Golf ball with thermoplastic polyurethane thread

Abstract

A golf ball with a wound layer composed of thermoplastic elastomer thread is disclosed herein. The golf ball has a core, an optional boundary layer, a wound layer and a cover. The core is preferably composed of polybutadiene material. The optional boundary layer is preferably composed of a blend of ionomers. The cover is preferably composed of a thermosetting polyurethane material.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Not Applicable

FEDERAL RESEARCH STATEMENT

[0002] [Not Applicable]

BACKGROUND OF INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a wound golf ball. More specifically, the present invention relates to a golf ball a wound layer composed of thermoplastic polyurethane thread.

[0005] 2. Description of the Related Art

[0006] Golf balls have evolved throughout the history of the game. The first type of golf balls were the featherie, a leather sphere stuffed with wet, compressed feathers. The next innovation in golf balls was the gutta percha one piece golf ball. As early as the 1800's, golfers realized that gutta percha golf balls with indented surfaces flew better than those with smooth surfaces. Hand-hammered gutta-percha golf balls could be purchased at least by the 1860's, and golf balls with brambles (bumps rather than dents) were in style from the late 1800's to 1908. In 1908, an Englishman, William Taylor, received a patent for a golf ball with indentations (dimples) that flew better and more accurately than golf balls with brambles. A. G. Spalding & Bros., purchased the U.S. rights to the patent and introduced the GLORY ball featuring the TAYLOR dimples. Until the 1970s, the GLORY ball, and most other golf balls with dimples had 336 dimples of the same size using the same pattern, the ATTI pattern. The ATTI pattern was an octahedron pattern, split into eight concentric straight line rows, which was named after the main producer of molds for golf balls. The only innovation related to the surface of a golf ball during this sixty year period came from Albert Penfold who invented a mesh-pattern golf ball for Dunlop. This pattern was invented in 1912 and was accepted until the 1930's.

[0007] Golf balls with a wound layer appeared in the 1920's, and have been refined since that time. In the 1930's through the 1960's, the major innovations in golf balls related to core development. In the 1960's, the development of ionomer materials, particularly the brand SURLYN® from Du Pont, became the major innovation for golf balls into the 1980's. In the 1970's, dimple pattern innovations also appeared from the major golf ball manufacturers. In 1973, Titleist introduced an icosahedron pattern, which divides the golf ball into twenty triangular regions. In the late 1980's and into the 1990's, three-piece solid golf balls, as opposed to three-piece wound, began to appear from the major golf ball manufacturers. These three-piece solid golf balls involved two thermoplastic layers covering a core.

[0008] Although not commercialized, several patents have disclosed four-piece golf balls. One example is Sun, U.S. Pat. No. 5,273,286 for a Multiple Concentric Section Golf Ball, which was filed in 1992. Sun discloses a golf ball with a solid inner core, a graphite intermediate core, a polybutadiene outer core and a cover composed of balata, ionomer or urethane materials.

[0009] Other examples are Hayashi et al., U.S. Pat. No. 5,816,940 for a Wound Golf Ball, which was originally filed in Japan in 1996, and Hayashi et al., U.S. Pat. No. 5,797,808 for a Wound Golf Ball which was originally filed in Japan in 1996. The Hayashi patents disclose a polybutadiene center core, a thermoplastic enclosure layer (preferably an elastomer), a wound layer and a cover composed of an inner layer and an outer layer with both cover layers composed of thermoplastic materials.

[0010] Yet another example is Maruko et al., U.S. Pat. No. 5,674,137 which was originally filed in Japan in 1994. Maruko discloses a golf ball with a liquid filled core, a wound layer over the core, and inner and outer cover layers composed of an ionomer material. The primary objective of Maruko is to provide a golf ball with good distance, well-defined spin and greater durability.

[0011] A further example is Yabuki et al., U.S. Pat. No. 5,716,293 for a Golf Ball which was originally filed in Japan in 1995. Yabuki discloses a golf ball with a rubber solid core containing an oil substance, an oil-resistant coating layer, a wound layer and an ionomer cover layer.

[0012] Another example is Stanton et al., U.S. Pat. No. 5,836,831 for a Golf Ball, originally filed in 1996. Stanton discloses a liquid filled core having a polyether-amide shell, a wound layer and a polymer cover.

[0013] There have been many attempts to develop a golf ball that can do everything for every golfer, a golf ball that has tremendous distance, with exceptional feel and outstanding durability. However, current golf balls have been unable to deliver everything.

SUMMARY OF INVENTION

[0014] The present invention provides a golf ball that has tremendous distance, with exceptional feel and outstanding durability. The present invention is able to accomplish this by providing a golf ball with a wound layer composed of a thermoplastic elastomer thread.

