Title:
High Performance Golf Ball Comprising Modified High Mooney Viscosity Rubber
Kind Code:
A1


Abstract:
A high performance golf ball made in part of a modified high Mooney viscosity rubber. The modified high Mooney viscosity rubber has less than about 20 phr oil and is high Mooney viscosity rubber having a Mooney viscosity at least about 40 blended with between about 1 phr and about 10 phr of process oil and between about 0.05 phr and 5 phr of peptizing agent.



Inventors:
Tomita, Seisuke (Tokyo, JP)
Kennedy III, Thomas J. (Wilbraham, MA, US)
Bender, Aaron Craig (Portland, OR, US)
Tutmark, Bradley C. (Aloha, OR, US)
Application Number:
13/404544
Publication Date:
08/29/2013
Filing Date:
02/24/2012
Assignee:
NIKE, Inc. (Beaverton, OR, US)
Primary Class:
Other Classes:
473/371, 473/378, 473/351
International Classes:
A63B37/06; A63B37/00; A63B37/02; A63B37/12
View Patent Images:
Related US Applications:
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20070270256Sports racquetNovember, 2007Chullikattu
20060223649Weighting system for a putter type golf clubOctober, 2006Rife
20060240902Golf swing training aidOctober, 2006Jordan
20100062879Football holder for place kicking and method for making and using football holder for place kickingMarch, 2010Shaw et al.
20050049060Nothing but fairways & greens (N.B.F. & Greens)March, 2005Bell
20060135293Chute counterJune, 2006Lake et al.
20020165047Football reaction training deviceNovember, 2002Nunnely et al.
20090137352Padded sports ballMay, 2009Ou
20080207347Golf swing trainer and method of improving a golf swingAugust, 2008Rose
20030224870Shaft having axial pre-stressDecember, 2003Soong



Primary Examiner:
BUTTNER, DAVID J
Attorney, Agent or Firm:
Honigman LLP/Nike (650 Trade Centre Way Suite 200, Kalamazoo, MI, 49002-0402, US)
Claims:
What is claimed is:

1. A high performance golf ball comprising: a modified high Mooney viscosity rubber having less than about 20 pounds per 100 pounds of rubber (phr) of oil, the modified high Mooney viscosity rubber comprising high Mooney viscosity rubber having a Mooney viscosity at least about 40 blended with between about 1 phr and about 10 phr of process oil and between about 0.05 phr and about 5 phr of a peptizing agent.

2. The golf ball of claim 1, the golf ball further comprising a core layer, wherein the modified high Mooney viscosity rubber is in the core layer.

3. The golf ball of claim 1, the golf ball further comprising an inner cover layer, wherein the modified high Mooney viscosity rubber is in the inner cover layer.

4. The golf ball of claim 1, wherein the high Mooney viscosity rubber is selected from the group consisting of polybutadiene rubber, polyisoprene rubber, natural rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene-butadiene rubber, and blends thereof.

5. The golf ball of claim 4, wherein the high Mooney viscosity rubber is polybutadiene rubber.

6. The golf ball of claim 5, wherein the polybutadiene rubber comprises greater than about 90 percent cis structure.

7. The golf ball of claim 1, wherein the amount of the process oil is between about 2 phr and about 7.5 phr.

8. The golf ball of claim 1, wherein the process oil is selected from the group consisting of process oils, vegetable oils, vulcanized or functionalized vegetable oils, oils from animals, functionalized oils, and blends thereof.

9. The golf ball of claim 8, wherein the process oil is selected from the group consisting of naphthenic oils, paraffinic oils, and blends thereof.

10. The golf ball of claim 8, wherein the vulcanized or functionalized vegetable oils are selected from the group consisting of epoxidized soy bean oil, epoxidized linseed oil, epoxidized alkyl oils, the reaction products of epoxidized oil with a peroxide, an amine, a polyamide, or an isocyanate-containing molecule, and blends thereof.

11. The golf ball of claim 10, wherein the functionalized vegetable oil is epoxidized soy bean oil.

12. The golf ball of claim 4 wherein the peptizing agent is pentachlorothiophenol.

13. The golf ball of claim 8 wherein the peptizing agent is pentachlorothiophenol.

14. The golf ball of claim 2, the golf ball further comprising an inner cover layer, wherein the inner cover layer comprises HNP.

15. The golf ball of claim 14, wherein the HNP is selected from the group consisting of HPF1000, HPF2000, HPF AD1024, HPF AD1027, HPF AD1030, HPF AD1035, HPF AD1040, and blends thereof.

16. The golf ball of claim 14, wherein the relative weight proportions of the modified high Mooney viscosity polybutadiene rubber to HNP in a blended product range from about 60:40 to about 99.5:0.5.

17. The golf ball of claim 16, wherein relative weight proportions of the modified high Mooney viscosity polybutadiene rubber to HNP in a blended product range from about 75:25 to about 99:1.

18. The golf ball of claim 2, wherein the golf ball further comprises a layer essentially surrounding the core, the layer comprising HNP.

19. The golf ball of claim 2, wherein the core consists essentially of modified high Mooney viscosity polybutadiene rubber and the layer consists essentially of HNP.

20. The golf ball of claim 3, the golf ball further comprising an outer cover, the outer cover comprising polyurethane.

Description:

BACKGROUND

The present disclosure relates generally to a golf ball comprising modified high Mooney viscosity rubber. The disclosure also relates to a high performance golf ball comprising the modified high Mooney viscosity rubber in a core layer.

Golf balls are important sporting goods that have changed with changes in technology. For example, balls were first made of wood, and then by stuffing boiled, softened feathers into a leather sack. The sack typically was painted white, and would tighten upon drying. However, because the feather ball tended to absorb moisture and to split, many balls were required to play a round. Also, these feather balls were expensive as compared with wooden balls.

Both feather and wooden balls were in use until the gutta percha ball was made. The gutta percha ball was relatively inexpensive and easily manufactured. Also, the gutta percha ball was fairly durable, as compared with the feather ball, performed well because the surface could easily be roughened to improve flight characteristics, and so became popular. However, the ball exhibited a tendency to break up in flight.

Golf balls comprising other elastic materials then were developed. For example, a golf ball having a rubber core and an elastic thread wound tightly around the core was developed. The winding was covered with gutta percha at first, but later with balata. However, balata-covered golf balls often are damaged by players who are less skilled at striking the ball. Thus, tougher covers were developed, including in particular covers comprising a Surlyn® compound or a polyurethane compound.

