EP0667891A1

EP0667891A1 - Dialkyl esters for use in agents for treating metal surfaces

Info

Publication number: EP0667891A1
Application number: EP93923564A
Authority: EP
Inventors: Jürgen Geke; Carsten Friese; Richard Cornely; Helmut Endres; Bernd Fabry; Matthias Fies; Hans-Peter ÖLSCHER; Bernd Stedry
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1992-11-06
Filing date: 1993-10-28
Publication date: 1995-08-23
Also published as: WO1994011469A1

Abstract

The invention concerns the use of at least substantially water-insoluble dialkyl ethers of natural or synthetic mono- and/or polyhydric alcohols, the ethers being liquid at working temperatures, as the oil phase in agents for treating metal surfaces and in cooling lubricants. The invention also concerns agents containing at least such dialkyl ethers, corrosion inhibitors and emulsifiers. These dialkyl ethers are intended for use as mineral-oil substitutes.

Description

Dialkyl ethers in metal surface treatment agents

The invention relates to the use of dialkyl ethers as an oil phase in metal surface treatment agents, for example in cooling lubricants for cutting or non-cutting shaping metal processing, and in cleaning and corrosion protection emulsions, and metal surface treatment agents which contain at least dialkyl ethers, corrosion inhibitors and emulsifiers.

When metal is shaped, cooling lubricants are required, which essentially reduce the friction between the tool and the workpiece, dissipate the heat generated and remove the metal abrasion or chips. For the purposes of the invention, the term “shaping metalworking” is understood to mean chipless forming processes such as rolling, cold extrusion, deep drawing and wire and tube drawing, as well as cutting processes such as cutting, drilling, turning, milling, grinding, honing or lapping .

An overview of the shaping metalworking processes and the aids usually used for this purpose can be found, for example, in Ullmann's Encyclopaedia of Industrial Chemistry, 5th Ed., Vol.Alδ, 479-486.

Cooling lubricants are often O / W emulsions (= oil-in-water emulsions). Means for shaping metalworking can, however, also be used as an essentially water-free oil phase. As a rule, the oil phase of these agents is based on mineral oil. The mineral oil qualities used are predominant. Combinations of paraffinic, naphthenic and aromatic hydrocarbon compounds. In addition to the mine Ral oils also have so-called synthetic lubricants ("synthetic oils"), such as polyolefins, polyalkylene glycols and polyglycol ethers, natural ester oils and synthetic esters and their derivatives. In addition, the metal surface treatment agents mentioned contain special active ingredient additives for setting the desired performance properties.

In addition to cooling lubricants, the metal surface treatment agents also include cleaning and corrosion protection emulsions.

If metallic workpieces, such as body components, are exposed to the influence of atmospheric conditions, the interplay of air humidity and heat causes the appearance of corrosion phenomena, which are undesirable primarily for aesthetic reasons, but can destroy the workpieces in the long term. For this reason there is a sustained interest in means by means of which these corrosion effects, if not eliminated, can at least be significantly delayed.

There is extensive literature in the field of corrosion protection. Modern corrosion protection agents usually contain non-polar or polar oils, emulsifiers, corrosion inhibitors and, if necessary, water. Their effect is based on the adsorption of inhibitor molecules on the metal surface and the formation of a protective film from emulsion constituents, which acts as a diffusion barrier for atmospheric oxygen and water. Other commercially available systems are based on anhydrous oil concentrates which contain emulsifiers and corrosion inhibitors. However, this means that only those active ingredients can be used that have sufficient oil solubility [Surface-Surface, 4, 8 (1989)].

Today paraffin or mineral oils are preferably used as oil components. The use of carboxylic acids and (optionally substituted) amines and fatty acid soap as corrosion inhibitors is described, for example, in German patent application DE-Al 2160100 and Dutch patent application NL-Al 74 13481. Rust protection emulsions are also known from German patent application DE-Al 39 33 137, which contain mineral oil, carboxylic acids and nonionic surfactants. de contain the type of fatty alcohol polyglycol ether. The latter, however, have no corrosion-inhibiting properties, but rather represent the emulsifier component. In Soap.Cosn.Che .Spec. May, 39 (1975) is finally reported that adducts of sulfuric acid with unsaturated triglycerides, so-called "sulfoils", have corrosion-inhibiting properties. These sulfoils, which are used together with alkylbenzene sulfonates or alkylphenol polyglycol ethers, are triglycerides whose fatty acid residues are substituted with sulfate groups.

