The Tiny Placemat from Ezpz is a non-slip, silicone placemat that fits on most highchair trays (including the Ikea Antilop). The placemat comes with a silicone travel band, which allows you to roll-up the mat and use it on the go!
Note – the edges of the Tiny Placemat may retain the rolled form. If this happens, simply wet the mat and seal the mat edges to the table/tray with your fingers.