Note: Descriptions are shown in the official language in which they were submitted.
~WO 96/01915 PCT/US95/08462
.?_ 170364
COMPO8ITIONB AND 1LETHODB FOR
TREATING CLEANING 80LVENTB
BACKGROUND OF THE INVENTION
The present invention relates generally to automotive,
industrial, and commercial parts cleaning, and, more
particularly, to improved formulations for increasing the
effectiveness of cleaning solvents.
In industry today, there has been an increasing
awareness of the importance of washing mechanical parts.
In almost every repair, reconstruction, and rebuilding of
motors, engines, and/or machines, it is necessary to clean
oily, greasy, or otherwise dirty or contaminated parts
before they can be repaired and reassembled. Further, in
a number of cases, machining and refabricating operations,
particularly those carried out on metal parts, leave
residues or contaminants which are desirably cleaned before
the part or component in question is reassembled or
otherwise the subject of a completed operation.
In most cases, the kind of dirt and contamination
which has accumulated on metal parts is that of an oily,
greasy residue. In the case of automotive, truck,
agricultural, and earth-moving construction machinery
components, the parts in question gradually become covered
with oil or grease that has leaked from the crankcases or
gear housings of the machines, and these in turn attract
dust, sand, dirt, and other constituents of the environment
in which they work. Almost all oils and greases have the
capability not only of attracting dust and dirt, but also,
in effect, of acting as an adhesive for these and other
contaminants.
Normally, for reasons of rust prevention, and
particularly for reasons of solubility, such parts, being
possessed of an oily, greasy residue, are best cleaned
using hydrocarbon-based solvent systems rather than aqueous
WO 96/01915 PCT/US95108462
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systems. The use of aqueous systems calls for using large
quantities of water and requires emulsifying the oil and
grease that is, in effect, serving as a dirt binder. Such
cleaning, while effective if conducted properly, involves
time-consuming washing/emulsification/saponification steps
followed by rinsing and subsequent application of a
corrosion inhibitor coating. In addition, disposing of
oil-containing residues is sometimes subject to prohibition
or regulation.
Accordingly, rather than pursue this method, most
parts are simply washed in a hydrocarbon-based solvent that
is compatible with the oils and greases in question, and
which therefore serves to remove the dirt quite rapidly and
effectively. This is particularly true when combined with
a scrubbing or mechanical agitation action, i.e., brushing
or dipping and agitating of parts, or both. Where the
solvent is confined to a recirculating washer, the solvent
need not be disposed of in violation of environmental
regulations.
In connection with the use of hydrocarbon-based
solvents, certain problems arise. These include
environmental and fire hazard concerns, one consequence of
which has been the increasing use of relatively high flash
point solvents. In many cases, these solvents used have a
flash point of 100°F or above and are primarily aliphatic
in nature with a certain aromatic constituent. Newer
solvents. have a 150°F or higher flash point and are
predominantly or almost exclusively aliphatic.
Referring to the equipment used in parts washing,
while simple dip tanks have been known to be used with some
effectiveness, the most cost- and labor-effective method of
small-scale parts washing, (i.e., that carried on in
maintenance, repair, and rebuild shops and garages and
industrial fabrication and assembly facilities of all
sizes), has been to use parts washers which include a sink
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or the like positioned atop a reservoir of hydrocarbon-
based solvent and wherein this solvent is circulated from
the reservoir though a pump and directed over the parts
being cleaned from a nozzle at the end of a conduit or the
like. Parts washers using such hydrocarbon-based solvents
include those of the general type described in U.S. Patent
3,522,814, of which many hundreds of thousands have been
sold and/or are in use.
Referring again to automotive, industrial, and
commercial parts washing, when the cost of hydrocarbon
based solvent was very low and the regulatory atmosphere
was somewhat lax, it was not uncommon to provide a rather
crude filter to be used with such solvent and for the
solvent to be changed by a route or serviceman every two to
four weeks. The used solvent would be picked up by the
route man, who then furnished a charge of new solvent for
the parts washer. This cycle would commonly be repeated on
a two to four week cycle or as needed.
