Note: Descriptions are shown in the official language in which they were submitted.
133
LIQUIV DETERGENT COMPOSITIONS
Field of the Invention
. .
This invention relates to aqueous liquid detergent
compositions and particularly to substantially unbuilt
dishwashing detergent compositions incorporating a source
of magnesium ions.
Background of the Invention
The use of magnesium salts and magnesium surfactants
in dishwashing detergent formulations is taught in the
patent literature and the disclosures of British Patent
Specifications Nos. 1,524,441 and 1,551,074 and British
published Patent Application No. 2,010,893 A are repre-
sentative of the state of the art. The art teaches that
these formulations have enhanced performance, particularly
when used in water of low mineral hardness. Nevertheless
products made in accordance with these teachings have all
been found to be non-optimum in various ways such as raw
material expense, phase stability on storage, performance
in hard water, effect on hands and suds profile.
Accordingly the search has continued for compositions
having improved economy, performance and in-use
characteristics and it has now been found that certain
combinations of active ingredients can provide a range of
enhanced properties not thought previously attainable in
one formulation. More particularly it has been found
possible to provide concentrated stable liquid dishwashing
formulations of improved greasy soil removal, suds profile,
viscosity and freeze-thaw characteristics.
~0133
The Applicants have found that compositions incor-
porating a ternary anionic surfactant mixture comprising
alkyl benzene sulphonate, alkyl ether sulphate and alkyl
sulphate, and in which part of the cation system is
magnesium, produce the maximum suds mileage,ti.e. number
of dishes washed) when the ma~nesium level corresponds
to the level of alkyl sulphate present.
Furthermore, in one aspect of the invention, it has
been found possible to combine these characteristics with
no sacrifice in the effect on hands relative to leading
liquid dishwashing detergents available commercially.
An additional increment of sudsing performance is
obtainable by the addition of a suds booster such as
an alkyl alkanolamide. It had previously been believed
that high levels of performance could only be obtained
by the use of very high surfactant levels or by the use
of high levels of suds boosters, which were expensive,
difficult to incorporate and gave rise to phase stability
problems on storage. The Applicants have found that
surprisingly low suds booster levels viz. 3-4% provide
a significant sudsing benefit in the formulations of
the present invention and that, whilst levels of 6-8%
can be used they offer little or no performance advantages
over the lower levels.
Whilst the mechanism by which the compositions of
the invention attain their enhanced performance is not
fully understood and whilst the Applicants do not wish
to be bound by any theory, it is believed that, in the
ternary surfactant system employed in the compositions,
magnesium is primarily associated with the alkyl sulphate
in a polar i.e. non-ionic bond arrangement and that this
combination of the magnesium and alkyl sulphate, provides
a more closely packed (and hence stable) structure in the
suds. The effect of any additional suds booster is believed
to be primarily of a suds-stabilizing nature.
~6(;3133
Summary of the Invention
According to the present invention there is provided
a physically stable liquid detergent composition comprising
a mixture of alkylbenzene sulphonate, alkyl ether sulphate
and alkyl sulphate surfactants in a hydrotrope-water
system comprising:
(a) 4%-24% by weight of a primary C10-C26 alkyl
sulphate salt
(b) 0.5%-20% by weight of a water soluble C10-Cl6
primary alkyl ethoxy sulphate salt,
containing an average of 2-6 ethylene oxide
groups per alkyl group in the alkyl ether
sulphate,
(c) 10%-28% by weight of a water soluble substan-
tially linear C10-Cl6 alkyl benzene sulphonate
salt,
provided that the ratio of the total weight of
components (a) and (c) to the weight of component
(b) is <33:1, the composition containing magnesium
ion in a molar amount corresponding to 0.20-0.70X
where X is the number of moles of C10-Cl6 alkyl
sulphate present.
Preferably the composition contains magnesium ion
in an amount corresponding to 0.45-0.55X where X is
defined as above.
Preferably the ratio of the total weight of alkyl-
benzene sulphonate and alkyl sulphate to the weight of
alkyl ethoxy sulphate is ~ 14:1 and in one aspect of
the invention it is preferred that the ratio is ~ 5:1.
Preferably also the composition contains 2%-8% most
preferably 3%-4~ by weight of a suds booster selected from
C10-Cl6 mono and di C2-C3 alkanolamide, C12-C14 alkyl
amides condensed with up to 15 moles ethylene oxide per
mole of amide, and C8-C18 alkyl di Cl-C3 alkyl amine oxides.
.
