Note: Descriptions are shown in the official language in which they were submitted.
13 ~3~
~RADAsLe AESSORB~ TERl[AL
Ai~ ~A~FAc~aRIlæ PROOESS q~E~FOR
BACK~;RWND OF T~IE I~VENTION
~ical~iel~
The present invention relates generally to absorbent
materials and processes for the manufact:ure thereof~ and, more
particularly, to absorbent materials which are readily
degradable by incineration or the like following usage as an
absorbent and which may be either hydrophilic or hydrophobic in
nature, thereby permitting usage of the hydrophilic forms of
the invention as industrial floor sweeps, beddings for use in
animal transport, kitty litter and the like, while pennitting
usage of the hydrophobic forms of the invention for species
specific absorption purposes 6uch, merely by way of ex~nple, as
the absorption of oil spills fran both land and water
: environments, as well as absorption of other toxic liquid
materials and/or other liguid contaminants.
More specificallyt the present invention utilizes, as a
basic ingredient, waste cellulose fibers of the type commonly
generated in wood pulping or paper making operations; and, more
p~rticularly, waste cellu}ose fibers having a relatively low
content of inorganic solids~ ,, clays and/or other silica
`` compounds, commonly referred to as "fillers~. Preferably, the
waste cellulose fibers used with the present invention include
not more than 10% inorganic solids by weight and, in any event,
less than 30% inorganic ~olids by weight. Ideally, however,
~e waste cellulose fibers employed with the present invention
have no inorganic solids content; but, as a pra¢tical matter,
the waste streams from most pulp and/or paper mills will
include some inorganic ~olid~ or Ufillers". ~ypically, such
waste cellulose fiber materials having relatively low inorganic
~ ~olids content are generated afi a waste bi product at the: discharge end of a sulfite bleach mill used in the pulping
industry ~uch~ for example, as in the pulp mill of 5eorgia
Pacific Corporation located in Bellin~ham, Washington.
~owever, as the ensuing description proceeds, ~hose slsilled in
" ~b
~3~3~6~
the art will appreciate that the invention is not limited to
use with the discharge wastes of sulfite bleach pulp mills but,
rather, can be used with such materials generated in other
conventional pulping and/or paper making processes that produce
lcw inorganic solids content in the waste outflows.
~ u~ld~
Heretofore clay-based materials and other inorganic
absorbents have been utilized in the control and removal of
undesired liquids frosn industrial floors and walkways and
similar industrial environments. But, such materials are not:
i) sufficiently effective as determined by absorptive capacity;
ii) ccn~enient as determined by bulk density, typically 25 to
40 lbs./ft.3; or iii) r readily decomposable or degradable, as
the wholly inorganic constituents preclude incineration even
when saturated with combustible liquid material or the like.
A recent advance in absorptive media entails the
pelletization of cellulose fibers and clay and/or other
inorganic solids as disclosed in U.S. Letters Patent No.
49374,794 -Kok. ~owever, the action of pelletizing a
cambination of cellulose fibers and inorganic solids or
~fillersU reguires use of considerable force applied to the
material in order to extrude it fram a die orifice. me
reguisite force is a compressive action that: i) eliminates
interstitial spaces in the body of the pellet; ii~ creates a
non-porous surface; iii) creates a dimensionally st~ble
cylindrical shape; and iv), results in a product having a bulk
densi~y typically ranging from 25 to 40 lbs./Et.3 Moreover,
when used as an absorptive media on floor surfaces, the
extr~ded pellets present a hæ ardous rolling interface between
the floor surface and pedestrian traffic. Further, such
ex~ruded pelle~s exhibit 1QW absorptive capacities.
Two other patents of interest are those recently issued
to Papyrus Ropparfors A.B. of M~lndal, Sweden as the assi~nee
of Thomas Ericsson, U.S. Letters Patent No. 4,537~877, and as
the assignee of Thomas Ericsson ~ ~1, U,S. Letters Patent ~o.
4,519,918. Thus, in the aricsson '877 patent, the p~tentee
.~3~3~8
-- 3 --
discloses various examples of a particulate oii-absorbing
composition comprising at least ~0% by weight hydrophobic
cellulose pulp fibers "...blended with at least 30% up to 50%
of an inorganic cellulose paper pulp filler...". ~e, Col~ 1,
lines 48 and 49 of U.S. Pat. No. 4,537,877. Unfortunately, the
inclusion of large amounts of inorganic cellulose paper pulp
fillers--including particularly amounts in the ranye proposed
by the Ericsson comprising at least 30% by weight and ranging
up to 50% by weight of the basic composition--presents a number
of problems. First and foremost, the inorganic solids or
afillers~ tend to increase the bulk density of the resulting
product which generally ranges from 16 to 20 lbs./ft.3; and, as
a consequence, even though the product is hydrophobic, upon
saturation with oil it will not float. Morecver, t~e large
amount of inorganic solids present tends to reduce both the
rate of absorption and the absorptive capacity of the product
produced. Additionally, the inorganic solids are not readily
fl~mmable and/or degradable; and, cannot be satisfactorily
disposed of by incinerationl thus producing a significant
quantity of non-degradable ash, which creates a high-cost
di~posal problem, and reducing the amount of heat that can be
generated per cubic volume of waste material~ The inorganic
solids present further create significant dust problems
resulting in eye and/or breathing irritants, undesirable
abrasion of production equipment and, indeed, a severe
explosion ha~ard.
