COMPOSITION FOR CLEANING HARD SURFACES AT HIGH PRESSURE

Description

Technical Field

[0001] The present invention relates to the field of compositions for cleaning hard surfaces at high pressure, and especially for cleaning the outer surfaces of vehicles.

Technical Background

[0002] Cleaning hard surfaces, both domestic and industrial, is a problem that has attracted a considerable interest over many decades.

[0003] The problems generated by such cleaning have their origins in both the heterogeneous set of objects that constitute hard surfaces and the diversity of materials that form them, including, for example, metals, glass, ceramics, porcelain, plastics, gum, rubber or wood.

[0004] A specific case of hard surface cleaning that motivates a particular interest is the exterior car wash. In this case, the surface is predominantly metallic, optionally galvanized, typically with an outer coating made of paints and/or varnishes, which can also include chromed elements. Likewise, it is also common the presence of other materials such as plastics, rubber, and glass.

[0005] Maintaining clean the outer surface of the vehicle is desirable not only for esthetic reasons but also in order to prevent its premature deterioration, avoiding its wear, discoloration and corrosion as much as possible. One of the elements that contribute to the deterioration of the outer surface of the vehicles is constituted by a particular type of dirt which adheres to said surface, forming a film, which is usually designated by the term traffic film. The composition of this film of dirt includes a great variety of substances, both organic and inorganic, having very different physical and chemical characteristics (in particular their high degree of adhesion to the surface, probably due to electrostatic attractions), making it particularly difficult to eliminate.

[0006] In order to get an effective cleaning of the traffic film, an aggressive treatment is often necessary, both chemical and mechanical, that can impact negatively on the surface, particularly on the paint and/or varnish coating. In general, it is desirable to avoid cleaning systems involving mechanical removal of dirt from the surface by rubbing, since such an abrasive treatment involves a risk of scratch and wear of the car coating.

[0007] In this regard, non rubbing cleaning systems have been developed, based on pressure spraying of cleaning compositions onto the vehicle surface. However, it has been found that with simple detergent compositions, complete dirt removal is not achieved, and that for achieving a degree of cleanliness, which is not always acceptable, high concentrations of detergent are required, which is a serious drawback from both an economic and environmental point of view. In the prior art several more effective compositions or methods for cleaning hard surfaces by pressure spraying have been proposed, using detergent compositions in combination with certain particles conferring abrasive properties to such compositions.

[0008] Thus for example, the European patent application EP-A-1184452 discloses a detergent composition for use in the cleaning of hard surfaces by spraying, comprising spherical particles, which produce an abrasive effect due to the kinetic energy of said particles when directed at high pressure onto the surface. Such particles are composed of silicic acid, silicic acid derivatives, silicates or alumina.

[0009] In the British patent application GB1099701 a process for cleaning surfaces is described, by high pressure treatment with a detergent solution which further comprises particles of a thermoplastic material such as polyethylene, polypropylene, polystyrene or acrylonitrile butadiene styrene (ABS). These particles, preferably, have a spherical or rounded shape so as not to damage the surface being cleaned.

[0010] In the international patent application WO-A-94/16831 a method for cleaning surfaces is described consisting in spraying a pressurized liquid comprising surfactants together with water soluble abrasive particles, preferably sodium or potassium carbonate, bicarbonate or sulfate.

[0011] Furthermore, in the international patent application WO-A-98/29193 a cleaning composition to be used for spraying is described, comprising abrasive particles which can be water soluble, for example, sodium bicarbonate, sodium tripolyphosphate pentahydrate, sodium tetraborate decahydrate, potassium sulfate or sodium citrate; or they can be water-insoluble abrasive particles such as silicon dioxide, silicates, calcium carbonate, dicalcium phosphate, iron oxide, calcium pyrophosphate, sodium metaphosphate, diatomite or aluminum oxide.

[0012] In spite of the different cleaning compositions and methods proposed in the prior art, there remains a need for new compositions for cleaning hard surfaces, applicable by high pressure spraying, which are effective for the removal of dirt, while they do not deteriorate the surface, especially in the case of the more vulnerable surfaces, such as those having a paint, varnish or similar finish.

Object of the Invention

[0013] The object of the present invention is a composition for cleaning hard surfaces.

[0014] It is also part of the object of the present invention a method for cleaning hard surfaces.

[0015] It is also part of the object of the present invention the use of discrete particles of cellulose for cleaning hard surfaces.

Detailed Description of the Invention

[0016] The object of the present invention is a composition for cleaning hard surfaces at high pressure, comprising discrete particles of cellulose whose average particle size is less than or equal to 200 µm.

[0017] The authors of the present invention have developed a composition for cleaning hard surfaces at high pressure, comprising discrete particles of cellulose which, surprisingly, is highly effective for removing the dirt adhered to these surfaces. It has been found that such composition is particularly effective for significantly removing the film of dirt of the traffic film type adhered to the outer surfaces of the vehicles without causing the deterioration of the cleaned surface.

The discrete particles of cellulose

[0018] Within the scope of the present invention, the discrete particles of cellulose refer to insoluble particles of cellulose.

