Note: Descriptions are shown in the official language in which they were submitted.
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Method of cleaning laundry
Field of the invention
The present invention relates to the use of hydroxamic acid and
its corresponding salts in laundry detergent compositions with
low levels of zeolite and phosphate builder, leading to
improved detergency and stain removal.
Background of the invention
Improvement of stain removal is one of the constant goals of
the detergent industry, as this may lead to savings on the use
of chemicals in detergent compositions, or may lead to washing
at lower temperatures, and/or for shorter times, and therewith
saving energy. Therefore, there is still an interest to improve
the detergency effect, especially the primary detergency effect
of laundry detergent compositions on textile stains, for
example particulate stains, such as stains comprising soils or
clay, or plant based stains, such as grass. Especially
particulate stains are difficult to remove during the
laundering process.
Hydroxamic acids are a class of chemical compounds in which a
hydroxylamine is inserted into a carboxylic acid. The general
structure of a hydroxamic acid is the following:
0
/cx / OH
Formula 1
in which R1 is an organic residue, for example alkyl or
alkylene groups. The hydroxamic acid may be present as its
corresponding alkali metal salt, or hydroxamate.
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The hydroxamates may conveniently be formed from the
corresponding hydroxamic acid by substitution of the acid
hydrogen atom by a cation:
0 0
II LOH c II e e
,OH 0 L
Ri/C\N
-VI' RiN'
I I
H H
(Formula 2)
LE is a monovalent cation such as for example the alkali metals
(e.g. potassium, sodium), or ammonium or a substituted
ammonium.
Hydroxamic acids and hydroxamates are known to be useful as
metal chelators. They have also been used in detergent
compositions in order to improve bleaching performance, as well
as use as a builder substance.
EP 388 389 A2 discloses bleach free under built liquid
detergent compositions containing hydroxamic acids and their
derivatives which assist in the removal of bleachable wine
stains from fabrics during laundering. Hydroxamic acids as in
formula 1 are disclosed, wherein R1 represents an optionally
substituted straight- or branched chain C5-C21 alkyl or C5-C21
alkenyl group or an optionally-substituted phenyl group, and R2
represents hydrogen, or an optionally substituted Ci-C6 alkyl
group, or an optionally-substituted phenyl group. One of the
examples shows an improved bleaching performance when a
hydroxamate is used in a detergent composition in hard water
(20 German hardness, which is about 143 milligram calcium per
litre). The examples use C12 linear, C12 branched, C13 branched
and C18 hydroxamates in detergent formulations comprising
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mixtures of anionic surfactant and nonionic surfactant. In
examples I, II and IV there is an excess of nonionic surfactant
of at least 1.25 to 1 and in example III there is 100% anionic
surfactant. The liquids also contain at least 6 wt% ethanol,
which assists in solubilising the long chain hydroxamates
EP 384 912 A2 discloses the use of hydroxamic acids and their
derivatives as stabilizers for peroxygen bleach compounds in
built, mainly granular, detergent compositions. Fully
formulated detergent powder examples with 20 wt% zeolite used
C12, C13 and C12 branched hydroxamates. C18 was also used.
US 4,874,539 discloses polymeric carboxy hydroxamic acids
useful as detergent additives, especially as metal ion
chelating agents, and also leading to improved tea stain
removal from a test cloth, as compared to a detergent powder
without a metal ion chelating agent.
US 4,863,636 discloses liquid detergent compositions comprising
one or more detersive surfactants and one or more of N-
hydroxyimide or carboxy hydroxamic acid detergent additives.
These compounds serve as active metal ion chelants, leading to
improved stain removal.
WO 97/48786 discloses a multicomponent system for use with
detergent substances, containing an oxidation catalyst, a
suitable oxidant, at least one mediator that has been selected
from the group of, among others, hydroxamic acids and
hydroxamic acid derivatives, a co-mediator, and optionally a
low quantity of at least one free amine of each inserted
mediator. This system leads to improved bleach function of the
detergent, and less consumption of a mediator.
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GB 1317445 discloses detergent compositions comprising an
alkali-metal salt of a hydroxamic acid. The function of this
salt is to prevent the corrosion of copper and copper alloys
that is utilised in the construction of the washing machines.
Copending patent application PCT/EP2009/067193 describes
laundry detergent formulations comprising 0.5 to 20% by weight
hydroxamic acid or its corresponding hydroxamate having a
structure as specified therein. It is also shown in this
document that the primary detergent effect, especially on red
clay particulate soil, can be improved when applying these
laundry detergent formulations for treating soiled fabric.
