EP0294707A2 - Breathing protection mask - Google Patents

Abstract

A multi-layer breathing mask (10) for covering the mouth and nose of a user is described, which has an outer layer (12), an inner layer (14) and a filter element (16) between the outer and inner layers (112, 14) . The filter element (16) has a particle filter (18) and an adsorber filter (20). The adsorber filter (20) can consist of a layer of foam material (36) or of several layers of foam material. The layers of foam material (36) can have different porosities. The at least one foam material layer has adsorber particles (38, 42) which are formed with at least one particle size.

Description

The invention relates to a multilayer breathing mask for covering the mouth and nose, with an outer layer, an inner layer and a filter element provided between the outer and inner layers.

Such a breathing mask is known for example from DE-PS 31 13 828. It is used to filter out particulate contaminants from the breathing air and, for this purpose, has an outer layer made of a thermoformable plastic material. Likewise, the inner layer of this respirator can be made of a thermoformable plastic material. The filter element in this respirator is a non-woven fabric. As a result of the construction of this respirator mask from an outer and an inner layer made of thermally deformable plastic material, this respirator mask is relatively expensive to manufacture. Another shortcoming of this respirator is that it takes up a certain amount of space at all times and not very much can be folded to save space. Likewise, this known respirator mask is not, or only to a very limited extent, suitable for removing gaseous pollutants.

A particle filtering half mask made of a flexible polymer foam is known from DE-PS 34 34 357. Although this respirator mask can be folded to save space, it is also only intended for the filtration of particulate pollutants and not for the filtration of gaseous pollutants.

The invention has for its object to provide a multi-layer respirator of the type mentioned, which is simple and collapsible in a very small space, and which is suitable not only for the filtration of particulate pollutants, but also for the filtration of gaseous pollutants, the filter properties depending can be set within wide limits according to the application.

This object is achieved according to the invention in that the filter element has a particle filter and an adsorber filter. The particle filter is advantageously arranged on the outside of the respirator and the adsorber filter on the inside of the respirator facing the face. In this way, the adsorber filter is secured against the ingress of pollutant particles. The particle filter and the adsorber filter are designed in such a way that the flow resistance during inhalation and exhalation through the breathing mask remains small.

The particle filter of the respiratory mask according to the invention preferably has a layer made of electret material. The layer of electret material preferably has polycarbonate or polypropylene microfibers. With the particle filter, the pollutant particles flowing through the outer layer into the respiratory mask are separated by physical, i.e. held on to the particle filter in particular by electrostatic forces and prevented from penetrating the respiratory mask.

The adsorber filter of the respirator mask according to the invention inevitably has at least one layer of open-pore foam material which is provided with adsorber material. This adsorber material can have activated carbon particles. In the adsorber material there is an adsorption or chemical decomposition of the pollutants entering the respirator. The adsorber material can be impregnated with various metals or metal compounds. By using appropriate metals or metal compounds, the catalytic decomposition of a wide variety of pollutants can be adjusted as desired in a wide range. The same applies in the military area for weapons. Table 1 below lists some catalysts and pollutants or warfare agents that are decomposed by these catalysts.

The adsorber material of the multilayer breathing mask according to the invention can be coated with polymers to retain moisture or water. These are, for example, polymers from the group consisting of polypropylene, vinyl chloride-vinylidene chloride copolymers, ethylene glycol polymetaacrylate, pyroxilin, collagen, acrylic acid-acrylonitrile copolymers, or the like.

When the respirator mask according to the invention is designed, the at least one layer of the adsorber filter made of open-pore foam material is provided with adsorber material which has at least two different particle sizes. The first particles can be spherical, granular or granular particles, and the second adsorber particles can be powdered or powdered, for example.

In the respiratory protection mask of the last-mentioned type according to the invention, the adsorber material can have first particles with a particle size that is between 0.1 times and 0.9 times the average pore diameter of the open-pore foam material, and the adsorber material can have second fine powder particles, the finely powdered second adsorber particles covering the free pore surface remaining next to the first adsorber particles. The first large adsorber particles, for example in the form of activated carbon spheres, result in a high storage capacity for pollutant gases and vapors. The second small adsorber particles ensure good adsorption kinetics.

