Note: Descriptions are shown in the official language in which they were submitted.
POROUS ME~IA TO SEPARATE GASES~ LIQUID DROPLETS A~/OR
SOLID PARTI~L~S FRO~ C-~SES OR ~APO~S AND COALESCE
3rief Description Of The Invention
This invention is that of (a) porous media, briefly called
gas-~apor mats or gas-vapor ~iltering or treating mats, having
good tensile strength and porosity to provide maintained good flow
-through ra~es but ye~ being suff ciently dense to enable filter-
ing finely divided solid particles and/or entrained liquid drop-
lets from aerosols or gases an*/or vapor s~reams, as well as
coalescing liquid droplets entrained in them, and also capable of
separating some gases from such streams, and ~b) the preparation0 of these mats.
m e gas-vapor trea~ing mats of the invention consist basi-
cally of (a) very small (e.g. average 6.3
microns) diameter gl~ss ~ibers composed of a plurality of fila-
ments and of short length about 6 . 35 mm long, and intermixed
therewith (b) so-called micro-bits of (i) an
expanded thermoplastic styrene-polymer and/or lower polyolefin
and/or (ii) a ~lexible foamed polyurethane, each of the members
(i) and (ii) being non-brittle in expanded form, and (c) a
minor amount of (i~ an organic binding agent insoluble in
cold water, but soluble in hot water and inert to the glass fiber
and the polymer micro-bits and any other constituent o~ the mat
as well as to the contents of the gaseous and/or ~apor stream to
~ich the mat is to be exposed, or ~ii) a cobeat (as described
further below) of wet lap cotton fibers and micro-bits. A gas
2~ separation embodiment o~ these mats also includes polyester
fibers and activated carbon.
A web OL merel~ glass fibers such as the Owens-Corning DE 636
(described in EXample 1 ~elow) bound with polyvinyl alcohol (98y3
hydrolyzed) was made but its use has been rather rostricted~ For
,' ,; : , -
exa~ple, it has been used as a battery plate separator and as the
base for roof covering to be coated o~er with tar. Howe~er, no
such web of glass fiber and polyvinyl alcohol (i.e called PVA)
has been known ~or use in any such treatment of fluids as described
above.
For many years various industries have been concerned with
troublesome solid particles or ~ine droplets of liquids, or harm-
ful gases released into working areas and often passing through
vents or smoke stacks into the outside atm~sphere, thus provoking
bothersome environmental problems. In some cases, it has been
merely dust particles from working with inorganio materials such
as recovering minerals from ores or ~rinding and polishing opera-
tions.
In other cases also involved are liquid droplets entrained
from chemical operations such as electropla~ing, spray coatln~ of
one kind or another or produc~ion of certain synthetic resins. In
still other situations it may be harm~ul gases, for exarnple, sul-
fur dioxide carried into the atmosphere as lrom burning of high
sul~ur con~ent fuel oils or bituminous coals. Produc-tion of a
polyphenylene oxide-polystyrene alloy poly~er involves release in
part of resin fines or pellets, dust particles and of oily plasti-
cizer droplets entrained apparently as an aerosol into the air.
Some attempts to overcome some of these problems have been
made by using (i) a filter medium such as a mat of glass fl~er.s
2~ held together Dy a phenol lormaldehyde resin binder~ or ~ii) glass
wool air filters in window openings or other outlets. Howe~er,
generally these filter media are bulky and yet not dense enough
to restrain the finer particles or gases, thus still allowing
undesirable fluid passage through them and thereby still to pass
out to the atmosphere. m en also some of these mats, among other
-2-
~ ,L rZ ~ 3 9
shortcomings, have an undesirably limited tensile strength resulting
in too frequen~ breaks requiring interrupting their use in undue
time-consuming repair.
Other attempts include use of electric charging precipitators,
such as the long known "Cottrell" ~ electric precipitators, but these
are costly to install, operate and maintain, and do not restrain
merely gases, for example, sulfur dioxide.
These disadvantages are o~ercome by the gas ~apor filter or
treating mats o~ the invention~ Then too, these mats o~ the in~en-
~ion show enhanced porosity and tensile s~rength o~er the above
described glass ~ibers and PVA webs used as battery separators and
in roof co~ering sheet~.
General Description_Of The In~ention
Considered broadly, the gas-vapor treating mats of the in~en-
tion comprise glass fibers (usually composed of a plurality of fila-
ments) more o~ten selected as about 6.35 mm (millimeters) long
and varying in diameter from about 3 to about 12 microns, and general-
ly more readily applicable as of about 6.3 microns, intermixed with
micro-bits of any o~ an expanded~ thermoplastic styrene polymer and
c~n expanded lower polyole~m whIch is the pol~er of an ethylenically
unsaturated hydrocarbon monomer having from 2 to 6 carbon atoms and a
flexible foamed polyurethane (each said polymer being non-br~ttle
in expanded form), and with the fiber glass and polymer micro-bits
being (a) bonded (primarily at their intersections) by a compatible
organic binder insoluble in cold water and soluble in hot water
(e.g at about 80C. as for PV~) and inert to the micro-bits, the
glass ~ib~rand any other mat constituent as well as the gases (in-
cluding any entrained liquid droplets or aerosols and fine particles)
that are to contact or be treated with the mat, or (b) held together
by a cobeat of wet lap cotton fibers and polymer micro-bits ~as
described below in Exarnple 5).
i~ . . . . .
