US 20070270238 A1
A method for selecting the spin characteristics of a fluid filled golf ball and a golf ball incorporating these properties is disclosed herein. One aspect is a method for optimizing the spin and flight characteristics of a fluid containing golf ball which selects an internal fluid material having a viscosity that matches the cover hardness of the golf ball as to obtain the desired spin and flight characteristics of the golf ball.
1. A golf ball comprising:
a core having a shell layer defining an interior chamber, the interior chamber containing a fluid material therein, the fluid material having a viscosity lower than 50 centapoise;
a cover disposed over the core, the cover having a Shore D hardness ranging from 40 to 60;
wherein the golf ball has a spin greater than 2800 rotations per minute when struck with a wedge golf club at a swing speed of 88 miles per hour, and a spin greater than 3200 rotations per minute when struck with a wedge golf club at a swing speed of 105 miles per hour.
2. The golf ball according to
3. The golf ball according to
4. The golf ball according to
5. A golf ball comprising:
a cover defining an interior chamber, the interior chamber containing a fluid material therein, the fluid material having a viscosity lower than 50 centapoise, the cover having a Shore D hardness ranging from 40 to 60;
wherein the golf ball has a spin greater than 2800 rotations per minute when struck with a wedge golf club at a swing speed of 88 miles per hour, and a spin greater than 3200 rotations per minute when struck with a wedge golf club at a swing speed of 105 miles per hour.
6. The golf ball according to
7. The golf ball according to
8. The golf ball according to
9. The golf according to
10. A method for optimizing the spin and flight characteristics of a fluid containing golf ball, the method comprising:
selecting a desired spin and flight characteristic for a golf ball;
selecting a cover hardness for a golf ball; and
selecting an internal fluid material with a viscosity that matches the cover hardness of the golf ball as to obtain the desired spin and flight characteristics of the golf ball.
The present application claims priority to U.S. Provisional Patent Application No. 60/747,756, filed on May 19, 2006.
1. Field of the Invention
The present invention relates to a golf ball. More specifically, the present invention relates to a golf ball having a fluid core and a soft cover, and a method of matching a viscosity of a fluid core with a hardness of a cover material to enhance the spin characteristics of the golf ball.
2. Description of the Related Art
Spin rate is an important golf ball characteristic for both the skilled and unskilled golfer. High spin rates allow for the more skilled golfer, such as PGA professionals and low handicap players, to maximize control of the golf ball. This is particularly beneficial to the more skilled golfer when hitting an approach shot to a green. The ability to intentionally produce “back spin”, thereby stopping the ball quickly on the green, and/or “side spin” to draw or fade the ball, substantially improves the golfer's control over the ball. Thus, the more skilled golfer generally prefers a golf ball exhibiting high spin rate properties.
The prior art has disclosed the use of fluids in cores for golf balls.
Saunders, U.S. Pat. No. 1,080,592 discloses golf balls with cores consisting of rubber bags filled with water or some other liquid.
Gammeter, U.S. Pat. No. 1,167,396, discloses a method for making a golf ball by injecting a fluid into a core.
Schupphaus, U.S. Pat. No. 1,298,410, discloses a golf ball with a liquid or jelly like substance consisting of a solution of lead salt of an alky-sulfuric acid.
Brown, U.S. Pat. No. 2,259,060 discloses a liquid core filler composed of glue, glycerine and water.
Sullivan, U.S. Pat. No. 5,368,304 describes a low spin golf ball in which the spin rate is reduced by using the combination of a soft core and a hard outer cover. In addition, that patent suggests that spin rate can be further reduced by decreasing the weight of a softened polybutadiene core while maintaining core size and by increasing the thickness of the cover. The golf ball in the '304 patent may also be made larger than the standard 1.680 inch golf ball to provide a further reduced spin rate. While these designs are successful in reducing the spin rate of golf balls, many golfers object to a golf ball which has a very hard feel such as occurs when using a very hard cover on a golf ball. When struck with an iron club, such golf balls tend to induce vibrations into the club which are undesirable even to the unskilled golfer.
