WO2024223718A1

WO2024223718A1 - A unit dose tablet

Info

Publication number: WO2024223718A1
Application number: PCT/EP2024/061340
Authority: WO
Inventors: Manoj Vilas Dagaonkar; Girish Muralidharan; Aditya Bangalore NAGESH; Ivy PAL; Rajeesh Kumar Ramachandran; Himadri SEKHAR KUMAR
Original assignee: Unilever Ip Holdings B.V.; Unilever Global Ip Limited; Conopco, Inc., D/B/A Unilever
Priority date: 2023-04-28
Filing date: 2024-04-25
Publication date: 2024-10-31

Abstract

The present invention is in the field of cleaning compositions. It relates to a tablet composition providing a liquid cleaning composition on dissolution in water. There is a need for an improved tablet containing significantly high amount of detersive active for providing enhanced cleaning benefit, wherein the tablet is hard, yet dissolves fast in contact with water. The present invention provides a tablet comprising an anionic surfactant and a non-ionic surfactant in a select ratio along with select water-soluble disintegrants, that disintegrants quickly in contact with water thereby providing a liquid cleaning composition. The liquid cleaning composition provides enhanced cleaning benefit. The present invention further provides a process for obtaining a hard surface cleaning composition and a method for cleaning a surface.

Description

A UNIT DOSE TABLET

Field of the Invention

The present invention is in the field of cleaning compositions. In particular, it relates to a unit dose tablet providing a liquid cleaning composition on dissolution in water.

Background of the Invention

Consumers spend considerable amount of time and effort in cleaning their households. They prefer to use different cleaning products depending on the substrates to be cleaned. Typically, such products differ in terms of their ingredients such as, detersive agents, builders, perfume etc. Further, a particular product may be available in different formats such as, powder, liquid, tablet, and pod. Often consumers prefer to have a product in tablet format since a tablet is compact in size and provides a controlled dosage.

Typically, a cleaning product in tablet format contains concentrated cleaning or detersive active. A consumer dissolves the tablet in water to form a cleaning composition, thereby use it. Conventionally, a tablet is formed by compacting a homogenised powder comprising the required ingredients. In one hand, a high compression force leads to hard tablets which fails to dissolve fast. On the other hand, lower compression force leads to loosely packed ingredients which helps in faster dissolution, however, does not have the required strength. In the present context, it is desirable that the tablet is hard enough to resist breakage in transportation/storage yet dissolves fast in contact with water.

Further, it is implicitly desired that the tablet provides an improved cleaning efficacy. One way to achieve this by increasing the amount of detersive actives in the tablet. However, that may lead to densely packed hard tablets with relatively slower dissolution rate. Further, increasing detersive actives is compensated with reducing the amount of disintegrants, thereby affecting dissolution further.

In this regards, WO 08/8040151 describes a solid synthetic detergent comprising anionic surfactants, disintegrants and builders, in which at least one surfactant surrounding the particles comprising detergent ingredients acts as disintegrative component, and the disintegrants also include polyvinyl pyrrolidone, succinic acid or citric acid, and sodium bicarbonate.

US 2002 082187 describes an effervescent compound which includes a solvent and an effervescent system. The solvent may include a glycol ether, for example, but not limited to, 2- butoxyethanol. The effervescent system used in the effervescent compound may be, for example, but is not limited to, expanded sodium perborate or a mixture of sodium bicarbonate, sodium carbonate, and an acid.

US 2005/0148488 (Henkel, 2005) describes a multiphase detergent tablet that has at least one active phase containing one or more washing or cleaning substances, a solid matrix enclosing the substances in the form of a solidified melt, where the matrix material is selected from sugars, sugar acids, sugar alcohols, and any mixtures thereof. The solid matrix has a solubility above 100 gm/L at 20° C and it is at least 10% of the total weight of the active phase.

