[0001] This invention relates to a cleaning agent based on active chlorine and alkali. Such
cleaning agents are used in practice for cleaning pipes and ducts and the like, for
instance of apparatuses for milk processing. Usually the cleaning occurs at 40 - 45°C
and accordingly, the mixture should be preheated at a suitable temperature. Normally,
no surfactants other than wetting agents are incorporated in such mixtures, because
otherwise too much foaming would occur, particularly at the elevated temperatures
and the intensive mechanical action, which accordingly would influence the cleaning
action rather in a disadvantageous than in an advantageous way.
[0002] Such cleaning agents should be well discerned from the so-called thickened bleach
compositions, such as disclosed in GB-A-2,076,010A and EU-A-0,072,600 which contain
much more hypochlorite solution than alkali (vide page 2, line 25 of EU-A-0072600)
and wherein the added surfactant serves for thickening the composition. The present
compositions are intended for industrial use and contain alkali metal hydroxide in
an amount of at least 50 % of the bleaching agent.
[0003] Surprisingly, it has now been found that a very restricted group of ethercarboxylic
acid derivatives, when added to this kind of compositions, shows a combination of
a very efficient surfactant action with a low foaming, which makes it possible to
incorporate these compounds in the present kind of cleaning agents, and then to use
these cleaning agents at room temperature. Accordingly, an important energy saving
is attained in this way which is not at the expense of the cleaning action.
[0004] Accordingly, this invention relates to cleaning agents on the basis of active chlorine
and alkali which are characterized by the fact that they also contain a minor amount
of a compound of the formula
wherein M is sodium or potassium and n is a number having an average value of 1 -
.10.
[0005] The present surfactants are known per se and belong to a group of compounds which
is already known for a long time for its useful properties. However, within this group
of compounds the C
8H
17-compounds have always been considered to constitute more or less a borderline case,
and compounds derived from larger hydrophobic residues were always preferred. This
appears not only from the above-mentioned
UK-A-2,076,010 which, although stating that the hydrophobic residue may be a.o. a C
6-20 alkyl residue, states a preference for C
12-C
13' and from EU-A-0,072,600 which mentions as hydrophobic group a.o. an alkyl group of
8 - 18 carbon atoms and expresses a clear preference for C
12-C
14, but also from N
L-A-7405231, wherein the hydrophobic residue again may be a C
8-C
20 alkyl group, but again is preferably c12-C14 alkyl, and from FR-A-1,099,84/ which,
although mentioning the C
SH
17 compound as an example of a possible compound, also clearly prefers higher alkyl
compounds. It should be noted that the C
- compound is used in none of the examples of the above-mentioned publications.
[0006] In the compounds used according to the present invention the alkyl group C
8H
17 may be a straight chain or branched group, for instance n-octyl or 2-ethylhexyl.
In principle one can of course also incorporate the free acid into the composition
containing the active chlorine and alkali, so that the desired salt is formed in situ.
Theoretically it is of course also possible to use other salts, such as the ammonium
salt or organic ammonium and amine salts, but of course in actual practice one uses
preferably a salt of the ethercarboxylic acid with the same anion as in the alkali
metal hydroxide component of the base mixture.
[0007] The other components in the system are the usual ones for this kind of compositions.
The alkali is KOH or NaOH and the concentration thereof can be varied within relatively
wide limits, generally between 20 to 250 g per liter. A suitable concentration is
in the order of 80 - 120 g per liter. The active chlorine in the system can be derived
from various usual compounds. Chlorine- containing bleaching lye is a cheap product,
and therefore this is generally used. However, a compound like trichlorocyanuric acid
or chloramine T can also be used as chlorine-producing agents. Usually, the system
contains about 3 - 6 % of active chlorine, preferably about 4.5 %. As mentioned already,
the amount of alkali in such systems is at least 50 % of the amount of bleaching agent-The
amount of surfactant to be used according to the present invention can best be expressed
in the weight ratio between surfactant and active chlorine. This weight ratio generally
can vary from 1:10 to 1:3. Thus it is suitable to use 0.65 % of the present surfactant
with the above-mentioned preferred amount of 4.5 % of active chlorine.
EXAMPLES
[0008] A number of mixtures were prepared, containing 30.0 % hypochlorite bleaching agent
(150 g chlorine/liter), 20.0 % of 50 % aqueous potassium hydroxide, the percentages
of ethercarboxylic potassium salts stated hereinbelow, and the remainder water. The
used ethercarboxylic salts had the formula octyl-O-(C
2H
4)
n-CH
2COOK.
[0009] A foaming test was carried out by dissolving 10 grams of each product in 1 liter
of tap water (German hardness about 20°), shaking 50 ml of this solution vigorously
by hand in a shaking cylinder of 100 ml, and reading the foam volume after 1 minute.
In this experiment a foam volume of 15 ml or less is considered satisfactory. The
results of these experiments have been rendered in the following table.
[0010] For some purposes KOH is preferred in this kind of compositions and for other purposes
NaOH is preferred. This does not make any difference for the effect of the present
invention, as will appear from the following two examples.
[0011] The mixtures of Examples IX and XI were prepared again, but this time with NaOH.
These compositions are named Examples IXa and XIa. They were also subjected to the
above foaming test, and this at 12°C and 20°C. The results have been rendered hereinbelow,
and for the sake of clarity the corresponding results with KOH from the above table
have been reiterated here.
1. A cleaning agent based on active chlorine providing bleaching agent and alkali
metal hydroxide in an amount of at least 50 % of the bleaching agent, characterized
by containing a minor amount of a low-foaming compound of the formula C8H17O-(C2H4O)nCH2COOM, wherein M is sodium or potassium and n is a number having an average value of
1 - 10.
2. A cleaning agent according to claim 1, characterized by the fact that the weight
ratio between said low-foaming compound and active chlorine is 1:10 to 1:3.
3. A cleaning agent according to claim 1 or 2, characterized by the fact that it contains
3 - 6 % of active chlorine in the form of bleaching lye.
