IMPROVEMENTS RELATING TO FACE MASKS

Abstract

The disclosed methods of manufacturing filter masks include using an overmoulding step to both form a sealing member and to fix the sealing member to a support frame and a sheet of filtering material.

Claims

1. A method of manufacturing a filter mask, the filter mask comprising a support frame, a filter and a sealing member, wherein the method comprises: a) locating the filter and the support frame in a mould; and b) injecting a polymeric material into the mould to form the sealing member, wherein the sealing member is brought into engagement with the filter and the support frame, during injection moulding of the sealing member, in a manner that fixes the sealing member to the support frame and the sheet of filtering material.

2. A method of manufacturing a filter mask as claimed in claim 1, wherein the support frame is made in a preceding step of the method by injection moulding, and the method further comprises a step of transferring the support frame from a first mould in which the support frame is injection moulded to a second mould in which the sealing member is injection moulded.

3. A method of manufacturing a filter mask as claimed in claim 1 or claim 2, wherein when the filter is located into the mould with the support frame, the support frame extends about the periphery of the filter.

4. A method of manufacturing a filter mask as claimed in any preceding claim, wherein the support frame comprises a rim that defines an aperture through which inhaled and/or exhaled gases flow, in use.

5. A method of manufacturing a filter mask as claimed in claim 4, wherein the support frame comprises a shoulder extending from an inner edge of the rim, providing a surface on which the filter can be located, facilitating retention of the filter in the mould prior to injection moulding of the sealing member.

6. A method of manufacturing a filter mask as claimed in any preceding claim, wherein the support frame comprises one or more ribs, which extend across a surface of the filter, providing support to the filter and rigidity to the mask.

7. A method of manufacturing a filter mask as claimed in any preceding claim, wherein the filter that is located in the mould in the method of manufacture comprises a filter substrate only.

8. A method of manufacturing a filter mask as claimed in any preceding claim, wherein the support frame and the filter are not fixed or bonded together prior to injection moulding of the sealing member.

9. A method of manufacturing a filter mask as claimed in any preceding claim, wherein, during injection moulding of the sealing member, a portion of the sealing member adheres aligned edges of the filter and the support frame.

10. A filter mask manufactured according to the method as claimed in any preceding claim.

11. A filter mask comprising a support frame, a filter and a sealing member, wherein the sealing member is fixed to the support frame and the filter.

12. A filter mask as claimed in claim 11, wherein the support frame and the filter together define a mask body, which forms a cavity for the accommodation of the wearer's mouth and nose.

13. A filter mask as claimed in claim 11 or claim 12, wherein an external face of the support frame comprises a shield, which extends over at least part of a surface of the filter.

14. A filter mask as claimed in any one of claims 11 to 13, wherein the shield is separated from the filter, such that air may flow between the shield and the filter before the air is drawn through the filter by the wearer during inhalation.

15. A filter mask as claimed in any one of claims 11 to 14, wherein one or more inlet apertures, through which air may be drawn by a wearer inhaling, is defined between an edge of the shield and the support frame.

16. A filter mask comprising a support frame, a filter and a sealing member, the support frame retaining the filter, such that ambient air is drawn through the filter on inhalation by a wearer, wherein the support frame includes a shield that extends over at least part of an outwardly-facing surface of the filter, wherein the shield is separated from the filter, such that air flows, in use, between the shield and the filter.

17. A filter mask as claimed in claim 16, wherein the support frame comprises a rim and a shield, and the shield is offset from the rim.

18. A filter mask as claimed in claim 17, wherein the rim extends about and/or over the periphery of the filter, and the shield is offset from both the rim and the filter.

19. A filter mask as claimed in claim 17 or claim 18, wherein the rim and the shield are connected together by one or more connection members, which extend between the shield and the rim and fix their relative positions.

20. A filter mask as claimed in any one of claims 16 to 19, wherein the shield has a shape corresponding to the shape of the filter, such that the surfaces of the filter and the shield are parallel.

21. A filter mask as claimed in any one of claims 16 to 20, wherein there is a spacing having an average size of 0.1-5 cm, or of 0.2-2.5 cm, or of 0.2-1.5 cm, or of 0.3-1 cm between the shield and the filter, measured along a line normal to the surface of the shield.

22. A filter mask as claimed in any one of claims 16 to 21, wherein one or more ribs are provided that extend across at least part of the surface of the shield that faces the filter, the ribs contacting the filter.

23. A filter mask as claimed in any one of claims 16 to 22, wherein the surface area of the shield is at least 50%, at least 60%, at least 70%, or at least 80%, or at least 90% or at least 95% of the surface area of the filter.

