WO1987007657A2

WO1987007657A2 - Textile yarn for producing a filter layer with an activated carbon base and use of said yarn

Info

Publication number: WO1987007657A2
Application number: PCT/EP1987/000294
Authority: WO
Inventors: Roland Fangeat; Pierre Christ; Alain Choserot
Original assignee: Filature De La Gosse S.A.
Priority date: 1986-06-04
Filing date: 1987-06-02
Publication date: 1987-12-17

Abstract

The textile yarn comprises an inert core consisting of a single filament without axial torsion, made from an inorganic material able to withstand an oxidizing atmosphere at a temperature of over 800°C. The core is surrounded by carbonized fibers and is activated in order to acquire a specific surface area/thread weight in excess of 1000 m2/g, the proportion of inert material in relation to the total weight prior to carbonization and activation being less than 30 %.

Description

Textile yarn for making a filter layer based on activated carbon and using this yarn

The present invention relates to a textile yarn for the production of a filter layer based on activated carbon, and to a use of this yarn.

It has already been proposed various solutions for making protective clothing incorporating activated carbon capable of adsorbing harmful substances contaminating the atmosphere.

This is how we know son formed of different organic materials which then smells charred and activated. Such yarns, however, lose almost all of their mechanical strength, which precludes their use for the manufacture of fabrics and consequently of protective clothing. Their use is therefore limited to the formation of filter layers associated with a support able to compensate for their lack of mechanical resistance.

In the field of clothing, two types of activated carbon supports have been proposed, one is the open-pore foam impregnated with pulverulent activated carbon, the other is the non-woven material also impregnated with pulverulent activated carbon. The disadvantage of foam is its thickness which makes it much less comfortable than a textile. Moreover, the specific surface area of the activated carbon, taking into account the presence of the inert support, is reduced to 700-300% while it is of the order of 1500-2000 m ² / g for the carbon fibers. As regards the impregnated nonwoven, the discomfort arises from the stiffness of the material which must be hot-rolled to give it a certain mechanical strength. In addition, the active surface of the active carbon reduced to the weight of the nonwoven hardly exceeds 400 m 2 / g, which is even lower than for the foam. .

Other solutions have been proposed to try to remedy these disadvantages. Thus, DE-Al-3,339,756 proposed to produce activated carbon fibers by coating a core of a high temperature resistant flexible material with a solution or a fused carbon substance which is then charred and activated. It is obvious that with such a solution, the mass ratio between the inert material of S e in mineral or metallic substance and the activated carbon gives an active surface per unit of mass extremely low. Moreover, the textile qualities of a yarn obtained with such fibers would be extremely poor both in terms of weight and flexibility of thread.

It has also been proposed in JP-A-59043134e in JP-A-59088940 to produce a wire with a ceramic or glass stainless steel core and unactivated carbon fibers based on acrylonitrile to form a fire resistant wire. However, in this case, the core is itself formed by a yarn spun from glass or steel fibers. Since such a wire, when it is made of glass fibers, has already 83 Tex, given the specific weight of the steel, a corresponding wire made of steel fibers alone will have 250 Tex, which excludes use to form a Sme of a thread for forming a clothing fabric. However, if to carbonize the fibers spun around the core, a core of ordinary glass fibers is sufficient, this soul would not resist the activation trai¬ ment that requires a temperature of 800-900 ° C in atmos Corrosive. Since in the solutions proposed by these documents the yarn is spun by the "open-end" technique, it is not possible to use a core formed of a monofilament, only a spun yarn relative¬ ment gros, as proposed by this document, is capable of withstanding the twisting induced by the spinning, considerably reducing the active speci¬ fic surface brought to the total mass of the yarn.

It therefore appears that there is currently no satisfactory solution for making a wire based on activated carbon fibers présen¬ a high specific surface, sufficient strength to allow to make it and the use. Such a yarn must obviously remain in the range of titles that can be used for the manufacture of fabrics used in the manufacture of protective clothing, for example as a lining. This title is to be considered considering an important loss of mass after carbonization and activation.

The object of the present invention is to overcome, at least in part, the disadvantages of the aforementioned solutions.

For this purpose, this invention relates to a textile yarn according to claim 1. It also relates to a use of this yarn according to claim 8.

Such a yarn has a high adsorptive capacity thanks to a large specific surface area. The textile properties of the yarn make the fabric permeable to air and water vapor, thus permitting physiological exchanges so that such a fabric can be used to enter the confec¬ tion of protective clothing . It therefore appears that the textile yarn according to the invention does not only have the physical and mechanical properties These fibers are necessary for the manufacture of a fabric having a high adsoption capacity, but this yarn also has the textile properties inherent in a fabric intended for clothing.

We will describe below, by way of example, different embodiments of the textile yarn object of the present invention.

As explained above, the textile yarn is best able to meet the requirements for making a fabric having a large surface area and therefore a high adsorption power. However, given the poor mechanical properties of activated carbon fibers, it is necessary to reinforce such a yarn by an inert element, obviously capable of withstanding carbonization treatments and especially activation of cabonized fibers, c. that is, at temperatures of 800 ° -900 ° C in an oxidizing atmosphere. These severe constraints exclude, for example, ordinary glass which does not withstand more than 600 ° C. They limit the range of useful filaments to materials such as stainless steel, boron, tungsten, inconel or silica. It is obvious that in this non-limitative list, but nevertheless limited according to the above-mentioned constraints, stainless steel is particularly advantageous in view of its price and the fact that it is capable of withstanding up to a temperature 1150 ° C in oxidizing atmosphere.