In the Ericsson '877 patent, it is proposed to render
the cellulose fibers hydrophobic by siæing with rosin, whereas
in the Ericsson ~ ~1 '918--a patent which is subject to all of
the disadvantages mentioned a~w e which are inherent in the
~ricsson 3877 patent~-the fibers are rendered hydrophobic b~
impregnation with liquid resinous materials. In both cases, no
provision is made for conditioning the particulate materials to
insure that the fiber ends do not project ou~wardly from the
fibrous particles; andr as a consequence, the particula~e
materials of Ericsson and ~ricsson ~ ~1 exhibit a fuzzy
~313~
surface appearance which results in breakage of fiber end~,
increasing the dust problem, while causing clinging and
comp3ction of adjacent particles.
StlM~hR~ 0~ rIo~
The present invention overcomes all of the
disadvantages inherent in the prior art as exempli~ied by the
foregoing ~ok~ Ericsson and Ericsson ~t ~1 patents by providing
particulate absorbent materials which: i~ in most for~as of the
invention haYe a relatively low content of inorganic materials
and in all forms have less than 30% inorganic solids by weight;
ii) are not in pellet form; iii) are characterized by an open
porous fiber structure having relatively low bulk densitiest
high rates of absorption, and high absorptive ca~acities;
iv) are highly flammable both before and after absorption of
liquid materials which are often themselve~ non-flc ~ able, and,
therefore, are characterized by high heat values during
recycling; v) produce relatively little ash when incinerated,
thus minimizing disposal cost~ and problems; and vi), readily
permit of treatment to render the absorbent material
hydrophobic and/or characterized by it~ ability to re~o~ef
and/or form a barrier for, toxic and/or noxious odorants.
Id~ally the in~ention contemplates the u~e of waste
cellulose fiber materials having no inorganic solids or
nfillers" at all; although, given the state of the known
technology available today, it is generally necessary to use
waste cellulose materials having from on the order of 2%, or
le~s, inorganic solids by weight to on the order of 10%
inorganic solids by weight, but in any event, less than 30%
inorga m c solids by weight. Thus, it will ke understood by
those skilled in the art that referenoe s in the ensuing
~etailed Description and in the appended claims to waste
cellulose materi~ls having ~minimal inorganic solids con~ent"
shall mean a waste cellulose material having: i) less than 30%
inorganic sQlids content by weight even when used as a litter
material where inorganic solid~ may be added to increase the
lnorganic solids content to on the order of 25~ 50 as to
~3~ 3~$~
increase the flushability of used litter material;
ii) preferably not more than 10~ inorganic solids content by
weight, and iii), ideally, either no inorganic solids content
or as little inorganic solids content as possible.
In carrying out the process of the present invention
for forming highly degradable absorbent materials, the waste
cellulose fibers are mixed with water, a latex emulsion and
aluminum ~ulfate or other material capable of reducing the p~
level, so as to form a slurry comprising approximately g6.5%
water by weight and approximately 3.5g total solids by weight.
A suitable flocoulant is added to the slurry, preferably during
transfer of the slurry to a press where excess water is removed
frGm the slurry so as to produce a mat or press cake whioh is
approximately 40% total solids b~ weight. The mat or press
cake is ~hen shredded and passed through a conditioniny
conveyor where the particulate shredded materials are tumbled
in a water mist in the presence of a surfactant so as to
condition the particulate materials by folding in projectlng
fibers and fiber ends to form non-fuzzy particles and to
enhance ~he wetability thereof. The resulting particulate
material is then dried to increase the solids content to
preferably on the order of from 88% to 90~ total solids by
weight. While it is prefered to dry the particulate material
to a range of from 88% to 90% total solids by weight, it is
essential that the material be dried to at least 75% total
solids by weight æo as to minimize bacteriologic degradation;
and, indeed, preferably all moisture in exoess of water o~
hydration is removed.
A degradable absorbent material produ~ed in accordance
with the foregoing proce~s will be hydrophilic by nature,
having a relatively low bulk density which i8 preferably on the
order of from about 8 to 10 lbs./ft~3 as contrasted with the
b~lk densities inherent in the Ericsson and the Ericsson ~ ~1
products which range fram 16 to 20 lbs~/ft.3D The lower bulk
density serves to substantially enhanoe the absorptive capacity
of the product; and, when the product i~ treated to render it
t 3134~
hydrophobic, serves to ensure that the product will float on
water for prolonged periods of time, even when saturated wikh
oil, so as to permit the ready absorption and retention of
oil and similar liquids in a floating environmentO Moreover,
the substantially reduced amount of inorganic solids present
in the product o~ the present invention as contrasted with
prior products ensures ready degradati.on of the product after
use by incineration or the like, thus maximizing heat values
produced and minimizing the quantity o:E ash that must be
disposed of as well as attendant disposal costs.
