CA1115679A

CA1115679A - Filter material and a method of making it

Info

Publication number: CA1115679A
Application number: CA305,537A
Authority: CA
Inventors: Hubert Von Blucher; Hasso Von Blucher
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-01-31
Filing date: 1978-06-15
Publication date: 1982-01-05
Also published as: FR2416044B1; CH635519A5; DE2804154B1; GB2013102A; DE2804154C2; FR2416044A1; GB2013102B

Abstract

ABSTRACT OF THE DISCLOSURE
There is described a filter material made of open-pored foam base with adsorber particles on the pore walls and porous adsorber grains placed in addition in the pores.
For making the material the adsorber grains are forced into the foam material base wetted with water with an air current running up against the base. Such a filter material is characterized by a high degree of separating out damaging liquid substances without, however, decreasing the separating effect for vapors and gasses, even when the filter material is completely wetted or the degrees of movement of air through it is relatively high.

Description

~i~S~79 Background of the Invention (1) Field of the invention The invention relates tc a filter material of an open-pored, flexible foam material base and adsorber particles sup-ported by its pore walls, and to a method and an apparatus formaking such a filter material.
In the design and making of safety apparatus, safety or protective clothing for human use and for medical apparatus, air-conditioning, water-processing and aircraft design there is a need for flexible filters stopping vapors and gases going through them, which have a poisoning or otherwis~ damaging effect.

(2) The prior ~rt This is effected for example by an earlier filter material of this sort (see German specification 2,400,827) having the useful property that gases are readily able to go through it to a small degree.
If however in addition to damaging materials in the form of gas or vapor such materials in a liquid phase are to be come across, it has so far been necessary to have a heavy in-take filter, that is to say coming before the rest of the filter, for the absorption of liquid materials so that there was a loss of the noted properties of flexible sheet material such as a low weight, flexibility, little insulation of heat and high ventilation.
In particular in safety apparatus as used in very rough conditions, as for e~ample in fires, damage to persons or pro-perty in chemical plant, it has so far been necessary to use ~llS679 different sorts of apparatus each made for one sort of damaging material. Light safety clothing, designed to make possible operations in a thick mist of damaging material, is only able to be made of the filter material, noted earlier and having very good properties, to a limited degree, since liquid damaging material readily goes through this filter material. i -Account of the invention Taking these earlier designs as a starting point one pur-pose of the invention is that of making for such a development of the filter material of the sort noted that it is better at separating out damaging liquid substances without, however, the separating effect for vapors and gases being decreased, even when the filter material is completely wetted or the movement of air through it is possible to an important degree.
For effecting this and other purposes in the invention -the pores of the foam material base have porous adsorber grains in them in addition. These adsorber grains in the pores do not get in the way of the movement of gas through the pores to any important degree, while on the other hand, because of their porosity liquid are sucked up by them and damaging substances adsorbed. Even if generally all adsorber grains have taken up liquid to the full degree, the movement of gases through the filter material of the invention is not made harder to any im-portant degree.
So it is not only possible to make flexible air or gas filters which are able to take up a very great amount of liquids, but also to put to use the filter material as a liquid filter, because the effect of the porous adsorber grains gener-ally keeps liquid elements longer in the material. Furthermore the filter material of the invention is in a position to take up and keep within it great amounts of damaging liquid material

- 3 -.
, "

