Patent Publication Number: US-2023136249-A1

Title: System and method for manufacturing face masks with elasticized straps and product

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/704,074, filed 16 Mar. 2020, the disclosure of which is incorporated herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Embodiments of the present invention relate to face masks and, more particularly, to high speed automated production of face masks. 
     BRIEF STATEMENT OF THE INVENTION 
     Embodiments of the present invention are directed to systems, apparatus, and methods for making a face mask. More specifically, embodiments of the present invention are directed to a method for making a face mask through high speed automated production, a system for practicing the method, and a product made by the method. 
     In accordance with one aspect of the invention, a method of manufacturing a face mask includes coupling at least one tensioned elastic structure to at least one web material to form a continuous elastic strap, advancing the continuous elastic strap in a machine direction, coupling the continuous elastic strap to a multi-layer mask web traveling in the machine direction to form a continuous face mask composite structure, the multi-layer mask web comprising an inner web layer, an outer web layer, and a filter layer positioned therebetween, and cutting the continuous face mask composite structure to define a plurality of discrete face masks. 
     In accordance with another aspect of the invention, a face mask includes a multi-layer mask panel comprising an inner web layer, an outer web layer, and at least one filter layer positioned therebetween and at least one elastic strap coupled to the multi-layer mask web, the at least one elastic strap comprising at least one elastic structure coupled between a first web layer and a second web layer. 
     In accordance with another aspect of the invention, an apparatus for manufacturing a plurality of face masks includes at least one strap bonding unit configured to couple at least one tensioned elastic structure to at least one web material to form a continuous elastic strap and a feeding unit configured to advance the continuous elastic strap in a machine direction. The apparatus also includes a mask bonding unit configured to couple the continuous elastic strap to a multi-layer mask web traveling in the machine direction to form a continuous face mask composite structure, the multi-layer mask web comprising an inner web layer, an outer web layer, and a filter layer positioned therebetween. The apparatus further includes a cutting unit configured to cut the continuous face mask composite structure to define a plurality of discrete face masks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate embodiments presently contemplated for carrying out the invention. 
       In the drawings: 
         FIG.  1    is a schematic view of a portion of the manufacturing line for forming face masks according to an embodiment of the invention. 
         FIGS.  1 A and  1 B  are schematic views of portions of the manufacturing line of  FIG.  1    according to alternative embodiments of the invention. 
         FIG.  2    is a flowchart illustrating a method for making a face mask according to an embodiment of the invention. 
         FIGS.  3 - 9    are systematic diagrams illustrating the multi-layer mask web of  FIG.  1    during the manufacturing process according to embodiments of the invention. 
         FIG.  10    is a schematic view of an individual face mask unit producible via the manufacturing line and method of  FIGS.  1  and  2    according to an embodiment of the invention. 
         FIG.  11 - 14    are side plan views of an individual face mask unit producible via the manufacturing line and method of  FIGS.  1  and  2    according to embodiments of the invention. 
         FIG.  15    is a schematic diagram of an elasticized strap web with deactivation zones according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention provide for a system and method for high speed automated production of face masks. 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     As illustrated in  FIG.  1   , a schematic view of a portion of a manufacturing line  100  for forming face masks according to an embodiment of the invention is shown.  FIG.  2    illustrates a flowchart illustrating a method  200  for making face masks according to an embodiment of the invention. Referring to both  FIGS.  1  and  2   , a plurality of bendable strips  102  is supplied (step  202  of  FIG.  2   ) from a supply spool  104  of bendable material such as metal. Each bendable strip  102  may be cut or otherwise separated from the supply spool  104  by a separator unit  106  such as a slip cut unit or other type of spacing and cutting unit. In an alternative embodiment where bendable strips  102  are provided in discrete form, the separator unit  106  may be omitted. 
     The bendable strips  102  are provided to a multi-layer mask web  108  that includes an outer layer  110 , a filter layer  112 , and an inner layer  114  stacked together (step  204  of  FIG.  2   ). As non-limiting examples, outer and inner layers  110 ,  114  may include nonwoven materials, woven materials, films, foams, and/or composites or laminates of any of these material types. In the embodiment illustrated in  FIG.  1   , the outer and inner layers  110 ,  114  are separate webs. However, embodiments of the invention contemplate that the outer and inner layers  110 ,  114  may be formed from a single web folded about the filter layer  112 . In addition, the filter layer  112  may include single or multiple layers of filter material that may be flat or may have folds or pleats formed therein. The bendable strips  102  may be positioned between the outer layer  110  and filter layer  112  (as illustrated in  FIG.  1   ), between the filter layer  112  and inner layer  114 , between multiple filter layers  112 , or to the outward-facing surface of inner layer  114 . An adhesive may be optionally applied from an adhesive applicator  116  directly to each bendable strip  102  or to one of the layers to which it is being supplied. 
