EP0124851A2 - Composition and process for metal cleaning and passivation by spraying - Google Patents

Abstract

Compositions and processes for cleaning and passivating metals wherein the cleaning operation is carried out at temperatures of from room temperature to 100 DEG C. and said compositions are aqueous solutions containing a phosphoric acid ester, an alkanolamine, at least one sprayable surfactant and, optionally, builders, non-ferrous metal inhibitors, and/or biocides.

Description

The invention relates to agents and a method for cleaning and / or passivating metals by spraying, as an additive to grinding and pressure water and as a passivating agent in cooling circuits.

Metal surfaces which have been machined by spraying are generally cleaned using aqueous cleaners based on organic rust inhibitors, for example combinations of alkanolamines and fatty acids, surfactants, anti-foaming agents and / or Ph ^q sponates, and if necessary. Biocides and builder substances, the cleaners mentioned being used in aqueous liquids at a pH of 7.5 to 10.5; usually called "neutral cleaner".

To avoid undesirable signs of corrosion, it is often advisable to passivate the metal surface with aqueous solutions that contain the appropriate chemical additives. This is expediently carried out during or after cleaning operations during metal processing or before the intermediate storage before further processing of the metals.

The neutral cleaners and corrosion protection agents that have been customary up to now are only suitable for the treatment of iron and steel without further additives. Such cleaning and passivating agents which inhibit the corrosion of iron and steel surfaces contain, for example, alkali metal nitrites, alkanolamines, soaps and benzoates.

In addition to ferrous metals, non-ferrous and light metals and their alloys, especially zinc, aluminum and their alloys, are increasingly coming into contact with cleaning and passivating agents. For _B untmetalle stand as inhibitors eg mercaptobenzothiazole and benzotriazole are available. However, these passivation components have the disadvantage that they do not prevent discoloration of the surfaces of light metals (fountain water blackness). Zinc, aluminum and their alloys are also attacked by the cleaning agents. A correspondingly high metal removal is found, which can sometimes no longer be tolerated with precision parts. This applies in particular to the new types of motors and transmissions made of light metal alloys in the automotive sector.

• Um eine automatische Steuerung und Dosierung der Reinigungsflüssigkeiten auch in Leitungswasser zu ermöglichen, was in der Regel über eine Leitfähigkeitsmessung erfolgt, enthalten die bislang üblichen Reinigungsmittel Polyphosphate, die sich besonders bei höheren Temperaturen zu Pyro- bzw. Orthophosphaten abbauen. Sehr häufig führt die Verwendung derartiger anorganischer Ionen zu _Ausfällungen mit den Härtebildnern des Wassers, also zu Calcium- oder Magnesiumphosphat-Niederschlägen, in Gegenwart entsprechender Legierungen auch zu Aluminiumphosphatausfällungen. Die Folge sind nicht nur störende Auftrocknungen auf den zu bearbeitenden Teilen, sondern auch Verklebung, Versteinung oder sogar Verstopfung von Anlageteilen und Pumpen.

On the other hand, the trend towards automation requires additional special cleaning systems:

• In order to enable automatic control and metering of the cleaning fluids in tap water, which is usually done via a conductivity measurement, the cleaning agents that have been common until now contain polyphosphates, which break down into pyro- or orthophosphates, especially at higher temperatures. Very often, the use of such inorganic ions to usfällungen _A with the hardness components of water, so to calcium or magnesium phosphate-precipitation, in the presence of appropriate alloys also Aluminiumphosphatausfällungen. The result is not only annoying drying on the parts to be machined, but also gluing, petrification or even blockage of system parts and pumps.

Furthermore, precipitated phosphates, especially aluminum phosphates, can lead to undesired coagulation processes, e.g. for irreversible binding of surfactants or anti-foaming agents. This leads to a significantly higher tendency to foam and thus to the quick inoperability of the cleaning solution. In addition, these electrolyte-containing products usually result in increased metal removal and very rapid discoloration of the light or non-ferrous metal.