When hydrocarbon-based solvent prices were low, this
was an economical, common sense approach to parts washing
problems. The combination of the relatively crude filter
and simple gravity settling provided a gross separation of
contaminants which was satisfactory for the times in
question. Now, however, hydrocarbon-based solvent costs
are much higher, and environmental regulations are such
that it is much more desirable to ensure maximum use and
re-use o~ a particular charge of solvent. However, this
desirable state of affairs has not heretofore been able to
be fully achieved in practice.
One characteristic of parts washer solvent that has
been subjected to even comparatively few washing cycles is
that the dirt entrained therein includes finely dispersed
particles, many of which may be of sub-micron size. While
sand, gravel, metal filings, and the like cleaned from
dirty or greasy parts rapidly settle out, a significant
WO 96/01915 PCTIUS95/08462
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portion of the contaminants in solvent used for parts
washing is comprised of very fine particles that are
resistant to settling. As a result, while the solvent's
cleaning effectiveness may not be impaired, due to the
dispersed and unsettled contamination, it may be difficult
to determine visually that the solvent can still be used
effectively. Consequently, such solvent may be changed
more often than needed.
If it were possible to achieve a greater separation of
dirt and particles from the mass of solvent within a finite
time, say fifteen minutes to one hour, the effectiveness
and useful lifetime of much parts cleaning solvent would be
greatly increased. It is possible that, by positioning the
liquid pump inlet an appropriate distance from the bottom
of the reservoir, if there were highly effective gravity
separation of contaminants, the pump could continue to
circulate comparatively clean solvent, while the case, the
contaminants would continue to self-separate by gravity.
Thus, the supernatant liquid within the reservoir would
remain clean and be able to be used over a much longer
period of time.
In speaking of reclamation of hydrocarbon solvents,
being that the current regulatory atmosphere in some ways
promotes this practice, when recycling of the hydrocarbon-
based solvent used in parts cleaning is called for, i.e.,
by filtration, distillation of the solvent at a recycle
center, and/or by various other commonly known methods, an
economic price is extracted both for recycling very dirty
solvent and also for distilling solvent that has sufficient
solids suspended so as to be of reduced effectiveness in
use as a cleaning material.
If it were the case that a greater separation of the
dirt and particles in used or spent hydrocarbon-based
solvent could be achieved, recycling would be simplified in
that the major portion of the contaminants could be removed
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into a contaminant rich layer by physical separation, thus
reducing the accumulation of sludge in the distillation
phase of recycling. Heat transfer would be better and
equipment damage would be minimized if the solvent that was
ultimately recycled by distillation were cleaner when
entering the distillation phase of recycling.
While it is not known with certainty all the reasons
why the contaminants in parts cleaning hydrocarbon-based
solvent are apparently so highly resistant to gravity
separation, it is known that modern motor oil, cutting and
machining fluids, and grease formulations include
detergent/dispersant additives which form a part of the
dirt and grime which accumulates on mechanical parts, both
inside and outside sealed machine areas. The
detergent/dispersant additives remaining in these oil,
fluid, and grease residues may serve to suspend fine
contaminants within the cleaning solvent and prevent their
separation by gravity or filtration.
In any case, it would be considered extremely
advantageous to provide at low cost a cleaning solvent that
would provide much better particle separation from the
majority of the liquid phase of parts cleaning solvent than
is presently able to be achieved.
In view of the failure of the prior art to provide a
solvent composition that enhances particle settling, or
which can be treated so as to rejuvenate dirty solvent by
separating contaminant particles from the body of the
solvent, it is an object of the present invention to
provide a composition which can alter or modify used or new
solvent to restore its cleaning effectiveness.
Another object of the present invention is to provide
a treatment which will restore the original ability of pre-
treated solvent so as to cause separation of dirt and other
contaminants therefrom.
WO 9GI01915 PCT/US95I08462
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A still further object of the invention is to provide
an enhanced solvent composition that greatly accelerates
dirt and particle separation and which can be repeatedly
used to clarify solvent which continues to be contaminated.
A further object of the invention is to provide a
solvent additive that is physiologically benign and is
effective in small concentrations.
A further object of the invention is to provide at
least two separate treatments for a cleaning solvent, that
may also be used in combination with each other, one being
an enhanced solvent which will greatly accelerate
particle settling during initial washing operations and
another subsequent treatment which will enhance the
settling rate of contaminants from solvent, whether
enhanced or not, so as to extend solvent service life in
use.