When used as a litter material for cats and similar
animals, inorganic solids may be added to the slurry so as to
increase the total inorganic content of the solids in the
slurry to approximately 25% of the total solids present by
weight but, in any event, less than 30% of the total solids
present by weight, thus enhancing the flushability of used
litter material. Moreover, when used as either a litter
material or as a bedding material for animals, or when used
as an absorbent for other noxious and/or odoriferous waste
materials, the absorbent material of the present invention
can incorporate a suitable deodorant and/or vapor barrier
; which either serves to absorb noxious fumes and/or odorants
or to prevent dissemination thereof into the surrounding
atmosphere.
~ When it is desired to convert the absorbent material of
; the present invention to one that is hydrophobic in nature,
it is possible to add resins and/or other water repellants
to the material--preferably water repellants that are species
specific with regard to attraction of the liquids to be
absorbed.
Alternatively, plastic materials may be added to the
basic absorbent material of the present invention so as to
render the material hydrophobic in nature.
According to one aspect of the invention, there is
provided a process for forming a degradable particulate
absorbent material having not more than 30% inorganic solids
content by weight and comprising the steps o~:
- 6A - ~ 3 ~ 8
a. obtaining waste cellulose fiber material having
not more than 30% inorganic solids content by weight with a
total dry solids content ranging from approximately 20% to
approximately 50% by weight;
b. rehydrating the waste cellulose fiber material to
produce a water/fiber slurry comprising on the order of
about 96.5% water by weight and about 3.5% total solids by
weight;
c. adding a water insoluble latex emulsion to the
slurry produced in Step (a~ in an amount ranging from about
0.5% to about 5.0% of the total dry solids by weight in the
slurry;
d. ~ewateriny the slurry to form a shreddable press
cake;
e. part;culatiny the press cake by means of a
shreddiny device to form discrete particles;
f. conditloniny the discrete particles produced in
Step (e) by imparting a tumbling motion to such particles
in the presence of a water mist; and
g. drying the conditioned discrete particles to
produce a generally flat planar particulate absorbent
medium ranging from 80% total dry sollds by weight to 92%
total dry solids by weight and having not more than 30%
inorganic solids content by weight.
Also according to the invention, there is provided a
degradable particulate absorbent material prepared by the
above-described process and characterized in that it has an
open porous fiber structure with extensive open and
unfilled interstitial spaces on the surface and throughout
the interior thereof, whereby the material has relatively
high ratios of absorption and rendering the material highly
flammable both before and after absorption of liquid
materials, the material having a bulk density of not more
than about 13 lbs./ft.3 and having less than about 30%
inorganic solids by weight.
~ .i
., .
- 6B ~ 3~fi~
According to a further aspect of the invention, there
is provided a degradable liquid absorbent material
comprising waste cellulose fiber materials having minimal
inorganic solids content and characterized by having:
(i) a bulk density of not more than 13 lbs./ft.3;
(ii) extensive open and unfilled interstitial spaces on the
surface and throughout the interior of the degradable
liquid absorbent material; and (iii) surface fibers and
fiber ends laid into the body of the degradable li~uid
absorbent material so as to form particles of absorbent
material devoid of outwardly projecting fibers and fiber
ends.
DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the present
invention will become more readily apparent upon reading
the following Detailed Description and upon reference to
the attached drawings in which:
~'
~31~
-- 7 --
FIGURE 1 is a microphotograph (200X magnification~
depicting a typical conventional prior art absorbent material
of the type resulting from the processe~ disclosed in the
foregoing Ericsson and/or Ericsson ~ _l patents, here
particularly illustrating the presence of clays and other
inorganic solids or ~fillers" tendiny to fill the interstitial
spaces bætween the randomly oriented fibers;
FIG~ 2 is a microphotograph ~200X magnification~
illustrating the fibrous array in absorb~nt materials made in
accordance with the present invention, and emphasizing
particularly the absence of inorganic solids present in the
interstitial spaces between adjacent fibers;
FIG. 3 is a highly magnified (500X magnification)
microphotograph here illu~tra~ing the conventional prior art
absorbent material inherently produced in accordance with the
processes of the foregoing Ericsson and ~ricsson ~t ~1 patents,
and emphasizing particularly both the presence of inorganic
: solids in the interstitial spaces between adjacent fibers and
the tendency of the fibers and fiber ends to project randomly
out of the ~urface of the particulate material; and,
FIG. 4 is a highly magnified 1500X magnification)
microphotograph o~ an absorbent material made in accordance
with the present invention, here particularly emphasizing both
the lack of inorganic solids present within the product and the
absence of randomly oriented fibers and fiber ends projecting
out of the particulate material~
While the invention is susoeptible of various
modifications and alternative forms, specific embodiments
thereof have been shown by way of example in the drawings and
will herein be described in detail. It should be understood,
: however, that it is not intended ~o limit the invention to ~he
particular forms disclosed, but, on the contrary, the intention
: is to cover all modifications, equivalents and alternatives
falling within the spirit an~ scope of the invention as
expressed in the appended claims.
