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Title:
POWDER COMPOSITION FOR HARD SURFACE CLEANING
Document Type and Number:
WIPO Patent Application WO/2016/096328
Kind Code:
A1
Abstract:
The disclosed powder composition comprises: (i) 5 wt% to 30 wt% anionic surfactant; (ii) 0.5 wt% to 10 wt% water-swellable polymer; (iii) 10 wt% to 30 wt% salt of Sodium which is either Sodium sulphate or Sodium silicate or a mixture thereof. The composition further comprises 45 wt% to 80 wt% stabilising agent which is either solely an abrasive with Moh's index of at least 3.5 or a combination of said abrasive and a water-swellable clay, where for every part by weight of said salt of Sodium, the composition comprises 1.5 to 8 parts by weight of said stabilising agent.

Inventors:
ARNIPALLY SUMANTH KUMAR (IN)
DAGAONKAR MANOJ VILAS (IN)
KOTTUKAPALLY JIJI PAUL (IN)
NADAKATTI SURESH MURIGEPPA (IN)
SHAH KUNAL DHIRAJLAL (IN)
Application Number:
EP2015/077434
Publication Date:
June 23, 2016
Filing Date:
November 24, 2015
Export Citation:
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Assignee:
UNILEVER NV (NL)
UNILEVER PLC (GB)
CONOPCO INC DBA UNILEVER (US)
International Classes:
C11D11/00; C11D1/02; C11D3/04; C11D3/08; C11D3/12; C11D3/14; C11D3/37
Domestic Patent References:
WO2001077273A12001-10-18
WO2004046292A12004-06-03
WO1996035771A11996-11-14
WO2004046292A12004-06-03
WO2001077273A12001-10-18
WO1996035771A11996-11-14
Foreign References:
EP2243822A12010-10-27
EP2138563A12009-12-30
US6673766B12004-01-06
US4704222A1987-11-03
US20070249514A12007-10-25
JPH0229497A1990-01-31
EP13199803A2013-12-30
EP2243822A12010-10-27
Other References:
SCHWARTZ; PERRY: "Surface Active Agents", vol. 1, 1949, INTERSCIENCE
SCHWARTZ; PERRY; BERCH: "SURFACE ACTIVE AGENTS", vol. 2, 1958, INTERSCIENCE
"McCutcheon's Emulsifiers and Detergents", MANUFACTURING CONFECTIONERS COMPANY
H. STACHE: "Tenside-Taschenbuch. 2nd ed.", 1981, CARL HAUSER VERLAG
Attorney, Agent or Firm:
CORSTEN, Michael, Allan (Unilever Patent Group Olivier van Noortlaan 120, AT Vlaardingen, NL)
Download PDF:
Claims:
Claims

1. A powder composition comprising:

(i) 5 wt% to 30 wt% anionic surfactant;

(ii) 0.5 wt% to 10 wt% water-swellable polymer; and,

(iii) 10 wt% to 30 wt% salt of Sodium which is either Sodium sulphate or

Sodium silicate or a mixture thereof;

wherein said composition further comprises 45 wt% to 80 wt% stabilising agent which is either solely an abrasive with Moh's index of at least 3.5 or a combination of said abrasive and a water-swellable clay, where for every part by weight of said salt of Sodium, the composition comprises 1.5 to 8 parts by weight of said stabilising agent.

2. A powder composition as claimed in claim 1 wherein, when said water-swellable clay is present in said stabilising agent in addition to said abrasive, the content thereof is from 0.5 wt% to 10 wt% of said composition.

3. A powder composition as claimed in claim 1 or 2 wherein said water-swellable polymer is one or more of polyacrylic acid, polyacrylate, cross-linked acrylate, guar gum or its derivative, starch-acrylic grafted copolymer, hydrolysate of starch- acrylonitrile grafted copolymer, crosslinked polyoxyethylene, cross-linked methyl cellulose, sodium carboxymethylcellulose or partially cross-linked water-swellable polymer of polyethylene oxide and polyacrylamide or isobutylene/maleic acid copolymer.

4. A powder composition as claimed in claim 1 wherein said water-swellable

polymer is sodium carboxymethyl cellulose.