A further object of the invention is to provide a
solvent additive which is able to be blended with parts
cleaning solvents and that is economical and not
environmentally objectionable.
Another object of the invention is to provide a
solvent additive selected from the class consisting of
aromatic, aliphatic and alkaryl sulfonic acids and sulfonic
acid salts; alkyl phenol formaldehyde resins modified so as
to include alkoxy solubilizing groups forming a part
thereof, esterified polyols, and mixtures of the above
acids, said resins, and such esterified polyols.
A further object of the invention is to provide an
additive which causes the cleaning solvent in which it is
used to exhibit an accelerated settling and
demulsification/flocculation action to fine contaminant
particles suspended within the body of said solvent.
A still further object of the invention is to provide
a method of cleaning parts using a cleaning solvent, which
method comprises cleaning parts until a mass of solvent
_ WO 96/01915 ~ PCT/LTS95/08462
undergoes reduced visual clarity, and thereafter treating
the solvent with an additive composition to clarify said
solvent so as to extend its effective cleaning life.
Yet another object of the invention is to provide a
parts cleaning method which includes periodically adding a
demulsifying agent to parts washer solvent which is
becoming contaminated with fine suspended particles and,
after continuing to use the solvent to the point of
substantially reduced visual clarity, again clarifying the
solvent by again adding the same additive composition.
A further object of the invention is to provide an
additive which is effective to clarify cleaning solvent
contaminated with fine suspended particles and which is
effective in the presence of water and other additives for
the solvent.
Another object of the invention is to provide an
additive for a cleaning solvent which additive is
compatible with solvent recirculating machinery including
recirculating pumps and motors.
A still further object of the invention is to provide
a solvent additive which accelerates the settling of finely
dispersed suspended particles in a manner which does not
significantly increase the hazards of fire and toxicity
presented by the solvent.
Another object of the invention is to provide an
additive composition for cleaning solvent which is readily
available and is not excessively costly in view of its
advantages and performance characteristics.
WO 96/01915 PCT/US95/08462
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2
_8_
DESCRIPTION OF THE PREFERRED-
EMBODIMENTS OF THE INVENTION
Inasmuch as one important object of the present
invention is to provide a solvent which, when used in a
parts cleaning or similar operation, will provide maximum
settling out of particulate contaminants in the shortest
possible time, with the object of effectively dividing a
mass or volume of solvent into a relatively clear
supernatant layer overlying a contaminant-rich lower layer
of greatly decreased volume in relation to the volume of
the supernatant layer, certain baseline criteria were
established using existing cleaning solvent. For this
purpose, and for providing the controls used in the
examples referred to herein, several operations were
conducted. Before referring in detail to these operations,
a general description of them will be furnished.
The solvent used as a baseline and considered to be
typical of contaminated parts washers solvent was taken
from parts washing machines in the midwest periodically
serviced by the assignee of this invention. Depending upon
the duty cycle or the work load at any particular location,
parts washers are serviced at varying intervals by picking
up old, contaminated solvent and replacing it with new
fresh solvent. The pickup intervals usually range from two
to twelve weeks.
The solvent in many instances originally comprises a
batch of. 18 gallons for a 30 gallon parts washer unit of
the type shown in U.S. Patent No. 3,522,814. In the course
of servicing each individual parts washer, the residual
dirty solvent therefrom is picked up by a serviceperson,
and this solvent is ultimately all combined into a holding
tank at a service center. Subsequently, such solvent
batches are normally collected from the service centers and
taken to a recycling center where recycling operations are
performed on the solvent.
~. WO 96!01915 217 0 3 6 4 p~~S95108462
-g-
Thus, in a particular region of the country, the mass
of recycled solvent resulting from periodic servicing tends
to be of a generally uniform character, although each
individual parts washer may be a source of used solvent
which is quite different from that of another given
individual parts washer. Customarily, the parts washers
use a solvent which is primarily aliphatic but may contain
up to 15 percent aromatic components, and has a flashpoint
of 105°F or higher or as solvent "SK-105". This is
sometimes referred to herein, and in the charts and tables
as a standard solvent. The aliphatic component usually is
made up primarily of C8-C13 alkanes. In other instances, to
which reference will be made, a higher flashpoint solvent,
such as a 99+ percent aliphatic solvent is provided, and
this solvent has a flashpoint of 140°-150°F or higher. The
hydrocarbons are usually a mix of Cg-C15 alkanes. This
solvent is sometimes referred to herein, and in the charts
and tables as solvent "P-150".
