EP2373770B1 - Method for producing form 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 comprises at least one Phosphorsäurepolyoxyalkylenester.

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 phosphoric acid esters with alkoxy groups as corrosion inhibitors.

DE 27 56 747 A1 discloses the use of phosphoric acid esters, which are obtainable by reacting phosphoric acids with alkoxylated polyols, for example polypropylene glycol, as low-foam corrosion inhibitors and lubricants.

US 4,360,474 discloses derivatives of polyphosphoric acid half-esters and their use as corrosion inhibitors, wherein the ester groups are polyalkylene groups.

US 4,684,475 discloses a radiator protection mixture which contains, among other components as a corrosion inhibitor, an alkylene oxide-containing organophosphate.

WO 00/42135 discloses processing of metals using metalworking fluids containing oxyalkylene group-containing phosphonic acid esters.

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 of the general formula RO-P (= O) (OH) ₂ or (RO) ₂ -P (= O) OH, wherein R is an alkyl group having from 4 to 20 carbon atoms. Phosphoric acid esters of alkoxylated alcohols are not disclosed.

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 corrosion protection coating for galvanized steel containing phosphoric acid polyoxyalkylene esters has been found, and is particularly well suited for preventing "black spot corrosion" in the transport of precursors, semi-finished or finished products of galvanized steel.

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 das Korrosionsschutzöl mindestens 20 bis 100 Gew. %, bezogen auf die Gesamtmenge aller Komponenten des Korrosionsschutzöls, mindestens eines Phosphorsäureesters (A) der allgemeinen Formel
   
           [R²-(-O-CH(R¹)-CH₂-)_n-O-]_k-P(=O)-(OX)_3-k
   
   umfasst, und wobei R¹, R², X, n und k die folgende Bedeutung haben:

   k:

   1 oder 2,

   n:

   eine Zahl von 10 bis 70,

   R¹:

   unabhängig voneinander ein Rest ausgewählt aus der Gruppe von H, C₁-bis C₁₀-Alkylresten oder arylsubstituierten C₂- bis C₁₀-Alkylresten, mit der Maßgabe, dass es sich bei mindestens 50 mol % der Reste R¹ um einen Methylrest handelt,

   R²:

   H oder ein C₁- bis C₃₀-Alkylrest,

   X:

   H oder ein Kation 1/mY^m+, wobei m für eine natürliche Zahl von 1 bis 3 steht.

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 anticorrosive oil at least 20 to 100 wt.%, Based on the total amount of all components of the anticorrosive oil, at least one phosphoric acid ester (A) of the general formula
   
   [R ² - (- O-CH (R ¹ ) -CH ₂ -) _n -O-] _k -P (= O) - (OX) _3-k
   
   and wherein R ¹ , R ² , X, n and k have the following meaning:

   k:

   1 or 2,

   n:

   a number from 10 to 70,

   R ^1:

   independently of one another a radical selected from the group of H, C _{1 to} C ₁₀ -alkyl radicals or aryl-substituted C ₂ to C ₁₀ -alkyl radicals, with the proviso that at least 50 mol% of the radicals R ¹ is a methyl radical .

   R ² :

   H or a C ₁ - to C ₃₀ -alkyl radical,

   X:

   H or a cation 1 / mY ^{m +} , where m stands for a natural number from 1 to 3.

Furthermore, such a corrosion protective coating containing moldings of galvanized steel have been found. In a preferred embodiment of the invention, the moldings are parts of automobile bodies or automobile bodies.

This solution was particularly surprising because polyoxyalkylenephosphoric acid esters 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.

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 used 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, you can also study 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 in the invention with the inhibitor (A) 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 (A) for preventing "blackspot" corrosion.

Applied corrosion protection oil

According to the invention, a corrosion protection oil is applied to the metal surface to protect against "blackspot corrosion" in the course of storage and transport of one-sided or double-sided galvanized steel sheet, wherein the corrosion protection oil 20 to 100 wt.% Of at least one Phosphorsäurepolyoxyalkylenesters (A). The quantity refers to the total amount of all components of the corrosion protection oil. The anticorrosive oil further preferably contains a diluent in an amount of up to 80% by weight with respect to all components of the anticorrosive oil and may further comprise other components. Worth mentioning here are the typical additives and additives of corrosion protection oils.

The phosphoric acid polyoxyalkylene esters used have the general formula (I)

[R ² - (- O-CH (R ¹ ) -CH ₂ -) _n -O-] _k -P (= O) - (OX) _3-k (I)

on.

The radicals R ¹ are hereby independently a radical selected from the group of H, C ₁ - to C ₁₀ -alkyl radicals or aryl-substituted C ₂ - to C ₁₀ -alkyl radicals, with the proviso that at least 50 mol% of the Radicals R ¹ is a methyl radical.