The interior structure of the golf ball has advanced, with plastics and polymeric materials having properties and characteristics appropriate for manufacture of high-quality, high-performance, affordable golf balls. In particular, polymeric materials having properties and characteristics appropriate for golf ball manufacture have been developed. Such polymeric materials include polyurethanes and ionomeric materials, including highly neutralized acid polymers. Blended materials also are used to manufacture other products.

However, the quest for such desirable golf balls sometimes is sabotaged by processing techniques that diminish the preferred properties and characteristics of the compositions used to form the golf ball. For example, high Mooney viscosity polybutadiene rubber has the properties and characteristics one would seek for a golf ball core, including in particular, a high coefficient of restitution (COR). The high viscosity exhibited by high Mooney viscosity polybutadiene rubber makes it difficult to process. Thus, significant stresses are placed on processing equipment, and the period required to process the high Mooney viscosity polybutadiene rubber to form part of a golf ball, particularly part of the core, is long.

A typical way to reduce the viscosity of high Mooney viscosity polybutadiene rubber is to incorporate oils and other materials to reduce the viscosity of the high Mooney viscosity polybutadiene rubber. Thus, extender oil and lubricant compositions often are added to high Mooney viscosity rubber to ameliorate the difficulties in processing and forming. Typically, such compositions are added in large quantity, most typically greater than about 30 phr, and often as much as 500 phr. However, adding extender oil or such viscosity-reducing material in an amount sufficient to make processing appreciably easier, typically greater than about 30 phr, tends to reduce the COR and to degrade the desired properties and characteristics of the rubber.

Other additives also have been used in an attempt to ameliorate processing and forming difficulties with high Mooney viscosity polybutadiene rubber without significantly degrading the performance properties and characteristics sought. For example, traditional plasticizers such as phthalate esters have been utilized, but they are expensive and sometimes difficulty compatible with high Mooney viscosity polybutadiene rubber. Similarly, fatty acids and metal soaps also are expensive and tend not to adhere well, but rather exhibit ‘waxy’ behavior.

Another type of composition often used as a core layer in a golf ball is the highly neutralized polymer, or HNP. These materials have a high COR, but sometimes lack other properties and characteristics sought for golf ball performance.

Therefore, there exists a need in the art for a high-performance golf ball that includes components that are easily and efficiently processed. Such a golf ball exhibits high performance and can be produced without undue processing difficulty.

SUMMARY

In one aspect, the disclosure provides a golf ball that comprises modified high Mooney viscosity rubber.

In another aspect, the disclosure provides a high performance golf ball comprising the modified high Mooney viscosity rubber in a core layer.

In yet another aspect, the disclosure provides a high performance golf ball comprising both modified high Mooney viscosity rubber and HNP in separate core layers.

In still another aspect, the disclosure provides a high performance golf ball comprising both modified high Mooney viscosity rubber and HNP in separate core layers and an HNP cover layer.

Other systems, methods, features, and advantages of the invention will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the invention, and be protected by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 shows a representative golf ball in accordance with this disclosure, the golf ball being of a two-piece construction;

FIG. 2 shows a second representative golf ball, having a core, an inner cover layer, and an outer cover layer;

FIG. 3 shows a third representative golf ball, having an inner core, an outer core layer, and a cover layer; and

FIG. 4 shows a fourth representative golf ball, having an inner core, an outer core layer, an inner cover layer, and an outer cover layer.

DETAILED DESCRIPTION

As used herein, unless otherwise stated, compression deformation, hardness, COR, flexural modulus, and Vicat softening temperature are measured as follows:

A. Compression deformation: The compression deformation herein indicates the deformation amount of the ball, or any portion thereof, under a force; specifically, when the force is increased to become 130 kg from 10 kg, the deformation amount of the ball or portion thereof under the force of 130 kg reduced by the deformation amount of the ball or portion thereof under the force of 10 kg is the compression deformation value of the ball or portion thereof.

B. Hardness: Hardness of a golf ball layer is measured generally in accordance with ASTM D-2240, but measured on the land area of a curved surface of a molded ball.

C. Method of measuring COR: A golf ball for test is fired by an air cannon at an initial velocity of 40 m/sec, and a speed monitoring device is located over a distance of 0.6 to 0.9 meters from the cannon. The golf ball strikes a steel plate positioned about 1.2 meters away from the air cannon and rebounds through the speed-monitoring device. The return velocity divided by the initial velocity is the COR.

D. Flexural modulus: Measured in accordance with ASTM D-790.

E. Vicat softening temperature: Measured in accordance with ASTM D-1525.

F. Mooney viscosity is measured herein by a Mooney Shearing Disk Viscometer in accordance with ASTM D1646. The viscometer is run at a defined temperature, which is 100° C. herein. The resultant value, identified as (ML1+4 (100° C.)) and expressed as a number, is an indication of the torque on the viscometer's rotating spindle within heated dies.

G. Compression often is measured with a device from ADC, and typically is reported in millimeters (mm). An ADC compression tester, commercially available from Automated Design Corp. in Illinois, USA, can be used to carry out this determination. The ADC compression tester can be set to apply a first load and obtain a first deformation amount, and then, after a selected period, to apply a second, typically higher load and determine a second deformation amount. Thus, the first load herein is 10 kg, the second load herein is 130 kg, and the compression deformation is the difference between the second deformation and the first deformation. Herein, this distance is reported in millimeters. The compression can be reported as a distance, or as an equivalent to other deformation measurement techniques, such as Atti compression.

The disclosure provides a golf ball that comprises modified high Mooney viscosity rubber. In particular, the disclosure provides a high performance golf ball comprising the modified high Mooney viscosity rubber in a core layer.

High Mooney viscosity rubber is defined herein as a rubber having a Mooney viscosity value of at least about 40, typically at least about 50. In embodiments of the disclosure, high Mooney viscosity rubber is modified by addition of less than about 10 phr (pounds per hundred pounds of rubber) of process oil and less than about 5 phr peptizing agent to form modified high Mooney viscosity rubber.

High Mooney viscosity rubber has desirable properties and characteristics for use in golf balls. For example, high Mooney viscosity rubber has high COR, low cold flow, and higher molecular weight. Low cold flow and high molecular weight imbue the high Mooney viscosity rubber with excellent durability. However, high Mooney viscosity rubber typically is difficult to process because both mixing and extruding are difficult. Also, forming a golf ball layer from high Mooney viscosity rubber typically is difficult because molding high Mooney viscosity rubber typically is difficult.

The inventors have discovered that it is possible to use only small amounts of process oil, i.e., less than about 10 phr, in combination with less than about 5 phr peptizing agent to yield modified high Mooney viscosity rubber. The inventors have discovered that this combination provides processing and forming advantages over unmodified high Mooney viscosity rubber while maintaining most of the sought-after properties and characteristics, particularly COR. Importantly, the inventors also have discovered that judicious use of a combination of modified high Mooney viscosity rubber and HNP in separate core layers provides a golf ball core that yields excellent COR and a high performance golf ball that can be made with reduced processing difficulty.

