Method for reducing peel defects in adhesive bonded plastics

Abstract

A method for producing a processed polymeric sheet to be adhesively secured to a cover to form a seal, the sheet having properties such that the seal does not have branching peel defects when it is separated. A polymeric sheet is formed from a source of polymeric material, and at least one side of the polymeric sheet is coated with silicone. The polymeric sheet is further processed while implementing a static neutralization method to substantially eliminate electrostatic discharge across the polymeric sheet during such further fabrication, producing a processed polymeric sheet. Preferably the polymeric material is selected from the group consisting of polyethylene, polystyrene, polyester, polyvinyl chloride, polypropylene, acrylics, acrylonitrile, polycarbonates, polyimide, and cellulosics. The static neutralization method, in different preferred embodiments, may be impregnating the polymeric source with a conductive material to dissipate a static charge on the polymeric sheet, coating the polymeric sheet with a hygroscopic material to attract moisture and dissipate a static charge on the polymeric sheet, at least partially ionizing an air mass and passing the polymeric sheet through the air mass to neutralize a static charge on the polymeric sheet, or passing the polymeric sheet near static neutralization bars to neutralize a static charge on the polymeric sheet.

What is claimed is: 
     
       1. A method for producing a processed polymeric sheet to be adhesively secured to a surface to form a seal, comprising: forming a polymeric sheet from a source of polymeric material, coating at least one side of the polymeric sheet with silicone, and thereafter processing the polymeric sheet while implementing a static neutralization method at a source of electrostatic charge accumulation to prevent an electrostatic charge accumulation of greater than 3000 volts across the polymeric sheet during processing, thereby producing a processed polymeric sheet that is resistant to peel defects when the processed polymeric sheet is adhesively secured to a surface and then peeled from the surface;   whereby the processed polymeric sheet is resistant to peel defects by the prevention of the electrostatic charge accumulation at the source of accumulation during processing.   
     
     
       2. The method of claim 1 wherein implementing the static neutralization method comprises impregnating the source of polymeric material with a sufficient quantity of conductive material to prevent electrostatic accumulation of greater than 3000 volts on the polymeric sheet. 
     
     
       3. The method of claim 1 wherein implementing the static neutralization method comprises coating the polymeric sheet with a sufficient quantity of hygroscopic material to attract moisture and prevent electrostatic accumulation of greater than 3000 volts on the polymeric sheet. 
     
     
       4. The method of claim 1 wherein implementing the static neutralization method comprises at least partially ionizing an air mass and passing the polymeric sheet through the air mass whereby electrostatic charge accumulation across the polymeric sheet is neutralized at the source of accumulation. 
     
     
       5. The method of claim 1 wherein implementing the static neutralization method comprises passing the polymeric sheet near static neutralization bars to prevent electrostatic accumulation of greater than 3000 volts on the polymeric sheet. 
     
     
       6. A method for producing a processed polymeric sheet to be adhesively secured to a cover to form a seal, the processed polymeric sheet having properties such that the seal is resistant to branching peel defects when the seal is separated, comprising: extruding glycol modified polyester from a source of glycol modified polyester to produce a polymeric sheet, coating one side of the polymeric sheet with silicone, and thereafter passing the polymeric sheet through an at least partially ionized air mass at a source of electrostatic charge accumulation of the polymeric sheet to prevent an electrostatic charge accumulation of greater than 3000 volts on the polymeric sheet; whereby a processed polymeric sheet, having electrostatic charge accumulation of below about 3000 volts after application of silicone, is produced that has a seal resistant to branching peel defects when the processed polymeric sheet is adhesively secured to a cover and then peeled from the cover.   
     
     
       7. A method for fabricating packaging material for sterile items, the packaging material having a reduced number of branching peel defects, comprising the steps of: (a) extruding a polymeric sheet,   (b) drawing the polymeric sheet through a first series of rollers, the first series of rollers acting to set physical characteristics of the polymeric sheet,   (c) coating at least one side of the polymeric sheet with silicone,   (d) drawing the coated polymeric sheet through a second series of rollers,   (e) winding the polymeric sheet onto a spool, and   (f) implementing a static neutralization method at steps (d) and (e) to prevent an electrostatic charge accumulation of greater than 3000 volts across the polymeric sheet by neutralizing any charge accumulation occurring at contact between the coated polymeric sheet and the second series of rollers and between the coated polymeric sheet and the spool.   
     
     
       8. A method for fabricating packaging material for sterile items, the packaging material having no branching peel defects, comprising the steps of: (a) extruding glycol modified polyester into a polymeric sheet,   (b) drawing the polymeric sheet through a first series of rollers, the first series of rollers acting to set physical characteristics of the polymeric sheet,   (c) coating at least one side of the polymeric sheet with silicone,   (d) drawing the coated polymeric sheet through a second series of rollers,   (e) winding the polymeric sheet onto a spool, and   (f) implementing a static neutralization method at steps (d) and (e) to prevent an electrostatic charge accumulation of greater than 3000 volts across the polymeric sheet by neutralizing any charge accumulation occurring at contact between the coated polymeric sheet and the second series of rollers and between the coated polymeric sheet and the spool.