EP0976851A1 - Vapour phase corrosion inhibitors, their use and method of producing the same - Google Patents

Abstract

A sublimable corrosion inhibitor consists of a combination of (1) aromatic mercaptothiazole or triazole, (2) water-insoluble, poly-substituted phenol and (3) L-ascorbic acid or one of its salts. An Independent claim is also included for a process for the production of corrosion inhibiting combinations by mixing the above components together.

Description

The invention relates to combinations of substances that act as vapor phase corrosion inhibitors (volatile corrosion inhibitors, VCI) to protect especially non-ferrous metals or non-passivable metals, such as copper, silver, manganese, magnesium and their alloys against atmospheric corrosion are usable.

It is already well known that corrosion inhibitors, which tend to sublime in powder form under normal conditions and via the gas phase to metal surfaces to be protected can get temporary corrosion protection of metal objects inside closed rooms, e.g. in packaging or showcases can be used.

These vapor phase inhibitors (vapor phase inhibitors, VPI) or volatile corrosion inhibitors (volatile corrosion inhibitors, VCI) according to the type of protective metal selected and packaged as a powder Pouch made of a material that is used for the vaporous VPI's is permeable, used (see e.g. H.H. Uhlig, corrosion and corrosion protection, Akademie-Verlag Berlin, 1970, p. 247 - 249; K. Barton, protection against atmospheric corrosion; theory und Praxis, Verlag Chemie, Weinheim 1973, p. 96 ff. or I.L. Rozenfeld, corrosion inhibitors (Russian) Izt-vo Chimija, Moskva 1977, pp. 320 ff).

Modern packaging for corrosion protection included the VCI either in tablet form within porous Foam capsules or as a fine powder within polymers Carrier materials. For example, US 3,836,077, US 3,967,926, US 5,332,525, US 5,393,457, US 4,124,549, US 4,290,912, US 5,209,869, JP 4,124,549, EP 0.639.657 and DE-OS 3.545.473 different variants proposed, the VCI in capsules or air-permeable plastic films to bring in, either by storage in by cutting a foam created cavities with subsequent Cover the same with a gas permeable Material or by adding the VCI to the spray or Bubble extrusion provided polymer melt, so that a packaging material (Foil or hard material) arises from which because of structure-related porosity the VCI components continuously can sublimate.

Attempts have also been made to use the VCI while foaming of polymeric solids, which e.g. in JP 58.063.732, US 4,275,835 and DD 295,668. Farther can VCI-containing packaging be produced, by placing the VCI components in a suitable solvent solved and on the packaging in question be applied. Procedures of this kind with different Active ingredients and solvents are e.g. in JP 61.227.188, JP 62.063.686, JP 63.028.888, JP 63.183.182, JP 63.210.285, DE-PO 1521900 and US 3,887,481.

However, since the VCI packaging materials produced in this way are the active ingredients usually only loosely in the structural cavities of the carrier material paper, cardboard, foam, etc. contain, there is a risk of mechanical spreading and trickling out of the active ingredient particles, so that not can be ensured that the pretreated carrier materials at the time of their application for corrosion protection the required specific surface concentration at all own at VCI.

To eliminate this disadvantage, DE-PS 19708285 described a corrosion-inhibiting composite material that from a mixture of a metal oxide sol, the sublimable Corrosion inhibitors and other additives exist and a firmly adhering, sufficiently porous on the carrier material Forms gel film of the metal oxides and additives used, from which the corrosion inhibitors (VCI) with a uniform, long-term emission rate are given.

Chemical substance which decreases the corrosion rate when present in the corrosion system at a suitable concentration whithout significantly changing the concentration of any other corrosive agent; the use of the term inhibitor should be qualified by the nature of the metal and the environment in which it is effective" vgl. "Corrosion of metals and alloys - Terms and definitions"; ISO 8044 - 1986).According to the ISO definition, a corrosion inhibitor is a "chemical substance that, when present with a suitable concentration in a corrosive system, reduces the rate of corrosion without significantly changing the concentration of any other corrosive agent. The use of the term inhibitor is intended by the type of metal and the environment. " (

Chemical substance which decreases the corrosion rate when present in the corrosion system at a suitable concentration whithout significantly changing the concentration of any other corrosive agent; the use of the term inhibitor should be qualified by the nature of the metal and the environment in which it is effective "see" Corrosion of metals and alloys - Terms and definitions "; ISO 8044 - 1986).