24. A filter mask as claimed in any one of claims 16 to 23, wherein the shield extends over less than 100% of the surface area of the filter, such that a portion of the filter is exposed at the periphery of the shield.

25. A filter mask as claimed in any one of claims 16 to 24, wherein the shield has no apertures formed therein, through which the sheet of filtering material is exposed, and forms a continuous barrier.

26. A filter mask comprising a support frame, a filter and a sealing member, the support frame retaining the filter, such that ambient air is drawn through the filter on inhalation by a wearer, wherein the support frame includes a shield that extends over at least part of an outwardly-facing surface of the filter, and at least part of the periphery of the shield being separated from the support frame, and one or more inlet apertures being defined between the shield and the support frame, through which air is drawn on inhalation by the wearer.

27. A filter mask as claimed in claim 26, wherein the separation between the periphery of the shield and the support frame is less than the width of the average person's finger.

28. A filter mask as claimed in claim 26 or claim 27, wherein the separation between the periphery of the shield and the support frame is less than 2 cm, or less than 1.5 cm or less than 1 cm.

29. A filter mask as claimed in any one of claims 26 to 28, wherein the shield forms a continuous barrier and the one or more inlet apertures are arranged around the periphery of the shield.

30. A filter mask as claimed in any one of claims 26 to 29, wherein the one or more inlet apertures in the nasal region and/or the chin region extend along curved paths from an angled apex in a central region of the mask, outwardly towards the sides of the mask, so as to receive the fingers of the wearer during a fit test, the fingers meeting at the angled apex.

31. A filter mask as claimed in any one of claims 26 to 30, wherein the one or more inlet apertures in the nasal region and/or the chin region extend a regular curved path from one side of the mask to the other, so as to receive the fingers of the wearer during a fit test, the fingers meeting at a midpoint of the curved path.

32. A filter mask as claimed in any one of claims 26 to 31, wherein the one or more inlet apertures in the side regions of the mask are aligned with the longitudinal axis of the mask and the wearer, ie the axis from the nose region to the chin region, and are generally linear in form, so as to receive the part of the hand between the index finger and thumb of the wearer during a fit test, for example.

33. A filter mask as claimed in any one of claims 26 to 32, wherein the filter mask is provided with a cover for the one or more inlet apertures, which enables the apertures to be occluded to perform a fit test.

34. A filter mask comprising a support frame, a filter and a sealing member, the support frame retaining the filter, such that ambient air is drawn through the filter on inhalation by a wearer from an exterior side of the filter to an interior side of the filter, wherein the filter mask includes an element for emitting a smell on the exterior side of the filter.

35. A filter mask according to claim 34, which further comprises a cover for inhibiting the smell before use, the cover being at least partially removable to at least partially expose the element for emitting a smell.

36. A kit of parts comprising the filter mask of any of claims 26 to 32, and a cover for the one or more inlet apertures, which enables the apertures to be occluded to perform a fit test.

37. A filter mask comprising a support frame and a sheet of filtering material, the support frame and the sheet of filtering material defining a mask body adapted to provide a cavity in use about the mouth and nose of a wearer, the filter mask includes a sealing member depending from at least a portion of a peripheral edge of the mask body, the sealing member comprising both an inwardly and outwardly depending lip portion relative to the peripheral edge of the mask body.

38. A filter mask as claimed in claim 37, wherein the portion of the peripheral edge of the support frame about which the inwardly and outwardly depending lip portions extend may comprise a chin portion.

39. A filter mask as claimed in claim 37 or claim 38, wherein the outwardly depending lip formation has a contact surface that is concave in shape.

40. A filter mask as claimed in any one of claims 37 to 39, wherein the outwardly depending lip portion is shaped so as to provide a sill or shelf formation beneath the wearer's mandible.

41. A filter mask as claimed in any one of claims 37 to 40, wherein the proximal portion of the outwardly depending lip portion engages the chin of the wearer, while a distal portion curves and extends under the chin of the wearer.

42. A filter mask as claimed in any one of claims 37 to 41, wherein the outwardly depending lip formation is shaped in the form of a chin cup.

43. A filter mask as claimed in any one of claims 37 to 41, wherein the periphery of the support frame in the vicinity of the inner and outer lip portions is shaped from a central point or region of the mask by a first radius, and the inwardly depending lip portion has an inner edge of radius which is smaller than the first radius.

