DE69706314T2 - CLEANING AGENT WITH CATIONIC MONOALKYTE SIDES - Google Patents

Description

Technical area

The present invention relates to an alkaline cleaning composition for hard surfaces, the composition comprising both a cationic fatty alkyl surfactant and a nonionic surfactant.

Background of the invention

In traditional cleaning of hard surfaces, e.g. wood, glazed tiles, painted metal and the like, it is known to remove dirt using surfactant- or solvent-based compositions, with a separate step of applying a varnish, wax or polish to seal and protect the surface and reduce the rate of dirt redeposition. This two-step cleaning and sealing job is time-consuming and complicated.

It has been proposed to incorporate a variety of soil releasing agents, including polymers, siloxanes and quaternary cationic dialkyl surfactants, into cleaning compositions to provide a secondary cleaning effect. These soil releasing agents are believed to act by depositing a layer of polymer, siloxane or surfactant on the surface during cleaning. This layer of material is believed to facilitate further cleaning operations by reducing the extent to which soil adheres to the surface.

It is preferred that these compositions be strongly alkaline to promote cleaning. Of these materials, the quaternary cationic surfactants are the lowest cost available. These quaternary salts generally comprise a quaternized nitrogen atom with one or two fatty alkyl side chains and three or two lower alkyl side chains. In the case of these compositions comprising quaternary cationic dialkyl surfactants, it has proven difficult to stabilize the products against flocculation or phase separation due to the interaction of the components present.

Accordingly, a technical problem exists with regard to a stable formulation of strongly alkaline cleaning compositions containing an effective proportion of a quaternary nitrogen-containing soil release agent.

Brief description of the invention

We have developed stable alkaline organic amine-containing compositions that both clean a surface and deposit thereon a layer of a cationic surfactant containing relatively long chain mono-fatty alkyl groups that promote the release of soil that is subsequently deposited on the surface. It is believed that the stability in such compositions is contributed by the combined use of the alkaline organic amine and the cationic mono-fatty alkyl surfactant.

Thus, the present invention provides an aqueous hard surface cleaning composition comprising a surfactant mixture, the surfactant mixture comprising:

a) at least 65% by weight, based on the total surfactant, nonionic surfactant,

b) less than 1% by weight, based on the total surfactant, anionic surfactant,

c) 0.1 to 35% by weight, based on the total surfactant, of cationic surfactant which is a quaternary mono-fatty alkyl ammonium compound, wherein the alkyl chains comprise at least 10% by weight of C₁₈-C₂₆ alkyl groups,

wherein the composition further contains at least 0.5 wt.% of an organic amine having a pKa of at least 8.0 .

It is believed that the cationic surfactants present in the compositions of the invention modify the surface energy of surfaces to which the composition is applied so as to increase the contact angle of soil subsequently deposited on the modified surface.

Detailed description of the invention

In order that the present invention may be better understood, it is described in more detail below with particular reference to preferred components and formulation details.

Cationic surfactants

A number of cationic quaternary mono-fatty alkyl ammonium compounds find useful application in the compositions of the present invention. Particularly suitable cationic surfactants have the general formula:

(R1 R2 R3 R4 N]+X

wherein R1, R2 and R3 are independently C1-C6 alkyl radicals, R4 is a fatty alkyl chain and X is a monovalent anion equivalent, the distribution of chain lengths in the material being such that in at least 10% by weight of the material the fatty alkyl chains comprise C18-C26 carbon atoms. It is preferred that less than 60% of the material contains monofatty alkyl quaternary ammonium compounds in which the fatty alkyl chain is C16 or shorter.

These longer chain mono-fatty alkyl quaternary materials are believed to perform better in terms of secondary cleaning benefits than shorter mono-fatty alkyl chain materials. It has also been found that the use of the mono-fatty alkyl chain materials allows more room for formulation than the use of the corresponding di-alkyl fatty chain materials. Halides, particularly chloride or bromide, are suitable counterions. The fatty alkyl chain may be derived from synthetic or natural starting materials. When the fatty alkyl chain is derived from natural materials, it will generally comprise a mixture of materials with a range of alkyl chain lengths in the fatty alkyl chain. Preferably, the fatty alkyl chains are fully saturated. Saturated alkyl chains are believed to exhibit effective properties due to the packing of the alkyl chains at the surfaces and interfaces.

