Note: Descriptions are shown in the official language in which they were submitted.
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A METHOD OF DRY CLEANING ARTICLES USING DENSIFIED CARBON DIOXIDE
TECHNICAL FIELD
The present invention provides a method for the removal of stains from
articles,
especially fabric, using densified carbon dioxide. More particularly the
invention is concerned
with a method of dry cleaning an article comprising the successive steps of
contacting the
article with a fluid dry cleaning composition containing densified carbon
dioxide at a
temperature between -20 and 60 C and a pressure between 1 and 100 MPa, so as
to allow
stains to dissolve and/or to disperse into the fluid dry cleaning composition,
and separating
the article and the fluid dry cleaning composition, wherein the fluid dry
cleaning composition
contains a surfactant.
BACKGROUND OF THE INVENTION
Densified, particularly supercritical fluid, carbon dioxide has been suggested
as an
alternative to halocarbon solvents used in conventional dry cleaning.
Densified carbon dioxide provides a nontoxic, inexpensive, recyclable and
environmentally acceptable solvent to remove soils in the dry cleaning
process. The
supercritical carbon dioxide has been shown to be effective in removing
nonpolar stains such
as motor oil, when combined with a viscous cleaning solvent, particularly
mineral oil or
petrolatum as described in U.S. 5,279,615
The solvent power of densified carbon dioxide is low relative to ordinary
liquid
solvents and the carbon dioxide solvent alone is less effective on hydrophilic
stains such as
grape juice, coffee and tea and on compound hydrophobic stains such as
lipstick and candle
wax, unless surfactants and solvent modifiers are added.
A cleaning system combining particular anionic or nonionic surface active
agents with
supercritical fluid carbon dioxide is described in DE-A 39 04 514. These
anionic and nonionic
agents, such as alkylenebenzene sulfates and sulfonates, ethoxylated alkylene
phenols and
ethoxylated fatty alcohols, were particularly effective when combined with a
relatively large
amount of water (greater than or equal to 4%).
US 5,676,705 describes a method of dry cleaning fabrics comprising contacting
stained fabric with a dry cleaning system comprising densified carbon dioxide
and 0.001 % to
10% by weight of a surfactant compound which is soluble in the densified
carbon dioxide.
The examples of the US-patent disclose methods wherein the surfactants are
deemed to be
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fully dissolved during the actual dry cleaning operation. Furthermore these
surfactants are
liquid under the cleaning conditions employed in these methods.
US 5,858,022 relates to a method for dry cleaning articles in carbon dioxide,
comprising: contacting an article to be cleaned with a liquid dry cleaning
composition
comprising a mixture of carbon dioxide, water, surfactant and an organic co-
solvent; and then
separating the article from the liquid dry cleaning composition. The methods
described in the
examples utilise a cleaning composition in which the surfactants are fully
dissolved during the
cleaning operation.
US 6,200,352 describes a method of dry cleaning articles such as fabrics and
clothing
with the help of a liquid dry cleaning composition that comprises a mixture of
carbon dioxide,
a surfactant and an organic co-solvent. The preferred surfactant is one that
does not contain a
C02-philic group.
The dry cleaning systems using densified carbon dioxide known in the art
suffer from
the drawback that, although they may effectively be used to remove certain
types of stains,
they are incapable of effectively removing all sorts of stains including
nonpolar stains (e.g.
those made by a nonpolar organic component such as mineral oil, vegetable oil,
sebum etc.),
polar stains (e.g. grape juice, coffee and tea stains), compound hydrophobic
stains (e.g. stains
from lipstick and candle wax) as well as particulate soils (e.g. soils
containing insoluble solid
components such as silicates, carbon black etc.).
The present invention provides an improved dry cleaning method that utilises
densified carbon dioxide and a special surfactant which method offers the
advantage that it
can be used to effectively remove all sorts of stains from articles such as
fabrics.
