US20140045623A1

US20140045623A1 - Golf Ball With Hard Cover Layer

Info

Publication number: US20140045623A1
Application number: US13/963,477
Authority: US
Inventors: Arthur Molinari; Nicholas Yontz; Chien-Hsin Chou; Chen-Tai Liu
Original assignee: Nike Inc
Current assignee: Nike Inc
Priority date: 2012-08-13
Filing date: 2013-08-09
Publication date: 2014-02-13

Abstract

A golf ball is provided that has a cover layer with an increased hardness. The golf ball may have an inner core made from a highly neutralized polymer. The golf ball may have a four-piece construction, including an inner core, an outer core, a mantle layer, and the cover layer. The cover layer may be made of a thermoplastic polyurethane. The thermoplastic polyurethane cover layer may be formed of a material having a plaque hardness of at least about 44 Shore D. For example, the cover layer may be formed of a material having a plaque hardness of from about 44 to about 50 Shore D, or about 46 Shore D in particular.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a non-provisional application claiming the benefit of priority to U.S. Provisional Application Ser. No. 61/682,757, entitled “Golf Ball with Hard Cover Layer”, filed Aug. 13, 2012, which is incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates generally to golf balls with an inner core made from a highly neutralized polymer that have a cover layer with increased hardness.
The game of golf is an increasingly popular sport at both 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 and durability. For example, some golf balls have a better flight performance than other golf balls, in terms of initial velocity, spin, and total distance.
In recent years, golf balls with high performance resins, in particular, highly neutralized polymer materials, have been introduced into the market. Highly neutralized acid polymers are known to be used as the material for a golf ball core. For example, U.S. Pat. No. 6,653,382 to Statz et al., entitled “Highly Neutralized Ethylene Copolymers and Their Use in Golf Balls” and filed Oct. 18, 2000, discloses a golf core having melt-processable, highly-neutralized ethylene acid copolymers. U.S. Pat. No. 6,756,436 to Rajagopalan et al., entitled “Golf Balls Comprising Highly-Neutralized Acid Polymers” and filed Apr. 9, 2002, discloses golf balls having highly neutralized acid polymer cores. The disclosure of this patent is hereby incorporated by reference. Other conventional highly neutralized acid polymers are generally disclosed in U.S. Pat. No. 7,652,086 to Sullivan et al., entitled “Highly-neutralized Thermoplastic Copolymer Center for Improved Multi-layer Core Golf Ball” and filed Feb. 3, 2006, the disclosure of which is hereby incorporated by reference.
Known golf balls with a core made of highly neutralized polymer materials may achieve some desirable performance properties. However, different types of golfers may prefer different play characteristic from a golf ball. Namely, some golfers may prefer that a golf ball be softer and thereby achieve increased spin and controllability, at the loss of total distance off the tee. On the other hand, other golfers may prefer a harder golf ball that achieves lower spin and therefore increased total distance.
Therefore, there exists a need in the art for a golf ball with an inner core made from a highly neutralized polymer that achieves lower rates of spin when struck by a golf club.

SUMMARY

Generally, this disclosure relates to golf balls that have an inner core made from one or more highly neutralized polymers, while also having a cover layer made from a material having a plaque hardness of at least 44 Shore D. The increased hardness of the cover layer may enable the golf ball to achieve lower rates of spin, and therefore attain a longer total distance off the tee.
In one aspect, this disclosure provides a golf ball comprising: an inner core, the inner core encompassing a center of the golf ball and being comprised of a highly neutralized polymer; an outer core, the outer core being positioned radially outward of the inner core and substantially surrounding the inner core; a mantle layer, the mantle layer being positioned radially outward of the outer core and substantially surrounding the outer core; and a cover layer, the cover layer being positioned radially outward of the mantle layer and substantially surrounding the mantle layer; wherein the cover layer is made from a material having a plaque hardness of at least about 44 Shore D.
In another aspect, this disclosure provides a golf ball comprising: an inner core, the inner core encompassing a center of the golf ball and being comprised of a highly neutralized polymer; an outer core, the outer core being positioned radially outward of the inner core and substantially surrounding the inner core, the outer core being comprised of a thermoset polybutadiene rubber; a mantle layer, the mantle layer being positioned radially outward of the outer core and substantially surrounding the outer core, the mantle layer being comprised of an ionomer resin; and a cover layer, the cover layer being positioned radially outward of the mantle layer and substantially surrounding the mantle layer, the cover layer being comprised of a thermoplastic polyurethane; wherein the thermoplastic polyurethane of the cover layer has a plaque hardness of from about 44 to about 50 Shore D.
Other systems, methods, features and advantages of the disclosure will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the disclosure, and be protected by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.