[0015] Further, the present invention allows for facilitated processing of wound ball with a cast thermosetting polyurethane cover since the thermoplastic elastomer thread is capable of withstanding the exothermic reaction during casting of the thermosetting polyurethane cover.

[0016] Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a cross-sectional view of a golf ball of the present invention having a core, a wound layer and a cover.

[0018] FIG. 2 is a cross-sectional view of an alternative embodiment of a golf ball of the present invention having a core, a boundary layer, a wound layer and a cover.

[0019] FIG. 3 is a cross-sectional view of an alternative embodiment of a golf ball of the present invention having a fluid containing core, a boundary layer, a wound layer and a cover.

[0020] FIG. 4 is an isolated top plan view of one embodiment of a thermoplastic polyurethane thread of the present invention.

[0021] FIG. 5 is an isolated top plan view of an alternative embodiment of a thermoplastic polyurethane thread of the present invention.

DETAILED DESCRIPTION

[0022] As illustrated in FIG. 1, the golf ball of the present invention is generally indicated as 10. In a preferred embodiment, the golf ball 10 includes a solid core 12, a wound layer 13 and a cover 14. As shown in FIG. 2, an alternative embodiment of the golf ball 10 includes a solid core 12, a boundary layer 15, a wound layer 13 and a cover 14. As shown in FIG. 3, a second alternative embodiment of the golf ball 10 includes a fluid-containing hollow core 12′, a boundary layer 15, a wound layer 13, and a cover 14. The wound layer in each embodiment is composed of thermoplastic elastomer thread 30 (also referred to as windings). The thermoplastic elastomer thread is preferably a thermoplastic polyurethane. Alternatively, the thermoplastic elastomer is a polyether block amide or a polyester elastomer.

[0023] The wound layer 13 has a thickness in the range of 0.050 inch to 0.250 inch, preferably in the range of 0.060 inch to 0.150 inch and most preferably in the range of 0.080 to 0.100 inch. A preferred embodiment has a wound layer 13 with a thickness of 0.080 inch. As shown in FIG. 4, a preferred embodiment of the thermoplastic elastomer thread 30 has a flat cross section with a thickness t ranging from 0.1 millimeters (mm) to 0.5 mm, and a width w preferably ranging from 30 mm to 100 mm, more preferably ranging from 50 mm to 80 mm, and most preferably 70 mm. As shown in FIG. 5, an alternative embodiment of the thermoplastic polyurethane thread 30′ has a circular cross-section with a diameter d preferably ranging from 0.5 mm to 1.5 mm, more preferably ranging from 0.75 mm to 1.25 mm, and most preferably 1 mm. The thermoplastic elastomer thread 30 preferably has an ultimate elongation of approximately 1000 grams (the thread has a 1000% elongation under a load of 1000 grams).

[0024] The thermoplastic elastomer thread of the present invention is preferably composed of para-phenylene diisocyanate (PPDI) based polyurethane prepolymer and a curing agent, reacted to create a thermoplastic PPDI-based elastomer thread. One such thermoplastic elastomer thread material is HYLENE, available from DuPont Chemicals of Delaware. Alternatively, the thermoplastic elastomer thread of the present invention is preferably composed of 4,4′diphenylmethane diisocyanate (MDI) based polyurethane prepolymer and a curing agent, reacted to create a thermoplastic MDI-based elastomer thread. Such a MDI based elastomer thread is available from Meltex, Inc of Newport Beach, Calif. Another thermoplastic elastomer thread material is PEBAX, a polyether block amide available from Atochem. Another thermoplastic elastomer thread material is HYTREL, a polyester elastomer available from DuPont. Those skilled in the pertinent art will recognize that other thermoplastic elastomer materials may be used for the wound layer without departing from the scope and spirit of the present invention.

[0025] Devices for winding threads around cores are well known in the golf industry. One such apparatus rotates a golf ball core as it draws thread through a tensioning system from a thread source. The tensioning system usually has several tension wheels for applying tension to the thread during winding around the core. The thread is wound around the core to a predetermined diameter. In constructing the golf ball 10 of the present invention, a similar winding device may be utilized to wind the thermoplastic polyurethane thread 30 around the core 12 or the boundary layer 15 and core 12. A latex coating may be placed over the wound layer 13 prior to molding a cover over the wound layer 13.

[0026] The wound layer 13 preferably provides a softer feel to the golf ball 10, especially with a solid polybutadiene core 12. The wound layer 13 also preferably provides a golf ball 10 with better spin around the greens while not deterring from the distance performance.