WO 00/27986 (Henkel, 2000) describes detergent tablets, which are characterized by high hardness coupled with short disintegration times. Such tablets can be produced by addition of fine-particle sugar with at least 50% by weight of the sugar particles having size smaller than 400 microns.

EP 1 074608 A1 (Robert McBridge Ltd., 2001) discloses detergent tablets containing at least one surface active agent, a builder, and a water insoluble but water swellable disintegrating agent. More particularly the tablets contain at least 5% by weight of solid surface-active agent of which at least a portion is a solid non-ionic surface-active agent and does not contain more than 3% by weight of liquid non-ionic surface-active agent.

WO 2022/258413 A1 (Unilever et.al. , 2022) discloses a detergent tablet comprising at least 10% by weight surfactant; and a dissolving aid selected from hydrated monosaccharides, hydrated disaccharides, hydrated oligosaccharides and combinations thereof, wherein the ratio of the surfactant to the dissolving aid is at least 1: 1.5 by weight.

Despite the prior art, there remains a need for an improved tablet containing significantly high amount of detersive active for enhanced cleaning benefit, wherein the tablet is hard, yet dissolves fast in contact with water.

The present inventors while working on this have surprisingly found that a tablet composition comprising a mix of an anionic surfactant and a non-ionic surfactant in a select ratio, along with select water-soluble disintegrants dissolves quickly in water thereby providing a liquid cleaning composition. The cleaning composition provides improved cleaning benefit.

Summary of the Invention

In a first aspect, the present invention provides a unit dose tablet comprising: a) 5 to 40 % by weight of an anionic surfactant; b) 5 to 75 % by weight of a non-ionic surfactant; and c) a water-soluble disintegrant is selected from hydrated monosaccharides, hydrated disaccharides, hydrated oligosaccharides and combinations thereof, wherein ratio of the anionic surfactant to the non-ionic surfactant is in the range from 1:1 to 1:5 by weight.

In another aspect, the present invention provides a hard surface cleaner obtained by dissolving a tablet according to the first aspect in water, wherein the ratio of the tablet to water is in the range from 1:5 to 1 :100 by weight.

In a further aspect, the present invention provides a process for cleaning a surface comprising the steps of: a) providing water in a container; b) adding and dissolving a tablet according to the first aspect into the water, wherein the ratio of the tablet to water is in the range from 1 :50 to 1 : 1000 by weight, thereby providing a liquid cleaning composition; and c) applying the cleaning composition on the surface and cleaning it.

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from reading of the following detailed description. For the avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word “comprising” is intended to mean “including” but not necessarily “consisting of” or “composed of.” In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about”. Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Detailed Description of the Invention

By “unit dose” as used herein, implies an amount of a composition suitable for single time use.

By “effervescent system” as used herein refers to a compound or combination of two or more compounds which produces effervescence in contact with water. By “Disintegrant” as used herein refers to ingredients present in a tablet to accelerate dissolution of the tablet in water. In contact with water such ingredients break or disintegrate the tablet into smaller fragments thereby accelerating the dissolution.

According to the present invention there is provided a unit dose tablet comprising an anionic surfactant, a non-ionic surfactant and a water-soluble disintegrant selected from hydrated monosaccharides, hydrated disaccharides, hydrated oligosaccharides and combinations thereof. The ratio of the anionic surfactant to non-ionic surfactant is in the range 1 :1 to 1 :5 by weight. The tablet according to the present invention comprises a surfactant for providing detersive benefit.

Anionic surfactant

The tablet comprises an anionic surfactant. Preferably the anionic surfactant is selected from alkyl sulphate, alkyl ether sulphate, linear alkyl benzene sulphonate, alkyl cocoyl taurate and combinations thereof.

