I was told when I signed my first engineering employment contract that, "we own what you do here but we don't claim to own your brain." So who owns your learning journal?
One's learning journal is an informal but still written record of thought. It is similar to but might not have the legal standing of a regularly reviewed engineering notebook. Of particular concern here is how much of this will an employee take with them as their own upon separation?
Employees might cite internal resources that are of higher security than company confidential, but they should not quote higher security information in their journal.
Upon separation an employee is understood to leave with company confidential information in their heads. They are bound by separation agreements to protect that information into perpetuity except where other public sources make that information available. The same holds for their learning journal that remains joint property of the engineer and the employer.
Ownership of one's own learning journal might be provisional upon promotion beyond junior engineer. Senior engineering ranks might be expected to keep several learning journals, some of which will be in public and part of their open professional correspondence.
A company might reserve the right to review a separating employees learning journal and expunge pages judged to sensitive to be retained. The employee should have some opportunity to appeal that could lead to arbitration. The result of this exercise would be a much clearer and legally sound understanding of ongoing intellectual obligations.