44. A filter mask as claimed in any one of claims 37 to 43, wherein the periphery of the support frame in the vicinity of the inner and outer lip portions is shaped from a central point or region of the mask by a first radius, and the outwardly depending lip portion has an outer edge of radius which is larger than the first radius.

45. A filter mask as claimed in any one of claims 37 to 44, wherein the nasal portion of the sealing member comprises an inwardly depending lip portion, which presents a convex surface for contact with a wearer's face.

46. A filter mask as claimed in any one of claims 37 to 45, wherein the nasal portion of the sealing member includes reinforcement formations on each side of the nose.

47. A filter mask as claimed in any one of claims 37 to 46, wherein the sealing member and, therefore, the filter mask, may also extend laterally across the wearer's cheeks.

48. A face mask comprising a mask body that defines a cavity for accommodating the nose and mouth of a wearer and from which a wearer inhales respiratory gases, in use, and a sealing member depending from the mask body for engagement with the wearer's face, the mask body comprising a nasal portion for accommodating the nose of the wearer, a mouth portion for accommodating the mouth of the wearer, and cheek portions extending laterally across the wearer's cheeks.

49. A face mask as claimed in claim 48, wherein the cheek portions may extend laterally across the wearer's cheeks between the upper edges of the malar bones and the lower edge of the mandible of the wearer.

50. A face mask as claimed in claim 48 or claim 49, wherein the face mask extends laterally across the wearer's cheeks such that an edge of the mask is situated, in use, within 5 cm, or within 4 cm, or within 3 cm, or within 2 cm of the wearer's ears.

51. A face mask as claimed in any one of claims 48 to 50, wherein the mask substantially covers the wearer's cheeks.

52. A face mask as claimed in any one of claims 48 to 51, wherein the portions of the mask body which extend across the wearer's cheeks form a shallower cavity between the mask body and the wearer's face than the portion of the mask body which extends over the wearer's nose and mouth.

53. A face mask as claimed in any one of claims 48 to 52, wherein the face mask is a filter mask, and the mask body is defined by the support frame and the filter.

54. A face mask as claimed in claim 53, wherein the sealing member extends about the periphery of the support frame.

55. A face mask as claimed in claim 53 or claim 54, wherein the support frame and the filter extend laterally across the wearer's cheeks in the cheek portions of the mask body.

56. A face mask comprising a pair of first attachment formations and a pair of second attachment formations, the pair of first attachment formations being positioned on first side of the face mask which, in use, is located near a first ear of the wearer and the pair of second attachment formations being positioned on a second side of the face mask which, in use, is located near a second ear of the wearer, wherein each of the first pair of attachment formations provides means for securing an end portion of the strap, and the second pair of attachment formations provides means for releasably fixing an intermediate portion of the strap.

57. A face mask as claimed in claim 56, wherein the cord or strap passes sequentially through the pair of second attachment formations, such that a loop of cord is formed between the pair of second attachment formations.

58. A face mask as claimed in claim 56 or claim 57, wherein the second attachment formations permit easy passage of the cord in one direction on application of tension, but prevent movement of the cord in the opposite direction without additional action by the user.

59. A face mask as claimed in any one of claims 56 to 58, wherein the pair of second attachment formations each comprise a slot or aperture and a tab or resilient member extending over the slot or aperture such that, in use, the cord or strap is inserted through the aperture and is captured between an edge of the slot or aperture and an edge of the tab or resilient member.

60. A face mask as claimed in claim 59, wherein the tab or resilient member comprises a gripping formation along at least one edge.

61. A face mask as claimed in any one of claims 56 to 58, wherein the first and/or second attachment formations are formed integrally with a support frame of the face mask.

62. A filter mask according to any of claims 10-47, or a face mask according to any of claims 48-61, which further comprises an additive containing silver ions.

63. A method of manufacturing a filter mask, the filter mask comprising a support frame and a sealing member, the support frame having a housing for receiving a filter, wherein the method comprises: a) providing the support frame in a mould; and b) injecting a polymeric material into the mould to form a first sealing member for sealing against the face of a wearer, and a second sealing member for sealing against the filter received by the housing, wherein the sealing member is brought into engagement with the support frame, during injection moulding of the sealing member, in a manner that fixes the sealing member to the support frame.

64. A method of manufacturing a filter mask as claimed in claim 63, wherein the filter comprises a filter substrate retained within a cartridge or other support, which is connectable to the support frame.

65. A method of manufacturing a filter mask as claimed in claim 64, wherein the cartridge takes the form of a rim of plastic, for example injection moulded plastic, which matches the shape and size of the filter substrate and which is fixed about the circumference of the filter substrate.

