EP1670972A1

EP1670972A1 - Method for pickling metallic surfaces by using alkoxylated alkynols

Info

Publication number: EP1670972A1
Application number: EP04765569A
Authority: EP
Inventors: Frank Dietsche; Thomas Heidenfelder; Helmut Witteler
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2003-09-30
Filing date: 2004-09-24
Publication date: 2006-06-21
Also published as: CA2539246A1; KR20060090817A; WO2005033364A1; MXPA06002924A; BRPI0414711A; JP2007507607A; US20070034606A1

Abstract

Disclosed is a method for pickling metallic surfaces by treating the metallic surface with a composition comprising water, at least one acid, an alkyne alkoxylate, and other optional additives. In a preferred embodiment, the alkyne alkoxylate is used along with a complexing agent.

Description

Process for pickling metallic surfaces using alkoxylated alkynols

description

The present application relates to a method for pickling metallic surfaces by treating the metallic surface with a composition which comprises water, at least one acid, an alkali alkoxylate and optionally further additives. In a preferred embodiment, the alkali alkoxylate is used together with a complexing agent.

In the case of pickling, the surface of a material is treated with a pickle and thereby changed chemically. Unwanted surface layers are removed and protective or effect layers are built up if necessary. In the case of metallic surfaces, pickling primarily serves to remove various oxide layers, such as rust or scale layers, and / or other contaminants, such as greases, oils or lime, from the surface and / or to activate and / or protect the surface. An example of a protective treatment is acid phosphating of an iron or steel surface. An essential element here is a pickling attack on the metal. In the case of phosphating with an acidic Zn-phosphate solution, a large amount of H ⁺ ions are consumed by the acid attacking the metal directly on the metal surface, as a result of which the pH increases locally. Only then is the solubility product for zinc phosphate exceeded, so that zinc phosphate is deposited on the surface in a thin layer.

For ^' pickling, aqueous, inorganic or organic acids, in particular hydrochloric acid, phosphoric acid or sulfuric acid, and generally auxiliaries such as surfactants are used. Although the acid should attack the surface layers and possibly also the metal itself, it is generally undesirable if too large amounts of metal are dissolved. On the one hand, a lot of pickling acid is consumed and the pickling contaminated with dissolved metal ions. Accordingly, the pickling bath has to be renewed frequently. On the other hand, the surface - especially with iron or nickel - can also be damaged by so-called hydrogen embrittlement. Preparations for pickling are therefore usually added to pickling inhibitors which are intended to prevent the dissolving of the base material or at least to slow it down considerably without significantly impeding the dissolution of the surface layers. Pickling using inhibitors is also sometimes called "saving pickling".

It is known to use alkynols such as 2-butyne-1,4-diol, 1-propyn-3-ol or 1-ethynyl-cyclohexanol as pickling inhibitors. Examples include US 3,658,720, US 3,969,260 or JP-A 60-208 ^* 487. WO 99/32687 discloses the use of 2-butyne-1,4-diol as an inhibitor in the acid phosphating of one-sided galvanized steel strip.

Special care must be taken when handling alkinols. 2-butyn-1, 4-diol and 1-propyn-3-ol are classified as toxic and carcinogenic.

Alkaline alkoxylates are known in principle, for example from DE-A 2241 155. They are used, inter alia, as gloss additives in the electrodeposition of nickel or cobalt, as disclosed by US 3,804,727, 3,814,674 or US 4,832,802. Alkoxylated alkynols are not classified as toxic or carcinogenic.

US 3,004,925 discloses the use of ethoxylated butynediol derivatives and ethoxylated propinol derivatives as a corrosion inhibitor in aqueous solutions. The OH groups are each modified with - (CH ₂ -CH ₂ O) _x groups, where x has the value from 3 ^" to 25. Furthermore, the alkynols disclosed additionally have one or more alkyl, aryl, cycloalkyl and Aralkyl groups Unsubstituted butynediol or propargyl alcohol is not disclosed.

No. 5,215,675 discloses compositions for removing lacquers from surfaces which have 10 to 50% water, 3 to 15% of a peroxide and 40 to 70% ethyl lactate. The composition can also optionally have ethoxylated butynediol as a corrosion inhibitor and an acid. In a further embodiment, a composition is disclosed which comprises 55 to 60% butyrolactone, 30 to 32% aqueous hydrogen peroxide, 9.5% formic acid, 1% ethoxylated butanediol, 0.5% Na EDTA and 4% surfactants.

The object of the present invention was to provide a method for pickling metallic surfaces in which butynediol or propinol are replaced by suitable substitutes, and in which a better pickling inhibition is nevertheless achieved. Accordingly, a process has been found for pickling metallic surfaces, in which the metallic surface is treated with an acidic aqueous preparation which comprises at least the following components:

(a) 60 to 99.99% by weight of a mixture of water and at least one acid,

(b) 0.01 to 2% by weight of at least one alkyne alkoxylate of the general formula

HC ≡C-CH ₂ -O (-CH ₂ -CHR ¹ -O-) _n H or H (-O-CHR ¹ -CH ₂ -) _n -O-CH ₂ -CsC-CH ₂ -O (-CH ₂ -CHR ¹ -O-) _n .H, where the radicals R ¹ each independently represent H or methyl and the indices n and n 'independently of one another are 1 to 10, and

(c) 0 to 38% by weight of one or more additives and / or auxiliaries.

