EP2373769A1

EP2373769A1 - Method for producing shaped elements from sheet steel galvanized on one or both sides

Info

Publication number: EP2373769A1
Application number: EP09760141A
Authority: EP
Inventors: Helmut Witteler; Karl-Heinz Stellnberger; Martin Fleischanderl; Stephan Hüffer
Original assignee: Voestalpine Stahl GmbH; BASF SE
Current assignee: Voestalpine Stahl GmbH
Priority date: 2008-12-04
Filing date: 2009-11-23
Publication date: 2011-10-12
Anticipated expiration: 2029-11-23
Also published as: KR20110111283A; JP2012511101A; US20110236716A1; WO2010063597A1; EP2373769B1

Abstract

Method for producing shaped elements from sheet steel galvanized on one or both sides, the raw material being a galvanized steel strip, wherein at least one of the method steps is a transporting operation and wherein protection against "black spot corrosion" is achieved by applying an anticorrosive oil which contains N-acyl derivatives of sarcosine acid as a corrosion inhibitor.

Description

Process for the production of moldings from sheet steel galvanized on one or both sides

description

The present invention relates to a process for the production of moldings from one-sided or two-sided galvanized steel sheet starting from galvanized steel strip, wherein at least one of the process steps is a transport process, and in which one for protection against "black spot corrosion" a corrosion protection oil which contains N-acyl derivatives of sarcosine acid as a corrosion inhibitor.

The manufacture of sheet-like metallic finished products made of galvanized steel, such as car bodies or parts thereof, device cladding, facade cladding, ceiling cladding or window profiles is a multi-stage process. The raw material for this purpose are usually galvanized steel strips, which are produced by rolling the metal followed by galvanizing and wound up into coils for storage and transport, which are rewound for processing, separated into smaller pieces by means of suitable techniques such as Punching, drilling, folding, profiling and / or deep-drawing formed Larger components, such as automobile bodies, may be obtained by assembling several individual parts, for example, after forming and joining, the product may be painted.

It is characteristic of the said production process that the said process steps are not all carried out in one production facility, but that precursors and / or semi-finished products usually have to be transported once or several times from one to another production facility. Reference may be made by way of example to the production of automobiles: The metal strips are produced by a steel manufacturer. The cutting of the strips and the forming into an automobile body or body parts takes place in a press shop and the finished bodies or parts thereof are subsequently transported to an automobile manufacturer for painting and final assembly.

In this context, the "Completely-Knocked-Down" - or the "Partly Knocked-Down" manufacturing technology for automobiles to mention in the export of certain vehicles deliberately not ready mounted state, but in the form of individual parts in The importing country is transported and finally assembled in the importing country. In this production technique, whole bodies or body parts have to be transported from the exporting country to the importing country, possibly also in several weeks of sea transports. During transport, for example on railway wagons or in ships, the precursors and / or semi-finished products are exposed to atmospheric influences and must therefore be protected from corrosion for transport.

For corrosion protection during transport, a so-called "temporary corrosion protection" is usually applied, ie it is not yet the final corrosion protection coating which is intended to give the finished product lasting protection, but a coating which is to be used later Corrosion protection oils often have a double function and also act as auxiliaries for forming, for example during deep-drawing To ensure lubricity during the molding process to prevent breakage or cracking of the sheet.

When transporting molded parts made of galvanized steel, a special form of corrosion comes to the fore, namely the so-called "blackspot corrosion". This is not a surface form of corrosion, but a localized form of corrosion. One possible reason for this is that the metal surfaces can be contaminated with particles during transport. As a result of this particulate contamination, then often around the particles to locally very limited forms of corrosion. The particles may be, for example, dirt and / or salt particles or dirt-associated SaIz particles.

Especially with electrolytically galvanized steel, this form of corrosion also results in a significant change in the surface morphology. In the side view, for example, crater-shaped elevations are observed on the metal surface. In the automotive industry, such crater-shaped elevations are extremely disturbing, because they are rather reinforced by the subsequent cationic dip coating, but by no means equalized. As a result of the "blackspot corrosion", extremely time-consuming reworking of the already assembled bodywork is necessary.The reworking on the one hand leads to high costs for the automobile manufacturers and also disturbs the chronological sequence of the series production.Also, the corrosion resistance of the finished bodywork is also impaired, since repaired spots Represent germ cells for the corrosion of the commodity.

It is known to use N-acyl derivatives of sarcosine acid as corrosion inhibitors. JP 2007-039764 A discloses an anticorrosive oil composition containing a base oil as well as N-acyl derivatives of sarcosine acid or its salts or esters.

EP 1 092 788 A2 discloses a composition of an N-acylsarcosic acid and a substituted triazole in oil and their use for corrosion protection in metalworking fluids, hydraulic oils, gear oils or lubricating oils.