Anionic surfactant suitable for the present invention includes salts of organic sulphates and sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term “alkyl” being used to include the alkyl portion of higher acyl radicals. Examples of such materials include alkyl sulphates, alkyl ether sulphates, alkaryl sulfonates, alpha-olefin sulfonates and mixtures thereof. The alkyl radicals preferably contain from 10 to 18 carbon atoms and may be unsaturated. The alkyl ether sulphates may contain from one to ten ethylene oxide or propylene oxide units per molecule, and preferably contain one to three ethylene oxide units per molecule.

The suitable anionic surfactant includes alkylbenzene sulfonates. Preferably in an embodiment suitable for dishwash comprises linear alkylbenzene sulfonates (LAS) with an alkyl chain length of from 10 to 18 carbon atoms. Commercial LAS is a mixture of closely related isomers and homologues alkyl chain homologues, each containing an aromatic ring sulfonated at the “para” position and attached to a linear alkyl chain at any position except the terminal carbons. The linear alkyl chain typically has a chain length of from 11 to 15 carbon atoms, with the predominant materials having a chain length of about C12. Each alkyl chain homologue consists of a mixture of all the possible sulpho-phenyl isomers except for the 1 -phenyl isomer. LAS is normally formulated into compositions in acid (i.e. , HLAS) form and then at least partially neutralized in-situ. The counterion for anionic surfactants is generally an alkali metal such as sodium or potassium; or an ammoniacal counterion such as monoethanolamine, (MEA) diethanolamine (DEA) or triethanolamine (TEA), monoisopropanolamine (MIPA), monoisopropylamine. Mixtures of such counterions may also be employed. Sodium and potassium are preferred.

Preferably the suitable anionic surfactant includes alkyl sulphate surfactant (PAS), such as nonethoxylated primary and secondary alkyl sulphates with an alkyl chain length of from 10 to 18.

Preferably the tablet suitable for laundry application may contain alkyl ether sulphates having a straight or branched chain alkyl group having 10 to 18, more preferably 12 to 14 carbon atoms and containing an average of 1 to 3 ethylene oxide (EO) units per molecule. A preferred example is sodium lauryl ether sulphate (SLES) in which the predominantly C12 lauryl alkyl group has been ethoxylated with an average of 3EO units per molecule. The alkyl ether sulphates may be used alone or in combination with any other anionic surfactant.

Preferably the anionic surfactant is selected from alkyl benzene sulphonate, alkyl ether sulphate, alkyl cocoyl taurate and combinations thereof. Preferably the anionic surfactant comprises alkyl cocoyl taurate.

The amount of the anionic surfactant is in the range 5 to 40% by weight of the tablet. Preferably the amount of the anionic surfactant is in the range 5 to 35% by weight, more preferably 5 to 30 and most preferably 5 to 25% by weight of the tablet.

Non-ionic surfactant

The tablet comprises a non-ionic surfactant. Preferably the non-ionic surfactant is selected from alcohol, ethoxylate, alkyl polyglycoside and combinations thereof.

Typically, anionic surfactants are known for providing good detersive benefit. Surprisingly, in the present invention it is found that the anionic surfactant is not sufficient, whereas a combination of the anionic surfactant with the non-ionic surfactant in claimed ratio provides a significantly improved cleaning efficacy.

Suitable non-ionic surfactants include water soluble aliphatic ethoxylated non-ionic surfactants including the primary aliphatic alcohol ethoxylates and secondary aliphatic alcohol ethoxylates. This includes the condensation products of a higher alcohol (e.g., an alkanol containing about 8 to 16 carbon atoms in a straight or branched chain configuration) condensed with about 4 to 20 moles of ethylene oxide, for example, lauryl or myristyl alcohol condensed with about 10 moles of ethylene oxide (EO), tridecanol condensed with about 6 to 15 moles of EO, myristyl alcohol condensed with about 10 moles of EO per mole of myristyl alcohol, the condensation product of EO with a cut of coconut fatty alcohol containing a mixture of fatty alcohols with alkyl chains varying from 10 to about 14 carbon atoms in length and wherein the condensate contains either about 6 moles of EO per mole of total alcohol or about 9 moles of EO per mole of alcohol and tallow alcohol ethoxylates containing 6 EO to 11 EO per mole of alcohol.