The main principle of using VCI is maintenance, or reinforcement of the inherent, mostly only limited protective Primary oxide layer that can be touched on any metal with the atmosphere very quickly, but purely visually is imperceptible without optical aids (K. Barton, loc.cit.).

With regard to the type and properties of the primary oxide layer mentioned can the known metals and their alloys can be divided into two categories, those where for the maintenance of the protective primary oxide layer a sufficiently strong oxidizing agent is required and those where the passive oxide layer just because of the action of Oxidizing agents such chemical and / or structural Undergoes changes that adhere to the substrate and so that the corrosion protection effect is lost.

In the case of iron materials, the primary oxide layer mainly consists of an Fe (III) oxide. If the metal surface is moistened, as is already the case, for example, when a condensed water film is formed without a sufficiently strong oxidizing agent being present, the metal begins to corrode by converting these oxides into Fe (II) compounds, e.g. : Fe ₂ O ₃ + H ₂ O + 2 H ⁺ + 2 e ^- → 2 Fe (OH) ₂ and for the anodic corrosion of the substrate metal: Fe + 2 H ₂ O → Fe (OH) ₂ + 2 H ⁺ + 2 e ^- act cathodically.

To avoid this, the action of one is sufficient strong oxidizing agent required. Nitrites and the relatively volatile dicyclohexylammonium nitrite have therefore been used as vapor phase inhibitors for over 50 years applied (see: Uhlig, Barton, Rozenfeld, loc. cit.) and are part of VCI compositions in numerous Called patents (e.g. US-PS 2.419.327, US-PS 2,432,839, U.S. Patent 2,432,840, U.S. Patent 4,290,912, U.S. Patent 4,973,448, JP 02085380, JP 62109987, JP 63210285 A, DE-PS 4040586).

Metals, their primary oxide layer against further oxidation sensitive, e.g. Copper, silver and manganese.

In the case of Cu and Cu base materials, for example, the primary oxide film mainly consists of the oxide Cu ₂ O. This film is only stable in aqueous media free of oxidizing agents, regardless of the pH. Under the influence of oxygen in moist air, the oxide CuO is formed relatively quickly, perceptible as a black deposit, which due to its crystal lattice dimensions cannot grow together with the metal substrate (no epitaxy) and therefore does not protect against corrosion. The following can therefore be formulated for the initial reactions of atmospheric corrosion:

In an effort to create VCI packaging that not just for a certain type of metal, but multivalent VCI combinations have been tried formulate that not only amine nitrites but also components contain the heterogeneous casting materials and just such Metals, such as the copper and silver base materials from corrosion can protect.

In this framework it was proposed to use nitrites with others substances capable of sublimation, such as the salts of medium strength to weak, saturated or unsaturated carboxylic acids combine, cf. e.g. US 2,419,327, US 2,432,839, 2,432,840, DE 814.725. Protection of the usual Al, Sn and Zn materials, but on the other hand the corrosion of those also in the relevant packaging Cu and Mg materials promoted more.

The reason for this is seen in the existence of nitrite, which not only can oxidize the primary oxide layer of copper, but also reduces itself to ammonia, NH ₃ , when acting as an oxidizing agent. On the one hand, this NH ₃ can convert the oxidic passive layer of the copper metals into soluble complexes and, on the other hand, can cause such a high level of alkalization on Mg surfaces when moistened that a soluble magnesium-hydroxo complex is formed from the MgO film present there. In both cases this is associated with the loss of the passive state and therefore incipient corrosion (see. Also AD Mercer, Proc. Of the 7 ^th Europ. Symp. On Corrosion Inhibitors, Ann. Univ. Ferrara / Italy, NS, Sez. V , Suppl. N. 9. (1990), 449 pp.).

