Now i have the Loctite 435 and made some tests.
That stuff sticks like hell

I took two plastic plates 2x2 cm, about 1mm thick and glued them together at the thin side.
After 12 hours hardening i am not able to get the plates apart by hand.
Pulling and bending with all power i have causes nothing, it feels like one plate.
Think i found a good glue.

Same effect when glueing plastic to metal.