Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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LAUNDRY COMPOSITIONS FOR USE IN A TUMBLE DRYER
Technical Field
The present invention relates to improvements to fabric
treatment compositions and a process for use of the same. It
is,particularly concerned with a method and compositions for
use with a tumble drier.
Background to the Invention
Sequestering agents have been used in detergents since
ancient times, when materials such as citric and tartaric
acid were employed to obtain clear products with good
solubility. In particular traces of metals such as ferric
iron can cause discoloration of textiles and it has long
been known to use sequestering agents, such as oxalic acid,
to remove them.
In 1937, IG Farbenindustrie introduced the amino-carboxylic
acid sequestrants for use in the dyeing industry. It is well
known that traces of metals, particularly calcium,
magnesium, iron, copper and aluminium are often responsible
for faulty dyeing. These impurities can be present in a dye
bath because of corrosion from fittings, from the water used
or as carry over from a previous process. The difficulties
that occur in the dyeing process are due to the sensitivity
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of the dyestuffs to these trivalent and divalent cations.
Dyestuffs form less soluble salts with these metals and this
can lead to precipitation. Additionally, many dyestuffs
contain complexing groups which complex with metal ions and
may lead to changes in the solubility or colour of the dye.
This latter point is particularly true with the mordant
dyes. Chrome dyes, on the other hand intentionally chelate
chromium and the replacement of chromium with iron in the
dyestuff leads to a disastrous change of colour.
Almost everyone is aware that repeated laundering of clothes
will eventually cause most colours to fade or change in tint
or hue. Consequently, many products have been marketed under
the banner of `colour care'. The first of these merely
omitted bleach and other components which could damage
colours. Later developments have included the incorporation
of agents to prevent dye loss or dye transfer.
In certain ways, the environment within which laundering
processes occur is similar to that in a dyeing bath. Dyed
fabric is subjected to a combination of heat and water of
variable purity and it is to be expected that the presence
of metal ions will cause similar problems to those that
occur in dyeing. In recent years, it has been suggested that
sequestrants can have benefits in the laundering process.
The laundering process comprises a series of unit operations
of which several involve the wet treatment of fabrics. These
can include pre-soak and pre-treatment processes, as well as
the more commonplace washing/rinsing process. Often these
washing and rinsing processes are mechanised. Optional
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processing includes machine-drying either by centrifuge or
by the application of heat, as in a so-called `tumble
drier'. Treatment components can be added at various stages,
for example, with detergents being added in the wash and
conditioners being added in the rinse.
WO 2000/34427 discloses the use of the sequestrant IDS
(iminodisuccinic acid) at various stages within the laundry
process as part of a non-bleaching detergent composition
containing IDS for colour care and stain-removal benefits.
US 5686376 discloses the possibility of adding sequestering
agents in the rinse to improve colour fidelity.
Instances of treatment in the drier are less common. Often,
treatment in the drier is restricted to the addition of
perfume (from a so-called `drier sheet') although it is also
possible to treat fabrics with conditioners/softeners during
this operation.
US 6107270 discloses dryer-added fabric softener
compositions that are said to provide colour and other
fabric benefits. Suggested sequestering agents include TPED
(Quadrollm L), EDDS and NTA. US 6025321 discloses further
dryer-added fabric softener composition to provide colour
and other fabric benefits, suggesting the same sequestering
agents.
Persistent staining and colour loss and/or change on fabrics
are major issues for many users of domestic detergent
compositions. There is therefore an ongoing need to find
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improved sequestering agents and or the means for delivering
them.
Brief Description of the Invention
We have determined that a particular group of sequestering
agents gives an improved colour benefit and indeed even a
colour restoration benefit when used in the tumble drier. It
is believed that this is in some way due to the removal of
metal ions associated with the fabrics either through
staining or through an earlier step in the laundry process.
It is believed that treatment with these materials prevents
further transition metal ion colour damage and that such
treatment can give stain removal benefits in the next wash.
The present invention provides a laundry treatment process,
which comprises tumble drying clothes in the presence of a
chelating agent which has one nitrogen atom and at least
four carboxylic acid groups per molecule, or a salt thereof.
The present invention also provides a laundry drier sheet
comprising a substrate and a chelating agent is of the
general formula
AMENDED SHEET
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HOOC- (R1. COOH) R2-NR5-R3 (R4. COOH) -COOH
wherein R1-R5 are each independently, C1-C5 alkyl, hydroxy-
5 alkyl or hydrogen.
