Method and apparatus for selectively curing a sheet of EPDM material

Abstract

A method and apparatus for selectively curing a sheet of ethylene-propylene diene termonomer (EPDM) material to form a roofing membrane for installation on a roof deck. The method includes the steps of providing a sheet formed of ethylene-propylene diene termonomer, the sheet having a field and longitudinal edge areas bordering the field; and then simultaneously shielding at least one edge area of the EPDM sheet and exposing at least the field to a source of radiation to cure at least the field of the EPDM sheet and provide a selectively cured EPDM roofing membrane. Also disclosed is the product formed by the method of the present invention.

What is claimed is:  
     
         1 . A method for selectively curing a sheet of ethylene-propylene diene termonomer (EPDM) material to form a roofing membrane for installation on a roof deck comprising the steps of: 
 providing a sheet formed of ethylene-propylene diene ternonomer, the sheet having a field and two longitudinal edge areas bordering the field; and    simultaneously shielding at least one edge area of the EPDM sheet and exposing at least the field to a source of radiation to cure at least the field of the EPDM sheet and provide a selectively cured EPDM roofing membrane.    
     
     
         2 . The method of    claim 1    wherein the sheet is provided by milling, calendering or extrusion.  
     
     
         3 . The method of    claim 1    wherein the sheet is from 5 to 200 mils thick.  
     
     
         4 . The method of    claim 1    wherein two longitudinal edge areas of the EPDM sheet are shielded.  
     
     
         5 . The method of    claim 1    wherein the at least one longitudinal edge area of the EPDM sheet is shielded by operatively projecting at least one screen over the at least one longitudinal edge area of the sheet and shield the edge area of the sheet of EPDM.  
     
     
         6 . The method of    claim 1    wherein two longitudinal edge areas of the EPDM sheet are shielded by operatively projecting a screen over each longitudinal edge area of the sheet thereby shielding the edge area of the sheet of EPDM.  
     
     
         7 . The method of    claim 1    wherein the source of radiation is infrared radiation.  
     
     
         8 . An apparatus for selectively curing a sheet of ethylene-propylene diene termonomer (EPDM) material, the sheet having a field and longitudinal edge areas bordering the field, the apparatus comprising: 
 a curing oven having a roof and a floor interconnected by sidewalls, a front end and a back end, the front end including an entrance and the back end including an exit, a conveyor positioned between the front end and the back end of the curing oven for continuously conveying the sheet of EPDM through the curing oven;    a radiation source located above the conveyor within the curing oven; and    at least one screen operatively projecting from each sidewall of the curing oven and extending the longitudinal length of the curing oven to cover at least one edge area of the sheet and shield the edge area of the sheet of EPDM as the sheet passes through the curing oven under the radiation source.    
     
     
         9 . The apparatus of    claim 8    wherein the screen is a flat, rectangular shape radiation reflective material.  
     
     
         10 . The apparatus of    claim 8    wherein the curing oven includes an actuating member to operatively position the screen between an extended position over the edge area of the sheet of EPDM to a retracted position.  
     
     
         11 . The apparatus of    claim 10    wherein the actuating member includes a piston member and an arm attached to the screen.  
     
     
         12 . The apparatus of    claim 8    wherein the radiation source provides a desired dose of high-energy radiation to cure at least the exposed field of the sheet of EPDM.  
     
     
         13 . The apparatus of    claim 12    wherein the radiation source is selected from infrared radiation, gamma rays, x-rays, or beta rays.  
     
     
         14 . The apparatus of    claim 12    wherein the radiation source includes an array of infrared heat lamps positioned above the conveyor within the curing oven.  
     
     
         15 . A method of joining selectively cured sheets of EPDM membrane comprising the steps of: 
 providing at least two sheets formed of ethylene-propylene diene termonomer, the sheets having a field defined by a cured planar surface portion and a noncured longitudinal edge area bordering the field defined by the extent of overlap of adjacent roofing membranes when installed on a roof deck; and then    overlapping and pressing the noncured edge areas of two EPDM roofing membranes together and then vulcanizing the edge areas to splice the edge areas together.    
     
     
         16 . A roofing membrane comprising: 
 a sheet formed of ethylene-propylene diene termonomer (EPDM) material, the sheet having a field defined by a cured planar surface portion and a noncured longitudinal edge area bordering the field and defined by the extent of overlap of adjacent roofing membranes when installed on a roof deck.