[0019] The discrete particles of cellulose suitable for being used in the compositions of the present invention are selected from the group consisting of microcrystalline cellulose, powdered cellulose, nanocellulose, cellulose microfibers, and mixtures thereof. Preferably they are selected from microcrystalline cellulose, cellulose microfibers, and mixtures of both.

[0020] Said discrete particles of cellulose can have a granular appearance, with variable and irregular shapes, as is the case of microcrystalline cellulose, powdered cellulose and nanocellulose; or they can be filaments, of substantially cylindrical shape, as is the case of cellulose microfibers.

[0021] The average particle size of microcrystalline cellulose, powdered cellulose and nanocellulose is usually characterized by its equivalent average diameter, which is determined according to the conventional analytical methods for measuring the average particle size as described, for example, in the book M. E. Aulton, Farmacia. La ciencia del diseño de las formas farmacéuticas, second edition, Elsevier, Madrid, 2004, by the electrical sensing zone method (Coulter counter), or by laser light scattering.

[0022] The substantially cylindrical cellulose microfibers are usually characterized by the length (L) and thickness (T) of the same. Within the context of the present invention, the cellulose microfibers are also characterized by their equivalent diameter, whose value corresponds to the diameter of a hypothetical sphere that has the same volume as the cylindrical filament defined by the above mentioned L and T dimensions.

[0023] Thus, within the scope of this invention, the average particle size of the discrete particles of cellulose refers to the equivalent average diameter determined according to the methods described above, depending on the type of particles of cellulose concerned.

[0024] The discrete particles of cellulose that are part of the object of the present invention have an average particle size of less than or equal to 200 µm, typically comprised between 0.05 µm and 200 µm, preferably between 1 µm and 150 µm, and more preferably comprised between 10 µm and 100 µm.

[0025] The microcrystalline cellulose, powdered cellulose and the cellulose microfibers are commercially available. Nanocellulose can be obtained from the aforementioned ones, for example by an ultrasound treatment that reduces the average particle size to dimensions of about 1 µm or less.

[0026] Microcrystalline cellulose is a crystalline powdered substance, obtained by controlled hydrolysis of α-cellulose, which shows the characteristics specified for example in the handbook of pharmaceutical excipients, R. C. Rowe, P. J. Sheskey and P. J. Weller, Handbook of Pharmaceutical Excipients, Fourth Edition, Pharmaceutical Press, 2003. Microcrystalline cellulose is commercially available from several suppliers, for example from the company FMC Biopolymer under the general trade name AVICEL®, and it is available in different average particle sizes which are usually comprised between 1 µm and 200 µm. Also microcrystalline cellulose qualities can be obtained from the company Acros Organics, with an average particle size of 50 µm or 90 µm. It can also be obtained from the company Sigma-Aldrich under the name Cellulose microcrystalline 310697 with an average particle size of 20 µm.

[0027] Preferably microcrystalline cellulose with an average particle size comprised between 20 µm and 100 µm is used.

[0028] The powdered cellulose is a powder obtained by reducing the size of α-cellulose by mechanical means, which shows the characteristics specified in the book R. C. Rowe, already cited. The cellulose in powdered form is commercially available, for example from the company J. Rettenmaier & Söhne, under the general trade name ARBOCEL®. Said cellulose is available in different average particle sizes which usually are comprised between 1 µm and 200 µm.

[0029] The cellulose microfibers can be obtained by means of several mechanical and/or chemical treatments of cellulose until cellulose in the form of filaments is obtained. Cellulose microfibers are commercially available from several suppliers, for example from the company J. Rettenmaier & Söhne, under the general trade name ARBOCEL®. Said microfibers are available in different sizes, and are usually characterized by the length (L) and thickness (T) of the same. The cellulose microfibers suitable for being used in the present invention can have a length comprised approximately between 1 µm and 220 µm, and a thickness comprised approximately between 0.01 µm and 150 µm, which corresponds to an equivalent average diameter comprised between 0.05 µm and 195 µm, according to the approach discussed above. Preferably cellulose microfibers that have an equivalent average diameter comprised between 10 µm and 30 µm are used.

[0030] The cellulose nanoparticles can be obtained from any of the particles of cellulose described above, i.e. from microcrystalline cellulose, powdered cellulose or cellulose microfibers, subjecting them to a process to reduce their size. This reduction can be achieved, for example, by ultrasound treatment of a liquid dispersion of said particles, until obtaining nanoparticles of cellulose whose average size is equal to or less than 1 µm, preferably comprised between 0.05 µm and 1 µm. Preferably, the ultrasound treatment is performed at a power of 450 W, for a time period comprised between 5 minutes and 3 hours, using a dispersion of the particles of cellulose preferably in distilled water with a concentration comprised between 0.01% and 20%, by weight.

Composition

[0031] The composition for cleaning hard surfaces at high pressure of the present invention comprises discrete particles of cellulose as defined above.

[0032] Preferably, the composition object of the present invention comprises between 1% and 20% of discrete particles of cellulose, percentage expressed as weight of cellulose relative to the total weight of solids of the composition. Within the context of the invention, the term "solids" refers to all the ingredients of the composition, except water and, occasionally, other co-solvents.

