AN ALKYLENE OXIDE ADDUCT OF AN ALCOHOL

Field of the Invention

The present invention relates to the use of an ethoxylated alcohol as a hydrotrope for an alkylene oxide adduct of an alcohol in aqueous solutions. It also relates to a composition comprising said ethoxylated alcohol and said alkylene oxide adduct, and the use of this composition for the cleaning of hard surfaces.

Background of the Invention

The ability of an aqueous solution to spread evenly over a surface, the so-called wetting ability, is important for many applications. For example, a composition for the cleaning of hard surfaces benefits from a good wetting of the surface.

Nonionic surfactants that are alkylene oxide adducts of alcohols, also referred to as alcohol alkoxylates, are known to be good wetting agents, and are often present in compositions for the cleaning of hard surfaces. Depending on the specific application the compositions may further contain alkaline or acidic components, such as alkaline or acidic chelating agents, or neutral salts. However, especially when a high amount of electrolytes is present, many alcohol alkoxylates with good wetting properties are not soluble enough in aqueous solutions, and therefore need the presence of a hydrotrope to improve their solubility. A hydrotrope is defined as a compound that solubilizes hydrophobic compounds in aqueous solutions, in particular a compound that improves the solubility of surfactants in water. Hydrotropes are sometimes also called e.g. solubilizers, couplers, compatibility agents or co-surfactants. A good hydrotrope is not necessarily a good wetting agent. Its main task is to enhance the solubility of the surfactant, and thereby increase the wetting ability of the composition. For alcohol alkoxylates this will be manifested in an increased cloud point of the composition as compared to a composition without the hydrotrope. A number of hydrotropes for alcohol alkoxylates have been described in various publications. Examples of such hydrotropes are ethanol, sodium xylene sulphonate, sodium cumene sulphonate, alkyl glycosides, alkoxylated quaternary ammonium compounds, and phosphated alkoxylated alcohols.

US 2012/0102668 A1 relates to a thickened liquid hard surface cleaning composition comprising an alkoxylated non-ionic surfactant, a sulphated or sulphonated anionic surfactant and a neutralizing co-surfactant, such as an amine oxide surfactant and a betaine surfactant.

EP 0 616 027 relates to concentrated cleaning compositions, primarily for hard surfaces, comprising from 10 to 80% by weight of the total composition of water and at least one short chain surfactant comprising a C ₆ - C ₀ alkyl chain as its hydrophobic portion, such as a non-ionic surfactant and/or an alkyl sulphonate.

GB 2 204 321 A relates to a biodegradable liquid detergent composition containing a fatty alcohol polyethylene glycol ether, an alkanolamine, a sequestering agent and a fatty alcohol polyethylene/polypropylene glycol ether.

JP 2010-143971 relates to a detergent composition and method for cleaning a liquid crystal panel, which composition includes organic alkali, e.g. an alkanolamine; a hydrocarbon, and a surfactant selected from a group consisting of a polyoxyalkylene alkyl ether and a sulfosuccinic acid-type anionic surfactant.

JP 2009-084621 relates to metal detergent composition comprising two specific types of non-ionic surfactants

WO 2007/064673 and US 8, 1 19,585 B2 relate to a high actives liquid non-ionic surfactant concentrate that includes a fatty alcohol alkoxylate having an alkylene oxide content of about 10-100 moles and at least one other non-ionic surfactant alkoxylate having an alkylene oxide content of about 4-12 moles. The liquid surfactant concentrate may be utilized in e.g. emulsion polymerization or in the formulation of agrochemical compositions, and also as emulsifier for solvents in cleaning compositions.

US 6,342,474 B1 relates to an aqueous hard surface cleaning composition comprising a water soluble organic solvent, a non-ionic surfactant selected from the group consisting of an alcohol alkoxylate, an alcohol block alkoxylate, a polyoxyethylene polyoxypropylene block surfactant, and mixtures thereof, a cleaning auxiliary and optionally a thickening agent. EP 0 681 865 A2 relates to a low-foaming wetting agent useful for e.g. textile processes and plant protection formulations, which comprises a combination of several types of alkyl ethoxylates, alkyl ethoxylates/propoxylates and alkyl propoxylates.

