Note: Descriptions are shown in the official language in which they were submitted.
CA 02211~89 1997-08-13
This invention relates to novel methods and articles for use in
cleaning and absorption having particular application but not limited to the
absorption of petrochemical products and more particular to the absorption
of oil spills on water or dry surfaces.
It is known to use flexible polyurethane foams incorporating detergents
as sponges for cleaning purposes. Canadian patent 1,143,237 which issued
March 22, 1983 discloses such a sponge. This patent discloses a foam which
includes a clay filler resulting in a flexible hydrophilic cleaning device.
It is also known to use naturally occurring or synthetic substances to
absorb petrochemical based materials such as diesel fuel, crude oil or
bunker oil. For example, wood chips will absorb approximately their own
weight in crude oil while saw dust will absorb approximately five times its
weight in crude oil. These materials once saturated with crude oil are
virtually non-reusable and pose a significant disposal problem.
Accordingly, a material which can be processed to extract the absorbed oil
and leave the material suitable for reuse offers a ma~or economic and
ecologic advantage over the aforementioned naturally occurring materials.
Many of the synthetic absorbents are in mat or sheet form which results in a
handling problem when the structure is saturated with absorbed material. It
is also important, particularly when absorbing oil from water that the
absorbent be hydrophobic.
The absorbent of the present invention overcomes many of the
aforementioned problems ~n~- rh as it does not absorb water but will absorb
as much as 12 times its weight of crude oil and 15 times its weight in
bunker oil. Further, the material is in particulate form which means that
it can be qki ~1 or otherwise collected from the surface. Finally, a
simple centrifuge operation extracts the oil from the absorbent so that both
the oil and the absorbent can be reused.
The material of the present invention, however, is not limited to the
recovery of oil spilled on water. It is also particularly useful in
absorbing oil or gasoline spilled on a floor or asphalt surface. For
example, oil or gasoline spilled on a garage floor is quickly and
conveniently removed by the absorbent of the present invention. Similarly,
gasoline spilled on a highway as a result of an accident, or fuel spilled on
the tarmac of a runway may be quickly absorbed and removed without
CA 02211~89 1997-08-13
difficulty.
Further, the material of the present invention may be used in block
form as a scrubbing block to remove stains and particularly petroleum based
stains from dry surfaces. Additionally, the material may be ground and
S mixed with lanolin or glycerin type components to produce a paste-like hand
cleaner.
Thereforej in accordance with one aspect of the present invention there
is provided a cleaning pad adapted to remove oil-based stains from a
surface. The pad comprises a block of rigid, closed-cell polyurethane foam
having detergent encapsulated therein.
In accordance with a second aspect of the invention there is provided
an absorbent for use in absorbing liquid petroleum materials from a wet or
dry surface. The absorbent comprises a rigid, closed-cell polyurethane foam
having a detergent incorporated in the foam. Preferably, the absorbent is
in particulate form.
In accordance with a further aspect of the invention there is provided
a cleaning agent for use in removing petrochemical based materials from a
surface. The cleaning agent comprises a rigid, closed-cell polyurethane
foam including entrapped detergent. The foam is in particulate form and
added to a carrier to form the cleaning agent.
In accordance with a further aspect of the invention there is provided
a method of preparing an absorbent for petrochemical-based materials, the
method including the steps of combining liquid polyurethane resin and liquid
detergent in the ratio of 54:1 combining the above mixture with an equal
amount of isocyanate foaming agent, forming a rigid, closed-cell
polyurethane foam and c~ ~nl~ting or shredding the foam into particles.
A preferred embodiment of the present invention will now be described
with reference to the appended drawings wherein:
Figure 1 is a photograph of a cross-section of individual cells
magnified 50 times;
Figure 2 is a photograph of a cross-section of the foam showing
individual cells magnified 25 times;
Figure 3 is a photograph of the polyurethane foam in particulate form
magnified 51 times;
Figure 4 is a photograph of the foam of Figure 3 magnified 26 times;
CA 02211~89 1997-08-13
Figure 5 is a photograph of the particulate foam having absorbed oil
under magnification of 24 times; and
Figure 6 is the foam of Figure 5 magnified 51.5 times.