The filter properties of the respiratory mask according to the invention can be set as desired within wide limits by suitable selection of the proportion of large first adsorber particles and the proportion of fine powder second particles which cover the free pore surface in addition to the first adsorber particles. That means high Storage capacity, a low sensitivity to moisture, a large inner surface of the activated carbon due to the large first adsorber particles, a small pressure drop through the respirator mask, i.e. a low breathing resistance, is possible through the use of the open-pore foam material. Through the combined use of large first adsorbers particles and fine powdery second adsorber particles, the adsorption kinetics and the storage capacity of the respirator can be adjusted as desired. Both the relatively large-volume first adsorber particles and the finely powdered second adsorber particles are preferably bound by means of a binder on the foam material and in the open pores of the open-pore foam material. The binder is applied, for example, by impregnating the open-pore foam material to the open pores thereof before the adsorber particles are introduced into the open pores of the foam material.

When the respirator mask according to the invention is designed, the adsorber filter can have at least two layers of open-pore foam material. These two layers of open-pore foam material can be layers with first larger adsorber particles and second finely powdered adsorber particles.

The at least two layers of open-pore foam material can have different porosities if the breathing mask is designed differently. The position of the adsorber filter with a smaller porosity can be provided with finely powdered adsorber particles, and the position of the adsorber filter with the larger porosity can be provided with adsorber particles whose Grain size in the range between 0.1 times and 0.9 times the average pore diameter of this layer. This results in a so-called progressive filter, in which the foam layer with the smaller porosity is preferably on the side facing the outside of the respirator mask , and on the opposite, inward-facing side of the respirator the open-pore foam material with the greater porosity is provided. Through a suitable choice of the porosities and the adsorber particle sizes, the pressure drop or the air passage resistance of the respiratory mask as well as the pollutant distribution and the storage capacity can be controlled and adjusted in almost any way.

The fine powdered adsorber particles are preferably present as an impregnation coating in the inventive respiratory mask. This impregnation coating achieves high adsorption kinetics, i.e. the odor and pollutants are quickly absorbed by the adsorber particles.

The outer layer of the respiratory mask according to the invention is preferably a flame-resistant and / or water or oil-repellent fabric. This fabric can be a cotton or glass filament fabric. For the military use of the respirator mask, it has proven to be advantageous to color the outer layer olive green. In particular when the respirator mask according to the invention is used in the military field, it has proven to be expedient for the outer layer to have certain reflection properties for infrared radiation. The infrared reflection should be below 28% at a wavelength of 1000 nm bear. With such a design, the user of the respiratory mask can be protected from infrared detection. Due to the flame-retardant finish of the outer layer, the respirator mask according to the invention offers good protection against the effects of flame, which is advantageous both when used in the military and also in the civilian sector, for example for firefighters, hotel fires, etc. The water-repellent or water-repellent design of the outer layer, which is done by water-repellent impregnation, also protects the respirator from moisture. This ensures a low pressure drop or a low breathing resistance in a simple manner. An oil-repellent impregnation ensures that any liquid warfare agent drips off and prevents such warfare agents from penetrating into the respirator mask.

In the respiratory protection mask according to the invention, the inner layer can be a cotton and / or polyester fabric or a nonwoven. The individual layers of the breathing mask, i.e. the outer layer, the filter element and the inner layer are preferably connected to one another along the peripheral edge of the breathing mask. This connection can be made by sewing, welding or the like. After the different layers have been put together at the edge, the respiratory mask can be cleaned with a bias tape.

In the case of the respiratory protection mask according to the invention, a foam strip is preferably arranged at least along part of its peripheral edge on the inside for sealing. This foam strip ensures a tight and tight fit of the respirator to the face of a user. The foam strip is provided in particular in the area of the nose and in the cheek area of a user adjoining it. The foam stripes can be glued to the inside of the respirator.

A flexible stiffening element can be provided in the respirator mask according to the invention. This stiffening element can be a metal strip that is sewn onto the respiratory mask by means of a strip of material made from the material of the outer layer. The bendable stiffening element enables optimal adaptation to all possible nose shapes and nose sizes, which further improves the sealing fit of a breathing mask on the face of a user.

