Note: Descriptions are shown in the official language in which they were submitted.
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DETERGENT COMPOSITIONS
TECHNICAL FIELD
The present invention relates to detergent
compositions, especially particulate detergent compositions,
suitable for the laundering of fabrics in domestic or
commercial washing machines, containing a detergency builder
system which is a combination of a specific aluminosilicate
and a citrate builder salt.
BACKGROUND AND PRIOR ART
Detergent compositions for heavy-duty fabric washing
conventionally contain materials - detergency builders
- to lower the concentration of calcium water hardness
ions in the wash liquor and thus to give good detergency
in hard water as well as in soft water.
Alkali metal aluminosilicate ion-exchangers,
especially the crystalline sodium aluminosilicate zeolite
4A, are now well-known replacements for the inorganic
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phosphates traditionally used as detergency builders in
fabric washing detergents. It is also well known that
zeolites show certain deficiencies in detergency
building, as compared with phosphates, and that
supplementary building power is generally desirable. In
many zero-phosphate premium detergent powders now on the
European market, homo- or copolymers of acrylic acid are
included for this purpose.
It is also known to include citric acid and/or its
salts in detergent compositions, but these compounds are
well-known to be poor sequestrants of calcium ions and to
contribute little to detergency building.
Detergent compositions built with crystalline
aluminosilicate (zeolite) and also containing citrates
are specifically disclosed in GB 1 473 201 (Henkel),
GB 1 429 143 (Procter & Gamble), GB 1 470 250 (Procter &
Gamble), EP 1310A (Procter & Gamble), EP 1853A (Procter &
Gamble), EP 75 796B (Procter & Gamble), GB 2 095 274B
(Colgate-Palmolive), DE 2 336 182C (Lion), EP 234 867A
(Clorox),
Water-softening or detergency building granules
based on zeolites and citrates are disclosed in
EP 243 908A (Henkel), DE 3 144 297A (Degussa), and
EP 22 023A (Union Carbide).
EP 313 143A (Unilever) discloses bleaching detergent
compositions containing aluminosilicate (15-40 wt%), citric
acid or alkali metal citrate (1-15 wt%), and a solid organic
peroxyacid (1-15 wt%). EP 313 144A (Unilever) describes
and claims bleaching detergent compositions containing
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aluminosilicate (15-40 wt%), citric acid or alkali metal
citrate (1-15 wt%), an inorganic peroxy compound
(5-35 wt%), and a peroxybenzoic acid bleach precursor
(1-10 wt%). Both specifications claim improved cleaning
and bleaching performance when a builder system based on
zeolite and citrate is used in conjunction with these
specific bleach systems.
//
EP 384 070A (Unilever) describes and claims a novel
zeolite P (maximum aluminium zeolite P, or zeolite MAP)
having an especially low silicon to aluminium ratio, not
greater than 1.33 and preferably not greater than 1.15.
This material is demonstrated to be a more efficient
detergency builder than conventional zeolite 4A.
The present invention is based on the discovery that
the novel combination of zeolite MAP and citrate provides
an especially effective detergency builder system.
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DEFINITION OF THE INVENTION
In its first aspect, the present invention provides a
detergent composition for fabric washing, comprising:
(i) one or more detergent-active compounds selected from
anionic, nonionic, cationic, amphoteric and zwitterionic
detergent-active compounds and combinations thereof,
(ii) a detergency builder system comprising:
(a) zeolite P having a silicon to aluminium ratio
not exceeding 1.33 (hereinafter zeolite MAP), and
(b) citric acid and/or a salt thereof;
the ratio of zeolite MAP (a) (anhydrous basis) to citrate
(b) (calculated as trisodium citrate dihydrate equivalent)
preferably being within the range of from 1:1 to 6:1, more
preferably from 1.5:1 to 3:1.
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In its second aspect, the present invention provides a
detergency builder composition comprising:
(a) zeolite MAP (as defined above), and
(b) citric acid and/or a salt thereof,
but excluding a composition comprising at least 50 wt%
(anhydrous basis) of zeolite MAP, from 15 to 20 wt% of
sodium carbonate, and from 2 to 12 wt% (calculated as
trisodium citrate dihydrate) of a water-soluble salt of
citric acid;
the ratio of zeolite MAP (a) (anhydrous basis) to citrate
(b) (calculated as trisodium citrate dihydrate equivalent)
preferably being within the range of from 1:1 to 6:1, more
preferably from 1.5:1 to 3:1.
