EP1281790A1 - Volatile corrosion inhibitors and process for making them - Google Patents

Abstract

A corrosion inhibiting composition comprises: (a) an inorganic salt of nitric acid, (b) a water-insoluble multi-substituted phenol, (c) an aliphatic ester of a di-hydroxybenzoic acid and (d) tocopherol (2,5,7,8-tetramethyl-2-(4',8',12'-trimethyltridecyl) chroman-6-ol). An Independent claim is also included for a process for the production of a sublimatable corrosion inhibiting composition (I) by mixing together components (a)-(d).

Description

The invention relates to substance combinations as vapor-phase corrosion inhibitors (volatile corrosion inhibitors, VCI) for the protection of common utility metals, such as iron, chromium, Nickel, tin, zinc, aluminum, copper and their alloys, against atmospheric corrosion.

It is already well known that corrosion inhibitors, which in powder form tend to sublimation under normal conditions and via the gas phase to be protected metal surfaces for temporary corrosion protection of metal objects within closed spaces, e.g. in packaging or showcases are used.

Typically, these vapor phase inhibitors (VPI) or volatile corrosion inhibitors (VCI) are selected according to the type of metal to be protected and packaged as a powder packaged in pouches of a material which is permeable to the vaporous VPIs ( See, for example: HH Uhlig, corrosion and corrosion protection, Akademie-Verlag Berlin, 1970, pp 247-249, K. Barton, protection against atmospheric corrosion theory and practice, Verlag Chemie, Weinheim 1973, p 96 ff Rozenfeld, corrosion inhibitors (russ.) IZT-vo Chimija, Moskva 1977, p 320 ff; 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.).

Modern packaging materials for corrosion protection included the VCI either in tablet form within porous Foam capsules or as a fine powder within polymers Support materials. Thus, in the US patents 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 various variants proposed the VCI in capsules or air-permeable plastic films to bring in, either by inclusion in by separating a foam created cavities with subsequent Cover same with a gas-permeable Material or by adding the VCI to the melt, Spray or bubble extrusion provided polymer melt, so that a packaging material (film or hard material) is produced, because of the structure-related porosity, the VCI components can continuously sublimate.

It has also been tried, the VCI during foaming of polymeric solids, e.g. in JP 58,063,732, US 4,275,835 and DD 295,668. Farther VCI-containing packaging can be produced, by placing the VCI components in a suitable solvent dissolved and applied to the packaging material in question become. Process 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-PS 1521900 and US 3,887,481.

However, the VCI packaging materials produced in this way are the active ingredients usually only loose in the structural cavities of the carrier material paper, cardboard, foam etc. stored contain, there is a risk of mechanical Abspreitens and trickle out the drug particles, so not can be ensured that the pretreated support materials at the time of its application for corrosion protection even the required specific surface concentration to own VCI.

To overcome this disadvantage, US Pat. No. 5,958,115 is incorporated herein by reference described corrosion inhibiting composite material, the a mixture of a metal oxide sol, the sublimation capable Corrosion inhibitors and other additives exists and on the carrier material a firmly adhering, sufficiently porous Gel film of the metal oxides used and additives forms, from the corrosion inhibitors (VCI) with a uniform, long-term emission rate.

According to the ISO definition, a corrosion inhibitor is a "chemical Substance that in presence with a suitable concentration reduces the corrosion rate in a corrosive system, without the concentration of any other corroding To change funds decisively. The use of the The term inhibitor should be defined by the nature of the metal and its environment, in which it is effective, be specified. " ("chemical substance which decreases the corrosion rate when Present in the corrosion system at a specific 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 the application of VCI is the maintenance, or reinforcement of the inherent, mostly limited protective Primary oxide layer, which is on each metal by contact with the atmosphere is very fast, but purely visual without optical aids is imperceptible (K. Barton, cit .; E. Kunze (ed.), Corrosion and Corrosion Protection, Volume 3, Wiley-VCH, Berlin, Weinheim, New York 2001, p. 1680 ff.).

With regard to the nature and properties of the said primary oxide layer can the known utility metals and their alloys be divided into two categories, the passivatable, where for the maintenance or reproduction of the protective primary oxide layer is a sufficiently strong oxidizing agent is needed and those referred to as non-passivatable Metals where the passive oxide layer just through the Action of strong oxidizing agents such chemical and / or structural changes undergoes that liability on the substrate and thus also the corrosion protection effect get lost.

To illustrate this difference, which exists between the two categories of working metals, the following examples serve. For the iron materials belonging to the category of passivatable metals, the primary oxide layer consists, for example, mainly of Fe (III) oxides. If moistening of the metal surface occurs, as is the case, for example, when a condensed water film is formed in rooms saturated with water due to temperature reduction, without a sufficiently strong oxidizing agent acting at the same time, the corrosion of the metal begins by precipitating these oxides in Fe (II). Conversions, eg: Fe ₂ O ₃ + H ₂ O + 2 H ⁺ + 2 e ^- → 2 Fe (OH) ₂ and for the anodic step of corrosion of the substrate metal: Fe + 2H ₂ O → Fe (OH) ₂ + 2H ⁺ + 2 e ^- act cathodically.