It is known that this beneficial detergent effect cannot be
obtained when using the hydroxamic acid or its corresponding
hydroxamate in a fully built detergent in particular when the
builder mainly contains zeolite and/or phosphate and/or
carbonate builder.
In this connection, it is an object of the present invention to
provide an effective method for cleaning fabric wherein both a
fully built detergent formulation and hydroxamic acid or its
corresponding hydroxamate are used.
It has now surprisingly been found that this object could be
achieved by a method of cleaning fabric comprising a
pretreating step followed by a main wash step whereby the
hydroxamic acid is used in the pre-treatment step and the fully
built detergent formulation, preferably a fully built detergent
powder, is applied in the main wash step.
Definition of the invention
Accordingly, in a first aspect the present invention provides a
method of cleaning laundry, wherein said method comprises the
steps of:
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(I) pre-treating the laundry with a liquid pre-treatment
composition; and
(II) washing the thus-pre-treated laundry in a wash liquor
comprising a main wash detergent formulation, preferably a main
5 wash detergent powder,
wherein the liquid pre-treatment composition comprises:
(a) 0.005 to 20 wt% hydroxamic acid or its corresponding
hydroxamate of the structure
o
II
/cx / OH
R1 N
I
R2
wherein R1 is a straight or branched C4-C20 alkyl, or a
straight or branched substituted C4-C20 alkyl, ora straight or
branched C4-C20 alkenyl, or a straight or branched substituted
C4-C20 alkenyl, or an alkyl ether group CH3 (CH2)n (E0)m wherein
n is from 2 to 20 and m is from 1 to 12, or a substituted alkyl
ether group CH3 (0H2)n (E0)m wherein n is from 2 to 20 and m is
from 1 to 12, and
the types of substitution include one or more of -NH2, -OH,
-S-, -0-, -COOH, and
and R2 is selected from hydrogen and a moiety that forms part
of a cyclic structure with a branched R1 group,
b) 3 to 80 wt% of detersive surfactant system comprising
anionic nonionic, cationic zwitterionic surfactant or a
combination thereof, wherein the weight ratio a) to b) lies in
the range 6: 1 to 1:16000, preferably 1:10 to 1:400, and
c) optionally, other ingredients to 100 wt% provided that
zeolite, phosphate and carbonate builders are present at less
than 5 wt% and ethanol is present at a level of less than 5
wt%.
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It should be understood that references to a number of carbon
atoms include mixed chain length materials provided that some
of the hydroxamate material falls within the ranges specified
and the ratios and amounts are determined by excluding any
material falling outside of the specified range.
Soap is not included in the calculation of anionic surfactant
amounts and ratios.
However, the pre-treatment composition may comprise from 1 to
15 wt% soap. The preferred soaps are made from saturated fatty
acids.
It is undesirable to have ethanol present at all as it is an
explosion hazard during manufacture, and subsequently. If a
high level of surfactant is present, it is desirable to seek
alternative hydrotrope systems. We prefer a hydrotrope system
comprising propylene glycol and glycerol at levels of at least
6 wt%, more preferably at least 10 wt%.
The preferred hydroxamates are those where R2 is Hydrogen and R1
is C8 to C14 alkyl, preferably normal alkyl, most preferably
saturated.
Especially preferred pre-treatment compositions comprise at
least 0.5 wt% of soil release polymer. This improves the multi
wash performance of the detergent system for the removal of the
clay. Inclusion of at least 0.5 wt% anti redeposition polymer
is also beneficial due to the very high efficiency of primary
detergency soil removal meaning that there is an increased
level of soil in the wash liquor (particularly in step I of the
method), which must then be prevented from redeposition onto
the same or a different piece of fabric.
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In the pre-treatment composition, the preferred weight ratio of
hydroxamate to detersive surfactant system for optimum
particulate red clay soil removal lies in the range 1:10 to
1:100.
Preferably the pre-treatment composition used in the method of
the invention comprises a surfactant system including nonionic
and anionic surfactant whereby the level of anionic surfactant
is 50 to 95 wt% based on the total weight of the surfactant
system.
Said surfactant system can also suitably contain two different
types of anionic surfactant of which the weight ratio lies in
the range of 80:20 to 20:80. In such surfactant system, a first
type of anionic surfactant is preferably alkyl benzene
sulphonate and the second type of anionic surfactant is
preferably selected from the group consisting of alkyl ether
sulphate, alkyl sulphate and alkyl carboxylate. More
preferably, the second type of anionic surfactant is an alkyl
ether sulphate.
