Separating film composition, the starting material and process for the preparation of a starting material as well as surface treatment agent for a starting material and using a surface treatment agent

Cellulose fiber-based substrate of which at least a surface with a surface treatment layer containing at least one water-soluble polymer backbone is coated, characterized in that comprising water-soluble polymer backbone hydroxyl functions, at least some previously of which at least one organic molecule comprising a vinyl function, and contains aldehyde, have been implemented.