CA1327857C

CA1327857C - Golf ball

Info

Publication number: CA1327857C
Application number: CA000586059A
Authority: CA
Inventors: Michael J. Sullivan
Original assignee: Lisco Inc
Current assignee: Topgolf Callaway Brands Corp
Priority date: 1988-01-15
Filing date: 1988-12-15
Publication date: 1994-03-15
Anticipated expiration: 2011-03-15
Also published as: SE8900122L; KR890011619A; NZ227609A; JPH01308577A; US4884814B1; IT1229901B; US4884814A; JP2709950B2; AU2700888A; DE3900097C2; GB2214515B; FR2625909A1; FR2625909B1; KR930001279B1; GB8900625D0; DE3900097A1; GB2214515A; ZA889636B; IT8947525A0; ES2013831A6

Abstract

ABSTRACT
The subject invention relates to golf ball technology, and more particularly, golf ball cover technology. The invention is concerned with a particular mixture of ionic resins as a golf ball cover composition.
Ionomers have been widely used as golf ball cover materials for the past 15 years. While these ionomers are very durable, they have a deficiency as a golf ball cover material in that they tend to be hard.
This invention is concerned with a mixture of a hard ionomer with a soft ionomer in order to produce a golf ball cover composition wherein the cover is softer than the prior art ionomer covers.
A golf ball covered in accordance with this invention is durable and a skilled golfer can impart back spin to the ball in play.

Description

1327~7 IMPROYED GOI,F BALL

This invention relates to golf balls. More particula~ly, this lnvention relates to an i~proved golf ball cover useful in producing golf balls, particularly two-piece golf balls, exhibiting superior short lron and other playability characteristics.

BAC~GROUND OF THE INVENTION
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~ or many years balata and blends of balata wlth elastomeric or plastic ~aterials were the prlncipal ~aterials used in the manufacture of top quality golf balls~ Balata and balata-contalning cover compositions possess the desirable property of ready adaption to molding and accordlngly can be easily compression ~olded about a spherical wound core to produce a high quality golf ball.
The relative softness of the balata cover is advantageous in that an experienced golfer can apply a spin to balata-covered balls to control the ball in flight to produce a draw or a fade, or a backspin to cause the ball to "bite" or stop abruptly on contact with the green. Such playability properties are particularIy l~portant in short iron play and are e~ploited significantly by relatively skllled players.
However, balata covered golf balls are easily cut if ~ishit and golf balls produced with balata or balata-containing cover compositions have a relatively ~hort life ~pan.

' ' . , ' '' , , ' ' 1~278~7 Due to this negatlve property, balata and its synthetic substltutes, t~ans-polybutadiene and tra~s-polyisoprene, have today been replaced essentially by newcover materials, primarlly by a fa~ily of lonomers sold by E. I. duPont de Ne~ours ~ Company under the trademark SURLYN. These iono~ers comprise copolymers of olefins, typically ethylene, with an alpha, b~ta ethylenically unsaturated carboxylic acid, such as ~ethacrylic acid.
Neu~ralization of a number of the acidic groups is effected with metal ions, such as zlnc or sodium, resulting in a thermoplastic elastomer which has ~everal advantages over balata when employed as the cover composition for golf balls.
In addition to cost-saving vis-a~vis balata, the hardness, resilience and other ~echanical properties of these ionomers may be controlled in order to a~fect cut resistance, shear resistance, general durability and resilience. Such control can be exercised by selection of particular co~onomers, molecular weight, degree of neutralization and the particular ~etal ions used.
The use of Surlyn~as golf ball covers has been a ~a~or factor in the productlon of two-piece balls. These Surlyn balls for all pract1cal purposes cannot be cut in play and they travel further when hit with a golf club as co~pared to the prior~ art balata covered balls.
Regardless of these desirable properties, Surlyn covered golf balls have not proven desirable in short iron play, in that it is ~ore difficult to l~part spin to the Surlyn covered balls than to the balata covered counterpart.
Purther, frequently e~perienced golfer~ have noted that the Surlyn covered balls do not have a sAtisfactory "feel" or "click".

