Patent Application
20240342563
This disclosure generally relates to golf balls, and more particularly relates to dual core golf balls having a specific construction for high playability on a wide variety of shots.
The performance of a golf ball is affected by a variety of factors including the materials, weight, size, dimple pattern, and external shape of the golf ball. Golf ball manufacturers are constantly improving or tweaking the performance of golf balls by adjusting the materials and construction of the ball as well as the dimple pattern and dimple shape.
The spin rate refers to the rate of rotation of the golf ball after being hit with a club. Golf balls with high spin rates generally feature three or four layers and typically include a solid core, one or two intermediate layers, and a relatively soft cover. Two piece golf balls that have a large core and a relatively thin, hard outer layer generally deliver less spin and maximum distance. In one aspect, more golf ball layers generally (but not always) equates to more spin.
Most professionals and low-handicap amateurs prefer golf balls with high spin rates to allow for better control in and around the green and draw and fade on approach shots. These types of golf balls are beneficial for short distance shots made with irons and wedges. In contrast, recreational players who cannot necessarily control the spin of the golf ball will likely find that it is easier to play with a low spin golf ball because the spin from a golf ball with a high spin rate can create more shot dispersion, i.e., more stray off to the left or right of the centerline, especially if the golf ball is hooked or sliced.
It would be desirable to provide a golf ball with improved spin control on shorter shots, while avoiding excessive spin and maintaining high speed on longer shots.
Exemplary golf balls are disclosed herein which, among other features, provide improved playability on a variety of types of shots. In one example, the golf ball comprises a core formed from polybutadiene rubber, butyl rubber, or a blend thereof. The core, which is also known as a dual core and core assemblage, can consist of an inner core and an outer core. The core can have a core hardness gradient (HGCORE) (in Shore C). A casing surrounds the core, and the casing is formed from ionomer. A cover surrounds the casing, and the cover is formed from polyurethane. The cover can be formed from polyurethane with an NCO content of no greater than 5.0%. The cover can have a cover thickness (TCOVER) (in inches) and is formed from a composition having a material hardness (HCM) (in Shore C). The golf ball has a golf ball hardness (HB) (in Shore C).
A soft-spin factor (S) of the golf ball can be defined by:
A ratio of the material hardness of the cover composition to cover thickness (HCM:TCOVER) can be less than 2,100. The ratio of the material hardness of the cover composition to cover thickness (HCM:TCOVER) can be 2,000-2,100.
The cover thickness (TCOVER) can be 0.028 inches-0.032 inches. The material hardness of the cover composition (HCM) can be 60 Shore C-64 Shore C.
The core hardness gradient (HGCORE), i.e., the hardness of the outer surface of the core assemblage minus the hardness of the geometric center of the core, can be at least +25 Shore C. A compression of the core assemblage can be 80 DCM-90 DCM.
A specific gravity of the core can be 1.15-1.16. A ratio of the inner core diameter (DIC) to an outer core diameter (DOC) can be 0.700-0.800. In another example, the ratio of the inner core diameter (DIC) to an outer core diameter (DOC) is 0.700-0.750. The ratio of the inner core diameter to the outer core diameter (DIC:DOC) and the soft-spin factor (S) can have the following relationship: 800≤DIC:DOC×S≤950. In one example, the ratio of the inner core diameter to the outer core diameter (DIC:DOC) and the soft-spin factor (S) can be 855-875.
In one example, the inner core can have an inner core diameter (DIC) of at least 1.10 inches.
The golf ball hardness (HB) can be no greater than 82 Shore C.
The golf ball can have a compression (CB) (in DCM), and the soft-spin factor (S) and the golf ball compression (CB) can have the following relationship:
In another example, a golf ball is provided that comprises a core consisting of: an inner core having an inner core diameter (DIC) of 1.10 inches-1.15 inches; and an outer core having an outer core diameter (DOC) of 1.52 inches-1.58 inches. The core can be formed from rubber and have a core hardness gradient (HGCORE) of at least +25 Shore C. A casing can surround the core, and the casing can be formed from ionomer and have a casing diameter of no greater than 1.62 inches. A cover can surround the casing, and the cover can be formed from polyurethane with an NCO content of 4.8%-5.2%. The cover can have a cover thickness (TCOVER) of 0.028 inches-0.032 inches, and the cover can be formed from a composition having a material hardness (HCM) of no greater than 62 Shore C. A soft-spin factor (S) can be defined by:
An adaptive-shot factor (A) can be defined by:
The adaptive-shot factor (A) can be less than 2,000, in one example. The adaptive-shot factor (A) can be 1,750-1,850 in one example.
A relationship between the soft-spin factor (S) and the adaptive-shot factor (A) can be defined as well. In one aspect, the soft-spin factor (S) and the adaptive-shot factor (A) can be related as shown below:
Various other aspects and features of a golf ball and its characteristics are disclosed herein.
Further features and advantages of the invention can be ascertained from the following detailed description that is provided in connection with the drawings described below:
According to some of the disclosed embodiments, a golf ball is disclosed herein which exhibits improved playability for a variety of types of shots. The golf ball exhibits desirable spin and speed performance for long shots and short shots, in one example. The golf ball comprises a unique combination of various construction parameters in order to achieve an improved playability profile. Various aspects of the golf ball construction are provided in more detail herein. Other exemplary golf ball constructions are disclosed in U.S. patent application Ser. Nos. 18/105,267 and 18/105,269, which are both commonly assigned to Acushnet Company and which both are incorporated by reference in their entirety as if fully set forth herein.
In one embodiment, golf balls made in accordance with the present disclosure have a core assemblage with a center (i.e., inner core layer) and an outer core layer disposed about the inner core layer. Additional layers may also be used in or around the core assemblage.
Each of the components of the core assemblage may be formed from a rubber formulation. In one embodiment, the rubber formulation includes a base rubber in an amount of about 5 percent to 100 percent by weight based on total weight of formulation. In one embodiment, the base rubber is included in the rubber formulation in an amount within a range having a lower limit of about 5 percent or 10 percent or 20 percent or 30 percent or 40 percent or 50 percent and an upper limit of about 55 percent or 60 percent or 70 percent or 80 percent or 90 percent or 95 percent or 100 percent. For example, the base rubber may be present in the rubber formulation in an amount of about 40 percent to about 95 percent by weight based on the total weight of the formulation. In one embodiment, the rubber formulation includes about 55 percent to about 95 percent base rubber based on the total weight of the formulation.
The base rubber may be polybutadiene, polyisoprene, ethylene propylene rubber, ethylene-propylene-diene rubber, styrene-butadiene rubber, styrenic block copolymer rubbers, polyalkenamers such as, for example, polyoctenamer, butyl rubber, halobutyl rubber, polystyrene elastomers, polyethylene elastomers, polyurethane elastomers, polyurea elastomers, metallocene-catalyzed elastomers and plastomers, copolymers of isobutylene and p-alkylstyrene, halogenated copolymers of isobutylene and p-alkylstyrene, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and blends of two or more thereof. In one embodiment, the rubber formulation includes polybutadiene rubber, butyl rubber, or a blend thereof as the base rubber.
For example, one or more of the core components may be formed from a rubber formulation that includes polybutadiene as the base rubber. Polybutadiene is a homopolymer of 1,3-butadiene. The double bonds in the 1,3-butadiene monomer are attacked by catalysts to grow the polymer chain and form a polybutadiene polymer having a desired molecular weight. Any suitable catalyst may be used to synthesize the polybutadiene rubber depending upon the desired properties. In one embodiment, a transition metal complex (for example, neodymium, nickel, or cobalt) or an alkyl metal such as alkyl lithium is used as a catalyst. Other catalysts include, but are not limited to, aluminum, boron, lithium, titanium, and combinations thereof. The catalysts produce polybutadiene rubbers having different chemical structures. In a cis-bond configuration, the main internal polymer chain of the polybutadiene appears on the same side of the carbon-carbon double bond contained in the polybutadiene. In a trans-bond configuration, the main internal polymer chain is on opposite sides of the internal carbon-carbon double bond in the polybutadiene. The polybutadiene rubber can have various combinations of cis- and trans-bond structures. For example, the polybutadiene rubber may have a 1,4 cis-bond content of at least 40 percent. In another embodiment, the polybutadiene rubber has a 1,4 cis-bond content of greater than 80 percent. In still another embodiment, the polybutadiene rubber has a 1,4 cis-bond content of greater than 90 percent. In general, polybutadiene rubbers having a high 1,4 cis-bond content have high tensile strength.
