[0001] The present invention relates to liquid detergent compositions suitable for use especially,
but not exclusively, in fabric washing, shampoos, and above all, in manual dishwashing
operations in both hard and soft water.
[0002] The term "dishes" as used herein means any utensils involved in food preparation
or consumption which may be required to be washed to free them from food particles
and other food residues, greases, proteins, starches, gums, dyes, oils and burnt organic
residues.
[0003] Light-duty liquid detergent compositions such as are suitable for use in washing
dishes are well-known. Many of the formulations in commercial use at the present time
are based on a sulphonate-type anionic detergent, especially an alkyl benzene sulphonate,
in conjunction with an alkyl polyethoxy sulphate (alkyl ether sulphate). The sulphonate-type
detergent generally predominates.
[0004] The use of conventional dishwashing liquids based on alkyl benzene sulphonate (ABS)/alkyl
ether sulphate (AES) or on alkyl sulphate (PAS)/alkyl ether sulphate (AES) is seen
to have deleterious influence on the hand condition of users. Hence mildness in washing-up
liquid is considered a desirable quality, and many specially formulated products on
the market make claims for it.
[0005] Protein denaturation by surfactants is considered to be one of the major causes of
skin irritation and skin roughness induced by surfactants (G Imokawa et al. JOACS
52, 484-489, Dec 1975). The degree of surfactant denaturation of protein depends on
the type of surfactants and their concentration.
[0006] At present, the dishwashing formulations that are on the market which are less interactive
with protein and hence considered to be milder are those based on a combination of
ether sulphates and amine oxides. See for example US-A-3 928 249 (Procter & Gamble).
In place of amine oxides, betaines can also be used. See for example US-A-4 554 098.
However, such formulations - particularly with amine oxides - are expensive, not only
because the active ingredients are expensive, but also because they require a large
amount of expensive hydrotropes such as xylenesulphonate and/or ethanol to produce
liquids which are stable and of acceptable viscosity.
[0007] EP-A-0232153 (Unilever) discloses detergent compositions based upon a mixture of
anionic and nonionic surfactants together with lather boosters, at least some of the
anionic surfactants being alkyl ether sulphate.
[0008] Example 9 of EP-A-0036625 relates to a surfactant system comprising 33% of a 9-10EO
nonionic in combination with PAS, a specified AES mixture and a betaine.
[0009] It is preferred to include high amounts of nonionic surfactants in order to produce
a mild system because such surfactants are inert towards proteins in the skin and
because nonionic-containing formulation require lesser amounts of expensive hydrotropes.
[0010] Nonionics have also been shown to have a good soil removing potential, particularly
of greasy soils often found on dishes. However, nonionics as a class are low foamers
and produce unstable lather.
[0011] GB-A-2 165 855 (Colgate) discloses mild nonionic-based light duty liquid detergents
wherein the nonionic component exceeds 50% by weight of the total detergent content.
However, for reasons stated above, such high nonionic-based formulations would have
foam performance deficiencies.
[0012] US-A-4 554 098 (Colgate) mentioned above discloses a mild dishwashing formulation
based on an alkyl ether sulphate containing-an average of 5 to 12 moles of ethylene
oxide in the molecule. However, such ether sulphates are not commercially easily available.
Also, it is believed that the dioxane level in ether sulphate raw material increases
with the increase in EO content of ether sulphate. Therefore, for ease of commercial
exploitation the use of widely used and generally available ether sulphates containing
less than 5 EO is preferred.
[0013] Therefore there is need for the development of more cost-effective mild dishwashing
formulations, which are based on relatively less expensive detergent raw materials
and which also require lesser amounts of expensive hydrotropes.
[0014] The present invention is based on the realisation that cost-effective mild liquid
dishwashing formulations with adequate performance can be obtained by careful choice
of the active ingredients and their preparation, in particular by restricting the
main anionic detergent active present and including also selected amounts of alkyl
ether sulphate, lather boosters and non-ionic detergent active material.
