dashed line1765to delineate a boundary between inner cover layer1720and groove material1735.

In some embodiments, groove material may be recessed from the outer surface of the outer cover layer. In some such embodiments, the outer cover layer may be formed of a more compressible material than the groove material. This configuration may operate on similar principles to embodiments, wherein a bulging groove material is more compressible than an outer cover layer into which it is molded. In some embodiments, this may provide a larger surface area of the ball formed of the more compressible material. Thus, such an embodiment could be implemented to provide even greater amounts of spin and/or feel.

In some embodiments, recessed groove material may be formed of a material that is more compressible than the outer cover layer. For example, the outer cover layer may be an ionomer when the groove material is a polyurethane. Such configurations may be implemented to provide a golf ball with a more durable outer surface. In a recessed groove material embodiment, contact between the outer surface of the groove material with clubs and the ground may be limited. By having a less compressible, and possibly harder, material disposed further radially outward than the more compressible groove material, and thus, exposed to more contact with the clubs and the ground, a more durable material may be subjected to a substantial majority of the abuse.

In addition to the benefits (discussed above) of adding a compressible material in the cover region of a golf ball having a recessed groove material, the recesses in the grooves may also provide an aerodynamic effect. As discussed above regarding the embodiment shown inFIG. 21, like bulged groove material, recesses in grooves may provide disruption of airflow at boundary layers (similar to dimples). Also like bulged groove material, recesses in grooves may be arranged to provide other aerodynamic effects, such as by inducing spin.

FIG. 26illustrates an exemplary embodiment including a recessed groove material.FIG. 26shows a golf ball1800, having an inner core layer1810, an outer core layer1815, an inner cover layer1820, and an outer core layer1825. Ball1800may also include a groove1830, and a groove material1835disposed within groove1830. As shown inFIG. 26, in some embodiments, an outer surface1850of groove material1835may be recessed from an outer surface1840of outer cover layer1825.

Groove material1835may have a compressibility, and/or hardness, that are different than outer cover layer825. In some embodiments, outer cover layer1825may be more compressible than groove material1835. For example, as mentioned above with respect to other embodiments, outer cover layer1825may comprise a polyurethane while groove material1835may comprise an ionomer. In other embodiments, groove material1835may be more compressible than outer cover layer1825. For example, again as mentioned above with respect to other embodiments, outer cover layer1825may comprise an ionomer while groove material1835may comprise a polyurethane. In determining whether to utilize a more compressible material for outer cover layer1825or for groove material1835, a ball designer may consider, as a factor, the desirability of performance characteristics provided by a more compressible material (e.g., spin, feel, control), and performance characteristics provided by a less compressible material (e.g., distance, durability). In order to achieve more compressible material characteristics, the more compressible material may be used to form outer cover layer1825, which generally makes more contact with the club face. In order to achieve more incompressible material characteristics, the less compressible material may be used to form outer cover layer1825.

Performance characteristics may also be determined by the relative surface areas of outer cover layer1825and groove material1835that make up the overall outer surface1845of ball1800. For example, although a more compressible material may be utilized for recessed groove material1835, the ball may be provided with more compressible material characteristics by making grooves1830wider and providing a higher ratio of groove material surface area to outer cover layer surface area.

Groove1830may have any suitable shape. As shown inFIG. 26, groove1830may be arranged in a spiral configuration similar to groove1330inFIG. 21. In addition, groove1830may have any suitable cross-sectional shape.FIG. 27is an enlarged view of a portion of ball1800, showing an exemplary cross-sectional shape of groove1830. As shown inFIG. 27, in some embodiments, groove1830may have a curved bottom surface1885. As further illustrated inFIG. 27, groove1830may be formed as a recess in outer cover layer1825. Therefore, a portion1860of outer cover layer1825may extend between an inner surface1865of groove material1835and an outer surface1870of inner cover layer1820. As can also be seen inFIG. 27, an outer surface1850of groove material1835may be recessed from outer surface1840, as illustrated by a dimension1880.

Golf ball1800may also include other surface features. For example, in some embodiments, ball1800may include dimples1875on at least a portion of outer surface1840of outer cover layer1825or in other portions of golf ball1800.