WO 2007/096292 relates to a surfactant mixture containing an alkoxylation product of alkanols having 8 to 12 carbon atoms and 3 to 30 alkoxy groups per alkanol group, where the alkanols have a mean degree of branching of at least 1 , and an alkoxylation product of alkanols having 13 to 20 carbon atoms and 3 to 30 alkoxy groups per alkanol group, where the alkanols have a mean degree of branching of 0.0 to 0.3. These surfactant mixtures may be used in formulations for e.g. hard surface cleaning.

WO 03/091 190 relates to an alkoxylate mixture of at least one alkoxylate having a hydrocarbyl group with 8 to 1 1 carbon atoms, alkoxylated with 1 to 20 ethyleneoxy groups and 0 to 10 C ₃ -C ₁₀ alkyleneoxy groups, and at least one alkoxylate having a hydrocarbyl group with 12 to 24 carbon atoms, alkoxylated with 1 to 50 ethyleneoxy groups and 0 to 10 C ₃ -C ₀ alkyleneoxy groups. The alkoxylate mixture is claimed to be useful for detergents for the cleaning of textiles.

However, there is still a need for new efficient products that act as effective hydrotropes, and are compatible for the achievement of stable compositions delivering optimal performance, especially such that have an excellent environmental profile with a good biodegradability and a low toxicity.

Summary of the Invention

It is an object of the present invention to at least partially meet the above-mentioned need in the art and to provide an improved hydrotrope for alkylene oxide ad ducts of alcohols in aqueous solutions. It is also an object of the invention to provide a stable cleaning composition having improved activity. These and other objects are achieved by the ethoxylated alcohol hydrotropes/compositions of the present invention.

Detailed Description of the Invention

In one aspect the invention relates to the use of an ethoxylated alcohol as a hydrotrope for an alkylene oxide adduct of an alcohol in aqueous solutions. In a further aspect the invention relates to an aqueous composition comprising the ethoxylated alcohol and an alkylene oxide adduct of an alcohol.

In yet one more aspect the invention relates to the use of the composition in a method for the cleaning of hard surfaces.

For clarity reasons, throughout this document, the hydrotrope will be referred to as the "ethoxylated alcohol" and the non-ionic compound that is solubilised by the hydrotrope will be referred to as the "alkylene oxide adduct of an alcohol".

The ethoxylated alcohol, i.e. the hydrotrope, has the formula RO(EO) _b Y (I), wherein R is a hydrocarbyl group having 8-12, preferably 8-1 1 , and most preferably 8-10, carbon atoms, EO is an ethyleneoxy unit, b is at least 10, preferably at least 11 , more preferably at least 12, even more preferably at least 13, still more preferably at least 14, still more preferably at least 15, and most preferably at least 16, and at most 35, preferably at most 34, more preferably at most 33, even more preferably at most 32, still more preferably at most 31 , still more preferably at most 30, and most preferably at most 25; and Y is H, -R ¹ or -C(0)R ¹ where R ¹ is a C1 -C4 alkyl group. Preferably Y is H.

The hydrocarbyl group of the ethoxylated alcohols may be linear or branched, saturated or unsaturated. Suitable examples of the ethoxylated alcohols are n- octanol ethoxylated with from 10 to 35 moles of EO (ethylene oxide) per mole of n- octanol, 2-ethylhexanol ethoxylated with from 10 to 35 moles of EO per mole of 2- ethylhexanol, n-decanol ethoxylated with from 10 to 35 moles of EO per mole of n- decanol, 2-propylheptanol ethoxylated with from 10 to 35 moles of EO per mole 2- propylheptanol, and n-dodecanol ethoxylated with from 10 to 35 moles of EO per mole of n-dodecanol.

The products based on the ethoxylated alcohols are in general easy to work with when making solutions in water. However, for the ethoxylated dodecanol products there is a problem with gelation when concentrated solutions are made. Thus, due to easier handling, the products (I) having a C ₈ to Cn hydrocarbyl group are more preferred than the compounds having a C ₂ hydrocarbyl group.