FIG. 1 shows a representative golf ball in accordance with this disclosure, the golf ball being of a four-piece construction, having an inner core, an outer core, a mantle layer, and a cover layer;

FIG. 2 is a chart showing various values of the launch angle and backspin for several example golf balls in accordance with this disclosure as contrasted with several comparative example golf balls that are not within the scope of this disclosure, for a first test conducted with a driver;

FIG. 3 is a chart showing various values of the launch angle and backspin for several example golf balls in accordance with this disclosure as contrasted with several comparative example golf balls that are not within the scope of this disclosure, for a second test conducted with a driver;

FIG. 4 is a chart showing various values of the launch angle and backspin for several example golf balls in accordance with this disclosure as contrasted with several comparative example golf balls that are not within the scope of this disclosure, for a test conducted with a seven iron golf club;

DETAILED DESCRIPTION

This disclosure provides golf balls having an inner core formed from a highly neutralized polymer and a cover layer formed from a thermoplastic polyurethane, wherein the cover layer has an increased hardness. The golf ball may result in lower spin and therefore longer total distance off the tee.
As used herein, unless otherwise stated, certain material properties and golf ball properties are defined as follows.
The term “hardness” as used herein is measured generally in accordance with ASTM D-2240 and JIS K 6253. The hardness of a material is taken as the slab hardness, while the hardness of a golf ball component is measured on the curved surface of the molded golf ball component. The “cross-sectional” hardness of a golf ball component is the hardness measured in accordance with the above testing procedures, as measured on a cross-section of a golf ball that has been cut in half. When a hardness measurement is made on a dimpled cover layer, hardness is measured on a land area of the dimpled cover layer. Hardness units are generally given in Shore D, Shore C, and JIS C, as indicated.
The “coefficient of restitution” or “COR” is measured generally according to the following procedure: a test object is fired by an air cannon at an initial velocity of 40 m/sec, and a speed monitoring device is located over a distance of 0.6 to 0.9 meters from the cannon. After striking a steel plate positioned about 1.2 meters away from the air cannon, the test object rebounds through the speed-monitoring device. The return velocity divided by the initial velocity is the COR.
The “flexural modulus” is measured generally in accordance with ASTM D-790.
The “Vicat softening temperature” is measured generally in accordance with ASTM D-1525.
The “compression deformation” herein indicates the deformation amount of the ball under a force; specifically, when the force is increased to become 130 kg from 10 kg, the deformation amount of the ball under the force of 130 kg subtracts the deformation amount of the ball under the force of 10 kg to become the compression deformation value of the ball. All of the tests herein are performed using a compression testing machine available from Automated Design Corp. in Illinois, USA (ADC). The ADC compression tester can be set to apply a first load and obtain a first deformation amount, and then, after a selected period, apply a second, typically higher load and determine a second deformation amount. Thus, the first load herein is 10 kg, the second load herein is 130 kg, and the compression deformation is the difference between the second deformation and the first deformation. Herein, this distance is reported in millimeters. The compression can be reported as a distance, or as an equivalent to other deformation measurement techniques, such as Atti compression. While the ADC compression testing machine identified above can be programmed to perform these compression tests, these types of compression tests may also be performed on other testing machines.
Other properties and tests may be conducted as disclosed herein, and as may be known to a person having ordinary skill in the art of golf ball manufacturing.
Except as otherwise discussed herein below, any golf ball discussed herein may generally be any type of golf ball known in the art. Namely, unless the present disclosure indicates to the contrary, a golf ball may generally be of any construction conventionally used for golf balls, such as a conforming or non-conforming construction. Conforming golf balls are golf balls that meet the Rules of Golf as approved by the United States Golf Association (USGA). Golf balls discussed herein may also be made of any of the various materials known to be used in golf ball manufacturing, except as otherwise noted.
Furthermore, it is understood that any feature disclosed herein (including but not limited to elements of the various embodiments shown in the FIGS. and various chemical formulas or mixtures) may be combined with any other features disclosed here, as may be desired, in any combination, sub-combination, or arrangement.
Finally, as used herein, the terms “about” and “substantially” are intended to account for engineering and manufacturing tolerances.
FIG. 1 shows an embodiment of a golf ball in accordance with this disclosure. Golf ball 100 is a four-piece golf ball. Namely, golf ball 100 includes inner core 102, outer core 104, mantle layer 106, and cover layer 108.
Golf ball 100 includes radius 200 that extends from center 101 to outer surface 103. Each component may also have the dimensions as shown in FIG. 1, however FIG. 1 is not necessarily shown to scale. Namely, inner core 102 may have radius 202, outer core 104 may have thickness 204, mantle layer 106 may have thickness 206, cover layer 108 may have thickness 208. The compositions of these layers, and the thicknesses and other properties, are discussed below.