The pre-treatment compositions used in the method of the
invention are particularly suitable for use on particulate
stains such as soils and clays, especially red clay, and also
surprisingly grass. Therefore, in a second aspect, the present
invention provides the use of a pre-treatment composition
applied in the invention for the removal of particulate soils,
preferably red clay, most preferably Georgia clay, from
polyester and cotton fabrics.
Furthermore, in a third aspect, the present invention provides
the use of 0.005 to 20% by weight hydroxamic acid or its
corresponding hydroxamate of the structure
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/cx / OH
R1
R2
wherein R1 is a C8 -C14 normal alkyl group, and R2 is a hydrogen
atom, in a laundry pre-treatment composition, for improving the
particulate soils stain removal from a textile substrate,
wherein the pre-treatment composition further comprises from 3
to 80 wt% of a detersive surfactant system; and optionally
other ingredients to 100 wt% provided that zeolite, phosphate
and carbonate builders are present at less than 5 wt%, and
wherein the pre-treated fabrics are washed in a wash liquor
comprising a main wash detergent formulation, preferably a main
wash detergent powder, including surfactant and more than 15%
by weight builder.
Detailed Description of the Invention
Whenever either the term 'hydroxamic acid' or 'hydroxamate' is
used in this specification, this encompasses both hydroxamic
acid and the corresponding hydroxamate (salt of hydroxamic
acid), unless indicated otherwise.
All percentages mentioned herein are by weight calculated on
the total composition, unless specified otherwise. The
abbreviation 'wt%' is to be understood as % by weight of the
total composition.
The stained fabric is treated with the liquid laundry pre-
treatment composition comprising hydroxamate according to the
invention and the primary detergency is the measured stain
removal by the laundry composition on the stain. This is a
separate process to so-called soil release using a polymer,
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which is treatment of fabric with a polymer (through a wash or
other such treatment), with subsequent staining of the fabric,
the soil release polymer having the effect of the easier
removal of the stain.
The following definitions pertain to chemical structures,
molecular segments and substituents:
Molecular weights of monomers and polymers are expressed as
weight average molecular weights, except where otherwise
specified.
The textile/fabric substrates used can be any typical
textile/fabric substrate, such as cotton (woven, knitted &
denim), polyester (woven, knitted & micro fibre), nylon, silk,
polycotton (polyester/cotton blends), polyester elastane,
cotton elastane, viscose rayon, acrylic or wool. Particularly
suitable textile/fabric substrates are cotton, polycotton and
polyester substrates.
Particulate stains are stains comprising for example dirt,
soil, clay, mud or soot. They are predominately solid in nature
and come into contact with fabrics in the course of their
regular use.
Hydroxamic acid and derivatives
The general structure of a hydroxamic acid in the context of
the present invention has been indicated in formula 3, and R1,
is as defined above. When R1, is an alkyl ether group CH3 (CH2)n
(E0)m wherein n is from 2 to 20 and m is from 1 to 12 then the
alkyl moiety terminates this side group. Preferably, R1 is
chosen from the group consisting of C4f CS, C6r C7, C8r C9, C10,
Cli, or C12 Or C14 normal alkyl group, most preferably R1 is at
least a C8-14 normal alkyl group. When the C8 material is used
this is called octyl hydroxamic acid. The potassium salt is
particularly useful.
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octanohydroxarnic acid K salt
However, other hydroxamic acids, whilst less preferred, are
suitable for use in the present invention. Such suitable
5 compounds include, but are not limited to, the following
compounds:
NH2
NH2
0 NH
OH
Lysine H ydroxam ate*HCI
NH2
0
HN
OH NH2 UH
Methionine Hydroxarnate Norvaline Hydroxarnate
10 Such hydroxamic acids are commercially available.
Without wishing to be bound by theory, we believe that the
hydroxamate acts by binding to metal ions that are present in
the soil on the fabric. This binding action, which is, in
effect, the known sequestrant property of the hydroxamate is
not, in itself, of any use to remove the soil from the fabric.
The key is the "tail" of the hydroxamate i.e. the group R1
minus any branching that folds back onto the amate Nitrogen via
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group R2. The tail is selected to have an affinity for the
surfactant system. This means that the soil removal ability of
an already optimised surfactant system is further enhanced by
the use of the hydroxamate as it, in effect, labels the
difficult to remove particulate material (clay) as "soil" for
removal by the surfactant system acting on the hydroxamate
molecules now fixed to the particulates via their binding to
the metal ions embedded in the clay type particulates. The
detersive surfactants will adhere to the hydroxamate, leading
overall to more surfactants interacting with the fabric,
leading to better soil release. Therewith the hydroxamic acids
act as a linker molecule facilitating the removal and
suspension of the particulate soil from the fabric into a wash
liquor and thus boosting the primary detergency.