Examples of C ₁ to C ₁₀ alkyl radicals include methyl, ethyl, 1-propyl, 1-butyl, 1-pentyl, 1-hexyl or 1-octyl. Examples of aryl-substituted C ₂ - to C ₁₀ -alkyl radicals include 2-arylethyl radicals, in particular 2-phenylethyl radicals. R ¹ is preferably a radical selected from the group of H, methyl or ethyl radicals, ie the polyoxyalkylene block is a block based on ethylene, propylene or butylene oxide units. Preferably, at least 60 mol%, particularly preferably at least 80 mol% and very particularly preferably at least 95 mol% of the radicals R ¹ is a methyl radical. Of course, R ^{1 can} also be exclusively methyl radicals.

The radical R ² is H or a straight-chain or branched C ₁ - to C ₃₀ -alkyl radical. In the case of alkyl radicals, preference is given to straight-chain or branched C ₁ - to C ₆ -alkyl radicals, and more preferably to methyl or ethyl radicals.

Preferably, R ² is H.

The number n is a number from 10 to 70. It is known to those skilled in the art of alkoxylation that these are average values. N is preferably from 20 to 60 and more preferably from 25 to 40.

If the polyoxyalkylene blocks have different radicals R ¹ , the various alkylene oxide units can be randomly incorporated into the block or they can be block copolymers or gradient copolymers. It is also known to those skilled in the art of alkoxylation that the orientation in which an alkylene oxide moiety is incorporated into a polyoxyalkylene oxide chain may depend on the reaction conditions; Thus, structures of the type R ² - (- O-CH (R ¹ ) -CH ₂ -) _n -O- as well as R ² - (- O-CH ₂ -CH (R ¹ ) -) _n are intended with the above formula -O- includes his.

X is H or a cation 1 / mY ^{m +} , where m is a natural number from 1 to 3, ie it may be an acidic ester or a salt thereof. Of course, it may also be several different radicals X.

The cations Y ^{m +} can be alkali metal ions, for example Li ⁺ , Na ⁺ or K ⁺ , alkaline earth metal ions or ammonium ions. To name as ammonium ions NH ₄ ⁺ or organic radicals containing ammonium ions [NR ⁴ ₄ ] ⁺ , wherein the radicals R ^{4 are} each independently H or hydrocarbon radicals, in particular hydrocarbon radicals having 1 to 20 carbon atoms, it also being possible for the radicals to be further substituted. Particularly noteworthy are ammonium ions derived from di- or triethanolamine and from fatty amines.

Preferably, X is H, i. the phosphoric acid esters are preferably used in the acid form.

The number k may be 1 or 2, i. they are phosphoric monoesters or phosphoric diesters. K preferably has the value 1.

The described Phosphorsäurepolyoxyalkylenester can be carried out in a manner known in principle by esterifying alcohols of the general formula R ² - (- O-CH (R ¹ ) -CH ₂ -) _n -OH with phosphoric acids or phosphorus pentoxide. Polyphosphoric acid can advantageously be used for this purpose, which can bind water formed in the course of the esterification. A suitable production method is, for example, in DE 27 56 747 A1 described. The reaction generally produces a mixture of monoesters and diesters, whereas triesters are generally not formed. Preferred mixtures for carrying out the invention are those in which the monoesters are present in an amount of at least 80 mol% relative to the amount of all esters. The reaction mixtures may also contain residues of phosphoric acid and / or polyphosphoric acid as secondary components and possibly also contain other products. For the case R ² = H, for example, diesters of the formula (OH) ₂ P (= O) - (- O-CH (R ¹ ) -CH ₂ -) _n -OP (= O) (OH) ₂ can be formed. Such minor components can be separated before use; but it is usually possible to use the unpurified products directly in the process of the invention.

Of course, mixtures of several different Phosphorsäurepolyoxyalkylenester (I) can be used. The amount of Phosphorsäurepolyoxyalkylenester (I) is 20 to 100 wt.% With respect to the amount of all components of the anticorrosion oil, preferably 25 to 80 wt.%, Particularly preferably 30 to 70 wt.% And most preferably 30 to 60 wt.%.

In addition to the phosphoric acid polyoxyalkylene esters (A), the anticorrosive oil may further comprise at least one diluent (B). With the help of diluents, the viscosity of the anticorrosion oil can be adjusted to the desired value, so that optimum processing is possible. The choice of diluents is not limited provided they are miscible with the phosphoric acid polyoxyalkylene esters (A). Particularly suitable are organic solvents which have a certain polarity, while water or nonpolar organic Solvents such as hydrocarbons should not be used. Suitable diluents include oxygen-containing organic solvents, especially those comprising ether and / or alcohol functions.

