Spray-coating method

Abstract

A method for spray-coating substrate surfaces, in which (a) a thermoplastically processable material is molten and thus liquefied in an extruder in a first step; (b) the molten material is pressurized by means of a carrier gas or vapor; (c) a mixture formed from said molten material and said carrier gas or vapor is pressed through one or more nozzles, optionally supplying a spraying gas having a temperature at least as high as the melt temperature to the spraying jet in the region of the discharge opening of the nozzle; and (d) the obtained spray jet with the molten material is directed onto the substrate surface, wherein the material impinges in drops in a flowable state onto the substrate surface, forms a continuous coating on the substrate surface, and subsequently solidifies.

1 . A method for spray-coating substrate surfaces, in which
 (a) a thermoplastically processable material is molten and thus liquefied in an extruder in a first step;   (b) the molten material is pressurized by means of a carrier gas;   (c) a mixture formed from said molten material and said carrier gas is pressed through one or more nozzles, supplying a spraying gas having a temperature at least as high as the melt temperature to the spraying jet in the region of the discharge opening of the nozzle; and   (d) the obtained spray jet with the molten thermoplastically processable material is directed onto the substrate surface, wherein the material impinges in drops in a flowable state onto the substrate surface, forms a continuous coating on the substrate surface, and subsequently solidifies.   
     
     
         2 . The process according to  claim 1 , characterized in that said thermoplastically processable material is selected from homopolymers, co- and terpolymers or thermoplastically processable elastomers, especially acrylonitrile-butadiene-styrene (ABS), polyamide (PA), polylactate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyether ether ketone (PEEK) and polyvinyl chloride (PVC) including copolymers and compounds thereof, which may optionally contain further components, especially fillers. 
     
     
         3 . The process according to  claim 1  characterized in that an amount of fillers of from 0 to 80% by weight is employed, based on the thermoplastically processable material. 
     
     
         4 . The process according to  claim 3 , characterized in that said filler is inorganic in nature. 
     
     
         5 . The process according to  claim 3  characterized in that said filler is in the form of an inorganic short fiber. 
     
     
         6 . The process according to  claim 3  characterized in that said filler has polymeric fibers having a melting temperature higher than the processing temperature of the compound. 
     
     
         7 . The process according to  claim 3  characterized in that said filler comprises natural fibers. 
     
     
         8 . The process according to  claim 2  characterized in that the mixture, the thermoplastically processable material and/or the filler itself as well as the weight ratio of thermoplastically processable material to filler is varied in the course of the spraying process. 
     
     
         9 . The process according to  claim 1  characterized in that nitrogen, carbon dioxide or air is employed as the carrier gas and/or spray gas. 
     
     
         10 . The process according to  claim 1  characterized in that a spraying jet with a weight ratio of thermoplastically processable material to carrier gas within a range of from 100:0.1 weight parts to 100:30 weight parts is employed. 
     
     
         11 . The process according to  claim 1  characterized in that a spraying jet with a pressure of from 10 to 500 bar is employed. 
     
     
         12 . The process according to  claim 1  characterized in that from 1 to 50 nozzles with different output cross-sectional areas are employed. 
     
     
         13 . The process according to  claim 1  characterized in that said mixture is pressed through orifice and/or slotted nozzles. 
     
     
         14 . The process according to  claim 1  characterized in that orifice nozzles with the same or different diameters within a range of from 0.1 mm to 10 mm, or discharge openings with comparable cross-sectional areas are employed. 
     
     
         15 . The process according to  claim 1  characterized in that slotted nozzles with the same or different cross-sectional areas of 0.1 to 3 mm×3 to 30 mm are employed. 
     
     
         16 . The process according to  claim 1  characterized in that a continuous coating that is porous or coherent in itself is prepared. 
     
     
         17 . The process according to  claim 1  characterized in that a substrate selected from textiles or a mold cavity with or without a surface structure is employed.