This enhancing of the primary detergency of surfactant systems
is especially relevant when using a concentrated liquid pre-
treatment detergent compositions having a relatively low pH
(7.5-8) as compared to traditional laundering processes with
particulate detergent compositions (pH 9-10.5). The lower pH
during the laundry pre-treatment process with liquid detergent
compositions may lead to reduced soil release, as the surface
charges of the soils are less negative as compared to the
higher pH during the conventional well built and buffered
laundering processes, achieved with conventional zeolite or
phosphate built powder products. This surface charge of the
soil may lead to increased repellence of the surfactants by the
soil, possibly leading to reduced release of the soil. Hence,
in the method of the invention the hydroxamates are used in a
liquid laundry pre-treatment composition, and more preferred
the detersive surfactant concentration in said liquid pre-
treatment composition is from 20 to 80 wt%.
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The hydroxamates have a higher affinity for transition metals,
like iron, than for alkaline earth metals like calcium and
magnesium, therefore the hydroxamic acid primarily acts to
improve the removal of soil on fabric, especially particulate
soils, and not additionally as a builder for calcium and
magnesium. This selectively is especially beneficial if the
laundering composition is underbuilt; especially when it
comprises less than 5 wt% zeolite or phosphate builder.
Surfactants
The pre-treatment laundry detergent composition in which the
hydroxamate is used comprises a detersive surfactant system at
a concentration from 3 to 80 wt%. By a detersive surfactant
system, we mean that the surfactants therein provide a
detersive, i.e. cleaning effect to textile fabrics treated as
part of a laundering process. Other surfactants, which are not
detersive surfactants, can be used as part of the composition.
Preferably, the detersive surfactant is present at a level of
from 5 to 60 wt%, more preferably from 10 to 50 wt%. Even more
preferably, the detersive surfactant system comprises at least
20, or 30 or even 40 wt% of the composition.
In general, any surfactant may be used as detersive
surfactants, including anionic, nonionic, cationic, and
amphoteric or zwitterionic surfactants, or combinations
thereof.
In general, the nonionic and anionic surfactants of the
surfactant system may -if present- be chosen from the
surfactants described in 'Surface Active Agents' Vol. 1, by
Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry
& Berch, Interscience 1958, in the current edition of
'McCutcheon's Emulsifiers and Detergents' published by
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Manufacturing Confectioners Company or in
'Tenside-Taschenbuch', H. Stache, 2nd Edn., Carl Hauser Verlag,
1981.
Nonionic surfactant
For the purposes of this disclosure, 'nonionic surfactant'
shall be defined as amphiphilic molecules with a molecular
weight of less than about 10,000, unless otherwise noted, which
are substantially free of any functional groups that exhibit a
net charge at the normal wash pH of 6-11.
Any type of nonionic surfactant may be used, although preferred
materials are further discussed below. Highly preferred are
fatty acid alkoxylates, especially ethoxylates, having an alkyl
chain of from C8-C35, preferably C8-C30, more preferably C10-C24,
especially C10-C18 carbon atoms, for example, the Neodol range
from Shell (The Hague, The Netherlands); ethylene
oxide/propylene oxide block polymers which may have molecular
weight from 1,000 to 30,000, for example, Pluronic (trademark)
from BASF (Ludwigshafen, Germany); and alkylphenol ethoxylates,
for example Triton X-100, available from Dow Chemical (Midland,
Mich., USA).
Other nonionic surfactants may also be considered. These
include condensates of alkanolamines with fatty acids, such as
cocamide DEA, polyol-fatty acid esters, such as the Span series
available from Uniqema (Gouda, The Netherlands), ethoxylated
polyol-fatty acid esters, such as the Tween series available
from Uniqema (Gouda, The Netherlands), alkylpolyglucosides,
such as the APG line available from Cognis (DiAsseldorf,
Germany) and n-alkylpyrrolidones, such as the Surfadone series
of products marketed by ISP (Wayne, N.J., USA). Furthermore,
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nonionic surfactants not specifically mentioned above, but
within the definition, may also be used.