Boehm, et al., U.S. Pat. No. 5,683,312, for a Fluid Or Liquid Filled Non-Wound Golf Ball discloses a golf ball with a fluid filled center having a specific gravity and viscosity to effect the performance properties of the golf ball such as spin rate, spin decay, compression and initial velocity. The '312 Patent defines 100 centapoise as the demarcation line for high viscosity and low viscosity fluids.
Sullivan et al., U.S. Pat. No. 6,193,618, discloses a golf ball with a liquid filled core to reduce the spin rate of the golf ball.
Viscosity can be measured in different unit systems. The SI unit is N s/m2 which is known as the poiseuille (PI). An older unit, the poise (dyne s/cm2) remains in common use (where 10 poise=N s/m2 and 100 centipoise=1 poise) (1 Pa s or Pascal second is also used). The basic unit of absolute viscosity is the poise. The common unit for expressing absolute viscosity is the “centipoise” ( 1/100 of a poise). Water at 68.4° F. (20.2° C.) has an absolute viscosity of one centipoise. The faster the fluid/liquid flows, the lower the viscosity. If the fluid/liquid has a high viscosity it strongly resists flow, so the fluid/liquid flows slowly. If the fluid/liquid has a low viscosity, it offers less resistance to flow, so the fluid/liquid flows faster.
The prior art has failed to disclose the matching of a core's fluid viscosity and a cover hardness to enhance the spin characteristics of a golf ball.
The present inventors have addressed the need for developing a golf ball having an increased spin rate after impact with a golf club, while at the same time maintaining durability, playability and resiliency characteristics needed for repeated use. The increased spin rate golf ball of the present invention meets the rules and regulations established by the United States Golf Association (U.S.G.A.).
One aspect of the present invention is a method of matching the fluid viscosity of a fluid core of a golf ball to a cover hardness of the golf ball to enhance the spin characteristics of the golf ball.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
As shown in
As noted, the preferred embodiment golf ball may include a liquid core. In one variant, the liquid filled core disclosed in U.S. Pat. Nos. 5,480,155 and 5,150,906, both herein incorporated by reference, is suitable. Suitable liquids for use in the present invention golf balls include, but are not limited to, water, alcohol, oil, combinations of these, solutions such as glycol and water, or salt and water. Other suitable liquids include oils or colloidal suspensions, such as clay, barytes, or carbon black in water or other liquid. A preferred liquid core material is a solution of inorganic salt in water. The inorganic salt is preferably calcium chloride. The preferred glycol is glycerine. All of the liquids noted in the previously-mentioned, '155 and '906 patents are suitable. The density of the liquid can be adjusted to achieve the desired final weight of the golf ball.
The most preferred technique for forming a ball having a liquid core is to form a thin, hollow polymeric sphere by blow molding or forming two half shells and then joining the two half shells together. The hollow sphere is then filled with a suitable liquid and sealed. These techniques are described in the '155 and '906 patents.
A wide array of polymeric materials can be utilized to form the thin hollow sphere or shell 35. Thermoplastic materials are generally preferred for use as materials for the shell. Typically, such materials should exhibit good flowability, moderate stiffness, high abrasion resistance, high tear strength, high resilience, and good mold release, among others.
