EP2373769B1 - Method for producing bodies from sheet steel galvanized on one or both sides - Google Patents

Description

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

The manufacture of galvanized steel sheet metal finished products, such as automobile bodies or parts thereof, equipment panels, cladding, ceiling panels 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 storing and transporting. These are rewound for processing, separated into smaller pieces, formed by suitable techniques such as punching, drilling, folding, profiling and / or deep drawing. Larger components such as automobile bodies may be obtained by assembling a plurality of parts. After molding and joining, the product can be painted, for example.

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 call in the export of certain vehicles deliberately not ready assembled 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, i. it is not yet the final anti-corrosive coating which is intended to give permanent protection to the finished product, but a coating which is removed at a later stage in the process and replaced by the final anti-corrosion coating. For temporary corrosion protection, the steel strips are usually provided with a coating of a corrosion protection oil. Anti-corrosion oils often have a dual function and also act as auxiliaries for forming, for example during deep drawing. The forming oil should ensure the necessary lubricity in the deformation 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 salt 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 complex reworking of the already assembled body is necessary. The rework leads on the one hand to high costs for the car manufacturers and also disturbs the timing of the series production. In addition, the corrosion resistance of the finished body is affected, as 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 comprising 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 strip and DD 218 775 A3 Cooling lubricating oils containing, among other components, each oleylsarcosine as a component.

DD 240 384 A1 discloses temporary anticorrosive coatings comprising a film-forming polymer having a glass transition temperature below 20 ° C, such as acrylate resins, alkylphenol resins or nitrocellulose, in a mixture of solvents, such as toluene, ethylbenzene, butanol or butylglycol. In addition, the anti-corrosion varnish contains a mixture of zinc octoate, zinc alkyldithiophosphate, oleylsarcosine, rapeseed fatty acid diethylamide, alkylnaphthalene and mineral oil. The treatment of galvanized steel is not disclosed.

DD 203 567 A1 discloses anticorrosive oils for the temporary corrosion protection of metallic surfaces of semi-finished and finished products from atmospheric corrosion during processing, storage and transport, eg 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 having 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 of 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, there has been found a temporary oily anticorrosive coating for galvanized steel containing N-acyl derivatives of sarcosinic acid which is particularly well suited for preventing "black spot corrosion" in the transport of precursor, semi-finished or finished products of galvanized steel Steel is suitable.

1. (1) Auftragen eines Korrosionsschutzöls auf die Oberfläche eines verzinkten Stahlbandes in einer Menge von 0,25 bis 5 g/m²,
2. (2) Transportieren des beschichteten, verzinkten Stahlbandes zu einer Fabrikationsstätte für Formkörper, sowie
3. (3) Trennen und Umformen des verzinkten Stahlbandes zu Formkörpern aus einseitig oder beidseitig verzinktem Stahlblech,

wobei es sich bei dem Korrosionsschutzöl um eine Formulierung aus

• 50 bis 99,5 Gew. % mindestens eines Öls (A) mit einem Siedepunkt von mindestens 300°C,
• 0,5 bis 50 Gew. % mindestens eines korrosionsinhibierenden Wirkstoffes (B), sowie
• 0 bis 30 Gew. % weiteren Additive (C)

handelt, und wobei die Mengenangaben jeweils auf die Gesamtmenge aller Komponenten des Korrosionsschutzöls bezogen sind, und wobei es sich bei mindestens einem der korrosionsinhibierenden Wirkstoffe (B) um einen Wirkstoff (B1) der allgemeinen Formel R¹-CO-N(R²)-(CH₂)_n-COOR³ handelt, wobei die Reste und Indices R¹, R², R³ und n die folgende Bedeutung haben:

• R¹: ein gesättigter oder ungesättigter, linearer oder verzweigter Kohlenwasserstoffrest mit 10 bis 20 Kohlenstoffatomen,
• R²: H oder ein linearer oder verzweigter C₁- bis C₄-Alkylrest;
• R³: H oder ein Kation ¹/_mY^m+, wobei m für eine natürliche Zahl von 1 bis 3 steht, und
• n: eine natürliche Zahl von 1 bis 4,

und wobei die Menge des Wirkstoffes (B1) mindestens 0,5 % beträgt.Accordingly, a method has been found for producing moldings from single-sided or double-sided galvanized sheet steel, wherein the method-in this order-comprises at least the subsequent steps