In its third aspect, the invention provides a method of
washing fabrics, which includes the step of bringing the
fabrics into contact with an aqueous wash liquor containing
a detergent composition as defined above and/or a detergency
builder composition as defined above.
In its fourth aspect, the invention provides the use of
citric acid and/or a salt thereof as a detergency builder in
a detergency builder composition or a detergent composition
for fabric washing containing zeolite MAP.
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DETAILED DESCRIPTION OF THE INVENTION
The detergent composition
The detergent composition of the invention contains, as
essential components, a detergent-active compound, and a
detergency builder system.
The deterqent-active compound
The detergent compositions of the invention will
contain, as essential ingredients, one or more
detergent-active compounds (surfactants) which may be chosen
from soap and non-soap anionic, cationic, nonionic,
amphoteric and zwitterionic detergent-active compounds, and
mixtures thereof. 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.
The preferred detergent-active compounds that can be
used are soaps and synthetic non-soap anionic and nonionic
compounds.
Anionic surfactants are well-known to those skilled in
the art. Examples include alkylbenzene sulphonates,
particularly linear alkylbenzene sulphonates having an alkyl
chain length of C8-Cl5; primary and secondary alkyl
sulphates, particularly C12-Cl5 primary alkyl sulphates;
alkyl ether sulphates; olefin sulphonates; alkyl xylene
sulphonates; dialkyl sulphosuccinates; and fatty acid
ester sulphonates. Sodium salts are generally preferred.
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Nonionic surfactants that may be used include the
primary and secondary alcohol ethoxylates, especially the
aliphatic C12-C15 primary and secondary alcohols ethoxylated
with an average of from 3 to 20 moles of ethylene oxide per
mole of alcohol; and alkylpolyglycosides.
Preferred detergent-active systems, suitable for
compositions intended for use in automatic fabric washing
machines, comprises anionic non-soap surfactant, or
nonionic surfactant, or combinations of the two in any
ratio, optionally together with soap.
The total amount of detergent-active compounds present
may suitably lie in the range of from 5 to 40 wt%.
The detergency builder system
The detergency builder system of the invention contains
two essential components: zeolite MAP and a citrate.
Zeolite MAP and its use in detergent compositions are
described and claimed in EP 384 070A (Unilever). It is
defined as an alkali metal aluminosilicate of the zeolite P
type having a silicon to aluminium ratio not greater than
1.33, preferably within the range of from 0.9 to 1.33, and
more preferably within the range of from 0.9 to 1.2.
Of especial interest is zeolite MAP having a silicon to
aluminium ratio not greater than 1.15 and having a
tetragonally distorted cubic crystal structure.
Especially preferred is zeolite MAP having a silicon to
aluminium ratio not greater than 1.07.
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Zeolite MAP generally has a calcium binding capacity of
at least 150 mg CaO per g of anhydrous aluminosilicate.
Although zeolite MAP like other zeolites contains water
of hydration, for the purposes of the present invention
amounts and percentages of zeolite are expressed in terms of
the anhydrous material.
The second essential component of the detergency
builder system of the invention is citric acid or a salt
thereof, preferably sodium citrate. This salt normally
exists in the form of the dihydrate, and for the purposes of
the present invention amounts and percentages of citrates
are expressed in terms of sodium citrate dihydrate.
It should be understood, however, that the use of other
wholly and partially neutralised citric acid salts, and the
free acid itself, in equivalent amounts, is also within the
scope of the invention.
The weight ratio of aluminosilicate to citrate is
preferably within the range of from 1:1 to 6:1, more
preferably from 1.5:1 to 3:1.
Preferred builder systems
Detergent compositions of the invention preferably
comprise from 10 to 45 wt%, more preferably from 12 to
30 wt%, of zeolite MAP; and from 2 to 20 wt%, more
preferably from 3 to 9 wt% and most preferably from 5 to
8 wt%, of the citrate.
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Other builder components
The compositions of the invention may be formulated
without homo- or copolymers of acrylic acid, for example,
polyacrylates or acrylic/maleic copolymers. Preferred
compositions are substantially free from such polymers,
although compositions containing them are not excluded from
the scope of the invention.
