WO2000074794A1 - Three piece distance golf ball with dimples - Google Patents

Abstract

A three piece golf ball (1) has a center compression in the range of about 40 PGA to 60 PGA, a center (5) weight in the range of about 27.5 grams to 28.5 grams, a core (6) compression in the range of about 60 PGA to 80 PGA, a core weight in the range of about 34.5 grams to 35.5 grams, a cover (2) hardness in the range of 63 to 69 Shore D, and an ionomer cover composition wherein the ionomer mixture comprises a blend of about 75 % by weight of a high resilience ionomer and about 25 % by weight of a very low modulus ionomer. In addition, the present invention provides a golf ball (1) having a plurality of dimples (200, 202, 204), of about 402 in number, arranged on its outer surface, selected from two sets of dimples, the first set having a single radius cross section, and the second set having a dual radius cross section. The dimple configuration of the instant invention is based on the geometry of a rhombicosadodecahedron. A ball having such characteristics exhibits superior distance performance without compromising shot-making feel.

Description

THREE PIECE DISTANCE GOLF BALL WITH DIMPLES

CROSS-REFERENCE TO RELATED APPLIATIONS

A claim of benefit is made to U.S. Provisional Application Serial No.

60/138,078 filed June 8, 1999, the contents of which are incorporated herein by

reference. This is a continuation -in -part application of the provisional application filed June 8, 1999, the contents of which are incorporated herein by

reference.

BACKGROUND OF THE INVENTION

The instant invention is directed to golf balls, and more particularly to a ball having the optimal cover hardness, cover composition, size of thread

windings, center compression, center weight, center diameter, and dimple

configuration to provide superior play ability capabilities with respect to softness

and spin without sacrificing superior distance capabilities.

DESCRIPTION OF THE PRIOR ART

It is well known in the golf industry that the distance a ball travels is one

of the key features that distinguish one ball from the next. In the golf ball

business, distance sells.

There are a number of physical properties that affect the performance of a

golf ball. The core of the golf ball is the source of the ball's major elastic properties.

In a three-piece golf ball, the core is comprised of the center and thread windings layer of the golf ball. Among other things, the core affects the ball's "feel" and its initial velocity. The initial velocity is the velocity at which the golf ball travels

immediately following impact. The initial velocity can be grouped with launch angle and spin to describe the ball's initial conditions, or the conditions exhibited

by the ball immediately after impact. The initial conditions along with dimple pattern determine the ball's trajectory and ultimately its distance. The "feel" is the

overall sensation transmitted to the golfer through the golf ball at impact. The

overall construction of the ball influences the "feel" of a golf ball. Properties such as cover hardness, compression, and rebound can be used to gauge the response of a golfer to a ball's construction. But ultimately, the ball's "feel" can only be determined by the avid golfer. One property commonly tested by golfers to judge

the "feel" of a ball is the sound made at impact between the ball and the club. This

sound or "click" provides the golfer with a lasting impression of the ball's feel.

Generally, lower cover hardness, compression, and rebound give the golfer an

impression of a softer "feel" and a corresponding lower, softer click.

Until the late 1960's, most golf balls were constructed with a thread

wound core and a cover of compounds based on natural balata and gutta

percha or synthetic transpolyisoprene. These golf balls have been and are still known to provide good flight distance. Additionally, due to the relative

softness of the balata cover, skilled golfers can impart various spins on the ball in order to control the ball's flight path (e.g., "fade" or "draw") and "bite"

characteristics upon landing on a green. "Fade" is a term used in golf to describe a particular golf ball flight

path that is characterized by a curved or arched flight exhibited towards the

latter portion of the flight path that veers off from the center line of the initial

flight path to the opposite side from which the golfer stands. Upon contact with the ground, a ball hit with a "fade" will stop in a relatively short

distance. This is a result of an open club face at impact imparting more spin

and a higher trajectory than normal.

"Draw" is the term used in golf to describe a particular golf ball flight

path that is characterized by a curved or arched flight exhibited towards the

latter portion of the flight path that veers off from the center line of the initial

flight path to the same side on which the golfer stands. Upon contact with

the ground, a ball hit with a "draw", unlike that of a ball hit with a "fade",

will roll for a considerable distance. This is a result of a closed club face at

impact imparting less spin and a lower trajectory than normal.

"Check" or "bite" is the term used in golf to describe the effect of

imparting a substantial amount of backspin to an approach shot into a green

that causes the golf ball to stop abruptly upon contact with the green.

Another desirable feature of balata-based compounds is that they are

readily adaptable to molding. These compounds therefore can be compression

molded about a spherical core to produce golf balls.

Though possessing many desirable properties, there are substantial

drawbacks to use of balata or transpolyisoprene-based compounds for golf ball

covers. From a manufacturing standpoint, balata-type materials are expensive and the manufacturing procedures used are time consuming and labor-intensive,

thereby adding to the material expense. From a player's perspective, golf balls

constructed with balata-based covers are very susceptible to being cut from mishits and being damaged from sharp grooves on a club face. As a result, they

have a relatively short life span.

In response to these drawbacks to balata-based golf ball covers, the golf

ball manufacturing industry has shifted to the use of synthetic thermoplastic

materials, most notably ionomers sold by E. I. DuPont De Nemours & Company

under the name SURLYN^®. Surlyn is an ionomeric resin that is an ionic

copolymer of an olefin having from about 2 to about 8 carbon atoms, such as

ethylene, and a metal salt of an alpha, beta-ethylenically unsaturated mono- or

dicarboxylic acid such as acrylic acid, methacrylic acid, or maleic acid. The

pendent ionic groups in the ionomeric resins interact to form ion-rich aggregates

contained in a non-polar polymer matrix. Metal ions, such as sodium, zinc, or

lithium are used to neutralize some portions of the acid groups in the copolymer

resulting in a thermoplastic elastomer exhibiting enhanced properties such as

improved durability.

Thread wound balls with ionomer covers are less costly to manufacture

than balls with balata covers. They are more durable and produce satisfactory

flight distance. However, these materials are relatively hard compared to balata

and thus lack the "feel" of a balata covered golf ball.