In a preferred embodiment, the pickling inhibitor is used in combination with a water-soluble complexing agent.

The following is to be explained in detail regarding the invention:

The method according to the invention can in principle be used for pickling various types of metallic surfaces. The metals can be pure metals as well as alloys. Examples include surfaces made of iron, cast iron, steel, nickel, zinc, brass or aluminum, in each case meaning the uppermost metal layer which comes into direct contact with the preparation. The metallic surface can also be, for example, surface-tempered steels, such as hot or galvanized steels. The method is particularly suitable for pickling surfaces made of (cast) iron, steel or aluminum, very particularly preferably for steel surfaces. The method is particularly suitable for pickling the surface of strip metals, such as steel or aluminum strips.

The metallic surfaces can be both external surfaces of metallic materials, such as the surface of metallic strips, metal sheets or irregularly shaped workpieces such as machine parts. But it can also be internal surfaces, such as the inner surfaces of pipelines, boilers, chemical plants or the like.

In the method of pickling according to the invention, undesired surface layers and impurities are removed and, if appropriate, protective and / or effect layers are built up. The term “pickling” includes the phosphating of metallic surfaces. Unwanted surface layers can in particular be inorganic layers, for example largely oxidic layers such as rust layers, scale layers or layers which are formed when metals, for example steel, are rolled. It can also be used for temporary corrosion protection, such as phosphate layers or layers of other materials, such as carbonate layers such as lime layers or patina layers, and unwanted layers can also be thin layers of organic materials such as fat or oil layers , The preparation used for the process according to the invention comprises, as component (a), water and at least one acid in a total amount of from 60 to 99.99% by weight. The percentages here and below always refer to the amount of all components of the preparation.

The total amount of water and acid is preferably 70 to 99.99% by weight and very particularly preferably 80 to 99.99% by weight.

The acid can be an inorganic acid such as, for example, hydrochloric acid, hypo- and chlorous acid, sulfuric acid, phosphoric acid or phosphorous acid or else an organic acid such as, for example, formic acid, methanesulfonic acid, acetic acid, citric acid, succinic acid or amidosulfonic acid. Mixtures of different acids can of course also be used, for example mixtures of hydrochloric acid and phosphoric acid. The acid is preferably hydrochloric acid, sulfuric acid, methanesulfonic acid or phosphoric acid.

The amount of water and acid depends on the one hand on the intended use of the preparation and also on the type of acid. While in special cases the solvent can only consist of concentrated (i.e. 85%) phosphoric acid when using phosphoric acid, higher dilutions are advantageous when using acids other than phosphoric acids. If acids other than phosphoric acid are used, the preparation generally comprises at least 50% by weight of water, preferably at least 60% by weight of water. The total amount of water in the preparation is calculated as the sum of the water which is added together with the acid and from which is added in pure form or in the form of solutions of other materials.

Component (b) in the preparation used for the process according to the invention is 0.01 to 2% by weight of at least one alkali alkoxylate of the general formula

HC≡C-CH ₂ -0 (-CH ₂ -CHR ¹ -O-) _n H (I)

or

H (-O-CHR ¹ -CH ₂ -) _n -0-CH ₂ -C ^ -CH ₂ -O (-CH ₂ -CHR ¹ -O-) _n Η (II).

The indices n and n 'independently of one another are from 1 to 10. It is known to the person skilled in the art that such alkoxy groups can be obtained in particular by oxalkylation or starting from technical polyglycols. The values mentioned stand for n thus for average chain lengths, whereby the average value does not of course have to be a natural number, but can also be any rational number. It is preferably n and n 'and a number from 1 to 3.

The radicals R ¹ in (I) and (II) each independently represent H or methyl. The alkyleneoxy groups can be groups derived exclusively from ethylene oxide units or groups derived exclusively from propylene oxide. Of course, however, these can also be groups which have both ethylene oxide units and propylene oxide units.

They are preferably polyoxypropylene units

Mixtures of (I) and (II) and / or mixtures of different compounds (I) or different compounds (II) can of course also be used. Compound (I) is preferably used.

0.05 to 2% by weight of (I) and / or (II) are preferably used, and particularly preferably 0.075 to 1.5% by weight and particularly preferably 0.1 to 1.0% by weight. All concentration data refer to the ready-to-use composition. It is of course possible to first produce a concentrate which is only diluted to the desired concentration on site.

