JP3126972B2 - CO 2 lower 2 absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a CO ₂ absorption device. In summary the present invention, the absorbent is intimately admixed with fibrous material, to provide a CO ₂ absorber that is formed as a sheet.

Technical Background conventional variety emergency breathing apparatus of the present invention, for example, word GETS felt (Werjefelt) U.S. patent protection hood having a CO ₂ absorbent that is described in No. 4,627,431 (hood), and 1987
Multilayer hoods with elastomeric neck seals have been developed as described in co-pending application Ser. No. 120,533, dated Nov. 13, 2013. Such devices generally include a protective hood, a source of oxygen and a device for removing carbon dioxide emitted by the wearer from the interior of the hood.

Lithium hydroxide (LiOH) is one of the compounds commonly used to absorb carbon dioxide. LiOH is often preferred as an absorbent because it provides acceptable absorption properties at an acceptable weight. Weight is an important consideration, especially for aircraft.

Lithium hydroxide is readily available in powder form, which provides a surface area that maximizes its effectiveness as an absorbent. However, powder dust is irritating to breathing and must therefore be isolated from the wearer.

Conventionally, by treating felt and LiOH in a ball mill, impregnating the felt with LiOH powder
A scrubber was configured. The resulting filled felt is a semi-permeable membrane coating that allows gas flow through the vessel while retaining LiOH.
velope). Sealing of such containers was also used so that the LiOH powder was evenly distributed within the coating.

While such existing technologies and designs are somewhat satisfactory, CO2 has been developed to provide a good balance between maximum absorption, isolation from the wearer, ease of manufacture, and low cost and weight. Efforts have continued to be made for _two- absorbent systems.

Summary of the Invention The present invention provides a CO ₂ absorbent that is easily and economically manufactured, and uniform distribution of the absorbent, to provide isolation of the absorbent from the excellent absorption capacity and user.

In particular, the present invention provides a powdered CO ₂ absorbent by weight relative to from about 0.1 to 70% by weight of homogeneously mixed with that CO ₂ absorber and fibrous material mixture. The absorber is arranged in the form of a sheet having a thickness of about 1 to 25 mm.

The purpose of the detailed description of the Invention The present invention is to powdered CO ₂ absorbent to provide a CO ₂ absorber that is blended with the fibrous material so as to mix uniformly and intimately with fibrous material. This formulation stabilizes the CO ₂ absorber and reduces the likelihood of dusting and irritation to the user. The fibrous material is about 0.
Powdered C so that it can account for 1 to 70% by weight
The composition ratio of the O ₂ absorbent and the fibrous material can be used in a wide range. Preferably, the fibrous material comprises about 0.5 to 50% by weight of the mixture, and especially about 1 to 10%.

Examples of powdered CO ₂ absorbent can be used in the present invention,
And alkali and alkaline earth metal hydroxides and oxides such as calcium hydroxide, calcium oxide, sodium hydroxide and barium hydroxide. Of these, lithium and sodium salts are preferred, and lithium hydroxide is particularly preferred. Generally, lithium hydroxide having a particle size of about 5 to 250 μm is used to best match the handling and absorption properties.

Powdered CO ₂ absorbent mixed with any fibrous material that can be molded into a mat or sheet by wet or dry techniques, or blended. Fibrous materials that can be used are polymeric fibers, such as polyolefins, polyesters and polyamides, having a fiber length of about 0.1 to 3 inches. Inorganic fibers can also be used.

The preferred fibrous material in the present invention is a fluorocarbon such as polytetrafluoroethylene. Fluorocarbon, commercially available as "Teflon TFE3512" from EI du Pont de Nemours, has been found to be particularly satisfactory when formed into fibrids. . Other fluorocarbons that can be used include those commercially available from DuPont as Teflon K10 fluoropolymer. Suitable polypropylenes that can be used are those commercially available from DuPont as "Pulp Plus" in the form of polypropylene fibrids.

Fibrous material can be used in fibrillated form, or a blend of fibrillated and powdered CO ₂ absorbent can be performed at the same time. While the use of pre-fibrillated materials such as the above-mentioned polypropylene fibrids is satisfactory, it is preferred to simultaneously fibrillate the material and blend it with the powdered CO ₂ absorbent. This simultaneous fibrillation and compounding results in an increased degree of embedding of the absorbent and a more stable structure.