Detailed Description of the Invention
Preferred 1-N 4-COOH chelating agents are disuccinnic acids
containing a nitrogen hetero-atom. Preferred materials are
amine-bridged.
Preferably, the chelating agent is of the general formula:
HOOC- (R1. COOH) R2-NR5-R3 (R4. COOH) -COOH (1)
wherein R1-R5 are each independently, C1-C5 alkyl, hydroxy-
alkyl or hydrogen. In this arrangement, two of the
carboxylic acid groups are disposed on either side of the
bridging nitrogen atom.
In a preferred embodiment, R1-R4 in the formula (1) are
methylene and R5 is hydrogen. A particularly preferred
material is therefore iminodisuccinnic acid or a salt
thereof. The structure of which is given below as formula
(2) .
HOOC- (CH2. COOH) CH-NH-CH (CH2. COOH) -COOH (2)
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It is envisaged that the corresponding hydroxy acids can
also be used.
The process can be conducted in the presence of other fabric
treatment agents. These are preferably one or more of a
fabric softening agents, fabric conditioning agents,
perfumes, anti-static agents, dye-transfer inhibiting
polymers, dye fixing agents, other sequestrants, chlorine
scavenging agents, lubricants, cross-linking polymers, soil
release polymers, and optical brightening agents.
In its broadest aspect, compositions that embody the present
invention can be in the form of a liquid, gel, paste, foam,
powder, sheet, film, deformable solid, breakable solid or
combination thereof.
A particularly preferred form is that of the drier sheet.
Preferred sheets are non-woven, and are more preferably
embossed. A range of suitable materials are known including
a polyester/rayon (50:50 mix) in sheet form. Levels of
sequestrant are typically such that the weight of
sequestrant is in the range 0.0005-1.0owt of the weight of
cloth being placed in the drier.
In order that the invention may be further understood it
will be described below with reference to the following non-
limiting examples.
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Examples:
The reflectance versus wavelength profile of 1%, Direct Red
80 dyed, unfixed, woven, cotton fabric was measured using
the large aperture on a Texicon ICS Spectraflash 500 TM,
(excluding the UV below 420nm). Sixteen measurements were
taken (using 4 cloth thicknesses over the Spectraflash
aperture).
The Direct Red 80 dyed cotton fabric was obtained from
Campbell Hayward Ltd. (Springvale Works, Shawclough Rd.
Waterfoot, Rossendale, Lancs. BB4 9JZ) and was not made up
into garments.
The fabric was then washed twice in demineralised water
containing transition metal and water hardness ions at the
following concentrations: 1.lppm Cue+: 2.Oppm Fe3+: 0.12ppm
Mn2+: 2.3ppm Zn2+. The levels selected are quoted in the
literature as being representative of the transition metal
ion levels found in the main wash for soiled loads(Patent
W09403553). Water hardness was: 4 FH Ca2+: 2 FH Mg 2+
Washing was performed in a vertical axis (US) machine
(WhirlpoolTM Super Capacity Plus Washer) set for a 12min wash
on a small load setting. Two applications of transition
metal ions were performed in order to damage the fabric by
transition metal ion deposition. This has the effect of
changing the hue of the fabric, to give a visible blue
tinge. The fabric was dried in a tumble dryer (WhirlpoolTM
Super Capacity Dryer) after each wash.
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The change in colour of the `colour-damaged' fabric when
treated with chelating agents, provides a sensitive measure
of their efficacy. For these experiments, this fabric was
cut into 20cm2 swatches and overlooked. The reflectance
versus wavelength profile of these swatches was measured
using the large aperture on a Texicon ICS Spectraflash
500 TM, (excluding the W below 420nm) to obtain a
comparative measure of damage compared to the new fabric.
Here, 4 measurements were taken per swatch, using 4 cloth
thicknesses over the Spectraflash aperture. Five swatches
were used per drying experiment. The swatches were rewet
using demineralised water, prior to mixing in with a wet
ballast load, containing white non-mercerised, desized woven
cotton. The ballast had previously been put through a rinse
cycle with demineralised water.
Examples 1-5 and comparatives:
The dose response characteristic of IDS was investigated
using the IDS concentrations (% on total weight of fabric in
the load) given in table 1 below.
To obtain these results a Miele NovotronicTM T454 tumble
dryer was allowed to warm up on "extra dry cotton" heat
setting for 5min.
