Games using tangible projectile – Golf – Ball
Reexamination Certificate
2000-05-12
2002-06-04
Chapman, Jeanette (Department: 3711)
Games using tangible projectile
Golf
Ball
C528S318000
Reexamination Certificate
active
06398669
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to golf balls having a body on which a coating film is formed, and particularly to a painted golf ball having improved smoothness and contamination resistance of the ball surface while maintaining originally intended performances of the coating film.
2. Description of the Background Art
Commercially available golf balls have been manufactured having a body to which paint is applied to form a coating film thereon for the purposes of keeping aesthetic appearance and protecting the ball surface. The coating film formed of the paint is required to have such basic characteristics as impact resistance and wear resistance in order to endure repeated hitting by a golf club.
In general, as a paint material which meets these performances, two-component type urethane resin paint has frequently been employed that is produced by curing polyfunctional isocyanate and polyester polyol in the presence of catalyst. However, conventionally employed paint material for golf balls is relatively flexible and thus elongates well in order to enhance the impact resistance to repeated hitting by a golf club. Therefore, the resultant coating film is soft which increases the coefficient of friction of the ball surface. For example, in a system of collecting and transporting a large number of golf balls which is employed in the golf practice field, the golf balls tend to stick to each other due to the frictional force forming a cluster which clogs the transportation passage. This problem is called blocking.
In order to avoid this blocking, a small amount of silicone oil is added to a coating film component. However, the silicone component does not chemically bond to the coating film component so that the component for providing smoothness to the coating film, which is contained in the coating film, could be released because of repeated hitting or long term use, resulting in impaired smoothness.
According to Japanese Patent Laying-Open No. 5-269221, in an attempt to obtain a golf ball having an excellent smoothness for a long period while retaining impact resistance of the coating film, urethane-based clear paint is employed containing modified polysiloxane with a main chain of molecules partially containing at least one hydroxyl group. In this case, the modified polysiloxane serving to give smoothness to the golf ball surface has the hydroxyl group in the main chain and can thus react with binder resin. However, the modified polysiloxane has a high surface activity and thus readily diffuses throughout the surface. Further, the modified polysiloxane has a characteristic of remaining on the coating film because of its reactivity. Although this characteristic is effective for the smoothness of the surface, unreacted components of the polysiloxane tend to remain. Therefore, when a golf ball is immersed in a washing detergent for removing dirt on the golf ball or the golf ball is exposed to rain water, the unreacted components of the modified polysiloxane containing the hydroxyl group and resin of a relatively small molecular weight (including polysiloxane) diffuse into water, resulting in a considerable damage to the surface smoothness. Since polysiloxane tends to remain on the coating film surface, the effect of the surface smoothness is remarkable at first. However, this effect does not last for a long period of time because those components exposed to water are likely to diffuse into the water.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a golf ball having an excellent smoothness of the ball surface which is maintained over a long period of time, by solving the problems above in the conventional art and especially improving the smoothness of the ball surface while maintaining basic performances such as impact resistance of the coating film.
In order to achieve this object, the inventors of the present invention have thoroughly studied and found that smoothness can be provided to the surface of a golf ball and the effect of the smoothness can be kept for a long period without impairing impact resistance of a coating film, by forming the coating film on the surface of the golf ball using urethane resin-based paint, acrylic resin-based paint, or epoxy resin-based paint which contains modified polysiloxane having at least one hydroxyl group or carboxyl group in one end of a polysiloxane chain.
Specifically, according to the present invention, a painted golf ball is provided which is constituted of a golf ball body and a coating film applied onto the body. The coating film is formed of urethane resin-based paint, acrylic resin-based paint, or epoxy resin-based paint. The paint contains modified polysiloxane of 0.1 to 10% by weight relative to a resin component of the paint. The modified polysiloxane has at least one hydroxyl group or carboxyl group in one end of a polysiloxane chain. The molecular weight of the modified polysiloxane is 700 to 7000.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Modified polysiloxane having at least one hydroxyl group or carboxyl group in one end of a polysiloxane chain, which is employed in the present invention, is represented by a general chemical formula below:
where n represents an integer, R represents alkyl group, Me represents methyl group, and X represents alkyl group having at least one hydroxyl group or carboxyl group in an end carbon. The alkyl group may partially include at least one ether group or ester group. Here, “end” means an end of a main chain which is a chain having at least one hydroxyl group or carboxyl group. The main chain can include a side chain formed of 3 or less carbons.
The number of end hydroxyl groups or end carboxyl groups may be 1 to 3, and preferably 1 or 2. Modified polysiloxane having at least one carboxyl group in one end is commercially available as Silaplane FM-0611, Silaplane FM-0621 and Silaplane FM-0625 which are manufactured by CHISSO CORPORATION. Modified polysiloxane having at least one hydroxyl group in one end is commercially available as Silaplane FM-0411, Silaplane FM-0421, Silaplane FM-0428, Silaplane FM-DA11, Silaplane FM-DA21 and Silaplane-DA25 manufactured by CHISSO CORPORATION.
The modified polysiloxane shown above has at least one hydroxyl group or carboxyl group in one end of a polysiloxane chain to chemically react with the resin component of the paint. Accordingly, the polysiloxane chain is directly grafted to the main chain of the paint and thus can be properly aligned with the polymer main chain of the paint. As a result, there are fewer chances that unreacted polysiloxane remains. Then, washing by water does not cause siloxane to run off and a long-lasting effect is achieved. In particular, modified polysiloxane having two hydroxyl groups in one end is suitable because it is hardly left unreacted.
If a chain of modified polysiloxane has hydroxyl groups or carboxyl groups in both ends, the polysiloxane chain is taken into the main chain of the paint, which adversely influences characteristics of a coating film such as impact resistance. Therefore, such modified polysiloxane is not preferable.
If a chain of modified polysiloxane has at least one hydroxyl group via at least one alkyl group or ester group of a long chain, the portion of the alkyl or ester chain which has the hydroxyl group is bonded to the main chain of resin. In this case, it is difficult to establish alignment of the polysiloxane chain with the main chain of resin and thus there is generated unreacted polysiloxane. In view of this, the polysiloxane is required to have a molecular weight of 7000 or less.
If the molecular weight of polysiloxane is less than 700, the reactivity of polysiloxane with resin is lower. Further, a large amount of polysiloxane should be blended for achieving desired physical properties. In this case, there are many components which do not r
Maruoka Kiyoto
Wayaku Kaichiro
Yokota Masatoshi
Birch & Stewart Kolasch & Birch, LLP
Chapman Jeanette
Hunter Alvin A.
Sumitomo Rubber Industries Ltd.
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