,
~ lne mlcro- DitS can amoun-~ to from about 2 to about 50S~ of the
mat, and beneLicially ~rom a~out 10 to about 35%, and ad~antageously
from about 15 to abou~ 25~; and the compatible organic chemical
binder present at from about 2~ to about 10~ and beneficially at
from 5 to about 8%, or the cobeat of cotton fibers and micro-bits
being from 5.8 to about 11%; and with the glass ~ibers present in
an amount suLficient to make up the total of 100% content. m e
tensile stren~th of the mats varies from about 0~9 to about 5.34 kg.
per cm. and the porosity varies from ab~ut 152 to 914 liters per
lQ sq. dcm. (i.e. square ~ecimeter) a~ 0,43 kg.
~ ne micro-bi~s component o~ the gas-vapor treating mats of the
inven~ion are micro-bits of any of an expanded, thermoplastic
styrene-polymer or lower polyolefin9 non-brittle in expanded form,
or of a flexîble foa.ned polyurethane likewise non-brittle in expanded
form. These micro-bits of an expanded, ther~oplastic s~yrene-polymer
or lower polyolefin are more lully described (as in my
Canadian patent application ~erial ~lo. 295,012 file~ Janw~ 16, 1978,
now Canadian Pate~t No. 1,093,749, issued Jan~ 13, 1981), as an ~$~nde~ form
polymeriselected from a styrene polymer and a lower
polyole~in from polye~hylene to poly-methylpentene9 and characterized
by being in the form of micro-bits and (a) from about 40 to about
325 microns long and ~rom about 20 to about ~25 micrvns wide, (b)
from substantially completely to entirely completely free o~ intact
cells of the expanded polymer bit-pieces from which they ~ere pro-
duced, tc) substantially wi'hout any uniformity in outline of the
indïvidual micro-bits par~icles, and (d) in density from about 85
percent of, to about substantially the same as, *he specific unex-
panded poly~er from which there was pro~ided the aforesaid expanded
polymerO
~ese micro-bits of an expanded, thermoplastic styrene polymer
-4--
. ;
or a lower polyolefin are produced from so-called bit pieces of any
of the expanded the~mo?lastic, non-bri~tle in expanded form styrene
-polymers or lower polyole~ins as starting materialO By "bi~-pieces"
is meant any of the discirete free-flowing forms of any of these
s~yrene-polymers and lower polyolefins, such as (i) the various sizes
of granules made by cutting the respective extruded polymer into
fairly small lengths usually called pellets or crystal (as with a
styrene-polymer) or pellets or cubes of a polyethylene-polys~yrene
blend~ (ii) ~he various sizes OL styrenepolymer beads o~tained from
suspension poly~erization or othe~ise as by molding the particles
obtained by disintegrating any of these different polymer forms,
(iii) the so-called l'grind" including the coarsely ground molded
polymer or waste or o~her scrap such poly~er of various sizes9 e~
3.175 millimeter (i.e. ml.) thick, 6.35 ml. wide, and 9.5~5 ml. long,5 and (iv) any other small sized shapes of any o~ them.
m e preparation and properties of flexible polyurethane foams
are described, for ex~mple, in the "Handbook of Foamed Plastics",
Bender, Rene ~., Section X9 pp. 173-236, Lake Publishing Corporation,
Libertyville, Illinois, ~S.A. (1955), 'IPolyurethanes: Chemistry
and Technology, Saunders & Frisch,Chapter V,I, Part II, m ~erscience
Publishers, New York, N.Y., U.S.A. (1964)1 and "The Development and
Use of Polyure~hane Foams'l, Doyle, E.N., pp. 233-256, McGraw Hill
~ook Company, ~ew York, N.Y " U.S.A. (1971).
m e flexible polyurethane foams useflll to proYide foamed poly-
ure~hane micro-bits preferably should be no greater than 72.14 gm-
per liter in density, beneficially ranging from about 360 to
about 120 gm. per liter, and show excellent recovery
af~er 75% de~lection with approximately less than 15~ loss in height
(as determined by American Society of Testing ~aterials D-1564-64T).
The flexible foam polyurethanes are no~ ob~ained in the fore-
, ~
~,. J :
going same bi~-pieces ~orr.s as are the styrene-polymers and lower
polyolefins, bu~ r~her in continuous ~oamed blocks as a resul~ of
the reaction that pro~ides the polyurethane. Accordingly, the
foamed polyurethane blocks first are shredded into bit-pieces (for
5 example, similar to how they may be prepared for use in stuffing
into various articles).
The.foamed polyurethane micro-bits are more fully
described as comprising broken and interconnected strand portions
from adjacent cells of the flexible foa~. which strand portions
show substanttally total absence of intact cells and cell windows
and are tripodal particles with generally uneven length legs, the
strand portions having ~ook-like projections, indentations and
flutes resulting from ~y destruction of the cells and cell windows
of the starting ~lexible foam.
~ ~ . . . . . . . . .
