DE102015012410A1 - Respiratory filter made of rigid activated carbon material - Google Patents

Abstract

The invention relates to a respirator made of a rigid activated carbon material, which is equipped as a molded body with a plurality of non-interconnected parallel channels. The channels are covered with metal compounds, preferably selected from zinc, copper, silver and / or molybdenum compounds. Furthermore, the invention relates to the use of the respiratory filters and respirators equipped with the respirator filters.

Description

The invention relates to a respirator made of a rigid activated carbon material, which is equipped as a molded body with a plurality of non-interconnected parallel channels. The channels are covered with metal connections. Furthermore, the invention relates to the use of the respiratory filters and respirators equipped with the respirator filters.

On the one hand, respiratory protection filters are classified as particle filters or gas filters, depending on whether the respiratory protection filters absorb or adsorb solids or gases. In addition, there are combination filters that provide protection against gases and particles. For respiratory protection filters in escape filter devices, a distinction is still made between fire escape and industrial refuge filter areas. While the filters of the fire escape devices primarily protect against carbon monoxide (CO), the filters of the industrial escape devices are designed to protect against various industrial gases. This is also reflected in the corresponding standards. For example, in the EN 403 (Respiratory protective device for self-rescue filter units with hood for self-rescue in case of fire) the required gas absorption capacity with respect to CO described, while in DIN 58647-7 (Respiratory protective equipment for self-rescue escape filter devices) the capacity for the substances known as ABEK gases is described. The abbreviation ABEK stands for gases and vapors of organic compounds with a boiling point> 65 ° C (A), inorganic gases and vapors except carbon monoxide (B), sulfur dioxide and other acidic gases and vapors (E) and ammonia and organic ammonia derivatives (K). Another spread than the German Standard DIN 58647-7 has the European Standard EN14387 (Respiratory protective devices - Gas filters and combination filters - Requirements, testing and marking) which also describe filters against ABEK gases, in this case for implements.

The structure of the known respiratory filters can be subdivided into those in which the filter material is present in the form of (a) granules or powders as packed fixed beds, (b) loaded nonwovens, and (c) monolithic filter bodies.

Of these known Adsorbensgefügen only the packed fixed beds have achieved commercial importance or have been developed so far that they meet the strict filtration requirements for gas and Dampfatemschutz. Practically all such fixed-bed filters for the respiratory protection are cylindrical, have a certain bed thickness and arranged in parallel planes inputs and outputs.

Up until now, mainly respiratory protection filters have been obtained, which are filled with granular activated carbon (activated carbon bedding). In addition, few filters with so-called fixed activated carbon are known, which either contain foam-supported activated carbon granules or are filled with activated carbon pads in which activated carbon granules are bonded by means of polymers. The activated carbon can be used both untreated and impregnated in multi-range filters.

All previously known systems have a relatively high resistance to breathing and are mechanically limited and therefore must be filled and fixed in a housing made of metal or plastic. The housing is provided with an adapter for connection to a mask or hood. Respirators are interchangeable but non-recyclable, producing waste with known drawbacks.

A disadvantage of using activated charcoal heaps is that when the activated charcoal bed is subjected to vibrations, the activated carbon particles rub against each other and cause abrasion. Also, the homogeneity of the bed can suffer from this.

Monolithic filter bodies containing activated carbon are known from the prior art. As a matrix for the activated carbon, open-cell foams, phenolic resins, polyurethanes, gypsum, paper carriers and carbon skeletons have been proposed.

In the US 5,078,132 Activated carbon moldings are proposed for gas mask use. These are self-supporting porous gas filter materials, which consist of a cast body of particles of the adsorber material and the thermoplastic binder.

But there are already activated carbon moldings with monolithic structure and a plurality of parallel channels ( DE 10104882 A1 ) has been proposed. Unlike the porous body, these can not be flowed through freely, but the flow is separated in the channels. The use of activated carbon molded articles with parallel channels has hitherto found little use.

An example of the use of non-monolithic filters with parallel channels for respiratory protection is the WO 2014/041144 A1 , The WO 2014/041144 A1 does not disclose that the parallel channels are covered with metal compounds (= impregnated).

