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Description  |
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The present invention relates to substantially non-aqueous liquid cleaning
products of the kind comprising solid particles dissolved in a liquid
phase, which composition comprises a persalt bleach and an activator
therefor.
Non-aqueous products are preferred over aqueous systems when it is desired
to incorporate a bleach or bleach system since these are highly unstable
in the presence of water. However, in those non-aqueous liquids which
comprise a bleach system having a persalt bleach and a precursor
(activator), the precursor can still be unstable.
The exact mode of action of such precursors is not known, but it is
believed that peracids are formed by reaction of the precursors with the
inorganic peroxy compound, which peracids then liberate active-oxygen by
decomposition.
They are generally compounds which contain N-acyl or O-acyl residues in the
molecule and which exert their activating action on the peroxy compounds
on contact with these in the washing liquor.
The applicants have now found that the precursors can be rendered
significantly more stable if the liquid phase comprises a specific
nonionic surfactant.
Thus according to the invention there is provided a non-aqueous liquid
cleaning composition containing a persalt bleach and a precursor therefor,
the composition being in the form of a liquid phase comprising a
surfactant and a particulate solid phase dispersed therein, at least a
major portion of said surfactant being a capped alcoxylated nonionic
surfactant.
The capped alkoxylated nonionic surfactants comprise a saturated or
unsaturated linear or branched fatty chain linked via one or more
independently selected alkyleneoxy, e.g. C.sub.1-4 alkyleneoxy groups to a
terminal group which is other than hydrogen. This terminal or `capping`
group may be aliphatic or aryl, for example a long-chain alkyl or alkenyl
group having from 5 to 15 carbon atoms, an alkyl group of 1 to 4 carbon
atoms or a benzyl group. The surfactants capped with the C.sub.1-4 alkyl,
especially methyl groups, are preferred. It is, of course, advisable that
the capping group be free of primary --OH groups.
Most preferred are those capped surfactants in which the capping group is
of formula--COR where R is aryl or aliphatic, most preferably alkyl, e.g.
methyl. Thus, the alkoxylated portion of the molecule terminates in an
ester (--O COR) group instead of a hydroxy group. These compounds not only
give excellent precursor stability but also can react with water on
contact with the wash liquor to yield uncapped derivatives of proven
detergency.
By way of example, the capped alkoxylated nonionic surfactants may have any
structure according to the following general formula:
RO(C.sub.2 H.sub.4 O).sub.p (C.sub.3 H.sub.6 O).sub.q R.sup.1
wherein R represents a straight or branched primary or secondary aliphatic
hydrocarbon group, for example alkenyl, or more preferably alkyl, of from
8 to 24, e.g. from 10 to 15 carbon atoms, p is from 2 to 14 preferably 3
to 11, q is from 0 to 8, and R.sup.1 is a capping group other than
hydrogen, for example as hereinbefore described.
Most preferred of these are the solely ethoxylated capped nonionics, for
example those of the above general formula wherein q represents zero.
Other materials of interest are corresponding compounds containing butoxy
or other alkoxy groups.
Surprisingly, we found that if the capped nonionic surfactant comprises an
ester formed from an organic acid and an alkoxylated alcohol nonionic
detergent, the ester can act as a precursor for a persalt bleach included
in the composition, thus obviating the need for any other conventional
precursor. These esters can also lower the pour point of the composition.
Regarding the structure of the ester, t should be noted that British patent
specification No. GB 2 158 454 A discloses use of nonionic surfactants,
modified to have a terminal --COOH group, as agents for preventing gelling
of non-aqueous liquid detergent products when they are dispensed into
water. In contrast however, this embodiment of the present invention is
concerned with organic acids, particularly carboxylic acids of formula
RCOOH where R is an aliphatic or aromatic residue for example C.sub.1-4
alkyl or benzyl, the acid being esterified with an alkoxylated alcohol
nonionic surfactant of formula R.sup.1 --A--OH where R.sup.1 is a
hydrophobic moiety, optionally attached to A via an ether linkage and A is
an alkoxylene or polyalkoxylene linkage, to form a corresponding ester of
formula R.sup.1 --A--O--COR.