[0015] According to a first aspect of the present invention, there is provided a stable
detergent composition in liquid or gel form containing from 10 to 80%wt of an active
detergent mixture of primary alkyl sulphate (PAS), alkyl ether sulphate (AES), water
soluble nonionic detergent active material and betaine and/or amine oxide and also
water, CHARACTERISED IN THAT:
a) the AES has an average ethoxylation value of between 1 and 5, and weight ratio
of PAS:AES is in the range 2:1-1:3; and,
b) the molar ratio of PAS to said betaine and/or amine oxide is in the range 3:1-1:3;
and,
c) the nonionic detergent comprises more than 35%, but less than 50% by weight of
the active detergent mixture.
[0016] Compositions of the invention can give performance in detergency tests as good as
those of conventional compositions containing alkyl benzene sulphonate, but are considerably
milder.
[0017] It is particularly surprising that mildness of predominantly nonionic-based formulations
can wholly be maintained by substituting a substantial portion of the nonionic with
ether sulphates containing less than 5 EO, but enhancing the foam performance significantly
and thus improving cost effectiveness.
[0018] Although in principle the concentration of the active detergent mixture may be as
high as desired in the range 10 to 80%, provided that a stable liquid or gel product
can be obtained, the range of 5 to 60% by weight is preferred, and aqueous liquid
compositions with an active detergent mixture in the range of 5 to 40% by weight are
of especial interest.
[0019] Primary alkyl sulphate (PAS) for use in the invention component is preferably of
the formula
ROSO₃X
where R is a C₈ to C₁₈ primary alkyl group and X is a solubilising cation. Suitable
is Dobanol 23A of Shell in which R is predominantly C₁₂ and C₁₃. As will be explained
in more detail below alkyl sulphate is a constituent of alkyl ether sulphates.
[0020] The active detergent mixture may also include one or more other detergent actives
used in liquid compositions, for example alkyl glyceryl ether sulphonates, or alkyl
sarcosinates.
[0021] The second essential component of the active detergent mixture is alkyl ether sulphate
(sometimes called alcohol ether sulphate or alkyl polyethoxy sulphate) having at least
one ethylene oxide residue per molecule. This will normally be provided by incorporating
into the composition an alkyl ether sulphate which is a mixture of materials of the
general formula:
R - (OCH₂CH₂)
n - OSO₃X
wherein R is a C₁₀ to C₁₈ primary or secondary alkyl group, X is a solubilising cation,
and
n, the average degree of ethoxylation, is from 1 to 5, preferably from 3 to 4. Particularly
preferred values of n are 3 and 4. R₃ is preferably a C₁₀ to C₁₆ alkyl group. In any
given alkyl ether sulphate, a range of differently ethoxylated materials, and some
unethoxylated material, will be present and the value of
n represents an average. The unethoxylated material is, of course, alkyl sulphate and
this contributes to the PAS content of the composition.
[0022] The amount of alkyl sulphate in any alkyl ether sulphate will depend on average degree
of ethoxylation
n. When n is 3, alkyl sulphate typically constitutes 15 to 20% of the mixture, and
less than this when
n is 4 or more. When the proportion of alkyl sulphate is low, it may prove convenient
to ignore it. Nevertheless, it contributes to the PAS content of the composition.
[0023] When the average degree of ethoxylation is 2, alkyl sulphate typically constitutes
30% of the mixture provided as "alkyl ether sulphate". Such a mixture can provide
both component PAS and AES.
[0024] We have found that it is not feasible to use alkyl ether sulphate with an average
degree of ethoxylation below 1.5. Unless the alkyl sulphate content of the ether sulphate
is providing much or the whole of component PAS it is preferred that the alkyl ether
sulphate is provided by material with an average of at least 2 or 2.5 ethylene oxide
residues per molecule.
[0025] Alkyl ether sulphate contains molecules with differing numbers of ethylene oxide
residues in a statistical distribution. In an alkyl ether sulphate where the average
degree of ethoxylation is 1.5 or greater, the proportion of molecules with a single
ethylene oxide residue will not be substantially greater than the proportion with
two ethylene oxide residues, nor the proportion with the most frequently encountered
number of ethylene oxide residues (if this is more than two). Therefore this feature
is an observable characteristic of the AES. If the average degree of ethoxylation
is 2 or more, as preferred, the proportion of molecules with a single ethylene oxide
residue will be less than the proportion with two ethylene oxide residues and the
proportion with the most frequently encountered number.