The amount of (I) and / or (II) also depends on the type and amount of acid used and the temperature at which the preparation is to be used. The higher the acid concentration, the higher the concentration of pickling inhibitor (I) and / or (II) used should generally be. The higher the temperature, the higher the concentration of the pickling inhibitor should normally be. The amounts specified below have proven particularly useful for use at room temperature:

The compounds used can be obtained in a known manner by oxalkylation of butynediol or propargyl alcohol, as described, for example, in DE-A 2241 155 or US Pat. No. 3,814,674. The preparation used for the method generally also comprises one or more additives or auxiliary substances, even if their addition is not absolutely imperative in every case.

The amount of such additives is 0 to 38% by weight, preferably 0.01 to 30% by weight and particularly preferably 0.1 to 20% by weight.

Auxiliaries are in particular 0.01% by weight to 20% by weight of at least one surface-active substance. 0.1 to 10% by weight and particularly preferably 0.5 to 8% by weight of the surface-active substance are preferably used. Examples of suitable surface-active substances include conventional anionic, cationic or nonionic surfactants.

The following are particularly suitable as nonionic surfactants:

^{* "*} Alkoxylated C ₈ -C ₂₂ alcohols, such as fatty alcohol alkoxylates, oxo alcohol alkoxylates and Guerbet alcohol ethoxylates: The alkoxylation can be carried out using ethylene oxide, propylene oxide and / or butylene oxide. Block copolymers or statistical copolymers can be present. They usually contain 2 to 1 mol of alcohol 50 mol, preferably 3 to 20 mol, of at least one alkylene oxide. Preferred alkylene oxide is ethylene oxide. The alcohols preferably have 10 to 18 carbon atoms.

Alkylphenol alkoxylates, especially alkylphenol ethoxylates, which contain C ₆ -C ₁₄ alkyl chains and 5 to 30 mol alkylene oxide / mol.

Alkyl polyglucosides containing C ₈ -C ₂₂ , preferably C ₁₀ -C ₁₈ alkyl chains and generally 1 to 20, preferably 1, 1 to 5, glucoside units.

^* - ^* . N-alkyl glucamides, fatty acid amide alkoxylates, fatty acid alkanolamide alkoxylates and block copolymers of ethylene oxide, propylene oxide and / or butylene oxide.

Suitable anionic surfactants are, for example:

Sulfate atoms of (fatty) alcohols having from 8 to 22, preferably 10 to 18, carbon, in particular CgC n-alcohol sulfates, C ₁₂ C ₁₄ alcohol sulphates, C ₁₂ -C ₁₈ - Alkohoi-sulfate, lauryl sulfate, cetyl sulfate, myristyl sulfate, Palmityl sulfate, stearyl sulfate and tallow fatty alcohol sulfate.

Sulfated alkoxylated C ₈ -C ₂₂ alcohols (alkyl ether sulfates): Compounds of this type are prepared, for example, by first alkoxylating a C ₈ -C ₂₂ , preferably a C ₁₀ -C ₁₈ alcohol, for example a fatty alcohol, and that Alk-oxylation product then sulfated. Ethylene oxide is preferably used for the alkoxylation.

Linear C ₈ -C ₂₀ alkylbenzenesulfonates (LAS), preferably linear C ₉ -C ₁₃ alkylbenzenesulfonates and alkyltoluenesulfonates.

Alkane sulfonates, in particular C ₈ -C ₂₄ -, preferably C ₀ -C ₁₈ alkane sulfonates.

Soaps, such as the Na and K salts of C ₈ -C ₂₄ carboxylic acids.

The anionic surfactants are preferably added in the form of salts. Suitable cations are e.g. Alkali metal ions such as sodium, potassium and lithium, and ammonium salts such as hydroxyethylammonium, di (hydroxyethyl) ammonium and tri (hydroxyethyl) ammonium salts.

The following may be mentioned as particularly suitable cationic surfactants:

C ₇ -C ₂₅ alkylamines;

^~ N, N-dimethyl-N- (hydroxy-C ₇ -C ₂₅ alkyl) ammonium salts; mono- and di- (C ₇ -C ₂₅ -alkyl) dimethylammonium compounds quaternized with alkylating agents;

^~ Ester quats, especially quaternary esterified mono-, di- and tjalkanolamines which are esterified with C ₈ -C ₂₂ -carboxylic acids;

Imidazoline quats, in particular 1-alkylimidazolinium salts of the formulas III or IV

in ιv in which the variables have the following meaning:

R ² C Cse alkyl or C ₂ -C ₂₅ alkenyl; R ³ CC ₄ alkyl or hydroxy-C C alkyl; R ⁴ CC ₄ alkyl, hydroxy-dC ₄ alkyl or a radical R ⁴ - (CO) -X- (CH ₂ ) _p - (X: -O- or -NH-; p: 2 or 3), where at least one R ^{2 is} C ₇ -C ₂₂ alkyl.

Of course, several different surfactants can also be used. The person skilled in the art makes a suitable selection from the surface-active substances depending on the desired application. Recipe suggestions can be found in the relevant literature, for example the Technical Information from BASF AG "Technical Cleaning Agents", January 1993 edition.

