Polymer powder blending apparatus

Abstract

An apparatus for blending polymer powder and pigment inside of a blender that heats the polymer through agitation of the blending process. The apparatus includes a control scheme that monitors the condition of the powder and discharges the powder from the blender just before the powder reaches its melting point. The apparatus monitors the flowability of the powder as well as the temperature. As an additional method of controlling the temperature inside of the blender, the blending speed can be varied by virtue of a variable speed motor that is attached to the blender.

What is claimed is.  
     
         1 . A method of conditioning polymer powder comprising the steps of: 
 preprogramming set point data into a controller, where the set point data comprises flowability data and powder outletflow data;    feeding a specified amount of powder into a container; where said powder has a flowability value that changes in proportion to changes in powder temperature;    stirring said powder inside of said container at a rate sufficient to heat said powder;    discharging a fraction of said powder within the container and measuring the flowability of said fraction with a flowability meter that is in data communication with said controller;    comparing the measured flowability of said fraction with the flowability data pre programmed into said controller; and    when the evaluated flowability of the powder being discharged from the container is equal to the flowability data pre programmed into said controller, discharging the powder remaining in the container.    
     
     
         2 . The method of  claim 1  further comprising adding a specified amount of pigment to said powder within the container.  
     
     
         3 . The method of  claim 1  further comprising the step of cooperatively adapting a load cell to said flowability meter and measuring the flowability of the discharging powder with the flowability meter adapted to include a load cell.  
     
     
         4 . The method of  claim 1  further comprising the step of preprogramming a temperature set point into said controller, measuring the actual temperature of the powder being discharged from the container, and discharging all powder remaining in the container when the actual temperature of the powder being discharged from the container is equal to the temperature set point.  
     
     
         5 . The method of  claim 1  further comprising the step of adding another specified amount of powder to the container after all of the powder has been discharged from the container.  
     
     
         6 . The method of  claim 5  further comprising the step of adding another specified amount of pigment to the container after all of the powder has been discharged from the container.  
     
     
         7 . The method of  claim 1  further comprising the step of preprogramming said controller with a flowability value that corresponds to an optimum temperature for mixing said powder with said pigment.  
     
     
         8 . The method of  claim 1  further comprising controlling the temperature of said powder by controlling the rate of rotation of said container.  
     
     
         9 . The method of  claim 1  further comprising cooling said discharged powder by forcing the powder through a fluidized air driven bed unit.  
     
     
         10 . The method of  claim 9  further comprising separating off-spec material from said cooled powder.  
     
     
         11 . The method of  claim 10  further comprising selectively directing off-spec material to an off-spec container and directing said cooled powder to a product container.  
     
     
         12 . Apparatus for blending pigment with particulate polyolefin resin, said apparatus comprising: 
 a continuous blender adapted to receive powder at a controlled rate of feed through a powder inlet, adapted to receive pigment at a controlled rate of feed through a pigment feed inlet, and a powder outlet;    one or more stirrers attached within said continuous blender to blend the powder and pigment residing inside of said continuous blender;    a pigment feed flow control device in communication with said pigment fee inlet;    a powder outletflow control device in communication with said powder outlet capable of regulating the amount of powder flowing from said powder outlet;    a flowability meter positioned to receive powder flowing from said powder outletflow control device; and    a controller in communication with said flowability meter and said powder outletflow control device, where said controller receives flow data from said flowability meter, compares the flow data to pre programmed flow data set points within the controller memory, calculates the flow control data required in the powder outletflow control device, and transmits the flow control data to said powder outletflow control device.    
     
     
         13 . The blending apparatus of  claim 12 , further comprising a powder feed flow control device in communication with said powder feed inlet.  
     
     
         14 . The blending apparatus of  claim 13 , wherein said controller also calculates the flow control data required in the powder feed flow control device, and transmits the flow control data amount to said powder feed flow control device.  
     
     
         15 . The blending apparatus of  claim 14 , wherein said powder feed flow control device regulates powder flow into said continuous blender based on flow control data received from said controller.  
     
     
         16 . The blending apparatus of  claim 15 , further comprising a pigment feed flow control device in communication with said pigment feed inlet.  
     
     
         17 . The blending apparatus of  claim 16 , wherein said controller also calculates the flow control data required in the pigment feed flow control device, and transmits the flow control data to said pigment feed flow control device.  
     
     
         18 . The blending apparatus of  claim 17 , wherein said pigment feed flow control device regulates pigment flow into said continuous blender based on flow control data received from said controller.  
     
     
         19 . A pigmented polymer particulate conditioned in accordance with the method of  claim 1  comprising: 
 a polymer powder particle impregnated with pigment along its outer surface, where said pigment is encapsulated within the outer crust of said polymer powder particle material such that said pigment adheres to said polymer powder particle.  
 
     
     
         20 . The pigmented polymer particulate of  claim 19 , wherein said polymer powder particle is selected from the group comprising, polyethylene, and polypropylene.  
     
     
         21 . The pigmented polymer particulate of  claim 19 , wherein said pigment is in powder form.  
     
     
         22 . The pigmented polymer particulate of  claim 19 , wherein said pigment is in liquid dispersed form.