A blank (2) is molded for the manufacture of a multi-layer preform (1). The blank possesses protrusions (5). After the protrusions (5) have been brought to a plasticized state under the action of heat, those surfaces that contain protrusions (5) are covered by a layer of plasticized material. The blank (2) becomes connected to the layer (6) in the area of the protrusions (5). After cooling of the preform created from the blank (2) and the layer (6), the blank (2) will be connected with the layer (6) by means of microweld positions (7) in the area of the said protrusions (5). With that, delamination of the preform (1) during further processing or use will be effectively prevented.