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-` 13278~7 The golfing industry h~s therefore, for a number of years, attempted to develop a cover co~position whlch possesses both the durabillty of the Surlyn formulatlons and the playabllity characteristics of the balata-based compositions.
In the mid-1~80's, golf balls were introduced to the lndustry which were covered wlth a mlxture o~ hard ionic resins and a thermoplastic polyurethane resin. The hard ionomers used in these blends had a hardness of about 94-85 on the Shore C scale. While these balls have been generally satisfactory in provlding the desirabie qualities of playabillty and acceptable durability, these balls were disadvantageous ln that they were short on distance when hit by an average golfer with an average swing veloc~ty. Further, these prior art golf balls had a lower initial velocity when comp~red to prior art golf balls which were covered with a single or blend of hard ionomers. In the subject application, when a hard iono~er is referred to it is a Surlyn resln havlng a hardness o~ from about 94-96 un the Shore C scale.
Further, it has been noted that balls co~ered with the ~.ixture of Surlyn and soft ther~oplastic polyurethane tend to yellow and not to provide the bright white which can be obtained In traditional Surlyn covered balls. This deficiency results from the fact that the polyurethane resins tend to be yellow to off white in color.
Stlll further, the ~ixtures of Surlyns and polyurethanes are difficult to process and ~old, such difficulties being lnherent in all ther~oplastic polyurethane resins. ~or example, lt is difflcult to - 3 _ ~ ' .
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~327~7 obtain a homogeneous bl~nd of Surlyns and polyurethanes in ~n extruder prIor to in~ection ~olding the co~position onto the preposition core.
It is felt that iono~ers such as Surl~n ionomer are baslcally incompatible with polyurethane resins due to the backbone difference of each of these polymeric species. As a result of this inco~patibility, dela~Ination or separation in the ~anufacturing prGcess ~ay occur. Finally, such mixtures of Surlyns and polyurethane are expensive, due to the inltial cost of the thermoplastic polyurethane and in compounding procedure require~ents.
Attempts to ~odlfy the basic ionomer polyurethane compositlons by such ~ethods as adding addltional hard ionomers to enhance toughness have been unsuccessful since the ~aterials are basically inco~patible at levels of greater than 15 to 20 percent ionomer. ~urther, blends of harder ther~oplastic polyurethanes with hard ionomers have resulted in products lacking an adequate initial velocity.
It 1~, therefore, an object of the present invention to provIde a golf ball whlch is cut resistant and provides the desirable playability features of balata-covered golf balls.
It is another object to provide a golf ball which is longer, i.e., does not have a distance shortco~ing when struck wi~h a golf club.
A further object of the present lnvention is to provide a golf ball which exhibits a bright white coloration and which does not yellow upon aging.

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~ 3~S7 Still another obJect ~f this inventlon is to prov~de a golf ball co~er compositlon which c~n be easily processed.
Lastly, lt is an obJect of this lnvention to provide a golf ball cover compositlon whlch does not delaminat0 in either processing or on finlshed golf balls.

BRIEF DESCRIPTION OF TH~ INVENTION

In the prior art, two princlpal types of ~olf balls were known. The Surlyn covered golf balls which lack control and have a hardness of about ~5 $o 96 on the Shore C scale and the traditional Balata covered ball which had a hardness of about 75 on the Shore C scale.
Hard Surlyns suitable for use in golf ball cover composltions have been available for approxImately 20 years. Initially, all Surlyns were lonomers whlch were very tough and hard. These properties of toughness and hardness ~ade Surlyns commercially viable as a replacement for other poly~eric materials ln golf ball cover co~positions. While these properties of toughness and hardness are advantageous, when it comes to the toughness and cut resistance of a golf ball, the~e properties are dlsadvantageous when it ls desirable Por a golfer to impart back spin to R golf ball as a result of the controlled striking of the ball with an lron club.
For over a decade the trade ette~pted to solve these proble~s of Surlyn covered golf balls by the blending of hard Surlyn with a soft Surlyn. Or in so~e ~nstances, with a dlfferent type of poly~eric raterial.

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Unt~l this invention, the blending of a hard Surlyn and a soft Surlyn was totally unsatisfactory in the production of a com~erclally vlable golf ball.
Basically, in the prlor art, when a hard Surlyn was blended with a soft Surlyn to such a degree that -the proper hardness or modulus was achieved, the durablllty of the golf ball deteriorated to a point where the resulting ball was not commercially viable.
In the prior art, endeavors were ~ade to blend a hard Surlyn with other softer poly~eric ~aterlals such as softer polyurethanes. While these endeavors were generally successful, the resulting golf balls had a deficiency in that they were generally short when co~pared to golf balls which were covered wlth a single or a blend of hard Surlyns. These blends of a hard Surlyn with a polyurethane were disadvantageous in that they exhibited light stability problems, they were hard to process and ~ost significantly they were fihort on distance.
In accordance with the above description, it can be seen that while it was possible to achieve a glven ; hardness by the blending of the prior art, hard and soft Surlyns, this blending did not necessarily result in a com~ercially viable golf ball.
In accordance with this invention, it has been found that when a hard Surlyn or a ~ixture of hard Surlyn resins are blended with a soft Surlyn which ls a terpoly~er of ~ethacrylic acid and iso- or n-butylacrylate partially neutralized with a ~etal salt, a superior golf ball cover formulation i% produced. The resulting cover co~position of this lnvention is '~
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- ~, :' ' , 13278~7 ~ntermediate in softness between a balata covered golf b~ll and a hard Surlyn covered golf ball, to such a degree that an adequate back spin oan be imparted to the ball by a skilled golfer. Further, the resulting golf ball of th1s invention exhib~ts a degree of cut resistance which is adequate for play and which ls definitely superior to that of the above mentioned prlor art balls which are covered with a blend of a hard Surlyn and a polyurethane resin.
Lastly but ~ost importantly, the golf ball of this inventlon in addition to having the above described properties, exhibits outstanding distance properties which is exhibited by its coefficient of restitutlon and/or initial veloclty wllen tested in accordance with the rules and regulatlons of the United States ~olf Association.
In order to achieve these desired physical properties, it i5 lmperative that the hard lono~er and soft ionomer be blended in particular proportions which are described herelnbelow.