Nonionic surfactants are preferably used.

The preparation used particularly preferably comprises one or more water-soluble complexing agents as further components. The complexing agents work synergistically with the pickling inhibitor. It has been found that complexing agents as an additive to pickling acids accelerate the removal of metal. However, if they are used in combination with the alkoxylated alkinols used as pickling inhibitors according to the invention, the inhibiting effect of the pickling inhibitor is not reduced by the complexing agent, but on the contrary is even increased. In experiments, the inhibitory effect could be improved by up to 60% by adding a complexing agent.

The complexing agent is a water-soluble, at least bidentate ligand, which is able to form chelate complexes. The ligand comprises acidic groups, preferably COOH groups. As a rule, the complexing agent has at least two COOH groups. It is preferably a two- to six-toothed ligand, particularly preferably a two- to four-toothed ligand. It is known to the person skilled in the art that the coordinating groups are arranged in a chelating ligand in such a way that the ligand can form one or more rings together with the metal, in particular five-membered rings.

The ligand can also have other atoms or groups which are capable of forming coordinative bonds to metal ions. OH groups and nitrogen-containing groups such as primary, secondary and tertiary amino groups should be mentioned here in particular. Tertiary amino groups are preferred.

Complexing agents preferred for carrying out this invention are ligands which are derived from compounds having primary amino groups and in which the H atoms on the amino group are substituted by -CH ₂ -COOH groups. Examples include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid. acid (NTA) or methylglycinediacetic acid (MGDA). Ethylene diamine tetraacetic acid and methyl glycinediacetic acid are preferably used to carry out the present invention, and methyl glycinediacetic acid is very particularly preferred. The complexing agents can be used in the form of acids or in the form of salts.

The complexing agents can also be polymeric complexing agents. Suitable polymeric complexing agents are in particular those which are derived from polymers which have primary and / or secondary amino groups and in which the H atoms on the amino groups are wholly or partly substituted by —CH ₂ —COOH groups. Preferred polymer complexing agents are polyethyleneimines modified with -CH ₂ -COOH groups. As a rule, at least 50%, preferably at least 60% and particularly preferably at least 75% of the H atoms on the amino groups should be substituted. The preparation of such polymeric complexing agents is described in WO 2004/001099.

The person skilled in the field of water-soluble complexing agents is aware that the solubility of complexing agents containing COOH groups in water can depend on the pH. The pH value desired for the respective application should therefore be chosen as the reference point. A complexing agent which has insufficient solubility for the intended use at a certain pH can have sufficient solubility at a different pH.

If present, the complexing agent is generally used in an amount of from 0..01 to 10% by weight. Preferably 0.1 to 10% by weight and particularly preferably 0.1 to 5% by weight are used

The weight ratio of complexing agent to pickling inhibitor is generally 100: 1 to 1: 100, preferably 50: 1 to 1:50 and particularly preferably 5: 1 to 1:10. Depending on the acid concentration, the following quantities have proven particularly useful for use at room temperature:

The pH of the composition is determined by the person skilled in the art depending on the desired

Application intended. It can be adjusted by the type and amount of the acid as well as any other components depending on the desired application. the. Suitable buffer systems, for example phosphate buffers or citrate buffers, can also be used to stabilize the pH. As a rule, the pH is 0 to less than 7, preferably 6.5 to 2 and particularly preferably 3 to 6.

A preparation which is particularly preferred for carrying out the method according to the invention is:

(a) 60 to 99.97% by weight of a mixture of water and at least one acid,

(b) 0.01 to 2% by weight of at least one of said alkali metal alkoxylates,

(c) 0.01 to 20% by weight of at least one surface-active substance, and (d) 0.01 to 10% by weight of at least one of said chelating complexing agents.

The amounts are very particularly preferably: (a) 70 to 98.9% by weight, (b) 0.1 to 2% by weight, (c) 0.5 to 15% by weight, and (d) 0.5 up to 10% by weight.

In a further preferred embodiment of the invention, the pickling inhibitors used according to the invention are used together with water-soluble cationic, nitrogen-containing polymers (V) which contain quaternized ammonium groups

have, wherein R ⁵ or R ^{5 'are the} same or different and represent a saturated or unsaturated, substituted or unsubstituted aliphatic radical, a saturated or unsaturated, substituted or unsubstituted alicyclic radical or a substituted or unsubstituted araliphatic radical. The groups A connecting the ammonium groups are hydrocarbon groups, in particular alkylene groups, into which further functional groups and / or heteroatoms can also be incorporated. For example, non-adjacent groups can be replaced by -O atoms or N atoms. Suitable functional groups are in particular urea groups -NC-CO-NH-. X is chosen by the person skilled in the art depending on the desired properties. Particularly suitable polymers usually have a molecular weight of 1000-100000 g / mol, preferably 1500-50000 g / mol and particularly preferably 2000-20000 g / mol.