Additional embodiments, not shown, of golf ball in accordance with this disclosure may have one or more additional layers or pieces beyond those shown in FIG. 1. For example, additional core layers and/or additional cover layers may be present to form five, six, seven, or even higher piece balls. Generally, unless otherwise stated herein, the various layers of golf balls according to the various embodiments may be made from any known golf ball material.
First, inner core 102 may be comprised of a highly neutralized polymer. Highly neutralized polymer compositions, sometimes called highly neutralized acid polymers or highly neutralized acid polymer compositions, are a type of ionomer.
An ionomer is generally understood as any polymer material that includes ionized functional groups therein. Ionomeric resins are often ionic copolymers of an olefin and a salt of an unsaturated carboxylic acid. The olefin may have from about 2 to about 8 carbon atoms, and may be an alpha-olefin. The acid may be an unsaturated monocarboxylic acid having from about 3 to about 8 carbon atoms, and may be an alpha, beta-unsaturated carboxylic acid. Commonly, ionomers are copolymers of ethylene and either acrylic acid or methacrylic acid. In some circumstances, an additional co-monomer (such as an acrylate ester, i.e., iso- or n-butylacrylate, etc.) can also be included to produce a terpolymer. A wide range of ionomers are known to the person of ordinary skill in the art of golf ball manufacturing.
When a large portion of the acid groups in the ionomer is neutralized by a cation, the ionomer material may be considered to be a highly neutralized acid polymer. Generally, such a polymer is considered highly neutralized when at least 70% of the acid groups are neutralized by a cation. In various embodiments, the highly neutralized acid polymer may be neutralized to at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or substantially 100%.
The acid content of an ionomer, including highly neutralized polymers, is defined as the percentage of unsaturated carboxylic acid by weight relative to the total weight of the polymer. Generally, the acid content may range from 1% to 50%. In general, the acid content is considered “normal” when the acid content does not exceed 15%. In particular embodiments where the ionomer has a “high” acid content, the acid content is above 15% but still below 50%. In some embodiments, the acid content is considered high when between 20% and 50% or between 20% and 40%. Generally, higher acid levels may enable higher densities, but higher acid levels may also result in a loss of melt-processibility and related properties such as elongation and toughness. The acid content of an ionomer may affect the hardness. Namely, high acid levels may reduce any crystallinity otherwise present in the polymer.
In some embodiments, inner core 102 may comprise only one type or formulation of highly neutralized polymer. In other embodiments, blends of different types or formulations of highly neutralized polymers in various percentages are used. The innermost core layer may be made using any technique known in the art, including but not limited to injection molding.
In some embodiments, inner core 102 may generally include one or two highly neutralized polymer compositions with additives, fillers, and melt flow modifiers. In some embodiments, inner core 102 generally includes HPF resins such as HPF2000 and HPF AD1035, produced by E. I. DuPont de Nemours and Company. In some embodiments, inner core 102 includes 100% by weight of HPF AD1035. In some embodiments, inner core 102 includes 80% by weight of HPF AD1035 and 20% by weight of additives, fillers, and melt flow modifiers. In some embodiments, inner core 102 includes 70% by weight of HPF AD1035 and 30% by weight of HPF2000. In some embodiments, inner core 102 includes 60% by weight of HPF AD1035, 20% by weight of HPF2000, and 20% by weight of additives, fillers, and melt flow modifiers. In some embodiments, the relative percentages of HPF AD1035, HPF2000, and additives, fillers, and melt flow modifiers may change, with HPF2000 ranging from 0% to 100% by weight of the composition, HPF AD1035 ranging from 0% to 100% by weight of the composition, and/or additives, fillers, and melt flow modifiers ranging from 0% to about 25% by weight of the composition.
In a particular embodiment, inner core 102 may comprise a blend of highly neutralized polymers, at least one ionomer and optionally weight fillers for adjusting the mass and specific gravity of the ball to desired levels. An inner core may comprise from about 40% to about 85% by weight of a first highly neutralized polymer (such as HPF AD1035), from about 0% to about 45% by weight of a second highly neutralized polymer (such as HPF 2000), about 2% to about 8% by weight of an ionomer (such as Surlyn), and about 0% to about 15% by weight BaSO₄additives.
Inner core 102 may generally have any hardness value. In some embodiments, the hardness is the same throughout the entire cross-section of inner core 102, as the inner core 102 may be substantially homogeneous.
Generally, the hardness of inner core 102 may be adjusted by changing the relative amounts of a first highly neutralized polymer and a second highly neutralized polymer. For example, a first highly neutralized polymer may have a first hardness, and a second highly neutralized polymer may have a second hardness. Then, the two highly neutralized polymers may be mixed together to form a mixture having a hardness that is between the first hardness and the second hardness, depending on the relative proportions thereof.