-8- ~3~ 3~
DETAILED DESCRIPTION
In accordance with one of the important aspects of the
present invention, provision i5 made for forming readily
degradable absorbent materials from wast.e cellulose fibers
having minimal inorganic solids content--i.e., less than 30%
inorganic solids by weight, preferably l.ess than 10% inor-
ganic solids by weight, and ideally at or approaching 0% in-
organic solids by weiyht--and where such readily degradable
absorbent materials are: i) loose and porous, having a bulk
density of less than 13 lbs./ft.3 and preferably in the
range of from 6 to 10 lbs./ft.3; ii) characterized by their
high rate of absorption and high absorptive capacity; iii)
characterized by their high flammability and their
propensity for ease of disposal after use by conventional
incineration processes which, because of the flammable
nature of the product and the presence of minimal levels of
inorganic solids or "fillers", create usable high heat
values and produce minimal ash, thus minimizing waste
disposal problems and costs; iv) conditioned to eliminate
problems inherent with prior art processes and/or products
wherein the fibers and fiber ends project out of the
particulate material; and v), which readily permit of the
use of process additives to render the degradable absorbent
material hydrophobic and a species specific attractant to
non-water liquid contaminants, as well as highly effective
in removing and/or serving as a barrier for noxious and/or
odoriferous contaminants. Suitable waste cellulose fibers
can be obtained from sulfite, sulfite-acid, groundwood,
sul~ate, thermomechanical and kraft process mills for
forming pulp, as well as from a variety of other paper
making operations; and, the types of inorganic solids which
are commonly present in such waste cellulose fiber materials
include, but are not limited to, KAOLIN (Trademark), CHINA
CLAY (Trademark), talc~ calcium carbonate and silica mineral
complexes; but, as previously indicated, it is preferable to
employ a waste cellulosic fiber material having a minimal
~.r -; -
. ~
9 ~31 3~8
content of inorganic solids o~ the foreyoing types.
In keeping with this aspect of the invention, theprocess initially involves the formation of a slurry com-
prising approximately 96.5% water and approximately 3.5%
total solids by weight wherein the solid~ content of the
slurry comprises: i) waste cellulose fibers having minimal
inorganic solids content and constituting in the range of
94% to 99.5~ and, preferably, approximately 99% by weight of
total dry solids; ii) a suitable latex emulsion to promote
adhesion of the fibers one to another and constituting in
the range of about 0.5% to 5%, and preferably approximately
1%, of total dry solids by weight; and iii), a suitable
acidic material in such quantity as required to reduce the
pH level of the slurry to in the range of from about 4.~ to
5.5. To this end, the waste cellulose fibers having minimal
inorganic solids content are added to water in any suitable
agitation tank. Thereafter, the requisite amount o~ latex
emul~ion is added to the slurry~ While those skilled in the
art will appreciate that a wide variety of latex emulsions
can be employed to promote adhesion of the fibers one to
another, particularly advantageous results have been ob-
tained when using a water insoluble latex emulsion marketed
by Dow Chemical U.S.A. of Midland~ Michigan under the prod-
uct designation DL244A (Trademark). Thereafter, a suitable
acidic material is added to the slurry, as required, in
order to adjust the pH level down to a range of from 4.5 to
5.5. Again, those skilled in the art will appreciate that a
wide variety of acidic additives can be employed; but, ex-
cellent results have been achieved using, for example,
aluminum sulfate or "Alum" (Trademark) [A12tSO4)] which is
marketed by Stau~fer Chemical Co. of Westport~ Connecticut.
In carrying out the process of the present invention to
form industrial grade hydrophilic liquid absorbents which
are readily degradable and attain the objectives o~ the in-
vention, the slurry produced in the agitation tank is, aftersufficient agitation to insure a homogeneous mix of the
slurry constituents, transferred to a conventional press to
-lo- ~3~3~
dewater the slurry and form a mat or press cake having in the
range of 30% to 45%, and preferably on the order of about 40%,
total dry solids by weight. Those skilled in the art will
appreciate that the press may take many well known,
conventional and commercially available forms--e.q., a V-
press, a screw press, a vacuum drum, or t:he like--but,
excellent results have been achieved using a conventional
high-pressure belt press of the type manufactured by Parkson
Co. of Fort Lauderdale, Florida and marketed ~mder the product
designation MAGNUM (Trademark) Series 3000-2Ø
To promote flocculation of the solids content of the
slurry and adh sion of the fibers one to another, it has
been found desirable to add a suitable flocculating agent to
the slurry produced in the agitation tank prior to delivery
thereof to the press. Such flocculating agent may take
various forms; but, particularly desirable results have
been achieved when using POLYMER 1264 (Trademark) manufactured
by Betz Paper Chem, Inc. of Jacksonville, Florida as a
flocculating agent. Such flocculating agent may be added
to the slurry as it is transEerred from the agitation tank
to the press. The quantity of flocculating agent added may
vary widely dependent upon such diverse variables as the
type of flocculating agent employed, the nature and
content of the slurry, etc. However, it has been found that
the quantity of flocculating agent is not critical provided
only that as the flocculating agent is added to the slurry,
the operator visually observes the slurry; and, when
floccluation or "clumping" of the fibers is observed,
accompanied by clearing of the water which theretofore
exhibited a milky appearance due to the presence of the latex
emulsion, the addition of further flocculating agent can be
terminated.