Among the metals that must be classified in the category of non-passivatable metals, for example, is the copper whose primary oxide layer is sensitive to further oxidation. Its primary oxide layer is known to consist mainly of the oxide Cu ₂ O and is stable only in aqueous media containing no strong oxidant, regardless of pH. On the other hand, under the action of oxygen in humid air, the oxide CuO develops relatively quickly, perceptible as a black deposit, which due to its crystal lattice dimensions can not grow together with the metal substrate (no epitaxy) and therefore does not protect against corrosion. For the initial reactions of the atmospheric corrosion of copper, one can thus formulate: Cu ₂ O + H ₂ O → 2 CuO + 2 H ⁺ + 2 e ^- ½ O ₂ + 2 H ⁺ + 2 e ^- → H ₂ O and as the passive state reversing gross reaction: Cu ₂ O + ½ O ₂ → 2 CuO

Most of the common use metals are passivatable when in contact with aqueous media. Thus, the case of nickel is similar to iron, because its primary oxide layer contains Ni ₂ O ₃ . In the case of chromium, however, the passive state is caused by Cr ₂ O ₃ / CrOOH, in tin by SnO / SnO ₂ , in zinc by ZnO and in aluminum by Al ₂ O ₃ / AlOOH. These passive oxide layers are usually maintained in neutral aqueous media, or spontaneously reproduced in the case of local mechanical abrasion (abrasion, erosion) when the action of a sufficiently strong oxidizing agent is ensured (E. Kunze, loc. Cit.).

As such passivating oxidizing agents, the nitrites have already proven to be versatile as salts of nitrous acid. Therefore, they have long been used as vapor phase inhibitors. In particular, the relatively volatile dicyclohexylammonium nitrite has been used for more than 50 years as a vapor phase inhibitor (see Uhlig, Barton, Rozenfeld, Kunze, loc cit.) And is mentioned as part of VCI compositions in numerous patents (eg: US-PS 2,419. 327, US Patent 2,432,839, US Patent 2,432,840, US Patent 4,290,912, US Patent 4,973,448, JP 02085380, JP 62109987, JP 63210285 A, DE-PS 4040586). The effect of nitrite as an oxidizing agent is associated with its electrochemical reduction, for which z. B. the following reactions can be formulated: 2 NO ₂ ^- + 2 H ⁺ + 2 e ^- → 2 NO + 2 OH ^- NO ₂ ^- + 3H ₂ O + 2H ⁺ + 6 e ^- → NH ₃ + 5 OH ^-

Since these reactions lead to the formation of hydroxyl ions, OH ^- , they run in aqueous media, the less intense, the higher the pH of this medium.

In this aspect, it is unfavorable that the dicyclohexylamine, or the dicyclohexylammonium ion formed by dissociation of the dicyclohexylammonium nitrite in water at room temperature values by pH ≈ 9 sets. This is not only behind the unfolding of the passivator effect of the nitrite, but also endangers the stability of the passive oxide of zinc and aluminum materials. As is well known, the oxides of these metals are only stable in the neutral range and undergo increasing dissolution with zinc> or aluminate formation at pH> 8: ZnO + H ₂ O + OH ^- → Zn (OH) ₃ ^- Al ₂ O ₃ + H ₂ O + 5 OH ^- → 2 Al (OH) ₄ ^-

In an effort to create VCI packaging materials, the not only for ferrous metals, but at least for galvanized Steels and aluminum materials were applicable tries to formulate VCI combinations that are not just a-nitrites, but also contain components that condensed in Intervene in water films on metal surfaces in a pH-regulating manner, so it's not the described resolution of the passive oxide layers comes.

In this aspect, it has been proposed to combine nitrite-amine mixtures with other sublimation-capable substances, such as the salts of moderate to weak, saturated or unsaturated carboxylic acids, cf. eg US 2,419,327, US 2,432,839, 2,432,840, DE 814,725. Although this achieves improved protection of the conventional Al and Zn materials when they are in contact with an aqueous medium or a condensation film, provided that the passive oxide layer is not mechanically damaged or dissolved by the action of complexing agents, these properties make the passivator properties of the Nitrites simultaneously reduced. The carboxylates in question are known to build in aqueous media or Kondenswasserfilmen on metal surfaces with or without the simultaneous presence of an amine depending on the particular carboxylic acid / salt system pH buffer systems higher buffer capacity and thus hinder the reducibility of oxidizing agents, resulting from the abovementioned reduction reactions in principle becomes clear for nitrite. These necessary for the passivation reactions are well known, from left to right voluntarily only when the reaction medium does not already have a high concentration of OH ^- has ions or the resulting OH ^- - ions are regularly discharged from the medium or the concentration of the oxidizing agent in Medium comparatively much higher than the resulting OH ^- ions remains adjusted, such as by continuously reacted portions of the oxidizing agent from a depot.

Consequently, all conventional applications of VCI combinations, which also contain an amine or amine carboxylate in addition to an oxidizing agent such as nitrite, chromate or an organic nitro compound, can only be successful in practical implementation if the passivating oxidizing agent is used at excessive concentrations. However, this fact is not always readily apparent from the corresponding patents, since the concentration ranges in which the VCI combinations according to the invention can be used are usually stated very generously. Such oxidant-containing VCI combinations are described, for example, in US Pat. No. 600,328, where it is recommended to use as much of an organic nitrite salt as possible, or in DE-PS 814 725, in which nitrite salts of organic nitrogen-containing bases (eg. Carboxylates, piperidines, oxazines or morpholines) are proposed under the condition that at least 0.5 to 20 g of nitrite / m ² packaging material are applied and reliable protection is given only if at least 35 to 600 g / m ³ Interior of the packaging were emitted.

Since today the practical application of the designated oxidizing agent as a result of her becoming known, more or less damaging effect on humans and the environment and it regards the concentration in preparations as well the maximum permissible workplace concentration (MAK value) Limit values (see, for example, classification of substances and preparations according to EC Directive 67/548 / EEC including annual Adaptation), are the VCI combinations mentioned with Excessive Passivatoranteilen no longer applicable.