In keeping with the invention, pickup of used solvent
or incident to a service call occurs when users of the
service encounter one of two conditions. One of these
conditions results from a diminution in the effectiveness
of the solvent for cleaning purposes when it becomes
saturated, or nearly so, with solubilized contaminants such
as oil, or suspended particles of grease and other
components that are truly soluble in the solvent. In such
a case, effective solvent action is no longer possible; the
solvent has exhausted its potential as a cleaning agent and
is no longer effective. In such a case, recycling is the
only choice left.
However, a much more common case is that the solvent
is too dirty and contaminated with suspended particulates
to continue to be effective. This judgment is usually
based on visual observation. Between the time operations
are begun with a fresh batch of solvent and the time the
WO 96/01915 PCT/US95108462
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service call is made, evaporative losses, contamination
from dirt of all kinds, water, etc. occurs; and a gradual
dirtying of solvent takes place. This is a natural
incident to washing parts in the automotive industry,
and/or in manufacturing, construction, agriculture or like
industries wherein ferrous and non-ferrous metal mechanical
parts are customarily cleaned using parts washer solvent
(hereinafter generically referred to as "PWS") and cleaning
equipment designed for this purpose.
The contaminated solvent received from a solvent
collection and replacement service center was initial'y
analyzed to provide a base-line or control for the various
experiments referred to herein. One of the first steps
performed was simply to pour a series of specimens or
aliquot portions of used solvent into a graduated cylinder,
a specially equipped drum, or the like and note the extent
to which observable turbidity will spontaneously dissipate,
i.e., whether and to what extent to which the solvent will
separate spontaneously into two or more layers, one clean
and one dirty.
Certain of these experiments are referred to in detail
herein, but in summary, it was determined that a certain
amount of contamination will settle by gravity within the
first half hour after agitation. Thereafter, untreated
contaminants tend to remain somewhat uniformly dispersed
throughout the mass of solvent, and additional time does
not result in material clarification of the solvent. The
dispersion depends on a particle size, but in a wide range
of sizes, certain particles appear to remain suspended
indefinitely. Typically, the total suspended solids
("TSS") in used PWS requiring service were about 1,000-
14,000 ppm in the supernatant layer, depending on the
application. This is, in effect, an end point beyond which
self-cleaning by gravity does not occur.
_._WO 96/01915 217 ~ 3 6 4 pCT~S95/08462
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For purposes of the following discussions of the
nature and effect of particle size in solvent
classification, the particle size range of solid
contaminants suspended in PWS was divided into seven
groups, ranging from 70+ microns to 0.45 microns, as is
described later.
Regarding settlement rates generally, larger and more
dense particles settle out more rapidly. Some particles
are large and/or dense enough to settle without assistance
in a finite time. Consequently, in a given specimen of
solvent, as time passes, the concentration of suspended
solids becomes somewhat less near the top of a column of
such solvent. However, in general, with particles of 20~
and smaller, these settling rates are so slow that the
solvent appears uniformly dirty to the naked eye, and it is
the accelerated settling of these particles with which the
present invention is primarily concerned.
Referring to another aspect of the present tests,
inasmuch as it was desired to test the effectiveness of
certain additives in accelerating the rate of settling,
i.e., greatly enhancing the extent to which particulate
materials would separate from a mass of solvent, another
series of steps was carried out. These are a part of a
process intended to recognize that solvent in a parts
washer initially tends to become dirtied in the process of
cleaning, after which the parts washer is not used for a
given time, ranging from minutes up to days. The washer is
thus used on an intermittent basis or duty cycle throughout
the service interval, with additional dirt and contaminants
continually finding their way into the solvent over a
period of time.
Thus, a material that might be effective to create
solids separation from a solvent should desirably be able
to remain effective when a treated volume of solvent,
already contaminated to a certain extent, is subsequently
WO 96/01915 PCTILTS95/08462
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-12-
subjected to additional contamination. To simulate this
condition, tests were performed wherein a given batch of
solvent was divided into several aliquot portions. When
the first aliquot portion was subjected to chemical
additions to effect a clarifying or particulate settling
action, the supernatant layer contained a greatly
diminished level of contaminants. In order to determine
the continuing effectiveness of such additives, more
contaminants were added in a plurality of subsequent steps.