[0027] The cover 14 is preferably composed of a polymer material that is relatively soft and has a good durability. A preferred material for the cover 14 is a thermosetting polyurethane material such as disclosed in U.S. Pat. No. 6,190,268, entitled Golf Ball With A Polyurethane Cover, and hereby incorporated by reference in its entirety. An alternative material for the cover is a blend of ionomers such as disclosed in co-pending U.S. patent application Ser. No. 09/847,094, filed on May 1, 2001, entitled Golf Ball, and hereby incorporated by reference in its entirety. Other materials for the cover 14 include thermoplastic polyurethane, polyether block amide such as PEBEX material, a polyester elastomer such as HYTREL, a blend of ionomer and thermoplastic polyurethane, a blend of ionomer and diene rubber, and the like. The thickness of the cover 14 preferably ranges from 0.020 inch to 0.060 inch, more preferably from 0.025 inch to 0.045 inch, and most preferably from 0.030 inch to 0.0375 inch. The Shore D hardness of the cover 14 preferably ranges from 30 Shore D to 75 Shore D, more preferably from 40 Shore D to 60 Shore D, and most preferably from 47 Shore D to 55 Shore D.

[0028] The cover 14 is preferably composed of a polyurethane material preferably formed from a blend of diisocyanate prepolymers. Preferably, the polyurethane is a thermosetting polyurethane, however, thermoplastic polyurethane materials are within the scope of the present invention. The blend of diisocyanate prepolymers includes at least one TDI-based polyurethane prepolymer and at least one other diisocyanate-based polyurethane prepolymer. In a preferred embodiment, the blend of diisocyanate prepolymers includes at least one PPDI-based polyurethane prepolymer and at least one TDI-based polyurethane prepolymer. Alternative embodiments have a blend, which includes at least two different PPDI-based polyurethane prepolymer and at least one TDI-based polyurethane prepolymer. Yet further embodiments may include at least one TDI-based polyurethane prepolymer and at least one MDI-based polyurethane prepolymer. Still further embodiments have only a PPDI-based prepolymer instead of a blend of polyurethane prepolymers. Those skilled in the pertinent art will recognize that multiple variations of diisocyanate prepolymers may be utilized without departing from the scope and spirit of the present invention.

[0029] A process for casting a cover is disclosed in U.S. Pat. No. 6,200,512, which is hereby incorporated by reference. As stated above, the thermoplastic elastomer thread is capable of withstanding the exothermic casting reaction used for forming a cover.

[0030] In an alternative embodiment, the threads of the wound layer 13 encompass a boundary layer 15, as shown in FIGS. 2 and 3. The boundary layer 15 is preferably composed of a thermoplastic material. A preferred material for the boundary layer 15 is a blend of ionomers such as those sold by DuPont under the brand name SURLYN® or those sold by Exxon Chemical under the brand name IOTEK®. Alternatively, the boundary layer 15 may be composed of a polyether block amide such as PEBAX®, or a polyester elastomer such as HYTREL®. The boundary layer 15 has a Shore D hardness, as measured by ASTM standards, in range of 55 to 75, preferably 65 to 75, and most preferably 70. The boundary layer 15 is described in greater detail below.

[0031] The core 12 is solid, hollow, or fluid filled with a liquid or gas. A preferred core 12 is a solid core primarily composed of a polybutadiene material. The fluid-containing version of the core 12′ preferably has a liquid such as corn syrup or water.

[0032] The coefficient of restitution (COR) is a measure of the resilience of a golf ball. The COR is a measure of the ratio of the relative velocity of the golf ball after direct impact with a hard surface to the relative velocity before impact with the hard surface. The COR may vary from 0 to 1, with 1 equivalent to a completely elastic collision and 0 equivalent to a completely inelastic collision. A golf ball having a COR value closer to 1 will generally correspond to a golf ball having a higher initial velocity and a greater overall distance. The effect of a higher COR value is apparent when a golf club strikes the golf ball 10. The force of the club during a swing is transferred to the golf ball 10. If the golf ball has a high COR (more elastic), then the initial velocity of the golf ball will be greater than if the golf ball had a low COR. In general, a higher compression core will result in a higher COR value.

[0033] The core 12 of the golf ball 10 is preferably composed of a blend of a base rubber, a cross-linking agent, a free radical initiator, and one or more fillers or processing aids. A preferred base rubber is a polybutadiene having a cis-1,4 content above 90%, and more preferably 98% or above. A preferred cross-linking agent is a zinc diacrylate, and a commercially available zinc diacrylate is SR-416 from Sartomer Co., Inc., Exton, Pa. Other metal salt di- or mono-(meth)acrylates suitable for use in the present invention include those in which the metal is calcium or magnesium. In the manufacturing process it may be beneficial to pre-mix some cross-linking agent(s), such as, e.g., zinc diacrylate, with the polybutadiene in a master batch prior to blending with other core components.