In the respiratory mask according to the invention, an elastic holding element is preferably provided, which is fastened with its end sections to the respiratory mask. This holding element can be two rubber bands which are connected to one another in an H-shape by a central part. The rubber bands span the user's head of the respirator in such a way that the respirator fits tightly and sealingly against the user's face. The elastic bands extend around the back of the head and around the neck of the user and thus offer a comfortable fit and a secure hold. The holding element is designed in such a way that the respiratory mask can be quickly put on or taken off if necessary.

The breathing mask according to the invention can - as has already been explained - be used both in the civilian and in the military field. It can be worn by soldiers in the event of unexpected attacks with weapons as a temporary measure until the actual full face mask is put on. With the respiratory protection mask according to the invention, the time period can thus be bridged between the occurrence of the warfare agent and the putting on of the ABC protective mask. The respiratory mask according to the invention can be used in a simple manner to prevent soldiers from taking an incapacitated or lethal dose of warfare agents in the event of a surprise attack. As a result of its minimal physiological load, the respiratory mask according to the invention can also be used preventively during sleep. In the civilian field, the respirator mask according to the invention can be used for hotel fires, fire brigades, in industrial companies with a polluted atmosphere, etc. Since the respirator mask according to the invention is light in weight, it can also be worn for a long period of time for a wide variety of purposes. In addition, it has only a low breathing resistance and guarantees a high degree of speech transmission.

• Figur 1 eine Seitenansicht einer Atemschutzmaske, bei der die Halteelemente abschnittweise dargestellt sind,
• Figur 2 eine vergrösserte Darstellung des geschnitten gezeichneten Details II aus Figur 1,
• Figur 3 eine weiter vergrösserte Darstellung des Details III gemäss Figur 2,
• Figur 4 einen Ausschnitt aus einem Filterelement der Atemschutzmaske in einem stark vergrösserten Maßstab, und
• Figur 5 einen Ausschnitt aus einem anderen Ausfüh­rungsbeispiel eines Filterelementes der Atemschutzmaske.

Further details, features and advantages result from the following description of an exemplary embodiment of the multi-layer breathing mask according to the invention shown in the drawing. Show it:

• FIG. 1 shows a side view of a breathing mask, in which the holding elements are shown in sections,
• FIG. 2 shows an enlarged illustration of the detail II drawn in section from FIG. 1,
• FIG. 3 shows a further enlarged illustration of detail III according to FIG. 2,
• FIG. 4 shows a detail from a filter element of the respiratory mask on a greatly enlarged scale, and
• Figure 5 shows a detail from another embodiment of a filter element of the respirator.

Figure 1 shows a respirator 10 in a side view. As can be seen from FIG. 2, the respirator mask 10 has an outer layer 12, an inner layer 14 and between the outer and inner layer a filter element 16 comprising a particle filter 18 and an adsorber filter 20. The outer layer 12 is made of a flame-retardant, water- and oil-repellent cotton or glass filament fabric. It can be colored olive green, which is particularly required when using the respirator 10 in the military.

The inner layer 14 can be a cotton and / or polyester fabric or a fleece. The particle filter 18 is preferably provided on the side of the filter element 16 facing the outer layer 12. The adsorber filter 20 is preferably arranged on the side of the filter element 16 facing the inner layer 14. In this way, particles penetrating through the outer layer 12 are retained in the particle filter 18. Particulate filter 18 may be an electret material e.g. in the form of polycarbonate or polypropylene microfibers. The particles are held in place by electret material by electrostatic forces.

The multilayered structure comprising the outer layer 12, filter element 16 and inner layer 14 is sewn together or welded along the edge of the respiratory mask 10 and, after being plugged together, sewn together at the edge 22 with a bias tape (not shown). In the partial section of the edge 22 of the breathing mask 10 covering the nose and the cheek areas adjacent to the nose, there is a foam strip 24 on the inside of the breathing mask 10 intended. This foam strip 24 serves to further improve the seal between the respirator 10 and the face of the user of the respirator. A bendable stiffening element 26 is provided on the outside of the last-mentioned partial section of the edge 22 of the respiratory mask 10. This stiffening element is a formable metal strip that is sewn into a strip made of the material of the outer layer 12.

