LIQUID CLEANING COMPOSITION AND METHOD OF CLEANING A

SURFACE DESCRIPTION

Field of the invention The present invention relates to homogenous aqueous liquid cleaning compositions containing low abrasive particles which are suited to the cleaning of hard surfaces.

More specifically, the present invention relates to liquid cleaning compositions suited to the cleaning of hard surfaces such as ceramic, steel, plastic, glass and/or painted surfaces. According to another aspect thereof, the present invention relates to a method of cleaning a surface of an article which is also capable of rendering hydrophilic the cleaned surface.

According to additional aspect thereof, the present invention relates to solid inorganic microparticles and uses thereof as low abrasive material in cleaning compositions and for imparting hydrophilic properties to a substrate.

Background of the invention

Liquid compositions for cleaning hard surfaces are widely available on the market.

These compositions are used for two purposes, the first being to clean soil from the surface and the second being to leave the surface with an aesthetically pleasing finish e.g. spot-free or shiny.

Related art

To this end, hard surface cleaners containing abrasive particles are widely used. Typical liquid abrasive cleaning compositions are disclosed for example in International patent application WO 03/031554 and generally comprise one or more surfactants and a plurality of abrasive particles dispersed therein. The surfactants may form a lamellar micelle aqueous phase which acts as a suspending system to keep the abrasive particles in a stable suspension. Often a polymeric thickening agent is also added to further improve the stability of the suspension.

Typical abrasive materials include minerals such as calcite or dolomite and other materials of relatively high density.

These abrasive materials are generally obtained by grinding naturally occurring minerals or ores obtaining crystalline microparticles having a particle size ranging from 20 to 300 μm and an irregular outer surface formed by sharp-cornered edges formed during the grinding operations.

Although the morphological characteristics of these ground minerals may be beneficial in attaining a satisfactory cleaning action by acting on the soil particles adhered to the surface to be cleaned, the known liquid cleaning compositions containing abrasive particles may damage in the long run delicate surfaces, such as the chromium plated surfaces of taps and fittings used in kitchens and bathrooms, forming micro scratches which irreversibly impair the luster and gloss over time giving a dull look to the surface. In order to obviate in some way to this drawback it has been proposed in the art, as disclosed for example in International patent application WO 2004/013268, to use in a liquid composition shape selective particulate abrasive particulates having a particle size ranging from 1-600 μm and a roundness factor RF (defined as RF = 4πA/P , wherein P is the perimeter and A the surface area of the two-dimensional projection of a particle) of 0.6-1 in order to obtain superior tough soil cleaning and ensure that the cleaning achieved does not affect the desired luster and surface character of the substrate being cleaned.

Apart form the noted problem of possible surface damage, the known liquid cleaning compositions containing abrasive particles have a tendency to leave residues which are difficult to rinse away and often leave water-marks, smears or spots on the cleaned surface which is believed may be due to the evaporation of water from the surface leaving behind deposits of minerals which were present as dissolved solids in the water, for example calcium, magnesium and sodium ions and salts thereof or may be deposits of water-carried soils, or even remnants of abrasive particles. Summary of the invention

The present invention aims at overcoming at least in part one or more of the drawbacks mentioned with reference to the cited prior art and, more specifically, aims at providing a liquid cleaning composition for hard surfaces containing low abrasive particles which allows both to reduce in a substantial way the abrasive action on the surface to be cleaned and to facilitate the rinsing operations while attaining at the same time a satisfactory cleaning action.

According to one aspect thereof, the present invention provides a liquid cleaning composition for hard surfaces as defined in attached claim 1.

More specifically, the liquid cleaning composition of the present invention comprises: - a carrier, at least some of which is aqueous;

- one or more surfactants;

- solid inorganic microparticles having a particle size of from 0.5 to 5 μm, a surface area of from 10 to 50 m ² /g and a crystallinity degree CD lower than 50%, the crystallinity degree being defined as CD = (XZY) « 100 wherein:

Y= diffracted peaks net area + background area, X = diffracted peaks net area of the microparticles X-ray diffraction pattern.

Most advantageously, the liquid cleaning composition of the invention is capable of exerting an effective cleaning action by interacting in a mechanical way with the soil and dirt particles lying even in the tiniest microscratches formed in the surface to be cleaned without abrading in any detectable way the surface to be cleaned and without affecting the ability of the liquid cleaning composition of being rinsed away easily.

Most advantageously, the liquid cleaning composition of the invention is also capable of imparting to the cleaned surface hydrophilic characteristics which render the surface even more rinsable thereby preventing the formation of water spots or streaks which tend to drift away from the surface. By the term hydrophilic it is meant herein that the surface has a high affinity for water.

It has been observed that the liquid cleaning composition of the invention is capable of hydrophilically modify a hard surface on which it is applied to the extent that the hard surface exhibits surprising and significantly improved rinsability, wetting and sheeting, quick drying, uniform drying, anti-spotting, anti-soil deposition, cleaner appearance, enhanced gloss, enhanced color, minor surface defect repair, improved smoothness, anti-hazing properties, modification of surface friction, release of actives, reduced damage to abrasion and improved transparency properties. In addition, the surface cleaned with the liquid cleaning composition of the invention exhibits some advantageous "self-cleaning" properties (dirt removal via water rinsing, e. g. from rainwater) and/or soil release benefits (top layers are strippable via mild mechanical action).

The hydrophilicity can also provide the cleaned surface with resistance to soiling by hydrophobic types of soils.

For the purposes of the present description and of the claims which follow, the term: liquid cleaning composition, is used to indicate compositions in the form of liquids, aqueous gels, phase-separated liquid compositions (such as suspensions) and/or colored liquid compositions.

For the purposes of the present description and of the claims which follow, the term: hard surface, is used to indicate any kind of rigid surfaces typically found in houses like kitchens, bathrooms, or the exterior surfaces of a vehicle, e. g., floors, walls, tiles, windows, sinks, showers, shower plastified curtains, wash basins, WCs, dishes, fixtures and fittings and the like made of different materials like ceramic, vinyl, nowax vinyl, linoleum, melamine, glass, any plastics, plastified wood, metal, especially steel and chrome metal or any painted or varnished or sealed surface and the like. Surfaces also include household appliances including, but not limited to, refrigerators, freezers, washing machines, automatic dryers, ovens, microwave ovens, _. dishwashers and so on. The present composition is especially efficacious in the cleaning of ceramic, enamel, steel, plastic, glass surfaces found in kitchens, bathrooms and the like.

Although the inventors do not wish to be bound by any theory, it is believed that the non-abrasive effective cleaning action of the liquid cleaning composition is due to a reduced size of the microparticles, while the ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface may be attributed to the large surface area and to the low crystallinity degree of the microparticles, which features impart to the microparticles a highly indented and irregular outer surface.

La this regard, it is believed that a major role in imparting to the liquid cleaning composition the ability of being easily washed away and of rendering hydrophilic the cleaned surface is played by this elevated disorder of the outer surface of the microparticles at which the ions stoichiometry of the bulk portion of the particles is no longer maintained.

As a consequence of these structural characteristics, it is believed that the microparticles are capable of modifying the surface by adhering or in some way associating with the surface to be cleaned such that they preferably remain on the surface during and after the cleaning process. Such adhesion or association may be due for example to electrostatic interaction, hydrogen bonding or Van der Waals forces. The microparticles modify the surface by rendering it hydrophilic meaning that the contact angle (measured as will be explained later on) between water and the surface, after the surface has been treated with the polymer-containing composition is less than 33°, more preferably less than 30°, still more preferably, less than 25°.

For the purposes of the invention, the particle size of the solid inorganic microparticles can be measured according to known methods, such as, for example, by using transmission electron microscopy (TEM). For the purposes of the present description and of the claims which follow, the expression: crystallinity degree, is intended to indicate the percentage of the compound or compounds forming the microparticles present in the crystalline state.

For the purposes of the invention, the crystallinity degree can be measured according to known methods, such as, for example, by using X-ray diffraction analysis.

Within the framework of the definition given above, the crystallinity degree CD is measured according to the method reported by Z. E. Erkmen "The effect of heat treatment on the morphology o/D-Gun Sprayed Hydroxyapatite coatings", J. Biomed

Mater Res (Appl Biomaterial) 48;861-868, 1999.

For the purposes of the present description and of the claims which follow, except where otherwise indicated, all numerical values expressing parameters such as amounts, weights, temperatures, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include any combination of the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Carrier Medium

The carrier medium can form part of the liquid cleaning composition, or it can comprise the medium in which the microparticles are carried (or transported) for application to the hard surface.

For the purposes of the present invention, the carrier medium is contained in the liquid cleaning composition in an amount suitable to transport and/or solubilize the various ingredients described herein. Such amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the physical and chemical nature of the ingredients, the application technique of the cleaning composition, and the like.

Several non-limiting examples of types of carrier mediums are provided hereinbelow by way of explanation, and not by way of limitation. In one example, the liquid cleaning composition can be provided in the form of an aqueous liquid or gel in a container, and the liquid or gel can be poured, applied by means of a cloth or sponge or sprayed (if liquid) onto a hard surface. In such a case, the aqueous liquid or gel carrier in the container holding the coating composition may be

referred to herein as the "static carrier". When a liquid coating composition is sprayed onto the hard surface, the liquid droplets in the spray may be referred to herein as the "dynamic carrier" (the medium that transports the ingredients to the surface in order to contact the surface). The term "carrier", as used herein, includes both static and dynamic carriers.

Suitable carrier mediums include liquids. One suitable carrier medium is water, which can be distilled, deionized, or tap water. Water is valuable due to its low cost, availability, safety, and compatibility, hi certain embodiments in which the carrier medium is aqueous, it may be preferred that at least some of the aqueous carrier is purified beyond the treatment it received to convert it to tap water (that is, the tap water is post-treated, e. g., deionized or distilled). The purified water could comprise: all or part of the static carrier for the composition; all or part of the dynamic carrier; or, all or part of both. Other carrier mediums which may be used in combination with water are low molecular weight organic solvents that are highly soluble in water, e.g., ethanol, methanol, propanol, isopropanol and the like, and mixtures thereof. Low molecular weight alcohols can allow the treated hard surface to dry faster. The optional water soluble low molecular weight solvent can be used at a level of up to about 50% by weight, typically from about 0.1% to about 25% by weight, alternatively from about 2% to about 15% by weight, alternatively from about 5% to about 10%, by weight of the suitable carrier medium. Factors that need to consider when a high level of solvent is combined with the suitable carrier medium are odor, flammability, dispersancy of the microparticle and environment impact. Solid inorganic microparticles According to the invention, the liquid cleaning composition comprises solid inorganic microparticles having a particle size of from 0.5 to 5 μm, preferably from 0.5 to 1.5 μm. hi this way, the ability of the microparticles of reaching dirt and soil located in the tiniest scratches of the surface to be cleaned and the ability of the liquid cleaning

composition of exerting its cleaning action without affecting the surface integrity and its gloss are advantageously enhanced.

