Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DETERGENT COMPOSITION
This invention relates to a detergent composition,
in particular to a detergent composition for washing
fabrics.
Fabric washing compositions contain, as an essential
ingredient, a surfactant system whose role is to assist
in the removal of soil from the fabric and its suspension
in the wash liquor. Suitable detergent active materials
fall into a number of classes, including anionic,
nonionic and cationic materials and marketed products
contain materials selected from one or more of these
classes.
The most widely used anionic detergent active
materials are the alkyl benzene sulphonates and these
provide satisfactory results especially at high
temperatures. There has been a desire to find
alternative anionic surfactants for use in circumstances
when alkyl benzene sulphonates are undesirable, but
generally speaking the performance of other anionic
detergent active materials is unsatisfactory.
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Among such alternative anionic surfactants are the
primary alcohol sulphates (PAS) otherwise known as alkyl
sulphates. PAS may be derived from both synthetic and
natural alcohols containing from about 8 to 18 carbon
atoms. Examples of suitable alcohols which can be used
in alkyl sulphate manufacture include decyl, lauryl,
myristyl, palmityl and stearyl alcohols and the mixture
of fatty alcohols derived by reducing the glycerides of
tallow and coconut oil. Natural alcohols, for example
tallow or coconut alcohol, give rise to straight chain,
or linear, PAS. Synthetic alcohols for example those
produced by the Oxo process can give rise to straight or
branched chain PAS.
In the past PAS derived from tallow fat that is to
say linear PAS has been recommended for use in fabric
washing compositions. Thus, GB 1 399 966 (The Procter
and Gamble Company) discloses a detergent composition in
which the surfactant system is a mixture of sodium tallow
alkyl sulphate and a nonionic detergent active material.
However, tallow PAS suffers from the disadvantage that
its performance at low temperatures is poor. With the
trend towards lower wash temperatures this becomes a
serious disadvantage.,
GB 1 399 966 referred to above also discloses the
possibility of using the PAS derived from coconut oil,
also linear. The performance of tallow PAS at low
temperatures is poor.
The consumer expects a single product to perform
satisfactorily both at high and low temperatures, neither
tallow PAS nor coconut PAS can achieve this.
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In EP 342 917A (Unilever) it is suggested that a PAS
which has a wider spread of chain lengths than is derivable
from either tallow or coconut alcohol can perform better
than tallow PAS at low temperatures and better than coconut
PAS at higher temperatures. The PAS disclosed in
EP 342 917A are derived from either synthetic or natural
alcohols but are all linear PAS.
US 3 480 556 (Atlantic Richfield) discloses C1/C2
branched PAS in a formulation for dishwashing.
JP 47 021 232B (Nissan) discloses a detergency negative for
the replacement of C~1 linear PAS with branched PAS of
unspecified branching.
We have now found that there are benefits in
performance, particularly in the field of the removal of
oily soil, when certain specific branched PAS materials are
used, especially when they are combined with certain types
of nonionic surfactant. These benefits can be seen over a
range of temperatures.
Thus according to a first aspect of the present
invention there is provided a detergent composition for
washing fabrics, the composition comprising a surfactant
system (2 to 50 wt%) and a detergency builder system (5-
60 wt%), wherein the surfactant system comprises an anionic
surfactant the major ingredient of which is a primary alkyl
sulphate having a primary alkyl chain length of between 10
and 20 carbon atoms and comprising both linear and branched
material, wherein more than 10% by weight of the total
primary alkyl sulphate is branched, and more than 5% by
weight of the total primary alkyl sulphate comprises
material wherein the branches contain at least 4 carbon
atoms.
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In compositions of this invention, the branched PAS
preferably contains between 15 and 70 wt% of branching, and
most preferably between 30 and 65 wt% of branching, based
on the total weight of PAS.
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It is preferred to use braffched PAS having a range
of primary alkyl chain lengths for example between 12 and
18 carbon atoms, or between 12 and 16 carbon atoms, most
preferably between 13 and 15 carbon atoms.
The water soluble salts of these anionic surfactants
are preferred, especially the alkali metal salts thereof.
Preferred compositions according to the invention
include from 2% to 50%, such as from 4% to 30% by weight
of the surfactant system.
In addition to the branched PAS materials according
to the invention, other PAS materials may be included in
the composition, for example linear PAS.