As a substitute, for example, in US Patent 5,209,869, US-PS-5,332,525 and EP 0662 527 A1 proposed, the Nitrites and amine carboxylates with or without molybdate existing VCI mixtures still with a drying agent, such as silica gel combine to allow the formation of a condensed water film on the metal surface to be protected and with it Associated, adverse pH effect delayed as long as possible become. However, this proposal has the crucial Disadvantage that fixed on or in the packaging means VCI system due to the existing desiccant to strong water absorption from the environment tends, which in turn to an impairment of the emission rate of the VCI components and thus to a reduction of the VCI corrosion protection effect leads.

On the other hand, in recent years, with the increasing Globalization and integration of the economic areas of ours Earth the need for reliable functioning VCI systems and VCI packaging materials greatly increased, is still the Use of VCI in storage and transport processes essential more environmentally friendly and less expensive than before conventional methods of temporary corrosion protection, the on behalf of oils, fats and waxes and where to Time of removal of these agents from the metal parts large quantities of difficult-to-dispose organic solutions attack.

Most of the previously known VCI systems simultaneously Containing a nitrite and an amine can provide the required reliability not for the reasons already mentioned provide. Meanwhile, another factor of uncertainty has become proved that especially those introduced as VCI components secondary amines and cyclic nitrogen-containing Compounds, such as e.g. Morpholine and piperidine, easy to N-nitroso compounds being transformed. These N-nitrosamines usually act as weak oxidizers and promote the corrosion of the metals. Much more disadvantageous, however their carcinogenic effect, that of large-scale use of this VCI systems stands in the way.

First, one tried this disadvantage by substitution of the Nitrite remedy, since it was suspected that the nitrosation the amines only by the simultaneous presence of nitrite is caused. In the US-PS 4051066 is therefore instead of the Nitrits m-nitro and dinitrobenzoate used, the DD-PS 268th 978 and DD-PS 295 668 suggest, however, the use of dicyclohexylamine o-nitrophenolate and dicyclohexylamine-m-nitrobenzoate in front. The US-PS 1224500 generalizes finally on the use of volatile aliphatic and aromatic Nitro compounds together with heterocyclic amines and specifically mentions 2-nitropropane, nitrobenzene and dinitrobenzene. On the one hand, however, the passivator properties were proven this alternative oxidizing agent compared to Nitrite as much weaker and the other was the intended Effect, in the case of the amines used the same Not to achieve N-nitrosamine formation. meanwhile It is well known that such proven VCI components, such as the morpholine and dicyclohexylamine already through the normal Components of the air are nitrosated, especially at Contact with metals and at higher temperatures. That forbids practically their incorporation into plastics, because these Melt, spray or blow extrusion is known to be the case Temperatures around 200 ° C in metallic plants instead.

To just the demand for VCI-equipped films and Hard plastics for coping with overseas transports too satisfied, the application was amine-free, nitrite-containing VCI systems proposed. Thus, in US-PS 3836077 the Combination of nitrite with borate and a phenol with Styrenes mono-, di- or trisubstituted, called. The purpose the use of such aromatic substituted phenols was not justified in this PS. However, it can be presumed that they only serve as antioxidants the stability of the polyolefin films against the oxidative effect of the greater proportions should protect the contained nitrite. From slides that made of polyethylene and these fabric combinations, sublimate only small amounts of nitrite, as long as the additional incorporation of the in said PS also claimed phenyl-beta-naphthylamins is omitted. By the presence of this amine could reduce the emission rate of nitrite be improved, thus keeping the goal of being free of but was abandoned. By the way, it was possible with this amine not, a sublimation of borate and the aromatically substituted To reach phenols.

US Pat. No. 4,290,912, on the other hand, emphasizes the production of VCI films on the application of inorganic nitrites in combination with a trisubstituted phenol and silica gel However, the embodiments prove that in the case of Phenols only aliphatic substituted and especially the 2.6-di tert-butyl-4-methyl-phenol (butylated hydroxytoluene, BHT) are meant. Since these substituted phenols even at normal temperature tend to sublimation, could with this combination also for sodium or potassium nitrite without participation of a volatile amine achieved an improved rate of sublimation but that can arrive on the metal surface Nitrite without the participation of other components no reliable Realize VCI corrosion protection. It needs at passivating metals are known to be involved with components, the pH in condensed water films in a adjust for the passivation favorable range and the trained Passive oxide layer by adsorption against dissolution stabilize (see, e.g., E. Kunze, loc. cit.). At the same time Presence of non-passivating metals, e.g. the Copper materials would have the sole effect of a nitrite in addition, increased corrosion.

Namely for the protection of copper and copper alloys from atmospheric Corrosion has long been benzotriazole in use (See, e.g., Barton, Mercer, loc cit.). However, since the sublimation trend This connection is relatively low, is in DE-PS 1182503 and US-PS 3,295,917 proposed that Depot this VCI first 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, to cool. In the US Pat. Nos. 2,941,953 and 3,887,481, on the other hand, teach the impregnation of Paper with benzotriazole and / or tolyltriazole described. It come organic solvents such as the tetrachlorethylene to Use and it is prescribed, the metal parts to be protected as tight and tight as possible with the impregnated VCI packaging material to envelop the distance between VCI depot and to be protected metal surface as low as possible hold. However, this technology has the already mentioned Disadvantage that the active ingredient in the form of the finest powder particles only slightly adhering to the paper and lightly trickling off so that the anti-corrosion properties of these packaging materials not reliable.

The sublimation tendency of benzoyl and tolyltriazole from VCI depots Similar to inorganic nitrites and nitrates to, if at the same time still sublimationsfähige Be incorporated solids in powder form. Call for this EP 0662527 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 molybdenum data, Amine Benzoates and Nitrates, U.S. Patent 4,973,448 Blends of Benzotriazole with organic carbonates, phosphates and amines, JP 62063686 and JP 63210285 A finally mixtures of benzotriazole with alkali and amine salts of aromatic carboxylic acids.