WO 01/088068 discloses an oil composition for the temporary treatment of metallic surfaces for simultaneous lubrication and protection against corrosion. The oil composition is a biodegradable composition which comprises at least two different triglycerides and at least one fatty acid ester of a monoalcohol and optionally at least one amide derivative from the condensation of a fatty acid and a mono-, di- or trialkanolamide. The compositions may further optionally comprise from 0.5% to 5% by weight of at least one corrosion inhibitor, which may also be half-imides or derivatives of N-acylsarcosine. The oils are applied in an amount of 0.5 to 3 g / m ² on the metallic surface.

DD 148 234 A1 discloses a corrosion protection and deep-drawing agent for cold-rolled strip and DD 218 775 A3 cooling lubricating oils which, in addition to other components, each contain oleosarcosine as a component.

DD 240 384 A1 discloses temporary corrosion protection lacquers comprising a film-forming polymer having a glass transition temperature below 20 ⁰ C, such as acrylate resins, alkylphenol resins or nitrocellulose, in a mixture of solvents such as toluene, ethylbenzene, butanol or butyl glycol. In addition, the anticorrosion paint contains a mixture of zinc octoate, zinc alkyl dithiophosphate, oleyl sarcosine, rapeseed fatty acid diethylamide, alkylnaphthalene and mineral oil. The treatment of galvanized steel is not disclosed.

DD 203 567 A1 discloses anticorrosion oils for the temporary corrosion protection of metallic surfaces of semi-finished and finished products from atmospheric corrosion during processing, storage and transport, for example overseas transports. The corrosion protection oils consist of 75 to 99.3 wt.% Of a mineral base oil having a viscosity of 1 to 1000 mm ² / s, 0.15 to 15 wt.% Of a reaction product of alkylarylsulfonic and barium hydroxide in the presence of alkylphenols, and 0.2 to 10% by weight of a mixture of in each case two of the following three components in a weight ratio of 1: 1, namely 1) amine salts of mono- or dialkylphosphoric acid esters, 2) mono-, di- or trialkanolamides of oleic acid or 3) a fatty acid 10 to 20 carbon atoms or their sarcoside. The corrosion protection oils were tested on cylindrical gray cast iron plates, ie carbon-containing cast iron, by means of a conventional climate change test. For the application of the disclosed anticorrosive oils, the font does not provide any further details beyond what has just been said.

US 5,555,756 discloses a method for improving the stretchability of a steel strip. For this purpose, the steel strip is first heated and then applied a liquid lubricant on the surface, which is then dried and forms a dry film on the surface. The applied amount is at least 10.8 mg / m ² . Subsequently, the steel strip is rolled out. The liquid lubricant preferably comprises water, a surfactant and an alkyl phosphate ester of the general formulas RO-P (= O) (OH) 2 or (RO) 2-P (= O) OH, where R is an alkyl group having 4 to 20 carbon atoms.

However, none of the writings mentioned deals with the problem of

"Blackspot corrosion" when transporting precursors, semi-finished products or finished products made of galvanized steel in an atmospheric environment.

The object of the invention was to provide an improved corrosion protection for the transport of precursors, semi-finished or finished products made of galvanized steel, can be effectively prevented by the Salzkorn- or Blackspot corrosion.

In a first aspect of the invention, a temporary oily anticorrosive coating has been found for galvanized steel containing N-acyl derivatives of sarcosinic acid, and is particularly well suited for preventing "black spot corrosion" in the transport of precursors, semi-finished products or finished products made of galvanized steel.

Accordingly, a method has been found for producing moldings from single-sided or double-sided galvanized sheet steel, wherein the method comprises, in this order, at least the subsequent steps

(1) applying an anticorrosion oil to the surface of a galvanized steel strip in an amount of 0.25 to 5 g / m ² , (2) transporting the coated galvanized steel strip to a molding facility, and

(3) separating and forming the galvanized steel strip into shaped articles made of sheet steel galvanized on one or both sides,

wherein the corrosion protection oil is a formulation of 50 to 99.5% by weight of at least one oil (A) having a boiling point of at least 300 ^° C.,

0.5 to 50% by weight of at least one corrosion-inhibiting active ingredient (B), as well as

0 to 30% by weight of further additives (C)

and wherein the quantities are in each case based on the total amount of all components of the anticorrosion oil, and wherein at least one of the corrosion-inhibiting active ingredients (B) is an active ingredient (B1) of the general formula R ¹ -CO-N (R ² ) - (CH ₂ ) _n -COOR ³ , where the radicals and indices R ¹ , R ² , R ³ and n have the following meaning:

R ¹ : a saturated or unsaturated, linear or branched hydrocarbon radical having 10 to 20 carbon atoms,

R ² : H or a linear or branched C ^{1 to} C ⁴ alkyl radical;

R ³ : H or a cation ¹ / _m Y ^{m +} , where m is a natural number from 1 to 3, and n: a natural number from 1 to 4,

and wherein the amount of the active ingredient (B1) is at least 0.5%.