To overcome this disadvantage, VCI systems have been proposed for the corrosion protection of any metal combination should be usable, but without nitrite and Amines have to get by by just using combinations organic carboxylic acids and their salts are built up, such as e.g. in DE-OS 877.086, CS-PS 124.738 and PL-PS 96.548. It results but generally no reliable protection against corrosion, if only because the sublimation rate is comparatively low is and with increasing relative humidity even further is reduced.

To overcome this disadvantage, it has been proposed to use salts, how to combine the benzoates with a volatile amine and thus the exit speed of the VCI from the as Accelerate depot-serving packaging. So be e.g. in U.S. Patent 4,124,549 the combinations of dicyclohexylamine with benzoic acid and / or caprylic acid as well as the analog Combinations called monoethanolamine laurate and morpholine benzoate, while DE-OS 3219360 claims the morpholine caprylate. JP 61227188 specifically mentions salts of tertiary amines, like dimethylethanolamine caprylate mixed with hexamethylenetetramine, JP 09228078, on the other hand, cyclohexyl-cyclohexamine, Cyclohexyl-benzenamine and other homologues, moreover, in Propanol dissolved on paper can be applied as a carrier material can or even as an easily vaporizable corrosion inhibitor Liquid should be usable. Instead of Combination of carboxylic acid salts with amines are described in DE-OS 3210360 Mixtures of fatty alcohol phosphates with volatile Amines named as VCI, e.g. Mixtures of di- [2-ethylhexyl] hydrogen phosphate and di- [9-octadecenyl] hydrogen phosphate with morpholine or morpholine caprylate.

However, practical applications of such systems have so far remained off, probably mainly because laboratory tests already have the evidence provided that especially for multi-metal combinations no reliable corrosion protection effects can be achieved, because, on the one hand, the usual types of steel in particular not be protected against corrosion if the VCI system does not contains acting as passivator oxidant and others are due to the relatively high alkalization that due to the substances mentioned on metal surfaces in moist air which is set on copper, aluminum, zinc and magnesium existing primary oxide layers complexed and thus the The passive state is abolished.

In addition, copper and silver materials are not protected from corrosion anyway if the usual contaminations of industrial air (e.g. carbon dioxide, sulfur dioxide, hydrogen sulfide) are present in the atmosphere of the interior of the packaging in question. These metals are also characterized by the fact that they have a higher affinity for sulfidic sulfur than for oxygen and that the blackish-brown tarnish film on silver is attributable to the formation of the silver sulfide Ag ₂ S.

Specifically to protect copper and copper alloys from atmospheric Corrosion has been in use for a long time (see e.g. Barton, Mercer, loc.cit.). However, since the Sublimation tendency of this connection is relatively low proposed in DE-PS 1182503 and US-PS 3,295,917, the depot of this VCI initially to a higher temperature (up to approx. 85 ° C) and at the same time the metal objects, on which the condensation is to take place. In US Pat. Nos. 2,941,953 and 3,887,481, on the other hand, are impregnation described by paper with benzotriazole and / or tolyltriazole. There are organic solvents, such as tetrachlorethylene used and it is prescribed the metal parts to be protected as closely and tightly as possible with the impregnated in this way VCI packaging to wrap the distance between VCI depot and metal surface to be protected as low as possible to keep. However, this technology has the one already mentioned Disadvantage that the active ingredient is in the form of very fine powder particles adheres only slightly to paper and sprinkles easily can, so that the anti-corrosion properties of this packaging cannot be designed reliably.

The sublimation tendency of benzo- and tolyltriazole from VCI depots also increases if at the same time other sublimable ones Solids are incorporated in powder form. For this purpose EP 0662527 name mixtures of benzotriazole with cyclohexylamine benzoate and ethylamine benzoate or with anhydrous Sodium molybdate and dicyclohexylamine nitrite, U.S. Patent 4,051,066 and U.S. Patent 4,275,835 mixtures of benzotriazole with ammonium and Amine molybdate, amine benzoates and nitrates, U.S. Patent 4,973,448 mixtures of benzotriazole with organic carbonates, Phosphates and amines, JP 62063686 and JP 63210285 A. finally mixtures of benzotriazole with alkali and amine salts aromatic carboxylic acids.

