WO1999009134A1

WO1999009134A1 - A cleaning composition

Info

Publication number: WO1999009134A1
Application number: PCT/GB1997/002221
Authority: WO
Inventors: Michael Levey
Original assignee: Natural Marine Resources Limited
Priority date: 1997-08-18
Filing date: 1997-08-18
Publication date: 1999-02-25
Also published as: AU4021697A

Abstract

There is disclosed a composition for removing long chain compounds, which are substantially insoluble in water, the use of the composition in such removal and methods of cleaning. The composition comprises an inert gel matrix within which is entrained a solvent which is capable of dissolving the material of interest. Examples of materials to which application of this composition is suitable include bitumen, tar, wax and chewing gum.

Description

Title of Invention:

"A Cleaning Composition'

THE PRESENT INVENTION relates to a composition for the cleaning of unwanted materials, particularly long chain compounds which are substantially insoluble in water.

Over 815 million packs of chewing gum are sold in the United Kingdom each year. Typically the chewing gum, when finished, is not disposed of properly, in many cases being stuck on pavements, carpets or the underside of furniture. On average, every square metre of the pavements of the United Kingdom are covered with 20 individual pieces of chewing gum.

Chewing gum is one of a number of materials which are extremely difficult to remove from surfaces. Other such materials include glues, tars, bitumen, waxes, heavy oils and greases. The materials comprise long chain compounds which are substantially insoluble in water. Whilst certain of these compounds are able to be wiped off some smooth surfaces, others, such as chewing gum are extremely adhesive.

Because these materials are substantially insoluble in water, they are not easily cleaned using either water or an aqueous detergent solution. Many of them are dissolved or broken down by non-aqueous solvents, although several problems exist. Taking chewing gum as a prime example of a material with which this problem is commonly found, the non-aqueous solvents suitable for breaking down chewing gum typically provide several problems in their use. In particular, chewing gum, as with many of the other materials mentioned above, takes some considerable time to be dissolved and broken down to a state in which it is easily removable from a surface. However, in many situations, such as in the open or where the chewing gum has been applied to a non-horizontal surface such as a wall, ceiling or the underside of furniture, a liquid solvent will not remain in contact with the chewing gum for sufficient time to break it down to an extent to allow the chewing gum to be removed easily. Furthermore, the majority of the solvents useful for breaking down material such as chewing gum are relatively volatile and, therefore, evaporate quickly. Once again, the length of time that such solvents remain in contact with the chewing gum is not sufficient to allow the chewing gum to be broken down to an extent to allow cleaning of the chewing gum easily and efficiently.

There, therefore, remains, in the art, a need to develop cleaning compositions and methods to allow the breakdown and rapid and efficient cleaning of long chain compounds substantially insoluble in water, such as chewing gum, in an efficient manner.

According to the present invention there is provided a composition for removing a material comprising a long chain compound substantially insoluble in water from a surface, which composition comprises a non-aqueous liquid solvent in which a given long chain compound, substantially insoluble in water, is soluble, which solvent is entrained within a gel comprising a molecular matrix which does not substantially prevent diffusion of liquid therethrough and which is substantially inert to the non- aqueous liquid solvent.. The present invention also provides the use of such a composition for the cleaning of long chain compounds, substantially insoluble in water, from a surface.

There is also provided a method of cleaning from a surface a long chain compound, substantially insoluble in water, comprising applying thereto a composition according to the present invention in which the non-aqueous liquid solvent is capable of dissolving said long chain compounds.

The present invention solves the problems of the prior art by providing a composition in which the relevant solvent to be used is entrained within a gel matrix. By gel matrix is meant a molecular matrix which does not substantially prevent diffusion of liquid therethrough. Such a material is pliable and thus able to be applied to a given area but is sufficiently solid so as to remain substantially in position when applied. As such, the term "ge " as used herein includes certain pastes which have the required properties.

It is preferred that the gel does not react with the material to which the composition is being applied, and that it is not absorbed by the material to which it is applied. The gel will not react with the solvent entrained within the gel. The purpose of the gel is to hold the solvent in place, in contact with the material to be cleaned, for sufficient time to allow the material to be dissolved by the solvent. In this respect, as used herein, reference to "dissolution " of a material also includes chemical reaction so as to break the material down into smaller components.

