CA2211589A1

CA2211589A1 - Polyurethane foam cleaning pad and absorbent particles

Info

Publication number: CA2211589A1
Application number: CA002211589A
Authority: CA
Inventors: Charles William Mitchell (Deceased)
Original assignee: ABSORB-X ENVIRONMENTALLY FRIENDLY PRODUCTS LIMITED
Current assignee: MITCHELL CHARLES WILLIAM (DECEASED)
Priority date: 1997-08-13
Filing date: 1997-08-13
Publication date: 1999-02-13

Abstract

A cleaning and absorbing agent for petroleum-based products comprises a rigid, closed-cell polyurethane foam having a detergent entrapped within the cells. The cleaning and absorbing agent is preferably in particulate or granular form and may be combined with a suitable carrier. Method aspects of the invention are also described.

Description

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 o ~-, o o o o ~ U7 o ~~
~U oo o o Q oo o ~, _, ~ ~ o --~ o o o ¢ .. ~
o o o o O ~
L~ OO O
~d ~O
3 ~ ~ ~ o ~
Q o o o _. ~ ~ o o o o oo o ¢

-o_, ~, ~¢ o r~

W o <~
o _, Z¢ t~

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.

Claims

1. A cleaning pad adapted to remove oil-based stains from a surface, said pad comprising a block of rigid, closed-cell polyurethane foam having detergent encapsulated therein.

2. The cleaning pad of claim 1 wherein said rigid polyurethane foam has a density in the range of 1 pound per cubic foot to 10 pound per cubic foot.

3. The cleaning pad of claim 1 wherein said detergent is a liquid detergent encapsulated within the closed-cells of said polyurethane foam.

4. The cleaning pad of claim 1 wherein said detergent is a dry detergent encapsulated within the closed-cells of said polyurethane foam.

5. An absorbent for use in absorbing liquid petrochemical materials, said absorbent comprising a rigid, closed-cell polyurethane foam having a detergent incorporated into said foam.

6. The absorbent of claim 5 wherein said foam is in particulate form.

7. The absorbent of claim 5 wherein said polyurethane foam has a density in the range of 1 pound per cubic foot to 10 pounds per cubic foot.

8. The absorbent of claim 1 wherein said detergent is a liquid detergent.

9. The absorbent of claim 5 wherein said rigid foam is in particulate form wherein the size of each particle is of a size such that no closed-cell is complete.

10. The absorbent of claim 6 wherein said petrochemical material is oil.

11. The absorbent of claim 6 wherein said petrochemical material is gasoline.

12. The absorbent of claim 7 or 8 wherein said petrochemical material is on a dry surface.

13. The absorbent of claim 7 wherein said oil is floating on water.

14. A cleaning agent for use in removing petrochemical materials from a surface of said cleaning agent comprising a rigid, closed-cell polyurethane foam including entrapped detergent, said foam being in particulate form and combined with a carrier.

15. The cleaning agent of claim 14 wherein said carrier is lanolin and glycerin.

16. A method of making an absorbent for absorbing liquid petrochemical materials, said method comprising the steps of:
(a) combining liquid polyurethane resin and liquid detergent in the ratio of 54:1, (b) combining the mixture of (a) with isocyanate foaming agent in the ratio of 1:1, (c) forming a rigid, closed-cell polyurethane foam, and (d) comminuting said foam into particles.

17. The method of claim 16 wherein said comminuting step is such that the particles formed thereby are of a size wherein virtually no cells are complete.

18. The method of making the absorbent of claim 16 wherein said liquid detergent is encapsulated within said closed cells during the foaming step.

19. A method of absorbing and recovering an oil spill from a surface comprising the steps of:
(a) covering the oil spill with particles of a rigid, closed-cell polyurethane foam having encapsulated therein a liquid detergent, (b) collecting the particles having absorbed therein the oil spill, and (c) centrifuging said particles to separate said oil therefrom.

20. The method of claim 19 wherein said surface is a dry surface.

21. The method of claim 19 wherein said surface is water.