GB1581433A - Scouring cleansers - Google Patents

Abstract

The novel scouring composition contains a surface-active agent and an abrasive powder. In this, less than 10 per cent by weight of the particles in the abrasive powder have a particle size above 150 mu m and less than 20 per cent by weight have a particle size below 10 mu m. The abrasive powder has, in particular, a hardness of from 1 to 4 on the Mohs' scale of hardness; it is preferably calcite. The abrasive powder advantageously has a particle size distribution curve within the region between the curves X in the figure, and even better within the region between the curves Y in the figure. The scouring composition is in the form of a free-flowing powder or liquid composition. <IMAGE>

Description

(54) SCOURING CLEANSERS (71) We, UNILEVER LIMITED, a company organised under the laws of Great Britain, of Unilever House, Blackfriars, London E.C.4, England, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to scouring cleansers, and to processes for their preparation.

Scouring cleansers contain as essential ingredients a surfactant and an abrasive powder.

Such products can take the form of powders, solid blocks, pastes and pourable liquids. The choice of material for use as abrasive in scouring cleansers has always involved making a compromise between efficiency in removing tough soils and minimising damage to delicate surfaces. In general hard abrasives and relatively large particles are good for removal of difficult soils such as burnt foodstuffs adhering to cooking utensils, whereas softer abrasives and smaller particles cause less scratching and other abrasion of substrates from which the soil is to be removed. It has long been recognised that fineness of the abrasive is of the greatest importance for a good and effective cleanser.

The usage in the scouring cleanser art has been to express particle size of abrasives in terms of proportions by weight of abrasive passing or held on a sieve of a given mesh number, or as a series of ranges of particle sizes in micro microns, or, less precisely, as an average particle size in microns. Micron sizes have reference to nominal diameters of particles, as it is not possible to define accurately the diameter of an irregular-shaped particle. Sieves are normally used for determination of particle sizes above about 40 microns, but for smaller sizes sieving is impracticable and various methods giving slightly differing results are employed. Mesh sizes corresponding to sieves are correlated with diameters in microns according to the system of sieve used.Using other methods, such as the Coulter (Registered Trade Mark) counter or the photosedimentometer methods, particle size is expressed in microns. In this specification particle size of abrasives is expressed in microns as mesh sizes provide inadequate definition.

The literature indicates that abrasives used in household scouring cleansers should have particle sizes mostly below 75 microns, and that particles of size within the range of 10 to 50 microns are particularly effective when calcite is used. The abrasive powders hitherto used in commercial household scouring cleansers have particle sizes ranging from below 1 micron to about 100 or 125 microns, with an average particle size of between 10 and 50 microns, irrespective of the material used as abrasive. In such abrasive powders there is a concentration of particles of from 10 to 50 microns diameter, with amounts of particles below and above this range decreasing as the difference from the average particle size increases. As abrasive powders incorporated in scouring cleansers are in practice made by grinding or crushing minerals, the powders obtained have a very wide range of particle sizes.As coarse particles tend to cause obvious scratching and very fine particles are ineffective as abrasives, the commercial producer of abrasive powders used in household scouring cleansers operates a sizereduction process in such a way as to produce an optimum average particle size and as narrow a range of particle sizes centred on this optimum as can be achieved without using a costly sieving step.

The particles size of an abrasive is expressed in detail as a distribution curve on a graph in which nominal diameters in microns are plotted against cumulative amounts of material in percent by weight. Such a graph is illustrated in the accompanying diagram, in which one axis represents the cumulative amount % by weight (W) of particles and the other represents particle diameter in microns (M). The particle size distributions of four abrasive powders which have been used extensively in household scouring cleansers, namely silica (A), felspar (B) and calcite (C and D) are given as curves.

The average particle sizes of the abrasives concerned are the sizes at which 50% by weight of the particles are larger and 50% are smaller, and are 22, 22, 27 and 15 microns respectively.

These abrasives all contain more than 25% and 10% by weight of particles below 10 and 5 microns respectively.