Typical gels which provide appropriate molecular matrices for uses covered by the present invention include a number of known gels of either manmade or natural origin. The matrix may be formed from an inorganic material or a mixture of organic or inorganic materials, such as silica or clays. Particularly preferred materials include fumed or precipitated silica and/or mineral silicates, aluminium silicates, silicate clays such as bentonite, other clays such as kaolin (china clay) and Fuller's earth.

The solvent that may be used depends, of course, upon the material to be cleaned. Therefore, the types of solvents that may be used in the present invention are veiy wide ranging, although all are non-aqueous liquid solvents. Typical solvents include saturated and unsaturated aliphatic and aromatic hydrocarbons and their derivatives particularly alcohols, glycols, aldehydes, ketones, ethers, terpenes, phthalates, esters and mixtures thereof and halogenated hydrocarbons, all of which are liquid at the temperature of operation. Particularly preferred examples include hexane, toluene, di-pentenes (a mixture of d- and 1-limonene), orange-terpenes, ethanol, N-propanol, N- butanol, ethoxy-propanol, di-propyl glycol mono-methyl ether, tetrahydrofuran, iso-propyl acetate, methoxy propyl acetate, methyl iso-pentyl ketone, methyl ethyl ketone, per-chloroethylene, Portuguese gum terpentine (an alpha pinene and beta pinene mixture), terpen-4-ol, heptane, xylene, d-limonene, 1-limonene, methanol, iso-propanol, iso-butanol, N-pentanol, mono-propylene glycol, butyl di-glycol ether, iso-butyl acetate, ethyl acetate, acetone, cyclohexanone, di- chloromethane, tri-chloroethylene, Achilles pine oil, citral, tri-chloroethylene, per-chloroethylene, tri-chloroethane and di-chloromethane, although the last four halogenated hydrocarbons are less preferred because they present health and environmental hazards. Indeed, tri-chloroethane is a major ozone depleter.

Individual solvents need not be used alone. Indeed, in many cases, blends of solvents may be used. For example, a blend of 25% by weight d-limonene, 73% by weight ethanol and 2% by weight methanol may be used. Other preferred blends include a blend of 50% by weight di-pentene and 50% by weight iso-propanol, or 10 parts by weight d-limonene, 80 parts by weight ethanol and 3 parts by weight methanol which may contain 1 part by weight water in order to dissolve certain solvents that are insoluble in alcohols without a small amount (10% by weight or less) of water present.

As stated before, different solvents are particularly suitable for the dissolution of different materials. In particular, bitumen, tar and heavy oils are broken down well by hexane, heptane, xylene, toluene or d-limonene. Paints are broken-down by a mixture of methylene chloride and methanol or by methyl ethyl ketone. Inks may be removed by using cyclohexanone, tetra- hydrofuran. PVC and other plastics may also be removed using cyclohexanone or tetra-hydrofuran. Waxes may be removed by using, for example, hexane, heptane, xylene, or toluene. Glues may be removed by using, for example, hexane, heptane, xylene, toluene, d-limonene, methylene chloride, or tri- chloromethane, depending upon the base substrate of the glue to be removed.

As stated earlier, the materials to be cleaned are long chain compounds which are substantially insoluble in water, which materials include polymers, gums, waxes and resins such as glues, tars, bitumen, heavy oils, greases and candle wax. The term "substantially insoluble^'" as used herein is intended to mean less than 1% by weight soluble in aqueous solvents, preferably water, at ambient temperatures and pressures.

It is particularly preferred that the gel is, in fact, formed by mixing the solvent with an inert carrier. The mixture of the two components forms the gel, which is able to entrain a high proportion of solvent (typically greater than 80% by weight and most preferably greater than 90% by weight). In such circumstances, the gel comprises the non-aqueous liquid solvent and the inert carrier. It is preferred that the inert carrier has an extremely large surface area, a feature which may be found in, for example, fumed or precipitated silica.