Examples of the foregoing non-ionic surfactants include, but are not limited to, the Neodol (trade mark, ex Shell), which are higher aliphatic, primary alcohol containing about 9 to 15 carbon atoms, such as C9 to C11 alkanol condensed with 4 to 10 moles of ethylene oxide (Neodol 91-8 or Neodol 91-5), C12 to C13 alkanol condensed with 6.5 moles ethylene oxide (Neodol 23-6.5), C12 to C15 alkanol condensed with 12 moles ethylene oxide (Neodol 25-12), C14 to C15 alkanol condensed with 13 moles ethylene oxide (Neodol 45-13), and the like. Such ethoxamers have an HLB (hydrophobic lipophilic balance) value of about 8 to 15 and give good O/W emulsification, whereas ethoxamers with HLB values below 7 contain less than 4 ethylene oxide groups and tend to be poor emulsifiers and poor detergents. Preferably the tablet comprises at least 10% by weight of the alcohol ethoxylate as non-ionic surfactant. Preferably the alcohol ethoxylate constitutes 50 to 100 % by weight of the total amount of non-ionic surfactant. Most preferably the alcohol ethoxylate constitutes 100% by weight of the total amount of non-ionic surfactant.

Another group of suitable non-ionic surfactants are alkyl polyglycosides(APG) which are sugar derivatives of fatty alcohol. Example of such surfactants are decyl glucoside, lauryl glucoside, myristyl glucoside. Most preferred non-ionic surfactant is alcohol ethoxylate.

The amount of the non-ionic surfactant is in the range 5 to 75% by weight of the tablet. Preferably the amount of the non-ionic surfactant is in the range 10 to 70% by weight, more preferably 10 to 65% by weight, even more preferably 10 to 60% by weight, yet more preferably 10 to 55% by weight and most preferably 10 to 50% by weight of the tablet.

Preferably total amount of surfactant present in the tablet is in the range 10 to 90% by weight of the tablet. More preferably the total amount of the surfactant is in the range 10 to 80% by weight, even more preferably 10 to 75% by weight, yet more preferably 10 to 70% by weight, and most preferably 12 to 65% by weight of the tablet.

In some scenario, the tablet may comprise up to 60% by weight, more preferably up to 55% by weight and most preferably up to 50% by weight of total amount of the surfactant. The ratio of the anionic surfactant to the non-ionic surfactant is in the range 1 :1 to 1 :5 by weight, more preferably 1 :1 to 1 :4 and most preferably 1 :1 to 1 :3 by weight.

Preferably the ratio of the anionic surfactant to non-ionic surfactant is in the range 1 :2 to 1 :5 by weight, more preferably 1 :2 to 1 :4 by weight and most preferably 1 :2 to 1 :3 by weight. Most preferred ratio of the anionic to non-ionic surfactant is 1 :3 by weight.

The anionic surfactant and the non-ionic surfactant may constitute 100% by weight of the total surfactant present in the tablet. The surfactant mix provided enhanced cleaning benefit over individual surfactant.

Disintegrant

The tablet comprises a water-soluble disintegrant. Generally, disintegrant in a tablet context used to facilitate breaking or disintegrating the tablet into pieces, thus helps in dissolution of detersive actives in water. In the present invention, it is observed that the surfactant mix in presence of the water-soluble disintegrant accelerates dissolution of the tablet.

Preferably the tablet comprises 10 to 90% by weight of the water-soluble disintegrant. More preferably the tablet comprises 15 to 85% by weight, even more preferably 20 to 80% by weight and most preferably 25 to 75% by weight of the water-soluble disintegrant.

. A tablet containing such disintegrants, when added to water, it leaves no residues in the water, thereby providing a transparent liquid on dilution.

