Patent Publication Number: US-2023144471-A1

Title: Mask arranged to flex about median plane

Description:
BACKGROUND 
     A mask may cover the nose and mouth of a wearer in order to protect the wearer from potential contaminants in the air. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a front view of an example mask; 
         FIG.  2    is a rear view of the mask; 
         FIG.  3    is a side view of the mask; 
         FIG.  4    is a cross-sectional view through the mask; 
         FIG.  5    is a plan view of the mask worn on different wearers; and 
         FIG.  6    is a flowchart of an example method for manufacturing the mask. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS.  1  to  4    show an example of a mask  10 . The mask  10  comprises a mask body  20 , a cushion  30 , a pair of filter units  40 , and attachments  50 . 
     The mask body  20  is generally cup shaped and is intended to cover the nose and mouth of a wearer of the mask. The mask body  20  defines an internal cavity  21  into which the nose and mouth of the wearer are received. The mask body is formed of a compliant elastomeric material, such as a thermoplastic polyurethane (TPU). As described below, the mask body is shaped so as to flex about a median plane  22  when the mask  10  is worn by the wearer. 
     The cushion  30  is secured to and depends inwardly from the periphery of the mask body  20 . The cushion  30  provides a seal against the face of the wearer and comprises an opening  31  through which the nose and mouth of the wearer pass. Like that of the mask body  20 , the cushion  30  is formed of a compliant elastomeric material. In one example, the mask body  20  and the cushion  30  may be formed from the same material in the same process to create an integral article. 
     The filter units  40  are provided on opposite sides of the mask body  20  on either side of the median plane  22 . Each filter unit  40  comprises, in an assembled configuration, a filter port  60 , a filter medium  70 , and a retainer  80 . 
     The filter port  60  forms an opening in the mask body  20 , and comprises a base  61  and a side wall  62 . The base  61  and side wall  62  collectively define a recess  63  within which the filter medium  70  and the retainer  80  are removably received. The base  61  serves to support the filter medium  70  and comprises an annular ridge  65  and plurality of openings  66 . The side wall  62  comprises an annular groove  68  into which the retainer  80  is removably seated. 
     The retainer  80  comprises an annular ring  81  and a tab  82 . When seated within the groove  68  of the filter port  60 , the annular ring  81  of the retainer  80  and the annular ridge  65  of the base  61  cooperate to sealingly engage the filter medium  70 . The retainer  80  has a relatively large open area. As a result, the retainer  80  retains the filter medium  70  within the filter port  60  without unduly restricting the flow of air through the filter medium  70 . 
     The filter medium  70  is removable from the filter port  60  for cleaning and/or replacement. In order to remove the filter medium  70 , the retainer  80  is first removed from the filter port  60  by grasping and pulling the tab  82 , after which the filter medium  70  may be removed. The particular choice of filter medium  70  (e.g. material and grade) may be selected according to the intended use of the mask  10 . In one example, the filter medium may comprise a non-woven polypropylene fabric. However, other filter media suitable for respiratory filtering may be used, such as polyester, nylon, cellulose or cotton. 
     The filter port  60  may be formed of a compliant elastomeric material. Furthermore, the groove  68  in the side wall  62  of the filter port  60  may be sized such that, when the retainer  80  is seated within the groove  68 , the side wall  62  biases the retainer  80  downwards towards the filter medium  70  and base  61 . As a result, an effective seal may be formed between the filter port  60 , the filter medium  70 , and the retainer  80 . 
     The retainer  80  may be formed of a compliant elastomeric material. This may then make insertion and removal of the retainer  80  easier. For example, the retainer  80  may be squeezed during insertion in order to fit the annular ring  81  within the groove  68 . 
     Each filter unit  40  provides for both inhalation and exhalation. In particular, air inhaled by the wearer is drawn through the filter medium  70 , through the openings  66  in the base  61  of the filter port  60 , and into the internal cavity  21  of the mask body  20 . Air exhaled by the wearer into the internal cavity  21  of the mask body  20  is expelled through the openings  66  in the base  61  of the filter port  60 , and through the filter medium  70 . The mask  10  therefore provides for filtration of both inhaled and exhaled air. 
     Attachments  50  are provided on both sides of the mask  10  for attaching a harness (not shown) to the mask  10 . The attachments  50  are provided on the filter ports  60  and may be integrally formed with the filter ports  60 . The attachments  50  take the form of loops through which straps of the harness may be inserted. However, other forms of attachment are possible. The mask  10  comprises a pair of attachments  50  on each side of the mask  10 . This then enables the mask  10  to be used with a harness having upper and lower straps to more firmly secure the mask to the head of the wearer. Alternatively, the mask  10  may be used with a harness having left and right straps for securing around the ears of the wearer. The mask  10  may nevertheless comprise a fewer or greater number of attachments. 
     The mask body  20  is formed of a compliant, elastomeric material and is shaped such that, when the mask  10  is worn by the wearer, the mask body  20  may flex about a median plane  22  of the mask body  20 . 