In such circumstances, the inert carrier is added to the solvent or mixture of solvents, whilst stirring, to ensure even distribution of the carrier in the solvent. This, in turn, leads to the formation of the gel. The gel formation is not generally dependent upon temperature, although the volatility of certain volatile solvents should be borne in mind. The majority of gels according to this preferred embodiment of the invention are manufactured at ambient room temperature. It should be noted that the inert carrier does not chemically react with or form a chemical compound with the solvents.

It is preferred that the solvent to gel ratio in such gels is at least 8:2 by weight, preferably 9: 1 by weight and most preferably 9.5:0.5 by weight.

These gels are formed by the surface tension effects between the solvents and the inert matrices. In this respect, it is particularly preferred that the inert carriers forming the matrices comprise veiy fine particulate matter which allows a particularly strong surface tension effect to produce the gel. The surface tension between the solvent and the inert carrier matrix forms the gel and retains the solvent entrained in the gel. It should be noted that the finer the particles of a chosen matrix, the larger the surface area of the matrix and so the greater the surface tension effects between the matrix and the solvent. This, in turn, allows retention of greater amounts of solvent within the gel matrix so formed.

Examples of formulations of such gels, formed between a solvent and an inert carrier, are 94.5% by weight d-limonene in 5.5% by weight fumed silica, 95% by weight di-pentene in 5% by weight fumed silica, 80% by weight d-limonene in 20% by weight bentonite, 94% by weight xylene in 6% by weight precipitated silica, 95% by weight d-limonene in 5% by weight fumed silica, 95% by weight of a di-pentene in 5% by weight fumed/precipitated silica, 95% by weight orange and/or lemon terpenes in 5% by weight fumed/precipitated silica, or 95% by weight plant terpenes in 5% by weight fumed/precipitated silica.

The entrainment of the solvents within the inert matrix retains the solvents in place over the material to be dissolved for a sufficient time to allow the dissolution of the material. Furthermore, the entrainment of the solvents within the inert matrix allows the controlled release of the solvents due to the surface tension effects of the matrix and the solvent, which substantially reduce the flow of solvent out of the matrix and thus control the diffusion of the solvent to the material to be dissolved. In this way, the flow of solvents is restricted, thus allowing the gel to be used on non-horizontal surfaces, including walls and ceiling for considerable time, thereby allowing time for thorough cleaning and dissolution of a material adhering to the surface. Furthermore, the entrainment of volatile solvents within the matrix substantially reduces the rate of evaporation by restricting the ratio of surface area to volume. This further allows the continued contact of the solvent with the material to be dissolved for a considerable length of time, sufficient to allow dissolution of the material.

In this way, the compositions of the present invention are able to dissolve and remove long chain compounds which are substantially insoluble in water and which require prolonged contact with the solvent to allow their dissolution. This applies even in circumstances in which the materials to be cleaned are in an environment in which liquid solvents alone would not remain in contact with the material for a sufficient length of time, such as, for example, in the open air, in temperatures in which evaporation will take place too rapidly or on non-horizontal surfaces. It allows application of solvents to the material to be dissolved in circumstances in which it is not possible to place the item, on which the material is located, in a container of liquid solvent.

The compositions of the present invention preferably comprise a gel which will wet the surface of the material upon which it is placed The ability of the gel to wet the surface depends upon the surface tension of the solvent and the material to be removed, and a balance of the adhesion between the solvent molecules and the material to be removed and the cohesion between the solvent molecules. This is a function of the surface tension of the solvents within the gel and the material to be dissolved. Because, as mentioned before, surface tension effects of the matrix and the solvent reduce the flow of solvent and thus control the diffusion of solvent out from the matrix towards the material to be dissolved, the release of the solvents is controlled by this effect, along with the rate at which the material dissolves, the temperature, and the concentration grade into the material in the solvent. Because different solvents and blends of solvents have different surface tensions, consequently the gels formed using the solvents will have different surface tensions. Because the surface tensions of the gels can also be modified with the addition of surfactants which will dissolve on a chosen solvent, gels can be tailored to allow the release of solvent at a particular rate so as to ensure maximum dissolution of the material in contact with the composition of the present invention.