In a preferred embodiment of the invention, the moldings are parts of automobile bodies or automobile bodies.

This solution was particularly surprising because N-acyl

Derivatives of sarcosinic acid, such as, for example, oleylsarcosic acid or laurylsarcosic acid, are commercially available corrosion inhibitors whose use is already known for a very wide variety of purposes. Nevertheless, such compounds have not yet been proposed for preventing "blackspot corrosion" in the course of transporting galvanized steel moldings.

In solving the problem, the difficulty arose that the known tests for determining the corrosion behavior of a commodity, such as the climate change test according to VDA, test sheet 621-415 or the salt spray test according to DIN EN 9227 are not always sufficient, the requirements for corrosion protection accurately and comprehensively during the transport of intermediate products, semi-finished products or finished products made of galvanized steel. Thus, the N-acyl-sarosic acid derivatives used according to the invention gave only moderate results in the salt spray test, so that these products would not actually have been considered solely on the basis of the salt spray test. In a further aspect of the invention, therefore, there is provided a test method which is particularly suitable for investigating the behavior of corrosion inhibitors in view of their property of preventing black spot corrosion.

More specifically, the following is to be accomplished for the invention:

test method

In the known salt spray tests for determining the corrosion resistance of metal sheets, the entire surface of the test sheet is exposed to a fine mist of saline water, i. it is a uniform corrosion load of the entire metal surface.

In the method developed according to the invention for testing galvanized steel sheets with regard to their resistance to "blackspot corrosion", on the other hand, the uniform corrosion load is replaced by a punctiform corrosion load.

To carry out the test, the galvanized steel sheets to be tested are stored horizontally in a climatic chamber. The galvanized steel sheets are coated for testing with the coating to be tested, of course, but also uncoated sheets can be tested for comparison purposes. Typical test panels have a surface area of about 0.01 m ² , but test panels of other surfaces can of course also be used. However, a size of 0.0025 m ² should generally not be undercut.

To perform the test, the top of the panels is sprinkled with saline test granules. In the simplest case, these may be salt grains, in particular NaCl grains, but it is also conceivable to use test grains of other materials, such as, for example, sand contaminated with NaCl, in order to be able to better model dirt grains. Of course, the grains may also be agglomerates of smaller grains. The grains should as a rule have a diameter of 0.1 to 1 mm, preferably 0.2 to 0.6 mm. Corresponding grain fractions can easily be provided by sieving. In this case, the surface is sprinkled in such a way that the grains are essentially arranged individually on the surface on the surface. The amount of grains should generally be from 1000 to 25000 grains / m ² , preferably 5000 to 15000 grains / m ² and for example about 10000 grains / m ² , ie with a sheet size of 1 dm ² about 100 grains. The thus prepared sheets are then stored for a defined time at a defined humidity and temperature in a suitable device for adjusting the climatic conditions. The test is preferably performed at 15 to 40 ⁰ C, particularly preferably at room temperature, but other test temperatures are of course conceivable. A relative humidity of 60 to 90%, for example 85%, and a test time of 12 to 96 h, for example 24 h, has proven useful. Of course, other test times are conceivable. In particular, one can study the corrosion over time. The test conditions can be adapted by a person skilled in the art, for example, to the climatic conditions prevailing during transport.

At the end of each test time, the surface of the sheet is optically evaluated for corrosion around the test grains. The evaluation can be done in particular photographically. The number of "black spots" on the metal sheet as well as the size of the corroded areas around the test grains can be evaluated, as well as the chronological course of the corrosion, for example, when "black spots" are observed for the first time, or The number of "blackspots" can be recorded as a function of time.

By means of the test according to the invention, a more practical assessment of the corrosion behavior of galvanized moldings in the course of transport processes can be achieved than with the known salt spray tests.

For example, the test of the anticorrosive oil used with the inhibitor (B1) according to the invention by means of a salt spray test gave only moderate results, so that this inhibitor would not have been considered for the present application due to the salt spray test. Only the test developed according to the invention revealed the particular suitability of the corrosion inhibitor (B1) for preventing blackspot corrosion.

Applied corrosion protection oil

According to the invention, the corrosion protection oil used is a formulation which comprises at least one oil (A), at least one corrosion-inhibiting active substance (B) and optionally further additives (C). On the one hand, the anticorrosive oil serves to protect against corrosion and furthermore has such good lubricating properties that it is also suitable as an aid for forming.

The boiling point of the base oil used (A) is usually at least

300 ⁰ C at 1 bar. The base oil (A) for the formulation can be mineral oils or synthetically produced oils. Suitable mineral oils may, for example, be be obtained by vacuum distillation of crude oil at about 350 to 500 ⁰ C. In particular, largely aromatics-free mineral oils are suitable. Synthetic oils include in particular poly-α-olefins, for example those of C12 to C30 olefins, polyisobutenes, various long-chain esters or silicone oils. Furthermore, higher melting paraffins and blends of these with oils and waxes and wax emulsions can be used. Of course, mixtures of several different oils can be used provided they are compatible with each other. Preferred for carrying out the invention are mineral oils and synthetic oils based on poly-α-olefins.

