EP2311928A2 - Aqueous solution containing an organic phosphoric acid ester for producing a metal sheet coated with lubricant with improved reforming characteristics - Google Patents

Abstract

Lubricant-coated sheet metal comprises a layer formed by applying a solution containing a phosphate ester onto the metal surface. Independent claims are also included for: (1) production of sheet metal as above by applying the solution to one or both sides of the sheet and applying a lubricant to the coated sheet; (2) aqueous solution for treating metal surfaces, comprising a phosphate ester and a water-soluble organosulfur compound and/or an organomolybdenum compound; (3) concentrate for preparing a solution as above.

Description

The invention relates to a lubricant-coated metal sheet or a blank thereof with improved Umformeigens̈chaften, wherein the lubricant is in particular a corrosion protection oil, Pre-Lube and / or Dry-Lube. The invention further relates to a method for producing such a metal sheet or sheet metal blank and their use for the production of metal bodies by forming, in particular by deep drawing.

In the manufacture of metal sheets, for. As steel sheets, it is customary to equip them immediately after the production and coating process and before delivery to the metalworking industry with a temporary corrosion protection for storage and transport. This is usually done by applying a corrosion-inhibiting lubricant immediately before winding the sheet, such as a corrosion protection oil, a pre-Lubes or a dry Lubes. If the metal sheet for further processing by forming such as deep drawing is determined, the lubricants used in addition to corrosion-inhibiting substances may contain other specially tailored to the particular forming process excipients improve the tribological properties of the sheet during the forming process. Such coated metal sheets are used for example in the automotive industry in the manufacture of bodies made of metal sheets by deep drawing.

When using lubricants for temporary corrosion protection and to improve the forming properties, it should be noted in particular that these can be easily and completely removed from the sheet after the forming process.

From the EP 0 489 105 B1 For example, a method of cold-forming metal sheets is known in which the deep-drawing sheet and / or the deep-drawing die are treated with an aqueous solution of an inorganic alkali phosphate and then deep-drawn in the presence of a deep-drawing oil. The salt deposited on the sheet, under the conditions of pressure and temperature of drawing by reaction with the thermoforming oil, forms a soap which causes a reduction in the coefficient of friction. A disadvantage of the method is that the alkali phosphate used and the soaps formed after deep drawing is not completely free from residue to remove from the sheet.

From the CH 441 594 Further, a lubricant composition for non-cutting cold working of metals is known, which contains a finely dispersed water-soluble inorganic salt such as borax to improve the tribological properties. A disadvantage of this lubricant composition is that its lubricity is not constant since The salt is not evenly distributed over the surface, which disturbs the deep drawing process.

In the production of one-sided electrolytically galvanized thin sheet, a thin-layer phosphating or borax passivation with a layer weight of about 10 mg / m ^{2 has been found to} be advantageous in terms of tribological properties. Both products can be applied in the existing rinsing baths of galvanizing lines. But they have the disadvantage that they can affect the phosphating in the automobile plant.

The idea of influencing the tribological properties of steel strip directly on the steel surface is taken into account through the use of Prelubes. Prelubes contain Ziehhilfsstoffe, which are introduced into the approximately 1 micron thick oil layer. However, only the direct steel tool interface in the range of a few nanometers is tribologically active.

Finally, it is generally known to perform a surface treatment of the deep-drawn sheet to improve the tribological properties. In particular, chemical processes for surface treatment, such as, for example, phosphorus sorting, are known, by means of which the friction coefficient of sheet metal / tool is reduced, and thus the shaping of the sheet metal blank is promoted. However, such treatment is expensive and can not be applied to all deep-drawn sheets.

1. a) ein oder mehrere Polyetherpolyole mit Molekulargewichten von 200 bis 100000, die erhalten wurden durch Addition von Alkylenoxiden an eine oder mehrere der Verbindungen, welche ausgewählt wurden aus
   1. (1) Polyalkylenpolyaminen und deren Derivaten
   2. (2) Alkyl und Alkylarylaminen und Derivaten derselben und
   3. (3) Carbonsäureamiden und Derivaten derselben; und
2. b) eine oder mehrere Verbindungen, ausgewählt aus Phosphorsäureverbindungen und Borsäure.

The invention was based on the object, a lubricant-coated metal sheet for the production of From the GB 2 142 540 A a water-soluble metalworking lubricant composition is known which has the following composition:

1. a) one or more polyether polyols having molecular weights from 200 to 100,000, obtained by addition of alkylene oxides to one or more of the compounds selected from
   1. (1) Polyalkylenepolyamines and their derivatives
   2. (2) alkyl and alkylarylamines and derivatives thereof and
   3. (3) carboxylic acid amides and derivatives thereof; and
2. b) one or more compounds selected from phosphoric acid compounds and boric acid.