Preferably, the cationic surfactant comprises a cation of the formula given above, where R1 = R2 = R3 = CH3. Materials of this general type in which the lower alkyl groups are methyl groups are commercially available.

A particularly preferred material is trimethylbehenylammonium bromide. This material has been found to flocculate over time in the presence of significant amounts of inorganic salts, including alkali salts such as sodium hydroxide and sodium or potassium carbonate. As described below, this difficulty is avoided in the compositions of the present invention.

Non-ionic surfactants

It is essential that the compositions of the present invention contain a nonionic surfactant. It is It is believed that the presence of the nonionic surfactant contributes significantly to the cleaning effectiveness of the compositions of the invention.

Suitable nonionic detergent compounds can be broadly described as compounds produced by condensation of alkylene oxide groups, which are hydrophilic, with an organic hydrophobic compound, which may be aliphatic or alkyl aromatic.

The length of the hydrophilic or polyoxyalkylene moiety condensed with any particular hydrophobic group can be readily adjusted to provide a water-soluble compound with the desired degree of balance between hydrophilic and hydrophobic elements.

Specific examples include the condensation product of aliphatic alcohols having 6 to 22 carbon atoms in straight chain or branched configuration with ethylene oxide, e.g. a coconut oil ethylene oxide condensate containing 2 to 15 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains 6 to 12 carbon atoms with 5 to 25 moles of ethylene oxide per mole of alkylphenol; condensates of the reaction product of ethylenediamine and propylene oxide with ethylene oxide, the condensates containing 40 to 80% polyoxyethylene radicals by weight and having a molecular weight of 5,000 to 11,000; tertiary amine oxides of the structure R₃NO, wherein one R group is an alkyl group having 8 to 18 carbon atoms and the others are each methyl, ethyl or hydroxyethyl groups, e.g. B. Dimethyldodecylamine oxide; tertiary phosphine oxides of the structure R₃PO, in which one group R is an alkyl group having 10 to 18 carbon atoms and the others are each alkyl or hydroxyalkyl groups having 1 to 3 carbon atoms, e.g. Dimethyldodecylphosphine oxide, and dialkyl sulfoxides of the structure R₂SO, in which one group R is an alkyl group having 10 to 18 carbon atoms and the other is a methyl or ethyl group, e.g. methyltetradecyl sulfoxide; fatty acid alkylolamides; alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans.

Particularly preferred nonionic surfactants are the ethoxylated alcohols having 6 to 14 carbon atoms and 2 to 9 moles of ethoxylation. Suitable materials include IMBENTIN 91/35 OFA (TM), a C9 to C11 nonionic surfactant with an average of 5 moles of ethoxylation, and NONIDET 91-6T (TM), a topped C9 to C11 nonionic surfactant with an average of 6 moles of ethoxylation.

Many other non-ionic surfactants are known to the person skilled in the art and are described in M. J. Schick "Nonionic Surfactants", Marcel Dekker (1967) and subsequent editions of the same work.

The amount of nonionic detergent active to be employed in the composition of the invention is generally between 1 and 30% by weight, preferably 2 to 20% by weight, and most preferably 5 to 10% by weight.

It is particularly preferred that the ratio of nonionic surfactant to anionic and cationic surfactant is such that > 75% of all surfactants present in the composition are nonionic.

It is essential that the compositions of the invention contain only low levels of anionic detergent actives or, as far as practical, that these actives are absent. It is believed that the presence of anionic detergents causes the formation of a complex between the cationic and anionic detergents, which reduces the effectiveness of the compositions.

The total surfactant content of the compositions according to the invention is generally between 1 and 30% by weight.

Organic amine

It is essential that the compositions of the invention contain at least 0.5% by weight of an organic amine having a pKa of at least 8.0. This component is believed to act as an ester-cleaving agent which promotes the cleaning of difficult-to-degrade soils, e.g. pyrolyzed soils produced when fatty and/or proteinaceous foods are surface-heated. If organic amines with a lower pKa, e.g. aniline, are used, they are not effective in aiding cleaning. If inorganic alkalis are present in significant proportions, the quaternary material described above flocculates and the phases of the composition separate.

It is preferred that the composition contains from 1 to 10% of an alkanolamine, with levels of from 2 to 6% by weight being particularly preferred. Particularly suitable alkanolamines include 2-amino-2-methyl-1-propanol, monoethanolamine and diethanolamine. 2-amino-2-methyl-1-propanol is the most preferred organic amine.