In an attempt to overcome the negative factors of the hard ionomer covers,

DuPont introduced low modulus SURLYN^® ionomers in the early 1980's. These SURLYN^® ionomers have a flexural modulus of from about 3000 to about 7000

PSI and hardness of from 25 to about 40 as measured on the Shore D scale -

ASTM 2240. The low modulus ionomers are terpolymers, typically of ethylene,

methacrylic acid and n or iso-butylacrylate, neutralized with sodium, zinc,

magnesium or lithium cations. E.I. DuPont De Nemours & Company has

disclosed that the low modulus ionomers can be blended with other grades of

previously commercialized ionomers of high flexural modulus from about 30,000

to 55,000 PSI to produce balata-hke properties. However, "soft" blends, typically

52 Shore D and lower (balata-hke hardness), do not exhibit good physical

properties and are prone to cut and shear damage.

The low modulus ionomers when used without high stiffness blends

produce covers with very similar physical properties to those of balata, including

poor cut and shear resistance. Worse, wound balls with these covers tend to go

"out-of-round" quicker than wound balls with balata covers. Blending with hard

SURLYN^® ionomers was found to improve these properties.

Historically, in addition to manipulating the cover composition of a golf

ball, golf ball manufacturers have also varied the size and winding conditions of

the thread windings layer as well as the weight of the center in three-piece golf

balls in an effort to design a golf ball with superior ball performance. Vaiious

efforts have been made to select the optimal winding pattern as well as the ideal

thread dimension and winding tension.

For many years golf ball manufacturers have also investigated changing

dimple configurations in an effort to design a ball with superior distance capabilities. Dimples are the surface indentations or depressions on a golf ball. Specifically, ball manufacturers have looked to dimple configurations in an effort

to design a ball with superior distance capabilities. Many efforts have been made

to select the optimum number, size and shape of dimples as well as their

disposition around the outer surface of a generally spherically shaped golf ball.

However, a problem with the prior art dimple configurations is that they fail to

take into account other features of the ball, such as core size, core compression and cover hardness, which also influence how far a ball will travel.

Dimples on golf balls are typically circular in elevation cross section, but a number of other designs are also utilized, including truncated cones, dimples

within dimples, elliptical surfaces, hemispherical (or single radius) dimples, and

dual radius dimples. For example, U.S. Patent No. 4,979,747 shows dimples

having a frusto-contical elevation view cross section, and U.S. Pat. No. 5,005,838

shows dimples having complex shapes.

Different dimple shapes have different aerodynamic properties, and

therefore, result in different performance characteristics. For example, a single

radius dimple provides a more gradual entry of the airflow into the dimple, while a dual radius dimple provides a more abrupt entry of the airflow into the dimple. (A

single radius dimple is one in which the elevation cross sectional shape of the

dimple can be described by one radius, and dual radius dimple is one in which the

elevation cross section is described by two radii.)

Generally, it has been found that the single radius dimple is the most

optimal dimple shape for a high performance three-piece wound golf ball. By contrast, the dual radius dimple is the most optimal shape design for two-piece distance balls for providing the desired golf ball flight trajectory. These dimple

choices are based on the current view that the higher spinning performance balls

require a more gradual entry of the airflow into the dimple to create the desired aerodynamic effects, whereas the low spinning distance ball requires a more

abrupt entry of the airflow into the dimple to create the desired aerodynamic effect.

There are a number of hybrid type balls which do not fall squarely within either the three-piece performance category or the two-piece distance category. For

example, two-piece performance balls and three-piece distance balls are hybrid balls which behave like performance balls for certain shots and like distance balls

for other shots. As used herein the term "hybrid ball" is used to refer to a two piece

performance ball, a three-piece distance ball, or any other ball which behaves like a

performance ball for certain shots and like a distance ball for other shots.

It has been found, for instance, that a dimple pattern utilizing dual radius

dimples allows for a lower more boring trajectory for a distance two-piece ball,

whereas a pattern utilizing single radius dimples allows for a more consistent flight trajectory for high performance three-piece balls.

A need exists for a dimple pattern (and dimple shape) which takes into

account the unique characteristics of the hybrid ball (i.e. the fact that it performs

as a distance ball for certain shots, and as a performance ball for other shots) to

provide optimum performance. The goal is to provide a ball that (i) provides shghtly longer overall distance than a ball utilizing either all single radius dimples or all dual radius dimples, and (ii) has a significantly lower trajectory, as exhibited

by the lower rear trajectory value.

As is well known in the art, ball manufacturers are bound by regulations

of the United States Golf Association (USGA) which control many characteristics

of the ball, including the size and weight of the ball, the initial velocity of the ball when tested under specified conditions, the overall distance the ball travels when

hit under specified test conditions, and the ball's aerodynamic symmetry. Under

USGA regulations, the diameter of the ball cannot be less than 1.680 inches, the

weight of the ball cannot be greater than 1.620 ounces avoirdupois, the initial

velocity of the ball cannot be greater than 250 feet per second when tested under

specified conditions (with a maximum tolerance of +2%), the driver distance

cannot exceed 280 yards when tested under specified conditions (with a test

tolerance of +6%), and the ball must perform the same aerodynamically

regardless of orientation. It should be noted that while the USGA sets a limit for

the distance a ball can travel under set test conditions, there is no upper limit on

how far a player can hit a ball.

OBJECT OF THE INVENTION

Accordingly, it is an object of the instant invention to optimize the

combination of center weight, center compression, size and winding conditions of

the windings dimple, configuration, cover composition, and cover hardness to

provide a three-piece golf ball, which travels great distances, and at the same

time complies with USGA regulations. It is another object of the instant invention to provide a three-piece golf ball

that has a soft "feel" in combination with superior distance capabilities.

It is yet another object of the instant invention to provide a three-piece golf

ball having a synthetic cover material that achieves the sound, feel, and playabihty and flight performance qualities of balata covered golf balls.

It is still a further object of the instant invention is to provide a three-piece

golf ball having superior distance, trajectory and flight stability.

Another object of the instant invention is to provide a three-piece golf ball

having a surface divided into a plurahty of polygonal configurations or shapes for the location of dimples for enhancing the aerodynamic properties of the golf ball.