DESCRIPTION O~ THE PREPERRED ~M~ODIMENT
The deslrable properties and the resultlng golf balls as described herein above are achleved in accordance wlth this invention by the b}ending of a high ~odulus ~hard) iono~er wlth a low ~odulus (fioft~ iono~er to produce a base ionomer ~ixture.
I~ this invention, a hlgh ~odulus iono~e~ i~ an ionomer havlng a flexural ~odulus of from about 30,000 to 55,000 P.S.I. as ~easured in accordance with A.S.T.M.
~ethod D-790. All ~oduli mea~ured and referred to ln accordance with this invention is flexural ~odull.

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:, i327~7 The pbysical properties of the iono~ers which are useful ln ttlls Invention may be furtlIer deflned by the hardness of said lonomers. The high modulus ionomers ~s defined above have a hardness of fro~ about 60 to 66 on the Shore D scale as measured in accordance wlth ASTM
~ethod D-2240.
The oodulus of the ionomers which are useful in this invention is closely related to the hardness of said ionomers. Generally, the higher the ~odulus, the harder the iono~er although one skilled in the art recognizes that there ~ay be exceptlons to this rule.
-To the best of applicant's knowledge,lthe hard Surlyn reslns as used in this invention are ionic copolymers which are the sodium or zinc salts of the reaction ~product of an olefin having from 2 to 8 carbon atoms and an unsaturated monocarboxylic acid having fro~
3 to 8 carbon atoms. The carboxYlic acid groups of the copolymer ~ay be totally or partially neutralized.
These hard ionomers are sold under the trademark SURLYN. In the high ~odulus ionomers which are useful in this invention, the acid groups ~ay be 15-75 percent cation neutralized ~lth either sodium or zinc cations.
; A low modulus iono~er as is useful in the blends of this lnvention has a ~odulus of from about 3,000 to about 7,000 P.S.I. and a hardness of from about 25 to about 40 as `measured on the Shore D scale. ~oth the ~odulus and hardness were measured in accordance wlth the A.S.T.M. tests ~s referred to above.
While the applicant is not sure of the chemical makeup of these lower ~odulus ionomers i~ accordance with the preferred e~bodi~ent, they are thought to be terpolymers of ethylene, ~ethacrylic acid and n- or :.
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:`, ," : ' . ' ' `, 1327~7 lso butylacrylate. In these low modulus ionomers, the acid groups may be 5-95 percent cation neutralized with sodium or zinc cations.
It is understood by one skilled ln the urt that the soft ionomer may be a sodium or ~inc salt of a terpoly~er of an olefin ilaving from 2 to 8 carbon ato~s, an unsaturated monocarboxyllc acld havin~ from 3 to 8 carbon atoms and an unsaturated mono~er of the acrylate ester class having from 2 to 22 carbon atoms.
As a starting point in preparation of the co~er formulatlons in accordance with this lnvention, a base lonomer ~ixture is for~ed from low and high modulus ionomers as are described above. This base lonolner ~lxture can comprlse from about 25 to about 75 parts of a low modulus lonomer and from about 25 to about 75 parts of a high ~odulus ionomer. A more preferred range is fro~ abou~ 35 to ~bout 65 parts of a low modulus ionomer and from about 65 to about 35 parts of a high nodulus lonomer. A most preferred range for the base ionomer ~ixture is from about 38 to about 62 parts of a low modulus ionomer and from abou~ 62 ~o about 38 parts of a high ~odulus ionomer.
Two preferred embodi~ents for use in accordance with this invention are as follows: About 61.9 parts of a low ~odulus ionomer and 38.1 parts of a high ~odulus ionomer, and stlll another preferred embodlment uses about 3~.6 parts of a low modulus iono~er and ~0.4 parts of a hlgh ~odulus ionomer.
The above described base ionomer mixture can be used to produce a superior golf ball cover and hence superior golf balls. Tradltion dictates that golf balls ~,J~'~j"

