GB1569812A - Respirator masks - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO RESPIRATOR MASKS (71) We, AMERICAN OPTICAL CORPORATION, a corporation organised under the laws of the State of Delaware, 14 Mechanic Street, Southbridge, State of Massachusetts, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The present invention relates to a respirator mask, and more particularly to a completely disposable respirator mask.

Conventionally, respirator masks, as dis- tinguished from surgical masks and the like, comprise facepiece devices into which filter cartridges are detachably mounted and wherein the latter may be discarded after use but leaving the facepiece device in need of sterilization or at least cleaning and occasional repair prior to subsequent use. Thus, unlike wholly disposable devices such as surgical masks, respirators for the protection against dust and pollution have heretofore been designed with the expectation of repeated use either by incorporation of long-lasting relatively heavy filter media requiring exhalation valves to relieve the strain of breathing or the aforesaid disposable cartridge-type devices.

While surgical masks of the disposable type have been known and used for decades, the respirator mask art which requires considerably greater and different respiration protection has been in need of a completely disposable item which is free of ungainly and costly breathing valves and/or related equipment and wherewith optimum respiratory protection against micron size dust particles and/or mists of pollutants can be accomplished with economically feasible complete disposal of the rmit after use.

According to one aspect of the present invention, there is provided a disposable respirator mask comprising a generally cupshape main body member made from a plurality of layers of filtering material including outer layers of filtering material of sufficient stiffness to be shape-retaining and an intermediate layer which comprises a lofty web of fibres the majority of which are unconnected and loosely intermingled, the said layers of filtering material being heat sealed together around the edges thereof to form a substantially rigid rim to the cup shape main body member, which is so shaped that when the mask is placed over the face of a wearer the rim fits about the nose, mouth and chin of the wearer, and a headband attached to the said rim.

According to another aspect, the present invention provides a method of forming a generally cup shape main body member of a disposable respirator mask from a flat multilayer filtering material having two outer layers and an intermediate layer which comprises a lofty web of fibres the majority of which are unconnected and loosely intermingled, comprising the steps of positioning the said sheet over a die cavity which has walls and a marginal shoulder together corresponding in shape and size to the cup shape configuration of the main body member of the said respirator mask, pressing the said sheet fully into the cavity and against said marginal shoulder with a pre-determined pressure lower than that capable of appreciably compressing the said intermediate layer of the filtering sheet, heating the portion of the said sheet spaced from the said shoulder of the cavity sufficiently to set the overall shape of the said sheet permanently to the shape of the cavity, the said heating being effected at a controlled temperature lower than that at which heat sealing and loss of loftiness of the fibres of the intermediate filtering web take place, applying sufficiently high pressure and temperature to the portion of the sheet adjacent the shoulder of the die to soften, compress and seal together the said multiple layers of the said sheet to form a rigid rim around the cup shape main body member of the respirator mask without affecting the layer of the sheet in the main part of the main body member of the respirator mask, and trimming the formed sheet about the said rigid rim at the shoulder of the said die to complete the main body member of the respirator mask.

A preferred embodiment of the respirator mask comprises a cup shape respirator mask body formed from a multilayer sheet by heat and pressure, and having a sealed edge contoured to fit about the mouth, chin and nose.

The multilayer sheet comprises a first, outer layer of polyester and vinyl acetate modified vinyl chloride co-polymer fibres, an intermediate lofty filtering web of vinyl acetate, polyester, rayon and glass fibre and a second outer layer of an intimate mesh of polyester fibre with a vinyl chloride binder. The firstmentioned layer is used to form the interior surface of the cup shape respirator mask body and all three layers are simultaneously com- pressively heat sealed together about their edges to form the said rigid rim. The heatsealed rim is preferably extended outwardly at preselected points peripherally of the respirator mask body into the form of tabs to which ends of elastic headbands are cemented.

A malleable, preferably metallic, nosepiece is cemented exteriorly over the nasal portion of the respirator mask body for use in retaining the nasal portion of the respirator mask body in a given dose-fitting relationship with the sides and bridge of the nose. This close-fitting relationship is obtained by pressing the malleable nosepiece toward the nose after the respirator mask has been placed upon the face.

