Apparatus and method to control the temperature of a melt stream

Abstract

Disclosed is an apparatus for controlling the temperature of a melt stream, a method of using the apparatus to make variable-density polymeric articles, and the polymeric article formed thereby. The apparatus for making the article includes a row of baffles wherein the baffles include a temperature-control conduit defined or disposed within at least one of the baffles. A polymer melt is passed through the apparatus while the temperature of the baffles is varied (which has the effect of altering the density of certain polymer melts). The process can be used to yield a continuous, monolithic polymeric article of variable density. The apparatus can also be used to control the temperature of the material passing through the apparatus.

1 . An apparatus comprising: 
 a row of baffles, the row comprising a plurality of baffles wherein each baffle defines a longitudinal axis, wherein each baffle includes an upstream portion and a downstream portion, wherein the downstream portion of each baffle is convex or pointed, wherein each baffle has a non-cylindrical cross-section perpendicular to its longitudinal axis, and further wherein the baffles of each row define a converging flow path for materials passing through the apparatus; and    a closed-circuit, temperature-control conduit defined or disposed within at least one of the baffles.    
     
     
         2 . The apparatus of  claim 1 , wherein the longitudinal axis of each baffle in the row is parallel to the longitudinal axis of another baffle in the row, and wherein the downstream portion of each baffle has a width wider than the upstream portion, and wherein the downstream portion of each baffle has a convex surface.  
     
     
         3 . The apparatus of  claim 1 , wherein the temperature-control conduit is a void defined within the baffle, wherein the void is configured to allow a temperature-control medium to flow within the conduit.  
     
     
         4 . The apparatus of  claim 1 , wherein the temperature-control conduit is a solid thermal-control device disposed within the baffle.  
     
     
         5 . The apparatus of  claim 1 , comprising a conduit defined or disposed within each baffle.  
     
     
         6 . The apparatus of  claim 1 , wherein the downstream portion of each baffle has a convex shape.  
     
     
         7 . The apparatus of  claim 1 , comprising a plurality of rows of baffles, wherein the longitudinal axes of the baffles in one row are transverse to the longitudinal axes of the baffles in an adjacent row.  
     
     
         8 . The apparatus of  claim 7 , wherein the axes of one row of baffles are rotated about 90 degrees relative to the axes of the baffles in an adjacent row.  
     
     
         9 . The apparatus of  claim 7 , wherein the axes of the baffles in one row are parallel to the axes of the baffles in a non-adjacent row.  
     
     
         10 . The apparatus of  claim 7 , wherein the baffles in one row overlap with the baffles of an adjacent row.  
     
     
         11 . The apparatus of  claim 1 , wherein the baffles are substantially teardrop in shape.  
     
     
         12 . The apparatus of  claim 1 , wherein the downstream portion of at least one baffle is semi-cylindrical in shape.  
     
     
         13 . The apparatus of  claim 1 , wherein the downstream portion of at least one baffle is semi-elliptical in shape.  
     
     
         14 . The apparatus of  claim 1 , wherein the upstream portion and the downstream portion of each baffle are pointed.  
     
     
         15 . The apparatus of  claim 14 , wherein the upstream portion and the downstream portion of each baffle are symmetrical about a plane perpendicular to direction of flow of material through the apparatus.  
     
     
         16 . The apparatus of claims  1 , further comprising a die lip dimensioned and configured to yield an extrudate having a predetermined profile.  
     
     
         17 . The extrusion die of  claim 16 , wherein the die lip is dimensioned and configured to yield an extrudate having planar profile.  
     
     
         18 . A method for manufacturing variable-density polymeric articles, the method comprising: 
 (a) passing a polymer melt through an apparatus comprising a row of baffles, the row comprising a plurality of baffles wherein each baffle defines a longitudinal axis, wherein each baffle includes an upstream portion and a downstream portion, wherein the downstream portion of each baffle is convex or pointed, wherein each baffle has a non-cylindrical cross-section perpendicular to its longitudinal axis, and further wherein the baffles of each row define a converging flow path for materials passing through the apparatus; and a closed-circuit, temperature-control conduit defined or disposed within at least one of the baffles to control the baffle's temperature; and    (b) varying the temperature of the baffle via the temperature-control conduit as the polymer melt passes through the apparatus, wherein the temperature is varied to cause density of the polymer melt passing proximate to the baffle to be altered as compared to density of the polymer melt passing distal to the baffle, thereby yielding a polymeric article having variable density.    
     
     
         19 . The method of  claim 18 , wherein in step (a) the longitudinal axis of each baffle in the row is parallel to the longitudinal axis of another baffle in the row, and wherein the downstream portion of each baffle has a width wider than the upstream portion.  
     
     
         20 . The method of  claim 18 , wherein step (b) comprises varying the temperature of the baffle such that the density of the polymer melt passing proximate to the baffle is increased as compared to the density of the polymer melt passing distal to the baffle.  
     
     
         21 . The method of  claim 18 , wherein in step (a), the apparatus is dimensioned and configured to yield a polymeric article having a predetermined profile.  
     
     
         22 . The method of  claim 21 , wherein in step (a), the apparatus is dimensioned and configured to yield a polymeric article having a planar profile.  
     
     
         23 . The method of  claim 18 , further comprising, after step (b), 
 (c) and then passing the polymer melt through a die dimensioned and configured to yield a polymeric article having a predetermined profile.    
     
     
         24 . The method of  claim 18 , further comprising, after step (b), 
 (c) and then passing the polymer melt through a die dimensioned and configured to yield a polymeric article having a planar profile.    
     
     
         25 . The method of  claim 18 , wherein step (b) comprises varying the temperature of the baffle to yield areas of increased density within the polymer article, and further wherein the areas of increased density are disposed substantially perpendicular to the planar profile, substantially parallel to the planar profile, or at non-perpendicular, non-parallel angles to the planar profile.  
     
     
         26 . The method of  claim 18 , further comprising: (c) co-extruding at least one additional polymer melt to yield a composite, variable-density polymeric article.  
     
     
         27 . A variable-density polymeric article comprising: 
 a continuous, monolithic, polymeric body, without joints or seams, and having defined therein areas of higher density disposed adjacent to areas of lower density.    
     
     
         28 . A variable-density polymeric article of  claim 27 , produced by: 
 (a) passing a polymer melt through a die comprising a row of baffles, the row comprising a plurality of baffles, each baffle defining a longitudinal axis that is parallel to the longitudinal axis of another baffle in the row, wherein each baffle includes an upstream portion, and a downstream portion having a width wider than the upstream portion; and a closed-circuit temperature-control conduit defined or disposed within at least one of the baffles to control the baffle's temperature; and    (b) varying the temperature of the baffle via the temperature-control conduit as the polymer melt passes through the die, wherein the temperature is varied to cause density of the polymer melt passing proximate to the baffle to be altered as compared to density of the polymer melt passing distal to the baffle, thereby yielding a polymeric article having variable density.