Note: Descriptions are shown in the official language in which they were submitted.
1328065
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DETERGENT COMPOSITIONS
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TEC~NICAL FIELD .
The present invention relates to fabric washing :.
detergent compositions having improved antiredeposition
properties.
BACKGROUND AND PRIOR AR~
Redeposition of soil removed from washed articles
back onto the articles themselves is a well-known problem
which is of particular significance with textile fabrics,
and many solutions to this problem have been suggested.
Classically, sodium carboxymethyl cellulose was
incorporated into fabric washing compositions, and that
compound is still used today. More recently, copolymers
of ethylene or vinyl methyl ether and maleic anhydride,
copolymerc of acrylic acid and maleic anhydride, and
homopolymers of acrylic acid have been suggested in the
patent literature; see, for example, GB 1 269 848
(Procter & Gamble) and GB 1 460 893 (Unilever).
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Another polymeric material that has been suggested
for improving soil suspension is polyvinylpyrrolidone.
EP 262 897A (Unilever) discloses detergent compositions
containing polyvinylpyrrolidone, an anionic surfactant,
and a nonionic surfactant system having a
hydrophilic-lipophilic balance (HLB) of not more than
10.5.
EP 219 048A (BASF) discloses the use of graft
copolymers of polyalkylene oxide with vinyl acetate as
greying inhibitors in the washing and post-wash treatment
of synthetic textile fabrics.
We have now discovered that detergent compositions
containing a graft copolymer of this type in conjunction
with a low-~LB nonionic surfactant system exhibit
surprisingly enhanced 90il suspension (antiredeposition)
properties on polyester/cotton fabricæ.
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DEFINITION OF THE INVENTION
The present invention provides a detergent
~ composition comprising:
:
(a) from 2 to 50% by weight of a detergent active
system which amount includes a nonionic surfactant system :~.
consisting of one or more nonionic surfactants, the
nonionic surfactant system having a cloud point ~as
hereinafter defined) not higher than 40C; and
(b) from 0.1 to 3% by weight of a graft copolymer
of (i) polyethylene, polypropylene or polybutylene oxide
with (ii) vinyl acetate (optionally partially saponified)
in a weight ratio of (i) to (ii) of from 1:0.2 to 1:10.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to detergent
compositions containing two specified ingredients - a
nonionic surfactant system, and a graft copolymer
which may additionally contain any other conventional
detergent ingredients, for example, other surfactants,
builders, bleach systems, antifoam systems, fluorescers,
inorganic salts, and other materials well known to those
skilled in formulating detergents. The compositions of
the invention may take any suitable form, for example, .
powders, liquids or bars.
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The nonionic surfactant system
The nonionic surfactant system of the prese~t
- invention exists as a cloudy phase somewhere in the
temperature range of 0C to 40C, preferably 0C to 15C, -
in distilled water at a concentration of 1%. In
practice this means that the system has a cloud point of
not more than 40C, preferably not more than 15C.
Cloud point is a term well known in the art, for example,
from "Surface Active Ethylene Oxide Adducts" by
N Schonfeldt, Pergamon Press 1969, pages 145 to 154. In
general terms the cloud point of a surfactant material is
the temperature at which association between the
surfactant molecules and water molecules through hydrogen
bonding breaks down, leading to the separation of
surfactant-rich and water-rich phases and a consequent
increase in turbidity or cloudiness.
The cloud point correlates approximately to the
hydrophilic-lipophilic balance ~HLB) of the surfactant
system and it is therefore preferred that the HLB should
be not higher than 10.5 and more preferably not higher
than 9.5. The HLB should however preferably be above
6.0, more preferably above 8.0, in order to provide
25 sufficient detergency. ~ -
Suitable nonionic detergent compounds which may be
used include in particular the reaction products of
compounds having a hydrophobic group and a reactive
30 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 22)
phenol-ethylene oxide condensates, the condensation
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products of linear or branched aliphatic C8 20 primary or
secondary alcohols with ethylene oxide, and products made
by condensation of ethvlene oxide with the reaction
products of propylene oxide and ethylenediamine. Other
so-called nonionic detergent compounds include long-chain
tertiary amine oxides, tertiary phosphine oxides, and
dialkyl sulphoxides.
Where, for example, alkylene oxide adducts of
fatty materials (aliphatic alcohols, acids or amides) are
used as the nonionic detergent compounds, the number of
alkylene oxide groups per molecule has a considerable
effect upon the cloud point as indicated by the
Schonfeldt reference mentioned above. The chain length
and nature of the fatty material is also influential, and
thus the preferred number of alkylene oxide groups per
molecule depends on the the nature and chain length of
the fatty material. We have found, for example, that
where the fatty material i8 an alcohol having about 12 to
15 carbon atoms, the adducts having 3 and 4 ethylene
oxide groups per molecule (hereinafter the 3EO and 4EO
materials) both have cloud points of less than 0C and
are therefore suitable for use in the present invention.
The corresponding 5EO and 6EO surfactants have cloud
points of about lZC and about 30C respectively; both
are therefore suitable for use in the present invention,
but the 5EO is preferred to the 6EO.