The respirator mask body with sealed rim and headband tabs, but excluding the headbands and nosepiece, is preferably formed by pressing a section of the aforesaid multilayer sheet into a heated die cavity. Heat forming of the body configuration, and edge sealing at the rim are effected simultaneously and followed by peripheral shearing of the respirator mask body to the final size and shape desired.

A die having means for performing both of these operations in one stroke can be used.

There is thus provided a completely disposable respirator mask which, as distinguished from disposable surgical masks and the like, will provide for respiratory protection against micron size particulate matter and mists of pollutants. The respirator mask offers maximum comfort of fit, minimum breathing resistance and exceptional lighmess of weight.

In order that the present invention be more readily understood, an embodiment thereof will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front elevational view of a preferred embodiment of a respirator mask according to the invention; Figure 2 is a top plan view of the respirator mask illustrated in Figure 1; Figure 3 is a rear elevational view of the aforesaid respirator mask; and Figure 4 is a view, in vertical cross-section, of apparatus for manufacturing main bodies of respirator masks according to the invention.

Referring to Figure 1, 2 and 3, a respirator mask 10 comprises a main body 12 having a deeply cupped configuration. Body 12 is peripherally contoured and dimensioned so as to extend and fit closely over the nose, cheeks and chin to enclose a wearer's mouth and nostrils with ample free breathing space thereabout within the deeply cupped interior 14 (Figure 3).

The body 12 of the respirator mask 10 is formed from a fiat sheet of multilayer stock into the configuration illustrated in Figures 1-3 under heat and pressure. Flat stock (sheet 16) useful in producing respirator masks is illustrated in Figure 4. Sheet 16 comprises a first filtering layer 18 of web of polyester and Vinyon (Registered Trade Mark) vinyl acetate modified vinyl chloride co-polymer fibres, an intermediate lofty filtering layer 20 of Vinyon, polyester, viscose (rayon) and glass fibres and a further, outer filtering layer 22 formed of a mesh of polyester fibres in a polyvinyl chloride binder. The fibres along the surface 22 of the sheet 16 are so integrated in the final structure of body 12 as to provide the respirator mask 10 with a smooth, wrinkle-free, abrasionresistant outer (convex) surface.

A desirable highly efficient, but not restrictive, combination of fibres for the intermediate filtering section 20 may comprise the approximate proportions of 53% Vinyon fibres of 3 Denier fineness, 30% polyester fibres of 2.25 Denier, 5 % viscose (rayon) fibres of 0.75 Denier and 12% glass fibres of approximately 0.5 micron diameter.

Outer filtering layers 18, 22 and intermediate filtering layer 20 are edge sealed together around the whole of their peripheries to form face-fitting rim 24 for the main body 12. At preselected points about the rim 24, it is extended to form tabs 26 which are best illustrated in Figure 3. Headbands 28 and 30 are attached to these tabs, e.g. with hot melt adhesive. The soft rolled nature of the interior of body 12 adjacent rim 24 provides a gentle but highly effective face seal.

Extending over the uppermost nasal portion of main body 12 and affixed thereto, e.g. with hot melt adhesive, is a malleable chevronshaped, preferably metallic, nosepiece 32 (Figures 1 and 2). Using the nosepiece, the respirator mask 10 may be readily given a comfortable close fit over the bridge and sides of the nose by applying finger pressure to nosepiece 32 after the respirator mask has been placed on the face. The malleable but shaperetaining characteristtcs of nosepiece 32 permits optimum fitting of the respirator mask to all shapes and sizes of noses which are the most difficult portions of faces to fit and seal against. A 0.020 inch thick strip of aluminium approximately 0.24 inch wide may be used for this purpose.

Headbands 28 and 30 are intended to be extended around the back of the head and nape of the neck respectively at whatever exact positions are found to be most comfortable and/or desirable to the wearer. The headbands may comprise knitted elastic bands or other forms of adjustable strap means.

It is contemplated that the forming of main body 12 including sealed rim 24 and tabs 26 be accomplished in a single manufacturing operation and to this end, there is illustrated in Figure 4 a suitable die 34 which receives a sheet 16 of material to be formed into the main body 12 of the respirator mask.