[0033] The cleaning effect of the discrete particles of cellulose is so significant that in a preferred embodiment of the invention, the cleaning composition only comprises discrete particles of cellulose as insoluble product, i.e., the composition does not comprise additional abrasive products.

[0034] In its simplest implementation, the composition comprises discrete particles of cellulose dispersed in water and preservation agents. In this case the composition comprises between 1% and 20% by weight relative to the total weight of the composition.

[0035] To obtain a more significant degree of cleanliness, preferably said composition further comprises surfactants, coadjuvants, and optionally other auxiliary products.

[0036] This composition comprising surfactants, adjuvants and optionally other auxiliary components can be in solid or liquid form, without having any influence on the result of the cleaning, since, as explained below, the composition, whether solid or liquid, is dispersed in water before being applied at high pressure onto the hard surface.

[0037] Surfactants, as is well known by the skilled in the art, are amphiphilic substances which have a hydrophobic portion and a hydrophilic portion. This particular chemical structure of surfactants plays an important role in the washing process because they lower the surface tension of the liquid providing improved wetting of the surfaces and they are also able to form aggregates such as micelles, which allow dissolving, emulsifying or disaggregating the dirt.

[0038] The surfactants suitable for being used in the compositions of this invention are selected from the group consisting of anionic, nonionic, cationic and amphoteric surfarctants, and mixtures thereof.

[0039] A great variety of surfactants are commercially available from several suppliers such as, for example, the companies Kao Corportation, BASF, Croda, Huntsman, Evonik, or Cognis (now BASF), among others.

[0040] Among the anionic surfactants suitable for being used within the context of the present invention are, for example, soaps, alkylbenzenesulfonic acids and their salts, sulfonated α-olefins, sulfonated paraffins, alkyl sulfates, alkyl ether sulfates, glycerin ether sulfates, alkyl sulfosuccinates, carboxylic acids ethers and their salts, alkyl phosphates, alkyl ether phosphates, alkylphenol sulfates, alkylphenol ether sulfates, isethionates, sarcosinates, taurates, and N-acylamino acid salts. Only to cite some examples of this group, among the alkyl ether sulfates there is the sodium lauryl ether sulfate, as the one supplied by the company Kao Corporation under the trade name or EMAL® or the product range TEXAPON® from the company Cognis (now BASF); alkyl sulfates are commercially available under the name SULFOPON® from the company Cognis (now BASF); among the carboxylic acids ethers are those supplied by the company Kao Corporation under the trade name AKYPO®; or among the alkylbenzenesulfonic acids should be mentioned, for example, the linear alkylbenzene sulfonic acid (LAS), especially the n-dodecylbenzenesulfonic acid and its salts, such as for example the one supplied by the company Cognis (now BASF) under the trade name MARANIL®.

[0041] Among the nonionic surfactants suitable for being used within the context of the present invention are, for example, ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated alkylphenols, fatty acid alkanolamides, ethoxylated fatty acid alkanolamides, ethoxylated fatty amines, fatty amine oxides, fatty amidoamine oxides, esters of glycerin and fatty acids, sorbitan esters, ethoxylated sorbitan esters, sucrose esters, alkylpolyglycosides, copolymers of ethylene/propylene oxide, among others. Thus, for example, among the ethoxylated fatty alcohols can be mentioned those provided by the company Cognis (now BASF) under the trade name DEHYDOL®, such as DEHYDOL® LT7 which is a C₁₂-C₁₈ fatty alcohol with about 7 moles of ethylene oxide. Among the ethoxylated sorbitan esters can be mentioned those provided by the company Kao Corporation under the trade name RHEODOL®. Among the ethoxylated alkylphenols can be mentioned the products marketed under the name DEHYDROPHEN® by the company Cognis (now BASF).

[0042] Among the amphoteric surfactants suitable for being used within the context of the present invention are, for example, alkyldimethyl betaines, alkylamidobetaines, alkylsulfobetaines, alkylamidosulfobetaines, imidazoline derivatives and alkylaminopropionates, among others. Thus, for example, among the alkylamidobetaines can be mentioned those supplied by the company Cognis (now BASF) under the trade name DEHYTON®.

[0043] The cationic surfactants suitable for being used within the context of the present invention are quaternary ammonium compounds having an antistatic effect, such as benzalkonium chloride, which is commercially available under the trade name DEHYQUART® supplied by the company Cognis (now BASF).

[0044] In the book M. Asch and I. Asch, Handbook of Industrial Surfactants, Fourth Edition, Synapse Information Resources, 2005, an extensive list of commercially available surfactants can be found.

[0045] As coadjuvant agents can be used, for example, polyphosphates, especially tripolyphosphates and alkali pyrophosphates, alkali carbonates, alkali silicates, zeolites, alkali salts of nitriloacetic acid, EDTA and its salts, the present eco-friendly substitutes for NTA/EDTA/phosphates, such as GLDA (Glutamic Acid N,N-Diacetic Acid) commercially available under the name Disolvine® GL from Akzo Nobel, alkali salts of citric acid, and mixtures thereof. The alkali salt preferably used is sodium salt.

