Games using tangible projectile – Golf – Ball
Reexamination Certificate
2001-07-06
2003-01-07
Passaniti, Sebastiano (Department: 3711)
Games using tangible projectile
Golf
Ball
C473S365000, C473S351000, C525S420000
Reexamination Certificate
active
06503157
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a golf ball having a polyurethane cover and a process for manufacturing the same.
2. Description of the Related Art
A wound golf ball having a “Balata” cover is widely used by high-level golfers and professional golfers, because Balata cover is superior in feel and control. Herein, “feel” is the overall sensation to the golfer when the golf ball is hit and “control” is to impart the motion such as back spin to the golf ball. However, the golf ball having a Balata cover is expensive due to a complicated manufacturing process and is inferior in durability and cut resistance.
For this reason, various cover stocks have recently been proposed in an attempt to replace the Balata cover.
For instance, a golf ball having an ionomer resin is disclosed in Japanese Unexamined Patent Application No.H01-308577. The ionomer resin cover is less expensive and has a superior durability than the Balata cover. However, it is pointed out that the ionomer resin cover is poor in feel.
U.S. Pat. No. 4,123,061 discloses a polyurethane cover formed by using a urethane prepolymer and a diamine curing agent. Japanese Examined Patent Application No. 2,662,909 also discloses a polyurethane cover formed by using a polyamine curing agent having a lower reactivity with an isocyanate group. Polyurethane cover generally has a higher impact resilience than the ionomer resin cover and has the good feel such as the Balata cover. However, in the process for manufacturing a golf ball having a polyurethane cover, there are various problems associated with the curing reaction.
The diamine curing agent disclosed by U.S. Pat. No. 4,123,061 has too high reactivity with the isocyanate group of a polyurethane prepolymer, hence the curing reaction proceeds even at the room temperature (not higher than 25° C.).
Therefore, it is difficult to prevent an increase in viscosity and gelation due to the curing reaction during mixing the polyurethane prepolymer with the diamine curing agent.
3,3′-dichloro-4,4′-diaminodiphenylmethane is disclosed as the typical amine-type curing agent in U.S. Pat. No. 4,123,061, which is preferably used as a curing agent for polyurethane polymer because the resulting polyurethane polymer exhibits excellent performance. However, 3,3′-dichloro-4,4′-diaminodiphenylmethane has the melting point of about 100° C., thus this curing agent usually needs to be melted by heating at 100° C. or higher temperature prior to use. Heating the curing agent such a high temperature causes the generation of the toxic vapor which pollutes the working place as well as promotes the curing reaction during mixing the polyurethane prepolymer with the curing agent.
In the case of a liquid diamine curing agent which can be mixed with a polyurethane prepolymer at a low temperature, it is still difficult to prevent an increase in viscosity and gelation due to the curing reaction proceeding during mixing. In addition, the resulting polyurethane polymer exhibits the poor physical properties than the polyurethane polymer using 3,3′-dichloro-4,4′-diaminodiphenylmethane.
If the polyamine curing agent having low reactivity disclosed in Japanese Patent No. 2,662,909 is used in an attempt to overcome the above problems, it is inevitable that the curing time becomes longer, which results in lowering the productivity. When the curing temperature is raised to shorten the curing time, there arises another problem that the rubber core of the golf ball is deteriorated by heat, resulting in the poor performance of the golf ball.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a golf ball and a process therefor, which overcome the foregoing problems raised in forming a cover by curing a polyurethane prepolymer.
The present invention provides a process for manufacturing a golf ball having a core and a cover covering the core, comprising;
coating the core with a composition including a complex of a polyamine compound with a metal salt, and an isocyanate group terminated polyurethane prepolymer; and
curing the composition to form the cover.
The present invention further provides a golf ball comprising a core, and a polyurethane cover covering the core, wherein the polyurethane cover is formed by curing a composition including
an isocyanate group terminated polyurethane prepolymer; and
a complex of a polyamine compound with a metal salt.
These and other objects, features and attendant advantages of the present invention will become apparent from the reading of the following detailed description.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The process of the invention comprises coating the core with a composition including a complex of a polyamine compound with a metal salt, and an isocyanate group terminated polyurethane prepolymer; and curing the composition to form the cover.
First of all, the composition including the isocyanate group terminated polyurethane prepolymer and the complex of a polyamine compound with a metal salt will be explained. Hereinafter, the composition is referred to as “cover stock composition”.
I. Isocyanate Group Terminated Polyurethane
The isocyanate group terminated polyurethane prepolymer used for the cover stock composition is not limited, as long as it has at least two isocyanate groups in a polyurethane prepolymer molecular chain. The location of each isocyanate group in a polyurethane prepolymer molecular chain is not particularly limited. The isocyanate group may be located at the terminal of the backbone chain or side chain of a polyurethane prepolymer molecular chain.
The isocyanate group terminated polyurethane prepolymer can be obtained by reacting polyisocyanate compound with a polyol so that isocyanate group of a polyisocyanate compound is at least stoichiometric quantity of the hydroxyl group of a polyol in molar ratio.
Polyisocyanate compound includes, without limitation, for example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HDI), 1,5-naphthylene diisocyanate (NDI), 3,3′-bitoluene-4,4′-diisocyanate (TODI), isophorone diisocyanate (IPDI), paraphenylene diisocyanate (PPDI), and xylene diisocyanate (XDI). In view of the impact resilience of an intended golf ball and the workability in manufacture, TDI and MDI, or a polyisocyanate compound including TDI or MDI as a major component are preferred.
Any polyol having a plurality of hydroxyl groups may be used in the present invention, for example, low molecular weight polyol and high molecular weight polyol may be used.
Low molecular weight polyol includes, for example, diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; and triols such as glycerin, trimethylolpropane, and hexanetriol. High molecular weight polyol includes, for example, polyether polyol obtained by the reaction between an initiator having active hydrogen and alkylene oxide; polyester polyol obtained by the condensation between a dibasic acid such as adipic acid and a glycol or a triol; lactone polyester polyol obtained by the ring-opening polymerization of a lactone such as &egr;-caprolactone; polycarbonate diol generally synthesized using a cyclic diol; and polymer polyol such as an acrylic polyol prepared by introducing a hydroxyl group into an acrylic copolymer.
Examples of polyether polyol are, without limitation, polyoxyethylene glycol, polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG). Examples of polyester polyol are, without limitation, polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA). Examples of such lactone polyester polyols include poly-&egr;-caprolactone (PCL). In view of their superior impact resilience and water resistance, polyether polyol is pre
Birch & Stewart Kolasch & Birch, LLP
Hunter Alvin A.
Passaniti Sebastiano
Sumitomo Rubber Industries Limited
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