Die 34 comprises base 36 which may be constructed of aluminium, stainless steel or other rigid heat-conductive materials. Base 36 is provided with cavity 38 which is finished (preferably smoothly) to the final size and shape desired for the main body 12 of the respirator mask 10. A shoulder 40 of a width equal to that desired of rim 24 of respirator mask body 12 is provided about the open end of cavity 38 in base 36. Base 36 is heated preferably with electrical heaters 42 of the wellknown cartridge type. It should be understood, however, that any desired form of heating means capable of producing a substantially uniform temperature along the surface of cavity 38 may be used.

A layer 43 of insulating material extending across base 36 prevents undue loss of heat by conduction from base 36 into die shoe 45 and/or other associated equipment not shown.

The mating or uppermost element of die 34, as it is depicted in Figure 4, comprises plunger 44 preferably formed of a soft natural or synthetic rubber, e.g. a commercially available silicone rubber known in the trade as 35 durometer RTV 700 Silicone which is manufactured and sold by General Electric.

Plunger 44 is so contoured and dimensioned as to provide an approximate 0.020 inch clearance completely about the periphery of cavity 38, i.e. adjacent shoulder 40 of base 36, when centered therewithin. It is reinforced by rigid mounting plate 46 which, in turn, is fastened to a second plate 48 by studs 50. Shims 52 are placed between plates 46 and 48 as means for adjusting the depth to which plunger 44 is permitted to enter cavity 38.

The plate 48 is provided with a depending internally shouldered margin 54 which is heated, preferably with cartridge heaters 56, for the purpose of forming the earlier mentioned heat-sealed rim 24 of the main body 12 of the respirator mask. This is accomplished by urging margin 54 of plate 48 toward shoulder 40 of base 36 and against sheet material 16. A pressure of from 500 to 600 lbs/sq. in. will produce desirable results.

Extending over plate 48 is a shear 60 which is used to trim the heat-sealed rim 24 of the main body 12 of the respirator mask to its final peripheral size and configuration. Shear 60 includes a depending annular blade 62 which is slidable along side 58 of plate 48 and, when moved downwardly toward base 36, performs this trimming function. The main body of shear 60 is connected to plate 48 by studs 64.

Shear 60 is provided with a layer 66 of heatinsulating material preventing undue transfer of heat from die 34 into its associated supporting and operating mechanism, only a portion of which (ram 68) is shown. It is to be understood that die 34 may be positioned in and operated by any suitable manual or automatically operated press mechanism.

Compression springs 70 normally retain blade 62 of shear 60 in the illustrated retracted position on plate 48. These springs are of such preselected resistance to compression as to allow a desired pressure, e.g. 500-600 lbs/sq.

in. to be applied by ram 68 before actuation of shear 60. This provides for complete heat sealing of rim 24 of the respirator main body 12 before cutting to its final shape and size.

The latter is achieved by adding enough pressure to die 34 by ram 68 to overcome the resistance of springs 70 to compression.

In the operation of forming main body IZ of respirator mask 10 with die 34, plunger 44 is initially completely retracted from cavity 38 whereupon fiat stock 16 is extended across the cavity opening. Plunger 44 is next lowered against stock 16 forcing it fully into cavity 38 until the aforementioned pressure of from 500 to 600 lbs/sq. in. is applied against the portion of stock 16 extending over shoulder 40. In the area of contact of plate 48 with fiat stock 16, plate 48 is heated to a temperature of from approximately 300"F to 325"F to form the sealed rim 24 of body 12 while the temperature of base 36 along the surface of cavity 38 is held to approximately 200"F whereby permanently to set the cupped shape of the body 12. Trimming with shear 60 is then effected and plunger 44 is retracted to permit removal of the finished main body 12 from die 34. The total body forming operation, including die opening and closing time, can be performed in less than 5 seconds.

The above method and apparatus make possible the manufacture of respirator masks at costs rendering their disposal after a single use economically feasible.

