Note: Descriptions are shown in the official language in which they were submitted.
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LAUNDRY BLEACHING WITH IMPROVED SAFETY TO FABRICS
Technical Field
The present invention relates to the bleaching of fabrics.
Background
Peroxygen bleach-containing compositions have been described in laundryapplications as laundry detergents, laundry additives or even laundry
pretreaters.
Indeed, it is known to use peroxygen bleach-containing compositions in
laundry treatment applications to boost the removal of encrustated
stains/soils which are otherwise particularly difficult to remove, such as
grease, coffee, tea, grass, mud/clay-containing soils and the like. However,
we have found that a drawback associated with such peroxygen bleach-
containing compositions is that said compositions may damage fabrics,
resulting in loss of tensile strength, especially when used in pretreatment
application, i.e. when applied directly (neat) onto the fabrics, and left to actonto said fabrics for prolonged periods of time before washing the fabrics.
It is thus an object of the present invention to provide improved fabric safety
upon bleaching, especially in pretreatment applications where the
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compositions are left neat into contact with the fabrics for prolonged periods
of time before washing.
Indeed, when bleaching fabrics with a composition comprising a peroxygen
bleach like hydrogen peroxide, it has been found that the presence of metal
ions such as copper andlor iron and/or manganese andtor chromium on the
surface of the fabrics and/or the exposure to UV radiation from sunlight of
the fabrics after having been contacted with the peroxygen bleach-containing
composition, produces fabric damage resulting in loss of tensile strength of
the fabric fibres. Indeed, it is speculated that the presence of metal ions suchas copper and/or iron and/or manganese and/or chromium on the surface of
the fabrics, especially on cellulosic fibres, and/or the exposure of the fabricsto UV radiation from sunlight catalyses the radical decomposition of
peroxygen bleaches like hydrogen peroxide. Thus, it is believed that a radical
reaction occurs on the surface of the fabric with generation of free radicals,
which results in loss of tensile strength.
It has now been found that improved fabric safety can be achieved by
formulating a bleaching composition where hydrogen peroxide is substituted
by selected hydroperoxides as the bleaching agent, or mixtures thereof.
US 5,284,597 discloses a composition for treating soft surfaces, essentially
carpets, which comprise amongst other things tertiary alkyl hydroperoxide.
The compositions are said to be safer to colors.
US 3,574,519 discloses the bleaching of textiles where the bleaching agent
is an organic hydroperoxide. Organic hydroperoxides are said to be
economically attractive. '519 does not discuss the problem of safety to
f abrics.
BE 831.277 discloses the bleaching of textiles with the help of a mixtures of
bleach activators, one of which being from the class of triazine
hydroperoxides. Triazine hydroperoxides are said to be potentially damaging
to the colors of fabrics. '277 does not discuss the problem of safety to
fabrics.
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US 3,753,915 discloses the bleaching of fabrics with a granular composition
comprising salts of hydroperoxides. '915 does not discuss the problem of
safety to fabrics.
Summarv of the invention
In its broadest embodiment, the present invention encompasses the use of
hydroperoxides for the bleaching of fabrics, for reducing the loss of tensile
strength in said fabrics.
The present invention further encompasses processes of bleaching fabrics,
starting from a liquid composition comprising a hydroperoxide. The
processes include the steps of contacting said fabrics with the liquid
bleaching composition neat or diluted, and subsequently rinsing said fabrics.
In the preferred embodiment, when the fabrics are "pretreated", the
composition is applied neat on the fabrics, and the fabrics are subsequently
washed in a normal wash cycle.
Detailed descriPtion of the invention
In its broadest embodiment, the present invention encompasses the use of a
hydroperoxide as a bleaching agent in a process of bleaching fabrics for
reducing the loss of tensile strength in said fabrics.
In other words, the present invention is based on the finding that fabric
damage resulting in tensile strength loss is reduced, when a composition
comprising a hydroperoxide, or mixtures thereof, is used to bleach fabrics, as
compared to the same composition where hydrogen peroxide is used instead
of hydroperoxide.
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It is speculated that reduced fabric damage observed herein is due to the
much lower reactivity of free radicals generated from hydroperoxides vs.
those generated from hydrogen peroxide.