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~3278~7 be either white or colored. In order to achleve this end, a pig~ent must be added to the base iono~er olxture. Most commonly white plgments are utllized to produce the traditional white golf ball. Sultable white pigments for use in this invention are titanlu~ dioxide, zinc oxide, barium sulfate and zinc sulfate. It is understood by one skilled in the art that covers other than white can be ~ade by adding colored dyes or pigments to the sub~ect base ionomer mixture.
The amount of pigment used in conjunctlon with the poly~eric cover composition naturally depends on the particular base ionomer mixture utllized and the particular pigment utilized. The concen~ration of the pigment in the polymeric cover composition can be from about lX to about 10% as based on the weight of the base ionomer mixture. A more preferred range i9 from about 1%
to about 5% as based on the weight of the base iono~er ~ixture. The most preferred range is from about 1% to about 3% as based on the weight of the base ionomer mixture.
The ~ost preferred pigment for use in accordance with this invention is titanium dioxide. When this co~bination of components is utilized, it is preferred that the concentration of tltanium dioxide in the cover composition be from about 1% to about 10% as based on the weight of the base ionomer ~ixture utilized. A ~ore preferred range for the concentration of titanium dioxide is ~ro~ about lX to about 5S as based on the base ionomer mixture utilized. A ~ost preferred concentration for the titanium dioxide is about 2% as based on the weight of the base iono~er xixture utilized.

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,., : . . : , :~ : , ; , ; '~ ' :~ ' ~327~57 It is within the purvlew of this invention to add to the cover co~positions of this lnvention comp~tible materials which do not affect the baslc novel characteristics of the composition of thls lnvention.
Among such materials are antioxidants, antistatic agents, stabilizers and processing aids.
Functional cover compo~itions for producing white golf balls in accordance with this invention are as follows:
Base Ionomer Mixture from about 90% to about 99%
White Pigment fro~ about 10% to about 1 Blue Pigment - trace A more preferred cover composition for use ln accordance with this invention is as follows:
Base Ionomer Mixture from about 95% to about 99%
Titanium Dioxide from about 5X to about 1 81ue Pigment - trace A preferred cover co~position for use in accordance with this invention is as follows:

Base Ionomer Mixture$ from about 95% to about 97%
Titanium Dloxide from about 4X to about 2%
Ultramarine Blue - trace Nucrel** 925 from about 0% to about 1.0%
*The base iono~er ~ixture used in this preferred composition comprises 43.1 parts of a low ~odulus ionomer sold as Surlyn AD-8269, 18.8 parts of a low ~odulus ionomer s~ld as Surlyn AD-8266, 25.1 parts of a high ~odulus Surlyn sold as Surlyn 9910, 5.6 parts of high ~odulus Surlyn sold as Surlyn 8940 and 7.4 parts of a high ~odulus Surlyn ~old as Surlyn 8528.
~*Nucrel~ ls used as a processing agent, it is thought to be a copoly~er of ethylene and ~ethacrylic acld.

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Base Ionomer Mixture*~* from about 9~% to about 98%
Titaniu~ Dioxide from about 2% to about 4%
Ultramarine Blue - trace ***The base ionomer mixture used in this instance comprises 27.6 parts of a low modulus lonomer sold as Surlyn AD-8269, 12.0 p~rts of a low modulus ionomer sold as Surlyn AD-8265, 42.2 parts of a high ~odulus Surlyn sold as Surlyn 9910, 10. a parts of a high modulus Surlyn sold as Surlyn 8940 and 7.4 parts of a high modulus Surlyn sold as Surlyn 9650.
When a white pig~ent is utillzed, the resulting covers are pure white in that the poly~eric co~ponents which make up the cover stock do not detract from the whiteness of the pigment. In their pure state the high and low modulus polymeric components are clear. Thls is to be contrasted with the off white or yellow color of the prior art compositions which incorporate polyurethane components. Because the resulting cover composition of this invention is pure white, the technology of U.S.
Patent No. 4,679,795 can be readily adapted to this invention. That is the surface of golf balls ~ade in accordance with this invention can be optically brightened as per the teaching of this patent.
This invention can likewlse be used in con~unction with cellular polymeric gol~ ball covers as are described in U.S. Patent No. 4,274,637 issued June 23, 1981.
One ækilled in the art is aware of the fact that there are various hues of the color white; for example, there are blue whites, yellD~ ~hites, etc. In accordance with the preferred e~bodi~ent of thl~ invention, trace ~2 -1: . , 13?7~7 amounts of a blue pigment are added to the golf ball covercomposition in order to give sald cover co~position materials a blue white appearance. Naturally, it is understood if other hues of the color white are desired, different pigments can be added to the cover co~position ~aterial. The amount of pigment used ~ust be ad~usted by one skilled in the art in order ts achieve the desired color hue.
In the subject ~pecification and claims, the term "center" is utilized to deflne the central part of the finished golf ball. As used in this specification and claims the term "center" refers to both solld centers as are used on two-plece golf balls, and to wound centers which are commonly used ln balls which are referred to in the trade as three-piece golf balls.
The following examples serve to illustrate the present invention, such examples given for the purpose of lllustration and not for purposes oP limltlng the present islvention. In the examples, all parts percent are given by weight unless otherwise specified.

