A golf ball which reduces the impact on the environment is provided. The golf ball, which may be a one-piece ball or a ball having a core and a cover of one or more layer, is composed at least in part of a biodegradable material.

Prior-art golf balls include one-piece balls, two-piece balls, three-piece balls, and multi-layer balls having an even larger number of layers. Concrete materials used in such golf balls include, as core materials: thermoplastic elastomers such as natural rubber, butadiene rubber, isoprene rubber and styrene-butadiene rubber; and as cover materials enclosing the core: thermoplastic resins such as ionomers, polyamides, polyesters, polyetheresters, polyetheramides and thermoplastic polyurethanes, and thermoset resins such as polyureas, thermoset polyurethanes, epoxy resins, polyphenols, polysilicones and urea-melamine resins. These golf balls are mass-produced by processes such as injection molding and compression molding in a volume of some hundreds of millions of balls annually.

Used golf balls are generally disposed of in a landfill or incinerated, although a certain proportion of golf balls end up as lost balls or are otherwise abandoned to the environment. Because the above materials used as ingredients of golf balls are unlikely to be biodegradable to any substantial extent, there is some concern over the adverse impact of such abandoned golf balls on the environment. JP-A 7-213204, JP-A 2001-192023 and JP-A 2003-284800 indicate the use of biodegradable materials in the production of fishing gear, boxes for packaging golf balls, and shuttlecocks. Yet, when it comes to golf balls produced in a larger volume than these other products, there exists an unmet need for the development of technology to manufacture golf balls not harmful to the environment.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide golf balls having a lower impact on the environment.

It was found that by consisting of a biodegradable material as at least one ingredient of a golf ball, and particularly by forming a golf ball using a biodegradable material designed as a mixture of a biodegradable compound with, for example, a thermoplastic resin in a specific form to compatibilize both ingredients in a ratio, the formation of a golf ball not harmful to the environment can be achieved.

Accordingly, the invention provides a golf ball composed of a biodegradable material as at least an ingredient of the golf ball. Preferably, the golf ball is a one-piece golf ball composed of the biodegradable material, or a golf ball consisted of a biodegradable material as at least an ingredient of both a core and a cover of one layer or multi-layers.

In one aspect of the invention, the biodegradable material includes at least one ester group-containing biodegradable compound.

In another aspect of the invention, the biodegradable material includes at least one ester group-free biodegradable compound.

The biodegradable material of either of the foregoing aspects of the invention is also a mixture of the biodegradable compound with a thermoplastic resin, a thermoplastic elastomer and/or a thermoset resin.

It is preferable for the mixture prepared by blending the biodegradable compound with a thermoplastic resin, thermoplastic elastomer and/or thermoset resin in a weight ratio, described as (biodegradable compound)/(total amount of thermoplastic resin, thermoplastic elastomer and thermoset resin), of from 5/95 to 95/5. The mixture has an interpenetrating polymer network structure.