Golf ball

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

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C525S268000, C525S269000, C525S274000, C473S371000, C473S372000, C473S377000

Reexamination Certificate

active

06713565

ABSTRACT:

BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,929,678 discloses a rubber composition for a solid golf ball having excellent durability and rebound properties comprising: (a) a rubber component comprising at least 40 percent by weight of a polybutadiene rubber which has a Mooney ML 1+4 viscosity of 50 to 70 and a cis-1,4 bond content of at least 80 percent, (b) a co-crosslinking agent and (c) a peroxide. The polybutadiene rubber that is utilized in manufacturing golf balls can be synthesized utilizing a wide variety of organometallic catalyst systems. For instance, some representative examples of organometallic catalyst systems that can be used include trialkyl aluminum-nickel carboxylate-boron trifuoride etherate systems, trialkyl aluminum-organonickel compound-hydrogen fluoride systems, alkyl aluminum halide-cobalt carboxylate systems, alkyl aluminum-titanium salt systems, alkyl aluminum-titanium salt-iodine complexes, alkyl lithium compounds, alkyl lithium-amine complexes, neodymium halide-alkyl aluminum systems, neodymium carboxylate-alkyl aluminum-alkyl aluminum halide systems, and organoneodymium compound-alkyl aluminum halide systems.
Rare earth catalyst systems can be employed in synthesizing the cis-1,4-polybutadiene. For example, 1,3-butadiene monomer can be polymerized with a catalyst system which is comprised of (1) an organoaluminum compound, (2) an organometallic compound which contains a metal from Group III-B of the Periodic System, such as a lanthanide selected from the group consisting of neodymium, praseodymium, cerium, and gadolinium, and (3) at least one compound which contains at least one labile halide ion.
U.S. Pat. No. 4,663,405 is based upon the use of vinyl halides as molecular weight regulators in polymerizations which are catalyzed with rare earth metal catalyst systems. U.S. Pat. No. 4,663,405 more specifically discloses a process for polymerizing conjugated diolefin monomers into polymers which utilizes a catalyst system which is comprised of (1) an organoaluminum compound, (2) an organometallic compound which contains a metal from Group III-B of the Periodic System, such as a lanthanide selected from the group consisting of neodymium, praseodymium, cerium, and gadolinium, and (3) at least one compound which contains at least one labile halide ion; wherein the molecular weight of the polymer produced in reduced by conducting the polymerization in the presence of a vinyl halide, such as vinyl bromide, vinyl chloride, and vinyl iodide.
Ziegler-Natta catalyst systems are commonly used in the polymerization of conjugated diolefin monomers, such as 1,3-butadiene, into rubbery polymers. Nickel-based catalyst systems are commonly used in the polymerization of 1,3-butadiene monomer into cis-1,4-polybutadiene rubber. Such nickel-based catalyst systems contain (a) an organonickel compound, (b) an organoaluminum compound and (c) a fluorine containing compound. Such nickel-based catalyst systems and their use in the synthesis of cis-1,4-polybutadiene is described in detail in U.S. Pat. Nos. 3,856,764, 3,910,869 and 3,962,375.
Various compounds have been found to act as molecular weight-reducing agents when used in conjunction with the nickel-based catalyst system. For instance, U.S. Pat. No. 4,383,097 discloses that alpha-olefins, such as ethylene and propylene, act as molecular weight-reducing agents when utilized in conjunction with such three-component nickel catalyst systems. U.S. Pat. No. 5,698,643 indicates that 1-butene, isobutylene, cis-2-butene, trans-2-butene and allene act as molecular weight regulators when used in conjunction with such nickel-based catalyst systems. U.S. Pat. No. 4,383,097 reveals that certain nonconjugated diolefins, such as 1,4-pentadiene, 1,6-heptadiene and 1,5-hexadiene, act as molecular weight-reducing agents when utilized in conjunction with such catalyst systems. U.S. Pat. No. 5,100,982 indicates that cis-1,4-polybutadiene having reduced molecular weight and a broad molecular weight distribution can be synthesized with certain nickel-based catalyst systems in the presence of halogenated phenols, such as para-chlorophenol.
U.S. Pat. No. 5,451,646 discloses that para-styrenated diphenylamine acts as a molecular weight-reducing agent when employed in conjunction with nickel-based catalyst systems which contain (a) an organonickel compound, (b) an organoaluminum compound and (c) a fluorine containing compound. The teachings of U.S. Pat. No. 5,451,646 also indicate that para-styrenated diphenylamine acts to improve the processability of cis-1,4-polybutadiene rubbers prepared in their presence utilizing such nickel-based catalyst systems. Para-styrenated diphenylamine can be employed in conjunction with such nickel-based catalyst systems to reduce the molecular weight of the rubber without sacrificing cold flow characteristics. The para-styrenated diphenylamine that remains in the rubber produced also acts in a manner that provides it with antioxidant protection. In other words, the para-styrenated diphenylamine accomplishes two major objectives. It acts as a molecular weight regulator and acts as an antidegradant.
U.S. Pat. No. 5,451,646 specifically discloses a process for producing cis-1,4-polybutadiene having a reduced molecular weight and improved processability which comprises polymerizing 1,3-butadiene in the presence of (a) an organonickel compound, (b) an organoaluminum compound, (c) a fluorine containing compound and (d) para-styrenated diphenylamine; wherein the organoaluminum compound and the fluorine containing compound are brought together in the presence of the para-styrenated diphenylamine.
After the desired degree of monomer conversion has been attained in polymerizations that are conducted with organometallic catalyst systems a terminator (short-stop) is added to terminate the polymerization. Rosin acids are commonly used as terminators for such polymerizations. The rosin acids that are used on a commercial basis are comprised predominately of abietic acid that contains about 10 percent of a mixture dihydroabietic acid and dehydroabietic acid. Abietic acid is of the structural formula:
SUMMARY OF THE INVENTION
This invention is based upon the unexpected discovery that cis-1,4-polybutadiene that is synthesized utilizing organometallic catalyst systems has superior characteristics for utilization in solid golf ball cores if the polymerization is short-stopped utilizing a carboxylic acid of the structural formula RCOOH, wherein R represents an alkyl group containing from 1 to about 30 carbon atoms.
The present invention more specifically discloses a golf ball which is comprised of a solid core and a resin cover, wherein the solid core is comprised of cis-1,4-polybutadiene rubber which is made by polymerizing 1,3-butadiene in the presence of an organometallic catalyst system wherein the polymerization is short-stopped with a carboxylic acid of the structural formula RCOOH, wherein R represents an alkyl group containing from 1 to about 30 carbon atoms.
The present invention further reveals a rubber composition for a solid golf ball having excellent durability and rebound properties comprising: (a) cis-1,4-polybutadiene rubber, wherein said cis-1,4-polybutadiene rubber has a Mooney ML 1+4 viscosity of 30 to 90, wherein said cis-1,4-polybutadiene rubber has a cis-1,4 bond content of at least 95 percent, wherein cis-1,4-polybutadiene rubber is made by polymerizing 1,3-butadiene in the presence of organometallic catalyst system, wherein the polymerization is short-stopped by the addition of a carboxylic acid of the structural formula RCOOH, wherein R represents an alkyl group containing from 1 to about 30 carbon atoms.
DETAILED DESCRIPTION OF THE INVENTION
The cis-1,4-polybutadiene rubber used in the golf balls of this invention is synthesized by polymerizing 1,3-butadiene monomer utilizing a standard organometallic catalyst system. However, after the desired level of monomer conversion is attained the polymerization is terminated (short-stopped) by the addition of a carboxylic acid of the structural formula R

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