Combinations of benzo, tolyl or methyl benzotriazole with other nitrogen-organic volatile solids e.g. in JP 62109987, JP 61015988, DD-PS 268978 and DD-PS 298662. The disadvantage is that all ammonium ions components containing amine because of their more or less pronounced tendency to form complexes with metal ions Protective effect of triazoles especially against non-ferrous metals lower again. In addition, the designated amines and Ammonium compounds highly hydrophilic. VCI depots, such Containing substances therefore tend to absorb more water. It usually occurs as a result of their hydrolysis to a greater decrease in their tendency to sublimate what inevitably a reduction in the corrosion protection effect Consequence.

For these reasons, e.g. in JP-PS 56122884 A alternatively proposed to dispense with amine-containing admixtures and only use triazoles. But in order not to wait until the triazole from the VCI depot Packaging sublimates and on the metal surface to be protected adsorbed, it is suggested these inhibitors dissolved in a suitable halogenated hydrocarbon spray from spray bottles directly onto the metal parts. These spray liquids are described in JP-PS 56122884 A. especially for the corrosion protection of copper materials and others Alloy materials in electronic equipment and printed Microelectronic circuits recommended. This kind the use of corrosion inhibitors does not benefit more the advantages of the principle of action of the volatile corrosion inhibitors (VCI), but has the disadvantage that in addition to the Packaging (encapsulation) process of the electronic concerned Components with spraying an additional step becomes necessary.

To take advantage of the use of VCI and the inhibitor effect the triazole structure is described in JP-PS 03079781 proposed instead of the triazole / amine combinations to use only alkylaminotriazoles. In fact have the explicitly listed substances 3-amino-1.2.4-triazole and 3-amino-5-methyl-1.2.4-triazole a higher volatilization rate, but above all not so with copper and silver significant anti-corrosion effect, such as benzo- and tolyltriazole.

As an alternative to the triazoles, the DD 284255 specifies a general for the corrosion protection of non-ferrous metals the use of indole or Imidazole derivatives. However, neither information on the The type and concentration of such additives is still being made Protection effect proven by concrete data.

The object of the invention is compared to those listed above Disadvantages of conventional corrosion inhibitors improved sublimation-capable, corrosion-inhibiting substances and Specify combinations of substances, in particular those under the practically interesting climatic conditions within of technical packaging and analog closed Clear with sufficient speed from an appropriate Sublimate the depot and after adsorption and / or condensation on the surface of metals in this room ensure conditions there, especially those classified as non-passivable non-ferrous metals, such as copper, Silver, manganese, magnesium and their base alloys are effective be protected against atmospheric corrosion. The task The invention furthermore relates to processes for the production or Processing of such substances and combinations of substances for the Specify manufacture of improved VCI packaging.

These tasks come with combinations of substances and procedures 10 solved the features of claim 1 and 10 respectively. Advantageous embodiments and uses of the invention result from the subclaims.

(1) einem aromatischen Mercaptothiazol oder Triazol

(2) einem wasserunlöslichen, mehrfach substituierten Phenol,

und (3) L-Ascorbinsäure oder einem ihrer Salze.

Surprisingly, these objects were achieved according to the invention in particular by providing combinations of substances which consist of the following components:

(1) an aromatic mercaptothiazole or triazole

(2) a water-insoluble, multi-substituted phenol,

and (3) L-ascorbic acid or one of its salts.

In coordination with components (1) to (3) may also be necessary a suitable carboxylic acid / salt pair is added as component (4) his. The carboxylic acid / salt pair is chosen such that after its sublimation and condensation on metal surfaces there the pH of a condensed water film in the area 4.8 ≤ pH ≤ 6.5 is stabilized (buffered).

According to the invention, these combinations of substances are directly in shape appropriate powder mixtures used or after known methods in the production of VCI packaging incorporated so that this packaging act as a VCI depot and the corrosion protection properties the combinations of substances according to the invention particularly can unfold advantageously.

The combinations of substances according to the invention are mainly used the metals classified as non-passivable, such as. Copper, silver, manganese, magnesium and their alloys in packaging and during storage in analog closed Protect rooms from atmospheric corrosion.

