Patent Publication Number: US-2006005838-A1

Title: Multi-layer face mask with foamed in place edge member

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to face masks, and, in particular, facemasks formed from a plurality of layers and with the individual layers serving different functions and with a foamed edge member extending around the edge of the facemask.  
      2. Description of the Prior Art  
      In the prior art, facemasks have been constructed using a pair of flexible layers of fiberfill material and with a layer of filter material supported between the layers of fiberfill material. In the prior art facemasks, an edge portion of the facemask is heat sealed to form a line seal extending around the periphery of the mask and with this periphery line seal stiffening and sealing the edge portion of the facemask. In order to provide for the facemask of the prior art being sealed against the face of the wearer, a pair of elastic bands is attached to the facemask. The elastic bands extend around the head of the wearer so that the mask is pulled tightly against the face. The prior art facemasks also use a separate piece of foam rubber that is attached to the inner surface of the facemask and extend across the nose bridge portion of the mask. The piece of foam rubber provides for additional sealing of the mask in the nose bridge area. In addition, the prior art facemasks include a metal clip on the outside of the mask across the nose bridge portion, so that the wearer of the mask can bend the metal clip to maintain the foam rubber in sealing contact.  
      The prior art also includes the use of a molded rubber like edge bead as shown in Huber et al U.S. Pat. No. 4,454,881 which is assigned to the same assignee as the present application. This patent requires the use of high-pressure injection molding in a mold chamber formed by mold members to produce the molded rubber like edge bead. Such high-pressure injection molding is difficult to accomplish cleanly since the high-pressure will produce excess rubber like material extending onto the mask body in areas not perfectly sealed off by the mold members.  
      Generally, the masks of the prior art are uncomfortable to wear, since the mask is maintained very tightly against the face by the double bands and with the metal clip also squeezing the mask against the face in the nose bridge area. It will be appreciated that if the mask is uncomfortable to wear, there are times when workers will not wear the mask even though the use of a filter mask is indicated because of environmental conditions or fail to squeeze the metal noseband adequately.  
      The prior art masks with the molded rubber like edge bead are expensive to manufacture, and can produce uneven results, and can be uncomfortable for some wearers since, some wearers react to the rubber like material or find the rubber like material sticky, rigid and annoying.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a multi-layer facemask that is comfortable to wear and which seals to the face of the wearer without the necessity of tight elastic bands or metal clip members or rubber like material. Reference is made U.S. Pat. No. 4,454,881 listing Otto L. Huber and Mark Magidson as inventors, which Patent is assigned to the assignee of the present application that shows a multi-layer facemask wherein at least one layer is formed out of an open-work, flexible plastic material so as to serve as a support layer for carrying at least another layer of filter material. This Patent discloses the use of a peripheral molded rubber like edge bead and with this rubber like edge bead, providing for a sealing of the mask against the face of the wearer.  
      The present invention is directed to an improved multi-layer facemask using a foamed in place edge member foamed around at least a portion of the periphery of the mask to provide for sealing, by deformation of the foamed member, especially around the nose and upper cheek area of the facemask. Specifically, in the present invention, the foamed in place edge member may also include foamed flange portions extending inwardly at least in the nose and upper cheek area of the mask. The flange portions are deformable and flexible and lie against the sides of the nose and the cheekbones of the wearer. The flange portions extend inwardly to lie against the side of the nose and the cheekbones and since the flange portions are deformable and flexible, they adapt to the various facial contours even during facial movement such as during speech or change of facial expression. Additionally, the foam material may be hydrophilic to absorb moisture from the face of the wearer to thereby provide for an increase in the comfort level of the facemask.  
      As indicated above, the foamed in place deformable edge member, with the flange portions, may extend along the nose and upper cheek areas, but the flange portion may also extend around additional areas of the mask to provide for additional sealing around the periphery of the mask. In addition, since the foamed in place edge member is formed by a foaming technique, the present invention provides for foaming in place additional integral portions of the foamed edge member to extend further on the inside or outside of the mask to provide for additional functions. For example, portions of the foamed member may be foamed in place under low pressure to extend either on the inside or the outside surface around the nose area to provide for additional comfort and support in this area. The foamed member may be foamed in place to extend into the inside or outside surface of the mask along the sides of the mask so as to provide for side supports for strap members to hold the mask against the face. The foamed member may be foamed in place to extend on the inside or outside surface of the mask at a bottom portion to allow for the insertion of an exhalation valve.  