In the case of the inorganic persalt bleaches, essential to the present
invention, the precursor makes the bleaching more effective at lower
temperatures, i.e in the range from ambient temperature to about
60.degree. C., so that such bleach systems are commonly known as
low-temperature bleach systems and are well known in the art. The
inorganic persalt such as sodium perborate, both the monohydrate and the
tetrahydrate, acts to release active oxygen in solution, and the precursor
is usually an organic compound having one or more reactive acyl residues,
which cause the formation of peracids, the latter providing for a more
effective bleaching action at lower temperatures than the peroxybleach
compound alone. The ratio by weight of the peroxy bleach compound to the
precursor is from about 15:1 to about 2:1, preferably from about 10:1 to
about 3.5:1. Whilst the amount of the bleach system, i.e. peroxy bleach
compound and precursor, may be varied between about 5% and about 35% by
weight of the total liquid, it is preferred to use from about 6% to about
30% of the ingredients forming the bleach system. Thus, the preferred
level of the peroxy bleach compound in the composition is between about
5.5% and about 27% by weight, while the preferred level of the precursor
is between about 0.5% and about 40%, most preferably between about 1% and
about 5% by weight.
Typical examples of the suitable peroxybleach compounds are alkalimetal
peroborates, both tetrahydrates and monohydrates, alkali metal
percarbonates, persilicates and perphosphates, of which sodium perborate
is preferred.
Precursors for peroxybleach compounds have been amply described in the
literature, including in British patent specifications Nos. 836,988,
855,735, 907,356, 907,358, 907,950, 1,003,310, and 1,246,339, U.S. patent
specification Nos. 3,332,882, and 4,128,494, Canadian patent specification
No. 844,481 and South African patent specification No. 68/6,344.
Typical examples of precursors within these groups are polyacylated
alkylene diamines, such as N,N,N.sup.1,N.sup.1 -tetraacetylethylene
diamine (TAED) and N,N,N.sup.1,N.sup.1 -tetraacetylmethylene diamine
(TAMD); acylated glycolurils, such as tetraacetylgylcoluril (TAGU);
triacetylcyanurate and sodium sulphophenyl ethyl carbonic acid ester.
A particularly preferred precursor is N,N,N.sup.1,N.sup.1 -tetra-
acetylethylene diamine (TAED)
Peroxybenzoic acid precursors are known in the art, e.g. from GB-A-836988.
Examples thereof are phenylbenzoate; phenyl p-nitrobenzoate; o-nitrophenyl
benzoate; o-carboxyphenyl benzoate; p-bromophenyl benzoate; sodium or
potassium benzoyloxybenzenesulphonate; and benzoic anhydride.
A preferred peroxybenzoic acid bleach precursor is sodium
p-benzoyloxybenzene sulphonate of the formula:
##STR1##
The organic peroxyacid compound bleaches which optionally may also be
incorporated are preferably those which are solid at room temperature and
most preferably should have a melting point of at least 50.degree. C. Most
commonly, they are the organic peroxyacids and water-soluble salts thereof
having the general formula
##STR2##
wherein R is an alkylene or substituted alkylene group containing 1 to 20
carbon atoms or an arylene group containing from 6 to 8 carbon atoms, and
Y is hydrogen, halogen, alkyl, aryl or any group which provides an anionic
moiety in aqueous solution.
Another preferred class of peroxygen compounds which can be incorporated to
enhance dispensing/dispersibility in water are the anhydrous perborates
described for that purpose in the applicants' European patent
specification No. EP-A-217,454.
