The invention refers to a device for evaporating volatile substances comprising: a container of a liquid volatile substance, and a vapour permeable membrane (1) and a thermoplastic porous or fibrous laminate (2) bonded together. Said container is closed at its opening by said vapour permeable membrane (1) and the fibrous laminate (2), wherein the fibrous laminate (2) is welded to the thermoformed part of the container.