The present invention relates to the use of cleaning and
antibacterial hygienizing compositions to be preferably applied,
as laundry pretreat, or prewash, directly on stains
before laundering by-hand or in domestic washing machine. The
compositions of the present invention, are particularly
suitable for stain removal on wool, silk and other delicate or
coloured fabrics.
It is known in the art that the removal of the
bleachable stains (for instance tea, coffee, red wine,
coloured fruits such as plums or bilberries, grass) and
disinfection and hygiene of fabrics, in domestic laundering
by-hand or in washing machine, are difficult tasks requiring
the use of bleaching additives, either alone or in combination
with laundry detergents. The task is particularly difficult in
the case of stains on coloured and delicate fabrics because
delicates need to be washed at warm temperatures (usually not
above 30°C) and in slightly acid to slightly basic solutions,
i.e. under very mild conditions to avoid fabric damage and
similarly for coloured fabrics lower washing temperature are
needed to reduce the colour damage. Unfortunately the milder
the conditions, the lower the stain removal and disinfection
efficacy. On the contrary, when the fabrics can be washed at
high temperatures (at or above 60°C), the use of any bleaching
additives gives poor improvements because of the good
efficiency given by detergents themselves.
It is well established the use of chlorine based
bleaching agents: they are very effective, but can be used
only on white or few resistant colours and on alkaline- and
chlorine-resistant fabrics, such as cotton and some
synthetics, but cannot be used on delicates and most coloured
fabrics.
Another bleaching system, widely used in powder heavy
duty laundry detergents, is based on solid carriers or precursors
of active oxygen, for instance persalts as perborates,
percarbonates, and/or on percarboxylic acids, generated in
situ in the washing solution by reaction of their precursors,
known as activators, with hydrogen peroxide; amongst them the
most used activator in Europe is TAED. Even if less alkaline
and less aggressive than chlorine base bleach towards colours
and fabrics, the above mentioned solid oxygen based bleaching
systems cannot be used on delicate fabrics and are not fully
satisfactory on coloured ones. Furthermore, they cannot be
used directly on stains, but only in solution, i.e. in a more
or less diluted, and therefore less active, form.
It is also known the use of liquid additives, containing
hydrogen peroxide: they can be either directly applied on
stains and soiled fabrics before washing or added into the
laundry machine or laundry solution. Examples of such compositions
commercialised in Italy are: OMINO BIANCO CANDEGGINA
DELICATA®, ACE GENTILE®, in Spain: NEUTREX®, in Greece:
KLINEX®, SENSO®, in France: BLANCO®, VANISH®, ACE DESICAT®,
in Germany: SIL®, ACE MILDE BLEACH®. The hereabove mentioned
bleach products are fully compatible with coloured and
delicate fabrics, but they are much less effective than the
above mentioned other bleaching systems.
The need was therefore felt to find out cleaning and hygienizing
liquid additives to be directly applied on the stains
both in resistant articles at high temperatures, and on
delicate and coloured articles, at room and/or low
temperatures, able to produce an effective bleaching action
without halos, with a wide applicability range, overcoming the
drawbacks of the products of similar use commercially
existing.
The Applicant has surprisingly and unexpectedly found
that the liquid compositions of the invention to be directly
applied on the stains before washing, lead to improved cleaning
and hygienizing results.
It is therefore an object of the present invention the
use of aqueous liquid compositions, comprising a percarboxylic
acid, as stain removing, a pre-treating, cleaning and
antibacterial additives very effective at low temperatures,
for by-hand or washing machine laundry, both for delicate
and/or coloured fabrics. They can be preferably applied
directly on the stains before washing, which allows to obtain,
washing at room or at low temperature (20-30°C), either much
higher disinfecting and stain removing results, than the ones
given by the above-mentioned existing liquid additives under
the same conditions or the same results given by the above-mentioned
existing liquid additives at higher temperatures, so
achieving the important goal of a minor colour and fabric damage.