The alkylene oxide adduct of an alcohol preferably has an HLB value according to Davies (Tenside Surfactants Detergents 29 (1992) p. 2) of at most 8.0, preferably at most 7.5. The formula for the alkylene oxide adduct of an alcohol is

R ² 0 - (AO) _x (EO) _y (AO) _z Y (II)

wherein R ² is a C ₈ to C _12, preferably C ₈ to Cn, hydrocarbyl group, AO is a C3-C10 alkyleneoxy unit, preferably a propyleneoxy unit, EO is an ethyleneoxy unit, x = 0-4, preferably 0-2, and most preferably 0; y is at least 1 , preferably at least 2, more preferably at least 3, and most preferably at least 4, and is at most 9, preferably at most 8, more preferably at most 7, and most preferably at most 6; z = 0—4, preferably 0-2, and most preferably 0; and Y is H, -R ¹ or -C(0)R ¹ , where R ¹ is a C1 -C4 alkyl group. Y is preferably H. Thus, in addition to the 1-9 ethyleneoxy units, the C ₈ -C ₁₂ -alcohol alkoxylates may also contain e.g. up to 4 propyleneoxy (PO) units. The number of propyleneoxy units, when present, may be as small as 0.1 mole PO per mole alcohol. The ethyleneoxy units and the alkyleneoxy units may be added randomly or in blocks. The blocks may be added to the alcohol in any order. The alcohol ethoxylates may be end-capped with the group Y (when Y is not H), but products that are not end-capped (Y is H) are preferred. The hydrocarbyl group of the alcohol alkoxylates may be linear or branched, saturated or unsaturated.

However, no alkylene oxide ad ducts containing only propyleneoxy units are contemplated for use in the compositions of the present invention.

The ethoxylated alcohol (I) and the alkylene oxide adducts of an alcohol (II) may be produced by procedures well-known in the art using e.g. a conventional basic catalyst, such as KOH, or a so-called narrow range catalyst (see e.g. Nonionic Surfactants: Organic Chemistry in Surfactant Science Series volume 72, 1998, pp 1 - 37 and 87-107, edited by Nico M. van Os; Marcel Dekker, Inc). For the ethoxylated alcohol (I) the procedure using a conventional basic catalyst would be most suitable.

Suitable alkylene oxide adducts of an alcohol having a linear hydrocarbyl group include C ₉ -Cn alcohol + 4, 5, 6, 7 or 8 EO, and Cn alcohol + 3, 4, 5, 6, 7 or 8 EO. Suitable alkylene oxide adducts of an alcohol having a branched hydrocarbyl group include 2-ethylhexanol + 3, 4 or 5 EO, 2-ethylhexanol + 2 PO + 4, 5 or 6 EO, 2- propylheptanol + 3, 4, 5 or 6 EO and 2-propylheptanol + 1 PO + 4 EO. Another example is 2-butyloctanol + 5, 6 or 7 EO. Wherever the degree of alkoxylation is discussed, the numbers referred to are molar average numbers, essentially corresponding to the reaction of the indicated number of moles of alkylene oxide with one (1 ) mole of alcohol.

The composition normally will contain a salt of some kind, such as alkaline or acidic chelating agents, also called complexing agents or sequestering agents, or neutral salts. Suitable examples of chelating agents are alkali salts of phosphates, such as sodium pyrophosphate or sodium tripolyphosphate and the corresponding potassium salts; organic phosphates; aminocarboxylates, such as sodium nitrilotriacetate (Na ₃ NTA), disodium 2-hydroxyethyliminodi(acetate), sodium ethylenediamine tetraacetate (EDTA), sodium diethylenetriamine pentaacetate (DTPA), sodium 1 ,3- propylenediamine tetraacetate, sodium hydroxyethylethylenediamine triacetate (HEDTA), sodium ethylenediaminedisuccinate (EEDS), tetrasodium N,N- bis(carboxymethyl)-L-glutamate (= glutamic acid-N,N-diacetic acid tetrasodium salt (GLDA)), methylglycine diacetic acid (MGDA), tetrasodium iminodisuccinate (IDS), and methyliminodiacetic acid; aminopolyphosphonates, such as nitrilotris(methylene phosphonic acid) (ATMP) and its salts, diethylenetriamine penta(methylene phosphonic acid) (DTPMP) and its salts; polyphosphonic acids, such as 1 - hydroxyethylidene-1 , 1 -diphosphonic acid (HEDP); polycarboxylates, such as citrates and citric acid; 2-phosphonobutane-1 ,2,4-tricarboxylic acid (PBTC) and its salts; alkali salts of gluconic acid, such as sodium or potassium gluconates; and alkali salts of glucoheptonic acid, such as sodium or potassium glucoheptonates. Examples of neutral salts are NaCI, KCI and Na ₂ S0 ₄ .