SUMMARY OF THE INVENTION
The inventors have surprisingly discovered that in a method of dry cleaning
articles
with a densified carbon dioxide composition, the use of an ionic surfactant,
e.g. a surfactant
that contains a lipophilic alkyl residue and an amine, sulphate, phosphate
and/or carboxylate
residue, produces exceptionally good cleaning results if said surfactant is
employed in an
amount that exceeds its maximum solubility in the densified carbon dioxide
composition
under the conditions employed during the cleaning operation and provided said
surfactant is
present during the cleaning operation in the form of undissolved solid
particles. It was
unexpectedly found that the resulting presence of undissolved ionic surfactant
particles makes
it possible to effectively remove all sorts of stains, ie. polar, nonpolar,
compound stains and in
particular particulate soils.
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Although the inventors do not wish to be bound by theory it is believed that
the
exceptionally good results obtained with the present method are partly due to
the ability of the
ionic surfactant particles to manifest and retain an electrostatic surface
charge during the
washing operation, allowing these particles to capture and bind soil particles
until the
resulting aggregates are removed from the cleaned article together with the
densified carbon
dioxide composition. Thus, the presence of a significant amount of undissolved
ionic
surfactant particles reinforces the detergent effect of the densified carbon
dioxide and the
dissolved ionic surfactant.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly the present invention relates a method of dry cleaning an article
comprising the successive steps of.
a) contacting the article with a fluid dry cleaning composition containing
densified
carbon dioxide at a temperature between -20 and 60 C and a pressure between 1
and 100
MPa, so as to allow stains to dissolve and/or to disperse into the fluid dry
cleaning
composition and
b) separating the article and the fluid dry cleaning composition;
wherein the fluid dry cleaning composition comprises an ionic surfactant in a
concentration of
between 0.01 and 15% by weight of the carbon dioxide and wherein during step
a) at least
10%, preferably at least 30% of said ionic surfactant is present in an
undissolved solid form.
The term "ionic surfactant" as used herein refers to surfactants that are
either
positively charged (cationic surfactants), negatively charged (anionic
surfactants) or
zwitterions at the conditions applied in step a).
The teen "cleaning" as used herein refers to any removal of soil, dirt, grime,
or other
unwanted material, whether partial or complete. The present method may be used
to clean
nonpolar stains, polar stains, compound hydrophobic stains and particulate
soils. Examples of
articles that can suitably be cleaned by the method of the invention include
fabrics such as
woven and non-woven fabrics formed from materials such as cotton, wool, silk,
leather,
rayon, polyester, acetate, fiberglass, furs, etc. These fabrics may have been
formed into items
such as clothing, work gloves, rags, leather goods (e.g. handbags and brief
cases), etc. The
present method may also be used to clean non-fabric articles such as
semiconductors, micro
electromechanical devices, opto electronics, fiber optics and machined or
fabricated metal
parts.
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During the cleaning operation the undissolved surfactant is present in a solid
form,
especially in the form of solid particles. It is noted that the present method
also encompasses
the use of surfactants which are liquid at room temperature and atmospheric
pressure, but
which surfactants form solid particles prior to and/or during step a), e.g. as
a result of a
chemical or physical interaction with other components present in the cleaning
composition.
For instance, liquid amine surfactants may suitably be employed in the present
process as they
form solid particles during the cleaning operation, probably as a result of
the reaction with
carbon dioxide, resulting in the formation of a solid carbamate.
Examples of reactions that may occur between amine surfactants, carbon dioxide
and
other components of the fluid dry cleaning composition prior to and/or during
step a) and
which could lead to the formation of reaction products that will precipitate
as solid particles
include:
Protonation of the amines according to the following reactions [ 1-4] :
C02 + H2O < H2C03 (1)
H2CO3 + H2O <-> H30+ + HCO 3 (2)
R1R2NH + H3O+ < > R1R2NH 2 + H2O (3)
R3R4R5N + H3O+ <> R3R4R5NH+ + H2O (4)
in which R1R2NH is a primary or a secondary amine and R3R4R5N a tertiary
amine.