It is yet another object of the present invention to provide a golf ball dimple

pattern that optimizes the performance characteristics of the instant invention.

It is still another object of the present invention to provide a hybrid golf ball that provides a shghtly longer overall distance and a lower trajectory than the prior art hybrid balls.

It is still a further object of the invention to provide a golf ball having a

dimple pattern that incorporates dimples of different sizes to maximize the

aerodynamic qualities for each such dimple shape.

It is yet another object of the present invention to provide a golf ball having superior distance, trajectory and flight stability. SUMMARY OF THE INVENTION

The invention achieves the above-described objectives by providing a three-

piece golf ball having a sohd rubber center, a thread windings layer whose threads

are a large gauge and which is wound in an "open" basket weave pattern, a synthetic ionomer resin cover, and a "rhombicosadodecahedron" dimple pattern.

The ball of the instant invention has a core compression in the range of 60 PGA

to 80 PGA, a center weight in the range of 27.50-28.50 grams, a center size of

between 1.34 to 1.37 inches, an unstressed (not wound) thread dimension of

about 0.024 ± .004 inches height by l/16^th of an inch width, a cover hardness in

the range of about 63 Shore D to about 69 Shore D, and a dimple pattern based

on the geometry of a rhombicosadodecahedron. This combination has been found

to produce a ball with superior distance capabilities and superior play ability

capabilities with respect to softness and spin. The use of these properties in the

golf ball of the instant invention is based on the recognition that it is the

combination of the center size and weight, the size, modulus, and tension of the

thread windings, cover hardness, dimple configuration, dimple size and dimple

shape that will produce a ball that will travel the greatest distance without

compromising shot-making feel.

The golf ball of the present invention has a conventional, sohd rubber

center or rubber sphere. In a preferred embodiment of the invention, the center

has a weight that is shghtly heavier than in golf balls manufactured previously.

The use of a heavier center is necessary in order to attain a golf ball with

sufficient weight to maximize distance and still meet USGA standards. In particular, as mentioned previously, the instant golf ball has a synthetic ionomer

resin cover. This cover has a relatively low specific gravity and as a consequence, a

lower weight. Therefore, to manufacture a ball of sufficient weight, a heavier

center is used.

The thread of the golf ball of the invention is cut from a sheet that is about

0.020 inches to 0.028 inches in thickness or height. A typical thickness is 0.024

inches, which corresponds to a "gauge" of 24. The width of the thread cut for the

instant invention is about l/16^th inch.

It has now been discovered that the combination of a relatively heavy

center with a large gauge thread, of about 0.024 ± 0.004 inches, and having

relatively low Swartz modulus, and width of about l/16^th of an inch (0.063 ±

0.004 inch), wound to promote an "open" winding pattern under a tension in the

range of 925 to 1025 grams of tension produces a ball with improvements in

player characteristics. Specifically, the heavy center surrounded by a thread

windings layer comprised of a large gauge thread wound to an "open" winding

pattern results in a three piece golf ball that spins less than known inventions

when it is hit by a driver, while spinning more when it is hit by a pitching wedge.

Lower spin off the driver is preferable as it increases the total distance attained

from a golf ball.

The use of the relatively large gauge, wide thread, wound to an "open"

winding pattern, allows the ionomer resin into which the thread-wound sohd

rubber center is placed, to penetrate or seep into the thread windings layer to a greater extent than in the prior art balls. The result is a softer-feeling ball than would be attained otherwise.

The cover material can be constructed from any relatively stiff material, for example, synthetic thermoplastic materials. Most notably these synthetic

thermoplastic materials are ionomeric resins. Ionomeric resins are polymers

containing interchain ionic bonding. As is well known in the chemical arts,

ionomeric resins are generally ionic copolymers of an olefin having from about two to about eight carbon atoms, such as ethylene and a metal salt of an unsaturated carboxylic acid, such as acryhc acid, methacrylic acid, or maleic acid. The pendent

ionic groups in the ionomeric resins interact to form ion-rich aggregates contained in a non-polar polymer matrix. Metal ions, such as sodium, zinc or magnesium

are used to neutralize some portion of the acidic groups in the copolymer. This

results in a thermoplastic elastomer, which exhibits enhanced flight characteristics

and durability when compared to golf balls constructed with balata covers.

However, the advantages gained by enhanced durability have been offset by the

decreased playabihty properties.

The ionomers used in the cover composition are sold by E.I. Dupont De Nemours & Company under the name SURLYN^®. In an attempt to overcome the

negative factors of the hard ionomer covers, DuPont introduced low modulus

SURLYN^® ionomers in the early 1980's. These SURLYN^® ionomers have a

flexural modulus of from about 3000 to about 7000 PSI and hardness of from 25

to about 40 as measured on the Shore D scale - ASTM 2240. The low modulus

ionomers are terpolymers, typically of ethylene, methacrylic acid and n or iso- butylacrylate, neutralized with sodium, zinc, magnesium or lithium cations. E.I.

DuPont De Nemours & Company has disclosed that the low modulus ionomers

can be blended with other grades of previously commercialized ionomers of high

flexural modulus from about 30,000 to 55,000 PSI to produce balata-hke

properties. However, soft blends, typically 52 Shore D and lower (balata-hke

hardness), are still prone to cut and shear damage.

The low modulus ionomers when used without high flexural modulus

blends produce covers with very similar physical properties to those of balata,

including poor cut and shear resistance. Worse, wound balls with these covers

tend to go "out-of-round" quicker than wound balls with balata covers. Blending

with hard SURLYN^® ionomers was found to improve these properties.

It has now been discovered that a blend of a high resilience ionomer with an

associated high acid level with a soft ionomers containing low acid level results in a

golf ball cover with improved playabihty characteristics. For the purposes of the

SURLYN^® ionomer resin grade designations, a high acid level is approximately

19% by weight, and a low acid level is approximately 12% by weight.

As mentioned previously, in addition to manipulating the center, thread

windings layer, and cover parameters in a golf ball, superior aerodynamic

properties are also attributed to the dimple configuration on a golf ball. In the

instant invention, the dimples are arranged on the surface of the golf ball based on

the geometry of a rhombicosadodecahedron.

