Golf ball and method of manufacture
In a golf ball having a core composed of one or more layer, the outermost layer of the core is formed of a rubber composition containing a base rubber and an α,β-unsaturated metal carboxylate, an envelope layer directly encasing the core is formed of a resin composition containing a thermoplastic resin having a structure that includes α,β-ethylenically unsaturated carboxylic acid copolymerization units, and a surface of the core outermost layer and the envelope layer adjoin each other through an intervening oxazoline group-containing substance. The golf ball has improved adhesion between the rubber-based core and the cover layer that directly encases the core and is formed of an ionomer resin or other α,β-ethylenically unsaturated carboxylic acid copolymer-containing resin material.
1. A method for producing a golf ball having a core composed of one or more layer, which method comprises the steps of:
forming an outermost layer of the core with a rubber composition containing a base rubber and an α,β-unsaturated metal carboxylate;
surface-treating the core outermost layer by bringing a solution that contains an oxazoline group-containing substance into contact with a surface of the outermost layer;
forming an envelope layer by molding, over the surface-treated core outermost layer, a resin composition containing a thermoplastic resin having a structure that includes α,β-ethylenically unsaturated carboxylic acid copolymerization units; and
prior to surface-treating the core outermost layer with a solution that contains an oxazoline group-containing substance, the step of surface-treating the outermost layer of the core by bringing an acid-containing solution into contact with the surface of the outermost layer.
2. The method of claim 1 , wherein the acid-containing solution is a hydrochloric acid-containing solution.
3. The method of claim 1 , wherein the acid-containing solution is an alcohol-containing solution.
4. The method of claim 1 , wherein the acid-containing solution, when brought into contact with the surface of the core outermost layer, has an acid concentration of 0.05 mol/L or more.
5. The method of claim 1 , wherein the acid-containing solution is brought into contact with the surface of the core outermost layer by dipping the core in the acid-containing solution.
6. The method of claim 1 , wherein the solution containing an oxazoline group-containing substance is an alcoholic solution.