Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-12-06
2001-01-30
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C473S351000, C473S378000, C524S589000, C528S044000, C528S045000, C528S048000, C528S055000, C528S058000
Reexamination Certificate
active
06180714
ABSTRACT:
This invention relates to a golf ball coating composition and a golf ball coated therewith.
BACKGROUND OF THE INVENTION
Among a variety of paints on golf balls, a polyurethane paint of the two-part curing type wherein polyol and polyisocyanate are mixed immediately before use is commonly adopted since it is resistant to substantial deformation, impact and friction.
As it is currently desired to increase the spin rate of golf balls, the cover has been made softer. In order to avoid any deformation of the soft cover during paint coat drying, it is now necessary to dry paint coats at lower temperatures. From the productivity standpoint, it is desired to reduce the curing time of paint in order that a series of coating steps from application to drying be finished in a short time.
One practice for improving the workability of paint (for example, low-temperature drying and time reduction) is to increase the amount of curing catalyst relative to the paint base. This is successful in promoting the curing reaction of the paint, but at the same time, reduces the pot life of the paint, inviting many drawbacks such as inefficient working and deterioration of the paint prior to application.
It is, therefore, desired to have a paint which has a satisfactory pot life and a short curing time and is thus improved in workability, and at the same time, forms a coat having improved characteristics including durability, water resistance and adhesion.
SUMMARY OF THE INVENTION
An object of the invention is to provide a golf ball coating composition which has a long pot life, contributes to improvements in workability and productivity in the manufacture of golf balls, and forms a coat of quality. Another object is to provide a golf ball of quality coated with the composition.
It has been found that when a two-part curable urethane paint consisting essentially of a polyol and a polyisocyanate is blended with a metal chelating agent having a boiling point of up to 200° C. and an organometallic compound as a curing catalyst, the metal chelating agent blocks the metal moiety of the organometallic compound to adjust its catalysis adequate so that the curing time of a coat may be substantially reduced without shortening the pot life. The golf ball manufacturing process can then be shortened. Coats resulting from this coating composition are of quality and consequently, golf balls coated therewith are also improved in quality.
The coating performance is further improved when a metal chelating agent having a boiling point of up to 150° C., more specifically acetylacetone or a fluorinated derivative thereof is used and when the metal moiety of the organometallic compound is tin or zinc. Additionally, the characteristics required as the golf ball coat including durability, adhesion, abrasion resistance and water resistance are improved. Coated golf balls of higher quality are obtainable.
Accordingly, the invention provides a golf ball coating composition comprising a two-part curable urethane paint consisting essentially of a polyol and a polyisocyanate, a metal chelating agent having a boiling point of up to 200° C., and an organometallic compound as a curing catalyst. A golf ball coated with the coating composition is also provided.
The golf ball coating composition of the invention is successful in significantly reducing the curing time required for coats to cure, at no sacrifice of the pot life. This leads to improvements in workability and productivity of the golf ball manufacturing process. After compounding, the coating composition is prevented from changing its properties. Golf balls coated with the coating composition have stabilized coat performance. Since the coats can be cured at lower temperatures, golf balls even with soft cover stock undergo no thermal deformation during the coating operation. Then golf balls with good appearance and high quality are obtained.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The golf ball coating composition of the invention is based on a two-part curable urethane paint consisting essentially of a polyol and a polyisocyanate.
The polyol component used herein may be a well-known one and selected from, for example, polyester polyols, acrylic polyols, and polyether polyols. Also useful are modified ones of these polyols, for example, acrylic-modified polyester polyols, polyester-modified acrylic polyols, and polyether-modified polyester polyols. The use of acrylic-modified polyols is especially preferred.
The polyisocyanate component used herein is not critical as long as it serves as a curing agent for the polyol component. For example, when weather resistance is taken into account, a non-yellowing type polyisocyanate (typically HMDI: methylenebis(4-cyclohexyl isocyanate)) may be selected. The polyisocyanate is not limited thereto and may be selected so as to meet the desired performance, from TDI (tolylene diisocyanate), XDI (xylylene diisocyanate), IPDI (isophorone diisocyanate) and HDI (hexamethylene diisocyanate), for example.
The coating composition of the invention is formulated by blending a metal chelating agent and an organometallic compound as a curing catalyst in the above-described two-part curable urethane paint. The metal chelating agent chelates or blocks the metal moiety of the curing catalyst to adjust its catalysis adequate so that the pot life may be prolonged.
The metal chelating agent used herein should have a boiling point of up to 200° C., and especially up to 150° C. If a chelating agent having a higher boiling point is used, some time is necessary for the agent to volatilize or evaporate during low-temperature drying, retarding the drying step.
As long as the metal chelating agent is effective for chelating the metal moiety of the organometallic compound, it may be selected from, for example, &bgr;-diketones, keto-esters, hydroxycarboxylic acids and esters thereof, keto-alcohols, and enolic active hydrogen compounds. These metal chelating agents can be used as the solvent for the paint. Of these, &bgr;-diketones such as acetylacetone and fluorinated derivatives thereof and keto-esters such as methyl acetoacetate and ethyl acetoacetate are preferable because they readily volatilize at low temperatures during the drying step (that is, have a low boiling point) and do not react with isocyanates. It is recommended to use acetylacetone and fluorinated derivatives thereof because of their low boiling point, low cost, and availability. The use of the metal chelating agent as the low-boiling solvent has the following advantages. First, the metal chelating agent blocks the metal moiety of the organometallic compound as the catalyst through chelate formation, thereby prohibiting the catalysis and extending the pot life. Secondly, since the solvent readily volatilizes at the drying temperature (above about 40° C.), the catalyst blockage is relieved during the drying step so that curing of the coat quickly takes place.
The amount of the metal chelating agent added may be determined as appropriate in accordance with the type thereof and the balance thereof with the organometallic compound and the two-part urethane paint. An appropriate amount of the metal chelating agent is about 0.1 to 10%, and preferably about 1 to 5% by weight based on the entire coating composition. Outside the range, lesser amounts of the metal chelating agent may insufficiently block the metal moiety of the organometallic compound, failing to extend the pot life. Excessive amounts of the metal chelating agent may take a long time to evaporate off, retarding the drying of an applied coat and reducing the working efficiency.
The coating composition of the invention uses an organometallic compound as the curing catalyst. There may be used organometallic compounds which are commonly blended as the curing agent in prior art two-part curable urethane paints.
Then, the organometallic compound used herein may be selected from a number of well-known ones. Those organometallic compounds having a metal soap structure within the molecule are recommended when the solubility in the above-described so
Muta Susumu
Ohira Takashi
Sasaki Hiroto
Bridgestone Sports Co. Ltd.
Niland Patrick D.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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