WHAT WE CLAIM IS:- 1. A disposable respirator mask comprising a generally cup-shape main body member made from a plurality of layers of filtering material including outer layers of filtering material of sufficient stiffness to be shape-retaining and an intermediate layer which comprises a lofty web of fibres the majority of which are unconnected

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. against. A 0.020 inch thick strip of aluminium approximately 0.24 inch wide may be used for this purpose. Headbands 28 and 30 are intended to be extended around the back of the head and nape of the neck respectively at whatever exact positions are found to be most comfortable and/or desirable to the wearer. The headbands may comprise knitted elastic bands or other forms of adjustable strap means. It is contemplated that the forming of main body 12 including sealed rim 24 and tabs 26 be accomplished in a single manufacturing operation and to this end, there is illustrated in Figure 4 a suitable die 34 which receives a sheet 16 of material to be formed into the main body 12 of the respirator mask. Die 34 comprises base 36 which may be constructed of aluminium, stainless steel or other rigid heat-conductive materials. Base 36 is provided with cavity 38 which is finished (preferably smoothly) to the final size and shape desired for the main body 12 of the respirator mask 10. A shoulder 40 of a width equal to that desired of rim 24 of respirator mask body 12 is provided about the open end of cavity 38 in base 36. Base 36 is heated preferably with electrical heaters 42 of the wellknown cartridge type. It should be understood, however, that any desired form of heating means capable of producing a substantially uniform temperature along the surface of cavity 38 may be used. A layer 43 of insulating material extending across base 36 prevents undue loss of heat by conduction from base 36 into die shoe 45 and/or other associated equipment not shown. The mating or uppermost element of die 34, as it is depicted in Figure 4, comprises plunger 44 preferably formed of a soft natural or synthetic rubber, e.g. a commercially available silicone rubber known in the trade as 35 durometer RTV 700 Silicone which is manufactured and sold by General Electric. Plunger 44 is so contoured and dimensioned as to provide an approximate 0.020 inch clearance completely about the periphery of cavity 38, i.e. adjacent shoulder 40 of base 36, when centered therewithin. It is reinforced by rigid mounting plate 46 which, in turn, is fastened to a second plate 48 by studs 50. Shims 52 are placed between plates 46 and 48 as means for adjusting the depth to which plunger 44 is permitted to enter cavity 38. The plate 48 is provided with a depending internally shouldered margin 54 which is heated, preferably with cartridge heaters 56, for the purpose of forming the earlier mentioned heat-sealed rim 24 of the main body 12 of the respirator mask. This is accomplished by urging margin 54 of plate 48 toward shoulder 40 of base 36 and against sheet material 16. A pressure of from 500 to 600 lbs/sq. in. will produce desirable results. Extending over plate 48 is a shear 60 which is used to trim the heat-sealed rim 24 of the main body 12 of the respirator mask to its final peripheral size and configuration. Shear 60 includes a depending annular blade 62 which is slidable along side 58 of plate 48 and, when moved downwardly toward base 36, performs this trimming function. The main body of shear 60 is connected to plate 48 by studs 64. Shear 60 is provided with a layer 66 of heatinsulating material preventing undue transfer of heat from die 34 into its associated supporting and operating mechanism, only a portion of which (ram 68) is shown. It is to be understood that die 34 may be positioned in and operated by any suitable manual or automatically operated press mechanism. Compression springs 70 normally retain blade 62 of shear 60 in the illustrated retracted position on plate 48. These springs are of such preselected resistance to compression as to allow a desired pressure, e.g. 500-600 lbs/sq. in. to be applied by ram 68 before actuation of shear 60. This provides for complete heat sealing of rim 24 of the respirator main body 12 before cutting to its final shape and size. The latter is achieved by adding enough pressure to die 34 by ram 68 to overcome the resistance of springs 70 to compression. In the operation of forming main body IZ of respirator mask 10 with die 34, plunger 44 is initially completely retracted from cavity 38 whereupon fiat stock 16 is extended across the cavity opening. Plunger 44 is next lowered against stock 16 forcing it fully into cavity 38 until the aforementioned pressure of from 500 to 600 lbs/sq. in. is applied against the portion of stock 16 extending over shoulder 40. In the area of contact of plate 48 with fiat stock 16, plate 48 is heated to a temperature of from approximately 300"F to 325"F to form the sealed rim 24 of body 12 while the temperature of base 36 along the surface of cavity 38 is held to approximately 200"F whereby permanently to set the cupped shape of the body 12.Trimming with shear 60 is then effected and plunger 44 is retracted to permit removal of the finished main body 12 from die 34. The total body forming operation, including die opening and closing time, can be performed in less than 5 seconds. The above method and apparatus make possible the manufacture of respirator masks at costs rendering their disposal after a single use economically feasible. WHAT WE CLAIM IS:-

