[0001] The present invention relates to liquid cleaning compositions of the spherulitic
type containing sodium tripolyphosphate builder and a non-ionic surfactant.
[0002] U.S.P. 4,618,446 describes the preparation of liquid detergents comprising an aqueous
liquid medium which contains a surfactant and an electrolyte with which the surfactant
interacts to form spherulites. The latter can pack together to support suspended solid
particles, e.g. builders such as sodium tripolyphosphate.
[0003] Typically, the surfactant used to form the spherulites is an anionic mixture such
as a mixture of sodium C₈₋₁₄ alkyl benzene sulphonate with an alkyl polyethyleneoxy
ether sulphate or a olefin or paraffin sulphonate or else a mixture of anionic surfactant
with minor amounts of an an alkanolamide or amine oxide. The electrolyte is usually
dissolved builder, especially sodium tripolyphosphate, an( sometimes also sodium carbonate
and/or sodium silicate.
[0004] For some types of washing, e.g. heavy oil stains or synthetic fibre, it is desirable
to include in the formulation a relatively high level of ethoxylated non-ionic surfactant.
Unfortunately it has been found that the inclusion of even small amounts of non-ionic
alkoxylates in built liquid detergents of the spherulitic type tends to cause loss
of stability and of homogeneity of the product, giving a curdled appearance on standing.
[0005] Our copending UK Patent application no. 8813132.1 describes the use of low HLB (e.g.
less than 10) non-ionic surfactant systems to avoid promblems of instability or curdling
in spherulitic liquid detergents. However detergents normally have an HLB of 12 to
15 and there remains a need for spherulitic liquid detergents containing non-ionic
surfactants which are not limited to low HLB surfactants.
[0006] We have now discovered that the instability of non-ionic surfactants is due to the
presence of certain polyvalent anions such as tripolyphosphate, carbonate, silicate
or borate. In the absence of such anions it is possible to formulate stable spherulitic
liquids containing high HLB non-ionic surfactants provided that, if the amount of
surfactant is not sufficient to form spherulitic compositions spontaneously, sufficient
electrolyte is present. This however presents problems if a builder is required. The
most cost effective detergent builder is sodium tripolyphosphate, with causes particularly
severe problems of curdling of non-ionic detergent surfactants. It is possible to
replace sodium tripolyphosphate by certain other builders e.g. zeolite, or citrate
but the performance is substantially inferior. Other alternatives such as carbonate,
silicate and pyrophosphate cause similar problems of curdling the surfactant, as well
as being less cost effective.
[0007] We have found that the adverse effect of sodium tripolyphosphate on non-ionic detergents
is substantially reduced or eliminated if a sufficient amount of a salt, preferably
a sodium salt, of a monobasic acid is present. We believe that this phenomenon is
due to the effect of monobasic sodium salts reducing the solubility and/or the degree
of dissociation of the tripolyphosphate anions resulting in the amount of polyvalent
anion in solution being reduced below the critical level at which instability of non-ionic
sufactants is usually observed. In this way relatively high levels of non-ionic alkoxylates
up to 100% of the total surfactant may be included in sodium tripolyphosphate built
liquid detergents of the spherulitic type if the composition additionally contains
sodium hydroxide or a surfactant desolubilising sodium salt of a monobasic acid.
[0008] Our invention provides a liquid detergent composition comprising a non-ionic surfactant,
suspended sodium tripolyphosphate and a surfactant desolubilising electrolyte of the
formula NaX, where X is OH⁻, or the anion of a monobasic non-surfactant acid, in an
amount sufficient to provide a stable homogeneous non-sedimenting detergent composition.
[0009] The non-ionic surfactant is preferably an alkoxylate. "Alkoxylates", whenever the
context permits herein, are preferably ethoxylates or less preferably propoxylates
or mixed ethoxylate propoxylate copolymers. For example the alkoxylate may typically
be an alkoxylated C₈₋₁₈ natural or synthetic alcohol or an alkoxylated fatty acid,
C₆₋₁₈ alkyl phenol, or glycerol or sorbitan ester, preferably with an HLB of from
10 to 18, e.g. 12 to 15.