5. A powder composition as claimed in any one of the preceding claims 1 to 4

wherein said water-swellable clay comprises one or more of Montmorillonite, Laponite, Hectorite, Nontronite, Saponite, Volkonsite, Sauconite, Beidellite, Allevarlite, lllite, Halloysite, Attapulgite, Mordenite, Kaolines, or Bentonite.

6. A powder composition as claimed in claim 5 wherein said clay is Bentonite.

7. A powder composition as claimed in any one of the preceding claims 1 to 6 wherein mixing one part by weight of said composition with one to three parts by weight of water provides a paste having viscosity of 5000 to 12000 cP at 25 °C.

8. An aqueous paste composition having viscosity of 5000 to 12000 cP at 25 °C, comprising 25 wt% to 50 wt% composition of claim 1 , the balance being water.

Description:
POWDER COMPOSITION FOR HARD SURFACE CLEANING Field of the invention The present invention relates to a composition for cleaning hard surfaces, in particular to a powder composition convertible into an aqueous paste for cleaning utensils or other hard surfaces.

Background of the invention

Dishwashing compositions are available in three well-known formats. A bar is the most preferred format in South Asian countries. The other two formats, gel and liquid, are used widely in developed countries. US4704222 B1 discloses an aqueous gel for cleaning hard surface compositions. Like other similar compositions, it also has an abrasive, a gelling agent (clay or polymer), a surfactant and water.

US2007/0249514 A1 (P&G) also discloses a gelled composition having 0.01 % to 5% rheology modifying system made up of anionic/cellulosic polymer and a surfactant.

In some countries people still use abrasive powder compositions or even proxy products like detergents or ash for cleaning utensils. Such abrasive powder

compositions consist almost entirely of an abrasive and a small amount (ca. 5%) of a foaming surfactant. The composition is applied directly onto a soiled surface and then the surface is cleaned with a scrubber using a small amount of water. The surfactant aids the cleaning process by improving wetting behavior of the water/abrasive mix on the surface and it further provides visual cue of cleaning due to foam that gets generated.

JP2029497 A2 (Sekisui Plastics) describes one such ready-to-use abrasive powder which contains hydroxyapatite and surfactant. Such abrasive compositions cannot be converted easily into a paste which remains stable. This happens because the surfactant does not form the lamellar micellar phase which is essential to keep solid abrasives in stable suspended form. In such cases, it is often observed that the abrasive quickly separates from the rest of the pasty medium.

A new kind of format (powder-to-paste) was disclosed in WO04/46292 A1 and

WO01/77273 A1 (Unilever). The composition of WO'292 has a surfactant and water- swellable polymer. The composition turns into a voluminous paste when mixed with prescribed amount of water. The paste is used for cleaning soiled dishes. A typical composition contains about 20% anionic surfactant, about 20% cross-linked polyacrylic acid, about 4 wt% alkaline silicate and about 55 % abrasive.

On the other hand, the powder composition disclosed in WO'273 is water dispersible and it forms an abrasive paste. The dry powder contains an abrasive, a foaming surfactant and a suspending system to stabilise the paste. The suspending system contains an anionic surfactant, a nonionic surfactant and an electrolyte.

Our co-pending unpublished European application number EP13199803.1 also discloses a similar product which contains 35 to 60 wt% swelling agent composition containing a water-swellable polymer and water-swellable clay. It also contains 5 to 50 wt% surfactant. The ratio between the water- swellable polymer and the water- swellable clay is 1 :3 to 1 :13.

The product format disclosed in WO04/46292 A1 , WO0177273 A1 and EP13199803.1 is innovative and user friendly because from manufacturer's point of view it is a sustainable powder therefore easier and cost-effective to manufacture, store, package and transport. On the other hand, from the user's point of view, it is a product (powder) which is convenient to store and the end-product (i.e., the aqueous paste) can be made afresh in the required quantity each time the user needs some.

W096/35771 A1 (Reckitt & Colman) discloses a thickened hard surface cleansing composition which has abrasive particles, a chlorine-containing bleach, a thickening system made up of cross-linked polyacrylate resin and a synthetic smectite clay. The composition also contains surfactant, an electrolyte which is carbonate or silicate of sodium or potassium and sufficient amount of sodium or potassium hydroxide.