Since metalworking agents sooner or later get into the surface waters via sewage treatment plants or even directly, high demands must be placed on their ecological compatibility. Particular attention is paid to agents that contain mineral and therefore biologically "hard" carrier oils. In this context, acetals have been proposed, for example, in EP-A20512501 as substitutes for mineral oils, but their large-scale production can only take place with considerable technical effort.

In order to detoxify and reduce the ecological problems thus created, the use of largely aromatic-free hydrocarbon fractions - now also referred to as "non-polluting oils" - is known in the field of drilling fluid for earth drilling in this special application area, whereby these largely aromatic-free hydrocarbon fractions are used as a closed oil phase. See, for example, the publications E.A. Boyd et al. "New Base Oil Used in Low Toxicity Oil Muds", Journal of Petroleum Technology, 1985, pp. 137-143 and R.B. Bennet "New Drilling Fluid Technology - Mineral Oil Mud", Journal of Petroleum Technology, 1984, pp. 975-981 and the literature cited therein. However, these oil phases, known as "non-polluting oils", are not completely harmless even when released into the environment. A reduction in the environmental problem - triggered by the liquid oil phases of the type concerned here - therefore appears to be urgently required also in the field of metal surface treatment agents.

The present invention is therefore based on the object of To create chen treatment agents with previously unknown ecological compatibility, which at the same time have good usage properties in a wide variety of fields and ensure satisfactory use, in particular also in problem areas.

In a further approach, the invention also intends to ecologically improve the further problem area of the active substance additives in metal surface treatment agents by at least predominantly and preferably consistently selecting such additives and auxiliary agents from the large range of additives and auxiliary agents known per se in the prior art , which are characterized by ecological harmlessness or at least ecological advantages.

The invention thus relates in a first embodiment to the use of at least largely water-insoluble dialkyl ethers of mono- and / or polyfunctional alcohols of natural or synthetic origin which are liquid at working temperature as an oil phase in metal surface treatment agents.

The use of the ethers as the oil phase, but also, if appropriate, their use as a quantitative or subordinate portion of the oil phase, demands that these ethers be sufficiently insoluble in water. In general, the water solubility of the ethers should be in the range of less than 1% by weight and preferably less than about 0.5% by weight.

In a further embodiment, the invention relates to compositions comprising a) at least largely water-insoluble dialkyl ethers of one and / or polyfunctional alcohols of natural and / or synthetic origin as an oil phase, b) corrosion inhibitors, c) emulsifiers

The advantages of the use of the dialkyl ethers according to the invention over formulations of the prior art based on mineral oil are, in particular, the biodegradability of the dialkyl ethers. In addition, there is no accumulation of hydrocarbons in the waste water from pro- cycles and in the environment. The disposal of used metal surface treatment agents is greatly simplified. In addition, there results an at least comparable but predominantly improved material compatibility compared to metal surface treatment agents based on mineral oils. Dialkyl ethers have been found to be an excellent oil base for metalworking agents. The invention also includes the surprising finding that the dialkyl ethers particularly effectively reduce the friction between the tool and the workpiece and ensure rapid heat dissipation.

Dialkyl ethers are used as oil bodies for the purposes of the invention. These are known substances which can be obtained according to the relevant procedures in preparative organic chemistry. Processes for their preparation, for example by condensation of fatty alcohols in the presence of p-toluenesulfonic acid, are known, for example, from Bull.Soc.Chim.France, 333 (1949), DE-Al 4039950 (Hoechst) and DE-Al 41 03 489 (Henkel) known. With regard to the prior art, reference is also made to EP-A1 0170076 (BASF), in which the use of dialkyl ethers as a carrier for heat liquids is proposed. Lubricants which contain dialkyl ethers are known from US Pat. No. 4,844,534 (Esso). According to the teaching of DE-Al 41 16406 (Henkel), dialkyl ethers can also be used as components of low-foaming cleaning agents.

Generally suitable are ethers of monofunctional and / or polyfunctional alcohols. In addition to the ethers, in particular monofunctional alcohols are also suitable here, which are derived from difunctional alcohols. The alcohols themselves are said to be ecologically compatible and, accordingly, do not have any aromatic constituents in preferred embodiments. Straight-chain and / or branched-chain, aliphatic or also corresponding unsaturated, in particular mono- and / or poly-olefinically unsaturated alcohols are the preferred ether-forming starting compounds. In addition, cycloaliphatic alcohols can also be considered as starting compounds.

The metal surface treatment agents produced according to the invention, for example cooling lubricants, generally have to be well tolerated by the skin because the machine operators often come into direct contact with the liquids. An important general requirement within the meaning of the present invention is therefore that both the underlying alcohols and the ethers themselves are not only ecologically compatible, but also that there are no other toxicological, in particular no inhalation-toxicological, hazards for the operator and user trigger.