[0010] Other non-ionic surfactants that may be present include alkanolamides, such as coconut
diethanolamide or monoethanolamide, amine oxides and alkoxylated amine oxides. The
non-ionic surfactant may be present in a proportion of from 10 to 100% by weight of
the total surfactant, preferably 15 to 90% more preferably 20 to 70%, e.g. 25 to 40%.
The total concentration of nonionic surfactant is typically from 2 to 20% by weight
of the composition, preferably 3 to 15%, e.g. 3.5 to 10%.
[0011] The detergent preferably contains an anionic surfactant. The latter is preferably
a sodium linear alkyl benzene sulphonate (e.g. C₈₋₁₄ alkyl) or a mixture thereof with
a sodium alkyl polyoxyethylene sulphate. Other anionic surfactants which may be used
include olefin sulphonates, paraffin sulphonates, alkyl sulphates and mixtures of
alkyl benzene sulphonate with alkanolamides.
[0012] The anionic surfactant is preferably present in a concentration of from 3 to 25%
by weight of the composition, especially 5 to 24% e.g. 6 to 20% by weight. For some
markets, compositions containing a high ratio of builder to surfactant are desirable,
and the anionic surfactant is typically in the range 5 to 15%, e.g. 6 to 12%. Other
markets may require high total surfactant levels, e.g. 15 to 30%.
[0013] One preferred active system comprises a major proportion of anionic surfactant, preferably
sodium alkyl benzene sulphonate or, most preferably a mixture of sodium alkyl benzene
sulphonate and sodium alkyl polyoxyalkylene ether sulphate and a minor proportion
of non-ionic surfactant comprising an alkylethoxylate and, optionally, but preferably,
a mono- or di-ethanolamide such as coconut diethanolamide. The alkylbenzene sulphonate
and the ethyl polyoxyethylene sulphate may be present in a relative proportion by
weight of from 10:1 to 1:2, preferably 5:1 to 1.5:1, especially 2:1 to 1:1.2, e.g.
1:1. The total of the anionic surfactant is preferably from 12 to 25%, more preferably
15 to 20%, by weight of the composition. The total proportion of nonionic is preferably
from 20 to 40%, e.g. 25 to 37%, more usually 30 to 35%, by weight of the total anionic
and preferably from 2 to 8%, especially 3 to 6%, e.g. 4 to 5.5%, by weight of the
composition. The alkanolamide may typically be present in a proportion of from 0.5
to 5%, e.g. 0.75 to 4%, especially 0.8 to 2% by weight of the composition.
[0014] The composition preferably contains sufficient total dissolved electrolyte to provide
a spherulitic structure. This can usually be identified by centrifuging off the suspended
builder and examining the liquid medium by optical or electron microscopy whereupon
close packed spherulites may be observed. Preferably the total electrolyte concentration
is adjusted to form a substantially space filling flocculated system, e.g. one which
does not form two or more separate liquid layers when centrifuged for two minutes
at 20,000 G. The spherulites are believed to exhibit a concentric structure which
exhibits X-ray scattering or neutron diffraction peaks indicative of a 110-140 nm
repeat spacing.
[0015] The surfactant may also be present as an emulsified lamellar phase. This may appear,
with some surfactant systems, as droplets resembling spherulites, but distinguishable
from them both in appearance and properties at electrolyte concentrations slightly
greater than those required to provide true spherulites. The emulsified, lamellar
phase shows evidence of the presence of a 30-70nm repeating structural unit under
neutron scattering or X-ray diffraction analysis. In some systems the emulsion separates
on standing into a liquid lye layer and a lamellar liquid crystal ("G" phase) layer
unless a stabiliser, e.g. a film forming polymer, such as a polyacrylate, or an emulsifying
or dispersing agent, is present. In such systems we prefer that an appropriate emulsifying
or dispersing agent should be used.
[0016] The surfactant may alternatively be present as an open reticular lamellar phase cocontinuous
with the lye phase, as described in G.B. 2123846.
[0017] The total quantity of electrolyte required will depend upon the nature and concentration
of surfactant present. The electrolyte comprises dissolved sodium tripolyphosphate
and may additionally comprise any builder which is a surfactant-desolubilising, ionisable
salt of a monovalent acid or base such as sodium or potasssium nitrilotriacetate,
or phosphonate. It is, however, essential to include in the electrolyte, at least
a substantial proportion of at least one compound NaX. The latter may for example
be sodium hydroxide, a sodium halide such as sodium chloride, sodium fluoride, sodium
bromide or sodium iodide, sodium nitrate or a surfactant desolubilising sodium salt
of a monobasic organic acid, such as sodium formate, sodium acetate or sodium trichloracetate.