Reference has been made to the effect of ionic strength of the gel on its viscosity and it has also been disclosed that ionic strength should preferably be kept lower than 5 g- ions/kg. However, no reference has been made to any particular manner of balancing the ionic strength.

It is found that pastes prepared from a precursor powder do not remain stable for long time, although consumers always prefer stable products. Sometimes the paste separates into a watery phase and a powdery phase within hours of preparation. There is no known solution for this technical problem.

We found that a detergent base powder offers a promising starting point to make a hard surface cleaning powder which can be converted into a paste. The term detergent base powder is explained, for example, in EP2243822 A1 (Unilever, 2010). A base powder is a premix which forms the base or bulk of a fully formulated detergent powder. The base powder is usually post-dosed with ingredients like perfume, colour granules and builders to make a fully formulated detergent powder. In order to convert a detergent base powder into an abrasive hard surface cleaning composition which further can be converted into an aqueous paste, the only ingredients that necessarily need to be added are an abrasive and a thickening agent.

However, such pastes are prone to phase separation. Without wishing to be bound by theory, it is believed that high levels of inorganic alkali metal salts like sulphates and silicates, which are invariably present in detergent base powders, cause instability, at least in part.

This poses a technical problem of providing a powder hard surface cleaning

composition which can be used to provide a stable paste upon mixing with water in recommended proportions. Summary of the invention

We have determined that the powder composition should have proper balance between some of the ingredients as hereinafter disclosed.

In accordance with a first aspect is disclosed a powder composition having:

(i) 5 wt% to 30 wt% anionic surfactant;

(ii) 0.5 wt% to 10 wt% water-swellable polymer; and,

(iii) 10 wt% to 30 wt% salt of Sodium which is either Sodium sulphate or Sodium silicate or a mixture thereof;

wherein the composition further includes 45 wt% to 80 wt% stabilising agent which is either solely an abrasive with Moh's index of at least 3.5 or a combination of the abrasive and a water-swellable clay, where for every part by weight of the salt of Sodium, the composition comprises 1.5 to 8 parts by weight of the stabilising agent.

In accordance with a second aspect is disclosed an aqueous paste composition having viscosity of 5000 to 12000 cP at 25 °C, where the paste includes 25 wt% to 50 wt% composition of the first aspect, the balance being water. The invention will now be explained in details.

Detailed description of the invention

In the context of the present invention, the reference to "powder composition" means compositions in the form of a solid powder, tablet, granules or pellets.

In the context of the present invention, the reference to "hard surface" typically means utensils or kitchenware, kitchen tops, kitchen floors, sinks and platforms, floors and bathrooms.

Surfactant The compositions of the present invention comprise 5 to 30 wt% anionic surfactant, which is primarily responsible for cleansing action. Preferred compositions have 5 wt% to 20 wt% anionic surfactants and more preferred compositions have 10 to 15 wt% anionic surfactants. In the detergents industry it is customary to indicate the total surfactant content of a composition as the AD (Active Detergent) level. Thus, a formulation containing 5 wt% of total surfactant is identified as 5 AD formulation.

Anionic surfactants are included in the composition for primary cleaning action by emulsifying the oil attached to the substrate.

Preferred classes of anionic surfactants include water-soluble salts of organic sulphuric acid mono-esters and sulphonic acids having in the molecular structure a branched or straight chain alkyl group containing 8 to 22 carbon atoms or an alkylaryl group containing 6 to 20 carbon atoms in the alkyl part.

Examples of such anionic surfactants are water soluble salts of:

long chain (i.e. 8 to 22 carbon atoms) alcohol sulphates (hereinafter referred to as PAS), especially those obtained by sulphating the fatty alcohols produced from tallow or coconut oil or the synthetic alcohols derived from petroleum; alkylbenzene-sulphonates, such as those in which the alkyl group contains from 6 to 20 carbon atoms; and

secondary alkanesulphonates.