Two rubber bands 28 are sewn to the respiratory mask 10 with their two end sections. The two rubber bands 28 extend approximately parallel to one another and are connected in an H-shaped manner in their central part by a connecting element 30. The upper rubber band 28 extends over the back of the user's head when the respirator 10 is used, and the lower rubber band 28 extends along the user's neck. The holding element 32 of the breathing mask 10, which consists of the rubber bands 28 and the connecting element 30, is designed such that the breathing mask 10 can be quickly put on and taken off.

By means of the stiffening element 26, the respirator mask 10 can be adapted to any nose shape and nose size, in particular in the nose area, which further improves the sealing of the respirator mask on the face of the user.

In Figures 2 to 4, an adsorber filter 20 is shown in various scales, which consists of a layer of open-pore foam material. This foam material is in particular a polyurethane foam. The layer made of open-cell foam material has a certain porosity, ie the open pores 34 have a certain mean pore diameter which fluctuates within a relatively narrow range of dimensions. In comparison, FIG. 5 shows an adsorber filter 20 which has two layers of open-pore foam material, the two layers of foam material having different porosities from one another.

As can be seen from FIG. 4, adsorber materials with two different particle sizes are provided in the open pores 34 of the foam material 36. The first particles 38 are spherical in the embodiment shown. These first adsorber particles 38 are, for example, activated carbon balls. The first adsorber particles 38 are glued to the free pore surface 40 of the foam material 36. On the free pore surface 40 remaining free between the first adsorber particles 38, second adsorber particles 42 are fastened in the same way as the first adsorber particles 38. For fastening the first and second adsorber particles 38 and 42, the free pore surface 40 can be provided with an adhesive layer. To form the adhesive layer (not shown), the filter body 20 made of foam material can be immersed in a liquid adhesive until the entire filter body 20 is completely wetted with adhesive. The filter body 20 is then squeezed off, so that most of the adhesive is removed from the open pores 34. The first and second adsorber particles 38 and 42 can be held on the adhesive layer (not shown) remaining on the pore surface 40. The first, relatively large adsorber particles 38 result in a high storage capacity for gaseous pollutants without the flow resistance through the adsorber filter 20 being significantly increased.

On the other hand, the relatively small second adsorber particles 42 cause high adsorption kinetics, so that the odor and pollutants are rapidly absorbed.

To increase the contact time of the gaseous pollutants to be adsorbed on the adsorber particles, the adsorber filter 20 is not designed to have a single layer, as shown in FIG. 3, but rather to have two or more layers, as shown in FIG. The last-mentioned figure shows that the adsorber filter 20 is formed from a layer of foam material 36 with a large porosity, ie with open pores of large medium diameter, and of foam material 36 with small porosity, ie with open pores 34 of small medium diameter. This results in a so-called progressive filter, in which the comparatively large open pores 34 on the left side of the illustration with relatively large first adsorber particles and the comparatively small pores 34 of the foam material 36 shown on the right in this figure with fine powder or powder or spherical second adsorber particles with a diameter between 0.05 and 1 µm are provided. Of course, it is also possible to provide the layer of foam material 36 with the large open pores 34 not only with comparatively large adsorber particles, but - as shown in FIG. 4 - to combine large first adsorber particles 38 with small second adsorber particles 42. By suitable selection of the pore size and the size of the adsorber particles the pressure drop through the respiratory mask 10 or its air passage resistance, as well as the pollutant distribution and the storage capacity can be controlled in almost any manner.

A preferred embodiment of the respiratory mask 10 according to the invention is designed as follows:

The outer layer 12 consists of a flame-retardant and water-repellent cotton-glass filament fabric.

The particle filter 18 retains suspended matter from the ambient air by mechanical filtering before the air can reach the user. The particle filter 18 is designed as a three-layer composite, which consists of a carrier fleece, a middle layer of polycarbonate microfibers and a cover fleece.

The advantage of this electret filter over conventional particle filters is, on the one hand, an increased separation capacity, in particular in the respirable size range of the particles of 0.1 to 2 µm, and on the other hand, a lower pressure loss with comparable performance.

