Process for manufacturing stable, low viscosity O/W anti-rust emulsions

The invention relates to a process for preparing stable low-viscosity O/W rust-inhibiting emulsions, characterized in that a mixture having the following composition is employed for the formation of the emulsion: PA1 a) from 10 to 60% by weight of an oil component; PA1 b) from 1 to 10% by weight of an emulsifier component consisting of at least one addition product of from 2 to 20 moles of ethylene oxide to fatty alcohols having from 10 to 22 carbon atoms; PA1 c) from 1 to 10% by weight of a corrosion inhibitor consisting of at least one carboxylic acid having the general formula (I): EQU R--COOH (I), wherein R represents a straight-chain or branched saturated or unsaturated alkyl moiety comprising from 6 to 22 carbon atoms or a moiety having the general formula (II): ##STR1## wherein R.sup.1 represents a saturated straight-chain or branched alkyl moiety comprising from 8 to 18 carbon atoms; PA1 d) from 0 to 10% by weight of co-emulsifier component consisting of at least one fatty alcohol comprising from 12 to 22 carbon atoms; and PA1 e) water as the balance.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a process for preparing O/W (oil-in-water) 
rust-inhibiting emulsions based on an oil component, water, at least one 
emulsifier component, and a corrosion inhibitor. Observing certain 
conditions in said process leads to especially stable and low viscosity 
O/W emulsions which ensure good protection from corrosion for metal 
surfaces made of iron or steel. 
2. Statement of Related Art 
Rust-inhibiting emulsions are employed for the temporary protection of 
metallic workpieces from atmospheric influences causing corrosion. Said 
emulsions substantially contain non-polar or polar oils, emulsifiers, 
corrosion inhibitors, and water. The effect provided thereby is due to an 
adsorption of inhibitor molecules on the metal surface and the formation 
of a protective film from emulsion components, which film acts as a 
diffusion barrier for the oxygen of the air and for water. Th. Forster et 
al. in Oberflache-Surface 1989, No. 4, pp. 8-12, report on the mode of 
action and methods of investigation of rust inhibiting emulsions. Other 
commercially available systems are based on oil concentrates containing 
emulsifiers and corrosion inhibitors--but no water. This depends on the 
emulsifiers and corrosion inhibitors employed being oil soluble. For the 
preparation of O/W emulsions from such oil concentrates this further means 
that such systems must be self-emulsifying. 
It has been known that oil-in-water emulsions which have been prepared and 
stabilized with non-ionic emulsifiers can undergo a phase inversion when 
heated, i.e., at elevated temperatures the outer aqueous phase may become 
the inner phase. This process, as a rule, is reversible, i.e., upon 
cooling the initial emulsion type is regenerated. It has also been known 
that the point of phase inversion temperature is dependent on many 
factors, e.g., on the kind and phase volume of an oil component, on the 
hydrophilicity and structure of the emulsifier, and on the composition of 
the emulsifier system; cf., for example, K. Shinoda and H. Kunieda in 
Encyclopedia of Emulsion Technology, Vol. I, ed. P. Becher (M. Decker, 
N.Y., 1983), pp. 337 to 367. It has further been known that emulsions 
prepared at or slightly below the phase inversion temperature (PIT) are 
distinguished by particularly fine particle size and particular stability, 
whereas those emulsions prepared above the phase inversion temperature are 
less finely divided; cf. S. Friberg, C. Solans, J. Colloid Interface Sci., 
66, pp. 367 to 368 (1978). F. Schambil, F. Jost, and M. J. Schwuger, in 
Progress in Colloid & Polymer Science 73, (1987), pp. 37 to 47, report on 
the properties of cosmetic emulsions containing fatty alcohols and fatty 
alcohol polyglycolethers and, in the course thereof, also describe how 
emulsions produced above the phase inversion temperature exhibit a low 
viscosity and a high storage stability. In the so far unpublished German 
Patent Application P 38 19 193.8 by Applicants there has been described a 
corresponding process for the preparation of stable low-viscosity O/W 
emulsions of polar oil components. 