More particularly, in embodiments where inner core 102 is comprised of a mixture of two or more types of highly neutralized polymers, the relative amounts of each type of highly neutralized polymer may affect the cross-sectional hardness. Namely, as the percentage of HPF AD1035 relative to HPF2000 increases, the hardness generally decreases. The relationship of cross-sectional hardness to percentage HPF AD1035 is generally linear. In some embodiments, if H is the cross-sectional hardness and P is the percentage of HPF AD1035 in the inner core composition, the relationship between H and P, when HPF AD1035 is blended with HPF2000, is given by the following equation, Eq. 1, within standard engineering/manufacturing tolerances: H=78-0.12 P. This equation is valid when no masterbatch is used.
Suitable additives and fillers for use with a highly neutralized polymer composition in inner core 102 may include, for example, blowing and foaming agents, optical brighteners, coloring agents, fluorescent agents, whitening agents, UV absorbers, light stabilizers, defoaming agents, processing aids, mica, talc, nanofillers, antioxidants, stabilizers, softening agents, fragrance components, plasticizers, impact modifiers, acid copolymer wax, surfactants. Suitable fillers may also include 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. Suitable fillers may also include high specific gravity metal powder fillers, such as tungsten powder and molybdenum powder. Suitable melt flow modifiers may include, for example, fatty acids and salts thereof, polyamides, polyesters, polyacrylates, polyurethanes, polyethers, polyureas, polyhydric alcohols, and combinations thereof.
In some of the embodiments, inner core 102 may have a diameter of between 20 mm and 35 mm, or between about 24 mm and about 30 mm. FIG. 1 shows radius 202, which is half of this diameter value. In particular embodiments, a diameter of inner core 102 may be about 24 mm. In other embodiments, a diameter of inner core 102 may be about 28 mm. In further embodiments, a diameter of inner core 102 may be between about 28 mm and about 30 mm. Such embodiments may achieve advantageous durability while having no detrimental impact on driver distance.
Next, FIG. 1 shows outer core 104. Outer core 104 is located radially outward of inner core 102, and outer core 104 substantially surrounds inner core 102.
Outer core 104 in some embodiments may have a thickness 204 of at least 4.8 mm. In embodiments where inner core 102 is made of a highly neutralized polymer composition having a diameter ranging from 20 mm to 28 mm, if the thickness of outer core 104 is less than about 4.8 mm, the golf ball may not have sufficient durability. Internal durability may be preferable when the thickness of outer core 104 ranges from 5.0 mm to 8 mm.
In some embodiments, the diameter of the core (inner core 102 and outer core 104 together) may range from about 34 mm to about 40 mm. In embodiments where inner core 102 is made of a highly neutralized polymer composition having a diameter ranging from greater than 28 mm to less than 40 mm, outer core 104 thickness 204 may be selected to maintain an overall core diameter of 34 mm to 40 mm. In any of the embodiments described herein, outer core 104 thickness 204 may be selected to have a conforming golf ball, where the total diameter of the confirming golf ball is not less than 1.68 inches.
Outer core 104 may be made using any material, but in some embodiments may be made of a thermoset polybutadiene rubber. In some embodiments, outer core 104 may be generally formed by crosslinking a polybutadiene rubber composition as described in U.S. Pat. No. 8,193,296, entitled Golf Balls Including Crosslinked Thermoplastic Polyurethane, the disclosure of which is hereby incorporated by reference in its entirety.
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. The filler may be used to alter the specific gravity of the material. 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. 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 the outer core may be from about 1.05 to about 1.45. In some embodiments, the specific gravity of the outer core may be from about 1.05 to about 1.35.
In some embodiments, a polybutadiene synthesized with a rare earth element catalyst may be used to form outer core 104. Such a polybutadiene may provide excellent resilience performance of the golf ball. Examples of rare earth element catalysts include lanthanum series rare earth element compound, organoaluminum compound, and almoxane and halogen containing compounds. Polybutadiene obtained by using lanthanum rare earth-based catalysts usually employs a combination of a lanthanum rare earth (atomic number of 57 to 71) compound, such as a neodymium compound.
In some embodiments, a polybutadiene rubber composition having at least from about 0.5 parts by weight to about 5 parts by weight of a halogenated organosulfur compound may be used to form the outer core. In some embodiments, the polybutadiene rubber composition may include at least from about 1 part by weight to about 4 parts by weight of a halogenated organosulfur compound. The halogenated organosulfur compound may be selected from the group consisting of pentachlorothiophenol; 2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol; 2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol; 3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol; 2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol; pentafluorothiophenol; 2-fluorothiophenol; 3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol; 2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol 2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol; 2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol; 4-chlorotetrafluorothiophenol; pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol; 2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol; 2,3,5,6-tetraiodothiophenol; pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol 4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol; 3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol; 3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol; and their zinc salts, the metal salts thereof and mixtures thereof.