Primary and secondary amines can also react with carbon dioxide to form a
zwitterion [5]:
CO2 + R1R2NH < > R1R2NH+COO- (5)
This zwitterion is found in the isoelectric area. Above the isoelectric area,
the zwitterion can
be deprotonated by a base [6-8]:
R1R2NH+COO" + R1R2NH <> R1R2NCOO- + R1R2NH 2 (6)
R1R2NH+COO- + H2O <> R1R2NCOO- + H3O + (7)
R1R2NH+COO- + HC0 3 <-> R1R2NCOO- + H2C03 (8)
Below the isoelectric area of the zwitterion, the zwitterion can be protonated
according to the
following reaction [9]:
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R1R2NH+0007 + H30+ 4--> RIR2NH+000H + H2O (9)
In order to provide sufficient time to allow stains to dissolve and/or to
disperse into the
dry cleaning fluid it is preferred that the duration of step a) exceeds 1
minute, more preferably
2 minutes, and most preferably 5 minutes.
The results obtained with the present method are very dependent on the type of
ionic
surfactant used. Very good results are obtained with an ionic surfactant that
contains a
lipophilic, optionally heterogeneous hydrocarbyl residue with 3-25 carbon
atoms and one or
more groups selected from amine, phosphate, phosphonate, phosphinate,
phosphorite,
phosphene, phosphinite, phosphite, quaternary phosphonium salt, quaternary
ammonium salt,
sulphate, sulphonate, sulphinate, suiphenate, sulphide and carboxylate groups.
The
aforementioned (polar) groups maybe employed in protonated or salt form, e.g.
as salts with
monovalent cations such as sodium, potassium and ammonium, or as salts with
divalent
cations such as copper, magnesium, zinc and calcium.
Exceptionally good results can be achieved with an ionic surfactant that is
represented
by the formula R1X, XR1X, R2YR2,, R3Z(R3.)R3õ or R3E(R3=)(R3,,) R3...D
wherein:
R1 is a substituted or unsubstituted, linear or branched, optionally
heterogeneous C1-C22 alkyl;
a substituted or unsubstituted, optionally heterogeneous C3-C16 cycloalkyl; a
substituted or
unsubstituted, linear or branched, optionally heterogeneous C2-C22 alkenyl; or
a substituted or
unsubstituted, optionally heterogeneous aryl;
R2 and R2, independently are R1, X, RaX or Ra(X)2i
R3, R3,, R3,. and R3õ independently are R1, X, RaX, YRI, Ra('Ra)nYR1 or
Y(RaY)nRi;
Ra is a substituted or unsubstituted, linear or branched, optionally
heterogeneous C1-C22 alkyl;
a substituted or unsubstituted, optionally heterogeneous C3-C16 cycloalkyl; a
substituted or
unsubstituted, linear or branched, optionally heterogeneous C2-C22 alkenyl; or
a substituted or
unsubstituted, optionally heterogeneous aryl;
and wherein
X is NH2, NH3, OP(0)(0MI)(0M2), 0P(0)32 Q2+, P(0)(OMI)(OM2), P(0)32-Q2+,
P(O)(H)(OM1), OS(0)2(OMI), S(0)2(OM1), S(O)(OM1), COO- or COOMI;
Y is NH, NH2+, OP(O)(OM1)O, P(O)(OMI)O, P(0)(OM1), OS(0)20, S(0)20, S(0)0;
Z is N, NW;
EisN+;
D is F, Cl-, Br` or r;
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M1 and M2 independently represent sodium, potassium, ammonium or hydrogen;
Q2} represents Cat+, Cue+, Mg2+ or Zn2+; and
n = 0-20.