Specifically the aqueous liquid compositions of the present
invention to be directly applied on the stains, comprise:
- percarboxylic acid;
- one or more surfactants;
- hydrogen peroxide;
- one or more optional minor components preferably
selected from: dyes, perfumes, viscosity thickeners, solvents,
hydrotropic agents, suspending agents, antiredeposition
agents, optical brighteners, antifoam, opacifying,
sequestering agents, dye transfer inhibitors, pH modifiers.
The percarboxylic acid used to prepare the liquid composition
is a crystalline solid, having generally sizes in the
range 0.1 ÷ 1000 µm, more preferably in the range 1 ÷
200 µm, even more preferably in the range 5 ÷ 100 µm, only
slightly soluble in acid environment but readily soluble in
alkaline or weakly alkaline environment, highly stable as a
solid also in aqueous suspension as well as a liquid composition.
In the invention compositions the percarboxylic acid is
present in a percentage in the range 0.5÷20.0% by weight, more
preferably 2.0÷10.0% by weight. Preferably the percarboxylic
acid is an amido- or imido-percarboxylic acid, more preferably
the ε-N,N-phthaloyl-amino-peroxycaproic acid or ε-phthalimido-peroxycaproic
acid, named PAP.
Therefore the invention compositions appear either in the
form of either a solution or suspension depending on the solution
pH. Preferably the compositions of the invention have
acid pH whereby they appears as suspension.
The surfactant is present in the range 1.0%÷25.0% by weight,
preferably in the range 3.0%÷15.0% by weight. Preferably
the surfactants are selected from the anionic and the nonionic
ones. Preferably a mixture of surfactants comprising at least
an anionic surfactant and at least a nonionic surfactant is
used.
Among the anionic surfactants sodium, potassium,
ammonium salts, preferably sodium or potassium salts
alkylbenzenesulphonates acid are preferred, wherein alkyl is
preferably a linear or branched aliphatic chain, preferably
linear, or also alicyclic having a number of carbon atoms
between 6 and 18, preferably between 8 and 15. Other preferred
anionic surfactants are of the sodium alkanesulphonate type
having a linear or branched chain comprised between C8 and
C20, preferably between C10 and C16.
Anionic surfactants are present in a percentage in the
range 0.5÷15.0% by weight, preferably 1.5÷10.0% by weight,
more preferably 2.0÷8.0% by weight.
Nonionic surfactants are preferably derived from aliphatic
alcohols polycondensed with alkylenoxide, for instance
ethylenoxide or propylenoxide: the aliphatic alcohols have a
linear or branched chain, preferably comprised between C8 and
C18 and are condensed with 2-12 units of ethylenoxide and/or
propylenoxide. The use of 2 or more alcohols polycondensed
with ethylenoxide is particularly preferred.
These are indicated for the sake of brevity with initials
indicating the length in carbon atom number of the aliphatic
chains of the prevailing alcohols, followed by the average
ethoxylation number; for instance the C12-13·3EO abbreviation
is used to indicate a mixture of ethoxylated alcohols wherein
the largely predominant alkyl chains are dodecyl and tridecyl
and the average number of condensed ethoxylic groups is 3.
Nonionic surfactants are present in a percentage in the
range 0.5÷15.0% by weight, preferably 1.5÷10.0% by weight,
more preferably 2.0÷8.0% by weight.
Hydrogen peroxide is present in a percentage in the range
1.0÷10.0% by weight, preferably 2.0÷8.0% by weight.
Auxiliary agents can be used to achieve a stable suspension
of the percarboxylic acid. Preferred auxiliary suspending
agents are water soluble or dispersible polymers, of ionic
type, such as polycarboxylates, of which various kinds of acrylic
homopolymers or acrylic-maleic copolymers having a different
molecular weight, are commercially available, for instance
with the trademark SOKALAN® by BASF, or associative/non
associative ones of non ionic type; such as for instance
ACUSOL® polymers by ROHM & HAAS. The auxiliary agents can be
present in percentages in the range 0.01÷3.0% by weight,
preferably 0.1÷1.5% by weight.