Scouring cleansers are applied to a soiled surface to be cleaned with a rubbing material such as a cloth or sponge in the presence of water; after the soil has been dislodged the rubbing material is rinsed in water, and used to wash away the soil and cleanser. It has now been observed that when a very glossy surface, for instance stainless steel or enamel, is cleaned with household scouring cleansers hitherto used it is often necessary to rinse the rubbing material more than once, for otherwise the surface is liable to have a dull appearance.In the course of investigating the effect of particle size on the performance of household scouring cleansers, it has now been discovered that the finest particles of abrasive present in commercial scouring cleansers are responsible for the dull film, particularly noticeable on glossy surfaces, which remains if rinsing has not been sufficiently repeated. Possibly the forces of attraction between the scoured surface and fine particles are such that the particles redeposit more easily than larger ones. It has been discovered that if the amount of these finest particles in the abrasive powder used in making the cleanser is reduced, the rinsing of glossy surfaces on which the cleanser has been used, with restoration of the gloss, is made more easy.It has also been discovered that many housewives have an established habit of rinsing out the rubbing material only once, which makes this easy rinsing of practical significance.

In accordance with these discoveries, the present invention provides a scouring cleanser comprising a surfactant and an abrasive powder or whose particles less than 10% by weight are of size above 150 microns and less than 20% by weight are of size below 10 microns, in which the abrasive powder has a Mohs hardness in the range of from 1 to 4, the abrasive powder having a particle size distribution curve wholly within the area bounded by the two curves Y of the accompanying diagram. Preferably the scouring cleanser contains 1 part of abrasive powder to from 0.001 to 10 parts of surfactant by weight.

Preferably the particle size of the abrasive is such that less than 20% is below 13 microns, especially below 15 microns. Preferably less than 15%, especially less than 10% is below 7,8 or 9 microns. Preferably also less than 8%, especially less than 5% is below 5,8 or even 10 microns. It is preferable to have substantially no particles below 1,2 or even 5 microns. The average particle size of the abrasive is preferably in the range of from 20 to 60 microns. Preferably at least 40% by weight of the abrasive powder is of particle size in the range from 15 to 70 microns. Preferably less than 5% is above 150 microns, less than 10% above 100 microns, and less than 12IASc above 90 microns. Preferably the abrasive powder contains substantially no particles of size above 125 microns.The particle size distribution curves of the abrasives in compositions of this invention are much steeper than those of abrasives hitherto used, as is illustrated in the accompanying diagram by curve E, which is typical of an abrasive suitable for use in a composition of the invention.

Suitable for use as materials of the abrasive are both natural and manufactured abrasives, having a hardness on Mohs scale of from 1 to 4, because it is such an abrasive that is most used in cleaning glossy surfaces and with which the easy rinsing effect is therefore particularly valuable, for example dolomite, precipitated calcium carbonate (aragonite) and calcite. Particularly suitable is calcite, for instance limestone, chalk or marble, such as those forms of calcite referred to in British Patent 1,345,119.

Suitable abrasive powders can be prepared by the standard techniques of crushing and grinding minerals until a material of average particle size from 20 to 50 microns is obtained, followed by elutriation of the resulting powder by air to carry off the finest particles, the air flow being adjusted in such a way as to achieve the grading desired. If too many large particles are present in the powder produced, these can be removed by appropriate sieving. The particle size distribution of a powder can be measured by standard methods including sieving for particles above about 50 microns, and use of a Coulter counter for particles below this.

Suitable as surfactants are any of the detergent-active compounds normally used in scouring cleansers, including anionic, nonionic, cationic, zwitterionic and amphoteric compounds. Suitable are soaps that are alkali metal salts of saturated fatty acids having from 10 to 24 carbon atoms. Suitable synthetic anionic detergents are alkali metal salts of sulphated and sulphonated hydrocarbons, especially those having from 12 to 26 carbon atoms in the molecule. Alkyl benzene sulphonates in which the alkyl group has from 8 to 16 carbon atoms can be employed.