The micro bits OL any expanded tnerr~oplastic~ non-brittle in
expanded form s~yrene-polymer or lower polyolefin or flexi~le ~oamed
polyure~hane are prepared by disi~tegrating the respective s~arting
expanded polymer bi~-pieces in a com~inuti~g machine such as that
produced by Fi~zpatric~ Company (of 832 Industrial Drive9 Elmhurst,
Illinois 60120, U.S.A.) according to their Bulletin No. 152 copyright
1968 using the broached fixed blades (identified therein by ",Co~e
DS225") to replace the blades or other com~inuting elements, mounted
~or ro~ation in ~he c~mminu~ing chamber model DASo6t both shown on
that bulletin's page 5. That chamber is liquid-tightly capped, Lor
example, by a cover such as shown in their Code M4436 or Code 1~A44D6
(upper half of page 3 of ~heir Bulletin 152).
m at model DAS06 comminuting chamber is recta~gular in hori-
zon~al cross-sec~ion and has a pair o~ opposed parallel entirely
~ertical walls integrally joined at each o~ their opposite end~ by
a separ~te one of a pair of opposed vertically arcuate walls each
with its convex face exposed to the exteriorO
Sixteen identical, slat-shaped comminuting arms are separately
removably but fixedly carried with their snugly adjacent to one
another bases encircled about, and keyed to, the operating sha~t
and in~ermediate its free ou~er mounting ends. m ese arms extend
radially out Lrom the sha~t (P,g. 127 mm. from its axis to the outer
, end of each arm) with the ~irst of each consecuti~e ~our o~ them
/ extending horizontally toward one arcuate wall, the secon~ of each
four extending vertically, the third four of them extending toward
the other arcuate wall 9 and the ~ourth four o~ them extending verti-
cally downward.
Each ar~ is rectangular in cross-section in a plane running
through the en~ire length of the shaft's axis and o~ that arm, and
OL each arm 180 removed from it. The outer end of each arm meets
a~ right angles with its two wider sides (5.4 mm. width) and its nar-
row or impaGt side (9.5~5 mm. wide) facing ~he direction o~ rota~ionO
m at narro~l side also meets at right angles with the two wider sides
which are parallel to one another for most o~ their width and with
the trailing thiTd of their sur~aces tapering to one another and
terminating in the kni~e edge of their trailing end.
~ ach free expo~ed end of the shaft extends through its respec-
tive stuffing box in its neighboring one o~ the two parallel vertical
walls on through a bearing carried on a respective trunnion af~ixed
to the machine's foundation and spaced outwardly awa~J from the respec
tive wall. A driYing pulley is mounted on each end of the shalt ex-
tending outwardly ,rom its respective mounting trunnionO
The bottom o~ the commi~uting chamber i5 an exchangeable dish
-shaped, arcuate screen cur~ed convexly downward with an inside radius
~0 (from the axis of the operating sha~t~ equal to the length of a
~ $ ~ ~
comminuting arr.l plus ~ mm. clearanCe . The screen's overall
rec~angular peripheral o~ening has such dimensions and shape as to
enable ~t to be removably ~itted in a li~uid-tight engagement ~Jith
the bottom of the four walls of the comminuting chamber.
m e screen has s~aggered ro~s of~ for example, circular holes
varying in diameter as from 0.102 to abou~ 3~175 mm. and closely
spaced to one another with sufficien~ space between them for the
screen ~o h~ld up under working conditions. 3
EXce~t ,or its starting material feed hopper inlet at one
side o~ it, the rest of the chamber's cover is arcuate and convex
upwardly with a radius (from the axis of the operating shaf~) suffi~
cien~ for -~he rotating arms to have a 0.762 mm. clearance from the
in~arlly facing surfaces of a plurality (e.g. thr~e) pre-breaker
bars (about 20.32 cm. long and 6.35 mmO wide) protruding for ~.175
~. along their entire length into the interior of the comminuting
chamber, and ex~ending spaced apart from one another and parallel
to the axis of the operating shaft.
Thè selected driving pulley on the operating shaft is connected
by driving belts extending from a motor shaft drive pulley and can
be operated at speeds embracing the range of from about 4700 to about
8000 r.p.m., and more effectively ~rom about 5000 to about 7500 r.p~m
m e in~en~ion includes also a form of these mats, whic`n can
be called the gas-vapor adsorption filtering or treating mats. ~nese
include the basic or primary constituents ta) the glass fibers, (b)
~5 the micro-bits, and (c) the organic bin~ ~ agent, each being generally within
its earlier above recited respective range relative tv the others o~
them, together with an amount of finely diYided activated carbon (as
primary gas-adsorbing agent) below ~hat at which undesirable dustin~
of~ of carbon particles can occur, a suf~icient amount o~ the cobeat
to serve to restrain the carbon particles against dusting off, and
. ~
, .
2~
~n amount of a ~iber-forming terephthalate polyester su~licient to
hold the mat ' s tensile strength within its earlier above recited
range without undesirable lowering o~ the mat's p~rosity~
Thus, ~or example, in addition to its three primary cons~ituents
(a), (b) and (c), these adsorp~ion filtering and treating mats can
contain, of their overall content, the activated carbon to a maximum
of about 255$, the polyester fibers in ~he range ~rom about 2% to
about 7.5~' and from about 2% to about 30~0 o~ cobeat.