In yet another aspect, therefore, the disclosure provides a high performance golf ball comprising both modified high Mooney viscosity rubber and HNP in separate core layers. The HNP further ameliorates the reduction in COR caused by addition of the process oil and provides additional hardness and resilience to the core layers.

In still another aspect, the disclosure provides a high performance golf ball comprising both modified high Mooney viscosity rubber and HNP in separate core layers and an HNP cover layer. The HNP cover layer provides not only high performance spin control and an excellent flight path, but also excellent scuff resistance.

In yet another aspect, the disclosure provides a high performance golf ball comprising both modified high Mooney viscosity rubber and HNP in separate core layers and a polyurethane cover. Further, the polyurethane cover may be cross-linked or otherwise treated to provide scuff resistance.

The disclosure relates to golf balls having 2 or more layers. If the golf ball has only 2 layers, the core is modified high Mooney viscosity rubber and the cover is HNP. However, it is more typical for golf balls that benefit from this disclosure to have at least 3 layers.

FIG. 1 illustrates a 2-layer or 2-piece golf ball 100 having core 120 essentially surrounded by cover layer 110. In this golf ball embodiment, core 120 comprises modified high Mooney viscosity rubber and cover layer 110 comprises HNP or another suitable cover material, such as polyurethane.

FIG. 2 illustrates a 3-piece golf ball 200 having a relatively large core 230 essentially surrounded by inner cover layer 220, which itself is encompassed within or essentially surrounded by outer cover layer 210. In this golf ball embodiment, core 230 comprises modified high Mooney viscosity rubber, inner cover layer 220 typically comprises HNP, and outer cover layer 210 comprises HNP (whether the same as or different from the HNP used in inner cover layer 220), polyurethane, or another cover layer material.

FIG. 3 illustrates 3-piece golf ball 300 having a relatively smaller inner core 330, outer core layer 320, and cover layer 310. In this golf ball embodiment, inner core 330 comprises modified high Mooney viscosity rubber, outer core layer 320 typically comprises HNP, and cover layer 310 comprises HNP (whether the same as or different from the HNP used in inner cover layer 320), polyurethane, or another cover layer material.

FIG. 4 illustrates 4-piece golf ball 400 having inner core 440, outer core layer 430, inner cover layer 420, and outer cover layer 410. In this golf ball embodiment, inner core 440 comprises modified high Mooney viscosity rubber, outer core layer 430 typically comprises HNP, and cover layers 420 and 410 comprise other cover layer materials, such as HNPs, ionomers, polyurethane, and other materials. In another golf ball embodiment, inner core 440 comprises typical core material, including modified high Mooney viscosity rubber, outer core layer 430 typically comprises HNP, inner cover layer 420 comprises modified high Mooney viscosity rubber, and outer cover layer 410 comprise other cover layer materials, such as HNPs, ionomers, polyurethane, and other materials.

Thus, in embodiments of the disclosure, modified high Mooney viscosity rubber typically is used in the inner core, but also can be used in the outer core layer, if present, and in the inner cover layer, if present. Modified high Mooney viscosity rubber also can be used in two layers of the same golf ball. Typically, modified high Mooney viscosity rubber is not used as outer cover material because of the tendency of the process oil to bloom and become separated from the high Mooney viscosity rubber. There are materials, such as maleic anhydride, silanes, and titanates, that can be used to compatibilize the process oil and the high Mooney viscosity rubber. However, the separation tendency typically is better managed, and more easily managed, in a layer that is essentially encompassed within another layer.

In embodiments of the disclosure, modified high Mooney viscosity rubber comprises high Mooney viscosity rubber blended with process oil and a peptizing agent. Although the inventors do not wish to be bound by theory, it is believed that process oils aid the processing and forming of the rubber by serving as a physical peptizer that reduces viscosity without shortening rubber chain length. Further, it is believed that a peptizing agent acts as a chemical peptizer, shortening chain length by scission to reduce viscosity. Process oils are present at less than about 10 phr, typically between about 1 phr and about 9 phr, more typically between about 2 phr and about 8 phr, and most typically between about 2 phr and 7.5 phr. Peptizing agents are present in an amount between about 0.01 phr and about 5.0 phr, typically between about 0.1 phr and about 4 phr, and more typically between about 0.2 phr and about 1 phr.

The quantity of oil disclosed herein is in addition to any oils or similar lubricious materials that may have been added to the high Mooney viscosity rubber as a component of or carrier for another compound. For example, the skilled practitioner recognizes not only that rubber may have a small amount of extender oil in it as supplied, but also that some ingredients, additives, and modifiers may be supplied in oil or associated with oil. Typically, such materials are pulverulent compositions, and the amount of oil so supplied is relatively small and produces no adverse effects in the finished product. However, the potential exists for introducing amounts that, when accumulated, exceed that amount of oil that may produce adverse effects in finished product.

For example, the skilled practitioner is familiar with the Crystex® family of sulfur delivery products. These products comprise sulfur and oil in quantities between about 10 wt percent and 30 wt percent, based on the weight of the Crystex® product. Although the inventors do not wish to be bound by theory, it is believed that this oil serves both to suppress the tendency of pulverulent sulfur to fly into the air, causing a potential health and safety hazard, and to aid in dispersion of the sulfur in the rubber. Whereas the skilled practitioner recognizes that this sulfur-containing product typically is not used in rubber to be used in the manufacture of golf balls, Crystex® is a well-known product that exemplifies this type of product. Oil may be introduced as a dispersant and as a dust-reducing composition in conjunction with sulfur and other pulverulent solids or other materials that are difficult to blend with or disperse in rubber or tend to become dispersed in air. Thus, this oil often is called ‘dispersant oil’. Also, the rubber may be ‘extended’ rubber, i.e., rubber already containing extender oil.

In embodiments of the disclosure, the total amount of oil in rubber, i.e., the sum of process oil, dispersant oil, and extender oil already present in the rubber, is less than about 20 phr, typically between about 1 phr and about 18 phr, and more typically between about 2 phr and about 15 phr. The amount of process oil is less than about 10 phr, and typically is between about 1 phr and about 9 phr in embodiments of the disclosure. In other embodiments of the disclosure, process oil more typically is between about 2 phr and about 8 phr, most typically between about 2 phr and about 7.5 phr. Further, the amount of dispersant oil and extender oil present typically is less than about 10 phr. If the amount of these oils exceeds about 10 phr, the maximum amount of process oil introduced in embodiments of the disclosure typically is limited to that amount that will ensure that the total amount of oil does not exceed about 20 phr. With the guidance provided herein, the skilled practitioner will be able to select components of the rubber that limit the amount of oil present in the rubber.