The polybutadiene rubber may have a relatively high or low Mooney viscosity. Generally, polybutadiene rubbers of higher molecular weight and higher Mooney viscosity have better resiliency than polybutadiene rubbers of lower molecular weight and lower Mooney viscosity. However, as the Mooney viscosity increases, the milling and processing of the polybutadiene rubber generally becomes more difficult. Blends of high and low Mooney viscosity polybutadiene rubbers may be prepared as is described in U.S. Pat. Nos. 6,982,301 and 6,774,187, the disclosures of which are hereby incorporated by reference, and used in accordance with this invention. In general, the lower limit of Mooney viscosity may be about 30 or 35 or 40 or 45 or 50 or 55 or 60 or 70 or 75 and the upper limit may be about 80 or 85 or 90 or 95 or 100 or 105 or 110 or 115 or 120 or 125 or 130. For example, the polybutadiene used in the rubber formulation may have a Mooney viscosity of about 40 to about 90.
Examples of commercially available polybutadiene rubbers that can be used in rubber formulations in accordance with this invention, include, but are not limited to, BR 01 and BR 1220, available from BST Elastomers of Bangkok, Thailand; SE BR 1220LA and SE BR1203, available from DOW Chemical Co of Midland, Mich.; BUDENE 1207, 1207s, 1208, and 1280 available from Goodyear, Inc of Akron, Ohio; BR 01, 51 and 730, available from Japan Synthetic Rubber (JSR) of Tokyo, Japan; BUNA CB 21, CB 22, CB 23, CB 24, CB 25, CB 29 MES, CB 60, CB Nd 60, CB 55 NF, CB 70 B, CB KA 8967, and CB 1221, available from Lanxess Corp. of Pittsburgh. Pa.; BR1208, available from LG Chemical of Seoul, South Korea; UBEPOL BR130B, BR150, BR150B, BR150L, BR230, BR360L, BR710, and VCR617, available from UBE Industries, Ltd. of Tokyo, Japan; EUROPRENE NEOCIS BR 60, INTENE 60 AF and P30AF, and EUROPRENE BR HV80, available from Polimeri Europa of Rome, Italy; AFDENE 50 and NEODENE BR40, BR45, BR50 and BR60, available from Karbochem (PTY) Ltd. of Bruma, South Africa; KBR 01, NdBr 40, NdBR-45, NdBr 60, KBR 710S, KBR 710H, and KBR 750, available from Kumho Petrochemical Co., Ltd. Of Seoul, South Korea; DIENE 55NF, 70AC, and 320 AC, available from Firestone Polymers of Akron, Ohio; and PBR-Nd Group II and Group III, available from Nizhnekamskneftekhim, Inc. of Nizhnekamsk, Tartarstan Republic.
In another embodiment, one or more of the components of the core assemblage are formed from a rubber formulation including butyl rubber. Butyl rubber is an elastomeric copolymer of isobutylene and isoprene. Butyl rubber is an amorphous, non-polar polymer with good oxidative and thermal stability, good permanent flexibility and high moisture and gas resistance. Generally, butyl rubber includes copolymers of about 70 percent to about 99.5 percent by weight of an isoolefin, which has about 4 to 7 carbon atoms, for example, isobutylene, and about 0.5 percent to about 30 percent by weight of a conjugated multiolefin, which has about 4 to 14 carbon atoms, for example, isoprene. The resulting copolymer contains about 85 percent to about 99.8 percent by weight of combined isoolefin and about 0.2 percent to about 15 percent of combined multiolefin. A commercially available butyl rubber includes Bayer Butyl 301 manufactured by Bayer AG.
In still another embodiment, the rubber formulations used to form one or more of the components of the core assemblage include a blend of polybutadiene and butyl rubber. In this embodiment, the rubber formulation may include a blend of polybutadiene and butyl rubber in a ratio of about 10:90 to about 90:10. For example, the core layer may include a blend of polybutadiene and butyl rubber in a ratio of about 30:70 to about 70:30 or about 40:60 to about 60:40. In other embodiments, the rubber formulation may include polybutadiene and/or butyl rubber in a blend with any of the other elastomers discussed above.
The rubber formulations further include a reactive cross-linking co-agent. Suitable co-agents include, but are not limited to, metal salts of unsaturated carboxylic acids having from 3 to 8 carbon atoms; unsaturated vinyl compounds and polyfunctional monomers (e.g., trimethylolpropane trimethacrylate); phenylene bismaleimide; and combinations thereof. In one embodiment, the co-agent is 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 another embodiment, the co-agent includes one or more zinc salts of acrylates, diacrylates, methacrylates, and dimethacrylates. For example, the co-agent may be zinc diacrylate (ZDA). In another embodiment, the co-agent may be zinc dimethacrylate (ZDMA).
The co-agent may be included in the rubber formulation in varying amounts depending on the specific core component for which the rubber formulation is intended. In one embodiment, the amount of co-agent used in the rubber formulations increases for each outer component of the core assemblage. In other words, the co-agent in the rubber formulation for the center is included in a first amount and the co-agent in the rubber formulation for the outer core layer is included in a second amount. The second amount may be more than the first amount. In this aspect, the first amount may be about 25 percent to about 90 percent of the second amount. For example, the first amount may be about 40 percent to about 80 percent of the second amount. In one embodiment, the first amount is about 60 percent to about 75 percent of the second amount.
For example, when the rubber formulation is intended for use in the center, the co-agent may be used in an amount of about 10 to about 30 parts by weight per 100 parts of the total rubber. In one embodiment, the rubber formulation for the center of the core assemblage includes about 15 to about 28 parts by weight co-agent per 100 parts of the total rubber. In another embodiment, the co-agent is included in the rubber formulation for the center in an amount of about 20 to about 30 parts by weight per 100 parts of the total rubber. In still another embodiment, the rubber formulation for the center of the core assemblage includes about 22 to about 30 parts by weight co-agent per 100 parts of the total rubber.
The rubber formulation for the outer core layer may include about 31 parts to about 40 parts by weight co-agent per 100 parts of the total rubber. In one embodiment, the co-agent is included in the rubber formulation for the outer core layer in an amount of about 33 parts to about 38 parts by weight per 100 parts of the total rubber. For example, the rubber formulation for the outer core layer may include about 34 parts to about 37 parts by weight co-agent per 100 parts of the total rubber.
Moreover, the co-agent in each rubber formulation may be the same or different. In particular, the co-agent used in the rubber formulation for the center may be different or the same as the co-agent used in the rubber formulation for the outer core layer. In some embodiments, the co-agent used in each of the rubber formulations for the center and outer core layer of the core assemblage is ZDA, ZDMA, or a combination thereof. For example, the rubber formulations used to form the center and outer core layer of the core assemblage may include ZDA. In this aspect, the ZDA may be used in an amount of about 21 to about 30 parts by weight per 100 parts of the total rubber for the center rubber formulation and an amount of about 31 to about 40 parts by weight per 100 parts of the total rubber in the outer core layer rubber formulation. In another embodiment, the ZDA may be used in an amount of about 25 to about 30 parts by weight per 100 parts of the total rubber in the center rubber formulation and an amount of about 35 to about 40 parts by weight per 100 parts of the total rubber in the outer core layer rubber formulation.
Radical scavengers such as a halogenated organosulfur, organic disulfide, or inorganic disulfide compounds may also be added to the rubber formulation. In one embodiment, a halogenated organosulfur compound included in the rubber formulation includes, but is not limited to, pentachlorothiophenol (PCTP) and salts of PCTP such as zinc pentachlorothiophenol (ZnPCTP). In another embodiment, ditolyl disulfide, diphenyl disulfide, dixylyl disulfide, 2-nitroresorcinol, and combinations thereof are added to the rubber formulation.