It has now surprisingly been found that a combination of special phosphoric acid esters and alkanolamines in conjunction with injectable surfactants drastically reduces metal removal; Discoloration of the metal surfaces is not observed.

• a) Phosphorsäureester
• b) Alkanolamine und/oder Alkanolaminsalze
• c) mindestens ein spritzfähiges nichtionisches Tensid, sowie ggfls.
• d) Buildersubstanzen, Komplexbildner und/oder Biozide enthalten.

The invention accordingly relates to agents for cleaning and passivating metals by spraying, which are characterized in that they

• a) phosphoric acid esters
• b) alkanolamines and / or alkanolamine salts
• c) at least one sprayable nonionic surfactant, and if necessary.
• d) contain builder substances, complexing agents and / or biocides.

The cleaning agents according to the invention are characterized in that those phosphoric acid esters are used which ensure a trouble-free process flow without foaming. This is all the more surprising since the OE-PS 235 149 describes phosphoric acid esters as foam stabilizers.

The preferred phosphoric acid esters of ethoxylated fatty alcohols are also insensitive to calcium and magnesium ions. The effect of inhibiting the surfaces of various light metals is therefore guaranteed even in hard water.

Since the agents according to the invention do not contain phosphates, there is also no disadvantageous precipitation of phosphate salts.

Due to the good inhibitory effect of the phosphoric acid esters, the aluminum removal remains extremely low. In addition, discoloration of the cleaned metal surfaces is practically not observed. The inhibitory effect against ferrous metals, but especially true ferrous and light metals and zinc, making cleaning compositions of the invention to universally suitable cleaners, for example for use in large Zentralanla ^g s.

• a) Mono- und/oder Diester der Phosphorsäure mit Alkanolen mit 10 - 20 C-Atomen;
• b) Mono- und/oder Diester der Phosphorsäure mit ethoxylierten und/oder propoxylierten Alkanolen mit 10 - 20 C-Atomen;
• c) Phosphorsäureester von Polyethylenglykol- und/oder Polypropylenglykolethern; bzw. deren wasserlösliche Salze

The light metal inhibitors according to the invention can be phosphoric acid esters of different provenance:

• a) mono- and / or diesters of phosphoric acid with alkanols with 10-20 C atoms;
• b) mono- and / or diesters of phosphoric acid with ethoxylated and / or propoxylated alkanols with 10-20 C atoms;
• c) phosphoric acid esters of polyethylene glycol and / or polypropylene glycol ethers; or their water-soluble salts

All alcohols can be straight-chain, branched, saturated or unsaturated. Straight-chain fatty alcohols (alkanols with 10-20 C atoms) are preferably used.

The monoesters of phosphoric acid with ethoxylated, straight-chain alkanols having 10-20 C atoms and their sodium, potassium, ammonium or alkanolamine salts are preferably used in the agents according to the invention.

This _' class of compounds is particularly characterized in that when used in the combination according to the invention in aqueous solution, especially in spray systems, no disruptive foam is generated, and thus a smooth process flow in automatic cleaning machines is ensured.

_D a Those ethoxylated hydrophilic Monoester in hard water no precipitation of calcium or _M cause agnesiumsalzen, Auftrocknungen be avoided on the cleaned parts, could be the cause of corrosion. Such precipitates would also cause unnecessary, non-effect-related consumption of the inhibitor, which would make practical use impossible. The inhibition effect is therefore also unrestricted in hard water.

In contrast to other cleaning agents (EP-A 81 810 136.6), the use of zinc salts can be dispensed with when using the cleaners according to the invention.

Suitable alkanolamines for the purposes of the invention are, for example, the following compounds: mono-, di- and triisopropanolamine, n-propanolamine, N, N, N ', N'-tetrakis (2-hydroxyethyl) ethylenediamine and preferably mono-, Di- and triethanolamine, individually or in a mixture. Suitable alkanolamine salts are, for example, salts of the abovementioned compounds with linear and / or branched mono- and / or dicarboxylic acids and / or sulfonic acid derivatives. Suitable mono- and / or dicarboxylic acids here are, in particular, 2-ethylhexyl acid, caprylic acid, isononanoic acid, capric acid and sebacic acid. A suitable sulfonic acid derivative is, for example, benzenesulfonyl-N-methyl-aminocaproic acid.