From the broad range of suitable ethers, preferably at least in part based on pronounced oleophilic alcohols, ethers of alcohols with a straight-chain and / or branched-chain hydrocarbon structure are particularly suitable. In the context of corresponding monofunctional alcohols, corresponding compounds with at least 6 C atoms are suitable compounds, it being particularly useful to use corresponding alcohols with at least 8 C atoms in the molecule. The upper limit of the chain length is determined by the technical accessibility of the alcohols and is therefore, for example, in the range up to approximately 36, preferably approximately 20 to 24, particularly preferably 18 C atoms. The ether-forming alcohols themselves can be straight-chain or branched-chain independently of one another, they can be aliphatically saturated or also mono- and / or polyolefinically unsaturated.

Basically, ethers from alcohols of natural and / or synthetic origin are suitable. In particular, synthetic alcohols in the range of about Cg-iβ, which is of particular interest here and which can also contain unsaturated portions, are often inexpensive components of the market and can be used as starting materials for ethers in the sense of the invention.

The flash points of the ethers should preferably be at least 80 ° C., in particular at least 100 ° C. and more preferably at least 120 ° C. Accordingly, in addition to the ethers mentioned, based on monofunctional alcohols with in particular at least 8 carbon atoms, ethers of selected polyols are also suitable. Polyols suitable for ether formation are, in particular, lower diols, such as ethylene glycol and / or dipropylene glycols, but also, if appropriate, branched-chain diols with a higher oleophilic hydrocarbon radical in the molecule. The following are suitable for example oleophilic diols with hydroxyl groups in the α, position and / or longer-chain diols which have their hydroxyl groups on adjacent carbon atoms. Typical examples of the compounds of this type are the 2,2-dimethyl-1,3-propanediol (neopentyl glycol) or the saponification products of epoxidized olefins.

In addition to symmetrical dialkyl ethers which are prepared from two alcohol residues of the same chain length, non-symmetrical dialkyl ethers which can be prepared from mixtures of alcohols of different chain lengths can also be used in the sense of the present invention. For the purposes of the present invention, however, preference is given to using dialkyl ethers which have two identical alkyl radicals, i.e. symmetric dialkyl ethers. The dialkyl ethers which are particularly preferred for the purposes of the invention are di-n-octyl ether, di-2-ethylhexyl ether, di-stearyl ether and di-isostearyl ether.

Compared to comparable formulations based on mineral oils, when using the dialkyl ethers according to the present invention, there is generally no disruptive foam when the metal surface treatment agents are circulated; the painting and the seals of the machines are not attacked. It was also found that the emulsion stability is guaranteed even over a longer period of use. Residues on the machines can easily be washed off with water.

The amount of the dialkyl ethers to be used in the metal surface treatment agents depends in particular on the particular application. It is generally to be assumed here that the same amounts of dialkyl ether are to be used as of mineral oils in comparable products. The metal surface treatment agents in the sense of the present invention can be present on the one hand in the form of oil-based concentrates and on the other hand in the form of oil-in-water emulsions (0 / W emulsions). In the former case, the metal surface treatment agents consist of the oil phase - the dialkyl ethers - which generally only contain active ingredient additives that correspond to the respective application. The agents according to the invention can contain the dialkyl ethers in amounts of 1 to 95% by weight, based on the agents. In the second The dialkyl ethers form the disperse oil phase of a water-based O / W emulsion, which then also contains the corresponding active ingredient additives. For the purposes of the present invention, it is preferred that the dialkyl ethers are present in the metal surface treatment agent concentrates in amounts of 20 to 95% by weight, in particular 30 to 70% by weight, these additionally containing active ingredient additives and optionally water ¬ hold.

The preferred aqueous products are concentrates with a water content of 5 to 25% by weight, which can optionally be diluted on site by the user to an application concentration. In the forms of supply mentioned, the agents according to the invention can be used, for example, as rolling, deep-drawing or cutting oils and as grinding, honing or lapping oils. For machining operations, for example, 1 to 10, preferably 2 to 6% by weight emulsions are produced from the concentrates.

Special cooling lubricant technologies are known from the prior art for certain rolling processes (DE-Al 38 35 460, FR-B 2 101 197) and for the deep-drawing process (US Pat. No. 5,020,350), which use mixed O / W systems works without the two phases forming an emulsion. Rather, the two phases are fed separately, mechanically mixed at the point of use by a mixing system and applied to the workpiece in this mixture. The mixture running off the workpiece spontaneously separates in a short time, so that the two phases can be prepared separately and fed to the respective storage containers. The agents according to the invention also come into consideration for this special embodiment.