The object of the present invention is to provide a filter for use as a respiratory protection filter which is easy to handle, provides a low breathing resistance and has a good and constant filter performance even with fluctuating gas volume flows.

Object of the present invention is further to reduce the impregnation costs compared to the impregnation of particulate activated carbon. In addition, it would be desirable to be able to dispense with the need for stabilizing housing necessary when using packed solid beds of granules or powders.

This object is solved by the subject matter of the independent claims. Preferred embodiments are subject of the dependent claims or described below.

The respirator filters according to the invention comprise a rigid activated carbon material, in particular of monolithic nature, and are equipped as shaped bodies with a plurality of non-interconnected parallel channels. The channels are covered with metal connections.

Monolithic means that the activated carbon molded body of one piece without forming (apart from a cutting) as a whole body z. B. is made by extrusion.

Activated carbon moldings with a multiplicity of parallel channels have the advantage that they allow the user of respirator filters to use a respirator mask with reduced respiratory resistance in comparison to masks with conventional gas filters and thereby enable a long-fatigue-free application of the respiratory protection.

The respiratory protection filter according to the invention can be used directly as a filter body due to their mechanical stability. On a complex housing, which would be disposed of with the filter material, can be dispensed with. By a simply designed slot on z. As a mask, it is possible to remove the adsorber from the mask and dispose. The drawer has a seal. The respirator can be encapsulated for better dimensional accuracy in the drawer with small amounts of plastic. By attaching the insert directly to the mask, the field of view can be significantly improved, also provides the filter on the gas mask only low mechanical points of attack, which is the working safety z. B. improved in tight areas.

The respiratory protection filters according to the invention have a very homogeneous structure due to their defined geometry and are characterized as a filter medium in respiratory protection systems such as respirators by a low pressure drop at high adsorption capacity. By impregnating the activated carbon moldings according to the present invention with impregnating the production of activated carbon moldings to protect against z. B. ABEK gases in respiratory filters.

In addition to the standard-compliant protective effect, such a respiratory protection filter surpasses all previously known low pressure drops and is therefore hardly noticeable for the wearer of respiratory protective devices, in particular respiratory masks, or requires only a fraction of energy in fan-assisted respiratory technologies. In portable respiratory protection systems, this makes it possible to use performance-optimized batteries, which means an additional noticeable advantage for the user.

• (a) Vermengen von zumindest Kohlenstoffpartikeln und zumindest einem Bindemittel unter Herstellung einer extrudierbaren Masse,
• (b) Extrudieren der erhaltenen Masse unter Erhalt eines Stranges mit Kanälen,
• (c) Aushärten des erhaltenen Stranges,
• (d) Carbonisieren der Stranges bzw. Strangabschnitten unter Erhalt von Kohlenstoff-Formkörpern bzw. Aktivkohle-Formkörpern,
• (e) fakultativ Aktivieren der carbonisierten Kohlenstoff-Formkörper, wenn keine Aktivkohle oder nur anteilig Aktivkohle eingesetzt wurde zum Erhalt eines monolithischen Aktivkohle-Formkörpers.

The respiratory protection filter according to the invention as a monolithic activated carbon molding can, for. B. be prepared by extrusion, comprising at least the following steps:

• (a) blending at least carbon particles and at least one binder to produce an extrudable mass,
• (b) extruding the resulting mass to obtain a strand of channels,
• (c) curing the strand obtained,
• (d) carbonizing the strands or strand sections to obtain carbon moldings or activated carbon moldings,
• (e) optionally activating the carbonized carbon moldings when no activated carbon or only partially activated carbon has been used to obtain a monolithic activated carbon molding.

The carbon particles are particles of carbon material whose possible further constituents pyrolyze during carbonation and at least partially convert to carbon. The carbon material may be activated carbon or coke from a variety of starting materials, for example. From wood, peat, stone fruit seeds, nut shells, coconut fibers, plastics, hard coal coke and / or brown coal coke.