1. A disposable respirator mask comprising a generally cup-shape main body member made from a plurality of layers of filtering material including outer layers of filtering material of sufficient stiffness to be shape-retaining and an intermediate layer which comprises a lofty web of fibres the majority of which are unconnected

and loosely intermingled, the said layers of filtering material being heat sealed together around the edges thereof to form a substantially rigid rim to the cup shape main body member, which is so shaped that when the mask is placed over the face of a wearer the rim fits about the nose, mouth and chin of the wearer, and a headband attached to the said rim.

2. A disposable respirator mask according to claim 1, wherein the said rim includes a plurality of tab portions to which ends of the said headband are attached.

3. A disposable respirator mask according to claim 1 or 2, wherein the said outer layers of filtering material forming the said cup shape main body member comprise an abrasion-resistant smoothly contoured layer of fibres in a binder on the convex side of the main body member and a web of integrated fibres on the concave side of the main body member.

4. A disposable respirator mask according to claim 3, wherein the said intermediate lofty layer comprises the combination of intermixed vinyl acetate modified vinyl chloride co-polymer, polyester, viscose and glass fibres.

5. A disposable respirator mask according to claim 4, wherein the approximate relative proportions of the said fibres are 53% vinyl acetate modified vinyl chloride co-polymer, 30% polyester, 5% viscose and 12% glass.

6. A disposable respirator mask according to claim 4 or 5, wherein said vinyl acetate modified vinyl chloride co-polymer fibres are approximately 3 Denier in fineness, the said polyester fibres are of approximately 2.25 Denier, the said viscose fibres are approximately 0.75 Denier and the said glass fibres are of approximately 0.5 micron in diameter.

7. A disposable respirator mask according to any of the preceding claims, further including malleable reinforcing means affixed to the outer convex surface of the said body member in the region thereof intended to extend over the nose of a wearer.

8. A method of forming a generally cup shape main body member of a disposable respirator mask from a fiat multi-layer filtering material having two outer layers and an intermediate layer which comprises a lofty web of fibres the majority of which are unconnected and loosely intermingled, comprising the steps of positioning the said sheet over a die cavity which has walls and a marginal shoulder together corresponding in shape and size to the cup shape configuration of the main body member of the said respirator mask, pressing the said sheet fully into the cavity and against said marginal shoulder with a pre-determined pressure lower than that capable of appreciably compressing the said intermediate layer of the filtering sheet, heating the portion of the said sheet spaced from the said shoulder of the cavity sufficiently to set the overall shape of the said sheet permanently to the shape of the cavity, the said heating being effected at a controlled temperature lower than that at which heat sealing and loss of loftiness of the fibres of the intermediate filtering web take place, applying sufficiently high pressure and temperature to the portion of the sheet adjacent the shoulder of the die to soften, compress and seal together the said multiple layers of the said sheet to form a rigid rim around the cup shape main body member of the respirator mask without affecting the layer of the sheet in the main part of the main body member of the respirator mask, and trimming the formed sheet about the said rigid rim at the shoulder of the said die to complete the main body member of the respirator mask.

9. A method according to claim 8 wherein said steps of pressing, heating, peripherally sealing and trimming of said sheet to form the said respirator mask main body member are performed in a single stroke with a die having means for performing both the heat sealing and the trimming operations.

10. A method according to claim 8 or 9, further including the step of attaching a headband to said respirator main body member.

11. A method according to claim 8, 9 or 10 further including the step of attaching malleable reinforcing means to the outer surface of the body member in the region thereof intended to extend over the nose of the wearer.

12. A disposable respirator mask substantially as hereinbefore described with reference to the accompanying drawings.

13. A method of making a disposable respirator mask substantially as hereinbefore described with reference to the accompanying drawings.