[0026] Preferred alkyl ether sulphates are mixtures of compounds of the above formula
R-(OCH₂CH₂)
n- OSO₃X
in which
n is any positive integer, with the proviso that the average EO value is less than
5.
[0027] Examples of preferred alkyl ether sulphates for use in the present invention are
Dobanol (Trade Mark) 23-3 from Shell in which the degree of ethoxylation (n) is 3
and the equivalent material in which the degree of ethoxylation is 4. These materials
are based on C₁₂-C₁₃ (50% of each) primary alcohol (about 75% straight chain, 25%
2-methyl branched). Another preferred material is an alkyl ether sulphate based on
Lial (Trade Mark) 123 from Chimica Augusta, which is a branched chain primary alcohol
with a degree of ethoxylation of 3 to 4 and with a similar alkyl chain length distribution
to Dobanol 23. Also preferred is Empicol MD (Trade Mark) from Albright and Wilson,
with degree of ethoxylation of 4 and based on middle-cut coconut alkyl group.
[0028] A suitable example of a secondary alcohol ether sulphate is a material derived from
an alcohol such as Tergitol 15/S/3 (trade mark) of Union Carbide (this material itself
is not at present available). The conventional process of manufacture of secondary
alkyl ether sulphate is such that there is only a very small quantity of alkyl sulphate
in the product.
[0029] AES generally provides at least 12% of the active detergent mixture, preferably it
provides at least 20 or 30%. It preferably provides not more than 40% of the active
detergent mixture.
[0030] The solubilising cations of the anionic detergent actives of the PAS and AES, denoted
as X in the formulae above, may be any which provide the desired solubility of the
anionic material. Monovalent cations such as alkali metal ions, ammonium and substituted
ammonium are typical. Divalent ions giving adequate solubility may be used, and especially
magnesium ions may be present to improve soft water performance and can be incorporated
as magnesium salt of the anionic actives or as inorganic magnesium salts, or in the
hydrotrope system.
[0031] Betaine and amine oxide can be used as such or in a mixture. It is preferred to avoid
using substantial amounts of the betaine or amine oxide, especially amine oxides,
for the sake of economy and consequent cost effectiveness. Preferably then the amount
of amine oxide is not more than 10% by weight of the active detergent mixture. Preferably
the amount of betaine is not more than 30% by weight of this mixture. The total amount
of amine oxide and betaine is preferably not more than 30% and more preferably not
more than 15% or 10% by weight of the active detergent mixture. It is preferred to
use betaines alone.
[0032] Suitable betaines include simple betaines of formula

and amido betaines of formula:

[0033] In both formulae R is a C₈ to C₁₈ straight or branched alkyl group. It may be a lauryl
group or a middle cut coconut alkyl group. R₆ and R₇ are each C₁ to C₃ alkyl or C₁
to C₃ hydroxyalkyl. Examples of sulphobetaines have the above formulae with -CH₂CO
-2 replaced by

[0034] A suitable simple betaine is Empigen BB (TM) from Albright & Wilson. It has the formula
quoted above in which R is C₁₂ to C₁₄ alkyl, derived from coconut, and R₆ and R₇ are
both methyl. Also preferred is Tego L7 (TM) from Goldsmidt, which has a whole coconut
alkyl group.
[0035] Suitable amine oxides have the formula

wherein R is a straight or branched chain C₈ to C₁₈ alkyl group and R₆ and R₇ are
each C₁ to C₃ alkyl, or C₁ to C₃ hydroxyalkyl. A suitable amine oxide is Empigen OB
(TM) from Albright & Wilson. In it R is middle-cut coconut alkyl and R₆ and R₇ are
both methyl.
[0036] The water-soluble non-ionic detergent active materials, are exemplified by materials
conventionally used in detergent formulations. The betaines and amine oxides do not
form part of the nonionic.
[0037] The nonionic is preferably a polyalkoxylated material, notably it is one or more
ethoxylated non-ionic detergent active materials. It is then desirable that such material
should have an HLB value in the range from 12.0 to 16.0.