FIGS. 28 and 29show enlarged, cross-sectional views of exemplary alternative groove configurations having recessed groove material.FIG. 28illustrates an embodiment wherein the groove has beveled or angled side walls.FIG. 28shows a golf ball2000, having an inner core layer2010, an outer core layer2015, an inner cover layer2020, and an outer core layer2025. Ball2000may also include a groove2030, and a groove material2035disposed within groove2030. As shown inFIG. 28, in some embodiments, an outer surface2050of groove material2035may be recessed from an outer surface2040of outer cover layer2025.

In some embodiments, groove2030may have sidewalls2055that are angled relative to outer surface2040of outer cover layer2025. In some embodiments, opposing sidewalls2055may be angled farther away from one another at outer surface2040of outer cover layer2025, as shown inFIG. 28. In some embodiments, a bottom surface2085of groove2030may be curved about the center of ball2000, as also shown inFIG. 28.

FIG. 29illustrates an embodiment wherein the groove extends completely through the outer cover layer.FIG. 29shows a golf ball2100, having an inner core layer2110, an outer core layer2115, an inner cover layer2120, and an outer core layer2125. Ball2100may also include a groove2130, and a groove material2135disposed within groove2130. As shown inFIG. 29, in some embodiments, an outer surface2150of groove material2135may be recessed from an outer surface2140of outer cover layer2125. This is illustrated by a dimension2145. Outer surface2150of groove material2135is illustrated as being curved about the center of ball2100. However, it may also be possible for outer surface2150to be substantially planar.

As shown inFIG. 29, in some embodiments, groove2130may be defined by side walls2155and may extend completely through outer cover layer2125. Also, in some embodiments, groove material2135may be formed by a portion2160of inner cover layer material that extends radially outward into groove2130. A dashed line2165illustrates a boundary between inner cover layer2125and portion1160forming groove material2135.

FIGS. 30 and 31illustrate enlarged, cross-sectional views of exemplary groove configurations, wherein the groove material is substantially flush with the outer surface of the outer cover layer. The benefits and considerations of having groove material bulging or recessed are discussed above. The same considerations are also relevant to flush embodiments. In some cases, having flush groove material may provide a suitable compromise between bulged and recessed groove material configurations. Flush embodiments may also be easier to manufacture, and may produce a golf ball that appears to have a more traditional outer surface shape.

FIG. 30shows a golf ball2200, having an inner core layer2210, an outer core layer2215, an inner cover layer2220, and an outer core layer2225. Ball2200may also include a groove2230, and a groove material2235disposed within groove2230. As shown inFIG. 30, in some embodiments, an outer surface2250of groove material2235may be substantially flush with an outer surface2240of outer cover layer2225. In addition, groove2230may include angled side walls2255.

As also shown inFIG. 30, in some embodiments, groove2230may extend completely through outer cover layer2225. Accordingly, an inner surface2265of groove material2235may be in contact with an outer surface2270of inner cover layer2220.

FIG. 31shows a golf ball2300, having an inner core layer2310, an outer core layer2315, an inner cover layer2320, and an outer core layer2325. Ball2300may also include a groove2330, and a groove material2335disposed within groove2330. As illustrated inFIG. 31, in some embodiments, groove2330may be defined by side walls2355and may extend completely through outer cover layer2325. In addition, in some embodiments, groove material2335may be formed by a portion2360of inner cover layer material that extends radially outward from the center of ball2300. Portion2360is generally delineated by a dashed line2365inFIG. 31.

FIG. 32illustrates an alternative embodiment having bulged groove material.FIG. 32shows a golf ball2400, having an inner core layer2410, an outer core layer2415, an inner cover layer2420, and an outer core layer2425. Ball2400may also include a groove2430, and a groove material2435disposed within groove2430.

As shown inFIG. 32, in some embodiments, grooves2430(and the bulging groove material2435associated with each groove2430) may be substantially circular. It will be understood that grooves2430may have any other suitable shape, such as squares, rectangles, triangles, and any other suitable shape.

Outer surfaces2440of outer cover layer2425and outer surfaces2450of groove material2435may constitute an outer surface2445of ball2400. The size of grooves2430may vary and, accordingly, the ratio of surface area between outer surface2440and outer surface2450may also be varied to provide the desired performance characteristics.

Groove material2435may bulge beyond outer surface2440as indicated by a dimension2460. In addition, grooves2430may include side walls2455that are angled with respect to outer surface2440of outer cover layer2425.