[0034] Free radical initiators are used to promote cross-linking of the base rubber and the cross-linking agent. Suitable free radical initiators for use in the golf ball core 12 of the present invention include peroxides such as dicumyl peroxide, bis-(t-butyl peroxy) diisopropyl benzene, t-butyl perbenzoate, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-5-butylperoxy-hexane, 1,1-di (t-butylperoxy) 3,3,5-trimethyl cyclohexane, and the like, all of which are readily commercially available.

[0035] Zinc oxide is also preferably included in the core formulation. Zinc oxide may primarily be used as a weight adjusting filler, and is also believed to participate in the cross-linking of the other components of the core (e.g. as a coagent). Additional processing aids such as dispersants and activators may optionally be included. In particular, zinc stearate may be added as a processing aid (e.g. as an activator). Any of a number of specific gravity adjusting fillers may be included to obtain a preferred total weight of the core 12. Examples of such fillers include tungsten and barium sulfate. All such processing aids and fillers are readily commercially available. A particularly useful tungsten filler is WP102 Tungsten (having a 3 micron particle size) available from Atlantic Equipment Engineers (a division of Micron Metals, Inc.), Bergenfield, N.J.

[0036] Table 1 below provides the ranges of materials included in the preferred core formulations of the present invention. 1 TABLE 1 Component Preferred Range Most Preferred Range Polybutadiene 100 parts 100 parts Zinc diacrylate 20-35 phr 25-30 phr Zinc oxide 0-50 pbr 5-15 pbr Zinc stearate 0-5 pbr 1-10 pbr Peroxide 0.2-2.5 phr 0.5-1.5 phr Filler As desired As desired (e.g. tungsten) (e.g. 2-10 pbr) (e.g. 2-10 phr)

[0037] In the present invention, the core components are mixed and compression molded in a conventional manner known to those skilled in the art. The finished core 12 has a diameter of about 1.20 to about 1.64 inches for a golf ball 10 having an outer diameter of 1.68 inches. More preferably, the finished core 12 has a diameter of about 1.30 to about 1.50 inches for a golf ball 10 having an outer diameter of 1.68 inches. Most preferably, the finished core 12 has a diameter of about 1.305 to about 1.345 inches for a golf ball 10 having an outer diameter of 1.68 inches The core weight is preferably maintained in the range of about 32 to about 40 g. The core PGA compression is preferably maintained in the range of about 55 to 90, and most preferably about 55 to 80.

[0038] As used herein, the term PGA compression is defined as follows:PGA compression value=180 Riehle compression valueThe Riehle compression value is the amount of deformation of a core or a golf ball in inches under a static load of 200 pounds, multiplied by 1000. Accordingly, for a core deformation of 0.110 inches under a load of 200 pounds, the Riehle compression value is 110 and the PGA compression value is 70.

[0039] In an alternative embodiment, the core 12 may be hollow or fluid filled. In such an embodiment, as shown in FIG. 3, the core 12 has a shell 12a encompassing an interior chamber 12b. The interior chamber may be filled with a fluid 12c. Exemplary fluids 12c are water, air, corn syrup, oil, and the like. If a liquid is utilized as the fluid 12c, then preferably the liquid occupies only half of the volume of the interior chamber 12b. The compressibility of the fluid is a primary concern in such an embodiment. The shell 12a should be sufficient to contain the fluid under the tremendous forces exerted on the shell 12a during impact between a golf club head and the golf ball 10. A preferred shell 12a is composed of a polybutadiene material. Alternatively, the shell 12a may be composed of metal such as titanium, stainless steel or the like. If the fluid 12c is air, the air may be greater or less than one atmosphere in pressure.

[0040] As is described above, one embodiment of the golf ball 10 includes at least one boundary layer 15 that is preferably composed of a thermoplastic material or a blend of thermoplastic materials. Most preferably the boundary layer 15 is composed of at least one thermoplastic that contains organic chain molecules and metal ions. The metal ion may be, for example, sodium, zinc, magnesium, lithium, potassium, cesium, or any polar metal ion that serves as a reversible cross-linking site and results in high levels of resilience and impact resistance. Suitable commercially available thermoplastics are ionomers based on ethylene copolymers and containing carboxylic acid groups with metal ions such as described above. The acid levels in such suitable ionomers may be neutralized to control resiliency, impact resistance and other like properties. In addition, other fillers with ionomer carriers may be used to modify (e.g. preferably increase) the specific gravity of the thermoplastic blend to control the moment of inertia and other like properties. Exemplary commercially available thermoplastic materials suitable for use in a boundary layer 15 of a golf ball 10 include, for example, the following materials and/or blends of the following materials: HYTREL® and/or HYLENE® products from DuPont, Wilmington, Del., PEBAX® products from Atochem, Philadelphia, Pa., SURLYN® products from DuPont, and/or ESCOR® or IOTEK® products from Exxon Chemical, Houston, Tex.