Particularly good results are obtained with the present invention if the ionic
surfactant
is represented by the formula R1X, XR1X, or R2YR2,, wherein X is NH2, NH3+,
COOM1,
COO-, OP(O)(OM1)(OM2), OS(O)2(OM1) and Y is NH. More preferably X is NH2
and/or
COOM1 and Y is NH.
In another preferred embodiment R1is a substituted or unsubstituted, linear or
branched, optionally heterogeneous C3-C22 alkyl, preferably C8-C22 alkyl or
are a substituted
or unsubstituted, linear or branched, optionally heterogeneous C3-C22 alkenyl,
preferably C8-
C22 alkenyl. Most preferably, R1 is an unsubstituted, linear or branched C3-
C22 alkyl,
preferably C8-C22 alkyl or are an unsubstituted, linear or branched C3-C22
alkenyl, preferably
C8-C22 allcenyl.
In case R2 or R2, represents Ra(X) it is preferred that the X-radical is
substituted to the
terminal carbon atom, i.e. the carbon atom farthest from Y or Z. Similarly, in
case R2 or R2>
represents Ra(X)2 it is preferred that both X-radicals are substituted to the
terminal carbon
atom. In an even more preferred embodiment in the formula Ra(X)2 one X
represents NH2 or
NH3+ and the other X represents COOM1 or COO".
In yet another preferred embodiment R. is a substituted or unsubstituted,
linear or
branched, optionally heterogeneous C3-C22 allcyl, preferably C8-C22 alkyl or
are a substituted
or unsubstituted, linear or branched, optionally heterogeneous C3-C22 alkenyl,
preferably C8-
C22 allcenyl. Most preferably, Ra is an unsubstituted, linear or branched C3-
C22 alkyl,
preferably C8-C22 alkyl or are an unsubstituted, linear or branched C3-C22
alkenyl, preferably
C8-C22 alkenyl.The liquid dry-cleaning compositions useful for carrying out
the present
invention typically include some water. The source of the water is not
critical in all
applications. The water may be added to the dry cleaning composition before
the articles to be
cleaned are deposited therein, it may be added during the cleaning operation
or it can be water
carried by or previously added to the garments, etc.
In one embodiment of the invention, better particulate cleaning may be
obtained in the
absence of water added to the dry-cleaning composition. There is inherently
water present on
or in the garments or articles to be cleaned as they are placed in the
cleaning vessel. The
presence of a certain amount of water in a fabric will result in a certain
swelling of the fabric
which is believed to make the fabric more easily accessible for the dry
cleaning composition.
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The improved accessibility facilitates the removal of stains (particularly oil
and fat stains) that
have penetrated into the interior of the fabric.
According to a preferred embodiment of the present method, the fluid dry
cleaning
composition contains less than 10 wt.% water. More preferably the composition
contains less
than 6 wt.% water. Even more preferably the water content of the dry cleaning
composition is
between 0.0001 and 5 wt.%, most preferably the water content is in the range
of 0.03-5 wt.%.
Here the water content relates to the total water content of the composition,
i.e. water that may
originate from different sources (e.g. the article) as described above.