Outer core 104 may be made by any suitable process. For example, in some embodiments, outer core 104 may be made by a compression molding process. The process of making outer core 104 may be selected based on a variety of factors. For example, the process of making outer core 104 may be selected based on the type of material used to make outer core 104 and/or the process used to make the other layers.
In some embodiments, outer core 104 may be made through a compression molding process including a vulcanization temperature ranging from 130° C. to 190° C. and a vulcanization time ranging from 5 to 20 minutes. In some embodiments, the vulcanization step may be divided into two stages: (1) the outer core material may be placed in an outer core-forming mold and subjected to an initial vulcanization so as to produce a pair of semi-vulcanized hemispherical cups and (2) a prefabricated inner core may be placed in one of the hemispherical cups and may be covered by the other hemispherical cup and vulcanization may be completed. In some embodiments, the surface of inner core 102 placed in the hemispherical cups may be roughened before the placement to increase adhesion between the inner core and the outer core. In some embodiments, inner core surface may be pre-coated with an adhesive before placing the inner core in the hemispherical cups to enhance the durability of the golf ball and to enable a high rebound.
Generally, the hardness of a rubber compound may be changed by varying the amount of cross-linking agent, such as zinc diacrylate (ZDA) or a peroxide. Varying the cross-linking agent to achieve a particular desired hardness level for the rubber is within the skill of one having ordinary skill in the art of golf ball manufacturing.
Third, FIG. 1 shows mantle layer 106. Mantle layer 106 is located radially outward of outer core 104 and generally surrounds and encloses outer core 104.
In some embodiments, the mantle layer is made from a thermoplastic material including at least one of an ionomer resin, a highly neutralized polymer composition, a polyamide resin, a polyester resin, and a polyurethane resin. In some embodiments, the mantle layer is Surlyn®. In some embodiments, the Surlyn used in the mantle layer is normal acid, having an acid content that does not exceed about 15% by weight. In some embodiments, the Surlyn used in the mantle layer is high acid, having an acid content of between 15% and 50% by weight. In some embodiments, the high acid Surlyn of the mantle layer has an acid content of about 20% by weight.
Mantle layer 106 may have any desired thickness 206. In some embodiments, mantle layer thickness 206 may be selected so that the golf ball is a conforming golf ball. In some embodiments, mantle layer thickness 206 is between 0.5 and 1.3 mm. In some embodiments, mantle layer thickness 206 is between about 0.95 mm and about 1.2 mm. In some embodiments, mantle layer thickness 206 is between about 0.5 mm and 0.95 mm. In some embodiments, mantle layer thickness 206 is about 0.6 mm. In some embodiments, mantle layer thickness 206 is about 0.95 mm. In some embodiments, mantle layer thickness 206 is about 1.2 mm.
The combination of acid level and thickness for the mantle layer may impact performance. In some embodiments, the mantle layer material is normal acid and has a thickness of about 0.95 mm. In some embodiments, the mantle layer material is high acid and has a thickness of about 0.95 mm. In some embodiments, the mantle layer material is high acid and has a thickness of about 1.2 mm. In some embodiments, the mantle layer material is normal acid and has a thickness of about 1.2 mm. In some embodiments, the mantle layer material is normal acid and has a thickness of about 0.6 mm. In some embodiments, the mantle layer material is high acid and has a thickness of about 0.6 mm.
Generally, the hardness of mantle layer 106 may be adjusted by varying the proportions of the stock materials used to form it. That is, in some embodiments, mantle layer 106 may be formed of a mixture of two or more stock Surlyn materials. In such embodiments, the hardness of mantle layer 106 may be adjusted by changing the relative amounts of a first Surlyn ionomer and a second Surlyn ionomer, and additional Surlyn ionomer(s) if applicable. For example, a first Surlyn ionomer may have a first hardness, and a second Surlyn ionomer may have a second hardness. Then, the two Surlyn ionomers may be mixed together to form a mixture having a hardness that is between the first hardness and the second hardness, depending on the relative proportions thereof. Generally, the amount of additives does not substantially affect the hardness of a mixture of two or more Surlyn ionomers. In some embodiments, mantle layer 106 may be a mixture of one or more of DuPont's Surlyn ionomers S9150, S8150, and S9320.
Finally, FIG. 1 shows cover layer 108. Cover layer 108 is located radially outward of mantle layer 106, and substantially surrounds mantle layer 106.