The cleaning liquids contain such sprayable nonionic surfactants that the agents can be used and sprayed in all temperature ranges without disturbing foaming. The surfactants of such combinations remain dispersed in the cleaning liquid above the cloud point and do not separate. This results in a very good, constant cleaning effect. At the same time such combinations is achieved that separates from ewaschenes ^g, little self-emulsifying oil on the surface of the storage baths, and, for example, can be separated by Ringkammerentöler or separators, in mechanical form by the use. Emulsification is practically prevented, which significantly extends the service life of the baths. If necessary, however, the emulsifying effect can be increased by appropriate emulsifier additives if this should be necessary or desired in special cases.

A major advantage that the agents according to the invention have is that they enable automatic control of the cleaning process and metering of the cleaning solution. In the present method, too, the control and metering are carried out via the conductivity of the Detergent solution, but without the need to use phosphates to generate conductivity. Although electrolytes generally greatly increase the removal of light metals, it is possible to achieve a conductivity which is appropriate to practice by using the phosphoric acid esters mentioned in combination with alkanolamines and / or alkanölamine salts of linear and / or branched mono- or dicarboxylic acids and / or sulfonic acid derivatives. In particular, mixtures of monoethanolamine, if necessary, for the conductivity 'combination. in the presence of other alkanolamines, and mono- and / or dicarboxylic acids, preferably isononanoic acid. To increase the effectiveness and stabilization of this conductivity combination, builder substances such as borates, gluconates, potassium hydroxide and / or aminopolycarboxylic acids or their salts, preferably ethylenediaminetetraacetate or nitrilotriacetate, are added.

Die jeweilige Einsatzkonzentration dieser Komponenten ist so zu wählen, daß die Leitfähigkeit in entsprechendem Prozeßwasser ausreichend groß ist, um die automatische Dosierung und Steuerung zu ermöglichen. Gleichzeitig dürfen die Mischungen nicht zu Ausfällungen führen.The use of the combination due to which compositions of the invention have the desired conductivity is carried within the framework of the total combination in amounts of a total of 0.5 - 5 wt _-.%. The aqueous solutions, whose pH is between 7.5 and 10.5, contain the following components:

The respective application concentration of these components must be selected so that the conductivity in the corresponding process water is sufficiently large to enable automatic metering and control. At the same time, the mixtures must not lead to precipitation.

Optionally, no biocides, cleaning agents according to the invention, for example, derivatives of hexahydrotriazine, such as the reaction product of monoethanolamine with formaldehyde, can be added without this the essential characteristics such as cleaning and passivating ungs- ^g, conductivity or foaming affected.

Optionally, non-ferrous metal inhibitors, e.g. Mercaptobenzothiazole or benzotriazole added.

The use concentrations of the phosphoric acid esters in the application solutions are 10 to 1000 ppm, but preferably 10 to 300 ppm when the agent is used as a neutral cleaner.

For the usual, short treatment times, approx. 25 ppm phosphoric acid esters in the application liquid are sufficient to achieve the passivation effect according to the invention with good cleaning at the same time.

When used in similar areas, e.g. in closed systems such as cooling circuits as passivating agents, the amounts can be above 300 ppm.

The process according to the invention is therefore carried out using the agents mentioned, the pH of which is in the range from 7.5 to 10.5. The cleaning or passivation process with the agents which contain the phosphoric acid esters in concentrations in the range from 10 to 1000 ppm, preferably 10 to 300 ppm, takes place at room temperature to 100 ° C., preferably between 35 and 70 ° C.

• A. Herstellung der erfindungsgemäßen Mittel.

The agents according to the invention and the cleaning and passivation process are explained in more detail by the following examples:

• A. Preparation of the agents according to the invention.