During the next step in ths process, the press cake output
from the conventional press is shredded to form discrete par-
ticles exhibiting predominantly flat planes by means of a dualshaft counterrotating shredding device incorporating circular
toothed blades. Such a shredding device is completely
~.~
~3~3~
conventional and may take ~he fonm of a shredder of the type
manufactured by ~iller Franklin Co. of Livingston, New Jersey
and marketed under the trademark "TASKMASTER". Again, however,
those skilied in the art will recognize that other readily
a~ailable particulating devices may be substituted without
departing from the teachings of the present in~ention.
The flat planed discrete particles of ~bsorbent
material composed of randomly aligned fibers and minimal
inorganic solids formed by the non-compressive shearing action
of the shredding device are then conveyed to a conventional
screw conveyor wher2in the particles are conditioned by
tumbling in the presence of a water mist so as ~o cause the
loose fibers and fiber ends protruding from the flat pl~nes and
edges of the particles to be combined with th2 body thereof,
thus converting the fuzzy particles produced by the shredder to
non-fuzzy particles. Moreover, in carrying out this aspect of
the invention, it ha~ been found desirable to apply a water
soluble surfactant to the liquid absorbent partlcles so as to
enhance the wetability ~hereof. While numerous surfactants may
be employed, excellent results have been attained with a
surfac ant manufactured by Betz Paper Chem, Inc~ of
Jack~onviller Florida and designated as DPS1104. The amount of
surfactant added is not critical and i8 a matter of choice,
but, the desired re~ults have been found to be achieved when
using a water soluble solution containing approximately 0.5%
surfactant by weight which is applied to the absorbent
particles as they are tumbled in the water mist during transit
through the conditioning screw conveyor~ Those skilled in the
art will recognize that other conventional devices can be
30 employed to impart a tumbling action to the particles without
departing from the teachings of the present invention.
The random alignment of fibers in conjunction with the
non-compressive shearing action of the press cake by the
shredding device and the non-compressive action in the
35 conditioning scr~w conveyor ensures that the li~uid absorbent
particles retain, upon drying, a thorough distribution of open
~ 3~ 3~
- 12 -
interstitial spaces within the particle interiors and an open,
porous surface as clearly illustrated in FIGS. ~ and 4~
especially when contrasted with the con~entional prior art
processes of the Ericsson and/or ~ricsson ~t al type as
depicted in FIGS. 1 and 3.
Drying of the particles is accomplished in a fluidized
bed dryer of conventional manufacture and available from such
entities as, for e~ample: Car~en Ind. of Jeffersonville,
Indiana; and, Dresser Industries of ~illsboro, Oregon,
utilizing an inlet airstre~n temperature in the range of 170~C.
to 240UC. and, preferably, 180C. to 200C. The particles exit
the dryer after a residence time of approximately six (6)
minutes with a total dry solids content in excess of 75~ by
weight, preferably in the range of 80~ to 92~ by w~igbt, and
most preferably in the range of from 88% to 90% by weight.
The final bulk density of the liquid absorbent
particles is, of course, a function of the origin of the
fibers, the ratio of inorganic solids to organic fibers by
weight, and the final tvtal dry solids content. ~uch variables
may be adjusted, as desired, to better suit the material to
specific applications. ~owever, an acceptable range is equal
to, or less than, 13 lbs./ft.3, with a preferred bulk density
ranging from 6 to 10 lbs./ft.3
A general purpose industrial grade liquid absorbent
embodying features of the present invention was made as
follows:
First, waste cellulose fibers having minimal inorganic
solids content were obtained from a sulfite-acid pulping
facility having a waste discharge stream containing a total
solids con~ent of 28% with an inorganic solid~ content of 5~.