Further details of suitable base oils are for example published in "Lubricants and Lubrication" in Ullmann's Encyclopedia of Industrial Chemistry, Electronic Edt. 7 ^th Release, 2007, Wiley-VCH Verlag, Weinheim.

Particularly suitable oils are mineral oils with a kinematic viscosity at 20 ^° C. of 50 to 200 mm ² / s (measured to ASTM D 445), preferably 120 to 180 mm ² / s and particularly preferably 140 to 160 mm ² / s Pour point of -15 ° C to + 5 ° C, preferably -5 ° C to + 5 ° C measured according to ASTM D 97, a density measured at 15 ° C according to ASTM D 1298 from 0.85 to 0, 90 kg / l, preferably 0.88 to 0.90 kg / l and a flash point, determined according to ASTM D 92 of more than 180 ⁰ C, preferably more than 200 ⁰ C.

The amount of all oils (A) used together amounts to 50 to 99.5% by weight, preferably 70 to 90% by weight and particularly preferably 75 to 85% by weight, in each case based on the total amount of all components of the formulation used.

The formulation used according to the invention contains one or more corrosion-inhibiting active ingredients (B). According to the invention, these are at least one active ingredient (B1) of the following formula R ¹ -CO-N (R ² ) - (CH ₂ ) _n -COOR ³ . Here, the radicals R ¹ , R ² , R ³ and the index n have the following meaning:

R ¹ : a saturated or unsaturated, linear or branched hydrocarbon radical having 10 to 20 carbon atoms, preferably 12 to 18 carbon atoms and particularly preferably 16 to 18 carbon atoms, R ² : H or a linear or branched C ^{1 to} C 4 alkyl radical, preferably a methyl radical ;

R ³ : H or a cation ¹ / _m Y ^{m +} , where m is a natural number from 1 to 3, preferably 1 or 2 and particularly preferably 1. n: a natural number from 1 to 4, preferably 1 or 2 and more preferably 1. The radical R ¹ is preferably a monounsaturated radical having 17 carbon atoms. This radical is particularly preferably a radical derived from oleic acid. Preference is furthermore given to radicals derived from lauric acid.

The cations Y ^{m +} may in particular be alkali metal ions, in particular Li ⁺ , Na ⁺ or K ⁺ , alkaline earth metal ions or ammonium ions. To be mentioned as ammonium ions NH ⁴⁺ or organic radicals having ammonium ions [NRV] ^+, where it is ⁴ atoms each independently H or hydrocarbon radicals, in particular hydrocarbon radicals having 1 to 4 carbon in the R radicals. R ³ is preferably H ⁺ , Na ⁺ or NH ⁴ ⁺ . Of course, it can also be several different residues.

The preparation of the corrosion inhibitors (B1) can be carried out by methods known in the art, in particular by reacting sarcosic acid or its derivatives HN (R ² ) - (CH ₂ ) _n -COOR ³ with carboxylic acids R ¹ -COOH or reactive derivatives of the carboxylic acids such as the corresponding carboxylic acid anhydrides or halides. Corrosion inhibitors (B1) are commercially available.

Of course, mixtures of several different active ingredients (B1) can be used and mixtures of active compounds (B1) with different corrosion inhibiting agents (B2) are used.

The amount of all corrosion inhibitors (B) used together is 0.5 to 50% by weight, preferably 10 to 30% by weight and more preferably 15 to 25% by weight, based in each case on the total amount of all components of the formulation used.

However, the amount of all active ingredients (B1) together amounts to at least 0.5% by weight. If, in addition, further corrosion-inhibiting active compounds (B2) are present, the weight ratio (B1) / (B2) is at least 0.1, preferably at least 0.5, particularly preferably at least 0.8. Very particular preference is given to using exclusively corrosion-inhibiting active ingredients (B1).

The amount of the corrosion inhibitors (B1) used is therefore preferably from 0.5 to 50% by weight, in particular from 5.01 to 50% by weight, preferably from 10 to 30% by weight and more preferably from 15 to 25% by weight, in each case based on on the total amount of all components of the formulation used.

The anticorrosion oil formulation used according to the invention may optionally further comprise additives or auxiliaries (C). With such additives, the properties of the formulation can be adapted to the desired purpose. Examples of such additives (C) include carboxylic acid esters, free or partially neutralized carboxylic acids, emulsifiers, for example alkyl sulfonates or antioxidants, such as phenolic components, imidazoles, polyether phosphates, alkyl phosphates or succinimides, in particular polyisobutylene succinimides reacted with oligoamines, such as tetraethylenepentamine or ethanolamines. Furthermore, it is also possible to use phosphorous or phosphonic acid esters or else wear protection agents, for example zinc dithiophosphate. The person skilled in the art will make a suitable choice among the additives depending on the desired properties of the formulation.