In addition, it is speculated that with hydroperoxides, there is a lower
dependence of fabric damage from heavy metal pollution, probably because
the formation of a complex between the metal and the peroxide molecule is
more difficult than with hydrogen peroxide.
The tensile strength in a fabric may be measured by stretching said fabric
until it breaks. The force needed to break the fabric is the "Ultimate Tensile
Stress" and may be measured with a stress-strain INSTRON ~ machine
available from INSTRON. The loss of tensile strength is the difference
between the tensile strength of a fabric taken as a reference, i.e. a fabric
which has not been bleached, and the tensile strength of the same fabric
after having been bleached. A tensile strength loss of zero means that no
fabric damage is observed.
As a first essential element, the liquid compositions suitable to be used
according to the present invention comprise a hydroperoxide, or mixtures
thereof, as the bleaching agent. Suitable hydroperoxides for use herein
include alkyl hydroperoxides and organomineral hydroperoxides.
Suitable alkyl hydroperoxides for use herein are according to the formula
Rl
R2 C--O--O--H
~3
in which each R 1, R2 and R3 is, independently, a hydrogen atom or a
hydrocarbon radical having from 1 to 30 carbon atoms. The hydrocarbon
radical can be a linear or a cyclic hydrocarbon chain, and the linear and the
cyclic hydrocarbon chain can be straight or branched, saturated or
unsaturated. Also, two of the R groups can be part of the same cyclic
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hydrocarbon. One or more R groups in the above formula can be a single or
condensed aromatic radical, alkyl-aryl radical or cycloalkyl-aryl radical.
All the above R radicals can also be substituted by heteroatoms or group of
heteroatoms, such as hydroperoxide (-OOH) groups, halogen atoms, hydroxy
groups, nitrates, suphonyls, nitro groups, ethers, carboxylic groups and
esters. All these groups can also be present as substituents of one or more
positions of the R radicals.
Preferred alkyl hydroperoxides for use herein are tert-butyl hydroperoxide,
cumyl hydroperoxide, 2,4,4-trimethylpentyl-2-hydroperoxide, di-
isopropylbenzene-monohydroperoxide, tert-amyl hydroperoxide and 2,5-
dimethyl-hexane-2, 5-dihydroperoxide .
Suitable organomineral hydroperoxides for use herein are according to the
formula
RmM(OOH)n
where M is a metal atom like Si, Sn, Ge or Sb and R is a radical defined as
R1, R2, R3 above. Preferred organomineral hydroperoxides for use herein are
(CH3)3SiOOH, (C6Hs)2CH3SiOOH, (C6Hs)3SiOOH, (n-C6H1 3)3SiOOH~
(CH3)3SnOOH, (C6Hs)3Sb(OOH)2. Most preferred for use herein are
(CH3)3SiOOH, (C6Hs)3SiOOH.
Typically, the compositions herein comprise from 0.01% to 5.0%, preferably
0.015% to 4.0%, most preferably from 0.02% to 2.0% of available oxygen
provided by said hydroperoxide.
The compositions to be used according to the present invention must be
liquids. As used herein, "liquid" includes "pasty" compositions, and liquid
compositions herein preferably have a viscosity of from 5 cps to 10000 cps at
60 rpm shear rate and at 20~c temperature.
Preferably, the compositions to be used herein are aqueous. Said aqueous
compositions have a pH as is of from 2 to 1 1, preferably from 3 to 10 and
more preferably from 3.5 to 9.5 when optimum chemical stability for the
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hydroperoxides has been observed. The pH of the compositions can be
adjusted for instance by using organic or inorganic acids, or alkalinizing
agents.
The compositions used in the present invention may further comprise anysurfactant including nonionic, anionic, cationic, zwitterionic and/or
amphothereic surfactants.
Accordingly, the compositions used in the present invention preferably further
comprise a nonionic surfactant, or mixtures thereof. Typically, the
compositions used in the present invention comprise from 0.1% to 50% by
weight of the total composition of said nonionic surfactant, or mixtures
thereof, preferably from 0.3 % to 30 % and more preferably from 0.4 % to
25 %.
