Method for manufacturing a fibrous material which is made of continuous fibres and impregnated with a thermoplastic polymer

A method for manufacturing an impregnated fibrous material comprising a fibrous material made of continuous fibres and at least one thermoplastic polymer matrix, characterized in that said fibrous material is sized by a sizing thermoplastic polymer and has, before its pre-impregnation with said thermoplastic polymer, an initial width I, said method comprising a step of spreading said fibrous material before a pre-impregnation step, said spreading step being carried out by means of at least two tension devices (E) and at least one heating system SC for heating said tension devices and/or said fibrous material, said spreading, after said fibrous material has passed in contact with said tension devices, being between 1.5 and 5 times the initial width I, said spread fibrous material being cooled below the Tg of the sizing thermoplastic polymer by means of a cooling system before it is placed in contact with said thermoplastic polymer matrix in the pre-impregnation system to carry out the pre-impregnation step, the spreading being consistent and always representing 1.5 to 5 times the initial width I when said fibrous material is placed in contact with said thermoplastic polymer matrix in the pre-impregnation system.