The rubber formulation may also include filler(s). Suitable non-limiting examples of fillers include carbon black, clay and nanoclay particles, talc, glass (e.g., glass flake, milled glass, and microglass), mica and mica-based pigments (e.g., Iriodin® pearl luster pigments from The Merck Group), and combinations thereof. Metal fillers are also contemplated for inclusion in the rubber formulation such as, for example, particulate, powders, flakes, and fibers of copper, steel, brass, tungsten, titanium, aluminum, magnesium, molybdenum, cobalt, nickel, iron, lead, tin, zinc, barium, bismuth, bronze, silver, gold, and platinum, and alloys and combinations thereof. The concentration of the fillers when included may be in an amount of about 1 percent to about 20 percent by weight based on total weight of rubber formulation. In one embodiment, the rubber formulation includes at least one filler in an amount of about 5 percent to about 15 percent by weight of the total weight of the rubber formulation.
Antioxidants, processing aids, accelerators (for example, tetra methylthiuram), dyes and pigments, wetting agents, surfactants, plasticizers, coloring agents, fluorescent agents, chemical blowing and foaming agents, defoaming agents, stabilizers, softening agents, impact modifiers, antiozonants, as well as other additives known in the art, may also be added to the rubber formulation. Examples of suitable processing aids include, but are not limited to, high molecular weight organic acids and salts thereof. Suitable organic acids are aliphatic organic acids, aromatic organic acids, saturated mono-functional organic acids, unsaturated monofunctional organic acids, multi-unsaturated mono-functional organic acids, and dimerized derivatives thereof. In one embodiment, the organic acids include, but are not limited to, caproic acid, caprylic acid, capric acid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylacetic acid, naphthalenoic acid, and dimerized derivatives thereof. The salts of organic acids include the salts of barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, or calcium, salts of fatty acids, particularly stearic, behenic, erucic, oleic, linoelic or dimerized derivatives thereof.
The rubber formulation may be cured using conventional curing processes. Non-limiting examples of curing processes suitable for use in accordance with the present invention include peroxide-curing, sulfur-curing, high-energy radiation, and combinations thereof. In one embodiment, the rubber formulation includes a free-radical initiator selected from organic peroxides, high energy radiation sources capable of generating free-radicals, and combinations thereof. Suitable organic peroxides include, but are not limited to, dicumyl peroxide; n-butyl-4,4-di(t-butylperoxy) valerate; 1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane; 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. In a particular embodiment, the free radical initiator is dicumyl peroxide, including, but not limited to Perkadox® BC, commercially available from Akzo Nobel. Peroxide free-radical initiators may be present in the rubber formulation in an amount of at least 0.05 parts by weight per 100 parts of the total rubber, or an amount within the range having a lower limit of 0.05 parts or 0.1 parts or 1 part or 1.25 parts or 1.5 parts or 2.5 parts or 5 parts by weight per 100 parts of the total rubbers, and an upper limit of 2.5 parts or 3 parts or 5 parts or 6 parts or 10 parts or 15 parts by weight per 100 parts of the total rubber. Concentrations are in parts per hundred (phr) unless otherwise indicated. As used herein, the term, “parts per hundred,” also known as “phr” or “pph” is defined as the number of parts by weight of a particular component present in a mixture, relative to 100 parts by weight of the polymer component. Mathematically, this can be expressed as the weight of an ingredient divided by the total weight of the polymer, multiplied by a factor of 100.
The hardness of the geometric center of the center (or center of the core assemblage) may be obtained according to the following: the center (or core assemblage) is first gently pressed into a hemispherical holder having an internal diameter approximately slightly smaller than the diameter of the center (or core assemblage), such that the center is held in place in the hemispherical portion of the holder while concurrently leaving the geometric central plane of the center exposed. The center is secured in the holder by friction, such that it will not move during the cutting and grinding steps, but the friction is not so excessive that distortion of the natural shape of the core would result. The center is secured such that the parting line of the center is roughly parallel to the top of the holder. The diameter of the center is measured 90 degrees to this orientation prior to securing. A measurement is also made from the bottom of the holder to the top of the center to provide a reference point for future calculations. A rough cut is made slightly above the exposed geometric center of the core using a band saw or other appropriate cutting tool, making sure that the center does not move in the holder during this step. The remainder of the center, still in the holder, is secured to the base plate of a surface grinding machine. The exposed “rough” surface is ground to a smooth, flat surface, revealing the geometric center of the center, which can be verified by measuring the height from the bottom of the holder to the exposed surface of the center, making sure that exactly half of the original height of the center, as measured above, has been removed to within 0.004 inches. Leaving the center in the holder, the geometric center of the center is confirmed with a center square and carefully marked and the hardness is measured at the center mark according to ASTM D-2240.
Additional hardness measurements at any distance from the geometric center of the center can then be made by drawing a line radially outward from the geometric center mark, and measuring the hardness at any given distance along the line, typically in 2 mm increments from the center. The hardness at a particular distance from the geometric center should be measured along at least two, preferably four, radial arms located 1800 apart, or 900 apart, respectively, and then averaged. All hardness measurements performed on a plane passing through the geometric center are performed while the center is still in the holder and without having disturbed its orientation, such that the test surface is constantly parallel to the bottom of the holder, and thus also parallel to the properly aligned foot of the durometer.
The outer surface hardness of a core layer (or any golf ball layer) is measured on the actual outer surface of the layer and is obtained from the average of a number of measurements taken from opposing hemispheres, taking care to avoid making measurements on the parting line of the core or on surface defects, such as holes or protrusions and preferably making the measurements prior to surrounding the layer of interest with an additional layer. Hardness measurements are made pursuant to ASTM D-2240 “Indentation Hardness of Rubber and Plastic by Means of a Durometer.” Because of the curved surface, care must be taken to ensure that the golf ball or golf ball sub-assembly is centered under the durometer indenter before a surface hardness reading is obtained. A calibrated, digital durometer, capable of reading to 0.1 hardness units is used for the hardness measurements. The digital durometer must be attached to, and its foot made parallel to, the base of an automatic stand. The weight on the durometer and attack rate conforms to ASTM D-2240. It is worthwhile to note that, once an additional layer surrounds a layer of interest, the hardness of the layer of interest can be difficult to determine. Therefore, for purposes of the present invention, when the hardness of a layer is needed after the inner layer has been surrounded with another layer, the test procedure for measuring a point located 1 mm from an interface is used.
It should also be noted that there is a fundamental difference between “material hardness” and “hardness as measured directly on a golf ball” (or, as used herein, “surface hardness”). For purposes of the present invention, material hardness is measured according to ASTM D2240 and generally involves measuring the hardness of a flat “slab” or “button” formed of the material. Surface hardness as measured directly on a golf ball (or other spherical surface) typically results in a different hardness value. The difference in “surface hardness” and “material hardness” values is due to several factors including, but not limited to, ball construction (that is, core type, number of layers, and the like); ball (or ball sub-assembly) diameter; and the material composition of adjacent layers. It also should be understood that the two measurement techniques are not linearly related and, therefore, one hardness value cannot easily be correlated to the other. Shore hardness (for example, Shore C or Shore D hardness) was measured according to the test method ASTM D-2240.
The center can have a geometric center hardness that ranges from about 55 to about 65 Shore C. In another example, the center can have a geometric center hardness that ranges from about 60 to about 70 Shore C. In one embodiment, the hardness at the geometric center is about 57 to about 63 Shore C.
The hardness at the surface of the center may range from about 70 to about 90 Shore C. In one embodiment, the hardness at the surface of the center is about 80 to about 90 Shore C. In one embodiment, the hardness at the surface of the center is about 70 to about 80 Shore C. In one embodiment, the hardness at the surface of the center is about 75 to about 85 Shore C. For example, the center may have a surface hardness of about 78 to about 82 Shore C. In one example, the center can have a surface hardness of about 80 to about 85 Shore C.
The outer core layer has a hardness at the surface that may range from about 80 to about 95 Shore C. In one embodiment, the surface hardness of the outer core layer is about 85 to about 95 Shore C. For example, the surface hardness of the outer core layer may have a hardness of about 88 to about 92 Shore C. In one example, the surface hardness of the outer core layer/core assemblage can be about 86 to about 91 Shore C.