As shown inFIG. 32, in some embodiments, grooves2430may extend completely through outer cover layer2425. Accordingly, an inner surface2465of groove material2435may be in contact with an outer surface2470of inner cover layer2420.

Golf ball2400may also include other surface features. For example, in some embodiments, ball2400may include dimples2475on at least a portion of outer surface2440of outer cover layer2425or in other portions of golf ball2400.

FIG. 33illustrates a golf ball embodiment similar to ball2400, but having recessed groove material.FIG. 33shows a golf ball2500, having an inner core layer2510, an outer core layer2515, an inner cover layer2520, and an outer core layer2525. Ball2500may also include a groove2530, and a groove material2535disposed within groove2530.

As shown inFIG. 33, in some embodiments, grooves2530(and the groove material2535associated with each groove2530) may be substantially circular. It will be understood that grooves2530may have any other suitable shape, such as squares, rectangles, triangles, and any other suitable shape.

Outer surfaces2540of outer cover layer2525and outer surfaces2550of groove material2535may constitute an outer surface2545of ball2500. The size of grooves2530may vary and, accordingly, the ratio of surface area between outer surface2540and outer surface2550may also be varied to provide the desired performance characteristics.

Outer surface2550of groove material2535may be recessed from outer surface2540. In some embodiments, outer surfaces2550of groove material2535may be substantially planar, as shown inFIG. 33. In other embodiments, outer surfaces2550may curve about the center of ball2500. In addition, grooves2530may include side walls2555that are angled with respect to outer surface2540of outer cover layer2525.

As shown inFIG. 33, in some embodiments, grooves2530may extend completely through outer cover layer2525. Accordingly, an inner surface2565of groove material2535may be in contact with an outer surface2570of inner cover layer2520.

Golf ball2500may also include other surface features. For example, in some embodiments, ball2500may include dimples2575on at least a portion of outer surface2540of outer cover layer2525or in other portions of golf ball2500.

FIG. 34illustrates an alternative embodiment wherein the outer cover layer is formed as a grid defining grooves between the gridlines.FIG. 34shows a golf ball2600, having an inner core layer2610, an outer core layer2616, an inner cover layer2620, and an outer core layer2625. Ball2600may also include a groove2630, and a groove material2635disposed within groove2630.

As shown inFIG. 34, an outer surface2640of outer cover layer2625and an outer surface2650of groove material2635may form the overall outer surface2645of ball2600. In some embodiments, outer surface2650of groove material2635may extend beyond outer surface2640of outer cover layer2625. This configuration may operate on similar principles to the bulged groove material embodiments discussed above.

In some embodiments, outer cover layer2625may be formed as a grid, wherein the gridlines of the grid are formed by intersecting bands of material. For example, a first set of bands2655may intersect with a second set of bands2660. Grid bands2655and2660may have any suitable configuration and orientation. As shown inFIG. 34, grid bands2655may be oriented as latitudinal gridlines. In other embodiments, grid bands2655may be oriented differently, such as longitudinally. Also, as shown inFIG. 1634grid bands2660may be oriented longitudinally. In other embodiments, grid bands2660may be oriented differently, such as latitudinal.

The openings in the outer cover layer grid may define grooves2630. In some embodiments, as shown inFIG. 34, groove material2635may be formed by portions of inner cover layer2620that extend radially outward into grooves2630.

In some embodiments, groove material2635may be more compressible than outer cover layer2625. In other embodiments, groove material1635may be less compressible than outer cover layer2625. The advantages of each such configuration are discussed above in conjunction with other similar embodiments.

Golf ball2600may also include other surface features. For example, in some embodiments, ball2600may include dimples2675on at least a portion of outer surface2640of outer cover layer2625or in other portions of golf ball2600.

The disclosed golf ball embodiments as shown inFIGS. 19-34may be manufactured in several different ways. The following discussion provides details regarding exemplary processes for making certain disclosed embodiments. Many of the provided details apply generally for making golf balls having grooves and groove material.

The layers of a golf ball may be made using any of a number of molding processes, such as injection molding and compression molding. In some embodiments, outer layers may be molded on top of pre-molded inner layers. In some embodiments, an inner layer may be injection molded within a pre-molded outer shell.