66. A method of manufacturing a filter mask as claimed in claim 63 or 64, wherein the cartridge further comprises a shield.

67. A filter mask manufactured according to a method of manufacturing a filter mask as claimed in any one of claims 63 to 65.

Description

[0120] FIG. 1 is a perspective view of a support frame of a first embodiment of a filtration mask according to the invention;

[0121] FIG. 2 is a side view of the support frame of FIG. 2;

[0122] FIG. 3 is a perspective view of a filter of the first embodiment of a filter mask according to the invention;

[0123] FIG. 4a is a perspective view of the filter located within the support frame of the first embodiment of a filter mask according to the invention during manufacture;

[0124] FIG. 4b is the view of FIG. 4a, without the filter;

[0125] FIG. 5 is a perspective view of the support frame and filter of FIG. 4 and a core of the mould using during manufacture of the first embodiment of a filter mask according to the invention;

[0126] FIG. 6 is a side view of the first embodiment of a filter mask according to the invention;

[0127] FIG. 7 is a perspective view of the rear of the first embodiment of a filter mask according to the invention;

[0128] FIG. 8 is a schematic drawing showing the connection between the support frame and the filter material formed by overmoulding of the sealing member;

[0129] FIGS. 9a and 9b are perspective views of the front and rear of a second embodiment of a filter mask according to the invention; and

[0130] FIGS. 10a and 10b are perspective views of the front a rear of a third embodiment of a filter mask according to the invention.

[0131] A support frame 10 for use in a filter mask according to the invention is shown in FIGS. 1 and 2. The support frame 10 has a generally curved shape and comprises an integrally formed rim 11, a shield 12, a pair of first attachment formations 13 and a pair of second attachment formations 14. The shield 12 is substantially the same shape as the rim 11, but is smaller, and is offset from the rim 11 by approximately 1 cm. The shield 12 is attached to the rim 11 by four connection members 16 equally spaced about the circumference of the rim, and attached to points close to the edge of the shield. A space 15 between the shield 12 and the rim 11 extends about the periphery of the shield, interrupted only by the connection members 16. The support structure 10 is an integrally formed component, with all features manufactured in a single injection moulding step.

[0132] A pair of first attachment formations 13 outwardly extend from a first side of the rim 11 which, in use, is located near a first ear of the wearer. The first attachment formations 13 take the form of a keyhole shaped slot through which a cord or strap (not shown) may be threaded, and secured with a knot or clamping device. A pair of second attachment formations 14 extend outwardly from a second side of the rim which, in use, is located near the second ear of the wearer. The second attachment formations 14 comprise a slot (not visible) covered by a tab 17. The tab 17 has a series of teeth 18 which provide grip. The cord or strap (not shown) passes through the slot in the attachment formation 14 from the internal side of the support frame to the external side, between the tab 17 and an edge of the slot. The teeth 18 grip the cord and reduce or prevent movement of the cord in the reverse direction.

[0133] In use, the cord or strap is secured in the upper first attachment formation 13, passes through the upper second attachment formation 14 from the internal side to the external side, through the lower second attachment formation 14 from the external side to the internal side, and is finally secured in the lower first attachment formation 13. Thus, the strap passes behind the wearer's head twice, with a loop being formed between the pair of second attachment formations 14 on the external side of the support structure. When the wearer applies tension to this loop, eg by pulling the loop, the cord will be pulled through the apertures, past the teeth 18 on the tab 17. The release of this tension eg by the wearer releasing the loop of cord, will allow the teeth 18 to grip the cord, thus preventing the cord from sliding back through the slot unless a significant force is applied. In this way, one hand may be easily used to adjust the mask to fit the wearer's head.

[0134] Injection moulding is used to produce the support frame 10, the support frame 10 being an integrally formed unit produced from injection moulded polypropylene in a single step.

[0135] Where the manufacture of the filter mask is automated, the support frame 10 is ejected from the mould onto a vacuum cup on a robot arm. A pneumatic die pushes a sheet of filter material 22 from a roll of filtration material into the support frame 10, the roll of filter material comprising a continuous series of pre-stamped sheets of filter material, heat sealed about their peripheral edges. The sheet of filter material 22 is shown in FIG. 3.

[0136] The sheet of filter material is positioned on the internal side of the support frame 10, that is, the side of the support frame 10 which will face the wearer in use. The sheet of filtering material is located on the inwardly extending shoulder, held in place about its periphery by retention tabs 19 at either side of the rim. This support structure/filter material assembly is shown in FIGS. 4a and 4b.