In some embodiments, the hardness at the surface of the center may be about 75 percent to about 95 percent of the hardness at the surface of the outer core layer/core assemblage. In one embodiment, the center has a surface hardness that is about 80 percent to about 90 percent of the hardness at the surface of the outer core layer/core assemblage. In yet another embodiment, the center has a surface hardness that is about 85 percent to about 90 percent of the hardness at the surface of the outer core layer/core assemblage. In another example, the center has a surface hardness that is at least 90 percent of the hardness at the surface of the outer core layer/core assemblage.
The direction of the hardness gradient is defined by the difference in hardness measurements taken at the geometric center and outer surfaces of the center and inner and outer core layers. The geometric center hardness is readily determined according to the test procedures provided above. For example, the outer surface of the center (or outer core layer) is also readily determined according to the procedures given herein for measuring the outer surface hardness of a golf ball layer, if the measurement is made prior to surrounding the layer with an additional core layer.
While the gradient across the core assemblage will vary based on several factors including, but not limited to, the dimensions and formulations of the components, the core assemblage of the present disclosure has a “positive” hardness gradient (that is, the geometric center is softer than the surface of the outer core layer). More particularly, the term, “positive hardness gradient” as used herein means a hardness gradient of positive about 3 Shore C or greater, about 5 Shore C or greater, about 7 Shore C or greater, or about 10 Shore C or greater. In general, the hardness gradient may be determined by subtracting the hardness value of the first component being measured (for example, the outer surface of the center) from the hardness value of the second component being measured (for example, the outer surface of the outer core layer).
In some embodiments, the surface hardness of the center is less than the surface hardness of the outer core layer. In one embodiment, the positive hardness gradient from the surface of the center to the surface of the outer core layer is in the range of about 2 to about 30 Shore C units. In one embodiment, the hardness gradient of the surface of the center to the surface of the outer core layer may be about +5 to +30 Shore C. In some embodiments, the positive hardness gradient of the center to the outer core layer is about 8 to 25 Shore C. Similarly, the geometric hardness of the center is less than the surface hardness of the outer core layer. In one embodiment, the positive hardness gradient from the geometric center to the surface of the outer core layer is in the range of about 20 to about 50 Shore C units. In one embodiment, the hardness gradient of the geometric center to the surface of the outer core layer may be about +25 to +45 Shore C. In some embodiments, the positive hardness gradient of the geometric center to the outer core layer is about 30 to 40 Shore C. In one embodiment, the hardness gradient of the geometric center to the surface of the outer core layer is at least +26 Shore C.
The center itself may also have a positive hardness gradient. In one embodiment, the center has a positive hardness gradient from the geometric center to the surface of the center of about 10 to 40 Shore C. In this aspect, the positive hardness gradient of the center (from the geometric center to the surface of the center) is about 15 to about 35 Shore C. For example, the positive hardness gradient of the center is about 20 to about 28 Shore C. In one example, the center has a positive hardness gradient from the geometric center to the surface of the center of about +15 to +25 Shore C.
The center may also have a “zero” hardness gradient, i.e., the hardness values of the outer surface of the outer core layer and the geometric center are substantially the same. The term, “zero hardness gradient” as used herein means a hardness gradient of less than about 3 Shore C, preferably less than about 1 Shore C and may have a value of zero. In other embodiments, the outer core layer may have a “zero” hardness gradient within the layer itself (i.e., the hardness values of the inner surface and outer surface of the outer core layer are substantially the same). In still other embodiments, the surface of the center and the inner surface of the outer core layer may have a substantially similar hardness or the same hardness, but the surface of the center and the outer surface of the outer core layer still have hardness values that differ such that a positive hardness gradient as described above is achieved.
In some embodiments, a point or plurality of points measured along a “positive” gradients may be above or below a line fit through the gradient and its outermost and innermost hardness values. In an alternative embodiment, the hardest point along a particular steep “positive” gradient may be higher than the value at the innermost portion of the center (the geometric center) or outer core layer, as long as the outermost point (i.e., the outer surface of the center) is greater than the innermost point (i.e., the geometric center of the center), such that the “positive” gradients remain intact.
Several different methods can be used to measure compression, including Atti compression, Riehle compression, load/deflection measurements at a variety of fixed loads and offsets, and effective modulus (see, e.g., Compression by Any Other Name, Science and Golf IV, Proceedings of the World Scientific Congress of Golf (Eric Thain ed., Routledge, 2002) (J. Dalton)). For purposes of the present invention, compression values are provided as measured by the Dynamic Compression Machine (“DCM”) as well as the Soft Center Deflection Index (“SCDI”). The DCM applies a load to a ball component or a ball and measures the number of inches the core or ball is deflected at measured loads. A crude load/deflection curve is generated that is fit to the Atti compression scale that results in a number being generated that represents an Atti compression. The DCM does this via a load cell attached to the bottom of a hydraulic cylinder that is triggered pneumatically at a fixed rate (typically about 1.0 ft/s) towards a stationary core. Attached to the cylinder is an LVDT that measures the distance the cylinder travels during the testing timeframe. A software-based logarithmic algorithm ensures that measurements are not taken until at least five successive increases in load are detected during the initial phase of the test.
The SCDI is a slight variation of the DCM set up that allows determination of the pounds required to deflect a component or ball 10 percent of its diameter. With the SCDI, the goal is to obtain the pounds of force required to deflect a component or ball a certain amount of inches. That amount of deflection is 10 percent of the component or ball diameter. The DCM is triggered, the cylinder deflects the component or ball by 10 percent of its diameter, and the DCM reports back the pounds of force required (as measured from the attached load cell) to deflect the component or ball by that amount. The SCDI value obtained is a single number in units of pounds.
In some embodiments, the center has a compression of less than 70 DCM. For example, the center compression may be about 30 to about 70 DCM. In one embodiment, the center compression may range from about 40 to about 60 DCM. In still another embodiment, the center compression is about 45 to about 55 DCM. In yet another embodiment, the center has a compression of about 48 to about 52 DCM. The SCDI compression of the center may range from about 120 to about 160 SCDI. In one embodiment, the center has a compression of about 130 SCDI to about 150 SCDI. In another embodiment, the compression of the inner core is about 135 to about 145 SCDI. In another embodiment, the compression of the inner core is no greater than 120 SCDI. In another embodiment, the compression of the inner core is no greater than 125 SCDI.
The core assemblage (i.e., the center with an outer core layer disposed thereon) may have a compression that ranges from about 65 to about 105 DCM. In one embodiment, the core assemblage has a compression of about 75 to about 95 DCM. In another embodiment, the core assemblage has a compression of about 80 to about 90 DCM. Similarly, the core assemblage compression may range from about 200 to about 240 SCDI. In on embodiment, the core assemblage has a compression of about 210 SCDI to about 230 SCDI. In another embodiment, the compression of the core assemblage is about 215 to about 225 SCDI. In one example, the core assemblage can have a compression of 85 DCM-90 DCM.
In some embodiments, the compression of the center may be about 25 percent to about 65 percent of the core assemblage. For example, the compression of the center may be about 50 percent to about 80 percent of the core assemblage compression. In another example, the compression of the center may be about 60 percent to about 75 percent of the core assemblage. In still another example, the compression of the center may be about 60 percent to about 70 percent of the core assemblage. In another embodiment, the compression of the center may be about 25 percent to about 70 percent of the compression of the core assemblage. For example, the compression of the center may be about 30 percent to about 50 percent of the compression of the core assemblage. In another example, the compression of the center may be about 35 percent to 45 percent of the compression of the core assemblage.
The direction of the compression gradient is defined by the difference in compression measurements of the center and core assemblage. While the gradient across the core assemblage (and from component to component) will vary based on several factors including, but not limited to, the dimensions and formulations of the components, the core assemblage of the present disclosure has a “positive” compression gradient (that is, the center has a lower compression than the core assemblage). More particularly, the term, “positive compression gradient” as used herein means a compression gradient of positive about 5 DCM or greater, about 10 DCM or greater, about 20 DCM or greater, or about 30 DCM or greater or about 10 SCDI or greater, about 20 SCDI or greater, about 30 SCDI or greater, or about 40 SCDI or greater. In general, the compression gradient may be determined by subtracting the compression of the first component being measured (for example, the center) from the compression of the second component being measured (for example, the core assemblage).