The amounts of the components in the aqueous composition are suitably:

i) at least 0.02, preferably at least 0.1 , and most preferably at least 0.5% by weight, and at most 60, preferably at most 50, more preferably at most 40, even more preferably at most 30, still more preferably at most 20, still more preferably at most 15, and most preferably at most 10% by weight, of the ethoxylated alcohol

(i);

ii) at least 0.05, preferably at least 0.5, and most preferably at least 1 % by weight, and at most 60, preferably at most 50, more preferably at most 40, even more preferably at most 30, still more preferably at most 20, still more preferably at most 15, and most preferably at most 10% by weight, of the alkylene oxide adduct of an alcohol (II); and Hi) 0, preferably at least 0.05, most preferably at least 0.1 % by weight, and at most 20 preferably at most 15, and most preferably at most 10% by weight, of a chelating agent or other salt.

The aqueous compositions may either be concentrates that could be used as such, or that should be diluted before use.

The ethoxylated alcohol (I) and the alkylene oxide adduct of an alcohol (II) could be premixed in a highly concentrated composition comprising water as a solvent. A premix concentrate suitably contains 30-60% by weight of ethoxylated alcohol (I), 30- 60% by weight of alkylene oxide adduct of an alcohol (II), and normally at least 10% water. This composition is suitable for bulk transportation, since the amount of water is rather low.

To produce a less concentrated aqueous composition, additional water is mixed with the premix. If a chelating agent or any other salt should be present in the composition, it may suitably be added to the water before the premix and water are mixed, but it could equally well be added afterwards. The less concentrated aqueous composition could also be produced by adding the desired amounts of the components separately, in any order.

In a typical consumer concentrate, to be diluted before use, the amounts of the components are suitably

i) at least 0.5%, preferably at least 1 %, more preferably at least 2%, and most preferably at least 3% by weight, and at most 10%, preferably at most 9%, more preferably at most 8% and most preferably at most 7% by weight of the ethoxylated alcohol (I);

ii) at least 1 %, preferably at least 2%, more preferably at least 3% and most preferably at least 4% by weight, and at most 10%, preferably at most 8%, more preferably at most 7%, still more preferably at most 6% and most preferably at most 5% by weight of the alkylene oxide adduct of an alcohol (II); and

iii) 0%, preferably at least 0.1 , more preferably at least 0.5, even more preferably at least 1 , still more preferably at least 2, still more preferably at least 3, still more preferably at least 4, and most preferably at least 5% by weight, and at most 10% by weight of a chelating agent Concentrates having higher amounts of the components are also possible to produce if needed.

If the above concentrates are diluted before use, a typical dilution would be from 1 :5 to 1 :30 with water, but depending on the initial concentration of the composition, dilutions of up to 1 :50 or even up to 1 :200 with water may also be made.

In a typical diluted composition comprising a chelating agent the amounts of the components are suitably 0.1 -1 % by weight of i), 0.1 -1 % by weight of ii) and 0.05-1 % by weight of iii).

The compositions of the present invention are suitably clear and homogeneous, preferably up to a temperature of at least 40°C, i.e. the cloud point of compositions comprising the alkylene oxide adduct of an alcohol should suitably be at least 40°C. The cloud point may be adapted by changing the weight ratio of ethoxylated alcohol (I) to alkylene oxide adduct of an alcohol (II). This ratio is within the range 1 :20 to 2:1 , typically 1 :5 to 1.5:1. The weight ratio between the ethoxylated alcohol (I) and the chelating agent/other salt suitably is within the range 1 :50 to 20: 1 , typically 1 :10 to 10:1 . The weight ratio between alkylene oxide adduct of an alcohol (II) and the chelating agent is normally within the range 1 : 10 to 10:1 , typically 1 :5 to 5: 1 . The consumer concentrates normally contains at least 50% by weight of water, suitably at least 70% by weight, and normally at most 95% by weight of water, suitably at most 90% by weight.

Aqueous cleaning compositions in accordance with the invention may further contain other hydrotropes and other surfactants, such as anionic surfactants, cationic surfactants, amphoteric surfactants and/or amine oxides: and conventional additives, such as (but not limited to) alkali, such as sodium hydroxide or potassium hydroxide, silicates, acids, solvents, other salts, perfumes, pH buffers, abrasives, soil antiredeposition agents, preservatives, opacifiers, disinfectants, deodorants, colorants, corrosion inhibitors, foam regulators and rheology modifiers, such as polymers; in the usual amounts. However, to obtain a composition having an optimal performance and an excellent environmental profile, the presence of certain components is less desirable. If hydrocarbon solvents are present, the weight ratio between the solvent and the sum of (I) and (II) is lower than 1 : 10, preferably lower than 1 :20. Most preferably the compositions are substantially or totally free from hydrocarbon solvents. If anionic surfactants are present, the weight ratio between the anionic surfactant and the alkylene oxide adduct of an alcohol (II) is less than 1 :4, more preferably less than 1 : 10, and even more preferably less than 1 :20. Most preferably the compositions are substantially or totally free from anionic surfactants.