EXAMPLES

FInished golf balls were p~epared for the below listed examples by positioning pre~or~ed, cross-llnked poIybutadiene cores in an in~ection molding cavity. The ccres in question were centrally positioned in the cavities by the use of retractable pins. The cover ~as thenin~ection ~olded a~ound the core.
In all exaimples, the cover composition formulas are on a parts by ~eight basis. The Surlyn and Nucrel reslns are used in these exa~ples are a product of the E. I. DuPont de Nemour~ ~ Co., Inc., Wilmington, Delaware.

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, ~327~7 The test data for the golf balls of the below listed examples is expressed in Tables 2 thru 5 hereln below.
Riehle compresslon is a ~easurement of the deformation of a golf ball under a flxed static load of 225 pounds.
Coefficient of restitution was measured by firing the resulting goIf ball in an air cannon at a velocity of 125 feet per second against a steel plate which ls positioned 12 feet from the ~uzzle of the cannon. The rebound velocity was then ~easured. The rebound velocity was divided by the forward veloclty to give the coefficient of restitution.
Shore hardness was measured ln accordance wlth ASTM Test 2240.
Cut resistance was measured in accordance with the following procedure: A golf ball is fired at 135 feet per second against the leading edge of a pitching wedge, wherein the leading edge radius ls 1/32 lnch, the loft angle is 51 degrees, the sole radius is 2.5 inches, and the bounce angle is 7 degrees.
The cut resistance of the balls tested herein was evaluated on a scale of 1-5. 1 represents a cut that extends completely through the cover to the core; a 2 represents a cut that does not extend completely through the cover but that does break the surface; a 3 does not break the surface of the cover but does leave a per~anent dent; a 4 leaves only a sllght crease which is permanent but not as severe as 3; and a 5 represents virtually no vislble indentation or damage of any 80rt.
The total distance was ~easured by strlklng the golf ball with a mechanical device which swings a driver at a head speed of 160 feet per second.

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~327857 The ~pin rate of the golf ball was ~easured by striking the resulting golf balls with a #5 iron in the manner as described above wherein the head speed ls 128 feet per second at a launch angle of 10 tO 12 degrees and an initial velocity of ahout 168 feet per second.
The spin rate was measured by observlng the rotation of the ball in flight using stop action Strobe photography.
The traJectory of the golf balls during flight was ~easured in accordance wlth United States Golf Association Test: Symmetry (1.5).
Initlal velocity is the velocity of a golf ball when struck at a ha~mer speed of 143.8 feet per second in accordance with a test as prescribed by the Unlted States Golf Association.
The Ultramarine Blue used in these examples is a pigment dye as sold by Whitaker, Clark and Daniels, of South Plainsfield, N.J.
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~3%7~7 Examp_e 1 Using the procedures described above. at least 72 golf balls were prepared wherein the cover had the foll Oh'i ng composition:
Surlyn 8940 5.6 Surlyn 8528 7 4 Sur]yn 9910 25.1 Surlyn AD-8269 43.1 pph Surlyn AD-8265 18.8 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB~ 0.10 ~'ucrel 925 1.0 Example 2 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following compos.ition:
Surlyn 8940 10.8 Surlyn 9650 7.4 : Surlyn 9910 42.2 Surlyn AD-8269 27.6 Surlyn AD-8265 12.0 Titanium dioxide 2.3 Ultramarine Blue 0.02 ~; Uvitex OB 0.10 Example 3 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 8528 7.5 Surlyn 8940 5.6 Surlyn 9910 25.2 Surlyn AD-8269 43.0 . Surlyn AD-8265 18.7 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB 0.10 1- Trade-lnark ~ .

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.: . , ~3~7~57 F.xamwle 4 Using the procedures described above, at least : 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 85287.4 Surlyn 894020.5 Surlyn 991024.9 Surlyn AD-826932.9 Surlyn AD-826514.3 Titanium dioxide 2.3 Ul-tramarine Blue 0.02 Uvitex OB 0.10 ~ .
Using the procedures described above. at least .
72 golf balls were prepared wherein the cover had the following composition:
Surlyn 85287.4 Surlyn 894035.9 Surlyn 991024.9 Surlyn AD-826922.2 Surlyn AD-82659.6 Titanium dioxide 2.3 Ultramarine Blue 0.02 : Uvitex OB 0.10 Example 6 Using the procedures described abo~e, at least 72 golf balls were prepared wherein the cover had the following composition: `
Surlyn 8528 .7.4 Surlyn 89~051.2 Surlyn 9910.2g.9 Surlyn AD-826911.5 Surlyn AD-82655.0 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB 0.10 .