[0046] The cleaning composition object of the present invention can optionally contain other auxiliary products such as, for example, enzymes, colorants, foam stabilizers, thickeners, co-solvents, and pH regulators. When it is a liquid composition, it generally further comprises preservative agents.

[0047] In a preferred embodiment of the present invention, the cleaning composition comprises between 1% and 20% of discrete particles of cellulose, preferably between 5% and 10%; between 5% and 50% of surfactants, preferably between 10% and 30%; and between 35% and 95% of coadjuvants, preferably between 50% and 65%. These percentages are expressed by weight relative to the total weight of solids of the composition. The percentages of the different components are selected so that the sum thereof is the 100% of the composition.

[0048] In a more preferred embodiment of the present invention, the cleaning composition comprises between 1% and 20% of discrete particles of cellulose, preferably between 5% and 10%; between 2% and 20% of anionic surfactants, preferably between 2% and 10%; between 3% and 30% of nonionic surfactants, preferably between 5% and 15%; and between 35% and 95% of coadjuvants, preferably between 50% and 65%. These percentages are expressed by weight relative to the total weight of solids of the composition. The percentages of the different components are selected so that the sum thereof is the 100% of the composition.

[0049] In a particularly preferred embodiment the anionic surfactant is an alkali salt of a linear alkylbenzenesulfonic acid, and more preferably is the sodium salt of the n-dodecylbenzenesulfonic acid; the nonionic surfactant is an ethoxylated fatty alcohol, more preferably is an alcohol with C₁₂-C₁₈ chain ethoxylated with about 7 moles of ethylene oxide, and the coadjuvant is selected from the group consisting of sodium tripolyphosphate, sodium carbonate, and mixtures of both, more preferably the coadjuvant is a mixture of sodium tripolyphosphate and sodium carbonate.

[0050] A characteristic solid cleaning composition according to the present invention comprises, for example, between 1% and 20% of discrete particles of cellulose, between 5% and 45% of sodium tripolyphosphate, between 20% and 50% of sodium carbonate, between 2% and 10% of anionic surfactant and between 5% and 15% of nonionic surfactant. These percentages are expressed by weight relative to the total weight of solids of the composition. The percentages of the different components are selected so that the sum thereof is the 100% of the composition.

[0051] Optionally, the composition can also contain other ingredients such as amphoteric surfactants, cationic surfactants, enzymes, colorants, foam stabilizers, among others.

[0052] The preparation of the detergent composition is performed according to methods that are well known in the field of detergent technology. For example a solid detergent composition can be prepared by direct mixing of all the ingredients when they are solid, being also directly mixed with the discrete particles of cellulose. It can also be prepared by a process comprising a step of spray drying, for which a paste known as slurry is previously prepared by dispersing some of the components in water, usually anionic surfactants and coadjuvants. Said slurry is subjected to spray drying, for example, by a counterflow of hot air. Thus, powdered detergent composition particles are obtained with an apparent density approximately comprised between 300 g/l and 1000 g/l. The atomized detergent composition can be completed by the further addition of other components, for example, nonionic surfactants. The discrete particles of cellulose can also be added in this final step to the detergent already atomized.

[0053] A characteristic liquid cleaning composition according to the present invention comprises, for example, between 0.5% and 5% of discrete particles of cellulose, between 10% and 20% of sodium tripolyphosphate, between 1% and 15% of nonionic surfactant and between 1% and 10% of anionic surfactant, adding water, optionally in combination with other co-solvents, until reaching the 100% of the composition. In this case, the percentages are expressed by weight of each ingredient relative to the total weight of the composition including water and possibly the co-solvents. Some co-solvents suitable for being used in the liquid formulations of the invention are, for example, propylene glycol, 1-methoxy-2-propanol, glycerin, cumenesulfonate, dipropylene glycol, dipropylene glycol monomethyl ether, butyl glycol, or butyldiglycol. Optionally, the liquid detergent formulation can contain other ingredients such as amphoteric surfactants, cationic surfactants, enzymes, colorants, foam stabilizers, thickening agents, pH regulators, and preservative agents, among others.

[0054] The preparation of the liquid detergent is performed by methods that are also well known in the field of detergent technology. For example, it can be prepared by dissolving the different components in water under stirring until achieving a homogeneous solution. The discrete particles of cellulose can be added, for example, in a final step, to the prepared detergent composition, by mechanical stirring or by other methods of dispersion such as, for example, sonication, until obtaining a homogeneous dispersion of such particles in the liquid medium.

The hard surface

[0055] Within the context of the present invention, the term hard surface is understood broadly and comprises, for example, any metal surface, for example, of aluminum, chromium, steel, or stainless steel; glass, ceramic or porcelain surfaces; rubber or gum surfaces; surfaces of any type of plastic, such as thermoplastic or thermosetting polymers, among other possible materials. Moreover, such surfaces coated with a layer of paint, varnish, enamel, or other finishing are also included.