Cover layer 108 may be made of any material known in the golf ball art, including but not limited to ionomers such as Surlyn®, urethanes, thermoplastic polyurethanes, balata, and combinations of these materials. In some embodiments, outer cover layer 108 is made from a crosslinked thermoplastic polyurethane material that is a blend of PTMEG, BG, TMPME, DCP, and MDI in varying percentages by weight. “PTMEG” is polytetramethylene ether glycol, having a number average molecular weight of 2,000, and is commercially available from Invista, under the trade name of Terathane® 2000. “BG” is 1,4-butanediol, commercially available from BASF and other suppliers. “TMPME” is trimethylolpropane monoallylether, commercially available from Perstorp Specialty Chemicals AB. “DCP” is dicumyl peroxide, commercially available from LaPorte Chemicals Ltd. “MDI” is diphenylmethane diisocyanate, commercially available from Huntsman, under the trade name of Suprasec® 1100. Specifically, these materials may be prepared by mixing the components in a high agitated stir for one minute, starting at a temperature of about 70° C., followed by a 10-hour post curing process at a temperature of about 100° C. The post cured polyurethane elastomers may be ground into small chips.
Other suitable outer cover layer compositions are disclosed in the following patent documents, each of which is incorporated herein in its entirety:
US Patent Publication Number US-2012-0004050, currently U.S. patent application Ser. No. 12/829,131 to Yasushi Ichikawa et al., filed on Jul. 1, 2010 under the title “Golf Ball Incorporating Thermoplastic Polyurethane”;
US Patent Publication Number ______, currently U.S. patent application Ser. No. 13/341,544 to Thomas J. Kennedy III, filed on Dec. 30, 2011 under the title “Ionomer/Polyamide Alloy for Golf Balls”; and
US Patent Publication Number ______, currently U.S. patent application Ser. No. 13/342,551 to Yasushi Ichikawa et al., filed on Jan. 3, 2012 under the title “Over-Indexed Thermoplastic Polyurethane Elastomer, Method of Making, and Articles Comprising The Elastomer”.
Cover layer 108 may be manufactured using any known technique, including but not limited to injection molding, RIM, and compression molding.
Cover layer 108 may have specific hardness ranges or values. These hardness values may be expressed as either the plaque hardness of the material making up cover layer 108, as measured by ASTM D-2240, or as the cover layer hardness “on the ball”, that is measured in accordance with ASTM D-220 except that the measurement is taken on the curved surface of the finished ball on a fret between adjacent dimples.
In one embodiment, cover layer 108 may be made from a material having a plaque hardness of at least 44 Shore D. In another embodiment, cover layer 108 may be made from a material having a plaque hardness of from about 44 to about 50 Shore D. In another embodiment, cover layer 108 may be made from a material having a plaque hardness of from about 46 to about 50 Shore D. In another embodiment, cover layer 108 be made from a material having a plaque hardness of from about 46 Shore D.
In yet another embodiment, cover layer 108 may have a hardness on the golf ball of from about 60 to about 70 D. In particular embodiment, cover layer 108 may have a hardness on the golf ball of about 64.5 Shore D. In another embodiment, cover layer 108 may have a hardness on the golf ball in a range of from about 60 to about 70 Shore D, or from about 62 to about 68 Shore D, or from about 63 to about 66 Shore D. In yet still another embodiment, cover layer 108 and mantle layer 106 have a ball hardness difference of less than 10 Shore D.
In a particular embodiment, cover layer 108 may be formed of a thermoplastic polyurethane while having the above discussed hardness ranges and values. Further aspects of the cover layer are shown with respect to the examples, below.
Thickness 208 of cover layer 108 may be any desired thickness. In some embodiments, the thickness 208 may be selected to allow golf ball 100 to be a conforming golf ball. In some embodiments, the thickness 208 may be selected to enhance the feel of golf ball 100. In some embodiments, thickness 208 may be between about 0.5 mm to about 1.5 mm. In some embodiments, thickness 208 may be about 1.10 mm. While in some embodiments, thickness 208 may be greater than thickness 206.
Golf balls according to this disclosure are provided with dimples on the outer cover layer to enhance the aerodynamic performance of the golf ball. Any number of dimples having any shape and depth and in any pattern known in the art may be provided on cover layer 108. In some embodiments, between 200 and 500 dimples may be provided. In some embodiments, between 300 and 400 dimples may be provided. In some embodiments, between 320 and 350 dimples may be provided.
In some embodiments, one or more coating layers may be applied to cover layer 108. The coating layer(s) may be provided for any reason, such as for altering a hardness of the cover layer 108, altering the aerodynamics of golf ball 100, enhancing the visibility of golf ball 100, and for aesthetic purposes. The coating may be any type of coating known in the art, including but not limited to paints, inks, clear coats, urethane coatings, sparkle coatings, and the like. The coating may be applied using any method known in the art, including but not limited to spraying, stamping, pad printing, brush applications, combinations of these techniques, and the like.
Once assembled, golf balls according to the present disclosure will exhibit various characteristics based upon the construction. Some of these characteristics include a ball COR, a ball weight, and a ball compression.
In particular, golf balls according to the present disclosure having cover layers with increased hardness may achieve desirable lower rates of backspin.
This disclosure may be particularly understood in view of the following examples, which are not intended to limit the scope of this disclosure.