In a preferred embodiment of the present method in addition to carbon dioxide
one or
more co-solvents are employed in the fluid dry cleaning mixture. Suitable
examples of such
co-solvents include aliphatic and aromatic hydrocarbons, and esters and ethers
thereof,
particularly mono and di-esters and ethers (e.g., EXXON ISOPAR L, ISOPAR M,
ISOPAR
V, EXXON EXXSOL, EXXON DF 2000, CONDEA VISTA LPA-170N, CONDEA VISTA
LPA-210, cyclohexanone, and dimethyl succinate), alkyl and dialkyl carbonates
(e.g.,
dimethyl carbonate, dibutyl carbonate, di-t-butyl dicarbonate, ethylene
carbonate, and
propylene carbonate), alkylene and polyalkylene glycols, and ethers and esters
thereof (e.g.,
ethylene glycol-n-butyl ether, diethylene glycol-n-butyl ethers, propylene
glycol methyl ether,
dipropylene glycol methyl ether, tripropylene glycol methyl ether, and
dipropylene glycol
methyl ether acetate), lactones (e.g., (gamma)butyrolactone,
(epsilon)caprolactone, and (delta)
dodecanolactone), alcohols and diols (2-methoxy-2-propanol, 1-octanol, 2-ethyl
hexanol,
cyclopentanol, 1,3 -propanediol, 2,3-butanediol, 2-methyl-2,4-pentanediol) and
polydimethylsiloxanes (e.g., decamethyltetrasiloxane, decamethylpentasiloxane,
and
hexainethyldisloxane), etc. Particularly suitable co-solvents include C1-C6
alcohols (e.g.,
methanol, ethanol, isopropanol, n-propanol), C1-C6 diols, methane, ethane,
propane, butane, n-
pentane, n-hexane, cyclohexane, n-heptane, ethylene, propylene, benzene,
toluene, p-xylene,
sulfur dioxide, chlorotrifluoromethane, trichlorofluoromethane,
perfluoropropane,
chlorodifluoromethane, sulfur hexafluoride and nitrous oxide. The preferred co-
solvent is a
C1-C6 alcohol or diol. More preferably the co-solvent is a C1-C5 alcohol. Most
preferably the
co-solvent is a C2-C4 alcohol.
The aforementioned co-solvents are advantageously employed in an amount of at
least
0.1 % by weight of the dry cleaning composition, more preferably in an amount
of 0.1-10 %
by weight.
As will be apparent to those skilled in the art, numerous additional
ingredients can be
included in the present fluid dry cleaning composition, including detergents,
bleaches,
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whiteners, softeners, sizing, starches, enzymes, hydrogen peroxide or a source
of hydrogen
peroxide, fragrances, etc.
The present method is suitably carried out at around room temperature. Hence,
in a
preferred embodiment the method comprises contacting the article with the
fluid dry cleaning
composition at a temperature between 0 and 30 C. Similarly, in a preferred
embodiment step
a) comprises contacting the article with the fluid dry cleaning composition at
a pressure
between 2 and 25 MPa.
In practice, in a preferred embodiment of the invention, the article to be
cleaned and
the fluid dry cleaning composition are combined in a closed drum. The liquid
dry cleaning
composition is preferably provided in an amount so that the closed drum
contains both a
liquid phase and a vapour phase (that is, so that the drum is not completely
filled with the
article and the liquid composition). The article is then agitated in the drum,
preferably so that
the article contacts both the liquid dry cleaning composition and the vapour
phase, with the
agitation carried out for a time sufficient to clean the article. The cleaned
article may
subsequently be removed from the drum.
The article may optionally be rinsed (for example, by removing the composition
from
the drum, adding a rinse solution such as liquid carbon dioxide (with or
without additional
ingredients such as water, co-solvent, etc.) to the drum, agitating the
article in the rinse
solution, removing the rinse solution, and repeating as desired), after the
agitating step and
before it is removed from the drum. The dry cleaning, compositions and the
rinse solutions
may be removed by any suitable means, including both draining, and venting.
In a particularly preferred embodiment of the invention, the present method
comprises
a rinsing step wherein the original dry cleaning composition is replaced by a
composition
containing densified carbon dioxide, and optionally other components, but no
undissolved
ionic surfactant. The latter composition may be used advantageously to remove
any remaining
undissolved surfactant. The rinsing operation with densified carbon dioxide
may suitably be
repeated several times. Preferably the densified carbon dioxide used in the
rinsing operation
contains a co-solvent as defined herein before and/or water, as such a co-
solvent may
facilitate the dissolving of the undissolved ionic surfactant and the water
may enhance the
removal of non-particulate soils.