In this disclosure, high Mooney viscosity rubber is defined as rubber having Mooney viscosity greater than about 40, or greater than about 50, or greater than about 55, or greater than about 60, or greater than about 65, or greater than about 70. Mooney viscosity is measured as set forth in the definitions.

High Mooney viscosity rubber is selected from the group consisting of polybutadiene rubber, polyisoprene rubber, natural rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene-butadiene rubber, and blends thereof, that have Mooney viscosity value greater than about 40, or greater than about 50, or greater than about 55, or greater than about 60, or greater than about 65, or greater than about 70. In embodiments of the disclosure, the high Mooney viscosity rubber comprises, in major part, polybutadiene rubber. For convenience herein, the disclosure will focus on high Mooney viscosity polybutadiene rubber, and the modified high Mooney viscosity polybutadiene rubber resulting therefrom upon addition of process oil and peptizing agent.

In embodiments of the disclosure, the high Mooney viscosity polybutadiene rubber comprises high-cis high Mooney viscosity polybutadiene rubber, typically neodymium-catalyzed polybutadiene rubber. Cobalt-catalyzed and nickel-catalyzed versions also are suitable.

The skilled practitioner recognizes that polybutadiene rubber is available in various versions, including high-cis (greater than about 92 percent cis structure, typically with less than about 4 percent trans and less than about 4 percent vinyl); low-cis (as little as about 35 percent cis structure) and vinyl, all of which structures is suitable in embodiments of the disclosure.

Typically, high-cis high Mooney viscosity polybutadiene rubber is used in accordance with the disclosure herein. Polybutadiene having primarily trans structure is not an elastic product, but rather is a crystalline, plastic product. Therefore, polybutadiene comprising primarily trans structure typically is not used as a rubber (elastic) product and so would not be suitable for use in this disclosure, although small amounts of crystalline trans polybutadiene in elastomeric polybutadiene rubber are to be expected, and do not adversely affect the properties and characteristics of the elastic polybutadiene rubber product.

In embodiments of the disclosure, members of the Buna CB family or series of polybutadiene rubber having a Mooney viscosity greater than about 50, available from Lanxess USA, Texas, USA, are suitably used. In particular, Buna CB 21, a highly linear neodymium-catalyzed butadiene rubber having a Mooney viscosity of 73; Buna CB 22 and Buna Nd 60, each a highly linear neodymium-catalyzed butadiene rubber having a Mooney viscosity of 63, and Buna CB 1221, a branched cobalt-catalyzed butadiene rubber having a Mooney viscosity of 53, are suitable in embodiments of the disclosure.

Other high Mooney viscosity polybutadiene rubbers suitable for use in embodiments of the disclosure include LG BR1208, which has a Mooney viscosity of 40 and is available from LG Chem, LTD, Korea, and Kumho 60, which has a Mooney viscosity of 60 and is available from Kumho, Korea.

The high Mooney viscosity polybutadiene rubber typically is cured using a conventional curing process. Suitable curing processes include, for example, peroxide curing, radiation curing, and combinations thereof.

In one embodiment, the high Mooney viscosity polybutadiene rubber is peroxide cured. Organic peroxides suitable as free radical initiators include, for example, dicumyl peroxide (DCP); n-butyl-4,4-di(t-butylperoxy)valerate; 1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane (TMCH); 2,5-dimethyl-2,5-di(t-butylperoxy)hexane; di-t-butyl peroxide; di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide; 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3; di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoyl peroxide; t-butyl hydroperoxide; and combinations thereof. Peroxide free radical initiators are generally present in the rubber compositions in an amount within the range having a lower limit of 0.05 phr, or 0.1 phr, or 0.25 phr, or 1 part, or 1.5 phr, and an upper limit of 2.5 phr, or 3 phr, or 5 phr, or 6 phr, or 10 phr, or 15 phr.

Co-agents can be used with peroxides to improve the cure. Suitable co-agents include, for example, metal salts of unsaturated carboxylic acids having from 3 to 8 carbon atoms; unsaturated vinyl compounds and polyfunctional monomers (for example, trimethylolpropane trimethacrylate); phenylene bismaleimide; and combinations thereof. Particularly suitable metal salts include, for example, one or more metal salts of acrylates, diacrylates, methacrylates, and dimethacrylates, wherein the metal is selected from magnesium, calcium, zinc, aluminum, lithium, and nickel. In a particular embodiment, the co-agent is selected from zinc salts of acrylates, diacrylates, methacrylates, and dimethacrylates. In another particular embodiment, the co-agent is zinc diacrylate (ZDA). When the agent is zinc diacrylate and/or zinc dimethacrylate, the co-agent is typically included in the rubber composition in an amount within the range having a lower limit of 1 phr, or 5 phr, or 10 phr, or 20 phr, and an upper limit of 25 phr, or 30 phr, or 35 phr, or 40 phr, or 50 phr, or 60 phr. When one or more less active co-agents are used, such as zinc monomethacrylate and various liquid acrylates and methacrylates, the amount of less active co-agent used may be the same as or higher than for zinc diacrylate and zinc dimethacrylate co-agents.

High energy radiation sources capable of generating free radicals may also be used to crosslink the high Mooney viscosity polybutadiene rubber. Suitable examples of such radiation sources include, for example, electron beams, ultra-violet radiation, gamma radiation, X-ray radiation, infrared radiation, heat, and combinations thereof. Free radical initiators known in the art also may be used.

With the guidance provided herein, the skilled practitioner will be able to select a curing agent or combinations thereof to cure the high Mooney viscosity polybutadiene rubber.

Other compositions may be added to the high Mooney viscosity polybutadiene rubber. For example, a cis-to-trans conversion compound, such as halogenated organosulfur compounds, may be added. Anti-oxidant compounds also may be present. The skilled practitioner is familiar with these compounds and can select suitable compounds and the amount thereof to provide the desired result.

Further, as described above, the disclosure relates to golf balls having at least 2 layers, or pieces. Thus, although discussion herein is directed to a 4-piece ball for convenience, the disclosure is directed to golf balls having at least 2-layers, and as many as 5, 6, or 7 layers, or more. The number of layers in the golf ball is limited only by any rules extant at the time of manufacture if the ball is to be “conforming,” i.e., meet the rules of a governing body such as the USGA.