The cationic polymers V are preferably one which has two different connecting groups A 'and A ".

As shown, the residues A 'or A "» can preferably be arranged alternately, but in principle they can also occur in the polymer in any sequence and number.

Group A 'is a group which has alkylene units and urea units:

. (CH ₂ ) _k _ N. -N (CH ₂ ), (A ') R ^D

k and k 'independently of one another represent a natural number from 1 to 5, preferably 2 or 3. R ⁶ and R ^6' independently of one another represent H or a straight-chain or branched aikyl radical having 1 to 12 C atoms. R ⁶ or R ^{6 '} are preferably selected from the group of H, -CH ₃ or -C ₂ H ₅ , particularly preferably R ⁶ or R ^6' is H.

The group A "is a straight-chain or branched alkylene group with 2 - 20 C atoms. The group can be substituted by groups such as -OH or = O. Furthermore, non-adjacent, non-terminal C atoms can also be substituted by one or a plurality of identical or different heteroatoms such as O, S and / or N. O-substituted radicals are preferred.

A "is preferably a radical of the general formula

-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) r,

where I stands for a natural number from 1 to 3. A "is particularly preferably -CH ₂ CH ₂ -O-CH ₂ -CH ₂ -.

Such cationic polymers, their production and properties are known in principle, in particular as a cosmetic agent for hair. For example, reference is made to DE-A 25 21 960 or DE-A 2 924 230. It is particularly preferably a polymer of the general formula VI:

The cationic polymers are preferably used in the same amounts as the complexing agents. Of course, both complexing agents and cationic polymers can also be used together with the pickling inhibitor.

Depending on the intended use, the preparation used can also comprise further components or auxiliaries.

In order to improve the removal of fats during pickling degreasing, it may be advantageous to add small amounts of water-miscible organic solvents to the composition. The amount of optionally added organic solvents is usually 0 to 10% by weight. Examples of suitable, water-miscible solvents include monoalcohols such as methanol, ethanol or propanol, higher Al> alcohols such as ethylene glycol or polyether polyols and ether alcohols such as butyl glycol or ^■ methoxypropanol. Examples of further auxiliaries include, for example, foam attenuators such as polypropoxylates or silicone ethers. The type and amount of additional components or auxiliaries are determined by the person skilled in the art depending on the intended use. The amount of optionally added additional aids is usually 0 to 5% by weight.

In addition to the above-mentioned constituents, formulations for phosphating comprise Zn ions, phosphate ions and, if appropriate, further components such as fluoride, in particular complex fluorides, accelerators such as, for example, nitrite ions or other metal ions such as manganese, copper, magnesium or nickel ions. Acid formulations for phosphating are disclosed, for example, in WO 99/32687, DE-A 19923084 or DE-A 197 23 084.

In the method according to the invention, the metallic surface is brought into contact with the aqueous preparation, for example by spraying, dipping or rolling on. After a dipping process, you can remove excess treatment solution drain the workpiece; in the case of sheets, metal foils or the like, however, excess treatment solution can also be squeezed off, for example.

Of course, metallic surfaces can also be treated inside systems. Internal deposits in boilers, pipelines or the like can be removed by filling the system with the preparation used according to the invention or rinsing it with it. The dissolution of deposits can be accelerated by pumping the preparation around in the system.

The method according to the invention can optionally also comprise one or more pretreatment steps. For example, the metal surface can be cleaned with the preparation used according to the invention prior to pickling, e.g. to remove fats or oils. This is regularly recommended, especially when phosphating.

Furthermore, the method can optionally include post-treatment steps. Mention should be made here in particular of rinsing steps in which the treated surface is rinsed with suitable cleaning liquids, in particular water, in order to remove, for example, residues of the preparation used according to the invention from the surface.

It can also be a so-called "no-rinse" process, in which the treatment solution is dried in a drying oven immediately after application without rinsing.

The treatment can be carried out batchwise or continuously. A continuous process is particularly suitable for treating strip metals. The metal strip is passed through a trough or a spray device and optionally through further pre-treatment or post-treatment stations.

The temperature and duration of the treatment are determined by the person skilled in the art depending on the desired application. On the one hand, higher temperature accelerates the pickling attack on layers to be removed, but on the other hand also accelerates the pickling attack on the metal itself. In general, the temperature of the treatment is 20 to 80 ° C., without the invention being restricted to this range. The duration of treatment can range from 1 s to several hours. The treatment time is usually shorter at higher temperatures than at lower temperatures. When pickling steel strips, a temperature of 60 to 80 ° C, for example 70 ° C, with contact times of 1 to 10 s has proven particularly useful. Sulfur or hydrochloric acid pickling is particularly suitable for steel strips.

In the process according to the invention, the pickling attack on the metal is inhibited significantly more than is the case when using non-alkoxylated pickling inhibitors. Complexing agents work synergistically with the alkoxylated pickling inhibitors and significantly reduce the pickling attack again.