Polyurethane foams, which are cellular plastic materials, represent a
ma~or advance in the plastics industry. Polyurethane foam is generally
formed by the reaction of polyol compounds and organic polyisocyanates.
Cellular plastics are available in various degrees of rigidity ranging from
soft flexible foams to semi-rigid foams and rigid foams which are frequently
used for structural and insulation purposes. The final properties of the
foam depend mainly on the choice of polyethers, polyesters or other
polyhydroxyl compounds which are converted by the polyisocyanate into a high
molecular weight polymer which is then foamed by a suitable foaming system,
usually a reaction of water with the free isocyanate content of the polymer,
resulting in the formation of carbon dioxide which expands the resin into
the desired cellular plastic. The density of the foam is, to a great
extent, effected by the amount of water used.
Flexible and semi-rigid foams have a low density whereas rigid foams
have a higher density. Further, flexible and semi-rigid foams have an
open-celled structure which means that a high percentage of the cells are
interconnected. Rigid foams, on the other hand, usually have a
predominately closed-cell structure which means that each cell is isolated
from the ad~acent cell by a commonly shared wall.
It is polyurethane foam of the latter type which is used in the present
invention. Inasmuch as the literature contains considerable detail with
respect to the processes for producing rigid closed-cell polyurethane foam
further general description as to the production of the foam of the present
invention is not believed necessary. What is considered to be novel and
described in greater detail hereinafter is the addition of detergent to the
basic ingredients prior to the foaming step.
The detergent in the preferred embodiment is any common liquid
detergent as may be used in many household applications. In the preferred
embodiment, liquid detergent is mixed with the liquid polyether resin the
ratio of which falls in the range 1:50 to 1:60 with the preferred ratio
being 1:54. The liquid detergent and polyether resin is then mixed with the
polyisocyanates in a ratio of 1:1. The polyisocyanate used in this process
CA 022ll~89 l997-08-l3
is available from Dow Corning under the trade name ISO.
As a less preferred process, dry detergent can be used although a
different ratio is required. In this regard, it has been found that dry
detergent is added at the approximate rate of l ounce of detergent per pound
of liquid resin.
The process is carried out at room temperature although the process is
to some extent exothermic.
During the foaming step, the detergent is entrapped within each closed
cell and it is observed as a thin shiny film deposited on each wall of the
closed cell. Figures 1 and 2 show, under ma~nification, a cross-sectional
view through cells in the foam with each surface including a thin film of
the detergent.
For certain applications, it has been found that the polyurethane foam,
when formed in large sheets or slabs, may be cut by any suitable means such
as hot wire to a preferred size for cleaning purposes. The pads so formed
being in one embodiment approximately 1 inch by 2 inches by 3 inches and are
used in association with water or other cleaning agents to scrub a surface
which has loose oil-based material or a stain caused by an oil or
petroleum-based product. The scrubbing action of the rigid foam over the
surface causes the walls of the outermost cells to be broken thereby
releasing the entrapped detergent and the stain is removed. Since the foam
is hydrophobic, it does not absorb any of the water but the oil or oil stain
is caused to adhere to the inner walls of the broken cells.
It has also been found that the foam prepared in accordance with the
present invention, when comminuted into particles, creates an effective
absorbing agent. Preferably, each particle after comminution is no larger
than an individual cell. By way of further definition, the average size of
each individual cell is approximately l/64th of an inch from side to side.
Since it is the detexgent entrapped within and coated on the wall of
each cell that effects the cleaning and absorbing, it is important that the
majority of the cells are broken in order to absorb the m~imllm amount of
oil or other petroleum-based materials Figures 3 and 4 show, under
magnification, the absorbent of the present invention in particle form
The photograph of Figure 3 shows the particles magnified by 51 5 times
while the photograph of Figure 4 shows the particles magnified 26 times
CA 02211~89 1997-08-13
In the case of oil, gasoline, etc. spilled on a d n surface such as a
garage floor, highway or tarmac, the particles are spread liberally over the
spill and left for a period of time such as 30 minutes. At the end of this
time period, the absorbent may be picked up by suitable means such as a
shovel or scraper and retained in a suitable container The surface is dry
and basically free of the oil or other petroleum-based produce forming the
spill
If desired, the absorbent and oil may be further processed by means of
a centrifuge which forces the oil out of the cell~ in which it was received
and the absorbent is returned to its original condition for reuse.