The activation takes place z. By gas activation or chemically. In gas activation, the material is exposed to a temperature of 800-1000 ° C in an oxidizing gas stream such as water vapor, carbon dioxide, air or mixtures of these gases. When chemically activated, the material is treated at 500-900 ° C with chemicals such as dehydrating agents (eg zinc chloride, phosphoric acid) or by dry distillation. The crude activated carbon thus obtained is then oxidatively activated at 700-1000 ° C with steam or carbon dioxide, sometimes with air.

The extrudable mass may contain other pulverfömige ingredients such as clays, refractory materials or ceramic materials but also microspheres, glass fibers and / or carbon fibers. The extrudable mass may also have been prepared by adding a liquid phase, such as water.

Suitable binders are water glasses z. As with amorphous powdery silica, phenolic resins such as resoles or novolaks, furan resins, epoxy resins or polyester resins or mixtures thereof.

When producing the monolithic activated carbon moldings by extrusion, the viscous curable compositions are pressed out under pressure continuously from a shaping die. The activated carbon adsorber is obtained as a strand which is then separated according to the requirements in appropriate lengths.

Another way of producing the shaped body is to apply the activated carbon composition flatly with a corrugated structure and to form these surfaces by rolling into an activated carbon shaped body. Such a method is in the WO2011 / 041144 described. This is a non-monolithic embodiment.

The activated carbon molded body contains channels which are aligned parallel to each other, in particular substantially parallel to the longitudinal axis of the activated carbon molding or twisted against each other. The channels preferably extend completely through the activated carbon molded body through openings with openings on the end faces. Preferably, each channel opening on one end face corresponds to a channel opening on the other end face, without the channels being interconnected. The activated carbon molded body can, for. B. in the form of a cuboid or a cylinder.

• – mittlere Kanallängen von 17 bis 150 mm, vorzugsweise 25 mm bis 110 mm,
• – mittlere Kanaldurchmesser von 0,3 bis 2 mm, vorzugsweise 0,5 bis 1 mm und
• – mittlere Kanaldichten von 200 bis 800 cpsi, vorzugsweise 400 bis 600 cpsi. cpsi (cells per square inch): wird hier in der Bedeutung von Anzahl der Kanäle pro Quadratinch, auf der Eintrittsfläche bezogen, verwandt.

Particularly suitable are activated carbon moldings which have independently of one another:

• Middle channel lengths of 17 to 150 mm, preferably 25 mm to 110 mm,
• - Average channel diameter of 0.3 to 2 mm, preferably 0.5 to 1 mm and
• Medium channel densities of 200 to 800 cpsi, preferably 400 to 600 cpsi. cpsi (cells per square inch): is used here in the meaning of number of channels per square inch, based on the entrance surface.

By laminarly arranged channels in the activated carbon molded body succeeds surprisingly by filling the channels with the impregnating solution, the application or combination of metal compounds, eg. B. by immersion or flooding method, as a coating of the channel inner walls, so that their continuity is maintained.

• 1. Ansetzen der Imprägnierlösung,
• 2. Bereitstellen des Monolithen,
• 3. Imprägnieren des Monolithen durch Tauchen oder Durchleiten der Imprägnierlösung, und
• 4. Trocknung des Monolithen.

The impregnation takes place z. B. by at least the following steps

• 1. application of the impregnating solution,
• 2. providing the monolith,
• 3. Impregnating the monolith by dipping or passing the impregnating solution, and
• 4. Drying of the monolith.

According to one embodiment, a zinc- and molybdenum-containing coating of the activated carbon (impregnation) is carried out at least in the region of the channels of the monolithic activated carbon adsorber. The impregnation is preferably carried out with a soluble in water or in an aqueous ammonia solution metal compound such as a zinc and molybdenum compound, for. By stirring and dissolving zinc carbonate, ammonium chloride, ammonium carbonate and sodium molybdate. The monolithic activated carbon body is soaked with such impregnating solution and dried carefully, for. By hot / hot air until the water content of the impregnated monolith is below 3m% (m% = mass%, also referred to as mass fraction (w)).