Combinations of benzo, tolyl or methylbenzotriazole with other nitrogen-organic volatile solids e.g. in JP 62109987, JP 61015988, DD-PS 268978 and DD-PS 298662 described. The disadvantage is that all ammonium ions and amine-containing components because of their more or less pronounced tendency to complex with metal ions the Protective effect of triazoles especially against non-ferrous metals to belittle again. In addition, the designated amines and Ammonium compounds strongly hydrophilic. VCI depots, such Contain substances tend, as already mentioned above, to increased water absorption. As a result of their hydrolysis it comes then usually to a greater decrease in their sublimation tendency, which inevitably reduces the anti-corrosive effect entails.

To take advantage of the use of VCI and the inhibitor effect the triazole structure is disclosed in JP-PS 03079781 proposed instead of the substance combinations triazole / amine only to use 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, However, especially against copper so clear Corrosion protection effect, such as the benzoyl and tolyltriazole.

• erstens ist die hohe Flüchtigkeit der VPI bei Temperaturen, bei denen der Extrusionsprozeß vorgenommen wird, einzukalkulieren, denn diese kann zu einem intensiven Übergang der Inhibitoren in den gasförmigen Zustand und damit zu bedeutenden Verlusten dieser Stoffe sowie zum Ausschäumen der Folie, zur Verletzung ihrer Geschlossenheit und damit zur unkontrollierten Verminderung ihrer Festigkeits- und Schutzeigenschaften führen;
• zweitens ist zu berücksichtigen, dass es im Verlauf der Verarbeitung der Mischungen während des Extrusionsprozesses zur thermischen Zersetzung der Korrosionsinhibitoren und zu chemischen Reaktionen der Komponenten untereinander bzw. mit der Polymermatrix kommen kann. Daraus resultiert insgesamt der entscheidende Nachteil, dass eine Vielzahl bisher üblicher VPI auf diese Weise nicht mehr applizierbar sind und durch neuartige Wirkstoffe substituiert werden müssen.

Now, if VCI components are to be used for modern packaging, storage and transport technologies with hard plastics and plastic films and VCI additives that can guarantee VCI corrosion protection for the widest possible range of working metals are available To cope with essentially the following problems:

• First, the high volatility of the VPI at temperatures at which the extrusion process is made to take into account, because this can lead to an intensive transition of the inhibitors in the gaseous state and thus to significant losses of these substances and foaming of the film, to breach of their closure and thus lead to the uncontrolled reduction of their strength and protective properties;
• Secondly, it must be taken into account that thermal decomposition of the corrosion inhibitors and chemical reactions of the components with one another or with the polymer matrix may occur during the processing of the mixtures during the extrusion process. Overall, this results in the decisive disadvantage that a large number of previously customary VPIs can no longer be applied in this manner and must be substituted by novel active substances.

The object of the invention is compared to those listed above Disadvantages of conventional corrosion inhibitors improved sublimation-capable, corrosion-inhibiting substances and Indicate substance combinations, in particular among the practical interesting climatic conditions within of technical packaging and analogue closed spaces with sufficient speed from a corresponding depot sublime and after adsorption and / or condensation the surface of metals in this room there to provide conditions under which the usual utility metals reliably protected against atmospheric corrosion. The object of the invention is also to provide methods for Production or processing of such substances and substance combinations for the production of improved VCI packaging materials indicated.

These tasks are combined with fabric combinations and procedures the features of claim 1 or 15 solved. Advantageous embodiments and uses of the invention will be apparent the dependent claims.

(1) anorganisches Salz der Salpetrigen Säure,

(2) wasserunlösliches, mehrfach substituiertes Phenol,

(3) aliphatischer Ester einer Di-Hydroxy-Benzoesäure, und

(4) Tocopherol (2,5,7,8-Tetramethyl-2-(4',8',12'trimethyltridecyl) Chroman-6-ol).

The basic idea of the invention is to provide sublimation-capable substance combinations which contain the following components:

(1) inorganic salt of nitrous acid,

(2) water-insoluble, polysubstituted phenol,

(3) aliphatic ester of di-hydroxybenzoic acid, and

(4) tocopherol (2,5,7,8-tetramethyl-2- (4 ', 8', 12'-trimethyltridecyl) chroman-6-ol).

In coordination with the components (1) to (4) may optionally further as component (5) a bicyclic terpene or aliphatic substituted naphthalene, which contributes to that consisting of representatives of components (1) to (4) Fabric combinations even at relatively low temperatures and in air with permanently high levels of relative humidity always results in a sufficiently high emission rate and thus the reliability of the VCI corrosion protection is further improved.

According to the invention, these substance combinations are directly in the form corresponding powdered mixtures used or according to methods known per se in the context of production incorporated by VCI packaging means, so that these packaging materials act as a VCI depot and the anti-corrosion properties the substance combinations according to the invention especially can be advantageous to unfold.

The invention also provides the use of said Substance combinations as vapor-phase corrosion inhibitors in Packaging or when stored indoors Protection of common use metals, such. As iron, chromium, Nickel, tin, zinc, aluminum, copper and their alloys against atmospheric corrosion. The substance combinations according to the invention are mainly used to the wide range the usual utility metals and their alloys in Packaging and during storage in analog enclosed spaces from atmospheric corrosion protect.

