[0001] The present invention relates to liquid abrasive cleaner compositions comprising
particulate abrasive material stably suspended in an aqueous liquid medium.
[0002] Liquid abrasive cleaners have been known in the art for many years. They are widely
used in the ordinary household cleaning of hard surfaces as they provide a convenient
means for the elimination of stubborn soils, greases, burnt-in materials and stains
which are not or not completely removed by abrasive-free cleaning products.
[0003] Over the last two decades, a multitude of publications have dealt with the formulating
of liquid abrasive cleaners. A majority of these publications focus on the stability
and suspending properties of the aqueous liquid medium. Suspending media have e.g.
been described in the British patent specifications Nos 1 167 597, 1 181 607, 1
262 280, 1 303 810, 1 308 190 and 1 418 671. Other disclosures are concerned with
the stability of the suspending media under high shear rates during processing, such
as the European patent specifications Nos. 0 050 887 and 0 080 221.
[0004] Over recent years liquid abrasive cleaners have become increasingly more sophisticated,
the in-use properties other than straightforward cleaning efficiency becoming relevant
factors in the consumer appreciation. Accordingly, the art is aiming at liquid abrasive
cleaner products which display a combination of properties such as cleaning efficiency,
non-scratching behaviour, rich foaming, a non-gritty creamy appearance, good rinsability,
etc.
[0005] Unfortunately, various of these properties prove to be difficult to combine in one
product. Good cleaning efficiency is difficult to achieve simultaneously with non-scratching
behaviour and/or non-gritty appearance. The same applies e.g. to a combination of
rich foaming and easy rinsability.
[0006] Although it has long been recognised that the size of the abrasive is of the greatest
importance for an effective cleaner, only in the recent art has it been indicated
that the specific particle size distribution of the abrasive material may play an
important rôle in the formulation of liquid abrasive cleaner products which, to
an acceptable extent, satisfy a number of the desired properties simultaneously.
[0007] In the British patent specification N° 1 581 433 it has been disclosed that rinsing
properties are considerably improved if the amount of finest particles in the abrasive
powder used in making the cleaner is reduced. In preferred particle distributions
less than 20% by weight of the particles are of size below 10 micrometres and substantially
no particles are of size above 125 micrometres.
[0008] In the United States patent N° 4 181 633 there are disclosed liquid abrasive cleaner
compositions comprising calcium metasilicate as sole abrasive, or in conjunction
with calcium carbonate, which are stated to yield abrasive cleaners of superior cleaning
action and reduced abrasion. The abrasive material should have a mean particle size
in the range of about 5.5 to 16 micrometres and substantially no particles above
40 micrometres.
[0009] In the United States patent N° 4 302 347 all-purpose liquid abrasive cleaners are
disclosed comprising from 1 to 20% by weight of water-insoluble particulate abrasive
of particle sizes in the range of 1 to 40 micrometres. Compositions are stated to
have a creamy consistency and to exhibit effective removal of grease and other soils
with effective polishing action and virtually no scratching.
[0010] In the British patent specification N° 2 125 428 liquid scouring cleanser compositions
are described comprising an abrasive powder of mean particle size between 4 and 17.5
micrometres with substantially no particles of size above 75 micrometres. An improved
soft and smooth consistency is combined with acceptable cleaning performance.
[0011] Compared to the conventional household liquid abrasive cleaners comprising abrasive
powders with particle sizes ranging from 1 to about 150 micrometres and mean particle
size of between 10 and 50 micrometres, recent prior art suggests a considerable shift
to lower particle size ranges and sharper distributions, thereby improving consistency
and rinsing properties without unacceptable loss of cleaning performance.
[0012] A drawback of liquid abrasive cleaner compositions formulated with relatively high
amounts of fine mineral abrasives, in particular very fine calcite, is that on storage
the fine mineral will grow to particles of much larger size which consequently adversely
affect the consistency of the product and the non-scratching behaviour thereof on
the softer substrates such as e.g. plastic surfaces.
[0013] It has now been found that in compositions which are free from phosphates, a specific
selection of electrolyte type effectively reduces this tendency to particle growth.
[0014] In accordance with these findings, the present invention provides a liquid abrasive
cleaner composition which is free from phosphates, comprising, stably suspended
in a liquid medium, from 40 to 70% by weight of a mineral abrasive having particles
in the size range of from 1 to 10 micrometres, and up to 20% by weight of one or
more electrolytes selected from the group consisting of alkali metal and ammonium
salts of citric, carbonic, sulphuric, hydrochloric, succinic, adipic and glutaric
acids.
[0015] Suitable for use as the abrasive material are both natural and synthetic mineral
abrasives, for example dolomite, precipitated calcium carbonate (aragonite), feldspar,
alumina, silica, abrasives, such as quartz and quartzite; and preferably an abrasive
material is used with a hardness on Moh's scale of from 1 to 4. Particularly suitable
is calcite, for instance limestone, chalk or marble such as those forms of calcite
referred to in the British Patent 1 345 119.
[0016] The mineral abrasive is included in an amount of from 40 to 70% by weight of the
composition, preferably of from 45 to 55% by weight.
[0017] Suitable abrasive distributions in accordance with the present invention are highly
classified distributions having particles within the range of from 1 to 10 micrometres.