Any suitable cleaning, apparatus may be employed, including both horizontal
drum
and vertical drum apparatus. When the drum is a horizontal drum, the agitating
step is carried
out by simply rotating the drum. When the drum is a vertical drum it typically
has an agitator
positioned therein, and the agitating step is carried out by moving, (e.g.,
rotating, or
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oscillating) the agitator within the drum. A vapour phase may be provided by
imparting
sufficient shear forces within the drum to produce cavitation in the liquid
dry-cleaning
composition.
Finally, in an alternate embodiment of the invention, agitation may be
imparted
by means of jet agitation as described in U. S. Pat. No. 5,467, 492 to Chao et
al. As
noted above, the fluid dry cleaning, composition is preferably an ambient
temperature
composition, and the agitating step is preferably carried out at ambient
temperature,
without the need for associating a heating, element with the cleaning
apparatus.
The invention is further illustrated by means of the following examples.
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EXAMPLES
Example 1
The experiment is carried out in a vessel of 25 litres with a rotating drum of
10 litres.
The vessel has two viewing glasses to monitor the behaviour of the fluid.
During the cleaning
and rinsing cycle the rotating drum is alternately rotated clockwise for 30
seconds and counter
clockwise for 30 seconds both at a speed of 75 cycles per minute. The dry-
cleaning fluid is
circulated over the vessel using a centrifugal pump. The piping from the
vessel towards the
pump contains a filter, while the piping from the pump towards the vessel
contains a heat
exchanger to control the temperature of the whole system. The equipment
contains a mass
flow meter, a temperature indicator and a pressure indicator.
During the cleaning cycle the rotating drum is filled with ten small pre-
stained test
fabrics. These stained test fabrics are:
STAIN FABRIC
1 sebum and carbon black wool
2 sebum and carbon black polyester
3 egg yolk wool
4 egg yolk polyester
butterfat with colorant cotton
6 butterfat with colorant polyester/cotton blend
7 vegetable oil with chlorophyll cotton
8 vegetable oil with chlorophyll polyester/cotton blend
9 clay wool
clay polyester
The test fabrics were attached to an additional load of 400 grams of white
cotton
fabrics. The stained test fabrics were analysed before and after the cleaning
cycle to determine
the coloration change of the fabrics. The values were expressed in Lab values.
The absolute
colour difference between two samples in the Lab space is expressed as:
AE = AL2 + Aa 2 + Ab 2
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To examine the efficiency of the cleaning, both the cleaned and stained
fabrics are
compared with the original unstained fabric, leading to the absolute colour
differences
AEstained-unsoiled and AEcleaned-unsoiled. The cleaning performance index of
an experiment is
expressed as:
CPILab = 1- cleaned-unsoiled x100%
stained-unsoiled
When the fabric is clean the CPIIab value is 100%, when the cleaning has no
effect the value is
0%.
The cleaning is started by filling the vessel at ambient conditions with the
additional
load and the attached stained test fabrics. Subsequently a cleaning fluid
comprising of 250
grams of iso-propanol, 25 grams water and 39 grams of dissolved dodecylamine,
was added
to the fabric load. The vessel was closed and pressurised with 6 kg of liquid
carbon dioxide
from a storage tank. The system reached a pressure of 48 bars and a
temperature of 12 C.
Through the viewing glasses it was observed that a large amount of small
particles is formed.
The particles were collected and analysed. It was found that the material in
the particles
displayed a melting point that was about 20 C higher than the melting point of
dodecylamine.
The rotating drum was started and the fabric is cleaned for 30 minutes. After
the
cleaning the vessel was rinsed with 12 kg of fresh carbon dioxide from the
storage vessel for
minutes, while keeping the system at 48 bars. Subsequently the vessel was
depressurised
after which it was opened, the cleaned fabrics were taken out and the colour
differences were
measured. The CPIIab values obtained are shown in the table below.