This document relates to an application in the acidic pH range. The use in the acidic area is disadvantageous because it has a negative effect on safety at work and brings with it the risk of chemical burn of machine components.

To provide metal bodies by forming with improved tribological properties. The metal sheet should be easy to clean after the forming process and without leaving any residue. The production of the lubricant-coated metal sheet should finally be feasible easily and without high investment in existing manufacturing facilities.

This object is achieved by a metal sheet or a sheet metal blank with a coating of lubricant, in particular a corrosion protection oil, pre-lube and / or dry lube, wherein the metal sheet or sheet metal blank comprises a layer containing by applying an organic phosphoric acid ester Solution is formed on the metallic surface of the sheet.

Surprisingly, it has been found that the lubricant-coated metal sheets according to the invention have excellent tribological properties as a result of their layer formed by the phosphoric acid ester. Compared with lubricant-coated metal sheets without such a layer, the metal sheets according to the invention have a reduced coefficient of friction. Finally, the metal sheets according to the invention can easily be cleaned with existing degreasing systems after the forming process, wherein both the lubricant-containing and the layer formed by the phosphoric acid ester can be removed without residue from the surface of the sheet without any problems.

The metal sheets which can be used according to the invention may be any metal sheets from which metal bodies can be produced by deformation, in particular by cold forming. Particularly suitable metal sheets are steel sheets. The metal sheets which can be used according to the invention can be coated or uncoated. As an uncoated metal sheet, for example, uncoated sheet, in particular contigeglühtes uncoated sheet comes into question. As coated metal sheets are in particular electrolytically coated sheet, in particular electrolytically galvanized sheet, and hot-dip galvanized and galvanized sheets in question. The metal sheets preferably have a thickness of 0.05 to 5 mm, in particular from 0.5 to 1.5 mm.

The metal sheets and sheet metal blanks according to the invention are coated with a lubricant which is intended, at least temporarily, to protect the sheets from undesired environmental influences, in particular from corrosion phenomena, after production. The selection of the lubricant is not limited; Rather, any fat or oil-containing substances or the like as well as dry lubricant such as graphite come into question. The inventively employable lubricants preferably contain corrosion inhibitors. In addition, the lubricant may contain other additives, in particular additives to improve the drawing properties of the sheets.

Such lubricants for the metalworking industry are well known in the art and, for example, in Nachtmann "Lubricants and lubrication in metalworking operations ", Marcel Decker, New York, 1985, pages 81-105 ; Byer's "Metalworking Fluids", Marcel Decker, New York, 1994, pages 136-140 and Mortier, Orslick "Chemistry and Technology of Lubricants", 2nd Ed., Chapman & Hall, London, 1997, pp. 253-260 described.

According to a preferred embodiment of the invention, a corrosion protection oil is used as the lubricant. Such corrosion protection oils are well known to the skilled person and usually contain a base oil having an aromatic content <10% and a corrosion inhibitor such. B. calcium sulfonates. In addition, the corrosion protection oils may contain antioxidants to prevent oil aging and Thixotropiebildner to reduce dripping losses in oiled metal sheets.

According to a further preferred embodiment of the invention, a so-called pre-lube is used as the lubricant. Pre-lubes are corrosion protection oils with improved drawing properties and as such are well known to those skilled in the art. The improvement of the drawing properties is achieved by adding further additives, eg. As esters, achieved.

According to a further preferred embodiment of the invention, a so-called dry lubricant is used as the lubricant. Dry lubricants are wax and / or acrylate based thin films with similar properties to pre-lubes and as such are well known to those skilled in the art. In addition, dry lubricants offer the possibility of producing difficult drawn parts in the press shop without any additional lubrication. drip loss coated sheets are completely avoided. Dry Lubricants can be applied after melting, for example, electrostatically or by means of a roller coater.

According to the invention, a layer is formed on the metallic surface of the sheet, which is obtainable by applying an organic phosphoric acid ester on the metallic surface of the sheet.

Organic phosphoric esters which can be used according to the invention are, in particular, compounds of the general formula

X _3-n PO ₄ R _n ,

wherein X is hydrogen, Na, K, -NH ₂ , -NHR, -NR ₂ , -NH (R'-OH), -N (R'-OH) ₂ or -NR (R'-OH), R is for a straight-chain or branched alkyl group having 1 to 14, in particular 1 to 8 carbon atoms, R 'represents a straight-chain or branched alkylene group having 1 to 14, in particular 1 to 8 carbon atoms, wherein one or more hydrogen atoms in R and R' by a polymeric or in which Y is (CH ₂ -CH ₂ -O-) _m or (CH ₂ -CH (CH ₃ ) -O-) _m where m = 1 to ∞ and in particular m = 1 to 10 each R and R 'may be the same or different and n is a number from 0 to 3, with the proviso that n is not 0 when X is hydrogen only.

