Methods of overmolding softer material with harder material and moisture tight container assemblies made by the methods

A method of forming a cap assembly for use with a container in forming a container assembly, the cap assembly including a seal formed from a first material and a cap formed from a second material having one or both of a greater hardness when solidified than the first material and/or a higher melting temperature than the first material, the method comprising:

• providing a mold having a portion which defines the shape of the cap assembly, wherein a first portion of the mold has an outer surface into which a groove is defined;
• providing the first material in the groove such that only a single surface of the first material is exposed to a vacant portion of the mold, the entire single surface of the first material being flush with a plane defined by the outer surface of the first portion of the mold;
• providing, via an injection molding process, the second material in a liquid form in the vacant portion of the mold adjacent to, and in engagement with, the first material;
• and
• allowing the second material to solidify and become directly coupled to the first material, thus forming the cap assembly.