The corresponding 7EO surfactant has a cloud point
of about 48C and is therefore unsuitable for use in the
present invention, unless in admixture with another
surfactant of lower cloud point: for example, a mixture
of 1 part by weight of the 7EO material with 3 parts by
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weight of the 3EO matPrial has a sufficiently low cloud
point to be useful in the present invention. Further -
ethoxylation raises the cloud point still higher: thus
the corresponding llEO material has a cloud point higher
than 80C and is unsuitable for use in the present
invention.
Thus preferred nonionic surfactants for use in the
compositions of the invention are C12_15 aliphatic
alcohols having a degree of ethoxylation not exceeding 6,
preferably 3 to 5.
The nonionic surfactant system of the compositions
of the invention may consist of a single nonionic
surfactant of appropriate cloud point, although it must
be remembered that even a single commercial nonionic
surfactant is a mixture of materials of different chain ;~
lengths and degrees of ethoxylation: the chain lengths
and degrees of ethoxylation quoted in this specification
are average values. Alternatively, a nonionic
surfactant system of suitable cloud point and HLB value
may be obtained by blending two or more nonionic
surfactants, as exemplified by the 7EO/3EO mixture
mentioned in the previous paragraph.
The nonionic surfactant system is preferably present
in an amount of from 2 to 20% by weight, more preferably
from 3 to io% by weight, based on the total composition.
Ae indicated below under "Optional Ingredients", other
surfactants, of other ~onic types, may also be present if
desired, the total amount of surfactant of all ionic
type~ present being within the range of from 2 to 50% by
weight, preferably from 5 to 40~ by weight, of the final
compositlon.
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The ~Iraft copolymer
.
The graft copolymers used in the compositions of the
present invention are described and claimed in
EP 219 048A (BASF). They are obtainable by gra~ting a
polyalkylene oxide of molecular weight (number average)
2000 - 100 000 with vinyl acetate, which may be
partially saponified, in a weight ratio of polyalkylene
oxide to vinyl acetate of 1:0.2 to 1:10. The vinyl
acetate may, for example, be saponified to an extent of
up to 15%. The polyalkylene oxide may contain units of
ethylene oxide, propylene oxide and/or butylene oxide;
polyethylene oxide is preferred.
Preferably the polyalkylene oxide has a
number-average molecular weight of from 4000 to 50 000,
and the weight ratio of polyalkylene oxide to vinyl
acetate is from 1:0.5 to 1:6. Especially preferred are :~.
polymers derived from polyethylene oxide of molecular
weight 2000-50 000 and having a weight ratio of
polyethylene oxide to vinyl acetate of from 1:0.5 to 1:6. ~ .
A material within this definition, based on
polyethylene oxide of molecular weight 6000 (equivalent
to 136 ethylene oxide units), containing approximately
3 parts by weight of vinyl acetate units per 1 part by
weight of polyethylene oxide, and having itself a
molecular weight of 24 000, is commercially available .
from BASF as Sokalan (Trade Mark) HP22. ..
.
The polymers are present in the composition~ of the
invention in amounts of from 0.1 to 3% by weight,
~ preferably from 0.3 to 1% by weight.
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Optional ingredients
As well as the specified nonionic surfactant system
and graft copolymer, the compositions of the invention
may contain any other non-interfering ingredients known
to be suitable for incorporation into detergent
compositions.
The compositions may usefully contain one or more
soap or non-soap anionic, cationic, amphoteric or
zwitterionic surfactant~, or combinations of these.
Many suitable detergent-active compounds are available
and are fully described in the literature, for example,
in "Surface-Active Agents and Detergents", Volumes I and
II, by Schwartz, Perry and Berch.
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The preferred detergent-active compounds that can be
used, in addition to the specified nonionic surfactant
system, are soaps and synthetic non-soap anionic
surfactants.
Synthetic anionic surfactants are well known to
those skilled in the art. Examples include alkylbenzene
sulphonates, particularly sodium linear alkylbenzene
sulphonates having an alkyl chain length of C8-C15:
primary and secondary alkyl sulphates, particularly -
sodium C12-C15 primary alcohol sulphates; olefin
sulphonates; alkane sulphonates; dialkyl ~ -
sulphosuccinates; and fatty acid ester sulphonates.
It may also be desirable to include one or more
soaps of fatty acids. These are preferably sodium soaps
derived from naturally occurring fatty acids, for
example, the fatty acids from coconut oil, beef tallow,
sunflower or hardened rape seed oil.
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A preferred type of detergent composition suitable
- for use in most automatic fabric washing machines
contains anionic and nonionic surfactant together in a
- weight ratio of at least 0.67:1, preferably at least 1:1,
and more preferably within the range of from 1:1 to 10:1.
Soap may also be present if desired.
As previously indicated, the total amount of
surfactant in the compositions of the invention is from 2
to 50% by weight, and is preferably from 5 to 40% by
weight.