     As illustrated, the multi-layer mask web  108  includes the outer layer  110 , the filter layer  112 , and the inner layer  114 . Optional materials such as foam or other types of padding  118  may be included adjacent to bendable strip  102  either externally (as shown; step  206  of  FIG.  2   ) or internally to increase the comfort of the wearer of the mask. 
     In one embodiment, the outer layer  110  may be wider than the inner layer  114  such that one or both of the longitudinal edges  122 ,  124  of the outer layer  110  extend beyond the longitudinal edges  126 ,  128  of the inner layer  114 . Alternatively, one or both of the longitudinal edges  126 ,  128  of the inner layer  114  may be wider than the corresponding edges  122 ,  124  of the outer layer  110 . Accordingly, an optional edge folder  120  may fold the extending longitudinal edges  122 - 128  to overlap the longitudinal edges  122 - 128  of the opposite layer (step  208  of  FIG.  2   ). 
     The multi-layer mask web  108  is provided to an edge sealer  130  so that the outer and inner layers  110 ,  114  may be joined or sealed together (step  210  of  FIG.  2   ). In a preferred embodiment, the sealing of the outer and inner layers  110 ,  114  locks the filter layer  112  between the outer and inner layers  110 ,  114  so that its position remains fixed. Alternatively, the position of the filter layer  112  may be fixed through other methods such as adhesive. 
     In one embodiment, the outer and inner layers  110 ,  114  are joined or sealed together using a bonding apparatus using any known ultrasonic welding system in alternative embodiments, including, as non-limiting examples, a rotary ultrasonic welding system or a blade ultrasonic welding system. For example, a rotary anvil and an ultrasonic fixed blade horn, also known as a sonotrode, cooperate with each other to bond the outer and inner layers  110 ,  114 . Alternative embodiments may include multiple fixed blade horns or one or more rotary horns. 
     The ultrasonic emission of energy from the edge sealer  130  is concentrated at specific bond points where frictional heat fuses the layers of web together without the need for consumable adhesives. While the edge sealer  130  may include an ultrasonic bonding assembly that ultrasonically fuses layers of web together as described herein, it is contemplated that the techniques described herein may be extended to any other known welding or bonding techniques that fuse together two or more material layers including ultrasonic, thermal, or pressure bonding techniques and various other forms of welding known in the industry. 
     Alternatively, the edge sealer  130  may include an adhesive applicator and one or more rollers configured to apply adhesive or glue between the outer and inner layers  110 ,  114  and to apply pressure thereto to join the outer and inner layers  110 ,  114  together. 
     Alternatively, the edge sealer  130  may include a thermal bonding unit (not shown) configured to heat one or both of the outer and inner layers  110 ,  114  and press the layers  110 ,  114  together causing the outer and inner layers  110 ,  114  to be joined together. 
     It may be desirous to have the speed or feed rate of the multi-layer mask web  108  changed to a slower speed in locations where bonding or sealing of the outer and inner layers  110 ,  114  is to occur. In this case, a system configured to selectively decrease the feed rate of the mask web  108  at the bond location may be used, such as, for example, multiple festoon accumulators may be used to slow the web to a bonding velocity in a manner disclosed in U.S. Pat. No. 10,537,479, issued to Curt G. Joa, Inc. of Sheboygan Falls, Wis. and which is incorporated herein by reference in its entirety. 
     In an embodiment where it is desirable to remove one or more portions of the longitudinal edges  122 - 128  extending beyond bond joints between the outer and inner layers  110 ,  114 , an optional trimmer  132  may slit the multi-layer mask web  108  to separate undesirable portions therefrom to be discarded (step  212  of  FIG.  2   ). 
     Downstream of the edge sealer  130  in a machine direction  134 , a pleat folder  136  forms pleats (step  214  of  FIG.  2   ) in the multi-layer mask web  108  that allow the web  108  to be stretched to increase a covering area for a user&#39;s face. An optional patch placement assembly  138  may attach (step  216  of  FIG.  2   ) reinforcement patches adjacently to the longitudinal edges of the multi-layer mask web  108  at the attachment zones to which the elastic straps disclosed herein will be affixed. The optional reinforcement patches may be applied, for example, to the inner layer  114  to reinforce the coupling of the elastic straps to the multi-layer mask web  108 . Manufacturing line  100  may also include one or more optional edge wrap units (not shown) configured to wrap material about one or both lateral edges of the multi-layer mask web  108 . 