After mixing the powdery CO ₂ absorbent with the fibrous material, it is formed into a sheet. Generally, the compounded material is dispersed in a fluid to facilitate molding. Fluid that may be used include any liquid such, does not dissolve the fibrous material or powdered CO ₂ absorbent under conditions of use as aliphatic and aromatic hydrocarbon solvents. However, naphtha is a preferred dispersing aid. The dispersion can be formed into a sheet using ordinary papermaking techniques.

In another method, the formulated CO ₂ absorber material can be pelletized and incorporated into a sheet structure in a dry method. For example pelletized CO ₂ absorber material is sprayed between two sheets of permeable membrane and then needle punched (needle-punch) process in order to provide structural stability.

Regardless of whether a wet or dry manufacturing method is used,
The powdery absorbent and the fibrous material in the sheet-like CO ₂ absorption device are uniformly mixed. For example, in a four square inch absorber, the relative concentrations of the absorbent and fibrous material do not change significantly above about 20% by volume.

The CO ₂ permeable membrane is preferably bonded to at least one surface, and especially both surfaces, of the compounded CO ₂ absorber. These layers have been found to improve the overall strength of the absorbent structure. A wide variety of membranes can be used so long as the membrane does not significantly impede the flow of air through the absorbent. Preferably, the fabric has a pore size of at least about 0.1 μm. Particularly satisfactory materials are those commercially available from DuPont as Nomex hydrolaced fabrics.

The membrane or fabric can be added to the compounded absorber before or after forming the sheet. For example, an absorbent sheet can be cast from the dispersion onto a layer of permeable fabric.

It is preferred that the CO ₂ absorbent sheet be mechanically treated to impart three-dimensional cohesion. For this purpose, ultrasonic bonding, heat bonding, suturing or hydrolacing using a suitable solvent is advantageously used. However, needling using conventional equipment such as a needle loom used for felt manufacturing is suitable for such a process.

The preferred manufacturing technique used in the present invention is LiOH
The powder is processed in a high shear mixer with a highly fibrillated fluoropolymer to obtain a dust-free material. The mass is then dispersed in a non-solvent using a high shear mixer and the slurry is deposited on the permeable sheet using conventional paper making machinery. The resulting sheet is dried and a second permeable sheet is placed on top. The entire sandwich structure is then mechanically treated, for example using a needle loom.

FIG. 1 shows a preferred configuration of the CO ₂ absorption device.
In this figure, a powdery absorbent 31 is intimately mixed with a fibrous material 32 and arranged in a sheet. The permeable fabric layers 33 and 34 are bonded to each surface of the mixed absorbent and fiber material.

The absorbent device of the present invention is constructed according to the general form specified in U.S. Pat. It can be used in a protective hood with the material, see both for reference.

A hood in which the present invention can be used is disclosed in U.S. Pat.
No. 431 can have a tubular configuration. Such a configuration is shown in FIG. 2, in which a tubular section 1 having a top end 2 and a bottom end 3 generally has continuous side walls forming the basic parts of the hood. The upper end of the tubular part is joined to a circular top part 5. A substantially annular resilient neck seal 6 is attached to the inner side portion of the bottom end of the tubular portion, the neck seal forming a closed system around the user with at least the user's head in it. It has an opening 7. The CO ₂ absorber 8 is housed in a coating 9 and adheres to the inner side wall of the tubular part of the hood. If an external air source is used for the hood, the arrangement preferably further comprises an inlet valve 10 and an outlet valve 11.

By incorporating or blending the powdered absorbent with the fibrous component in accordance with the present invention, the problems associated with dusting from the absorbent are substantially reduced. The use of papermaking technology allows for a uniform distribution of the powdered absorbent in the resulting structure.
The layers of fibrous sheet, and particularly suitable materials, increase strength and fire resistance. Suitable mechanical treatment ensures long-term mechanical integrity of the scrubber and prevents significant migration or settling of the absorbent powder in the scrubber. An expensive coating of foamed polytetrafluoroethylene is unnecessary because the powdered absorbent is very effectively bound by the fibrous material and the mechanical treatment. Instead, it can be inserted into a permeable covering with sufficient strength for applications intended for sandwich construction, and can be attached inside an emergency life support device.

 The invention will be further described with respect to the following specific examples.

Example 60 g of environmental grade anhydrous LiOH powder (6-14 Tyler mesh) was ground in a hammer mill to a particle size of about 10 μm. LiOH is converted to polytetrafluoroethylene (TFE) powder (“Teflon TFE35
12 "), 98% LiOH and 2% Teflon in a high shear Banbury mixer at 212 ° F for 5 minutes.・ Blender (Waring blend
er) and dispersed in one quart of a hydrocarbon solvent (VM & P naphtha) and blended until uniform. The mixture is further added to the VM with moderate agitation to ensure uniform dispersion.
Diluted to a final volume of about 3 gallons with & P naphtha.