without the material going right through the filter.
If liquid damaging material goes into a vapor form in the adsorber grains, these vapors will be adsorbed by the adsorber particles on the pore walls.
So the filter material of the invention makes possible on the one hand a high degree of ventilation and on the other hand, however, the keeping back of skin and respiration poisons and gases and liquids of the sort attacking metals, by a sieve or filter action and surface-forces and/or to make them safe chemically.
The air and/or liquid moving past the adsorber grains is rolled by the foam-specific arrangement of the pore systems of the foam material base from one pore layer into the next, lower one, and they are forced past a large number of adsorber particles and adsorber grains, which have the effect of sedi-mentation sieves or filters and of - ~115~
separating damaglng material~ or substances from the ~~` alr and/or liquld~
It ls generally po~slble to have the size of the adsorber grains such that ln the pore~ having them more than one grain is arranged in each pore~ however in order to make certain that, even wlth the connectlon channels between separate pores of the foam materlal, base adsorber gralns are able to go through readlly out of one pore lnto the next one, in one form of the in-ventlon the adsorber graln~ are so ~lzed that they gene-rally take up the whole of the ~pace in the full-slze pore~ tthat ls to say the pore~ of the greatest sise) in the fonm materlal ba~e. If a partlcularly great amount of damaglng llquld materlal~ 1~ llkely, and a deslgn 1 needed ln whlch the foam material base i9 thin or the property of the fllter matorlal stopplng movement of air 18 not very lmportant, lt is generally possible to have adsorbor graln~ln more or le~o all pores of the foam materlal ba~e~ ln some ca~es lt ls of good effect as well to use a foam materlal ba~e, which, because lt has a great number of mlcro-pores, makes certain of a good ventilatlon effect ~o that all full-size pores are able to be taken up by adsorber grains wlthout very much decreaslng the ventllation effect. In a further development of the ln-ventlon lt i~ however of good effe~t lf only 20 to 50%
of the full-slze pores of the foam materlal ~ave the ad-sorber gralns ln them, so that about every second to every fifth pore has such an adsorber graln in it,though because of a large number of pore layers and whose lnsides are irregularly taken up by such adsorbers, a high degree of fllterlng 1~ made possihle without the movement of alr _ 5 _ , , , :