[0041] The Shore D hardness of the boundary layer 15 is preferably 75. It is preferred that the boundary layer 15 has a hardness of between about 55-85 Shore D. In a preferred embodiment, the boundary layer 15 has a Shore D hardness in the range of about 65-75. One reason for preferring a boundary layer 15 with a Shore D hardness of approximately 75 is to improve the feel of the resultant golf ball. It is also preferred that the boundary layer 15 is composed of a blend of SURLYN® ionomer resins. SURLYN® 8150, 9150, and 6320 are, respectively, an ionomer resin composed of a sodium neutralized ethylene/methacrylic acid, an ionomer resin composed of a zinc neutralized ethylene/methacrylic acid, and an ionomer resin composed of a terpolymer of ethylene, methacrylic acid and n-butyl acrylate partially neutralized with magnesium, all of which are available from DuPont Polymer Products, Wilmington, Del.

[0042] The boundary layer 15 may include a predetermined amount of a baryte mixture. The baryte mixture is included as 8 or 9 parts per hundred parts of the ionomer resins. One preferred baryte mixture is composed of 80% barytes and 20% of an ionomer, and is available from Americhem, Inc., Cuyahoga Falls, Ohio, under the trade designation 38534X1. The thickness of the boundary layer 15 preferably ranges from 0.040 inch to 0.90 inch, and most preferably ranges from 0.0525 inch to 0.058 inch.

[0043] From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.

Claims

1. A golf ball comprising:

a core;

a wound layer covering the core, the wound layer composed of a thermoplastic elastomer thread, the thermoplastic elastomer thread having a flat cross section with a thickness ranging from 0.1 mm to 0.5 mm and a width ranging from 30 mm to 100 mm; and

a cover encompassing the wound layer, the cover composed of a cast thermosetting polyurethane material.

2. The golf ball according to claim 1 wherein the thermoplastic polyurethane thread is composed of a thermoplastic polyurethane from reactants comprising a para-phenylene diisocyanate prepolymer.

3. The golf ball according to claim 1 wherein the wound layer has a thickness in the range of 0.050 inch to 0.250 inch.

4. The golf ball according to claim 1 wherein the wound layer has a thickness of between 0.080 inch and 0.100 inch.

5. The golf ball according to claim 1 wherein the cover has a thickness of 0.03 inch to 0.05 inch.

6. The golf ball according to claim 1 wherein the core has a diameter between 1.30 inches and 1.55 inches.

7. The golf ball according to claim 1 wherein the core comprises a polybutadiene material and has a PGA compression of at least 55.

8. A golf ball comprising:

a solid core comprising a polybutadiene material, having a PGA compression of at least 55, and a diameter in the range of 1.35 inches to 1.58 inches;

a boundary layer covering the solid core, the boundary layer comprising a blend of ionomer materials, having a Shore D hardness between 40 and 85 and a thickness in the range of 0.040 inch to 0.090 inch;

a wound layer covering the boundary layer, the wound layer having a thickness of 0.050 inch to 0.250 inch, the wound layer composed of a thermoplastic elastomer thread, the thermoplastic elastomer thread having a flat cross section with a thickness ranging from 0.1 mm to 0.5 mm and a width ranging from 30 mm to 100 mm; and

a cover encompassing the wound layer, the cover having a thickness in the range of 0.020 inch to 0.050 inch, the cover composed of a cast thermosetting polyurethane.

9. The golf ball according to claim 8 further comprising a latex coating over the wound layer.

10. A golf ball comprising:

a solid core comprising a polybutadiene material, having a PGA compression of at least 55, and a diameter in the range of 1.35 inches to 1.58 inches;

a boundary layer covering the solid core, the boundary layer comprising a blend of ionomer materials, having a Shore D hardness between 40 and 85 and a thickness in the range of 0.040 inch to 0.090 inch;

a wound layer covering the boundary layer, the wound layer having a thickness of 0.050 inch to 0.250 inch, the wound layer consisting essentially of a thermoplastic elastomer thread; and

a cover encompassing the wound layer, the cover having a thickness in the range of 0.020 inch to 0.050 inch, the cover composed of a cast thermosetting polyurethane material.