The amount of all additives (C) used together is 0 to 30% by weight, preferably 0 to 20% by weight, particularly preferably 0.5 to 20% by weight and very particularly preferably 1 to 10% by weight, based in each case on the total amount of all components of the formulation used.

For use, the components (A) and optionally (B) and / or (C) are mixed.

The described formulation of a corrosion protection oil is used according to the invention for corrosion protection in the course of storage and transport of moldings made of galvanized sheet steel. The steel sheets usually have a thickness of 0.2 to 3 mm. The sheet steel can be galvanized on one or both sides.

The term "galvanized" includes, of course, steel sheets coated with Zn alloys, which may be hot-dip galvanized or electrolytically galvanized steel strips, Zn alloys for coating steel are known to those skilled in the art One of the typical constituents of zinc alloys is Al, Mg, Si, Mg, Sn, Mn, Ni, Co, and Cr, preferably Al or Mg. These may also be Al-Zn alloys The coatings may be substantially homogeneous coatings or also coatings with concentration gradients, and Zn-Mg alloys may also be preferred Zn-Mg alloy coated steel, for example galvanized steel, or it may be galvanized steel which additionally steamed with Mg. As a result, a surface Zn / Mg alloy can arise.

Such moldings are in particular those which can be used for cladding, facing or lining. Examples include automobile bodies or parts thereof, truck bodies, frames for two-wheelers such as motorcycles or bicycles, or parts for such vehicles such as

Mudguards or coverings, coverings for household appliances such as washing machines, dishwashers, tumble dryers, gas and electric cookers de, microwave ovens, freezers or refrigerators, cladding for technical appliances or equipment such as machines, control cabinets, computer housings or the like, architectural elements such as wall parts, facade elements, ceiling elements, window or door profiles or partition walls, including metal materials such as metal cabinets, Metal shelves, parts of furniture or fittings. Furthermore, it may also be hollow body for storage of liquids or other substances, such as cans, cans or tanks. The term "shaped body" also includes precursors for the production of said materials, such as steel strips or steel sheets.

The use is carried out by adding the anticorrosive oil before storage and / or transport in an amount of 0.25 to 5 g / m ² , preferably 0.5 to 3 g / m ² and particularly preferably 1 to 2.5 g / Apply m ² to the galvanized surface.

By "transport" is meant all types of transport operations in which the moldings are moved from one location to another, the first location may be, in particular, the fabrication site of the moldings, but may also be, for example The second location is, in particular, another manufacturing facility where the resulting moldings are further processed, for example, the first location may be a press shop where car bodies or body parts are manufactured and at the second location to an automobile production.

By "storage" is meant all types of storage operations, ranging from a few hours to a few days, or a prolonged storage period of a few weeks to a few months.

Process for the production of moldings

In a preferred embodiment of the method, the corrosion protection oil is used by means of the process according to the invention described below, in which moldings are produced from sheet steel galvanized on one or both sides.

As starting material for the process according to the invention galvanized steel strips are used. Galvanized steel strips usually have a thickness of 0.2 to 3 mm and a width of 0.5 to 2.5 m. Galvanized steel strips are commercially available for a wide variety of applications. It can be unilaterally galvanized steel strips on both sides. The person skilled in the art selects a suitable steel strip depending on the desired application. Of course, the term "galvanized" also includes steel strips coated with Zn alloys and suitable zinc alloys have already been described.

Process step (1)

In process step (1), the corrosion protection oil described above is applied to the surface of the galvanized steel strip. If it is a single-sided galvanized strip, the formulation used according to the invention is applied at least to the galvanized side; it can of course also be applied to the non-galvanized side. The non-galvanized side can also be treated with another anti-corrosion oil.

The application can be carried out, for example, by spraying, in particular with the assistance of an electrostatic field. Furthermore, the application can be carried out using a chemcoater or by immersion in an oil bath followed by squeezing or alternatively spraying the oil on the sheet followed by squeezing.

The amount of anticorrosion oil applied to the surface is generally 0.25 to 5 g / m ² , preferably 0.5 to 3 g / m ² and particularly preferably 1 to 2.5 g / m ² .

The application of the anticorrosion oil can preferably take place immediately after the production of the steel strip, that is typically in a steel or rolling mill.

However, this does not preclude applying the anticorrosive oil at a later date.

The corrosion-inhibiting active ingredient (B1) used according to the invention also acts as a surfactant and ensures a particularly uniform distribution of the oil on the metal surface. Furthermore, the active substance has strong IR absorptions, in particular the> C = O band, so that the application of the oil can be monitored and controlled particularly well by means of IR spectroscopy.