Other surfactants and combinations of surfactants are those referred to for use in scouring cleanser compositions described in British Patents 822,569, 955,081, 1,007,342, 1,044,314 1,167,597, 1,181,607, 1,262,280, 1,303,810, 1,308,190, 1,345,119 and 1,418,671.

A scouring cleanser of the invention can contain adjuncts, especially builder salts such as sodium carbonate, trisodium orthophosphate and sodium tripolyphosphate, dyes, perfumes and salt electrolytes such as those referred to in the above patents. Particularly valuable are scouring cleansers that are free-flowing powders.

Such cleansers can contain from 0.1 to 40% by weight of surfactant, from So to 99% by weight of abrasive powder, and from 0 to 95% by weight of scouring cleanser adjuncts. Also particularly valuable are scouring cleansers that are pourable aqueous liquid compositions. Such cleansers can contain from 0.1 to 50% by weight of surfactant, and from 5 to 60% by weight of abrasive powder, the remainder being scouring cleanser adjuncts and water. Preferably the abrasive powder is dispersed in the aqueous medium of the cleanser, and this aqueous medium has Bingham plastic characteristics which maintain the abrasive powder in dispersion. Suitable aqueous media are those described in British Patents 1,167,597 1,181,607, 1,262,280, 1,303,810, 1,306,190 adn 1,418,671.

The invention includes a process for preparing a scouring cleanser comprising the step of incorporating the abrasive powders described above in the remainder of the scouring cleanser composition.

The invention is illustrated by the following Examples, in which amounts are by weight.

EXAMPLE 1 A commercial calcite powder made by grinding marble and having the particle size distribution shown as curve C in the accompanying diagram was subjected to grading by partial removal of fine particles. For this there was used a separator known as an Alpine Multiplex Laboratory Zig-Zag Classifier type 100 MZR, in which small particles are separated from large ones by sifting them in a current of air in rotating zigzag-shaped tubes, the centripetal force generated by rotation causing the particles to be thrown against the airflow. The separator was adjusted for removal of particles of size less than 10 microns, using a rotor speed of 8000 rpm and an airflow of 47m3 /hr. The calcite powder was separated into two fractions containing 73%a and 27% by weight of the material used.The coarse fraction was found to have the particle size distribution curve E shown in the accompanying diagram : the powder had about 4.3% of particles larger than 90 microns, an average particle size of 25 microns, and 15%, 9.5%, 3.5% and 1.5% of particles below 10,8,5 and 2 microns respectively. The slight decrease in average particle size of the coarse fraction as compared with the starting material despite the removal of fines is believed to be due to calcite particle disaggregation or shatter during separation.

A scouring powder was prepared by using the following ingredients: Parts Sodium dodecylbenzene sulphonate 0.82 Sodium sulpahte 0.18 Trisodium orthophosphate dodecahydrate 2.0 Calcite powder 97.0 This powder was used in the following test, in comparison with a corresponding scouring powder prepared using the commercial calcite powder used as starting material for preparing the fraction. Powder (2g) was placed on stainless steel plate of size 15 x 30 cm and sufficient water added to give a slurry of a consistency suitable for cleaning. The plate was rubbed with a wet sponge of size 4 x 4 x 15 cm under hand pressure until the abrasive was spread uniformly all over the plate. The sponge was then rinsed and the side of the clean wet sponge of largest area was drawn twice across the plate in such a way that the whole surface was sponged once using the same side.The plate was then allowed to dry and compared with an untreated plate for visibility of a residue by looking at the plates against a dark background with incident light from the side. While a marked opaque residue was obtained with this commercial calcite, there was no noticeable difference between the treated and untreated plates when the fractionated material was used.

EXAMPLE 2 A scouring powder is prepared from the following ingredients, using the coarser calcite fraction obtained in Example 1.

Parts Sodium dodecylbenze sulphonate 1.85 Sodium sulphate 0.50 Sodium carbonate 1.50 Sodium tripolyphosphate 2.00 Trichlorocyanuric acid 0.50 Perfume 0.20 Calcite powder 93.45 The perfume is incorporated by spraying it on to the triopolyphosphate powder, and the powdered ingredients then admixed, with the trichlorocyanuric acid added after mixing the other ingredients.