For the purposes of the present invention, the solid inorganic microparticles are contained in the liquid cleaning composition in an effective amount to provide one or more of the benefits described herein.

As used herein, "effective amount of the solid inorganic microparticles" refers to the quantity of microparticles of the present invention described herein necessary to achieve at least one of the desired cleaning action, ability of the cleaning composition to be rinsed away and hydrophilic characteristics of the cleaned surface in the specific composition. Such effective amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the particular microparticles used, the application technique of the cleaning composition, the specific composition of the cleaning composition, and the like. Preferably, the concentration of microparticles in the liquid cleaning compositions described herein is comprised between 0.1 and 60% by weight as a function of the application technique of the cleaning composition.

Thus, for example, a liquid cleaning composition that is to be applied to the hard surface by pouring or by means of a sponge or cloth may comprise from 5 to 50% by weight, more preferably from 10 to 40% by weight, of solid inorganic microparticles, whereas a liquid cleaning composition that is to be applied to the hard surface by spraying may comprise from 0.1 to 15% by weight, more preferably from 0.5 to 5% by weight, of solid inorganic microparticles in order not to clog the spraying device. According to a preferred embodiment of the invention, the solid inorganic microparticles of the liquid cleaning composition have a surface area of from 20 to 40 m ² /g.

In this way, the ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface may be advantageously enhanced.

For the purposes of the invention, the surface area of the microparticles can be measured according to known methods, such as, for example, by the BET method. In connection with this parameter, the inventors have observed that the average values of the surface area of the microparticles may vary within the aforementioned range as a function of the total amount of microparticles synthesized per each production batch, the higher values being more easily reached the smaller is the entity of the production batch. According to a preferred embodiment of the invention, the solid inorganic microparticles of the liquid cleaning composition have a crystallinity degree CD comprised between 25% and 35%. In this way, the ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface may be advantageously enhanced.

For the purposes of the invention, suitable solid inorganic microparticles are inorganic microparticles selected from phosphates, oxides, silicates, carbonates, hydroxides, and mixtures thereof.

In a preferred embodiment, the solid inorganic microparticles are inorganic microparticles selected from acid phosphates, calcium phosphates, hydroxyapatite, modified hydroxyapatite, alkaline earth metal phosphates, ammonium phosphates, brushite, monetite, feldspar, quartz, topaz, calcite, alumina, limonite, kimenite, ceramic, leucite, glass, taconite, silica sand, flint, vermiculite, fire clay, diaspore, bauxite, limestone, magnetite, hematite, and mixtures thereof.

In a particularly preferred embodiment, the solid inorganic microparticles are microparticles of a carbonate-substituted non-stoichiometric hydroxyapatite having the formula: Ca ₁₀ (Pθ ₄ ) ₆ - _y (CO ₃ ) _y+z (OH) _2-z wherein y is a number comprised between 0.065 and 0.9 and z is a number comprised between 0 and 0.32.

Most advantageously, the carbonate-substituted non-stoichiometric hydroxyapatite microparticles possess negatively ^" charged carbonate and phosphate moieties which enhances the ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface. Most advantageously, these technical effects are further enhanced by the carbonate ions incorporated in the apatite structure which contribute to lower the crystallinity degree of the microparticles consequent to the incorporation of these ions in the apatite structure. In this regard, it is to be observed that the carbonate ion can occupy two different sites in the hydroxyapatite structure: namely, it can partially substitute the OH-ion (site A) and/or the PO ₄ ^3" ion (site B). In the microparticles of the invention, carbonation preferably takes place at site B ₅ as this results in a reduction of the crystallinity with the consequent beneficial effect on the aforementioned ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface. In a preferred embodiment of the invention, the carbonate-substituted non- stoichiometric hydroxyapatite microparticles comprise from 1 to 15% by weight and, more preferably, from 1 to 10% by weight based on the total weight of the microparticles, of carbonate substituted into the hydroxyapatite structure. In this way, the aforementioned reduction of crystallinity of the microparticles may be optimized with the consequent beneficial effect on the ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface.

According to a preferred embodiment of the invention, the ratio A/B between the carbonate substitution at the hydroxyl site (A) and the carbonate substitution at the phosphate site (B) of the hydroxyapatite microparticles is comprised between 0.05 and 0.5 and, still more preferably, comprised between 0.18 and 0.33.

According to another preferred embodiment of the invention, the carbonate substitution at the phosphate site (B) of the hydroxyapatite is greater than or equal to 65% by weight

and, still more preferably, comprised between 90% and 100% by weight, of the total carbonate present in the hydroxyapatite.

These preferred patterns of carbonate substitution in the hydroxyapatite structure advantageously allow to decrease the crystallinity of the microparticles with the consequent beneficial effect on the ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface.

According to another preferred embodiment of the invention, the carbonate-substituted non-stoichiometric hydroxyapatite microparticles have a molar ratio Ca/P comprised between 1.6 and 1.9. hi this way, the rinsing ability of the liquid cleaning composition may be further enhanced.

For the purposes of the invention, suitable carbonate-substituted non-stoichiometric hydroxyapatite microparticles may be prepared by processes known in the art and disclosed, for example, by L. Rimondini, B. Palazzo, M. Iafisco, L. Canegallo, F. Demarosi, M. Merlo, N. Roveri, "The remineralizing effect of carbonate-hydroxyapatite nanocrystals on dentine", Materials Science Forum, VoIs. 539-543 (2007) pp. 602-605.

A preferred process for preparing carbonate-substituted non-stoichiometric hydroxyapatite microparticles comprises the steps of: a) preparing an aqueous solution or suspension comprising a Ca compound; b) forming nanoparticles of a carbonate-substituted hydroxyapatite by adding

PO ₄ ^" ions to the aqueous solution or suspension of step a) while simultaneously agitating the same over a time comprised between 30 minutes and 8 hours while maintaining said solution or suspension at a temperature lower than or equal to 60°C; c) agitating the suspension obtained from step b) over a time comprised between

1 and 8 hours at a temperature lower than or equal to 6O ⁰ C so as to cause the formation of non-stoichiometric hydroxyapatite microparticles; d) separating the microparticles from the suspension obtained from step c);

e) drying the wet solid microparticles thus obtained.

The aforementioned step a) of preparing an aqueous solution or suspension comprising a Ca compound may be carried out in any conventional manner, such as by dissolving or suspending the Ca compound in water. According to a preferred embodiment, the Ca compound is a calcium salt selected from the group comprising: calcium hydroxide, calcium carbonate, calcium acetate, calcium oxalate, calcium nitrate, and mixtures thereof.

Li this way, the cost of the process may advantageously be reduced since these Ca compounds are commodities readily available from the marked at a very low cost. Additionally, these Ca compounds are easily workable and stockable to the advantage of the manufacturing operations.

In the aforementioned process, step a) is preferably carried out in order to achieve a suspension of nanoparticles having a basic pH. Preferably, the aqueous solution or suspension of step a) has a pH comprised between 8 and 12. In the process of the invention, nanoparticles of carbonate-substituted hydroxyapatite are formed in step b) by adding PO ₄ ^3" ions to the aqueous solution or suspension of step a) and by simultaneously agitating this solution or suspension in order to capture the carbon dioxide present in the atmosphere and achieve the desired carbonate substitution at the phosphate site (B) of the hydroxyapatite compound being formed. In this way, the carbonate substitution may be advantageously carried out by simply agitating the solution or suspension for example by means of a mechanical stirrer. In an alternative embodiment, the required agitation of the solution or suspension may be achieved by bubbling air, a CO ₂ -containing gas or a mixture thereof into the liquid phase or by combining a mechanical stirring with a gas bubbling. The PO ₄ ^3" ions are added to the aqueous solution or suspension of step a) over a time which generally depends on the amount of the used phosphoric solution with respect to the amount of the basic, calcium solution or suspension, and which may be selected by those skilled in the art.

Preferably, step b) is carried out over a time comprised between 30 minutes and 2 hours in order to keep the reaction time and the operating costs as low as possible.

According to the invention, step b) is carried out while maintaining said solution or suspension at a temperature lower than or equal to 60 ⁰ C. The inventors have observed that in this way the crystallinity degree CD of the nanoparticles may be kept below the aforementioned maximum value of 50%.

In a preferred embodiment of the invention, step b) is carried out while maintaining said solution or suspension at a temperature lower than or equal to 4O ⁰ C and more preferably comprised between 25° and 4O ⁰ C. In this way, the crystallinity degree CD of the nanoparticles may be kept within the aforementioned preferred range of values (CD = 25-35%).

According to a preferred embodiment, step b) is carried out by adding, preferably dropwise, an aqueous solution including PO ₄ ^3" ions to the aqueous solution or suspension of step a). According to an alternative preferred embodiment, the aqueous solution including PO ₄ ^3" ions added in step b) may further comprise HCO ₃ ^" ions. hi this way, it may be possible to adjust to the proper extent the desired carbonate substitution at the phosphate site (B) of the hydroxyapatite compound being formed.

Within the framework of this preferred embodiment, the aforementioned aqueous solution including HCO ₃ ^" and PO ₄ ^3" ions may be prepared by bubbling air, CO ₂ or a mixture thereof through water to obtain a solution of carbonic acid and then adding

H ₃ PO ₄ thereto.

According to another alternative preferred embodiment, step b) may be carried out by simultaneously adding a first solution containing CO ₃ ^2" ions and a second solution containing PO ₄ ^3" ions to the aqueous solution or suspension of step a).

In a preferred embodiment, the process is carried out such that the suspension of microparticles obtained from step c) has a pH comprised between 7 and 8 and, more preferably, between 7 and 7.4.

In this way, the preparation process of the microparticles allows to produce a suspension which may be advantageously directly used as such or mixed with other ingredients in the formulation of effective liquid cleaning compositions with a remarkable simplification of the manufacturing operations of the compositions and a remarkable cost reduction.

In the process of the invention, step c) promotes the growth and aggregation of the nanoparticles of carbonate-substituted hydroxyapatite to form microparticles of the desired particle size. According a preferred embodiment of the invention, the microparticles obtained in this way are aggregate or clusters of nanoparticles as will be described in greater detail hereinbelow.

Preferably, step c) is accomplished by agitating the suspension obtained from step b) (during which mainly a nucleation of the nanoparticles is taking place) over a time of at least 2 hours at a temperature lower than or equal to 60 ⁰ C. Preferably, step c) is carried out over a time comprised between 2 and 24 hours and more preferably between 2 and 12 hours, as required by the circumstances in order to have a growing time of the microparticles sufficient to reach the desired size and in order to obtain a single phase.

In a preferred embodiment of the invention, step c) is carried out while mamtaining the suspension of microparticles at a temperature comprised between 25° and 40°C. In a preferred embodiment of the invention, step c) is carried out while mamtaining the suspension of microparticles at the same temperature of step b).

