A method for injection molding of an airbag case comprising a chute channel and a flap, with the chute channel being adapted to receive an airbag. The injection molding is carried out in a mould and comprises the following steps: arranging in the mould a net, manufacturing the flap and the chute channel by injecting plastic matter into the mould, by overmolding plastic matter on the net by manufacturing a continuity of material between the chute channel and the flap, with a portion of the net being isolated from the injected plastic material, in a closed protective space delimited between a wedge mobile and a first matrix of the mould. An airbag case in particular manufactures with such a method and dashboard for a vehicle.