Suitable nonionic surfactants to be used herein are fatty alcohol ethoxylates
and/or propoxylates which are commercially available with a variety of fatty
alcohol chain lengths and a variety of ethoxylation degrees. Indeed, the HLB
values of such alkoxylated nonionic surfactants depend essentially on the
chain length of the fatty alcohol, the nature of the alkoxylation and the
degree of alkoxylation. Surfactant catalogues are available which list a
number of surfactants, including nonionics, together with their respective
HLB values.
Suitable chemical processes for preparing the nonionic surfactants for use
herein include condensation of corresponding alcohois with alkylene oxide, in
the desired proportions. Such processes are well known to the man skilled
in the art and have been extensively described in the art. As an alternative,
a great variety of alkoxylated alcohols suitable for use herein is commercially
available from various suppliers.
Particularly suitable to be used herein as nonionic surfactants are
hydrophobic nonionic surfactants having an HLB (hydrophilic-lipophilic
balance) below 16, preferably below 15, more preferably below 12, and
most preferably below 10. Those hydrophobic nonionic surfactants have
been found to provide good grease cutting properties.
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Preferred hydrophobic nonionic surfactants to be used in the compositions
according to the present invention are surfactants having an HLB beiow 16
and being according to the formula RO-~C2H40)n(C3H60)mH, wherein R is
a C6 to C22 alkyl chain or a C6 to C2g alkyl benzene chain, and wherein
n~m is from O to 20 and n is from O to 15 and m is from O to 20,
preferably n+m is from 1 to 15 and, n and m are from 0.5 to 1~, more
preferably n+m is from 1 to 10 and, n and m are from O to 10. The
preferred R chains for use herein are the Cg to C22 alkyl chains. Accordingly
suitable hydrophobic nonionic surfactants for use herein are Dobanol R 91-
2.5 (HLB= 8.1; R is a mixture of C9 and C1 1 alkyl chains, n is 2.5 and m is
0), or Lutensol R T03 (HLB=8; R is a C13 alkyl chains, n is 3 and m is 0),
or Lutensol R A03 (HLB=8; R is a mixture of C13 and C1s alkyl chains, n
is 3 and m is 0), or Tergitol R 25L3 (HLB= 7.7; R is in the range of C12 to
C1s alkyl chain length, n is 3 and m is 0), or Dobanol R 23-3 (HLB=8.1; R
is a mixture of C12 and C13 alkyl chains, n is 3 and m is 0), or Dobanol R
23-2 (HLB=6.2; R is a mixture of C12 and C13 alkyl chains, n is 2 and m is
0), or Dobanol R 45-7 (HLB=11.6; R is a mixture of C14 and C1s alkyl
chains, n is 7 and m is 0) Dobanol R 23-6.5 (HLB=11.9; R is a mixture of
C12 and C1 3 alkyl chains, n is 6.5 and m is 0), or Dobanol R 25-7
(HLB=12; R is a mixture of C12 and C1s alkyl chains, n is 7 and m is 0),
or Dobanol R 91-5 (HLB= 11.6; R is a mixture of Cg and C1 1 alkyl chains, n
is 5 and m is 0), or Dobanol R 91-6 (HLB=12.5; R is a mixture of Cg and
C11 alkyl chains, n is 6 and m is 0), or Dobanol R 91-8 (HLB= 13.7; R is a
mixture of Cg and C1 1 alkyl chains, n is 8 and m is 0), Dobanol R 91 10
(HLB=14.2; R is a mixture of Cg to C11 alkyl chains, n is 10 and m is 0),
or mixtures thereof. Preferred herein are Dobanol R 91-2.5, or Lutensol R
T03, or Lutensol R A03, or Tergitol R 25L3, or Dobanol R 23-3, or
Dobanol R 23-2, or mixtures thereof. These DobanolR surfactants are
commercially available from SHELL. These LutensolR surfactants are
commercially available from BASF and these Tergitol R surfactants are
commercially available from UNION CARBIDE.