In this way, the process may be advantageously carried out with a simpler control and at a lower cost. In a preferred embodiment, the separation step d) is carried out by decantation, centrifugation or filtration using apparatuses and techniques well known to those skilled in the art.

In a preferred embodiment, the drying step e) is carried out by freezing the wet solid microparticles at a temperature lower than 0°C until reaching a constant weight.

Within the framework of this preferred embodiment, the drying step e) is preferably carried out by freeze-drying the wet solid microparticles at a temperature comprised between -20° and -50 ⁰ C, most preferably at about -40°C.

In a preferred embodiment, the process may also comprise the additional step f) of washing the separated solid microparticles with water or a basic solution prior to effecting the drying step e).

Advantageously, this additional washing step f) serves the useful function of removing any acid residues possibly absorbed or trapped by the microparticles. In additional embodiments of the invention, solid inorganic microparticles suitable for the purposes of the present invention are layered clay minerals and inorganic metal oxides.

The layered clay minerals suitable for use in the present invention include those in the geological classes of the smectites, the kaolins, the illites, the chlorites, the attapulgites and the mixed layer clays. Typical examples of specific clays belonging to these classes are the smectites, kaolins, illites, chlorites, attapulgites and mixed layer clays. Smectites, for example, include montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, volchonskoite and vermiculite. Kaolins include kaolinite, dickite, nacrite, antigorite, anauxite, halloysite, indellite and chrysotile. Illites include bravaisite, muscovite, paragonite, phlogopite and biotite. Chlorites include corrensite, penninite, donbassite, sudoite, pennine and clinochlore. Attapulgites include sepiolite and polygorskyte. Mixed layer clays include allevardite and vermiculitebiotite. Variants and isomorphic substitutions of these layered clay minerals offer unique applications. The layered clay minerals of the present invention may be either naturally occurring or synthetic. An example of one embodiment of the present invention uses natural or synthetic hectorites, montmorillonites and bentonites. Another embodiment uses the hectorites clays commercially available.

The inorganic metal oxides of the present invention may be silica-or alumina-based microparticles that are naturally occurring or synthetic. Aluminum can be found in many naturally occurring sources, such as kaolinite and bauxite. The naturally occurring sources of alumina are processed by the Hall process or the Bayer process to yield the desired alumina type required.

Various forms of alumina are commercially available in the form of Gibbsite, Diaspore, and Boehmite.

Natural clay minerals typically exist as layered silicate minerals and less frequently as amorphous minerals. A layered silicate mineral has SiO ₄ tetrahedral sheets arranged into a two-dimensional network structure. A 2: 1 type layered silicate mineral has a laminated structure of several to several tens of silicate sheets having a three layered structure in which a magnesium octahedral sheet or an aluminum octahedral sheet is sandwiched between two sheets of silica tetrahedral sheets.

A sheet of an expandable layer silicate has a negative electric charge, and the electric charge is neutralized by the existence of alkali metal cations and/or alkaline earth metal cations.

For the purposes of the invention, the microparticles described above may be prepared by processes known in the art.

In a preferred embodiment, the solid inorganic microparticles and most preferably the microparticles of the carbonate-substituted non-stoichiometric hydroxyapatite mentioned above, are aggregates or "clusters" of inorganic nanoparticles.

For the purposes of the present description and of the claims which follow, the term: nanoparticle, is used to indicate a particle having a size generally below lμm.

In this way, the microparticles are characterized by an elevated disorder of their outer surface which is believed to account for to the enhanced ability of the liquid cleaning composition of being easily washed away and of rendering hydrophilic the cleaned surface.

Also, this aggregation of smaller particles is deemed to contribute to reducing the abrasive action on the surface to be cleaned thanks to their tendency to disgregate if subjected to the mechanical rubbing action exerted during cleaning. In the preferred embodiment in which the solid inorganic microparticles are microparticles including charged moieties, such as in the case of carbonate-substituted non-stoichiometric hydroxyapatite, the liquid cleaning composition of the invention achieves the additional advantage that the nanoparticles are aggregated in clusters without the need of any binding agent but are simply reversibly kept together by electrostatic interaction, hydrogen bonding or Van der Waals forces. Preferably, the nanoparticles forming the aggregates or "clusters" have a particle size ranging from 5 to 200 nm.

In a particularly preferred embodiment, the aforementioned aggregates are aggregates of nanoparticles, most preferably aggregates of nanoparticles of a carbonate-substituted non-stoichiometric hydroxyapatite, having: a) a length L ranging from 20 to 200 nm and a width W ranging from 5 to 30 nm; and b) an aspect ratio AR comprised between 2 and 40, the aspect ratio being defined as

AR = IVW.

For the purposes of the present description and of the claims which follow, the term: length L of the nanoparticles, is intended to mean the dimension of the nanoparticle as measured along the major axis thereof, while the term: width W of the nanoparticles, is intended to mean the dimension of the nanoparticle as measured along the minor axis thereof.

For the purposes of the invention, the length L and the width W of the nanoparticles can be measured according to known methods, such as, for example, by using transmission electron microscopy (TEM).

According to a preferred embodiment of the invention, the solid inorganic nanoparticles forming the aforementioned aggregates, and preferably the carbonate-substituted non- stoichiometric hydroxyapatite nanoparticles, have a substantially acicular or platelet

shape. having a length L comprised between 50 and 150 nm and a width W comprised between 5 and 20 nm.

Preferably, furthermore, the nanoparticles have a thickness T as measured by the TEM technique ranging from 2 to 15 nm. The aspect ratio AR of the nanoparticles is preferably comprised between 2 and 16 and, still more preferably, between 5 and 10.

In this way, the ability of the liquid cleaning composition of being easily washed away and of imparting hydrophilic characteristics to the cleaned surface may be advantageously further enhanced. According to an additional preferred embodiment, the liquid cleaning composition of the invention may further include additional solid inorganic microparticles, selected from the materials disclosed above, and having a particle size higher than 5 μm and preferably comprised between 5 and 25 μm. These additional solid inorganic microparticles need not comply with the aforementioned requirements of surface area and crystallinity degree and may be added to regulate the content of abrasive particles contained in the composition to optimal values reducing at the same time the overall cost of the liquid cleaning composition. The concentration of these additional solid inorganic microparticles in the liquid cleaning compositions described herein should be suitably selected to such low values as not to trigger the noted problems of surface damage and progressive loss of surface gloss which affect the liquid cleaning compositions of the prior art. To this end, the concentration of these additional solid inorganic microparticles in the liquid cleaning compositions described herein is preferably comprised between 0.1 and 15% by weight, more preferably, between 0.5 and 5% by weight, as a function of the concentration in the cleaning composition of the above-described solid inorganic microparticles of the invention. .

Preferably, furthermore, the weight ratio between the additional solid inorganic microparticles and the solid inorganic microparticles of the invention is maintained at a

value lower than 0.3 and preferably lower than 0.15 in order not to trigger the noted problems of surface damage and progressive loss of surface gloss which affect the liquid cleaning compositions of the prior art.

Surfactants The presence of a surfactant in the liquid cleaning compositions of the present invention have been found to not only improve the cleaning performance, but also facilitate the dispersion of the solid inorganic microparticles and other adjunct ingredients such as antimicrobial actives and perfumes.

Most advantageously, therefore, the liquid cleaning composition of the invention may do without the suspending systems usually required in the compositions of the prior art to keep the solid abrasive in a stable suspension.

Suitable surfactant useful in the present invention is surfactant selected from the group consisting of anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, zwitterionic surfactants, and mixtures thereof. For the purposes of the present invention, the surfactant is contained in the liquid cleaning composition in an effective amount to provide one or more of the benefits described herein.

As used herein, "effective amount of the surfactant" refers to the quantity of surfactant described herein necessary to achieve at least one of the desired cleaning action, ability of dispersing the solid inorganic microparticles and other optional adjunct ingredients.

Such effective amount may be readily ascertained by one of ordinary skill in the art and is based on many factors, such as the specific composition of the cleaning composition, the application technique of the cleaning composition, and the like.

The concentration of surfactant in the liquid cleaning compositions described herein is preferably comprised between 0.1 and 40% by weight as a function of the application technique of the cleaning composition.

Thus, for example, a liquid cleaning composition that is to be applied to the hard surface to be cleaned by pouring or by means of a sponge or cloth may preferably comprise

firom 0.3 to 20% by weight, more preferably from 1.5 to 10% by weight, of surfactant, whereas a liquid cleaning composition that is to be applied to the hard surface to be cleaned by spraying may preferably comprise from 0.5 to 10% by weight, more preferably from 1.0 to 6.0% by weight, of surfactant in order to reduce the formation of foam, enhance the rinsability characteristics and reduce costs.

Suitable anionic surfactants for use in the compositions herein include water-soluble salts or acids of the formula ROSO ₃ M wherein R preferably is a C ₇ -C ₂₄ hydrocarbyl, preferably an alkyl or hydroxyalkyl having a C ₇ -C ₂₄ alkyl component, more preferably a C ₁₂ -C ₁₈ alkyl or hydroxyalkyl, and M is H or a cation, e.g., an alkali metal cation (e.g., sodium, potassium, lithium), or ammonium or substituted ammonium (e.g., methyl-, dimethyl-, and trimethyl ammonium cations and quaternary ammonium cations, such as tetramethyl-ammonium and dimethyl piperdinium cations and quaternary ammonium cations derived from alkylamines such as ethylamine, diethylarnine, triethylamine, and mixtures thereof, and the like). Other suitable anionic surfactants for use herein are water-soluble salts or acids of the formula RO(A) _1n SOaM wherein R is an unsubstituted C ₁₀ -C ₂₄ alkyl or hydroxyalkyl group having a C ₁₀ -C ₂₄ alkyl component, preferably a C ₁₂ -C _2O alkyl or hydroxyalkyl, more preferably C ₁₂ -C ₁₈ alkyl or hydroxyalkyl, A is an ethoxy or propoxy unit, m is a number greater than zero, typically between about 0.5 and about 6, more preferably between about 0.5 and about 3, and M is H or a cation which can be, for example, a metal cation (e.g., sodium, potassium, lithium, calcium, magnesium, etc.), ammonium or substituted-ammonium cation. Alkyl ethoxylated sulfates as well as alkyl propoxylated sulfates are contemplated herein. Specific examples of substituted ammonium cations include methyl-, dimethyl-, trimethyl-ammonium and quaternary ammonium cations, such as tetramethyl-ammonium, dimethyl piperdinium and cations derived from alkanolamines such as ethylamine, diethylamine, triethylamine, mixtures thereof, and the like.