111S~i~9 belng stopped to any geat extent.
It 1~ generally posslble to have adsorber gralns wlth edges, ~uch as octahedra, tetrahedra, cubes or six-siaea blocks. In thls respoct the adsorber grain~
S can have thelr edges touchlng the pore walls so that between their flat walls and the curved pore surface ventllatlon channel~ are present ln all case~ however in further developments of the invention the use of graln form~ wlthout edges or wlth only a few edges i8 of good effect, as for example elllpsolds or cyllndors, slnce ~uch gralns are generally speaking more readily put ln the pore~ of the foam materlal ba~e. In thls res-pect, ~n a further development of the lnvention, it i~
of partlcularly good effect lf the ad~orber graln~ have generally the s~me geometrlcal form a~ the pores, though they aro smaller ln slze,so that ln oach pore a ventila- -tlon channel 1~ at a~l tlme~ formed between tho face of the adsorber graln and the wall face of tho pore and, in a furthsr form of the lnvention, u~e 19 more p~rticularly made of ~pherlcal adsorber gralns, whlch not only have the good effects noted earllor of odgo-froe grAlns but ln addltion are able to be mado slmply and at a low price wlth a hlgh accuracy and with qulte the rlght graln slze needed 80 that the use of the fllter materlal of the ln-ventlon for normal purpo~es i~ of good effect not only fortechnlcal but al~o for prlce rea~ons.
Generally speaklng lt 1~ posslble to make u~e of foam materlal bases with any desired pore size and to make the ~ize of the adsorber grains so a~ to go with them;
in one development of the invention u~e is however made more partlcularly of adsorber gralns wlth a diameter of 11156~9 about 0 01 to 0.001 mm and pore sizes as needed for such ~rains, slnce in the ca~e of such a ~lze a ~pe-clally good ventllatlon and filter effect was made pos~lble.
As a materlal for the adsorber graln lt i8 posslble to make use, for example, of kieselguhr, whlch ln ~ome cases has the necessary grain form in lts natural form.;
however ~n order to make certaln of a speclally good filterlng effect lt is partlcularly useful for the ad-sorber grain~ to be made of actlve carbon and for the adsorber particles, present on the pore wall~,.to be for-med by actlve carbon.
~n the case of low alr speeds and stationary . use of the fllter materlal it 18 generally likely that the adsorber graln~ wlll keep in the pores once they have been put in them~ however ln order to make possible u~e of the filtor materlal of the lnventlon ln movlng and shaklng structureR, and ln the case of high ventlla-tlon speeds, there ls a sugge~tlon, formlng part of a further development of the lnventlon, for the ad~orber grains to be placed stlcklng.to the wall~ of the pores ln whlch they are placed ~o that the dl~tributlon, made once and for all durlng maklng the materlal, of the adsor-ber gralns among the pores of the foam material base, ls kept more or less wlthout any changes,even in very rough condltlons of use.
Though every foam materlal wlth the necessary mecha-nlcal propertles and not of a sort attacked bv chemicals is generally ln order as a foam materlal base for the 3~ filter materlal of the invention, in a further develonment ~56~9 of the lnventlon the forma materlal base is formed as pol~urethane foam materlal, slnce this not only has all necessary mechanical and chemical pro~ertles~ but furthermore is able to be made with nore sizes and pore distributions seem to be of partlcularly good effect in filter material as used ln the invention; furthermore this foam material makes ~osslble a stlcklng on of the adsorber grain~ by means of heat proces~ing.
In order to make certaln that the fllter material of the lnvention 1~ not for example overly stretched so that at least for a short time lts pore shape and ~lze 18 changed with the outcome that even adsorber grains sticklng ln positlon are caused to come off and to come out of their pores, ln a further development of the lnventlon the foam materlal base has at least one flber layer,made for example of flbers placed ln positlon on foamlng,~o that the foam materlal base is not able to be stretched to such a degree that any change ln it~
flltering propertles takes place.
Such a flber layer ls more particularly in the form of a 1exlble grld running across the main dlrectlon of movement of material to be filtered. The grid ls able to put an end to any stretching ln nearly all directions of the grld plane because of the cro~sing-over of seoarate flbers, and ln this respect it ls of partlcularly good effect lf the grld ls so made that lts effective mesh si2e generally makes lt impos~lble for adsorber gralns to go through lt; the outcome ls that the adsorber grains are furthermore flxed ln position ln certain zones of the foam material base because of the placlng in it of grld layers, and they are kept in place even when the fllter materlal 6'~9 is heavily.loaded. In thls respect a partlcularly good effect 1B made posslble lf the flber layer ls placed on at least one of the facés of the foam material base ln order to make certaln that even ln the case of hea-vlly loaded fllters no adsorber gralns, for example, are able to come out of the foam materlal base to any lmportant degree, somethlng whlch ls llkely to make for a change ln the fllterlng characterlstlcs once lt takes place, If only one flber layer ls used, a particularly good effect ls made posslble lf the layer ls on the outlet face for flltered materlal ln order to make cer-taln that no adsorber gralns are pulled out of the support body by the flltered current of materlal. Thls ~s of partlcular lmportance ln the ca~e of breathlng mask8, because, unlike actlve carbon dust, not having a damaglng effect, trouble from adsorber gralns ls llkely lf they get lnto the eye~ or parts of the breathing ~ystem.
A partlcularly good effect ls furthermore made posslble lf the flber layer ls formed by knltted polyamide flbers, as 1~ the case as well ln the fllter materlal notod earller, because such flbers are not only not attacked by chemlcals, as needed, and are mechanically strong, but they are, as well, partlcularly well able to keep back the adsorber gralns ln the foam layer base.
The loose, knltted polyamlde flber structure ls more partlcularly bonded, welded, or flxed by adheslves on the face of the foam material base.
So the fllter material of the lnventlon is not only better at taklng up and filterlng liquids than the old ~l~S~'79 materlal, but furthermore - and thls ~ 8 very ~urprislng -has a very much better effect on filter~ng vapors and gases because of the further actlve face~ formed by the ad~orber gralns.
S For maklng the fllter materlal of the lnventlon it ls for example possible for the adsorber grains to be mlxed ln with the components of the foam material base before lt 18 cau~ed to foam, though a complete wettlng of the adsorber grain~ 18 not to be pos~ible.
Furthermore lt soems to be posslble for a layer of ad~orber graln~ to be placed all over the dry foam material base and then for vlolent vlbratlon to be cau~ed, for example by an apparatus producLngln sound so that the adsor-ber gralns are able to get lnto the foam materlal ba~e.
However ln oxder to have the mo~t even dl~trlbutlon of the adsorber graln~ possible ln the foam materlal base and not to have overmuch gralns at partlcular place~, there is the further development ln the lnventlon ln whlch the aasorber gra~ns are forced lnto the ~queous-wet foam mate-rlal base wlth an alr current runnlng towards lt. Becau~e alr ls readlly able to go through the foam materlal ba~e, a great part of the alr current will ln fact go through the foam materlal base and, on dolng 80, wlll make certaln that the adsorber gralns get through the lnslde of the foam materlal base and when adsorber gralns come out of the back-slde of the foam materlal ba~e,lt will be po~slble to see to what degree the base has taken up adsorber gralns.
In order to make certaln that there ls no later effect on the actlve carbon grains a~ for example becauqe the pore walls take u~ adsorber partlcles later, ln the lnventlon a foam materlal base 15 u~ed with the pore walls havlng the adsorber particles put on them beforehand and ln partlcular u~e is made of a polyurethane foam baQe with actlve carbon partlcles welded on lts pore wall~;
lt 18 pos~lble to make the polyurethane foam 90 hard or 80 able to glve way that on blowlng or forcing the adsorber graln~ into it later the graln~ go into the base to qulte the deslred degree. Then the ll~uid wet-ting the foam materlal base has the effect of a lubri-cant.
As noted it is possible to see from the degree to which the ad~orber gralns come out of the foam materlal ba~e lnto whlch they are forced, how far lts pores have taken up adsorber.grains. However once ln a test lt has been ~een what the blowlng tlme 1~ for a certaln thlck-ne~s of the foam materlal base and atcertaln alr current ~peed, because gralns come out of the back-~lde, lt wlll then no longer be nece~sary to see lf or when the ad~or-ber gralns come out of the foam materlal ba~e ln later full-~cale maklng of the filter material of the inventlon as an event controlllng the process. So lt 18 of parti-cularly good effect, ln order to make certaln that there 1~ no damage to the complete filter materlal, if a foam materlal base 18 used, whlch on lts face turned away from the blowlng alr current 18 coated wlth flber fabric, more particularly polyamide fiber knltted fabrlc which, a~ noted earlier, is not only of good effect becau~e of lts strength propertles as the fllter material, but fur-thermore put~ an end to any undesired widenlng out of the foam materlal base and, for thls reason, 1~ of help ln maklng certain that the ba~e evenly takes up the ad-~orber graln~.