Preferably the compound NaX is present in a concentration of at least 0.5%, typically
more than 1%, most preferably more than 1.25% by weight. The compound NaX may constitute
the whole of the dissolved electrolyte, other than sodium tripolyphosphate, or preferbaly
at least a major part of the total dissolved elecrolyte. Sodium hydroxide used to
neutralise any sulphonic or alkyl sulphuric acid present so as to form surfactant
in situ does not contribute to the electrolyte content, since it is not present as a non-surfactant
electrolyte in the composition.
[0018] Depending upon what other electrolytes are present the compound NaX may be present
in concentrations up to 10 or even 15% by weight of the composition. We do not exclude
the possibility of using higher concentrations, although they will normally be precluded
by considerations such as cost, adverse effects on washing performance or on the stability
of the spherulitic system or by solubility limitations. usually the compound NaX will
be present in total concentration of from 0.75 to 5% by weight of the composition,
especially 1 to 3%. Two or more compounds NaX may be present, for instance we have
found mixtures of sodium hydroxide and sodium chloride particularly useful.
[0019] Polyvalent anions are preferably absent or present in concentrations below the minimum
at which they cause instability. For instance carbonate, pyrophosphate, orthophosphate,
metaphosphate, sulphate and other polyvalent anions are preferably avoided, or maintained
at concentrations below 6% preferably below 5%, more preferably below 4% e.g. below
2% especially below 1%, more especially below 0.5%, of the weight of the composition.
Sodium silicate has also been found undesirable because of its adverse affect on the
physical properties of the system when substantial levels of non-ionic surfactant
are present. While we do not exclude the possibility of including sodium silicate,
we prefer that it is absent, or maintained within the above limits.
[0020] Salts which are chemically unstable in the composition are also preferably absent
unless they have been protected against decomposition or premature reaction, e.g.
by a suitable form of encapsulation or by the inclusion of chemical stabilisers. Such
salts include perborates, chlorates, hypochlorites, perchlorates and persulphates.
[0021] The compositions of our invention contain sodium tripolyphosphate in excess of its
solubility in the aqueous medium, the excess being present as suspended solid particles.
The tripolyphosphate may typically be present in a total proportion between about
10 and about 35% by weight of the composition, e.g. 12 to 30%, preferably 15 to 25%
by weight.
[0022] The compositions of our invention may contain any of the usual additives and minor
ingredients that are compatible with the formulation, e.g. soil suspending agents
such as sodium carboxymethyl cellulose, optical brightening agents, perfumes, dyes,
fabric softeners, clays such as bentonite, foaming agents, antifoams enzymes and bleaches.
[0023] While it is possible to include in our compositions solvents such as ethanol, ethyleneglycol,
isopropanol, propyleneglycol or glycerol or hydrotropes such as sodium benzene sulphonate,
sodium xylene sulphonate or sodium toluene sulphonate, we have found in general that
they do not improve the washing performance of the composition, add to its cost and
make it more difficult to obtain a stable spherulitic composition. We therefore prefer
that they be absent.
[0024] The invention is illustrated by the following examples:
|
Example A |
Example B |
Example C |
Sodium Linear C12-14 alkyl benzene sulphonate |
9.06 |
8.96 |
9.7 |
Sodium C12-1₄ alkyl 5 mole polyoxyethylene sulphate |
7.05 |
8.96 |
- |
C12-15 synthetic alkyl 7 mole ethoxylate |
5.03 |
4.01 |
4.8 |
Cocount diethanolamide |
- |
0.98 |
- |
Sodium tripolyphosphate |
20.14 |
18.0 |
19.4 |
Potassium carbonate |
2.01 |
2.5 |
- |
Sodium chloride |
1.15 |
0.5 |
- |
Sodium hydroxide |
- |
1.02 |
4.0 |
Optical brightener |
0.1 |
0.1 |
0.1 |
Sodium carboxymethyl cellulose |
0.1 |
0.2 |
0.1 |
Perfume |
0.3 |
0.3 |
0.3 |
% Solids |
45.3 |
45.5 |
38.4 |
[0025] Examples A, B and C were made up by stirring together the specified ingredients,
the balance in each case being water. The compositions were pourable, homogenous and
stable, showing no sign of sedimentation after three months at laboratory ambient
temperature, and gave good performance in washing tests.
