Note: Descriptions are shown in the official language in which they were submitted.
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ChEANING COMPOSITION COMPRISING POhYETHYhENE GhYCOh, A
SYNTHETIC ANIONIC SURFACTANT AND AN AMPHOTERIC SURFACTANT
The present invention relates to a liquid detergent
composition and, in particular, a mild detergent composition
suitable for cleansing the skin and hair and comprising a
synthetic anionic surfactant, an amphoteric surfactant and a
polyethylene glycol.
Traditionally, soap has been an essential component of
personal washing compositions both in the solid and liquid
form. However, whilst soap based formulations deliver an
abundance of lather, soap is considered to be a harsh
surfactant which is likely to damage the stratum corneum, i.e
the outer layer of the skin, washed with it. Consequently,
there has been a move to replace soap, at least partially, in
such formulations with synthetic surfactants such as sodium
lauryl ether sulphate, commonly referred to as SLES.
Formulations based on such anionic surfactants alone tend to
produce an abundance of lather during use but the lather is
perceived as being of poor quality by the consumer due to its
thinness and lack of creaminess. To improve the quality of
the lather amphoteric surfactants, and in particular,
betaines are commonly added to such compositions as a
cosurfactant. Since betaines are mild, their incorporation
also leads to improvements in the mildness of the overa-11 . .
composition. As the ratio of amphoteric surfactant to
synthetic anionic surfactant is increased so the composition
becomes milder however, this is at the expense of the
quantity of lather produced during its use.
Attempts to improve lather by increasing the total level of
active detergent components in the compositic; have been
unsuccessful. Hence, there has been little exploitation of
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very mild detergent compositions, particularly in those
countries where the quantity and quality of the lather is
perceived important by users of such products.
We have now found that for formulations comprising a
synthetic anionic surfactant and an amphoteric surfactant in
a weight ratio in the range 4:1 to 0.1:1 for optimum
mildness, lather can be boosted by the addition of specified
polyethylene glycols.
Polyethylene glycol has been suggested as an optional
component for detergent compositions comprising a mixture of
anionic and amphoteric surfactants and an insoluble nonionic
oil such as in W093/19199. However, in this reference it is
mentioned as one of a large group of nonocclusive
moisturisers. There is no suggestion that it can be used as
a lather booster.
The invention provides an aqueous liquid detergent
composition comprising a synthetic anionic surfactant and an
amphoteric surfactant in a weight ratio within the range 4:1
to 0.1:1 and from 10~ to 40~ by weight of a polyethylene
glycol having a molecular weight of 200 to not more than
100,000.
~n~on-c Surfactant
Synthetic anionic surfactants are an essential component of
the invention as claimed. Suitable materials include fatty
acyl isethionates of formula:
RCO-.CH-.CH-.SO,M
where R is an alkyl or alkenyl group of 7 to 21 carbon atoms
and M is a solubilising cation such as sodium, potassium,
ammonium or substituted ammonium. Preferably at least three
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quarters of the RCO groups have l2 to 18 carbon atoms and may
be derived from coconut, palm or a coconut/palm blend.
Other possible anionic detergents include alkyl glyceryl
ether sulphate, sulphosuccinates, taurates, sarcosinates,
sulphacetates, alkyl phosphate, alkyl phosphate esters and
acyl lactylate, alkyl glutamates and mixtures thereof.
Sulphosuccinates may be monoalkyl sulphosuccinates having the
formula : R~'O~CCH~CH ( S03M) CO:M; and amido-MEA sulphosuccinates
of the formula : R'CONHCH_CH=O :CCH-,CH ( SO~M) COlM; wherein R
ranges from Cq-C_o alkyl, preferably C~-_-C1~ alkyl and M is a
solubilising cation.
Sarcosinates are generally indicated by the formula:
RSCON ( CH3 ) CH ~C02M, wherein R'' ranges f rom C9-Coo alkyl ,
preferably C12-C1; alkyl and M is a solubilising canon.
Taurates are generally identified by the formula:
RSCONR6CH,CH:S03M, wherein R-'' ranges from C~-C~~ alkyl,
preferably C1~-Cl alkyl, R' ranges from C1-Cn alkyl, and M is a
solubilising cation.