A combination filter is used as the adsorber filter 20. The combination filter consists of a pre-filter layer made of open-cell or reticulated (mesh-like) polyurethane foam with a pore size of 15-100 ppi (pores per inch) and a thickness of 3 mm. The polyurethane foam is impregnated with a paste that has the following components:
- 20 to 30 parts by weight of highly active powdered activated carbon coated with catalysts
- 40 to 65 parts by weight of water
- 10 to 20 parts by weight of binder and
- 5 to 10 parts by weight of thickener.

This pre-filter layer serves as a chemisorption filter.

• a) Aufbringen der mittelviskosen Paste durch Foulardieren (-Appretieren, Imprägnieren)
• b) Aufsprühen oder
• c) beidseitiges Pflatschen

The polyurethane foam can be impregnated with the activated carbon paste as follows:

• a) Applying the medium-viscosity paste by padding (finishing, impregnation)
• b) spraying on or
• c) Splashing on both sides

The combination filter also has one or two gas filter layers made of open-cell or reticulated (mesh-like) polyurethane foam with a pore size of 15 to 25 ppi and a material thickness of 3 to 6 mm. This polyurethane foam is impregnated with a binder. In a subsequent operation, spherical activated carbon 38 is fixed to the polyurethane foam 36. This gas filter layer has a high storage capacity.

The degree of hardness of the polyurethane foam can be adjusted by pre-impregnation with a binder. A defined application of binder can be done by spraying, padding, slapping or with rollers.

• a) elektrostatische Beflockung,
• b) definiertes Aufstreuen mit geringem Überschuss,
• c) definiertes Anschleudern, oder
• d) Durchführen durch ein Kugelbad.

There are various alternatives for covering the polyurethane foam with spherical activated carbon 38:

• a) electrostatic flocking,
• b) defined sprinkling with a small excess,
• c) defined spinning, or
• d) Performing through a ball bath.

The powdered activated carbon is a highly active powder coal with an inner surface of over 1000 m² / g (with a high proportion of macropores). The powder coal is finely ground so that 80% of the coal has a size of less than 40 µm. Powdered carbon can be impregnated with metal salts such as copper or chrome to destroy harmful substances.

Zeolites which are used instead of activated carbon or mixed with activated carbon can also be used as carriers for the impregnations.

The inner surface of the spherical activated carbon 38 is 600-1400 m² / g (with a high mesopore content). The diameter of the spheres can be 0.1 to 0.9 mm, an optimal ratio of adsorber support to adsorption kinetics being achieved when using spherical carbon with a diameter of 0.4 mm. The spherical carbon can be impregnated with metals or metal compounds, depending on the corresponding gaseous pollutants.

The following can be used as binders:
- modified acrylates
- polyurethanes
- silicone rubber
- polyvinylidenes
- polyvinyl chloride
- polyamide
- polyester granules or powder.

A white viscose fleece or a black polyamide charmeuse is used as the inner layer 14. Viscose fleeces are kind to the skin and offer special advantages in terms of filtering due to their high ability to absorb moisture. The microscopic effect of the viscose fleece creates an additional filtering effect due to the moist layer when inhaled, and the gas filter is protected from moisture during exhalation. Since from about 60% relative humidity of the loading air already a significant impairment of the adsorption capacity of the filter occurs, the lifespan of the respiratory mask 10 is increased considerably by using a viscose fleece.

The outer layer 12, the particle filter 18, the adsorber filter 20 and the inner layer 14 are welded or sewn together on both sides with single seams. The mask 10 should have as few seams and butt joints as possible due to the chemical protective performance. The edge 22 of the respiratory mask 10 is then cleaned with a bias tape over all material layers. The gas filter layer covered with spherical carbon 38 preferably lies loosely in the sandwich-like respirator 10 and is only attached to the edge.
As a seal of the mask edge 22, a laterally emerging polyurethane foam strip 24 is glued to the upper part of the mask directly at the edge 22. An all-round bead seal with foam cords can also be used as an edge seal. Other options for sealing are:
- sewing a sealing lip made of polyurethane foam onto the edging tape intended for overcasting,
- All around welding of the mask edge 22 as a flanged edge.