The amount of soluble silicates in the compositions
of the invention is preferably kept to a relatively low
level: preferably below 5 wt%, and more preferably below
1 wt~.
The compositions of the invention may advantageously
contain alkali metal carbonate, to provide alkalinity
rather than for detergency building. The amount of
alkali metal, preferably sodium, carbonate may suitably
range from 2 to 20 wt%, preferably from 5 to 15 wt%.
Bleach system
Detergent compositions according to the invention
may also suitably contain a bleach system. This preferably
comprises one or more peroxy bleach compounds, for example,
inorganic persalts or organic peroxyacids, which may be
employed in conjunction with bleach precursors to improve
bleaching action at low temperatures.
The bleach system preferably comprises a peroxy bleach
compound, preferably an inorganic persalt, optionally in
conjunction with a precursor.
Preferred inorganic persalts are sodium perborate
monohydrate and tetrahydrate, and sodium percarbonate.
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Preferred bleach precursors are peracetic acid
precursors, especially tetraacetylethylene diamine (TAED);
peroxybenzoic acid precursors; and the novel quaternary
ammonium and phosphonium bleach activators disclosed in
US 4 7S1 015 and US 4 818 426 (Lever Brothers Company), more
especially cholyl p-sulphophenyl carbonate (CSPC).
If desired, the bleach system may also include a bleach
stabiliser (heavy metal sequestrant).
Dicarboxylic acid structurant
The invention is especially, but not exclusively,
concerned with detergent compositions in particulate form.
Particulate compositions of the invention may
advantageously contain a dicarboxylic acid powder
structurant.
Suitable materials include succinic acid, adipic acid,
glutaric acid and mixtures thereof. The acids may be
employed in free acid or in salt (wholly or partially
neutralised) form. The dicarboxylic acid is suitably
employed in an amount within the range of from 0.5 to 5 wt%.
A commercial mixture of adipic acid (maximum 33 wt%),
glutaric acid (maximum 50 wt%) and succinic acid (maximum 31
wt%) is available from BASF, Ludwigshafen, Germany under the
trade mark Sokalan DCS, and a similar mixture of sodium
salts under the trade mark Sokalan DCN.
Particulate detergent compositions containing
succinates as powder structurants are described and
claimed in EP 61 295B (Unilever).
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Other ingredients
Other materials that may be present in detergent
compositions of the invention include fluorescers,
antiredeposition agents, inorganic salts such as sodium
sulphate, enzymes, lather control agents, fabric
softening agents, pigments, coloured speckles, and
perfumes. This list is not intended to be exhaustive.
Preparation of the deterqent compositions
Detergent compositions of the invention may be prepared
by any suitable method. The particulate detergent
compositions which are the preferred embodiment of the
invention are suitably prepared by spray-drying a slurry
of compatible heat-insensitive ingredients, and then
spraying on or postdosing those ingredients unsuitable
for processing via the slurry.
The skilled detergent formulator will have no
difficulty in deciding which ingredients should be included
in the slurry and which should not.
Both the zeolite MAP and the citrate builder component
are suitable for inclusion in the slurry, although it may be
advantageous for processing reasons for part of the
zeolite MAP to be incorporated post-tower.
The particulate detergent compositions of the
invention may be prepared to any suitable bulk density.
Compositions having bulk densities of at least 400 g/l, more
preferably at least 500 g/l, are of especial interest.
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The deterqency builder composition
The detergency builder system of the invention may be
exist as a composition in its own right that may be used for
water softening or added to the wash li~uor to enhance the
performance of an unbuilt or underbuilt detergent
composition in hard water.
10 ~
A typical composition of this type might contain from
50 to 80 wt% zeolite MAP (anhydrous basis), and from 5 to
30 wt% sodium citrate.
A composition of this type may in principle contain no
components other than the two essential components (zeolite
MAP and citrate), although in practice it may be desirable
to include other ingredients, for example, sodium carbonate,
and binders such as nonionic surfactants or cellulose
derivatives. However, as mentioned above, builder
additives of the specific composition claimed in EP 419 036A
are disclaimed and do not form part of the present
invention.