The invention particularly relates to a corrosion-inhibiting Material consisting of a component, the one aromatic mercaptothiazole or triazole is and above all Surfaces of non-ferrous metals are specifically adsorbed, another component that is a multiply substituted Phenol is, and because of its properties, not in water soluble, but easy to adsorb on solids, including all further components of the substance combinations according to the invention hydrophobic and because of its relatively high sublimation pressure as a carrier material over the gas space to be protected Transported metal surface, a component that L-ascorbic acid or one of their salts and because of their property, to act as an antioxidant, surprisingly also the attack of atmospheric oxygen on metal surfaces and thus inhibiting the corrosion process, and finally as another Component a suitable carboxylic acid / salt system, which in condensed water films on metal surfaces the pH value in the range 4.8 ≤ pH ≤ 6.5, where the previously mentioned components the combinations of substances according to the invention their corrosion protection effect can develop optimally, stabilized.

The combinations of substances according to the invention advantageously exist exclusively from non-toxic, the environment not hazardous substances and are based on methods known per se easy and safe to process. That is why they are particularly suitable for the production of anti-corrosive packaging, which is inexpensive on a large scale and without any risk potential are applicable.

For the introduction of the material combinations according to the invention in VCI depots or in packaging that functions as such it is advisable to start with the individual substances first finely ground to achieve particle sizes ≤ 20 µm, then dry thoroughly and finally according to known Mixing methods as intensively as possible.

Komponente (1): 10 bis 40 %

Komponente (2): 10 bis 40 %

Komponente (3): 10 bis 40 %
oder bei Einsatz aller vier Komponenten

Komponente (1): 10 bis 40 %

Komponente (2): 10 bis 35 %

Komponente (3): 10 bis 30 %

Komponente (4): 10 bis 30 %

The substance combinations according to the invention should be formulated within the following mass ratios:

Component (1): 10 to 40%

Component (2): 10 to 40%

Component (3): 10 to 40%
or when using all four components

Component (1): 10 to 40%

Component (2): 10 to 35%

Component (3): 10 to 30%

Component (4): 10 to 30%

The subject of registration is illustrated by the examples below explained in more detail. As can be seen from this, judge Type, quantitative proportion of the individual components in the invention Mixture and proportion of mixture in the respective VCI depot both according to the metal to be protected and the manufacturing conditions of the relevant VCI packaging material.

Example 1 :

The following combination of substances according to the invention was prepared from the predried, powdery substances: 25 mass% Mercaptobenzthiazole 20 mass% 2.6-di-tert. butyl-4-methoxyphenol 15 mass% L-ascorbic acid 12 mass% Sodium benzoate 8 mass% Benzoic acid 20 mass% inert filler (silica gel)

10 g of this mixture was spread widely in a flat dish and put it in a larger glass jar. In this flat rectangular glass jar was at the same time A clean sheet is placed next to each other without contact (30 x 50) mm made of Cu, Ms63, MnFe20, Ag 99 and MgAl3, free of Tarnishing films and deposits. Through the anti-reflective Glass sealed top of this jar could condition the sheets were assessed by measuring the gloss behavior become. The measuring system "GLOSScomp / OPTRONIK Berlin" used for this registers the direct and diffuse parts Reflection composite reflection curve whose peak height P / dB sufficient for the respective properties of the metal surface is representative.

One due to the first tarnishing films or other signs of corrosion conditional loss of gloss compared to the fixed Initial state always noticeable in lower values of P. To indicate that such changes have taken place have the eye purely visually without optical aids only hardly perceivable, it is sufficient to determine ΔP /%.

The vessel with the metal samples and the substance combination according to the invention was tightly closed and the starting data P / dB of the individual metal samples were determined through the top. After 5 hours, the inlet and outlet connected to the side walls of the vessel was opened to a reservoir which in turn contained a saturated disodium hydrogenphosphate solution. The air above this solution was then circulated by means of a circulation pump through the vessel with the metal samples and the mixture of substances according to the invention, so that a uniform rel. Humidity of (RH) ≈ 95%. At regular intervals of approximately 5 hours, ΔP /% was recorded for each metal sample stored. All of the metals identified were through during a test period of 25 d 0 ≤ ΔP /% ≤ + 0.5 expelled. It follows that their shiny metallic appearance remained unchanged in the moist air saturated with the combination of substances according to the invention.