Thus, cleaning products according to the invention are non-aqueous
dispersions which comprise a non-aqueous liquid phase which can be a
liquid surfactant, or a mixture thereof with other liquid ingredients such
as an organic non-aqueous non-surfactant liquid. The compositions may
contain a surfactant as a dispersed or dissolved solid, or more often, as
all or part of said liquid phase. These surfactant compositions are liquid
detergent products, e.g. for fabrics washing or hard surface cleaning
However, the wider term `liquid cleaning product` also includes low
surfactant liquids which are still useful in cleaning, for example
non-aqueous bleach products or those in which the liquid phase consists
primarily of one or more light, non-surfactant solvents for greasy stain
pre-treatment of fabrics prior to washing. Such pre-treatment products can
contain solid bleaches, dispersed enzymes and the like.
As well as the liquid phase, such non-aqueous dispersions also contain
dispersed particulate solids. These are small (e.g. 10 microns) particles
of solid material which are useful in cleaning and as well as the bleach,
could be solid surfactants, builders, enzymes or any other such solids
known to those skilled in the art.
The particles can be maintained in dispersion (i.e. resist settling, even
if not perfectly) by a number of means. For example, settling may be
inhibited purely by virtue of the relative small size of the particles and
the relatively high viscosity of the solvent phase. In other words, the
particles settle very slowly at a rate predicted by Stokes' law or due to
the formation of a loosely aggregated network of particle flocs. This
effect is utilised in the compositions described in patent specifications
No. EP-A-30 096 and GB 2 158 838A. However, there have been several
proposals to utilise additional means to enhance solid-suspending
properties in such non-aqueous liquids. These are somewhat analogous to
so-called external structuring techniques used in aqueous systems; i.e.,
in addition to the particulate solids and the liquid solvent phase in
which they are to be suspended, an additional dispersant is used which by
one means or another, acts to aid stable dispersion or suspension of the
solids for a finite period.
One known means for the stabilisation of a dispersion of solids in
non-aqueous system, which may be utilised in the compositions of the
present invention is to add an inorganic carrier material as the
dispersant, in particular highly voluminous silica. This acts by forming a
solid-suspending network. This silica is highly voluminous by virtue of
having an extremely small particle size, hence high surface area. This is
described in GB patent specifications Nos. 1,205,711 and 1,270,040. A
problem with these compositions is setting upon prolonged storage. A
similar appropriate structuring is use of fine particulate chain
structure-type clay, as described in specification No. EP-A-34,387.
Another suitable substance which can be used as a dispersant for solid
particles is a hydrolyzable co-polymer of maleic anhydride with ethylene
or vinylmethylether, which co-polymer is at least 30% hydrolyzed. This is
described in specification No. EP-A-28,849 (Unilever). A problem with
these compositions is the difficulty in controlling manufacture to obtain
reproducible product stability.
A preferred means by which such dispersions may be stabilised in the
compositions of the present invention is the use of a dispersant material
which has been termed `a ceflocculant`, according to the disclosure of the
applicants' EP-A-266199.
All composition according to the present invention are liquid cleaning
products. They may be formulated in a very wide range of specific forms,
according to the intended use. They may be formulated as cleaners for hard
surfaces (with or without abrasive) or as agents for warewashing (cleaning
of dishes, cutlery etc) either by hand or mechanical means, as well as in
the form of specialised cleaning products, such as for surgical apparatus
or artificial dentures. They may also be formulated as agents for washing
and/or conditioning of fabrics.
In the case of hard-surface cleaning, the compositions may be formulated as
main cleaning agents, or pre-treatment products to be sprayed or wiped on
prior to removal, e.g. by wiping off or as part of a main cleaning
operation.
In the case of warewashing, the compositions may also be the main cleaning
agent or a pre-treatment product, e.g. applied by spray or used for
soaking utensils in an aqueous solution and/or suspension thereof.
Those products which are formulated for the cleaning and/or conditioning or
fabrics constitute an especially preferred form of the present invention.