Also suitable are the salts of:

- alkylglyceryl ether sulphates, especially of the ethers of fatty alcohols derived from tallow and coconut oil;

- fatty acid monoglyceride sulphates;

sulphates of ethoxylated aliphatic alcohols containing 1 to 12 ethyleneoxy groups;

- alkylphenol ethylenoxy-ether sulphates with from 1 to 8 ethyleneoxy units per molecule and in which the alkyl groups contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralised with alkali. The powder composition preferably also includes one or more additional surfactants generally selected from non-ionic, cationic, zwitterionic or amphoteric surfactants. Suitable nonionic surfactants can be broadly described as compounds produced by the condensation of simple alkylene oxides, which are hydrophilic in nature, with an aliphatic or alkyl-aromatic hydrophobic compound having a reactive hydrogen atom. The length of the hydrophilic or polyoxyalkylene chain which is attached to any particular hydrophobic group can be readily adjusted to yield a compound having the desired balance between hydrophilic and hydrophobic elements. This enables the choice of nonionic surfactants with the right HLB. Particular examples include:

the condensation products of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut alcohol/ethylene oxide condensates having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol;

- condensates of alkylphenols having C6 to C15 alkyl groups with 5 to 25 moles of ethylene oxide per mole of alkylphenol;

condensates of the reaction product of ethylene-diamine and propylene oxide with ethylene oxide, the condensates containing from 40 to 80% of ethyleneoxy groups by weight and having a molecular weight of from 5,000 to 1 1 ,000.

Suitable amphoteric surfactants include derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilizing group, such as sodium 3-dodecylamino- propionate, sodium 3-dodecylaminopropane sulphonate and sodium N-2- hydroxydodecyl-N-methyltaurate.

Suitable cationic surfactants are quaternary ammonium salts of the general formula: Ri R2R3 4 N + X " , wherein Ri is a C12-C18 alkyl group, each of R2, R3 and R 4

independently is a C1-C3 alkyl group and X is an inorganic anion. Ri is preferably a Cu- C16 straight chain alkyl group, more preferably C16. R2-R 4 are preferably methyl groups. The inorganic anion is preferably chosen from halide, sulphate, bisulphate or OH " . 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 is alkyldimethylbenzylammonium chlorides, particularly benzalkonium chloride.

Suitable zwitterionic 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. Further examples of suitable surfactants are compounds commonly used as surface- active agents given in the well-known textbooks like "Surface Active Agents" Vol. 1 , by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, and/or the current edition of "McCutcheon's Emulsifiers and Detergents" published by Manufacturing Confectioners Company or in "Tenside-Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981 .

The stabilising agent:

The stabilising agent is either solely an abrasive with Moh's index of at least 3.5 or a combination of the abrasive and a water-swellable clay. For every part by weight of the salt of Sodium, the composition includes 1.5 to 8 parts by weight of the stabilising agent. In preferred compositions for every part by weight of the salt of Sodium, the composition includes 1.8 to 7.4 parts by weight of the stabilising agent. It is further preferred that for every part by weight of the salt of Sodium, the composition includes 2.8 to 6.2 parts by weight of the stabilising agent.

Abrasive: The powder composition also contains 35 to 80 wt% abrasive having Moh's index at least 3.5. Preferred compositions have 38 to 78 wt% abrasive. Where the quantity of the abrasive is less than 45 wt%, the stabilising agent includes water-swellable clay such that the minimum level of stabilizing agent, i.e., 45 wt% is present in the composition. For example, if a composition contains 35 wt% abrasive, then it also must have at least 10 wt% of the water-swellable clay such that the composition then contains at least the minimum level of the stabilising agent.

Alternatively, in the case of compositions in which the abrasive is the sole stabiling agent, the compositions contain 45 to 80 wt% abrasive having Moh's index at least 3.5. The abrasive can be any fine particulate solid known in the art for its suitability as an abrasive material. Most of the known materials are insoluble in water, however, suitable materials, which are water-soluble, are known as well. When the abrasive content is less than the minimum quantity of the stabilising agent, the composition necessarily contains a water-swellable clay.

The abrasive has Moh's index (hardness index) of at least 3.5. Harder abrasives can be employed for special applications. Generally, the lower the hardness of the abrasive materials the lesser the surface damage, although a hardness of 1 or more is preferred to give sufficient cleaning capability. In preferred compositions, the abrasive is dolomite, feldspar, apatite, fluorite and hematite, kyanite, magnetite, orthoclase or pumice. The abrasive may be water soluble or insoluble.