More preferably the anionic surfactant is an alkyl ether
sulphate of formula:
R''O (CH_CH:O) nSO~,M
where R' is an alkyl group of 8 to 22 carbon atoms, n ranges
from 0.5 to 10 especially 1.5 to 8, and M is a solubilising
canon as before, most preferably the anionic surfactant is
sodium lauryl ether sulphate.
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Amr~hnr.Pr,'_c Surfactant
Suitable amphoteric --surfactants are detergents which have an
alkyl or alkenyl group of 7 to 18 carbon atoms and comply
with an overall structural formula
0 RZ
R1- ( -C-NH ( CHz ) m- ] n-N+-X-Y
R
where R1 is alkyl or alkenyl of 7 to 18 carbon,atoms R' and R'
are each independently alkyl, hydroxyalkyl or carboxyalkyl of
1 to 3 carbon atoms
M is 2 to 4
n is 0 or 1
X is alkylene of 1 to 3 carbon atoms optionally
substituted with hydroxyl, and
Y is -CO:- or -SOs-
They include simple betaines of formula:
R'
Rz -- N- -- CH.,CO-
R'
and amido betaines of formula:
R'
R1-CONH ( CHI ) _-N~-CH ,CO :-
R'
where m is 2 or 3.
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In both formulae Rl , R' and R3 are as def fined previously . R1
may, in particular, be a mixture of Cl~ andC14 alkyl groups
derived from coconut so that at least half of the groups R1
have 10 to 14 carbon atoms. R2 and R3 are preferably methyl.
5
A further possibility is a sulphobetaine of formula:
R2
R1-N+- ( CHz ) 350_,-
R'
or
R-
R1 -CONH (CHZ)mN~- (CH~) ~,SO_
R'
where m is 2 or 3, or variants of these in which - (CHZ) x,503-
is replaced by
OH
-CH~ CHCH~SO;-
R1, R~ and R~ in these formulae are as defined previously.
Amido betaines are most preferred.
The total level of anionic and amphoteric surfactant in the
composition according to the invention preferably lies within
the range 5 to 50 wto, most preferably 7 to 35 wto.
For optimum mildness, the weight ratio of the anionic
surfactant to amphoteric surfactant should lie within the
range 4:1 to 0.1:1, preferably 3:1 to 0.5:1, more preferably
2:1 to 0.5:1.
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s
The composition may also contain nonionic surfactants.
Suitable nonionic surface active agents include alkyl
polysaccharides, lactobionamides, ethylene glycol esters,
glycerol monoethers, polyhydroxyamides (glucamide), primary
and secondary alcohol ethoxylates, especially the C8_Zo
aliphatic alcohols ethoxylated with an average of from 1 to
20 moles of ethylene oxide per mole of alcohol.
Preferably fatty acid soaps are not added to the detergent
compositions of the invention. However, if present, they are
at a level of not more than 25 wto based on the level of
synthetic anionic surfactant.
Polvethvlene Glvcol
The polyethylene glycol will have a molecular weight of not
more than 100,000; preferably within the range 200 to 25,000
and most preferably within the range 300 to 10,000.
Preferably, the level of polyethylene glycol will be in the
range 2 to 40 wt~, most preferably 4 to 30 wt~.
PEG, besides being a lather booster, also effects the
mildness of. the anionic/amphoteric formulations according to
the invention. This effect is only generally noticeable at
levels of PEG higher than the minimum required for lather
boost i.e. at levels of at least 10 wto and up 30 wto.
Although the compositions of the invention may be self-
structuring generally they will comprise a structurant and/or
a thickener. Suitable materials include swelling clays, for
example laponite; fatty acids and derivatives thereof.arad, in
particular, fatty acid monoglyceride polyglycol ethers;
cross-linked polyacrylates such as Carbopol (TM) (polymers
available from Goodrich); acrylates and copolymers thereof,
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polyvinylpyrrolidone and copolymers thereof; polyethylene
imines; nonionic partial triglycerides; natural gums
including alginates, guar, xanthan and polysaccharide
derivatives including carboxy methyl cellulose and
hydroxypropyl guar; propylene glycols and propylene glycol
oleates; salts such as sodium chloride and ammonium sulphate;
sucrose esters; gellants; and mixtures thereof.
Of the clays, particularly preferred are synthetic hectorite
(laponite) clay used in conjunction with an electrolyte salt
capable of causing the clay to thicken. Suitable
electrolytes include alkali and alkaline earth salts such as
halides, ammonium salts and sulphates; and mixtures thereof.