• – Zink-Verbindung (A1) mit Molybdän-Verbindung (B),
• – Kupfer-Verbindung (A2) mit Molybdän-Verbindung (B),
• – Silber-Verbindung (A3) mit Molybdän-Verbindung (B).

Particularly preferred are the following adsorbent combinations:

• Zinc compound (A1) with molybdenum compound (B),
• Copper compound (A2) with molybdenum compound (B),
• - Silver compound (A3) with molybdenum compound (B).

However, combinations of A1 + A2, A1 + A3, A2 + A3, or even all members A1 - A3 with B are possible. A1 + B, A2 + B or A1 + A2 + B is preferred.

Copper compound (especially basic) is preferably used as the copper compound. Preferably, the impregnation or impregnation solution is free of chromium.

It is also possible to use a plurality of differently coated activated carbon adsorber one behind the other, so that the breathing air is flowed through by these successively.

• • 1 bis 8 m% Zink,
• • 0,1 bis 2,5 m% Molybdän,
• • 1 bis 10 m% Kupfer und/oder
• • 0,1 bis 2 m% Silber.

wobei vorzugsweise und auch unabhängig von der Konzentration der Metallverbindung weiterhin zumindest eines der folgenden Anionen: Chlorid, Phosphat und deren Gemische, und insbesondere in nachfolgenden weiter bevorzugten Konzentrationen auf dem Träger vorhanden ist:

• • 0,2 bis 6 m% eines Chlorids, berechnet als Cl, oder
• • 1 bis 12 m% eines Phosphats, berechnet als Phosphorsäure.

The respirator filter preferably has the metal compound individually and in combination in the following concentration (calculated with respect to the metal):

• • 1 to 8 m% zinc,
• 0.1 to 2.5 m% molybdenum,
• • 1 to 10 m% copper and / or
• • 0.1 to 2 m% silver.

wherein preferably and also independently of the concentration of the metal compound, at least one of the following anions: chloride, phosphate and mixtures thereof, and in particular in subsequent further preferred concentrations on the carrier is present:

• 0.2 to 6 m% of a chloride, calculated as Cl, or
• • 1 to 12m% of a phosphate, calculated as phosphoric acid.

According to one embodiment, the respiratory protection filters according to the invention are part of respirators, the facial part of which encapsulates the respiratory organs from the ambient air, in that the facial part rests sufficiently close to the face.

If the mask is to be worn for long periods of time without undue discomfort, the facial part is what and flexible designed. When the respirator operates with interchangeable filters, the filter typically consists of a filter element built into a housing. The coupling of the housing containing the filter element with the breathing air inlet of the respirator takes place by means of an adapter, with which the housing for the filter element is typically accommodated simultaneously in a complementary housing on the face part. However, the respiratory protection filter according to the invention can also be used directly, d. H. without complementary housing. The respirators can z. B. as a full face mask or as a half mask, which surround only mouth and nose, be formed.

Furthermore, the respiratory protection filter according to the invention can be used in closed and semi-closed breathing circuits, which serve to allow the user to a completely or partially independent of the ambient air breathing. This is the case, for example, with fire service work cycle equipment, for pits, but also escape devices, diving equipment or submarines. By guiding the breathing air in the circulation breathing gas can be saved. For this purpose, it is necessary to deplete the user produced and exhaled carbon dioxide and other pollutants.

Experiment examples:

Used chemicals: 25% aqueous ammonia solution CAS 1336-21-6 ammonium chloride CAS 12125-02-9 zinc carbonate CAS 3486-35-9 sodium CAS 10102-40-6

Impregnating solution 1:

In 1771.4 g of a 25% ammonia solution were dissolved with stirring and with gentle heating (about 35-40 ° C) 163.1 g of ammonium chloride, 235.1 g of zinc carbonate and 69.1 g of sodium molybdate.

Impregnating solution 2:

In 971.4 g of a 25% ammonia solution were dissolved with stirring and with gentle heating (about 35-40 ° C) 163.1 g of ammonium chloride, 235.1 g of zinc carbonate and 69.1 g of sodium molybdate.