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~ 3 ~ 7 Example 7 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 8528 7.4 Surlyn 8940 70.2 Surlyn 9910 22.4 b Surlyn AD-8269 Surlyn AD-8265 Titanium dioxide 2.3 ~ Ultramarine Blue 0.02 ; Uvitex OB 0.10 Example 8 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 8528 7.4 Surlyn 8940 Surlyn 9910 24.9 Surlyn AD-8269 47.1 Surlyn AD-8265 20.5 Titanium dioxide 2.3 : Vltramarine Blue 0.02 Uvitex OB 0.10 .
~,~ Example 9 Using the procedures described above. at least 72 golf balls were prepared whereih the cover had the following composition:
Surlyn 8528 7.4 . Surlyn 8940 Surlyn 9910 16.4 Surlyn AD-8269 53.0 Surlyn AD-8265 23.2 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB O.10 ., .

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~3~7~7 Example 10 Using the procedures descri~ed above. at least 72 golf balls were prepared wherein the cvver had the following composition:
Surlyn 85287.4 Surlyn 8940 Surlyn 99108.2 Surlyn AD-8269 58.8 Surlyn AD-826S 25.6 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB0.10 Example 11 Using the procedures described above, at least 72 ~olf ba]ls were prepared wherein the cover had the following composition:
Surlyn 85287.4 Surlyn 8940 Surlyn 9910 Surlyn AD-8269 64.5 Surlyn AD--8265 28.1 Titanium dioxide 2.3 Ultramarine Blue Q.02 Uvitex OB0.10 Example 12 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following co~position:
Surlyn 8940 Surlyn 991017.5 Surlyn AD-8269 57.5 Surlyn AD-8265 25.0 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB0.10 ~ ~Y' - , .

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: . , ~327857 Example 13 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 8940 Surlyn 9910 42.5 Surlyn AD-8269 57.5 Surlyn AD-8265 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB O.lo Example 14 Using the procedures described'above, at least 72 golf balls were prepared wherein the cover had the fol]owing composition:
Surlyn 9910 ~o,o Surlyn AD-~269 60.0 Surlyn Titani~m dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB 0.10 xamPle 15 Using the procedures described above, at least 72 golf balls were prepared ~herein the cover had the following composition:
Surlyn 9910 30.0 Surlyn AD-3269 70.0 Surlyn Titanium dioxide 2.3 Ultramarine Blue 0.02.
Uvitex OB 0.10 .

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, ~327857 Example 16 Vsing the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 9910 20.0 Surlyn AD-8269 80.0 Surlyn Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB 0.10 ExamPle 17 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 9910 14.0 Surlyn AD-8269 57.5 Surlyn 8940 28.5 Titanium dioxide 2.3 Ultramarine Blue 0.02 Vvitex OB 0.10 ~' Example 18 Using the procedures described above. at least 7~ golf balls were prepared wherein the cover had the following composition:
Surlyn 9910 13.2 Surlyn AD-8265 60.0 Surlyn 8940 26.8 Titanium dioxide 2.3 Ultramarine Blue 0.02 : Uvitex OB 0.10 .5 . ~ .

, . . . . .
.

1~27857 Example 19 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 991o 9.9 Surlyn AD-8269 70.0 Surlyn 8940 20.1 Titanium dioxide 2.3 Ultra~arine Blue 0.02 Uvitex OB O.lo Example 20 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the ~ollowing composition:
Surlyn 9910 6.6 Surlyn AD-8269 80.0 Surlyn 8940 13.4 Titanium dioxide 2.3 Ultramarine Blue O.Q2 Uvitex OB 0.10 ExamPle 21 : Using the procedures described above. at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 8940 70.2 Surlyn 9910 22.40 Surlyn 9650 7.4 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB 0.l0 - ~

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~27857 ~xample 22 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 8660 46.3 Surlyn 9970 46.3 Surlyn 9650 7.4 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB 0.10 Example 23 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the follow.ing composition:
j Surlyn 8020 46.3 Surlyn 9520 46.3 Surlyn 9650 7.4 Titanium dioxide 2.3 Ultramarine Blue 0.02 j~ Uvitex OB 0.10 '~ Example 24 ~ sing the procedures described above, at least`
72 goli` balls were prepared wherein the cover had the following compositiou:
I Surlyn 9910 78.7 Surlyn 9650 7.4 i Surlyn I Titanium dioxide 2.3 Ultramarine Blue 0.02 l~ Uvitex OB 0.10 ~ucrel 925 13.9 J
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~3278~7 Example 25 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 9910 74.1 Surlyn 8020 9.3 Surlyn 9650 7.4 Titanium dioxide 2.3 Ultramarine Blue 0.02 Uvitex OB 0.10 ~'ucrel 925 9.2 Example 26 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Surlyn 9970 20.0 Texin 48OAR 80.0 Titanium dioxide 5.0 Ultramarine Blue 0.02 Uvitex OB 0.10 Example 27 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Texin 913~ 100.0 ::.
Titanium dioxide 5.0 Ultramarine Blue 0.02 Uvitex OB 0.10 ~ .