[0038] The non-ionic may be a polyethoxylated aliphatic alcohol having an alkyl chain length
of from C₈ to C₁₈ preferably C₈ to C₁₆, and an average degree of ethoxylation of from
4 to 14. Suitable nonionic detergents include short-chain high-foaming ethoxylated
alcohols of the general formula
R - (OCH₂CH₂)
m - OH
wherein R is an alkyl group, preferably straight-chain, having from 8 to 18, better
8 to 16 and yet more preferably 9 to 12, carbon atoms, and the average degree of ethoxylation
m is from 5 to 14, more preferably 6 to 12. An especially preferred nonionic detergent
is Dobanol 91-8 from Shell, in which R is C₉-C₁₁ (predominantly straight-chain) and
m is 8, or alternatively Lialet C₁₁-10 EO.
[0039] Alternative suitable materials are those in which R is a secondary alkyl having from
8 to 18, preferably 11-15, carbon atoms and m is from 5 to 14, preferably 6-12. An
example is Tergitol (TM) 15/S/12 of Union Carbide (not available at present) or the
material of the Softanol (TM) A series (from Japan Catalytic).
[0040] Preferably the polyethoxylated alcohol mixture is stripped, to reduce odour imparted
to the composition.
[0041] Another possibility for the nonionic is an ethoxylate alkanolamide of the general
formula

wherein R is a straight or branched alkyl having from 7 to 18 carbon atoms,
- R₈
- is an ethyleneoxy or propyleneoxy group
- Y
- is an hydrogen or -R₈(CH₂CH₂O)qH
- p
- is 1 or more and q is 0, 1 or more
- R
- may be lauryl or coconut alkyl. Examples of ethoxylated alkanolamide are Amidox L5
and Amidox C5 from Stepan Chemical Company.
[0042] Further possibilities for the nonionic are ethoxylated alkylphenols and ethoxylated
fatty acids, ie. polyethyleneglycol esters of fatty acids.
[0043] The nonionic constitutes more than 35% by weight of the active detergent mixture,
but less than 50%.
[0044] Optionally present within the active detergent mixture of the composition of the
invention may be one or more mono- or dialkanolamides, preferably C₈ to C₁₈, more
preferably C₁₀-C₁₈ carboxylic acid mono- or di(C₂-C₃) alkanolamides. These have the
general formulae
R₄ - CO - NHR₅ and R₄ - CO - N(R₅)₂
respectively
wherein R₄ is a C₇-C₁₇ aliphatic group, preferably straight- chain and preferably
saturated, and R₅ is a hydroxyethyl or hydroxypropyl group. R₅ is preferably a 2-hydroxyethyl
group.
[0045] Materials of this type are generally made from fatty acids of natural origin and
contain a range of molecules having R₄ groups of different chain lengths; for example,
coconut ethanolamides consist predominantly of C₁₂ and C₁₄ material, with varying
amounts of C₈, C₁₀, C₁₆ and C₁₈ material. Preferred are ethanolamides derived from
so-called middle cut coconut fatty acid, most preferably from lauric acid.
[0046] The mono- and di-ethanolamides may range from 5% to 20% of the detergent mixture.
[0047] As well as the active detergent mixture and water, the liquid detergent compositions
of the invention will generally need to contain one or more hydrotropes.
[0048] Hydrotropes are materials present in a formulation to control solubility, viscosity,
clarity and stability but which themselves make no active contribution to the performance
of the product. Examples of hydrotropes include lower aliphatic alcohols, especially
ethanol; urea; lower alkylbenzene sulphonates such as sodium, toluene and xylene sulphonates
and combinations of these. Preferred are alcohol, urea and xylene sulphonate. Hydrotropes
are expensive and take up room in a formulation without contributing to its performance,
and it is therefore desirable to use as small quantities of them as possible.
[0049] For example, the use of amine oxides as mentioned above requires a large amount of
alcohol as hydrotrope. For this reason and because of expense, it is preferred to
avoid the use of a substantial amount of any tertiary amine oxide in the present invention.
[0050] In preferred forms of this invention the weight of hydrotrope in the composition
is not more than 12% of the weight of the active detergent mixture.
[0051] The compositions of the invention may also contain the usual minor ingredients such
as perfume, colour, preservatives and germicides.
[0052] The stable liquid detergent compositions of the invention may be used for all normal
detergent purposes especially where foaming is advantageous, for example, fabric washing
products, general purpose domestic and industrial cleaning compositions, carpet shampoos,
car wash products, personal washing products, shampoos, foam bath products, and above
all, manual dishwashing.