The invention also relates to a corrosion-inhibiting Material containing a component that is an inorganic Salt of nitrous acid is and due to its oxidizing power on passivatable metals the spontaneous formation of a Passive oxide layer causes another component, the one polysubstituted phenol and, owing to its properties, insoluble in water, but with a passive oxide covered metal surfaces to be well adsorbed, to Stabilization of such metal surfaces contributes to corrosion, a component which is an aliphatic ester of a dihydroxybenzoic acid and surprisingly both Effect of nitrites as a passivator is supported as well adsorptive stabilization of passive oxide layers, a component containing a tocopherol (2,5,7,8-tetramethyl-2- (4 ', 8', 12'-trimethyltridecyl) Chroman-6-ol) and because of her Property of acting as an antioxidant, surprisingly the attack of atmospheric oxygen or of nitrite Component (1) inhibited in non-passivatable metals and In addition, chemical reactions between the other components completely eliminates the substance combinations according to the invention, so that their long-term stability is ensured and finally as a further component a bicyclic terpene or aliphatically substituted naphthalene, which because of their relatively high sublimation pressure and its Wasserdampffflüchtigkeit even at lower temperatures and in humid air with high values of the relative humidity as carrier substance for the transport of the active ingredients (1) to (4) via the gas space acts to protect the metal surface, without to influence the same negative, corrosive, but ensures that the corrosion protection effect fully unfold the substance combinations according to the invention can. In addition, a composition of the invention contain at least one inert filler.

The inventively provided components are advantageously only substances that are after themselves easily and safely process known methods and in the proportions to be applied as non-toxic and Environment are not endangering. They are suitable for that especially for the production of anti-corrosive packaging materials, the on a large scale cost and without risk potential are applicable.

For the introduction of the substance combinations according to the invention in VCI depots or in packaging materials acting as such it is appropriate, the individual substances in the anhydrous state according to methods known as intensively as possible with each other to mix.

The substance combinations according to the invention are preferably formulated within the following proportions by weight: Component (1) 0.1 to 40% Component (2) 0.5 to 40% Component (3) 0.5 to 40% Component (4) 0.5 to 40% or when using all five components Component (1) 0.1 to 40% Component (2) 0.5 to 30% Component (3) 0.5 to 20% Component (4) 0.5 to 20% Component (5) 0.1 to 10%.

The invention is explained in more detail by the following examples. As can be seen from that, type, quantity depend the individual components in the mixture according to the invention and proportion of mixture in each VCI depot both after the metal to be protected as well as the conditions of manufacture of the relevant VCI packaging material.

Example 1:

From the anhydrous substances, the following combination of substances according to the invention was prepared: 30.0 mass% sodium nitrite 9.0% by mass 2.6-di-tert-butyl-4-methoxy-phenol 11.7 mass% 2- (2H-benzotriazol-2-yl) -4-methyl-phenol 16.7 mass% 2.4 Dihydroxybenzoic acid methyl ester 11.7 mass% d-Tocopherol 7.4% by mass (IS) - (-) - Borneol: (endo- (1S) -1,7,7-trimethyl-bicyclo [2.2.1] heptan-2-ol) 13.5 mass% inert filler (silica gel)

In each case 5 g of this mixture were placed on the bottom of a 25 ml Beaker spread wide and this in a mason jar (content 1 l). Next to the beaker was a second with 10 ml of demineralised water (fully desalinated water) positioned. Then it became a test specimen rack introduced, cleaned at the 4 pieces each Standard spray rings at 45 ° inclination to the horizontal were hung up. These consisted in each approach from the Materials low alloyed steel 100Cr6, cast iron GGL25, AlMg1SiCu and Cu-SF, free of tarnish films and deposits.

In the first two test specimens can be incipient Easily detect rust formation visually. Harder to On the other hand, identifying is the initial phase of corrosion the latter two Buntmetallprüfkörpern.

To remedy this situation, was from these Prüfringen ago Start of the test the surface condition by measuring the gloss behavior assessed at selected locations. The used for it Measuring system "GLOSScomp" (OPTRONIK, Berlin) registers the composed of the proportions of direct and diffuse reflection Reflection curve whose peak height P / dB for the respective Texture of the metal surface sufficiently representative is.

A first start-up films or other corrosion phenomena Conditional loss of gloss makes itself with Al and Cu base materials compared to the fixed initial state usually noticeable in lower values of P. To show, that such changes have taken place that the Eye purely visually difficult without optical aids it is sufficient to determine ΔP /%.

The mason jars with the metal samples, the deionized water and the invention Fabric combination were sealed, for which use a lid with a sealing ring and a clamp were. After 16 h waiting time at room temperature could the so-called build-up phase of the VCI components within the vessel considered complete. The individual mason jars were then exposed for 16 h in warming cabinets at 40 ° C, then again for 8 h at room temperature. This cyclical burden (1 cycle = 24 h) was repeated until, until the test specimens through the glass wall through visual changes or a maximum load of 42 Cycles awaited.

After the end of the experiment, Al and Cu rings were used for each individual the values ΔP /% registered. The steel and cast iron specimens were assessed only visually.

In reference to the composition according to the invention, 5 g portions of a commercially available VCI powder were tested in the same way. This reference VCI powder (R1) consisted of 54.0% by mass Monoethanolaminbenzoat 23.0% by mass 1H-Benzotriazole 23.0% by mass Filler (silica gel)

Result of the exam:

The existing of the iron materials test specimens together been used with the composition of the invention were, had at all 4 parallel approaches after 42 cycles an unchanged appearance. The same was true of the Al and Cu specimens. These were 0 ≤ ΔP /% ≤ after 42 cycles +0.5. It follows that you are shiny metallic Appearance in saturated with the combination of substances according to the invention Moist air remained unchanged.

In the approaches with the commercial reference system showed the test specimens from GGL25 after 8 to 10 cycles first punctual Rusty spots resulting from continuation of the tests quickly enlarged. At the steel rings could after 11 to 12 Cycles edge rust can be observed.