The acidic and alkaline components, the surfactants, the non-ferrous and light metal additives were gradually added to the amount of water at room temperature while stirring and if necessary. added the biocides. Either fully demineralized water (VEW), tap water (LW) or water in which a hardness of 5 ° d with magnesium sulfate or calcium chloride had been set (5 ° d Mg ²⁺ or 5 ° d _Ca ²⁺ ₎ .

B. Determination of aluminum and zinc removal.

A test solution of a certain concentration was prepared in defined water at room temperature. 1000 ml of the test solution were heated to 65 ° C. in an appropriate glass vessel. Test sheets measuring 50 x 100 mm were immersed freely suspended on a glass hook in the mechanically moved liquid, the glass vessel was covered. After 1 hour, the test sheet removed, the liquid cooled, adjusted to pH = approx. 2 with hydrochloric acid, the liquid volume made up to 1000 ml with deionized water and part of the hydrochloric acid liquid filtered. If turbidity occurs, some of the hydrochloric acid liquid can also be centrifuged if necessary.

The aluminum concentration in the clear solution could be determined either with the aid of atomic absorption or photometrically (filter 535 nm) with eriochrome cyanine in ammonium acetate buffered solution, the zinc concentration only with atomic absorption.

C. Determination of the Degree of Inhibition.

The inhibitory properties of the agents according to the invention on zinc, aluminum and aluminum alloys were determined according to the arrangement described under B. The degree of inhibition k is calculated using the formula:

• k den Inhibierungsgrad in %
• a die Metallionenkonzentration in einer Prüflösung ohne Inhibitor
• b die Metallionenkonzentration in einer Prüflösung mit Inhibitor.

Where:

• k the degree of inhibition in%
• a the metal ion concentration in a test solution without inhibitor
• b the metal ion concentration in a test solution with inhibitor.

The composition of the inhibitors used for the production of the cleaning agents according to the invention can be seen from the following list:

In den folgenden Beispielen werden die Aktivsubstanzen der wässrigen Konzentrate in Gewichts-% genannt; hierin bedeuten EO = Ethylenoxid, PO = Propylenoxid.

In the following examples, the active substances of the aqueous concentrates are given in% by weight; EO = ethylene oxide, PO = propylene oxide.

example 1

• 7% monoethanolamine
• 9% diethanolamine
• 7% triethanolamine
• 7% isononanoic acid
• 7% mixture of branched carboxylic acids with 9 - 11 carbon atoms
• 5% boric acid
• 1% inhibitor 1, 30%
• 5% isotridecyl alcohol + 3 PO
• 52% demineralized water (VEW) spray temperature: above 35 ° C

Example 2

• 7% monoethanolamine
• 9% diethanolamine
• 7% triethanolamine
• 7% isononanoic acid
• 7% mixture of branched carboxylic acids with 9 - 11 carbon atoms
• 5% boric acid
• 3% inhibitor 1, 30%
• 3% of an adduct of 30 EO and 60 PO of ethylenediamine
• 2% of an adduct of 2 _EO and 4 PO to an alkanol with 12-18 C atoms
• 50% VEW
• Spray temperature: above 45 ° C

Example 3

• 7% monoethanolamine
• 9% diethanolamine
• 7% triethanolamine
• 7% isononanoic acid
• 7% mixture of branched carboxylic acids with 9 - 11 carbon atoms
• 5% boric acid
• 2% inhibitor 1, 30%
• 4% 2-ethylhexanol + 3 PO
• 1% of an adduct of 2 EO and 4 PO to an alkonol with 12 - 18 C atoms
• 51% VEW
• Spray temperature: above 50 ° C

Example 4

• 7% monoethanolamine
• 9% diethanolamine
• 7% triethanolamine
• 7% isononanoic acid
• 7% mixture of branched carboxylic acids with 9 - 11 carbon atoms
• 5% boric acid
• 2% inhibitor 1, 30%
• 5% of an adduct of 2 EO and 4 PO to an alkanol with 12-18 C atoms
• 3% of an adduct of 5 EO and 4 PO to an alkanol with 12 - 14 C atoms
• 48% VEW
• Spray temperature: above 60 ° C