If amine oxides are present, the weight ratio between the amine oxide and the alkylene oxide adduct of an alcohol (II) is less than 1 :4, preferably less than 1 : 10, and more preferably less than 1 :20. Most preferably the compositions are substantially or totally free from amine oxides.

In the context of the present invention, the term "substantially free from", e.g. as in substantially free from a compound, e.g hydrocarbon solvents, anionic surfactants and/or amine oxides, shall be interpreted as that no such compound has been added purposively to the composition. However, trace amounts of such compound, such as coming from impurities etc, may be present in the compostion.

The compositions may be acidic, neutral or alkaline. Alkaline compositions typically comprise alkaline chelating agents. Alkanolamines, such as monoethanolamine MELA, diethanolamine (DEA) and triethanolamine (TEA), which are sometimes used as a source of alkalinity, are however not contemplated for use as components in the present compositions, and the compositions are thus substantially free from alkanolamines.

In neutral and acidic compositions chelating agents may also be added, such as citric acid.

The cleaning compositions of the invention are suitably alkaline. There are several advantages connected with the use of the ethoxylated alcohols as hydrotropes for alkylene oxide adducts of alcohols. Firstly, they are excellent hydrotropes that also contribute to the cleaning performance of the compositions. The compositions of the present invention were found to be at least as efficient as comparative compositions containing sodium xylene sulfonate as hydrotrope instead of the ethoxylated alcohol. The cleaning efficiency of the compositions is very good even at high dilutions of the compositions. Further, their biodegradability is good and the toxicity low.

The compositions are excellent for use in cleaning hard surfaces, such as for vehicle cleaning and household cleaning. Thus another aspect of the invention is a method for the cleaning of hard surfaces, which comprises the steps of adding to said surfaces a cleaning effective amount of a composition as described above, and thereafter rinsing and/or wiping the said surfaces.

One further aspect of the invention is a general method for raising the cloud point of a composition comprising an alkylene oxide adduct of an alcohol, by adding an effective amount of an ethoxylated alcohol as defined above.

The cloud point of a fluid is the temperature at which dissolved solids are no longer completely soluble, precipitating as a second phase giving the fluid a cloudy appearance.

The present invention is further illustrated by the following examples.

Examples

General

The materials are abbreviated in the following manner:

^* Cg-Cn-alcohol + 5.5EO (NR): synthetic primary alcohol with >80 % linearity, narrow range (NR) ethoxylated with 5.5 moles of ethyleneoxide (EO) per mole alcohol.

^* Cg-C -alcohol + 4EO (NR): synthetic primary alcohol with >80 % linearity, narrow range (NR) ethoxylated with 4 moles of ethyleneoxide (EO) per mole alcohol. All narrow range ethoxylated alcohols are abbreviated in the same manner.

* 2-EH = 2-ethylhexanol; 2-PH = 2-propylheptanol; C8 = n-octanol; C10 = n- decanol; C12 = n-dodecanol.

Example 1

In this and all following examples all percentages and ratios are by weight, unless otherwise specified, and all amounts given refer to the active content of the components.

Aqueous formulations with the ethoxylated alcohol hydrotropes specified in Table 1 were made. All compositions contain 5% of a 1 : 1 mixture of a C ₉ -C ₁ alcohol + 5.5EO (NR) and a C ₉ -C ₁ alcohol + 4EO (NR); and 10% (4.7% a.s.) of Dissolvine GL-47S (Active ingredient is L-glutamic acid-N,N-diacetic acid tetrasodium salt; GLDA) (ex AkzoNobel). The amount of hydrotrope in Table 1 was the amount needed to obtain a solution having the cloud point indicated in the Table. The cloud points in the Table are given as °C.

Table 1

Example 2

In this example it was investigated how much of the respective hydrotrope that was needed to obtain a solution having a cloud point of at least 40°C, but not exceeding 42°C, for aqueous solutions containing 5 wt% of a C ₉ -Cn- alcohol + 4EO (NR) and 10% (3.9% a.s.) Dissolvine E-39 (tetrasodium salt of ethylenediamine tetraacetic acid). The amounts of the hydrotropes are based on the total amount of all components in the respective composition.