.~..
bi0133
-- 4
In a highly preferred composition at least 50% and
preferably 100% of the counter ions of components (b)
and (c) above are ammonium ions and the chill point
(as hereinafter defined) of the formulation is 'C.
Description of the Invention
_
Detergent compositions in accordance with the present
invention comprise a mixture of three anionic surfactants
of defined constitution in carefully controlled proportion.
The surfactant component of principal importance is a
primary alkyl sulphate in which the alkyl group contains
10-16 carbon atoms, more preferably an average of 12-13
carbon atoms preferably in a linear chain. C10-Cl6
alcohols, derived from natural fats or Ziegler olefin
build-up or oXO synthesis, form suitable sources for the
alkyl group. Examples of synthetically derived materials
include Dobanol~ 23 (RTM) sold by Shell Chemicals (UK)
Ltd., Ethyl~ 24 sold by the Ethyl Corporation, a blend
of C13-C15 alcohols in the ratio 67% C13, 33% C15 sold
under the trade mark Lutensol by BASF GmbH and
Synperonic~ (RTM) by ICI Ltd, and Lial~ 125 sold by
Liquichimica Italiana. Examples of naturally occurring
materials from which the alcohols can be derived are
coconut oil and palm kernel oil and the corresponding
fatty acids.
The alkyl sulphate component is present at a level of
from 4% to 24% by weight of the composition more generally
from 6% to 16% by weight. In a preferred aspect of the
invention the usage level lies in the range from 8% to 12%
by weight, most preferably in the range from 9% to 11% by
weight.
For the purposes of the present invention the alkyl
sulphate is associated with a source of magnesium ions
which, as will be described hereinafterf can either be
introduced as the oxide or hydroxide to neutralise the
acid or can be added to the composition as a water
33
-- 5 --
soluble salt. However, the addition of appreciable
levels of magnesium salts to the dishwashing compositions
of the invention raises the temperature at which inorganic
salt crystals form in the compositions on cooling and is
therefore less preferable. The molar amount of magnesium
ion in the compositions is controlled to correspond to
0.20-0.70X preferably 0.45-0.55X where X is the number
of moles of C10-Cl6 alkyl sulphate present. Most prefer-
able the magnesium ion content is adjusted to provide the
stoichiometric equivalent of the alkyl sulphate present.
In practice the magnesium ion will be present at a level
of from about 0.15% to about 0.70% by weight preferably
from 0.35% to 0.55% by weight of the composition.
The second anionic surfactant component comprises
a primary alkyl ethoxy sulphate derived from the
condensation product of a C10-Cl6 alcohol with an average
of from 2 to 6 ethylene oxide groups. The C10-Cl6
alcohol itself can be obtained from any of the sources
previously described for the alkyl sulphate component.
It has however been found preferable to use alkyl sulphate
and alkyl ether sulphate in which the carbon chain length
distributions are the same. C12-C13 alkyl ether sulphates
are preferred and the level of alkyl ethoxy sulphate in
the compositions lies between 0.5~ and 20% by weight of
the compositions generally in the range from 4% to 14%
by weight. In a preferred aspect of the invention the
level lies in the range from 9% to 12% by weight, most
preferably in the range from 9% to 11% by weight.
The conventional average degree of ethoxylation is 3
groups per mole of alcohol, but as conventional ethoxy-
lation processes result in a distribution of individual
ethoxylates ranging from 1 to 10 ethoxy groups per mole
of alcohol, the average can be obtained in a variety of
ways. Blends can be made of material having different
33
degrees of ethoxylation and/or different ethoxylate
distributions arising from the specific ethoxylation
techniques employed and subsequent processing steps
such as distillation. In fact, it has been found that
equivalent sudsing and grease removal performance to that
given by a blend of alkyl sulphate and alkyl triethoxy
ether sulphate can be obtained by reducing the level of
alkyl sulphate and using an alkyl ether sulphate with an
average of approximately two ethoxy groups per mole
of alcohol.
The counter ion for the alkyl ethoxy sulphate can
be any one of sodium, potassium, ammonium or alkanol-
ammonium or a mixture thereof. However for the purposes
of obtaining the lowest possible chill point temperature,
(the temperature at which inorganic salt crystals
separate) it is desirable that at least 50% of the counter
ions for the alkyl ethoxy sulphate should be ammonium.
In highly preferred compositions in accordance with the
invention, the alkyl ethoxy sulphate is completely
neutralized by ammonium ions.