DESCRIPTION OF THE INVENTION OBJECT OF THE INVENTION 
In contrast thereto it is the object of the invention to develop a process 
suitable for preparing O/W rust inhibiting emulsions which entirely or 
predominantly contain polar carboxylic acids as corrosion inhibitors. Such 
O/W emulsions should be capable of inverting at temperatures below 
100.degree. C. in order thereby to produce particularly stable finely 
divided and low viscosity emulsions. The emulsions thus obtained should 
further be water dilutable, and the dilutions should also be stable and 
provide an efficient protection from corrosion. 
SUMMARY OF THE INVENTION 
Accordingly, the invention relates to a process for preparing stable 
low-viscosity O/W rust inhibiting emulsions, wherein a mixture containing 
an oil component, water and at least one emulsifier component is 
emulsified at a temperature where all components of the mixture are in the 
liquid state, and the emulsion formed is heated at a temperature within or 
above the temperature range of phase inversion; or the mixture is 
emulsified at a temperature within or above the temperature range of phase 
inversion, followed by cooling the resulting emulsion to a temperature 
below said temperature range, and optionally by dilution with water, said 
process being characterized in that a mixture having the following 
composition is employed for the formation of the emulsion: 
a) from 10 to 60% by weight of an oil component, 
b) from 1 to 10% by weight of an emulsifier component consisting of at 
least one addition product of from 2 to 20 moles of ethylene oxide to 
fatty alcohols having from 10 to 22 carbon atoms, 
c) from to 10% by weight of a corrosion inhibitor consisting of at least 
one carboxylic acid having the general formula (I): 
EQU R--COOH (I) 
wherein R represents a straight-chain or branched saturated or unsaturated 
alkyl moiety comprising from 6 to 22 carbon atoms, or a moiety having the 
general formula (II): 
##STR2## 
wherein R.sup.1 represents a saturated or branched alkyl moiety comprising 
from 8 to 18 carbon atoms, 
d) from 0 to 10% by weight of co-emulsifier component consisting of at 
least one fatty alcohol comprising from 12 to 22 carbon atoms, and 
e) water as the balance. 
Within the scope of the invention, the following items are of essential 
importance: 
On the one hand, the selection of suitable carboxylic acids which in their 
acidic forms are effective as corrosion inhibitors and, on the other hand, 
the manner of preparing stable low viscosity O/W emulsions containing said 
corrosion inhibitors. Here, the carboxylic acids must not impair, or 
prohibit altogether, a phase inversion of the emulsion. Furthermore, the 
selection of suitable emulsifiers, which, on the one hand, will form such 
stable emulsions with said corrosion inhibitors and, on the other hand, 
will not impair the activity of the corrosion inhibitors on the substrate 
surface under atmospheric corrosion conditions by re-emulsification, is 
essential. 
Surprisingly, the process according to the invention makes it possible to 
produce such stable and low viscosity O/W rust-inhibiting emulsions. In 
said process, the mixture comprising all of the emulsion components as set 
forth, including the carboxylic acids, is subjected to a phase inversion 
by heating the mixture or the emulsion already existing at a temperature 
within or above the temperature range of phase inversion. Thereby it is 
made possible to introduce said corrosion inhibitors in the finely divided 
form as desired into the emulsion and to stably emulsify them therein. 
Within those of the above-defined composition of O/W rust inhibiting 
emulsions according to the invention which contain relatively high amounts 
of carboxylic acids as corrosion inhibitors, a phase inversion will take 
place below 100.degree. C. This phase inversion takes place with non-polar 
oils (paraffin oils) as well as with lightly polar oils (mineral oils). 