The golf ball of the instant invention has a dimple pattern that incorporates

dimples of different shapes to maximize the aerodynamic properties of the ball. The dimple shapes may be selected from any known dimple shapes, including but not limited to truncated cones, squares, triangles, dimples within dimples, elliptical

surfaces, single radius dimples, and dual radius dimples. The invention allows for

the combination of any of the possible dimple shapes into a single dimple pattern to

allow a more optimized golf ball flight trajectory.

The golf ball of the preferred embodiment is a hybrid ball in which the

dimple pattern on the surface of the ball includes both single radius and dual

radius dimples in order to achieve the most optimal flight performance. This

hybrid ball is allowed to best utilize the aspects of single radius dimples for shots

where it behaves more like a performance three-piece ball, and the aspects of dual

radius dimples for shots where it behaves like a distance ball, while maintaining

good flight performance and control with a combination of both. The ball provides

shghtly longer overall distance, and a significantly lower trajectory than the prior

art hybrid balls. This is a much desired property for this type of ball.

The dimples are arranged by dividing the outer spherical surface of a golf

ball into a plurahty of polygonal configurations, including pentagons, squares and

triangles for locating a plurahty of dimples on the outer surface of the golf ball.

The polygonal configurations of this invention are preferably a combination of

regular pentagons, squares and triangles to cover the outer surface. This first

plurahty of polygonal configurations is generally referred to herein as a

"rhombicosadodecahedron". The rhombicosadodecahedron is further characterized

by a uniform pattern of pentagons formed over the outer surface each bounded by

triangles and squares. The preferred embodiment utilizes a pattern of 402 dimples arranged in the

construction of the rhombicosadodecahedron. A pair of first polygonal

configurations, each located on opposite sides of the outer surface, include one of

the two poles symmetrically arranged within its boundaries. The outer surface has

a plurahty of dimples of different sizes. In one embodiment, the dimples are of

first, second and third sizes and are generally located to have a first pattern

associated with the pentagons, a second pattern associated with the squares, and a

third pattern associated with the triangles.

In another embodiment of the invention, the outer suiface of the golf ball

includes a plurality of parting lines along great circle paths of the ball for further

dividing the first plurahty of polygonal configurations into a second plurahty of

polygonal configurations, each of which are smaller than the polygonal

configurations of the first polygonal configurations. The dimples are arranged over

the outer surface by being associated with both the first and the second plurahty of

polygonal configurations.

The combination of the aforementioned center, thread windings layer, cover

and dimple specifications produces a golf ball that possesses noticeable

improvements in playabihty (i.e. softness in feel) without sacrificing the ball's

durability (i.e. impact resistance etcNThis combination also contributes directly to

the distance that a ball will travel when struck. These and other objects of the

instant invention will be apparent from a reading of the following detailed

description of the instant invention. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross sectional view of a three-piece golf ball made in

accordance with one embodiment of the invention.

Figure 2 is an elevation view of the outer surface of a golf ball being divided

into a plurahty of polygonal configurations according to the invention;

Figure 3 is an elevation view of the golf ball of this invention showing the

relative locations of pentagons, squares

and triangles formed on the outer surface with a pole at the center of a pentagon;

Figure 4 is an equatorial view of the ball of the preferred embodiment of the

present invention, and includes polygons projected thereon.

Figure 5 is a polar view of the ball shown in Fig. 4 and includes polygons

projected thereon.

Figure 6 is a cross sectional view of a single radius dimple;

Figure 7 is a cross sectional view of a dual radius dimple; and

Figure 8 is a cross sectional view cut through one of the dimples on the outer

surface of the ball.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in Fig. 1, the golf ball is comprised of a sohd spherical rubber

center 6, a thread windings layer 4, and a cover 2 to make a three-piece golf ball.

The sohd rubber center 6 together with the thread windings layer 4 comprise the

core 5 of the golf ball. In the preferred embodiment, the golf ball center 6 has a

diameter of about between 1.34 inches to 1.37 inches, preferably 1.354 inches, a PGA compression in the range of about 40 to about 60, and weighs about 27.5

grams to 28.5grams, preferably about 28.0 grams. When combined, the sohd

rubber center 6 and the thread windings layer 4 form the core 5 measuring

approximately 1.565 ± 0.010 inches in diameter, and having a weight of about

35.0 ± 0.5 grams.

The thread windings layer 4 is comprised of thread cut from sheets of

polyisoprene rubber and/or natural rubber and their blends thereof. The

unstressed (unwound) thread dimensions are preferably 0.024 inches thickness

or height and a thread width of about l/16^th inch. The thread windings are

wound in an "open" pattern due to the relatively large size of the thread. The

thread windings are wound under a tension from about 900 grams to 1100

grams, to a thread winding thickness of between 0.092 inches to 0..118 inches,

preferably about 0.105 inches.

The windings layer of the instant invention has a lower density than is

found in other ionomer resin golf balls. Specifically in the preferred embodiment,

the unstressed dimensions for thread used in the windings of the golf ball are

about 0.020 inches to about 0.028 inches in height, preferably about 0.024 inches,

with a width of about 0.059 to about 0.067 inches and preferably l/16th of an

inch. In contrast to a gauge of 24, corresponding to 0.024 inches, the gauge of

threads used in other windings is smaller, 17, or 0.017 inches. Advantageously,

the use of a large gauge (about 24) thread in the winding layer produces a golf

ball that spins less off the driver when compared to a golf ball produced with a

smaller gauge (17) thread. This decrease in spin when the instant ball is hit by a driver occurs as a consequence of the novel construction of a heavy center combined with a thread winding layer that has threads with a lesser density.

The larger gauge used for the threads in the thread windings layer results in a

golf ball that has a more "open" pattern for the windings. Advantageously, this

second design feature for the windings with regard to the "open" winding pattern

allows more reactive ionomer resin to penetrate into the core of the golf ball

during its manufacture.

