Fibrous substrate treatment method and machine for implementing the method

Abstract

A method for treating a fibre substrate, including the steps of feeding a substrate along a feed path, stretching the substrate longitudinally to reduce the thickness of the substrate to a value less than 1 mm and then treating the substrate with plasma at atmospheric pressure at a treatment station (T) located.

1 . A fibre substrate treatment method, comprising the steps of:
 feeding a substrate along a feed path;   treating the substrate with plasma at atmospheric pressure at a treatment station located on the feed path;   wherein it comprises, along the feed path and before the treatment with plasma at atmospheric pressure, a step of reducing the substrate in thickness until the substrate reaches a predetermined thickness.   
     
     
         2 . The method according to  claim 1 , wherein the step of reducing the substrate in thickness is performed until the substrate has a final thickness of between 0.05 mm and 1 mm, preferably between 0.1 mm and 0.5 mm. 
     
     
         3 . The method according to  claim 1 , wherein the step of reducing the substrate in thickness is accomplished by stretching the substrate longitudinally along the feed path. 
     
     
         4 . The method according to  claim 3 , wherein the step of stretching the substrate longitudinally is performed until applying to the substrate a final stretch factor of between 1.5 and 10. 
     
     
         5 . The method according to  claim 3 , wherein the step of treating the substrate with ionized gases and/or plasma at atmospheric pressure is accomplished by feeding the substrate between two opposite arrays of rollers, the arrays being longitudinally offset in such a way that the feed path, defined by the rollers, is made to follow an undulatory course, each roller of one of the arrays being operatively coupled to a corresponding roller of the other array to define a respective treatment zone. 
     
     
         6 . The method according to  claim 5 , wherein each pair of rollers defining a respective treatment zone is configured in such a way as to form, between the two rollers, a gap through which the substrate is fed, and wherein the step of reducing the substrate in thickness is performed until the substrate is reduced to a final thickness which is less than a minimum thickness of the gap between the rollers. 
     
     
         7 . The method according to  claim 5 , wherein the step of treating the substrate with ionized gases and/or plasma at atmospheric pressure is accomplished by keeping the substrate in a configuration of constant thickness along the feed path within the treatment station. 
     
     
         8 . The method according to  claim 5 , wherein the step of treating the substrate with plasma at atmospheric pressure is accomplished without subjecting the substrate to further longitudinal stretching. 
     
     
         9 . A fibre substrate treatment machine, comprising:
 means for feeding a substrate along a feed path;   a treatment station located on the feed path and designed for treating the substrate with plasma at atmospheric pressure;   
       wherein it comprises a preparation station, located upstream of the treatment station on the feed path and configured to reduce the thickness of the substrate to a predetermined thickness. 
     
     
         10 . The machine according to  claim 9 , wherein the preparation station comprises stretching means configured to stretch the substrate longitudinally along the feed path. 
     
     
         11 . The machine according to  claim 10 , wherein the stretching means comprise at least two pairs of rollers located in succession along the feed path, a first of the pairs of rollers being located upstream of the second pair of rollers and having a tangential speed which is less than that of the second pair of rollers. 
     
     
         12 . The machine according to  claims 9 , wherein the treatment station comprises two opposite arrays of rollers, the arrays being longitudinally offset in such a way that the feed path, defined by the rollers, is made to follow an undulatory course, and wherein the rollers of one of the arrays and the rollers of the other array mutually interconnected in pairs to define respective treatment zones. 
     
     
         13 . The machine according to  claim 12 , wherein the rollers of each pair of rollers are spaced from each other to define a gap of minimum width between 0.3 mm and 3.0 mm, preferably between 0.4 mm and 0.8 mm.