     An end seal unit  140  receives the multi-layer mask web  108  and seals or joins the outer and inner layers  110 ,  114  together (step  218  of  FIG.  2   ) in an end seal location extending in a cross-machine direction  142  at locations along the multi-layer mask web  108  corresponding to separation zones from which individual masks may be separated into individual units. The end seal locations overlap and extend away from their corresponding separation zones such that when an individual mask unit is separated from the web  108 , the joint of the outer and inner layers  110 ,  114  created by the separated end seal location forms an end edge seal. 
     In a different portion of manufacturing line  100 , an elasticized strap web  144  is formed to provide elastic straps to be attached to the multi-layer mask web  108  to form straps stretchable around the head of a user to keep the mask unit in place. As shown, the elasticized strap web  144  may be simultaneously created with the creation of the multi-layer mask web  108 . Alternatively, the elasticized strap web  144  may be supplied from a spool where the elasticized strap web  144  has been previously created in a prior process. In the embodiment shown, a strap web  146  is provided (step  220  of  FIG.  2   ), and a one or more tensioned elastic strands or structures  148  are joined (step  222  of  FIG.  2   ) to the strap web  146 , in one embodiment, by adhesive applied from an adhesive applicator  150  before or after the elastic strands are brought next to the strap web  146 . While three elastic strands  148  are illustrated in  FIG.  1   , embodiments of the invention contemplate that any number of elastic strands may be used including a single strand. In addition or alternatively thereto, elastic film or other stretchable materials such as rubber may be used. 
     In the case where the elastic straps are formed from a single layer of strap web material  146  as illustrated, a folder  152  may fold (step  224  of  FIG.  2   ) one portion of the strap web  146  over another to create inner and outer layers of strap web material between which the plurality of elastic strands  148  is positioned. In an embodiment not using adhesive, a non-adhesive bonding unit  154  (shown in phantom) may be used in place of the adhesive applicator  150  to create a glue-less elastic strap. The non-adhesive bonding unit  154  may utilize any known welding or bonding techniques that fuse together two or more material layers without the use of adhesive, including sonic, thermal, or pressure bonding techniques and various other forms of welding known in the industry. In other words, the non-adhesive bonding unit  154  may be an ultrasonic bonding unit, a thermal bonding unit, or a pressure bonding unit, according to alternate embodiments. According to one non-limiting embodiment, non-adhesive bonding unit  154  may be configured in a similar manner as any of the bonding units disclosed in U.S. Ser. Nos. 16/260,259, 16/717,186, and 16/721,414 filed by Curt G. Joa, Inc. of Sheboygan Falls, Wis., the disclosures of which are incorporated herein by reference in their entireties. 
     In the embodiment shown, a single assembly line for forming elasticized strap web  144  is used to form and split (step  226  of  FIG.  2   ) the elasticized strap web  144  into two or more elastic straps by a cutter/slitter  156 . However, it is contemplated that multiple assembly lines may be used for creating corresponding multiple lines of elasticized strap webs  144 . In this case, the cutter  156  may be eliminated. Furthermore, it is contemplated that the cutter/slitter  156  may be omitted in embodiments where a single, wide elastic strap may be used to secure the individual mask unit to the user wherein the single strap is attached to the mask at the side edges of both the top and bottom portions of the mask. 
     Manufacturing line  100  may further include an optional friction enhancing unit  153  downstream from the folder  152 . In one embodiment, unit  153  may be a cut-and-place unit that cuts and positions patches of material on the elasticized strap web  144  that enhance the friction of the strap web  144  and aid in maintaining the straps in position when the completed mask is in use. These patches of material may be secured to the elasticized strap web  144  via adhesive, sonic, thermal, or pressure bonding, or any other known securement means. In alternative embodiments, unit  153  may be a feed unit that couples a continuous web of friction-enhancing material to the surface of the strap web  144 . In yet other embodiments, the frictional properties of the strap web  146  may be enhanced via application of a coating or surface treatment of the material itself. 
     Application of the elastic strands  148  to the strap web  146  occurs while the elastic strands  148  are in a stretched state. The result is an elasticized strap web  144 . The tension in the elasticized strap web  144  is relaxed or partially relaxed prior to its attachment to the multi-layer mask web  108 . In one embodiment, the manufacturing speed of the elasticized strap web  144  is faster than the manufacturing speed of the multi-layer mask web  108 . For example, the manufacturing speed of the elasticized strap web  144  may be 900-1000 ft./min. while the manufacturing speed of the multi-layer mask web  108  may be 300 ft./min. Thus, when in a relaxed state matching the length of the mask, the elasticized strap web  144  may offer a stretch of up to three times the length of the mask. 
