Sound absorbing and sound insulating automotive noise attenuating trim part

A process for producing a sound attenuating trim part, comprising at least the following steps:

• a first fibrous non-woven layer, a barrier layer and a second fibrous non-woven layer are stacked on top of each other, with the first fibrous non-woven layer above the barrier layer and the barrier layer above the second fibrous non-woven layer;
• the obtained multilayer is laid on the lower half-mold of a moulding tool comprising an upper half-mold and a lower half-mold which, when closed, delimit a cavity having the shape desired for the noise attenuating trim part;
• in order to cure the fibrous layers and make them adhere to the barrier layer, hot steam is injected into the moulding tool cavity both from the upper half-mold and from the lower half-mold, wherein the pressure of the hot steam injected both from the lower half-mold and from the upper half mold is first increased from 0 bar to a maximum value preferably comprised between 5 bar and 6 bar and then kept constant at this maximum value and wherein, during the pressure increase phase of the hot steam pressure, the pressure of the hot steam injected from the lower half-mold is higher than that of the steam injected from the upper half-mold, by an amount preferably comprised between 1 bar and 2 bar, so to compress the first porous fibrous layer between the barrier layer and the upper half-mold;
• after a time interval sufficient for the hot steam to cure the fibrous layers and make them adhere to the barrier layer, the steam is exhausted both through the upper half-mold and through the lower half-mold of the molding tool;
• and
• the moulding tool is opened and the molded part is taken out of it.