The more preferred nonionic surfactants are the fatty acid
ethoxylates with an average degree of ethoxylation of 7,
alkoxylates with one propylene oxide and multiple ethylene
oxide units, seed oil based surfactant, such as Ecosurf SA7 or
SA9 available from Dow Chemical, APGs, and branched alcohol
Guerbet nonionics.
Anionic surfactant
'Anionic surfactants' are defined herein as amphiphilic
molecules comprising one or more functional groups that exhibit
a net anionic charge when in aqueous solution at the normal
wash pH of between 6 and 11.
Preferred anionic surfactants are the alkali metal salts of
organic sulphur reaction products having in their molecular
structure an alkyl radical containing from about 6 to 24 carbon
atoms and a radical selected from the group consisting of
sulphonic and sulphuric acid ester radicals.
Although any anionic surfactant hereinafter described may be
used, such as alkyl ether sulphates, soaps, fatty acid ester
sulphonates, alkyl benzene sulphonates, sulphosuccinate esters,
primary alkyl sulphates, olefin sulphonates, paraffin
sulphonates and organic phosphate; preferred anionic
surfactants are the alkali and alkaline earth metal salts of
fatty acid carboxylates, fatty alcohol sulphates, preferably
primary alkyl sulfates, more preferably they are ethoxylated,
for example alkyl ether sulphates; alkylbenzene sulphonates,
alkyl ester fatty acid sulphonates, especially methyl ester
fatty acid sulphonates and mixtures thereof.
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Cationic, amphoteric surfactants and/or zwitterionic
surfactants
Also cationic, amphoteric surfactants and/or zwitterionic
5 surfactants may be present in the liquid laundry pre-treatment
compositions in which the hydroxamate is used as cosurfactant
according to the invention.
Preferred cationic surfactants are quaternary ammonium salts of
10 the general formula R1R2R3R4N+ X, for example where R1 is a C12-
C14 alkyl group, R2 and R3 are methyl groups, R4 is a
2-hydroxyethyl group, and X is a chloride ion. This material
is available commercially as Praepagen (Trade Mark) HY from
Clariant GmbH, in the form of a 40% by weight aqueous solution.
In a preferred embodiment the liquid laundry pre-treatment
composition in which the hydroxamate is used according to the
invention further comprises an amphoteric or zwitterionic
surfactant. Amphoteric surfactants are molecules that contain
both acidic and basic groups and will exist as zwitterions at
the normal wash pH of between 6 and 11. Preferably an
amphoteric or zwitterionic surfactant is present at a level of
from 0.1 to 20% by weight, more preferably from 0.25 to 15% by
weight, even more preferably from 0.5 to 10% by weight.
Suitable zwitterionic surfactants are exemplified as those
which can be broadly described as derivatives of aliphatic
quaternary ammonium, sulfonium and phosphonium compounds with
one long chain group having about 8 to about 18 carbon atoms
and at least one water solubilizing radical selected from the
group consisting of sulfate, sulfonate, carboxylate, phosphate
or phosphonate. A general formula for these compounds is:
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YR3Z
R1 contains an alkyl, alkenyl or hydroxyalkyl group
with 8 to 18 carbon atoms, from 0 to 10 ethylene-oxy groups or
from 0 to 2 glyceryl units; Y is a nitrogen, sulphur or
phosphorous atom; R2 is an alkyl or hydroxyalkyl group with 1
to 3 carbon atoms; x is 1 when Y is a sulphur atom and 2 when Y
is a nitrogen or phosphorous atom; R3 is an alkyl or
hydroxyalkyl group with 1 to 5 carbon atoms and Z is radical
selected from the group consisting of sulfate, sulfonate,
carboxylate, phosphate or phosphonate.
Preferred amphoteric surfactants are amine oxides, for example
coco dimethyl amine oxide.
Detergency builders
The liquid laundry pretreatment compositions in which the
hydroxamate is used preferably comprise low levels of
detergency builder, based on the weight of the total
composition. The amounts of the inorganic builders zeolite and
phosphate are less than 5 wt%.
On the other hand, the main wash detergent formulation used in
step (II) of the method of the invention preferably comprises
surfactant material and more than 15% by weight of builder.
Said main wash detergent is preferably a main wash detergent
powder.
Preferably the builder used both in the pretreatment step (I)
of the method of the invention is selected from the group of
alkali and alkaline earth metal carbonates (e.g. sodium
carbonate), silicates (e.g. layered silicate), and organic
builders such as citrates (e.g. sodium citrate), succinates,
sulphamates and malonates, and any combination of these. The
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organic builders are preferred. They may be used at levels of 1
wt% or more, up to, say, 50 wt%.