Synthetic polymeric materials which may be used for the thin hollow sphere include homopolymeric and copolymer materials which may include: (1) Vinyl resins formed by the polymerization of vinyl chloride, or by the copolymerization of vinyl chloride with vinyl acetate, acrylic esters or vinylidene chloride; (2) Polyolefins such as polyethylene, polypropylene, polybutylene, and copolymers such as polyethylene methylacrylate, polyethylene ethylacrylate, polyethylene vinyl acetate, polyethylene methacrylic or polyethylene acrylic acid or polypropylene acrylic acid or terpolymers made from these and acrylate esters and their metal ionomers, polypropylene/EPDM grafted with acrylic acid or anhydride modified polyolefins; (3) Polyurethanes, such as are prepared from polyols and diisocyanates or polyisocyanates; (4) Polyamides such as poly(hexamethylene adipamide) and others prepared from diamines and dibasic acids, as well as those from amino acid such as poly(caprolactam), and blends of polyamides with SURLYN, polyethylene, ethylene copolymers, EDPA, etc; (5) Acrylic resins and blends of these resins with polyvinyl chloride, elastomers, etc.; (6) Thermoplastic rubbers such as the urethanes, olefinic thermoplastic rubbers such as blends of polyolefins with EPDM, block copolymers of styrene and butadiene, or isoprene or ethylene-butylene rubber, polyether block amides; (7) Polyphenylene oxide resins, or blends of polyphenylene oxide with high impact polystyrene; (8) Thermoplastic polyesters, such as PET, PBT, PETG, and elastomers sold under the trademark HYTREL by E. I. DuPont De Nemours & Company of Wilmington, Del.; (9) Blends and alloys including polycarbonate with ABS, PBT, PET, SMA, PE elastomers, etc. and PVC with ABS or EVA or other elastomers; and (10) Blends of thermoplastic rubbers with polyethylene, polypropylene, polyacetal, nylon, polyesters, cellulose esters, etc.
The fluid cavity or center can be filled with a wide variety of materials including air, water solutions, gels, foams, hot-melts, other fluid materials and combinations thereof. The fluid or liquid material 80 can be varied to modify the performance parameters of the ball, such as the moment of inertia. Preferably, the fluid or liquid material 80 is comprised of a material that has a high specific gravity for high spin rate golf balls and a material that has a low specific gravity for a low spin rate golf ball. Preferably, the specific gravity of the fluid or liquid is below or equal to 1.2 for low specific gravity centers and above 1.2 for high specific gravity centers. More preferably, the specific gravity is approximately 1.15-1.2 for low specific gravity centers and approximately 1.3-1.55 for high specific gravity centers. Still further, the fluid is preferably comprised of a material with a low viscosity for a golf ball having a high spin rate and a material having a high viscosity for a golf ball having a low spin rate. Preferably, the viscosity of the fluid or liquid center is less than 100 cps for low viscosity centers and greater than or equal to 100 cps for high viscosity centers. More preferably, the viscosity of the fluid or liquid center is less than or equal to 10 cps for low viscosity centers and is between 100 and 1500 cps for high viscosity centers. Most preferably, the fluid or liquid center viscosity is approximately 500 cps for high viscosity centers.
Examples of suitable liquids include either solutions such as salt in water, corn syrup, salt in water and corn syrup, glycol and water or oils. The liquid can further include pastes, colloidal suspensions, such as clay, barytes, carbon black in water or other liquid, or salt in water/glycol mixtures. Examples of suitable gels include water gelatin gels, hydrogels, water/methyl cellulose gels and gels comprised of copolymer rubber based materials such a styrene-butadiene-styrene rubber and paraffinic and/or naphthenic oil. Examples of suitable melts include waxes and hot melts. Hot-melts are materials which at or about normal room temperatures are solid but at elevated temperatures become liquid. A high melting temperature is desirable since the liquid core is heated to high temperatures during the molding of the second mantle layer and the cover.
The liquid material 80 may be a reactive liquid system which combine to form a solid. Examples of suitable reactive liquids are silicate gels, agar gels, peroxide cured polyester resins, two part epoxy resin systems and peroxide cured liquid polybutadiene rubber compositions. It is understood by one skilled in the art that other reactive liquid systems can likewise be utilized depending on the physical properties of the mantle layer and the physical properties desired in the resulting finished golf balls.
The core 30 is preferably 60 to 95% of the total ball weight and more preferably, 75 to 86% of the ball weight. As stated above, the weight distribution within the core 30 can be varied to achieve certain desired parameters such as spin rate, compression and initial velocity.
For example, by increasing the diameter of the fluid or liquid filled interior chamber 50, and increasing the specific gravity of any mantle layer 40, the weight distribution of the core is moved toward the outer diameter for a lower spin rate ball. In contrast, the diameter of the fluid or liquid filled interior chamber 50 can be decreased and the specific gravity of the mantle layer 40 decreased to move the weight distribution of the ball towards the ball center for a high spin rate ball.