In some embodiments, the compression of the center is less than the compression of the core assemblage. In one embodiment, the positive compression gradient from the center to the core assemblage is in the range of about 5 to 75 DCM and/or 40 to 120 SCDI. For example, the compression gradient of the center to core assemblage may be about +25 to about +60 DCM and/or about +50 to about +110 SCDI. In another embodiment, the compression gradient of the center to core assemblage can be about +30 to about +45 DCM and/or about +70 to about +90 SCDI. In another example, the compression gradient of the center to core assemblage can be about +45 to about +55 DCM.
The diameter of the components of the core assemblage may vary, but the core assemblage diameter is larger than the diameter of the center. In one embodiment, the diameter of the center is between about 50 percent and 90 percent of the diameter of the core assemblage. For example, the center diameter may range from about 55 percent and 85 percent of the diameter of the core assemblage. In another embodiment, the diameter of the center is between about 60 percent and 80 percent of the diameter of the core assemblage. In still another embodiment, the diameter of the center is between about 70 percent and 85 percent of the diameter of the core assemblage. In still another embodiment, the diameter of the center is between about 70 percent-80 percent of the diameter of the core assemblage. In still another embodiment, the diameter of the center is between about 70 percent-75 percent of the diameter of the core assemblage.
In some embodiments, the center diameter may range from about 1.13 inches to about 1.30 inches. In one embodiment, the center diameter may range from about 1.20 inches to about 1.30 inches. In another embodiment, the center diameter may range from about 1.22 inches to about 1.28 inches. The core assemblage diameter may range from about 1.50 inches to about 1.60 inches. In one embodiment, the core assemblage has a diameter of about 1.52 inches to about 1.58 inches. In another embodiment, the core assemblage diameter ranges from about 1.54 inches to about 1.56 inches. In one specific example, the diameter of the inner core or center is 1.13 inches (+/−0.02 inches), and the diameter of the core assemblage is 1.55 inches (+/−0.02 inches).
As discussed above, a core assemblage 10 including a center 20 (i.e., inner core) and outer core layer 30 is formed in accordance with this disclosure, which is shown in
Referring to
Golf balls made in accordance with this disclosure can be of any size, although the USGA requires that golf balls used in competition have a diameter of at least 1.68 inches. For play outside of United States Golf Association (USGA) rules, the golf balls can be of a smaller size. In one embodiment, golf balls made in accordance with this invention have a diameter in the range of about 1.68 to about 1.80 inches.
In contrast to the core, the cover of a golf ball plays less of a role on shots off of a driver. However, because the cover plays a large role in generating spin on iron and wedge shots, the cover material and properties are important. In this aspect, different materials may be used in the construction of the intermediate and cover layers of golf balls according to the present disclosure. For example, a variety of materials may be used for forming the outer cover including, for example, polyurethanes; polyureas; copolymers, blends and hybrids of polyurethane and polyurea; olefin-based copolymer ionomer resins; polyethylene, including, for example, low density polyethylene, linear low density polyethylene, and high density polyethylene; polypropylene; rubber-toughened olefin polymers; acid copolymers, for example, poly(meth)acrylic acid, which do not become part of an ionomeric copolymer; plastomers; flexomers; styrene/butadiene/styrene block copolymers; styrene/ethylene-butylene/styrene block copolymers; dynamically vulcanized elastomers; copolymers of ethylene and vinyl acetates; copolymers of ethylene and methyl acrylates; polyvinyl chloride resins; polyamides, poly(amide-ester) elastomers, and graft copolymers of ionomer and; cross-linked trans-polyisoprene and blends thereof; polyester-based thermoplastic elastomers; polyurethane-based thermoplastic elastomers; synthetic or natural vulcanized rubber; and combinations thereof.
In one embodiment, the outer cover is formed from a polyurethane, polyurea, or hybrid of polyurethane-polyurea. When used as cover layer materials, polyurethanes and polyureas can be thermoset or thermoplastic. Thermoset materials can be formed into golf ball layers by conventional casting or reaction injection molding techniques. Thermoplastic materials can be formed into golf ball layers by conventional compression or injection molding techniques.
In one embodiment, the cover is formed from a polyurethane, polyurea, or hybrid of polyurethane-polyurea. When used as cover layer materials, polyurethanes and polyureas can be thermoset or thermoplastic. Thermoset materials can be formed into golf ball layers by conventional casting or reaction injection molding techniques. Thermoplastic materials can be formed into golf ball layers by conventional compression or injection molding techniques.
Exemplary thermoset materials for the outer cover layer (and any other layer so treated) include, but are not limited to: (1) thermoset polyurethanes, such as those prepared from polyols and diisocyanates or polyisocyanates and/or their prepolymers, and those disclosed in U.S. Pat. Nos. 5,334,673 and 6,506,851 (both of which are fully incorporated by reference as if fully set forth herein); (2) thermoset polyureas, such as those disclosed in U.S. Pat. Nos. 5,484,870 and 6,835,794 (both of which are fully incorporated by reference as if fully set forth herein); and (3) thermoset polyurethane-urea hybrids, blends or copolymers comprising urethane and urea segments.
Suitable polyurethane compositions comprise a reaction product of at least one polyisocyanate and at least one curing agent. The curing agent can include, for example, one or more polyamines, one or more polyols, or a combination thereof. The polyisocyanate can be combined with one or more polyols to form a prepolymer, which is then combined with the at least one curing agent. Thus, the polyols described herein are suitable for use in one or both components of the polyurethane material, i.e., as part of a prepolymer and in the curing agent. Suitable polyurethanes are described in U.S. Patent Application Publication No. 2005/0176523, which is fully incorporated by reference as if fully set forth herein.
Any polyisocyanate available to one of ordinary skill in the art is suitable for use according to the present disclosure. Exemplary polyisocyanates include, but are not limited to, 4,4′-diphenylmethane diisocyanate (MDI); polymeric MDI; carbodiimide-modified liquid MDI; 4,4′-dicyclohexylmethane diisocyanate (H12MDI); p-phenylene diisocyanate (PPDI); m-phenylene diisocyanate (MPDI); toluene diisocyanate (TDI); 3,3′-dimethyl-4,4′-biphenylene diisocyanate; isophoronediisocyanate; 1,6-hexamethylene diisocyanate (HDI); naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene diisocyanate; m-tetramethylxylene diisocyanate; ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate; dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methyl cyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of 2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate; napthalene diisocyanate; anthracene diisocyanate; isocyanurate of toluene diisocyanate; uretdione of hexamethylene diisocyanate; and mixtures thereof. Polyisocyanates are known to those of ordinary skill in the art as having more than one isocyanate group, e.g., di-isocyanate, tri-isocyanate, and tetra-isocyanate. Preferably, the polyisocyanate includes MDI, PPDI, TDI, or a mixture thereof, and more preferably, the polyisocyanate includes MDI. It should be understood that, as used herein, the term MDI includes 4,4′-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modified liquid MDI, and mixtures thereof and, additionally, that the diisocyanate employed may be “low free monomer,” understood by one of ordinary skill in the art to have lower levels of “free” monomer isocyanate groups, typically less than about 0.1% free monomer isocyanate groups. Examples of “low free monomer” diisocyanates include, but are not limited to Low Free Monomer MDI, Low Free Monomer TDI, and Low Free Monomer PPDI.
The at least one polyisocyanate can have less than about 14% unreacted NCO groups, or less than 9% unreacted NCO groups, or less than 8.5% unreacted NCO groups, or less than 8% unreacted NCO groups, or less than 7.5% unreacted NCO groups, or less than 7% unreacted NCO groups, or less than 6.5% unreacted NCO groups, or less than 6% unreacted NCO groups, or less than 5.5% unreacted NCO groups, or less than 5% unreacted NCO groups. In one example, the at least one polyisocyanate has no greater than about 8.0% NCO, or no greater than about 7.5% NCO, or no greater than about 7.0% NCO, or no greater than 6.5% NCO or 6.0% NCO or 5.5% NCO or 5.0% NCO. In one example, the at least one polyisocyanate has 6.5% NCO. In another example, the at least one polyisocyanate has 5.0% NCO. In another example, the at least one polyisocyanate has 4.8%-5.2% NCO.