`Any o~ the gas-adsorbing activated carbons from their various
sources, for exampl~, charcoal~ coal, petroleum distillation residue
~r pecan nut shells, can be used.
The invention also involves the method of preparing these mats
provided by the inventicn. Broadly the prepara~ion o~ the gas-vapor
treating mats comprises dispersing in water in a pulper (as used in
paper makin~) an amount o~ (a) micro-bits of any of an expanded,
therrr~plastic styren ~polylrer and an expanded lower p~lyolefin from p~lyethyle~e
to poly-methylpentene and a flexible polyurethane, each said polymer
being non-brittle in its expanded ~orm, and (b) glass fibers composed
o~ ~he glass filaments, as described above~ and agitating the mixture
of ~a) and (b) for the brie~ time at least su~icient ~or each of them
to be substantially ~ree of clumps and clusters and substantially uni-
formly intermixed, and in the propor~ion of from about 5 to about 50
parts o~ the micro~bits to from about 4 to about 45 pa~s of the glass
~ibers, admixing an organic binding agent (as described ea~lier aboYe)
or a cobeat (as described ~urther below) in an amount sufficien~ for
the finished mat to ha~e tensile stren~th an~ rosity, with each of
them bein~ within its respecti~e earlier above recited range;
then transferring the resulting mixture to a supply chest in a
concentration of ~rom about 0~l % to 0.5~ o~ the admixed
micro-bits and the glass fibers and therein agitating their mixture
.~ 7~
.
merely suf~iciently to maintain a uniform aispersion.
The dispersion then is fed from the supply chest to the furnish
box (of the Fourdr mier machine) at the ~ate, ~or example, from
about 3.3 to 5.5 kg. (iOe. kilogram) per minute and at the same time
is diluted uniformly with water fed into the fu~nish ~ox at the rate
o~ from 3,800 to about 9,000 liters per minute.
m e resulting diluted ~urnish slurry then is fed onto the
Fburdr~er screen moving at a rate to pro~ide a wet mat which after
drying has a basis weight of ~rom about 2.25 to abou~ 22.5 kg., and
continuously removing the wet mat from the screen and running it
through a suitable drying operation.
The gas-vapor treating mat can b~ prepared by including adding
to the mix~ure in the pulper, beneficially be~ore admixing any bind-
ing agent a separate amount o~ each of sodium hexametaphosphate and
concentrated sulfuric acid and in such proportion $o one another
sufficient to lower the pH of the mixture to 205.
m e gasvapor adsorption treating mats are prepared by a com-
bination o~ steps comprising preparing a cobeat suspension of wet la?
cotton fibers and micro-bits in water (as described further below)
and separately a suspension of micro-bits in water in the proportion
recited further below.
m en a furnish supply suspension is prepared by ad~ixing in
water an amou~t of the cobeat suspension wit'nin a given range and
addin~ a quan~ity o~ a ~iber~forming polyethylene terephthalate
2~ polyester in a quantity to partake in providing the ~inished mat
with tensile strength within an effective range without adversely
affecting its porosity. m en ~inely divided actiYated carDon
admixed within the range up to a maximum of about 25% Of the planned
total solids of ~he finished mat, and an aqueous suspensio~ of the
micro-bits is added in an amount to provide in the finished mat from
about lOy ~o about 30~0 of micro-bits.
_~ --10
3~
The remaining addition admixed is a suspension of glass fiDer.
micro-bits and binding a~ent, each within its respective range as
earlier recited for the gas-vapor treating mat and so proportioned to
the o~her solids ~or the finished mat to ha~e the planned tensile
5 stren~th and porosity. The ~inally resulting suspension ~rom all of
these included constituents is fe~ to the furnish box within the rate
of feed recited for the mats lacking the carbon and polyester, and
there similarly diluted with water and then fed onto the Fourdrinier
screen and dried as with the other mats.
lQ In each o~ the procedures preparing a mat wherein an organic
binding agent is used, it is beneficial to add that agent to the sus-
pension (being prepared) within the las~ minute or so o~ the agi~ation
be~ore the suspension is to be fed to the (machine) supply chest and
also tha~ the web lea~ing the Fourdrinier screen initially is subjected
to radiant heat from a relatively close source at a temperature in the
range of from about 600C.to about 700C.. m at rapidly causes solu-
tion of the organic bin~ ~ agent in the water carried by the mat an~ e~ es the
drying of theorsanic b ~ ~ agent at the intersections of the water~ luble
constituents.
The preparation o~ any of the desired styrene-polymer, lower
polyolefin or polyurethane micro-bits from starting bit-pieces of any
of the respective expanded polymers (styrene-polymer, lower polyolefin
or polyurethane) is illustrated in, but not restricted to, the follow-
ing preparation of polystyrene micro~bits:
2~ EXample A -
425 liters of expanding-agent-impregnated, extruded polystyrene pellets
(crystal) expanded to from &~out 6.~ to about 12~7 mm. substantially
round pellets having a bulk density o~ 12 grams per liter were commi-
nuted in a comminuting machine (as described earlier above) equipped
with an input ~eeder 10.16 cm. in diameter by 7.62 cm. long and a
bottom arcuate screen with holes of 0.1016 mm. diameter.