If similarly pretreated metal sheets of these metals were exposed alone, i.e. in clean moist air without a combination of substances according to the invention, then with increasing exposure time t _E a reduction in gloss could be observed, which was characterized by negative ΔP values /% and depending on the type of metal was: ΔP /% t _E / h Cu Ms63 MnFe20 Ag99 MgAl3 8th -0.4 -0.2 -0.9 -0.2 -0.3 24th -1.6 -1.0 -2.4 -0.5 -1.3 48 -2.1 -1.4 -3.6 -1.1 -3.5

From this example, the advantageous effect of the invention Combination of fabrics clearly.

Example 2:

The following combination of substances according to the invention was prepared from the predried, powdery substances: 28.5 mass% Benzotriazole 17.3 mass% 2.6-di-tert. butyl-4-ethylphenol 17.1 mass% L-ascorbic acid 28.5 mass% Potassium hydrogen phthalate 8.6 mass% Phthalic acid and made a 5% solution in ethanol (90%) / water.

An aqueous-alcoholic acid sol which, according to DE-PS 19708285, had been obtained from 50 ml of tetraethoxysilane, 200 ml of ethanol and 100 ml of 0.01N hydrochloric acid by stirring at room temperature for 20 hours and then 4.2% solids content in 70% ethanol at pH ≈ 4 was mixed with 50 ml of the 5% solution of the combination of substances according to the invention and thus paper (kraft paper 70 g / m ² ) was coated by means of wet rolling. Immediately after the VPI paper thus produced had been dried in air, it became, in comparison with a commercially available corrosion protection paper serving as a reference system (R1), by the method which is customary in practice Testing the corrosion-protecting effect of VPI packaging materials (see. Packaging Review "5/1988, p. 37 ff) tested for its anti-corrosion properties. After reference to chemical analysis, the reference system (R1) contained the active ingredients dicyclohexylamine, cyclohexylamine, benzotriazole and sodium molybdate, the total proportion being approximately comparable to that of the combination of substances according to the invention Test specimens of the metals Cu, MnFe20 and MgSi2 were used, which were pretreated in accordance with regulations and their initial state immediately before use in the test vessel was characterized with the gloss measurement system "GLOSScomp" mentioned in Example 1. Subsequently, these test specimens were used alone or together with the VPI to be tested. The packaging material was placed in tightly sealed containers and the conditions set there which resulted in water condensation on the surface of the test specimens The intended purpose of the grinding surface of the test specimens was to be checked visually regularly for the existence of signs of corrosion.

The blank samples of Cu used without the use of VPI showed a slight blackening after 4 d, the samples of the Alloy MnFe20 already had a thin, dark brown after 48 h Tarnish film while the surface of the Mg material appeared slightly matt. Those exposed along with the R1 paper Test specimens made of Cu showed stronger ones after only 24 h Discoloration, at the same time the samples of the MnFe were more intense tarnished dark brown and the magnesium alloy had the first little whitish blooms. When using the had the paper combination according to the invention carrying paper all test specimens still look flawless and even by means of of the very sensitive registration measuring system GLOSScomp became clear from values in the range 0 ≤ ΔP /% ≤ +0.5, that there are no changes on the test specimen surfaces had taken place. To date, there have been none VPI packaging materials, their usability for manganese and / or magnesium materials has been explicitly highlighted. Those Packaging means using an inventive Fabric combinations have been prepared, close according to of the example described, this gap is therefore the first time.