1. (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. (2) transporting the coated, galvanized steel strip to a molding facility, as well as
3. (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

• From 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 wt.% Of at least one corrosion-inhibiting active ingredient (B), and
• 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 sarcosine acid, such as, for example, oleylsarcosic acid or laurylsarcosic acid, are commercially available corrosion inhibitors whose use for various purposes is already known. 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 during transport of precursors, semi-finished products or finished products made of galvanized steel exactly and comprehensively. 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, 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 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 carried out at 15 to 40 ° C, more preferably at room temperature, but of course other test temperatures are 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 the 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 sheet as well as the size of the corroded areas around the test grains can be evaluated. Furthermore, the chronological course of the corrosion can be logged. For example, it is possible to record when "black spots" are being observed for the first time, or the number of "black spots" 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 generally at least 300 ° C at 1 bar. The base oil (A) for the formulation can be mineral oils or synthetically produced oils. Suitable mineral oils may be, for example be obtained by vacuum distillation of crude oil at about 350 to 500 ° C. In particular, largely aromatics-free mineral oils are suitable. Synthetic oils include in particular poly-α-olefins, for example those of C ₁₂ to C ₁₄ 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 in " Lubricants and Lubrication "in Ullmann's Encyclopedia of Industrial Chemistry, Electronic Edt. 7th 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 ° C, preferably more than 200 ° 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.

R¹:

ein gesättigter oder ungesättigter, linearer oder verzweigter Kohlenwasserstoffrest mit 10 bis 20 Kohlenstoffatomen, bevorzugt 12 bis 18 Kohlenstoffatomen und besonders bevorzugt 16 bis 18 Kohlenstoffatomen,

R²:

H oder ein linearer oder verzweigter C₁- bis C₄-Alkylrest, bevorzugt ein Methylrest;

R³:

H oder ein Kation ¹/_mY^m+, wobei m für eine natürliche Zahl von 1 bis 3, bevorzugt 1 oder 2 und besonders bevorzugt 1 steht.

n:

eine natürliche Zahl von 1 bis 4, bevorzugt 1 oder 2 und besonders bevorzugt 1.

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. Named ammonium ions are NH ⁴⁺ or ammonium ion [NR ⁴ ₄ ] ⁺ containing organic radicals, where the radicals R ^{4 are} each independently H or hydrocarbon radicals, in particular hydrocarbon radicals having 1 to 4 carbon atoms. 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 anticorrosive oil formulation used according to the invention may optionally also contain additives or adjuvants (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. Phosphoric or phosphonic acid esters can also be used or wear protection agents, such as 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.

Of course, the term "galvanized" also includes steel sheets which are coated with Zn alloys. These may be hot-dip galvanized or electrolytically galvanized steel strips. Zn alloys for coating steel are known to the person skilled in the art. Depending on the desired application, the skilled person will select the type and amount of alloying components. Typical constituents of zinc alloys include in particular Al, Mg, Si, Mg, Sn, Mn, Ni, Co and Cr, preferably Al or Mg. These may also be Al-Zn alloys in which Al and Zn in approximately the same amount are available. The coatings may be substantially homogeneous coatings or even coatings having concentration gradients. Further preferred may be Zn-Mg alloys. This may be coated with a Zn-Mg alloy steel, for example. Hot-dip galvanized steel, or it may be galvanized steel, which was additionally vapor-deposited 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 fenders or panels, linings for household appliances such as washing machines, dishwashers, tumble dryers, gas and electric stoves, Microwave ovens, freezers or refrigerators, covers for technical equipment or devices, such as machines, control cabinets, computer cases or the like, architectural elements, such as wall parts, facade elements, ceiling elements, window or door profiles or partition walls, furniture made of metallic 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" are meant all types of transport operations in which the moldings are moved from one place to another. The first location may be, in particular, the fabrication site of the moldings, but it may also be, for example, an intermediate storage facility. The second location is, in particular, another production site in which the shaped bodies obtained are further processed. By way of example, the first location may be a press shop in which automobile bodies or body parts are manufactured, and the second location may be an automobile production.