Example 2
Example 1 was repeated except that the cleaning fluid was composed of 250
grams
iso-propanol, 25 grams water and 40 grams of dioctylamine. The vessel was
closed and
pressurised with 6 kg of liquid carbon dioxide from a storage tank. The system
reached a
pressure of 48 bars and a temperature of 12 C. Through the viewing glass it
was observed
that a large amount of small particles was formed. After the cleaning, the
vessel was rinsed
and depressurised as described in example 1. The CPIIab values found for each
of the test
fabrics are shown in the table below.
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Example 3
Example 1 was repeated except that this time 50 grams of solid sodium stearate
and 25
grams of water were put in the cleaning vessel. The vessel was closed and
pressurised with 4
kg of liquid carbon dioxide from a storage tank. The system reached a pressure
of 46 bars and
a temperature of 10 C. Through the viewing glass it was observed that a large
amount of
sodium stearate did not dissolve in the carbon dioxide. After the cleaning,
the vessel was
rinsed and depressurised as described in example 1. The CPllab values found
for each of the
test fabrics are shown in the table below.
Example 4
Example 1 was repeated except that this time 10 grams of solid sodium dodecyl
sulfate
and 25 grams of water were put in the cleaning vessel. The vessel was closed
and pressurised
with 6 kg of liquid carbon dioxide from a storage tank. The system reached a
pressure of 46
bars and a temperature of 11 C. Through the viewing glass it was observed
that a large
amount of sodium dodecyl sulfate did not dissolve in the carbon dioxide. After
the cleaning,
the vessel was rinsed and depressurised as described in example 1. The CPIIab
values found
for each of the test fabrics are shown in the table below.
Example 5
Example 1 was repeated except that the cleaning fluid was composed of 250
grams of
iso-propanol, 25 grams water and 1 gram of tribenzylamine. The vessel was
closed and
pressurised with 6 kg of liquid carbon dioxide from a storage tank. The system
reached a
pressure of 45 bars and a temperature of 10 C. Through the viewing glass it
was observed
that a large amount of small particles was formed. After the cleaning, the
vessel was rinsed
and depressurised as described in example 1. The CPIIab values found for each
of the test
fabrics are shown in the table below.
Example 6
Example 1 was repeated except that the cleaning fluid was composed of 255
grams of
iso-propanol, 25 grams water and 1 gram of octadecylamine. The vessel was
closed and
pressurised with 6 kg of liquid carbon dioxide from a storage tank. The system
reached a
pressure of 48 bars and a temperature of 12 C. Through the viewing glass it
was observed
that small particles were formed. After the cleaning, the vessel was rinsed
and depressurised
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as described in example 1. The CPIIab values found for each of the test
fabrics are shown in
the table below.
Example 7
Example 6 was repeated except that the cleaning fluid was composed of 251
grams of
iso-propanol, 25 grams water and 5 grams of octadecylamine. The vessel was
closed and
pressurised with 6 kg of liquid carbon dioxide from a storage tank. The system
reached a
pressure of 46 bars and a temperature of 11 C. Through the viewing glass it
was observed
that small particles were formed. After the cleaning, the vessel was rinsed
and depressurised
as described in example 1. The CPIIab values found for each of the test
fabrics are shown in
the table below.
Example 8
Example 6 was repeated except that the cleaning fluid was composed of 250
grams of
iso-propanol, 25 grams water and 10 grams of octadecylamine. The vessel was
closed and
pressurised with 6 kg of liquid carbon dioxide from a storage tank. The system
reached a
pressure of 48 bars and a temperature of 12 C. Through the viewing glass it
was observed
that a substantial amount of small particles was formed. After the cleaning,
the vessel was
rinsed and depressurised as described in example 1. The CPIIab values found
for each of the
test fabrics are shown in the table below.
