Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2002-08-27
2004-12-28
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S053000, C528S056000, C528S058000, C528S061000, C528S065000, C528S076000, C473S374000, C473S377000, C473S378000
Reexamination Certificate
active
06835794
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to golf equipment including polyurea compositions. In particular, the present invention is directed to golf equipment including compositions formed from a polyurea prepolymer of polyether amine and isocyanate crosslinked with a curing agent, and methods for making same. Preferably, the components of the composition are saturated, i.e., substantially free of unsaturated carbon-carbon bonds or aromatic groups, to produce a light stable composition.
BACKGROUND OF THE INVENTION
Golf equipment, i.e., clubs and balls, are formed from a variety of compositions. For example, golf ball covers are formed from a variety of materials, including balata and ionomer resins. Balata is a natural or synthetic trans-polyisoprene rubber. Balata covered balls are favored by more highly skilled golfers because the softness of the cover allows the player to achieve spin rates sufficient to more precisely control ball direction and distance, particularly on shorter shots.
However, balata covered balls are easily damaged, and thus lack the durability required by the average golfer. Accordingly, alternative cover compositions have been developed in an attempt to provide balls with spin rates and a feel approaching those of balata covered balls, while also providing a golf ball with a higher durability and overall distance.
Ionomer resins have, to a large extent, replaced balata as a cover material. Chemically, ionomer resins are a copolymer of an olefin and an &agr;, &bgr;-ethylenically-unsaturated carboxylic acid having 10 to 90 percent of the carboxylic acid groups neutralized by a metal ion, as disclosed in U.S. Pat. No. 3,264,272. Commercially available ionomer resins include, for example, copolymers of ethylene and methacrylic or acrylic acid, neutralized with metal salts. Examples of commercially available ionomer resins include, but are not limited to, SURLYN® from DuPont de Nemours and Company, and ESCOR® and IOTEK® from Exxon Corporation. These ionomer resins are distinguished by the type of metal ion, the amount of acid, and the degree of neutralization.
U.S. Pat. Nos. 3,454,280, 3,819,768, 4,323,247, 4,526,375, 4,884,814, and 4,911,451 all relate to the use of SURLYN®-type compositions in golf ball covers. However, while SURLYN® covered golf balls, as described in the preceding patent, possess virtually cut-proof covers, the spin and feel are inferior compared to balata covered balls.
Polyurethanes have also been recognized as useful materials for golf ball covers since about 1960. U.S. Pat. No. 3,147,324 is directed to a method of making a golf ball having a polyurethane cover. The resulting golf balls are durable, while at the same time maintaining the “feel” of a balata ball.
Various companies have investigated the usefulness of polyurethane as a golf ball cover material. U.S. Pat. No. 4,123,061 teaches a golf ball made from a polyurethane prepolymer formed of polyether with diisocyanate that is cured with either a polyol or an amine-type curing agent. U.S. Pat. No. 5,334,673 discloses the use of two categories of polyurethane available on the market, i.e., thermoset and thermoplastic polyurethanes, for forming golf ball covers and, in particular, thermoset polyurethane covered golf balls made from a composition of polyurethane prepolymer and a slow-reacting amine curing agent, and/or a difunctional glycol.
Unlike SURLYN® covered golf balls, polyurethane golf ball covers can be formulated to possess the soft “feel” of balata covered golf balls. However, golf ball covers made from polyurethane have not, to date, fully matched SURLYN® golf balls with respect to resilience or the rebound of the golf ball cover, which is a function of the initial velocity of a golf ball after impact with a golf club.
Furthermore, because the polyurethanes used to make the covers of such golf balls generally contain an aromatic component, e.g., aromatic diisocyanate, polyol, or polyamine, they are susceptible to discoloration upon exposure to light, particularly ultraviolet (UV) light. To slow down the discoloration, light and UV stabilizers, e.g., Tinuvin 770, 765, and 328, are added to these aromatic polymeric materials. However, to further ensure that the covers formed from aromatic polyurethanes do not appear discolored, the covers are painted with white paint and then covered with a clear coat to maintain the white color of the golf ball. The application of a uniform white pigmented coat to the dimpled surface of the golf ball is a difficult process that adds time and costs to the manufacture of a golf ball.
Polyureas have also been proposed as cover materials for golf balls. For instance, U.S. Pat. No. 5,484,870 discloses a polyurea composition comprising the reaction product of an organic diisocyanate and an organic amine, each having at least two functional groups. Once these two ingredients are combined, the polyurea is formed, and thus the ability to vary the physical properties of the composition is limited. Like polyurethanes, polyureas are not completely comparable to SURLYN® golf balls with respect to resilience or the rebound or damping behavior of the golf ball cover.
Therefore, there remains a continuing need for golf equipment having soft components that provide improved resilience, increased cut, scratch and abrasion resistance, and enhanced adherence without adversely affecting overall performance characteristics of the golf balls. In addition, it would be advantageous to provide a composition that combines the cut and scratch resistance with improved resistance to discoloration that are suitable for forming golf ball components and other golf-related equipment.
SUMMARY OF THE INVENTION
The invention is directed to golf equipment having at least a portion formed of a polyurea composition. In one embodiment, the present invention is directed to one-piece golf balls including polyurea. In another embodiment, the compositions of the invention are used in two-piece and multi-component, e.g., three-piece, four-piece, etc. golf balls including at least one cover layer and a core, wherein at least one cover layer includes at least one polyurea, as well as multi-component golf balls including cores and/or covers having two or more layers, wherein at least one such layer(s) is formed of at least one polyurea.
More particularly, the present invention is directed, in a first embodiment, towards a golf ball including at least a cover and at least one core layer wherein the cover is formed from a composition including at least one polyurea composition formed from a polyurea prepolymer of diisocyanate and polyether amine cured with a curing agent.
The present invention is further directed in a second embodiment towards a golf ball including a cover, a core and at least one intermediate layer interposed between the cover and an outermost core layer, wherein the intermediate layer is formed from a composition including a polyurea prepolymer of diisocyanate and polyether amine cured with a curing agent
The present invention is yet further directed in a third embodiment towards a golf ball including a cover, a core, and at least one intermediate layer interposed between the cover and the core, wherein the outermost cover layer and at least one intermediate layer are both formed from a polyurea composition including a polyurea prepolymer of diisocyanate and polyether amine cured with a curing agent.
In the golf ball cover embodiment of the present invention, the polyurea preferably includes from about 1 to about 100 weight percent of the cover, with the remainder of the cover, if any, including one or more compatible, resilient polymers such as would be known to one of ordinary skill in the art.
The invention is further directed to a golf ball including at least one light stable cover layer formed from a composition including at least one polyurea formed from a polyurea prepolymer and a curing agent. In one embodiment, the polyurea prepolymer includes at least one diisocyanate and at least one polyether amine.
In this aspect of the invention the diisocyanate is sa
Rajagopalan Murali
Wilson Craig A.
Wu Shenshen
Acushnet Company
Buttner David J.
Swidler Berlin Shereff & Friedman, LLP
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