The alkyl benzene sulphonates forming component tc)
of the present invention are those in which the alkyl
group, which is substantially linear, contains 10-16
carbon atoms, preferably 11-13 carbon atoms, a material
with an average carbon chain length of 11.8 being most
preferred. The phenyl isomer distribution, i.e., the
point of attachment of the alkyl chain to the benzene
nucleus, is not critical but alkyl benzenes having
a h.igh Z-phenyl isomer content are preferred. For the
purposes of the present invention an alkylbenzene
sulphonate content of from 10% to 28% by weight of the
composition is required generally from 12% to 26% by
weight. In a preferred aspect of the invention an alkyl-
benzene sulphonate content of from 14% to 17% by weight
'~,
0133
is used and highly preferred compositions in accordance
with this aspect of the invention have from 15% to 17~
of Cll 8 alkyl benzene sulphonate. The counter ions in
association with the alkyl benzene sulphonate are indep-
endently selected in the same manner as those for thealkyl ethoxy sulphate, there being preferably at least
50~ of ammonium ions. In order for compositions in
accordance with the invention to have a chill point of
~ O~C, at least 70% of the neutralizing cations for the
anionic surfactants should be ammonium ions and most
preferably ammonium constitutes the only cation
present other than magnesium.
Formulations in accordance with the present
invention derive most of their sudsing and grease
removal performance from the alkyl sulphate and alkyl-
benzene sulph~nate components. The alkyl ether sulphate
component provides phase stability for the formulation on
storage and also prevents precipitation of insoluble
surface active salts at usage concentrations (0.05%-0.2%)
in water of high mineral hardness. In order to satisfy
the stability requirements on storage and in use, the
ratio of the total weight of alkyl benzene sulphonate
and alkyl sulphate salts to the weight of alkyl ethoxy
sulpha~e salts should not exceed 33:1, and generally
should not exceed 14:1, there being relatively little
benefit for ratios above 14:1 over those below that
ratio. Physically stable dishwashing li~uid compositions
having superior sudsing and grease cutting performance
comprise 8%-12% preferably 9%-11% alkyl sulphate, 4%-8%
preferably 4%-6% alkyl ether sulphate and 22%-28%
preferably 24%-26% of alkyl benzene sulphonate.
When incorporated in the formulation at levels
above the minimum necessary for phase stability, the
alkyl ether sulphate component also improves the effect
on hands. In a preferred aspect of the invention, in
~r
133
-- 8 --
which liquid detergent compositions are formulated to
provide the optimum mildness to skin (i.e. effect on
hands) consistent with enhanced sudsing and grease
cutting capability, the ratio of the total weight of
alkyl benzene sulphonate and alkyl sulphate to alkyl
ether sulphate should be less than 5:1 and preferably
should lie in the range 2.0:1 2.5:1.
A highly preferred ingredient of the composition
according to the invention is a suds-promoting agent
present at a level of from 2% to 8% by weight of the
composition preferably from 3% to 6% and most preferably
3%-4~.
The suds-promoting agent can be any of Cl~-Cl6
mono- and di-C2-C3 alkanolamide~ Cl2-C14 alkyl amides
condensed with up to 15 moles of ethylene oxide per
mole of amide and tertiary amine oxides containing a
C8-Cl8 alkyl group.
Examples of the alkanolamides are coconut alkyl
monoethanolamide, coconut alkyl diethanolamides and
palm kernel and coconut alkyl mono and di isopropanol-
amides. The palm kernel or coconut alkyl residue may
either be 'whole cut', including the C10 and C16
fractions or may be the so-called 'narrow-cut' C12-C14
fraction. Synthetic sources of the C10-Cl6 alkyl group
can also be used.
Examples of the ethoxylated amides include coconut
alkyl amide condensed with six moles of ethylene oxide,
lauryl amide condensed with eight moles of ethylene
oxide, myristyl amide condensed with ten moles of
ethylene oxide and coconut amide condensed with eight
moles of ethylene oxide. Amine oxides useful in the
present invention have one alkyl or hydroxyalkyl moiety
of 8 to 18 carbon atoms, preferably 8 to 16 carbon
atoms and two moieties selected from alkyl groups and
hydroxyalkyl groups containing l to 3 carbon atoms.
~,
133
g
Examples of such materials include dimethyloctylamine
oxide, diethyldecylamine oxide, bis - (2-hydroxyethyl)
dodecylamine oxide, dimethyldodecylamine oxide, dipropyl-
tetradecylamine oxide, methylethylhexadecylamine oxide,
and dimethyl - 2 - hydroxyoctadecylamine oxide.