Organic builders that may be present in the liquid pre-
treatment composition include polycarboxylate polymers such as
polyacrylates and acrylic/maleic copolymers; polyaspartates;
monomeric polycarboxylates such as citrates, gluconates,
oxydisuccinates, glycerol mono-di- and trisuccinates,
carboxymethyloxysuccinates, carboxy-methyloxymalonates,
dipicolinates, hydroxyethyliminodiacetates, alkyl- and
alkenylmalonates and succinates; and sulphonated fatty acid
salts.
Organic builders may be used in minor amounts. Especially
preferred organic builders are citrates, suitably used in
amounts of from 1 to 30 wt%, preferably from 1.5 to 10 wt%; and
acrylic polymers, more especially acrylic/maleic copolymers,
suitably used in amounts of from 0.5 to 15 wt%, preferably from
1 to 10 wt%.
Builders, both inorganic and organic, are preferably present in
alkali metal salt, especially sodium salt, form.
Other optional Ingredients
In addition to the essential components detailed in the claims,
the liquid pre-treatment formulation may include one or more
optional ingredients to enhance performance and properties.
While it is not necessary for these elements to be present in
order to practice this invention, the use of such materials is
often very helpful in rendering the formulation acceptable for
consumer use.
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Examples of optional components include, but are not limited
to: hydrotropes, fluorescent whitening agents, photobleaches,
fibre lubricants, reducing agents, enzymes, enzyme stabilising
agents (such as borates and polyols), powder finishing agents,
defoamers, bleaches, bleach catalysts, soil release agents,
especially soil release polymers for cotton or polyester or
both, antiredeposition agents, especially antiredeposition
polymers, dye transfer inhibitors, buffers, colorants,
fragrances, pro-fragrances, rheology modifiers, anti-ashing
polymers, preservatives, insect repellents, soil repellents,
water-resistance agents, suspending agents, aesthetic agents,
structuring agents, sanitisers, solvents, including aqueous and
non-aqueous solvents, fabric finishing agents, dye fixatives,
wrinkle-reducing agents, fabric conditioning agents and
deodorizers.
These optional ingredients may further include any one or more
of the following: soap, peroxyacid and persalt bleaches, bleach
activators, sequestrants, cellulose ethers and esters, other
antiredeposition agents, sodium sulphate, sodium silicate,
sodium chloride, calcium chloride, sodium bicarbonate, other
inorganic salts, fluorescers, photobleaches, polyvinyl
pyrrolidone, other dye transfer inhibiting polymers, foam
controllers, foam boosters, acrylic and acrylic/maleic
polymers, proteases, lipases, cellulases, amylases, other
detergent enzymes, citric acid, soil release polymers, fabric
conditioning compounds, coloured speckles, and perfume.
The main wash detergent formulation used in the 2nd step of the
method of the invention may also suitably contain one or more
of the optional ingredients mentioned hereinabove.
In particular, the main wash laundry detergent formulation may
suitably contain a bleach system based on peroxy bleach
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compounds, for example, inorganic persalts or organic
peroxyacids, capable of yielding hydrogen peroxide in aqueous
solution. Suitable peroxy bleach compounds include organic
peroxides such as urea peroxide, and inorganic persalts such as
the alkali metal perborates, percarbonates, perphosphates,
persilicates and persulphates. Preferred inorganic persalts are
sodium perborate monohydrate and tetrahydrate, and sodium
percarbonate. Especially preferred is sodium percarbonate
having a protective coating against destabilisation by
moisture. Sodium percarbonate having a protective coating
comprising sodium metaborate and sodium silicate is disclosed
in GB 2 123 044B (Kao).
The peroxy bleach compound is suitably present in an amount of
from 5 to 35% by weight, preferably from 10 to 25% by weight.
The peroxy bleach compound may be used in conjunction with a
bleach activator (bleach precursor) to improve bleaching action
at low wash temperatures. The bleach precursor is suitably
present in an amount of from 1 to 8% by weight, preferably from
2 to 5% by weight.
Preferred bleach precursors are peroxycarboxylic acid
precursors, more especially peracetic acid precursors and
peroxybenzoic acid precursors; and peroxycarbonic acid
precursors. An especially preferred bleach precursor suitable
for use in the present invention is N,N,N',N'-tetracetyl
ethylenediamine (TAED). Also of interest are peroxybenzoic acid
precursors, in particular, N,N,N-trimethylammonium toluoyloxy
benzene sulphonate.