The water-soluble disintegrant is selected from hydrated monosaccharide, hydrated disaccharide and hydrated oligosaccharides. Most preferred water-soluble disintegrant is glucose monohydrate.

The disintegrant may further comprise a water-insoluble disintegrant. The water-insoluble disintegrant may be selected from microcrystalline cellulose, sodium starch glycolate, polyvinyl pyrrolidone, starch, calcium silicate, magnesium stearate and combinations thereof. Polyvinyl pyrrolidone includes crosslinked polyvinyl pyrrolidone.

The amount of water-insoluble disintegrant, if present, may be in the range 1 to 60% by weight, more preferably 3 to 50% by weight and most preferably 5 to 40% by weight of the tablet.

Hydrotrope The tablet may comprise a hydrotrope. Hydrotrope is a class of low molecular weight compounds having a hydrophilic and hydrophobic part similar to surfactants. However, the hydrophobic part is much smaller compared to surfactants. Thus, they may not lead to spontaneous self-aggregation or micellar solubilization. It is also observed that hydrotrope does not have a critical micellar concentration (CMC) or a critical vesicle concentration (CVC) like surfactants. It may possible that hydrotrope aggregates in a stepwise self-aggregation process, gradually increasing aggregation size. Preferably the hydrotrope comprises an alkyl aryl sulphonate having C1 to C5 alkyl chain.

The tablet preferably comprises 0.1 to 10% by weight of the hydrotrope. More preferably the tablet comprises 0.2 to 9% by weight, even more preferably 0.3 to 8% by weight and most preferably 0.3 to 7% by weight of the hydrotrope.

The hydrotrope may be selected from sodium xylene sulphonate, sodium toluene sulphonate, sodium cumene sulphonate, potassium xylene sulphonate, potassium toluene sulphonate, potassium cumene sulphonate and combinations thereof. Most preferred hydrotrope is sodium cumene sulphonate and/or sodium xylene sulphonate.

Organic acid

The tablet according to the present invention may comprises an organic acid.

Preferably the organic acid is selected from citric acid, tartaric acid, fumaric acid, malic acid, adipic acid, succinic acid, and combinations thereof. Preferably the organic acid is citric acid.

Preferably the tablet comprises 1 to 50% by weight, more preferably 3 to 45% by weight and most preferably 5 to 40% by weight of organic acid.

Water-soluble inorganic salt

The tablet may comprise a water-soluble inorganic salt. Suitable inorganic salts include alkali metal salt of carbonate or bicarbonate or silicates and combinations thereof.

Preferably the carbonate or bicarbonate salt is selected from sodium carbonate, potassium carbonate, calcium carbonate, sodium bicarbonate, potassium bicarbonate, calcium carbonate, calcium bicarbonate and magnesium carbonate as well as mixtures thereof.

Preferably the tablet comprises 1 to 50% by weight, more preferably 3 to 45% by weight and most preferably 5 to 40% by weight of water-soluble inorganic salt. The organic acid and water-soluble insoluble may be selected in a combination that it serves an effervescent source in the tablet. Such combination further accelerates the dissolution of the tablet in contact with water. Example of such combination includes bicarbonate/carbonate salt with select organic acid, like citric. The bicarbonate/carbonate salt and the organic acid may be considered in a ratio 10:1 to 1:10, more preferably 5:1 to 1:5, most preferably 3:1 to 1:3 by weight. Most preferably, the ratio of the bicarbonate salt to the organic acid or salt of organic acid or salt of inorganic acid is 1 :1.

Further ingredient

The tablet may further comprise a cationic surfactant in addition to the anionic and/or the nonionic surfactant.

Suitable cationic surfactants are quaternary ammonium salts. According to the present invention quaternary ammonium salts are characterised in that the ammonium salt has the general formula: R1 R2R3R4N+X- wherein R1 is a C12 to C18 alkyl group, each of R2, R3 and R4 independently is a C1 to C3 alkyl group and X is an inorganic anion. R1 is preferably a C14 to C16 straight chain alkyl group, more preferably C16. R2, R3 and R4 are preferably methyl groups. The inorganic anion (X-) is preferably chosen from halide, sulphate, bisulphate or hydroxide.