To choose a suitable solvent or solvent blend for removal of any given material, the basic test protocol is to take a measured volume of several selected solvents or blends of solvents (for example 100 mis) and to each add a measured amount of the material to be dissolved. The material should be observed within the solvents at regular intervals to observe the effect of the solvent (e.g. softening, dissolving). For a soft polymer, observations should be made relatively regularly, for example every five minutes. For a hard polymer, however, greater intervals may be required such as every hour.

The choice of matiix material will depend on the amount of solvent that the material will retain and whether the material will react with the solvent to be used.

To determine the amount of solvent that can be retained by a matiix material, a known quantity of solvent (say, lOOmls) is placed in a beaker and the matrix material to be tested is slowly added thereto, with constant stirring, until a gel of the required consistency and viscosity is formed. The remaining solvent is decanted and measured to determine the amount retained.

The stability of the remaining gel may then be checked by allowing the gel to stand for a few minutes (typically 10 minutes) and measuring the amount of solvent released. If the amount released is relatively minor (typically less than 1% by weight of the total entrained solvent) the gel may be considered sufficiently stable for the purposes of the present invention.

To confirm the inert nature of the matrix material with respect to the solvent the gel made as described above is left to stand for several hours, for example, 10 hours, and observed regularly, usually every 15 minutes, for signs of physical changes in the structure of the gel. Another test that should be carried out is to confirm that the matrix material does not dissolve in the solvent. To do this a gel matiix of interest is made using a predetermined amount of matrix material. This is left to stand for some time, say 2 hours. Any released solvent is decanted away and the gel is then dried completely. The remaining matrix material is then weighed to ascertain whether any substantial weight has been lost by dissolution in the decanted solvent.

Fumed and/or precipitated silica will be an effective matrix material in almost all cases, the amount of solvent that is able to be retained being dependent on the particle size of the matrix material. Equally, clays will be effective in many cases although their larger particle size means that they will retain less solvent than the fumed and precipitated silicates.

To test the selected gel composition, the composition should be applied in controlled conditions to a sample of the material intended to be removed to confirm effectiveness and ascertain optimum conditions and times for effective removal.

For example, a known amount of gel, say 5g, may be applied to a known amount of material intended to be removed, say 2g, and the effect of the gel on the material is observed regularly, say every 15 minutes for soft materials and eveiy hour for harder materials. For increased accuracy, a number of identical samples could be prepared corresponding to the number of proposed observations, these could be observed consecutively at the desired time intervals. This procedure avoids any inaccuracies which might arise from repeated mechanical inspection of a single sample.

It is also advisable to carry out the same procedure for the effects of the chosen gel on an example of the material of the surface on which the material to be removed is located, to check for possible adverse reactions between the surface and the gel. It should be noted that the discussion herein of the present invention assumes, unless stated otherwise, that removal of the long-chain material is to take place at ambient temperature. The solvent selection and methodology of the present invention will vary according to the actual value of "ambient temperature" in the relevant circumstances, due to the solvent evaporation rates, and the dissolution rates at that particular temperature.

The compositions of the present invention may contain several other components, according to the circumstances in which the composition is to be used. For example, non-ionic surfactants may be included within the composition of the present invention. These materials may be used to either modify or improve the function of the particular composition, or to control the release or the effect of the solvents and/or their effects on the material to be dissolved. Such additional components may include water, modifiers, surfactants, adjuvants, preservatives, accelerators or catalysts. For example, the composition may include a surfactant, preferably non-ionic, which would allow the solvent gels and solids to be easily dispersed using water and thus wash the composition of the present invention away with ease, dissolution of the material having taken place. Such surfactants may also enable the material being dissolved to be more easily washed away if it has been partially dissolved and softened, through emulsification of the material, solvent and gel within the water applied. In such circumstances, however, the surfactant need not be part of the composition of the present invention but may be applied subsequently.

Acids or alkalis may also be included within the compositions of the present invention. Whilst these do not generally take part in the dissolving process, they may hydrolyse material remaining or which has been dissolved in the gel, to assist with subsequent dispersement using water. The acids or alkalis would dissolve in the water and hydrolyse the material. An example of this is the addition of sodium hydroxide to a gel used to remove chewing gum. Once the gum base of the chewing gum has been removed and dispersed with water, the alkali will hydrolyse and break down the polymer units in the gum which may, in turn, be degraded more easily by organisms such as bacteria. Furthermore, such added material may act as an accelerant in the dissolving procedure. For example, 5% by weight of sodium hydroxide added to a gel made of 90% by weight d-limonene and 10% fumed silica accelerates the dissolved dissolution of chewing gum base.

