Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-10-03
2002-11-05
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S072000, C525S193000, C525S221000, C473S355000, C473S365000, C473S373000, C473S374000, C473S377000, C473S378000, C473S385000
Reexamination Certificate
active
06476130
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to golf ball compositions that contain non-ionic polymers produced using single-site catalysts. The polymers derived using such catalysts have narrow molecular weight distributions and uniform molecular architecture. As a result of these characteristics, golf balls comprising such polymers have improved performance characteristics, such as improved distance and better control on the green.
BACKGROUND OF THE INVENTION
Three-piece, wound golf balls with balata covers are preferred by most expert golfers. These balls provide a combination of distance, high spin rate, and control that is not available with other types of golf balls. However, balata is easily damaged in normal play, and, thus, lacks the durability required by the average golfer.
In contrast, amateur golfers typically prefer a solid, two-piece ball with an ionomer cover, which provides a combination of distance and durability. Because of the hard ionomer cover, these balls are almost impossible to cut. They also have a very hard “feel”, however, which many golfers find unacceptable, and a lower spin rate, making these balls more difficult to draw or fade. The reduction in the spin rate can be attributed to the differences between three-piece, wound golf balls and solid, two-piece balls in the composition and construction of both the cover and the core.
Many attempts have been made to produce a golf ball with the control and feel of a wound balata ball and the durability of a solid, two-piece ball, but none have succeeded totally. For example, U.S. Pat. No. 4,274,637 to Molitor discloses two- and three-piece golf balls having covers completely or partially formed from a cellular polymeric material to improve backspin, but does not provide any examples that compare the spin rates of the disclosed golf balls with those of prior art balls.
U.S. Pat. No. 5,002,281 to Nakahara et al. discloses a three-piece solid golf ball having an ionomer cover and a solid core consisting of a soft inner core and a hard outer shell, where the difference in the hardness of the two parts of the core is at least 10 on the JIS-C scale.
Similarly, U.S. Pat. No. 4,781,383 discloses a solid, three-piece golf ball, having an ionomer cover and a core with inner and outer layers, where the inner layer has a diameter of 24 to 29 mm and a Shore D hardness of 15 to 30, and the outer layer has a diameter of 36 to 41 and a Shore D hardness of 55 to 65. The percentage of the ball surface which contacts the club face when the ball is struck is 27 to 35%.
European Patent Application 0 633 043 discloses a solid, three-piece golf ball with an ionomer or balata cover, a center core, and an intermediate layer. The center core has a diameter of at least 29 mm and a specific gravity of less than 1.4. The intermediate layer has a thickness of at least 1 mm, a specific gravity of less than 1.2, and a hardness of at least 85 on the JIS-C scale.
U.S. Pat. Nos. 5,703,166 and 5,824,746 to Rajagopalan et al. and Harris et al. disclose golf balls incorporating blends of ionomers and non-ionic polyolefin polymers produced by metallocene catalysts. Metallocene catalysts are transition metal complexes that have substituted or unsubstituted cyclopentadienyl groups serving as ligands. The polymers produced using metallocene catalysts have a narrow molecular weight distribution, and a uniform molecular architecture, such that the order and orientation of the monomers in the polymer, and the amount and type of branching is essentially the same in each polymer chain. However, metallocene catalysts technology is limited to the production of non-polar polymers. Single-site catalysts other than metallocenes, such as those disclosed herein, can produce both polar and non-polar polymers with unique properties, which will have a dramatic influence in golf ball performance.
A number of single-site catalysts other than metallocenes are known. Recent articles have disclosed several non-metallocene single-site catalysts. The Apr. 13, 1998 issue of Chemical and Engineering News describes a method a producing complexes of iron (II) and cobalt (II) with 2,6 bis-(imino)pyridyl ligands. These single-site catalysts reportedly produce polymers with narrow molecular weight distributions, and a uniform molecular architecture.
Similarly, Brookhart et al., at the Sixth International Business Forum on Specialty Polyolefins, September, 1996, reported a class of nickel (II) and palladium (II) complexes which serve as active catalysts for the polymerization of ethylene and &agr;-olefins. These complexes feature a substituted &agr;-diimine ligand. Brookhart reports that by varying, among other things, the catalyst structure the degree and type of polymer branching can be controlled.
Cribbs et al., Antec, 1998, S.P.E., discloses several single-site catalysts other than metallocene. These include diimide complexes of nickel and palladium, and complexes of 1,4,7-triazacyclononane with rhodium, chromium, and scandium. Cribbs also discloses a process for forming non-metallocene single-site catalysts that consists of deprotonating pyroles or indoles to form a monoanion, and then reacting the monoanion with TiCl
4
or ZrCl
4
to form the single-site catalysts. This catalyst, when co-catalyzed with a sizable excess of methylalumoxane, has been found to polymerize ethylene to narrow molecular weight distribution polyethylene. Cribbs also discloses boratabenzene complexes of the Group 4 or 5 metals, and reports that these complexes show good activity in ethylene polymerization and that the molecular weights of the product can be varied by changing the substituents on the boron atom.
In the December 1997 issue of Chemtech, Montagna discloses several examples of non-metallocene single-site catalysts, including the Brookhart catalyst and the McConville catalyst, which is a zirconium complex stabilized by diamide ligands.
International patent application PCT WO96/23010 discloses several additional single-site catalysts. These include transition metal complexes, typically nickel or palladium complexes, having an &agr;-diimine ligand.
However, although single-site catalysts are known, there is no known prior art disclosure of golf balls that incorporate compositions comprising polymers produced by such single-site catalysts, other than those produced using metallocene catalysts. Therefore, there is no appreciation in the prior art of the unique advantages obtained with golf balls produced with these materials.
While a variety of blend combinations of one species of polymer, such as ionomers, have been successfully used to make golf balls in the prior art, the prior art does not disclose successful blends of different types of polymers, such as ionomers and balata or other non-ionic polymers for use in golf ball covers. In general, prior art blends of such polymer components are immiscible, i.e., heterogeneous on a microscopic scale, and incompatible, i.e., heterogeneous on a macroscopic scale, unless strong interactions are present between the polymer components in the mixture, such as those observed between ionomers and polymers containing carboxylic acid groups. In particular, this lack of compatibility exists when an ionomer is blended with a polyolefin homopolymer, copolymer, or terpolymer that does not contain ionic, acidic, basic, or other polar pendant groups, and is not produced with a single-site catalyst. These mixtures often have poor tensile strength, impact strength, and the like. Hence, the golf balls produced from these incompatible mixtures will have inferior golf ball properties such as poor durability, cut resistance, and so on. In contrast, a compatible blend may be heterogeneous on a microscopic scale, but homogeneous on a macroscopic scale, and, thus, have useful golf ball properties.
In this regard, U.S. Pat. No. 5,397,840 to Sullivan discloses golf ball covers including a blend of “ionic copolymers” and “non-ionic copolymers”. However, the “ionic copolymers” are defined as copolymers of an &agr;-olefin and a metal salt of an &agr;,&bgr;-unsa
Harris Kevin M.
Rajagopalan Murali
Acushnet Company
Buttner David J.
Swidler Berlin Shereff & Friedman, LLP
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