It is also possible to use the dialkyl ethers in the context of the invention with further suitable oil components which are known per se from the prior art. For the purposes of the invention, particularly preferred are aromatic-free aliphatic and / or cycloaliphatic hydrocarbon fractions. Reference is made to the relevant state of the art in print and the commercial products on the market. If desired, paraffin oils and also mineral oils, for example, can thus be present as a mixture component in addition to the dialkyl ethers in the oil phase. However, particularly important mixture components in the sense of the present invention are oleophilic alcohols and / or ester oils which are subject to environmental contracts. Such alcohols or ester oils should be flowable at ambient temperature, but also under conditions of use. Accordingly, preference is given to using alcohols and ester oils whose solidification values (pour point and pour point) are below 10 ° C. and expediently below 0 ° C.

For reasons of operational safety, these mixture components should also have flash points in the area of the dialkyl ethers mentioned above. Particularly important in the sense of the present invention is the biologically and ecologically compatible constitution of the alcohols and ester oils to be used, which should therefore be free of undesirably toxic constituents. Corresponding alcohols and / or ester oils are known for example from WO-A-90/14400. If it is desired to use such mixture components in addition to the dialkyl ethers to be used according to the invention in the oil phase for technical or other reasons, such mixture components can replace the dialkyl ethers up to 50% by weight, based on the oil phase.

Metal surface treatment agents in the sense of the present invention also include so-called phase inversion emulsions (PIT emulsions). These are produced by first determining the phase inversion temperature by heating a sample of the emulsion prepared in the customary manner using a conductivity measuring device and determining the temperature at which the conductivity decreases sharply. Now that the phase inversion temperature range for a particular composition of an emulsion is known, an emulsion which contains all essential components is first heated to a temperature which is within or above the phase inversion temperature range. A further possibility for production is to choose a temperature which is within or above the phase inversion temperature range already during the production of a certain emulsion. The mixture is then emulsified by vigorous stirring. The emulsion is cooled or allowed to cool to the desired temperature. Depending on the manufacturing process, milky, cloudy, coarse-grained contain persistent emulsions or optically almost transparent micro emulsions. The preparation of corresponding stable O / W rust protection emulsions is described, for example, in DE-A-3933137.

A number of metal surface treatment agents based on mineral oils are known in the prior art. For the purposes of the present invention, these are selected in particular from cleaning and corrosion protection emulsions and cooling lubricants. In the broadest sense, such agents can be used for cleaning and corrosion protection (passivation) and for cooling and lubricating when machining, grinding, honing or milling metal surfaces, but also other hard surfaces, such as painted surfaces, plastic, using the aqueous application emulsions or glass surfaces.

In order to be able to meet the requirements in practice, the metal surface treatment agents usually have to contain various active ingredient additives in addition to the dialkyl ethers. The most important active ingredient additives for the purposes of the present invention are, depending on the intended use, corrosion inhibitors, emulsifiers, biocides, EP additives, lubricant additives, anti-fog additives, anti-aging agents, solubilizers, defoamers and pH regulators.

Usual corrosion inhibitors, e.g. B. alkanolamines and their salts, sulfonates, organic boron compounds, especially boric acid esters, fatty acid amides, aminodicarboxylic acids, phosphoric acid esters, thiophosphonic acid esters, dialkyldithiophosphates, mono- and dialkylarylsulfonates, benzotriazoles, polyisobutene succinic acid derivatives are intended to prevent rusting of metal surfaces.

Also suitable as corrosion inhibitors are carboxylic acids of the formula (I). , •: ^• • - ^■ .- - ..

Ri-COOH (I)

in R ¹ for an aliphatic, linear or branched hydrocarbon radical with 5 to 23 carbon atoms and 0 or 1 to 5 double bonds or an R2-Ph-C0CH = CH group, where R2 for a linear or mixed branched alkyl radical having 8 to 18 carbon atoms and Ph represents a phenyl group.

Typical examples are the fatty acids caproic acid, caprylic acid, capric acid, isononanoic acid, lauric acid, myristic acid, pal itic acid, palmoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselinic acid, linoleic acid, linolenic acid, elaeostearic acid, arachic acid, gadole Arachidonic acid, behenic acid, erucic acid and clupanodonic acid as well as their technical mixtures, such as those that occur during the pressure splitting of natural fats and oils. Carboxylic acids of the formula (I) are preferably used in which R is alkyl radicals having 5 to 17 carbon atoms.

Examples of substituted carboxylic acids are contained in the group of alkylbenzoylacrylic acids. The use of 3- (p-dodecylbenzoyl) acrylic acid is particularly preferred.