In addition or in alternative to the suspending polymers
stable suspensions of the compositions can preferably be
obtained by the formation of liquid crystal structures of continuous
lamellar and/or vesicular types. These liquid crystal
structures can be easily obtained by methods well known to the
ones skilled in the art, for instance, by the addition of suitable
amounts of some electrolytes, organic or inorganic salts,
to mixtures of anionic and non ionic surfactants or of
hydrophobic organic substances such as for instance long chain
alcohols or fatty acids. The electrolytes may be present in
amounts in the range 0.5÷15.0% by weight, more preferably
1.0÷8.0% by weight. Without any purpose of any limitation, the
electrolytes are preferably selected from: sodium citrate,
sodium or potassium hydrogensulphate, sodium or magnesium
sulphate, potassium sulphate, sodium or potassium nitrate and
mixtures thereof.
Optionally stable suspensions of the percarboxylic acid
can be obtained by combining the use of the electrolytes with
the above mentioned polymers.
Optional minor components may be present in small amounts
(0.05÷ 4.0% by weight), such as: acidifiers, as for instance
citric acid, sulphuric acid, sodium hydrogensulphate, sulphamic
acid; hydrotropes, such as sodium cumene- or xylene-sulphonate;
perfumes, antifoam agents, optical brighteners, heavy
or alkaline-earth metal sequestering agents.
The compositions generally appear as a stable suspension
which does not give signs of evident sedimentation on the bottom
either after centrifugation or after 4 weeks ageing at
30°C, but they can also appear with partial separation of the
percarboxylic acid on the bottom and therefore require the
container agitation without any influence on the use efficacy.
The compositions of the present invention have viscosity
at 20°C in the range 400-5000 mPa·s, more preferably between
600 and 2000 mPa·s.
Preferably the compositions of the invention have a pH in
the range 1.0 and 6.0, more preferably 2.0-5.0.
Water is present as the complement to 100% by weight.
The process for preparing the compositions in the form of
suspension is hereinafter described.
It has been found that the physical stability of the suspension,
obtained during the process for preparing the compositions,
is difficult to be obtained using the percarboxylic
having the characteristics of the type industrially available.
For instance the PAP wet cake appears as aggregate/conglomerate
of crystals having sizes in the range 10÷1000 µm. A
milling system of the percarboxylic acid has been set up which
remarkably reduces the crystal sizes in liquid phase without
danger of decomposition. The suspension obtained after milling
the percarboxylic acid results physically more stable and
appears as a viscous, turbid, opaque, creamy, homogeneous or
almost homogeneous liquid, characterised by an easier pourability
from the bottle and by a quicker solubilization of
the percarboxylic acid in the washing solution.
The crystal sizes of percarboxylic acid after milling are
in the range of 5.0 ÷ 100 µm.
Thus a dispersion of the percarboxylic acid, in demineralized
acidified water, or in a premixture containing some
components of the invention composition, such as the antifoam
and/or the anionic and/or non ionic surfactants and/or
hydrogen peroxide and/or the inorganic salts of the suspending
system (for instance sodium citrate, sodium or magnesium
sulphate) and/or acidity regulators (for instance citric or
sulphuric acid) and/or heavy metals chelant agents (for
instance derivatives or analogues of the ethylenediaminotetracetic
acid), is treated in a mixer, preferably a Silverson
type mixer or passed through a gear pump or a colloid mill for
a time suitable to obtain the desired milling level of
suspended solids, while temperature is monitored and anyway
maintained below 50°C, preferably below 35°C.
This milling process can be made directly in the mixer of
the composition preparation or in a separate vessel transferring
then the milled dispersion in the final mixer.
On the basis of what above reported but without any purpose
of any limitation two preferred general methods are described
in detail hereinafter for the preparation of present
invention compositions.
Preparation method A
A premix composition is prepared under stirring: to an
anionic surfactant solution (preferably prepared by neutralisation
of the anionic surfactant in acid form with a sodium or
potassium hydroxide solution under stirring or by solubilization
of sodium or potassium salt of the anionic surfactant),
antifoam, electrolytes (sodium or potassium or magnesium sulphate;
sodium bisulphate; sodium citrate or mixtures thereof)
optionally predissolved in demineralized water and hydrogen
peroxide are added and the pH is adjusted to the desired value,
for instance by sulphuric, or citric or sulphamic acid
addition.