Further examples of structurants and thickeners are given in
the International Cosmetic Ingredient Dictionary, Fifth
Edition, 1993, published by CTFA (The Cosmetic, Toiletry &
Fragrance Association),
Examples of adjuncts which may be added to the composition of
the invention include deposition aids and, in particular,
anionic polymers such as cationic derivatives of guar gum and
quaternary nitrogen-substituted cellulose ether derivatives
e.g. guar hydroxylpropyl trimonium chloride, available
commercially for example as JaguarTM C13S; pearlescers;
preservatives such as para-hydroxy benzoate esters;
hydrotropes such as alcohols, urea and triethanolamine;
antimicrobials such as antioxidants such as butyl hydroxy
toluene; bactericides; humectants such as glycerol and
sorbitol; sunscreens; plant extracts such as Aloe Vera, witch
hazel and elderflower; colourants; and perfumes.
A further group of particularly preferred optional components
include moisturising ingredients. Suitable materials include
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a) hydrocarbons such as petrolatum;
b) higher fatty acids such as those having 8 to 24 carbon '
atoms;
c) higher fatty alcohols such as those having 8 to 24 '
carbon atoms;
d) esters such as alkyl lactates;
e) essential oils;
f) lipids such as cholesterol, ceramides, sucrose esters
and pseudo-ceramides as described in European Patent
Specification No. 556 957 and phospholipids
g) vitamins;
h) derivatives of alpha hydroxy acids such
as materials of formula
R~ O
R1 - [ O-CH-C ~ mOR'
wherein
Rl is C~,HgNrOs, where P is 0-20, q is 1-41, r is 0-3, and
s is 0-3;
RZ is CCH" where t is 0-20 and a is 1-41;
R' is C"HWN,.O~. where v is 0-20, w is 1-41, x
is 0-3 and y is 0-3 or a metallic, ammonium or
alkanolammonium anion and m is 1-10; and
i) mixtures of any of the foregoing components.
The compositions of the invention will generally be pourable
liquids or semi-liquids, for example, pastes and will,
preferably, have a viscosity in the range 1000 to 200,000 '
mPas measured at a shear rate of 10s-1 and 25°C in a Haake
Rotoviscometer RV20.
The invention will now be illustrated with reference to the
non-limiting examples.
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In the examples
CAPB was cocoamidopropyl betaine ex Henkel
Clay was LaponiteTM XLS (a synthetic hectorite clay) ex Laporte
PEG 40 partial diglyceride of hardened castor oil was
Cremophor RH410 ex BASF
PEG 80 glycery tallowate was Rewoderm LI 48 ex RewoTM GmbH
SLES was sodium lauryl ether sulphate (3E0) ex Henkel.
All the polyethylene glycols are expressed in terms of their
molecular weight and were supplied by BP and BDH.
In this comparative example prototypes comprising SLES and
CAPE were prepared by heating and mixing the SLES and CAPB
using a conventional stirrer.
Example aSLES/CAPB ratio ~o~al, SLES/CAPB wt%
la 2:1 10
lb 2:1 20
lc 1:1 10
1d 1:1 ~ 20
The lather volume of these prototypes was measured by the
following method in which 20 panellists were used. Each
panellist worn a pair of surgical gloves which were turned
inside out. The gloved hands were washed with soap to remove
the talc and then rinsed with water. 0.5 g of product was
applied to a gloved hand of each panellist. Lather was
generated by rubbing the hands together for 40 seconds. An
inverted funnel connected to a measuring cylinder was placed
in a sink of water at ambient temperature. Immediately after
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the lather had been generated the panellist placed their
hands under the funnel, whereby foam floated off into the
funnel. The hands were then removed before the position of
the measuring cylinder in the sink was adjusted so that the
5 zero point was level with the water level. The_amount of
foam generated was measured off from the measuring cylinder.
The lather performance of the four prototypes was found to be
the same, within experimental error, demonstrating that the
10 lather volume for a given SLESICAPB ratio cannot be increased
merely by increasing the total level of surfactant.
Exam»1_eS 2-11
In these examples a series of prototype formulations with a
SLES/CAPB ratio within the range 2:1 to 1:2 were prepared by
heating and mixing the SLES, CAPS and PEG 600 using a
conventional stirrer.