Example 3:

The following combination of substances according to the invention was prepared from the predried, powdery substances: 22.5 mass% Mercaptobenzthiazole 6.0 mass% Tolyltriazole 17.5 mass% 2.6-di-tert. butyl-4-methylphenol 12.1 mass% L-ascorbic acid 8.5 mass% Calcium ascorbate 8.6 mass% Calcium stearate 8.3 mass% Stearic acid 6.2 mass% Zinc oxide (filler) 7.8 mass% Calcium carbonate (slip) 2.5 mass% Silica gel (antiblock)

35 mass% of this mixture became the usual with 65 mass% LD-PE mixed and processed into a VCI masterbatch. For this purpose, an extruder Rheocord 90 (HAAKE) with counter-rotating Twin screw used. With the screw speed from 65 to 80 rpm was at cylinder temperatures around 150 ° C and one Nozzle temperature of 158 ° C extruded and cold cut granulated. This granular VCI masterbatch was made by Blown extrusion processed into VCI films, including the extruder was to be equipped with a single screw and ring nozzle. To Mix 3 mass% of the VCI masterbatch with 97 mass% a common LD-PE granulate was used at cylinder temperatures of 175 ° C and a nozzle outlet temperature of 180 ° C, the screw speed between 80 and 85 rpm varied. It became a VCI film with a medium one Layer thickness of 80 microns.

The so using a combination of substances according to the invention VCI film produced was processed into bags (cut and welding the superimposed side seams). Sheets the materials Cu, Ms63, MnFe20, Ag99 and MgAl3 were Degreasing, drying and characterization using GLOSScomp individually sealed in such bags. That way packaged alloys Ms63, MnFe20 and MgAl3 were made in one Climatic chamber cyclically loaded with moist air in accordance with IEC 68-2-30. A 24-hour cycle consists of the following stages: 6 hours 25 ° C and (RH) = 98%, 3 h heating phase from 25 to 55 ° C at (RH) = 95%, 9 h 55 ° C at (RH) = 93% and 6 h cooling phase from 55 to 25 ° C at (RH) = 98%. After each cycle there is one visual assessment of the surface condition of the test sheets through the transparent film material. After cancellation a gloss measurement was also carried out on the load, to determine ΔP /%. At the same time, similar ones Test specimen once in pure polyethylene film (R2) the same Layer thickness and still in a commercially available VCI film material packed as a reference system (R3) and also deposited in the climate cabinet. (R3) contained according to chemical analysis the active substances ammonium molybdate, triethanolamine and benzotriazole.

MnFe20 appeared in drug-free polyethylene film (R2) already after 3 cycles slight brown discolouration, on MgAl3 after 5 cycles of first whitish excretions and on Ms63 after 12 Cycles first dark spots. For the samples packed in (R3) was no inhibition of corrosion with MnFe20 and MgAl3 noticeable, the described signs of corrosion after same stress time even more intense in some cases. Ms63 was stained after 16 cycles.

The samples packaged in the VCI film containing the substance combination according to the invention still had a completely perfect appearance after 25 cycles. The gloss measurements carried out after termination of this climatic stress yielded values in the range 0 ≤ ΔP /% ≤ +0.5 , which also gradually confirms this statement.

The contained in the combination of substances according to the invention VCI foil welded materials Cu and Ag99 were made in one closed glass vessel over saturated disodium hydrogenphosphate solution, which also contains 0.03 mass% of ammonium sulfide contained, stored. This solution poses As is well known, a rel. humidity of (RH) = 95% and also emits low Proportions of hydrogen sulfide. The one in pure polyethylene packed metals had in this hydrogen sulfide Wet air already after 8 hours a thin, dark tarnish film. The reference film (R3) delayed this effect Ag99 minimal, so that a first darkening takes place only after about 12 h was found. With Cu in (R3) it took about 48 h until the first changes were visually noticeable. The invention manufactured VCI foils also guaranteed 20 d load their full corrosion protection effect, recognizable again on the flawless appearance of the corresponding Test specimen.

Namely to protect silver against the formation of sulfidic Tarnish layers are with the combination of substances according to the invention for the first time one for transport and storage effective and easy to use solution provided. 500 Piece of silver blanks intended for minting coins were placed individually on cardboard and through a skin process with the substance combination according to the invention Foil packed tightly. After a storage period of 3 months the condition of all the blanks is still completely perfect, while before when using film (R3) after the same time about 20% the parts are already marked by a dark tarnish film were and had to be discarded.