-11;
~, , .
, ; : . ~ . -
The rotor was set to run at 6,ooo r.p.m. and the feeder set to
charge the expanded polystyrene bit-pieces at the rate o~ 35.4 liters
every 5 minutes (i.e. 425 liters per hour) The starting expanded
polystyrens bit-pieces to be introduced into the feeder were wetted
with sufficient water substantially completely to cover their outer
surfaces. The ~hus wetted expanded polystyrene bit-pieces were
charged in~o the feeder continuously at a ra~e o~ ~5.4 liters every
5 minutes, while at the same time water was injected into ~he commi~
nuting chamber through the two 1.6 mm. diameter jet orifices at a
rate of 7.57 liters per minute.
m e mixture of the expanded polystyrene micro-bits l~aving the
screen bottom of the comminuting chamber was collected in an open
tank with a bottom drain plug, wherein the free water settled to the
bottom and the polystyrene micro-bits with the bound water held by
them (in the proportion of 2 parts of micro-bits to 98 parts of water)
due to the entrapped air, rose on top of the free water. The free
water was drained off leaving behind a plastic mass of the resulting
expanded polysbyrene micro-bits in the water physically bound to
them. m e plastic mass weighed 255.15 kilos and contained 5.1 kilos
of micro-bits with 250.05 kilos of water bound by them.
27.24 kilos of this plastic mass, placed in a close weave double
cotton bag, then were subjected to pressure until 22071 liters o~
water were expressed. The ~emaining 4.08 kilos containing 544 grams of
~ expanded polystyrene micro-bits then were dried in an open dish in an
oven maintained at 43.33C.
Micro~bits of any other thermoplastic expanded styrene-polymer
or lower polyolefin, each non-brittle in expanded form, or of any
flexible foamed (i.e. expanded) polyurethane non-brittle in its foam
or expanded fo~m can be prepared by repeating Example A and replacing
its starting polystyrene bit-pieces by bit-pieces of any of these other
-12-
applicable expanded polymers. Thus, each such repeat of Ex~mple A
starting with the micro-bits of each such other applicable expanded
polymer is ~o be considered as i~ incorporated herein in full as a
separate example, thereby avoiding unnecessarily extending ~his
~ 5 speci~ication.
m e preparation of the gas-vapor treating mats of the in~ention
is illustrated by, but not limited to, the following examples:
EXam~le 1 asic Gas-vapor Treatment Mat: Into 15 ,1~9 liters
of water charged into a tpaper ma~ing) pulper (of ve~y little greater
capacity), there was ~ed by an endless belt conveyor 23.27 kilos (dry
basis) o~ polystyrene micro-bi~s (in ~he form of water-bound product
containing 8% micro-bits solids). m e pulper contents mixture then
was agitated for 3 minutes by its rotor turning at 506 revolutions
per minute (r.p.m.) thereby dispersing the micro-bits in the water.
~7hile agitating the mixture, 22.73 kilos o~ sodium hexametaphos-
phate were admixed and followed by admixing 3.785 liters of concentrate~
sulfuric acid (98.6,b H2S04). That brought the pH of the batch to 2.5.
m e agitation was stopped while there were added (~rom a number
o~ cartons) a total of 113.64 kilos o~ 6.35 millimeters (length) glass
fibers (diameter 6.3 microns) Owens-Corning electrical grade DE 636
as thè number o~ ~ilaments per bundle (and bound by a starch, oil and
cationic surfactant binder).
m e rotor agitation was resumed and continued for 10 minutes,
during the las~ 30 seconds of which 10.25 kilos of (cold) water-swell-
able polyvinyl alcohol (98% hydrolyzed) (hereina~ter called PVA) ~ibers
were added as binding agent. m e thus completed initial pulper mix
was pumped to the beater chest (serving only as holding ~acility to
receive amounts o~ pulper mix) and agitated ~here merely ~ufficiently
to maintain the insolubles in suspension.
7570 liters of ~rinse) water then were added to the pulper and
;~ ```
~ ;~
agitated to suspend any glass ~ibers and/or micro-bits which settled
out and remained behind while the ini~ial pulper mix was being pumped
t~ the beater chest. The resulting so-called pulper rinse mix then
was pumped to the beater chest and ~here admixed into the initial
pulper mix to provide the starting mat~m~king mix containing o.64
solids.
m is starting mat-making mix then was pumped to the machine ohes~
(also a supply holding chest) with its contents maintained under agita-
tion also as in the beat~r chest. From this supply chest ~he mat-making
mix was fed to ~he furnish box for the Fourdrinier at a ra~te of 4.32 kg.
solids per minute and there combined with clear dilution water at a
rate of 6056 LPM tliters per minute).
The resulting uniform web-furnish slurry (as diluted in the
furnish bo~ was fed onto the traveling Fourdrinier screen (86 strands
1~, in the machine direction by 60 strands across) moving at a rate of 15.24
meters per minute (i.e. MPM) to enable providing an initial web mat whic
after 1ater ~inished drying showed a basis weigh~ o~ 19.1 kg.