In a further preferred embodiment of the invention, the acidic, aqueous composition can be used as a dampening solution for offset printing. The ethoxylated alkynols contained in the formulation advantageously prevent undesirable corrosion on the printing press and printing plates. In particular, phosphoric acid or organic acids such as succinic acid are suitable as acids for this application, usually as components of a buffer system.

The usual additives known to those skilled in the art can be used as further components for this application. Examples include alcohols such as glycerin, hydrophilic polymers such as gum arabic or cellulose derivatives, surface-active substances and biocides.

The following examples are intended to illustrate the invention:

Used abbreviations:

PA: propargyl alcohol

BDA: 2-butyne-1,4-diol

EO: ethylene oxide

PO: propylene oxide

PA- n EO: propargyl alcohol, ethoxylated with an average of n ethylene oxide units

PAN PO: propargyl alcohol, propoxylated with an average of n propylene oxide units

BDA- n EO: 2-butyne-1,4-diol, ethoxylated with an average of n ethylene oxide units

BDA - n PO: 2-butyne-1,4-diol, propoxylated with an average of n propylene oxide units Production of pickling inhibitors:

The alkoxylated used for the process according to the invention was produced in accordance with the regulation disclosed in DE-A 2241 155.

The production of an ethylene oxide adduct starting from propargyl alcohol is shown as an example below.

Ethoxylated Propagyl Alcohol (PA - 2 EO)

In a 61 pressure reactor with anchor stirrer, temperature control and nitrogen introduction, 1200 g of propyl alcohol are reacted with 24 g of triphenylphosphine and with 2 equivalents of ethylene or propylene oxide within 12 hours under a nitrogen atmosphere between 55-65 ° C.

Preparations used:

The following solutions were used for the examples:

cleanser

Solutions 1 to 3

Solutions of corrosion inhibitor (if any) and complexing agents (if any) were made up in water. The amounts of corrosion inhibitor and complexing agent are given in Tables 1 to 4. The pH was adjusted with an acid. The total amount was 100 g each.

Solution 1 adjusted to pH 3.5 with 15% HCI. Solution 2 with conc. H ₂ SO adjusted to pH 1

Solution 3 with conc. H ₃ PO ₄ adjusted to pH 3.5

Pickling degreaser solution 4 1 g pickling inhibitor (according to Table 5) 3 g non-ionic surfactant: saturated Ci3-oxo alcohol, ethoxylated, on average 8 EO units 0.2 g anionic surfactant: acidic phosphoric acid ester of a fatty alcohol alkoxide 50 g HCI conc. (37% HCI) 45.8 g water water content: 77.3% water + acid content: 95.8%

Solution 4a as solution 4, additionally 0.2% by weight of methylglycinediacetic acid, (0.2% by weight of water less)

Solution 5 1 g pickling inhibitor (according to Table 5) 3 g non-ionic surfactant: saturated C ₃ -oxo alcohol, ethoxylated, on average 8 EO units 3 g 3-nitrobenzenesulfonic acid 0.5 g alkylphenol ether sulfate, Na salt, 40% 50 g HCI conc , (37% HCI) 42.5 g water water content: 74.3% water + acid content: 92.8%

Solution 6 2 g pickling inhibitor (according to Table 5) 0.5 g non-ionic surfactant: oleylamine, ethoxylated, on average 12 EO units 0.5 g non-ionic surfactant: saturated C ₁₃ oxo alcohol, ethoxylated, on average 8 EO units 25 g H ₂ SO ₄ conc. (96%) 72 g water

Water content: 73% water + acid content: 97%

Sour rust remover

Solution 7 1 g pickling inhibitor (according to Table 5) 12 g non-ionic surfactant: saturated Ci ₃ -i ₅ -oxoalcohol, ethoxylated, through an average of 8 EO units 5 g dodecylbenzenesulfonic acid 40 g H ₃ PO ₄ conc. (85%) 42 g water

Water content: 48% water + acid content: 82%

Solution 7a as solution 7, additionally 0.2% by weight methylglycinediacetic acid, (0.2% by weight water less)

Acidic cleaners

Solution 8 5 g pickling inhibitor (according to Table 5) 8 g non-ionic surfactant: saturated C ₁₃ oxo alcohol, ethoxylated, on average 12 EO units 50 g H ₃ PO ₄ conc. (85%) 37 g water water content: 44.5% water + acid content: 87% Polymer complexing agents and cationic polymers as additives

0.5% solutions of corrosion inhibitor (if present) and 0.25% solutions of complexing agent (if present) in water were used. The total amount was 100 g each.

Solution 9 0.5 g pickling inhibitor with conc. H ₂ SO ₄ adjusted to pH 1 and dissolved with 50 g / l Fe (II) sulfate.