Exemplary surfactants are C ₁₂ -C ₁₈ alkyl polyethoxylate (1.0) sulfate, C ₁₂ -C ₁₈ E(LO)M),

C ₁₂ -C ₁₈ alkyl polyethoxylate (2.25) sulfate, C ₁₂ -C ₁₈ E(2.25)M), C ₁₂ -C ₁₈ alkyl polyethoxylate (3.0) sulphate, C ₁₂ -C ₁₈ E(3.0), and C ₁₂ -C ₁₈ alkyl polyethoxylate (4.0) sulfate C ₁₂ -C ₁₈ E(4.0)M), wherein M is conveniently selected from sodium and potassium. Other particularly suitable anionic surfactants for use herein are alkyl sulphonates including water-soluble salts or acids of the formula RSO ₃ M wherein R is a C ₆ -C ₂₂ linear or branched, saturated or unsaturated alkyl group, preferably a C ₁ O-Ci ₆ alkyl group and more preferably a C ₁₂ -C ₁₆ alkyl group, and M is H or a cation, e.g., an alkali metal cation (e.g., sodium, potassium, lithium), or ammonium or substituted ammonium (e.g., methyl-, dimethyl-, and trimethylammonium cations and quaternary ammonium cations, such as tetramethylammonium and dimethyl piperdinium cations and quaternary ammonium cations derived from alkylamines such as ethylamine, diethylamine, triethylamine, and mixtures thereof, and the like). Suitable alkyl aryl sulphonates for use herein include water-soluble salts or acids of the formula RSO ₃ M wherein R is an aryl, preferably a benzyl, substituted by a C ₆ -C ₂₂ linear or branched saturated or unsaturated alkyl group, preferably a C ₁₀ -C ₁₈ alkyl group and more preferably a C ₁₂ -C ₁₆ alkyl group, and M is H or a cation, e.g., an alkali metal cation (e.g., sodium, potassium, lithium, calcium, magnesium, etc) or ammonium or substituted ammonium (e.g., methyl-, dimethyl-, and τrimethyl ammonium cations and quaternary ammonium cations, such as tetramethyl-ammonium and dimethyl piperdinium cations and quaternary ammonium cations derived from alkylamines such as ethylamine, diethylamine, triethylamine, and mixtures thereof, and the like). The alkylsulfonates and alkyl aryl sulphonates for use herein include primary and secondary alkylsulfonates and primary and secondary alkyl aryl sulphonates. By "secondary C ₆ -C ₂₂ alkyl or C ₆ -C ₂₂ alkyl aryl sulphonates", it is meant herein that in the formula as defined above, the SO ₃ M or aryl-SO ₃ M group is linked to a carbon atom of the alkyl chain being placed between two other carbons of the said alkyl chain (secondary carbon atom).

Other anionic surfactants useful for detersive purposes can also be used herein. These can include salts (including, for example, sodium, potassium, ammonium, and substituted ammonium salts such as mono-, di- and triethanolamine salts) of soap, of natural fatty acids, such as coconut oil, C ₈ -C ₂₄ olefinsulfonates, sulfonated polycarboxylic acids prepared by sulfonation of the pyrolyzed product of alkaline earth metal citrates, C ₈ -C ₂₄ alkylpolyglycolethersulfates (containing up to 10 moles of ethylene oxide); alkyl ester sulfonates such as C ₁₄ -C ₁₆ methyl ester sulfonates; acyl glycerol sulfonates, fatty oleyl glycerol sulfates, alkyl phenol ethylene oxide ether sulfates, paraffin sulfonates, alkyl phosphates, isethionates such as the acyl isethionates, N-acyl taurates, alkyl succinamates and sulfosuccinates, monoesters of sulfosuccinate (especially saturated and unsaturated C ₁₂ -C ₁₈ monoesters) diesters of sulfosuccinate (especially saturated and unsaturated C ₆ -C ₁₄ diesters), ethoxylated sulfosuccinates, sulfates of alkyl polysaccharides such as the sulfates of alkylpolyglucoside (the nonionic nonsulfated compounds being described below), branched primary alkyl sulfates, alkyl polyethoxy carboxylates such as those of the formula RO(CH ₂ CH ₂ O)I _C CH ₂ OOO-M ⁺ wherein R is a C ₈ -C ₂₂ alkyl, k is an integer from 0 to 10, and M is a soluble salt-forming cation.

Other particularly suitable anionic surfactants for use herein are alkyl carboxylates and alkyl alkoxycarboxylates having from 4 to 24 carbon atoms in the alkyl chain, preferably from 8 to 18 and more preferably from 8 to 16, wherein the alkoxy is propoxy and/or ethoxy and preferably is ethoxy at an alkoxylation degree of from 0.5 to 20, preferably from 5 to 15.

Preferred alkylalkoxycarboxylate for use herein is sodium laureth 11 carboxylate (i.e., RO(C ₂ -H ₄ O) ₁₀ -CH ₂ COONa, with R= C ₁₂ -C ₁₄ ). Suitable amphoteric surfactants for use herein include amine oxides having the following formula R ₁ R ₂ R ₃ NO wherein each of R ₁ , R ₂ and R ₃ is independently a saturated substituted or unsubstituted, linear or branched hydrocarbon chain of from 1 to 30 carbon atoms. Preferred amine oxide surfactants to be used according to the present

invention are amine oxides having the following formula R ₁ R ₂ R ₃ NO wherein Ri is a hydrocarbon chain comprising from 1 to 30 carbon atoms, preferably from 6 to 20, more preferably from 8 to 16, most preferably from 8 to 12, and wherein R ₂ and R ₃ are independently substituted or unsubstituted, linear or branched hydrocarbon chains comprising from 1 to 4 carbon atoms, preferably from 1 to 3 carbon atoms, and more preferably are methyl groups. R ₁ may be a saturated, substituted or unsubstituted linear or branched hydrocarbon chain. Suitable amine oxides for use herein are for instance natural blend C ₈ -C ₁₀ amine oxides as well as C ₁₂ -Ci ₆ amine oxides commercially available from Hoechst. Suitable zwitterionic surfactants for use herein contain both a cationic hydrophilic group, i.e., a quaternary ammonium group, and anionic hydrophilic group on the same molecule at a relatively wide range of pH's. The typical anionic hydrophilic groups are carboxylates and sulfonates, although other groups like sulfates, phosphonates, and the like can be used. A generic formula for the zwitterionic surfactants to be used herein is : R ₁ -N ⁺ (R ₂ )(R ₃ )R ₄ X ^" wherein R ₁ is a hydrophobic group; R ₂ is hydrogen, C ₁ -C ₆ alkyl, hydroxy alkyl or other substituted Ci-C ₆ alkyl group; R ₃ is Ci-C ₆ alkyl, hydroxy alkyl or other substituted C ₁ - C ₆ alkyl group which can also be joined to R ₂ to form ring structures with the N, or a C ₁ -C ₆ carboxylic acid group or a C ₁ -C ₆ sulfonate group; R ₄ is a moiety joining the cationic nitrogen atom to the hydrophilic group and is typically an alkylene, hydroxy alkylene, or polyalkoxy group containing from 1 to 10 carbon atoms; and X is the hydrophilic group which is a carboxylate or sulfonate group.

Preferred hydrophobic groups R ₁ are aliphatic or aromatic, saturated or unsaturated, substituted or unsubstituted hydrocarbon chains that can contain linking groups such as amido groups, ester groups. More preferred R ₁ is an alkyl group containing from 1 to 24 carbon atoms, preferably from 8 to 18, and more 20 preferably from 10 to 16. These simple alkyl groups are preferred for cost and stability reasons. However, the hydrophobic group Rl can also be an amido radical of the formula R ₂ -C(O)-NH-

(C(R _b )2) _m , wherein R _a is an aliphatic or aromatic, saturated or unsaturated, substituted or unsubstituted hydrocarbon chain, preferably an alkyl group containing from 8 up to 20 carbon atoms, 25 preferably up to 18, more preferably up to 16, R _b is selected from the group consisting of hydrogen and hydroxy groups, and m is from 1 to 4, preferably from 2 to 3, more preferably 3, with no more than one hydroxy group in any (C(R _b )2) moiety. Preferred R ₂ is hydrogen, or a C ₁ -C ₃ alkyl and more preferably methyl. Preferred R ₃ is a C ₁ -C ₄ carboxylic acid group or C ₁ -C ₄ sulfonate group, or a C ₁ -C ₃ alkyl and more preferably methyl. Preferred R ₄ is (CH ₂ ) _n wherein n is an integer from 1 to 10, preferably from 1 to 6, more preferably is from 1 to 3. Examples of particularly suitable alkyldimethyl betaines include coconut-dimethyl betaine, lauryl dimethyl betaine, decyl dimethyl betaine, 2-(N-decyl-N,N-dimethyl- ammonia)acetate, 2-(N-coco-N,N-dimethylammonio)acetate, myristyl dimethyl betaine, palmityl dimethyl betaine, cetyl dimethyl betaine, stearyl dimethyl betaine. For example Coconut dimethyl betaine is commercially available from Seppic under the trade name of Amonyl 265®. Lauryl betaine is commercially available from Albright & Wilson under the trade name Empigen BB/L®.

Examples of amidobetaines include cocoamidoethylbetaine, cocoamidopropyl betaine or C _1O -C ₁₄ fatty acylamidopropylene(hydropropylene)sulfobetaine. For example C ₁₀ -C ₁₄ fatty acylamidopropylene(hydropropylene)sulfobetaine is commercially available from Sherex Company under the trade name "Varion CAS® sulfobetaine".

A further example of betaine is lauryl-imino-dipropionate commercially available from Rhone-Poulenc under the trade name Mirataine H2C-HA®.

Suitable cationic surfactants for use herein include derivatives of quaternary ammonium, phosphonium, imidazolium and sulfonium compounds. Preferred cationic surfactants for use herein are quaternary ammonium compounds wherein one or two of the hydrocarbon groups linked to nitrogen are a saturated, linear or branched alkyl group of 6 to 30 carbon atoms, preferably of 10 to 25 carbon atoms, and more preferably of 12 to 20 carbon atoms, and wherein the other hydrocarbon groups (i.e. three when one

hydrocarbon group is a long chain hydrocarbon group as mentioned hereinbefore or two when two hydrocarbon groups are long chain hydrocarbon groups as mentioned hereinbefore) linked to the nitrogen are independently substituted or unsubstituted, linear or branched, alkyl chain of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon atoms, and more preferably are methyl groups.