[0137] The support structure/filtration material assembly is transferred into a first half of the mould and mounted to a mould core 30. A second half of the mould is sealed against the first half of the mould, forming the mould cavity. In an injection moulding step, a sealing member 25 is overmoulded to the support structure/filtration material assembly, surrounding the periphery of the sheet of filter material 22 and adhering it to the support frame 10, and forming the sealing member 25, in a single overmoulding step. The filter mask 20 is removed from the mould, eg using a large 20 mm pin to unpeel the filter mask 20 from the core 30, and transferred for manual attachment of an elasticated cord and subsequent packaging.

[0138] The connection between the filter, sealing member and support frame is shown schematically in FIG. 8. The periphery of the filter 91 is placed against a shoulder 94 extending laterally from the rim of the support frame 93, either before or after the support frame is placed in the mould. A thermoplastic elastomer (TPE) 92 is injected into the mould to form the sealing member. The portion of TPE 92 shown in FIG. 8 represents only a proximal edge of the sealing member. The TPE 92 is forced by the mould between the peripheral edge of the filter 91 and the rim and shoulder of the support frame 93, 94. The TPE 92 surrounds and impregnates the peripheral edge of the filter 91, the peripheral, impregnated region being denoted 95, adhering it to the rim and shoulder of the support frame 93, 94. Tool shutout, as shown in FIG. 8, prevents ingress of TPE 92 into the filter 91 beyond its periphery 95, ensuring that the filtering action of the filter 91 is not inhibited by TPE. As well as aiding adhesion of the support frame 93, 94 to the filter, impregnation of the peripheral edge 95 of the filter 91 with TPE may contribute to the seals at the edge of the filter, formed by heat sealing, preventing moisture or other contaminants from seeping into the structure of the filter.

[0139] A side view of a filtration mask 20 according to the invention is shown in FIG. 6. The support structure 21 is the same as that described in relation to FIGS. 1 and 2. A sheet of filtering material 22 is positioned behind the support structure 21, and is visible in the gap between the shield 23 and the rim 24, about the periphery of the shield 23. This permits air to easily flow past the shield 23 and through the filtering material 22, while still benefitting from the protection of the shield across the filtering material.

[0140] The sealing member 25 is overmoulded onto the support frame 21 and filter material 22, fixing their relative positions. The sealing member 25 comprises a chin engaging portion 26, a nose engaging portion 27 and cheek engaging portions 28. The cheek engaging portions 28 extend laterally across the cheeks, forming a seal against the softer skin on the cheek and improving the overall seal of the mask.

[0141] The sealing member 25 is formed of an elastomeric material. It provides a compressible region between the support structure 21 and the wearer's face, enabling the elastomeric material to conform to the contours of the wearer's face and provide a good seal against it.

[0142] FIGS. 4a and 4b show the support structure/filter member assembly, with and without the filter material present respectively. The support structure 10 comprises a rim 11. The rim 11 has an inwardly extending shoulder 18 onto which a pre-cut sheet of filter material 22 is placed. Extending from a first side of the rim are first attachment formations 13, and second attachment formations 14 extend from the second side of the rim. The support frame 10 also comprises a shield 12. A series of vertical ribs 29 across the back of the shield 12 ensure that the spacing between the shield 12 and the filter material 22 is maintained.

[0143] A second embodiment of a filter mask according to the invention can be seen in FIGS. 9a and 9b, and is generally designated 100. The structure of the mask is substantially the same as that described in relation to the first embodiment depicted in FIGS. 6 and 7, except that the mask 100 further comprises a mushroom valve 101 (shown in the closed position). In the chin region, the rim 102 of the support frame comprises an upwardly projecting portion 103, and the shape of the shield 104 and filter material 105 corresponds to the shape of the inner periphery of the rim 102 such that they accommodate the upwardly projecting portion 103. The filter material 105 is sealed along the periphery of the rim 102 of the support frame, including the upwardly projecting portion 103, by a surrounding rim of TPE 106. The upwardly projection portion comprises an aperture, with the mushroom valve 101 being formed in the aperture as part of the overmoulding step which also forms the sealing member 107. The mushroom valve 101 permits exhaled air to escape without passing through the filter material 105. The mushroom valve 101 could alternatively be accommodated within the shield 104.

[0144] The third embodiment of a filter mask shown in FIGS. 10a and 10b, which is generally denoted 110, has substantially the same structure is described in the second embodiment in relation to FIGS. 9a and 9b, but shows an elbow connection 111 in place of the mushroom valve. The elbow connection 111 permits connection of the mask 110 to other medical equipment, such as a nebuliser.