Claims (18)

Sublimation-capable, corrosion-inhibiting combination of substances, which contains: (1) aromatic mercaptothiazole or triazole, (2) water-insoluble, multi-substituted phenol, and (3) L-ascorbic acid or one of its salts. Corrosion-inhibiting combination of substances according to claim 1, which further contains (4) a carboxylic acid / salt pair. Corrosion-inhibiting combination of substances according to claim 1, for the 10 to 40% component (1), 10 to 40% component (2) and 10 to 40% component (3) are contained. Corrosion-inhibiting combination of substances according to claim 2, in the 10 to 40% component (1), 10 to 35% component (2), 10 to 30% component (3) and 10 to 30% component (4) are included. Corrosion-inhibiting combination of substances according to claim 2 or 4, in which the carboxylic acid / salt pair is selected in such a way after sublimation and condensation on metal surfaces there the pH of a condensed water film in the Range 4.8 ≤ pH ≤ 6.5 (based on 25 ° C). Corrosion-inhibiting combination of substances according to claim 2 or 4, in which as the carboxylic acid / salt pair benzoic acid / Na benzoate, Phthalic acid / potassium hydrogen phthalate, stearic acid / alkali or alkaline earth stearate or other carboxylic acid / salt pairs with similar protolytic properties is. Corrosion-inhibiting combination of substances according to one of the previous claims as aromatic mercaptothiazole or triazole mercaptobenzthiazole, methyl mercaptobenzthiazole, Contains benzotriazole, tolyltriazole or mixtures thereof. Corrosion-inhibiting combination of substances according to one of the preceding claims, which tert as a water-insoluble, poly-substituted phenol 2.4 di. butyl-4-methylphenol,
2.6 Di tert. butyl-4-ethylphenol,
2.6 Di tert. butyl-4-methoxyphenol,
2.6 di-octadecyl-4-methylphenol,
4- (1,1,3,3-tetramethylbutyl) phenol,
2 or 6 tert. butyl-4-methylphenol
or contains a similarly structured, multi-substituted phenol alone or a mixture thereof. Corrosion-inhibiting combination of substances according to one of the preceding claims, the L-ascorbic acid, sodium, potassium or calcium ascorbate individually or as a mixture thereof contains. Process for producing a sublimation-capable, corrosion-inhibiting combination of substances, in which (1) aromatic mercaptothiazole or triazole, (2) water-insoluble, multi-substituted phenol, and (3) L-ascorbic acid or one of its salts are mixed together. The method of claim 10, further comprising (4) a carboxylic acid / salt pair is added. The method of claim 10 or 11, wherein the components be mixed in dry powder form. Method according to one of claims 10 to 12, wherein the 10 to 40% component (1), 10 to 35% component (2), 10 to 30% component (3) and possibly 10 to 30% component (4) mixed become. Method according to one of claims 10 to 13, wherein the mixed components are added to a metal oxide sol and applied this composition on a carrier material becomes. Use of a corrosion-inhibiting combination of substances according to one of claims 1 to 9 as a volatile corrosion inhibitor (VPI, VCI) in the form of fine powder mixtures at Packaging or storage of materials. Use of a corrosion-inhibiting combination of substances according to one of claims 1 to 9 for incorporation in coating materials and / or colloidal composite materials to so that carrier materials such as paper, cardboard, foams, textile fabrics and similar fabrics in the context of manufacturing of VCI-emitting packaging and then within packaging and storage processes to apply. Use of a corrosion-inhibiting combination of substances according to one of claims 1 to 9 for the formation of corrosion inhibitors, which are in the form of fine powder mixtures with polymeric materials (polyolefins, polyamides, polyesters) on active ingredient concentrates (masterbatches) and flat final products let blow or spray extrude so that VCI emitting Foils or hard materials arise, their emissivity of volatile corrosion inhibitors (VPI, VCI) corrosion protection within packaging and storage processes of metals can be applied. Use of a corrosion-inhibiting combination of substances according to one of claims 1 to 9 as a volatile corrosion inhibitor (VPI, VCI) within packaging and storage processes for corrosion protection of those considered to be non-passivable Metals such as copper, silver, manganese, magnesium and their base alloys.