[0056] The hard surfaces to be cleaned by the method of the present invention may correspond to a wide variety of objects, both domestic and industrial. Among them can be mentioned, for example, floors, walls, tiles, sinks, work surfaces, blinds, windows, bathrooms, any type of outdoor furniture, panels, containers, tarps, machinery, or the outer surface of any type of vehicle.

[0057] In a preferred embodiment, the cleaning composition and the cleaning method of the present invention are applied for the cleaning of the outer surface of a vehicle. It has been observed that the composition of the invention is particularly effective for eliminating the so-called traffic film.

[0058] This is a particular type of dirt that adheres to the outer surface of the vehicle to form a film and that is difficult to remove without touching the surface in a "touchless" process, i.e., without the help of a mechanical effect: wiping, brushing, etc., by means of the methods described in the prior art because it has a very heterogeneous composition.

[0059] The traffic film can contain, for example, fuel combustion residues, fuel leaks, carbon black, lubricating substances, residues of previous washings and very heterogeneous environmental substances present in the roads, such as salts, sand, or mud.

[0060] Within the context of the present invention, the term vehicle includes any means of transport, typically, cars, trucks, buses, trailers, wagons, motorcycles, airplanes, aircraft, or parts thereof, among others.

Cleaning Method

[0061] It is also part of the object of this invention a method for cleaning hard surfaces comprising the step of spraying at high pressure onto the hard surface an aqueous dispersion of the composition of the invention comprising discrete particles of cellulose whose average particle size is less than or equal to 200 µm.

[0062] Within the context of the present invention, high pressure refers to a pressure equal to or higher than 10 bar. In a preferred embodiment, the cleaning method is performed at a pressure comprised between 20 and 200 bar, more preferably comprised between 50 and 150 bar, and more preferably between 90 and 110 bar.

[0063] The high pressure spraying can be performed using a pressure washer machine such as the ones existing on the market, for example, those supplied by the company Nilfisk-ALTO, Kärcher or piston pumps of the "CAT" or "Interpump" type.

[0064] In the method of the invention the aqueous dispersion to be sprayed is prepared by dispersing the composition of the invention in water. That is, the method of the invention comprises a prior step of preparing an aqueous dispersion of the composition that comprises the discrete particles of cellulose.

[0065] Typically, such machines have a tank in which a stock aqueous dispersion of the composition comprising the discrete particles of cellulose is prepared.

[0066] In one embodiment of the invention, this aqueous dispersion is prepared by dispersing in water the composition of the invention, either in solid or liquid form, until an approximate dilution of 1 to 10 g/l of it, remaining the particles of cellulose in suspension.

[0067] Typically, this stock aqueous dispersion is dosed within a jet of pressurized water, by means of a device that said pressure washer machines have for this purpose, and this allows the final concentration to be conveniently adjusted in the sprayed water, or nozzle concentration, which is the one effectively propelled against the surface to be cleaned.

[0068] According to the cleaning method of the present invention, the nozzle concentration of the discrete particles of cellulose is preferably comprised between 0.005% and 0.2%, more preferably between 0.005% and 0.1%, and still more preferably between 0.005% and 0.05%, wherein the percentage is expressed by cellulose weight relative to the weight of the sprayed aqueous dispersion.

[0069] The cleaning devices used usually have a system for heating the water for its subsequent application at pressure onto the surface to be cleaned. The cleaning method according to the present invention can be performed at a temperature comprised between room temperature and approximately 90° C, preferably between 40° C and 70° C, and still more preferably between 50° C and 60 °C.

Efficacy testing

[0070] Several tests were performed to evaluate the efficacy of the high pressure cleaning method that is part of the invention, in particular, by using the cleaning compositions of the invention. The results of these tests are explained in detail in the Examples section.

[0071] From the results obtained, the inventors of the present invention found that, surprisingly, with the compositions of the invention including discrete particles of cellulose, a substantially superior efficacy is achieved in the cleaning of hard surfaces compared with detergent compositions that do not comprise said particles.

[0072] It has also been observed that the use of the cellulose particles in the detergent composition for the cleaning of hard surfaces can allow the chemical charge of the composition to be reduced without decreasing the efficacy.

[0073] Additionally, it has been observed that with the composition of the invention the nozzle concentration can be significantly reduced, cleaning times are optimized and the wastewater is reduced.

[0074] It is noteworthy the synergistic effect that was observed by incorporating the discrete particles of cellulose in a detergent composition. As explained in the examples, with a lower nozzle concentration of particles of cellulose and of detergent, a greater degree of cleanliness was obtained than that obtained with a higher content of particles of cellulose, but without detergent, or with a higher detergent concentration, but without particles of cellulose.

[0075] Therefore, it is also an object of the present invention the use of discrete particles of cellulose of average particle size less than or equal to 200 µm for high pressure cleaning of hard surfaces, such as for example for cleaning of the outer surface of a vehicle

[0076] The use of discrete particles of cellulose facilitates the removal of dirt of the traffic film type from the vehicles in processes without intervention of physical or mechanical means such as brushes or chamois clothes, which tend to be aggressive to the treated surfaces because, for example, they can produce scratches on the painted surface.