Amongst the nonionic surfactants, alkoxylated nonionic surfactants are suitable for use herein. Such alkoxylated nonionic are preferably alkoxylated hydrocarbons, such as alkoxylated terpene, or alkoxylated alcohols having a carbon chain containing from 8 to 20 carbon atoms, more preferably from 10 to 18 carbon atoms and most preferably from 10 to 15 carbon atoms. The alkoxylation may be provided by ethoxylate, propoxylate or butoxylate groups, preferably ethoxylate groups. In a preferred aspect the ethoxylated alcohol comprises from 0.5 to 20, more preferably from 2 to 10, most preferably from 4 to 6 ethoxy groups. Suitable capped alkoxylated nonionic surfactants for use herein are according to the formula:

Rl(O-CH ₂ -CH ₂ V(OR ₂ VO-R ₃ wherein R ₁ is a C ₈ -C ₂₄ linear or branched alkyl or alkenyl group, aryl group, alkylaryl group, preferably R ₁ is a C ₈ -C ₁₈ alkyl or alkenyl group, more preferably a C _1O -C ₁₅ alkyl or alkenyl group, even more preferably a C ₁₀ -C ₁₅ alkyl group; wherein R ₂ is a C ₁ -C ₁₀ linear or branched alkyl group, preferably a C ₂ -C ₁₀ linear or branched alkyl group, wherein R ₃ is a C ₁ -C ₁₀ alkyl or alkenyl group, preferably a C ₁ -C ₅ alkyl group, more preferably methyl; and wherein n and m are integers independently ranging in the range of from 1 to 20, preferably from 1 to 10, more preferably from 1 to 5; or mixtures thereof. These surfactants are commercially available from BASF under the trade name Plurafac®, from HOECHST under the trade name Genapol® or from ICI under the trade name Symperonic®. Preferred capped nonionic alkoxylated surfactants of the above formula are those commercially available under the trade name Genapol® L 2.5

NR from Hoechst, and Plurafac® from BASF.

In another preferred alternative embodiment suitable surfactants include the alkyl polysaccharide surfactants. The alkyl polysaccharide surfactants, have a hydrophobic group containing from 8 to 20 carbon atoms, preferably from 10 to 18 carbon atoms, and a polysaccharide hydropbilic group containing from 1.5 to 10, preferably from 1.5 to 4 saccharide units. Suitable saccharide units include galactoside, glucoside, fructoside, glycosyl, fructosyl and/or galactosyl. Mixtures of saccharide units may be used in the alkyl polysaccharide. Typical hydrophobic groups include alkyl groups, either saturated or nonsaturated, branched or unbranched containing from 6 to 20, preferably from 8 to 18 carbon atoms. Preferably the alkyl group is a linear, saturated alkyl group. The alkyl group can contain up to 3 hydroxy groups and/or the polyalkoxide chain can contain up to 30, preferably less than 10 alkoxide groups. Suitable alkyl polysaccharides are octyl, decyl, dodecyl, tetradcyl, pentadecyl, hexadecyl and actadecyl, di-, tri-, terra-, penta- and hexa-glucosides, lactosides, fructosides, fructosyls, lactosyls, glucosyls, galactosyls, and mixtures thereof.

Other suitable surfactants include silicone surfactants such as organsilane or organosiloxane. Preferably the silicone surfactants have molecular weight of from 600 to 10000, more preferably from 900 to 6000, most preferably about 3000. Such compounds are well known in the art, examples of which can be found in for example US 3 299 112, US 4 311 695, US 4 782 095 the disclosures of which are incorporated herein by reference. Suitable siloxane oligomers are described in US 4 005 028. Suitable silicone surfactants include poly siloxane polyethylene glycol copolymers, polyalkylene oxide-modified polydimethylsiloxane copolymers. Other suitable surfactants include the fiuorosurfactants which comprise a hydrophilic and a hydrophobic section. The hydrophilic section comprises an alkyl group having from 2 to 12 carbons and an ester, sulfonate or carboxylate moiety. The hydrophobic section is fluorinated. Preferred fiuorosurfactants include alkyl fluorocarboxylates for example ammonium perfluroalkyl carboxylate and potassium fluroalkyl carboxylate. A

particularly suitable fluorosurfactants is an aqueous mixture of potassium fluoroalkyl carboxylate and has from 40-44% fluoroalkyl carboxylate having 8 carbon atoms in the alkyl chain, from 1-5% fluoroalkyl carboxylates having 6 carbon atoms in the alkyl chain, from 1-5% fluoroalkyl carboxylates having 4 carbon atoms in the alkyl chain, from 1-3% fluoroalkyl carboxylates having 7 carbon atoms in the alkyl chain and from 0.1-1% fluoroalkyl carboxylates having 5 carbon atoms in the alkyl chain. In a preferred aspect of the present invention the surfactant is a system comprising at least one anionic surfactant in combination with a non ionic surfactant. Particularly preferred anionic surfactants are the alkyl sulfates and the salts of natural fatty acids surfactants. Particularly preferred non ionic surfactants are the alkoxylated hydrocarbons, such as alkoxylated terpene.

In another preferred aspect of the present invention the surfactant is a system comprising at least one non ionic surfactant. Particularly preferred non ionic surfactants are alkoxylated hydrocarbons, such as alkoxylated terpene, and alkoxylated alcohols such as Laureth-4 (ethoxylated dodecyl alcohol). Optional ingredients

The liquid cleaning compositions described herein may comprise a variety of optional ingredients depending on the technical benefit required and the surface treated. Suitable optional ingredients for use herein can be selected from anti-resoiling ingredients, solvents, pH adjusting agents, rheology regulators, perfumes and minor ingredients such as colorants, preservatives and/or disinfectants. Suitable amounts of these optional ingredients may be easily selectable by those skilled in the art as a function of the specific characteristics to be imparted to the liquid cleaning composition. Anti-resoiling ingredients

In one preferred embodiment the composition comprises one or more anti-resoiling ingredients.

For the purposes of the present invention, the anti-resoiling ingredients are contained in

the liquid cleaning composition in an effective amount to provide one or more of the benefits described herein.

As used herein, "effective amount of the anti-resoiling ingredient" refers to the quantity of this ingredient necessary to impart anti-resoling properties to the cleaned surface thanks to the film-forming action of this ingredient.

Such effective amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the particular anti-resoiling ingredient used, the application technique of the cleaning composition, the specific composition of the cleaning composition, and the like. The concentration of the anti-resoiling ingredients in the liquid cleaning compositions described herein is preferably comprised between 0.1 and 2% by weight, more preferably between 0.25% and 1.5% by weight, as a function of the application technique of the cleaning composition. Suitable anti-resoiling ingredients include those well known to those skilled in the art, amongst which include polyalkoxylene glycol diesters, vinylpyrrolidone homopolymers or copolymers, polysaccharide polymers, polyalkoxylene glycols, mono- or di-capped polyalkoxylene glycols, as defined hereinafter, or a mixture thereof. Suitable vinylpyrrolidone homopolymers for use herein are homopolymers of N- vinylpyrrolidone ("PVP") having an average molecular weight of from 1,000 to 100,000,000, preferably from 2,000 to 10,000,000, more preferably from 5,000 to 1,000,000, and most preferably from 50,000 to 500,000.

Suitable copolymers of vinylpyrrolidone for use herein include copolymers of N- 15 vinylpyrrolidone and alkylenically unsaturated monomers or mixtures thereof. The alkylenically unsaturated monomers of the copolymers herein include unsaturated dicarboxylic acids such as maleic acid, chloromaleic acid, fumaric acid, itaconic acid, citraconic acid, phenylmaleic acid, aconitic acid, acrylic acid, and vinyl acetate. Any of the anhydrides of the unsaturated acids may be employed, for example acrylate, methacrylate. Aromatic monomers like styrene, sulphonated styrene, alpha-methyl

styrene, vinyl toluene, t-butyl styrene and similar well known monomers may be used.

Other suitable polymers for used herein are the polysaccharide polymers including substituted cellulose materials like carboxymethylcellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxymethyl cellulose, succinoglycan and naturally occurring polysaccharide polymers like xanthan gum, guar gum, locust bean gum, tragacanth gum or derivatives thereof, or mixtures thereof.

Particularly preferred polysaccharide polymers to be used in the liquid cleaning composition disclosed herein are xanthan gum and derivatives thereof.

Suitable additional anti-resoiling ingredients for use herein further include alkyl ether glycols, polyalkoxylene glycols, mono- and dicapped polyalkoxylene glycols or a mixture thereof, as defined herein after.

Suitable alkyl ether glycols for use herein are according to the following formula R ₁ -

(CH ₂ -CHR ₂ O) _n -H.

Suitable polyalkoxylene glycols for use herein are according to the following formula HO-(CH ₂ -CHR ₂ O) _n -H.

Suitable monocapped polyalkoxylene glycols for use herein are according to the following formula R ₁ -O-(CH ₂ -CHR ₂ O) _n -H.

Suitable dicapped polyalkoxylene glycols for use herein are according to the formula

R ₁ -O-(CH ₂ -CHR ₂ O) _n -R ₃ In these formulas, the substituents R ₁ and R ₃ each independently are substituted or unsubstituted, saturated or unsaturated, linear or branched hydrocarbon chains having from 1 to 30 carbon atoms, or amino bearing linear or branched, substituted or unsubstituted hydrocarbon chains having from 1 to 30 carbon atoms, R ₂ is hydrogen or a linear or branched hydrocarbon chain having from 1 to 30 carbon atoms, and n is an integer greater than 0.

Particularly preferred alkyl ether glycol to be used in the liquid cleaning composition disclosed herein is butyl glycol.

Solvents

The compositions described herein may further optionally comprise one or more solvents.

For the purposes of the present invention, the solvents are contained in the liquid cleaning composition in an effective amount to provide one or more of the benefits described herein.

As used herein, "effective amount of the solvents" refers to the quantity of this ingredient necessary to solubilize the soil or dirt removed from the surface preventing its redeposition on the cleaned surface.

Such effective amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the particular solvents used, the application technique of the cleaning composition, the specific composition of the cleaning composition, and the like.

Advantageously, the solvents are contained in the liquid cleaning composition also exert the useful function of stabilizing the suspension of microparticles present therein. The concentration of the solvents in the liquid cleaning compositions described herein is preferably comprised between 0.1 and 5% by weight as a function of the application technique of the cleaning composition.

Thus, for example, a liquid cleaning composition that is to be applied to the hard surface by pouring or by means of a sponge or cloth may comprise from 1.0 to 5% by weight, more preferably from 1.5 to 2.5% by weight, of one or more solvents, whereas a liquid cleaning composition that is to be applied to the hard surface by spraying may comprise from 0.75 to 5% by weight, more preferably from 1.0 to 2.5% by weight, of one or more solvents.

Solvents for use herein include all those known to those skilled in the art. Suitable solvents for use herein include ethers and diethers having from 4 to 14 carbon atoms, preferably from 6 to 12 carbon atoms, and more preferably from 8 to 10 carbon atoms, glycols, alkylated or alkoxylated glycols, alkoxylated aromatic alcohols, aromatic alcohols, aliphatic branched alcohols, alkoxylated aliphatic branched alcohols,

alkoxylated linear C ₁ -C ₅ alcohols, linear C ₁ -C ₅ alcohols, C ₈ -C ₁₄ alkyl and cycloalkyl hydrocarbons and halohydrocarbons, C ₆ -C ₁₆ glycol ethers, and mixtures thereof. Preferred solvents among the above-identified ones are selected from dodecaneglycol, propanediol, methoxy octadecanol, ethoxyethoxyethanol, benzoxyethanol, benzoxypropanol, benzyl alcohol, 2-ethylbutanol, 2-methylbutanol, 1- methylpropoxyethanol, 2-methyl butoxyethanol, butoxy propoxy propanol (n-BPP), butoxyethanol, butoxypropanol, ethoxyethanol, methanol, ethanol, propanol, butyl diglycol ether (BDGE), butyltriglycol ether, ter-amilic alcohol, or mixtures thereof. pH adjusting agents In the embodiment of the present invention the liquid cleaning compositions are preferably formulated at basic pH range, typically from 10 to 12.