Process oil added to the high Mooney viscosity polybutadiene rubber is selected from the group consisting of process oils, vegetable oils, vulcanized or functionalized vegetable oils, oils from animals, functionalized oils, and blends thereof. Typically, process oil is selected from the group consisting of process oils, vegetable oils, functionalized vegetable oils, and blends thereof. More typically, process oil is vegetable oil, functionalized vegetable oil, and blends thereof.

Suitable process oils include, for example, aromatic oils, naphthenic oils, and paraffinic oils, as classified by ASTM D2226. As the skilled practitioner recognizes, such oils typically are a blend of aromatic, naphthenic, and paraffinic oils, and are classified by the predominant types of properties and characteristics of the oil. In an embodiment, the process oil is selected from paraffinic oil, naphthenic oil, and blends thereof. Aromatic oils lower viscosity more than the same quantity of naphthenic oil or paraffinic oil, but may cause concern over potential health threats.

Aromatic oils include the Sundex® family of aromatic oils available from many sources, including American Lubricants & Chemicals, LLC, in Ohio, USA. Particularly suitable paraffinic and naphthenic oils include, for example, Sunpar® paraffinic oil, a family of oils commercially available from Sunoco, Inc. of Pennsylvania, USA and HollyFrontier Refining and Marketing; Paralux® paraffinic oil, a family of oils commercially available from Chevron Corporation of California, USA; Unithene® naphthenic oil, a family of oils commercially available from Ergon, Inc. of Mississippi, USA; and the family of oils commercially available from Idemitsu USA under the name Diana Process Oil PS.

In some embodiments, suitable oils also include low PCA/PHA (polycyclic aromatic/polyaromatic hydrocarbon) oils, including mild extraction solvates (MES), treated distillate aromatic extracts (TDAE), and heavy naphthenic oils. Suitable low PCA oils are further disclosed in U.S. Pat. No. 6,977,276 (column 4, line 31 up to and including column 6, line 27), the entire disclosure of which is hereby incorporated herein by reference. Hydrogenated naphthenic oils, including those disclosed in U.S. Pat. No. 6,939,910, the entire disclosure of which is hereby incorporated herein by reference, also are suitable in some embodiments.

Suitable vegetable oils for use in embodiments of the disclosure include, for example, rapeseed oil, castor oil, linseed oil, soybean oil, and tung oil. Suitable vulcanized vegetable oils include, for example, semi-translucent factice, black factice, and brown factice; in particular, “F14” and “F17” sulfur vulcanized rapeseed oils, “K14D” sulfur vulcanized modified fatty acids, “Gloria 17” sulfur vulcanized rapeseed oil, “Hamburg 4” partially hydrogenated rapeseed oil, and “WP” peroxide crosslinked modified castor oil free of sulfur and chlorine, all of which are commercially available from R.T. Vanderbilt Company, Inc. of Norwalk, Conn.

Embodiments of the disclosure also use functionalized vegetable oil. Functionalized vegetable oils include, for example, epoxidized soy bean oil, epoxidized linseed oil, and epoxidized alkyl oils. One suitable epoxidized soy bean oil family is available from Arkema Inc., of Pennsylvania, USA, under the tradename Vikoflex®. Functionalized vegetable oils also include the reaction product of an epoxidized oil with a peroxide, an amine, a polyamide, or an isocyanate-containing molecule. Although the inventors do not wish to be bound by theory, epoxidized oil and functionalized oils can be incorporated into the polymeric structure of the modified high Mooney viscosity polybutadiene rubber. In any event, functionalized oils exhibit significantly less motility of the oil, thus reducing blooming of the oil, i.e., reducing separation of the oil from the modified high Mooney viscosity polybutadiene rubber.

Functionalizing moieties typically are present in an amount between about 0.5 phr and 10 phr, more typically between about 1 phr and 5 phr, and even more particularly between about 1.25 and 3 phr. Also, the functionalizing moiety typically comprises between about 5 wt percent and about 20 wt percent, based on the weight of the functionalized oil, more typically between about 8 wt percent and about 12 wt percent, based on the weight of the functionalized oil.

Suitable oils from animals include, for example, whale oil and fish oil.

In embodiments of the disclosure, suitable peptizing agents include compositions that contain an organic sulfur compound and/or a metal-containing organic sulfur compound in addition to the base rubber and the unsaturated carboxylic acid metal salt. Examples of the organic sulfur compound include thiophenols such as pentachlorothiophenol, 4-butyl-o-thiocresol, 4-t-butyl-p-thiocresol, and 2-benzamidothiophenol, thiocarboxylic acids such as thio-benzoic acid, and sulfides such as dixylyl disulfide, di(o-benzamidophenyl)disulfide and alkylated phenol sulfides. Examples of the metal-containing organic sulfur compound include zinc salts of the above-mentioned thiophenols and thiocarboxylic acids. The sulfur compounds may be used alone or in admixture of two or more. The sulfur compound is preferably blended in amounts of from about 0.05 to about 2 parts by weight, more preferably from about 0.1 to about 0.5 parts by weight per 100 parts by weight of the base rubber.

Typically, the peptizing agents are known conventionally as “soft and fast” agents. The conventional soft and fast agent is present in an amount within a range having a lower limit of about 0.05 phr or about 0.1 phr or about 0.2 phr or about 0.5 phr and an upper limit of about 0.05 phr or about 1 phr or about 2 phr or about 3 phr or about 5 phr. As used herein, “soft and fast agent” means any compound or a blend thereof that is capable of making a core softer (have a lower compression) at a constant COR, making a core faster (have a higher COR at equal compression), or a combination thereof, when compared to a core equivalently prepared without a soft and fast agent. Suitable conventional soft and fast agents include, but are not limited to, those selected from organosulfur and metal-containing organosulfur compounds, organic sulfur compounds, including mono-, di-, and poly-sulfides, thiol, and mercapto compounds, inorganic sulfide compounds, Group VIA compounds, substituted or unsubstituted aromatic organic compounds that do not contain sulfur or metal, aromatic organometallic compounds, and mixtures thereof.

Additional suitable soft and fast agents, or peptizing agents, include organosulfur compounds, such as the thiophenols, including pentafluorothiophenol; 2-fluorothiophenol; 3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol; 2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol 2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol; 2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol; 4-chlorotetrafluorothiophenol; pentachlorothiophenol; 2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol; 2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol; 3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol; 2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol; pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol; 4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol; 3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol; 3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol; 2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol; 2,3,5,6-tetraiodothiophenol; zinc salts thereof; non-metal salts thereof, for example, ammonium salt of pentachlorothiophenol; magnesium pentachlorothiophenol; cobalt pentachlorothiophenol; and combinations thereof.