A builder composition of the type under discussion may
also be used as a raw material or premix in the manufacture
of more fully formulated detergent compositions. However,
the invention also includes within its scope detergent
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compositions prepared by admixing the two builder materials
(zeolite MAP and citrate) separately and independently with
other detergent ingredients.
The invention is further illustrated by the following
non-l imiting Examples, in which parts and percentages are by
weight unless otherwise stated.
EXAMPLES
Examples 1 and 2, Comparative Example A
Detergent powders containing zeolite MAP and citrate
were prepared to the following formulations (in parts by
weight):
Linear alkylbenzene sulphonate7.00 7.00
Nonionic surfactant (7EO) 3.00 3.00
Nonionic surfactant (3EO) 6.00 6.00
Soap 1.50 1.50
Zeolite MAP (anhydrous basis) (a) 26.00 24.00
Sodium citrate (2 aq basis) (b)5.40 5.40
Antifoam granules 2.00 2.00
Sodium carbonate 12.00 12.00
TAED granules 7.00 7.00
Sodium perborate monohydrate 15.00 15.00
*Dequest 2047 ~ ~ 75
Enzyme (Savinase 6.OT) 0.50 0.50
Fluorescer 0.20 0.20
Sodium carboxymethyl cellulose0.50 0.50
*denotes trade mark
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Ratio (a):(b) 4.80 4.40
Total (a)+(b) (parts) 31.40 29.40
Comparative Example A was identical to Example 1 except
that the zeolite MAP was replaced by 26.00 parts of zeolite
4A.
The zeolite MAP was prepared on a pilot scale by the
method described in Examples 1 to 3 of EP 384 070A
(Unilever). Its silicon to aluminium ratio was 1.10 and it
had a tetragonally distorted cubic crystal structure.
Detergency was measured in a tergotometer in 26~
(French) hard water (Ca:Mg ratio 4:1) at 60~C and a product
dosage of 4 g/l. Test cloths as described below were washed
together with a white ballast load. The results, expressed
as reflectance differences at 460 nm (~R460), were as
follows:
Test cloths
(1) oil/silica/ink soil on cotton;
(2) Indian ink/olive oil soil on polyester/cotton;
(3) Indian ink/olive oil soil on cotton.
Test cloth 1 2 A
(1) 24.6 25.6 23.6
(2) 16.6 14.5 14.1
(3) 25.7 25.6 22.5
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These results show the superior building capacity of
zeolite MAP/citrate as compared with zeolite 4A/citrate.
Examples 3 and 4, Comparative Examples B and C
Formulations containing lower percentages of zeolite
MAP and citrate were prepared as follows:
Linear alkylbenzene sulphonate 6.00
Nonionic surfactant (7EO) 2.75
Nonionic surfactant (3EO) 4.25
Soap 1.75
Zeolite MAP (anhydrous basis) (a) 12.00
Sodium citrate (2 aq basis) (b) see below
Antifoam granules 1.20
20 Sodium carbonate 14.00
Sodium silicate 0.55
TAED granules 3.00
Sodium perborate tetrahydrate20.00
Dequest 2047 0.75
25 Enzyme (Savinase 6.OT) 0.40
Fluorescer 0.21
Sodium carboxymethyl cellulose 0.83
Moisture and salts 10.00
The zeolite MAP used was the same as that used in
Examples 1 and 2.
The builder systems of the various formulations were as
shown below: Sokalan (Trade Mark) CP5 ex BASF AG,
Ludwigshafen, Germany is an acrylic/maleic copolymer.
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Exam~le 3 4 B C
Zeolite MAP (a) 12.0 12.0 12.0 12.0
5 Citrate (b) 6.0 8.0
Sokalan CPS - - - 2.0
Ratio (a):(b) 2.0 1.5
Total (a) + (b) 18.0 20.0
Detergency was measured in a tergotometer in 15~
(French) hard water (Ca:Mg ratio 4:1) at 40~C and a product
dosage of 4 g/l. Test cloths as described below were washed
together with a white ballast load. The results, expressed
as reflectance differences at 460 nm (~R460) as compared
with Comparative Example C, were as follows:
Test cloths: (1), (2): as in Examples 1 and 2;
(4) proteinaceous (casein) soil on cotton.
Test cloth 3 4 B
(1) 0.2 0.6 -1.1
(2) 2.9 3.5 1.6
(4) 0.8 0.9 0.1
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