Examples

Preparative Example: Nanocellulose preparation

[0077] 1g of microcrystalline cellulose from the company Sigma-Aldrich with an average particle size of 20 µm (Cellulose microcrystalline 310697) was incorporated in 100 ml of distilled water and it was stirred until obtaining a homogeneous dispersion.

[0078] The obtained dispersion was treated with ultrasounds at a power of 450 W for 1 hour.

[0079] After this time, a sample of the dispersion was taken that was observed under the microscope and it was found that there had been a significant reduction in the average size of the particles of cellulose, obtaining nanocellulose, whose average particle size was less than 1 µm.

Reference Example 1: Preparation of a liquid detergent composition without discrete particles of cellulose

[0080] A liquid detergent composition was prepared by the dissolution in water of 20% by weight of sodium tripolyphosphate, 10% by weight of DEHYDOL® LT-7 of the company Cognis (now BASF) (C₁₂-C₁₈ alcohol ethoxylated with 7 moles of ethylene oxide), 5% by weight of dodecylbenzenesulfonic acid neutralized with 0.6% by weight of sodium hydroxide.

[0081] For the preparation of such composition, first the dodecylbenzenesulfonic acid was dispersed under stirring in a part of the water, adding then the sodium hydroxide required to neutralize said acid. Subsequently, the other components and the remaining water were added, and the mixture was kept under stirring until a homogeneous solution was obtained.

Reference Example 2: Preparation of a solid detergent composition without discrete particles of cellulose

[0082] In a solids mixer a solid detergent composition was prepared containing 40% by weight of sodium tripolyphosphate, 45% by weight of sodium carbonate, 10% by weight of DEHYDOL® LT-7 of the company Cognis (now BASF) (C₁₂-C₁₈ alcohol ethoxylated with 7 moles of ethylene oxide), and 5% by weight of dodecylbenzenesulfonic acid. The mixture was kept under stirring until a homogeneous powder was obtained.

Example 1: Liquid detergent composition with microcrystalline cellulose

[0083] A liquid detergent composition was prepared by the dissolution in water of 20% by weight of sodium tripolyphosphate, 10% by weight of DEHYDOL® LT-7 of the company Cognis (now BASF) (C₁₂-C₁₈ alcohol ethoxylated with 7 moles of ethylene oxide), 5% by weight of dodecylbenzenesulfonic acid neutralized with 0.6% by weight of sodium hydroxide and 1.77% by weight of microcrystalline cellulose of the company Sigma-Aldrich with an average particle size of 20 µm (Cellulose microcrystalline 310697).

[0084] For the preparation of such composition, first the dodecylbenzenesulfonic acid was dispersed under stirring in a part of the water, adding then the sodium hydroxide required to neutralize said acid. Subsequently the sodium tripolyphosphate, the nonionic surfactant, and the remaining water were added, and the mixture was kept under stirring until a homogeneous solution was obtained. Finally the cellulose microfibers were added.

[0085] The cellulose content of this composition was 4.8% by weight relative to the weight of the active components, that is, all of them except water.

Example 2: Solid detergent composition with cellulose microfibers

[0086] In a solids mixer a solid detergent composition was prepared containing 40% by weight of sodium tripolyphosphate, 45% by weight of sodium carbonate, 10% by weight of DEHYDOL® LT-7 of the company Cognis (now BASF) (C₁₂-C₁₈ alcohol ethoxylated with 7 moles of ethylene oxide), 5% by weight of dodecylbenzenesulfonic acid, and 11.11% of cellulose microfibers having a length of 23 µm and a thickness of 17 µm (ARBOCEL® BE 600-20), which represents an equivalent average diameter of 22 µm. The mixture was kept under stirring until a homogeneous powder was obtained. The weight ratio of cellulose relative to the total of the composition was 10%.

Example 3: Solid detergent composition with microcrystalline cellulose

[0087] In a solids mixer a solid detergent composition was prepared containing 40% by weight of sodium tripolyphosphate, 45% by weight of sodium carbonate, 10% by weight of DEHYDOL® LT-7 of the company Cognis (now BASF) (C₁₂-C₁₈ alcohol ethoxylated with 7 moles of ethylene oxide), 5% by weight of dodecylbenzenesulfonic acid, and 11.11% of microcrystalline cellulose with an average size of 90 µm of the company Acros Organics. The mixture was kept under stirring until a homogeneous powder was obtained. The weight ratio of cellulose relative to the total of the composition was 10%.

Example 4: Solid detergent composition with microcrystalline cellulose

[0088] In a solids mixer a solid detergent composition was prepared containing 40% by weight of sodium tripolyphosphate, 45% by weight of sodium carbonate, 10% by weight of DEHYDOL® LT-7 of the company Cognis (now BASF) (C₁₂-C₁₈ alcohol ethoxylated with 7 moles of ethylene oxide), 5% by weight of dodecylbenzenesulfonic acid, and 11.11% of microcrystalline cellulose with an average size of 50 µm HEWETEN® 101 of the company J. Rettenmeier & Söhne. The mixture was kept under stirring until a homogeneous powder was obtained. The weight ratio of cellulose relative to the total of the composition was 10%.