Example 5

• 30% triethanolamine
• 10% caprylic acid
• 5% hexahydrotriazine derivative
• 0.5% mercaptobenzothiazole
• 0.3% inhibitor 1, 30%
• 3% of an adduct of 3 PO with isotridecyl alcohol
• 51.2% VEW
• Spray temperature: above 20 ° C

Example 6

• 30% triethanolamine
• 10% caprylic acid
• 5% hexahydrotriazine derivative
• 0.5% mercaptobenzothiazole
• 1% inhibitor 1, 30%
• 3% of an adduct of 3 PO with isotridecyl alcohol
• 3% of an adduct of 2 EO and 4 PO to an alkanol with 12-18 C atoms
• 47.5% VEW
• Spray temperature: above 30 ° C.

Example 7

• 30% triethanolamine
• 10% caprylic acid
• 5% hexahydrotriazine derivative
• 0.5% mercaptobenzothiazole
• 0.5% inhibitor 1, 30%
• 4% of an adduct of 2 EO and 4 PO to an alkanol with 12-18 C atoms
• 1% of an adduct of 5 EO and 30 PO on propylene glycol-1.2
• 49 9% VEW
• Spray temperature: above 45 ° C

Example 8

• 30% triethanolamine
• 10% caprylic acid
• 5% hexahydrotriazine derivative
• 0.5% mercaptobenzothiazole
• 0.5% inhibitor 2
• 3% of an adduct of 2 EO and 4 PO to an alkanol with 12-18 C atoms
• 3% of an adduct of 5 EO and 4 PO to an alkanol with 12 - 14 C atoms
• 48% VEW
• Spray temperature: above 55 ° C.

Example 9

• 20% diethanolamine
• 10% sebacic acid
• 10% isononanoic acid
• 1% inhibitor 2
• 5% of an adduct of 2 EO and 4PO to an alkanol with 12-18 C atoms
• 54% VEW
• Spray temperature: above 60 ° C

Example 10

• 20% triethanolamine
• 10% benzenesulfonyl-N-methyl-ε-aminocaproic acid
• 10% isononanoic acid
• 3% of an adduct of 3 PO to an alkanol with 12-14 carbon atoms
• 2% inhibitor 1
• 0.4% tetrasodium ethylenediaminetetraacetate
• 54.6% VEW
• Spray temperature: above 30 ° C

Example 11

• 30% diethanolamine
• 5% benzenesulfonyl-N-methyl-ε-aminocaproic acid
• 5% sebacic acid
• 5% caprylic acid
• 3% of an adduct of 3 PO to an alkanol with 12-14 carbon atoms
• 2% of an adduct of 2 EO and 4 PO to an alkanol with 12-18 C atoms
• 0.8% inhibitor 2
• 49.2% VEW
• Spray temperature: above 35 ° C

The aluminum removal values for the cleaning mixtures of Examples 1-11, including the blank tests a) and b), are shown in Table 1 below.

Examples 12-22

• 50 %-Wasser (VEW) .
• 15 % Monoethanolamin
• 15 % Triethanolamin
• 10 % Caprylsäure
• 10 % Versatic 10^R

The cleaning agents exemplified in Examples 12-22 contained the following components in addition to the inhibitors specified in Table 2:

• 50% water (VEW).
• 15% monoethanolamine
• 15% triethanolamine
• 10% caprylic acid
• 10% Versatic 10 ^R

This mixture was used in a concentration of 30 g / 1 in LW or VEW at a pH of 9.7.

The inhibitory properties of the agents according to the invention from Examples 12-22 are summarized in Table 2. Examples 12, 17, 19 and 21 are control examples in which the cleaning mixture did not contain an inhibitor according to the invention.