The gloss behavior of the Al and Cu specimens was also here measure again after 42 cycles. There was always one To determine gloss reduction, characterized by negative ΔP values /%, for AlMg1SiCu with -2,1 as the mean much more pronounced than with Cu-SF with -0.3.

The reference system is therefore only for VCI corrosion protection of Cu base materials gegeignet. From the described example comes in comparison to the VCI effect the combination of substances according to the invention over the usual Useful metals very beneficial effect.

Example 2

From the anhydrous substances, the following combination of substances according to the invention was prepared: 20.0 mass% sodium nitrite 11.0% by mass 2- (2H-benzotriazol-2-yl) -4-methyl-phenol 11.5 mass% 2.4 Dihydroxybenzoic acid methyl ester 12.7 mass% Tocopherol (RRR-α-T.) 25.6% by mass sodium benzoate 6.8% by mass benzoic acid 12.4 mass% (+) - borneol, (endo- (1R) -1,7,7-trimethyl-bicyclo [2.2.1] heptan-2-ol) and a 5% solution made up in ethanol (90%) / water.

An aqueous-alcoholic acidic sol which was obtained according to DE-OS 19708285 from 50 ml of tetraethoxysilane, 200 ml of ethanol and 100 ml of 0.01N hydrochloric acid by stirring for 20 hours at room temperature and then 4.2% solids content in 70% ethanol at pH ≈ 4, was mixed with 50 ml of 5% solution of the combination of substances according to the invention and thus paper (kraft paper 70 g / m ² ) coated by wet rolling. Immediately after drying the thus prepared VPI paper in air, it was tested for anti-corrosive effect as compared with a commercial anticorrosive paper serving as a reference system (R2). The reference system (R2) contained, according to chemical analysis, the active ingredients dicyclohexylamine nitrite, cyclohexylamine cyprylate and benzotriazole, the total proportion being approximately comparable to that of the substance combination according to the invention.

It came as in Example 1 again test specimens in ring form (Standard blanks) made of low alloy steel 100Cr6, cast iron GGl25, AlMg1SiCu and Cu-SF for application and also the Test ritual was analogous to that described in Example 1. Of the only difference was now that in place of the VCI powder blends now the individual mason jars with the VCI paper were lined, each one circular blank with ⊘ 8 cm at the bottom, a coat of 13 x 28 cm and another circular cut with ⊘ 9 cm for the lid. Then were the test specimen rack and the beaker with the deionized water placed, the mason jar closed and the climate load as described in Example 1, carried out.

However, since now the state of the candidates not by the Glass wall could be observed, the approaches to this were Purpose after every 5 cycles during the room temperature phase open for a short time. Visually, no changes determine the climate load was in the described Way continued.

Result of the exam:

The existing of the iron materials specimens that had been used together with the composition of the invention, had again in all 3 parallel batches after 42 cycles an unchanged appearance.
The same was true for the Al and Cu specimens. These were again indicated by 0 ≤ ΔP /% ≤ +0.5 after 42 cycles. It follows that their shiny metallic appearance remained unchanged in the humid air saturated with the combination of substances according to the invention.

In the approaches with the commercial reference system showed the test specimens from GGL25 after 8 to 10 cycles first punctual Rusty spots resulting from continuation of the tests quickly enlarged. At the steel rings could after 11 to 12 Cycles edge rust can be observed.

The gloss behavior of the Al and Cu specimens was only after Measure 42 cycles again. There was always a gloss reduction determined by negative ΔP values /% marked for AlMg1SiCu with -3.5 as the mean value again much clearer than with Cu-SF with -0.5.

The reference system is therefore only for VCI corrosion protection conditionally determined by Cu base materials, while the inventive Substance combination, as the example shows, opposite the usual utility metals even under the extreme Moist air conditions unfold reliable VCI properties.

Example 3:

From the anhydrous substances, the following combination of substances according to the invention was prepared: 22.4 mass% sodium nitrite 6.0% by mass 2.6-di-tert-butyl-4-methoxy-phenol 14.7% by mass of tylphenol 2- (2H-benzotriazol-2-yl) -4.6 di tert. bu- 15.7 mass% 2.4 Dihydroxybenzoic acid ethyl ester 12.7 mass% Tocopherol (RRR-α-T.) 12.4 mass% 2.6 Diisopropyl naphthalene 8.1 mass% calcium stearate 7.8% by mass Calcium carbonate (slip) 2.2% by mass Silica gel (antiblock) 35% by mass of this mixture was mixed with 65% by mass of a conventional LD-PE and processed to a VCI masterbatch. For this purpose, an extruder Rheocord 90 (HAAKE) was used with counter-rotating twin screw. With the screw speed of 65 to 80 U / min was extruded at cylinder temperatures around 150 ° C and a nozzle temperature of 158 ° C and granulated by cold cut. This granulated VCI masterbatch was further processed by blown extrusion into VCI films, for which purpose the extruder was to be equipped with a single screw and an annular die. After mixing 3% by mass of the VCI masterbatch with 97% by mass of conventional LD-PE granules, the cylinder temperatures were 175 ° C. and a nozzle outlet temperature of 180 ° C., the screw speed varying between 80 and 85 rpm , A VCI film with an average layer thickness of 80 μm was produced (VCI (3)). The VCI film VCI (3) thus produced using a combination of substances according to the invention was processed into bags (cutting and welding of the superimposed side seams). Sheet metals Carbon Steel C25, cold rolled, (90 x 50 x 1) mm ³ (Q-Panel, Q-Panel Lab Products, Cleveland, Ohio 44145 USA), and Zn-plated hot-dip galvanized steel ( ZnSt ) (EKO steel GmbH, D-15872 Eisenhüttenstadt) were each positioned inside spacer frames in ⊥-arrangement and welded into a prefabricated bag.