The free acids mentioned can also be used as alkali, alkaline earth, ammonium, alkylam onium and / or zinc salts.

Anionic surfactants of the petroleum sulfonate type can be considered as a further group of corrosion inhibitors. These are sulfoxidation products of paraffin fractions with an average of 6 to 30, in particular 10 to 20, carbon atoms. The petroleum sulfonates can also be regarded as secondary alkane sulfonates, with alkali or alkaline earth metals, ammonium or alkylammonium being suitable as counterions. The petroleum sulfonates are preferably used in the form of their sodium or calcium salts.

A further group of corrosion inhibitors are sulfonation products of unsaturated fatty acid glyceride esters of the formula (II), so-called "sulfotiglycerides" or "sulfoils", CH ₂ 0-C0R ³

I.

CH-0-C0R ⁴ (II)

I

in which R ^ CO represents an unsaturated acyl radical with 16 to 24 carbon atoms and 1 to 5 double bonds and R ^ CO and R ^ CO independently of one another represent acyl radicals with 6 to 24 carbon atoms and 0 or 1 to 5 double bonds.

Sulfotriglycerides are known substances which can be obtained, for example, by adding sulfur trioxide or chlorosulfonic acid to unsaturated tri-glycerides, in particular rapeseed oil or sunflower oil. In this connection, reference is made to the applicant's published patent applications DE-Al 39 36 001 and DE-Al 41 18955, which describe the preparation and the corrosion-inhibiting and self-emulsifying properties of the sulphuryl glycerides. For the purposes of the agents according to the invention, sulfonated rapeseed oil is preferably used in the form of the sodium, calcium, ammonium or alkylammonium salt.

Dimer fatty acids can also be considered as corrosion inhibitors. The agents according to the invention can contain the corrosion inhibitors in amounts of 1 to 80, preferably 2 to 50% by weight, based on the agents. In the past, nitrite was frequently used as a corrosion protection agent, but today it is frowned upon because of its toxicity and environmental damage, especially because of the risk of carcinogenic nitrosamines being formed. Some corrosion inhibitors have emulsifying properties at the same time and are therefore also used as emulsifiers.

Emulsifiers, e.g. B. nonionic surfactants, petroleum sulfonates, alkali soaps, alkanolamine soaps stabilize the fine distribution of oil droplets in the aqueous working fluid, which is an oil-in-water emulsion. In terms of quantity, the emulsifiers represent an important group of additives for the water-miscible cooling lubricants. The metal surface treatment agents preferably contain per se in the prior art Emulsifiers known in the art, in particular those selected from a) anionic emulsifiers, in particular soaps, sulfonates and phosphoric acid esters and their salts, and b) nonionic emulsifiers, in particular fatty alcohol ethoxylates, fatty alcohol propoxylates and sugar esters. The amounts of emulsifiers used can be transferred here from the field of mineral oil-based metal surface treatment agents.

Addition products of ethylene and / or propylene oxide onto compounds with acidic hydrogen atoms or fatty acid esters are suitable as nonionic emulsifiers. These include, for example, alkoxylation products of fatty alcohols, alkylphenols, fatty acids, fatty amines, fatty acid methyl esters and sorbitan esters, which can be obtained by the known processes of the prior art.

Typical examples are addition products of an average of 1 to 20, preferably 2 to 10, moles of ethylene oxide and 0 or 1 to 5 moles of propylene oxide onto fatty alcohols with 6 to 22 carbon atoms, alkylphenols with 4 to 12 carbon atoms in the alkyl radical, and fatty acids, fatty amines and fatty acid esters with each 6 to 22 carbon atoms in the fat residue. Addition products of 2 to 10 moles of ethylene oxide with lauryl or Ci2 / 14 coconut oil alcohol (conventional or restricted homolog distribution), with octylphenol, lauric or Ci2 / 14 ~ coconut fatty acid, laurylamine, coconut fatty acid methyl ester and / or sorbitan monolaurate are particularly preferred.

Further suitable nonionic emulsifiers can be found in the group of the sugar esters and / or alkyl polyglucosides.

In particular for cooling lubricants which are used in machining, in addition to the nonionic emulsifiers mentioned, anionic surfactants such as soaps, sulfonates and alkyl phosphates are also suitable. Typical examples of this group of compounds are alkali soaps of fatty acids, naphthen soaps, alkylarylsulfonates, alkanesulfonates, alkylbenzenesulfonates, alkyl sulfates and alkyl ether sulfates. The agents according to the invention can contain the emulsifiers in amounts of 1 to 80, preferably 2 to 50% by weight. - based on funds - included. Fatty alcohols of the formula (III) are suitable as co-emulsifiers which are optional constituents of the agents according to the invention and are not suitable on their own for producing an emulsion.

