Container assembly, closure cap for container assembly, container for container assembly, method for manufacturing a container assembly

A container assembly comprising a container and a closure, wherein:

• the container is suited for holding a substance, the container being made of a crystallisable polymer material and comprising a neck portion that has an inner neck surface and outer, threaded neck surface and defines an outlet opening of the container, the neck portion being configured for receiving the closure in a closed state of the container assembly;
• the closure includes a closure cap that is made of a crystallisable polymer material and has an inner, threaded cap surface, the closure cap being matched to the neck portion of the container to cover the outlet opening when the container assembly is in the closed state;
• and
• the inner, threaded cap surface of the closure cap is in contact with the outer, threaded neck surface of the neck portion when the container assembly is in the closed state;
• characterized in that the crystallizable polymer material of the inner, threaded cap surface of the closure cap is crystallized more than an outer cap surface and/or the outer, threaded neck surface of the neck portion with which the inner, threaded cap surface of the closure cap is in contact when the container assembly is in the closed state is crystallized more than the inner neck surface, such that the crystallinities is selected to allow the container assembly to be opened after being closed for an elongated period of time,
• wherein with the outer, threaded neck surface of the neck portion and the inner, threaded cap surface of the closure cap, the container assembly, in use, can be opened and closed by a rotational motion of the closure cap with respect to the container.