I think a newsletter is a good idea to address it. State your closing time and ask that all communication be done before that. If they all prefer to hear about their child's day over reading about it, than I'd suggest stopping the communication books as it's just a waste of your time

For myself, I only have one family that picks up at my closing time but I still give them a run down of our day, unless I need to go ASAP but I try and make my evening appts 15 minutes later than I think I need too so it leaves some leeway.

I'm a chatter myself so I usually don't mind it. It's nice to have that adult interaction lol. I'm not friends outside of daycare with any of my families so I feel it's important to establish that rapport during business hours. I mean, it's just part of the job right?? We talk about their child's day, anything funny they said or did, any issues (knock on wood, this is VERY rare), what we ate, how they slept, unusual bm's and than usually chat about anything else under the sun lol. Two of my dads and one of my moms will sometimes chat for 20 minutes!