Similarly, the specific gravity of the fluid or liquid filled center can be decreased and the specific gravity of the mantle layer 40 increased for a low spin rate ball. Alternatively, the specific gravity of the fluid or liquid filled interior chamber 50 can be increased and the specific gravity of the mantle layer 40 decrease for a high spin rate ball.
In a preferred embodiment, the cover 25 is composed of a RIM polyurethane material such as disclosed in U.S. Pat. No., which pertinent parts are hereby incorporated by reference. In an alternative embodiment, the golf ball 20 is constructed with a cover 25 composed of a polyurethane material as set forth in U.S. Pat. No. 6,117,024, for a Golf Ball With A Polyurethane Cover, which pertinent parts are hereby incorporated by reference. The golf ball 20 preferably has a coefficient of restitution at 143 feet per second greater than 0.7964, and an USGA initial velocity less than 255.0 feet per second. The golf ball 20 more preferably has a COR of approximately 0.8152 at 143 feet per second, and an initial velocity between 250 feet per second to 255 feet per second under USGA initial velocity conditions. A more thorough description of a high COR golf ball is disclosed in U.S. Pat. No. 6,443,858, which pertinent parts are hereby incorporated by reference.
The cover 25 of the golf ball 20 may be any suitable material. A preferred cover for a three-piece golf ball is composed of a thermoset polyurethane material. Alternatively, the cover 25 is composed of a thermoplastic polyurethane, ionomer blend, ionomer rubber blend, ionomer and thermoplastic polyurethane blend, or like materials. Those skilled in the pertinent art will recognize that other cover materials may be utilized without departing from the scope and spirit of the present invention. The golf ball 20 may have a finish of one or two basecoats and/or one or two top coats.
In an alternative embodiment of a golf ball 20, the mantle layer 40 or cover layer 25 is comprised of a high acid (i.e. greater than 16 weight percent acid) ionomer resin or high acid ionomer blend. More preferably, the mantle layer 40 is comprised of a blend of two or more high acid (i.e. greater than 16 weight percent acid) ionomer resins neutralized to various extents by different metal cations.
In an alternative embodiment of a golf ball 20, the mantle layer 40 or cover layer 25 is comprised of a low acid (i.e. 16 weight percent acid or less) ionomer resin or low acid ionomer blend. Preferably, the mantle layer 40 is comprised of a blend of two or more low acid (i.e. 16 weight percent acid or less) ionomer resins neutralized to various extents by different metal cations. The mantle layer 40 compositions of the embodiments described herein may include the high acid ionomers such as those developed by E. I. DuPont de Nemours & Company under the SURLYN brand, and by Exxon Corporation under the ESCOR or IOTEK brands, or blends thereof. Examples of compositions which may be used as the mantle layer 28 herein are set forth in detail in U.S. Pat. No. 5,688,869, which is incorporated herein by reference. Of course, the mantle layer 40 high acid ionomer compositions are not limited in any way to those compositions set forth in said patent. Those compositions are incorporated herein by way of examples only.