These compositions may for example, be of the kind used for pre-treatment
of fabrics (e.g. for spot stain removal) with the composition neat or
diluted, before they are rinsed and/or subjected to a main wash. The
compositions may also be formulated as main wash products, being dissolved
and/or dispersed in the water with which the fabrics are contacted. In
that case, the composition may be the sole cleaning agent or an adjunct to
another wash product. Within the context of the present invention, the
term `cleaning product` also embraces compositions of the kind used as
fabric conditioners (including fabric softeners) which are only added in
the rinse water (sometimes referred to as `rinse conditioners`).
Thus, the compositions will contain at least one agent which promotes the
cleaning and/or conditioning of the article(s) in question, selected
according to the intended application. Usually, this agent will be
selected from enzymes, microbiocides, (for fabrics) fabric softening
agents and (in the case of hard surface cleaning) abrasives, in addition
to the essential surfactant and bleach system. Of course in many cases,
more than one of these agents will be present, as well as other
ingredients commonly used in the relevant product form.
The compositions will be substantially free from agents which are
detrimental to the article(s) to be treated. For example, they will be
substantially free from pigments or dyes, although of course they may
contain small amounts of those dyes (colourants) of the kind often used to
impart a pleasing colour to liquid cleaning products, as well as
fluorescers, bluing agents and the like.
All ingredients before incorporation will either be liquid, in which case,
in the composition they will constitute all or part of the liquid phase,
or they will be solids, in which case, in the composition they will either
be dispersed as particles, preferably deflocculated, in the liquid phase
or they will be dissolved therein. Thus as used herein, the term "solids"
is to be construed as referring to materials in the solid phase which are
added to the composition and are dispersed therein in solid form, those
solids which dissolve in the liquid phase and those in the liquid phase
which solidify (undergo a phase change) in the composition, wherein they
are then dispersed.
Thus, where any further surfactants which may be present are solids, they
will usually be dissolved or dispersed in the liquid phase. Where they are
liquids, they will usually constitute part of the liquid phase. Some
surfactants are also eminently suitable as deflocculants.
In general however, any further surfactants may be chosen from any of the
classes, sub-classes and specific materials described in `Surface Active
Agents` Vol. I, by Schwartz & Perry, Interscience 1949 and `Surface Active
Agents` Vol. II by Schwartz, Perry & Berch (Interscience 1958), in the
current edition of "McCutcheon's Emulsifiers & Detergents" published by
the McCutcheon division of Manufacturing Confectioners Company or in
`Tensid-Taschenbuch`, H. Stache, 2nd Edn., Carl Hanser Verlag, Munchen &
Wien, 1981. However, the compositions of the present invention must
contain at least one capped alkoxylated nonionic surfactant.
Liquid surfactants are an especially preferred class of material to use in
the liquid phase, especially polyalkoxylated types and in particular
polyalkoxylated nonionic surfactants.
When deflocculated systems are to be formulated, as a general rule, the
applicants have found that the most suitable liquids to choose as the
liquid phase are those organic materials having polar molecules. In
particular, those materials comprising a relatively lipophilic part and a
relatively hydrophilic part, especially a hydrophilic part rich in
electron lone pairs, tend to be well suited. This is completely in
accordance with the observation that liquid surfactants, especially
polyalkoxylated nonionics, are preferred.
Nonionic detergent surfactants are well-known in the art. They normally
consist of a water-solubilizing polyalkoxylene or a mono- or
di-alkanolamide group in chemical combination with an organic hydrophobic
group derived, for example, from alkylphenols in which the alkyl group
contains from about 6 to about 12 carbon atoms, dialkylphenols in which
each alkyl group contains from 6 to 12 carbon atoms, primary, secondary or
tertiary aliphatic alcohols preferably having from 8 to 20 carbon atoms.