The compositions of the invention also preferably
contain a nonionic surfactant. We have found it to be of
advantage if such a nonionic surfactant has an HLB of
less than 10.5, preferably less than 10.
Suitable nonionic surfactants which may be used are
the reaction products of compounds having a hydrophobic
group and a reactive hydrogen atom, for example aliphatic
alcohols, acids, amides or alkyl phenols with alkylene
oxides, especially ethylene oxide either alone or with
propylene oxide. Specific nonionic detergent compounds
are alkyl (C6-C22) phenols-ethylene oxide condensates,
the condensation products of aliphatic (C8-C18) primary
or secondary linear or branched alcohols with ethylene
oxide, and products made by condensation of ethylene
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oxide with the reaction products of propylene oxide and
ethylenediamine.
When alkylene oxide adducts of fatty materials are
used as the nonionic surfactants, the number of alkylene
oxide groups per molecule has a considerable effect upon
the HLB of the nonionic surfactant. The chain length and
nature of the fatty material is also influential, and
thus the preferred number of alkylene oxide groups per
molecule depends upon the nature and chain length of the
fatty material.
We have found it of advantage that the weight ratio
between the anionic surfactant and the nonionic
surfactant lies between 10:1 and 1:4, most preferably
between 4:1 and 1:3.
The surfactant system may include other surfactant
materials in addition to the specified alkyl sulphate and
the above mentioned nonionic materials. These other
surfactant materials may be selected from other anionic
detergent active materials, zwitterionic or amphoteric
detergent active materials or mixture thereof.
Any such further surfactant materials should
preferably be present at a level which is no more than
25% preferably not more than 10% of the total amount of
surfactant in the composition.
The other anionic detergent active materials may be
the usual water-soluble alkali metal salts of organic
sulphonates having alkyl radicals containing from about 8
to about 22 carbon atoms, the term alkyl being used to
include the alkyl portion of higher acyl radicals.
Examples of suitable synthetic anionic detergent
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compounds are sodium and potassium alkyl (Cg-C20) benzene
sulphonates, particularly sodium linear secondary alkyl
(C10-Cl5) benzene sulphonates; sodium alkyl glyceryl
ether sulphates, especially those ethers of the higher
alcohols derived from tallow or coconut oil and synthetic
alcohols derived from petroleum; sodium coconut oil fatty
monoglyceride sulphates and sulphonates; the reaction
products of fatty acids such as coconut fatty acids
esterified with isethionic acid and neutralised with
sodium hydroxide; sodium and potassium salts of fatty
acid amides of methyl taurine; alkane monosulphonates
such as those derived by reacting alpha-olefins (C8-C20)
with sodium bisulphite and those derived from reacting
paraffins with SO2 and C12 and then hydrolysing with a
base to produce a random sulphate.
The compositions of the invention may contain a
detergency builder material, this may be any material
capable of reducing the level of free calcium ions in the
wash liquor and will preferably provide the compositions
with other beneficial properties such as the generation
of an alkaline pH and the suspension of soil removed from
the fabric. The amount of builder material in a
composition of this invention may in particular be from
15% to 60% by weight of the composition.
Examples of phosphorous-containing inorganic
detergency builders, when present, include the
water-soluble salts, especially alkali metal
pyrophosphates, orthophosphates, metaphosphates,
polyphosphates and phosphonates. Specific examples of
inorganic phosphate builders include sodium and potassium
tripolyphosphates, orthophosphates and
hexamataphosphates.
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Examples of non-phosphorous-containing inorganic
detergency builders, when present, include water-soluble
alkali metal carbonates, bicarbonates, silicates and
crystalline and amorphous aluminisilicates. Specific
examples include sodium carbonate (with or without
calcite seeds), potassium carbonate (with or without
calcite seeds), sodium and potassium bicarbonates and
silicates.
Examples of organic detergency builders, when
present, include the alkali metal, ammonium and
substituted ammonium polyacetates, carboxylates,
polycarboxylates, polyacetyl carboxylates and
polyhydroxysulphonates. 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.
It is preferred that the compositions according to
the invention be alkaline, that is at the concentration
of 1 g/l in distilled water at 25C the pH should be at
least 8, preferably at least 10. To this end the
compositions may include a water-soluble alkaline salt.