Particularly good results are achieved if, as the organic phosphoric acid ester, a compound of the abovementioned formula with X =H, R =C ₄ H ₉ and n = 1 or 2 is used. Also particularly preferred is an equimolar mixture of (C ₄ H ₉ -O) PO (OH) ₂ and (OH) PO (OC ₄ H ₉ ) ₂ .

According to a preferred embodiment of the invention, the layer formed by phosphoric acid ester contains, as further component, a water-soluble organic sulfur compound and / or an organic molybdenum compound.

Particularly suitable organic sulfur compounds according to the invention are thiadiazoles, dithiocarbamates and / or dithiopropionates and their salts and derivatives.

Particularly suitable organic sulfur compounds are, for example, sodium 2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4-thiadiazole and salts and derivatives thereof, sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate and / or monoethanolamine dithiopropionate.

Suitable organic molybdenum compounds according to the invention are obtainable, for example, by reacting molybdenum trioxide and / or molybdic acid with an amine and / or alkanolamine.

According to a further preferred embodiment of the invention, the layer containing phosphoric ester contains as further component at least one inorganic compound selected from the group consisting of polyphosphates, borates, molybdates and tungstates.

Particularly suitable inorganic compounds according to the invention are, for example, ammonium tripolyphosphate, sodium tetraborate, ammonium molybdate, sodium tungstate, potassium tungstate and / or sodium tungstate.

Preferably, the organic phosphoric acid ester and any other components in the form of an aqueous solution are applied to the metal sheet. After application, the metal sheet is preferably dried.

The layer formed by phosphoric acid ester may be formed in any thicknesses. However, this is preferably formed as a very thin layer, in particular as a line in the nanometer range.

According to a further preferred embodiment of the invention, a lubricant-containing layer is formed directly on the layer formed by phosphoric acid ester. The lubricant-containing layer preferably contains a corrosion protection oil, pre-lube and / or dry lube. Preferably, the lubricant-containing layer contains a corrosion protection oil.

The lubricant-containing layer may be formed in any thicknesses. Particularly good tribological properties can be achieved if the lubricant-containing layer in a thickness of 0.3 to 3.0 g / m ² , in particular 1 to 2 g / m ² is formed.

It has proved to be particularly advantageous if the lubricant-containing layer is matched to the layer containing phosphoric acid ester, as containing components which are also contained in the layer containing phosphoric acid ester.

It has been found that a synergistic effect occurs by this measure and the tribological properties of the sheet are further improved.

Thus, it is advantageous if the lubricant-containing layer contains at least one organic phosphoric acid ester as defined above in an amount of from 0.01 to 50% by weight, in particular from 0.05 to 10% by weight.

Further, it is preferable that the lubricant-containing layer comprises a water-soluble organic sulfur compound as defined above in an amount of 0.005 to 50% by weight, especially 0.01 to 30% by weight, and / or an organic molybdenum compound as defined above in an amount from 0.005 to 50 wt.%, In particular 0.01 to 30 wt.% Contains.

Finally, it is advantageous if the lubricant contains an inorganic compound as defined above in an amount of 0.005 to 50% by weight, in particular 0.01 to 30% by weight.

• Aufbringen einer Lösung enthaltend einen organischen Phosphorsäureester auf die Ober- und/oder Unterseite des Blechs und
• Aufbringen eines Schmierstoffs auf das so beschichtete Blech.

The invention further relates to a method for producing the metal sheet or sheet metal blank according to the invention, comprising the following steps:

• Application of a solution containing an organic phosphoric acid ester on the top and / or bottom of the sheet and
• Applying a lubricant to the thus coated sheet.

The application of the solution containing the organic phosphoric acid ester can be carried out by any known to the expert measures such as dipping, spraying, brushing or doctoring.

The operation can be conveniently integrated into the existing work processes in the manufacture of metal sheets. Thus, the application of the solution containing phosphoric acid can be carried out, for example, in the coating of the sheet in the rinsing bath of a coating plant or in the cooling of the sheet in the bath of a water cooling plant. The application of the solution containing phosphoric acid ester is preferably carried out in the rinsing bath of a coating installation. The rinsing bath is preferably downstream of the metallic coating process (eg electrolytic galvanizing) as a one-stage no-rinse aftertreatment. Within a production plant, the rinsing bath can be followed by further production steps. In particular, the metal sheet may be dried after the rinsing bath in a suitable dryer and / or subsequently coated with a lubricant (eg by electrostatic lubrication).