Process step (2)

In process step (2), the oiled, galvanized steel strip is transported to a production facility for moldings. For example, mold production facilities are stamping plants in which automobile bodies and / or parts of automobile bodies are manufactured. For transport, the galvanized steel strips are usually rolled up into coils ("coils"), preferably a truck and / or rail transport The steel strips can be transported immediately after process step (1) or they can be temporarily stored. before they are transported.

Process step (3)

In the molding facility, the oiled, galvanized steel strips are separated and formed into shaped bodies. Forming facilities for molded articles are, for example, stamping plants in which automobile bodies and / or parts of automobile bodies are produced.

When separating, the galvanized, oiled steel strip is cut into suitable pieces and, if appropriate, material particles are separated from the undivided material for further shaping. It can be both cutting and non-cutting separation techniques. The separation can be done for example by punching or cutting by means of suitable tools. The cutting can also be done thermally, for example by means of lasers or by means of sharp water jets. Examples of other separation techniques include techniques such as sawing, drilling, milling or filing. The cutting of the metal strip is sometimes referred to as "slabs".

During forming, moldings are produced from the individual sheets obtained during the separation by means of plastic deformation. It may be a cold or a hot forming. It is preferably a cold forming. They may, for example, be pressure forming, such as rolling or embossing, tensile drawing, such as drawing, deep drawing, collaring or pressing, tensile forming, such as length or width, bending, such as bending, rounding or folding, and shear forming, such as twisting or sliding. Details of such forming techniques are known to those skilled in the art. They are also recorded in the form of relevant standards, such as DIN 8580 or DIN 8584, for example. A particularly preferred method for carrying out the present invention is thermoforming.

In one embodiment of the invention, the anticorrosion oil applied in process step (1) remains on the surface and also acts as a lubricant for reshaping.

In another embodiment of the method, one can also clean the individual sheets after the separation but also first. This can be done for example by rinsing with water. After rinsing with water, the sheets can be squeezed off become. Subsequently, it is again possible to apply the corrosion protection or shaping oil used according to the invention in an amount of 0.5 to 50 g / m ² .

The shaped articles obtained can be further processed in further process steps in the same production site, for example by cleaning, applying a permanent corrosion protection and painting, if appropriate also after joining to assembled shaped bodies.

Process step (4)

In a preferred embodiment of the method, the shaped bodies obtained in step (3), for example parts of automobile bodies, are transported in a further method step (4) to a further production site, for example an automobile production. This is preferably a truck or rail transport. The moldings can be transported immediately after process step (3) or they can be stored temporarily before they are transported. In the further production site, the molded articles obtained according to step (3) are further processed.

Process step (5)

In the preferred embodiment of the method, the further processing comprises at least one process step (5), in which the shaped bodies obtained according to step (3) are joined with other shaped bodies to form assembled shaped bodies. This can be done for example by pressing, welding, soldering, gluing, screwing or riveting. For example, an automobile body can be assembled from several individual parts. For joining, a plurality of identical or different shaped parts obtained according to step (3) can be used, or different shaped bodies can also be used. For example, moldings of galvanized steel, non-galvanized steel and aluminum can be combined together to form an assembled molded body.

The assembled shaped bodies made of galvanized steel can then be further processed in the usual way to the intermediate or end products, for example by cleaning, phosphating and the application of different paint layers.

moldings

In a further aspect, the invention relates to molded articles made of sheet steel which is galvanized on one or both sides and which comprises a layer of anticorrosion oil applied to the galvanized surface in an amount of 0.25 to 5 g / m ² , where in the case of the anticorrosive oil has the already described composition. Preferred compositions have already been mentioned and preferred layer thicknesses are the values already mentioned. Examples of such moldings have also been mentioned above. The moldings may also be sheet metal or laser-welded blanks. They are preferably automobile bodies or parts of automobile bodies.

The production of the shaped bodies can preferably be carried out by the process according to the invention. However, it can in principle be done by other methods. So you can, for example, the corrosion protection of the steel strips and / or corrosion protection in the course of separation and forming to ensure the moldings by other methods, so apply, for example, using other corrosion inhibitors and the anticorrosion oil used according to the invention only after the production of the molding. This allows the molded body to be protected for transport. The application can be done for example by spraying.

Use of a corrosion protection oil

In a further aspect, the invention relates to the use of a corrosion protection oil for corrosion protection in the course of storage and transport of moldings made of galvanized steel sheet by applying the oil in an amount of 0.25 to 5 g / m ² on the surface of the molding, wherein the corrosion protection oil has the already described composition and preferred compositions, preferred layer thicknesses and examples of moldings have already been mentioned. The moldings may also be metal strips, in particular rolled-up metal strips, sheet metal sheets or laser-welded blanks. They are preferably automobile bodies or parts of automobile bodies. The application of the oil can take place by means of various techniques, for example by spraying.