......... . ..

` 1~1567~
- For making the adsorber gralns it seems to be ~ossible to make use of a graln-like materlal wlth a suitable graln form and slze, such as diatoms taken from kieselguhr and to put, if necessary, active carbon particles in the porous hollow s~aces of these gralns.
In a still further development of the invention it is however of ~artlcularlv good effect lf the ad-sorber gralns are made ~ynthetlcally from actlve car-bon by putting viscose dro~lets in a Lewis acid and then making them go through a carbonization process while being drummed all the tlme. On ~lacing the dro~-lets ln the acld the last-named goes through the vlscous materlal; the vlscose bodie~, stlll wet, are then placed ln a centrifuge and made to go through a carhonlzatlon ~rocess whlle belng drummed all the tlme so that at the end spherlcal adsorber gr~ln~ are made with the best ~peclflc ~urface area and which get a hard-porous surface ln the drummlng operatlon, whlle on the other hand inslde they have a porous sponge-like structure. The hard outer face makes the adsorber gralns very strong and in fact thls at the end makes possibie the blowlng of the grains lnto the foam material base wlthout the gralns belng broken because of thls because they are rubbed together, are knocked together or because they get out through the pore openings.
It is generally possible to place the foam materlal base, after the ~articles have been blown lnto it, in a weal solvent, which makes the face of the Pore walls soft 80 that the adsorber grains on the pore walls are caused to stlck to them.