The reference system (R3) was a commercially available VCI film Use which according to chemical analysis dicyclohexylamine nitrite, Sodium molybdate and sodium benzoate contained, in total about the double amount compared to the VCI components of the invention Fabric combination, and a layer thickness of 110 had μm. In addition, similar packaging with VCIfreier LDPE film, 80 μm, prepared.

All manufactured model packages were still around 17 h Room temperature intermediately stored in the packaging the Setting an atmosphere saturated with VCI components (Build-up phase!) To ensure. Then the transfer took place in a climatic test cabinet, type HC 4020 (VÖTSCH Industrietechnik GmbH, D-72304 Balingen), which refers to the humidity-temperature-alternating climate adjusted according to DIN EN 60068-2-30 was. A 24-h cycle consists of the following stages: 6 h 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 of 55 to 25 ° C at (RH) = 98% and 3 h 25 ° C and (RH) = 98%.

The surface of the foil-wrapped test panels could be inspected through the transparent foil material after each cycle
As soon as visible corrosion phenomena occurred in the model packaging, the climate load was interrupted for the sample in question and the number of cycles that had previously elapsed was registered.

Result of the exam:

Results of wet-air temperature cycling of model packaging (averages of number of cycles from 3 parallel samples) packaging Number of cycles according to DIN EN 60068-2-30 surface condition C25 ⊥ZnSt / LDPE, 80 5 at the C25 first rust at edges; microns 7 on the ZnSt white rust beginning at the edges C25 ⊥1 ZnSt / VCI (3), 80 μm canceled after 40 without corrosion on both metal samples C25 ⊥ZnSt / R3, 110 25 occasionally rust at the C25; microns 21 on the ZnSt white rust at the contact point of the C25 and at cutting edges This example documents the superiority of the combination of substances according to the invention as a high-performance VCI film packaging material for overseas transport, the climatic conditions with the selected wet air temperature alternating load are known to be timely adjusted.

Example 4:

From the anhydrous substances, the following combination of substances according to the invention was prepared: 10.0 mass% sodium nitrite 5.0 mass% 2.6-di-tert-butyl-4-methyl-phenol 15.0 mass% 2- (2H-benzotriazol-2-yl) -4.6-d i. tert butylphenol 16.0% by mass 2.4 Dihydroxybenzoic acid methyl ester 11.6 mass% d-Tocopherol 12.4 mass% 2.6 Diisopropyl naphthalene 11.7 mass% 1H-Benzotriazole 4.3 mass% calcium stearate 8.2% by mass Zinc oxide (filler) 4.3 mass% Calcium carbonate (slip) 1.5% by mass Silica gel (antiblock) 35% by mass of this mixture was again mixed with 65% by mass of a conventional LD-PE and processed to a VCI masterbatch. The conditions including the subsequent VCI film production also corresponded to those described in Example 3, so that in the end a VCI film with an average layer thickness of 80 μm resulted again (VCI (4)).

The thus using a combination of substances according to the invention VCI film VCI (4) prepared was partially cut to surface or processed into bags (cutting and welding the superimposed side seams) and these for the packaging used by electronic circuit boards. there these were 50.8 x 50.8 mm boards, in the stack of 5 pieces each with an intermediate layer VCI film were to be welded into a VCI bag. Every circuit board had a layer system consisting of galvanic Cu (25 microns) / chemically Ni (5 microns) / Sud Au (0.3 microns), its bondability to ensure storage and transport processes was.

The reference VCI packaging material was a commercial one VCI film (R4) for use as VCI components cyclohexylamine caprylate and benzotriazole emitted and 100 microns Layer thickness possessed. In addition, packaging of the printed circuit board stack made with LDPE film, 100 μm.

All so prepared model packages were already with that in the example 3 mentioned climate according to DIN EN 60068-2-30 applied and after 20, 25, 30 and 35 cycles always 3 Similar packaging for bonding tests from the climatic chamber taken. The bonding tests after 2 h storage of the Packaging material removed PCBs from dry air at room temperature were using a manual Thermosonicbonders K & S 4124 (60 kHz). Bonded with Bonding wire Au Beta 25 μm (wire pull load> 8 cN) each 170 positions per printed circuit board at a distance of 1.7 mm. Subsequently was made by micro tester LC 02 of 50 bond compounds characterized the stability by determining the tearing force (Test method MIL-883 D).

Bondability was deemed to exist when the averages the tearing force was> 10 cN and the microscopic detected crack had occurred at the bond site.

Result of the exam:

All packed in the combination of substances according to the invention and in the manner described klimabeaufschlagten PCBs could still be classified as bondable after 35 cycles. For printed circuit boards packaged in VCI-free LDPE film was on the other hand, after 20 cycles consistently no bondability more given.

Of the printed circuit boards packaged in the reference VCI film R4 First, the intermediate storage time from unpacking to Bonding test from 2 to at least 8 h to be extended by the 20 and 25 cycles were at least 45 more samples or 37% stable bonding. All samples in VCI film R4 had been subjected to more than 25 cycles however, are classified as no longer bondable.

The example shows that the combination of substances according to the invention by forming adsorption films on metals also Protects the slightest surface changes that are still visually are not perceptible, but already the usability of this Restrict metals. With the relatively fast desorbability This VCI movies will be the application of the VCI method also in promising areas such as microelectronics possible, where previously commercially available VCI systems, such as that tested here, remained unsuccessful, obviously, because they leave thin conversion layers instead of adsorption films. But just for bonding processes, the cleanliness of Metal surfaces, free of adsorption films and conversion layers of fundamental importance, what by hitherto commercial VCI systems just can not be guaranteed.