Another type of material which may be added to the composition of the present invention is one which helps feed and stimulate natural organisms to degrade and break down the solvents and material, once they have been dispersed with water. A prefeπed material for this use is powdered seaweed.

Addition of a relatively hard inert particulate material such as sand to the composition will also assist in removal of particularly adhesive materials. Such abrasive materials assist in the removal of a material that has been softened, as opposed to fully dissolved, when the gel and solute are removed, preferably by mechanical agitation.

The general protocol for removing materials, using the composition of the present invention, is to apply the composition directly to the material and to leave the composition on the material for sufficient time to dissolve or soften the material. The composition on the material may then be washed off and any remaining softened material may be removed using mechanical agitation. For the removal of chewing gum, natural teipenes, particularly d- limonene, are the best solvents, particularly in combination with fumed silica. The preferred composition is a gel consisting of 95% by weight d-limonene in 5% by weight of fumed silica. Although halogenated hydrocarbons such as tri- chloroethylene, per-chloroethylene, tri-chloroethane and di-chloromethane are more rapidly acting solvents, as indicated earlier, they are health and environmental hazards and are, therefore, not particularly preferred.

When the particularly preferred gel of the present invention for use with chewing gum is applied to chewing gum, the chewing gum will start to soften and dissolve upon contact with the d-limonene. The dissolved material will diffuse into the solvent within the matiix and therefore is physically separated from the remaining chewing gum. In this way, should the gel be allowed to dry out through complete evaporation of the solvent, the material will not return to its original state because the dissolved material will have diffused into the gel itself. In the case of chewing gum, this means that a brittle solid remains after dissolution of the solvent, which solid is easily break up and removed by mechanical agitation. As indicated before, the addition of an abrasive such as sand within the composition of the present invention assists further with the process of breaking-up the partially dissolved material.

The time for which the composition should be left on the material to be dissolved depends entirely on the material itself. For example, fresh chewing gum will soften within a matter of minutes from application of the preferred d- limonene/fumed silica composition. However, aged gum deposits are likely to require more than an hour in contact with the present invention to be properly broken down. After the majority of the softened and dissolved gum is removed using a wire brush or a blade, any remaining residue may be removed using a detergent and water.

Because of the strength of many of the solvents which may diffuse from the gels of the present invention, it is often recommended that the area around the material to be dissolved be dampened with water so as to prevent the diffusion of the solvent into the area around the material to be dissolved and thus damage the area around the material to be dissolved.

EXAMPLE 1

A piece of used chewing gum, less than two months old, was located on a smooth concrete surface. To the chewing gum was applied 5g of a gel, consisting of 95% by weight d-limonene made solely from oranges, and 5% of fumed silica (CAB-0-SIL, T M, Cabot Industries, grade M5). The used gum had a surface area of approximately 5 square centimetres.

After one hour the gel and dissolved gum was removed by scraping with a stiff wire brush. Subsequently, the residue of the dissolved/softened chewing gum was washed away using general purpose detergent. The chewing gum was completely removed from the concrete surface.

The same protocol was used for gum which was considerable older than two months' old. It was discovered that if the composition was left on the gum for between 3 to 12 hours, complete removal of the gum was achieved.

Claims

1. A composition for removing a material comprising a long chain compound, substantially insoluble in water, from a surface, which composition comprises a non-aqueous liquid solvent in which a given long chain compound, substantially insoluble in water, is soluble, which solvent is entrained within a gel comprising a molecular matiix which does not substantially prevent diffusion of liquid therethrough and which is substantially inert to the non- aqueous liquid solvent.

2. A composition according to Claim 1 in which the gel does not react with the given long chain compound.

3. A composition according to Claim 1 or 2 wherein the matrix is formed from a silica or a clay.

4. A composition according to Claim 3 wherein the matrix is formed from fumed silica, precipitated silica or a silicate clay.