Conventional and non-conventional materials may be used for forming intermediate layers of the ball including, for instance, ionomer resins, highly neutralized polymers, polybutadiene, butyl rubber, and other rubber-based core formulations, and the like. In one embodiment, the inner core layer, i.e., the layer disposed between the core assemblage and the outer cover, includes an ionomer. In this aspect, ionomers suitable for use in accordance with the present disclosure may include partially-neutralized ionomers and highly-neutralized ionomers (HNPs), including ionomers formed from blends of two or more partially-neutralized ionomers, blends of two or more highly-neutralized ionomers, and blends of one or more partially-neutralized ionomers with one or more highly-neutralized ionomers. For purposes of the present disclosure, “HNP” refers to an acid copolymer after at least 70 percent of all acid groups present in the composition are neutralized.
Preferred ionomers are salts of O/X- and O/X/Y-type acid copolymers, wherein O is an α-olefin, X is a C3-C5 α,β-ethylenically unsaturated carboxylic acid, and Y is a softening monomer. O is preferably selected from ethylene and propylene. X is preferably selected from methacrylic acid, acrylic acid, ethacrylic acid, crotonic acid, and itaconic acid. Methacrylic acid and acrylic acid are particularly preferred. Y is preferably selected from (meth) acrylate and alkyl (meth) acrylates wherein the alkyl groups have from 1 to 8 carbon atoms, including, but not limited to, n-butyl (meth) acrylate, isobutyl (meth) acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate.
Preferred O/X and O/X/Y-type copolymers include, without limitation, ethylene acid copolymers, such as ethylene/(meth)acrylic acid, ethylene/(meth)acrylic acid/maleic anhydride, ethylene/(meth)acrylic acid/maleic acid mono-ester, ethylene/maleic acid, ethylene/maleic acid mono-ester, ethylene/(meth)acrylic acid/n-butyl (meth)acrylate, ethylene/(meth)acrylic acid/isobutyl (meth)acrylate, ethylene/(meth)acrylic acid/methyl (meth)acrylate, ethylene/(meth)acrylic acid/ethyl (meth)acrylate terpolymers, and the like. The term, “copolymer,” as used herein, includes polymers having two types of monomers, those having three types of monomers, and those having more than three types of monomers. Preferred α, B-ethylenically unsaturated mono-or dicarboxylic acids are (meth) acrylic acid, ethacrylic acid, maleic acid, crotonic acid, fumaric acid, itaconic acid. (Meth) acrylic acid is most preferred. As used herein, “(meth) acrylic acid” means methacrylic acid and/or acrylic acid. Likewise, “(meth) acrylate” means methacrylate and/or acrylate.
In a particularly preferred version, highly neutralized E/X- and E/X/Y-type acid copolymers, wherein E is ethylene, X is a C3-C5 α,β-ethylenically unsaturated carboxylic acid, and Y is a softening monomer are used. X is preferably selected from methacrylic acid, acrylic acid, ethacrylic acid, crotonic acid, and itaconic acid. Methacrylic acid and acrylic acid are particularly preferred. Y is preferably an acrylate selected from alkyl acrylates and aryl acrylates and preferably selected from (meth) acrylate and alkyl (meth) acrylates wherein the alkyl groups have from 1 to 8 carbon atoms, including, but not limited to, n-butyl (meth) acrylate, isobutyl (meth) acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate. Preferred E/X/Y-type copolymers are those wherein X is (meth) acrylic acid and/or Y is selected from (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate. More preferred E/X/Y-type copolymers are ethylene/(meth) acrylic acid/n-butyl acrylate, ethylene/(meth) acrylic acid/methyl acrylate, and ethylene/(meth) acrylic acid/ethyl acrylate.
The amount of ethylene in the acid copolymer may be at least about 15 weight percent, at least about 25 weight percent, at least about 40 weight percent, or at least about 60 weight percent, based on total weight of the copolymer. The amount of C3 to C8 α,β-ethylenically unsaturated mono- or dicarboxylic acid in the acid copolymer is typically from 1 weight percent to 35 weight percent, from 5 weight percent to 30 weight percent, from 5 weight percent to 25 weight percent, or from 10 weight percent to 20 weight percent, based on total weight of the copolymer. The amount of optional softening comonomer in the acid copolymer may be from 0 weight percent to 50 weight percent, from 5 weight percent to 40 weight percent, from 10 weight percent to 35 weight percent, or from 20 weight percent to 30 weight percent, based on total weight of the copolymer.
The various O/X, E/X, O/X/Y, and E/X/Y-type copolymers are at least partially neutralized with a cation source, optionally in the presence of a high molecular weight organic acid, such as those disclosed in U.S. Pat. No. 6,756,436, the entire disclosure of which is hereby incorporated herein by reference. The acid copolymer can be reacted with the optional high molecular weight organic acid and the cation source simultaneously, or prior to the addition of the cation source. Suitable cation sources include, but are not limited to, metal ion sources, such as compounds of alkali metals, alkaline earth metals, transition metals, and rare earth elements; ammonium salts and monoamine salts; and combinations thereof. Preferred cation sources are compounds of magnesium, sodium, potassium, cesium, calcium, barium, manganese, copper, zinc, lead, tin, aluminum, nickel, chromium, lithium, and rare earth metals. The amount of cation used in the composition is readily determined based on desired level of neutralization. As discussed above, for HNP compositions, the acid groups are neutralized to 70 percent or greater, 70 to 100 percent, or 90 to 100 percent. In one embodiment, an excess amount of neutralizing agent, that is, an amount greater than the stoichiometric amount needed to neutralize the acid groups, may be used. That is, the acid groups may be neutralized to 100 percent or greater, for example 110 percent or 120 percent or greater. In other embodiments, partially-neutralized compositions are prepared, wherein 10 percent or greater, normally 30 percent or greater of the acid groups are neutralized. When aluminum is used as the cation source, it is preferably used at low levels with another cation such as zinc, sodium, or lithium, since aluminum has a dramatic effect on melt flow reduction and cannot be used alone at high levels. For example, aluminum is used to neutralize about 10 percent of the acid groups and sodium is added to neutralize an additional 90 percent of the acid groups.
“Low acid” and “high acid” ionomeric polymers, as well as blends of such ionomers, may be used. In general, low acid ionomers are considered to be those containing 16 weight percent or less of acid moieties, whereas high acid ionomers are considered to be those containing greater than 16 weight percent of acid moieties. In one embodiment, the inner cover layer is formed from a composition comprising a high acid ionomer. A suitable high acid ionomer is Surlyn® 8150 (DuPont), which is a copolymer of ethylene and methacrylic acid, having an acid content of 19 weight percent, 45 percent neutralized with sodium. In another embodiment, the inner cover layer is formed from a composition comprising a high acid ionomer and a maleic anhydride-grafted non-ionomeric polymer. An example of a suitable maleic anhydride-grafted polymer is Fusabond® 525D (DuPont), which is a maleic anhydride-grafted, metallocene-catalyzed ethylene-butene copolymer having about 0.9 weight percent maleic anhydride grafted onto the copolymer. Blends of high acid ionomers with maleic anhydride-grafted polymers are further disclosed, for example, in U.S. Pat. Nos. 6,992,135 and 6,677,401, the entire disclosures of which are each hereby incorporated herein by reference.
The inner cover layer also may be formed from a composition comprising a 50/45/5 blend of Surlyn® 8940/Surlyn® 9650/Nucrel® 960. In this aspect, the composition may have a material hardness of from 80 to 85 Shore C. In another embodiment, the inner cover layer is formed from a composition comprising a 50/25/25 blend of Surlyn® 8940/Surlyn® 9650/Surlyn® 9910, having a material hardness of about 85 to 95 Shore C. In yet another embodiment, the inner cover layer is formed from a composition comprising a 50/50 blend of Surlyn® 8940/Surlyn® 9650, having a material hardness of about 82 to 90 Shore C. A composition comprising a 50/50 blend of Surlyn® 8940 and Surlyn® 7940 also may be used. In yet another aspect, a composition comprising a blend of Surlyn® 8150 and Surlyn® 9120 can also be used. The blend of Surlyn® 8150 and Surlyn® 9120 can be 50/50 in one example.