     Therefore, in order to attach the elasticized strap web  144  in a relaxed or partially-relaxed state to the multi-layer mask web  108 , the manufacturing speed of the elasticized strap web  144  must be slowed down to correspond with the manufacturing speed of the multi-layer mask web  108 . A retraction assembly  158  retards (step  228  of  FIG.  2   ) the elasticized strap web speed prior to the attachment of the elasticized strap web  144  to the multi-layer mask web  108 . In one embodiment illustrated in  FIG.  1 A , the retraction assembly  158  includes a plurality of rollers  160  arranged in an “s-wrap” configuration configured to allow the speed of the elasticized strap web  144  to decrease between rollers  160 . Two or more rollers  160  may be used to retard the elasticized strap web speed. Rollers  160  may be powered or free-rolling. In another embodiment illustrated in  FIG.  1 B , multiple pairs of nip rollers  162 ,  164  may be used and actively controlled to slow down the manufacturing speed of the elasticized strap web  144 . For example, nip rollers  162  may be controlled to reduce the speed of the elasticized strap web  144  to a speed half of the difference (e.g., 600 ft./min. using the example numbers above) between the elasticized strap web speed and the multi-layer mask web speed. Nip rollers  164  may then be used to reduce the speed of the elasticized strap web  144  to a speed substantially matching the multi-layer mask web speed. It is contemplated that more pairs of nip rollers may be used to create more slowdown stages if desired. 
     Downstream of the end seal unit  140 , the one or more continuous elasticized strap webs  144  are brought together with the multi-layer mask web  108 , while the one or more continuous elasticized strap webs  144  and the multi-layer mask web  108  are traveling in the machine direction  134 , and provided to a strap bonding module  166  that bonds (step  230  of  FIG.  2   ) the one or more elasticized strap webs  144  in attachment zones or bond sites  805  ( FIG.  8   ) that are spaced apart in the machine direction  134  and correspond with the end seal locations  700  ( FIG.  7   ) sealed by the end seal unit  140 . Strap bonding module  166  may be similar to any of the embodiments described above for edge sealer  130  or may include other types of attachment methods including, for example, stapling. In the case where the strap bonding module  166  adhesively joins the one or more elasticized strap webs  144  to the multi-layer mask web  108 , an adhesive applicator  168  may apply adhesive for the attachment. The one or more elasticized strap webs  144  are positioned along the multi-layer mask web  108  so that both webs  108 ,  144  run together in the machine direction  134  for attachment. The straps, when bound in this manner, extend along the length direction  807  ( FIG.  10   ) of the individual mask units  172  ( FIG.  10   ) when separated rather than along the width direction  809  ( FIG.  10   ) as known in the art. 
     After the one or more elasticized strap webs  144  are bonded with the multi-layer mask web  108 , a cutting assembly  170  forms masks (step  232  of  FIG.  2   ) from the resulting continuous face mask composite structure  234  in preparation for packaging. Cutting assembly  170  may have a knife to completely cut through the combined webs  108 ,  144  to individualize discrete mask units  172  at the separation zones or may have a perforation unit that forms perforations through the combined webs  108 ,  144  to apply a perforation along the separation zones that allows an end user to tear individual masks from a continuous mask web. Thereafter, the individualized mask units (or the perforated mask web) are provided to a packaging unit  174  for packaging the individual or perforation-formed masks as desired. For example, the masks may be individually packed or bagged or boxed as a group of masks. 
     Referring to  FIG.  3   , a schematic diagram illustrating the multi-layer mask web  108  after the step  208  of folding the longitudinal edges  122 ,  124  of the outer layer  110  over the inner layer  114  is shown.  FIG.  4    illustrates a schematic diagram showing the multi-layer mask web  108  after the step  210  of edge sealing the longitudinal edges  122 - 128  of the outer and inner layers  110 ,  114 . Attachment zones  400  of adhesive or individual ultrasonic bond points, for example, are shown. As illustrated, additional attachment zones  402  may be positioned adjacently to ends of the bendable strips  102  to further secure against movement along the length direction of the individual masks. 
     Referring to  FIG.  5   , a schematic diagram illustrates the multi-layer mask web  108  after the step  214  of forming pleats  500  therein.  FIG.  6    illustrates a schematic diagram showing the multi-layer mask web  108  after the optional step  216  of placing reinforcement patches  600 . While pairs of patches  600  are illustrated on opposite sides of the multi-layer mask web  108 , a single patch  600  may be placed across the width of the multi-layer mask web  108  or a subportion of the width, such as in a patch extending through the central section of the mask web  108 , in other embodiments. 