Suitable water-insoluble abrasives are synthetic as well as naturally occurring materials (minerals) and examples include zeolite, silica, silicates, carbonates, alumina and organic polymeric abrasives such as polyethylene, polycarbonate, polyurethane, polystyrene, polypropylene, polyethylene terephthalate, polymethylmethacrylate and nylon, and mixtures thereof. Preferred abrasives are mixtures of calcium and magnesium carbonates (as dolomite), zeolite, alumina, hydrated alumina, feldspar, talc and silica. It is particularly preferred that the abrasive is feldspar.

Preferred water-soluble abrasives include sodium carbonate, sodium bicarbonate, sodium tripolyphosphate, sodium borate and potassium sulphate. The stabilising agent is either solely an abrasive with Moh's Index of at least 3.5 or a combination of the abrasive with a water-swellable clay, totaling in the aggregate to 45 to 80 wt% of the composition. Water-swellable clay

When the water swellable clay is present in the stabilising agent in addition to the abrasive, it is preferred that the content thereof is from 0.5 wt% to 10 wt% of the composition. It is preferred that its swelling index is 15 to 30. In preferred compositions, the water-swellable clay comprises at least one of Montmorillonite, Laponite, Hectorite, Nontronite, Saponite, Volkonsite, Sauconite, Beidellite, Allevarlite, lllite, Halloysite, Attapulgite, Mordenite, Kaolines, or Bentonite. Kaoline or Bentonite..

Water-swellable polymer

A third component is a water-swellable polymer. The composition contains 0.5 to 10 wt% water-swellable polymer. In preferred compositions the water-swellable polymer is one or more of polyacrylic acid, polyacrylate, cross-linked acrylate, guar gum or its derivative, starch-acrylic grafted copolymer, hydrolysate of starch-acrylonitrile grafted copolymer, crosslinked polyoxyethylene, cross-linked methyl cellulose, sodium carboxymethylcellulose or partially cross-linked water-swellable polymer of

polyethylene oxide and polyacrylamide or isobutylene/maleic acid copolymer. More preferred compositions contain 1.5 wt% to 3 wt% and further more preferred compositions contain 1.8 wt% to 2.5 wt% polymer.

A particularly preferred water-swellable polymer is sodium carboxymethylcellulose. More preferably, its degree of substitution is in the range of 0.7 to 0.95.

The salt of Sodium

The powder compositions of the present invention contains 10 wt% to 30 wt% salt of Sodium which is either Sodium sulphate or Sodium silicate or a mixture thereof. Where the composition contains Sodium sulphate and Sodium silicate then their cumulative content is 10 wt% to 30 wt%. The origin of this ingredient may be in the corresponding detergent base powder, especially if the base powder has been produced by spray drying route. It is believed that the cause of instability is an imbalance between the Sodium salt(s) and the abrasive. At ratios outside the claimed range, the base powder composition is stable but the aqueous ready-to-use paste made therefrom by mixing it with water is very unstable and is easily prone to phase separation. The problem cannot be solved by lowering the amount of water by making concentrated pastes.

The invention enables a manufacturer to use a detergent base powder to formulate a cleansing composition for hard surfaces by appropriately balancing some the ingredients of the composition.

Thus it is preferred that the powder composition is such that mixing one part by weight of the composition with one to three parts by weight of water yields a paste having viscosity of 5000 to 12000 cP at 25 °C.

Optional ingredients:

Furthermore, the powder compositions may contain other optional ingredients to increase attractiveness to the consumer, such as colorants, optical brighteners and particularly perfumes, preservatives and bactericides, free-flowing agents, dispersing agents and antifoam.

The powder composition may have any form, which is suitable for easy dispersion in water, such as granules, prills or even compacted tablets. Spray-drying, fluid bed drying, granulation and similar processes known in the art are very suitable to obtain products which are free-flowing and easily dispersible without lumping. For granulation, the addition of a granulating aid such as a polyethylene glycol with molecular weight of 1500-4000 D may be useful.