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" ' 13278~7 Example 28 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Texin 915 100.0 Titanium dioxide 5.0 Ultramarirle Blue 0.02 Uvitex OB 0.10 _xample 29 : Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the~
following composition:
Texin 345D 100.0 Titanium dioxide 5.0 Ultramarine Blue 0.02 Uvitex 08 0.10 Example 30 ~ `
Vsing the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Texin 355 100.0 Titanium dioxide 5.0 :~ UItramarine Blue 0.02 Uvitex OB 0.10 Example 31 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the : following composition:
Surlyn 9970 20.0 Texin 480AR 8U.O
Titanium dioxide 5.0 Ultramarine Blue 0.02 Uvitex 0~ 0.10 : ~ - 26 -"~

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., ExamDle 32 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Texin 480AR 65.0 Texin ~915 35.0 Titanium dioxide 5.0 Vltramarine Blue 0.02 Uvitex OB 0.10 E~amDle 33 Using the procedures described above, at least 72 golf balls were prepared wherein the cover had the following composition:
Pellethane 2355 80A
Pellethane 2355 ~OA
Titanium dioxide 5.0 Ultramarine Blue 0.02 Uvitex OB 0.10 , ~: -!~:

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~3278~7 PRIOR ART GOLF BALLS

ORIGINALTITLEIST
TOUR EDITION ~ .384 BALATAt EXAMPLE NO. 34 35 Welght 45.1 45.4 Compression 63 68 C.O.R. .795 7~4 Shore C Hardness 76 79 Cut Resistance 3-4 Drlver Test~ng:
Carry 244.3 244.4 Total 262.4 262.9 Tlmed Flight 5.g9 5.90 Tra~ectory 13.9 13.6 5-Iron:
Launch Angle 7.6 7.5 Clubhead Speed 232.4 235.5 Spin Rate (RPN) 2512 3090 .
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~327857 DISCUSSION OF THE EXAMPLES

Examples 1-5, 8, 13-15 and 17-19, the data of whlch ls incorporated in Tables 2 and 3, are golf ball cover compositions in accordance with thi~ lnventiDn.
Example~ 21-33, as per Table 4, are comparative examples wherein inferior golf ball cover compo~itions were created.
Examples 34-40, as per Tables 5 and 6, reflect prior art golf balls.
In order to properly correlate the distance dat~
as is reflected in some of the examples, lt should be noted that the data for Example 1 wa~ taken at the same ti~e as the data for Examples 36-40 as per Table 6.
Likewise, the distance data for Exa~ple 2 was taken at the same time as the data for examples 34 and 35 as per Table 5.
;~ Distance data was not available i~or all of the exa~ples due to the diffIculty ln gathering thi$ data.
The data for Examples 1-5, 8 and 9as per Table 2, reflect~
the preferred cover composltion ln accordance wlth thls invention, wherein relatively 60ft covered balls having superior coefficient o~ restltution and superior cut resistance are produced.
The balls of Exa~ples 6 and 7 are too hard to offer sufficiently good playabllity. Conversely, the ball~ of Examples lO and ll,while belng soft, suffer fro~
poor cut resistance and low coefflcient of restitution.
When compared to the prior art gol~ ball, Exa~ples 1-5 and 8 as per Table 5, it can be ~een that the aver~ge coefficient of re6tltutlon for these exa~ple~

:

,. . -13~78à7 is higher than the average coefficient o~ restltution for Examples 34 and 35. Purther, lt can be seen that the cut resistance is signlficantly better.
In comparing the actual distance that the resultant golf balls will fly, lt can be seen that ln co~paring the data of ~xample 2 with the data for Examples 34 and 35, the golf ball of Example 2 is approximately 4 yards longer than that of the balls of Examples 34 and 35. This 4 yard Increase is a signiflcant increase which could be easily observed by a skilled golfer. Likewise, relative to the data for Exa~ple 2, it can be seen that lt has a high spin rate of 2744 which is intermediate between the spin rates of 2512 and 3090 for the balls of Examples 34 and 35. The prior art golP baIls of Examples 34 and 35 are known to have spin rates which are satisfactory to skllled golfers.
Further, when comparing the data of Example 1 with the data of Examples 36-39, which are si~ilar soft ~olf balls, lt can be seen that the ball of Exa~ple 1 is significantly longer than the balls of Examples 3~-39.
Further, the ball of Example 1 is significantly ~ore durable than the balls of Examples 36-3~, as per the cut resistance data. Purther, the ball of Example 1 has a spin rate when strucX by a pitching wedge th~t is comparable to that of Examples 37 and 41. Llkewise, it can be seen that the spin rate of Example 1 ls ~uch higher than that of the balls of Exa~ple 40.
The data o~ Table 3, as per Examples 12-20, reflect the variations of the cover composition in accordance with this invention ~hich in so~e instances do not have the coefficient of restitution which ls as good as that of the data of Examples 1-S. ~ and 9, 13-15 and 17-19.