In addition, pre-formed inner and/or outer layers may be supported during the process of co-molding an adjacent layer using a plurality of support pins. In some embodiments, the support pins may be a retractable part of the mold apparatus. In some embodiments, the support pins may be extensions of the pre-molded layer. For example, in some embodiments, support mold pins may be formed as part of a core layer and may meld with inner cover layer material during injection of the inner cover layer material. In such embodiments, the support pins may be formed of a material that is readily compatible with the material of the layer to be added. This compatibility may prevent or inhibit the formation of voids and/or delamination at the pin sites.

Use of support pins in molding processes are well-known in the art and, accordingly, one of ordinary skill would readily recognize support pin configurations that may be suitable for use in the methods described below.

An exemplary method of making a golf ball according to the present disclosure may include molding at least one core layer. In some embodiments the method may include molding multiple core layers, such as an inner core layer and an outer core layer. The formation of these core layers may be accomplished by injection molding and/or compression molding. Various techniques for forming golf ball core layers will be readily recognized by those having ordinary skill in the art.

In addition, the method may also include molding an outer cover layer radially outward of the core layer. The molding of this outer cover layer may be performed using injection molding or compression molding. In some embodiments, the method may include formation of an inner cover layer radially inward of the outer cover layer. In some embodiments, the inner cover layer may be formed first, and the outer cover layer may be molded afterward. In other embodiments, the outer cover layer may be pre-molded as a shell and then the inner cover layer may be injection molded under the pre-molded shell between the outer cover layer and the core layers. In some embodiments, the shell may be formed as two hemispherical shells, in order to enable a pre-molded core to be placed inside the shell before injecting the inner cover layer material.

FIGS. 35 and 36illustrate an apparatus and method for molding a golf ball according to the embodiment shown inFIG. 34, wherein an inner cover layer is injection molded under and through a pre-formed, grid-like outer cover layer.FIG. 35shows a cross-sectional view of a mold2700, including a first mold section2705and a second mold section2710. Mold2700may be used for injection molding groove material within a pre-formed grid-type shell. Accordingly, mold2700may include recesses2715which may be configured to receive injected groove material about a periphery of a pre-formed outer cover layer shell. Mold2700may also include one or more injection gates2720for injecting groove material into mold2700.

FIG. 36illustrates mold2700with an outer cover layer shell2725placed inside. As shown inFIG. 36, shell2725may be formed as two hemispherical half-shells, as indicated by an equator line2740. In an exemplary method, the hemispherical half-shells may be snapped together about, or otherwise placed around one or more inner core layers (not shown) and then placed in mold2700, as shown inFIG. 36. It will be noted that, for purposes of illustration, mold2700is shown in cross-section, whereas shell2725is shown in an elevation view.

The method may further include injecting a groove material2735through gates2720into the cavity within mold2700where it may flow into the void under shell2725. Groove material2735may further flow radially outward through grooves2730(which may be formed completely through outer cover layer shell2725), into recesses2715. Molding groove material2735in this manner may form the groove material from portions of inner cover layer material that extend radially outward into grooves2730.

As noted above, the groove material2735may be formed of a more or less compressible material than outer cover layer shell2725.

FIGS. 37 and 38illustrate an apparatus and method for making a golf ball according to the embodiment shown inFIG. 21, including molding a grooved outer cover layer and molding a groove material into recess grooves on the pre-molded outer cover layer.FIG. 37illustrates an outer cover layer mold2900configured to pre-mold the outer cover layer. Mold2900may include a first mold section2905, and a second mold section2910. Mold2900may further include spiral protrusions2915, which may be configured to form channel-type recess grooves, such as grooves1330shown inFIG. 21. It will be noted that outer portions of mold2900are shown in cross-section, while a spherical inner void is shown in elevation to illustrate the arrangement of spiral protrusions2915along the walls of the spherical void. Mold2900may be used to injection mold outer cover layer material into injection gates2920to form an outer cover layer radially outward of one or more inner core layers and, in some embodiments, radially outward of one or more inner cover layers, thus forming a pre-molded golf ball component.

