A multi-piece solid golf ball for professional golfers and skilled amateurs in particular is endowed with an excellent distance, a soft yet good feel at impact and a good durability. In the ball, which includes a core, an envelope layer, an intermediate layer and a cover, the core has a hardness profile which satisfies specific conditions, the envelope layer has a thickness of from 0.3 to 1.2 mm, the intermediate layer has a thickness of from 0.3 to 1.2 mm, and the envelope and intermediate layers have a combined thickness from of 0.8 to 1.7 mm.

An object with a tactile outer layer includes, for example, a ball having an outer surface and a series of protrusions or spikes on the outer surface. The protrusion each appear as a tear-dropped shape mass that includes a base having a relatively flat bottom adhered to the outer surface of the ball and a narrow tip and/or curved tail extending away from the outer surface. Manufacturing can be performed by mounting the object and utilizing injection arms that deposit elastomer globules on the object. The globules are deposited by pressure through a reservoir in the injection arm and the injection arms are then withdrawn to product the tail shape.

An object of the present invention is to improve the durability of the golf ball without substantially lowering the spin performance. The present invention provides a golf ball comprising a spherical core and a cover covering the spherical core, wherein the cover contains: (A) a base resin component, and (B) resin fine particles containing a polyrotaxane component having a cyclodextrin, a linear molecule penetrating the cyclic structure of the cyclodextrin in a skewering manner, and blocking groups located at both terminals of the linear molecule to prevent disassociation of the cyclodextrin, wherein at least a part of hydroxyl groups of the cyclodextrin is modified with a caprolactone chain via a OC.sub.3H.sub.6O group.

A multi-piece solid golf ball for professional golfers and skilled amateurs in particular is endowed with an excellent distance, a soft yet good feel at impact and a good durability. In the ball, which includes a core, an envelope layer, an intermediate layer and a cover, the core has a hardness profile which satisfies specific conditions, the envelope layer has a thickness of from 0.3 to 1.2 mm, the intermediate layer has a thickness of from 0.3 to 1.2 mm, and the envelope and intermediate layers have a combined thickness from of 0.8 to 1.7 mm.

Method for incorporating a tracking device within a body of elastomeric material, including the steps of: a) providing a semi-finished product made of a raw elastomeric material, preferably rubber or a thermoplastic polymer; b) providing a tracking device; c) providing an insert; d) joining by means of textile technique the tracking device and the insert so as to obtain a trackable insert; e) providing a mould; f) inserting the semi-finished product and the trackable insert into the mould; h) obtaining a trackable body by moulding the semi-finished product together with the trackable insert.

The present invention provides a golf ball capable of exhibiting an excellent spin performance in approach shot while the effect on the spin performance in driver shot is being suppressed to be low. The golf ball of the present invention includes a core, a cover located outside the core and having dimples formed thereon, and a coating layer located outside the cover and formed with a material having a surface force of 130 N or less.

A golf ball a core, one or more intermediate layers, and one or more cover layers. The core may comprise an inner portion and an outer portion. One or more layers of the golf ball may be formed by the application of ultrasonic welding on two half shells to form. One or more of the layers may be formed by a number of different chemical compositions, and may have varying thicknesses, hardnesses, coefficients of restitution, and PGA compression. The golf ball itself may have varying coefficient of restitution and PGA compression, depending on the layers.

Closed cell foam articles, such as sports balls, and related manufacturing methods are disclosed herein. The article includes a main body made of closed-cell elastomeric resin foam having a density ranging between about 0.050 sg and about 0.800 sg after curing. Some articles are assembled by inserting a cured core into a main body so that the core is secured in the main body via an interference fit, and the core has one or more portions extending to the exterior surface of the main body such that the an exposed surface of the one or more exposed portions of the core blend substantially with the exterior surface of the main body.

A method for forming a golf ball provides a core member comprising a core of a golf ball into a cavity of a mold so that the core member is supported by a movable holding pin disposed in the mold; forming a layer outside the core member by injecting a material of the layer into the cavity; and retracting the pin from the cavity into the mold during the material injection so that a portion projecting from a surface of the layer is formed by a tip of the pin, the projecting portion having a site area of at least 0.2% in relation to an entire area of the tip of the pin and having a height of at least 0.2 mm. This method can be implemented by controlling the retraction of the pin, or alternatively by using the pin having a predetermined indentation portion on the tip.

Closed cell foam articles, such as sports balls, and related manufacturing methods are disclosed herein. The article includes a main body made of closed-cell elastomeric resin foam having a density ranging between about 0.050 sg and about 0.800 sg after curing. Some articles are assembled by inserting a cured core into a main body so that the core is secured in the main body via an interference fit, and the core has one or more portions extending to the exterior surface of the main body such that the an exposed surface of the one or more exposed portions of the core blend substantially with the exterior surface of the main body.