An injection molded composite comprising a first bonding surface of a diene rubber composition bonded to a second bonding surface of a polar thermoplastic elastomer composition. There may be no more than 25% of the bonding surfaces having an adhesive applied to them or alternatively, no adhesive is applied. Furthermore, the polar thermoplastic elastomer composition was injected against the first bonding surface to form the second bonding surface and the first bonding surface has an active halogen moiety.

A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is formed in a mold having support pins by injection molding. A ratio (V/S) of a volume V (mm.sup.3) of the cover 6 to an amount of compressive deformation S (mm) of the core 4 is not less than 1000 and not greater than 1900. The cover 6 has a shore D hardness of not greater than 62. The golf ball 2 has a plurality of dimples 8 on a surface thereof. A total volume W of these dimples is not less than 490 mm.sup.3 and not greater than 620 mm.sup.3. A ratio (α/P) of a latitude α (degree) of each support pin to a total cross-sectional area P (mm.sup.2) of the support pins is not less than 0.35 and not greater than 0.60.

A method for manufacturing a golf ball having a core, an intermediate layer and a cover that is formed of a resin material composed primarily of a polyurethane resin and has a thickness of 0.1 mm to 0.7 mm by injection molding the cover using a vertically separating two-part injection mold having specific gate and support pin configurations. This method enables a relatively soft urethane resin cover that is thin and of high quality to be formed, and has a good golf ball productivity.

A method for manufacturing a golf ball having a core, an intermediate layer and a cover that is formed of a resin material composed primarily of a polyurethane resin and has a thickness of 0.1 mm to 0.7 mm by injection molding the cover using a vertically separating two-part injection mold having specific gate and support pin configurations. This method enables a relatively soft urethane resin cover that is thin and of high quality to be formed, and has a good golf ball productivity.

A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is formed in a mold having support pins by injection molding. A ratio (V/S) of a volume V (mm.sup.3) of the cover 6 to an amount of compressive deformation S (mm) of the core 4 is not less than 1000 and not greater than 1900. The cover 6 has a shore D hardness of not greater than 62. The golf ball 2 has a plurality of dimples 8 on a surface thereof. A total volume W of these dimples is not less than 490 mm.sup.3 and not greater than 620 mm.sup.3. A ratio (/P) of a latitude (degree) of each support pin to a total cross-sectional area P (mm.sup.2) of the support pins is not less than 0.35 and not greater than 0.60.

A golf ball according to the present invention comprises: a core having a diameter of 37-39 mm and a first density; a mantle which surrounds the core, includes amorphous alloy powder, and has a thickness of 0.8-1.2 mm and a second density; and a cover which surrounds the mantle and has a thickness of 1-1.4 mm and a third density.

A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is formed in a mold having support pins by injection molding. A ratio (V/S) of a volume V (mm.sup.3) of the cover 6 to an amount of compressive deformation S (mm) of the core 4 is not less than 1000 and not greater than 1900. The cover 6 has a shore D hardness of not greater than 62. The golf ball 2 has a plurality of dimples 8 on a surface thereof. A total volume W of these dimples is not less than 490 mm.sup.3 and not greater than 620 mm.sup.3. A ratio (/P) of a latitude (degree) of each support pin to a total cross-sectional area P (mm.sup.2) of the support pins is not less than 0.35 and not greater than 0.60.

A method for manufacturing a golf ball having a core and a cover of at least one layer includes the step of molding the cover layer with a vertically separating two-part injection mold which has a spherical cavity and three or more support pins disposed so as to be capable of advancing and retracting in a direction perpendicular to a mold parting line, each support pin being housing in a pin housing hole having a nitrided inner peripheral sidewall. This method enables a golf ball cover material to be molded using an injection mold which, because a thick plating of hard chrome does not need to be applied to the inner peripheral sidewalls of the holes housing the support pins, is inexpensive and in which the pin housing holes have a good abrasion resistance.

A resin-rubber composite in which a polyamide-based resin-molded product or a polyphenylene sulfide-based resin-molded product is directly vulcanization-bonded to a peroxide-crosslinkable nonpolar rubber composition, which forms a rubber layer, without interposing an adhesive, wherein both resin-molded products have a polymerized film with a radical, which is formed by activating the surface of the product, in the case of polyamide-based resin-molded products, by low-pressure plasma treatment by a microwave method using inert gas, or by activating the surface of the product, in the case of polyphenylene sulfide-based resin-molded products, by low-pressure plasma treatment by a microwave method using active gas, and then performing low-pressure plasma treatment by a microwave method using a hydrocarbon-based monomer in both cases. The resin-rubber composite can be effectively used for drum seals, automobile parts such as side cover seals for transmissions, anti-vibration rubber, resin rubber laminate hoses, and the like.

A method for manufacturing a golf ball having a core and a cover of at least one layer includes the step of molding the cover layer with a vertically separating two-part injection mold which has a spherical cavity and three or more support pins disposed so as to be capable of advancing and retracting in a direction perpendicular to a mold parting line, each support pin being housing in a pin housing hole having a nitrided inner peripheral sidewall. This method enables a golf ball cover material to be molded using an injection mold which, because a thick plating of hard chrome does not need to be applied to the inner peripheral sidewalls of the holes housing the support pins, is inexpensive and in which the pin housing holes have a good abrasion resistance.