The capped derivatives of these comprise an essential component of the
present invention. Other known include monocarboxylic acids having from 10
to about 24 carbon atoms in the alkyl group and polyoxypropylenes. Also
common are fatty acid mono- and dialkanolamides in which the alkyl group
of the fatty acid radical contains from 10 to about 20 carbon atoms and
the alkyloyl group having from 1 to 3 carbon atoms. In any of the mono-
and di- alkanolamide derivatives, optionally, there may be a
polyoxyalkylene moiety joining the latter groups and the hydrophobic part
of the molecule. In all polyalkoxylene containing surfactants, the
polyalkoxylene moiety preferably consists of from 2 to 20 groups of
ethylene oxide or of ethylene oxide and propylene oxide groups. Amongst
the latter class, particularly preferred are those described in the
applicants' published European specification No. EP-A-225,654, especially
for use as all or part of the solvent. Also preferred are those
ethoxylated nonionics which are the condensation products of fatty
alcohols with from 9 to 15 carbon atoms condensed with from 3 to 11 moles
of ethylene oxide Examples of these are the condensation products of
C.sub.11-13 alcohols with (say) 3 or 7 moles of ethylene oxide. These may
be used as the sole nonionic surfactants or in combination with those of
the described in the last-mentioned European specification, especially as
all or part of the solvent.
Another class of suitable nonionics which may be incorporated, preferably
at most in minor quantities, comprise the alkyl polysaccharides
(polyglycosides/oligosaccharides) such as described in any of
specifications U.S. No. 3,640,998; U.S. No. 3,346,558; U.S. No. 4,223,129;
EP-A-92,355; EP-A-99,183; EP-A-70,074, '75, '76, '77; EP-A-75,994, '95,
'96.
Nonionic detergent surfactants normally have molecular weights of from
about 300 to about 11,000. Mixtures of different nonionic detergent
surfactants may also be used, provided the mixture is liquid at room
temperature. Mixtures of nonionic detergent surfactants with other
detergent surfactants such as anionic, cationic or ampholytic detergent
surfactants and soaps may also be used. If such mixtures are used, the
mixture must be liquid at room temperature.
Examples of suitable anionic detergent surfactants, which may be used,
preferably at most, in minor quantities, are alkali metal, ammonium or
alkylolamaine salts of alkylbenzene sulphonates having from 10 to 18
carbon atoms in the alkyl group, alkyl and alkylether sulphates having
from 10 to 24 carbon atoms in the alkyl group, the alkylether sulphates
having from 1 to 5 ethylene oxide groups, olefin sulphonates prepared by
sulphonation of C.sub.10 -C.sub.24 alpha-olefins and subsequent
neutralization and hydrolysis of the sulphonation reaction product.
Other surfactants which may be used, preferably at most in minor
quantities, include alkali metal soaps of a fatty acid, preferably one
containing 12 to 18 carbon atoms. Typical such acids are oleic acid,
ricinoleic acid and fatty acids derived from caster oil, rapeseed oil,
groundnut oil, coconut oil, palmkernal oil or mixtures thereof. The sodium
or potassium soaps of these acids can be used. As well as fulfilling the
role of surfactants, soaps can act as detergency builders or fabric
conditioners, other examples of which will be described in more detail
hereinbelow. It can also be remarked that the oils mentioned in this
paragraph may themselves constitute all or part of the solvent, whilst the
corresponding low molecular weight fatty acids (triglycerides) can be
dispersed as solids or function as structurants.
Yet again, it is also possible to utilise small amounts of cationic,
zwitterionic and amphoteric surfactants such as referred to in the general
surfactant texts referred to hereinbefore. Examples of cationic detergent
surfactants are aliphatic or aromatic alkyl-di(alkyl) ammonium halides and
examples of soaps are the alkali metal salts of C.sub.12 -C.sub.24 fatty
acids. Ampholytic detergent surfactants are e.g. the sulphobetaines.
Combinations of surfactants from within the same, or from different
classes may be employed to advantage for optimising structuring and/or
cleaning performance.