EXAMPLES

Examples E1 through E12 and comparative examples C1 through C19 were prepared as discussed below and as shown in Table 1. The results of testing examples E1 through E12 and comparative examples C1-C19 are shown in Table 2 through Table 4.
Generally, all samples were allowed to age at least 8 weeks after manufacturing before testing. All samples were incubated at approximately 23 C with 0% humidity for 24 hours prior to conducting the test.
Table 1 below shows the construction for several comparative examples:

TABLE 1

	Inner Core	Inner Core		Mantle	Cover
Example #	Material	Size	Outer Core	Layer	layer	Dimple

C6	75% AD1035	28 mm	Rubber - normal	51D	40D	N12
C7	50% AD1035	28 mm	Rubber - normal	58D	40D	N12
C8	50% AD1035	28 mm	Rubber - slightly	51D	43D	N12
			softer
C9	50% AD1035	28 mm	Rubber - normal	51D	43D	N12
C10	50% AD1035	28 mm	Rubber - slightly	51D	40D	N12
			softer
C18
	100% AD1035	28 mm	Rubber - normal	65D	40D	N12

Generally, each inner core was made from a composition including one or more highly neutralized polymers. Specifically, the inner cores were a mixture of HPF AD1035 and HPF2000, with minor amounts of additional Surlyn ionomer added, as well as BaSO₄additives for weight. The varying values of the hardness were achieved by varying the relative amounts of AD1035 and HPF2000.
Each outer core was made from a composition of neodymium-catalysed butadiene rubber (“Nd-BR”). BaSO₄was added to the outer core to add weight in sufficient amount to meet the USGA mass limitations of the ball. Varying hardnesses of the outer core were achieved by varying the amounts of ZDA or peroxide.
Each mantle layer was made from DuPont's commercially available Surlyn. The Surlyn used was a mixture of DuPont's S9150, S8150, and S9320. The varying values of the hardness of the mantle layers was achieved by varying the relative proportions of S9150, S8150, and S9320. Each example mantle layer was made from DuPont's commercially available Surlyn. The Surlyn used was a mixture of DuPont's S9150, S8150, and S9320. The varying values of the hardness of the mantle layers was achieved by varying the relative proportions of S9150, S8150, and S9320. Descriptions of various mantle layer formulations are provided in U.S. patent application No. 12/627,992 filed on Nov. 30, 2009, and published as U.S. Patent Application Number US-2011-0130220-A1, the contents of which is hereby incorporated by reference.
Each cover layer was made from a thermoplastic polyurethane. Examples of such are described in U.S. patent application No. 13/342,551 mentioned previously.
Table 2 shows the results of a first Driver Test. The driver test was conducted in the following manner: 12 samples of each finished golf ball were hit outdoors with a Golf Labs robot. The tee was approximately 2 inches forward of the center of robot and the ball impacted the driver face centered left to right and approximately half an inch above the center point of the face. The head speed was approximately 89 mph. The driver used was a VR Pro 9.5 degree loft with an extra stiff shaft. The trackman net system (radar based launch monitor) was used to gather the data.

TABLE 2

Driver Test 1

	Cover Layer	Initial	Launch	Backspin
Example	Hardness	Velocity (mph)	Angle (°)	(rpm)

E1	46D	172.9	10.3	2719
E2	46D	172.7	10.1	2776
E3	46D	171.7	10.1	2831
E4	46D	172.0	10.1	2800
E5	46D	172.3	10.0	2762
E6	46D	172.8	10.1	2773
C1	40D	171.1	9.7	3148
C2	40D	171.3	9.7	3090
C3	43D	171.4	9.8	3028
C4	43D	172.7	10.1	2837
C5	40D	172.2	9.8	2952
C6	40D	172.1	9.7	3071
C7	40D	173.3	9.7	3091
C8	43D	172.5	9.8	3122
C9	43D	173.1	9.7	3090
C10	40D	172.4	9.5	3240

The data of Table 2 is show in the chart of FIG. 2.
Table 3 shows the results of a second driver test. The second driver test was conducted in the same manner as the first driver test.

TABLE 3

Driver Test 2

E7	46D	144.6	12.4	2576
E8	46D	144.1	12.7	2530
E9	46D	144.2	12.7	2479
E10	46D	144.7	12.7	2564
E11	46D	144.6	12.5	2496
E12	46D	144.0	12.6	2484
E13	46D	144.7	12.3	2688
E14	46D	144.7	12.4	2525
E15	46D	144.8	12.5	2562
C11	40D	144.7	12.2	2703
C12	43D	144.7	12.2	2796
C13	40D	144.3	12.4	2715
C14	40D	144.2	12.3	2628
C15	43D	144.2	12.3	2640

The data of Table 3 is shown in the chart of FIG. 3.
Table 4 shows the results of a test using a seven iron. The seven iron test was conducted in the same manner as the first driver test, except that a seven iron club was used instead of a driver.