The phosphoric acid ester-containing solution is preferably applied as an aqueous solution.

The solution preferably contains the organic phosphoric acid ester in an amount of 0.1 to 15% by weight, in particular 3 to 8% by weight.

The pH of the solution is preferably adjusted to a value of 6.5 to 11, in particular 7.5 to 9.5.

According to a preferred embodiment of the invention, the solution contains as another component as described above a water-soluble organic sulfur compound, in particular one of the compounds described above, and / or an organic molybdenum compound, in particular one of the compounds described above, and / or one of the inorganic compounds described above contains.

The water-soluble organic sulfur compound (s) and / or organic molybdenum compound (s) are preferably contained in the solution in an amount of 1 to 50% by weight, more preferably 5 to 25% by weight on the amount of phosphoric acid ester.

The inorganic compound (s) are contained in the solution in an amount of 1 to 50% by weight, especially 5 to 10% by weight, based on the amount of phosphoric acid ester.

Before applying the lubricant, it is advantageous to dry the sheet.

The lubricant used is preferably a corrosion protection oil, pre-lube and / or dry lube as described above. Preferably, the lubricant In terms of its composition so far matched to the phosphoric acid ester-containing solution than that as described above contains components (eg., Organic phosphoric acid ester, water-soluble organic sulfur compound, organic molybdenum compound and / or inorganic compound), which are also included in the solution containing phosphoric acid ester.

The lubricant is preferably applied in an amount of 0.3 to 3 g / m ² , in particular 1 to 2 g / m ² .

The invention accordingly also comprises the use of a solution containing an organic phosphoric acid ester as described above for the treatment of metal surfaces.

The invention further provides an aqueous solution for treating metal surfaces comprising an organic phosphoric acid ester and a water-soluble organic sulfur compound and / or an organic molybdenum compound, all compounds as described above, and a concentrate for producing such a solution.

Finally, the use of the metal sheet or sheet metal blank according to the invention for the production of metal bodies by forming, in particular by deep drawing.

The invention will be described in more detail with reference to an embodiment.

Electrolytically galvanized steel sheets of 1 mm thickness were treated by dipping with an aqueous solution of the composition shown below, dried, and then coated with 1.5 g / m ² Pre-Lube. To determine the drawing power, the coefficient of friction was then determined in the draw-bed test. The reference for the coefficient of friction was a sample of the electrolytically galvanized steel sheet, which was not treated with an aqueous solution. The coefficient of friction of this reference sample was set at 100%.

example 1

An electrolytically galvanized steel sheet was treated with a 5% solution of an equimolar phosphoric ester mixture of (CH ₃ -O) PO (OH) ₂ and (OH) PO (O-CH ₃ ) ₂ . The sheet was dried and then coated with 1.5 g / m ² Pre-Lube. The coefficient of friction was 88%.

Compared with the reference sample without pretreatment, a reduction of the friction coefficient by 12% was found.

Example 2

An electrolytically galvanized steel sheet was treated with a 5% solution of an equimolar phosphoric ester mixture of (C ₄ H ₉ -O) PO (OH) ₂ and (OH) PO (OC ₄ H ₉ ) _2. The sheet was dried and then washed with 1.5 g / m ² pre-lube coated. The coefficient of friction was 58%.

Compared with the reference sample without pretreatment, a reduction of the friction coefficient by 42% was found.

Example 3

An electrolytically galvanized steel sheet was treated with a 5% solution of an equimolar phosphoric acid ester mixture of (C ₈ H ₁₇ -O) PO (OH) ₂ and (OH) PO (OC ₈ H ₁₇ ) ₂ . The sheet was dried and then coated with 1.5 g / m ² Pre-Lube. The friction coefficient was 90%.

Compared to the reference sample without pretreatment, a reduction in the coefficient of friction by 10% was found.

Example 4

An electrolytically galvanized steel sheet was treated with a 5% solution of an equimolar phosphoric acid ester mixture of (CH ₃ - [O-CH ₂ CH ₂ ] ₃ -C ₁₂ H ₂₄ -O) PO (OH) ₂ and (HO) PO (CH ₃ - [O-CH ₂ CH ₂ ] ₃ -C ₁₂ H ₂₄ -O) ₂ . The sheet was dried and then coated with 1.5 g / m ² Pre-Lube. The friction coefficient was 92%.