Preferred compositions to be used herein further comprise an anionic
surfactant, or mixtures thereof. Said anionic surfactants act as wetting
agent, i.e. in laundry application they wet the stains on the fabrics,
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especially on hydrophilic fabrics, and thus help the hydroperoxide perform its
bleaching action thereby contributing to improved laundry performance on
bleachable stains. Furthermore, anionic surfactants allow to obtain clear
compositions even when said compositions comprise hydrophobic ingredients
such as hydrophobic surfactants. Typically, the compositions to be used
herein comprise from 0.1 % to 20 % by weight of the total composition of
said anionic surfactant, or mixtures thereof, preferably from 0.2 % to 15 %
and more preferably f rom 0. 5 % to ~ 3 %
Particularly suitable for use herein are sulfonate and sulfate surfactants. The
like anionic surfactants are well-known in the art and have found wide
application in commercial detergents. These anionic surfactants include the
C8-C22 alkyl benzene sulfonates (LAS~, the C8-C22 alkyl sulfates (AS),
unsaturated sulfates such as oleyl sulfate, the C10-C18 alkyl alkoxy sulfates
(AES~ and the C10-C18 alkyl alkoxy carboxylates. The neutralising cation for
the anionic synthetic sulfonates and/or sulfates is represented by conventional
cations which are widely used in detergent technology such as sodium,
potassium or alkanolammonium. Preferred herein are the alkyl sulphate,
especially coconut alkyl sulphate having from 6 to 18 carbon atoms in the
alkyl chain, preferably from 8 to 15, or mixtures thereof.
The compositions for use herein may further comprise a foam suppressor
such as 2-alkyl alkanol, or mixtures thereof, as a highly preferred optional
ingredient. Particularly suitable to be used in the present invention are the 2-alkyl alkanols having an alkyl chain comprising from 6 to 16 carbon atoms,
preferably from 8 to 12 and a terminal hydroxy group, said alkyl chain being
substituted in the a position by an alkyl chain comprising from 1 to 10
carbon atoms, preferably from 2 to 8 and more preferably 3 to 6. Such
suitable compounds are commercially available, for instance, in the Isofol~
series such as Isofol~ 12 (2-butyl octanol) or Isofol(~ 16 ~2-hexyl decanol).
Typically, the compositions suitable to be used herein comprise from 0.05 %
to 2 % by weight of the total composition of a 2-alkyl alkanol, or mixtures
thereof, preferably from 0.1 % to 1.5 % and most preferably from 0.1 % to
0.8 %.
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The compositions herein may further comprise a variety of other optional
ingredients such as builders, stabilisers, chelants, soil suspenders, dye
transfer agents, radical scavengers, solvents, brighteners, perfumes, and
dyes.
In the present invention, the liquid bleaching composition comprising the
hydroperoxide needs to be contacted with the fabrics to be bleached. This
can be done either in a so-called "pretreatment mode", where the
composition is applied neat onto said fabrics before the fabrics are rinsed, or
washed then rinsed, or in a "soaking mode" where the liquid composition is
first diluted in an aqueous bath and the fabrics are immersed and soaked in
the bath, before they are rinsed, or in a "through the wash mode", where the
liquid composition is added on top of a wash liquor formed by dissolution or
dispersion of a typical laundry detergent. As discussed earlier, the
composition to perform the processes herein is in the form of a liquid as
opposed to a solid or a gas.
It is also essential in both cases, that the fabrics be rinsed after they have
been contacted with said composition, before said composition has
completely dried off.
Indeed, it has been found that water evaporation contributes to increase the
concentration of free radicals onto the surface of the fabrics and,
consequently, the rate of chain reaction. It is also speculated that an auto-
oxidation reaction occurs upon evaporation of water when the liquid
compositions are left to dry onto the fabrics. Said reaction of auto-oxidation
generates peroxy-radicals which may contribute to the degradation of
cellulose. Thus, not leaving the liquid compositions, as described herein, to
dry onto the fabric, in a process of pretreating soiled fabrics, contributes to
the benefits according the present invention, i. e. to reduce the tensile
strength loss when pretreating fabrics with liquid peroxygen bleach-
containing compositions.
In the pretreatment mode, the process comprises the steps of applying said
liquid composition in its neat form onto said fabrics, or at least soiled portions
thereof, and subsequently rinsing, or washing then rinsing said fabrics. In
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this mode, the neat compositions can optionally be left to act onto said
fabrics for a period of time ranging from 1 min. to 1 hour, before the fabrics
are rinsed, or washed then rinsed, provided that the composition is not left to
dry onto said fabrics. For particularly though stains, it may be appropriate to
further rub or brush said fabrics by means of a sponge or a brush, or by
rubbing two pieces of fabrics against each other.