For the purposes of this invention, a quaternary ammonium hydroxide is considered to be a quaternary ammonium salt. More preferably the anion is a halide ion or sulphate, most preferably a chloride or sulphate. Cetyl-trimethylammonium chloride is a specific example of a suitable compound and commercially abundantly available.

Another type of quaternary ammonium cationic surfactant is the class of benzalkonium halides, also known as alkyldimethylbenzylammonium halides. The most common type being benzalkonium chloride, also known as alkyldimethylbenzylammonium chloride (or ADBAC).

An amphoteric surfactant may also present in the tablet in addition to the anionic and/or the non-ionic surfactant.

Suitable amphoteric surfactants include derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising group, for instance 3- (N-N-dimethyl-N-hexadecylammonium) propane-1 -sulphonate betaine, 3-(dodecylmethyl sulphonium) propane-1 -sulphonate betaine and 3- (cetylmethylphosphonium) ethane sulphonate betaine.

Examples of amphoteric surfactants suitable for the present invention include cocoamidopropyl betaine (CAPB), cocoamidopropyl amine oxide (CAPAO), cocodiethanol amide (CDEA) and cocomonoethanol amide (CMEA).

The tablet may comprise a sequestrant. Examples include the alkali metal, citrates, succinates, malonates, carboxymethyl succinates, carboxylates, polycarboxylates and polyacetyl carboxylates. Specific examples include sodium, potassium and lithium salts of oxydisuccinic acid, mellitic acid, benzene polycarboxylic acids, and citric acid. Other examples are DEQUEST™, organic phosphonate type sequestering agents sold by Monsanto and alkanehydroxy phosphonates.

The tablet may comprise 0.1 to 6% by weight, more preferably 0.2 to 5% by weight, even more preferably 0.3 to 4% by weight and most preferably 0.5 to 3% by weight of the sequestrant. A preferred sequestrant is Dequest® 2066 (diethylenetriamine penta(methylene phosphonic acid) or heptasodium DTPMP). Other suitable sequestrant is 1 -hydroxyethylidene -1 ,1 ,-diphosphonic acid (HEDP) and methylglycinediacetic acid (MGDA), glutamic acid diacetic acid tetra sodium salt (GLDA). Most preferred sequestrant is methylglycinediacetic acid (MGDA) and/or glutamic acid diacetic acid tetra sodium salt (GLDA).

Fracture Stress

It is desired the tablet has certain hardness to resist breakage during handling/transportation.

One of the ways to assess the hardness of the tablet is diametrical fracture stress (DFS). The tablet preferably has a diametral fracture stress (DFS) ratio of DFS_air/DFS_water of at least 6, preferably at least 7, preferably at least 8 more preferably at least 9.

More preferably, the tablet has a diametral fracture stress (DFS) ratio of DFS_ajr/DFS_water in the range of 6 to 50, preferably 7 to 45.

The DFS_air/DFS_water ratio can be measured using techniques known to the skilled person. The DFS can be measured using a texture analyser, for example a CT3 Brookfield Texture Analyser. For examples, the DFSair/DFSwater can be measured using a TA instrument, model TA-XT2i and the Texture Experte software (Texture Technologies Corp., Scarsdale, NY, USA/- Stable Micro Systems, Surrey, England, UK). The instrument is calibrated with a 5 kg load cell and fitted with a stainless steel flat-bottomed cylindrical probe with 1 cm2 surface area (Kobe probe). The methodology consists in positioning the tablet to the flat surface of the probe. The probe moves until a trigger force is detected at which point the TA is set to maintain a predetermined nominal force for a given time (60 sec). As the tablet starts disintegrating, the TA measures the penetration distance as the tablet is compressed while submerged in the medium (water). A constant temperature of the medium of 18°C is maintained during the tests by means of a thermos stated double wall cell and a heating bath/circulator (Haake, Karlsruhe, Germany).