Suitable diluents include in particular oligo- and polyoxyalkanediols or the corresponding etherified products such as, for example, di-, tri-, tetra-, oligo- and polypropylene glycols. Preference is given to diluents (B) of the general formula R ³ - (- O-CH (CH ₃ ) -CH ₂ -) _m -OR ³ (II), where the radicals R ³ independently of one another are H or C ₁ - to C ₄ alkyl, preferably H or methyl, and particularly preferably are H. The radical m in formula (II) is a number from 2 to 20, preferably 2 to 12 and particularly preferably 2 to 5. Dipropylene glycol is particularly suitable as a diluent.

The amount of all diluents (B) used together is up to 80% by weight, preferably 20 to 75% by weight, particularly preferably 30 to 70% by weight and very particularly preferably 40 to 70% by weight, based in each case on the total amount of all Components of the formulation used.

The anticorrosion oil used according to the invention may optionally also contain additives or auxiliaries (C). With such additives, the properties of the oil can be adapted to the desired purpose.

Examples of such additives (C) include carboxylic acid esters, free or partially neutralized carboxylic acids, emulsifiers such as 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 phosphoric or phosphonic acid esters or anti-wear 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 additives and auxiliaries used together amounts to 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 Total amount of all components of the formulation used.

In a preferred embodiment of the invention, from 20 to 80% by weight of the phosphoric polyoxyalkylene ester (A) may be used in admixture with 80 to 20% by weight of a diluent (B) of the general formula (II), preferably from 30 to 70% by weight (A ) in a mixture with 70 to 30 wt.% (B) of the formula (II), wherein the sum of (A) and (B) with respect to the sum of all the components of such a mixture at least 80% by weight, preferably at least 90% by weight and particularly preferably 100% by weight.

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

The anticorrosion oil described is used according to the invention for corrosion protection in the course of storage and / or 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.

The 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, dryers, gas and electric stoves, microwave ovens, freezers or refrigerators , Cladding for technical equipment or facilities such as machinery, cabinets, computer cases or the like, architectural elements such as wall parts, facade elements, ceiling elements, window or door profiles or partitions, 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 oils are used by means of the process according to the invention described below, in which molded articles are produced from steel sheet 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 shown.

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 (A) used according to the invention furthermore also ensures a particularly uniform distribution of the oil on the metal surface. Furthermore, the active ingredient has strong IR absorptions, in particular the> P = 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, if appropriate, material particles of the undivided material for further shaping separated. 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. 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 directly after step (3) or they can be temporarily stored 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 made of steel sheet 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 , the anticorrosive oil having the composition already described. Preferred compositions 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 anticorrosive oil used in the invention supports the forming, in particular the deep drawing, slitting and roll forming by an excellent lubricating performance. 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 being impaired with regard to phosphate layer weight, homogeneity of the layer or the size of the crystals.
The following examples are intended to explain the invention in more detail:

Anti-corrosion formulation used:

For the experiments, a Phosphorsäurepolyoxyalkylenester starting from polypropylene glycol and polyphosphoric acid according to the DE 27 56 747 A1 Prepared example 2 (n about 34). For the experiments, a 35% mixture of the resulting Phosphorsäurepolyoxyalkylenesters was used with dipropylene glycol.

For comparative experiments, a commercially available alkyl phosphoric acid ester (C ₁₆ / C ₁₈ -alkyl phosphoric acid ester) was used as corrosion protection oil. It was used without diluent.

For comparison purposes, a commercially available white oil is used for the corrosion protection 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

Coating and test of the sheets:

With the described formulations or the white oil, test plates made of galvanized steel (10 cm × 15 cm) were coated with the described formulations 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.

"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 is about 25,000 salt grains / m ² (about 250 salt grains / dm ² ). The plates are then stored horizontally for 96 h in a climatic chamber at 20 ° C and 85% humidity, and the rust formation is photographically tracked. After storage, the sheets are rinsed and dried and evaluated photographically.

salt spray test

Furthermore, a standard salt-spatter test was carried out with the sheets for comparison purposes in accordance with DIN EN ISO 7253, ie the entire metal surface was uniformly exposed to a fine salt mist in a test chamber.

discussion of the results

In the salt spray tests, the phosphoric acid polyoxyalkylene esters used according to the invention, such as the alkylphosphoric acid esters used for comparison, gave an average, approximately equal corrosion protection effect.

On the other hand, the "black spot test" shows very clear differences between the sheet coated with alkylphosphoric acid esters or with a conventional corrosion protection oil and the phosphoric acid polyoxyalkylene esters used according to the invention.

illustration 1 shows the comparative experiment, in which a common white oil is used as a corrosion protection oil after 24 h test period. After 24 h, a clear number of "black spots" can be seen.

Figure 2 shows, however, a recording of the coated with the corrosion protection oil sheet according to the invention after 96 h experimental duration. Here, even after 96 h, only a few, relatively small "black spots" can be seen.

Figure 3 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.