The absorbent of the present invention is particularly beneficial in
the absorption of an oil spill on a river, lake etc. As in the case of a
spill on a dry surface, the absorbent of the invention is liberally poured
on the oil spill and left for a short period of time during which time the
detergent within the cell of each particle attracts the oil and retains a
globule therein. The particles upon entrapping the oil globules becomes
like a thick gel which may be ~k~ ed off the surface in any known manner.
This gel may then be processed by a centrifuge to separate the oil from the
particles and the particles are then in a condition for reuse. Obviously,
the oil after separation from the particles may also be further processed.
Figures 5 and 6 represent photographs of the absorbent in particulate
form after exposure to oil. Figure 5 illustrates the material magnified
24.2 times and Figure 6 is the same material magnified 51.5 times.
Tests were conducted under controlled conditions to determine the
absorption characteristics of the material of the present invention. The
following petroleum products were used in the test procedures:
Test Liquid Specific GravitY ViscositY (mPas)
diesel 0.83 3.3
crude 0.87 940
bunker (c) 0.99 6450
Two baths, each consisting of nine test cells filled to a depth of 30
cm with tap water were maintained at lO~C throughout the testing. The test
liquids were layered on the water and a pre-weighed sample of the absorbent
uas placed on the test system and left to stand for half an hour. A cover
CA 02211~89 1997-08-13
was placed over the baths to prevent evaporation of the test liquids.
Agitation was not applied to the system, however, the samples were turned
over once. After the given st~n~ing period, the samples were removed from
the bath, drained flat for several minutes and re-weighed. The water
content in the recovered fluid was dete ~ned by normal separation and
volume measurement or via liquid extraction using toluene when necessary.
The absorbent with respect to each test liquid was tested in triplicate
and the results averaged for each parameter calculated. The calculations
were based on the following:
(weight of test liquid, (initial
water and sorbent -(weight of - sorbent
Initial Capacity = after initial exposure) water recovered) wei~ht)
initial sorbent weight
(maximum weight (weight of
of test liquid, water -(weight of sorbent
Maximum Capacity = and sorbent)water recovered) used)
initial sorbent weight
Water Pick-up = wei~ht of water recovered
initial sorbent weight
The results of these tests are as shown in Table 1:
- . CA 02211589 1997-08-13
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CA 02211~89 1997-08-13
These results clearly indicate that in all cases, the initial and ~Y;
capacity are the same confirming the rapid adsorption characteristics of the
material. The results further show that very little if any water is absorbed
with the oil.
It has been found that the material ~f the present invention in
particulate or granular form, when combined with a suitable carrier such as
glycerin and/or lanolin provides a hand cleaning agent. The slightly abrasive
granules in combination with the carrier and the cleaning and absorption
characteristics of the foam results in an effective cleaning compound.
As indicated herein before, the polyurethane foam from which the
cleaning/absorbent agents are made is the result of normal processing
techniques. The resin/detergent mixture and the ISO are mixed by way of spray
nozzles which eject the two liquids into a mixing chamber from which the
combined mixture emerges by way of a single nozzle. The mixture ejected from
15 the nozzle is directed into a mold so as to produce a large block which, on
solidifying, produces the rigid or brittle cellular polyurethane structure
having closed cells of the type shown in Figures 1 and 2.
It has been found in certain applications that by the addition of
approximately 5 mg of baking soda per pound of resin, there appears to be some
20 neutralization of certain elements of the detergent which produces an improved
cleansing action. It has also been found that improved stain removal quality
may be achieved by adding approximately 1 gram of alum to the mixture prior to
foaming.
It has also been found that the oil absorption or attraction by the
25 particulate material may be improved in certain cases by reducing the amount
of detergent by approximately one half and by adding a light oil such as
vegetable oil to the mixture prior to foaming.
While the description relates to specific embodiments of the present
invention, it is expected that those skilled in the art may be able to devise
30 alternate embodiments that will fall within the scope of the amended claims.