~llS67~
However in order to make unnece~sary placlng in a solvent and the later washlng of the foam materlal base a number of tlmes for effcctlng washlng of the adsorber grains, in one form of the invention the foam material base with the blown-in particles is acetd upon by a temperature of 160 to 190 for thenmoflxlng of the adsorber grains on the lamellae of the foam pores, the adsorber gralns whlch are more particularly ball-shaped, belng ~oined at the point~ of touchlng on the foam material ba~e strongly enough,though however they have a free face whlch 18 not changed ln any way 80 that even wlth the stlcklng to the pore walls thelr effect 18 genorally not decreased.
To make pos~lble blowlng ln of adsorber gralns lnto the foam matorlal base the pore openlngs have to glve way to a certaln dogree for the adsorber gralns to be able to get lnto position. So in a further development of the invention a good effect can be gotten by vulcanizlng the foam material base, after the temperature processlng noted, for about 6 hours at 120C in order, on the one hand, to have the characteri~tic desired for tho fllter materlal produced and on the othor hand to make certain that the pore openlngs aro less able to give way, something whlch ln addltlon to th~ good flxing of the adsorber gralns wlll have the out-come of the gralns belng kept ln thelr pores.
For produclng viscose dropsfor the adsorber gralnslt 18, it seems, posslble for examplo to put thick vlscose on a turnlng dlsc, from whlch drops of different slzes are forced off b~ the centrifugal effect and after the last drummlng of the active carbon gralns, the grain~ are grouped ln different slzes, for example uslng an air classifylng .~ :

.

~ilS~i~9 apparatus. In order not to have the great amount of waste otherwise taklng place wlth such a method, in a further development of the method of the lnventlon for producing viscose drop~ of even slze, the viscose is extruded ln an extruder by pressure lmpulses coming one after the other, more partlcularly using hlghly compressed alr, and osclllatlon of the nozzle~ of the extruder is cau~ed for making certain that the drop~
are broken off. An extruder as used for example for making artificlal sllk 18 very good for thls purpose lf at lt~ lower end there is a number (500 and more~ of small nozzles5 by heating vlscose ln a li~uld form un~ing lmpulses, comlng one after the other, highly compres~ed alr ls forced into the meltlng zone of the extruder and through the nozzles in small amounts. By electro-magnetlcally produced vlbratlon of the nozzle groups these small amounts are broken off from a nozzle end as drops and then they are able slmply to fall ln an acid vessel placed under the extruder. Drops of even size are produced, whlch last-ly make for a grain size of 0,01 to 0.001 mm.
~ or producing spherlcal bodles of nearly complete spherlcal form of synthetlc actlve carbon from the drop-llke vlscose bodles after drumming and which have a speci-flc surface area of approxlmately 1200 m g (N: BET), in a further development of the invention a good effect is gotten by Rrocesslng the drops for approximately 10 minutes in the Lewls acid till they have taken up to 10% of the acid, In a further development of the invention the Lewis acid used is aluminium chloride or barium chloride, which have been noted to have a particularly good effect.