[0053] The invention is further illustrated by the following nonlimiting Examples.
EXAMPLES
[0054] The foaming performance and mildness of various aqueous formulations were compared.
These formulations I and II falling within the scope of the present application were
compared with a comparable composition (A) containing over 50% by weight of nonionic
active.
[0055] Foaming performance was assessed by means of a modified Schlachter-Dierkes test based
on the principle described in
Fetter und Seifen 1951,
53, 207. A 100 ml aqueous solution of each material tested, having a concentration of
0.04% active detergent in 24°H water (French hardness) at 45°C was rapidly oscillated
using a vertically oscillating perforated disc within a graduated cylinder. After
the initial generation of foam, increments (0.2 g) of soil (9.5 parts commercial cooking
fat, 0.25 parts oleic acid, 0.25 parts stearic acid and 10 parts wheat starch in 120
parts water) were added at 15 second intervals (10 seconds' mild agitation and 5 seconds'
rest) until the foam collapsed. The result was recorded as the number of soil increments
(NSI score): a score difference of 6 or less is generally regarded as insignificant.
Each result was typically the average of 3 or 4 runs.
[0056] Several in-vitro and in-vivo methods for evaluating protein denaturation potency
of surfactants and their mixtures have been reported (see Miyazowa et al, Int J Cos
Sci
6 33-46 1984, and the references cited therein). One such method is the study of interaction
of detergents with acid phosphatase enzyme either from skin (Prottey et al, Int J
Cos Sci
6 263-273 1984) or from wheatgerm (Tanaka et al, Anal Biochem
66 489-498 1975).
[0057] In vivo mildness of formulations can be assessed using a flex wash test. In this
test neat products were rubbed on the forearm of panellists and rinsed. The process
was repeated four times a day for five days and the level of erythema developed was
assessed by trained assessors.
[0058] A comparison of wheatgerm acid phosphatase (WGAP) test and flex wash test results
indicated that formulations giving less than 50% enzyme inhibition under the test
conditions are substantially mild; any mildness differences between products giving
<40% inhibition do not show any detectable mildness differences in flex wash test,
indicating that the enzyme test is very sensitive and that in a real life situation
there is a threshold level of protein denaturation below which all actives and products
are indistinguishably mild. The results of the WGAP test are expressed as percentage
inhibition (ie 100% minus percentage activity remaining). Water gave no inhibition
at all, ie 100% of activity remained.
|
I |
II |
A |
Lialet 123-3S¹ |
10 |
- |
- |
Lialet 123-4S¹ |
- |
10 |
- |
Dobanol 23-A |
- |
- |
8 |
Lialet 123-S |
5 |
5 |
- |
Lialet C₁₁ 10EO³ |
15 |
15 |
22 |
Empigen BB⁴ |
6 |
6 |
6 |
Empigen LME⁵ |
4 |
4 |
4 |
|
Plunger Test (0.04% AD) |
|
|
|
24°FH |
46 |
46 |
41 |
5°FH |
45 |
46 |
43 |
|
% WGAP Inhibition |
23 |
21 |
12 |
1 - Alkyl Ether Sulphate |
2 - Primary Alkyl Sulphate |
3 - Nonionic |
4 - Betaine |
5 - Ethanolamide |
[0059] The Examples show that formulations I and II give a greater foaming performance than
A. Although % WGAP inhibition of A is less than I and II, the effective mildness is
no different, as explained above. Thus compositions of the present invention give
a combination of mildness and performance.
1. Stabile Reinigungsmittelzusammensetzung in flüssiger Form oder Gelform, die 10 bis
80 Gew.-% eines aktiven Reinigungsmittelgemisches eines primären Alkylsulfats (PAS),
von Alkylethersulfat (AES), eines wasserlöslichen nichtionischen Reinigungsmittelaktivmaterials
und von Betain und/oder Aminoxid und ferner Wasser enthält und dadurch gekennzeichnet
ist, daß:
a) das AES einen mittleren Ethoxylierungswert zwischen 1 und 5 aufweist und das Gew.-Verhältnis
PAS/AES in einem Bereich von 2/1 bis 1/3 liegt und
b) das Molverhältnis PAS/genanntes Betain und/oder Aminoxid in einem Bereich von 3/1
bis 1/3 liegt und
c) das nichtionische Reinigungsmittel mehr als 35, jedoch weniger als 50 Gew.-% des
aktiven Reinigungsmittelgemisches ausmacht.