The compositions used to make the layers outside of the core assemblage, e.g., the inner cover and outer cover layers, may contain a variety of fillers and additives to impart specific properties to the ball. For example, relatively heavy-weight and light-weight metal fillers such as, particulate; powders; flakes; and fibers of copper, steel, brass, tungsten, titanium, aluminum, magnesium, molybdenum, cobalt, nickel, iron, lead, tin, zinc, barium, bismuth, bronze, silver, gold, and platinum, and alloys and combinations thereof may be used to adjust the specific gravity of the ball. Other additives and fillers include, but are not limited to, optical brighteners, coloring agents, fluorescent agents, whitening agents, UV absorbers, light stabilizers, surfactants, processing aids, antioxidants, stabilizers, softening agents, fragrance components, plasticizers, impact modifiers, titanium dioxide, clay, mica, talc, glass flakes, milled glass, and mixtures thereof.
The outer cover layer preferably has a material hardness of 85 Shore C or less. In one aspect, the outer cover layer has a surface hardness of 80 Shore C, and a material hardness of no greater than 65 Shore C. In one aspect the material hardness for the composition of the outer cover layer is 62 Shore C. In one aspect the material hardness for the composition of the outer cover layer is no greater than 63 Shore C. In one aspect the surface hardness of the outer cover layer is no greater than 82 Shore C. The thickness of the outer cover layer is preferably within a range having a lower limit of 0.010 or 0.015 or 0.025 inches and an upper limit of 0.035 or 0.040 or 0.055 or 0.080 inches. In one aspect, the thickness of the outer cover layer is at least 0.030 inches. In one aspect, the thickness of the outer cover layer is no greater than 0.030 inches.
Methods for measuring hardness of the layers in the golf ball are described in further detail herein. When included, the inner cover layer preferably has a material hardness within a range having a lower limit of 70 or 75 or 80 or 82 Shore C and an upper limit of 85 or 86 or 90 or 92 Shore C. The hardness of the inner cover layer or casing on the golf ball (i.e., surface hardness of the casing) can be about 68 Shore D to 72 Shore D.
The thickness of the intermediate layer is preferably within a range having a lower limit of 0.010 or 0.015 or 0.020 or 0.030 inches and an upper limit of 0.035 or 0.045 or 0.080 or 0.120 inches. In one aspect, the thickness of the casing or intermediate layer is 0.035 inches.
In one embodiment, the golf balls made in accordance with the present disclosure include a core assemblage as described herein, an inner cover layer formed from an ionomeric material, and the outer cover layer is formed from a polyurethane material, and the outer cover layer has a hardness that is less than that of the inner cover layer. For example, the inner cover layer may have a hardness of greater than about 60 Shore D and the outer cover layer may have a hardness of less than about 60 Shore D. In an alternative embodiment, the inner cover layer is comprised of a partially or fully neutralized ionomer, a thermoplastic polyester elastomer, a thermoplastic polyether block amide, or a thermoplastic or thermosetting polyurethane or polyurea, and the outer cover layer is comprised of an ionomeric material. In this alternative embodiment, the inner cover layer may have a hardness of less than about 60 Shore D and the outer cover layer may have a hardness of greater than about 55 Shore D and the inner cover layer hardness is less than the outer cover layer hardness. In one aspect, a material hardness of the casing layer can be greater than 65 Shore D, and a material hardness of the cover layer can be less than 45 Shore D.
When a dual cover is disposed about the core assemblage, the inner cover layer may have a thickness of about 0.01 inches to about 0.06 inches, about 0.015 inches to about 0.040 inches, or about 0.02 inches to about 0.035 inches. The outer cover layer may have a thickness of about 0.015 inches to about 0.055 inches, about 0.02 inches to about 0.04 inches, or about 0.025 inches to about 0.035 inches. In one aspect, the inner cover layer (i.e., casing or intermediate layer) has a thickness of 0.035 inches, and the outer cover layer has a thickness of 0.030 inches.
In one aspect, a thickness differential between a thickness of the cover (i.e., cover thickness) and a thickness of the casing (i.e., casing thickness (TCASING)) is no greater than 0.010 inches. In one aspect, a thickness differential between the cover thickness and the casing thickness is no greater than 0.005 inches.
The golf balls of the present disclosure may be formed using a variety of application techniques. For example, the golf ball layers may be formed using compression molding, flip molding, injection molding, retractable pin injection molding, reaction injection molding (RIM), liquid injection molding (LIM), casting, vacuum forming, powder coating, flow coating, spin coating, dipping, spraying, and the like. Conventionally, compression molding and injection molding are applied to thermoplastic materials, whereas RIM, liquid injection molding, and casting are employed on thermoset materials. In this aspect, cover layers may be formed over the core assemblage using any suitable technique that is associated with the material used to form the layer. Preferably, each cover layer is separately formed over the core assemblage. For example, an ethylene acid copolymer ionomer composition may be injection-molded to produce half-shells over the core assemblage. Alternatively, the ionomer composition can be placed into a compression mold and molded under sufficient pressure, temperature, and time to produce the hemispherical shells, which may then be placed around the core assemblage in a compression mold. An outer cover layer including a polyurethane or polyurea composition over the ball sub-assembly may be formed by using a casting process.
Golf balls made in accordance with the present disclosure may be subjected to finishing steps such as flash-trimming, surface-treatment, marking, coating, and the like using techniques known in the art. In one embodiment, a white-pigmented cover may be surface-treated using a suitable method such as, for example, corona, plasma, or ultraviolet (UV) light-treatment. Indicia such as trademarks, symbols, logos, letters, and the like may be printed on the cover using pad-printing, ink-jet printing, dye-sublimation, or other suitable printing methods. Clear surface coatings (for example, primer and top-coats), which may contain a fluorescent whitening agent, may be applied to the cover. Golf balls may also be painted with one or more paint coatings in a variety of colors. In one embodiment, white primer paint is applied first to the surface of the ball and then a white top-coat of paint may be applied over the primer.
Golf ball spin rate is the amount of spin on the golf ball once the ball is hit and separates from the clubface of the golf club. Spin rate can be measured by RPM (revolutions per minute). As described above, the golf balls of the present disclosure achieve a reduction in the driver spin rate and maintain a relatively high spin rate when compared to a “conventional golf ball.” For the purposes of this disclosure, the “conventional golf ball” used for comparison purposes includes a four-piece golf ball with a dual polybutadiene core, an ionomer inner cover layer or casing, and a polyurethane outer cover. Modifications with respect to each component or layer of the golf ball in terms of materials, dimensions, compositions, etc., have been implemented relative to the golf ball of the present disclosure as compared to the conventional golf ball. These modifications have resulted in a reduction of the spin rate of the golf ball when hit with a driver while also providing the desired short game performance associated with multi-layer golf balls.
In one example, if the average spin rate of a conventional golf ball off of a full wedge is about 9,950 RPM, then the spin rate of the golf balls of the present disclosure are about 150 RPM to about 200 RPM more, i.e., about 10,100 RPM to about 10,150 RPM (all other factors held constant). In one embodiment, the spin rate of the golf balls of the present disclosure are about 125 RPM to about 175 RPM more than the spin rate of a conventional golf ball off of a full wedge (all other factors held constant). In yet another embodiment, the spin rate of the golf balls of the present disclosure are about 100 RPM to about 225 RPM more than the spin rate of a conventional golf ball off of a full wedge (all other factors held constant).
In one example, if the average spin rate of a conventional golf ball off of a half wedge is about 7,175 RPM, then the spin rate of the golf balls of the present disclosure are about 150 RPM to about 200 RPM more, i.e., about 7,325 RPM to about 7,375 RPM (all other factors held constant). In one embodiment, the spin rate of the golf balls of the present disclosure are about 125 RPM to about 175 RPM more than the spin rate of a conventional golf ball off of a half wedge (all other factors held constant). In yet another embodiment, the spin rate of the golf balls of the present disclosure are about 100 RPM to about 225 RPM more than the spin rate of a conventional golf ball off of a half wedge (all other factors held constant).