~15679 It i~ generally po~slble for the viscose bodles taken out of the ~ewl~ acld flrstly to be drled and then drummed so that any uneven parts, parts whlch are not round etc.,are rubbed off. However ln a further S development of the lnventlon a good effect ls to be had lf the vlsco~e bodles taken out of the Lewls acld are drummed whlle stlll wet and to a certaln deqree are able to bo plastlcally changod ln ~hape ~lnce ln thi~ case lt ls not only pos~lble to be certaln of the deslred sphQrlcal graln form without a very large amount of materlal belng rubbed off, but addltlonally the arain face 18 mad~ denser, somethlng whlch lastly makes cer-taln that the outer face of the lndlvldual adsorber graln~ 18 much harder than normal and ls not damaged by rubblng, whlle the lnner walls and the lnner part of the ~pherlcal gralns 18 ~tlll porou~ and ~oft and for thl~ rea~on had very good absorptlon propertles.
on drummlng tho vl~co~o bodle.~, ln a further dovelop-mont of the lnventlon, are heated shut off from the alr to 600C to 900C for carbonlzlng and then acted upon for 15 to 60 mlnutes wlth wat~r-vaporS thi.~ actlvatlon tlmo, whlch 1~ short in comparlson, makes for A vlolent movement and thorough mlxlng all tho time of the vlscose bodle~, whlch 18 noeded for a complete, even carbonlza-tlon and actlvatlon of tho gralns.
In place of water-vapor lt ls po~lble to u~e, ln a further form of the lnventlon, C02AlCl3 or BF3 maklng po~slblo the proce~slng time, wlth them, of 15 to 60 mi-nute~ only dependent on the de~lgn of the plant.
It 1~ furthermore to be noted that the product made 1~ tho more clean and free of dlrt materials lf more gas 1~1567~
or vapor is forced through the carbonlzation zone when carbonizatlon ls taklng place.
For maklng certaln of a partlcularly even, s~heri-cal graln form the inventlon make~ use of a drum apparatus for maklng the adsorber gralns, whlch has a concave turning centrlfuge cyllnder able to be shut, a lower ~late tur-nlng ln the opposite direction and making the lower end of the cylinder, a part near the lnner wall of the centri-fuge cylinder, more partlcularly made of razor-blade steel, for changlng the dlrectlon of the material and lnlet and outlet connections for carbonlzlng and actlvating gas or vapor. Once they have been put ln the drum apparatus turnlng over the vlscose bodies 18 caused by the centrlfuge cyllnder and they are forced agalnst the changlng dlrec-tion part, whlch makes them come clear of the rotatlng cyllnder wall and they are forced agalnst the lower plate turnlng ln the opposlte dlrectlon. From thls posltlon they are then agaln forced Agalnst the cyllnder wall and then come back on to the lower plate agaln.
For causlng thls process to take place approxlmately 1500 tlmes per mlnute, obe form of the drum apparatus of the lnventlon 18 80 deslgned that the lower plate and the centrlfuge cyllnder are aesl~ned for turnlnq in oppo-81te dlrectlons, each at a speed of about 1500 r~m.
For testlng samples of materlal,on the filter materlal of the lnventlon and materlal samples of normal ~heet fil-ter, each havlng a surface slze of 4 cm2, dlchlorodlethyl sulflde was dro~ped.
After 6 hours the amount of thls chemlcal whlch had gone through the fllter per cm2 was measured.

~1567~
Outcome of te~ts , Filter materlal of the lnventlon ~wo layers (ln micrograms) (a) 0.35 0.37 went through 1 cm2 (b) 0~25 0,27 went through l cm2 Filtor materlal of ~he inventlon Three layers ~a) 0.60 0.62 went through l cm2 (b) 0.57 0.45 went through 1 cm2 Normal shoe~ fllter materlal ta) 2,52 2.42 went through l cm2 (b) 2.05 2.00 wont through l cm2 Tho toloranco limlt whlch has to be kept to for fllt~r materlals 19 4 microgr~m~/cm2. So the normal sheot fllter only takes up half of the limlt for materlal ~olng through the flltor, whlle tho mat~rlal of the lnv~ntlon havlng spherlcal ad~orbers of synthetlc actlve carbon only t~kes up a tenth of thls, An ~ccount ln more dotall of one form of the inventlon i~ now given uslng the diagrammatlc drawing of the appllca-tion, in whlch the ~ectlon through a filter materlal i~
to bo seen, The flgure i8 not true 'to scale, Sheet materlal l of polyurethano foam materlal is bonded at lt~ one face with knittod materlal 5 of poly-amlde fll~ment~, so thAt ~ filter matorial ls made wlth a thlckne~s of approxlmately 2 mm.
Dlrectly on the pore walls of the foam materlal base 1 actlve carbon partlcles 2 are flxed by ~tlckln~- They are rosponslble for cleanlng alr golng through the fllter matcrl~l ln the dlrectlon of the arrow and freelng lt of poisons.

A part of the full-size pores 3, that is to ~ay the pores of great slze,of the foam material base has adsorber grains 4 ln it, that ls to say one grain ln each pore. ~he graln take~ up m~re or less the whole of the full-~lze pore 3 and lt 1~ flxed by a bondlng or stlcklng effect to the pore wall.
m e knltted material coating 5 has its me~h made ~o wide a~ to be smaller than the dlameter of an adsor-ber graln 4 and as a result the adsorber graln~ 4 are not able to get out of the foam material base 1 in the dlrectlon of the arrow.
In addltlon to vlscose lt ls posslble to use polymides, polyesters or polyethylene as an extrudate as well for m~klng the adsorber gra~n~.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A filter material made up of an open-pored flexible foam material base and adsorber particles supported by its pore walls, characterised in that in the pores of the foam material base porous adsorber grains are additionally placed.