Compositions of the invention will also generally
contain one or more detergency builders. These are as
well known to the skilled formulator as are the
surfactants listed above. Inorganic builders that may
be present include alkali metal (generally sodium)
ortho-, pyro- and tripolyphosphate, carbonate, and
crystalline and amorphous aluminosilicates; while
organic builders include polycarboxylate polymers such as
polyacrylates, acrylic/maleic copolymers, and pclyacetal
carboxylates, and monomeric polycarboxylates such as
nitrilotriacetates, citrates and
carboxymethyloxysuccinates. This list is not intended
to be exhaustive. The total level of detergency builder
is generally within the range of from 20 to 80~ by
weight.
According to a preferred embodiment of the
invention, the compositions contain less than 10~ by
weight of inorganic phosphate builders, and are more
preferably substantially free of inorganic phosphate.
1~28~65
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:
In this preferred embodiment, the builder system
preferably comprises crystalline or amorphous alkali
metal aluminosilicate, optionally in conjunction with a
supplementary builder. The aluminosilicate is suitably
present in an amount of from 10 to 60% by weight.
Detergent compositions according to the invention
may also suitably contain a bleach system. Preferred
are peroxy bleach compounds, for example, inorganic
persalts or organic peroxyacids, which may be employed in
conjunction with activators to improve bleaching action
at low wash temperatures. The skilled detergent worker
will have no difficulty in applying the normal principles
to choose a suitable bleach system.
Other materials that may be present in detergent ;
compositions of the invention include sodium silicate,
fluorescers, inorganic salts such as sodium sulphate,
enzymes, lather control agents or lather boostexs as
appropriate, pigments, and perfumes. Again, this list
is not intended to be exhaustive.
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PreParation of detergent comPositions
Detergent compositions of the invention may be
prepared by any suitable method. Detergent powders are -
suitably prepared by spray-drying a slurry of ccmpatible
heat-insensitive components, and then spraying on or ^ `
postdosing those ingredients unsuitable for processing
via the ~lurry. The skilled detergent formulator will -~
generally have no difficulty in deciding which components
should be included in the slurry and which should be
postdosed or sprayed on.
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The graft copolymer is available as a solution
having a solids content of 20% which is stable at slurry
processing temperatures and can be incorporated in the
slurry without problems, provided that the pH is
maintained below 12.
The nonionic surfactant system is preferably not
incorporated via the slurry. If, however, a mixed
system is used which includes a relatively highly
ethoxylated component, that component may if desired be
processed via the slurry while material of lower
ethoxylation is sprayed on or postdosed on a solid
carrier.
The invention is further illustrated by the :::
following non-limiting Examples, in which parts and
percentages are by weight unless otherwise stated.
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EXAMPLES
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Example 1
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Four detergent compositions were prepared to the
following formulation by conventional slurry-making,
spray-drying and postdosing techniques~ ;
% ~;.
Sodium linear alkylbenzene sulphonate 9.0
Nonionic surfactant (see below) 4.0 ~.
Zeolite 4A (hydrated basis) 24.0 ~
15 Sodium alkaline silicate 5.0 .
Sodium sulphate 19.3
Sodium carbonate 7.0 -:
Sodium carboxymethylcellulose 0.5 :.
Fluorescer 0.7 :.
20 Sodium perborate monohydrate 8.0 .
Tetraacetylethylenediamine (76% granules) 3.0
Enzyme granules 0.5
Graft copolymer (Sokalan HP22) 0 or 0.5
Water and minor ingredients to 100.0 '
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The compositions prepared contained the following
amounte of nonionic surfactants and Sokalan SP22:
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1328065 ~-
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Example 1 A B C
- Nonionic surfactant 7E01 1.0 4.0 4.0 1.0
5 Nonionic surfactant 3E0 3~0 - - 3.0
Sokalan HP22 0.5 - 0.5
1 Synperonic (Trade Mark) A7 ex ICI, C12 1
linear primary alcohol 7E0
2 Synperonic (Trade Mark) A3 ex ICI, C12 15
linear primary alcohol 3E0
15 It will be seen that Composition 1 illustrates the
invention while Compositions A to C are comparative.
,
The soil suspension (antiredeposition) propertie~ of
the four compositions were compared by means of the
following procedure. Two new, clean, unwashed
polyester/cotton test cloths were washed together with
five soiled cloths ~n a tergotometer at 60C in 50
(French) hard water (Ca:Mg ratio 4:1) at a liquor to
cloth ratio of about 50:1, the wash liquor containing 4
gtl of the detergent composition under test. The soiled
cloths carried a range of different ~oils such as clay,
oil, fat, proteinaceous, and ink. The wash cycle was
repeated a further nine times, the soiled cloths being
replaced by new soiled cloths (with the same range of
soils) for each wash cycle.
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The reflectance of the two new cloths was measured :
before washing, and after the tenth wash cycle. The
reduction in reflectance of the washed fabrics after ten -
washes is shown in the following table; the lower the
reduction in reflectance, the less redeposition had
occurred.
10 ExamPle 1 A B C : ~
Delta R460* -2.4 -5.6 -7-5 ~4 7 ; :