Advantages of the invention

The use of the anticorrosive oil described above with the corrosion-inhibiting active compounds (B1) can particularly effectively avoid or at least significantly reduce the occurrence of "black spot corrosion." Furthermore, the anticorrosive oil used according to the invention comprises the base oil (A) and the corrosion inhibitor (B1 Furthermore, the moldings coated according to the invention can be glued without problems, without the anticorrosive oil hindering the bonding and finally the moldings can be cleaned and phosphated without the phosphating in view on Phosphate layer weight, homogeneity of the layer or the size of the crystals is impaired.

The following examples are intended to explain the invention in more detail:

Anti-corrosion formulation used:

The following corrosion inhibitor (B1) was used:

Oleylsarkosinsäure _I7 C H ₃ S-CO-N (CHS) -COOI-I

For the experiments, a commercial white oil was used for the one with the following properties:

Boiling point:> 300 ^° C

Density at 15 ° C: 0.887 kg / l;

Viscosity at 20 ^° C. (measured to ASTM D 445): 145 mm ² / s

Viscosity at 40 ^° C. (measured to ASTM D 445): 36 mm ² / s

Flash point (measured according to ASTM D 92): 214 ° C pour point (measured according to ASTM D 97): 3 ° C

The corrosion inhibitor was dissolved in the white oil in a concentration of 20% by weight.

Coating and test of the sheets:

With the obtained formulation, test plates of galvanized steel measuring 10 cm × 15 cm were coated in an amount of 1.5 g / m ² . For this purpose, the test sheet was placed on a precision balance and the formulation was added by means of a fine syringe in the stated amount to the surface of the sheet. The applied amount was then spread on the metal surface by means of a rubber roller with a smooth surface and a Shore A hardness of 50 under strong pressure.

For comparison purposes, a test sheet was only coated with the oil (A) without the addition of the corrosion inhibitor (B1).

For comparison purposes, a commercially available alkyl phosphoric ester (C 16 / C 18 -alkyl phosphoric acid ester) was furthermore used as anticorrosive oil. It was used without oil as a diluent. "Black Spot Test"

The sheets thus prepared are sprinkled with salt grains (NaCl) of a size of about 0.1 to 1 mm in size. The surface density was about 25,000 salt grains / m ² (about 250 salt grains / dm ² ). Subsequently, the sheets were stored horizontally for 24 h in a climatic chamber at 20 ⁰ C and 85% humidity. After storage, the sheets were rinsed and dried and photographically evaluated.

salt spray test

Furthermore, a standard salt spray test was carried out according to DIN EN 9227 with the sheets for comparison purposes, i. E. the entire metal surface was uniformly exposed to a fine salt mist in a test chamber.

discussion of the results

Figure 1 shows the comparative experiment without addition of the active ingredient (B1) and Figure 2 with addition of the active ingredient (B1). It can be seen that the number of "blackspots" is markedly lower in Figure 2. While the sheets treated with the anticorrosive oil without active ingredient (B1) show about 40 blackspots / dm ² (see Figure 1), the invention provides treated sheets less than 5 blackspots / dm ² , in some test sheets even only 0 - 1 spots / dm ² (see Figure 2).

Figures 3 and 4 show the test of the same sheets in a conventional salt spray test. Figure 3 shows a plate without active ingredient (B1) after 96 h salt spray test, Figure 4 shows the corresponding plate with active ingredient (B1). A certain effect of the active ingredient (B1) can also be seen in the salt spray test, but the test with active ingredient also shows only average results, due to which the active ingredient (B1) would not have been classified as particularly suitable for transport corrosion protection. In contrast, in the "blackspot test" according to the invention, the differences between the two sheets are much clearer.

FIG. 5 shows a picture of the sheet coated with a commercially available alkylphosphoric acid ester for comparison purposes after 96 h of test duration. A significant number of "blackspots" are already recognizable on this sheet as well: not every corrosion inhibitor is equally well suited as a corrosion inhibitor for transport corrosion protection.

Claims

claims

1. A process for the production of moldings from single-sided or double-sided galvanized sheet steel comprising - in this order - at least the following steps:

(1) applying a corrosion protection oil to the surface of a galvanized steel strip in an amount of 0.25 to 5 g / m ² ,

(2) transporting the oiled, galvanized steel strip to a molding facility, as well as

(3) separating and forming the oiled, galvanized steel strip into shaped articles made of sheet steel galvanized on one or both sides,

wherein the corrosion protection oil is a formulation of

50 to 99.5% by weight of at least one oil (A) having a flashpoint of at least 180 ^° C.,

0.5 to 50% by weight of at least one corrosion-inhibiting active ingredient (B) and also 0 to 30% by weight of further additives (C),

and the quantities are in each case based on the total amount of all components of the anticorrosion oil, characterized in that at least one of the corrosion-inhibiting active ingredients (B) is an active ingredient (B1) of the general formula R ¹ -CO-N (R ² ) - (CH ₂ ) _n -COOR ³ , where the radicals and indices R ¹ , R ² , R ³ and n have the following meaning:

R ¹ : a saturated or unsaturated, linear or branched hydrocarbon radical having 10 to 20 carbon atoms, R ² : H or a linear or branched C ¹ to C ⁴ alkyl radical;

with the proviso that at least 0.5% by weight of the active ingredient (B1) are used.