Compared with the reference sample without pretreatment, a reduction of the friction coefficient by 8% was found.

Example 5

In this example, the thermoforming working range of an electrolytically galvanized sheet according to the invention produced according to Example 2 was compared with the reference sample without pretreatment. The results of this study are in Fig. 1 shown.

The results show that the thin sheet coated according to the invention ( Fig. 1b ) has a significantly larger thermoforming working range than the reference sample without pretreatment ( Fig. 1a ).

Comparative Example 1

An electrolytically galvanized steel sheet was treated with a 5% sodium tetraborate solution, dried and then coated with 1.5 g / m ² Pre-Lube. The friction coefficient was 90%.

Compared to the reference sample without pretreatment, a reduction in the coefficient of friction by 10% was found.

Comparative Example 2

An electrolytically galvanized steel sheet was treated with a 5% phosphoric acid solution, dried and then coated with 1.5 g / m ^{2 of} Pre-Lube. The friction coefficient was 95%.

Compared with the reference sample without pretreatment, a reduction of the friction coefficient by 5% was found.

The results show that the metal sheets according to the invention which have been treated with a solution of phosphoric acid ester have significantly improved tribological properties as well as an increased deep drawing working range compared to metal sheets which have not been subjected to such a treatment. The Metal sheets according to the invention were also easy to clean and completely residue-free in a conventional degreasing system.

Claims (15)

Aqueous solution having a pH of 6.5 to 11 for the treatment of metal surfaces containing an organic phosphoric acid ester of the general formula

X _3-n PO ₄ R _n ,

wherein X is hydrogen, Na, K, -NH ₂ , -NHR, -NR ₂ , NH (R'-OH), -N (R'-OH) ₂ or -NR (R'-OH), R for a straight or branched chain alkyl group having 1 to 14 carbon atoms, R 'represents a straight-chain or branched alkylene group having 1 to 14 carbon atoms, R and R' may be the same or different and n is a number from 0 to 3, with the proviso that n is not 0 when X is hydrogen alone, and a water-soluble organic sulfur compound and / or an organic molybdenum compound. Aqueous solution according to claim 1, characterized in that R is a straight-chain or branched alkyl group having 1 to 8 carbon atoms and / or R 'is a straight-chain or branched alkylene group having 1 to 8 carbon atoms. Aqueous solution according to claim 1 or 2, characterized in that as organic phosphoric acid ester a compound of the formula mentioned in claim 1 with X = H, R = C ₄ H ₉ and n = 1 or 2 is used. Aqueous solution according to one of the preceding claims, characterized in that the organic phosphoric acid ester is a mixture of (C ₄ H ₉ -O) PO (OH) ₂ and (OH) PO (OC ₄ H ₉ ) ₂ . Aqueous solution according to one of the preceding claims, characterized in that the organic phosphoric acid ester is contained in an amount of 0.1 to 15% by weight in the solution. Aqueous solution according to claim 5, characterized in that the organic phosphoric acid ester in an amount of 3 to 8 wt.% Is contained in the solution. Aqueous solution according to one of the preceding claims, characterized in that the pH of the solution is 7.5 to 9.5. Aqueous solution according to one of the preceding claims, characterized in that the water-soluble organic sulfur compound, and / or organic molybdenum compound contained in the solution in an amount of 5 to 25 wt.% Based on the amount of phosphoric acid ester. Aqueous solution according to one of the preceding claims, characterized in that the organic sulfur compound is selected from the group consisting of thiadiazoles, dithiocarbamates and dithiopropionates and salts and derivatives thereof. Aqueous solution according to any one of the preceding claims, characterized in that the organic sulfur compound is selected from the group consisting of sodium 2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4-thiadiazole and salts and derivatives thereof, Natriumdimethyldithiocarbamat, Kaliumdimethyldithiocarbamat and monoethanolamine dithiopropionate. Aqueous solution according to one of the preceding claims, characterized in that the organic molybdenum compound is obtainable by reacting molybdenum trioxide and / or molybdic acid with an amine and / or alkanolamine. Aqueous solution according to one of the preceding claims, characterized in that it contains as further component at least one inorganic compound selected from the group consisting of polyphosphates, borates, Molybdaten and tungstates. An aqueous solution according to claim 12, characterized in that the inorganic compound is selected from the group consisting of ammonium tripolyphosphate, sodium tetraborate, ammonium molybdate, sodium tungstate, potassium tungstate and sodium tungstate. Concentrate for preparing a solution for the treatment of metal surfaces according to one or more of claims 1 to 13. Use of an aqueous solution according to any one of claims 1 to 13 for the treatment of metal surfaces.

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