Example 5: Aqueous composition with microcrystalline cellulose

[0089] In a container provided with stirring, 10 g of microcrystalline cellulose of the company Sigma-Aldrich with an average particle size of 20 µm (Cellulose microcrystalline 310697) were dispersed in 190 g of water. The dispersion was kept under stirring until a homogeneous dispersion was obtained, then, it was treated with ultrasounds at a power of 450 W for 90 minutes.

Example 6: Comparative tests of efficacy

[0090] A painted surface of a vehicle previously soiled with traffic-film type dirt was cleaned according to the method of the invention, using the compositions prepared in Examples 1 to 4. To this end, a pressure washer machine of the brand Nilfisk-ALTO was used.

[0091] The tests of the compositions of the invention were performed at two temperatures: at room temperature and at 53° C, and two pressures: 75 bar and 105 bar.

[0092] For comparison the compositions of the reference examples described above were also tested.

[0093] To test the liquid composition of Example 1, it was conveniently dosed in the feed water of the pressure system to obtain a nozzle concentration of 0.40%, and the surface was cleaned at a pressure of 75 bar and at room temperature. The high pressure spraying was maintained for a period of about 1 minute over an area of 0.25 m².

[0094] In an analogous manner, the efficacy of the solid compositions of Examples 2 to 4 was tested by dispersing 10 g of each of them in 5 l of water to obtain working solutions at the desired composition of 0.2% by weight. In this case, the cleaning method was performed at a pressure of 105 bar, at a temperature of 53° C and for a period of time of 1 minute over an area of 0.25 m².

[0095] The composition of Example 5 was conveniently dosed into the feed water of the pressure system to obtain a nozzle concentration of 0.40% by weight, and the surface was cleaned at a pressure of 75 bar and at room temperature. The high pressure spraying was maintained for a period of about 1 minute over an area of 0.25 m². The high pressure spraying was maintained for a period of 1 minute over an area of 0.25 m².

[0096] The efficacy of the liquid detergent prepared in Reference Example 1, which did not contain cellulose particles, was also tested. To this end, it was conveniently dosed in the feed water of the pressure system to obtain a nozzle concentration of 0.40% by weight, and the surface was cleaned at a pressure of 75 bar and at room temperature. The high pressure spraying was maintained for a period of about 1 minute over an area of 0.25 m².

[0097] Washing tests were also performed with the solid detergent prepared in Reference Example 2, which also lacked cellulose particles. To this end, 10 g were dispersed in 5 l of water and the desired composition of 0.2% by weight was obtained. In this case, the cleaning process was performed at a pressure of 105 bar, at a temperature of 53° C and for a period of time of 1 minute over an area of 0.25 m².

[0098] Water without cellulose particles or detergent was used as a control test.

[0099] To quantify the cleaning efficacy of the different compositions and conditions tested, the evaluation scale shown in Table 1 was used:

TABLE 1

Value	Degree of cleanliness observed
1	Completely clean
2	Hardly noticeable small marks still appear
3	Slight remains of marks
4	Remains of marks
5	Clear and visible remains of marks

[0100] The efficacy of the liquid composition of Example 1 was evaluated using a 2² factorial design with the factors and levels shown in the matrix of Table 2:

TABLE 2

Test	Particles of cellulose	Detergent composition
Control (water)	No	No
Example 5	Yes	No
Reference Example 1	No	Yes
Example 1	Yes	Yes

[0101] All tests were performed at room temperature, at a pressure of 75 bar and for 1 min over an area of 0.25 m².

[0102] In the Control test the cleaning was performed with water without detergent or cellulose; the composition of Example 5 included microcrystalline cellulose with an average particle size of 20 µm, but it did not contain surfactants or adjuvants; the Reference Example 1 was a liquid detergent composition not containing particles of cellulose, and Example 1 was a detergent composition of the invention containing microcrystalline cellulose with an average particle size of 20 µm.

[0103] The results of these tests are presented in Table 3:

TABLE 3

Test	Nozzle concentration	Assessment
Control (water)	-	5
Example 5	0.038% (microcrystalline cellulose)	2-3
Reference Example 1	0.5% (detergent without particles of cellulose)	4
Example 1	0.019% (microcrystalline cellulose)	1
	0.375% (detergent)

[0104] It can be observed that by incorporating microcrystalline cellulose to water, Example 5, there is an improvement in the degree of cleanliness, going from level 5 to level 2-3.

[0105] It can also be observed that by incorporating the detergent composition without particles of cellulose to water some improvement is obtained, but clearly insufficient.

[0106] However, when comparing the results of the reference examples to the degree of cleanliness achieved with the composition of the invention of Example 1, it is observed that a synergistic effect is obtained by adding microcrystalline cellulose to the detergent composition, since with a lower nozzle concentration of particles of cellulose (0.019% vs. 0.038%) and of detergent (0.375% vs. 0.5%) a higher degree of cleanliness is obtained.