The tablet may be formulated for hard surface cleaning. Hard surfaces, herein includes the surfaces in household, such as, kitchen utensils, floor, tiles, dishes, kitchen platform, tabletop etc. Consumers may dose a tablet in a bucket of water and allow it to dissolve thereby forming a cleaning composition. The composition thereon may be used for cleaning surfaces like tiles and floors.

It may also possible that consumers dose a tablet in a container or bottled filled with water, and prepare a hard surface cleaner, which can be stored and used at later stage.

The tablet according to the present invention may be provided along with a container having sufficient empty space. Consumers may fill the container with water, preferably up to a pre-set mark and dose the tablet. The tablet dissolves in the water thereby providing a cleaning product. Preferably, container is transparent or translucent and the composition appears visually clear. Such arrangement often provides a visual cue to the consumers. ‘Visually clear’ or ‘transparent’ in the composition context, refers to a liquid having a turbidity value less than 50 NTU (Nephelometric Turbidity Unit), more preferably less than 30NTU, even more preferably 20 NTU and most preferably 10 NTU. The container may be equipped with a spray head or foam engine, which helps in dispensing the cleaning composition directly on the surface as spray or foam.

According to the present invention, there is provided a hard surface cleaner obtained by dissolving the tablet in water, wherein the ratio of the tablet to water is in the range 1:5 to 1 :100 by weight. Preferably the ratio of the tablet to water is in range 1 :7 to 1 :80 by weight, more preferably 1 :9 to 1:60 by weight and most preferably 1:10 to 1:50 by weight. The hard surface cleaner may be obtained by following the steps of, taking a container, filling the container with water, dosing the tablet and optionally shaking the container. The hard surface cleaner may be stored and used at later stage. Preferably the tablet free of insoluble and the hard surface obtained is transparent. The term ‘free of insoluble’ herein indicates that the tablet contains less than 5% by weight, more preferably less than 3% by weight, even more preferably less than 1% by weight and most preferably less than 0.5% by weight insoluble compounds. In certain scenario the tablet does not contain an insoluble compound. The term ‘transparent’ here in implies that the hard surface cleaner appears to be visually clear or the liquid having turbidity value less than 50 NTU (nephelometric turbidity unit), more preferably less than 30 NTU and most preferably less than 10 NTU.

According to the present invention, there is also provided a process for cleaning a surface comprising steps of: providing water in a container or bucket, adding and dissolving the tablet into the water, wherein the ratio of the tablet to water is in the range from 1:50 to 1:1000 by weight, thereby providing a liquid cleaning composition; and, applying the cleaning composition on the surface and cleaning it. Preferably the ratio of the tablet to water is in the range of 1:75 to 1:800 by weight, more preferably 1:100 to 1 : 600 by weight, most preferably 1:150 to 1:500 by weight. Preferably the cleaning composition is intended for immediate use and may not be stored for later use. Consumers may use an applicator or implement, such as, cloth, wipe, brush, mop to apply the cleaning composition and optionally rinse the surface with water.

Process of making tablet

Preferably, tablets are prepared following conventional tablet making process. In the process a homogenised dry powder is prepared by mixing the ingredients in specified ratio. Subsequently, the powder is filled in a die-block and compressed to form the tablet. A rotary press or a hydraulic press maybe employed to compress the powder to tablet.

Preferably the pressure applied during the compression is in the range 1 to 100 kg-f/cm2, more preferably 2 to 80 kg-f/cm2, even more preferably 3 to 60 kg-f/cm2, and most preferably 4 to 50 kg-f/cm2.

Dry mix compositions were prepared according to the recipes provided in table 1. In subsequent step, 10 gm of each dry mix composition was taken in die-block and compressed by applying a pressure of 5 kg-f/cm2, thereby forming the tablet.