These rust-inhibiting emulsions produced in accordance with so-called PIT 
method, i.e., phase inversion temperature method, have a higher storage 
stability when compared to emulsions having the same compositions but 
which have not undergone a phase inversion. Moreover, in the corrosion 
test, evaluated according to DIN 51 359, more than 40 days have passed 
until a 100% corrosion is observed. Thus, the anti corrosive effectiveness 
is in the same order of magnitude as that of the products belonging to 
prior art.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Within the scope of the invention it is preferred to employ, for forming 
the emulsion, a mixture having a composition as follows: 
a) from 20 to 50% by weight of an oil component, 
b) from 2 to 8% by weight of an emulsifier component, 
c) from 2 to 6% by weight of a corrosion inhibitor, 
d) from 0 to 6% by weight of a co-emulsifier component, and 
e) water as the balance. 
For the individual components of the O/W rust inhibiting emulsions to be 
prepared according to the invention, the following details apply: 
As the oil component there may be employed oils of various polarities, for 
example paraffin oils or mineral oils. Also so-called ester oils, i.e., 
fatty acid glycerides, may be used in admixture with mineral oils and/or 
paraffin oils. Within the scope of the invention, it is preferred to 
employ paraffin oils or mineral oils as the oil component a). 
The emulsifier component b) may include products from addition of from 2 to 
20 moles of ethylene oxide to fatty alcohols comprising from 10 to 22 
carbon atoms. Fatty alcohols suitable therefore are natural and/or 
synthetic fatty alcohols such as decanol, undecanol, dodecanol, 
tridecanol, tetradecanol, pentadecanol, hexadecanol (cetyl alcohol), 
heptadecanol, octadecanol (stearyl alcohol), nonadecanol, eicosanol, 
heneicosanol, and docosanol (behenyl alcohol). Commercially produced 
addition products of ethylene oxide to such fatty alcohols are usually 
mixtures of polyglycolethers of the initial fatty alcohols, the average 
ethoxylation degree of which conforms to the molar amount of ethylene 
oxide attached. Within the scope of the invention, addition products of 
from 4 to 12 moles of ethylene oxide to fatty alcohols having from 12 to 
18 carbon atoms are preferred as the emulsifier component b). Especially 
used here are: Addition products of 4 moles of ethylene oxide to mixtures 
of fatty alcohols comprising from 12 to 14 carbon atoms, addition products 
of 4 moles of ethylene oxide to mixtures of fatty alcohols comprising from 
12 to 18 carbon atoms, or addition products of 12 moles of ethylene oxide 
to mixtures of fatty alcohols comprising from 16 to 18 carbon atoms. 
The carboxylic acids having the general formula (I) 
EQU R--COOH (I) 
employed as the corrosion inhibitors c) may be of different structures. 
Within the meaning of the invention, suitable carboxylic acids of the 
general formula (I) are those wherein the radical R represents a 
straight-chain or branched, saturated or unsaturated alkyl moiety 
comprising from 6 to 22 carbon atoms. These include, more specifically, 
natural or synthetic fatty acids, for example hexanoic acid (caproic 
acid), heptanoic acid, octanoic acid (caprylic acid), nonanonic acid, 
decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric 
acid), tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoic 
acid, hexadecanoic acid (palmitic acid), heptadecanoic acid, octadecanoic 
acid (stearic acid), nonadecanoic acid, arachidic acid, heneicosanoic acid 
and behenic acid. In the same manner, the corresponding branched-chain or 
unsaturated carboxylic acids are suitable as corrosion inhibitors within 
the scope of the invention. According to the invention, those carboxylic 
acids of the general formula (I), wherein the moiety R represents a 
straight-chain or branched saturated or unsaturated alkyl moiety having 
from 8 to 18 carbon atoms are preferred. The corresponding straight-chain 
saturated fatty acids are apparent from the above listing. As the branched 
chain or unsaturated carboxylic acids of this type there are especially 
considered isononaoic acid, oleic acid, linoleic acid, or linolenic acid. 
Mixtures of said acids are also effective corrosion inhibitors within the 
scope of the present invention, for example, a mixture comprising stearic 
acid and palmitic acid in a ratio by weight of 1:1. 
The corrosion inhibitors within the scope of the invention further include 
carboxylic acids having the general formula (I) wherein R represents a 
moiety having the general formula (II) 
##STR3## 
wherein R.sup.1 represents a saturated straight-chain or branched alkyl 
moiety comprising from 8 to 18 carbon atoms. Such alkylbenzoylacrylic 
acids and the use thereof as corrosion inhibitors in lubricating oils and 
lubricating greases have been described in the DE-OS 36 00 401. In said 
German Laid-Open Patent Application there are also found indications 
relating to the synthesis of such alkylbenzoylacrylic acid. Thus, the 
alkyl radicals R.sup.1 may be unbranched or branched radicals from the 
group of octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, 
pentadecyl, hexadecyl, heptadecyl, and octadecyl, with the corresponding 
straight-chain alkyl radicals having from 8 to 12 carbon atoms being 
preferred according to the invention. According to the invention, among 
this type of carboxylic acids the 3-(p-dodecylbenzoyl) acrylic acid is 
employed with particular advantage. 
It has further proven to be advantageous for the process according to the 
invention to employ a co-emulsifier component (d) in addition to the 
emulsifier component. The co-emulsifier, due to its hydrophilicity, itself 
is not suitable for preparing O/W emulsions; however, especially stable 
and finely divided emulsions of polar oil components can be prepared in 
combination with the above-defined emulsifier components according to the 
invention. The coemulsifiers according to the invention may include 
saturated fatty alcohols having from 12 to 22 carbon atoms. The fatty 
alcohols suitable for this purpose have been mentioned in the above 
enumeration of fatty alcohols. Also suitable are mixtures of such fatty 
alcohols as obtained, for example, upon the technical hydrogenation of 
vegetable and animal fatty acids having from 12 to 22 carbon atoms or of 
the corresponding fatty acid methyl esters. It is preferred within the 
scope of the invention that such coemulsifiers be employed in amounts of 
from 1 to 6% by weight, based on the mixture. Particularly preferred as 
co-emulsifiers are fatty alcohols comprising 16 to 18 carbon atoms, for 
example a mixture of cetyl alcohol and stearyl alcohol in a ratio by 
weight of 1:1. 
According to a further preferred embodiment of the present invention, the 
oil component a), the emulsifier component b), and the corrosion inhibitor 
c) are employed in a definite ratio by weight of a):b):c)+1:(0.1 to 
0.3):(0.1 to 0.3). Thus, especially low-viscosity and storage-stable 
rust-inhibiting emulsions are obtained. A ratio by weight of a:b:c=1:0.2:0 
15 is particularly preferred. 
The process according to the invention may be carried out in a manner such 
that first the phase inversion temperature is determined by heating the 
sample of the emulsion prepared in the usual manner by using an apparatus 
for measuring the conductivity and determining the temperature at which 
the conductivity strongly decreases. The specific conductivity of the 
oil-in-water emulsion as initially present will commonly drop within a 
temperature interval of from 2.degree. C. to 8.degree. C. from initially 
more than 1 mS/cm to values of below 0.1 mS/cm upon transition into an 
inverted emulsion. This temperature range is denoted as the phase 
inversion temperature range. 
After the phase inversion temperature range for a definite composition of 
an emulsion is known, the process according to the invention may, in one 
mode, be carried out by first preparing the emulsion as usual so that it 
contains all of the components essential for the invention and then 
heating the emulsion thus obtained at a temperature within or above the 
phase inversion temperature range. Another mode of carrying out the 
process according to the invention comprises preparing a pre-determined 
emulsion at a temperature already pre-selected such as to be within or 
above the phase inversion temperature range. As a rule, the last-mentioned 
mode is practiced, i.e., all of the components essential according to the 
invention for a definite emulsion are mixed, the resulting mixture is 
heated at some temperature above the phase inversion temperature range, 
and the mixture is then emulsified by vigorous stirring. The emulsion 
formed is then allowed to cool to a temperature below the phase inversion 
temperature range, or the emulsion is cooled to an appropriate 
temperature. Thereby, concentrates of O/W rust-inhibiting emulsions, which 
may optionally be diluted with water, are obtained. 
The O/W rust-inhibiting emulsions may be put into use in the form of the 
concentrates as well as in the form of the water dilutions obtained from 
said concentrates. However, usually they are used in the diluted form. The 
concentrates as well as the water-diluted emulsions ensure a very good 
protection from corrosion to be provided for metal surfaces from iron and 
steel. The anti-corrosive activity of the emulsions produced according to 
the invention is also retained, if the carboxylic acids effective as 
corrosion inhibitors are present in their neutralized forms. With a view 
thereto, it is possible to subsequently neutralize the O/W rust inhibiting 
emulsions prepared according to the invention with suitable alkaline 
agents, for example with caustic solutions such as NaOH or Ca(OH).sub.2 
solutions. 
The oil-in-water rust-inhibiting emulsions prepared upon temperature 
inversion by the process according to the invention, in comparison to 
emulsions prepared below the phase inversion temperature, are particularly 
finely divided and have low viscosities and, hence, are pourable and 
pumpable (FIG. 2). Moreover, said rust inhibiting emulsions also exhibit a 
marked storage stability. Upon comparison of the periods of time passed 
until test sheets show 100% corrosion (evaluated according to DIN 51 359), 
the sheets treated with anti-corrosive emulsions according to the 
invention showed a lower susceptibility to corrosion than did the sheets 
treated with conventional anti-corrosive emulsions. Upon phase inversion, 
concentrates of rust-inhibiting emulsions could be obtained which contain 
more than 50% of organic matter. These concentrates, because they, after 
the preparation thereof, constitute oil-in-water systems and because the 
oil phase is present in the most finely dispersed state, are readily 
water-dilutable without thereupon losing their high storage stabilities 
(FIG. 3). In contrast to the conventional systems based on 
oil-concentrates, for carrying out the process according to the invention, 
the emulsifier mixtures and corrosion inhibitors need not necessarily be 
oil-soluble. 
The process according to the invention and the advantages provided by the 
O/W rust-inhibiting emulsions produced thereby are illustrated in greater 
detail by the following Examples. 
EXAMPLES 
The formulations described below were prepared using various commercial 
products, the compositions and sources of which were as follows: 
______________________________________ 
Mineral oil 
Mineral oil (naphthene-based) from Hansen & 
Pionier .RTM. 4556 
Rosenthal, Hamburg 
Emulgin .RTM. B1: 
Product of addition of about 12 moles of 
ethylene oxide to cetylstearyl alcohol (a 
mixture consisting of cetyl and stearyl 
alcohols in a weight ratio of about 1:1), 
from Henkel KGaA, Dusseldorf 
Lanette .RTM. O: 
Cetylstearyl alcohol (a mixture consisting 
of cetyl and stearyl alcohols in a weight 
ratio of about 1:1), from Henkel KGaA, Dus- 
seldorf 
Dehydol .RTM. LS4: 
Product of addition of about 4 moles of eth- 
ylene oxide to C.sub.12-14 fatty alcohols, from 
Henkel KGaA, Dusseldorf 
Dehydol .RTM. LT4: 
Product of addition of about 4 moles of eth- 
ylene oxide to C.sub.12-18 fatty alcohols, from 
Henkel KGaA, Dusseldorf 
______________________________________ 
Compositions of the Formulations A to D 
Formulation A: 
40% by weight of mineral oil Pionier.RTM. 4556 
8% by weight of Emulgin.RTM. B1 
6% by weight of 1:1 stearic acid/palmitic acid 
46% by weight of water 
Formulation B: 
20% by weight of paraffin oil 
5% by weight of Dehydol.RTM. LS4 
3% by weight of 3-(p-dodecylbenzoyl)acrylic acid 
2% by weight of Lanette.RTM. O 
70% by weight of water 
Formulation C: 
20 % by weight of mineral oil Pionier.RTM. 4556 
3 % by weight of Emulgin.RTM. B1 
1 % by weight of Dehydol.RTM. LT4 
3 % by weight of 1:1 stearic acid/palmitic acid 
73 % by weight of water 
Formulation D: 
20 % by weight of mineral oil Pionier.RTM. 4556 
4 % by weight of Emulgin.RTM. B1 
3 % by weight of lauric acid 
73 % by weight of water 
EXAMPLE 1 
Preparation of the O/W Rust-Inhibiting Emulsions According to the 
Invention, Based on the Formulations A to D: 
The individual components as indicated for each of the formulations A to D 
were mixed, and each mixture was emulsified by vigorous stirring at a 
temperature above the respective phase inversion temperature range. The 
relevant data are shown in the following Table 1. 
TABLE 1 
______________________________________ 
Phase Inversion 
Emulsifying 
Example Formulation 
Temperature Range 
Temperature 
______________________________________ 
1.1 A 62 to 64.degree. C. 
70.degree. C. 
1.2 B 60 to 75.degree. C. 
80.degree. C. 
1.3 C 67 to 89.degree. C. 
95.degree. C. 
1.4 D 62 to 71.degree. C. 
95.degree. C. 
______________________________________ 
EXAMPLE 2 
Comparison of the Stability of Emulsions Having the Same Compositions, but 
Different Preparations Temperatures (FIG. 1). 
Two emulsions were prepared from mixtures of Formulation D. For the first 
emulsion, a preparation temperature of 45.degree. C.--below the phase 
inversion temperature (PIT) range--was chosen, while for the second 
emulsion a preparation temperature of 95.degree. C.--above the PIT--was 
chosen, in the same manner as in Example 1.4. For evaluating the stability 
of each emulsion, the conductivity thereof was measured in the upper and 
lower regions of the measuring vessel (cf. the left scale of FIG. 1), and 
the percentage difference was calculated (cf. the right scale of FIG. 1). 
The measuring vessel was a glass cylinder (height: 125 mm; diameter: 25 
mm), in which two pairs of platinum electrodes (Type PP 1042 from 
Radiometer) were provided in each of the positions 2 mm from the top and 2 
mm from the bottom. For the measurement, the glass vessel was completely 
filled with each emulsion under investigation, which contained 50 mg of 
NaCl per 1 liter of emulsion as the supporting electrolyte, so that even 
the electrodes in the top region of the vessel were completely immersed in 
the solution. All of the measurements were carried out at room 
temperature. 
In the case of an unstable emulsion there is a creaming tendency--in the 
sense of separation of the emulsion within the course of the period of 
measurement--shown by different conductivities in the top and bottom 
regions of the measurement vessel; the percentage difference is not zero. 
However, in the case of stable emulsion, there are nearly no differences 
between the conductivities in the different measurement regions; 
accordingly the percentage difference is zero or close to zero. 
FIG. 1 shows the results obtained by the measurement. It is apparent that 
the first emulsion, with a preparation temperature of 45.degree. C. (below 
PIT), was already unstable within a period of measurement of 20 hours, 
whereas the second emulsion, prepared according to the invention at a 
temperature of 95.degree. C. (above PIT) was stable over a substantially 
longer period of time. 
EXAMPLE 3 
Comparison of the Viscosity of Emulsions Having the Same Compositions, but 
Different Preparation Temperatures (FIG. 2). 
Two emulsions were prepared from mixtures of Formulation A. For the first 
emulsion, a preparation temperature of 60.degree. C.--below PIT--was 
chosen, while for the second emulsion according to this invention a 
preparation temperature of 95.degree. C.--above the PIT--was chosen, in 
the same manner as in Example 1.1. The resulting emulsions were diluted 
with water in a ratio of 1:1, and the viscosities of the diluted emulsions 
were determined at various shearing rates. 
FIG. 2 shows the results of the measurements, which represent the viscosity 
behavior of a diluted emulsion, i.e., a preferred embodiment. It is 
evident therefrom that the second emulsion according to the invention 
(with phase inversion) was substantially less viscous than the first 
emulsion (without phase inversion). 
EXAMPLE 4 
Storage Stability of Emulsion According to the Invention 
The storage stability at room temperature of the emulsions according to 
Examples 1.1 to 1.3 was visually assessed. In these tests, the emulsions 
were employed in the form of their concentrates; the emulsions according 
to Examples 1.1 and 1.3 were tested as prepared, unchanged, while the 
emulsion according to Example 1.2 was neutralized with Ca(OH).sub.2 prior 
to the test. The results are shown in Table 2. 
TABLE 2 
______________________________________ 
Emulsion According 
Storage Stability at 
to Example: Room Temperature 
______________________________________ 
1.1 &gt;6 months 
1.2 &gt;1 month.sup. 
1.3 &gt;6 months 
______________________________________ 
The results show that the concentrates according to the invention have a 
very good storage stability. 
EXAMPLE 5 
Storage Stability of a Diluted Emulsion According to the Invention (FIG. 3) 
An emulsion according to Example 1.1 was diluted and neutralized with 
aqueous NaOH solution in a ratio of 1:9. For the evaluation of the 
stability of the resulting emulsion, the conductivities in the top and 
bottom regions of the measuring vessel were determined (cf. the left scale 
of FIG. 3), and the percentage difference was calculated (cf. the right 
scale of FIG. 3). The significance of this measurement procedure with 
respect to the stability of the emulsion is explained in greater detail in 
Example 2. 
FIG. 3 shows the results obtained by the measurement. Therefrom it will be 
apparent that even the diluted emulsion, i.e., in its preferred 
embodiment, was stable for a period of nearly 100 hours. This period is 
absolutely sufficient for the stability of a water diluted emulsion, i.e., 
that form in which the emulsions are usually applied, in comparison to the 
concentrate form, i.e., that form in which the emulsions are usually 
stored. 
EXAMPLE 6 
Test of the Anti-Corrosive Ability 
The anti-corrosive property of emulsions according to the invention and of 
a comparative emulsion was tested according to DIN 51 359. The test 
procedure was carried out as follows: Steel sheets of the grade St 1405 
(unalloyed steel, surface-refined, dimensions 2.5 cm x 5 cm) were each 
immersed in one of the rust-inhibiting emulsions as indicated below. The 
steel sheets were kept in contact for a short time with the 
rust-inhibiting emulsions, then removed therefrom and, after a dripping 
and drying period of 24 hours, were placed in a moist chamber as specified 
in DIN 51 359, wherein the relative humidity was 100%, with a continuous 
air supply of 875 1/h at a temperature of 50 .degree. C. In each case 
there was determined a period of time after which a 100% corrosion 
(relative to the area of the test sheet) was to be observed - evaluated 
according to DIN 51 359. 
The emulsions employed in the test were as follows: 
______________________________________ 
Example 6.1: Emulsion according to Example 1.1, undi- 
luted and in various dilutions with water 
cf. Table 3). 
Example 6.2: Emulsion according to Example 1.2, 
neutralized with Ca(OH).sub.2, undiluted 
and in various dilutions with water 
(cf. Table 3). 
Example 6.3: Emulsion according to Example 1.3. 
Example 6.4: Emulsion according to Example 1.4. 
Comparative Example: 
An emulsion was prepared based on 
formulation D, with the emulsifying 
temperature being 45.degree. C. (non-inverted 
emulsion). The resulting emulsion was 
neutralized with diethanolamine. 
______________________________________ 
The test results are set forth in Table 3. 
TABLE 3 
______________________________________ 
Example Dilutions with Water 
100% Corrosion After: 
______________________________________ 
6.1 1:1; 1:3; 1:7; 1:9 
40 days 
6.2 1:1; 1:4 40 days 
6.3 -- 40 days 
6.4 -- 26 days 
Comparison 
-- 13 days 
______________________________________ 
In the Examples 6.1 and 6.2 the period of time as indicated above was 
reached with each of the undiluted emulsion and all of the dilutions 
tested.