For the purpose of this invention particle size distributions of 1 to 10 micrometres
are understood to denote distributions comprising less than 10% by weight of particles
having sizes above 10 micrometres and less than 30% by weight of particles having
sizes below 1 micrometre.
[0018] The classification at the upperside preferably results in distributions having less
than 5 or even 3% by weight of particles having sizes above 10 micrometres. A very
sharp classification at the lower side is less pertinent, but preferably results in
distributions comprising less than 20% by weight of particles having sizes below
1 micrometre.
[0019] The mean particle size of the distribution according to the present invention lies
in general within the range of from 1 to 5 micrometres, optimal results being obtained
with mean particle sizes within the preferred range of from 2 to 4 micrometres.
[0020] The mineral abrasive is stably suspended in a liquid medium, which normally comprises
an aqueous medium in which an anionic detergent material is present, preferably
in combination with a nonionic or zwitterionic detergent material. Suitable anionic
surfactants are alkali metal or alkanol amine salts of C₁₂-C₁₈ branched or straight
chain alkylaryl sulphonates, of C₁₀-C₁₈ alkyl (EO)₁
-₁₀ sulphates, of C₁₀-C₂₄ fatty acid soaps etc. In general the amount of anionic surfactant
will vary between 0.5 and 15 percent, preferably between 1 and 5 percent by weight
of the final composition.
[0021] It is often desirable to include also a nonionic or zwitterionic detergent material
i n the aqueous medium in an amount of from 0.3 to 7 percent, preferably from
0.5 to 5 percent by weight. Suitable examples of nonionic detergents are water-soluble
condensation products of ethylene oxide and/or propylene oxide with linear primary
or secondary C₈-C₁₈ alcohols, with C₈-C₁₈ fatty acid amides or fatty acid alkylolamides
(both mono- and diamides), with C₉-C₁₈ alkyl phenols and so on. The alkoxylated C₈-C₁₈
fatty acid mono- and dialkylolamides should contain more than one alkylene oxide
unit; for example, they should be condensed with e.g. 2-5 moles of alkylene oxide
such as ethylene oxide. Fatty acid mono-or dialkylolamides in which the fatty acid
radical contains 10-16 carbon atoms are also suitable nonionics, such as for instance
coco fatty acid mono-or diethanolamide.
[0022] Suitable zwitterionic detergents are trialkyl amine oxides having one long alkyl
chain (C₈-C₁₈) and two short (C₁-C₄) alkyl chains; betaines and sulphobetaines.
[0023] It is highly desirable that the liquid medium should exhibit Bingham plastic characteristics,
thus forming a stable suspending medium for the mineral abrasive. Such media using
the above-mentioned surfactants, possibly in combination with other surfactants,
are described in British patent specifications 1 167 597, 1 181 607, 1 262 280, 1
303 810, 1 308 190 and 1 418 671.
[0024] As a further essential component of the suspending medium, one or more electrolytes
are included, which must not be of the phosphate type.
[0025] Suitable electrolytes are selected from the group consisting of alkali metal and
ammonium salts of citric, carbonic, sulphuric, hydrochloric, succinic, adipic and
glutaric acids.
[0026] Preferred electrolytes are the alkali metal salts of citric and carbonic acid, such
as sodium citrate, sodium carbonate and sodium bicarbonate. The level of electrolyte
depends on the particular surfactant system of choice and in general ranges from 0.5
to 25% by weight, preferably from 1 to 7% by weight.
[0027] The compositions of the present invention optimally include a bleaching agent of
the chlorine-releasing type, such as sodium hypochlorite and isocyanurate.
[0028] Other adjuncts for liquid abrasive cleansers may be included, such as colouring
agents, perfumes, fluorescers, hydrotropes, soil-suspending agents, enzymes, opacifiers,
germicides, humectants, etc.
[0029] The invention will further be described by way of example, in which quantities are
expressed by percentages by weight of the total composition unless otherwise indicated.
1. A liquid abrasive cleaner composition which is free from phosphates, comprising,
suspended in an aqueous medium, from 40 to 70% by weight of a mineral abrasive having
particles in the size range of from 1 to 10 micrometres, and up to 20% by weight
of one or more electrolytes selected from the group consisting of alkali metal and
ammonium salts of citric, carbonic, sulphuric, hydrochloric, succinic, adipic and
glutaric acids.
2. A composition according to claim 1, wherein the abrasive has a Moh's hardness
of between 1 and 4.
3. A composition according to claim 1 or 2, wherein the abrasive is calcite.
4. A composition according to any one of the preceding claims, comprising from 45
to 55% by weight of the abrasive.
5. A composition according to any one of the preceding claims, wherein the abrasive
has a mean particle size within the range of from 1 to 5 micrometres.
6. A composition according to any one of the preceding claims, wherein the abrasive
has a mean particle size within the range of from 2 to 4 micrometres.
7. A composition according to any one of the preceding claims, wherein the aqueous
medium comprises from 0.5 to 15% by weight of an anionic surfactant,
from 0.3 to 7% by weight of a nonionic surfactant,
and
from 0.5 to 25% by weight of the electrolyte.
8. A composition according to any one of the preceding claims, wherein the electrolyte
is selected from the group consisting of the alkali metal salts of citric and carbonic
acid.
9. A composition according to any one of the preceding claims, which further includes
a bleaching agent of the chlorine-releasing type.