The high acid ionomers which may be suitable for use in formulating the mantle layer 28 compositions are ionic copolymers which are the metal (such as sodium, zinc, magnesium, etc.) salts of the reaction product of an olefin having from about 2 to 8 carbon atoms and an unsaturated monocarboxylic acid having from about 3 to 8 carbon atoms. Preferably, the ionomeric resins are copolymers of ethylene and either acrylic or methacrylic acid. In some circumstances, an additional comonomer such as an acrylate ester (for example, iso- or n-butylacrylate, etc.) can also be included to produce a softer terpolymer. The carboxylic acid groups of the copolymer are partially neutralized (for example, approximately 10-100%, preferably 30-70%) by the metal ions. Each of the high acid ionomer resins which may be included in the inner layer cover compositions of the invention contains greater than 16% by weight of a carboxylic acid, preferably from about 17% to about 25% by weight of a carboxylic acid, more preferably from about 18.5% to about 21.5% by weight of a carboxylic acid. Examples of the high acid methacrylic acid based ionomers found suitable for use in accordance with this invention include, but are not limited to, SURLYN 8220 and 8240 (both formerly known as forms of SURLYN AD-8422), SURLYN 9220 (zinc cation), SURLYN SEP-503-1 (zinc cation), and SURLYN SEP-503-2 (magnesium cation). According to DuPont, all of these ionomers contain from about 18.5 to about 21.5% by weight methacrylic acid. Examples of the high acid acrylic acid based ionomers suitable for use in the present invention also include, but are not limited to, the high acid ethylene acrylic acid ionomers produced by Exxon such as Ex 1001, 1002, 959, 960, 989, 990, 1003, 1004, 993, and 994. In this regard, ESCOR or IOTEK 959 is a sodium ion neutralized ethylene-acrylic neutralized ethylene-acrylic acid copolymer. According to Exxon, IOTEKS 959 and 960 contain from about 19.0 to about 21.0% by weight acrylic acid with approximately 30 to about 70 percent of the acid groups neutralized with sodium and zinc ions, respectively.
Furthermore, as a result of the previous development by the assignee of this application of a number of high acid ionomers neutralized to various extents by several different types of metal cations, such as by manganese, lithium, potassium, calcium and nickel cations, several high acid ionomers and/or high acid ionomer blends besides sodium, zinc and magnesium high acid ionomers or ionomer blends are also available for golf ball cover production. It has been found that these additional cation neutralized high acid ionomer blends produce mantle layer 40 compositions exhibiting enhanced hardness and resilience due to synergies which occur during processing. Consequently, these metal cation neutralized high acid ionomer resins can be blended to produce substantially higher C.O.R.'s than those produced by the low acid ionomer mantle layer 40 compositions presently commercially available.
The mantle layer 40 compositions may include the low acid ionomers such as those developed and sold by E. I. DuPont de Nemours & Company under the SURLYN and by Exxon Corporation under the brands ESCOR and IOTEK, ionomers made in-situ, or blends thereof.
Another embodiment of the mantle layer 40 comprises a non-ionomeric thermoplastic material or thermoset material. Suitable non-ionomeric materials include, but are not limited to, metallocene catalyzed polyolefins or polyamides, polyamide/ionomer blends, polyphenylene ether/ionomer blends, etc., which preferably have a Shore D hardness of at least 60 (or a Shore C hardness of at least about 90) and a flex modulus of greater than about 30,000 psi, preferably greater than about 50,000 psi, or other hardness and flex modulus values which are comparable to the properties of the ionomers described above. Other suitable materials include but are not limited to, thermoplastic or thermosetting polyurethanes, thermoplastic block polyesters, for example, a polyester elastomer such as that marketed by DuPont under the brand HYTREL, or thermoplastic block polyamides, for example, a polyether amide such as that marketed by Elf Atochem S. A. under the brand PEBEX, a blend of two or more non-ionomeric thermoplastic elastomers, or a blend of one or more ionomers and one or more non-ionomeric thermoplastic elastomers. These materials can be blended with the ionomers described above in order to reduce cost relative to the use of higher quantities of ionomer.
Additional materials suitable for use in the mantle layer 40 or cover layer 25 of the present invention include polyurethanes. These are described in more detail below.
In one embodiment, the cover layer 25 is comprised of a relatively soft, low flex modulus (about 500 psi to about 50,000 psi, preferably about 1,000 psi to about 25,000 psi, and more preferably about 5,000 psi to about 20,000 psi) material or blend of materials. Preferably, the cover layer 25 comprises a polyurethane, a polyurea, a blend of two or more polyurethanes/polyureas, or a blend of one or more ionomers or one or more non-ionomeric thermoplastic materials with a polyurethane/polyurea, preferably a thermoplastic polyurethane or reaction injection molded polyurethane/polyurea (described in more detail below).
