Roll coatings sol-gel precursors

Abstract

A roll coater with a recirculation loop is disclosed. Waste coating material form the roll coater is treated in an agitator unit containing, for example, one or more ultrasonic transducers, and optionally a filtration unit and/or temperature control unit to produce reconditioned coating solution, such as a reconditioned sol-gel precursor solution. Also disclosed is preventative maintenance module comprising a cleaning unit that is designed to engage and clean the applicator and/or metering rolls in a roll coater.

What is claimed is: 
     
         1 . A roll coater comprising:
 a metering roll;   an applicator roll,
 wherein the metering roll and the applicator roll create a gap between the metering roll and the applicator roll; 
   a reservoir in fluid communication with the gap;   a receptacle for receiving an excess fluid; and   a recirculation loop for receiving the excess fluid from the receptacle and for treating the excess fluid prior to returning the excess fluid into the reservoir,
 wherein the recirculation loop comprises an agitation device comprising an ultrasonic transducer for creating a phase interference in the excess fluid flowing through the recirculation loop. 
   
     
     
         2 . The roll coater of  claim 1 , wherein the recirculation loop further comprises a temperature control unit for controlling a temperature of the excess fluid flowing through the recirculation loop and from the agitation device. 
     
     
         3 . The roll coater of  claim 1 , wherein the recirculation loop further comprises a filtration unit for removing particulate matter from the excess fluid flowing through the recirculation loop. 
     
     
         4 . The roll coater of  claim 3 , wherein the filtration unit is positioned within the recirculation loop between the agitation device and a temperature control unit disposed downstream from the agitation device. 
     
     
         5 . The roll coater of  claim 1 , wherein the agitation device comprising an additional ultrasonic transducer. 
     
     
         6 . The roll coater of  claim 5 , wherein the ultrasonic transducer and the additional ultrasonic transducer are configured to have different operating frequency ranges. 
     
     
         7 . The roll coater of  claim 6 , wherein one of the operating frequency ranges is between 1 Hz and 500 Hz. 
     
     
         8 . The roll coater of  claim 6 , wherein one of the operating frequency ranges is between 100 Hz and 500 Hz. 
     
     
         9 . The roll coater of  claim 1 , wherein the recirculation loop comprises one or more peristaltic pumps for advancing the excess fluid flowing through the recirculation loop. 
     
     
         10 . The roll coater of  claim 1 , further comprising a cleaning unit, the cleaning unit comprising an engagement surface matching a surface of the applicator roll, the engagement surface comprising a plurality of rinsing holes and a plurality of suction holes. 
     
     
         11 . The roll coater of  claim 10 , wherein the cleaning unit is movable relative to the applicator roll to engage the surface of the applicator roll with the engagement surface of the cleaning unit. 
     
     
         12 . The roll coater of  claim 10 , wherein the plurality of rinsing holes is connected to a solvent supply, and wherein the plurality of suction holes is connected to a negative pressure source. 
     
     
         13 . The roll coater of  claim 10 , wherein the plurality of rinsing holes alternating with the plurality of suction holes. 
     
     
         14 . The roll coater of  claim 10 , wherein the engagement surface comprises a plurality of brushes positioned between the plurality of rinsing holes and the plurality of suction holes. 
     
     
         15 . The roll coater of  claim 14 , wherein the plurality of brushes comprises rotatable brushes. 
     
     
         16 . The roll coater of  claim 14 , wherein the plurality of brushes is electrically coupled to an electrical charge source for applying an electrostatic charge to the plurality of brushes. 
     
     
         17 . The roll coater of  claim 16 , wherein the electrical charge source is configured to apply different electrostatic charges to different ones of the plurality of brushes. 
     
     
         18 . The roll coater of  claim 14 , wherein the plurality of brushes are made from polytetrafluoroethylene (PTFE). 
     
     
         19 . The roll coater of  claim 1 , wherein the metering roll and the applicator roll are enclosed into a thermo-stabilization jacket. 
     
     
         20 . The roll coater of  claim 1 , further comprising a post-coating unit comprising at least one of a heat treatment device, an ultraviolet irradiation device, or an infrared irradiation device.