In a separate vessel, a PAP dispersion in a suitable amount
of demineralized water having pH < 4.0, is passed through
a gear pump or a colloid mill or is treated with Silverson
type mixer for about 20 minutes. Temperature is monitored and,
if the case, maintained below 50°C, more preferably below 35°C
by cooling or regulating mixer (or pump) speed.
The PAP dispersion is then transferred into the main mixer.
Nonionic surfactants are added. The dispersion is completed
with the optional components and when necessary it is brought
to 100% by weight with water. The stirring is continued
for about 1 hour.
Preparation method B
The anionic surfactant solution is prepared under stirring
preferably by neutralization of the anionic surfactant in
acid form with a sodium or potassium hydroxide solution under
stirring or by solubilization of sodium or potassium salt of
the anionic surfactant. The pH is adjusted to the required
value with sulphuric acid (or with citric or sulphamic acid).
Then antifoam, hydrogen peroxide and PAP are added. The
dispersion is passed through a gear pump or a colloid mill or
is treated with Silverson type mixer for about 20 minutes at
a suitable speed to obtain the desired milling level.
Temperature is monitored and, if the case, maintained below
50°C, more preferably below 35°C by cooling or regulating
mixer (or pump) speed. The electrolytes (sodium or potassium
or magnesium sulphate; sodium bisulphate; sodium citrate)
optionally predissolved in the minimum necessary amount of
demineralized water, ethoxylated alcohols are added under
stirring; the dispersion is completed with the optional
components. Stirring is continued for about 1 hour.
For illustrative but not limitative purposes some
examples of the invention compositions are reported in Tables
1 and 2, wherein all the reported values appearing therein are
in per cent weight/weight (% W/W).
Some examples of the cleaning and hygienizing
performances of the present invention compositions and of some
products present on the market, are reported hereinafter for
illustrative but not limitative purposes.
Composition | 1 | 2 | 3 | 4 | 5 | 6 |
PAP (wet cake90%) | 4.0 | 4.0 | 4.0 | 6.0 | 6.0 | 6.0 |
Hydroxide Na or K | as suff. | as suff. | as suff. | as suff. | as suff. | as suff. |
Alkylbenzene sulphonic acid | 4.0 | 4.0 | 4.0 | 4.0 | 6.0 | 6.0 |
H2O2 | 7.0 | 7.0 | 7.0 | 3.5 | 3.5 | 3.5 |
Citric or sulphuric acid | as suff. to pH 4 | as suff. to pH 4 | as suff. to pH 4 | as suff. to pH 3 | as suff. to pH 3 | as suff. to pH 3 |
Sodium citrate | 3.0 | 3.0 | - | - | - | 2.0 |
Sodium sulphate | - | - | 2.0 | - | 6.0 | - |
Magnesium-sulphate | - | - | 2.0 | 3.0 | - | - |
C10-C11·8,5 EO | 1.0 | - | - | 1.0 | - | 2.0 |
C13-C15·9 EO | - | 1.5 | 1.5 | - | - | - |
C10-C11·2 EO | 5.0 | - | - | - | 3.0 | - |
C12-C13·3 EO | - | 4.5 | 3.5 | 6.0 | - | 4.0 |
Sodium cumen sulphonate | 0.6 | 0.6 | 0.6 | 0.6 | - | Acusol 882 2.0 |
Minor components | 0.2 -0.5 | 0.2 -0.5 | 0.2 -0.5 | 0.2 -0.5 | 0.2 -0.5 | 0.2 -0.5 |
Demineralized water | as suff. to 100 | as suff. to 100 | as suff. to 100 | as suff. to 100 | as suff. to 100 | as suff. to 100 |
Total surfactants | 10 | 10 | 9 | 11 | 9 | 12 |
active O (%) | 3.5 | 3.5 | 3.5 | 1.9 | 1.9 | 1.9 |