Suitable metal-containing organosulfur compounds include, but are not limited to, cadmium, copper, lead, and tellurium analogs of diethyldithiocarbamate, diamyldithiocarbamate, and dimethyldithiocarbamate, and combinations thereof. Additional examples are disclosed in U.S. Pat. No. 7,005,479, the entire disclosure of which is hereby incorporated herein by reference.

Suitable disulfides include, but are not limited to, 4,4′-diphenyl disulfide; 4,4′-ditolyl disulfide; 4,4′-dixylyl disulfide; 2,2′-benzamido diphenyl disulfide; bis(2-aminophenyl)disulfide; bis(4-aminophenyl)disulfide; bis(3-aminophenyl)disulfide; 2,2′-bis(4-aminonaphthyl)disulfide; 2,2′-bis(3-aminonaphthyl)disulfide; 2,2′-bis(4-aminonaphthyl)disulfide; 2,2′-bis(5-aminonaphthyl)disulfide; 2,2′-bis(6-aminonaphthyl)disulfide; 2,2′-bis(7-aminonaphthyl)disulfide; 2,2′-bis(8-aminonaphthyl)disulfide; 1,1′-bis(2-aminonaphthyl)disulfide; 1,1′-bis(3-aminonaphthyl)disulfide; 1,1′-bis(3-aminonaphthyl)disulfide; 1,1′-bis(4-aminonaphthyl)disulfide; 1,1′-bis(5-aminonaphthyl)disulfide; 1,1′-bis(6-aminonaphthyl)disulfide; 1,1′-bis(7-aminonaphthyl)disulfide; 1,1′-bis(8-aminonaphthyl)disulfide; 1,2′-diamino-1,2′-dithiodinaphthalene; 2,3′-diamino-1,2′-dithiodinaphthalene; bis(4-chlorophenyl)disulfide; bis(2-chlorophenyl)disulfide; bis(3-chlorophenyl)disulfide; bis(4-bromophenyl)disulfide; bis(2-bromophenyl)disulfide; bis(3-bromophenyl)disulfide; bis(4-fluorophenyl)disulfide; bis(4-iodophenyl)disulfide; bis(2,5-dichlorophenyl)disulfide; bis(3,5-dichlorophenyl)disulfide; bis(2,4-dichlorophenyl)disulfide; bis(2,6-dichlorophenyl)disulfide; bis(2,5-dibromophenyl)disulfide; bis(3,5-dibromophenyl)disulfide; bis(2-chloro-5-bromophenyl)disulfide; bis(2,4,6-trichlorophenyl)disulfide; bis(2,3,4,5,6-pentachlorophenyl)disulfide; bis(4-cyanophenyl)disulfide; bis(2-cyanophenyl)disulfide; bis(4-nitrophenyl)disulfide; bis(2-nitrophenyl)disulfide; 2,2′-dithiobenzoic acid ethylester; 2,2′-dithiobenzoic acid methylester; 2,2′-dithiobenzoic acid; 4,4′-dithiobenzoic acid ethylester; bis(4-acetylphenyl)disulfide; bis(2-acetylphenyl)disulfide; bis(4-formylphenyl)disulfide; bis(4-carbamoylphenyl)disulfide; 1,1′-dinaphthyl disulfide; 2,2′-dinaphthyl disulfide; 1,2′-dinaphthyl disulfide; 2,2′-bis(1-chlorodinaphthyl)disulfide; 2,2′-bis(1-bromonaphthyl)disulfide; 1,1′-bis(2-chloronaphthyl)disulfide; 2,2′-bis(1-cyanonaphthyl)disulfide; 2,2′-bis(1-acetylnaphthyl)disulfide; and the like; and combinations thereof.

Suitable inorganic sulfide compounds include, but are not limited to, titanium sulfide, manganese sulfide, and sulfide analogs of iron, calcium, cobalt, molybdenum, tungsten, copper, selenium, yttrium, zinc, tin, and bismuth.

In particular, as noted herein, especially suitable peptizing agents, or soft and fast agents, for use in embodiments of the disclosure include, but are not limited to, zinc pentachlorothiophenol, pentachlorothiophenol, ditolyl disulfide, diphenyl disulfide, dixylyl disulfide, and mixtures thereof. The soft and fast agent component may also be a blend of an organosulfur compound and an inorganic sulfide compound.

Typically, the halogenated thiophenol peptizing agent is pentachlorothiophenol, which is commercially available in salt or neat form, or under the tradename STRUKTOL®, a clay-based carrier containing, in one form, pentachlorothiophenol (PCTP) loaded at 45 percent. STRUKTOL® is commercially available from Struktol Company of America of Ohio. PCTP is commercially available in neat form and in the zinc salt form from eChinachem of California, US. Suitable organosulfur compounds are further disclosed, for example, in U.S. Pat. Nos. 6,635,716, 6,919,393, 7,005,479 and 7,148,279, the entire disclosures of which are hereby incorporated herein by reference.

Further, in embodiments of the disclosure, activators may be used to accelerate peptization by starting the process at a lower temperature. Activators are chelates, or complexes, of ketoxime, phthalocyanine, or acetylacetone with metals such as iron, cobalt, nickel, or copper. Typically, the metal is iron. Because these activator compounds (chelates, or complexes) are highly effective, only small amounts are present with the peptizing agent.

The process oil and peptizing agent are mixed with high Mooney viscosity polybutadiene rubber to form modified high Mooney viscosity polybutadiene rubber in any suitable way. In some embodiments of the disclosure, the process oil, peptizing agent, and high Mooney viscosity polybutadiene rubber are kneaded or melt-blended in any suitable manner. Suitable equipment for blending the high Mooney viscosity polybutadiene rubber with the process oil and peptizing agent in accordance with this disclosure includes a twin screw extruder, a Banbury-type mixer, a two-roll mill (also known as a two-roll sheeter), or another manner of kneading the fairly stiff high Mooney viscosity polybutadiene rubber with the oil. Typically, kneading with a Banbury-type mixer, a two-roll mill, or any suitable kneading device is used to blend process oil and peptizing agent with high Mooney viscosity polybutadiene rubber.

In embodiments of the disclosure, the components are heated before introducing each to the kneader, two-roll mill, or other mixing device. The high Mooney viscosity polybutadiene rubber should be heated to a temperature below the scorch point, and the process oil should be heated to a temperature below the smoke point. The peptizing agent also can be heated, as appropriate. In this way, the time and significant energy input required for mixing the components will be reduced without reducing the quality of the product.