2. Zusammensetzung nach Anspruch 1, wobei das Gew.- Verhältnis PAS/AES in einem Bereich
von 2/1 bis 1/2 liegt.
3. Zusammensetzung nach einem der vorhergehenden Ansprüche, wobei die Gesamtmenge an
Aminoxid und Betain nicht mehr als 20 Gew.-% des aktiven Reinigungsmittelgemisches
beträgt.
4. Zusammensetzung nach einem der vorhergehenden Ansprüche, die im wesentlichen kein
Aminoxid enthält.
5. Zusammensetzung nach einem der vorhergehenden Ansprüche, wobei das Alkylethersulfat
aus einem Gemisch von Materialien der allgemeinen Formel:
R - (OCH₂CH₂)n - OSO₃X
wobei R für eine C₁₀-C₁₈-Alkylgruppe steht, X ein löslichmachendes Kation ist und
n den mittleren Ethoxylierungsgrad angibt, wenn er zwischen 2 und 5 liegt, besteht.
6. Reinigungsmittelzusammensetzung nach einem der vorhergehenden Ansprüche, wobei das
Alkylethersulfat (b) aus einem primären Alkylethersulfat besteht, worin die Alkylgruppen
R derart sind, daß Materialien mit einer Alkylkettenlänge von 14 Kohlenstoffatomen
oder mehr weniger als 20% ausmachen und der mittlere Ethoxylierungsgrad n 3 bis 5 beträgt.
7. Zusammensetzung nach einem der vorhergehenden Ansprüche, wobei der nichtionische Bestandteil
ein Material einer Kettenlänge von weniger als 12 Kohlenstoffatomen ist.
1. Une composition détergente stable sous forme d'un liquide ou d'un gel comprenant 10
à 80 % en masse d'un mélange détergent actif composé de sulfate d'alkyle primaire
(SAP), d'alkylsulfate d'éther (ASE), d'une matière détergente active non ionique soluble
dans l'eau et de bétaïne et/ou d'oxyde d'amine, et également d'eau, CARACTERISEE EN
CE QUE :
a) l'ASE présente une valeur d'éthoxylation moyenne comprise entre 1 et 5, et un rapport
de masse entre SAP et ASE compris dans la gamme allant de 2:1 à 1:3 ; et
b) le rapport molaire entre SAP et ladite bétaïne et/ou l'oxyde d'amine est compris
dans la gamme allant de 3:1 à 1:3 ; et
c) l'agent détergent non ionique comprend plus de 35 % mais moins de 50 % en masse
du mélange détergent actif.
2. Une composition selon la Revendication 1, dans laquelle le rapport de masse entre
SAP et ASE est compris dans la gamme allant de 2:1 à 1:2.
3. Une composition selon l'une quelconque des Revendications précédentes, dans laquelle
la quantité totale d'oxyde d'amine et de bétaïne n'excède pas 20 % en masse du mélange
détergent actif.
4. Une composition selon l'une quelconque des Revendications précédentes, qui ne contient
substantiellement pas d'oxyde d'amine.
5. Une composition selon l'une quelconque des Revendications précédentes, dans laquelle
l'alkylsulfate d'éther est fourni sous forme d'un mélange de matières présentant la
formule suivante :
R - (OCH₂CH₂)n - OSO₃X
où R est un groupe alkyle en C₁₀ à C₁₈, X est un cation solubilisant, et n, correspondant
au degré moyen d'éthoxylation, est compris entre 2 et 5.
6. Une composition détergente selon l'une quelconque des Revendications précédentes,
dans laquelle l'alkylsulfate d'éther (b) est fourni par un alkylsulfate d'éther primaire
dans lequel les groupes alkyle R sont tels que moins de 20 % de matière présentant
une chaîne alkyle de longueur C₁₄ ou plus est présente, et le degré moyen d'éthoxylation
n est compris entre 3 et 5.
7. Une composition selon l'une quelconque des Revendications précédentes, dans laquelle
l'agent non ionique est une matière présentant une longueur de chaîne inférieure à
C₁₂.