Composition
|
7
|
8
|
9
|
10
|
11
|
12
|
PAP (wet cake 90%) |
6.0 |
6.0 |
8.0 |
8.0 |
8.0 |
8.0 |
Hydroxide Na or K |
as suff. |
as suff. |
as suff. |
as suff. |
as suff. |
as suff. |
Alkyl benzensulphonic acid |
4.0 |
4.0 |
6.0 |
6.0 |
8.0 |
8.0 |
H2O2 |
3.5 |
3.5 |
3.5 |
5.0 |
5.0 |
5.0 |
Citric or sulphoric acid |
- |
as suff. to pH 3 |
- |
as suff. to pH 3 |
as suff. to pH 3 |
as suff. to pH 3 |
Sodium bisulphate |
1.0 (to pH 3) |
- |
2.0 (to pH 3) |
- |
- |
5.0 |
Potassium sulphate |
2.0 |
- |
- |
- |
1.0 |
- |
Magnesium sulphate |
- |
4.0 |
2.0 |
3.0 |
- |
- |
iso C10·6 EO |
- |
3.0 |
- |
1.0 |
- |
2.0 |
C13-C15·9 EO |
1.5 |
- |
1.5 |
- |
- |
- |
C10-C11·2 EO |
5.0 |
- |
- |
- |
- |
- |
C12-C13·3 EO |
- |
- |
3.5 |
6.0 |
4.0 |
4.0 |
Sodium cumenesulphonate |
0.6 |
- |
0.6 |
0.6 |
- |
- |
Minor components |
0.2 -0.5 |
0.2 -0.5 |
0.2 -0.5 |
0.2 -0.5 |
0.2 -0.5 |
0.2 -0.5 |
Demineralized water |
as suff. to 100 |
as suff. to 100 |
as suff. to 100 |
as suff. to 100 |
as suff. to 100 |
as suff. to 100 |
Total sufactants |
10.5 |
7 |
11 |
13 |
12 |
14 |
active O(%) |
1.9 |
1.9 |
2.0 |
2.8 |
2.8 |
2.8 |
EXAMPLES OF CLEANING PERFORMANCES (GROUP I)
The tests on cotton were doubly carried out in domestic
washing machine (REX RF 228X) by using a normal washing cycle at
the temperature indicated in table without prewashing and with 3
rinsing, cycles with water having an average hardness (ca. 25°
French degrees) an with 2 kg of white cotton articles. In each
washing two series of articles with standard dirts are
introduced. As oxidable stains the following dirts were used:
raw cotton (EMPA 222), red wine (EMPA 114), "immediale" black
(EMPA 115), tea (Wfk), coffee (Wfk). The removal of the stains
is determined by measuring with a Elrepho 2000 reflectometer the
increase of the percentage of reflected light before and after
the washing.
The washings were carried out at the washing machine
temperatures indicated in the tables with:
- High quality detergent (Dash®) for washing machine
(160 g in the small basin)
- additive (70 g) on the stains (2 g/dm2 applied on the
stains 5 minutes before the washing) + same detergent
(160 g in the small basin).
NOTES
The liquid additive containing hydrogen peroxide (indicated
with the name "Liquid additive" in tables "liq. add.") is
representative of the Italian market (Omino Bianco Candeggina
Delicata®, Ace Gentile®) and contains, in weight/weight %:
- - active oxygen
- about 3.3% (under the form of
hydrogen peroxide)
- - anionic surfactant
- about 1.2%
- - non ionic surfactant
- about 1.0% (under the form of
ethoxylated alcohol).
The results of the washings belong to group I, carried out
in the presence of the compositions of the invention and those
of the comparative tests are reported in Tables from 3a to 3c.
EXAMPLES OF STAIN REMOVING AND CLEANING PERFORMANCES (GROUP II)
The results of the washings belong to group (II) carried
out in the presence of the compositions of the invention and
those of the comparative tests, are reported in Tables 4a, 4b,
4c, 4d, 4e and 4f.
Bleach performances have been evaluated on artificially
soiled testfabrics over three washing cycles without prewashing
in domestic washer in the washing condition indicated below.