In embodiments of the disclosure, the modified high Mooney viscosity polybutadiene rubber is used in parts of a golf ball having at least 2 layers, typically in a golf ball having at least 3 layers, or pieces, and more typically in a golf ball having at least 4 layers. Typically, modified high Mooney viscosity polybutadiene rubber of the disclosure forms the core of a golf ball having at least 3 layers, or pieces, such as in core 230 of golf ball 200; core 330 of golf ball 300; and core 440 of golf ball 400. Embodiments of the disclosure also include golf balls having a core comprising modified high Mooney viscosity polybutadiene rubber and having 5 or more layers.

The inventors have discovered that substantially enclosing or substantially encompassing the modified high Mooney viscosity polybutadiene rubber core with a layer of HNP is particularly effective in forming a core or golf ball portion that has high COR. Thus, embodiments of the disclosure having a core comprising modified high Mooney viscosity polybutadiene rubber in the core advantageously have a cover 110 (two-piece), inner cover 220 (three-piece), outer core 320 (three-piece), or inner cover 430 (four-piece) comprising an HNP.

HNPs suitable for use in embodiments of the disclosure include highly neutralized terpolymer ionomers. HPF resins such as HPF1000, HPF2000, HPF AD1024, HPF AD1027, HPF AD1030, HPF AD1035, HPF AD1040, and other members of the HPF family of HNPs produced by E. I. DuPont de Nemours and Company, are exemplary of HNPs suitably used in embodiments of the disclosure. With the guidance provided herein, the skilled practitioner will be able to identify suitable HNPs to use to substantially encompass a core comprising modified high Mooney viscosity polybutadiene rubber disclosed herein.

Modified high Mooney viscosity polybutadiene rubber of embodiments of the disclosure also can be used to form an outer core layer (320 or 430) or an inner cover layer (220 or 420), also known as a mantle layer. Because the modified high Mooney viscosity polybutadiene rubber is dense, a thin inner cover layer may be useful in controlling spin and providing a high MOI golf ball.

For any arrangement of layers not specifically mentioned herein, any layer may be made of any material suitable for the purpose. For example, an outer cover layer should be tough and resistant to scuffing. Thus, thermoplastic polyurethane (TPU) and thermoset polyurethane are suitable for use in outer cover layers, as are HNP and ionomers. Thermoplastic polyurethane that is not scuff resistant without more can be treated to harden the surface, such as by a surface treatment. Suitable ionomers include members of the Surlyn® family of ionomeric polymers produced by E. I. DuPont de Nemours and Company and members of the Lotek® family of products produced by ExxonMobil Chemical Corporation.

The inventors also have discovered that modified high Mooney viscosity polybutadiene rubber of this disclosure can be blended with HNP to form a blended material that can be used in any layer the modified high Mooney viscosity polybutadiene rubber can be used. The blend has a high COR and is therefore particularly suited to serve as a core, particularly as an outer core, in a high performance golf ball. The blend may have a slightly higher density than the modified high Mooney viscosity polybutadiene rubber, and therefore also may form a suitable mantle (inner cover) layer.

The relative weight proportions of the modified high Mooney viscosity polybutadiene rubber to HNP in a blended product range from about 60:40 to about 99.5:0.5, typically from about 70:30 to about 99:1, and more typically from about 75:25 to about 99:1.

The modified high Mooney viscosity polybutadiene rubber and the HNP can be mixed in the same way the modified high Mooney viscosity polybutadiene rubber is made, i.e., on a two-roll sheeter or other kneading device. A compatibilizer or linker for the rubber and the HNP likely would be required to form a coherent blend of these components.

The modified high Mooney viscosity polybutadiene rubber disclosed herein, and the blend of modified high Mooney viscosity polybutadiene rubber with HNP, also may be suitably used as an outer cover layer. If the modified high Mooney viscosity polybutadiene rubber or the blend is used as an outer cover layer, it is typical to ensure that the process oil does not ‘bloom’ and separate from the high Mooney viscosity polybutadiene rubber. In that case, and in any other circumstance in which it is important to maintain excellent compatibility, a compatibilizer can be employed.

Compatibilizers include maleic anhydride, silanes, and titanates. The skilled practitioner recognizes that the silanes have the general formula SinH2n+2. Typically, n is less than about 8, as larger molecules are only difficulty made. The titanates are compounds known to the skilled practitioner. For example, the Ken-React® family of titanate coupling agents, available from Kenrich Petrochemical, Inc., of New Jersey, USA, are suitable titanates. Suitable titanates include monoalkoxy titanates, such as KR® TTS (Titanium IV 2-propanolato, tris isooctadecanoato-O) and KR 7 (Titanium IV bis 2-methyl-2-propenoato-O, isooctadecanoato-O 2-propanolato); oxyacetate chelate titanates, such as KR® 134S (Titanium IV bis[4-(2-phenyl)-2-propyl-2]phenolato, oxoethylenediolato) and KR 138S (Titanium IV bis(dioctyl)pyrophosphato-O, oxoethylenediolato, (adduct), (dioctyl)(hydrogen)phosphite); A,B ethylene chelate titanates, such as KR® 212 (Titanium IV bis(dioctyl)phosphato-O, ethylenediolato) and KR 238S (Titanium IV bis(dioctyl)pyrophosphato-O, ethylenediolato (adduct), bis(dioctyl)hydrogen phosphite); quaternary titanates, such as KR® 138D (Titanium IV bis(dioctyl)pyrophosphato-O, oxoethylenediolato, (adduct) 2 moles of 2-N,N-dimethylamino-2-methylpropanol) and KR 158D (Titanium IV bis(butyl methyl)pyrophosphato-O, (adduct) 2 moles 2-N,N-dimethylamino-2-methylpropanol); coordinate titanates, such as KR® 41B (Titanium IV tetrakis 2-propanolato, adduct 2 moles (dioctyl)hydrogen phosphate) and KR 46B (Titanium IV tetrakis octanolato adduct 2 moles (di-tridecyl)hydrogen phosphite); neoalkoxy titanates, such as LICA® 01 (Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris neodecanoato-O) and LICA 09 (Titanium IV 2,2(bis 2-propenolatomethyl)butanolato, tris(dodecyl)benzenesulfonato-O); and cycloheteroatom titanates, such as KR® OPPR (Titanium IV bis octanolato, cyclo(dioctyl)pyrophosphato-O,O) and KR OPP2 (Titanium IV bis cyclo(dioctyl)pyrophosphato-O,O). With the guidance provided herein, the skilled practitioner will be able to identify suitable titanates for use in embodiments of the disclosure.

