IMPROVEMENTS RELATING TO FACE MASKS

Abstract

Face masks, including filter masks, and methods for their production. The disclosed methods 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 sealing member for use in a filter mask, the method comprising the steps of: (a) providing a mould having a cavity, a polymer injection port and a gas inlet port; (b) injecting a polymer through the polymer injection port into the cavity of the mould; and (c) introducing gas through the gas inlet port into the cavity of the mould, thereby forming a sealing member of the filter mask, wherein the sealing member of the filter mask comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall formed of the polymer, the enclosing wall including a face-contacting surface, the face-contacting surface having a form that is determined by the cavity of the mould and provides an anatomical fit with a user.

2. A method of manufacturing at least a portion of a sealing member for use in a filter mask, the method comprising the steps of: (a) providing a mould having a cavity, a polymer injection port and a gas inlet port; (b) injecting a polymer and a blowing agent through the polymer injection port into the cavity of the mould; and (c) introducing gas through the gas inlet port into the cavity of the mould, to form a sealing member, wherein the sealing member comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall formed of the polymer, the enclosing wall including an external surface, the external surface having a form that is determined by the cavity of the mould.

3. The method of claim 2, wherein the blowing agent is a physical blowing agent.

4. 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) forming the sealing member by: i) providing a mould having a cavity, a polymer injection port and a gas inlet port; ii) injecting a polymer through the polymer injection port into the cavity of the mould; and iii) introducing gas through the gas inlet port into the cavity of the mould, thereby forming a sealing member of the filter mask, wherein at least part of the sealing member of the filter mask comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall formed of the polymer, the enclosing wall including a face-contacting surface, the face-contacting surface having a form that is determined by the cavity of the mould and provides an anatomical fit with a user; and 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.

5. The method of claim 4, wherein a blowing agent may be injected with the polymer in step ii).

6. A sealing member for a filter mask, at least a portion of the sealing member comprising an internal chamber at least partially bounded by a resiliently deformable enclosing wall, the enclosing wall including an external surface, the external surface having a form that is determined by the cavity of the mould.

7. A sealing member for a filter mask, at least a portion of the sealing member comprising an internal chamber at least partially bounded by a resiliently deformable enclosing wall, the enclosing wall including a face-contacting surface, the enclosing wall having a plurality of gas pockets formed therein.

8. A sealing member according to claim 7, wherein the face-contacting surface provides an anatomical fit with a user.

9. The method of claim 4 or claim 5, or the sealing member of any of claims 6 to 8, wherein only the nasal portion of the sealing member comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall.

10. A method of manufacturing at least a portion of a sealing member for use in a respiratory mask, the method comprising the steps of: (a) providing a mould having a cavity, a polymer injection port and a gas inlet port; (b) injecting a polymer through the polymer injection port into the cavity of the mould; and (c) introducing gas through the gas inlet port into the cavity of the mould, thereby forming at least a portion of a sealing member of the respiratory mask, wherein the at least a portion of the sealing member of the respiratory mask comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall formed of the polymer, the enclosing wall including a face-contacting surface, the face-contacting surface having a form that is determined by the cavity of the mould and provides an anatomical fit with a user, at least in the nasal region.

11. The method of claim 10, wherein the sealing member of the respiratory mask comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall formed of the polymer, the enclosing wall including a face-contacting surface, the face-contacting surface having a form that is determined by the cavity of the mould and provides an anatomical fit with a user, only in the nasal region.

12. A method of manufacturing at least a portion of a sealing member for use in a respiratory mask, the method comprising the steps of: (a) providing a mould having a cavity, a polymer injection port and a gas inlet port; (b) injecting a polymer and a blowing agent through the polymer injection port into the cavity of the mould; and (c) introducing gas through the gas inlet port into the cavity of the mould, to form a sealing member, wherein at least the nasal region of the sealing member comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall formed of the polymer, the enclosing wall including an external surface, the external surface having a form that is determined by the cavity of the mould.

13. The method of claim 12, wherein only the nasal region of the sealing member comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall formed of the polymer, the enclosing wall including an external surface, the external surface having a form that is determined by the cavity of the mould.

14. The method of claim 12, wherein the blowing agent is a physical blowing agent.

15. A sealing member for a respiratory mask, at least a portion of the sealing member comprising an internal chamber at least partially bounded by a resiliently deformable enclosing wall, the enclosing wall including an external surface, the external surface having a form that is determined by the cavity of the mould.