A bleach stabiliser (heavy metal sequestrant) may also be
present in the main wash detergent powder. Suitable bleach
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stabilisers include ethylenediamine tetraacetate (EDTA) and the
polyphosphonates such as Dequest (Trade Mark), EDTMP.
However, notwithstanding the above it is preferred for the said
powder to contain no bleach and to rely on the improved clay
5 stain removal derived from the novel hydroxamate and surfactant
combinationpresent in the liquid pre-treatment composition used
in the 1st step of the method of the invention.
The main wash detergent formulation may also contain one or
10 more enzymes. Suitable enzymes include the proteases, amylases,
cellulases, oxidases, peroxidases and lipases usable for
incorporation in detergent compositions.
Said detergency enzymes are commonly employed in granular form
in amounts of from about 0.1 to about 3.0 wt%. However, any
15 suitable physical form of enzyme may be used in any effective
amount.
Antiredeposition agents, for example cellulose esters and
ethers, for example sodium carboxymethyl cellulose, may also be
20 present.
The main wash detergent formulation may also contain soil
release polymers, for example sulphonated and unsulphonated
PET/POET polymers, both end-capped and non-end-capped, and
polyethylene glycol/polyvinyl alcohol graft copolymers such as
Sokolan (Trade Mark) HP22. Especially preferred soil release
polymers are the sulphonated non-end-capped polyesters
described and claimed in WO 95 32997A (Rhodia Chimie).
Product form and preparation
The pre-treatment composition used in the first step of the
method of the invention is in the liquid form. Preferably,
said composition contains a hydrotrope to solubilise the
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ingredients thereof. Ethanol is preferably avoided. Preferred
hydrotropes are propylene glycol and glycerol. Based on this
teaching the skilled person will be able to select other
hydrotropes that avoid the use of highly volatile solvents like
ethanol without the need for inventive activity.
The main wash detergent powders preferably used in the second
step of the method of the invention may be of low to moderate
bulk density. In that case they may be prepared by spray-drying
slurry, and optionally post dosing (dry-mixing) further
ingredients. Routes available for powder manufacture include
spray drying, drum drying, fluid bed drying, and scraped film
drying devices such as the wiped film evaporator. A preferred
form of scraped film device is a wiped film evaporator. One
such suitable wiped film evaporator is the 'Dryex system' based
on a wiped film evaporator available from Ballestra S.p.A.
Alternative equipment would be the Chemithon the 'Turbo Tube'
dryer system wherein a high active surfactant paste is heated
and metering to a multi tube, steam-jacketed drying vessel.
Alternatively, the main wash powder may be a 'Concentrated' or
'compact' powder. Such powders may be prepared by mixing and
granulating processes, for example, using a high-speed
mixer/granulator, or other non-tower processes.
The invention will now be further described with reference to
the following non-limiting examples.
EXAMPLES
Measurement of Soil Release Index (SRI)
SRI is a measure of how much of a stain on textile is removed
during a washing process. The intensity of any stain can be
measured by means of a reflectometer in terms of the difference
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between the stain and a clean cloth giving AE* for each stain.
It is defined as AE* and is calculated as:
'2 _L `-' 2 \ 2
AE* = II(L*sta,n¨before ¨lean¨cloth/ ' kstain¨before aclean-cloth ) (b*
s tam¨before 'clean¨cloth I
L*, a*, and b* are the coordinates of the CIE 1976 (L*, a*, b*)
colour space, determined using a standard reflectometer. AE*
can be measured before and after the stain is washed, to give
AE*,, (before wash) and (after wash). SRI is then defined
as:
SRI = 100 ¨ AEa*,,
A SRI of 100 means complete removal of a stain.
AE after wash is the difference in L a b colour space between
the clean (unwashed) fabric and the stain after wash. So a AE
after wash of zero means a stain that is completely removed.
Therefore, a SRIaw (aw: after wash) of 100 is a completely
removed stain. The clean (or virgin) fabric is an "absolute
standard" which is not washed. For each experiment, it refers
to an identical piece of fabric to that to which the stain is
applied. Therefore, its point in L a b colour space stays
constant.
Determination of SRI-values
For the determination of the SRI-values, a standard protocol
was used, called the Tergometer wash protocol.
Said Tergometer wash protocol is as follows:
1. Measurement of the colour of the stain on the textile cloth
(before washing).
2. Switch on the Tergometer and set to a temperature of 30 C.
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3. Add water of required hardness, leave to heat to 30 C for 10
minutes.
4. Add formulation to each pot and then agitate at 100 rpm for
1 minute
5. Add the stained swatches and ballast into each pot.
6. Start the wash, agitate at 100 rpm and leave to wash for 12
minutes.