The winding conditions for the thread windings layer also contribute

significantly to the novel character of the instant ball. In particular, the tension

under which the thread is wound affects the PGA compression of the resultant

golf ball. In the preferred embodiment, the golf ball is wound at a tension in the

range of about 900 grams of tension to about 1100 grams of tension, preferably,

1000 grams of tension. This winding tension produces a golf ball with a core

compression in the range of 60 PGA to 80 PGA, preferably 70 PGA. A core

compression in this range resulting from the unique character of the thread

windings layer, coupled with the heavy center produces a golf ball that is able to

maintain great distance and carry while simultaneously having a flight path

with a lower trajectory. Advantageously, a lower trajectory in the flight path

causes the golf ball to land at an acute angle to the ground. In turn, this acute

landing promotes more roll, and thus the golf ball will travel a greater distance

when it hits the ground.

In the preferred embodiment, the cover has a thickness of about 0.078 ±

0.015 inches to provide a total diameter of center 6, thread windings layer 4 and cover 2 of 1.680 inches, the commercial ball diameter standard specified by the United States Golf -Association.

As discussed previously, the cover material is comprised of ionomer resins available from E.I. du Pont de Nemours & Co. under the name SURLYN^®. In the

preferred embodiment, the ionomers are 75% by weight of SURLYN^® 8140, and

25% by weight of SURLYN^® 9320W. The hardness of the cover 2 is about 66 ± 3

Shore D.

Under the Dupont SURLYN ^® resin classification system, the 8140

SURLYN^® ionomer is classified as a high resilience ionomer. The 8140 SURLYN®

ionomer is defined as a copolymer including approximately 81% of an olefin, most commonly ethylene, and about 19% of an alpha, beta ethylenically unsaturated

caboxyhc acid, such as acrylic or methacryhc acid. Moreover, this ionomer uses the Sodium metal ion to neutralize the acid groups, and, as stated, its acid level is

about 19% by weight, which is considered a high acid level to those skilled in the

art. In turn, this high acid level is associated with a resin characterized by a high

stiffness level. Moreover, the 8140 SURLYN^® grade has no terpolymer. Finally,

the 8140 SURLYN^® resin has a melt index of about 2.6.

The 9320W SURLYN^® resin is classified as a very low modulus ionomer

which has a low acid level of about 12 % by weight, which in turn produces a resin

characterized by a low stiffness level. The 9320W SURLYN® ionomer is comprised of 67-70% by weight of ethylene, 20-21% by weight of n-butyl acrylate, and 12% by

weight of methaciyhc acid. In addition, the 9320W SURLYN^® resin uses the Zinc ion to neutralize the acid groups, and it is a terpolymer. Finally, the 9320W

SURLYN^® resin has a melt index of about 0.7.

In addition to the SURLYN^® resins, the cover composition contains color

concentrate for coloring the golf ball in an amount well known to those skilled in

the art.

Turning now to the dimple technology employed in the instant invention, as

stated previously, the preferred geometry is a rhombicosadodecahedron. The dimple configuration will normally be apphed to the ball during the molding of the

cover around the core by using appropriately shaped compression molding cavitites

common to those skilled in the art. The molded golf ball having the desired dimple

configuration may be then painted. Alternately, painting may be unnecessary for

one-piece golf balls using a cover having a suitable compounding of the composition

used.

Accordingly, the scope of this invention provides a golf ball mold whose molding surface contains a uniform pattern to give the golf ball a dimple

configuration superior to those of the prior art. The invention is preferably

described in terms of the golf ball that results from the mold, but could be described within the scope of this invention in terms of the mold structure that produces a

golf ball.

To assist in locating the dimples on the golf ball, the golf ball 1 of this

invention has its outer spherical surface partitioned by the projection of a plurahty

of polygonal configurations onto the outer surface. That is, the formation or

division that results from a particular arrangement of different polygons on the outer surface of a golf ball is referred to herein as a "plurahty of polygonal configurations." A view of one side of a golf ball 1 showing a preferred division of

the golf ball's outer surface 7 is illustrated in Fig. 2.

In the preferred embodiment, a polygonal configuration known as a

rhombicosadodecahedron is projected onto the surface of a sphere. A rhombicosadodecahedron is a type of polyhedron which contains thirty (30)

squares, twenty (20) polyhedra of one type, and twelve (12) polyhedra of another type. The term "rhombicosadodecahedron" is derived from "dodecahedron,"

meaning a twelve (12) sided polyhedron; "icosahedron," meaning a twenty (20)

sided polyhedron, and "rhombus" meaning a four (4) sided polyhedron.

The rhombicosadodecahedron of the preferred embodiment is comprised of

thirty (30) squares 12, twelve (12) pentagons 10, and twenty (20) triangles 14. It

has a uniform pattern of pentagons with each pentagon bounded by triangles and

squares. The uniform pattern is achieved when each regular pentagon 10 has only

regular squares 12 adjacent to its five boundary lines, and when a regular triangle

14 extends from each of the five vertices of the pentagon. Five (5) squares 12 and five (5) triangles 14 form a set of polygons around each pentagon 10. Two boundary lines of each square 12 are common with two pentagon boundary lines,

and each triangle 14 has its vertices common with three pentagon vertices.

The outer surface of the ball is further defined by a pair of poles and an

equatorial great circle path around the surface. A great circle path is defined by

the intersection between the spherical surface and a plane that passes through the

center of the sphere. An infinite number of great circle paths may be drawn on any sphere. The equatorial great circle path in the preferred embodiment corresponds to a mold parting line that separates the golf ball into two hemispheres. The mold

parting line is located from the poles in substantially the same manner as the

equator of the Earth is located from the North Pole and the South Pole.

Referring to Fig. 3, the poles 70 are located at the center of a pentagon 10 on

the top and bottom sides of the ball, as illustrated in this view of one such side. The

mold parting line 30 is at the outer edge of the circle in this planar view of the golf ball.

Dimples are placed on the outer surface of the golf ball based on segments of the plurahty of polygonal configurations described above. In the preferred

embodiment, three (3) dimples are associated with each triangle 14, five (5)

dimples are associated with each square 12, and sixteen (16) dimples are

associated with each pentagon 10. The term "associated" as used herein in relation

to the dimples and the polyhedra means that the polyhedra are used as a guide for

placing the dimples.