Rubber bands 28, which are sewn to the mask 10 and which are connected behind the head of the user by an artificial leather part 30, serve as the holding element 38 of the respiratory mask 10. The holder 32 is designed so that the respiratory mask 10 can be quickly put on or taken off. The rubber bands 38 can also be welded or riveted to the respiratory mask 10. The length of the rubber bands 38 can be changed, for example, by means of push buttons or by means of a Velcro fastener. The closure of the rubber bands 38 can also be designed similar to diving goggles.

Claims (23)

1. Multi-layer breathing mask (10) for covering the mouth and nose, with an outer layer (12), an inner layer (14) and a filter element (16) provided between the outer and inner layers,
characterized,
that the filter element (16) has a particle filter (18) and an adsorber filter (20). 2. Respirator mask according to claim 1, characterized in that the particle filter (18) has a layer of electret material. 3. Respiratory protection mask according to claim 2, characterized in that the electret material has polycarbonate or polypropylene microfibers. 4. Respirator mask according to claim 1, characterized in that the adsorber filter (20) has at least one layer of open-pore foam material (36) which is provided with adsorber material (38, 42). 5. Respiratory protection mask according to one of claims 1 to 4, characterized in that the particle filter (18) on the outside and the adsorber filter (20) is arranged on the inside of the respirator mask facing the face of a user. 6. Respirator mask according to claim 4, characterized in that the adsorber material (38, 42) has activated carbon particles. 7. Respirator mask according to claim 4, characterized in that the adsorber material (38, 42) is coated with polymers to retain moisture or water. 8. Respirator mask according to claim 4, characterized in that the adsorber material (38, 42) is impregnated with catalysts to destroy odors or pollutants. 9. Respirator mask according to claim 8, characterized in that the catalysts are metals or metal compounds. 10. Respiratory mask according to one of claims 4 to 9, characterized in that the at least one layer of the adsorber filter (20) made of open-pore foam material (36) is provided with adsorber material (38, 42) which has at least two different particle sizes. 11. Respiratory mask according to claim 10, characterized in that the adsorber material (38, 42) has first particles (38) with a particle size that is between 0.1 times and / or 0.9 times the average pore diameter of the open-pore foam material (36), and that the adsorber material (38, 42) has second fine powder particles (42), the fine powder second adsorber particles (42) covering the free pore surface (40) remaining next to the first adsorber particles (38). 12. Respirator mask according to one of the preceding claims, characterized in that the adsorber filter (20) has at least two layers of open-pore foam material (36). 13. Respiratory protection mask according to claim 12, characterized in that the at least two layers of open-pore foam material (36) have different porosities. 14. Respirator mask according to claim 13, characterized in that the position of the adsorber filter (20) with the smaller porosity is provided with fine powdered adsorber particles (42), and that the position of the adsorber filter (20) with the larger porosity is provided with adsorber particles (38) whose grain size is in the range between 0.1 times and 0.9 times the average pore diameter of this layer. 15. Respiratory protection mask according to claim 14, characterized in that the fine powder adsorber particles (42) are present as an impregnation coating. 16. Respirator mask according to one of the preceding claims, characterized in that the outer layer (12) is a flame-resistant and / or water or oil-repellent fabric. 17. Respirator mask according to claim 16, characterized in that the outer layer (12) is a cotton or glass filament fabric. 18. Respirator mask according to claim 16 or 17, characterized in that the outer layer (12) has reflection properties for visible light and / or for infrared radiation. 19. Respiratory protection mask according to one of the preceding claims, characterized in that the inner layer (14) is a skin-friendly knitted fabric, fabric or fleece. 20. Respiratory protection mask according to one of the preceding claims, characterized in that a sealing strip, in particular made of foam (24), is arranged on the inside for sealing along at least part of its peripheral edge (22). 21. Respiratory protection mask according to one of the preceding claims, characterized in that a bendable stiffening element (26) is provided on the partial section of the respiratory protection mask covering the nose and the cheek region adjacent to the nose. 22. Respiratory protection mask according to one of the preceding claims, characterized in that an elastic holding element (32) is provided, which is attached with its end sections to the respiratory protection mask (10). 23. Respirator mask according to claim 22, characterized in that the holding element (32) has two rubber bands (28) which are connected in an H-shape by a connecting element (30).

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