2. A filter material as given in claim 1, characterised in that the adsorber grains are of such a size that they take up substantially the whole of the full-size pores of the foam material base.

3. A filter material as given in claim 1, characterised in that 20% to 50% of the full-size pores of the foam material base have adsorber grains in them.

4. A filter material as given in any one of claims 1-3, characterised in that the adsorber grains have a form like the form of the pores.

5. A filter material as given in any one of claims 1-3, characterised in that the adsorber grains have a form like the form of the pores and in that the adsorber grains are of spherical form.

6. A filter material as given in any one of claims 1-3, characterised in that the adsorber grains have a diameter of 0.01 to 0.001 mm.

7. A filter material as given in any one of claims 1-3, characterised in that the adsorber grains are made of active carbon.

8. A filter material as given in any one of claims 1-3, characterised in that the pore walls have the adsorber grains sticking on them.

9. A filter material as given in any one of claims 1-3, characterised in that the foam material base is made of polyurethane foam material.

10. A filter material as given in claim 1, characterised in that the foam material base has at least one fiber layer.

11. A filter material as given in claim 10, characterised in that the fiber layer is a flexible grid running across the main direction of movement of a medium to be filtered and its mesh size as far as it comes into effect, generally makes impossible any movement of the adsorber grains through the material.

12. A filter material as given in claim 10 or claim 11, characterised in that the fiber layer is placed on at least one of the faces of the foam material base.

13. A filter material as given in claim 10 or claim 11, characterised in that the fiber layer is placed on at least one of the faces of the foam material base in that the fiber layer is placed on the outlet face for the filtered medium.

14. A filter material as given in claim 11, characterised in that the fiber layer is made of knitted polyamide fibers, and this material is welded or adhesively fixed on a face of the foam material base.

15. A method for making filter material as given in claim 1, using a foam material base whose pore walls are covered by adsorber particles, characterised in that adsorber grains are forced into the foam material base, made wet by water, by blowing an air current against the base.

16. A method for making filter material as given in claim 1, using a polyurethane foam material base, on whose pore walls active carbon particles are welded and whose one face is covered with a fabric of polyamide knitted material, characterised in that absorber grains are forced into the foam material base, made wet by water, by blowing an air current against the base.

17. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place.

18. A method as given in claim 15 or claim 16, characterised in that the foam material base into which the grains have been forced is placed at a temperature of 160 to 190°C.

19. A method-as given in claim 15 or claim 16, characterised in that the foam material base into which the grains have been forced is placed at a temperature of 160 to 190°C and in that the foam material base is vulcanized after this heat processing about 6 hours at 120°C.

20. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place and in that the viscose for making the viscose drops is extruded in an extruder by pressure impulses coming one after the other and oscillation of the nozzles of the extruder is brought about so that the drops are broken off.

21. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place and in that the viscose for making the viscose drops is extruded in an extruder by pressure impulses coming one after the other and oscillation of the nozzles of the extruder is brought about so that the drops are broken off, and in that the pressure impulses coming one after the other are obtained by acting on the viscose with highly compressed air.

22. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place and in that the drops are put in the Lewis acid for about 10 minutes.

23. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place,and in that as a Lewis acid use is made of aluminum chloride or barium chloride.

24. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place and in that the viscose bodies taken from the Lewis acid are drummed while still wet.

25. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place and in that the viscose bodies taken from the Lewis acid are drummed while still wet and in that the viscose bodies on drumming for carbonizing and activation are heated to 600 to 900°C while shut off from air and then have water-vapor acting on them for 15 to 60 minutes.

26. A method as given in claim 15 or claim 16, characterised in that for making the adsorber grains viscose drops are placed in a Lewis acid and then, while drumming without stopping a carbonization process is caused to take place and in that the viscose bodies taken from the Lewis acid are drummed while still wet and in that the viscose bodies on drumming for carbonizing and activation are heated to 600 to 900°C while shut off from air and then have water-vapor acting on them for 15 to 60 minutes and in that in place of water-vapor CO2AlCl3 or BF3 is used.