The 9.525 m~n. thicls wet mat (on the Fourdrinier) a~ter passing
the suction boxes under the leaving end of the Fourdrinier scre~n con-
tinued onto an endless belt conveyor (a 112 by 84 mesh screen) also at
15.24 I~PM. Then after about 1.5 meters beyond that end of the
Fourdrinier~ the we~ mat (on that conveyor) passed about 10 cm. below
a battery (about 60.5 cm. long~ of infrared lamps (52.4 kilowat~s, at
~.8 amperes, 480 volts, single phase 60 cycle) pro~iding at the mat
surface a rheostat set temperature o~ possibly 649C. m e exposure
o. the wet m~t to that temperature thus for about 2.4 seconds quickly
caused solution of the PVA,
Ihe partially dry web continued through a tunnel dryer (about
3.67 meters long 'Dy 1 . 83 meters wide) proYiding a temperature of about
121C. and then alternated in sequence o~er one and then under the
-14-
~i
next of each of a series of six dryer drums (the first drum providing
a temperature of 113C. with the temperature increased at each of them
that followed with the last drum maintained at 127~). me finally
dry mat then passed throu~h a pair of ~ension rollers and onto a wind
up drum. m e dry mat web with a smooth surface on each side wound up
easily around that drum without a~y tears or wrinklesO
At its basis of 19.1 kilos, the ~inished gas-vapor treating web
showed a porosity value (by Gurley porosity meter) of about 602.8
liters per minute (i.e. LPM) per square decimeter (i.e. sq. dcm.) of
sur~ace at a tes~ dif~erential air pressure of 2.54 centime~ers of
water (gage).
Based on the starting amoun~s of the essential materials, the
finished dry gas-vapor treating mat contains about 15.8% of the ex-
panded polystyrene micro-bits~ about 77.2~ of glass fibers and about
6.97~' of polyvinyl alcohol binder. The content of thsse essential
constituents may be varied in accordance with desired variations in
porosity~ gas or vapor ~luid flow rate and density by suitable varia-
tions in the constituents content. For example7 the porosity can be
decreased by lowering the micro bits content to any le~el do~m to a
mini~um of about 2% without corresponding decrease in tensile strength.
Alternatively, the porosity and flow rate can be increased by
increasing ~he micro--bits content, as in some formulationst to any
level even up to about 50%
Example 1 can be repeated by reducing the ~uantity o~ sulfuric
acid in part or as a whole and also by reducing the amount of sodium
hexametaphosphate (ordinarily used to e~lance glass fibers dispersion~
in whole or in part in preparing the initial pulper suspension, in
~iew of the indication that the micro-bits appear to enhance dis
persion of the solid constituen~s during agitation in the water.
~0 Depending on the anticipated ultimate use o~ the ~as-vapor
-15
treating mat its basis weight can be reduced or enlarged by either
decreasing or increasing the solids content in the aqueous ~urnisn
in the furnish box or increasing or reducing the speed of the
Fourdrlnier screen~ m e replacement may be in part or as a whole.
Example 2 - ~
Micro~Bits: Into a 3.5 liter stainless steel beaker containing 3
liters of water, there was dispersed 21.5 grams of (~urniture grade)
flexible polyurethane m,icro-bits containing 20% solids (thus 4.3 grams
of dry micro-bits and 17.5 cc. of water) by an air driven stirrer.
m en 15 grams OL the same 0.635 cm. length DE 636 glass fib~r las of
Example 1) were added and a~itation continued. In the last 10 minutes
of an hour of stirring there was admixed 1.375 grams of the PVA tsame
as in Example 1).
Six-tenths o~ the resul~ing dispersed slurry then was poured
over the hand sheet screen of an ordinary laboratory paper hand sheet
former (having a 30.48 cm. high brass tank with a 20.32 cm. square
base) and mixed from the top. The water discharge valve was opened
with the solids o~ the slurry developing in sheet ~orm on the screen
and the water dripping through the scree~ by gra~ity from the increas-
ing density slurry. After no further water drained off by gravity,
the wet sheet was dried in a drying oven by a hot air stream at 121C.
~lowing through it for 5 minutes. The resulting 12.57 grams dry hand
sheet mat showed a tensile strength of 1.41 kilos per cm. and porosity
of 579 liters per square decimenter per minute.
Example 2 includes no sodium hexametaphosphate and sulfuric acid
because the micro-bits tend to enhance dispersion of the glass fibers
which as introduced into the water appear to a large extent in a
multitude of bundles of the fibers. Other mats of this invention
can be made similarly without these two inorganic substances,from
micro-bits o~ the other effective polymers.
-16-
....
. . ,
. . ~
Example 2 was repeated except that during the agitation a~ter admixin~
~he glass fibers, i~stead of PVA there was admixed 60 grams of the
cobea~ suspension o~ Example 5 amounting to 1.2 grams of the cobeat
solids (composed of beater beaten, interlocked wet lap cotton ~ibers
and polystyrene micro-bits). m e preparation o~ the mat then was
completed as in EXample 2. m e resulting dry mat showed porosity of
335 1iters per sq~ dcm. per minute, at 0.45 kg. dif~erential pressure
(gage), and tensile strength of 0.61 kg. per cm.