The dimple configuration of the preferred embodiment is shown in Figs. 4-5. It is based on the projection of the rhombicosadodecahedron shown in Fig. 2. The

ball has a total of 402 dimples. The plurahty of dimples on the surface of the ball

are selected from three sets of dimples, with each set having different sized dimples. Dimples 200 are in the first set, dimples 202 are in the second set, and

dimples 204 are in the third set. Dimples are selected from all three sets to form a first pattern associated with the pentagon 10. AU sides 206 of each pentagon 10

are intersected by two dimples 202 from the first set of dimples and one dimple 202 from the second set of dimples. All pentagons 10 have the same general first pattern arrangement of dimples.

Dimples 200, 202 and 204 (from all three sets of dimples) are also used to

form a second pattern associated with the squares 12. All sides 208 of each square

12 are intersected by dimples 202 from the second set of dimples, and all squares

12 have the same general second pattern arrangement of dimples.

Dimples 202 from the second set of dimples form a third pattern associated

with the triangles 14. All sides 210 of each triangle 14 are intersected by a dimple

202 from this second set of dimples. All triangles 14 have this same general third

pattern arrangement of dimples. The mold parting hne 30 is the only dimple free

great circle path on this ball.

The ball of the preferred embodiment utilizes two different types of dimples

having two different cross-sections, single radius dimples 200 and 204 and dual

radius dimples 202. In the single radius dimple (Fig. 6), a single radius (referred to

as a major radius, or Radius 1) describes the shape of the bottom of the dimple. In

other words, the major radius governs the shape of the dimple toward the bottom of

the dimple. In a dual radius dimple (Fig. 7), on the other hand, two radh are used

to describe the shape of the dimple. The major radius describes the bottom of the

dimple, and a minor radius (Radius 2) describes the shape of the dimple about its

circumference.

Dimple size is measured by a diameter and depth generally according to the

teachings of U.S. Patent No. 4,936,587 (the '587 patent), which is included herein

by reference thereto. An exception to the teaching of the '587 patent is the measurement of the depth, which is discussed below. A cross-sectional view

through a typical single radius dimple 6 is illustrated in Fig. 8. The diameter Dd

used herein is defined as the distance from edge E to edge F of the dimple. Edges

are constructed in this cross-sectional view of the dimple by having a periphery 50

and a continuation thereof 51 of the dimple 6. The periphery and its continuation are substantially a smooth surface of a sphere. An arc 52 is inset about 0.003

inches below curve 50-51-50 and intersects the dimple at point E' and F'.

Tangents 53 and 53' are tangent to the dimple 6 at points E' and F' respectively

and intersect periphery continuation 51 at edges E and F respectively. The

exception to the teaching of '587 noted above is that the depth d is defined herein to

be the distance from the chord 55 between edges E an F of the dimple 6 to the

deepest part of the dimple cross sectional surface 6 (a), rather than a continuation

of the periphery 51 of an outer surface 50 of the golf ball.

The dimple dimensions for the preferred embodiment are set forth below:

Dimple (number) Diameter (in) Type Radius Kin) Radius

2(in)

200 (60) .156 Single .4148 NA

202(150) .145 Dual .7874 .1181

204(192) .140 Single .3535 NA

It is understood that the following dimple size ranges are within the scope of this

invention: dimples 200 from the first set may have a diameter in the range of 0.150

inches to 0.160 inches; dimples 202 from the second set may have a diameter in the

range of 0.140 inches to 0.150 inches; dimples 204 from the third set may have a

diameter in the range of 0.135 inches to 0.145 inches; all dimples, 200, 202 and 204 may have a depth in the range of 0.0056 inches to 0.0078 inches; the major radius may be in the range of 0.34 inches to 0.80 inches; and the minor radius (for dimple

202) may be in the range of 0.10 inches to 0.12 inches.

The following test data illustrates the improved performance of the dimple pattern of the present invention. Each of the balls identified below is a hybrid ball.

BALL #DIMPLES PATTERN TYPE CARRY(YDS) TOTALfYDS) REAR TRAJ

BB344 402 all single rad. 247.8 268.0 8.4

BB351 402 all dual rad. 246.3 268.2 8.2

BB370 402 combination 246.6 270.0 8.2

Control 392 all single rad. 245.6 267.5 8.3

As shown above, the ball of the present invention, which utilizes both

single radius and dual radius dimples, provides shghtly longer overall distance

than a ball utilizing either all single radius dimples or all dual radius dimples, and it has a significantly lower trajectory, as exhibited by the lower rear

trajectory value. This is a much-desired property for the hybrid ball.

Turning now to the method of manufacturing the instant golf ball, it is to be appreciated that a preferred embodiment of the golf ball is produced according to

standard methods well known to those skilled in the art. In particular, the sohd

rubber center 6 is manufactured using conventional compression molding

processes. The components are mixed together and extruded to form preforms,

which are then placed in cavities in the mold and are compression molded under

pressure and cured or vulcanized to form centers. The same mix may also be

injection molded. Curing is carried out in the mold at temperatures of 280°F-380°F for five to twenty minutes depending on the compound. Once fully cured, the center 6 is removed from the mold cavities and prepared for apphcation of the

thread windings layer.

In the preferred embodiment, the golf ball center 6 is made of a sohd rubber

composition comprising a polybutadiene rubber center of a composition typical to the industry. Specifically, the rubber may be 90-100 PHR polybutadiene, 0-10

PHR polyisoprene, 15-30 PHR zinc diacrylate, 3-10 PHR zinc oxide, 45-65 PHR

fillers, activators, process aids and antioxidants, and 0.5-5 PHR peroxide initiator. In the preferred embodiment, the diameter of the sohd rubber center 6 is about

1.355 ±0.015 inches. The center 6 weighs about 28.0 ±0.5 grams, and has a compression of about 50 ± 10 PGA.

As is well known in the art, the type and amount of crosslinking agents

used to make the center 6 will have the greatest influence on the center

compression achieved. To prepare the center 6 according to the preferred

embodiment, it has been found that a center composed primarily of high-cis

polybutadiene in combination with cross-hnking agents, activators, initiators

and fillers (active and inactive), can be used to achieve a golf ball center having

the desired compression characteristics. As used herein, high-cis means a cis

isomer content of greater than 93%). It is to be understood that the center

formula set forth herein is but one formula that can be used to make a center

having the desired center compression.