Preferably, the compositions according to the invention contain less than 1% of electrolytic salts, including sodium and/or potassium carbonates, bicarbonates and/or hydroxides.

Minor Components and Other Components A variety of minor components may be present in the compositions of the invention. The composition of the invention may contain other ingredients which enhance their cleaning performance and/or improve the physical properties of the composition. These components are not essential to the functioning of the invention.

Hydrophobic oils are optional components of compositions of the invention. Suitable oils include oils that rapidly dissolve triglyceride. When oils are present, preferred oils include limonene, paracymol, dibutyl ether and butyl butyrate.

Another optional ingredient for compositions of the invention is a foam controlling material which can be employed in those compositions of the invention which have a tendency to produce excessive foam in use. Examples of foam controlling materials are organic solvents, hydrophobic silica and silicone oils or hydrocarbons. Solvents are optional components of the compositions of the invention. When solvents are present, preferred solvents have the formula R1-O-(EO)m-(PO)n-R2, where R1 and R2 are independently C2-C6 alkyl radicals or H, but are not both hydrogen, m and n are independently 0 to 5. More preferably, the solvent is selected from the group comprising diethylene glycol mono-n-butyl ether, monoethylene glycol mono-n-butyl ether, propylene glycol n-butyl ether, isopropanol, ethanol, butanol, and mixtures thereof. Alternative solvents include the pyrolid(in)ones, e.g. N-methylpyrrolidinone.

It has been found that the inclusion of a long chain fatty alcohol, particularly C₁₆ or longer, more preferably C₁₆ to C₂₀, e.g. tallow alcohol, provides an improvement in cleaning performance. Typically these alcohols are in Amounts of 0.001 to 2% and preferably less than 1%.

Compositions according to the invention can also contain, in addition to the ingredients already mentioned, various other optional ingredients, for example pH regulating agents, dyes, optical brighteners, soil carriers, detergent enzymes, compatible bleaches, gel control agents, freeze-thaw stabilizers, bactericides, preservatives, detergent hydrotropes, perfumes and opacifiers.

It has been found suitable to deliver products according to the invention in the form of a relatively low dosage product in a relatively fine mist. This has the crucial advantage that only small amounts of product need to be applied. Preferred compositions according to the invention are packaged in a container designed to produce a spray of 0.1 to 1.5 ml of product per spraying operation, the spray having an average droplet size in the range of 30 to 300 µm.

It has been found to be particularly advantageous to add a polymer to the compositions of the invention to reduce the level of formation of exceptionally fine droplets when the composition is sprayed as a relatively fine mist. Suitable polymers include polyvinylpyrrolidone, which is commercially available as polymer PVP K-90.

Suitable proportions of PVP polymer are in a range of more than 50 ppm. Proportions of 300 to 2000 ppm are particularly preferred.

Particularly preferred compositions have a pH of > 10 and comprise, mixed with water:

a) 3 to 15% non-ionic surfactant (preferably C�9;-C₁₂ EO5-8 nonionic surfactant)

b) 2 to 10% solvent (preferably diethylene glycol mono-nbutyl ether)

c) 2 to 6% alkanolamine (preferably 2-amino-2-methyl-1- propanol)

d) 0 to 2000 ppm polymer (preferably PVP) and

e) 0.1 to 4% of a cationic surfactant of the general formula [R₁R₂R₃R₄N]⁺X⁻

wherein R₁, R₂ and R₃ are independently C₁-C₆ alkyl radicals, R₄ is a fatty alkyl chain having at least 10% C₁₉-C₂₅ carbon atoms and X is a monovalent anion equivalent.

In order to better understand the present invention, it is illustrated by non-limiting examples.

Examples

Aqueous compositions containing nonionic surfactant and a relatively low level of cationic surfactant were prepared as indicated in Table 1 below using the following materials (all compositions are in weight percent unless otherwise stated):

NONI: NONIDET 91-6T (TM: from Nippon Shell): a C9-C11 ethoxylated alcohol with 6 moles of ethoxylation and topped to reduce the amount of lower ethoxylates.