These subsequent evaluations of settling action were
termed "cycles" and were initiated by taking additional
individual aliquot portions of the original solvent batch
and separating the bottom sediment, water, and other
contaminants therefrom by centrifuging. After this "spin
down" operation was conducted on each of several aliquots,
the respective supernatant layers were discarded, and the
individual remaining "spun down" contaminants were the
concentrated contaminants that were then added successively
to the supernatant of the original or first aliquot that
had been treated with the modifying chemicals.
This, in effect, created a standard to determine how
effective any particular solvent treatment could be in
enhancing separation of contaminants subsequently placed
into a given solvent batch. This closely approximates real
life or field conditions wherein the solvent continues to
be contaminated, while also being allowed period of non-use
wherein settling can occur.
Referring again to certain general aspects of the
present invention, it will be therefore appreciated that an
advantageous solvent treatment will have the advantage of
at least initiating, perhaps continuing contaminant
separation, preferably at a relatively high rate.
Additionally, a favorable product will be able to continue
to provide layer formation and contaminant separation
generally over a relatively extended period of time,
217034
_ WO 96101915 PCT/US95108462
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including time during which clarifying chemicals are
periodically added. Another aspect, which is equally
important, in the visual appearance of the supernatant.
This is because its appearance is often a controlling
factor in determining when to initiate recycling.
Referring now generally to one aspect of the
appearance matter, a number of tests were performed wherein
a qualitative visual analysis of the effectiveness of
different materials used to create settling can be
demonstrated. Here, when a dirty solvent specimen taken
from a service center and used as a control is placed in a
transparent graduated cylinder, the control substance will
typically be a dark grayish-black to brownish-black color
with little visual clarity, and will remain turbid for an
indefinite period of time. When additives used in
accordance with the invention are placed in this solvent,
an interface between an upper, clarified layer and a lower,
contaminant rich layer appears, and this interface can be
seen to move gradually downwardly until an equilibrium is
approached or reached.
The height of the interface relative to the original
column height at various times, the time required to reach
equilibrium and the ultimate position of the interface can
all be measured to determine these characteristics. As
pointed out, where the solvent is recontaminated, this test
is then periodically repeated or put through "cycles" to
determine the residual effectiveness of the additive. This
is done by adding contaminants and agitating the old, but
treated solvent to which new contaminants only have been
added.
According to the invention, it was found that a number
of products were effective to promote contaminant settling
in both pretreated solvent and in untreated solvent.
By "pretreated" is meant solvent which, in addition to
its customary or conventional makeup of substantially all
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-14-
aliphatic hydrocarbons or of primarily hydrocarbons with up
to 20% aromatic solvents, is meant a solvent that has had
material of a different character added thereto to promote
settlement or interface formation. In this connection,
reference is made to copending application serial no.
2,170,363 filed July 6, 1995.
Such pretreatment is of a type wherein polar solvents,
including. but not limited to C8-C1o alcohols, diols,
glycols, polyols, and glycol ethers are added to the
hydrocarbon solvent. The addition of such chemicals makes
it possible to maximize the effect of using treatment
additives of the kind referred to herein. Thus, while the
additive compositions described herein are effective in the
absence of such pretreatment, they are advantageously also
used with pretreated solvent. The additive compositions of
the present invention may be used one or more times to
enhance particle separation from used cleaning solvent.
As a matter of illustrating the nature of the problem
encountered, and so as to distinguish it from liquid
processing generally, five specimens of spent parts washer
solvent were taken from tanks of collected, used solvent in
one or more service centers. Hence, the exact composition
of each of the specimens had come from a different source
and was different. These are referred to respectively in
Chart 1 as feed 1, feed 2, etc. A transparent cylinder was
used and a specimen of each feed was agitated thoroughly
and poured into the graduated cylinder. Thereafter, the
particle size of the dispersed particles in the solution
was analyzed. The size classifications are set forth in
the following Table 1:
A
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21703b4
-15-
SIZE CLASSIFICATION PARTICLE SIZE RANGE
Class 1 70~, or larger
Class 2 30 - 70~C
Class 3 20 - 30~
Class 4 10 - 20~
Class 5 5 - 10~,
Class 6 1.2 - 5~,
Class 7 0.45 - 1.2~
When each of the specimens was analyzed by the above
successive filtration, the total suspended solids,
expressed in parts per million by weight, within each of
the particle size classes was discovered to be as set forth
in Chart 1.