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However, the data of Table 3 demonstrates that over a wide range of variables, the cover compositlon of this invention is capable of producing a durable cut resistant golf ball.
~ 'he data of T~ble 4 reflects other relative cover co~positions whereln a hard Surlyn ls blended wlth, for example, polyu~ethanes. From this da~a, it can be seen that golf balls of Examples 21-33 are not as durable, at a comparable so~tness, as the preferred golf balls in accordance wlth this invention as per Examples 1-5 and 8.
The data for Examples 21-33 de~onstrates that it is not obvious to produce a durable soft cover golf ball having excellent cut resistance, coupled with a good coefficient of restitution.
The data ~or Examples 27-33 shows that if a soft golf ball is produced, it has a poor coefficient of restitution and, hence, poor distance properties and poor cut resistance.
From the data as listed above and the above discusslon, it can be seen that when the sub~ect invention is practiced as per Exa~ples 1-5, ~ and 9, a golf ball having superior playability is produced~ having excellent distance properties as are reflected by the coef~icient data and excellent durability properties as is reflected by the cut resistance data.

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:: : , - - : -:

Claims

1. A golf ball comprising a core and a cover, wherein said cover comprises from about 25 to about 70 percent of a hard ionomer which is a sodium or zinc salt of the copolymer of an olefin having from 2 to 8 carbon atoms and an unsaturated monocarboxylic acid having from 3 to 8 carbon atoms, wherein said hard ionomer has a modulus of from about 30,000 to about 50,000 P.S.I. and from about 75 to about 30 percent of a soft ionomer which is a sodium or zinc salt of a terpolymer of an olefin having from 2 to 8 carbon atoms, an unsaturated monocarboxylic acid having from 3 to 8 carbon atoms, and an unsaturated monomer of the acrylate ester class having from 2 to 22 carbon atoms, wherein said soft ionomer has a modulus of from about 3,000 to 7,000 P.S.I. and an effective amount of a suitable pigment.

2. The golf ball of claim 1 wherein the hard ionomer is a sodium or zinc salt of the copolymer of ethylene and methacrylic acid and the soft ionomer is a sodium salt of a terpolymer of ethylene, methacrylic acid and n- or iso-butyl acrylate.

3. The golf ball of claim 2 wherein said cover comprises from about 35 to about 65 percent of the hard ionomer and from about 65 to about 35 percent of the soft ionomer.

4. The golf ball of claim 2 wherein said cover comprises about 38 to about 62 percent of the hard ionomer and from about 62 to about 38 percent of the soft ionomer.

5. The golf ball of claim 2 wherein said cover comprises about 36.8 percent of the hard ionomer and about 59.9 percent of the soft ionomer.

6. The golf ball of claim 2 wherein said cover comprises about 59.0 percent of the hard ionomer and about 38.7 percent of the soft ionomer.

7. The golf ball of claim 2 wherein said cover composition incorporates from about 1 to about 10 percent by weight, based upon the weight of the ionomer mixture, of a suitable pigment.

8. The golf ball of claim 3 wherein said cover composition incorporates from about 1 to about 10 percent by weight, based upon the weight of the ionomer mixture, of a suitable pigment.

9. The golf ball of claim 4 wherein said cover composition incorporates from about 1 to about 10 percent by weight, based upon the weight of the ionomer mixture, of a suitable pigment.

10. The golf ball of claim 5 wherein said cover composition incorporates from about 1 to about 10 percent by weight, based upon the weight of the ionomer mixture, of a suitable pigment.

11. The golf ball of claim 6 wherein said cover composition incorporates from about 1 to about 10 percent by weight, based upon the weight of the ionomer mixture, of a suitable pigment.

12. The golf ball of claim 2 wherein said cover composition incorporates from about 1 to about 5 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

13. The golf ball of claim 3 wherein said cover composition incorporates from about 1 to about 5 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

14. The golf ball of claim 4 wherein said cover composition incorporates from about 1 to about 5 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

15. The golf ball of claim 5 wherein said cover composition incorporates from about 1 to about 5 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

16. The golf ball of claim 6 wherein said cover composition incorporates from about 1 to about 5 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

17. The golf ball of claim 2 wherein said cover composition incorporates from about 1 to about 3 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

18. The golf ball of claim 3 wherein said cover composition incorporates from about 1 to about 3 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

19. The golf ball of claim 4 wherein said cover composition incorporates from about 1 to about 3 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

20. The golf ball of claim 5 wherein said cover composition incorporates from about 1 to about 3 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.

21. The golf ball of claim 6 wherein said cover composition incorporates from about 1 to about 3 percent by weight, based upon the weight of the ionomer mixture, of a pigment which is a member selected from the group of titanium dioxide, barium sulfate, zinc oxide or zinc sulfate.