7. Rinse with fresh water (26 FH) for 2 minutes.
8. Repeat rinse.
9. Dry overnight in the dark.
10. Read stains after wash.
Example 1: Removal of a Indian Red Soil on knitted polyester,
preteated with a liquid Formualtion and then washed using a
powder formulation
Two liquid formulations A and B were formulated.
The surfactants present therein are sodium alkyl benzene
sulphonate (Na LAS anionic) and alkyl ether sulfate (SLES 3E0
Ex Unilever). Furthermore, formulation B contains a Coco
Hydroxamic Acid (Ex AXIS House), as shown in Table 1. Other
standard laundry ingredients were also included. The pH of
these formulations was buffered to between 7 and 8.5. The
formulations were made using demineralised water.
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Table 1: Liquid formulations used
A 1 B
wt % in final
Ingredients product
Mono propyl glycol 3.7 3.7
Glycerol 1.1 1.1
NaOH 1.3 1.3
TEA 1.95 1.95
NaLAS 14.8 14.8
SLES (3E0) 3.7 3.7
Coco Hydroxamic Acid 0.5
(Ex Axis House
Savinase Ultra 16L 0.1 0.1
Balance (demineralised 73.45 72.85
water, perfume)
Furthermore, a main-wash type detergent powder product C
including the surfactant alkyl benzene sulphonate was
formulated having the composition shown in Table 2.
Table 2: Powder detergent product C
Ingredient Wt % in Final
Product
LAS 20
Zeolite 4
sodium silicate 9.6
Soda Ash 20.2
Sodium Sulphate 33.8
Moisture 3.2
Minors (including enzyme, 9.2
perfume, pigments and flow
aids)
The Indian Red soil on knitted polyester stains tested were
treated with 0.8 g of one of the two liquid pre-treatment
formulations and then after 5 mins standing time washed in 1L
of wash liquor made in 26FH water with 2.8g/L of powder product
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C. The resultant SRIaw values after applying the two pre-
treatment formulations A and B followed by the wash step with
powder product C as outlined above are shown in Table 3 below.
5 Table 3: Stain removal values (SRI)
Pretreatment Liquid SRIaw, Indian Red Soil on
Knitted Polyester
A (no coco hydroxamic acid) 79.7
B (0.5% coco hydroxamic acid) 90.5
Table 3 shows the clear benefit in removal when pretreating
stain with a formulation containing alkyl hydroxamic acid.
Example 2: Removal of a Indian Red Soil on knitted polyester
and woven cotton, preteated with Liquid
(Anionic/Nonionic)Formualtions and then washed using a powder
formulation
Two liquid formulations D and E were formulated.
The surfactants present therein are sodium alkyl benzene
sulphonate (Na LAS anionic) and alcohol ethoxylate (Neodol 25-
7). Furthermore, formulation E contains a Coco Hydroxamic Acid
(Ex AXIS House), as shown in Table 4. Other standard laundry
ingredients were also included. The pH of these formulations
was buffered to between 7 and 8.5. The formulations were made
using demineralised water.
Table 4: Liquid formulations used
Ingredients LAS/NI (D) LAS/NI+coco
HXA (E)
% in formulation
Glycerol 5.00 5.00
PPG 9.00 9.00
NaOH 4.73 4.73
TEA 3.24 3.24
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Citric Acid 0.98 0.98
LAS 27.60 27.60
Neodol 25-7 12.50 12.50
Soap 4.78 4.78
Dequest 2066 0.50 0.50
Coco hydroxamate 0 2
water demin Balance to Balance to
100% 100%
The powder product used in this example was the same as that of
example 1.
The Indian Red soil (on knitted polyester and on woven cotton)
stains tested were treated with 0.8 g of one of the liquid
pretreatment formulations and then after 5 mins standing time
washed in 1L of wash liquor made in 26FH water with 2.8g/L of
powder product C. The resultant SRIaw after applying these two
pre-treatment formulations D and E followed by the wash process
with the powder product are shown in Table 5 below.
Table 5: Stain removal values (SRI)
Pretreatment SRIaw, Indian Red SRIaw, Indian Red
Liquid Soil on Knitted Soil from Woven
Polyester cotton
D (no coco 80.8 71.6
hydroxamic
acid)
E (2% coco 84.6 75.3
hydroxamic
acid)
Table 5 shows the clear benefit in removal when pretreating
stain with a formulation containing alkyl hydroxamic acid.