R6-0H (III)

in which R6 represents alkyl and / or alkenyl radicals having 6 to 22 carbon atoms.

Typical examples are capronic alcohol, caprylic alcohol, capric alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, pal oleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, arachyl alcohol, gadoleyl alcohol and technical grade alcohol, beucyl alcohol, beucyl alcohol, behenyl alcohol, behenyl alcohol, behenyl alcohol, for example, behenyl alcohol, behenyl alcohol, behenyl alcohol, behenyl alcohol the high pressure hydrogenation of natural fatty acid methyl ester fractions or aldehydes from Roelen's oxosynthesis are obtained. The co-emulsifiers are preferably selected on the basis of the C chain length of the emulsifiers.

Further co-emulsifiers are also branched primary alcohols, so-called Guerbet alcohols, which are obtainable by base-catalyzed condensation of fatty alcohols and can have 12 to 16 carbon atoms.

In the case of ready-to-use rolling oil emulsions for the cold rolling of metal strips, where a continuous lubricating film is to be formed on the rolling stock through coalescence of the emulsion, the oil content after dilution of the concentrates is generally of the order of magnitude of less than 10, preferably 1 to 3% by weight. To optimize the lubricating effect, it is advantageous if the oil droplets in the emulsion are as large as possible (approx. 2 to 5 micrometers) and have a narrow-band size distribution. In the case of cooling lubricants for machining, on the other hand, it is particularly important that the emulsions are stable over a longer period of time. In contrast, rolling oil emulsions can also be metastable, ie they may separate over time, provided the components are easily re-emulsified and the original oil drop size is restored. All of these properties and requirements can be included in the optional influencing reversible emulsifiers, so that the selection of these active components is of particular importance.

Biocides, e.g. B. phenol derivatives, formaldehyde derivatives, Kathon MW, are intended to prevent the growth of bacteria and fungi. Lubricants are intended to prevent micro-welding between metal surfaces at high pressures and temperatures. In addition to the fatty acids known as corrosion inhibitors, fatty acid esters (“fatty oils”), synthetic esters or metal soaps can be used as lubricating additives in addition to the fatty acids known as corrosion inhibitors. For higher requirements, it is more advantageous to use so-called "EP additives". Examples of these are organic chlorine compounds, such as chlorinated paraffins, chlorinated fatty oils, sulfochlorinated fatty oils or sulfur-containing compounds, such as sulfurized fatty oils, organic mono- and disulfides or sulfurized polybutenes, and phosphorus-containing compounds of the phosphoric acid ester or dialkyldithiophosphate type. The agents according to the invention can contain the lubricants in amounts of 1 to 80, preferably 2 to 50% by weight, based on the agents.

Anti-aging substances, e.g. B. organic sulfides, zinc dithiophosphates, aromatic amines, ensure a long service life of the metal surface treatment agent. Anti-fog additives prevent fogging of the metal surface treatment agents when they are used, for example atactic polypropylene, polyisobutene, poly-n-butene, polymethacrylate and in particular clear water-soluble polymer compounds (MW> 10 ^) based on polyalkylene oxides, polyacrylamides, polymethacrylamides and copolymers of acrylamide and / or Methacrylamide and unsaturated carboxylic acids with 3 to 5 carbon atoms (DE-A-42 17859). The substances usually used in such products can be used as defoamers, for example nonionic surfactants, in particular end group-capped fatty alcohol polyethylene glycol ethers.

The constancy of pH of the metal surface treatment agents is of major importance with regard to the emulsion stability and the corrosion protection. Usually it is not necessary to adjust the pH value of the metal surface treatment agents specifically. Preferred- However, in order to ensure adequate protection against corrosion, the pH is adjusted in the range from neutral to alkaline. Particularly preferred in the sense of the present invention is the adjustment of the pH in the range from 7 to 11, in particular pH 8 to 9.5. The pH can be set, for example, by alkali metal hydroxide. The use of magnesium or calcium hydroxide is less preferred since poorly soluble salts could possibly be formed. Accordingly, the use of potassium and / or sodium hydroxide is particularly preferred for the purposes of the present invention.