"Storage" means all types of storage operations. It may be a short interim storage of a few hours to a few days or even a longer storage 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 intended use.

Of course, the term "galvanized" also includes steel strips which are coated with Zn alloys. 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 tape, the formulation used in the invention is applied at least on 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 ingredient 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"). It is preferably a truck and / or rail transport. The steel strips can be transported immediately after 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. For example, mold production facilities are stamping plants in which automobile bodies and / or parts of automobile bodies are manufactured.

When separating, the galvanized, oiled steel strip is cut into suitable pieces and optionally separated material particles 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 moldings obtained can be further processed in further process steps in the same production facility, for example by cleaning, applying a permanent corrosion protection and painting, optionally also after joining to assembled moldings.

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 moldings of sheet metal galvanized on one or both sides, which comprise a layer of anticorrosion oil applied to the galvanized surface in an amount of 0.25 to 5 g / m ² , wherein the corrosion protection 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 be carried out by various techniques, for example by spraying.

Advantages of the invention

By means of the use of the corrosion protection oil described with the corrosion-inhibiting active ingredients (B1), the occurrence of "blackspot corrosion" can be avoided or at least significantly reduced in a particularly effective manner. Furthermore, the anticorrosion oil of the base oil (A) and the corrosion inhibitor (B1) used according to the invention supports the forming, in particular the deep drawing, slitting and Rolliumformung by an excellent lubrication performance. Furthermore, the moldings coated according to the invention can be glued without problems, without the anticorrosive oil hindering the bond and finally the moldings can be cleaned and phosphated without the phosphating with respect to 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:
Oleylsarcosinic acid C ₁₇ H ₃₃ -CO-N (CH ₃ ) -CH ₂ -COOH

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 according to ASTM D 445): 145 mm ² / s Viscosity at 40 ° C (measured according 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 vigorous pressing.

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 acid ester (C ₁₆ / C ₁₈ -alkyl phosphoric acid ester) was also 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 approximately 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 ° 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

illustration 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" in Figure 2 is significantly lower. While the treated with the anticorrosive oil without active ingredient (B1) sheets show about 40 blackspots / dm ² (see illustration 1 ), one finds with the inventively 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 sheet without active ingredient (B1) after 96 h salt spray test, Figure 4 the corresponding sheet with active ingredient (B1). A certain effect of the active substance (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 substance (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.

Figure 5 shows a recording of the comparative for comparison with a commercial alkylphosphoric acid coated sheet after 96 h experimental duration. Also on this sheet is already a significant number of "black spots" to recognize. Not every corrosion inhibitor is equally well suited as a corrosion inhibitor for transport corrosion protection.

Claims (14)

1. A method of producing shaped articles made from single-sidedly or double-sidedly galvanized steel sheet, comprising at least following steps - in following chronological order:

   (1) applying a corrosion preventive oil to the surface of a galvanized steel strip in an amount of 0.25 to 5 g/m²

   (2) transporting the oiled, galvanized steel strip to a fabrication site for shaped articles, and

   (3) separating and forming the oiled, galvanized steel strip into shaped articles made from single-sidedly or double-sidedly galvanized steel sheet,

   wherein the corrosion preventive oil is from a formulation of

   • 50 to 99.5% by weight of at least one oil (A) having a flash point of at least 180° C., measured in accordance with ASTM D92

   • 0.5 to 50% by weight of at least one active corrosion inhibitor substance (B), and

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

   and the percentages being based in each case on the total amount of all of the components of the corrosion preventive oil, characterized in that at least one of the active corrosion inhibitor substances (B) is an active substance (B1) of the general formula<
   R¹-CO-N(R²)-(CH₂)_n-COOR³, the definitions of the radicals and indices R¹, R², R³, and n being as follows:

   R¹: a saturated or unsaturated, linear or branched hydrocarbon radical having 10 to 20 carbon atoms,