      With the facemask of the present invention, the pair of layers of non-woven material provide for a flexible shape-retaining carrier support for the filter material. The fiberfill layers allow for the generally unrestricted passage of air, which air is filtered by the intermediate filter layer. The layer of filter material may be of any of the general types of filter material commonly used in face masks for providing for the filtering of particular impurities in the air. Some of the filter materials currently used are not shape retaining or self-supporting, so it is necessary to use some sort of carrier means, such as the non-woven layers, to provide for the support of the filter material. It is to be appreciated, however, that in place of the non-woven layers an open-work layer of plastic material, such as shown in the previously referred to U.S. Pat. No. 4,454,881, may be used.  
      The filter material may be formed from various types of filter material such as electrostatically-charged woven or non-woven polyester or polypropylene fibers, fiberglass, activated charcoal impregnated sheets or particles, various types of natural fibers and other types of filter materials commonly used.  
      The foamed in place edge member may be formed from any compressible resilient foam polymer with either fast or slow recovery properties such as polyurethane or polyvinyl chloride. Typical chemical systems are made up of two liquid components. When the components are mixed together, this causes a chemical reaction that creates a soft foam material under low pressure that gradually becomes the solid foam edge member. The initial exposure to the mask occurs when the material is substantially in liquid form and the bond between the mask body and edge member can be very strong since, when in the liquid state, the material can intermingle with the fibers forming the mask body. A cure time under low pressure of approximately 10 minutes or less is preferable.  
    
    
     BRIEF DESCRIPTION OF INVENTION  
       FIG. 1  is a front view of a first embodiment of a facemask constructed in accordance with the teachings of the present invention having a foamed in place deformable edge member extending around the periphery of the facemask.  
       FIG. 2  is a cross sectional view of the facemask of  FIG. 1  taken along lines  2 - 2  of  FIG. 1  and includes a fragmentary view of the layers forming the mask body.  
       FIG. 3  is a cross sectional view of the facemask of  FIG. 1  taken along lines  3 - 3  of  FIG. 1 .  
       FIG. 4  is a front view of a second embodiment of a facemask constructed in accordance with the teachings of the present invention having a foamed in place deformable edge member extending around the periphery of the facemask and with flange portions at least in particular areas.  
       FIG. 5  is a cross sectional view of the facemask of  FIG. 4  taken along lines  5 - 5  of  FIG. 4 .  
       FIG. 6  is a cross sectional view of the facemask of  FIG. 4  taken along lines  6 - 6  of  FIG. 4 .  
       FIG. 7  is a front view of a third embodiment of a facemask constructed in accordance with the teachings of the present invention having a foamed in place deformable edge member with flange portion extending around the periphery of the facemask.  
       FIG. 8  is a cross sectional view of the facemask of  FIG. 7  taken along lines  8 - 8  of  FIG. 7 .  
       FIG. 9  is a cross sectional view of the facemask of  FIG. 7  taken along lines  9 - 9  of  FIG. 7 .  
       FIG. 10  is a front view of a fourth embodiment of a facemask constructed in accordance with the teachings of the present invention having a foamed in place deformable edge member extending in the nose area of the facemask.  
       FIG. 11  is a cross sectional view of the facemask of  FIG. 10  taken along lines  11 - 11  of  FIG. 10 .  
       FIG. 12  is a cross sectional view of the facemask of  FIG. 10  taken along lines  12 - 12  of  FIG. 10 .  
       FIG. 13  illustrates an exploded view of a mold structure used in a method of producing the present invention for foaming in place the deformable edge member around the periphery of the mask. 
