I have a 45 year old copper beech tree that has quite a bit of...
We can't say what the problem without more information.
First, look at the information on our website about slime flux, which can occur on large shade trees: http://extension.umd.edu/hgic/shade-trees-slime-flux-and-wetwood If you tree looks perfectly healthy except for the bleeding, then it is likely that it just has some slime flux which is not harmful. You are welcome to send us digital photos of the bleeding and trunk in a reply to this email.
Beech can also get canker and other diseases that would have a damaging affect on the tree. In order to make that diagnosis, you would need a certified arborist, certified by the International Society of Arboriculture, come onsite and look at it and probably need to take a sample to be examined under a scope. Many tree service companies have certified arborists on their staff. To find one, go to: www.treesaregood.org. If your tree is showing decline, this diagnosis is more probable.