16. A sealing member for a respiratory mask, at least a portion of the sealing member comprising an internal chamber at least partially bounded by a resiliently deformable enclosing wall, the enclosing wall including a face-contacting surface, the enclosing wall having a plurality of gas pockets formed therein.

17. A sealing member according to claim 16, wherein the face-contacting surface provides an anatomical fit with a user.

18. A sealing member according to claim 15 or claim 16, wherein only the nasal portion of the sealing member comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall.

Description

[0164] Embodiments of the invention are now illustrated, by way of example only, with reference to the following drawings:

[0165] FIG. 1 is a perspective view of a support frame of a first embodiment of a filtration mask according to the invention;

[0166] FIG. 2 is a side view of the support frame of FIG. 2;

[0167] FIG. 3 is a perspective view of a filter of the first embodiment of a filter mask according to the invention;

[0168] 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;

[0169] 30 FIG. 4b is the view of FIG. 4a, without the filter;

[0170] 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;

[0171] FIG. 6 is a side view of the first embodiment of a filter mask according to the invention;

[0172] FIG. 7 is a perspective view of the rear of the first embodiment of a filter mask according to the invention;

[0173] FIG. 8 is a schematic drawing showing the connection between the support frame and the filter material formed by overmoulding of the sealing member;

[0174] FIGS. 9a and 9b are perspective views of the front and rear of a further embodiment of a filter mask according to the invention;

[0175] FIGS. 10a and 10b are perspective views of the front and rear of a further embodiment of a filter mask according to the invention;

[0176] FIGS. 11 and 12 are perspective views of the rear of a face mask according to a further embodiment of the invention;

[0177] FIGS. 13a and 13b show front and rear perspective views of a filter mask 25 according to a further embodiment of the invention;

[0178] 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 30 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. A seal supporting member 31 extends downwardly from the centre of the bottom edge of the rim 11. The seal supporting member 31 is an arcuate shaped tab which depends downwardly from the rim 11 and curves towards the rear of the support frame 10. The support frame 10 is an integrally formed component, with all features manufactured in a single injection moulding step.

[0179] 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.

[0180] 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 frame. 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.

[0181] 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.

[0182] 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.

[0183] The sheet of filter material is positioned on the internal side of the support frame 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 frame/filter material assembly is shown in FIGS. 4a and 4b.

[0184] The support frame/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 frame/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.

[0185] 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.

[0186] A side view of a filtration mask 20 according to the invention is shown in FIG. 6.

[0187] The support frame 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 frame 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.

[0188] 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.

[0189] The sealing member 25 is formed of an elastomeric material. It provides a compressible region between the support frame 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.

[0190] The downwardly depending seal supporting member 31 abuts the seal in the chin region, reinforcing the seal in this region and enhancing the seal against the wearer's chin.

[0191] FIGS. 4a and 4b show the support frame/filter member assembly, with and without the filter material present respectively. The support frame 10 comprises a rim 11. The rim 11 has an inwardly extending shoulder 41 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.

[0192] A further 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.

[0193] A further 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.

[0194] A further embodiment of a face mask is shown in FIGS. 11 and 12. These figures show filter masks 200, 210 in which the seal has been at least partially manufactured by gas-assisted injection moulding such that, in the nasal region 201, 211 the sealing member comprises an internal chamber at least partially bounded by a resiliently deformable enclosing wall, the enclosing wall including an external surface, the external surface having a form that is determined by the cavity of the mould. The sealing member in the chin region 202, 212 comprises both an inwardly and outwardly depending lip portion relative to the peripheral edge of the mask body.

[0195] FIGS. 13a and 13b depict a filter mask 140 comprising a filter 141, a gas inlet 142, a mask body 143, a sealing member 144 depending from a periphery of the mask body 143, and first and second pairs of attachment members 145, 146, which are as described in relation to FIGS. 4a-b. The gas inlet 142 may be a spigot. An aperture in a first side of the mask body 143 houses the filter 141, while the gas inlet 142 is inserted through or integrally formed with a second side of the mask body 143, such that the filter 141 and gas inlet 142 are located on different sides of the wearer's nose and mouth, in use. During use, oxygen flows from the gas inlet 142 to the filter 141, washing over the wearer's mouth and nose, providing a continuous flow of oxygen and helping to draw away exhaled gases.