FIG. 38illustrates an exemplary method of injecting a groove material into grooves3030formed in a pre-molded golf ball component3025.FIG. 38shows a groove material mold3000. Mold3000may include a first mold section3005and a second mold section3010.FIG. 38also shows pre-molded golf ball component3025disposed within mold3000. As shown inFIG. 38, mold3000may include a spiral groove3015configured to correspond with grooves3030in component3025to form a spiral void3040configured to receive groove material. In an exemplary method, groove material3035may be injected via injection gates3020into spiral void3040, as shown inFIG. 38. Molding groove material3035in this manner may form groove material3035in recess groove3030such that the outer cover layer material extends between an inner surface of groove material3035and an outer surface of the inner cover layer.

Similar molds and methods may be used to form golf balls having other features of embodiments discussed above. For example, exemplary methods of making golf balls may include forming the grooves completely through the outer cover layer, and molding the groove material such that an inner surface of the groove material is in contact with an outer surface of the inner cover layer. Further, similar molds and methods may be used for form the grooves in any suitable size, shape, and arrangement, including those discussed above. For example, such molds and methods may be used to form grooves having angled side walls, rounded bottom surfaces, planar bottom surfaces, and other configurations discussed above. Also, similar molds and methods may be implemented to form the groove material in any of the various configurations discussed above.

Although not wishing to be bound by any particular theory of action, it is believed that golf balls according to the present disclosure achieve superior play characteristics due to the interaction between a golf club face and the golf ball as is shown inFIGS. 39-41. Although these figures show embodiments of a golf ball where different materials correspond to the dimples and land respectively, it is believed that similar mechanisms apply to golf balls having different materials as the cover and in various grooves (as such mechanisms of action were discussed above).

InFIG. 39, a golfer4000swings a golf club4002toward golf ball100. It is noted that golf ball100is referenced here, however the same results are achieved by any particular golf ball disclosed herein. The golf club4002is a driver, having a large club head4004, and a club face4006that is wide and has a low loft angle. As seen in the zoomed-in section ofFIG. 15, the golf ball100includes dimples104and land area108(as inFIG. 1and others).

InFIG. 40, the club face4006strikes the golf ball100with a large amount of force, in accordance with a drive. The golf ball100therefore deforms, as is shown in the first zoom-in section. Specifically, the golf ball100deforms such that a first area4150of the golf ball cover layer is flat against the club face4006. In first area4150, the club face4006impacts both the land areas and the dimples, compressing them against core202(and any inner layers). In this first area4150where both the hard dimples104and the soft land108are flat against the club face, the cover layer “appears” to have a hardness that is between the hardness of the dimples and the hardness of the land (depending on the ratio of each). By “appears” is meant: how the club face4006interfaces with the cover layer in this area.

In particular, as seen in the second zoomed-in section ofFIG. 40, at the periphery of first area4150, the club face impacts the land while impacting the dimples to varying degrees. Specifically, first dimple4100is not impacted at all, while first land area4110is impacted to a slight degree. Second dimple4102is impacted only slightly, as shown by the difference between the present shape of dimple4102and the original shape denoted by outline4106, because the first land4110and second land4112are partially but not entirely compressed. Similarly, third dimple4104is also impacted somewhat but not entirely, as shown by outline4108. Therefore, during a golf shot involving a high degree of force (such as a drive), the golf ball100undergoes compression such that the club face touches at least some of the relatively hard surfaces of the dimples.

FIG. 41shows a different type of golf shot in action. InFIG. 41the golf club4010is, for example, an iron. Club head4012on iron4010has a higher loft angle, as seen by the angle of the club face4006in the first zoomed-in section ofFIG. 41. In this scenario, the golf ball is hit with less force than inFIG. 40. Therefore, golf ball100does not compress against club face4006so as to deform the dimples, as shown in the first zoomed-in section ofFIG. 41.FIG. 41shows a periphery of the deformed second area4160, where club face4006again impacts first land4110and second land4112, but in this case does not deform first dimple4100, second dimple4102, or third dimple4104. Therefore, the apparent hardness of the cover layer is lower, as compared to the apparent hardness of the cover layer under compression shown inFIG. 40, because the club face4006only touches relatively soft land areas108without also touching the relatively hard surfaces of dimples104.

Thus, the present golf ball appears to be softer when hit with less force, but harder when hit with more force. Thereby, the present golf ball achieves improved play characteristics associated with harder cover layers (such as longer distance) during drives, while also achieving improved play characteristics associated with softer cover layers (such as higher spin) during short shots. Furthermore, golf balls made in accordance with this disclosure may also simultaneously achieve improved play characteristics that are unrelated to the hardness.