The examples and comparative examples show the particular suitability of the phosphoric acid polyoxyalkylene esters used according to the invention for transport corrosion protection, in which "black spot corrosion" is the essential corrosion phenomenon. The known as corrosion inhibitors Alkylphosphorsäureester show little effect in this application.

Claims (14)

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

   (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,
   characterized in that the corrosion preventive oil comprises 20 to 100% by weight, based on the total amount of all of the components of the corrosion preventive oil, of at least one phosphoric ester (A) of the general formula
   
           [R²-(-O-CH(R¹)-CH₂-)_n-O-]_k-P(=O)-(OX)_3-k
   
   and where R¹, R², X, n, and k have the following definitions:

   k: 1 or 2,

   n: a number from 10 to 70,

   R¹: independently at each occurrence a radical selected from the group consisting of H, C₁ to C₁₀ alkyl radicals or aryl-substituted C₂ to C₁₀ alkyl radicals, with the proviso that for at least 50 mol % of the radicals R¹ is a methyl radical,

   R²: H or a C₁ to C₃₀ alkyl radical,

   X: H or a cation $\frac{1}{m}{Y}^{\mathrm{m}+},$

   

   where m is a natural number from 1 to 3.
2. The method according to claim 1, characterized in that the method subsequent to step (3) additionally at least comprises following step:

   (4) transporting the shaped articles produced in step (3) to a further fabrication site.
3. The method according to claim 1 or 2, characterized in that the method subsequent to step (4) additionally at least comprises following step:

   (5) joining the shaped articles to other shaped articles to form assembled shaped articles.
4. The method according to claim 1, characterized in that the shaped articles produced in step (3) are parts of automobile bodies.
5. The method according to claim 3, characterized in that the assembled shaped articles produced in step (5) are automobile bodies.
6. The method according to one of the claim 1 to 5, characterized in that in the course of step (3), the metal strip is first separated into individual sheets and cleaned and, prior to forming, a corrosion preventive oil of the stated composition is applied again in an amount of 0.25 to 5 g/m².
7. The method according to one of the claim 1 to 6, characterized in that the transport of step (2) and/or (4) is transport by truck or by rail.
8. The method according to one of the claim 1 to 7, characterized in that the corrosion preventive oil further comprises 20 to 80% by weight of at least one diluent (B).
9. The method according to claim 8, characterized in that the at least one diluent comprises R³-(-O-CH(CH₃)-CH₂)_m-O-R³, where the radicals R³ independently of one another are H or a C₁ to C₄ alkyl radical and m is a number from 2 to 20.
10. The method according to claim 8, characterized in that the at least one diluent comprises dipropylene glycol.
11. A shaped article made from a 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, characterized in that the corrosion preventive oil comprises 20 to 100% by weight, based on the total amount of all of the components of the corrosion preventive oil, of at least one phosphoric ester (A) of the general formula
    
            [R²-(-O-CH(R¹)-CH₂-)_n-O-]_k-P(=O)-(OX)_3-k
    
    and where R¹, R², X, n, and k have the following definitions:

    k: 1 or 2,

    n: a number from 10 to 70,

    R¹: independently at each occurrence a radical selected from the group consisting of H, C₁ to C₁₀ alkyl radicals or aryl-substituted C₂ to C₁₀ alkyl radicals, with the proviso that for at least 50 mol % of the radicals R¹ is a methyl radical,

    R²: H or a C₁ to C₃₀ alkyl radical,

    X: H or a cation $\frac{1}{m}{Y}^{\mathrm{m}+},$

    

    where m is a natural number from 1 to 3.
12. The shaped article according to claim 11, characterized in that the shaped article is a part of automobile bodies or is an automobile bodies.
13. Use of corrosion-prevention oil for corrosion protection in the course of storage and/or transport of shaped articles made from galvanized steel sheet, by applying to the shaped-article surface a corrosion-prevention oil in an amount of 0.25 to 5 g/m², characterized in that the corrosion preventive oil comprises 20 to 100% by weight, based on the total amount of all of the components of the corrosion preventive oil, of at least one phosphoric ester (A) of the general formula
    
            [R²-(-O-CH(R¹)-CH₂-)_n-O-]_k-P(=O)-(OX)_3-k
    
    and where R¹, R², X, n, and k have the following definitions:

    k: 1 or 2,

    n: a number from 10 to 70,

    R¹: independently at each occurrence a radical selected from the group consisting of H, C₁ to C₁₀ alkyl radicals or aryl-substituted C₂ to C₁₀ alkyl radicals, with the proviso that for at least 50 mol % of the radicals R¹ is a methyl radical,

    R²: H or a C₁ to C₃₀ alkyl radical,

    X: H or a cation $\frac{1}{m}{Y}^{\mathrm{m}+},$

    

    where m is a natural number from 1 to 3.
14. The method according to claim 13, characterized in that the shaped articles are automobile bodies.

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