In one example, a first spin rate differential for the present golf ball and a conventional golf ball was determined. The first spin rate differential was evaluated based on a difference in the spin rates for a half wedge and a driver, and also a difference in the spin rates for a half wedge and a 5 iron. A greater first spin rate differential indicates a greater playability factor. Golf balls according to the present disclosure have a greater first spin rate differential between half wedges and drivers, and half wedges and 5 irons as compared to conventional golf balls.
A second spin rate differential was evaluated between a difference in the spin rates for an 8 iron and a half wedge, and a difference in the spin rates for a full wedge and half wedge. A lower value for the second spin rate differentials indicates less excessive spin for the lofted iron conditions. Golf balls according to the present disclosure exemplified a relatively low second spin rate differential as compared to conventional golf balls using this testing methodology.
In one example, the golf ball disclosed herein is a four-piece golf ball (i.e., golf ball 40 in
The core can have a core hardness gradient (HGCORE) (in Shore C). This specific core hardness gradient is a difference between the surface hardness of the outer core minus the hardness of the geometric center of the inner core. In one example, the core hardness gradient (HGCORE) is at least +25 Shore C. In another example, the core hardness gradient (HGCORE) is at least +26 Shore C. One of ordinary skill in the art would understand that the core hardness gradient (HGCORE) can vary. The specific golf ball constructions disclosed herein have a relatively high positive core hardness gradient.
The cover can have a cover thickness (TCOVER) (in inches), and the cover is formed from a composition having a material hardness (HCM) (in Shore C). In one aspect, the cover thickness (TCOVER) is at least 0.028 inches. In one aspect, the cover thickness (TCOVER) is at least 0.030 inches. In one aspect, the material hardness (HCM) of the cover composition is less than 65 Shore C. In one aspect, the material hardness (HCM) of the cover composition is no greater than 65 Shore C.
A soft-spin factor (S) is defined by:
A ratio of the hardness of the cover material to the cover thickness (HCM:TCOVER) can be less than 2,100. In one example, the ratio of the hardness of the cover material to cover thickness (HCM:TCOVER) can be 2,000-2,100. In one example, the ratio of the hardness of the cover material to cover thickness (HCM:TCOVER) can be at least 1,800. In one example, the ratio of the hardness of the cover material to cover thickness (HCM:TCOVER) can be no greater than 2,300. The cover thickness (TCOVER) can be 0.028 inches-0.032 inches. The cover thickness (TCOVER) can be 0.030 inches in one example. In one aspect, the present disclosure provides a relatively thicker and softer cover as compared to conventional golf balls. In one aspect, this specific arrangement provides for increased spin rates on shorter shots.
The material hardness of the cover composition (HCM) can be 60 Shore C-64 Shore C. In one example, the material hardness of the cover composition (HCM) can be 62 Shore C. In one example, the material hardness of the cover composition (HCM) can be no greater than 62 Shore C. In one example, the material hardness of the cover composition (HCM) can be no greater than 64 Shore C. The core hardness gradient (HGCORE) can be at least +25 Shore C. In one specific example, the core hardness gradient (HGCORE) can be at least +26 Shore C.
A compression of the core can be 80 DCM-90 DCM. A specific gravity of the core can be 1.15-1.16.
A ratio of the inner core diameter (DIC) to an outer core diameter (DOC) can be 0.700-0.800. In another example, the ratio of the inner core diameter (DIC) to the outer core diameter (DOC) is 0.700-0.750. In another example, the ratio of the inner core diameter (DIC) to the outer core diameter (DOC) is 0.725-0.735. In another example, the ratio of the inner core diameter (DIC) to the outer core diameter (DOC) is 0.729. In one example, the inner core diameter (DIC) can be at least 1.10 inches. In one example, the inner core diameter (DIC) can be at least 1.13 inches.
The ratio of the inner core diameter to the outer core diameter (DIC:DOC), and the soft-spin factor (S) can have the following relationship: 800≤DIC:DOC×S≤950. In one aspect, 850≤DIC:DOC×S≤875.
The golf ball can have a hardness (HB), and the golf ball hardness (HB) can be no greater than 82 Shore C. In one example, the golf ball hardness (HB) can be no greater than 80 Shore C.
The golf ball can have a compression (CB) (in DCM), and the soft-spin factor (S) and the golf ball compression (CB) can have the following relationship:
The ratio of the golf ball compression (CB) to the soft-spin factor (S) can be 11.4-11.8. In another example, the ratio of the golf ball compression (CB) to the soft-spin factor (S) can be 11.6 (+/−0.1).
The cover can be formed from polyurethane with an NCO content of no greater than 5.0%. In one example, the cover can be formed from polyurethane with an NCO content of no greater than 5.2%. In another example, the cover can be formed from polyurethane with an NCO content of 4.8%-5.2%.
In another aspect, a golf ball is provided that comprises a core consisting of: an inner core having an inner core diameter (DIC) of 1.10 inches-1.15 inches; and an outer core having an outer core diameter (DOC) of 1.52 inches-1.58 inches. The core can be formed from rubber and have a core hardness gradient (HGCORE) of at least +25 Shore C. A casing can surround the core, and the casing can be formed from ionomer and have a casing diameter of no greater than 1.62 inches. A cover can surround the casing, and the cover can be formed from polyurethane with an NCO content of 4.8%-5.2%. The cover can have a cover thickness (TCOVER) of 0.028 inches-0.032 inches, and the cover can be formed from a composition having a material hardness (HCM) of no greater than 62 Shore C. A soft-spin factor (S) can be defined by:
The adaptive-shot factor (A) can be used as another design optimization characteristic that further accounts for golf ball parameters that influence a golfer's ability to hit the golf ball with a wide spectrum of golf clubs, including long shots and short shots. The adaptive-shot factor (A) can be configured to account for thickness of the cover, the hardness gradient of the core, and also the overall hardness of the golf ball. The adaptive-shot factor (A) can be less than 2,000, in one example. The adaptive-shot factor (A) can be less than 1,900, in one example. In yet another example, the adaptive-shot factor (A) can be 1,750-1,850. In a specific example, the adaptive-shot factor (A) can be 1,800.
A relationship between the soft-spin factor (S) and the adaptive-shot factor (A) can be provided as well. In one aspect, the soft-spin factor (S) and the adaptive-shot factor (A) can be related as shown below:
In one aspect, the soft-spin factor (S) and the adaptive-shot factor (A) can be related as shown below:
In one aspect, the ratio of the adaptive-shot factor (A) to the soft-spin factor (S) can be 2,500-3,500. In one aspect, the ratio of the adaptive-shot factor (A) to the soft-spin factor (S) can be 2,975-3,000. In yet another aspect, the ratio of the adaptive-shot factor (A) to the soft-spin factor (S) can be 2,980-2,990.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art of this disclosure. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well known functions or constructions may not be described in detail for brevity or clarity.
The terms “about” and “approximately” shall generally mean an acceptable degree of error or variation for the quantity measured given the nature or precision of the measurements. Numerical quantities given in this description are approximate unless stated otherwise, meaning that the term “about” or “approximately” can be inferred when not expressly stated.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well (i.e., at least one of whatever the article modifies), unless the context clearly indicates otherwise.
The terms “first,” “second,” and the like are used to describe various features or elements, but these features or elements should not be limited by these terms. These terms are only used to distinguish one feature or element from another feature or element. Thus, a first feature or element discussed below could be termed a second feature or element, and similarly, a second feature or element discussed below could be termed a first feature or element without departing from the teachings of the disclosure. Likewise, terms like “top” and “bottom”; “front” and “back”; and “left” and “right” are used to distinguish certain features or elements from each other, but it is expressly contemplated that a top could be a bottom, and vice versa.
The golf balls described and claimed herein are not to be limited in scope by the specific embodiments herein disclosed, since these embodiments are intended as illustrations of several aspects of the disclosure. Any equivalent embodiments are intended to be within the scope of this disclosure. Indeed, various modifications of the device in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. All patents and patent applications cited in the foregoing text are expressly incorporated herein by reference in their entirety. Any section headings herein are provided only for consistency with the suggestions of 37 C.F.R. § 1.77 or otherwise to provide organizational queues. These headings shall not limit or characterize the invention(s) set forth herein.