This salt may be a detergency builder or a non-building
alkaline material.
Apart from the ingredients already mentioned, a
number of optional ingredients may also be present.
Examples of other ingredients which may be present
in the composition include fabric softening agents such
as fatty amines, fabric softening clay materials, lather
boosters such as alkanolamides, particularly the
monoethanolamides derived from palm kernel fatty acids
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and coconut fatty acids, lather depressants,
oxygen-releasing bleaching agents such as sodium
perborate and sodium percarbonate, peracid bleach
precursors, chlorine-releasing bleaching agents such as
tricloroisocyanuric acid, inorganic salts such as sodium
sulphate, and, usually present in very minor amounts,
fluorescent agents, perfumes including deodorant
perfumes, enzymes such as proteases, cellulases and
amylases, lipases germicides and colourants.
Although detergent compositions generally include
sodium sulphate it may sometimes be desirable to have
compositions which are sulphate free or contain low
levels of sulphate.
The detergent compositions according to the
invention may be prepared by a number of different
methods according to their physical form. In the case of
granular products they may be prepared by dry-mixing or
coagglomeration. A preferred physical form is a granule
incorporating a detergency builder salt and this is most
conveniently manufactured by spray-drying at least part
of the composition. In this process a slurry is prepared
containing the heat-insensitive components of the
composition such as the surfactant system, builder
material and filler. The slurry is spray-dried to form
base powder granules with which any solid heat-sensitive
ingredients may be mixed, such ingredients including
bleaches and enzymes. The specified nonionic surfactants
can be liquidified by melting or solvent dissolution and
sprayed onto the base powder granules, rather than
including them in the slurry for spray-drying. The
invention will now be described in more detail in the
following non-limiting examples.
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2034666
Examples 1 to 4
Wash liquors were prepared in water having a
hardness of 24FH (equivalent to a free calcium ion
concentration of 2.4 X 10 3 molar). The wash liquor
contained the equivalent of 6g/l of a composition
containing (by weight)
1 2 3 4
Coconut PAS (ELFAN 280) 6 - - -
SYNPROL SULPHATE -6 - -
DOBANOL 45 SULPHATE - - 6
LIAL 145 SULPHATE - - - 6
SYNPERONIC A7 2 2 2 2
SYNPERONIC A3 5 5 5 5
Zeolite 24 24 24 24
SOKALAN CP5 4 4 4 4
Soluble "C" silicate 0. 8 0.80.8 0.8
Sodium carbonate 10 10 10 10
Sodium sulphate 20 20 20 20
Sodium metaborate 11 11 11 11
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The sodium metaborate was included as being
equivalent in ionic strength to 8% sodium perborate
monohydrate which would be present in practice. The
bleach is left out of these experiments to avoid
confusion between detergency and bleaching effects in the
interpretation of the results. The anionic surfactants
used were as set out in the following table:
Example Anionic % % Chain
No. branching branchin~ Length
(4 or (atoms)
qreater)
1 ELFAN 280 none none (12/14/
16/18)
2 SYNPROL SULPHATE 46 2.3 (13/15)
3 DOBANOL 45 18 8.8 14/15
SULPHATE
4 LIAL 145 61 30 14/15
SULPHATE
ELFAN 280 is ex Akzo, SYNPROL SULPHATE is ex ICI, DOBANOL
45 SULPHATE is the sulphate of DOBANOL 45 alcohol ex
Shell, LIAL 145 SULPHATE is the sulphate of LIAL 145
alcohol ex Enichem.
In examples 1 to 4 the nonionic surfactant was
SYNPERONIC A7 (ex ICI) which is principally C13/C15
alcohol ethoxylated with an average of 7 moles of
ethylene oxide mixed with SYNPERONIC A3 (ex ICI) which is
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principally C13/15 alcohol ethoxylated with an average of
3 moles of ethylene oxide. This mixture has an HLB of
approximately 9.
- 5 The wash liquors were used to wash a fabric load at
liquor to cloth ratio of 50:1. The load included a
number of polyester monitors to which had previously been
applied an amount of H tagged triolein. Measurement of
the level of tagged triolein after washing, using
standard radio-tracer techniques, gives an indication of
the degree of detergency, i.e. soil removal, obtained.