A 0.9 oz / square yard, 12 inch by 12 inch sheet of permeable cloth (commercially available from DuPont as Nomex splunlaced cloth) was placed on the screen of a laboratory sized paper machine. . To achieve an effective LiOH loading of 60 g / sq.
/ Teflon / naphtha slurry was injected. A vacuum of 15 inches of mercury was applied, then the bilayer structure was compressed at 60 psi. The resulting paper was dried at 230 ° F for 1 hour. Finally, a second sheet of 0.9 oz / square yard, 12 "x 12" permeable splancrust nonwoven was added and the whole was sewn on a Dilo needle loom. Several identical composite sheets were produced as described above, and if necessary combined and cut (using an industrial sewing machine), 5 individual products; about 6 inches × One sheet of 12 inches, two sheets of about 6 inches × 24 inches, and two sheets of about 18 inches × 4 inches were made. The composite sheet was then incorporated into two individual melt blown polypropylene coatings (outer layer 35 g / sq m, inner layer 20 g / sq m). The coating was made using traditional sewing techniques. Buttonholes are provided to facilitate attachment to the smoke hood, and additional stitching (stitc
h) Lines were added.

The emergency life support hood incorporating the scrubber was tested and passed the test for aircrew described in the FAA action notice, A8150.2 dated September 1, 1987. The test mimics the workload of an aircrew while extinguishing an in-flight fire.

 The main features and aspects of the present invention are as follows.

1. is tightly mixed with about 0.1 to 70 wt% of the fibrous material of the mixture, about 1 to are arranged in the shape of a sheet having a thickness of 10 mm, the CO ₂ absorbing device composed of a powdered CO ₂ absorbent .

2. The CO ₂ absorption apparatus of claim 1, wherein the sheet has a permeable fiber cloth bonded to at least one surface thereof, and the fiber cloth membrane has a pore size of at least about 0.1 μm.

3. The CO ₂ absorption apparatus according to the above item 2, wherein the sheet has a permeable fiber cloth bonded to both surfaces of the sheet.

4. The CO ₂ absorption device of claim 3, wherein the permeable fiber fabric consists essentially of a polyamide spunlaced fiber fabric.

5. The CO ₂ absorption device of claim 3, wherein the permeable fiber fabric consists essentially of polyester spunlaced fiber fabric.

6. The CO ₂ absorption device of claim 3, wherein the permeable fabric consists essentially of polytetrafluoroethylene.

7. The above 1), wherein the powdered CO ₂ absorbent is selected from the class consisting of alkali and alkaline earth metal oxides and hydroxides.
The CO ₂ absorption device according to 1.

8. The CO ₂ absorption device of claim 7, wherein the powdered CO ₂ absorbent consists essentially of lithium hydroxide.

9. The CO ₂ absorption device of claim 1, wherein the fibrous material consists essentially of polytetrafluoroethylene.

10. fibrous material has a fiber length of about 1/8 to 1-1 / 2 inches, CO ₂ absorber unit according to 9.

11. The CO ₂ absorption device of claim 1, wherein the sheet has been mechanically treated to improve the stability of the absorbent in the fibrous material.

12. The sheet is mechanically processed by stab sewing,
_2. The CO ₂ absorption device according to 1 above.

13. The sheet is mechanically processed by stab sewing,
3. The CO ₂ absorption device according to the above item 3.

[Brief description of the drawings]

FIG. 1 is a sectional view of a preferred CO ₂ absorption device of the present invention. FIG. 2 is a perspective view of the protective hood, partially cut away to show the CO ₂ absorption device of the present invention housed in the hood.

Continuation of front page (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53/14 A62B 19/00 B01D 53/04 B01D 53/62 B01J 20/28

Claims (1)

(57) [Claims] 1. A tightly miscible with about 0.1 to 70 wt% of the fibrous material of the mixture, about 1 to are arranged in the shape of a sheet having a thickness of 10 mm, CO consisting of powdered CO ₂ absorbent ₂ CO ₂ absorber, wherein the CO ₂ absorber simultaneously fibrillates the fluorocarbon and mixes it with the powdered CO ₂ absorbent in a high-shear mixer, and converts the material thus mixed into a fibrous material and A CO ₂ absorption device characterized by being produced by dispersing in a non-solvent for a CO ₂ absorbent, forming the dispersion into a sheet, and removing the non-solvent.