EXAMPLE 3 A liquid medium for a scouring cleanser was prepared from the following ingredients.

Parts Sodium n-dodecylbenzene sulphonate 3.88 Sodium sulphate 0.10 Cocoalkyldimethylamine oxide 6.12 Tetrapotassium pyrophosphate 10.00 Ethanol 5.00 Pine perfume 1.00 Water 73.90 To a solution of the pyrophosphate in water at 50 C were added with stirring the other ingredients excluding the perfume, the mixture allowed to cool to ambient temperature and the perfume then stirred in. Into 50 parts of the liquid medium with Bingham plastic characteristics thus obtained is stirred 50 parts of the coarser calcite fraction of Example 1 to give a liquid scouring cleanser.

EXAMPLE 4 A liquid medium for a scouring cleanser was prepared from the following ingredients.

Parts Sodium alkylbenzene sulphonate 5.3 Sodium sulphate 0.13 Potassium soap of groundnut oil acids 2.5 Condensation product of cocomonoethanolamide with 2.2 mols ethylene oxide 3.0 Sodium carbonate 3.5 Pine perfume 1.0 Water 84.57 To the water at 600C was added with stirring the sodium carbonate, sulphonate with sulphate, soap and condensate (in that order) to give a solution which was cooled to 25"C and the perfume stirred in.

Into 50 parts of the liquid medium with Bingham plastic characteristics thus obtained is stirred 50 parts of the coarser calcite fraction of Example 1 to give a liquid scouring cleanser.

EXAMPLE 5 A liquid medium for a scouring cleanser is prepared from the following ingredients: Parts Sodium alkylbenzene sulphonate 5.0 Sodium sulphate 0.13 Potassium soap of groundnut oil fatty acids 0.5 Cocodiethanolamide 4.0 Sodium tripolyphosphate 10.0 Pine type perfume 0.6 Water 79.77 To a solution of the phosphate in the water at 70"C was added with stirring the sulphate, soap and amide (in-that order) and the resulting solution was cooled to 350C and the perfume added, with stirring and cooling to ambient tem perature, to give a liquid medium having Bingham plastic characteristics.

To 50 parts of this liquid medium was added with stirring 60 parts of the coarser calcite frac tion of Example 1 to give a liquid scouring cleanser.

EXAMPLES 6 and 7 Liquid scouring cleansers are prepared as; described in Examples 1 and 7 of British Patent 1,418,671, except that instead of the felspar and calcite abrasives employed there, the coarser calcite fraction of the above Example 1 is used.

WHAT WE CLAIM IS: 1. A scouring cleanser comprising a surfac tant and an abrasive powder of whose particles less than 10% by weight are of size above 150 microns and less than 20% by weight are of size below 10 microns, in which the abrasive powder has a Mohs hardness in the range of from 1 to 4, the abrasive powder having a particle size distribution curve wholly within the area bounded by the two curves Y of the accompany ing diagram.

2. A cleanser according to Claim 1, in which the abrasive is calcite.

3. A cleanser according to any preceding claim, in which less than 10% by weight of the particles of the abrasive powder are of size below 7 microns.

4. A cleanser according to Claim 3, in which less than 5% by weight of the particles of the abrasive powder are of size below 5 microns.

5. A cleanser according to any preceding claim, in which the abrasive power contains substantially no particles of size below 1 micron.

6. A cleanser accordjng to Claim 5, in which the average particle size of the abrasive powder is in the range from 20 to 60 microns.

7. A cleanser according to any preceding claim, in which the abrasive powder contains substantially no particles of size above 125 microns.

8. A cleanser according to any preceding claim, and containing 1 part of abrasive powder to from 0.001 to 10 parts of surfactant by weight.