In another mode, generally referred to as "soaking", the process comprises
the steps of diluting said liquid composition in its neat form in an aqueous
bath so as to form a diluted composition, i.e., a composition comprising from
0.0001% to 0.2%, preferably 0.0002% to 0.02% of available oxygen
provided by said hydroperoxide. The fabrics are then contacted with the
aqueous bath comprising the liquid composition, and the fabrics are finally
rinsed, or washed then rinsed. Preferably in that embodiment, the fabrics are
immersed in the aqueous bath comprising the liquid composition, and also
preferably, the fabrics are left to soak therein for a period of time ranging
from 30 minutes to 48 hours, preferably from 1 hour to 24 hours.
In yet another mode which can be considered as a sub-embodiment of
"soaking", generally referred to as "bleaching through the wash", the liquid
composition is used as a so-called laundry additive. And in that embodiment
the aqueous bath is formed by dissolving or dispersing a conventional laundry
detergent in water. The liquid composition in its neat form is contacted with
the aqueous bath, and the fabrics are then contacted with the aqueous bath
containing the liquid composition. Finally, the fabrics are rinsed.
Depending on the end-use envisioned, the compositions herein can be
packaged in a variety of containers including conventional bottles, bottles
equipped with roll-on, sponge, brusher or sprayers, or sprayers.
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11
The invention is further illustrated by the following examples.
Examoles
ExamPle 1
A liquid composition is prepared which comprises:
Cumyl Hydroperoxide 10%
Dobanol 23.3 8.6%
Dobanol 45.7 6.4%
C 1 2 Alkyl Sulf ate 2 %
Water and minors up to 1 00%
pH = 4, trimmed with Sulphuric acid
In a pretreatment mode, this composition is applied neat on the stainedportion of a fabric and left to act thereon for 5 minutes. Then the fabric is
washed with a conventional detergent and rinsed.
ExamDle 2
The following liquid composition is prepared:
tert-Butyl Hydroperoxide 10%
Dobanol 45.7 6.0%
Dobanol 23.6,5 6.0%
C25-AE2.5-S ~ethoxylated alkyl sulfate) 6.0%
Water and minors up to 1 00%
pH=4, trimmed with Sulphuric acid
In a bleaching-through-the-wash mode, this composition is contacted with an
aqueous bath formed by dissolution of a conventional detergent in water.
Fabrics are then contacted with the aqueous bath comprising the liquid
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detergent, and the fabrics are rinsed. This composition can also be used in a
pretreatment mode, where it is poured neat on the stains on the fabrics, and
left to act for 5 minutes, and the fabrics are washed.
ExamDle 3
The following liquid composition is prepared:
tert-Butyl Hydroperoxide 5%
Dobanol 91.10 1.6%
Dobanol 23.3 1.5%
C 10 AS 1 .7%
Isofol 12@) 0.5%
Water and minors up to 100%
pH=4, trimmed with Sulphuric acid
This composition can be used in a pretreatment mode, or in a bleaching-through-the-wash mode, as described in examples 1 and 2. It can also be
used in a soaking mode, where 100 ml of the liquid compositions are diluted
in 10 liters of water. The fabrics are then contacted with this aqueous bath
containing the composition, and left to soak therein for a period of time of 24
hours. The fabrics are eventually rinsed.
ExamDle 4
A liquid detergent composition is prepared as follows:
Cumyl Hydroperoxide 10%
Dobanol 23.3 8.6%
Dobanol 45.7 6.4%
C 1 2 AS 2%
Water and minors up to 100%
pH = 6, trimmed with Sulphuric acid
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13
This composition is used in a pretreatment mode, as described in the
examples above.
ExamDle 5
The following liquid composition is made:
2, 5-dimethyl-hexane-2, 5-dihydroperoxide 5 %
Dobanol 23.3 8.6%
Dobanol 45.7 6.4%
C25-2.5EO-S 2%
Water and minors up to 100%
pH = 5, trimmed with Sulphuric acid
This composition is used in a pretreatment mode as described in the previous
examples.
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