CHART 1
PARTICLE SIZE DISTRIBUTION OF SOME REPRESENTATIVE SPENT PARTS WASHER SOLVENT
m o00
~o
3 8 000
0
s_
H
H
O
2 5 ~ 6 000
H
7
N
/~
0
1 2 3 4 5 8 7
CIBSSIfICatl0~1 B~I SIZe
WO 96/01915 PCT/US95/08462
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Here, it will be seen that the concentration of
suspended solids in class 4, i.e., 10-20~ was much greater
than the concentration of any other particle size range.
In four of the feeds, there were between 7,500 and almost
11,000 ppm in class 4, i.e., the range of 10-20~C. In one
specimen, feed 4, there were about 3,000 of the 70+ micron
size particles (class 1), and in feeds 2 and 3, there were
about 2,000 each of two different sizes, one being the 30-
70 micron size (class 2) and the other comprising about
2,000 of the 5-10~C size (class 5). Thus, the particles
sizes sought to be separated fell in greatest proportion
within the 10-20 micron size (class 4), such size range
containing anywhere from just more than 2 to over 5 times
the content of any other size range.
Because of their larger particle size, particles
greater than 20-30 microns tend to settle somewhat rapidly
by themselves and are therefore not either a significant
contributor to the problem of dirty solvent nor do they
require unusual treatments. However, those in the 10-20~
and smaller particle size range do require treatment
because of their persistence in remaining suspended within
the solvent. In Chart 1, therefore, in each set of feeds,
the highest bar and the bars to the right thereof represent
total suspended solids of the moderate and smaller sizes
that require treatment according to the invention.
In summary, one aspect of the invention is to provide
an additive composition and method which greatly
facilitates spontaneous separation in untreated solvent,
and in another aspect of the invention is the ability of
separation-enhancing additives to cooperate with solvent
compositions which have previously been treated with the
alcohol/diol/glycol/polyol/glycol ether compositions
referred to in the above copending application. Such
products include, but are not limited to, 2-ethyl-1,3-
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_WO 96/01915 PCT/US95/08462
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hexanediol, diethylene glycol mono-butyl ether and
propylene glycol and butyl ether.
In view of their purpose, the additives discussed
herein and in the claims are sometimes referred to as
"clarifying additives". The extent to which these
clarifying additives can be used is set forth by way of
illustration in the table set out below. Table 2, below,
is a list of such additives, each assigned a legend for
purposes of simplifying the following graphs and charts.
LEGEND CLARIFYING ADDITIVE
CA-1 A mixture of nonyl and butyl-
substituted phenol-formaldehyde
resins having plural ethoxy or
propoxy groups. See illustration
below.
CA-2 CA-1 plus an alkyl or aryl sulfonic
acid or mixture.
CA-3 A mixture of petroleum naphtha,
ammonium alkyl sulfonates and
diethylene glycol mono-butyl ether.
(DEGBE)
CA-4 A mixture of petroleum sulfonates,
esterified polyols and CA-1.
In the foregoing, the structure of the main
20, constituent of CA-1 is believed to comprise the following
or a similar structure:
WO 96/01915 PCT/US95/08462
21 ~ X364
-18-
x
0
I C ~i
o-x
R
Where X = H, $thoxy or Propoxy and R = C3-C~5 alkyl
In the preferred compositions, R ie C4 C9j n is an integer
of 1 or greater, and the molecular weight is usually from
500-10,000.
The foregoing materials were sometimes utilized by
adding the same, either once or several times in sequence,
to a solvent composition that had previously been treated
with an alcohol/diol/polyol/glycol/glycol ether additive as
those referred to above. In some instances, the presence
of the clarifying additive augmented the desirable
characteristics of the solvent treated with the other
additive, especially when a limited amount of water was
present in the composition. Thus, the additives referenced
to herein were useful both with and without prior solvent
treatment.