A 400 gallon batch of slurry was prepared as described above by
addition of sufficient water to the cellulose fibers in an
agitation tank to produce a water/fiber slurry containing 96.5g
water and 3.5~ total dry solids; and, wherein the total dry
solids comprised: i) approximately 99~ organic cellulose fibers
~313~
- 13
having minimal inorganic solids content t5%); ii) approximately
1% of water insoluble latex emulsion ~DL:244A); and iii), a
small quantity of Alum sufficient to redl~ce the pH value of the
slurry to approximately 5. The resultant slurry was then
transferred to a Parkson Co. belt press while a ~mall amount of
flocculant (Pol~mer 1264) was added sufficient to evidence
initiation of visibly observable flocculation of the solids and
clarification of the milky appearance of the water re ulting
from the latex added to the original slurry. The resultant
slurry and flocculant was dewatered in the Parkson Co. belt
press to form a press cake containing 40% total solids ~y
weiyht. Thereafter, the press cake was shredded in a Miller
Franklin TASKMASTER shredder, conditioned in a screw conveyor
; under the influence of a water mist containing 0.5% surfactant
~DPS1104), and dried to 90~ total dry solids.
The resulting liquid absorbent material manufactured in
accordance with the present invention was then campared with
conventional clay floor sweeps purchased locally with three
varieties of pellets designated herein as ~A", "B" and uca~
each of which were composed of cellulose and inorganic solids
and which are available commercially from various retail
e~tablishments located throughout the United States. The
; comparative bulk densities of the product of the present
invention and commercially available pellets "A", ~B~ and "C"
are ~et forth in Table I ~elow, while the superivr absorptive
abilities of the liquid absorbent media produced in accordance
witb ~he present invention as compared with those of the
pellets ~A", "B" and "C" are listed in Table II below.
TaBh~ I
Bulk Density lb./ft.~
Present Clay as Pellet Pellet Pellet
Inven~ion Tested ~ B C
~ 38.06
~3~3~
~ 14 ~
TABL~ II
Absorptive Capaci~y % by wei~ht
(uptake media, standard hydraulic oil~
Present Clay as Pellet Pellet Pellet
Invention Tested A B C
1 minute 290 100 66 61 29
1 hour 293 100 77 70 31
16 hours.301 109 ~3 71 31
As can be readily discerned from the comparative
figures set forth in Tables I and II above, the absor~ent media
prepared in accordance with the present invention is far
superior to conventional commercially available pellets in
absorption capacities and lighter in weight given comparative
volumes. In an industrial situation, time is of the essence in
containing liquid spills. Often ~he limiting factor in
containment and cleanup response is the weight-carrying ability
of an employee. Vtilizing the absorptive media of the present
invention, an employee will be able to deliver from two (2) to
three (3) times the volume of absorptive media to a ~pill
location in a given period of time with a consequent
significant increase in absorptive capacity. Further, the
absorptive media prepared in accordance with th~ present
invention does not present a round rolling interface between
the floor surface and pedestrian traffic. As such, the present
~i 25 i m ention exhibits many advancements over the known prior art
as exemplified by, for e~ample, the commercially available
; pellets designated UAU, "B" and ~cu and/or the pellets
disclosed in the aforesaid U.S. Pat. No. 4,374,794--Rok.
The absorbent media of the pre~ent invention was then
compared with absorbe~t media of the type disclosed in the
foregoing Ericsson patent. ~he bulk densi~y of the absorbent
~edia of the present invention was; as indicated above,
7.0 lbs./ft.3; wherea~ the bulk density of the Ericsson
absorbent material was 19.36 lbs./ft.3. In terms of absorptive
capacity, the present invention exhibited the capacity to
absorb an amount of standard hydraulic oil equal to 290~ of its
~3~3~
15 -
weight in only one (1) minute as ccmpared with 301~ in sixteen
~lS) hours- viæ~l the absorbent material of the invention
reached virtually its full capacity of absorption in only one
Il) minute. The Ericsson material, on the other hand, was
capable of absorbing an amount of the standard hydraulic oil
equal to only 133% of its weight in one (1~ minute and did not
reach its maximum capacity of 156% of its weight until 6ixteen
(16) hoars, thus clearly demonstrating the ~uperior absorbing
characteristics of the present invention, both in terms of
total absorptive capacity and rate of absorption.
Finally, the absor~ent media of both the present
invention and of the Erics~on process were then subjected to
incineration. The quantity of total ash produced with the
present invention was only g.6% by weight of the material
subjected to incineration; whereas, the total ash produced from
the Ericsson material represented 44~ of the material
incinerated, thus again clearly evidencing the superiority of
the present invention over the known prior art
Morecver, the striking differences between the
absorbent media of the present invention and those disclosed in
the aforesaid Erics~on '877 and Ericsson ~ '918 patents are
readily di~oernable merely by side-by side vi~al comparison of
highly magnified microphotographs of the two products. Thus,
referring to FIGS. 1 and 3 which respectively depict the
25 ~ricsson abBorbent media at 2001~ and 500X magnifiGation, one
can readily observe that the interstitial spaces between
adjacent fibers contain la~ge amounts of inorganic solids
consistent with Ericsson's teaching that his media must contain
...at least 30% up to 50% of an inorganic cellulose paper pulp
filler..." ~, Col. 1, lines 48 and 49 sf U.S. Pat. No.