VBM: Behenyltrimethylammonium chloride (from Nippon Oils & Fats)

DIGOL: Butyl-Digol (TM): Diethylene glycol mono-n-butyl ether AMP: 2-amino-2-methyl-1-propanol

CTAB: Cetyltrimethylammonium bromide (from BDH) DEA: Diethanolamine

CARB: Potassium carbonate

POL: PVP K-90 (TM from International Specialty Polymers) 2HT: NISSAN CATION 2ABTN (TM from Nippon Oils & Fats): Dihydrogenated tallow dimethyl ammonium chloride Table 1

All samples contained 0.1% polyvinylpyrrolidone, commercially available as polymer PVP K-90 (TM) and 0.2% perfume. For Example 1, the required amounts of all ingredients were mixed at room temperature. For Examples 2 and 5, VBM was added to hot water at 80ºC and stirred using a Heidolph mixer at 80ºC for 2 hours to give a 15.5% by weight solution. The required amount of this solution (still at 80ºC) was then added at room temperature to the required amount of a solution containing all remaining ingredients and the solution was stirred for an additional 10 minutes. For Example 3, equal amounts of nonionic surfactant (NONI) and di-hardened tallow dimethyl ammonium chloride were melted together at 60ºC. The required amount of this co-melt was added (still at 60ºC) to the required amount of a room temperature solution containing all remaining ingredients and the solution was stirred for a further 30 minutes. For Example 4, the required Amounts of all ingredients were mixed at room temperature. The solution was then briefly heated to 60ºC to homogenize it.

To measure cleaning results, the following experiments were conducted. 100 g of 1.5 poise dehydrated castor oil (from SEATONS) was weighed into a glass jar. 0.2 g of Fat Red (TM) dye (from SIGMA) was added and the mixture was stirred vigorously (2000 rpm) for 6 hours using a Heidolph stirrer. The stirred mixture was re-cooled when not in use. Vitreous enamel tiles (380 x 300 mm) were cleaned using a fresh damp J-CLOTH (TM), using sequentially JIF Cream (TM), then a commercially available brand of handwashing liquid and finally calcite powder. After drying, residual calcite was removed by polishing with a paper towel. 1 ml of the compositions listed in Table 1 was rubbed onto the cleaned tiles using a fresh damp J-CLOTH. The tiles were rinsed with tap water for 15 seconds to remove excess composition and allowed to drain. The tiles were soiled over an area of 215 x 150 mm using a DeVilbiss (TM) gravity feed spray gun (MODEL MPS-514/515) using compressed air at 25 psi by spraying from 27 cm for 35 seconds. The soiled tiles were placed horizontally in an 85ºC oven and thermally aged for 1.5 hours and then held overnight. The tiles were hand cleaned using damp J-Cloth and the compositions listed in Table 1. The effort required to clean the tiles was reported as "ETh" in Table 1. The ETh measurements are expressed in Newtons second, higher values indicate that greater effort was required to clean the tile.

Stability was determined by storing samples at 5, 25 and 37ºC for 3 months. In cases indicated as unstable in Table 1, a cloudy precipitate formed under one or more of the storage conditions.

The results in Table 1 show that the lowest purification effort values were obtained for Example 2, which is an embodiment of the invention using the quaternary cationic VBM with longer chain fatty alkyl groups. Examples 3 and 4 also showed an improvement over the control preparation provided by Example 1. It can be seen that this improvement was either small, as with the shorter fatty alkyl chains (CTAB: as used in Example 4) or product stability was lost on storage, as with the difatty alkyl material (2HT: as used in Example 3). Example 5 shows that the combination of an alkaline salt with VBM did not result in a stable product.

Further results are shown in Table 2 below. The same raw materials were used as described above. ETh is as described above. Sample 11 was prepared as Sample 1. Samples 6, 7, 9 and 10 were prepared as Samples 2 and 5. Sample 8 was prepared as Sample 3.

"WIRA" is % soil removal using a Wool Industries Research Association Abrasion Test Apparatus. To obtain these results, 10 cm x 10 cm stainless steel tiles were cleaned using calcite and then rinsed with deionized water. 25 g salad oil (from Nisshin, Japan), 5 g plain flour (Homepride (RTM) from Dalgety, UK) and 75 g acetone were stirred for 2 minutes under This mixture was then sprayed using a Humbrol (RTM) airbrush paint sprayer onto the cleaned tiles using a circular stencil, giving patches of soil 5.5cm in diameter. The acetone was allowed to evaporate, giving 0.04 to 0.05g of soil per tile. The soiled tiles were heated to 175ºC for 34 minutes and left overnight before cleaning. The soiled tile was placed in the "WIRA" tester and 0.5ml of test product was applied. The tile was then cleaned using a "J-cloth" (RTM) (from Johnson and Johnson, UK) folded to give eight layers, with a head pressure of 657g/cm2, over a full cycle (17 passes of the head). This procedure was repeated for a total of three full cycles, using a fresh J-cloth and 0.5 ml of test product each time. After all three cycles, the soiled tile was removed, rinsed and allowed to dry at 50ºC for 30 minutes. The total mass of soil removed was then calculated and expressed as a percentage of the original soil mass. This is reported as "WIRA" in Table 2.