Lather volume was measured as described above. The results
are given in Table 1, where the lather volume is expressed in
terms of significance level over the control which contained
no added PEG.
V3here lather volume is expressed as '>' this means at 950
significance level.
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E~am~~.e Formu lation BEG wt9s Lather
p
Volume
SLES/CAPB TOTAL
Measurement
RATIO SLES/CAPB
Wt o
2 1:1 10 30 >Control
" 1.0 =Control
Cont rol ~~ ~~
4 1:1 20 2.5 >Control
5 '~ " 5.0
6
" 10.0
" 15.0
Control ~~ ~~ _
2:1 10 40.0 >Control
" 50.0 =Control
Cont ro 1 ~~ ~~
10 1:2 10 5.0 >Control
11 " " 10.0 >Control
Control
_ _
.20 The results demonstrate that it is possible to boost the
lather in formulations comprising SLES and CAPB in different
weight ratios and total active concentrat-ions. Lather boost
was achieved over a wide concentration range of added PEG
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i.e. from 2.5 to 30 wtg.
4
Examples 8 and 9 demonstrate that whilst at 40 wtg PEG 600
boosts lather of a formulation comprising SLES and CAPBin a
weight ratio of 2:1, when it is added at a higher level of
50 wt~ there is no improvement over a composition from which
it is absent.
In these examples the effect of the molecular weight of the
PEG on lather boosting was examined. The amount of PEG added
to each prototype formulation was 5 wto.
~xamnle Formulation PEG Lather
Molecular yolume
Weight Measurement
SLES/CAPB TOTAL
RATIO SLES/CAPB
wt o
Comparative 2:1 10 - -
12 " " 1500 >Control
13 " " 6000 "
14 " " 10,000 "
15 " " 100.000 "
16 " " 300,000 =Control
Comparative 2:1 20
1~ ~~ ~~ 1500 >Control
18 " " 4000 >Control
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The results demonstrate that PEG of various molecular weights
present at a level of 5 wto delivers a significant
improvement in lather volume up to and including a molecular
weight of 100,000: PEG with a molecular weight of 300,000
did not provide a lather boost and, furthermore, the
formulation containing this material was unacceptable as it
was perceived as making the skin feel slimy during use.
Examples 19-22
Tn these examples the effect of PEG 600 or PEG 4000 on lather
was examined in a variety of fully formulated products.
Products were prepared by mixing the surface active agents,
PEG and glycerol at elevated temperatures using an order of
addition which avoided the formation of viscous phases.
Thereafter prehydrated Laponite was injected into the blend.
After addition of minors the blend was cooled and emptied
from the mixer.
The lather properties of these products were measured as
described previously and found to be superior to those
products which did not contain PEG.
t
J
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Tl~a~LE 2
Component wt~ Example Example Example Example
19 20 21 22
SLES 3 EO 10.0 8.0 12.0 12.0
CAPB 10.0 5.0 7.5 7.5
Glycerol 5.0 5.0 5.0 5.0
PEG600 5.0 5.0 - -
PEG4000 - - 5.0 5.0
PEG-80 glycerol 3.0 5.0 7.5 -
tallowate
PEG 40 partial - 3.0 3.0 3.0
diglyceride of
hardened castor
oil
Propan-1, 2-diol 3.0 - - -
Clay 0.6 1.5 1.5 1.5
Minors + Water to 100 to 100 to 100 to 100
F'.xample 23
In this example a number of compositions were assessed for-
mildness using a zero test generally as described by Gotte,
Proc. Int. Cong. Surface Active Subs., 4th Edition, Brussels,
J
~, 89-90 (1964). The test determines the amount of amino
acid solubilised from zero under specified conditions. The
solubilised material is determined by a nitrogen assay. The '
results were as follows:
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SLES/CAPB = 1:1 ratio
Total SLES/CAPB = 10 wto
g PEG 600 Zein Score o Nitrogen
5 0 0.21
5 0.20
10 0.18
0.14
10 30 0.15
35 0.14
SLES/CAPB = 2:1
15 Total SLES/CAPB = 10 wto
PEG Mwt o PEG Zein Score
0 0.28
600 20 0.23
20 4000 15 0.19
100,000 5 -0.29
(* all scores were corrected for the N content of CAPB)
The results demonstrate that addition of PEG at levels of
10~ wt or greater improves mildness, as determined by zero
score.