A nonwoven, embossed, polyester/rayon (50:50 mix) sheet
(95gm-2) was loaded with 62.5g of IDS liquid sequestrant
(Iminodisuccinic acid, tetrasodium salt, 40% activity ex.
Nippon Shokubai). This corresponds to 1% IDS on weight of
fabric for a 2.5kg load. The IDS solution was spread out
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evenly over the sheet, using a glass rod. The sheet was
placed inside the dryer, with the 2.5kg fabric load
comprising white, desized, non-mercerised, cotton ballast +
five 20x2Ocm `colour damaged', Direct Red 80, overlocked,
cotton test swatches. The load was dried on the extra dry
cotton heat setting.
Once the load was dry, the test swatches were removed from
the tumble dryer and the reflectance versus wavelength
profile was measured for each using the large aperture on a
Texicon ICS Spectraflash 500 T", (excluding the UV below
420nm). Four measurements were taken per cloth (using 4
cloth thicknesses over the Spectraflash aperture) giving a
total of 20 readings per wash load. This experiment was
repeated for separate wash loads using concentrations of
0.5%, 0.1%, 0.01 and 0.005% IDS on weight of fabric based on
a 2.5kg load. N.B. The total volume of IDS solution added
onto the sheet was kept constant at 62.5g.
The experiment was performed twice for each IDS
concentration, giving a total of 40 reflectance readings per
concentration. The average reflectance reading at 620nm for
each concentration is quoted in Table 1.
Comparison of the reflectance profiles showed that the
reflectance value at 620nm was found to be the most
sensitive wavelength for measuring differences in the
sequestering capability of the IDS for ions on the fabric
surface. The results from the dose response experiment at
620nm are shown below in Table 1. (95% confidence limits
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were calculated for the experiment using the Excel"'
statistical analysis tool.)
Table 1 - Dose Response for IDS
Example Treatment Mean Standard Confidence
Reflectance Deviation Limits
at 620nm
Comparative Unwashed 46.56 - -
A
Comparative Damaged 35.99 - -
B
Comparative 0% IDS 37.92 1.70 1.49
C
1 0.005% IDS 39.84 2.71 1.68
2 0.01% IDS 43.68 2.72 1.69
3 0.1% IDS 49.64 4.21 2.61
4 0.5% IDS 54.98 0.88 0.54
5 1% IDS 53.89 1.86 1.15
From these results it can be seen that washing fabric in the
presence of the metal ions causes a significant lowering of
reflectance at this wavelength (compare comparative A with
B). Some of this loss can be recovered by wetting and drying
the fabric with demineralised water (compare comparative B
with C). However, it can be seen that the presence of even
low levels of IDS causes a significant improvement in the
recovery of mean reflectance.
Examples 6 and comparatives:
A level of 0.01% sequestrant was chosen for the
investigation into the relative performances between the
sequestrants listed below:
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a) TPED (N, N, N', N' tetrakis (2-hydroxy propyl)
ethylenediamine: available as Quadrol TM L, 100%
activity, ex BASF).
b) EDDS (ethylene diamine disuccinic acid tri sodium salt:
available as Octaquest E30 TM ex Octet 32. 7-.)
c) NTA (Nitrilotriacetic acid sodium salt monohydrate 99%
ex Aldrich).
The method used was the same as that used for examples 1-5.
Results are given in table 2 below:
Table 2: - Comparison with other sequestrants
Example Treatment Mol. Mean Std. 95%
Wt. Ref. at Deviation Conf.
620nm
Comparative Unwashed - 46.56 0.16 0.16
A
Comparative Damaged - 35.99 0.29 0.28
B
Comparative 0% IDS - 37.92 1.70 1.49
C
6 0.01% IDS 337.1 43.68 2.72 1.69
Comparative 0.01% EDDS 358 40 3.02 1.87
D
Comparative 0.01% TPED 292.42 40 1.70 1.05
E
Comparative 0.01% NTA 257 39 3.9 2.42
F
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From these results it can be shown that the IDS sequestrant
shows statistically better performance at equivalent weight
(0.01%) than the other sequestrants (TPED, EDDS and NTA,
comparatives D-F).
Example 7 and Comparatives:
Woven fabric dyed with 1% Direct Red 80 (unfixed) was
obtained from Campbell Hayward Ltd. (Springvale Works,
Shawclough Rd. Waterfoot, Rossendale, Lancs. BB4 9JZ)
The reflectance versus wavelength profile was measured for
the new fabric using the large aperture on a Texicon ICS
Spectraflash 500 TM, (excluding the UV below 420nm) . Sixteen
measurements were taken (using 4 cloth thicknesses over the
Spectraflash aperture).