Once formed, the sohd rubber center 6 is then wound with thread windings

in an open pattern with a thread tension from about 900 grams to 1100 grams, wherein the thread windings have an unstressed thread dimension of about l/16^th of an inch width by about 0.020 inches to 0.028 inches height, and a 500%

modulus between 220 to 280 p.s.i.-. The resultant core, 5 is then subjected to a conventional molding process according to standard methods, whereby the SURLYN^® cover 2 is compression molded around the wound core 5 in a manner

well known to those skilled in the art. In the preferred embodiment, compression

molding consists of injecting an ionomer mixture constituting the blended Surlyn®

components into 'half shells'. The core is placed between two 'half shells' and

then placed into a golf ball mold comprising a first mold half and a second mold half, whereby each of the mold halves are larger in dimension than the finished

cover. It should be noted that the inner surfaces of the golf ball mold are

constructed with dimple-shaped projections, which form the dimples in the cover

in a configuration according to the invention as described above.

After molding, the golf balls produced may undergo further processing

steps such as pressure blasting, vibratory finishing, stamping of the logo,

application of a primer, and finally, application of a top coat.

The following examples are provided to illustrate and further explain the

beneficial effects of the ball described above. These examples are set forth for the

purposes of illustrating the advantages obtained with the combination of the center compression, center weight, thread size, thread winding tension, core compression,

core size, cover composition, cover hardness, cover thickness, dimple configuration,

and dimple number that will produce a ball that will travel the greatest distance

without compromising shot-making feel. EXAMPLE 1

Two flight tests were conducted comparing the flight characteristics of the instant invention, i.e., the Three-Piece Distance Golf Ball, known under the trade name as the Maxfli Tour Patriot, with two other golf balls against which it

competes in the marketplace. The golf baUs were hit with a driver and various

parameters were measured and are summarized below.

Example 1

Test #2095 Test # 2217

Ball Driver Driver

Carry (yards) Carry (yards) Total (yards) Total (yards) Spin (rpm) Spin (rpm)

Maxfli Tour Patriot 240.7 246.0 272.1 263.8 2622 2563

Titleist Tour Distance 232.9 237.9 266.5 255.7 2669 2609

Titleist DT Wound 244.2 261.4 Advantageously, as is clearly demonstrated by the test results, the use of a golf ball

configured according to the aforementioned center, core, cover and dimple parameters results in a golf ball, the Three-Piece Distance Golf Ball, which has longer flight characteristics than balls manufactured by competitors.

As was discussed previously, the improvements in ball performance of the invention are due to the combination of changes in the center weight, the size

and winding conditions of the thread, the cover material, and the dimple pattern

of the golf ball. In the invention, the novel manipulation of these parameters

creates a ball that spins less and travels further when hit by a driver, while

being able to spin more and have superior shot-making feel when hit by a

pitching wedge. These two desirable playabihty characteristics are possible in

the instant golf ball due to the unique construction of this ball.

As is known in the art, when a golf ball is hit by a driver, there is great impact force. The whole ball is deformed under this impact force. Consequently,

the entire construction of the ball accounts for its initial launch conditions and

ensuing flight performance. In the instant invention, the critical difference

contributing to the superior distance capability is the center weight, the center

compression, the thread windings layer, the core compression, and the cover

composition in conjunction with the dimple configuration.

While the present invention has been described in connection with

preferred embodiments thereof, it will be apparent to those skilled in the art that

many changes and modifications may be made without departing from the true spirit and scope of the present invention. It is to be understood that the instant invention is by no means hmited to the particular embodiments herein disclosed,

but also comprises any modifications or equivalents within the scope of the

claims. For example, it is understood that the invention is not hmited to a dimple

pattern defined by the rhombicosadodecahedron.

Accordingly, it is intended by the appended claims to cover all such

changes and modifications as come within the true spirit and scope of the

invention. Having thus described our invention, what we claim as new and

desire to secure by United States Letters Patent is:

Claims

1. A three-piece golf ball comprising: a core comprising a center and a thread windings layer, wherein said

center has a compression in the range of about 60 PGA to 80 PGA and a weight

in the range of about 27.5 grams to 28.5 grams, and wherein said thread

windings layer has an unstressed thread dimension of about 0.020inches to

0.028inches by 1/16 of an inch, and has a 500% modulus between 220 to 280

p.s.i.;

a cover having a Shore D hardness in the range of about 63 Shore D to

about 69 Shore D; and

a plurahty of dimples arranged on the outer surface, with a first pattern of

dimples associated with each pentagon, a second pattern of dimples associated with

each square, and a third pattern of dimples associated with each triangle.

2. The golf ball of claim 1 wherein the center has a diameter in the range of

about 1.340 inches to about 1.370 inches.

3. The golf ball of claim 1 wherein the core has a weight in the range of about

34.5 grams to about 35.5 grams.

4. The golf ball of claim 1 wherein the core has a compression in the range of

about 60 PGA to about 80 PGA.

5. The golf ball of claim 1 wherein the core has a diameter in the range of about

1.555 inches to about 1.575 inches.

6. The golf ball of claim 1 wherein the cover comprises a blend of about 75% by

weight of a high resilience ionomer and about 25% by weight of a very low

modulus ionomer, wherein the high resilience ionomer is a copolymer of

approximately 81% of an olefin with about 19% of an alpha, beta ethylenically

unsaturated caboxylic acid, where acid groups of the high resilience ionomer are

neutralized with a sodium ion, and wherein the very low modulus ionomer is a

terpolymer of 67-70% by weight of ethylene, 20-21% by weight of n-butyl

acrylate, and 12% by weight of methacrylic acid, where acid groups of the very

low modulus ionomer are neutralized by a zinc ion.

7. The golf ball of claim 1 wherein the cover has a thickness of in the range of

about 0.052 inches to about 0.063 inches.

8. The golf ball of claim 1 wherein the outer surface comprises a plurahty of

dimples arranged on the outer surface to form a dimple pattern, the plurahty of

dimples including

a first set of dimples, with each dimple in the first set having a single radius

cross section;

a second set of dimples, with each dimple in the second set having a dual

radius cross section; and

a third set of dimples, with each dimple in the third set having a single

radius cross section.