       FIG.  5    illustrates the mask  10  when worn by a wearer  90  having (a) a long/narrow facial profile, (b) a medium facial profile, and (c) a short/wide facial profile, as set out in international standard ISO/TS 16976-2. When the mask  10  is placed against the face of a wearer  90  having a medium facial profile, little or no flex in the mask body  20  occurs. However, when the mask  10  is placed against the face of a wearer  90  having a long/narrow profile, and tension is applied to the sides of the mask  10  (e.g. by the harness), the two sides of the mask body  20  flex inwards about the median plane  22 . Conversely, when the mask  10  is placed against the face of a wearer  90  having a short/wide profile, the two sides of the mask body  20  flex outwards about the median plane  22 . The mask body  20  therefore flexes about the median plane by different amounts or angles when worn by wearers having different facial profiles. By flexing about the median plane  22  in response to changes in the facial shape or profile of the wearer  90 , the cushion  30  is able to better conform to the shape of the face and thus a more effective seal may be formed between the mask  10  and the wearer  90 . The flexion of the mask body  20  in conjunction with the deformation of the cushion  30  enables a single design of mask  10  to fit a wide range of face profiles, thereby providing a good level of sealing between the mask  10  and wearer  90 . 
     The filter ports  60  are generally stiffer than the mask body  20  owing to their geometry, even when formed of the same elastomeric material as that of the mask body  20 . By providing the filter ports  60  on opposites sides of the mask body  20  (i.e. on opposite sides of the median plane  22 ), the filter ports  60  provide increased stiffness to the sides of the mask body  20 . As a result, when tension is applied to the sides of the mask  20  (e.g. by the harness), the mask body  20  is more likely to flex about the median plane  22 . 
     The attachments  50  are provided on the filter ports  60  but could alternatively be provided on the mask body  20 . If the attachments  50  are provided on the mask body  20 , the tension created by the harness may cause the mask body  20  to deform locally and pull the cushion  30  away from the wearer&#39;s face. The filter ports  60 , as already noted, are generally stiffer than the mask body  20 . Accordingly, by providing the attachments  50  on the filter ports  60 , the tension applied to the mask  10  by the harness is less likely to pull the cushion  30  away the from the face of the wearer. 
     The mask  10  comprises a pair of filter units  40 , each of which provides for both inhalation and exhalation. By providing two filter units  40 , a relatively large filter area may be achieved through which the wearer is able to inhale and exhale. As a result, breathing may be made easier, i.e. less restrictive. Nevertheless, the mask  10  may comprise a single (potentially larger) filter unit on one side of the mask body  20 . The single filter unit may again provide for both inhalation and exhalation. Alternatively, the filter unit may provide for just one of inhalation and exhalation, and the mask  10  may comprise a one-way valve (perhaps seated within the other filter port) to provide for the other of inhalation and exhalation. This particular configuration may be desirable when the mask  10  filters only one of inhaled air and exhaled air, but not both. Where the mask  10  comprises a single filter unit, the filter unit (and any one-way valves) continues to be provided on a side of the mask body  20 , such that flexing of the mask body  20  about the medial plane  22  is unimpeded. 
     Two or more of the components of the mask  10  may be integrally formed, which is to say that the components may be formed as a unitary structure from the same material. For example, the mask body  20  and the cushion  30  may be integrally formed. Additionally or alternatively, the mask body  20  may be integrally formed with the filter ports  40 . Indeed, the mask  10  may be formed as a single unitary structure. That is to say that the mask body  20 , cushion  30 , filter ports  40  and attachments  50  may be integrally formed. By integrally forming components, and in particular by forming the mask  10  as a single unitary structure, gaps and grooves between different components may be avoided, which might otherwise harbor contaminants, such as bacteria and viruses, or which may create challenges to achieve appropriate sealing. As a result, a potentially more hygienic mask may be realized, which is easier is to clean and sterilize. Additionally, manufacture of the mask  10  (e.g. using injection molding, compression molding and additive manufacturing) may be made without assembly of multiple mask components. 
       FIG.  6    illustrates an example method  100  for manufacturing the mask  10 . In this method  100 , the mask  10  is manufactured as a single unitary structure using 3D printing. The method  100  comprises receiving  110  at a 3D printing device model data for the mask  10 , and printing  120  the mask  10  using the model data with the 3D printing device. The 3D printing device then prints the mask  10  from an elastomeric material, such as TPU. In one example, the mask body may be formed from Ultrasint® TPU01 available from BASF 3D Printing Solutions GmbH. 
     Where the retainers  80  are formed of the same elastomeric material as the mask  10 , both the mask  10  and the retainers  80  may be printed in a single print job. In this instance, the 3D printing device may receive 110 model data for both the mask  10  and the retainers  80 , and then print  120  the mask  10  and the retainers  80  simultaneously. Furthermore, the 3D printing device may receive model data for a harness for use with the mask  10 , which may be printed separately or simultaneously with the mask  10 . 
     The preceding description has been presented to illustrate and describe examples of the principles described. This description is not intended to be exhaustive or to limit these principles to any precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with any features of any other of the examples, or any combination of any other of the examples.