CB is the contact angle on glass contacted with the composition of the invention using bromonaphthalene. Table 2

Examples 6, 7 and 10 are in accordance with the invention, while the remaining examples are comparative. Example 11 is a commercially available successful kitchen cleaner. Table 2 clearly shows that a greater cleaning effort (ETh) is required when no quaternary cationic surfactant is present (Example 11) or when the quaternary cationic surfactant has a short chain (Example 8).

The WIRA results, for which higher ratings are better, show that the presence of organic amines AMP (Examples 6 and 10) or DEA (Example 7) results in considerably more effective compositions compared to those in which the amine is not present (Example 9).

The CB data show that the compositions of the invention modify the surface energy (which can be calculated from the contact angle) compared to a known kitchen cleaning formulation (Example 11) that does not contain a quaternary cationic surfactant. The modification of the Surface energy is lower for the CTAB-based preparations (Example 8).

Overall, it can be seen that Examples 6 and 7, which clean a surface with reduced effort, leave the surface energy modified to prevent or reduce re-soiling. Example 8 is less effective, particularly with respect to thermally aged soil. The preparation of Example 9 attacks thermally aged soil used to determine ETh, but is poor as a general purpose cleaner. Example 10 is acceptable, but it is preferred that no carbonate be present.

Claims (10)

1. An aqueous hard surface cleaning composition comprising a surfactant mixture, the surfactant mixture comprising: a) at least 65% by weight, based on the total surfactant, of non-ionic surfactant, b) less than 1% by weight, based on the total surfactant, of anionic surfactant, c) 0.1 to 35% by weight, based on the total surfactant, of a cationic surfactant which is a mono-fatty quaternary alkyl ammonium compound, wherein the alkyl chains comprise at least 10% by weight of C18-C26 alkyl groups, the composition further comprising at least 0.5% by weight of an organic amine having a pKa of at least β.0. 2. Composition according to claim 1, wherein the quaternary mono fatty alkyl ammonium compound has the general formula [R1 R2 R3 R4 N]+X wherein R₁, R₂ and R₃ are independently C₁-C₆ alkyl radicals, R₄ is a fatty alkyl chain and X is a monovalent anionic equivalent, the distribution of chain lengths in the material being such that less than 60% of the material comprises monofatty alkyl quaternary ammonium compounds in which the fatty alkyl chain is C₁₆ or shorter. 3. A composition according to claim 2, wherein R₁ = R₂ = R₃ = CH₃. 4. A composition according to any one of claims 1 to 3, wherein the mono-fatty quaternary alkyl ammonium compound is trimethylbehenyl ammonium halide. 5. A composition according to claim 1, wherein the ratio of nonionic surfactant to anionic and cationic surfactant is such that more than 75% of all surfactants present in the composition are nonionic. 6. Composition according to claim 1, containing 2 to 10% of an organic amine. 7. The composition of claim 1, wherein the organic amine is selected from the group consisting of 2-amino-2-methyl-1-propanol, monoethanolamine and diethanolamine. 8. A composition according to claim 1, packaged in a container designed to produce a spray of 0.1 to 1.5 ml of product per spray operation, the spray having an average droplet size in the range of 30 to 300 µm. 9. Composition according to claim 1 having a pH > 10, which, mixed with water, comprises: a) 3 to 15% non-ionic surfactant b) 2 to 10% solvent c) 2 to 6% organic amine d) 0 to 2000 ppm polymer and e) 0.1 to 4% of a cationic surfactant of the general formula [R₁R₂R₃R₄N]⁺X⁻, wherein R₁, 1% and R₃ are independently C₁-C₆ alkyl radicals, R₄ is a fatty alkyl chain having at least 10% C₁₈-C₂₆ carbon atoms and X is a monovalent anionic equivalent. 10. A method for cleaning hard surfaces comprising the step of treating the surface with a composition according to any one of claims 1 to 9 by spraying the composition onto the surface.