2. The method according to claim 1, characterized in that it is the corrosion protection oil (A) is a mineral oil.

3. The method according to claim 1 or 2, characterized in that the corrosion protection oil (A) has a kinematic viscosity, measured according to ASTM D 445 at 20 ⁰ C from 50 to 200 mm ² / s.

4. The method according to any one of claims 1 to 3, characterized in that the method after step (3) additionally comprises at least the following method step:

(4) transport of the shaped bodies produced in process step (3) into a further fabrication site,

5. The method according to any one of claims 1 to 4, characterized in that the method after step (4) additionally comprises at least the following method step:

(5) joining the moldings with other moldings to form assembled moldings.

6. The method according to any one of claims 1 to 3, characterized in that it is in the moldings produced in step (3) are parts of automobile bodies.

7. Process according to claim 5, characterized in that the assembled shaped bodies produced in step (5) are automobile bodies.

8. The method according to any one of claims 1 to 7, characterized in that the metal strip in the course of process step (3) first separates into individual sheets, cleans and before forming again a corrosion protection oil of the given composition in an amount of 0.25 to 3 g / m ² applies.

9. The method according to any one of claims 1 to 8, characterized in that it is in the transport according to the method steps (2) and / or (4) is a truck or a rail transport.

10. The method according to any one of claims 1 to 9, characterized in that the corrosion protection oil has the following composition:

70 to 90% by weight of at least one oil (A) having a flash point of at least 180 ^° C.,

• 10 to 30 wt.% Of at least one corrosion-inhibiting active ingredient (B1), and • 0 to 20% by weight of further additives (C).

1 1. molded body made of sheet steel galvanized on one or both sides, comprising a layer of a corrosion protection oil applied to the galvanized surface in an amount of 0.25 to 5 g / m ² , wherein the corrosion protection oil is a formulation

70 to 90% by weight of at least one oil (A) having a flash point of at least 180 ^° C., 10 to 30% by weight of at least one corrosion-inhibiting active ingredient

(B1), as well

0 to 20% by weight of further additives (C),

in which the quantities are in each case based on the total amount of all components of the anticorrosion oil, characterized in that at least one of the corrosion-inhibiting active ingredients is an active ingredient (B1) of the general formula R ¹ -CO-N (R ² ) - ( CH ₂ ) _n -COOR ³ , where the radicals and indices R ¹ , R ² , R ³ and n have the following meaning:

R ¹ : a saturated or unsaturated, linear or branched hydrocarbon radical having 10 to 20 carbon atoms, R ² : H or a linear or branched C ¹ to C ⁴ alkyl radical; R ³ : H or a cation ¹ / _m Y ^{m +} , where m stands for a natural number from 1 to 3, and n: a natural number from 1 to 4.

12. Shaped body according to claim 10, characterized in that these are parts of automobile bodies or car bodies.

13. Use of a corrosion protection oil for corrosion protection in the course of storage and / or transport of moldings from one or both sides galvanized steel sheet by applying the oil in an amount of 0.25 to 5 g / m ² on the surface of the molding, wherein the formulation of the corrosion protection oil

• 10 to 30 wt.% Of at least one corrosion-inhibiting active ingredient (B), and

0 to 20% by weight of further additives (C), in which the quantities are in each case based on the total amount of all components of the anticorrosion oil, characterized in that at least one of the corrosion-inhibiting active substances (B) is an active ingredient (B1) of the general formula R ¹ -CO-N (R ² ) - (CH ₂ ) _n -COOR ³ , where the radicals and indices R ¹ , R ² , R ³ and n have the following meaning:

R ² : H or a linear or branched C ^{1 to} C ⁴ alkyl radical; R ³ : H or a cation ¹ / _m Y ^{m +} , where m stands for a natural number from 1 to 3, and n: a natural number from 1 to 4.

14. Use according to claim 13, characterized in that it is the moldings are automobile bodies.

15. Method for testing galvanized steel sheets with regard to their resistance to "blackspot corrosion", in which the zinc-plated steel sheets to be tested, which may optionally have a corrosion protection coating on the galvanized surface, are stored horizontally in a climatic chamber containing saline Test grains of a diameter of 0.1 to 1 mm in an amount of 1000 to 25000 grains / m ² sprinkled so that the grains are substantially each individually on the surface, the sheet thus prepared then for a defined time and temperature at a relative Humidity of 75 to 95% stores and after the test, the surface of the sheet optically

Evaluates the corrosion around the test grains around.