EXam le 4 - ample 3 With Pol~y_ ne ~Replacin~ P~o~y~rethane:
EXample 3 was repeated by using polystyrene micro-bits instead-of
the polyurethane mlcro-bI~s, and also cobeat as the binder instëad
of PVA. The resulting dry web showed tensile streng~ of 0.22 kg.
per cm. and porosity of 5,377 LPM at 0.45 kg. per cm. differential
pressure (gage).
m e adsorbent (oonstituent) containing gas-vapor ~iltering or
treating mats of this in~ention are illustrated by, but not restricted
to, the following:
Example 5 - ctivated Carbon-containing Adsorption Mat: ~a?
Cobeat Suspension PreE~ n: A cobeat suspension (so-called because
wet lap cotton ~ibers and micro-bits are beaten together in a beater)
was prepared by charging 363.6 kilos (dry basis) of wet lap cotton
fibers (as used in paper making, containi~g 1454.4 liters o~ water in
~ the ~ibers) and 181.8 kilos (dry basis) o~ polystyrene micro-bits t6Yo
solids with 2848.5 liters of bound water) into 13,354 liters of water
in a pulper and agitated ~or 3 minutes (as in Example 1) thereby dis
persing the cotton fibers and micro-bits free of clumps and clusters
in the water.
That cotton fibers and micro-bits dispersion was pumped to a
(paper making) beater having its pressure roll set at 65% o~ maximum
and run at 110 r.p.m. for 6 hours (when the freeness starting at 760
-17-
.
.
was ~ound to have dropped to 600). The roll setting then was changed
to provide more fibrillation and less cutting action, by using only
the brush roll pressure with the roll barely contacting the bed. m e
desired end occurred in two hou~s whe~ the ~reeness was ~ound reduced
to 450. The beater content (now the cobeat suspension) ~as retained
in the beater under merely sufficient agitation ~or the dispersion to
remain in~c~uspension for later use.
The term ~'freeness~' used hereinabove is a term commonly
used concerning the pulp in paper making, and is defined in U.S.
Patent 3,293,114 of December 20, 1966 (Column 3, lines 27-50 as:
"Freeness of pulp is a measure of the rate ~ flow of
water through the pulp and is measured in accordance with the
- Tappi Standard T 227 m-~8, also referred to as the Canadian
Standard Freeness".
The wet làp cotton fibers are those commonly used in writing
paper making to provide its cotton rag content. They are prepared for
the most part from cotton fabric cuttings and cotton linters which
are washed (bleached if necessary) and separated into fibers (as in a
hollander) of from about 4.73 mm. to about 1.27 cm. in length, fed
to a wet lap machine and from it as a web between pressure rolls and
lea~ing as a web about 2.1 mm. thick (containing about 80% moisture)
and then lapped up and back over and o~er on a pallet usually to a
pile of about 363.8 kilos gross weight.
~ : Into 7570 liters of water in the
pulper, there was admixed 136.4 kilos (dry basis) of the polystyrene
micro-bits (as the water-bound product containi~g 16% micro bits
solids and 715.9 liters of water) and agitated to a uniform dispersion
and maintained under merely suf~icient agitation for that until shortly
needed.
~ : A ~urnish supply suspension was
prepared in a beater chest
(i) by feeding into it 30,280 liters of water,
(ii) admixing into the water 189.3 liters of the foregoing cobeat sus
pension, thus proYiding a diluteA cobeat suspension,
(iii) followed by admixing 91 kilos o~ readily wa~er dispersible, se~i
-dull, opticzlly whitened polyethylene t~rephthala~e ~ D~e~
: ficially in 1.27 ~m. long ~iber~ o~ 1~5 denier gpu~ by con~entlonal
melt process9 ha~ing a special finish compatible with most anionic,
cationic or nonionic binders (and providing rapid and excellent dis-
persion with a wide ~ariety of rurnish ~ystems ~nd additi~es~, and
solution viscosity of 770 ~ 20 of 1/2 gram dissolved in 50 ml. of
solvent (by w~ight~ 40 parts to tetrachloroethane and 60 parts phenol)
at 25C. (solution ~isoosity is the ~iscosity of the polymer solution
divided by the vi cosity of the solYenty with the result minus one
multiplied by 1000); mel~ing point 48.67C., non-shrinka31e in boiling
water, and elongation at break 45~ (available as TREVIRA 101, product
of American Hoechst Corporation, Fibers Di~ision, Spartenburg, South
Carolina 29301~the incorporatiQn of polyethylene terephthalate f~s in the
suspension requires a relatively low solids content;
(iv) admixing 172~7 ~ilos of finely divided activated carbon (Nuchar S-N
product of ~restvaco Corporation, Covington, Va. 24426); and also
(v) admixing the ~oregoing micro-bits suspension containing the 136 4
kilos (dry basis) of polystyrene micro-bits as the water-bound product
~avin~ abou~ 1656 micro-bits solids) thereby adding 716 liters of water
to the 7570 liters initially included; and finally
(vi) adding 4163.5 liters o~ the cobeat suspension (containing 193.4
kilos of solids) and 15,140 liters of the JUSt below identified glass
fibers, micro-bits and binder suspension containing 187.7 kilos o~
suspended solids.
mis ~us-
pension was prepared by the proGedure used in (the first 4 paragraphs
of) EXample 1 by charging into a pulper 11,354 liters of water, admix-
- ing 22.73 kilos (dry basis) of polystyrene micro~bits as the water
-bound product (containing 65~ solids and 356 liters of water), dis
solving 22.73 ~ilos of sodium hexametaphosphate and 3.8 liters of
sul~uric acid (98.6%)9 and admixing 113.64 kilos of the same 6.35 mm.
length glass fibers and 10.23 kilos o~ the same PVA ~ibers. This
suspension then was pumped to a beat~r chest.