TABLE 4

Seven Iron Test - 6/7 GL 7 Iron

	Cover Layer	Initial	Launch
Example	Hardness	Velocity (mph)	Angle	Backspin

E7
	46D Cover	108.1	18.0	6977
E8	46D Cover	108.5	18.2	6955
E9	46D Cover	108.4	18.4	6797
E10	46D Cover	108.6	18.3	6830
E11	46D Cover	108.7	18.2	6762
E12	46D Cover		108..5	18.7	6636
C16	40D Cover	107.9	17.7	7326
C17	43D Cover	107.9	17.8	7199
C18	40D Cover	108.3	18.0	7052
C19	43D Cover	108.3	17.9	7084

The data of Table 3 is shown in the chart of FIG. 4.
As can clearly be seen in FIGS. 2-4, the example golf balls having a hard cover layer generally achieve lower backspin and increased launch angles as compared to similar golf balls having softer cover layers. The example golf balls in accordance with this disclosure may therefore be preferred by golfers desiring lower spin and longer total distances off the tee.
While various embodiments of the disclosure have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the disclosure. Accordingly, the disclosure is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.

Claims

What is claimed is:

1. A golf ball comprising:

an inner core, the inner core encompassing a center of the golf ball and being comprised of a highly neutralized polymer;

an outer core, the outer core being positioned radially outward of the inner core and substantially surrounding the inner core;

a mantle layer, the mantle layer being positioned radially outward of the outer core and substantially surrounding the outer core; and

a cover layer, the cover layer being positioned radially outward of the mantle layer and substantially surrounding the mantle layer;

wherein the cover layer is made from a material having a plaque hardness of at least about 44 Shore D.

2. The golf ball according to claim 1, wherein the cover layer is made from a material having a plaque hardness of from about 44 to about 50 Shore D.

3. The golf ball according to claim 1, wherein the cover layer is made from a material having a plaque hardness of from about 46 to about 50 Shore D.

4. The golf ball according to claim 1, wherein the cover layer comprises a thermoplastic polyurethane.

5. The golf ball according to claim 4, wherein the cover layer has a hardness on the ball in a range of from about 60 to about 70 Shore D.

6. The golf ball according to claim 4, wherein the cover layer has a hardness on the ball in a range of from about 63 to about 66 Shore D.

7. The golf ball according to claim 4, wherein the golf ball has a launch angle of at least 10.0 degrees, and a back spin of less than 3,000 rpm.

8. The golf ball according to claim 1, wherein the mantle layer comprises a high acid ionomer.

9. The golf ball according to claim 8, wherein the inner core comprises a mixture of at least two different types of highly neutralized polymers.

10. The golf ball according to claim 8, wherein the mantle layer has a thickness that is less than a thickness of the cover layer.

11. A golf ball comprising:

an outer core, the outer core being positioned radially outward of the inner core and substantially surrounding the inner core, the outer core being comprised of a thermoset polybutadiene rubber;

a mantle layer, the mantle layer being positioned radially outward of the outer core and substantially surrounding the outer core, the mantle layer being comprised of an ionomer; and

a cover layer, the cover layer being positioned radially outward of the mantle layer and substantially surrounding the mantle layer, the cover layer being comprised of a thermoplastic polyurethane;

wherein the cover layer is made from a material having a plaque hardness of from about 44 to about 50 Shore D.

12. The golf ball according to claim 11, wherein the cover layer is made from a material having a plaque hardness of from about 46 to about 50 Shore D.

13. The golf ball according to claim 11, wherein the cover layer is made from a material having a plaque hardness of about 46 Shore D.

14. The golf ball according to claim 11, wherein the outer core has a thickness of at least 4.8 mm.

15. The golf ball according to claim 11, wherein the inner core has a diameter of about 28.25 mm, the outer core has a thickness of about 5.20 mm, the mantle layer has a thickness of about 0.95 mm, and the cover layer has a thickness of about 1.10 mm.

16. The golf ball according to claim 11, wherein the inner core comprises a blend of two highly neutralized polymers.

17. The golf ball according to claim 11, wherein the thermoplastic polyurethane of the cover layer is a crosslinked thermoplastic polyurethane.

18. The golf ball according to claim 11, wherein the cover layer and the mantle layer have a ball hardness difference of less than 10 Shore D.

19. The golf ball according to claim 12, wherein the inner core has a diameter of from about 20 mm to about 30 mm.

20. The golf ball according to claim 16, wherein the mantle layer has a thickness that is less than a thickness of the cover layer.