     Referring to  FIG.  7   , a schematic diagram illustrates the multi-layer mask web  108  after the step  218  of joining the outer and inner layers  110 ,  114  together at end seal locations  700 .  FIG.  8    illustrates a schematic diagram showing the resulting continuous face mask composite structure  234  after the step  230  of bonding separated elasticized straps  800 ,  802  to the multi-layer mask web  108 . As shown in  FIG.  8   , the separated straps  800 ,  802  are bonded to the multi-layer mask web  108  at locations adjacent the respective top longitudinal edge  801  and the bottom longitudinal edge  803  of the multi-layer mask web  108 .  FIG.  9    illustrates a schematic diagram showing the separation zones  900  in the continuous face mask composite structure  234  along which the continuous face mask composite structure  234  is to be cut to individualize discrete mask units  172  ( FIG.  10   ) or along which the continuous face mask composite structure  234  is to be perforated as described above. 
       FIG.  10    provides a top plan view of an individual mask unit  172  with elasticized straps  1000 ,  1002  corresponding respectively to separated elasticized straps  800 ,  802  of  FIG.  8   . Referring to  FIG.  11   , a side plan view of the individual mask unit  172  is illustrated showing elasticized strap  1000  in a relaxed state. As shown in  FIG.  11   , the elasticized strap  1000  has a ruffled appearance in the relaxed state due to the gathering of strap web  146 .  FIG.  12    illustrates the elasticized strap  1000  in a stretched state to allow the elasticized strap  1000  to be positioned around the head of a user. As previously discussed, the length of the elasticized strap  1000  in the stretched state as illustrated in  FIG.  12    may be, for example, three times the length of the elasticized strap  1000  in the un-stretched or relaxed state as illustrated in  FIG.  11   . Other ratios of the length of the elasticized strap  1000  in its stretched state to its relaxed state are available, however, and contemplated herein. For example, an elasticized strap  1000  formed from the elasticized strap  800  may have a different stretch ratio than elasticized strap  1002  formed from the elasticized strap  802  on the same discrete mask  172 . One may have a 3:1 ratio while the other may be different such as a 2:1 ratio. In addition, an elasticized strap  1000  formed from the elasticized strap  800  may have a different attachment tension to the mask  172  than elasticized strap  1002  formed from the elasticized strap  802  on the same discrete mask  172 . 
     In an alternative embodiment,  FIG.  13    illustrates a side plan view of the individual mask unit  172  where the length of the mask is longer than the length of the elasticized strap  1000  in its relaxed state. As shown, the multi-layer mask web portion of the mask unit  172  may be folded in preparation for packaging to account for its longer length compared with the length of the elasticized strap  1000 . In another embodiment shown in  FIG.  14   , the length of the elasticized strap  1000  in its relaxed state is longer than the length of the mask unit  172 . Accordingly, the elasticized strap  1000  may be folded if desired to account for its longer length for packaging. 
       FIG.  15    illustrates a schematic diagram of an embodiment of the elasticized strap web  144  in either an adhesive-based construction or an adhesive-less elastic entrapment construction. As shown, deactivation zones  1400  may be formed by not applying adhesive or not forming entrapment bonds in areas  1400  to have elastic deactivation and breaking the elastic threads  148  that span the areas  1400 , causing the elastic threads  148  to retract toward opposite sides of the deactivation zone  1400  to the point where the elastic threads  148  are trapped by either adhesive or entrapment bonds. The elastic threads  148  may be broken by being cut with a cutting unit (not shown) configured to cut the elastic threads  148  using a knife or by being pinched to a breaking point with a crushing apparatus. Adhesive-less elastic entrapment construction involving entrapment bonds and deactivation zones is described in U.S. Publication No. 2019/0234606 and assigned to Curt G. Joa, Inc. of Sheboygan Falls, Wis., which is incorporated herein by reference in its entirety. 
     Embodiments of the invention described herein provide a number of improvements over prior art face masks. The resulting mask structure includes a ruffled elastic strap that is more comfortable to wear and more breathable. The disclosed methods of manufacturing the elastic straps facilitates forming straps with adjustable tension to create an improved fit. The mask is held in place while in use due to the ruffled profile of the strap alone or in combination with other friction-enhancing materials or surface textures. The disclosed method of manufacture also permits masks to be formed at a higher speed that prior art methods, as the masks do not need to be turned 90 degrees prior to attaching the straps. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description but is only limited by the scope of the appended claims.