Alkanolamines and alkanolamine derivatives can also be used as corrosion inhibitors. In addition, in conjunction with carboxylic acids, their good buffer capacity guarantees that the aqueous application emulsions have a constant pH. Furthermore, reaction products of alkanolamines with boric acid inhibit growth on bacteria and mold and therefore improve the service life of cooling lubricants. A serious disadvantage of the alkanolamines and alkanolamine derivatives is that they are used in practice with nitrosating substances, e.g. B. bacterially formed nitrite or nitrogen oxides in the air, can react and be converted into nitrosamines. For example, nitrosodiethanolamine (NDELA) can be formed in water-mixed cooling lubricants that contain ethanolamines. According to animal experiments, nitrosamines can trigger cancer in various organs (e.g. stomach, lungs, bladder, liver, esophagus). Therefore some nitrosamines, e.g. B. also NDELA, classified in the German Hazardous Substances Ordinance as carcinogenic. To avoid health hazards for the operators of metalworking machines, the formation of nitrosamines must therefore be avoided. Despite the excellent application properties of the alkanolamines, it is preferred according to the invention for the above reasons that the metal surface treatment agents do not contain alkanolamines, i.e. are free of amines. In general, however, alkanolamines and alkanolamine derivatives as active ingredient additives are entirely within the scope of the present invention.

To achieve homogeneous solutions or stable emulsions, solubilizers or "stabilizers" are occasionally required. Typical examples of these are C 1 -C 4 alcohols, glycols or glycol ethers. The inventive The solubilizers can contain large compositions in amounts of 1 to 50, preferably 2 to 25% by weight, based on the composition.

The amounts used for all of the abovementioned constituents are known to the person skilled in the art from the mineral oil-based metal surface treatment agent and require no further explanation.

The metal surface treatment agents obtainable according to the present invention can be used both in the form of the concentrates and in the form diluted with water. However, they are usually used in the form of water-diluted O / W emulsions. Both the concentrates and the emulsions diluted with water ensure very good corrosion protection for metal surfaces made of iron and steel.

In such O / W emulsions diluted with water, the concentration of the metal surface treatment agents (concentrates) is preferably in the range from 1 to 10% by weight, in particular in the range from 2 to 6% by weight (use concentration). The oil content of the ready-to-use emulsions is then preferably in a range between 1 and 3% by weight.

The composition of the agents is to be adapted to the respective intended use, for example as a cooling lubricant for metal cutting, as a rolling emulsion for cold rolling metal strips or as cleaning and / or corrosion protection emulsions.

Mixtures which are suitable, for example, as agents for the preparation of cooling lubricant or roller emulsions by mixing with water are:

20-95% by weight dialkyl ether

1-80% by weight of emulsifiers

1 - 80 wt .-% corrosion inhibitors

0 - 80% by weight of lubricants

0 - 50 wt .-% solubilizer

contain. Such agents preferably contain

30-70% by weight dialkyl ether 2-50% by weight emulsifiers 2-50% by weight corrosion inhibitors 0-50% by weight lubricants 0-25% by weight solubilizers.

Means are suitable for the preparation of corrosion protection emulsions

10-95% by weight dialkyl ether

2-15% by weight of emulsifiers

2 - 25 wt .-% corrosion inhibitors

0 - 15 wt .-% co-emulsifiers

0 - 86 wt% water

contain.

Examples

In the examples below, the abbreviation "EO" means ethylene oxide units.

example 1

Production of an amine-free anti-corrosion emulsion

Propylene glycol, tall oil fatty acid and water were placed in the reactor and stirred. The solid potassium hydroxide cookies were then sprinkled in (exothermic reaction) and stirred for about 30 min. The temperature of the solution was kept between 50 and 70 ° C. The remaining components (dioctyl ether, fatty alcohol ethoxylates, petroleum sulfonate and caprylic acid) were then metered in in the order mentioned above. The mixture was stirred for about 1 h until a clear brown solution was present.

Comparative Example 1

Analogously to Example 1, a corresponding corrosion protection emulsion based on mineral oil was prepared using 54.6% by weight mineral oil (Shell Gravex R 915) instead of the dioctyl ether. In game 2

Under the use of

Dioctyl ether 51.8% by weight,

Petroleum sulfonate 4% by weight,

Tall oil fatty acid 12% by weight,

Propylene glycol 4% by weight,

Caprylic acid 5% by weight,

Fatty alcohol ethoxylate (oleyl cetyl alcohol-2E0) 11% by weight,

Fatty alcohol ethoxylate (oleyl cetyl alcohol-5E0) 2% by weight, and

Monoethanolamine / triethanolamine 10.2% by weight

(Weight ratio 1: 1)

an anti-corrosion emulsion containing amine was produced.

Propylene glycol and tall oil fatty acid were placed in the reactor and stirred. The remaining components (dioctyl ether, fatty alcohol ethoxylates, petroleum sulfonate, caprylic acid and monoethanolamine / triethanolamine) were then metered in in the order mentioned (exothermic reaction). The mixture was stirred at 40 to 50 ° C for 1 h until a clear brown solution was present.