*Trademark
- 19 _
m e pulper then was rinsed by adding 3785 liters of water and
agitating the content as in Example 1. The resulting rinse suspen-
sion then was admixed with the pulper suspension in the beater chest9
thus providing the glass fibers, micro;;bits and binder suspension,
as ~he second member o~ the constituent (vi) of the ~urnish supply
suspension.
While maintained under agitation in the beater supply chest,
this uniformly admixed furnish supply suspension was fed to the
Fourdrinier machine head box at the same rate and admixture with
dilution water as in Example 1~ and onto ~he moving FOurd~inier
screen. A~ter passing the suction boxes, the resulting wet web
continued onto the endless belt conveyor and then was dried by
passing in sequence under the battery of infrared lamps through
the tunnel dryer and under and oYer the series o~ six dryer d~ums.
The final activated carbon-containing adsorbing mat was uni-
form in appearance with a basis weight o~ 15 to 15.45 kg. porosity
o~ 353.7 liters per minute per square decimeter, and tensile
strength of 1.074 kilos per cm. in the machine direction and 0.895
kilos per cm. in the cro3s direction.
m e polystyrene micro-bits of Examples 1, 4 and 5 can be re-
placed in par~ or as ~ ~hole by those of any other of the applicable
expanded ~hermoplastic styrene-polymers or lower polyole~ins or of
flexible polyurethanes each non-~rittle in expanded form. Thus, each
, .
such repeat of Examples 1, 4 and 5 by the just indicated replacement
2~ o~ expanded polystyrene micro-bits is ~o be considered as if occurring
herein in full as a complete example, thereby a~oiding making ~his
specification prolix. m e lower polyolefins from polyethy~ene to
poly-methylpentene include also polypropylene and polybutene.
In any of Examples 1 to 5, and any of t~e ~ust above indicated
modifications of any of them, the micro-bits can be provided with any
.
--2~
,
- :
amount of water held by ~hem ~s well as in the dry state. The micro
-bits were provided in these examples as used along with di~ferent
amounts ~f water held by them, because o~ their ready availability
in that form and their ~hus lower eost.
Similarly, the cotton fibers used in preparing the cobeat were
provided in their fo~ as wet lap cottoa~ fibers~ ordinarily contain
ing about 80% of water, because of the economy in doing sO. Howe~er,
that does not preclude using ~hese cot~on fibers in t~e dry state
~hen thus aYailable or desired ~or any particula~ reason.
The West~aco's NUCHAR~ -N acti~ated carbon in EXample 5 can be
replaced by any other Westvaco actiYated carbon. For exa~ple, if the
mat is to be used ~or adsorbing pnenol, WestYacO~s NUCHAR N A ~yield-
ing an acid wash water when washed in wa~er) would be beneficial be-
cause that acid grade mani~ests higher adsorption o~ phenol~
Either of these two grades of activat~d carbon ~an be replaced
by any of the others available, for examp~e, DARCO now available from
I.C.I. (U.S.A~) Ltd., and the NORIT product of American Norit Co. ~ne
Bar~eby-Cheney activated carbon from pecan nut shells is highly ef~ec-
ti~e, ~or.example, in the adsorption o~ sulfur dioxide from a gas
stream, for which it showed a very much greater adsorption capacity tha
an activated carbon from another source. Thus, Example 5 is to be
considered as if present~d written out in full with its activated
carbon replaced by the ~a~neby-Cheney product.
The polyester of Example 5 can be replaced by any oth~r fiber
-forming terephthalate polyester, f ~ example, the FORTREL poly-
ethylene terephthalate and th~ KOD~ ~imethyl 1.4-cYclo~exane di~
methanol. Example 5 and the thus resulting examples derived from
it are to be considered as if presented as written out in full
with the polyester separately respectively replaced by
each one of these other polyesters. ~ny of them can
be used in any of the available 1.5 and 3 denier diameters.
~21~
The mats of this in~ention are ef~ec~ive for removal and/or
recovery o~ various gases or ~apors, either inorganic or organic,
for example, sulf~r dioxide, chlorinated alkanes such as carbon
tetrachloride and other chlorinated alkanes~ and benzene and
phenol~
While the in~ention has been e~plained by detailed description
of certain specific embodiments of it, it is understood t~at various
substitutions or modifica~ions ca~ be made in any o~ them within the
scope o~ the appended claims which are i~tended to co~er also equi-
~alents of these embodiments.