Examples D-F
[0026] Automatic diswashing liquids have the following formulae:
|
Example D |
Example E |
Example F |
LF403 |
6.98 |
13.5 |
13.5 |
NP9 |
3.48 |
6.8 |
6.8 |
NaCl |
2.03 |
2.2 |
2.2 |
K₂CO₃ |
6.10 |
- |
- |
S.T.P. |
20.35 |
22.1 |
22.1 |
Polyelectrolyte |
- |
- |
2.0 |
Perfume |
- |
- |
0.2 |
Water |
Balance |
Balance |
Balance |
(LF 403 is an ethoxylated and propoxylated C18-15 alcohol NP9 is nonyl phenyl 9 mole ethoxylate. STP is sodium tripolyphosphate). |
[0027] In each case the composition was a brilliant white, opaque pourable fluid which gave
good performance with low foaming in automatic dishwasher tests.
[0028] For comparison, when the above formulations were prepared in the absence of NaCl
the compositions had a curdled appearance resembling cottage cheese.
1. A liquid detergent composition comprising a non-ionic surfactant, suspended sodium
tripolyphosphate and a surfactant desolubilsing electrolyte of the formula NaX where
X is OH or the anion of monobasic non-surfactant acid, in an amount sufficient to
provide a stable homogeneous, non-sedimenting detergent composition.
2. A composition according to claim 1 wherein said non-ionic surfactant comprises an
alkoxylate.
3. A composition according to claim 2 wherein a said alkoxylate is an ethoxylated C₈₋₁₈
natural or synthetic alcohol, fatty acid, alkyl phenol or sobitan or glycerol ester.
4. A composition according to any foregoing claim wherein said non-ionic surfactant
comprises an alkanolamide, amine oxide or alkoxylated amine oxide.
5. A composition according to any foregoing claim additionally comprising an anionic
surfactant.
6. A composition according to claim 5 wherein the anionic surfactant comprises sodium
alkyl benzene sulphonate, or a mixture thereof with a sodium alkyl polyethyleneoxy
sulphate.
7. A composition according to any foregoing claim wherein the nonionic surfactant is
present in a proportion of from 15 to 100% of the total surfactant.
8. A composition according to any foregoing claim wherein the nonionic surfactant is
present in a proportion of 2 to 20% by weight of the composition.
9. A composition according to any of claims 5 to 8 wherein the nonionic surfactant is
present in a proportion of from 3 to 25% by weight of the composition.
10. A composition according to any foregoing claim containing sufficient dissolved electrolyte
to form a spherulitic structure which does not form two or more separate liquid layers
when centrifuged for two minutes at 20,000 G.
11. A composition according to claim 10 which exhibits an X-ray diffraction and/or neutron
scattering peak corresponding to a repeat distance of 110 to 140 nm.
12. A composition according to any of claims 1 to 9 comprising sufficient dissolved electrolyte
to form a lamellar phase emulsified in a liquid lye phase.
13. A composition according to claim 12 which exhibits an X-ray diffraction and/or neutron
scattering peak corresponding to a repeat spacing of 30 to 70 nm.
14. A composition according to either of claims 12 and 13 containing sufficient of a
polymeric film forming, emulsifying or dispersing agent to maintain said lamellar
phase emulsified in said lye phase.
15. A composition according to any foregoing claim wherein said electrolyte comprises,
sodium hydroxide, a sodium halide, sodium nitrate or a surfactant desolubilising salt
of a monobasic organic acid.
16. A composition according to claim 15 wherein said electrolyte comprises sodium chloride.
17. A composition according to claim 15 wherein said electrolyte comprises sodium formate,
sodium acetate or sodium trichloracetate.
18. A composition according to any foregoing claim containing from 0.5 to 15% by weight
of said electrolyte NaX.
19. A composition according to claim 18 containing at least 1% by weight of said electrolyte
NaX.
20. A composition according to any foregoing claim containing from 1 to 3% by weight
of said electrolyte NaX.
21. A composition according to any foregoing claim which is substantially free from dissolved
polyvalent anions.