As reflected in the following materials, the
clarifying additives were evaluated by various methods as
set out below.
A preliminary screening was done using these additives
with an SK-105 solvent, to determine whether such
additives, with parts washer solvents, would develop an
interface, and if so, where and to what extent after a
given settling time. The solvent in these examples was not
intentionally treated with any other composition.
Chart 2 shows the compositions and the results, with
interface height in arbitrary units reflecting the height
WO 96!01915 PCT/US95/08462
2170364
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of a graduated cylinder on the vertical axis and settling
time in minutes on the horizontal axis. Column 1 is the
control; Column 2 is CA-4; Column 3 is CA-1; and Column 4
is CA-2.
CHART 2
SCREENING OF CLARIFYING ADOIT1VE9 FOR APPLICATION W PWS
zso
s'~
H
Z
O
Z
w
U
Q
z
0
In these tests, all products were effective, with CA-2
and 4 showing the most promise.
Another test was administered to determine the total
suspended solids content of the supernatant after 70 hours
of settling. This is shown in Chart 3.
0 JD 60 90 t20 t50
3lTf1.110 TtM! I~w)
WO 96/01915 PCT/US95I08462
~ ~.5~~
2~
-2 0-
CHART 3
TSS CONTENT OF SUPERNATANTS OF SOME TREATED SAMPLES RELATIVE TO THE CONTROL
AFTER TO
HOURS OF SETTLING
10
H
H
H
20
Total suspended solids appear on the vertical axis and the
individual products appear in columns to the right as
follows:
In the above chart, only suspended solids of 0.45
micron and larger size are depicted. The left hand column
is a control, expressed in terms of TSS, and showing the
supernatant of an untreated solvent. Column 2 shows
solvent treated with 0.2 pph of CA-3 and 2 pph water.
Column 3 is the same as column 2 except that the clarifying
additive is CA-2. Column 4 is the same as columns 2 and 3
except that the clarifying agent is CA-1 and 2 pph of AI-1
is present. Column 5 is the same as column 2 except that
no water is present. Column 6 is a solvent treated only
with 2 pph each of AI-1 and water.
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2170364
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In these examples, although the active ingredient (AI-
1) proved most effective when used only with water, this
was true only after a very extended (70 hrs. ) time. The
duration needed for separation, however, was so long that
a much more rapid, even if less complete, separation was
sought.
Therefore, the next set of tests, as reflected in
Chart 4, shows the quality of the supernatant after only 60
minutes of settling. In Chart 4, The control is compared
with a second column treated with CA-4, and a third column
reflecting treatment with CA-1. The results range from 2_3
to 500 parts per million of total suspended solids after 60
minutes.
CHART 4
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OUALITV OF SUPERNATANTS AFTER i4 MINUTES OF SETTLING
The following Chart 5 shows similar findings except
that a longer settling time was permitted and the
performance of CA-2 is reflected in the fourth column.
WO 96101915 PCTIUS95I08462
2~~ X364
-22-
CHART 5
TSS AS A MEASURE OF THE CUALITY Of SUPERNATANTS IN ADDITIVE SCREENING
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Chart 6 below, is similar to Chart 5 above, except
that the clarity of the supernatant is expressed in terms
of turbidity rather than total suspended solids. The first
column is the control; the second column is the control
after treatment with CA-4; the third column reflects
treatment of the control with CA-1 and the fourth column is
the control treated with CA-2. In these instances, the
turbidity is expressed in units of NTU/5. Consequently,
the readings are approximately five times higher than they
would be according to the prior example, i.e., where
turbidity units are NTU/25. If fully diluted, each of the
specimens shown in this chart would equal or approach the
10 unit threshold for solvent that is clear enough to be
considered a highly satisfactory product.
..~WO 96/01915 2 7 7 0 3 6 4 p~~S95/08462
-23-
CHART 6
TURBIOITY OF SUPERNATANTS AFTER i4 MINUTES OF SETTLING TIME
no
10
s
m
a
20 Chart 7, below, shows turbidity readings after fifteen
minutes and 24 hours with a combination of the other
treatment ingredients in different proportions. The left
hand column shows a control with 2 parts CA-2, also treated
with 2 parts each of 2-ethyl-1,3-hexanediol (hereinafter
"EHD") and water; column 2 shows the same ingredients with
2 parts CA-2 but .5 part EHD and .5 part water. The third
column shows a concentration of 2 parts CA-2 and 1 part
each per hundred of solvent of EHD and water. It is clear
that the turbidity varies with time and also that the order
of effectiveness, is 2 parts, 1 part, and 1/2 part,
respectively.