Non-surfactant liquids which are suitable as solvents include those having
the preferred molecular forms referred to above although other kinds may
be used, especially if combined with those of the former, more preferred
types. Non-surfactant solvents which have molecular structures which fall
into the former, more preferred category include ethers, polyethers,
alkylamines and fatty amines, (especially di- and tri-alkyl- and/or
fatty-N-substituted amines), alkyl (or fatty) amides and mono- and
di-N-alkyl substituted derivatives thereof, alkyl (or fatty) carboxylic
acid lower alkyl esters, ketones, aldehydes, and glycerides. Specific
examples include respectively, di-alkyl ethers, polyethylene glycols,
alkyl ketones (such as acetone) and glyceryl trialkylcarboxylates (such as
glyceryl tri-acetate), glycerol, propylene glycol, and sorbitol.
Many light solvents with little or no hydrophilic character are in most
systems, unsuitable on their own if a deflocculated system is sought.
Examples of these are lower alcohols, such as ethanol, or higher alcohols,
such as dodecanol, as well as alkanes and olefins. However, combination
with the surfactant essential to the compositions of the present invention
makes their use possible. Even though they appear not to play a role in
any deflocculation process, it is often desirable to include them for
lowering the viscosity of the product and/o assisting soil removal during
cleaning.
The compositions of the invention may contain the liquid phase (whether or
not comprising a liquid non-surfactant) in an amount of at least 10% by
weight of the total composition. The amount of the liquid phase present in
the composition may be as high as about 90%, but in most cases the
practical amount will lie between 20 and 70% and preferably between 20 and
50% by weight of the composition.
Preferably also, the compositions of the present invention contain a
deflocculant (as hereinbefore defined) which may be any of those referred
to in the published prior art or any described in the applicants
EP-A-266199.
The level of the deflocculant material in the composition can be optimised
by the means in the art but in very many cases is at least 0.01%, usually
0.1% and preferably at least 1% by weight, and may be as high as 15% by
weight. For most practical purposes, the amount ranges from 2-12%,
preferably from 4-10% by weight, based on the final composition.
The compositions according to the present invention preferably also contain
one or more other functional ingredients, for example selected from
detergency builders, other bleaches, and (for hard surface cleaners)
abrasives.
The detergency builders are those materials which counteract the effects of
calcium, or other ion, water hardness, either by precipitation or by an
ion sequestering effect. They comprise both inorganic and organic
builders. They may also be sub-divided into the phosphorus-containing and
non-phosphorus types, the latter being preferred when environmental
considerations are important.
In general, the inorganic builders comprise the various phosphate-,
carbonate-, silicate-, borate- and aliminosilicate-type materials,
particularly the alkali-metal salt forms. Mixtures of these may also be
used.
Examples of phosphorus-containing inorganic builders, when present, include
the water-soluble salts, especially alkali metal pyrophosphates,
orthophosphates, polyphosphates and phosphonates. Specific examples of
inorganic phosphate builders include sodium and potassium
tripolyphosphates, phosphates and hexametaphosphates.
Examples of non-phosphorus-containing inorganic builders, when present,
include water-soluble alkali metal carbonates, bicarbonates, borates,
silicates, metasilicates, and crystalline and amorphous alumino silicates.
Specific examples include sodium carbonate (with or without calcite
seeds), potassium carbonate, sodium and potassium bicarbonates, silicates
and zeolites.
Examples of organic builders include the alkali metal, ammonium and
substituted, citrates, succinates, malonates, fatty acid sulphonates,
carboxymethoxy succinates, ammonium polyacetates, carboxylates,
polycarboxylates, aminopolycarboxylates, polyacetyl carboxylates and
polyhydroxsulphonates. Specific examples include sodium, potassium,
lithium, ammonium and substituted ammonium salts of
ethylenediaminetetraacetic acid, nitrilotriacetic acid, oxydisuccinic
acid, melitic acid, benzene polycarboxylic acids and citric acid. Other
examples are organic phosphonate type sequestering agents such as those
sold by Monsanto under the tradename of the Dequest range and
alkanehydroxy phosphonates.
Other suitable organic builders include the higher molecular weight
polymers and co-polymers known to have builder properties, for example
appropriate polyacrylic acid, polymaleic acid and polyacrylic/polymaleic
acid co-polymers and their salts, such as those sold by BASF under the
Sokalan Trade Mark.