4,~37,877. Moreover, as is made particularly evident upon
inspection of FIG~ 3, it will be observed that the randomly
oriented fiber~ and fiber ends are not laid into the body of
the absorbent media particle, but, rather, project out of the
body of the particle pr~ducing a fuzzy particle which is
subject to breakage of the protruding fibers, thereby creating
~3~3~
~ 16 -
a severe dust problem and producing clinging, agglomeration and
compaction of the absorbent media particles.
Referring on the other hand to FIGS. 2 and 4 which
respectively depict the absorbent media of the type produced in
5 Example I of the present invention, one can readily observe
that the interstitial spaces be~ween adjacent fibers are
essentially devoid of inorganic solids or "fillers". Thus, the
particles are characterized by their open internal structure
and a porous surface defined by randomly oriented fibers
10 wherein the fibers and fiber ends are laid into the particle
body as a result of passage through the conditioning conveyor
in the presence of a water mist. As a consequence, the
absorbent media of the present invention is not fuzzy and is
e~sentia~ly dust free.
15 ~XAM2h~
A liquid absorbent material was prepared in accordance
with the present in~ention in the same manner as that described
above in connection with Example I except that in this instance
0.75~ by weight of a water soluble deodorizing chemical
20 cG~mercially available from Cox Family Laboratories, Inc. of
Lynden, Washington, and marketed under the trademark UCONTACT"~
was addçd to the product during transit through the screw-type
conditioning conveyor. I'he resulting dried absorbent m~terial
was then tested for use as an animal bedding material. To this
25 end, 4~ lbs. of liquid absorbent material were distributed
evenly throughout a pen 6'x8' (48 sq. ft.), forming a bedding
of approximately 2" in depth. Fifteen (15) mixed breed pigs
weighing approximately 20 lbs. each were placed in the pen and
prcvided with water, but with no feed. me pigs were left in
30 the pen for a period of 24 hour~. It was noted that at the
outset the test pigs chewed on the absorbent material; but~
; that did not continue after the first hour or ~o. Throughout
the test period the absorbent material maintained its
absorbency and resiliency; and, no dust was observed. The pigs
35 were observed for four days following the test and showed no
ill effects. Based upon the observations made during this
11 3 ~
- 17 -
testl the absorbent material of the present invention appeared
to work as an excellent bedding for shipping swine via air;
and, of course, the lightness in weight of the material
attributable to its l~w bulk density as contrasted with the
S bulk density of other conventional bedding materials, is a
contributing factor to minimal cost for air freight charges~
M~h~_III
A liquid absorbent material was formed in accordance
with the process as described above for Example II except that
in this instance the inorganic solids content of the waste
cellulose fibers (which were input to the slurry at 5%
inorganic solids) was adjusted upwardly by the addition of
silica sand having an 8 micron mean size to raise the total
content of inorganic ~olids in the slurry to X8~, thus reducing
the content of organic cellulose fibers to approximately 71%.
The amount of latex emulsion and Alum remained unchanged, as
did all other variables in the process.
The resulting liquid absorbent material exhibited a
bulk density of 11.7 lbs./ft~3 and showed an absorptive
capacity of 204~ o its weight after one minute, 20~ after one
hour~ and 213% after 16 hours. The material has proved
excellen~ as a flushable kit~y or pet litter since the addition
of inorganic ~olids increased the bulk density to a level which
enabled used litter material to be readily flushed down a
toilet, whereas the materials of Examples I and II tend to
float on the surface o the toilet water unless left unflushed
for a sufficient period of time as to be completely wetted by
the water.
A hydrophobic liquid absorbent material was prepared as
follGws:
A water/solids slurry containing ~6.5% water and 3~5%
total solids was prepared in precisely the same manner as
described above in conjunction with Example I except that in
this instance the solids were sized by the addition of
Nuepfor 635, a resin material marketed by Nercules Incorporated
-18-
` 13~3~
of Wilmington, Delaware. To this end, approximately 3% resin
by weight was added to the slurry, reducing the content of
waste aellulose fibers in the slurry to approximately 96%.
The quantity of latex and Alum remained ~he same. After
suitable agitation, the slurry was transflerred to the press in
precisely the same manner described above for Example I; but,
in this instance a water insoluble ionic wax was added to the
slurry during the transfer in a quantity ~omprising 1.5% of
the total solids present in the slurry. While those skilled
in the art will appreciate that various types of water 501uble
ionic waxes may be added to the slurry, excellent results were
achieved when using either Paracol 802N (Trademark) or Paracol
700N ('rrademark), ionic waxes available from Hercules
Incorporated of Wilmington, Delaware. The water aon~ent of
the slurry was then reduced in the belt-type press to form a
press cake constituted by 40% total solids and was shredded in
precisely the same manner as described above in Example I. As
the shredded particulata material was passed through the
conditioning conveyor, a non-ionic wax emulsion was sprayed on
the tumbling particulate material in an amount equal to 4% of
the material's weight along with the surfactant. Again, those
skilled in khe art will appreciate that various types of non-
ionic waxes may be employed to enhance the hydrophobicity of
the product; but, excellent results have been observed when
the non-ionic wax was comprised of either Cascowax EW403H
~Trademark) as provided by Bordon, Inc. of Columbus, Ohio or a
silicon material manufactuxed by ~nion Carbide Corporation of
Sistersville, West Virginia marketed under the product
designation LE9300. The product was then dried in precisely
the same manner described above in connection with Example I.