5. A composition according to any one of the preceding claims, wherein the gel serves to control the rate of diffusion of the non-aqueous solvent therefrom.

6. A composition according to any one of the preceding claims wherein the solvent is a saturated or unsaturated hydrocarbon, alcohol, glycol, aldehyde, ketone, ether, terpene, phthalate, ester or halogenated hydrocarbon, or a mixture thereof.

7. A composition according to Claim 6 wherein the solvent comprises hexane, toluene, di-pentenes, orange-terpenes, ethanol, N-propanol, N-butanol, ethoxy-propanol, di-propyl glycol mono-methyl ether, tetrahydrofuran, iso- propyl acetate, methoxy propyl acetate, methyl iso-pentyl ketone, methyl ethyl ketone, per-chloroethylene, citral, Poituguese gum terpentine (an alpha pinene and beta pinene mixture), terpen-4-ol, heptane, xylene, d-limonene, 1-limonene, methanol, iso-propanol, iso-butanol, N-pentanol, mono-propylene glycol, butyl di-glycol ether, iso-butyl acetate, ethyl acetate, acetone, cyclohexanone, di- chloromethane, tri-chloroethylene, Achilles pine oil, tri-chloroethylene, per- chloroethylene, tri-chloroethane or di-chloromethane.

8. A composition according to any one of the preceding claims wherein the non-aqueous solvent is a blend of solvents.

9. A composition according to Claim 8 wherein the non-aqueous solvent comprises a blend of 25% by weight d-limonene, 73% by weight ethanol and 2% by weight methanol or 50% by weight di-pentene and 50% by weight isopropanol, or 10 parts by weight d-limonene, 80 parts by weight ethanol and 3 parts by weight methanol.

10. A composition according to any one of the preceding claims wherein the solvent to gel ratio is 8:2 by weight.

11. A composition according to Claim 10 wherein the solvent to gel ratio is 9: 1 by weight.

12. A composition according to Claim 11 wherein the solvent to gel ratio is 9.5:0.5 by weight.

13. A composition according to any one of the preceding claims wherein the gel is formed by mixing said solvent with an inert canier comprising said matrix.

14. A composition according to any one of the preceding claims comprising 94.5% by weight d-limonene in 5.5% by weight fumed silica, 95% by weight di-pentene in 5% by weight fumed silica, 80% by weight d-limonene in 20% by weight bentonite, 94% by weight xylene in 6% by weight precipitated silica, 95% by weight d-limonene in 5% by weight fumed silica, 95% by weight di- pentene in 5% by weight fumed silica, 95% by weight orange and/or lemon terpenes in 5% by weight fumed silica, or 95% by weight plant terpenes in 5% by weight fumed silica

15. A composition according to any one of the preceding claims further comprising at least one of water, a modifier, a surfactant, an adjuvant, a preservative, an accelerator, an abrasive and a catalyst.

16. A composition according to Claim 15 wherein the composition further comprises an abrasive.

17. A composition according to Claim 16 wherein the abrasive is sand.

18. A composition according to any one of Claims 15 to 17 wherein the composition further comprises a surfactant.

19. A composition according to any one of Claims 15 to 18 wherein the composition further comprises an accelerator.

20. A composition according to Claim 19 wherein the accelerator is an acid or an alkali.

21. Use of a composition according to any one of Claims 1 to 20 for the removal of a material comprising a long chain compound, substantially insoluble in water, from a surface.

22. A method of removing a material comprising a long chain compound, substantially insoluble in water, from a surface, which method comprises applying a composition according to any one of Claims 1 to 20 to said material on said surface, leaving the composition and the material in contact for sufficient time to at least partially dissolve said material, and removing the gel and material from a surface.

23. A method according to Claim 22 wherein the removal of the gel material from the surface is effected by mechanical agitation.

24. A method according to Claim 22 or 23, wherein the removal of the gel and material is effected using water.

25. A composition for removing a material comprising a long chain compound, substantially insoluble in water, from a surface, substantially as hereinbefore described.

26. A method of removing a material comprising a long chain compound, substantially insoluble in water, from a surface, substantially as hereinbefore described.

27. Any novel feature or combination of features disclosed herein.