    
    
       FIGS. 1 through 3  illustrates a first embodiment of a facemask  10  of the present invention, which facemask is formed from three layers of material. Specifically, the facemask  10  includes an outer flexible layer  12  which may be formed as a fiberfill shell. The outer shell  12  may be molded using non-woven polyester fibers and the shell serves as an outer support layer and pre-filter. An inner flexible layer  14  may also be formed as a fiberfill shell and may also be molded using non-woven polyester fibers. The layers  12  and  14  may not have the exact characteristics, and, as an example, the outer layer  12  may be formed of larger fibers than the inner layer  14  so that the inner layer, by being formed of finer fibers, may have a softer and therefore more comfortable surface to lie against the face of the wearer.  
      The inner and outer layers  12  and  14  are used to sandwich a middle layer  16  of filter material. This filter material may be formed of any known type of filter material so as to provide for filtering of particular elements in the air. For example, the following type of filter material has been used to provide for filtering but it is to be appreciated that other filter material may be used; activated charcoal-treated sheets or sheets formed from charcoal particles, fiberglass material, electrostatic material such as made from fine denier non-woven polyethylene or polypropylene fibers or natural materials. The present invention contemplates using any of these known types of filtering material for the center layer  16  sandwiched and supported by the outer layers  12  and  14 .  
      The present invention also incorporates a foamed in place deformable edge member  18  of deformable foam material extending around the peripheral edge of the facemask  10 . Specifically, as shown in  FIGS. 2 and 3  the three layers  12 ,  14  and  16  are sealed together around the periphery and an edge member  18  is located around the sealed periphery of the facemask since the edge member  18  is foamed in place around the peripheral portion of the layers. The foamed in place edge member may be formed from any compressible resilient foam polymer with either fast or slow recovery properties such as polyurethane or polyvinyl.  
      The foamed in place deformable edge member  18  is foamed to at least include areas  20  and  22  which areas extend inwardly in the nose bridge and cheekbone areas of the mask  10 .  FIGS. 10-12  illustrate a fourth embodiment of the invention wherein the foamed in place deformable edge member is located only in selected areas such as in the areas  20  and  22  so as to extend inwardly in the nose bridge and cheekbone areas of the mask  10 . The embodiment of  FIGS. 10-12  also include the use of the foamed in place deformable edge member in areas  24  and  26  to accept a strap  28  and in area  30  to support an exhalation valve  32 . The exhalation valve  32  allows for a freer passage of air exhaled by the wearer of the mask.  
       FIGS. 4 through 6  illustrate a second embodiment of the invention similar to the first embodiment but additionally including foamed in place flange portions  34  and  36  formed at an angle relative to the three layers  12 ,  14  and  16  and the edge member  18 . This may be clearly seen with reference to  FIGS. 4 and 5 . The flange portions  34  and  36  are relatively thin and deformable and relatively soft to thereby deform and bend easily. The flange portions  34  and  36  therefore provide for a deformable and flexible surface to conform to the facial contours of the wearer and thereby produce an additional sealing of the mask against the face of the wearer along the sides and nose bridge of the nose and the upper cheekbone portions. The foamed in place deformable edge member  18  itself provides for sealing of the mask against the face of the wearer and the flange portions  34  and  36  provide for additional sealing in the critical area around and along the sides of the nose and along the upper cheekbones to accommodate facial contours of varying characteristics. The additional flange portions  34  and  36  may also be incorporated into the fourth embodiment of  FIGS. 10-12  so as to provide for additional sealing in the nose area of the face of a wearer of the facemask.  
      The embodiment of  FIGS. 4 through 6  also includes a flange portion  38  in the chin area of the facemask  10  to provide for additional sealing in the critical area around and along the sides of the chin to accommodate facial contours of varying characteristics.  
       FIGS. 7 through 9  illustrates a third embodiment of the invention. In this third embodiment the foamed in place deformable edge member  18  includes a flexible and deformable flange portion  40  extending completely around the inner surface of the facemask. The flange portion  40  therefore provides for the additional flange sealing, not only in the nose bridge and chin areas but also extending completely around the periphery of the facemask.  