The cover layer 25 preferably has a thickness in the range of 0.005 inch to about 0.15 inch, more preferably about 0.010 inch to about 0.050 inch, and most preferably 0.015 inch to 0.025 inch. In one embodiment, the cover layer 24 has a Shore D hardness of 60 or less (or less than 90 Shore C), and more preferably 55 or less (or about 80 Shore C or less). In another preferred embodiment, the cover layer 25 is comparatively harder than the mantle layer 40.
In one preferred embodiment, the cover layer 25 comprises a polyurethane, a polyurea or a blend of polyurethanes/polyureas. Polyurethanes are polymers which are used to form a broad range of products. They are generally formed by mixing two primary ingredients during processing. For the most commonly used polyurethanes, the two primary ingredients are a polyisocyanate (for example, 4,4′-diphenylmethane diisocyanate monomer (“MDI”) and toluene diisocyanate (“TDI”) and their derivatives) and a polyol (for example, a polyester polyol or a polyether polyol).
A wide range of combinations of polyisocyanates and polyols, as well as other ingredients, are available. Furthermore, the end-use properties of polyurethanes can be controlled by the type of polyurethane utilized, such as whether the material is thermoset (cross linked molecular structure not flowable with heat) or thermoplastic (linear molecular structure flowable with heat).
Cross linking occurs between the isocyanate groups (—NCO) and the polyol's hydroxyl end-groups (—OH). Cross linking will also occur between the NH2 group of the amines and the NCO groups of the isocyanates, forming a polyurea. Additionally, the end-use characteristics of polyurethanes can also be controlled by different types of reactive chemicals and processing parameters. For example, catalysts are utilized to control polymerization rates. Depending upon the processing method, reaction rates can be very quick (as in the case for some reaction injection molding systems (“RIM”)) or may be on the order of several hours or longer (as in several coating systems such as a cast system). Consequently, a great variety of polyurethanes are suitable for different end-uses.
Polyurethanes are typically classified as thermosetting or thermoplastic. A polyurethane becomes irreversibly “set” when a polyurethane prepolymer is cross linked with a polyfunctional curing agent, such as a polyamine or a polyol. The prepolymer typically is made from polyether or polyester. A prepolymer is typically an isocyanate terminated polymer that is produced by reacting an isocyanate with a moiety that has active hydrogen groups, such as a polyester and/or polyether polyol. The reactive moiety is a hydroxyl group. Diisocyanate polyethers are preferred because of their water resistance.
The physical properties of thermoset polyurethanes are controlled substantially by the degree of cross linking and by the hard and soft segment content. Tightly cross linked polyurethanes are fairly rigid and strong. A lower amount of cross linking results in materials that are flexible and resilient. Thermoplastic polyurethanes have some cross linking, but primarily by physical means, such as hydrogen bonding. The crosslinking bonds can be reversibly broken by increasing temperature, such as during molding or extrusion. In this regard, thermoplastic polyurethanes can be injection molded, and extruded as sheet and blow film. They can be used up to about 400 degrees Fahrenheit, and are available in a wide range of hardnesses.
Polyurethane materials suitable for the present invention may be formed by the reaction of a polyisocyanate, a polyol, and optionally one or more chain extenders. The polyol component includes any suitable polyether- or polyester polyol. Additionally, in an alternative embodiment, the polyol component is polybutadiene diol. The chain extenders include, but are not limited to, diols, triols and amine extenders. Any suitable polyisocyanate may be used to form a polyurethane according to the present invention. The polyisocyanate is preferably selected from the group of diisocyanates including, but not limited to, 4,4′-diphenylmethane diisocyanate (“MDI”); 2,4-toluene diisocyanate (“TDI”); m-xylylene diisocyanate (“XDI”); methylene bis-(4-cyclohexyl isocyanate) (“HMDI”); hexamethylene diisocyanate (“HDI”); naphthalene-1,5,-diisocyanate (“NDI”); 3,3′-dimethyl-4,4′-biphenyl diisocyanate (“TODI”); 1,4-diisocyanate benzene (“PPDI”); phenylene-1,4-diisocyanate; and 2,2,4- or 2,4,4-trimethyl hexamethylene diisocyanate (“TMDI”).