Examples 23-29

• 50 %^--Wasser VEW
• 10 % Monoisopropanolamin
• 10 % Diisopropanolamin
• 10 % Diethanolamin
• 10 % Triethanolamin
• 10 % Borsäure

Diese Mischung wurde eingesetzt in einer Konzentration von 25 g / 1 in LW oder VEW bei einem pH-Wert von 9,6.The cleaning agents exemplified in Examples 23-29 contained the following components in addition to the inhibitors listed in Table 3:

• 50% ^- -water VEW
• 10% monoisopropanolamine
• 10% diisopropanolamine
• 10% diethanolamine
• 10% triethanolamine
• 10% boric acid

This mixture was used in a concentration of 25 g / 1 in LW or VEW at a pH of 9.6.

The inhibiting properties of the agents according to the invention from Examples 23-31 can be found in Table 3. Examples 23 and 27 are control examples in which the cleaning agents did not contain an inhibitor.

Examples 30-32

• 50 %-VEW
• 20 % Triethanolamin
• 10 % Na-Glukonat
• 10 % Glyzerin
• 8 % Polyethylenglycol mit einem Molekulargewicht von 300
• 2 % Benzotriazol

The cleaning agents exemplified in Examples 30-32 contained the following components in addition to the inhibitors listed in Table 4:

• 50% -VEW
• 20% triethanolamine
• 10% Na gluconate
• 10% glycerin
• 8% polyethylene glycol with a molecular weight of 300
• 2% benzotriazole

This mixture was used in a concentration of 10 g / 1 in VEW at a pH of 8.6.

The inhibitory properties of the agents according to the invention from Examples 30-32 are summarized in Table 4. Example 30 is a control example in which the cleaning agent contained no inhibitor.

Examples 33-41

• 51 % VEW
• 7 % Monoethanolamin
• 9 % Diethanolamin
• 7 % Triethanolamin
• 7 % Isononansäure
• 7 % Versatic 911^R
• 5 % Borsäure
• 5 % Na-Glukonat
• 2 % eines Anlagerungsproduktes von 5 EO und 30 PO an Propylenglycol.

In addition to the inhibitors listed in Table 5, the cleaning agents exemplified in Examples 33-41 also contained the following components:

• 51% VEW
• 7% monoethanolamine
• 9% diethanolamine
• 7% triethanolamine
• 7% isononanoic acid
• 7% Versatic 911 ^R
• 5% boric acid
• 5% Na gluconate
• 2% of an adduct of 5 EO and 30 PO of propylene glycol.

This mixture was used in a concentration of 20 g / 1 in VEW or LW at a pH of 9.2.

The inhibitory properties of the agents according to the invention from Examples 33-41 are summarized in Table 5. Examples 33, 36 and 39 are control examples in which the cleaning agents contained no inhibitor.

Claims (4)

1. Means for cleaning and passivation of metals by spraying, characterized in that they a) mono- and / or diesters of phosphoric acid with -alkanols having 10-20 C atoms, mono- and / or diesters of phosphoric acid with ethoxylated and / or propoxylated alkanols or phosphoric acid esters of polyethylene glycol and / or polypropylene glycol ethers; or their water-soluble salts, b) alkanolamines and / or alkanolamine salts of linear and / or branched mono- and / or dicarboxylic acids and / or sulfonic acid derivatives, c) at least one sprayable nonionic surfactant and optionally d) contain builder substances, biocides and / or non-ferrous metal inhibitors. 2. Composition according to claim 1, characterized in that they contain alkali, ammonium and / or alkanolamine salts of monoesters of phosphoric acid with ethoxylated straight-chain alkanols with 10-20 C atoms. 3. Compositions according to claim 1 and 2, characterized in that they contain borates, gluconates, potassium hydroxide and / or aminopolycarboxylic acids or their salts as builder substances. 4. Process for cleaning and passivation of metals by spraying, characterized in that aqueous solutions of the agents according to claims 1 to 3 are used, the pH of which is in the range from 7.5 to 10.5 and the concentrations of the phosphoric acid esters are in the range from 10 to 1,000 ppm, preferably 10 to 300 ppm, and the cleaning is carried out at temperatures from room temperature to 100 ° C., preferably between 35 and 70 ° C.