      All of the embodiments of the invention may include additional integral molded portions in the body of the facemask to provide for additional support in the nose bridge and cheek area. As shown in drawings the facemask includes an integral molded area  42 , which extends over the nose bridge portion of the mask so as to provide for an additional resilient support for the nose bridge portion of the mask. In particular, the area  42  may be molded so that the nose bridge portion has a relatively narrow configuration that would become spread apart as the mask is placed on the face of the wearer. The area  42  therefore acts as a resilient, springy support surface to tend to maintain the nose bridge portion of the foamed in place deformable edge member  18  in contact with the face of the wearer. In addition, the area  42  may form flat pad portions on each side of the nose to receive and support nosepiece portions of eyeglasses to prevent the glasses from sliding forward.  
      It is to be appreciated that any of the embodiments of the facemask may have at least one of the inner or outer support layers is formed from open-work plastic as shown by open-work plastic  44  in the third embodiment of  FIGS. 7 through 9 . This open work plastic would be similar to that shown in U.S. Pat. No. 4,454,881 referred to earlier. It is also to be appreciated that the facemask may also be formed of soft material to have a flat configuration and with the facemask wrapped across the face of the wearer. A foamed in place edge member may be provided with such a mask to accomplish the purposes of the present invention.  
       FIG. 13  through  15  illustrates structure for providing for the foaming in place the edge member of any of the embodiments of the facemask  10  of the present invention. In particular,  FIG. 13  illustrates the foaming in place of the edge member to the facemask  10  with an additional flange extending around the periphery of the edge member and with additional flange portions in the nose bridge and chin areas. This would be a combination of the second and third embodiment of the present invention.  
      As can be seen in  FIG. 13  male and female mold members  50  and  52  include surfaces conforming to the desired shape of the face mask  10  and a void  54  that extends around the periphery of the mold members. The inner and outer support layers  12  and  14  and the filter material  16  may be precut to the desired configuration and then edge sealed in the mold members  50  and  52 . Alternatively, the three layers  12 ,  14  and  16  may be preformed to the desired edge seal and then placed between the mold members  50  and  52 . In either case, the edge portion of the layers forming the mask  10  is positioned within the opening between the mold members so as to receive the foamed in place deformable edge member  18 .  
      The void  54  is filled with foamable material  58  using nozzles  56  and the mold members are closed so the foamable material foams in place at low pressure only in the void  54  and attaches by adhesion to the periphery of the face mask to form the various embodiments of the invention dependent upon the specific structure of the mold members  50  and  52 . The foaming occurs under low pressure since the mold members are used only to contain the foamable material within the void  54  and the pressure is limited to the pressure produced by the foaming action of the foamable material.  
      As can be seen in  FIG. 13 , the opening between the mold members  50  and  52  have a configuration so as to form the foamed in place deformable edge member  18  and to also integrally form the flange portions  34  and  36  as shown in  FIG. 4  and the flange portion  40  as shown in  FIG. 7 . The mask  10  formed by the mold members  50  and  52 , therefore, includes the layers of support material and the intermediate filter layer and additionally include the foamed in place deformable edge member  18  extending around the periphery of the mask and with the additionally integrally molded flexible and deformable flange portions  34 ,  36  and  40 .  
      Also, the mold members  50  and  52  and the void area  54  may have an internal configuration to provide for any of the additional low pressure foamed in place deformable surfaces and portions as shown by any of the embodiments of the invention.  
      The foamed in place edge member  18  and any additional foam portions may be formed from any compressible resilient foam polymer with either fast or slow recovery properties such as polyurethane or polyvinyl chloride. Typical chemical systems are made up of two liquid components. When the components are mixed together, they cause a chemical reaction that creates a soft foam material that gradually becomes the solid foam edge member. The initial exposure to the mask occurs when the material is in liquid form and the bond between the mask body and edge member can be very strong since, when in the liquid state, the material can intermingle with the fibers forming the mask body. A cure time of approximately 10 minutes or less is preferable.  
      It will be appreciated that in addition to the particular embodiments of the invention shown, other adaptations and modifications may be made and the invention is only to be limited by the appended claims.