Other less preferred diisocyanates include, but are not limited to, isophorone diisocyanate (“IPDI”); 1,4-cyclohexyl diisocyanate (“CHDI”); diphenylether-4,4′-diisocyanate; p,p′-diphenyl diisocyanate; lysine diisocyanate (“LDI”); 1,3-bis(isocyanato methyl)cyclohexane; and polymethylene polyphenyl isocyanate (“PMDI”).
One additional polyurethane component which can be used in the present invention incorporates TMXDI (“META”) aliphatic isocyanate (Cytec Industries, West Paterson, N.J.). Polyurethanes based on meta-tetramethylxylylene diisocyanate (TMXDI) can provide improved gloss retention UV light stability, thermal stability, and hydrolytic stability. Additionally, TMXDI (“META”) aliphatic isocyanate has demonstrated favorable toxicological properties. Furthermore, because it has a low viscosity, it is usable with a wider range of diols (to polyurethane) and diamines (to polyureas). If TMXDI is used, it typically, but not necessarily, is added as a direct replacement for some or all of the other aliphatic isocyanates in accordance with the suggestions of the supplier. Because of slow reactivity of TMXDI, it may be useful or necessary to use catalysts to have practical demolding times. Hardness, tensile strength and elongation can be adjusted by adding further materials in accordance with the supplier's instructions.
The cover layer 25 preferably comprises a polyurethane with a Shore D hardness (plaque) of from about 10 to about 55 (Shore C of about 15 to about 75), more preferably from about 25 to about 55 (Shore C of about 40 to about 75), and most preferably from about 30 to about 55 (Shore C of about 45 to about 75) for a soft cover layer 25 and from about 20 to about 90, preferably about 30 to about 80, and more preferably about 40 to about 70 for a hard cover layer 25.
The polyurethane preferably has a flex modulus from about 1 to about 310 Kpsi, more preferably from about 3 to about 100 Kpsi, and most preferably from about 3 to about 40 Kpsi for a soft cover layer 25 and 40 to 90 Kpsi for a hard cover layer 25.
Non-limiting examples of a polyurethane suitable for use in mantle layer 40 include a thermoplastic polyester polyurethane such as Bayer Corporation's TEXIN polyester polyurethane (such as TEXIN DP7-1097 and TEXIN 285 grades) and a polyester polyurethane such as B. F. Goodrich Company's ESTANE polyester polyurethane (such as ESTANE X-4517 grade). The thermoplastic polyurethane material may be blended with a soft ionomer or other non-ionomer. For example, polyamides blend well with soft ionomer.
Other soft, relatively low modulus non-ionomeric thermoplastic or thermoset polyurethanes may also be utilized, as long as the non-ionomeric materials produce the playability and durability characteristics desired without adversely affecting the enhanced travel distance characteristic produced by the high acid ionomer resin composition. These include, but are not limited to thermoplastic polyurethanes such as the PELLETHANE thermoplastic polyurethanes from Dow Chemical Co.; and non-ionomeric thermoset polyurethanes including but not limited to those disclosed in U.S. Pat. No. 5,334,673, which is hereby incorporated by reference.
Typically, there are two classes of thermoplastic polyurethane materials: aliphatic polyurethanes and aromatic polyurethanes. The aliphatic materials are produced from a polyol or polyols and aliphatic isocyanates, such as H12MDI or HDI, and the aromatic materials are produced from a polyol or polyols and aromatic isocyanates, such as MDI or TDI. The thermoplastic polyurethanes may also be produced from a blend of both aliphatic and aromatic materials, such as a blend of HDI and TDI with a polyol or polyols.