Impregnating solution 3:

In 1314.3 g of a 25% ammonia solution was dissolved with stirring and with gentle heating (about 35-40 ° C) 163.1 g of ammonium chloride, 235.1 g of zinc carbonate and 69.1 g of sodium molybdate.

Impregnation and drying:

A monolithic activated carbon molded body with dimensions of about 50 × 50 × 110 mm (400 cpsi) (weight in each case about 95 g) was completely immersed in one of the impregnating solutions 1 to 3 for 5 minutes. Subsequently, the still dripping wet monolith was freed of excess impregnating liquid with a compressed air impact and passed through with 160 ° C hot air at a flow rate of about 85 L / min for about 30 min. The thus treated monolith after drying showed an increase in weight (loading) by the impregnation as shown in Table 1. The water content of the monolith after drying was about 2.5 m%.

Gas test:

The impregnated monoliths were gas-tight by means of sealing compound in housings, which in turn have an RD40 round thread connection, glued and the gas adsorption tested. The results of the service lives obtained are summarized in Table 1. Tab. 1 impregnating increase in weight Lifetime for C ₆ H ₁₂ Cl ₂ H ₂ S HCN SO ₂ NH ₃ G min min min min min min 1 7.3 70 25 35 19 20 39 2 15.6 39 83 89 58 39 98 3 12.5 73 74 50 47 27 88

The test was carried out according to EN 14387 : 30 L / min, 20 ° C, 70% r. F., at 1000 ppm of noxious gas, the resistance of the monolith (dimensions see above) under these conditions was in all cases less than 25 Pa (measured after EN 14387 ). This is a factor of 3 to 4 better than comparable gas adsorption filters for breathing air.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5078132 [0009]
• DE 10104882 A1 [0010]
• WO 2014/041144 A1 [0011, 0011]
• WO 2011/041144 [0027]

Cited non-patent literature

• EN 403 [0002]
• DIN 58647-7 [0002]
• Standard DIN 58647-7 [0002]
• Standard EN14387 [0002]
• EN 14387 [0047]
• EN 14387 [0047]

Claims (11)

Respiratory filter made of a rigid activated carbon material, wherein the respiratory protection filter as a molded body comprises a plurality of non-interconnected parallel channels and the channels are covered with at least one metal compound. Respiratory protection filter according to claim 1, wherein the shaped body has a pressure drop of 25 Pa and smaller when it flows through with breathing air. Respiratory protection filter according to claim 1 or 2, wherein the metal compound is selected from zinc, copper, silver, molybdenum compounds and mixtures thereof, in particular from zinc, copper, silver compounds and mixtures thereof in combination with a molybdenum compound , Respiratory filter according to at least one of the preceding claims, comprising at least one metal compound in each case in the following concentration (calculated based on the metal): • 1 to 8 m% zinc, 0.1 to 2.5 m% molybdenum, • 1 to 10 m% copper and / or • 0.1 to 2 m% silver. Respiratory protection filter according to at least one of the preceding claims, further comprising at least one of the following anions: Chloride, phosphate and their mixtures, preferably 0.2 to 6 m% of a chloride, calculated as Cl, or • 1 to 12m% of a phosphate, calculated as phosphoric acid. Respiratory protection filter according to at least one of the preceding claims, wherein the channels are additionally coated with an inorganic acid, in particular after application of the metal compound, in particular with phosphoric acid. Respiratory protection filter according to at least one of the preceding claims, wherein the channels are not covered with chromium or a chromium compound. Respiratory protection filter according to at least one of the preceding claims, independently of each other a) an average channel length of 17 to 150 mm, preferably 25 mm to 110 mm; b) a mean channel diameter of 0.3 to 2 mm, preferably 0.5 to 1 mm; and or c) a mean channel density of 200 to 800 cpsi, preferably 400 to 600, cpsi. Respiratory mask having at least one breathing air inlet having at least one respiratory protection filter according to at least one of the preceding claims. Respiratory mask according to claim 9, wherein the inserted respiratory protection filter from the activated carbon molded body has no additional housing. Use of the respiratory filter according to at least one of the preceding claims 1 to 8 as part of a respiratory mask for filtering respiratory air or in a closed or semi-open breathing circuit device.