The wash time was 20 minutes with an agitation of 70
rpm. Washes were isothermal at 40C.
The results obtained were as follows:
Example Anionic Branched ? ~ soil
No. removal
1 ELFAN 280 No 21.4
2 SYNPROL SULPHATE Yes 23.3
3 DOBANOL 45 SULPHATE Yes 27.6
4 LIAL 145 SULPHATE Yes ' 28.6
From these results it is apparent that the branched
chain PAS outperforms the linear chain PAS.
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Examples S to 7
Experiments were conducted in a similar manner to
Examples 1 to 4 excepting that the wash temperature was
30C and the water used was 25FH (equivalent to 2.5 x
10 3 mol/l of calcium).
Example
6 7
ELFAN 280 9
SYNPROL SULPHATE - 9
DOBANOL 45 SULPHATE - - 9
SYNPERONIC A7
SYNPERONIC A3 3 3 3
Zeolite 24 24 24
Sokalan CP5 4 4 4
Sodium Carbonate 12 12 12
Sodium sulphate 18 18 18
Soluble "C" silicate 3 3 3
Sodium Chloride 4.68 4.68 4.68
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In this case sodium chloride was included as being
equivalent in ionic strength to 8% sodium perborate
monohydrate.
In Examples 5 to 7 the nonionic surfactant mixture
had an HLB of approximately 9.
The results were as follows:
10 Example No. Anionic Branched ? ~ soil
removal
ELFAN 280 No 27.8
15 6 SYNPROL SULPHATE Yes 30.0
7 DOBANOL 45 Yes 34.9
SULPHATE
These results show that branched PAS outperforms the
linear PAS.
Examples 8 to 11
Experiments using the method and compositions as
used in Examples 6 and 7 were carried out at 30C and
60C on a different soiled polyester.
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Example Anionic Temp % Branchinq ~ Soil
No. C (4 and Removal
qreater)
8 SYNPROL SULPHATE 30 2.3 44
9 DOBANOL 45 30 8.8 48
SULPHATE
SYNPROL SULPHATE 60 2.3 39.5
11 DOBANOL 45 60 8.8 49.5
These results show that a higher level of C4 or
greater branching in the PAS gives rise to a higher
percentage of oily soil removal at both low and high
temperatures.
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Examples 12 to 13
Wash liquors were prepared in water having a hardness of
24FH to give a product concentration of 6g/l from a
composition containing (by weight)
12 13
SYNPROL SULPHATE (PAS) 13
ACROPOL SULPHATE (PAS)2 13
Zeolite 24 24
Sokalan CP5 4 4
Sodium carbonate 12 12
Sodium sulphate 10 10
Sodium metaborate 11 11
1 is C13/C15 sulphate with 46% branching of which 78%
is methyl and 5% is butyl or higher.
2 is a sulphate with 35% branching of which 50% is
methyl and 21% is butyl or higher.
The wash liquors were used to wash a fabric load as in
Example 1.
The results obtained were as follows.
Example No. Anionic % soil removal
______ ______________________________
12 SYNPROL SULPHATE 45.8
13 ACROPOL SULPHATE 49.1
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From these results it is apparent that branched PAS with
a high percentage of butyl branching outperforms PAS with
a low percentage of butyl branching.
Examples 14 to 15
Examples 12 and 13 were repeated with nonionic detergent
active in the formulation.
14 15
SYNPROL SULPHATE (PAS) 6
ACROPOL SULPHATE (PAS) - 6
SYNPERONIC A7 2 2
SYNPERONIC A3 6 6
ZEOLITE 24 24
SOKALAN CP5 4 4
SODIUM CARBONATE 12 12
SODIUM SULPHATE 10 10
SODIUM METABORATE 11 11
The results obtained were as follows.
Example No. Anionic % soil removal
_________________________________________________
14 SYNPROL SULPHATE 35.1
ACROPOL SULPHATE 38.0
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2034666
Examples 16-18
Example 12 was repeated using three different PASs in
place of SYNPROL SULPHATE. The results obtained were as
follows:
Example No. Anionic% soil removal
_ _ _ _ _
16 C16 straight chain PAS 4.1 + 0.8
17 C15-2-methyl PAS58.9 + 2.3
18 C12-2-butyl PAS60.2 + 2.5
These results show that branched PAS performs better than
straight chain PAS.