For evaluating the performance of the tablets made by said process, each tablet was added in 350 mL water and allowed to dissolve. The dissolution time of each tablet was noted using a stopwatch. Dissolution time herein refers to the time taken by each tablet to dissolved completely in water leaving no residue. Ex- 1 to 3 and Ex- A to C were prepared following the recipe provided in table 1 for evaluating cleaning efficacy on greasy kitchen soil and dissolution.

Table 1

* Sodium linear alkyl benzene sulphonate (80% w/w active) from Unger Fabrikker AS. ^# C16 to C18 alcohol ethoxylate from BASF.

Soiled plate mimicking greasy kitchen soil was prepared by depositing hydrogenated castor oil on 5 x5 cm steel plate. The plate was baked at 100° C for 75 minutes. Each tablet was dissolved in water in a ratio 1 :10 by weight forming a liquid cleaning composition. Thereon, 20 gm of each liquid cleaning composition was dosed on the plate and applied with an applicator. Subsequently each plate was washed, and amount of soil removed was estimated by gravimetry. The data for cleaning efficacy is summarised in table 2.

From table 1 , it is evident that Ex-1 to 3 having mix surfactants deliver improved soil removal compared to example A, B and at par with C. Further, Ex-1 to 3 dissolve significantly faster than A, B.

Claims

Claims:

1. A unit dose tablet comprising: a) 5 to 40 % by weight of an anionic surfactant; b) 5 to 75 % by weight of a non-ionic surfactant; and c) a water-soluble disintegrant is selected from hydrated monosaccharides, hydrated disaccharides, hydrated oligosaccharides and combinations thereof, wherein ratio of the anionic surfactant to the non-ionic surfactant is in the range from 1:1 to 1 :5 by weight.

2. A tablet as claimed in claim 1 wherein the anionic surfactant is selected from primary alkyl sulphate, alkyl benzene sulphonates, alkyl ether sulphates, alkyl cocoyl taurate and combinations thereof.

3. A tablet as claimed in claim 2 wherein the anionic surfactant comprises alkyl cocoyl taurate.

4. A tablet as claimed in any one of claims 1 to 3 wherein the amount of the non-ionic surfactant is in the range 10 to 60% by weight of the tablet.

5. A tablet as claimed in any of claims 1 to 4 wherein the non-ionic surfactant is selected from alcohol ethoxylate, alkyl polyglycoside and combinations thereof.

6. A tablet as claimed in claim 5 wherein the tablet comprises at least 10% by weight of alcohol ethoxylate as non-ionic surfactant.

7. A tablet as claimed in any one of claims 1 to 6 wherein ratio of the anionic surfactant to the non-ionic surfactant is in the range from 1 :1 to 1 :4 by weight.

8. A tablet as claimed in any one of claims of 1 to 7 wherein the ratio of the anionic to the non-ionic surfactant is in the range 1 :2 to 1 :4 by weight.

9. A tablet as claimed in any one of claims 1 to 8 wherein the amount of the water -soluble disintegrant is in the range from 10 to 90% by weight of the composition.

10. A tablet as claimed in claim any one of claims 1 to 9 wherein the water-soluble disintegrant is glucose monohydrate.

11. A tablet as claimed in any one of claims 1 to 10 further comprising a hydrotrope.

12. A hard surface cleaner obtained by dissolving a tablet as claimed in any one of claims 1 to 11 wherein the ratio of tablet to water is in the range from 1 :5 to 1:100 by weight.

13. A process for cleaning a surface comprising the steps of: a) providing water in a container; b) adding and dissolving a tablet as claimed in any one of claims 1 to 11 into the water, wherein the ratio of the tablet to water is in the range from 1:50 to 1 :1000 by weight, thereby providing a liquid cleaning composition; and c) applying the cleaning composition on the surface and cleaning it.