The skilled practitioner recognizes that the layers, or pieces, also may include further components such as fillers and/or additives. Fillers and additives may be used based on any of a variety of desired characteristics, such as enhancement of physical properties, UV light resistance, and other properties. For example, to improve UV light resistance, a light stabilizer is added. Light stabilizers may include hindered amines, UV stabilizers, or a mixture thereof.

Inorganic or organic fillers can be also added to any layer. Suitable inorganic fillers may include silicate minerals, metal oxides, metal salts, clays, metal silicates, glass fibers, natural fibrous minerals, synthetic fibrous minerals or a mixture thereof. Suitable organic fillers may include carbon black, fullerene and/or carbon nanotubes, melamine colophony, cellulose fibers, polyamide fibers, polyacrylonitrile fibers, polyurethane fibers, polyester fibers based on aromatic and/aliphatic dicarboxylic acid esters, carbon fibers or a mixture thereof. The inorganic and organic fillers may be used individually or as a mixture thereof. The total amount of the filler may be from about 0.5 to about 50 percent by weight of the layer.

Other density adjusting agents, such as hollow beads that have a low density, also may be used in selected layers.

The skilled practitioner recognizes that these additives, including in particular the density adjusters, affect the performance properties and characteristics of the layer. Thus, the amount of any fillers may not exceed that amount that adversely affects the performance of the golf ball.

Flame retardants may also be used to improve the flame resistance of any layer, and particularly of thermoplastic polyurethane. Suitable flame retardants may include organic phosphates, metal phosphates, metal polyphosphates, metal oxides (such as aluminum oxide hydrate, antimony trioxide, arsenic oxide), metal salts (such as calcium sulfate, expandable graphite), and cyanuric acid derivatives (such as melamine cyanurate). These flame retardants may be used individually or as a mixture thereof, and the total amount of the flame retardant may be from about 10 to about 35 percent by weight of a polyurethane component, for example.

To improve toughness and compression rebound of thermoplastic polyurethane elastomer, the thermoplastic polyurethane elastomer may include at least one dispersant, such as a monomer or oligomer comprising unsaturated bonds. Examples of suitable monomers include styrene, acrylic esters; suitable oligomers include di- and tri-acrylates/methacrylates, ester acrylates/methacrylates, urethane, or urea acrylates/methacrylates.

The outermost layer of a golf ball also may include at least one white pigment to aid in better visibility. The white pigment may be selected from the group consisting of titanium dioxide, zinc oxide or a mixture thereof.

With the guidance provided herein, the skilled practitioner will be able to select additives for each layer or piece of the golf ball.

Examples

Nine golf ball cores were made and tested for selected performance properties and characteristics. The effects of process oil loading, process oil type, high Mooney viscosity polybutadiene rubber type, and filler type were studied. The compositions of the golf ball cores was as follows in Table 1, and the proportions and identities of the high Mooney viscosity polybutadiene rubbers and process oils were as set forth in Table 2:

TABLE 1
Compositions of Golf Balls
Recipe12
Rubber, pounds100100
Zinc diacrylate, phr23.623.6
Zinc oxide, phr23.26.5
Zinc stearate, phr33
Barium sulfate, phr17
Dicumyl peroxide, phr0.30.3
1,1-di(t-butylperoxy)3,3,5-0.30.3
trimethylcyclohexane (TMCH), phr

TABLE 2
Golf ball core Proportions
GolfRubberProcessProcess oil
BallRecipetypeoil typeamount, phr
11BR1208None0
21BR1208Sunpar 1507.5
31BR1208Sunpar 15015
42BR1208None0
52K60None0
62K60327.5
72K603215
82K60Sunpar 15015
92K60Sunpar 228015

BR1208, available from LG Chem, has a Mooney viscosity of 40. K60 is Kumho 60, available from Kumho. K60 has a Mooney viscosity of 60. Each of the process oils is a paraffinic process oil.

The cores were prepared by curing the rubber for 8 minutes at 327° F.

Each of the golf ball cores was tested to determine Compression (ADC machine), COR, and approximate weight. The results were summarized in Table 3, as follows:

TABLE 3
Performance properties and characteristics
GolfCompressionWeight,
ball core(ADC), mmCORgrams
13.960.783239.5
24.990.755338.9
36.450.727838.5
44.120.779439.5
53.880.788939.3
64.980.757338.6
75.840.740138.3
86.090.732738.3
96.590.722138.3

As can be seen from this information, the increase in ADC compression values as process oil loading increases, the reduction in COR as process oil loading increases, and the reduction in COR as ADC compression increases were essentially linear for each combination of process oil and high Mooney viscosity polybutadiene rubber type. Although the inventors do not wish to be bound by theory, performance decreases are the consequence of the reduction in proportion, or dilution of the rubber proportion, as process oil amount is increased. The volume percent of rubber is 82.6 vol percent, 77.6 vol percent, and 73.2 vol percent, for 0 phr process oil, 7.5 phr process oil, and 15 phr process oil, respectively.

Additional properties and characteristics were determined for golf ball cores 1 and 4 to evaluate golf ball core properties and characteristics for different fillers. The results were summarized in Table 4 below. The results illustrated that the performance properties and characteristics of the two golf ball cores are quite similar. Although the inventors do not wish to be bound by theory, it is believed that any differences between the properties and characteristics of the two golf ball cores is the result of differences in density and high Mooney viscosity polybutadiene rubber concentration, i.e., lower density and high Mooney viscosity polybutadiene rubber concentration lead to lower COR and softer compression.

TABLE 4
Comparison of performance properties and
characteristics with different fillers
Golf ball core14
Recipe12
RubberBR1208BR1208
Theoretical density, g/cm31.13111.1264
Observed density, g/cm31.161.15
Vol percent Rubber82.6582.13
COR0.78320.7794
ADC Compression, mm3.964.12

Additional examples or golf ball cores are prepared in accordance with embodiments of the disclosure. The performance properties and characteristics of each are as described in this disclosure. Each of the values in Table 5A is weight. Table 5B expresses amounts of peptizing agent in phr.

TABLE 5A
Additional Examples
Golf ball core
12345678910
High Mooney viscosity98989893.593.593.598989898
polybutadiene rubber
Aromatic process oil26.5
Naphthenic process oil26.5
Paraffinic process oil26.5
Epoxidized soybean oil1.81.81.82
Amine0.2
Polyamide0.2
Isocyanate0.2
Total100100100100100100100100100100

TABLE 5B
Including Peptizing Agent
Golf ball core
12345678910
Penta-0.050.050.050.10.10.10.10.10.10.4
chlorothiophenol,
phr

While various embodiments of the invention have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. For example, different process oils, different high Mooney viscosity rubbers, and different proportions of oil and rubber may be used. Also, various modifications and changes may be made within the scope of the attached claims.