Most advantageously, this basic pH allows to achieve two beneficial technical effects: enhance the degreasing action of the liquid cleaning compositions thereby enhancing the cleaning efficacy of the same and stabilize the suspension of microparticles, especially if the latter are hydroxyapatite microparticles, thereby enhancing the stability of the liquid cleaning compositions.

To this end, the liquid cleaning compositions may further comprise an effective amount of a suitable compound or a combination of compounds adapted to regulate the pH of the composition to such range of values. As used herein, "effective amount of the pH adjusting agent" refers to the quantity of this ingredient necessary to achieve the desired pH value of the liquid composition. Such effective amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the particular pH adjusting agents used, the application technique of the cleaning composition, the specific composition of the cleaning composition, and the like.

The concentration of the pH adjusting agents in the liquid cleaning compositions described herein is preferably comprised between 2 and 5% by weight, more preferably between 2.5 and 3.5% by weight, as a function of the application technique of the

cleaning composition. pH adjusting agents for use herein include all those known to those skilled in the art.

Suitable pH adjusting agents for use herein include inorganic bases, such as sodium hydroxide, potassium hydroxide, phosphates, such as potassium diphosphates, carbonates, such as sodium carbonate, or any other compound or mixture of compounds known to those skilled in the art and suitable to achieve the desired pH value of the liquid composition.

Rheology regulators

The compositions described herein may further optionally comprise one or more rheology regulators.

For the purposes of the present invention, the rheology regulators are contained in the liquid cleaning composition in an effective amount to provide one or more of the benefits described herein.

As used herein, "effective amount of the rheology regulators" refers to the quantity of this ingredient necessary to regulate the rheology characteristics of the liquid cleaning composition, such as for example viscosity and thixotropicity, as a function of the application techniques.

Such effective amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the particular rheology regulators used, the application technique of the cleaning composition, the specific composition of the cleaning composition, and the like.

In the embodiment of the present invention the liquid cleaning compositions are preferably formulated at a viscosity comprised between 2000 and 30000 cps at 20 ⁰ C, and more preferably, between 6000 and 10000 cps at 20 ⁰ C as a function of the application technique of the cleaning composition.

The concentration of the rheology regulators in the liquid cleaning compositions described herein is preferably comprised between 0.1 and 2% by weight as a function of the application technique of the cleaning composition.

Thus, for example, a liquid cleaning composition that is to be applied to the hard surface by pouring or by means of a sponge or cloth may comprise from 0.25 to 1.5% by weight, more preferably from 0.3 to 0.8% by weight, of one or more rheology regulators, whereas a liquid cleaning composition that is to be applied to the hard surface by spraying may comprise from 0.1 to 3.0% by weight, more preferably from 0.25 to 1.5% by weight, of one or more rheology regulators.

Rheology regulators for use herein include all those known to those skilled in the art. Suitable rheology regulators for use herein include thickeners, adapted to adjust the viscosity of the composition, as well as thixotroping agents, adapted to impart suitable thixotropic properties to the composition.

Suitable thickening agents are those known in the art. Examples of thickening agents include gum-type polymers (e.g. xanthan gum), polyvinyl alcohol and derivatives thereof, cellulose and derivatives thereof and polycarboxylate polymers. In a particularly preferred embodiment of the present invention the thickening agent comprises a polymeric sulfonic acid, gum-type polymer or a polycarboxylate polymer. The gum-type polymer may be selected from the group consisting of polysaccharide hydrocolloids, xanthan gum, guar gum, succinoglucan gum, Cellulose, derivatives of any of the above, and mixtures thereof, hi a preferred aspect of the present invention the gum-type polymer is a xanthan gum or derivative thereof. The polycarboxylate polymer can be a homo or copolymer of monomer units selected from acrylic acid, methacrylic acid, maleic acid, malic acid, maleic anhydride. Suitable polymers have molecular weight in the range of from 10,000 to 100,000,000 most preferably 1,000,000 to 10,000,000. Particularly preferred examples of these thickening agents are polymeric sulfonic acid, xanthan gum and cross-linked polycarboxylate polymers.

Suitable thixotroping agents are those known in the art. Examples of thixotroping agents include vinylpyrrolidone homopolymer or copolymers, xanthan gum, acrylic homo polymers or copolymers, or mixtures thereof.

Suitable vinylpyrrolidone homopolymers for use herein is an homopolymer of N- vinylpyrrolidone ("PVP") having an average molecular weight of from 1,000 to 100,000,000, preferably from 2,000 to 10,000,000, more preferably from 5,000 to 1,000,000, and most preferably from 50,000 to 500,000. Suitable vinylpyrrolidone copolymers for use herein is an ammonium acryloyldimethylaurate/VP Copolymer. Perfumes

The compositions described herein may further optionally comprise one or more perfumes. For the purposes of the present invention, the perfumes are contained in the liquid cleaning composition in an effective amount to provide the benefits disclosed herein. As used herein, "effective amount of the perfumes" refers to the quantity of this ingredient necessary to attain the aforementioned effect as a function of the application techniques. Such effective amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the particular perfumes used, the application technique of the cleaning composition, the specific composition of the cleaning composition, and the like. The concentration of the perfumes in the liquid cleaning compositions described herein is preferably comprised between 0.01 and 5% by weight.

Suitable perfumes for use herein include materials which provide an olfactory aesthetic benefit and/or cover any "chemical" odor that the product may have. The main function of a small fraction of the highly volatile, low boiling (having low boiling points), perfume components in these perfumes is to improve the fragrance odor of the product itself, rather than impacting on the subsequent odor of the surface being cleaned. However, some of the less volatile, high boiling perfume ingredients provide a fresh and clean impression to the surfaces, and it is desirable that these ingredients be deposited and present on the dry surface. Perfume ingredients can be readily solubilized in the

compositions, for instance by the surfactants. The perfume ingredients and compositions suitable to be used herein are the conventional ones known in the art. Selection of any perfume component, or amount of perfume, is based solely on aesthetic considerations. Minors The compositions described herein may further optionally comprise one or more minor ingredients selected among colorants, preservatives and disinfectants. For the purposes of the present invention, these minor ingredients are contained in the liquid cleaning composition in an effective amount to provide the benefits disclosed herein. As used herein, "effective amount of the minor ingredients" refers to the quantity of these ingredients necessary to attain the desired effect as a function of the application techniques.

Such effective amount is readily ascertained by one of ordinary skill in the art and is based on many factors, such as the particular ingredient used, the application technique of the cleaning composition, the specific composition of the cleaning composition, and the like.

The concentration of the minor ingredients in the liquid cleaning compositions described herein is preferably comprised between 0.01 and 2% by weight. Suitable colorants are those known in the art. Examples of colorants include well known water soluble dyes and pigments both of natural and of synthetic origin.

Suitable preservatives are those known in the art. Examples of preservatives are any compound that can be stably added to the composition that kills or at least inactivates microbes, for example bacteria and fungi. Particularly preferred preservatives are 5- choloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one available from Rohm & Haas under the trade name KATHON® CG, imidazolidinylurea, C ₁ -C ₄ paraoxybenzoates in phenoxyethanol, chloroacetamide, sodium benzoate, 4,4- dimethyloxazolidine, l,2-benzisothiazolin-3-one available from Avecia under the trade name Proxel GXL, phenoxyethanol available from BASF under the trade name

Protectol PP or gluteraldehyde available from BASF under the trade name Protectol GDA.

Suitable disinfectants are those known in the art. Examples of disinfectants are any compound that can be stably added to the composition that kills or at least inactivates microbes, for example bacteria, thereby exerting sanitizing effect on the cleaned surface. Particularly preferred disinfectants are quaternary ammonium salts such as benzalconium chloride and tertiary amines such as bis-(3-aminopropyl) dodecylamine. For the purposes of the invention, one or more of the ingredients illustrated hereinabove may exert more than one function at the same time thereby advantageously reducing the number of total ingredients and the production costs.

Thus, for example, preferred embodiments of the liquid cleaning compositions may include xanthan gum which may act both as an anti-resoiling agent and as a thickener adjusting the viscosity characteristics of the composition. As mentioned above, furthermore, the surfactants may act both as cleaning agents and as suspending agents of the microparticles and/or of other ingredients such as the perfumes.

For the purposes of the invention, the liquid cleaning compositions described herein may be prepared using mixing procedures of the ingredients well known to those skilled in the art. According to another aspect thereof, the present invention relates to a method of cleaning a surface of an article and of imparting hydrophilic properties to said surface comprising the steps of: applying to said surface a liquid cleaning composition as described above, and rinsing the composition applied to the surface. Most advantageously, the method of the invention allows to render the cleaned surface hydrophilic once the liquid cleaning composition described above is applied to the surface to be cleaned.

As mentioned above, by the term hydrophilic it is meant that the surface has a high affinity for water. Because of the affinity between water and the surface, water spreads

out on the surface to maximize contact. The higher the hydrophilicity the greater the spread and the smaller the contact angle.

Hydrophilicity can be determined by measuring the contact angle between the surface and a droplet of water on the surface. Contact angle is measured according to procedures known in the art for measuring contact angle, for example using the apparatus commercially sold under the trade name DigiDrop, Model DS by GBX, Romans-sur- Isere, France and the software WINDR0P++ also commercially available from GBX. In a preferred embodiment of the present invention, the liquid cleaning composition applied to the surface is capable of modifying the cleaned surface to render it hydrophilic, providing a contact angle between water and the cleaned surface of less than 33°, more preferably the surface has a contact angle of less than 30°, still more preferably, less than 25°.

In a further embodiment of the method, the liquid cleaning composition is preferably also capable of durably modifying the surface to render it hydrophilic, meaning with the term "durably" that the hydrophilic surface modification is maintained for at least one rinse, preferably at least three rinses.

In a preferred embodiment of the present invention, the liquid cleaning composition may be applied to the surface of an article by pouring the composition over the surface, by applying the composition on the surface by means of a cloth or sponge or by spraying the composition on the surface.

The surface can then be left to dry naturally. A particular benefit of the present composition is that the surface is cleaned and rinsed as described above and the surface then left to dry naturally without the formation of water spots or streaks. Alternatively, the surface may be dried using a cloth or chamois. According to another aspect thereof, the present invention relates to solid inorganic microparticles as described above.

According to another aspect thereof, the present invention relates to the use of solid inorganic microparticles as described above as low abrasive material in a cleaning

composition.

Preferably, the cleaning composition may be in form of liquid, gel, foam, particulate or tablet.

