Golf Ball

The present invention relates to a golf ball which is coated by paints.

There are enameled golf balls and non-enameled golf balls commercially available. The enamaled golf balls are produced by coating its surface once or twice with an enamel paint which contains a pigment which comprises from about 20 to 50% by weight based on the solid content of the paint. The color of the enameled golf balls appear as the color of the enamel paint, because the color of the golf ball is concealed by the enamel paint. The non-enameled golf balls are produced by coating only with a clear paint. The color of the non-enameled golf balls is the same as the color of the golf ball itself.

In order to impart a beautiful color to a golf ball, pigments are formulated into a cover composition. This attempt, however, would be unsuccessful if an enamel paint having opacifying properties which are too high is applied to a golf ball in the same manner as applied to the enameled golf balls. In case of the non-enameled golf balls, it is required to formulate the pigments into a cover composition of the golf balls in a large amount in order to obtain the same color tone as the enameled golf balls. However, this causes the physical properties of the golf ball to deteriorate. Also, since the non-enameled golf balls have no enamel layers, ultraviolet lights are transmitted through the clear coat layer without any barriers so as to lead to a deterioration of surface properties, especially in the adhesion properties. Especially, in the case of a golf ball which is covered with an ionomer resin, the ionomer resin becomes severely deteriorated by ultraviolet lights which gives rise to a ply separation between the clear paint layer and the ionomer resin cover. For preventing the deterioration of adhesion properties, it is proposed to formulate an ultraviolet absorber into a clear paint. However, the formulation of the ultraviolet absorber would decrease the fine view and gloss of the cover. Further, if there are stains on the surface of the golf ball, these stains would be in plain sight and would diminish the commodity quality thereof.

It is desirable to develop golf balls having the desirable properties of both the enameled and non-enameled golf balls, as well as having the good appearance of both.

An object of the present invention is to provide a golf ball having the desirable properties of both the enameled and non-enameled golf balls. The golf ball is produced by coating its surface with an enamel paint containing a pigment of 1 to 10% by weight based on the solid content of the paint. An enamel paint conventionally used for golf balls contains about 20% by weight of pigments, but the enamel paint employed by the present invention contains 1 to 10% by weight which is less than the conventional one.

Another object of the present invention is to provide a two-piece golf ball prepared by coating a golf ball core with a resin composition comprising a pigment of 0.5 to 10% by weight and a cover resin of 0.5 to 10% based on said resin composition, and then coating the coated golf ball core with an enamel paint containing a pigment of 1 to 10% by weight based on a the solid content of said paint.

FIG. 1 is a sectional view of a two-piece golf ball of the present embodiment.

The enamel paint employed in the present invention includes an epoxy enamel paint, an aqueous urethane enamel paint or a solvent type urethane enamel paint. The enamel paint contains a pigment in an amount of 1 to 10% by weight, preferably 5 to 10% by weight based on the solid content of the enamel paint. When the amounts of the pigment are less than 1% by weight, the surface of the golf ball would be exposed to a high amount of the ultraviolet light as mentioned in the case of the non-enameled golf balls. When the amounts of the pigment are more than 10% by weight, the opacifying properties are too high to decrease the transparency and depth in the appearance of the golf ball.

The pigment formulated in the enamel paint includes a pigment having high opacifying properties, such as titanium dioxide, zinc oxide and the like; a pigment having transparency, such as micronized barium sulfate, zinc sulfate and the like. The pigment having transparency imparts high transparency to the obtained golf ball with preserving weather resistance. Preferred are the pigments having high opacifying properties.

The thickness of the enamel coating layer is generally within the range of 5 to 30 micron, preferably 10 to 25 micron. For obtaining a suitable thickness of the coating layer, a coating process can be repeated. A thickness of more than 30 micron makes meaningless the use of an enamel paint containing less amounts of the pigment than the amounts used in conventional enamel paints. Thus the color of the enameled golf ball does not reflect the basic color of a golf ball. The thickness of less than 5 microns does not impart the technical effects by the enamel coatings of the present invention.

A golf ball to be utilized in the present invention includes a one-piece golf ball, a balata covered golf ball or an ionomer covered golf ball. Preferred is the ionomer covered golf ball.

According to the present invention, it is preferred that the color of the golf ball be the same as the enamel paint to be coated. For imparting an excellent appearance to the golf ball, in the case of a white two-piece golf ball, it is preferred that the golf ball is prepared by covering a core with a resin composition containing a white pigment of 0.5 to 10% by weight and a cover resin of 0.5 to 10% by weight based on the composition. It is more preferred that the resin composition for the golf ball additionally contains a fluorescent whitening agent in an amount of 0.2 to 0.6% by weight.

The present invention is further explained with reference to FIG. 1.

The enamel paint mentioned above is coated once or twice by a conventional method on a golf ball which is prepared by covering core 1 with cover 2 to form enamel layer 3, to which a clear paint is applied to form outermost clear layer 4. If desirable, a clear paint layer may be formed between the golf ball and enamel layer 3. The clear paint includes a urethane type clear paint, an acryl type clear paint, an epoxy type clear paint and the like.

The present invention is illustrated by the following examples, which, however, are not to be construed as limiting the present invention to the details thereof.

Paints are applied to two piece golf balls which are covered by an ionomer resin composition (an ionomer resin (Surlyn 1605/1706=50/50 blend)/TiO.sub.2 =98/2 by weight) as shown in Table 1. Evaluation was made on appearance, paint adhesion after a weather resistance test, yellowing after a weather resistance test, crack resistance of the paint, opacifying properties of stains of the cover. The result of the evaluation is shown in Table 1.

Paints are applied to two-piece golf balls which are coated with an ionomer resin composition (an ionomer resin (Surlyn 1605 made dual ioning by Mg ions [see USP 4,526,375])/TiO.sub.2 /a fluorescent whitening agent Whiteflour HCS=97.9/1.8/0.3 by weight) as shown Table 2. Evaluation is made on appearance, paint adhesion after a weather resistance test, yellowing after a weather resistance test, crack resistance of the paint, opacifying properties of stains of the cover. The result of the evaluation is shown in Table 2.