Sheet and method for its production and a value and / or security document

The invention relates to a data sheet for a security document with a substrate layer (11) to form a front page (12) and an opposite data page (14), wherein the substrate layer (11) consists of a fiber composite layer (18), which (with at least one pressure 25 is, 35) is printable and (after printing the front page 12) or the data page (14), or both with a potting compound (19) impregnated, at least 50% of the free volume of the fiber composite layer (18) with the casting compound (19) filled is.