The red woven fabric was treated with transition metal ions
as follows:
The fabric was washed twice in demineralised water
containing transition metal and water hardness ions at the
following concentrations: 1.lppm Cue+: 2.Oppm Fe 3+: 0.12ppm
Mn2+: 2.3ppm Zn2+. The levels selected are quoted in
literature (W09403553)as being representative of the
transition metal ion levels found in the main wash when
soiled loads are used. Water hardness was: 4 FH Ca2+: 2 FH
Mg 2+
Washing was performed in a vertical axis (US) machine
(Whirlpool" Super Capacity Plus Washer) set for a 12min wash
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on a small load setting. Two applications of transition
metal ions were performed in order to damage the fabric by
transition metal ion deposition. This has the effect of
changing the hue of the fabric, to give a visible blue
tinge. The fabric was dried in a tumble dryer (Whirlpool"
Super Capacity Dryer) in between each wash.
The change in colour of the `colour-damaged' fabric when
treated with chelating agents, provides a sensitive measure
of their efficacy. For these experiments, this fabric was
cut into 20cm2 swatches and overlocked. The reflectance of
these swatches was measured to obtain a comparative measure
of damage. The reflectance versus wavelength profile was
measured for the `colour-damaged' fabric using the large
aperture on a Texicon ICS Spectraflash 500 TM, (excluding the
W below 420nm). Sixteen measurements were taken (using 4
cloth thicknesses over the Spectraflash aperture)
Six (20x20cm) overlocked swatches of the `colour-damaged'
woven fabric dyed with 1% Direct Red 80 (unfixed) were
taken, dampened with demineralised water and mixed randomly
into a 2.5kg ballast load (white, desized, non-mercerised
woven cotton sheeting) which had previously been put through
a rinse cycle with demineralised water.
Sequestrants used were:
TPED: N, N, N', N' tetrakis (2-hydroxy propyl)
ethylenediamine: available as Quadrol TM L, 100%
activity, ex BASF.
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EDDS: Ethylene diamine disuccinic acid tri sodium salt:
available as Octaquest E30 TM ex Octet 32.7%.
NTA: Nitrilotriacetic acid sodium salt monohydrate 99% ex
Aldrich.
IDS: Iminodisuccinic acid tetra sodium salt (ex Nippon
Shokubai Co. Ltd 40.2% aqueous solution)
Moles of all sequestrants used in experiment = 2.14e-3 moles.
A 50ml solution of 2.14e-3 moles IDS in demineralised water
was prepared. A nonwoven, embossed, polyester/rayon (50:50
mix) sheet (95gm2) was loaded with the 50g IDS sequestrant
solution described above. The IDS solution was spread out
evenly over the sheet, using a glass rod.
A US WhirlpoolTM Super Capacity Dryer was allowed to warm up
for 5 minutes on permanent press/heavy setting. The tumble
dryer sheet that had been loaded with IDS was then placed
inside the dryer, with the 2.5kg fabric load (ballast + 6
test swatches). The load was dried using the permanent
press/heavy setting for 90 minutes.
The process was repeated again with a separate, identical
load.
The entire regime was repeated with the other sequestrants,
TPED, NTA and EDDS.
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The reflectance versus wavelength profile was measured for
the treated fabrics using the large aperture on a Texicon
ICS Spectraflash 500 TM, (excluding the UV below 420nm).
Four measurements were taken for each piece of fabric in
each load using 4 cloth thicknesses over the Spectraflash
aperture. This gave 24 measurements per load and 48
readings per treatment.
The reflectance value of the coloured fabric at 620nm is the
most sensitive to the effects of transition metal ions in
this system. The changes in reflectance at 620nm for the
fabric after treatment with the various sequestrants are
shown below (in table 3) for comparison.
Table 3: Comparison with other sequestrants at equimolar
concentration (2.14x10-3 moles).
Treatment Mean reflectance Standard 95% confidence
at 620nm Deviation Limits
Unwashed 46.56 0.16 0.16
Damaged 35.99 0.29 0.28
IDS 44.03 4.48 1.27
TPED 38.23 1.11 0.31
EDDS 39.41 2.99 0.85
NTA 38.45 1.71 0.48
From these figures it can be seen that the IDS containing
system is significantly better than the other materials at
the concentration used.