In each wash cycle two series of testfabrics are washed. As
bleachable stains the following soiled testfabrics were used:
crude cotton (EMPA 222), red wine (EMPA 114), apple (CFT-CS 13),
black-currant (CFT-CS 12), tea (CTTN), coffee (CTTN) in the case
of cotton and tea soiled wool (CTTN), red wine soiled wool
(CTTN), red wine soiled silk (CTTN) in the case of delicate
fabric tests.
Reflectance value are determined without optical brightening
effect by ELREPHO 3300 (DATACOLOR) reflectometer. Four
tristimulus measures are determined for each sample. The average
measured values are then expressed in Tables 4a, 4b, 4c, 4e and
4f as follows:
s.r.= Stain removal of each stain kind.It is calculated as
follows:
wherein: A= reflectance value of white (unsoiled and unwashed) testfabric; B= reflectance value of stained testfabric before washing; C= reflectance value of stained testfabric after washing. average s.r. = stain removal calculated as the average of s.r. of
bleachable stain series s.r. difference =is the differenece between s.r. of additive
(+ detergent) in question and s.r. of
reference detergent alone,i.e. is the stain
removal improvement given by the additive. % increase = is the percent ratio between s.r.difference
of the additive in question and s.r. of
reference detergent.
Composition used:
EXAMPLES OF DISINFECTANT PERFORMANCES
The bactericide action of the present invention compositions
is very effective at low temperatures. The following results are
given as an example.
Indeed according to the primary bactericide action test PhEN
1040 September 1996, it is necessary that the examined product at
the use concentration causes a decrease of at least 105 colonies/millilitre
(col/ml) wherein colonies means unit forming colonies,
in a solution having in suspension pathogenic bacteria (PSEUDO MONAS
AERUGINOSA and STAPHYLOCOCCUS AUREUS) with an initial Total Bacteric
Charge (TBC) of 108-109 colonies/ml. By carrying out the above test
on solutions having a pH 8.0 of the exemplified compositions, the
following results are obtained:
at 30°C : after 5 minutes with a concentration of 4.0 g/l of
the composition 4 or of 2.5 g/l of the composition 12 (corresponding
to the addition respectively of 80 g and 50 g in a machine washing
machine) a decrease higher than 105 col/ml is obtained.
For comparison with a powder disinfectant additive (containing
as active starting materials for an hygienizing effect about: 3% by
weight of active oxygen as perborate or percarbonate and 1-6% by
weight of the activator TAED) at a concentration of 5.0 g/l, the
reduction of 105 col/ml is obtained only after 15 minutes.
at 20°C : after 10 minutes with a concentration of 4.0 g/l of
the composition 8 of the EXAMPLES or of 2.5 g/l of the composition
12 (corresponding to the addition respectively of 80 g and 50 g in
a washing machine) a reduction of 105 col/ml is obtained. The
application of the compositions directly on the cloth allows to
obtain the same action using a much less use of product since
locally it has a concentration even higher than that above
described.
For comparison a powder disinfectant additive, of the above
indicated composition, after 60 minutes, with a concentration of 5.0
g/l, causes a reduction of 105 col/ml.
For comparison a liquid additive selected from those indicated
in the art for instance OMINO BIANCO® added in the washing is
effective after 60 min at a concentration of 3.5 g/l equal to 70 ml
in washing machine.
The above test was carried out also on solutions of the
exemplified compositions without any pH modification, and the
following results have been obtained:
at 30°C : the composition 4' causes a TBC decrease higher than
105 u.f.c./ml after 15 minutes at a 5 g/l concentration.
For comparison a powder disinfectant additive (containing as
active starting materials for an hygienizing effect about: 3% by
weight of active oxygen as perborate or percarbonate and 1-6% by
weight of TAED as activator) produce the above description action
only at a concentration of 14.0 g/l after 15 minutes.
at 20°C : the composition 4' causes a TBC decrease higher than
105 u.f.c./ml within 30 minutes at a 7 g/l concentration obtained.
The direct application of the compositions on the cloth allows to
obtain the same action using a much less amount of product since in
the application area the concentration is higher than that above
described.
For comparison a powder disinfectant additive, of the above
indicated composition, after 120 minutes, with a concentration of
5.0 g/l, causes a reduction of 105 u.f.c./ml.