[0107] The results obtained with the dispersions prepared from the solid compositions of Examples 2 to 4 are shown in Table 4:

TABLE 4

Test	Nozzle concentration	Assessment
Reference Example 2	0.20% (detergent without particles of cellulose)	3
Example 2	0.02% (cellulose microfibers 20 µm)	1
	0.18% (detergent)
Example 3	0.02% (microcrystalline cellulose 90 µm)	1
	0.18% (detergent)
Example 4	0.02% (microcrystalline cellulose 50 µm)	1
	0.18% (detergent)

[0108] It can be observed that a substantial improvement in the efficacy occurs by incorporating cellulose particles to a detergent composition, both in liquid compositions (Example 1 compared with Reference Example 1), and in solid compositions (Examples 2 to 4 with respect to Reference Example 2).

[0109] It can also be observed that when comparing the results obtained with the solid detergent compositions, no significant differences between the different types of particles of cellulose tested were detected: cellulose microfibers and microcrystalline cellulose of different average sizes.

[0110] In all tests with the compositions of the invention it has been observed that the treated surfaces have not suffered alterations in the surface state, as appearance of scratches or defects, or decrease in brightness.

Claims

1. Composition for cleaning hard surfaces at high pressure, characterized in that it comprises discrete particles of cellulose whose average particle size is less than or equal to 200 µm.

2. Composition according to claim 1, characterized in that the discrete particles of cellulose are selected from the group consisting of microcrystalline cellulose, powdered cellulose, nanocellulose, cellulose microfibers, and mixtures thereof.

3. Composition according to claim 2, characterized in that the discrete particles of cellulose are selected from microcrystalline cellulose, cellulose microfibers, and mixtures of both.

4. Composition according to any one of claims 1 to 3, characterized in that the discrete particles of cellulose have an average particle size comprised between 1 µm and 150 µm.

5. Composition according to claim 4, characterized in that the discrete particles of cellulose have an average particle size comprised between 10 µm and 100 µm.

6. Composition according to claims 3 and 5, characterized in that the discrete particles of cellulose are of microcrystalline cellulose and have an average particle size comprised between 20 µm and 100 µm.

7. Composition according to claims 3 and 5, characterized in that the discrete particles of cellulose are cellulose microfibers and have an equivalent average diameter comprised between 10 µm and 30 µm.

8. Composition according to any one of claims 1 to 7, characterized in that it further comprises surfactants, coadjuvants, and optionally other auxiliary products.

9. Composition according to claim 8, characterized in that it comprises between 1% and 20% of discrete particles of cellulose, between 5% and 50% of surfactants and between 35% and 95% of coadjuvants, percentages expressed by weight relative to the total weight of solids of the composition.

10. Composition according to claim 9, characterized in that it comprises between 1% and 20% of discrete particles of cellulose, between 2% and 20% of anionic surfactants, between 3% and 30% of nonionic surfactants, and between 35% and 95% of coadjuvants, percentages expressed by weight relative to the total weight of solids of the composition.

11. Composition according to claim 10, characterized in that the anionic surfactant is an alkali salt of a linear alkylbenzenesulfonic acid, the nonionic surfactant is an ethoxylated fatty alcohol, and the coadjuvant is selected from sodium tripolyphosphate, sodium carbonate, and mixtures of both.

12. Method for cleaning hard surfaces characterized in that it comprises spraying at high pressure an aqueous dispersion of the composition of any one of claims 1 to 11.

13. Method for cleaning hard surfaces according to claim 12, characterized in that the spraying is performed at a pressure equal to or higher than 10 bar.

14. Method for cleaning hard surfaces according to claim 13, characterized in that the spraying is performed at a pressure comprised between 50 and 150 bar.

15. Method according to any one of claims 12 to 14, characterized in that it is performed at a temperature comprised between room temperature and approximately 90° C.

16. Method according to claim 15, characterized in that it is performed at a temperature comprised between 50°C and 60°C.

17. Method according to any one of claims 12 to 16, characterized in that the aqueous dispersion to be sprayed is prepared by dispersing in water a composition according to any one of claims 1 to 11.

18. Method according to any one of claims 12 to 17, characterized in that the concentration of the discrete particles of cellulose in the aqueous medium that is thrown at high pressure onto the surface is comprised between 0.005% and 0.2%, percentage expressed by cellulose weight relative to the weight of the sprayed aqueous dispersion.

19. Method according to claim 18, characterized in that the concentration of the discrete particles of cellulose in the aqueous medium is comprised between 0.005% and 0.05%, percentage expressed by cellulose weight relative to the weight of the sprayed aqueous dispersion.

20. Method according to any one of claims 12 to 19, characterized in that the hard surface is the outer surface of a vehicle.

21. Use of discrete particles of cellulose of average particle size less than or equal to 200 µm for high pressure cleaning of hard surfaces.

22. Use according to claim 21, characterized in that the discrete particles of cellulose are selected from the group consisting of microcrystalline cellulose, powdered cellulose, nanocellulose, cellulose microfibers, and mixtures thereof.

23. Use according to claim 22, characterized in that the discrete particles of cellulose are selected from microcrystalline cellulose, cellulose microfibers, and mixtures of both.

24. Use according to any one of the claims 21 to 23, characterized in the hard surface is the outer surface of a vehicle.