Process for the production of pure methylal

The invention relates to a continuous process to make and isolate methylal by reacting formaldehyde and methanol with an acid catalyst under at least partial formation of methylal and water, to form a mixture M2 comprising formaldehyde, methanol, methylal, and water, separating the said mixture M2 in a distillation column B into three distinct product streams, one being a distillate taken from the column head BH which is rich in methylal, one taken from the column bottom stream BB being almost pure water, and one taken from the side of the column B below the second reaction zone which stream is rich in methanol, characterised in that the ratio of the amount of substance of methanol to the amount of substance of formaldehyde in the mixture M1 is at least 3 mol/mol, and to an apparatus to be used with this process.