9. A cleanser according to any preceding claim, in which the surfactant comprises an anionic detergent-active compound.

10. A cleanser according to any preceding claim, which is a free-flowing powder.

11. A cleanser according to Claim 10, and containing from 0.1 to 40% by weight of surfactant, from 5 to 99% by weight of abrasive and from 0 to 95% by weight of scouring cleanser adjuncts.

12. A cleanser according to any one of Claims 1 to 9, which is a pourable aqueous liquid composition.

13. A cleanser according to Claim 12, and containing from 0.1 to 50% by weight of surfactant, and from 5 to 60% by weight of abrasive powder, the remainder being scouring cleanser adjuncts and water.

14. A cleanser according to Claim 13, in which the abrasive powder is dispersed in the aqueous medium of the cleanser, and this aqueous medium has Bingham plastic characteristics which maintain the abrasive powder in dispersion.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (14)

**WARNING** start of CLMS field may overlap end of DESC **. stirred 50 parts of the coarser calcite fraction of Example 1 to give a liquid scouring cleanser. EXAMPLE 5 A liquid medium for a scouring cleanser is prepared from the following ingredients: Parts Sodium alkylbenzene sulphonate 5.0 Sodium sulphate 0.13 Potassium soap of groundnut oil fatty acids 0.5 Cocodiethanolamide 4.0 Sodium tripolyphosphate 10.0 Pine type perfume 0.6 Water 79.77 To a solution of the phosphate in the water at 70"C was added with stirring the sulphate, soap and amide (in-that order) and the resulting solution was cooled to 350C and the perfume added, with stirring and cooling to ambient tem perature, to give a liquid medium having Bingham plastic characteristics. To 50 parts of this liquid medium was added with stirring 60 parts of the coarser calcite frac tion of Example 1 to give a liquid scouring cleanser. EXAMPLES 6 and 7 Liquid scouring cleansers are prepared as; described in Examples 1 and 7 of British Patent 1,418,671, except that instead of the felspar and calcite abrasives employed there, the coarser calcite fraction of the above Example 1 is used. WHAT WE CLAIM IS:

1. A scouring cleanser comprising a surfac tant and an abrasive powder of whose particles less than 10% by weight are of size above 150 microns and less than 20% by weight are of size below 10 microns, in which the abrasive powder has a Mohs hardness in the range of from 1 to 4, the abrasive powder having a particle size distribution curve wholly within the area bounded by the two curves Y of the accompany ing diagram.

2. A cleanser according to Claim 1, in which the abrasive is calcite.

3. A cleanser according to any preceding claim, in which less than 10% by weight of the particles of the abrasive powder are of size below 7 microns.

4. A cleanser according to Claim 3, in which less than 5% by weight of the particles of the abrasive powder are of size below 5 microns.

5. A cleanser according to any preceding claim, in which the abrasive power contains substantially no particles of size below 1 micron.

6. A cleanser accordjng to Claim 5, in which the average particle size of the abrasive powder is in the range from 20 to 60 microns.

7. A cleanser according to any preceding claim, in which the abrasive powder contains substantially no particles of size above 125 microns.

8. A cleanser according to any preceding claim, and containing 1 part of abrasive powder to from 0.001 to 10 parts of surfactant by weight.

9. A cleanser according to any preceding claim, in which the surfactant comprises an anionic detergent-active compound.

10. A cleanser according to any preceding claim, which is a free-flowing powder.

11. A cleanser according to Claim 10, and containing from 0.1 to 40% by weight of surfactant, from 5 to 99% by weight of abrasive and from 0 to 95% by weight of scouring cleanser adjuncts.

12. A cleanser according to any one of Claims 1 to 9, which is a pourable aqueous liquid composition.

13. A cleanser according to Claim 12, and containing from 0.1 to 50% by weight of surfactant, and from 5 to 60% by weight of abrasive powder, the remainder being scouring cleanser adjuncts and water.

14. A cleanser according to Claim 13, in which the abrasive powder is dispersed in the aqueous medium of the cleanser, and this aqueous medium has Bingham plastic characteristics which maintain the abrasive powder in dispersion.