The resulting product was then tested for its ability to
absorh oil spills on water. The product had a bulk density of
7~4 lbs~/ft.3; and, when placed in water containing an oil
spill, readily floated. Indeed, the product remained floating
long after all oil had been absorbed; effectively absorbed a
quantity of oil equal to 246% of its weight in less than 16
,, . ~
,
~3~3~6~
-- 19 --
hours; and, thereafter remained floating for a sufficient
period of time to have permitted its removal from the water
with all absorbed oil. However, the absorben~ material with
the absorbed oil was permitted to remain in the water. It was
noted that after 24 hours, some sinkage began to occur; but,
all of the material did not sink until two ~2) weeks had
elapsed. After sinkage, the product exhibited some propensity
to release a portion of the absorbed oil.
Those skilled in the art will appreciate that the
quantities o the process additives used in Example rv are not
critical, and may be varied as desired and/or requiredO For
example, while the amount of resin ~Nemphor 635) added to the
slurry in Example IV was 3% resin by weight, excellent results
have also been obtained using both less and more resin--for
example, from 2% or less to 4% or more resin. Similarly, the
amounts of ionic and/or non-ionic wax employed may also differ
from the quantities used in Example IV dependent on the results
desired.
~_Y
A ~econd hydrophobic absorbent material embodying
features of the present invention was manufactured as follows:
A water/solids slurry was prepared in precisely the
manner described above in Exxmple I~ Thereafter, the slurry
was transferred to a Parkson Co. belt press for dewatering in
the manner previously described; but, as the slurry was
transferred, 3% by weight of a liquid plastic of the type
manufactured by Betz Paper Chem~ Inc. of Jacksonville, Florida
and marketed under the product designation DPS863C was added to
the slurry. m e product was then dewatered, shredded,
conditioned and dried in precisely the manner described in
~xample I.
The resulting product had a bulk density of
7.7 lbs./ft.3, an affinity for oil spilled on water and an
absorptive capacity for oil of 326% of its weight after one
minute~ 330~ after one hour, and 336% after sixteen (16) hours,
by which time all oil in the spill had been absorbed. As in
!i
~.3~3~6~
- 20 -
Example IV, it was noted that product sinkage did not begin
until more than 24 hours after the absorbent material was
placed in the water--i e~, long after full absorption had
occurred, thus permitting ample time to have removed the
product and the absorbed oil. Indeed~ sinkage of all of the
absorbent media did not occur for three (3) weeks; and, even
then the product retained all of the absorbed oil and none was
released.
One additional advantageous application for liquid
absorbent materials embodying features of, and made in
accordance with, the present invention comprises usage as a
shock absorbent packing material for packaging
containers--particularly containers of noxious and/or toxic
chemicals and/or liquids. Thusr the absorbent media of the
pre5ent invention is both suitable and highly effective as a
replacement for conventional packing materials such as
~vermiculite", an expanded silica material containing fibrous
silica dust in the form of asbestos. ~ot only is the absorbent
material effective for its shock absorbing properties, but,
moreovert in those instances where the containers leak, the
absorbent media of the present invention serves to effectively
absorb and retain the leakin~ liquid, thereby preventing
;~ hazardous spill8 which might otherwise occur--all without any
dust problem and particularly without distribution of hazardous
asbestos dust.
Thus, those persons skilled in the art will appreciate
that there have herein been disclosed improved processes for
forming imprcved liquid absorbent media which may be either
hydrophilic or hydrophobic and which, in either case, are
; 30 characterized by: i) their loose porous cellulose iber
structure essentially devoid of appreciable amounts of
inorganic solids or 0fillers"~ 9, a cellulose ~iber
s~ruc~ure having minimal inorganic solids content as closely
approximating 0% inorganic solids by weight as possible (except
where inorganic solids are added to such material when intended
for use as kitty litter or the like to improve flushability of
3 ~ ~ ~
- 21 -
used litter) and, in any event, less than 30~ inorganic solids
by weight; ii) a relatively low bulk density (not ~ore than
13 lbs~/ft.3 and preferably 6-10 lbs./ft.3); iii) high
absorption rates and capacities; iv) high flammability and
consequent high heat values produced when incinerated with
attendent minimal ash and disposal costs; and v), lack of a
fuzzy surface texture with consequent recluction of dust and
attendant irritation to humans and abrasion of equipment, as
well as reduced explosion hazards.