The aluminosilicates are an especially preferred class of non-phosphorus
inorganic builders. They are especially detrimental to precursor stability
and therefore systems which contain them are those where the use of the
capped nonionic according to the present invention can most valuably exert
its effect. The aluminosilicates are for example crystalline or amorphous
materials having the general formula
Na.sub.Z (AlO.sub.2).sub.Z (SiO.sub.2).sub.Y xH.sub.2 O
wherein Z and Y are integers of at least 6, the molar ratio of Z to Y is in
the range from 1.0 to 0.5, and x is an integer from 6 to 189 such that the
moisture content is from about 4% to about 20% by weight (termed herein,
`partially hydrated`). This water content provides the best rheological
properties in the liquid. Above this level (e.g. from about 19% to about
28% by weight water content), the water level can lead to network
formation. Below this level (e.g. from 0 to about 6% by weight water
content), trapped gas in pores of the material can be displaced which
causes gassing and tends to lead to a viscosity increase also. However, it
will be recalled that anhydrous materials (i.e. with 0 to about 6% by
weight of water) can be used as structurants. The preferred range of
aluminosilicate is from about 12% to about 30% on an anhydrous basis. The
aluminosilicate preferably has a particle size of from 0.1 to 100 microns,
ideally betweeen 0.1 and 10 microns and a calcium ion exchange capacity of
at least 200 mg calcium carbonate/g.
Suitable other bleaches include the halogen, particularly chlorine bleaches
such as are provided in the form or alkalimetal hypohalites, e.g.
hypochlorites.
When the composition contains abrasives for hard surface cleaning (i.e. is
a liquid abrasive cleaner), these will inevitably be incorporated as
particulate so-ids. They may be those of the kind which are water
insoluble, for example calcite. Suitable materials of this kind are
disclosed in the applicants' patent specification Nos. EP-A-50,887;
EP-A-80,221; EP-A-140,452; EP-A-214,540 and EP 9,942, which relate to such
abrasives when suspended in aqueous media. Water soluble abrasives may
also be used.
The compositions of the invention optionally may also contain one or more
minor ingredients such as fabric conditioning agents, enzymes, perfumes
(including deoperfumes), micro-biocides, colouring agents, fluorescers,
soil-suspending agents (anti-redeposition agents), corrosion inhibitors,
enzyme stabilizing agents, and lather depressants.
In general, the solids content of the product may be within a very wide
range, for example from 1-90%, usual-y from 10-80% and preferably from
15-70%, especially 15-50% by weight of the final composition. The persalt
and any other solid phase material should preferably be in particulate
form and have an average particle size of less than 300 microns,
preferably less than 200 microns, more preferably less than 100 microns,
especially less than 10 microns. The particle size may even be of
sub-micron size. The proper particle size can be obtained by using
materials of the appropriate size or by milling the total product in a
suitable milling apparatus.
The compositions are substantially non-aqueous, i.e. they little or no free
water, preferably no more than 5%, preferably less than 3%, especially
less than 1% by weight of the total composition. It has been found by the
applicants that the higher the water content, the more likely it is for
the viscosity to be too high, or even for setting to occur. However, this
may at least in part be overcome by use of higher amounts of, or more
effective deflocculants or other dispersants.
Since the objective of a non-aqueous liquid will generally be to enable the
formulator to avoid the negative influence of water on the components,
e.g. causing incompatibility of functional ingredients, it is clearly
necessary to avoid the accidental or deliberate addition of water to the
product at any stage in its life. For this reason, special precautions are
necessary in manufacturing procedures and pack designs for use by the
consumer.