A highly preferred example of the tertiary amine
oxide is a C12-C14 alkyl dimethyl amine oxide in which
the Cl2-Cl4 alkyl group is derived from coconut oil.
The balance of the formula comprises a hydrotrope-
water system in which the hydrotrope may be urea, aCl-C3 alkanol, or a lower alkyl benzene sulphonate salt
such as toluene-, cumene- or xylene-sulphonate or mixtures
of any of these. Normally a single hydrotrope will be
adequate to provide the required phase stability and
viscosity characteristics, but compositions in which the
total surfactant concentration exceeds 45% may require a
mixture such as urea-alcohol-water or alcohol-lower alkyl
benzene sulphonate-water in order to remain stable and
easily pourable. For compositions having an organic active
concentration less than about 40% by weight the preferred
hydrotrope is ethanol which is employed at from 6% to 10%
by weight of the composition preferably at from 7% to 9%.
Mixtures of hydrotropes can, of course, be used in compo-
sitions of lower surfactant concentration and may be
employed for cost effectiveness reasons.
Optional ingredients of the liquid detergent
compositions of the invention include opacifiers such as
ethylene glycol distearate, thickeners such as guar gum,
antibacterial agents such as glutaraldehyde and Bronopol
(RTM), antitarnish agents such as benzoxytriazole, heavy
metal chelating agents such as ETDA or ETDMP, perfumes
and dyes. The pH of the compositions may be anywhere
within the range 6-7.5 but as manufactured the compositions
normally have a pH in the range 6.6~7.3. For coloured
products the pH preferably lies in the range 6.6-6.9 in
order to maintain colour stability.
6~1~3
-- 10 --
The technique of incorporation of the magnesium ions
is not thought to be critical and the composition can be
made in a number of ways.
Thus, individual anionic surfactants can be made as
aqueous solutions of alkali metal or ammonium salts which
are then mixed togPther with the suds booster and with
the hydrotrope, following which the magnesium ion can be
introduced as a water soluble salt such as the chloride
or sulphate. Optional minor ingredients are then added
before the pH and viscosity are adjusted. This method
has the advantage of utilizing conventional techniques
and equipment but does not result in the introduction of
additional chloride or sulphate ions which can increase
the chill point temperature (the temperature at which
inorganic salts precipitate as crystals in the liquid).
An alternative method is to mix the alcohol and
alcohol ethoxylate together and carry out a single sul-
phation and neutralization. For this, the alcohol and
alcohol ethoxylate should be mixed in a weight ratio lying
in the range 45:1 to 1:5.5. Sulphation can take place by
means of any of the conventional sulphating agents such as
e.g., sulphur trioxide or chlorosulphonic acid. Neutrali-
zation of the alkyl ether sulphuric acid and the alkyl
sulphuric acid is carried out with a magnesium oxide or
hydroxide slurry which avoids the addition of chloride
or sulphate ions. ~lthough not essential it is convenient
to use a mixture of these acids as the magnesium salt
of the alkyl ether sulphuric acid has relatively greater
aqueous solubility than the alkyl sulphuric acid com-
ponent. The separately neutralized alkyl benzene sul-
phonate salt, and the neutralized alkyl and alkyl ether
sulphate salts and the hydrotrope are then added to the
final mixing tank and the suds booster and any optional
ingredients added before the pH is adjusted as above.
Preferred compositions in accordance with the
invention are clear single phase liquids, but the
invention also embraces opaque products containing
dispersed phases provided that such products are physi-
cally stable (i.e., do not separate) on storage.
rj
Typical composition ranges for the present invention
are:
(a) 8-9% C12-C14 alkyl sulphate
10-11~ C12-C14 alkyl (EO)2 sulphate
14-15% Cll 8 alkyl benzene sulphonate
3-4% narrow cut Coconut alkyl ethanolamide
(b) 11-12% C12-C14 alkyl sulphate
11-12% C12-C14 alkyl (EO)3 sulphate
14-15% Cll 8 alkyl benzene sulphonate
3-4% narrow cut coconut alkyl ethanolamide
(c) 9-11% C12-C14 alkyl sulphate
9-11% C12-C14 alkyl (EO)3 sulphate
15-17% Cll 8 alkyl benzene sulphonate
3-4% whole cut coconut alkyl ethanolamide
(d) 9-11% C12-C14 alkyl sulphate
4-6% C12-C14 alkyl (EO)3 sulphate
24-26% Cll-C13 alkyl benzene sulphonate
The invention is illustrated in the following examples
in which the percentages of the components are by weight
based on the finished composition.