Claims (21)

Corrosion-inhibiting substance combination containing: (1) inorganic salt of nitrous acid, (2) water-insoluble, polysubstituted phenol, (3) aliphatic ester of di-hydroxybenzoic acid, and (4) tocopherol (2,5,7,8-tetramethyl-2- (4 ', 8', 12'-trimethyltridecyl) chroman-6-ol). Corrosion inhibiting substance combination according to claim 1, the further (5) a bicyclic terpene or aliphatic substituted Naphthalene as a steam-volatile component contains. Corrosion inhibiting substance combination according to claim 1, at the 0.1 to 40% component (1), 0.5 to 40% component (2), 0.5 to 40% component (3) and 0.5 to 40% component (4) are included. Corrosion inhibiting substance combination according to claim 2, at the 0.1 to 40% component (1), 0.5 to 30% component (2), 0.5 to 20% component (3), 0.5 to 20% component (4) and 0.1 to 10% of component (5). Corrosion inhibiting substance combination according to claim 2 or 4, in which the composition is adjusted so that in the temperature range up to 80 ° C at a relative humidity (RH) ≤ 98% all components with for a steam room corrosion protection sublime sufficient amount and speed. Corrosion inhibiting substance combination according to claim 2 or 4, in which as the promoter of the sublimation contained bicyclic terpene preferably derived from the group of Bornane and a camphor, borneol or substitution product derived therefrom is. Corrosion inhibiting substance combination according to claim 2 or 4, in which as the promoter of the sublimation contained aliphatically substituted naphthalene preferably from the group the isopropyl substituted naphthalenes and 4-Isopropyl-1,6-dimethyl-naphthalene (Cadalen), 2.6 Di-isopropyl-naphthalene or a similar isopropyl naphthalene is. Corrosion inhibiting substance combination according to one of preceding claims, which as inorganic salt of Nitrous acid is an alkali, alkaline earth or ammonium nitrite or mixtures thereof. Corrosion inhibiting substance combination according to one of preceding claims, as water-insoluble, multiple substituted phenol 2- (2H-benzotriazol-2-yl) -4-methylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-tert-butyl-phenol, 2,6-di tert. butyl-4-methyl-phenol, 2,6-di tert. butyl-4-ethyl-phenol, 2,6-di tert. butyl-4-methoxy-phenol, 2,6-dioctadecyl-4-methyl-phenol, or a similarly structured, polysubstituted phenol alone or a mixture thereof contains. Corrosion inhibiting substance combination according to one of preceding claims, which as an aliphatic ester of a Dihydroxybenzoic acid, 2.4 Dihydroxybenzoic acid methyl ester, 2.5 Dihydroxybenzoic acid methyl ester, 2.6 Dihydroxybenzoic acid methyl ester, 3.5 Dihydroxybenzoic acid methyl ester, 3.4 Dihydroxybenzoesäureethylester or a similar aliphatic ester a di-hydroxybenzoic acid alone or a mixture thereof contains. Corrosion inhibiting substance combination according to one of preceding claims, the α-tocopherol individually or as Contains mixture with its stereoisomers. Corrosion inhibiting substance combination according to one of previous claims, which include a camphor or Borneol as bicyclic terpene singly or as a mixture thereof contains. Corrosion inhibiting substance combination according to one of preceding claims, which also include 4-isopropyl-1,6-dimethylnaphthalene (Cadalen), 2.6 di-isopropyl-naphthalene or a similar isopropyl-naphthalene singly or as a mixture thereof contains. Corrosion inhibiting substance combination according to one of preceding claims, in addition to the components (1) to (5) contains, individually or as a mixture, substances which Form vapor phase inhibitors. Process for the preparation of a sublimation-capable, corrosion-inhibiting Substance combination in which (1) an inorganic Salt of nitrous acid, (2) water-insoluble, polysubstituted phenol, (3) aliphatic ester of a Di-hydroxybenzoic acid, and (4) tocopherol mixed together become. The method of claim 15, further comprising (5) a bicyclic Terpene or an aliphatic substituted naphthalene is added. Method according to one of claims 15 or 16, in which the 0.1 to 40% component (1), 0.5 to 30% component (2), 0.5 to 20% component (3), 0.5 to 20% component (4) and 0.1 to 10% component (5) are mixed. Use of a corrosion-inhibiting substance combination according to any one of claims 1 to 14 as a volatile corrosion inhibitor (VCI, VPI) in the form of finely powdered mixtures the packaging, storage or transport of metallic Materials. Use of a corrosion-inhibiting substance combination according to any one of claims 1 to 14 for incorporation in coating materials and / or colloidal composite materials thus carrier materials, in particular paper, cardboard, foams, textile fabrics and similar fabrics, for the manufacture of VCI-emitting packaging materials and these in packaging, storage and transport operations apply. Use of a corrosion-inhibiting substance combination according to any one of claims 1 to 14 for the formation of corrosion inhibitors, in the form of finely powdered mixtures with polymeric materials, in particular polyolefins, polyamides, Polyester, to active ingredient concentrates (masterbatches) and flat Final products melt, spray or bubble extruded so that VCI-emitting hard plastics or foils arise with their emissivity of volatile corrosion inhibitors (VCI, VPI) within packaging, storage and and transport processes for the corrosion protection of metals be applied. Use of a corrosion-inhibiting substance combination according to any one of claims 1 to 14 as a volatile corrosion inhibitor (VCI, VPI) for packaging, storage and transport operations for the corrosion protection of utility metals, in particular Iron, chromium, nickel, tin, zinc, aluminum, copper and their alloys.