According to another aspect thereof, the present invention relates to the use of solid inorganic microparticles as described above for imparting hydrophilic properties to a substrate.

For the purposes of the present description and of the claims which follow, the term: substrate, is used to indicate any kind of hard surface as previously disclosed or any kind of soft and/or flexible surface, such as fabric, textiles, fibers, woven materials, non- woven materials, and carpets.

Li a preferred embodiment, the substrate is a hard surface as illustrated above. Brief description of the drawings

Additional features and advantages of the present invention will be more readily apparent by the following Examples of some preferred embodiments of the present invention given hereinbelow by way of illustration and not of limitation, hi these drawings:

Fig. 1 shows an X-Ray diffraction pattern of one example of solid inorganic microparticles according to the invention;

Fig. 2 shows an X-Ray diffraction pattern of one example of solid inorganic microparticles according to the prior art;

Figs. 3 show a SEM image of one example of solid inorganic microparticles according to the invention;

Figs. 4 show a SEM image of one example of solid inorganic microparticles according to the prior art; - Figs. 5 show a TEM image of the solid inorganic microparticles according to the invention shown in Fig. 3 which display the aggregate structure of nanoparticles;

Fig. 6 shows a thermogravimetric plot of one example of solid inorganic microparticles according to the invention;

Fig. 7 shows a FTIR spectrum of one example of solid inorganic microparticles according to the invention;

Fig. 8 shows an image of a drop placed on a hard surface and of the contact angle formed between the drop and the surface before applying the liquid cleaning composition according to the invention;

Fig. 9 shows an image of a drop placed on a hard surface cleaned by means of a liquid cleaning composition according to the invention and of the contact angle formed between the drop and the cleaned surface;

Fig. 10 shows an image of a rinsed surface of mirrored stainless steel after application of a liquid cleaning composition according to the invention;

Fig. 11 shows an image of a rinsed surface of mirrored stainless steel after application of a liquid cleaning composition according to the prior art. In the following Examples, percentages and parts are by weight unless otherwise indicated. EXAMPLES 1-2

(Invention - Liquid cleaning compositions in cream form)

Liquid cleaning compositions in cream form adapted to be poured and applied to a surface to be cleaned by means of a cloth or sponge according to Examples 1-2 in Table 1 below were prepared.

TABLE l

* = solid microparticles of carbonate-substituted non-stoichiometric hydroxyapatite prepared according to the process described in Example 5 hereinbelow. The compositions were prepared by first dissolving the bentonite and xanthan gum in deionized water (aqua) until complete solubilization and then adding under agitation potassium cocoate, terpene ethoxylated propoxylated, butoxyethanol, tetrapotassium pyrophosphate and sodium carbonate.

The mixture thus obtained was then added with sodium 2-ethylexyl sulfate and perfume previously mixed together, with the microparticles and then with the preservative (MemylcMoroisotMazolinone-Methylisothiazolinone). All the dissolving and stirring steps were carried out taking care that aeration is avoided.

EXAMPLES 3-4

(Invention - Liquid cleaning compositions) Liquid cleaning compositions in a thixotropic form adapted to be applied to a surface to be cleaned by spraying according to Examples 3-4 in Table 2 below were prepared.

TABLE 2

* = solid microparticles of carbonate-substituted non-stoichiometric hydroxyapatite prepared according to the process described in Example 6 hereinbelow. The compositions were prepared by first adding under stirring the microparticles and the thixotroping agent in deionized water (aqua) until complete solubilization and then adding under agitation terpene ethoxylated propoxylated and butoxyethanol. The mixture thus obtained was then added with Laureth-4 and perfume previously mixed together, and then with the preservative (Methylchloroisothiazolinone- Methylisothiazolinone) and the sanitizing agent (benzalconium chloride). All the dissolving and stirring steps were carried out taking care that aeration is avoided.

EXAMPLE 5

(Invention - Preparation of the low abrasive microparticles)

The low abrasive carbonate-substituted non-stoichiometric hydroxyapatite microparticles used in Examples 1-2 were prepared as follows. In a first step, an aqueous suspension comprising 356 g of Ca(OH) ₂ and 94 g of Ca(CO ₃ ) in 1100 g Of H ₂ O was prepared in a conventional reaction vessel while agitating the ingredients with a mechanical stirrer.

During this step, the resulting suspension was brought to a temperature of 40°± 2 °C by means of an electrical resistance or by any other suitable heating element such as for example a thermostated jacket in which a heating fluid, such as oil or vapor, is circulated. Once the desired temperature was reached, nanoparticles of a carbonate-substituted hydroxyapatite were formed by adding dropwise PO ₄ ^3" ions to the aqueous suspension of the preceding step while simultaneously agitating the same. In this case, 600 g of an acid solution constituted by a mixture 70/30 of H ₃ PO ₄ (75%)/H ₂ O, were added with a dripping speed of 22 g "min ^'1 (0,4 g "sec ^'1 ), while continuously stirring and maintaining constant the temperature of the reaction vessel.

After about 4h a suspension of nanoparticles was obtained which was subsequently agitated over a period of time of 2h, after which a suspension having a total content of about 30-31% by weight of microparticles having a mean particle size of 2μm, a surface area of 40 m ² /g and a crystallinity degree CD of 30% was obtained. Next, the solid microparticles were separated from the liquid by filtering on a Millipore paper with a pore diameter of 45 μm and then were repeatedly washed with a diluted water solution OfCaCO ₃ to remove any acid residues.

The wet solid microparticles thus obtained were then freeze-dried at -40 ⁰ C until they reached a constant weight, sieved at (0=120-20 microns) and stored at a temperature of 0-4 ⁰ C.

The microparticles thus obtained, which had the aspect of a white powder, were then characterized as follows. n X-rav diffraction fXRD)

X-ray powder patterns were collected using a Philips PW 1710 powder diffractometer equipped with a secondary graphite monochromator using Cu Ka radiation generated at 40 kV and 40 niA. The instrument was configured with a 1° divergence and 0.2 mm receiving slits. The samples were prepared using the front loading of standard

aluminium sample holders which are 1 mm deep, 20 mm high and 15 mm wide. The 20 range was from 5° to 60° with a step size (2θ) of 0.05° and a counting time (s) of 3.

In Fig. 1 the XRD pattern of the microparticles, which allows to determine the crystallinity degree of the microparticles, is shown. In Fig. 1, the line intensity is related to its intensity percentage (arbitrary units), considering the highest line equal to 100.

The crystallinity degree, was evaluated according to the aforementioned Erkmen method was of about 30%.

2) Morphological characterization by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)

Scanning Electron Microscopy (SEM) observations were carried out using a Philips 515 apparatus. The samples were mounted on carbon tape on aluminium stubs and gold coated with an acceleration voltage of 3OmV for a time ranging from 30 to 180 sec, prior to investigation. Transmission Electron Microscopy (TEM) observations were carried out using a Philips

CM 100. The powdered samples were ultrasonically dispersed in ultrapure water and then a few droplets were dropped on holey-carbon foils supported on conventional copper microgrids.

SEM and TEM images of the microparticles are reported in Fig 3 and 5 respectively where it is possible to appreciate the small particle size thereof as well as their clusters nature comprising nanoparticles having an elongate shape with acicular and platelet shape morphology. The nanoparticles forming the clusters had an average length L of about 100 run, an average width W of about 10 nm and an average thickness T of about

5 nm. The average aspect ration A/R was 10.

3> Thermal analysis (TGA-DSC)

Thermogravimetric investigations were carried out on the microparticles using a

Thermal Analysis SDT Q 600. Heating was performed in nitrogen flow (100 ml/min)

using an alumina sample holder at a rate of 10°C/min up to 1000 ⁰ C. The weight of the samples was around 10 mg.

Fig. 6 reports the results of a thermogravimetric analysis of the microparticles showing the weight decreases relating to the decomposition of the inorganic phase. Line a corresponds to percentage weight loss as a function of the treatment temperature and line b represents the derivative of the percentage weight loss respect to the temperature. Line b shows a broad peak between 15O ⁰ C and 300 ⁰ C due to the loss of the physically absorbed water (weight loss of 2.2 ± 0.5%). The peak between 800 ⁰ C and 1000 ⁰ C can be attributed to the dehydroxylation process (weight loss of 1.5 ± 0.5%). The peak broadness is partially due to the low crystallinity degree of the microparticles.

4) Surface area analysis (BET)

The specific surface area of the microparticles was evaluated by the Brunauer, Emmet,

Teller method [S. Brunauer, P. H. Emmet, E. Teller, Adsorption of gases in multimolecular layers. J. Am. Chem. Soc. 60 (1938) 309- 319], [ SJ; Greg, KS. Sing (Eds.), Adsorption, Surface Area and Porosity, Academic Press, 1997 O. Gauthir, JM.

Boiler, E. Aguado, P. Piletand, G. Daculsi] carried out by means of a Carlo-Erba Sorpty

1750 instrument and using N ₂ as adsorption gas.

Analyses were performed on 300 mg of samples. Before gas absorption, the samples were dried under vacuum (2 mbar) while increasing the temperature, at a speed of 10°C/min, from 25 ⁰ C to 100 ⁰ C. N ₂ adsorption was then carried out keeping the sample in liquid N ₂ . Each surface area measurement supplied by the instrument corresponds to the mean of three values.

The average surface area of the microparticles was of about 40 m ² /g.

5) Chemical composition: Inductively Coupled Plasma - Optical Emission Spectrometry αCP-OES) analysis

The amount of calcium and phosphorous in the samples of nanoparticles was obtained using and Inductively Coupled Plasma - Optical Emission Spectrometry (ICP- OES) technique. The ICP-OES measurements were carried out with a Perkin Elmer Optima

4200 DV instrument. The samples had been previously dissolved in ultrapure nitric acid

1% to obtain a concentration of the elements between 1 and 8 ppm.

The microparticles exhibited a bulk Ca/P molar ratio of about 1.8.

6) Spectroscopic characterization by Fourier Transform Infrared (FTIR) analysis The infrared spectra were registered from 4000 to 400 cm ^-1 at 2 cm ^"1 resolution by using a Bruker IFS 66v/S spectrometer. Pellets (KBr) were obtained under vacuum by using powdered samples (1 mg) carefully mixed with infrared grade KBr (200 mg).

The FTIR spectrum of the microparticles is shown in Fig. 7. The spectrum shows the signals related to the groups PO ₄ ^3" (1037 cm ^"1 ), HPO ₄ ^2" (955 cm ^"1 ), OH ^' (3444 cm ^"1 and 1630 cm ^"1 ), CO ₃ ^2" (870 cm ^"1 ). A comparison between the peak area at 870 cm ^"1 of the nanoparticles and the peak area at 870 cm ^"1 of a CaCO ₃ reference standard allowed to evaluate a CO ₃ ^2" amount of about 8% by weight based on the total weight of the nanoparticles.