Solution 10 Like solution 9, additional 0.25% by weight methylglycinediacetic acid Solution 11 Like solution 9, additional 0.25% by weight of a polymeric complexing agent (polyethyleneimine, modified with acetic acid groups, Na salt)

Solution 12 As solution 9, additionally 0.25% by weight of a cationic polymer of the general formula

General test instructions:

1. Measuring principle:

Defined test sheets made of St 1.0037, AI 99.9 or Zn 99.8 are immersed in a constant test solution (see solutions 1-7) for 1h or 24h at room temperature and the area-related mass loss is determined gravimetrically using differential weighing.

The preparation and cleaning of the sheets is carried out according to ISO 8407 material-specific and is explicitly listed for this St1.0037.

Preparation of the sheets:

Degreasing: A solution of the degreasing bath with the following composition is used in a plastic tub with two flat electrodes (stainless steel or graphite) that are larger than the test plate: 20 g NaOH 22 g Na ₂ CO ₃ 16 g Na ₃ PO ₄ * 12 H ₂ O 1 g ethylenediaminetetraacetic acid (EDTA) 0.5 g non-ionic surfactant: alkylphenol, ethoxylated, on average 10 EO units in approx. 940 ml deionized water.

NaOH, Na ₂ CO ₃ and Na ₃ PO _{4 are dissolved} in DI water in succession with stirring. At the same time, EDTA and the surfactant are separately pre-dissolved in demineralized water, with the surfactant solution at a temperature of 50 ° C. The EDTA and surfactant solutions are then added to the sodium hydroxide solution in a measuring cylinder and, after cooling, made up to 1000 ml with demineralized water.

Rust removal: In a plastic tub with two flat electrodes that are larger than the test plate, a solution of the rust removal bath of the following composition is used: 100 g diammonium citrate in 1000 ml water

A sheet of steel measuring 50 mm x 20 mm x 1 mm is wiped with a paper rag and immersed in the degreasing bath between the electrodes at 10 volts and switched as a cathode. The voltage is adjusted so that the current is 1A. After ten seconds, the steel sheet is removed and rinsed under running water for five seconds. The steel sheet is immersed at 10 V in the rust removal bath between the electrodes and switched as the cathode. The tension is adjusted so that the

Current is 1A. After three minutes, the steel sheet is removed and rinsed under running deionized water for five seconds, blown off with air and used immediately for the test.

Beiztests

The metal sheet, size 50 mm x 20 mm x 1 mm, is degreased and derusted electrolytically.

The initial mass is determined with the analytical balance. The metal sheet is used immediately after weighing. The prepared metal sheet is placed diagonally in a 200ml glass bottle with test solution. The angle between sheet steel and floor is 35 °. The glass bottle is tightly closed and stored at room temperature. During storage, the glass bottle is shaken briefly once every 6 hours. The metal sheet is removed from the solution, rinsed with demineralized water, brushed with steel wool, rinsed with demineralized water and blown dry with air. The mass is then determined.

The gravimetric pickling test is carried out as a tenfold determination and the mean value is formed.

In parallel to the test, a tenfold determination was carried out without a pickling inhibitor and with but-2-yne-1,4-diol or propagyl alcohol as a pickling inhibitor.

4. Evaluation of the results

The difference between the first and second weighing in mg / cm ^{2 is} noted for each metal sheet (Δmp _r0 be) - In addition, the efficiency E of the active ingredient can be specified, by means of which the mass loss Δm _Pr0be in relation to the mass loss in the corrosion test without inhibitor Δm _{0 is} set. It applies

E = (Δm ₀ - Δmprobe) / Δm ₀ On max. The inhibition efficiency can therefore be 1 (no metal removal), O (in demineralized water), but it can also be <0 if the additives lead to accelerated corrosion.

Examples:

Tests without complexing agents

Examples 1 to 8, Comparative Examples 1 to 3

Solution 1 was used for the experiments (HCl, pH 3.5). The area-related removal of metal at 30 ° C. after 1 h or 24 h and the inhibition efficiency E were determined for sheet metal made of 1.0037 steel according to the method generally described above. The pickling inhibitors specified in Table 1 were used in the amounts indicated. A complexing agent was not present in these experiments. The results are summarized in Table 1.

Examples 9 and 10, Comparative Examples 4 and 5

Solution 2 was used for the experiments (H ₂ SO ₄ , pH 1). The area-related metal removal at 30 ° C. after 1 hour or 24 hours and the inhibition efficiency E were determined for steel sheets 1.0037 in accordance with the method generally described above. There were the pickling inhibitors specified in Table 2 in the amounts indicated used. A complexing agent was not present in these experiments. The results are summarized in Table 2.

Synergistic mixture with complexing agent

Examples 11 to 18, Comparative Examples 6 and 7

Solution 1 was used for the experiments (HCl, pH 3.5). The inhibition efficiency E was determined for steel sheets 1.0037 according to the method generally described above at room temperature after 1 hour. The pickling inhibitors and complexing agents given in Table 3 were used in the amounts indicated. The results are summarized in Table 3.