Tablets may be obtained by compaction of a predetermined amount of the powder composition. They may contain a disintegration aid to improve dispersion in water. Such disintegration aids are well known in the art of laundry and machine dish-wash tablets.

A preferred powder composition is one wherein mixing one part by weight of the composition with one to three parts by weight of water provides a paste having viscosity in the range of 5000 to 12000 cP at 25 °C.

The viscosity can be measured by any known means/procedure. It is preferred that viscosity is measured by a Controlled-stress Rheometer, Ex. TA Instruments AR 1000 series. The parallel flat plate geometry having diameter of 4 cm was used. The gap between the plate and the base was set to 1000 mm. Data was analyzed by the TA data analysis software. A sample of the paste is placed on the base and the plate is brought to the set geometry gap. The viscosity is measured at 21 s "1 . Thus a ready-to-use hard surface cleaning composition in the form of paste can be obtained from the powder compositions by adding a suitable amount of water.

The readv-to-use paste In accordance with a second aspect is disclosed an aqueous paste composition having viscosity in the range of 5000 to 12000 cP at 25 °C, said composition having 25 wt% to 50 wt% of the powder composition of the first aspect, the balance being water.

The powder composition is user-friendly for the consumer as the user to obtain a ready-to-use hard surface cleaning paste can mix it with water.

The invention will now be illustrated by means of the following non-limiting examples. Examples Example 1 : Preparation of compositions outside and inside the invention

The powder compositions outside and inside the scope of the invention were made by using a common detergent base powder (as given in Table 1 ). The base powder was mixed with an abrasive and/or clay as described hereinafter to make the powder compositions, which were further mixed with water to make corresponding paste compositions, also within and outside the scope of the invention.

Table 1

A powder composition outside the invention (C1 of table 2) was prepared by mixing 60 g of the above detergent base powder with 38 g feldspar and 2 g sodium carboxy methyl cellulose.

An inventive powder composition (E1 ) was prepared by mixing 40 g of the above detergent base powder with 58 g feldspar and 2 g sodium carboxy methyl cellulose. Another inventive powder composition (E2) was prepared by mixing 50 g of the detergent base powder as described above with 38 g feldspar, 10 g bentonite clay and 2 g sodium carboxy methyl cellulose.

Yet another inventive powder composition (E3) was prepared by mixing 20 g of the detergent base powder as described above with 78 g feldspar and 2 g sodium carboxy methyl cellulose.

One part by weight of each powder (C1 and E1 -E3) composition (100 g) was mixed with one part by weight of water (100 g) to provide pastes having viscosity of 6000 cP at 25 °C. Therefore each paste composition had 50% of the powder composition of the first aspect of this invention and the balance was water. The viscosity of each paste composition was measured at time zero, after 3 hours of preparation, after 6 hours of preparation and finally after 3 days of preparation. During this entire period the temperature of each paste composition was maintained around 25 °C. The final compositions of each powder thus obtained, along with observations stability of the respective pastes is shown in Table 2.

Table 2

Note: (1 ) Wherever the word unstable is used, the viscosity was observed to be significantly lower than 5000 cP at 25 °C.

Note (2) Wherever the word stable is used, the viscosity was observed to be in the range of 5000 to 12000 cP at 25 °C.

Note (3) The stabilizing agent was as follows:

(a) For C1 - Feldspar only

(b) For E1 - Feldspar only

(c) For E2 - Feldspar and Bentonite clay

(d) For E3 - Feldspar only Data in table 2 indicates that C1 , the composition outside the scope of this invention, does not have the required quantity of stabilising agent. Therefore the corresponding paste was found to be unstable after some hours of preparation. E1 , the composition inside the scope of the invention formed a stable paste because it contained 58 wt% stabilising agent (solely the abrasive) and further for every part by weight of the salt of Sodium, the powder composition had 2.84 parts by weight of the stabilising agent. Similarly E3 formed a correspondingly stable paste because it contained 78 wt% stabilising agent (solely the abrasive) and further for every part by weight of the salt of Sodium, the composition had 6.2 parts by weight of the stabilising agent.

Finally, E2 also formed a stable paste because it contains 48 wt% stabilising agent (abrasive+clay) and further for every part by weight of the salt of Sodium, the composition has 1.84 parts by weight of the stabilising agent.