The band at 870 cm ^"1 provides information about the apatite carbonation type. The deconvolution profile of the carbonate peak at 870 cm ^"1 allows to deduce that the hydroxy apatite carbonation is predominantly of type B (A/B ratio of approximately 1).

The relevant characterization data of the nanoparticles are summarized in the following

Table 3.

EXAMPLE 6 (Invention - Preparation of the low abrasive microparticles)

The low abrasive carbonate-substituted non-stoichiometric hydroxyapatite microparticles used in Examples 3-4 were prepared as follows.

First was prepared an aqueous suspension according to the method and using the same ingredients of preceding Example 1 save for the fact that the amount of water was of about 1050 g, the amount of CaCO ₃ was of 120 g, the amount of Ca(OH) ₂ was 340 g.

During this step, the resulting suspension was brought to a temperature of 40°± 2 °C by the same method of the preceding Example 5.

Once the desired temperature was reached, nanoparticles of a carbonate-substituted hydroxyapatite were formed by adding dropwise PO ₄ ^3' ions in the same way and in the same amounts as described in preceding Example 5.

After about 3h a suspension of microparticles was obtained which was subsequently treated in the same manner described in preceding Example 5.

The microparticles were then separated from the aqueous suspension thus obtained according to the separation method described in the preceding Example 5. The microparticles thus obtained were then characterized according to the procedures and methods described in Example 5. The relevant characterization data of the nanoparticles are reported in the following Table 3.

TABLE 3

* = % by weight with respect to the total weight of the microparticles.

EXAMPLE 7

(Comparative - Liquid cleaning composition in cream form according to the prior art) Using the same procedure of preceding Examples 1-2, a liquid cleaning composition in cream form adapted to be poured and applied to a surface to be cleaned by means of a cloth or sponge were prepared using the same ingredient of Example 1 except for the fact that calcite microparticles having a particle size of 80-500 μm, a surface area of 1 m ² /g and a crystallinity degree CD of 88% were used.

These microparticles were obtained from a commercial product and were characterized according to the procedures illustrated in preceding Example 5.

The XRD diffraction pattern and a SEM image of the microparticles used are shown in Figs. 2 and 4 respectively, from which it may visually appreciated the greater particle size and the greater crystallinity possessed by these microparticles.

EXAMPLE 8

(Comparative - Liquid cleaning composition according to the prior art) Using the same procedure of preceding Examples 3-4, a liquid cleaning composition in liquid adapted to be applied to a surface to be cleaned by means of a spraying device were prepared using the same ingredient of Example 3 except for the fact that calcite microparticles of preceding Example 7 were used.

EXAMPLE 9

(Evaluation of the hydrophilic characteristics of the cleaned surface) hi order to evaluate the ability of the liquid cleaning compositions of the invention to clean and to render hydrophilic a hard surface the following test was carried out. Hydrophilicity of the hard surface was determined by measuring the contact angle between the surface and a droplet of water placed onto said surface before and after a cleaning action. Test 1 (reference) A water drop was placed onto a glass slide. A photographic picture of the water drop was taken through the apparatus commercially sold under the trade name DigiDrop, Model DS by GBX, Romans-sur-Isere, France (see Fig. 8). The contact angle between the horizontal flat surface of the drop placed onto the untreated surface and the tangent to the drop itself was calculated utilizing the software WINDROP++ also commercially available from GBX, Romans-sur-Isere, France. A value of the contact angle of 33.3° was obtained. Test 2 (invention).

The same a glass slide was then cleaned with the liquid cleaning composition of Example 1 by pouring a small amount of the composition on a cloth, wiping the surface with a cloth, rinsing and letting the surface to dry naturally.

Then a water drop was placed onto the dry cleaned surface and a photographic picture of the water drop was taken (see Fig. 9). The contact angle was measured in the same way of test 1 and the obtained value of the contact angle was of 22.8°. Similar tests were carried out using the liquid cleaning composition of Examples 2-4 obtaining values the contact angle of 18.2° (Example 2), 28° (Example 3) and 26.1° (Example 4). As may be visually noted from Fig. 9, therefore, the liquid cleaning compositions of the invention advantageously allow not only to clean the surface, but also to impart to the cleaned surface characteristics of hydrophilicity which allow to reduce resoiling phenomena and water stagnation on the cleaned surface thereby enhancing the rinsability and "self-cleaning" properties and maintaining the gloss and luster characteristics of the cleaned surface.

EXAMPLE 10

(Evaluation of the abrasion characteristics of the liquid cleaning compositions) In order to compare the abrasion characteristics of the liquid cleaning compositions according to the invention with those of the prior art the following tests were carried out.

Abrasion test

Comparative damage tests were carried on a black enamelled surface and on a chrome- plated metal surface with the liquid cleaning compositions in cream form of Examples 1 (invention) and 7 (prior art). Black enamelled surface

A model black enamelled surface of metal with an initial reflectance of 4.405 (mean value of four measurements) as measured on a commercially available colorimeter

model UltraScan XE (Hunter Associates Laboratory, Inc., Reston, VA. U.S.A.) was chosen for this study.

The loss in gloss of this substrate was measured using 2 g of product using a cloth tool under 1.5 Kg load for 100 alternative wiping cycles on a to and fro head adding one drop of cleaning composition every 5 cycles. At the end of the wiping cycles, the surface was rinsed with tap water and dried by means of a cotton cloth in order to eliminate possible traces of the compositions.

The reflectance of the surface treated with the two compositions was then measured using the same colorimeter (mean value of three measurements). The higher the loss in terms of reflectance of the surface, the higher is the damage potential of the product. The abrasion characteristics of the tested liquid cleaning compositions is presented in the following Table 4.

TABLE 4

* According to AATCC Evaluation procedure 7, "Instrumental Assessment of The Change in Color of a Test Specimen" carried out using a commercially available spectrograph UV VIS.

AATCC scale: 5 = no detectable variation; 1 = great difference

Chrome-plated metal surface

A model chrome-plated metal surface with an initial reflectance of 60.1 (mean value of four measurements) as measured on the commercially available colorimeter mentioned above was chosen for this study.

The loss in gloss of this substrate was measured using 3 g of product using a cloth tool for 200 circular wiping cycles carried out manually adding one drop of cleaning composition every 5 cycles. At the end of the wiping cycles, the surface was rinsed with

tap water and dried by means of a cotton cloth in order to eliminate possible traces of the compositions.

The reflectance of the surface treated with the two compositions was then measured using the same apparatus (mean value of three measurements). The higher the loss in terms of reflectance of the surface, the higher is the damage potential of the product. The abrasion characteristics of the tested liquid cleaning compositions is presented in the following Table 5.

TABLE 5

Although the instrumental measurements showed a slight improvement of performance of the liquid cleaning compositions of the invention in terms of reflectance, a visual inspection of the treated surface showed that visible scratches appeared on the surface cleaned with the comparative composition according to the prior art.

The abrasion tests show that the liquid cleaning compositions of the invention have markedly lower abrasion characteristics with respect to the comparative cleaning compositions and achieve superior properties in terms of maintaining the surface integrity of the substrate.

EXAMPLE I l (Evaluation of the ability of the liquid cleaning compositions of being rinsed away)

In order to compare the ability of the liquid cleaning compositions according to the invention and of those of the prior art of being rinsed away the following tests were carried out.

Evaluation of loss of shine

Colorimetric tests were carried to evaluate the loss of shine on a surface of black enamelled surface and on a surface of stainless steel cleaned and rinsed with the liquid cleaning compositions in cream form of Examples 1 (invention) and 7 (prior art).

Black enamelled surface

A model black enamelled surface of metal with an initial reflectance of 4.405 (mean value of four measurements) as measured on the commercially available colorimeter mentioned above was chosen for this study.

The loss of shine of this substrate was measured using 2 g of product using an Erichsen apparatus model 494 (Erichsen GmbH, Hemer, Germany) under 1 Kg load for 5 alternative wiping cycles on a to and fro head. At the end of the wiping cycles, the surface was rinsed with tap water for 30" and dried by leaving the surface in vertical position in open air for three hours.

The reflectance of the surface treated with the two compositions was then measured using the same apparatus (mean value of three measurements). The higher the loss in terms of reflectance of the surface, the higher is the amount of product residues on the surface. The reflectance values of the treated surfaces are presented in the following Table 6.

TABLE 6

Stainless steel surface

A model stainless steel surface with an initial reflectance of 63.7125 (mean value of four measurements) as measured on the commercially available colorimeter mentioned above was chosen for this study. The loss of shine of this substrate was measured using 2 g of product using the Erichsen apparatus mentioned above under 1 Kg load for 5 alternative wiping cycles on a to and fro head. At the end of the wiping cycles, the surface was rinsed with tap water for 30" and dried by leaving the surface in vertical position in open air for three hours. The reflectance of the surface treated with the two compositions was then measured using the same colorimeter (mean value of three measurements). The higher the loss in terms of reflectance of the surface, the higher is the amount of product residues on the

surface. The reflectance values of the treated surfaces are presented in the following Table 7.

TABLE 7

The data presented above show that the liquid cleaning compositions of the invention have a markedly improved ability of being rinsed away with respect to the comparative cleaning compositions and achieve superior properties in terms of more rapid rinsing operation to restore the original surface shine of the substrate.

EXAMPLE 12

(Evaluation of the ability of sprayable liquid cleaning compositions of being rinsed away) hi order to compare the ability of the sprayable liquid cleaning compositions according to the invention and of those of the prior art of being rinsed away the following tests were carried out.

Visual tests were carried to evaluate the appearance of a rinsed surface of mirrored stainless steel on which the liquid cleaning compositions of Examples 3 (invention) and

8 (prior art) were applied by means of a spraying device.

To this end, on a model mirrored stainless steel surface with an initial reflectance of

62.99 (mean value of four measurements) as measured on the commercially available colorimeter mentioned above 2 g of product were applied using a conventional spraying device.

The product applied on the surface was then left to dry in open air for 30' at room temperature and the surface was then rinsed with tap water for 30" and dried by leaving the surface in vertical position in open air for three hours.

Pictures of the two rinsed surfaces are shown in attached Fig. 10 and 11. The reflectance of the rinsed surfaces was also measured using the same colorimeter

(mean value of four measurements). The higher the loss in terms of reflectance of the

surface, the higher is the amount of product residues on the surface. The reflectance values of the treated surfaces are presented in the following Table 8.

TABLE 8

Although the instrumental measurements already shows an improvement of performance of the liquid cleaning compositions of the invention over the liquid composition of the prior art in terms of reflectance, a visual inspection of the treated surface showed that rinsing ability of the liquid composition of the invention was far more superior to that of the prior art composition as may be appreciated by comparing Fig. 10 and 11. The data presented above show that the liquid cleaning compositions of the invention have a markedly improved ability of being rinsed away with respect to the comparative cleaning compositions and achieve superior properties in terms of more rapid rinsing operation to restore the original surface shine of the substrate.