Method Of Making A Filtering Face Mask Having New Exhalation Valve

Abstract

A method of making a filtering face mask, which method comprises: (a) providing a mask body that is adapted to fit over the nose and mouth of a person, the mask body comprising a filtration layer and having an opening through which exhaled air can pass without having to pass through the filtration layer, the opening being located directly in front of where the wearer's mouth would be when the face mask is being worn; and (b) attaching an exhalation valve to the mask body at the opening; wherein the attached exhalation valve comprises: (i) only one flexible flap that has only one stationary portion, only one free portion, a generally uniform thickness, and a peripheral edge, the peripheral edge having a stationary segment that is associated with the one stationary portion and a free segment that is associated with the one free portion; and (ii) a valve seat that has a flap-retaining surface, a seal surface, and an orifice that comprises a plurality of openings through which plurality of openings exhaled air may pass to lift the free portion of the flexible flap away from the seal surface during an exhalation, the flexible flap being attached to the valve seat at the flap-retaining surface and making contact with the seal surface when the flap is in its closed position such that the one free portion of the only one flap exhibits a curvature over the orifice area when viewed from a side elevation in the closed position and such that a bias is created that enables the only one flexible flap to provide a leak-free seal to the seal surface under any orientation of the valve; the flap-retaining surface being located above the plurality of openings when the filtering face mask is viewed from the front in an upright position ( FIG. 1 ), the flexible flap being held at the flap-retaining surface to create the stationary portion of the flap.

1 . A method of making a filtering face mask, which method comprises: 
 (a) providing a mask body that is adapted to fit over the nose and mouth of a person, the mask body comprising a filtration layer and having an opening through which exhaled air can pass without having to pass through the filtration layer, the opening being located directly in front of where the wearer's mouth would be when the face mask is being worn; and    (b)) attaching an exhalation valve to the mask body at the opening;    wherein the attached exhalation valve comprises: 
 (i) only one flexible flap that has only one stationary portion, only one free portion, a generally uniform thickness, and a peripheral edge, the peripheral, edge having a stationary segment that is associated with the one stationary portion and a free segment that is associated with the one the portion; and  
 (ii) a valve seat that has a flap-retaining surface, a seal surface, and an orifice that comprises a plurality of openings through which plurality of openings exhaled air passes to lift the free portion of the flexible flap away from the seal surface during an exhalation, the flexible flap being attached to the valve seat at the flap-retaining surface and making contact with the seal surface when the flap is in its closed position such that the one free portion of the only one flap exhibits a curvature over the orifice area when viewed from a side elevation in the closed position and such that a bias is created that enables the only one free portion of the flexible flap to reside in the closed position under any orientation of the valve when a fluid is not passing through the orifice;  
 the flap-retaining surface being located above the plurality of openings when the filtering face mask is viewed from the front in an upright position ( FIG. 1 ) the flexible flap being held at the flap-retaining surface to create the stationary portion of the flap.  
   
   
   
       2 . The method of  claim 1 , further comprising: 
 providing the exhalation valve with a valve cover that has fluid impermeable sidewalls, a fluid impermeable ceiling, and an opening for permitting exhaled air to pass therethrough, the arrangement of the sidewalls, ceiling, and valve cover opening on the valve with respect to the mask body being such that: (i) the ceiling is higher above the free segment of the flap than above the stationary segment, (ii) the path traced by the free segment is approximately parallel to the valve cover opening, and (iii) exhaled air would be directed in a downwardly direction when the mask is worn and the wearer is exhaling.    
   
   
       3 . The method of  claim 2 , wherein the valve cover comprises a surface that holds the flexible flap against the flap-retaining surface.  
   
   
       4 . The method of  claim 1 , further comprising: 
 providing a valve cover that comprises a surface that holds the flexible flap against the flap-retaining surface.    
   
   
       5 . The method of  claim 4 , wherein the flap-retaining surface is spaced from the seal surface and is located closer to the seal surface at the stationary segment of the peripheral edge of the flap than at the free segment of the peripheral edge.  
   
   
       6 . The method of  claim 1 , wherein the flexible flap comprises crosslinked polyisoprene.  
   
   
       7 . The method of  claim 1 , wherein the free portion of the flexible flap has a profile that comprises a curve when viewed from the front, which curve corresponds to the general shape of the seal surface that contacts the free portion of the flap when the valve is in the closed position.  
   
   
       8 . The method of  claim 1  , wherein the valve is positioned on the mask body such that the exhaled air only exits the mask downwardly away from the wearer's eyes when the mask is donned and the wearer is exhaling.  
   
   
       9 . The method of  claim 1 , wherein the area of the opening in the valve cover is greater than the area of the plurality of openings located below the flap-retaining surface of the valve seat.  
   
   
       10 . The method of  claim 9 , wherein the area encompassed by the plurality of openings is 2 to 6 cm 2 .  
   
   
       11 . The method of  claim 1 , wherein the flap-retaining surface is located outside of the area defined by the plurality of openings through which exhaled air passes to lift the free portion of the flexible flap away from the seal surface.  
   
   
       12 . A method of making a filtering face mask, which method comprises: 
 (a) providing a mask body that is adapted to fit over the nose and mouth of a person, the mask body comprising a filtration layer and having an opening through which exhaled air can pass without having to pass through the filtration layer, the opening being located directly in front of where the wearer's mouth would be when the face mask is being worn; and    (b) attaching an exhalation valve to the mask body at the opening;    wherein the attached exhalation valve comprises: 
 (i) only one flexible flap that has only one stationary portion, only one free portion, a generally uniform thickness, and a peripheral edge, the peripheral edge having a station, segment that is associated with the one stationary, portion and a free segment that is associated with the one free portion; and  
 (ii) a valve seat that has a flap-retaining surface, a seal surface, and an orifice that comprises a plurality of openings through which plurality of openings exhaled air may pass to lift the free portion of the flexible flap away from the seal surface during an exhalation, the flexible flap being attached to the valve seat at the flap-retaining surface and making contact with the seat surface when the flap is in its closed position such that the one free portion of the only one flap exhibits a curvature over the orifice area when viewed from a side elevation in the closed position and such that a bias is created that enables the only one flexible flap to be pressed in an abutting relationship with the seal surface under any orientation of the valve when a fluid is not passing through the orifice; the flap-retaining surface being located above the plurality of openings when the filtering face mask is viewed from the front in an upright position ( FIG. 1 ), the flexible flap being held at the flap-retaining surface to create the stationary portion of the flap, and wherein the flap-retaining surface and the plurality of openings are distanced from each other to enable the flap to be pressed towards the seal surface to create a substantially uniform seal when the valve is in a closed position.  
   
   
   
       13 . The method of  claim 12 , wherein the flap-retaining surface is planar and the flap is held in an abutting relationship to the flap-retaining surface.  
   
   
       14 . The method of  claim 13 , further comprising providing a valve cover that comprises a surface that holds the flexible flap in an abutting relationship to the flap-retaining surface.