To be able to obtain compositions only differing in the amount of hydrotrope needed for achieving the desired cloud point, the following method was used.

Method

The final solutions should all weigh 100g. In this solution there should be included X g of alcohol alkoxylate and Y gram of chelating agent.

Step 1. Y gram of chelating agent is dissolved in 75 g of water.

Step 2. X gram of alcohol alkoxylate is added to this solution.

Step 3. The mixture obtained in step 2 is heated to the desired cloud point.

Step 4. Hydrotrope is added dropwise at this temperature until a clear solution is obtained.

Step 5. Water is added in such an amount that the whole mixture weighs 99 g. Step 6. The cloud point is measured.

a) If the cloud point has not changed from the desired value in step 3, 1 g water is added, and the composition is ready.

b) If the cloud point has decreased, a few more drops of hydrotrope are added and the cloud point is measured again, some more water is added, and the measurement is repeated. This procedure is repeated until the total formulation weighs 100 g and the desired cloud point has been reached. A deviation of up to about 2°C above the desired cloud point is accepted. Table 2

Example 3

The formulations in Table 3 were tested by the method described below and the results are displayed in Table 4.

The screening test method for kitchen cleaning

Glossy tiles (25x40 cm) were soiled by a mixture consisting of

20% Lambert soil 50% corn oil

30% water

Composition of "Lambert" synthetic Urban soil

Hyperhumus 38.0 %

Portland Cement 15.0 %

Low Color Furnace Carbon Black 1 .5 %

Synthetic Red Oxide 0.3 %

Powdered Silica 15.0 %

Black Charm Clay 16.7 %

Stearic Acid 1.5 %

Oleic Acid 1 .5 %

Palm Oil 3.0 %

Cholesterol 1 .0 %

Vegetable Oil 1.0 %

Light Mineral Oil 1.0 %

Squalene 1.0 %

Linoleic Acid, Technical Grade 2.0 %

White Mineral Oil 1 .5 %

• The soil solution was stirred until it was applied to the tiles. • Approximately 2-3 ml soil was applied on each tile.

• A piece of paper was used to distribute the soil as homogeneously as possible on the surface.

• The soiled tiles may be kept up to 5 days at room temperature before use.

After 1 week the soil will dry and it will not be possible to get rid of it without mechanical treatment.

• 20 ml of the respective formulations 3 and 4 in Table 3 were poured onto the top of the soiled tiles and left there for 15 seconds.

• The plates were then rinsed with cold water from the tap during 15 seconds. The rinse was started from the top of the tile.

• The cleaning performance of the formulations 1 and 2 was measured with a Minolta Chroma Meter CR-200 reflectometer, and the results are presented in Table 4 as the % soil removal. The values are the average results of tests performed on three plates. The accuracy is about ± 5%.

Table 3

Table 4

Example 4

To evaluate the cleaning efficiency of the formulations in Table 5 the following cleaning test was used: White-painted plates were smeared with an oil-soot mixture obtained from train diesel engines. 25 ml of the test solutions, in this case formulations 5, 6 and 7 in Table 5 diluted to 1 :20, were poured onto the top of the oil-smeared plates and left there for one minute. The plates were then rinsed off with a rich flow of water. All solutions and the water were kept at a temperature of about 15 - 20°C. All comparison solutions were placed on the same plates as the test solutions. The cleaning ability was measured with a Minolta Chroma Meter CR-200 reflectometer, and the result is presented as the % soil removal. The results are collected in Table 6.

Note that the values given are to be used only as relative, not absolute values. The values to be compared should be obtained from the same plates with the same batch of oil-soot mixture being used. Where nothing else is stated, the values are the average results of tests performed on at least three plates. The accuracy is about ± 5%.

Table 5

^* Active ingredient is L-glutamic acid-N,N-diacetic acid tetrasodium salt; GLDA Table 6

^" Based on the results of 3 tests on 3 plates

Formulation 6, containing an ethoxylated alcohol hydrotrope (I) according to the invention, an alkylene oxide adduct of an alcohol (II), and a chelating agent, was much more effective in cleaning the plates at the dilution 1 :20 than the diluted comparison formulation 4, which contained only the hydrotrope, and the diluted formulation 5, which contained the hydrotrope and the chelating agent.

Thus, it is shown here that the hydrotrope in itself has a minor cleaning effect.