Thus during manufacture, it is preferred that all raw materials should be
dry and (in the case of hydratable salts) in a low hydration state, e.g.
anhydrous phosphate builder, sodium perborate monohydrate and dry calcite
abrasive, where these are employed in the composition. In a preferred
process, the dry, substantially anhydrous solids are blended with the
liquid phase ingredients in a dry vessel. In order to minimise the rate of
sedimentation of the solids, this blend is passed through a grinding mill
or a combination of mills, e.g. a colloid mill, a corundum disc mill, a
horizontal or vertical agitated ball mill, to achieve a particle size of
0.1 to 100 microns, preferably 0.5 to 50 microns, ideally 1 to 10 microns.
A preferred combination of such mills is a colloid mill followed by a
horizontal ball mill since these can be operated under the conditions
required to provide a narrow size distribution in the final product. Of
course particulate material already having the desired particle size need
not be subjected to this procedure and if desired, can be incorporated
during a later stage of processing.
During this milling procedure, the energy input results in a temperature
rise in the product and the liberation of air entrapped in or between the
particles of the solid ingredients. It is therefore highly desirable to
mix any heat sensitive ingredients into the product after the milling
stage and a subsequent cooling step. It may also be desirable to de-aerate
the product before addition of these (usually minor) ingredients and
optionally, at any other stage of the process. Typical ingredients which
might be added at this stage are perfumes and enzymes, but might also
include highly temperature sensitive bleach components or volatile solvent
components which may be desirable in the final composition. However, it is
especially preferred that volatile material be introduced after any step
of aeratron. Suitable equipment for cooling (e.g. heat exchangers) and
de-aeration will be known to those skilled in the art.
It follows that all equipment used in this process should be completely
dry, special care being taken after any cleaning operations. The same is
true for subsequent storage and packing equipment.
The invention will now be illustrated by way of the following examples.
Three liquids were prepared with the compositions given below. After 4
weeks storage at 37.degree. C. (to simulate prolonged storage) the amount
of precursor (activator) remaining was measured as the result quoted.
The invention will now be illustrated by the following non-limiting
examples.
EXAMPLES 1 to 3
All examples contained 24% partially hydrated zeolite, 15% sodium perborate
monohydrate, 5% glyceryl tri-acetate and 4% TAED, all percentages being by
weight The balance was the nonionic specified.
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% of original Activator
(GTA/TAED) remaining
Ex Nonionic after 4 weeks at 37.degree. C.
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1 Dobanol 91-5 (a)
19 (after only 2 weeks)
2 Dobanol 91-6T (b)
67.5
3 Dobanol 25-9 (c)
73.0
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(a) A nonionic surfactant which is approximately a C.sub.9 to C.sub.11
alcohol, ethoxylated with an average of 5 ethylene oxide groups per
molecule
(b) A nonionic surfactant which is approximately a C to C.sub.11 alcohol,
ethoxylated with an average of 6 ethylene oxide groups and end-capped with
a tertiary butyl group.
(c) A nonionic surfactant which is approximately a C.sub.12 -C.sub.15
alcohol, ethoxylated with an average of 9
ethylene oxide groups and end capped with a CH.sub.3 CO-- group.
N.B. The nonionic Dobanol 25-9 used in Example 3 is not liquid at room
temperature but is at 37.degree. C. It was chosen for expediency to
demonstrate the effect of using an ester-terminated nonionic.
EXAMPLES 4 and 5
All examples contained 24% partially hydrated zeolite and 15% sodium
perborate monohydrate, all percentages being by weight. The balance was
the nonionic specified.
______________________________________
Ex Nonionic
______________________________________
4 Dobanol 91-5 (a)
5 Dobanol 25-9 (b)
______________________________________
(a) uncapped
(b) CH.sub.3 CO-- capped
Example 4 is a reference whilst Example 5 is in accordance with the present
invention.
At 0.5 g dosage into 100 ml of water, pH 11, ambient temperature, the
composition of Example 4 gave no measurable peracid production. Under the
same conditions, after 4 minutes for the composition of Example 5, 45%-50%
by weight of the acetate capped nonionic was converted to the
corresponding uncapped material and (by reaction with the perborate)
peracid. After 10 minutes, the conversion was 75%.
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