Method for manufacturing a golf ball

A method for manufacturing a golf ball that comprises a spherical core formed from a core rubber composition containing:

• (a) a base rubber, (b) an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d) a carboxylic acid and/or a salt thereof not including (b) the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof, and at least one cover layer covering the spherical core,
• comprising the steps of:
• blending (a) the base rubber and at least (d) the carboxylic acid and/or the salt thereof to prepare a first masterbatch;
• blending (a) the base rubber, and at least (b) the α, β-unsaturated carboxylic acid having 3to 8 carbon atoms and/or a metal salt thereof and (c) the crosslinking initiator to prepare a second masterbatch while adjusting a material temperature thereof to 95° C. or more;
• blending the first masterbatch and the second masterbatch to prepare the core rubber composition while adjusting a material temperature thereof to 90° C. or less;
• molding the core rubber composition into the spherical core;
• and
• forming at least one cover layer covering the spherical core,
• wherein the core rubber composition may further contain (e) a metal compound to neutralize the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a weight adjusting agent to adjust the weight of the spherical core, a hardness adjusting agent to adjust the hardness of the spherical core, or an inorganic pigment.