However, given its specific gravity of the order of 7.8, it is obvious that the proportion of steel by weight in the wire may become rapidly important, as has been seen in the aforementioned solutions. It has become apparent that the incorporation of such a core into a textile yarn intended for clothing is acceptable only in the form of an extremely fine monofilament. Such a solution is only feasible if the yarn is spun without inducing axial torsion of the core which would obviously be incapable of supporting such a torsion, normally applied to the core of a reinforced yarn, without breaking. It is obvious, therefore, that the conventional spinning modes on ring or open-end are excluded.

There are two different spinning processes that make it possible to spin a wire around a core without making it undergo axial torsion to it. One of these processes is called DREF and is implemented by a spinning machine built by the firm Fehrer. This process consists in winding fibers around a core. The other existing process is known as PARAFIL and is implemented by a spinning machine built by the firm Siissen. This method consists in surrounding a core with fibers arranged longitudinally and guiping them with a filament forming a helix with non-contiguous turns. It is obvious that in the PARAFIL process, the wrapping filament must also be made of a material capable of resis¬ ter at the activation temperatures of the above-mentioned carbon fibers. However, this filament may be chosen thinner than that of the core since it is not intended to participate in the tensile strength of the yarn.

The following table gives different examples of son made according to the invention. The parameters shown in this table refer to the wire before carbonization and activation. The indications relating to the parameters measured after carbonization will be indicated later in relation to the fabric produced, given that the carbonization occurs after weaving the yarn.

T A B L E A U 1 (Part 1)

TABLE 1 (continued)

Table 2 below provides additional information relating to the examples in Table 1 marked with an asterisk. The parameters indicated in this table were measured before carbonization. TABLE 2

In the case of Examples 4,9,14 and 19, the filament used to form the core consists of a W filament 13 μm in diameter on which boron is deposited by chemical decomposition of BCl ^ _A similar _proceg3U3 can be used to make the W / SiC filaments of Examples 5, 10, 15 and 20. These indications come from "Encyclopedia of Chemical Technology" Kirk-Othmer third edition Volume 6 page 696 (John Wiley and Sons). Given the low density of boron, it is possible to produce more resistant filaments than carbon filaments and therefore steel, resistant to high temperatures and whose percentage by weight can be substantially reduced compared to steel stainless or inconel, as illustrated by Examples 14 and 15 in particular. Considering the significant loss of mass of the organic fibers after carbonization, it is possible, thanks to such filaments, to substantially lower the weight of the carbonized fabric.

To take into account this significant loss of mass and volume resulting from the carbonization, the yarn of 250 Tex is woven very tight for example with a 12/12 weave fabric giving a fabric of about 610 g / m ² q _U i pass after charring and activation, at 280 g / m ² when the yarn comprises 80% of organic fibers and a stainless steel core of 20%. The resistance of this stainless steel core after the carbonization and activation treatments corresponds to more than 80% of the initial resistance. In the case of the use of boron filaments on W-core in a proportion of 5%, the weight of the fabric after carbonization and activation can be less than at 200 g / m ² with further improved strength.

Once the yarn is woven and carbonized, it is activated in oxy¬ dante atmosphere (carbon dioxide, water vapor in particular) at a temperature of 800 ° C - 900 ° C.

The fibrous structure of the carbonized material obviously confers an optimum active surface area with active charcoal and therefore an incomparable filtering power with respect to the solutions proposed up to now. This active surface in the examples given above is> 1500 m ² / g, based on the weight of the yarn and taking into account the inert mass. This active surface can be up to 2000 m ² / g or even 3000 m ² / g with W / SiC or W / B cores examples 14 and 15 representing only 5% of the weight of the wire before carbonization.

The presence of a metal core in the wire can provide a practical advantage in the desorption of activated carbon. The thermal conductivity of this core allows a distribution of heat throughout the fabric. It is also possible to consider heating the fabric by induction of a heating current in the electrically conductive core for the regeneration of the activity of the product.

The fabric made from the yarn can be used in the field of gas filtration (filter air purification) or in liquid filtration (purification of water, recovery of recoverable products).

The use of the yarn which is the subject of the present invention is conceivable for the manufacture of protective clothing intended for any person who will be in an environment contaminated by toxic or contaminating substances with respect to the epidermis, this also being the case. good for industrial protective clothing, than for other civilian or military applications. The textile properties of the yarn make it possible to make whole clothes likely to be worn without gene all day long.

Claims

1. Textile yarn for the production of a filtering layer based on activated carbon, characterized in that it comprises an inert core formed of a monofilament without axial torsion of an inorganic material capable of withstanding an oxidizing atmosphere to a temperature> 800 ° C., this core being surrounded by activated and activated carbon fibers having, after activa¬ tion, a specific surface area referred to the weight of the wire> 1000 m ² / g, the proportion of inert material relative to the total mass before carbonization and activation being <30%.

2. textile yarn according to claim 1, characterized in that the inorganic material forming the monofilament is conductive heat and / or electricity.

3. Textile yarn according to claim 1, characterized in that the tensile strength of the core is> 10 N before carbonization and activa¬ tion.

4. Textile yarn according to claim 3, characterized in that the resistance of the core to traction after carbonization and activation is> 80% to that of the same core before carbonization and activation.

5. Textile yarn according to claim 1, characterized in that the fibers are made from cellulosic, phenolic or polymeric materials and used separately or in mixture.

6. Textile yarn according to claim 1, characterized in that the fibers are arranged parallel to the core and covered by a monofilament of an inorganic material capable of withstanding an oxidizing atmosphere at a temperature> 800 ° C.

7. Textile yarn according to claim 1, characterized in that the fibers are wound around the core.

8. Use of the textile yarn according to claim 1 for producing a filter cloth, characterized in that a fabric is formed with the aid of this yarn before carbonization and activation of the fibers surrounding its core and that is then subjected to material to the carbonization and activation treatment of the organic fibers surrounding this soul.