Examples 19 to 30, Comparative Examples 8 to 10

Solution 3 was used for the experiments (HCl, pH 3.5). The inhibition efficiency E was determined for steel sheets 1.0037 according to the method generally described above at room temperature after 1 h. The pickling inhibitors and complexing agents specified in Table 4 were used in the amounts specified. The results are summarized in Table 4.

Examples 31 to 42, Comparative Examples 11 to 15

Solutions 4 to 8 were used for the experiments (see above). The inhibition efficiency E was determined for steel sheets 1.0037 according to the method generally described above at room temperature after 1 h. The pickling inhibitors and complexing agents specified in Table 5 were used in the amounts specified. The results are summarized in Table 5.

Table 1: Test with solution 1 (HCI, pH 3.5)

Table 3: Tests with solution 1 (HCI, pH 3.5)

Table 4: Tests with solution 3 (H ₃ PO ₄ , pH 3.5)

Table 5: Test of various cleaning, pickling or decalcifying formulations

Table 6: Test with solution 9 (H ₂ SO, pH 1), comparison of different additives

The examples show that the alkoxylated pickling inhibitors used according to the invention inhibit considerably better than propargyl alcohol or butynediol. This not only provided a replacement that was less harmful from an ecological point of view, but also a replacement with a better effect. This applies in particular to steel surfaces.

In addition, they surprisingly interact with complexing agents in a synergistic manner. While the complexing agent used alone accelerates the dissolution of the metal, the combination of complexing agent and pickling inhibitor results in a stronger inhibition than with the pickling inhibitor alone.

Claims

claims

1. Method for pickling metallic surfaces by treating the metallic surface with an acidic aqueous preparation which comprises at least one acid, a pickling inhibitor and optionally further additives, characterized in that the aqueous preparation comprises at least the following components:

(a) 60 to 99.99% by weight of a mixture of water and at least one acid,

HC ≡e-CH ₂ -O (-CH ₂ -CHR ¹ -O-) _n H or

H (-O-CHR ¹ -CH ₂ -) nO-CH ₂ -C ^ -CH ₂ -O (-CH ₂ -CHR ¹ -O-) _n .H, where the radicals R ^{1 are} each independently of one another H or Methyl and the indices n and n 'independently of one another represent 1 to 10, (c) 0 to 38% by weight of one or more additives and / or auxiliaries.

2. The method according to claim 1, characterized in that the indices n and n 'independently of one another are 1 to 3

3. The method according to claim 1 or 2, characterized in that the composition further comprises 0.01 to 20 wt.% At least one surface-active substance.

4. The method according to any one of claims 1 to 3, characterized in that the composition further comprises 0.01 to 10% by weight of at least one water-soluble acid group comprising at least bidentate chelating complexing agent.

5. The method according to claim 4, characterized in that the weight ratio of complexing agent to pickling inhibitor is 5: 1 to 1:10

6. The method according to any one of claims 1-3, characterized in that the composition further comprises 0.01-10% by weight of at least one water-soluble polymer containing quaternized ammonium groups.

7. The method according to any one of claims 1 to 6, characterized in that the amount of water and acid is 70 to 99.99 wt.%.

8. The method according to any one of claims 1 to 7, characterized in that the pH of the composition is 3 to 6.

9. The method according to any one of claims 1 to 8, characterized in that the acid is at least one selected from the group of hydrochloric acid, sulfuric acid, methanesulfonic acid or phosphoric acid.

10. The method according to any one of claims 1 to 9, characterized in that the metallic surface is the surface of iron, steel, zinc, brass or aluminum.

11. The method according to any one of claims 1 to 10, characterized in that the surface is the surface of a strip metal.

12. Acidic, aqueous composition for pickling metallic surfaces, which comprises at least one acid, a pickling inhibitor and optionally further additives, characterized in that the aqueous preparation comprises at least the following components: ...

(a) 60 to 99.97% by weight of a mixture of water and at least one acid, (b) 0.01 to 2% by weight of at least one alkali alkoxylate of the general formula

HC ≡C-CH ₂ -O (-CH ₂ -CHR ¹ -O-) _n H or

H (-0-CHR ¹ -CH ₂ -) _n -O-CH ₂ -C≡C-CH ₂ -O (-CH ₂ -CHR ¹ -O-) _n .H, where the radicals R ^{1 are} each independently represents H or methyl and the indices n and n 'independently of one another are 1 to 10, (c) 0.01 to 20% by weight of at least one surface-active substance, and

(d) 0.01 to 10% by weight of at least one water-soluble, acidic group-containing, at least bidentate, chelating complexing agent and / or at least one water-soluble, quaternized ammonium group-containing polymer.

13. The composition according to claim 12, characterized in that the aqueous preparation has the following composition:

(a) 70 to 98.9% by weight of a mixture of water and at least one acid, (b) 0.1 to 2% by weight of alkali alkoxylates, (c) 0.5 to 15% by weight of surface-active substance, and (d ) 0.5 to 10% by weight of chelating complexing agent and / or polymer comprising quaternized ammonium groups.