Example 9
Example 6 was repeated except that the cleaning fluid was composed of 250
grams of
iso-propanol, 30 grams water and 40 grams of octadecylamine. The vessel was
closed and
pressurised with 6 kg of liquid carbon dioxide from a storage tank. The system
reached a
pressure of 46 bars and a temperature of 11 C. Through the viewing glass it
was observed
that a large amount of small particles was formed. After the cleaning, the
vessel was rinsed
and depressurised as described in example 1. The CPIIab values found for each
of the test
fabrics are shown in the table below.
Exam l~e10
Example 1 was repeated except that the cleaning fluid was composed of 250
grams of
iso-propanol and 10 grams of N-Lauroyl-L-lysine. The vessel was closed and
pressurised with
6 kg of liquid carbon dioxide from a storage tank. The system reached a
pressure of 57 bars
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WO 03/062520 PCT/NL02/00788
and a temperature of 20 C. Through the viewing glass it was observed that a
large amount of
small particles was formed. After the cleaning, the vessel was rinsed and
depressurised as
described in Example 1. The CPIIab values found for each of the test fabrics
are shown in the
table below.
Example 11
Example 1 was repeated except that the cleaning fluid was composed of 250
grams of iso-
propanol and 5 grams of N-Lauroyl-L-lysine. The vessel was closed and
pressurised with 6 kg
of liquid carbon dioxide from a storage tank. The system reached a pressure of
52 bars and a
temperature of 16 C. Through the viewing glass it was observed that a large
amount of small
particles was formed. After the cleaning, the vessel was rinsed with pure
carbon dioxide and
depressurised as described in Example 1. Subsequently a rinsing fluid
comprising of 250
grams of iso-propanol and 25 grams water was added to the fabric load. The
vessel was
closed and pressurised with 6 kg of liquid carbon dioxide from a storage tank.
The rotating
drum was started and the fabric was rinsed for 30 minutes. After this rinsing
step, the vessel
was rinsed again with pure carbon dioxide and depressurised as described in
Example 1.
Comparative example A
Example 1 was repeated except that no cleaning liquid was put in the vessel.
The
vessel was closed and pressured with 12 kg of liquid carbon dioxide from a
storage tank. The
system reached a pressure of 45 bars and a temperature of 10 C. After the
cleaning, the
vessel was rinsed and depressurised as described in example 1. The CPIIab
values found for
each of the test fabrics are shown in the table below.
The cleaning performance (expressed as CPIIab values) achieved in each of the
cleaning cycles
described in the aforementioned examples is summarised in the following table:
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EXAMPLES
1 2 3 4 5 6 7 8 9 10 11 A
Sebum on wool 74 76 63 58 44 55 57 79 89 71 72 30
Sebum on polyester 46 44 44 40 23 36 42 48 58 49 56 21
Egg-yolk on wool 64 62 46 47 56 60 60 62 64 44 56 41
gg-yolk on polyester 50 55 40 38 49 51 48 49 53 40 39 37
Butterfat on cotton 80 90 72 62 88 84 86 86 84 75 91 65
Butterfat on blend fabric 87 93 83 76 92 89 89 90 87 83 94 80
Vegetable oil on cotton 57 67 41 27 64 55 51 61 65 49 54 16
Vegetable oil on blend 20 20 27 19 26 22 15 24 23 22 20 6
fabric
Clay on wool 68 62 52 66 32 43 35 44 47 71 83 13
A
Clay on polyester 12 11 27 39 2 13 9 2 12 16 17 1
The above results show that the addition of an ionic surfactant dramatically
improves the
cleaning performance. The examples 1, 2, 3, 4, 5, 9,10 and 11 illustrate that
the benefits of the
present invention may be obtained with different types of ionic surfactants,
even though the
improved cleaning performance may manifest itself in different ways. The
results also shown
that the amines are particularly effective. The examples 6, 7, 8 and 9 show
that an increase of
the concentration of the surfactant increases the cleaning performance of the
washing cycle.
This is a surprising finding since the applied amount of dissolved surfactant
is the same in all
these samples. All examples show that especially the removal of particulate
soils is improved
dramatically.