Example 1
The following composition is made up.
C12_13 Alkyl sulphate 111.8) incorporation+
2 ) 1.24 parts NH
C12_13 alkyl (EO)3 sulphate 311-4 io~+and 0.50 parts
14. 23 Mg ion, t~t
Cll 8 linear alkyl benzene level of Mg
sulphonate corresponding to
Narrow cut ooconut monoethanol- 3.0 0.5X where X is
amide the number of
Ethanol 9.O mlehs of alky
Perfume, Colour and 1.0
Miscellaneous
Water to 100
, .
33
- 12 -
1) Derived f~om Dobano ~ 23 (RTM) a C12-C13
primary alcohol sold by She]l Chemicals.
2) Derived from Dobanol~ 23.3 (RTM) a C12-C13
primary alcohol condensed with an average of three
ethylene oxide groups per mole of alcohol sold by
Shell Chemicals.
3) Derived from Sirene~ XL 12, a linear alkyl
benzene sold by SIR Italy.
The alkyl benzene sulphonate is ~ormed by SO3
sulphonation of the alkyl benzene. I'he alkyl sulphate and
alkyl ether sulphate are formed by SO3 sulphation of a
blend of the alcohol and alcohol ether condensate and the
mixed sulphuric acids are neutralised in a heel of water,
ethanol all of the magnesium hydroxide required and
approximately 60% of the ammonia. The sulphonic acid is
then added to this mixture, followed by the remainder of
the ammonia in order to br;ng the pH to neutrality. Minor
ingredients are added to the mixture and the composition
is then pH trimmed with citric acid to give a pH of 6.6
before the viscosity is adjusted to 200cp.
Exampl _
The following composition is prepared using the same
materials as in Example 1.
C12_13 Alkyl sulphate 9.6) incorporating 1.24
C12_13 ~lkyl (EO)3 sulphate 11.4) oP 4l part iMn++nid
Cll 8 linear alkyl benzene 14.2) the level of Mg
~ ) corresponding to
sulphonate 0.5X where X is the
Narrow cut Coconut mono- 4.0 number of moles of
alkyl sulphate.
ethanolamlde
Ethanol 8.0
Minors 1.3
Water 51.5
The alkyl benzene is sulphonated and neutralized with
a heel of ammonia, water and ethanol to form ammonium
alkyl benzene sulphonate. The C12-C13 alcohol
~()133
- 13 -
and the C12-Cl3 alcohol ethylene oxide condensate are
blended together and sulphated using chlorosulphonic
acid and neutralized using the previously formed alkyl
benzene sulphonate solution as a heel to which magnesium
hydroxide and additional water have been added. After
reaction the pH of the paste is approximately 2.0 and
is raised to 6.0 using additional ammonia. The coconut
monoethanol amide is then added to this mixture followed
by the balance of the water and the minor ingredients.
Finally the pH is trimmed to 6.6 using citric acid and
the viscosity adjusted to 200 cp.
EXAMPLE III
A composition having the following formulation is
prepared using the method and materials of Example II.
15 C12_13 alkyl sulphate9.6 incorpor~ting 1.24
parts NH4 ion and
12-13 alkyl (EO)3 sulphate 9.6 0.40 parts Mg +~on,
the level of Mg
corresponding to
Cll.8 linear alkyl benzene 16.0 0.5X where X is the
sulphonatenumber of moles of
alkyl sulphate
Whole cut coconut monoethanol- 4.0
amide
Ethanol 8.0
Minors 1.3
Water 51.5
Example IV
A composition having the following formulation is
prepared using the method and materials of Example I.
Cl2-Cl3 alkyl sulphatelO.9 incorpor~ting 1.47
parts NH4 ion and 0.46
Cl2-C13 alkyl (EO)3 sulphate 4.9 Mg ion, the level
corresponding to 0.5X
Cll.8 linear alkyl benzene 24.2 where X is the number
sulphonateof moles of alkyl
sulphate.
Ethanol 8.0
Minors 1.5
Water 50-5
11f~0133
EXAMPLE V
The following composition was prepared using the
method of Example I.
C12-C13 alkyl sulphate 8.6) incorportting 1.24
parts NHa ion+~nd
C12-C13 alkyl (EO)2 sulphate 10.4) 0.37 par~s Mg ion
Cll 8 linear alkyl benzene 14.2
sulphonate
C12 alkyl mono ethanolamide 4.0
Ethanol 10.0