9. The golf ball of claim 8 wherein

the dimples in the first set of dimples have a diameter of 0.156 inches and a major radius of 0.4148 inches; the dimples in the second set of dimples have a diameter of 0.145 inches, a major radius of 0.7874 inches, and a minor radius of 0.1181 inches; and the dimples in the third set of dimples have a diameter of 0.140 inches and a

major radius of 0.3535 inches.

10. The golf ball of claim 8 wherein the dimples in the first set of dimples have a diameter in the range of 0.150 inches to 0.160 inches, and a major radius in the range of 0.34 inches to 0.80

inches; the dimples in the second set of dimples have a diameter in the range of

0.140 inches to 0.150 inches, a major radius in the range of 0.41 inches to 0.80

inches; and a minor radius in the range of 0.10 inches to 0.12 inches; and

the dimples in the third set of dimples have a diameter in the range of 0.135

inches to 0.145 inches, and a major radius in the range of 0.34 inches to 0.80 inches

11. The golf ball of claim 8 wherein the outer surface is divided into a plurahty of

polygonal configurations which include pentagons, squares and triangles, wherein a first pattern of dimples is associated with each pentagon, a second pattern of

dimples is associated with each square, and a third pattern of dimples is associated

with each triangle.

12. The golf ball of claim 8 wherein the dimples in the first set of dimples have a different size than the dimples in the third set of dimples.

13 The golf ball of claim 8 wherein the outer surface is divided into a polyhedron defined as a rhombicosadodecahedron and dimples are arranged using that

pattern.

14. The golf ball of claim 8 wherein the total number of dimples is at least 402.

15. A method of preparing a golf ball comprising:

a) producing a sohd rubber center; wherein the center has a compression

in the range of about 60 PGA to 80 PGA and a weight in the range of about 27.5 grams to 28.5 grams, b) wrapping the sohd rubber center with thread windings in an open pattern to form the golf ball core layer,

c) winding the thread windings around the solid rubber center with a

thread tension from about 900 grams to 1100 grams to a thread

winding thickness of between 0.20 inches and 0.26 inches, wherein the

thread windings have an unstressed thread dimension of about l/16^th of an inch width by about 0.020 inches to 0.028 inches height, and a

500% modulus between 220 to 280 p.s.i.; d) providing a ionomer mixture for a golf ball cover; wherein the ionomer

mixture comprises a blend of 75% by weight of a high resilience ionomer

and about 25% by weight of a very low modulus ionomer, wherein the high resilience ionomer is a copolymer of approximately 81% of an olefin

with about 19% of an alpha, beta ethylenically unsaturated caboxyhc

acid, where acid groups of the high resilience ionomer are neutralized with a sodium ion, and wherein the very low modulus ionomer is a terpolymer of 67-70% by weight of ethylene, 20-21% by weight of n-butyl

acrylate, and 12% by weight of methacrylic acid, where acid groups of the

very low modulus ionomer are neutralized by a zinc ion.

e) compression molding the ionomer mixture to the golf ball core to produce the golf ball cover; wherein the cover has a Shore D hardness

in the range of about 63 Shore D to about 69 Shore D;

f) applying a dimple configuration to the outer surface of the golf ball

cover, wherein the outer surface is divided into a polyhedron defined as a

rhombicosadodecahedron and dimples are arranged using that pattern; and g) further processing the golf ball by steps such as pressure blasting,

vibratory finishing, stamping of the logo, applying a primer, and

applying a top coat.

15. The method of claim 15 wherein in the production of the center the center has

a diameter in the range of about 1.340 inches to about 1.370 inches.

16. The method of claim 15 wherein in the formation of the core the core has a

weight in the range of about 34.5 grams to about 35.5 grams.

17. The method of claim 15 wherein in the formation of the core the core has a

compression in the range of about 60 PGA to about 80 PGA.

18. The method of claim 15 wherein in the formation of the core the core has a

diameter in the range of about 1.555 inches to about 1.575 inches.

19. The method of claim 15 wherein in the production of the cover the cover has a

thickness of in the range of about 0.052 inches to about 0.063 inches.

20. The method of claim 15 wherein in the apphcation of the dimple configuration

the total number of dimples is at least 402.

21. The method of claim 15 wherein in the apphcation of the dimple configuration

the outer surface comprises a plurahty of dimples arranged on the outer surface

to form a dimple pattern, the plurahty of dimples including

a first set of dimples, with each dimple in the first set having a single radius

cross section;

a second set of dimples, with each dimple in the second set having a dual radius cross section; and

a third set of dimples, with each dimple in the third set having a single

radius cross section.

22. The method of claim 21 wherein in the apphcation of the dimple configuration the dimples in the first set of dimples have a diameter of 0.156 inches and a major radius of 0.4148 inches; the dimples in the second set of dimples have a diameter of 0.145 inches, a major radius of 0.7874 inches, and a minor radius of 0.1181 inches; and

the dimples in the third set of dimples have a diameter of 0.140 inches and a

major radius of 0.3535 inches.

23. The method of claim 21 wherein in the apphcation of the dimple configuration

the dimples in the first set of dimples have a diameter in the range of 0.150

inches to 0.160 inches, and a major radius in the range of 0.34 inches to 0.80

inches;

the dimples in the second set of dimples have a diameter in the range of

0.140 inches to 0.150 inches, a major radius in the range of 0.41 inches to 0.80

inches; and a minor radius in the range of 0.10 inches to 0.12 inches; and

the dimples in the third set of dimples have a diameter in the range of 0.135

inches to 0.145 inches, and a major radius in the range of 0.34 inches to 0.80

inches.

24 The method of claim 21 wherein in the apphcation of the dimple configuration

the outer surface is divided into a plurahty of polygonal configurations which

include pentagons, squares and triangles, wherein a first pattern of dimples is

associated with each pentagon, a second pattern of dimples is associated with each square, and a third pattern of dimples is associated with each triangle. The golf ball of claim 21 wherein in the apphcation of the dimple configuration

the dimples in the first set of dimples have a different size than the dimples in the third set of dimples.