WO 96/01915 PCT/US95/08462
21~ ~~64
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ruae"s~, runs ia,,a,
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Chart 8, below, compares the turbidity of supernatants
in a control sample and three other specimens after 15
minutes and after 24 hours. In each set of columns, the
first column is the control and the second column
represents the control treated with 0.2 pph of CA-1 and 2
pph of water. The third column shows a combination of the
control treated with 0.2 pph of CA-1 and 2 parts each of
EHD. The last column shows the control treated with 0.2
parts CA-1 and 2 parts each of EHD and water. This last
composition, the one in column 4, is clearly the most
effective. Given enough time, as is indicated by the 24
hour term of the second set of data, the 0.2 parts of CA-1
combined with EHD, in the absence of water is not as
effective in the long run as is the control, CA-1 and some
water.
In this connection, it will be realized that a certain
amount of water may be unintentionally or transiently
present in solvent but that the water is not dispersed
therein, at least in the absence of additives. With the
proper additives, including some of those which by nature
attract water, an effective mixture can be provided.
~.WO 96!01915 PCT/US95108462
Z~ ~Q~~4
-25-
CHART 8
TURGIDITY AS A MEASURE OF QUALITY OF SUPERNATANTS AFTER 16 MINUTES AHD =1
HOURS OF
SETTLING TIME RESPECTIVELY
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15
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TuRSns,~.~l ruAS n~ nn i
A number of other similar tests were performed on
various combinations of the above active ingredients and
clarifying additives. In this connection, it will be
reali2ed that, as commercially obtained, each of the
clarifying additives includes its own diluent, the
character and extent of which varies depending on the exact
nature of the clarifying additive. In some instances, the
compositions are referred to as from 50 to 75% "active"
ingredients, meaning that the sulfonic acids, resins, etc.
are present in 50 to 70% of the additive composition. Some
ingredients are present in much smaller proportions of the
additives as a whole.
Since it is impractical to perform measurements in the
absence of such diluent, the proportions given here may not
be totally exact with respect to the active components of
the additives. The percentages given are those applicable
to the products as they are normally packaged and handled.
Accordingly, some latitude in the appended claims is also
WO 96!01915 ~ ~ ~ O 3 PCTIUS95/08462
-26-
indicated. Actually, a clarifying additive may be present
in very small proportions. Thus, if the effective portion
of a clarifying additive comprises only 10 or 20% of the
entire weight of such additive, then, when an amount such
as 0.1 parts per hundred of additive is used on an overall
basis, the actual concentration would be 10 times less. By
way of example, where 0.1 pph equals 1,000 ppm, in the case
of a 10% active material, benefit could be obtained at
levels of 100 ppm and less.
From the foregoing, it will be seen that the present
invention provides a highly advantageous manner of
extending the life of washing solvent by a novel action of
concentrating the solvent in a lower layer and leaving the
supernatant layer of improved quality.
A very unusual and advantageous aspect of the present
invention is that even after creating the ability to cause
the solvent to separate into separate layers, one of which
is very clear, the active ingredient nevertheless appears
to be partitioned in large measure into the supernatant
layer.
Consequently, when the lower layer is discarded prior
to recycling, the water, sediment, and the like are
disposed of but the active ingredient remains largely in
the supernatant layer where it can serve to continue to
create a cleaned supernatant layer area. Because of the
manner in which parts washers are customarily used, this is
an extremely, important solvent-prolonging process that is
highly favorable to not only economics but also to
planetary ecology.
It will thus be seen that the present invention
provides improved solvent compositions and methods having
a number of advantages and characteristics, including those
pointed out herein and others which are inherent in the
invention.
_. WO 96101915 21 7 U S 6 4 pCT/US95/08462
-27-
A number of examples having been set forth by way of
example, it is believed that variations and modifications
to the described forms of invention will occur to those
skilled in the art and that such changes may be made
without departing from the spirit of the invention or the
scope of the appended claims.
