Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-08-28
2004-09-21
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S270000, C528S322000, C473S354000, C473S371000, C473S374000, C473S378000
Reexamination Certificate
active
06794472
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to golf balls and, in particular, to self-healing polymeric compositions useful in golf ball covers, cores, and intermediate layers to improve the durability of the golf ball during the impact.
BACKGROUND OF THE INVENTION
The majority of golf balls commercially available today can be grouped into two general classes: solid and wound. Solid golf balls include one-piece, two-piece, and multi-layer golf balls. One-piece golf balls are inexpensive and easy to construct, but have limited playing characteristics and their use is usually confined to the driving range. Two-piece balls are generally constructed with a polybutadiene solid core and a cover and are typically the most popular with recreational golfers because they are very durable and provide good distance. These balls are also relatively inexpensive and easy to manufacture, but are regarded by top players as having limited playing characteristics. Multi-layer golf balls are comprised of a solid core and a cover, either of which may be formed of one or more layers. These balls are regarded as having an extended range of playing characteristics, but are more expensive and difficult to manufacture than are one- and two-piece golf balls.
Wound golf balls, which typically include a fluid-filled center surrounded by tensioned elastomeric material and a cover, are preferred by many players due to their spin and “feel” characteristics but are more difficult and expensive to manufacture than are most solid golf balls. Manufacturers are constantly striving, therefore, to produce a solid ball that retains the beneficial characteristics of a solid ball while concurrently exhibiting the beneficial characteristics of a wound ball.
Golf ball playing characteristics, such as compression, velocity, “feel,” and, therefore, spin, can be adjusted and optimized by manufacturers to suit players having a wide variety of playing abilities. For example, manufacturers can alter any or all of these properties by changing the materials (i.e., polymer compositions) and/or the physical construction of each or all of the various golf ball components (i.e., centers, cores, intermediate layers, and covers). Finding the right combination of core and layer materials and the ideal ball construction to produce a golf ball suited for a predetermined set of performance criteria is a challenging task.
The present invention is related to golf ball materials comprising at least one polymer and at least one healing agent to improve impact durability. Polymers are macromolecules built up by the linking together of large number of smaller molecules called monomers. Upon repetitive impact, the golf balls formed of many types of polymers tend to develop micro-cracks. One aspect of this invention is a way to make a polymeric golf ball component that is “repairable” through heating and cooling of the polymer backbone. No catalyst, monomers, or special surface treatments are required. The repaired plastic is believed to regain much of the strength of undamaged polymeric material. There is, therefore, a need for development of suitable healing agents that can be utilized to impart improved durability to golf ball cores, covers, and intermediate layers.
SUMMARY
The present invention is directed to a golf ball including a core and a cover disposed concentrically about the core, wherein at least one of the core or the cover is formed of a polymer including thermally reversible covalent bonds. At least about 20%, preferably at least about 30%, of the thermally reversible covalent bonds disconnect upon heating and re-connect upon cooling. Ideally, the reversible bonds disconnect at a temperature less than about 150° C., more preferably less than about 120° C., most preferably less than about 100° C.
The thermally reversible polymer typically include at least one furan diene unit and at least one amine comprising maleimide dienophiles. The furan diene units have the formula:
where R
1
, R
2
, and R
3
are hydrogen, alkyl, or aryl groups; and the amine comprising maleimide dienophiles has the formula:
where R
4
, and R
5
are hydrogen, alkyl, or aryl groups. Preferably, the polymer includes at least 4 furan diene units and at least 3 maleimide dienophiles.
The ball can be of any construction, but preferably the core comprises a center and an outer core layer. In one construction, the center includes a solid center, a hollow center, a gel, or a fluid. Alternatively, the cover comprises an inner cover layer and an outer cover layer, either one of which has a thickness of between about 0.03 inches and about 0.125 inches, Additionally, at least one of the core or cover may be foamed, includes a density-modifying filler, or both.
The present invention is also directed to a composition for sporting equipment formed of a polymer comprising thermally reversible covalent bonds. At least about 20%, preferably at least about 30%, of the thermally reversible covalent bonds disconnect upon heating and re-connect upon cooling. Ideally, the reversible bonds disconnect at a temperature of less than about 150° C., more preferably less than about 120° C., and most preferably less than about 100° C. The thermally reversible polymer typically include at least one furan diene unit and at least one amine including maleimide dienophiles. The furan diene units have the formula:
where R
1
, R
2
, and R
3
are hydrogen, alkyl, or aryl groups; and the amine includes maleimide dienophiles has the formula:
where R
4
, and R
5
are hydrogen, alkyl, or aryl groups.
DETAILED DESCRIPTION OF EMBODIMENTS
The golf balls of the present invention may comprise any of a variety of constructions. For example, the core of the golf ball may comprise a solid core surrounded by a cover layer. The core may be a single layer or may comprise a plurality of layers, such as a center and an outer core layer. In such a construction, the innermost portion of the core, the center, may be solid or a liquid filled sphere surrounded with an outer core layer. As with the core, the cover layer may also comprise a plurality of layers. For example, the cover may be formed of an inner and an outer cover layer. Additionally, the core, solid or otherwise, may also be surrounded by a wound layer of elastomeric material, generally tensioned. Any of these components may comprise the self-healing polymers of the present invention.
The polymeric compositions may include at least one of a base material and a microencapsulated healing agent. For the base material, the bulk of the golf ball material can be a thermoplastic, such as SURLYN®, or a thermoset, such as polyurethane, polyurethane-urea, polyurea-urethane, polyurea, or crosslinked polybutadiene. Microencapsulated healing agents are the “glue” that fixes the micro-cracks formed in the composite material. This healing agent is typically a fluid such as dicyclopentadiene (“DCPD”). DCPD is preferably encapsulated in tiny spheres or capsules that are spread throughout the polymeric material. Preferably, there are about 100 to about 200 capsules per cubic inch. Preferably, the spheres are about 300 &mgr;m or less in diameter.
In order to polymerize, the healing agent must come into contact with a catalyst. A preferred catalyst, called Grubbs catalyst, is used for this self-healing material. It is important that the catalyst and healing agent remain separated until they are needed to seal a crack. When a micro-crack forms in the base material, it will spread through the material. By doing so, this crack will rupture the microcapsules and release the healing agent. This healing agent will flow down through the crack and will inevitably come into contact with the Grubbs' catalyst, which initiates the polymerization process. This process will eventually bond the crack closed.
In a preferred embodiment, the self-healing polymer blend has a flexural modulus of from about 2,000 to about 200,000 psi contains microcapsules filled with dicyclopentadiene, dicyclohexa (or penta or octa) diene, (a liquid tricyclic diolefin), and a polymerization ca
Harris Kevin M
Rajagopalan Murali
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