Generally, the aliphatic thermoplastic polyurethanes are lightfast, meaning that they do not yellow appreciably upon exposure to ultraviolet light. Conversely, aromatic thermoplastic polyurethanes tend to yellow upon exposure to ultraviolet light. One method of stopping the yellowing of the aromatic materials is to paint the outer surface of the finished ball with a coating containing a pigment, such as titanium dioxide, so that the ultraviolet light is prevented from reaching the surface of the ball. Another method is to add UV absorbers, optical brighteners and stabilizers to the clear coating(s) on the outer cover, as well as to the thermoplastic polyurethane material itself. By adding UV absorbers and stabilizers to the thermoplastic polyurethane and the coating(s), aromatic polyurethanes can be effectively used in the outer cover layer of golf balls. This is advantageous because aromatic polyurethanes typically have better scuff resistance characteristics than aliphatic polyurethanes, and the aromatic polyurethanes typically cost less than the aliphatic polyurethanes.
Other suitable polyurethane materials for use in the present invention golf balls include reaction injection molded (“RIM”) polyurethanes. RIM is a process by which highly reactive liquids are injected into a mold, mixed usually by impingement and/or mechanical mixing in an in-line device such as a “peanut mixer,” where they polymerize primarily in the mold to form a coherent, one-piece molded article. The RIM process usually involves a rapid reaction between one or more reactive components such as a polyether polyol or polyester polyol, polyamine, or other material with an active hydrogen, and one or more isocyanate-containing constituents, often in the presence of a catalyst. The constituents are stored in separate tanks prior to molding and may be first mixed in a mix head upstream of a mold and then injected into the mold. The liquid streams are metered in the desired weight to weight ratio and fed into an impingement mix head, with mixing occurring under high pressure, for example, 1,500 to 3,000 psi. The liquid streams impinge upon each other in the mixing chamber of the mix head and the mixture is injected into the mold. One of the liquid streams typically contains a catalyst for the reaction. The constituents react rapidly after mixing to gel and form polyurethane polymers. Polyureas, epoxies, and various unsaturated polyesters also can be molded by RIM. Further descriptions of suitable RIM systems is disclosed in U.S. Pat. No. 6,663,508, which pertinent parts are hereby incorporated by reference.
Non-limiting examples of suitable RIM systems for use in the present invention are BAYFLEX elastomeric polyurethane RIM systems, BAYDUR GS solid polyurethane RIM systems, PRISM solid polyurethane RIM systems, all from Bayer Corp. (Pittsburgh, Pa.), SPECTRIM reaction moldable polyurethane and polyurea systems from Dow Chemical USA (Midland, Mich.), including SPECTRIM MM 373-A (isocyanate) and 373-B (polyol), and ELASTOLIT SR systems from BASF (Parsippany, N.J.). Preferred RIM systems include BAYFLEX MP-10000, BAYFLEX MP-7500 and BAYFLEX 110-50, filled and unfilled. Further preferred examples are polyols, polyamines and isocyanates formed by processes for recycling polyurethanes and polyureas. Additionally, these various systems may be modified by incorporating a butadiene component in the diol agent.
Another preferred embodiment is a golf ball in which at least one of the mantle layer 40 and/or the cover layer 25 comprises a fast-chemical-reaction-produced component. This component comprises at least one material selected from the group consisting of polyurethane, polyurea, polyurethane ionomer, epoxy, and unsaturated polyesters, and preferably comprises polyurethane, polyurea or a blend comprising polyurethanes and/or polymers. A particularly preferred form of the invention is a golf ball with a cover comprising polyurethane or a polyurethane blend.
The polyol component typically contains additives, such as stabilizers, flow modifiers, catalysts, combustion modifiers, blowing agents, fillers, pigments, optical brighteners, and release agents to modify physical characteristics of the cover. Polyurethane/polyurea constituent molecules that were derived from recycled polyurethane can be added in the polyol component.
The surface geometry of the golf ball 20 is preferably a conventional dimple pattern such as disclosed in U.S. Pat. No. 6,213,898 for a Golf Ball With An Aerodynamic Surface On A Polyurethane Cover, which pertinent parts are hereby incorporated by reference. Alternatively, the surface geometry of the golf ball 20 may have a non-dimple pattern such as disclosed in U.S. Pat. No. 6,290,615 for A Golf Ball Having Tubular Lattice Pattern, which pertinent parts are hereby incorporated by reference.
From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.