System and Method For Extruding Parts Having Microstructures

Abstract

A manufacturing apparatus for manufacturing extruded parts having microstructures comprising: a support structure; a hopper carried by the support structure for receiving feedstock; an extrusion chamber operatively associated with the hopper for receiving the feedstock from the hopper and melting the feedstock above a feedstock melting temperature; a die carried by the support structure having die microstructures disposed on an inner surface of the die, the die microstructures having a plurality of microfeatures each having an upper surface and a lower surface, the melted feedstock being forced through the die to produce an extrudate having extrudate microstructures; and, a cooling assembly wherein the extrudate microstructures of the pre-cooled extrudate have larger physical dimensions than that of the extrudate microstructures of the cooled extrudate.

What is claimed is: 
     
         1 . A method of manufacturing an extruded item by an extrusion manufacturing process comprising the steps of:
 providing an extrusion feedstock;   providing an extrusion die having microstructures disposed on an interior surface of said die, said die having a plurality of microfeatures having a depth between about 0.1 and 500 μm wherein each of said microfeatures includes an upper surface and a lower surface;   creating an extrudate having pre-cooled extrudate microfeatures by forcing said feedstock through said extrusion die so that said extrudate includes physical properties selected from the group consisting of: hydrophobicity, hydrophilicity, self-cleaning, decreased or increased hydro-dynamic drag coefficients, decreased or increased aerodynamic drag coefficients, increased friction, reduced friction, optical effects, increased adhesion, decreased adhesion, oleophobicity, oleophillicity, tactile effects, anti-blocking and any combination of these; and,   cooling said extrudate so that said pre-cooled extrudate microstructures have a larger physical dimension than that of said extrudate microstructures of said cooled extrudate.   
     
     
         2 . The method of  claim 1  wherein said extrudate microstructures of said cooled extrudate have a height in the range of 70 to 90 μm, a width in the range of 120 to 160 μm and a general slope shape. 
     
     
         3 . The method of  claim 1  including gathering said extrudate so that said extrudate microstructures of said extrudate have a larger physical dimension than that of said extrudate microstructures after said extrudate has been gathered. 
     
     
         4 . The method of  claim 1  including:
 processing said extrudate in a manner taken from the group consisting of: 
 drawing down, flattening, stretching, embossing, coating, stamping, rolling, spiraling, heating, freezing and any combination of these; and, 
 wherein said extrudate microstructures of said extrudate have larger physical dimensions than that of said extrudate microstructures of said extrudate after said extrudate passes through said post extrusion assembly. 
 
     
     
         5 . The method of  claim 1  including:
 providing a mandrel having microstructures disposed on an outer surface of said mandrel; and, 
 creating an inner cavity in said extrudate having an inner surface having microstructures. 
 
     
     
         6 . The method of  claim 1  including cooling said extrudate so that said area of said microstructure on said extrudate prior cooling said extrudate compared to an area of said microstructure post said extrudate is  0 . 5  to  25  times smaller. 
     
     
         7 . The method of  claim 1  including drawing said extrudate so that said area of said microstructure on said extrudate prior said drawing is  0 . 5  to  25  times smaller than a surface area of said microstructure on said extrudate post said drawing. 
     
     
         8 . A method of manufacturing extruded parts having microstructures comprising:
 melting feedstock above the feedstock's melting temperature;   forcing the melted feedstock through a die, the die having a lower surface having an arc defined in the lower surface and an upper surface having an upper channel, the upper surface having a concave potion;   producing pre-cooled extrudate having pre-cooled extrudate microstructures;   cooling the pre-cooled extrudate;   producing a post-cooled extrudate wherein the microstructures have a height in the range of 70 μm to 90 μm, a width in the range of 120 μm to 160 μm and a general slope.   
     
     
         9 . The method of  claim 8  wherein the step of producing pre-cooled extrudate having include the step of producing pre-cooled extrudate having a physical shape taken from the group consisting of a film, a square column, rectangular column, trapezoidal column, asymmetrical column, circular column, oval column, triangular column and any combination of these. 
     
     
         10 . The method of  claim 8  including the step of gathering the post-cooled extrudate. 
     
     
         11 . The method of  claim 10  including the step of producing post-gathered extrudate microstructures that have physical dimensions smaller than that of the pre-gathered extrudate microstructures. 
     
     
         12 . The method of  claim 8  including processing the post-cooled extrudate in a manner taken from the group consisting of: drawing down, flattening, stretching, embossing, coating, stamping, rolling, spiraling, heating, freezing and any combination of these. 
     
     
         13 . A method of manufacturing extruded parts having microstructures comprising:
 melting feedstock above the feedstock's melting temperature;   forcing the melted feedstock through a die having a plurality of microstructures disposed in the an inner surface;   producing pre-cooled extrudate having pre-cooled extrudate microstructures;   cooling the pre-cooled extrudate;   producing a post-cooled extrudate wherein the post-cooled extrudate microstructures have a height in the range of 70 μm to 90 μm, a width in the range of 120 μm to 160 μm and a general slope.   
     
     
         14 . The method of  claim 13  wherein the step of producing a post-cooled extrudate includes producing microstructures on the pre-cooled extrudate arranged in an alternating pattern so that the post-cooled extrudate includes physical properties taken from the group consisting of: hydrophobicity, self-cleaning, increased hydro-dynamic drag coefficients, decreased or increased aerodynamic drag coefficients, increased friction, reduced friction, optical effects, increased adhesion, decreased adhesion, oleophobicity, oleophillicity, tactile effects, and anti-blocking. 
     
     
         15 . The method of  claim 13  include the step of providing a die having microstructures disposed on an inner surface of the dye, a lower channel included in the die having walls having an interior angles of incident in relation to an upper surface less than 90°, a width having a range of between 0.25 to 1.25 mm and a height having a range of 0.25 to 1.25. 
     
     
         16 . The method of  claim 13  including the step of forming a post-cooled extrudate microstructure having a wall angle of at least 90°. 
     
     
         17 . The method of  claim 13  including the step of forming a post-cooled extrudate microstructure having a general pillar shaped cross-section. 
     
     
         18 . The method of  claim 13  including the step of forming a post-cooled extrudate microstructure having dimensions in the rage of  0 . 1  μm to 500 μm. 
     
     
         19 . The method of  claim 13  including forming an interior cavity in the pre-cooled extrudate having microstructures on an inner surface of the interior cavity. 
     
     
         20 . The method of  claim 13  including:
 forming post-cooled extrudate microstructures disposed on an external wall of the pre-cooled extrudate; 
 forming an interior cavity in the pre-cooled extrudate; and, 
 forming microstructures on an inner surface of the interior cavity.