the above object is achieved by connecting the applicator tube to a vibrating means . this ensures that the interface present at the wall in the applicator tube is not poor in flow or even flowless , as in the past , but is continuously moved by the vibration . even if it has prolonged residence times in this interface , the reaction mixture no longer has the opportunity to cake . however , the mass transfer transversely to the flow direction is also promoted by the continuous movement of the interface so that the residence time is reduced , i . e . the vibration process initiates a more desirable flow profile . as a surprising and particularly advantageous side effect , it has been found that gas dissolved in the reaction mixture issues almost completely in the form of small bubbles due to the vibrations . since these small bubbles serve as nucleating seeds at the beginning of the foaming reaction , a finer cell structure with improved thermal conductivity is formed . the vibration also prevents or reduces the tendency of a jet issuing from an opening to constrict . the frequency of vibration and / or the oscillation amplitude of the vibrating means are preferably adjustable . it is thus possible to adapt to the frequency of vibration and / or the oscillation amplitude to the respective requirements . adaptation may be necessary if a reaction mixture of a different viscosity is to be processed or if the working width changes . for example , operation in the resonant range can trigger or reinforce particular effects . according to one particular embodiment , the oscillating direction of the vibrating means coincides with the axial direction of the applicator tube . according to another embodiment , the oscillating direction is provided perpendicularly or transversely to the applicator tube . it is particularly advantageous to provide at least two superimposed oscillating directions . finally , it may be advantageous to superimpose two frequencies on one another . it is particularly advantageous to superimpose a frequency in the range of from 10 to 100 hz on a frequency in the range of from 10 to 500 hz . the higher frequency serves to move the interface in order to avoid caking whereas the lower frequency has the object of fanning out the jets issuing from the outlet openings . it is advantageous if fan formation takes place parallel to the applicator tube and the lower frequency is consequently applied in the axial direction of the applicator tube . if the frequency to be applied is based on the distance between the outlet openings , then it is possible to design the fans sufficiently wide to form a closed curtain at the moment when the reaction mixture strikes the substrate . as the fans formed have an approximately rhombic cross section , it is possible to arrange a substantially uniformly thick &# 34 ; curtain &# 34 ; of reaction mixture over the substrate by overlapping the fans over the working width in a suitable manner . to allow alteration of the working width , it is advantageous to design the applicator tube variable in length either by means of telescopic guidance or by means of exchangeable end pieces of differing length . an embodiment of the new apparatus is shown in the drawing and will be described when producing a laminated product . the figure shows a section through the charging region of the laminator . an applicator tube 3 which is connected via a branching outlet tube 4 to a mix head 5 is arranged transversely above the inlet region over the surface of the lower belt 2 of a laminator for the production of foam webs laminated with paper surface layers . on its lowest convex surface line , the tube has outlet openings 6 . the tube is arranged so as to oscillate by connecting one end to a vibrator 7 and the other end to an abutment 8 . a frequency controller 9 is connected to the vibrator 7 . the vibrator 7 and abutment 8 are fixed on the frame 11 by means of an oscillation - insulating bearing 10 . a paper web 12 is carried on the surface 1 and is folded up and supported at the sides by side strips 13 . the reaction mixture issuing from the outlet openings 6 is charged onto this paper web . the guidance frequency is adapted to the distance between the outlet openings 6 such that the issuing reaction mixture forms fans 14 which overlap one another so that a closed curtain 15 is formed immediately before it strikes the paper web 12 . although the invention has been described in detail in the foregoing for the purpose of illustration , it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims .