Multi-layer golf balls with increased interlayer adhesion

A golf ball, comprising:

• a center;
• an outer core layer disposed on the center;
• a casing layer disposed on the outer core layer, wherein the casing layer comprises carboxyl groups;
• and
• a cover layer disposed about the casing layer and formed from a cover composition comprising an adhesion promoter with at least one functional group, wherein the casing layer and cover layer are bonded by crosslinks between the at least one functional group in the cover layer and the carboxyl groups in the casing layer.

A golf ball, comprising:

• a core;
• a casing layer disposed on the core, wherein the casing layer comprises carboxyl groups;
• and
• a cover layer disposed about the casing layer and formed from a cover composition comprising an adhesion promoter with at least one functional group that crosslink with the carboxyl groups to form one or more of the following linkage: