Compositions of vapor phase corrosion inhibitors and their use as well as methods for their manufacture

Abstract

The invention relates to corrosion-inhibiting substance combinations capable of evaporation or sublimation, containing at least: (1) substituted 1,4-benzoquinone, (2) aromatic or alicyclic substituted carbamate, (3) polysubstituted phenol, and (4) monosubstituted pyrimidine. These combinations preferably include 1-30 mass % of component (1), 5-40 mass % of component (2), 2-20 mass % of component (3), and 0.5-10 mass % of component (4), each relating to the total quantity of the substance combination. The components can be provided mixed together or dispersed in water, or also pre-mixed in solubilizer that can be mixed with mineral oils and synthetic oils, preferably an arylalkylether alcohol such as, e.g., phenoxyethanol. Such substance combinations can be used as vapor phase corrosion inhibitors in packaging or during storage in closed spaces for protecting common commodity metals such as iron, chrome, nickel, aluminum, copper and their alloys as well as galvanized steels, against atmospheric corrosion.

Claims

1. A corrosion-inhibiting substance combination capable of evaporation or sublimation, comprising at least the following components: (1) 1 to 30 mass % of a substituted 1,4-benzoquinone, (2) 5 to 40 mass % of an aromatic or alicyclic substituted carbamate, (3) 2 to 20 mass % of a polysubstituted phenol, and (4) 0.5 to 10 mass % of a monosubstituted pyrimidine, wherein each mass % relates to a total quantity of the corrosion-inhibiting substance combination.

2. The corrosion-inhibiting substance combination according to claim 1, wherein the substituted 1,4-benzoquinone is selected from the group consisting of tetramethyl-1,4-benzoquinone (duroquinone), trimethyl-1,4-benzoquinone, 2,6-dimethoxy-1,4-benzoquinone (DMBQ), 2,5-dimethoxy-1,4-benzoquinone, 2-methoxy-6-methyl-1,4-benzoquinone, and similarly structured, in particular alkyl- or alkoxy-substituted, substituted 1,4-benzoquinones as well as combinations of the same.

3. The corrosion-inhibiting substance combination according to claim 1, wherein the aromatic or alicyclic substituted carbamate is selected from the group consisting of benzyl carbamate, phenyl carbamate, cyclohexyl carbamate, p-tolyl carbamate and similarly structured substituted carbamates as well as combinations of the same.

4. The corrosion-inhibiting substance combination according to claim 1, wherein the polysubstituted phenol is selected from the group consisting of 5-methyl-2-(1-methylethyl)-phenol (thymol), 2,2-methylene-bis-(4-methyl-6-tert.-butylphenol), 2-tert.-butyl-4-methylphenol, 2.4.6-tri-tert.-butylphenol, 2.6-dimethoxyphenol (syringol) and similarly structured polysubstituted phenols as well as combinations of the same.

5. The corrosion-inhibiting substance combination according to claim 1, wherein the monosubstituted pyrimidine is selected from the group consisting of 2-aminopyrimidine, 4-aminopyrimidine, 2-methylpyrimidine, 4-methylpyrimidine, 5-methoxypyrimidine, 5-ethoxypyrimidine, 4-phenylpyrimidine, 2-phenoxypyrimidine, 4-(N,N-dimethylamino)pyrimidine and similarly structured monosubstituted pyrimidines as well as combinations of the same.

6. The corrosion-inhibiting substance combination according to claim 1, which is adjusted in such a way that all the components evaporate or sublimate with sufficient quantity and speed for vapor corrosion protection within a temperature range of up to +80 C. at relative humidity (RH) of 98%.

7. The corrosion-inhibiting substance combination according to claim 1, which further comprises additional vapor phase corrosion inhibitors other than components (1) to (4), either individually or as a mixture with components (1) to (4).

8. A VCI corrosion protection oil, comprising a mineral oil or synthetic oil and a corrosion-inhibiting substance combination according to claim 1 optionally in a solubilizer, wherein all the components evaporate or sublimate with sufficient quantity and speed for vapor corrosion protection within a temperature range of up to +80 C. at a relative humidity (RH) of 98%.

9. A method for manufacturing a corrosion-inhibiting substance combination capable of evaporating or sublimating, wherein at least the following components are mixed with each other to provide the corrosion-inhibiting substance combination: (1) 1 to 30 mass % of a substituted 1,4-benzoquinone, (2) 5 to 40 mass % of an aromatic or alicyclic substituted carbamate, (3) 2 to 20 mass % of a polysubstituted phenol, and (4) 0.5 to 10 mass % of a monosubstituted pyrimidine.

10. A method of inhibiting corrosion comprising providing the corrosion-inhibiting substance combination according to claim 1 as a volatile corrosion inhibitor (VpCI, VCI) in a form of fine powder mixtures or briquettes (pellets) manufactured from the same during packaging, storage or transport of metal materials.

11. A method of inhibiting corrosion comprising incorporating the corrosion-inhibiting substance combination according to claim 1 into coating materials or coating solutions, for coating carrier materials selected from the group consisting of paper, cardboard, foam and textile fabric.

12. A method of manufacturing a corrosion protection oil, said method comprising providing the corrosion-inhibiting substance combination according to claim 1 in a form of a corrosion protection oil from which vapor phase corrosion inhibitors (VpCI, VCI) are emitted.

13. A method of inhibiting corrosion comprising providing the corrosion-inhibiting substance combination according to claim 1 to protect a metal from corrosion during packaging, storage and transport processes.

14. The method according to claim 13, wherein the metal is a member selected from the group consisting of iron, chrome, nickel, aluminum, copper, alloys thereof and galvanized steel.

Description

DESCRIPTION OF THE INVENTION

(1) The substance combination according to the invention comprises at least the following components:

(2) (1) a substituted 1,4-benzoquinone,

(3) (2) an aromatic or alicyclic substituted carbamate,

(4) (3) a polysubstituted phenol and

(5) (4) a monosubstituted pyrimidine.

(6) Depending on the special area of application the quantity proportions of the various components can vary, and suitable compositions can be easily determined by a person skilled in the art in this field by means of routine trials.

(7) In one preferred embodiment of the invention 1 to 30 mass % of component (1), 5 to 40 mass % of component (2), 2 to 20 mass % of component (3) and 0.5 to 10 mass % of component (4), each relating to the total quantity of the substance combination, are included in the corrosion-inhibiting substance combination.

(8) The substituted 1,4-benzoquinone is here preferably selected from the group comprising tetramethyl-1,4-benzoquinone (duroquinone), trimethyl-1,4-benzoquinone, 2,6-dimethoxy-1,4-benzoquinone (DMBQ), 2,5-dimethoxy-1,4-benzoquinone, 2-methoxy-6-methyl-1,4-benzoquinone, and similarly structured, in particular alkyl- or alkoxy-substituted, substituted 1,4-benzoquinones as well as combinations of the same.

(9) The aromatic or alicyclic substituted carbamate is preferably selected from the group comprising benzyl carbamate, phenyl carbamate, cyclohexyl carbamate, p-tolyl carbamate and similarly structured substituted carbamates as well as combinations of the same.

(10) The polysubstituted phenol is preferably selected from the group comprising 5-methyl-2-(1-methylethyl)phenol (thymol), 2,2-methylene-bis-(4-methyl-6-tert.-butylphenol), 2-tert.-butyl-4-methylphenol, 2.4.6-tri-tert.-butylphenol, 2.6-dimethoxyphenol (syringol) and similarly structured polysubstituted phenols as well as combinations of the same.

(11) The monosubstituted pyrimidine is preferably selected from the group comprising 2-aminopyrimidine, 4-aminopyrimidine, 2-methylpyrimidine, 4-methylpyrimidine, 5-methoxypyrimidine, 5-ethoxypyrimidine, 4-phenylpyrimidine, 2-phenoxypyrimidine, 4-(N,N-dimethylamino)pyrimidine and similarly structured monosubstituted pyrimidines as well as combinations of the same.

(12) With the corrosion-inhibiting substance combination according to the invention the components (1) to (4) can for example be present mixed with each other or dispersed in water, or also pre-mixed in a solubilizer to be mixed with mineral oils and synthetic oils.

(13) This solubilizer is preferably an arylalkylether alcohol, such as for example phenoxyethanol (protectol PE), commonly used for oil preparations, in which the components are present dissolved or dispersed.

(14) The corrosion-inhibiting substance combinations according to the invention can also contain, in addition to components (1) to (4) according to the invention and possibly the solubilizer, substances already introduced as vapor phase corrosion inhibitors, either individually or as a mixture of the same.

(15) The composition of the corrosion-inhibiting substance combinations according to the invention is preferably adjusted in such a way that all components evaporate or sublimate at a quantity and speed that is adequate for vapor room corrosion protection within a temperature range of +80 C., typically within a range of 10 C. to 80 C., at a relative humidity (RH) of 98%.

(16) According to the invention these substance combinations are used directly in the form of corresponding mixtures or introduced according to methods known in themselves during the manufacture of VpCI/VCI packaging materials and oil preparations, so that these packaging materials or oils will act as a VCI depot and the corrosion protection characteristics of the substance combinations according to the invention can develop in a particularly advantageous way.

(17) In one embodiment the corrosion-inhibiting substance combinations are used as a volatile corrosion inhibitor (VPCI, VCI) in the form of fine powder mixtures or briquettes (pellets) manufactured from the same during the packaging, storage or the transport of metal materials.

(18) The corrosion-inhibiting substance combinations can however also be incorporated into coating materials or coating solutions, preferably in an aqueous/organic medium, and/or colloidal composite materials in order to coat carrier materials such as paper, cardboard, foam, textile fabric, textile fleece and similar flat fabrics as part of manufacturing VCI-emitting packaging materials, and to then use the same during packaging, storage and transport processes.

(19) In another embodiment the corrosion-inhibiting substance combinations are used for manufacturing VCI corrosion protection oil, from which vapor phase corrosion inhibitors are emitted (VPCI, VCI).

(20) Such VCI corrosion protection oil preferably comprises a mineral oil or synthetic oil and 0.5 to 5 mass %, more preferably 0.8 to 3 mass %, related to the oil phase, of a corrosion-inhibiting substance combination according to the invention, optionally in a solubilizer, and the composition is adjusted in such a way that all corrosion inhibitor components evaporate or sublimate at a sufficient quantity and speed for vapor room corrosion protection from the VCI oil within a temperature range of up to 80 C., typically within a range of 10 C. to 80 C., at relative humidity of (RH)98%.

(21) The substance combinations according to the invention are primarily used to protect a wide range of common commodity metals, in particular iron, chrome, nickel, aluminum, copper and their alloys as well as galvanized steels, in packaging and during storage in analogue closed spaces against atmospheric corrosion.

(22) The substance combinations according to the invention are nitrite- and amine-free and advantageously consist only of substances that are easy to process without risk with methods known in themselves, and which can be classed as non-toxic and not environmentally harmful in the quantity proportions to be used. They are therefore particularly suitable for manufacturing corrosion protection packaging material that can be used on a large scale in a cost-effective way without an appreciable risk potential.

(23) It is normally expedient for the introduction of the substance combinations according to the invention into VpCI/VCI depots or into packaging material and oils functioning as such to mix individual substances with each other first under water-free conditions, using methods known in themselves, as intensely as possible.

(24) The substance combinations according to the invention are preferably formulated within the following mass proportions:

(25) Component (1): 1 to 30%

(26) Component (2): 5 to 40%

(27) Component (3): 2 to 20%

(28) Component (4): 0.5 to 10%.

(29) The subject of the application is explained in more detail with reference to the following examples. As also evident therefrom the type, quantity proportion of individual components in the mixture according to the invention, and the quantity proportion of the mixture in the respective VpCI/VCI depot will depend only on the manufacturing conditions of the VpCI/VCI-emitting product and the processing excipients required for this, and not on the type of the metal to be protected against corrosion.

Example 1

(30) The following preparation VCI (1) according to the invention was manufactured with the water-free components of the substance combination according to the invention and water-free substances serving as processing excipients:

(31) TABLE-US-00001 10.0 mass % tetramethyl-1,4-benzoquinone (duroquinone) 8.0 mass % benzyl carbamate 6.0 mass % 5-methyl-2-(1-methylethyl)-phenol (thymol), 6.0 mass % 5-ethoxypyrimidine, 20.0 mass % silica gel (SiO.sub.2) 10.0 mass % sodium benzoate, (micronized, d.sub.95 10 m) 8.0 mass % 1-H benzotriazole 1.0 mass % 2-(2H-benzotriazole-2-yl)-p-cresole (tinuvin P, CIBA) 30.0 mass % non-polar PE wax (CWF 201, ALROKO) 1.0 mass % calcium stearate (d.sub.95 8 m)

(32) 0.5 g each of this carefully homogenised powder mixture was filled into a previously produced small pouch made of Tyvek 1057 D (54 g/m.sup.2), a vapor-permeable synthetic film, the opening of which was welded shut, and this pouch was then placed on a floor insert made of PMMA equipped with holes, which served as a base surface of the preserving jar used to receive the test arrangement (volume 1 l) to guarantee a distance of approx. 15 mm. 15 ml of deionized water had previously been dosed under this floor insert. A bar made of PMMA equipped with approx. 5 mm deep notches was positioned in the floor insert next to the filled Tyvek pouch. 4 pieces of carefully cleaned metal test sheets (9050d) mm, each of a different type, were placed upright with approx. 15 inclination from the vertical at a distance of 10 mm from each other. Per preserving jar this was each 1 metal test sheet made of DC 03 steel, cold-rolled, low-carbon, material no. 1.0347, d=0.5 mm, aluminum 99.5, d=0.625 mm (both Q-Panel Cleveland), Cu ETP (MKM Mansfelder Kupfer and Messing GmbH), d=0.5 mm and hot-dip galvanized DX56D+Z140MBO steel (fine grain zinc coating 140 g/m.sup.2-70/70 g/m.sup.2-10 m, ArcelorMittal), d=0.8 mm, respectively.

(33) The preserving jars with the metal test sheets, the deionized water and the substance combination according to the invention were closed tightly, for which a lid with a sealing ring each as well as three tensioning clamps were used. After a waiting time of 16 h at room temperature the so-called development phase of the VCI components could be considered complete inside the vessel. The individual preserving jars were then exposed in a heat cabinet according to DIN 50011-12 at 40 for 16 h, then cooled back to room temperature for 8 h. This cyclic load (1 cycle=24 h) was briefly interrupted after every 7 cycles respectively, the preserving jars opened for approx. 2 minutes to replace atmospheric oxygen that may have permutated and to inspect the surface conditions of the metal sheets. After a total of 35 cycles the exposure was terminated and each test piece visually evaluated outside the preserving jars in detail.

(34) With reference to substance mixture VCI (1) according to the invention 0.5 g portions of a commercially available VCI powder were tested in the same way. This reference VCI powder R1) consisted of

(35) TABLE-US-00002 28.8 mass % dicyclohexylamine benzoate 67.1 mass % cyclohexylamine benzoate 1.5 mass % 1-H benzotriazole 2.6 mass % silica gel (SiO.sub.2)

(36) Results of the Test:

(37) The metal test sheets of the 4 different metals used with substance mixture VCI (1) according to the invention all had an unchanged appearance after 35 cycles for all 4 parallel batches.

(38) Of the batches with the commercially available reference system R1 only the metal sheets made of DC 03 were still free from signs of corrosion after 35 cycles. The metal sheets made of Al 99.5 were coated with a yellowish-brown tarnish layer as well as individual white dot-shaped precipitations on both sides, the metal sheets made of Cu ETP each had dark patches commencing at the top and extending down to the black tarnish layer. Most of the metal test sheet batches made of galvanized steel were already marked with initial patchy areas of white rust in their edge areas after just 7 cycles, which became more pronounced during subsequent test cycles.

(39) The commercially available test system R1 is therefore suitable only for the VCI corrosion protection of iron-based materials. The VCI effect of substance combination VCI (1) according to the invention appears very favorable compared to this for common commodity metals from the example described.

Example 2

(40) A coating agent VCI (2) with the following composition was manufactured through introducing water-free components of the substance combination according to the invention, and further substances required as processing excipients into an aqueous polyacrylate dispersion (PLEXTOL BV 411, PolymerLatex):

(41) TABLE-US-00003 1.0 mass % 2,6-dimethoxy-1,4-benzoquinone (DMBQ) 1.0 mass % benzyl carbamate 1.5 mass % thymol 2.5 mass % 2-aminopyrimidine 55.0 mass % PLEXTOL BV 411 6.0 mass % methylethylene ketone 16.0 mass % deionized water 10.0 mass % sodium benzoate, (micronized, d.sub.95 10 m) 6.0 mass % polymer thickener (Rheovis VP 1231. BASF) 1.0 mass % de-foaming agent (AGITAN 260/265, MNZING Chem.)

(42) and paper strips (kraft paper 70 g/m.sup.2) was coated with a wet application of 15 g/m.sup.2. Immediately after drying the VCI paper VCI (2) according to the invention manufactured in this way in air it was tested for its corrosion-protective effect compared to a commercially available corrosion protection paper serving as a reference system (R2).

(43) According to a chemical analysis the commercially available reference system (R2) with a grammage of 66 g/m.sup.2 contained the following active substances:

(44) TABLE-US-00004 6.2 mass % triethanolamine caprylate 3.4 mass % monoethanolamine caprinate 1.4 mass % benzotriazole 6.7 mass % sodium benzoate

(45) Compared to the substance combination according to the invention in preparation VCI (2) the total proportion of active substance components in the reference system (R2) was therefore approximately three times higher.

(46) As with example 1, the comparative test once again used metal test sheets made of DC 03 steel, cold-rolled, low-carbon, material no. 1.0347, d=0.5 mm, aluminum 99.5, d=0.625 mm (both Q-Panel Cleveland), Cu ETP (MKM Mansfelder Kupfer and Messing GmbH), d=0.5 mm and hot-dip galvanized steel (fine grain zinc coating 140 g/m.sup.2-70/70 g/m.sup.2-10 m, ArcelorMittal), d=0.8 mm. The test ritual once again equaled that described for Example 1. The only difference here was that individual preserving jars were now lined with VCI paper in place of the VCI powder mixture provided in a Tyvek pouch. This was achieved with 1 circular cut-out each with a diameter of 8 cm at the bottom, a sleeve of 1328 cm and once again a circular cut-out with a diameter of 9 cm for the lid, always with the coated side facing the insert of metal test sheets to be protected against corrosion. Once the 15 ml deionized water had once again been added and the notched bar had been placed on the bottom together with the 4 metal test sheets the preserving jar was closed and the climate load applied as described in Example 1.

(47) A waiting time of 16 h at room temperature was initially once again stipulated as a so-called development phase for the VCI components inside the closed vessel. This was again followed by the exposure of individual preserving jars in a heat cabinet according to DIN 50011-12 at for 16 h at 40 C., then for 8 h at room temperature. This cyclic load (1 cycle=24 h) was briefly interrupted after every 7 cycles, the preserving jars opened for approx. 2 minutes to replace atmospheric oxygen that may have permutated and to inspect the surface conditions of the metal sheets. After a total of 35 cycles the exposure was terminated and each test piece visually evaluated outside the preserving jars in detail.

(48) Results of the Test:

(49) The various metal test sheets used together with the VCI paper VCI (2) manufactured on the basis of the substance mixture according to the invention all appeared unchanged for all 4 parallel batches after 35 cycles.

(50) Only the metal test sheets made of DC 03 of the batches with the commercially available reference system R2 remained free from visible rust products during the 35 cycles, but were characterized by a more matt appearance compared to their starting condition. The metal test sheets made of Al 99.5 showed a patchy dark tarnish film that could not be wiped off.

(51) The metal test sheets made of galvanized steel displayed initial traces of white rust at their edges after just 7 cycles, which clearly grew larger across the area as the load continued. The appearance of the metal test sheets made of Cu ETP was uneven after 35 cycles. Whilst the appearance of the sheet metal surfaces of 2 batches remained unchanged, parts of the affected sheet metal pieces of the remaining batches were coated with a thin black tarnish layer that could not be wiped off. This finding could not be ruled out during repeated testing.

(52) Reference system R2 is therefore suitable only for the VCI corrosion protection of base iron materials, whilst the active substances emitted from reference system R2 are clearly adsorbed in such different specific concentrations that defects in the VCI corrosion protection effect result with Cu base materials. Compared to this the VCI paper VCI (2) manufactured on the basis of the substance combination according to the invention developed, as the example shows, reliable VCI characteristics even under extreme moist air conditions during long-term use compared to common commodity metals.

Example 3

(53) A corrosion protection oil VCI (3) with the following composition was manufactured through introducing water-free components of the substance combination according to the invention, and further substances required as processing excipients into a commercially available mineral oil:

(54) TABLE-US-00005 0.6 mass % duroquinone 0.1 mass % benzyl carbamate 0.2 mass % thymol 0.2 mass % 4-phenylpyrimidine 92.7 mass % mineral oil with thixotropy agent normal wax (BANTLEON base oil LV 16-050-2) 6.0 mass % phenoxyethanol 0.2 mass % tolyltriazole (TTA, COFERMIN)

(55) After intensive stirring the VCI oil VCI (3) resulted as an optically clear fluid, characterized by a mean cinematic viscosity of 253 mm.sup.2/s (20 C.).

(56) A commercially available VCI oil with an approximately identical mean viscosity was tested in the same way as a reference for the VCI oil VCI (3) according to the invention. According to a chemical analysis this reference VCI oil R3, also formulated on the basis of a mineral oil, contained the following active substances:

(57) TABLE-US-00006 11.3 g/kg dicyclohexylamine 8.2 g/kg diethylaminoethanol 15.1 g/kg 3.5.5 trimethyl hexanoic acid 3.6 g/kg benzoic acid.

(58) As with example 1, the comparative test once again used metal test sheets made of DC 03 steel, cold-rolled, low-carbon, material no. 1.0347, d=0.5 mm, aluminum 99.5, d=0.625 mm (both Q-Panel Cleveland), Cu ETP (MKM Mansfelder Kupfer and Messing GmbH), d=0.5 mm and hot-dip galvanized steel (fine grain zinc coating 140 g/m.sup.2-70/70 g/m.sup.2-10 m, ArcelorMittal), d=0.8 mm. The test ritual once again equaled that described for Example 1.

(59) The major difference now consisted of the notched bars made of PMMA serving as test piece frames now being equipped with 3 pieces each of one and the same test piece type, and the centrally positioned metal test sheet being covered on both sides with the VCI oil to be tested, whilst the metal test sheets each arranged as a distance of approx. 10 mm to the side were not oiled prior to insertion. This allowed the recording of the extent to which the oil film applied to the central metal test sheet is capable of protecting the metal substrate directly covered by the same as well as the two metal test sheets not coated with an oil film against corrosion through emission of the VCI component via the vapor phase inside the closed preserving jar. in practice

(60) Each preserving jar (volume 1 l) therefore now contained the notched PMMA bar equipped with the 3 metal test sheets in question, consisting of one and the same material, on the holed floor insert and the 15 ml deionized water dosed under the same. After closing the individual preserving jars the climate load was applied as described in Example 1.

(61) A waiting time of 16 h at room temperature was initially once again stipulated as a so-called development phase for the VCI components inside the closed vessel. This was again followed by the exposure of individual preserving jars in a heat cabinet according to DIN 50011-12 for 16 h at 40 C., then for 8 h at room temperature. This cyclic load (1 cycle=24 h) was once more briefly interrupted after every 7 cycles, the preserving jars opened for approx. 2 minutes to replace atmospheric oxygen that may have permutated and to inspect the surface conditions of the metal sheets. After a total of 35 cycles the exposure was terminated and each test piece visually evaluated outside the preserving jars in detail.

(62) Results of the Test:

(63) The appearance of the different metal test sheets, of which one each was coated with the VCI oil according to the invention, namely VCI (3), together with 2 identical metal test sheets not coated with oil arranged at a distance in a preserving jar, and which were exposed to the cyclic moist air climate, was unchanged for the 3 parallel batches after 35 cycles. The VCI oil VCI (3) according to the invention thus guaranteed good corrosion protection for the metal substrates in question in direct contact as well as for the metal test sheets not covered with the oil inside the closed preserving jar through VCI components emitted via the vapor phase.

(64) Of the batches with the commercially available reference system R3 the metal test sheets made from low-alloy DC 03 steel showed no signs of corrosion either in the oiled or in the non-oiled condition after 35 cycles. However, for the metal test sheets made of Al 99.5, Cu ETP and galvanized steel this was the case only for the oiled condition.

(65) The metal test sheets made from Al 99.5 in a non-oiled condition were consistently coated with a brown tarnish layer after 35 cycles, which was usually more pronounced at the edges of the metal sheets. On the metal test sheets made of Cu ETP used in a non-oiled condition patches with a dark grey to black appearance were observed in the upper edge area after just 7 cycles, which transformed into relatively even tarnish layers that could not be wiped off after 35 cycles.

(66) The most obvious appearance of changes occurred on the non-oiled metal test sheets made of the fine grain galvanized steel. Localized patches of white rust were observed here after just 7 cycles of moist air treatment, preferably in the edge areas, which transformed into patches of a light grey to white appearance as the moist air load continued.

(67) Reference system R3 can therefore be used for the corrosion protection of common commodity metals only in direct contact. The active substances emitted from the same in the gaseous phase are however suitable only for the VCI corrosion protection of iron-based materials. The VCI oil VCI (3) according to the invention however guarantees, as the example shows, pronounced multi-metal protection in that it has proven reliable VCI characteristics in the presence of common commodity metals even under extreme moist air conditions during long-term trials.