   R²: H or a linear or branched C₁ to C₄ alkyl radical,

   R³: H or a cation ¹/_m Y^m+, wherein m is a natural number from 1 to 3, and

   n: a natural number from 1 to 4,

   with the provision that at least 0.5% by weight of the active substance (B1) is used.
2. The method according to claim 1, characterized in that the corrosion preventive oil (A) is a mineral oil.
3. The method according to claim 1 or 2, characterized in that the corrosion preventive oil (A) has a kinematic viscosity, measured in accordance with ASTM D 445 at 20° C., of 50 to 200 mm²/s.
4. The method according to one of the claims 1 to 3, characterized in that the method after step (3) further comprises at least the following step:
   (4) transporting the shaped articles produced in step (3) to a further fabrication site.
5. The method according to one of the claims 1 to 4, characterized in that the method after step (4) further comprises at least the following step:
   (5) joining the shaped articles to other shaped articles to form assembled shaped articles.
6. The method according to one of the claims 1 to 3, characterized in that the shaped articles produced in step (3) are parts of automobile bodies.
7. The method according to claim 5, wherein the assembled shaped articles produced in step (5) are automobile bodies.
8. The method according to one of the claims 1 to 7, characterized in that the metal strip during method step (3) is at first separated into individual sheets, cleaned and again applied with a corrosion preventive oil of the stated composition in an amount of 0.25 to 3 g/m².
9. The method according to one of the claims 1 to 8, characterized in that the transport of step (2) and/or of step (4) is transport by truck or by rail.
10. The method according to one of the claims 1 to 9, characterized in that the composition of the corrosion preventive oil comprises:

    • 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 active corrosion inhibitor substance (B1), and

    • 0 to 20% by weight of further additives (C).
11. A shaped article made from single-sidedly or double-sidedly galvanized steel sheet, comprising a film of a corrosion preventive oil applied to the galvanized surface in an amount of 0.25 to 5 g/m², the corrosion preventive oil is a formulation of

    • 70 to 90% by weight of at least one oil (A) having a flash point of at least 180° C., measured in accordance with ASTM D92

    • 10 to 30% by weight of at least one active corrosion inhibitor substance (B), and

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

    and the percentages being based in each case on the total amount of all of the components of the corrosion preventive oil, characterized in that at least one of the active corrosion inhibitor substances (B) is an active substance (B1) of the general formula
    R¹-CO-N(R²)-(CH₂)_n-COOR³, the definitions of the radicals and indices R¹, R², R³, and n being as follows:

    R¹: a saturated or unsaturated, linear or branched hydrocarbon radical having 10 to 20 carbon atoms,

    R²: H or a linear or branched C₁ to C₄ alkyl radical,

    R³: H or a cation ¹/_m Y^m+, wherein m is a natural number from 1 to 3, and

    n: a natural number from 1 to 4,

    wherein the amount of all active substances (B1) totalled is at least 0.5% by weight.
12. The shaped article according to claim 11, characterized in that these is parts of automobile bodies or is automobile bodies.
13. Use of a corrosion protection oil for preventing corrosion in the course of storage and/or transport of a shaped article made from single-sidedly or double-sidedly galvanized steel sheet, by applying the oil to the shaped-article surface in an amount of 0.25 to 5 g/m², wherein the corrosion preventive oil being a formulation of

    • 70 to 90% by weight of at least one oil (A) having a flash point of at least 180° C., measured in accordance with ASTM D92

    • 10 to 30% by weight of at least one active corrosion inhibitor substance (B), and

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

    wherein the percentages being based in each case on the total amount of all of the components of the corrosion preventive oil, characterized in that at least one of the active corrosion inhibitor substances (B) is an active substance (B1) of the general formula
    R¹-CO-N(R²)-(CH₂)_n-COOR³, the definitions of the radicals and indices R¹, R², R³, and n being as follows:

    R¹: a saturated or unsaturated, linear or branched hydrocarbon radical having 10 to 20 carbon atoms,

    R²: H or a linear or branched C₁ to C₄ alkyl radical,

    R³: H or a cation ¹/_m Y^m+, wherein m is a natural number from 1 to 3, and

    n: a natural number from 1 to 4,

    wherein the amount of all active substances (B1) totalled is at least 0.5% by weight.
14. Use according to claim 13, wherein the shaped articles are automobile bodies.

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