Comparative Example 2

Analogously to Example 2, a corresponding corrosion protection emulsion containing mineral oil was prepared using 51.8% by weight of mineral oil (Shell Gravex ^R 915) instead of the dioctyl ether.

Behavior against sealing materials:

Experiments with dilute aqueous O / W emulsions (5% by weight) of Examples 1 and 2 and Comparative Examples 1 and 2 based on dioctyl ether or mineral oil were carried out on various types of nitrile butadiene rubber different acrylonitrile content (Perbunan ^R -N commercial products, Bayer AG) carried out in the storage test at 50 ° C (test duration 26 days). It was found that, after visual inspection, amine-free products generally attack the seals less than products which contain mono- and triethanolamine. Compared to mineral oil, dioctyl ether shows at least a comparable, but mostly a better material compatibility.

Corrosion protection test:

According to DIN 51360/2, the corrosion protection effect of aqueous emulsions according to Examples 1 and 2 and Comparative Examples 1 and 2 was tested by wetting castings on filter paper with the emulsion. After 2 hours, the corrosion marks on the filter paper were evaluated in accordance with a comparison scale, with "degree of corrosion 0" meaning that no corrosion was observed, but "degree of corrosion 6" that very strong corrosion was observed. The application concentrations can be found in Table 1 and vary from 2 to 5% by weight.

Table 1 below shows the pH of the respective emulsions and the degree of corrosion on a graduated scale in the range from 0 to 6.

Table 1

Example Con ce n t r a t i o n

(K.Grad = degree of corrosion) In particular, the emulsion according to Example 2 shows a better corrosion behavior than the Comparative Examples 1 and 2 at a low concentration.

Examples 3 to 6. Comparative Example 3:

The surface pressure of dialkyl ethers and mineral oils was investigated using the friction wear balance according to Reichert (Summer and Runge, Berlin). The specific surface pressure (expressed in bar or% -rel to the standard) at which the lubricating effect breaks down was measured. In this connection, a high value of the specific surface pressure means a good lubricating effect of the liquids.

Substances used:

I: Di-n-octyl ether

II: Di-2-ethylhexyl ether

III: Di-stearyl ether

IV: Di-isostearyl ether

Diesel oil was used as the standard, corresponding to 100% rel. The results are summarized in Table 2.

Tab. 2: Specific surface pressure (SFP)

Examples 7 to 9. Comparative Examples 4 and 5:

Water-miscible cooling lubricant concentrates (for the composition see Table 2) were produced. For this, 1/3 of the intended amount of oil was placed in a kettle together with tall oil fatty acid and a solubilizer and stirred. If specified, salicylic acid was then metered in. Aqueous potassium hydroxide solution was then added to the mixture with constant stirring at such a rate that the temperature was between 50 and 70 ° C. The mixture was then stirred for a further 60 min until a clear solution was obtained. The remaining amount of the oil body and the remaining constituents of the formulation were then added and stirring was continued for a further 60 min.

Tab. 3: Composition of cooling lubricant concentrates Percentage as% by weight

Contin. Tab. 3: Composition of cooling lubricant concentrates Percentage as% by weight

The performance of the cooling lubricant concentrates was tested on the basis of their corrosion-inhibiting effect in accordance with DIN 51 360, part 2, by wetting castings on filter paper with the emulsions. After 2 hours, the rust formation was assessed according to the comparison scale in accordance with DIN 51 360, part 2. Corrosion grade 0 means no corrosion. Table 4 shows the minimum concentration of cooling lubricant concentrates that is required to achieve degree of corrosion 0.

Tab. 4: Corrosion-inhibiting effect

Example 10. Comparative Example 6:

A rolling or cutting oil of the following composition was produced by stirring the components:

Base oil 50% by weight?

Ciö / ig fatty acid TMP ester 30% by weight? Sulphurized sperm oil 12% by weight? Sulfurized diisobutene 5% by weight? Zinc diethyl dithiophosphate 3% by weight?

Di-n-octyl ether (Example 10) or a naphthenic mineral oil (Pionier ( ^R ) 4556, Hansen and Rosenthal, HaBurg / FRG, cf. 6) was used as the base oil. The lubrication effect was checked in accordance with ASTM D 2625-83, method B, using the Falex Pin and Vee Block method. The load and the moment or break of the pin are then determined. The standardized FP&VB test machine was used, initially setting a load of 2224 N, reading the moment and reading again after 5 minutes. From the next load level (see Table 5), the load was changed and the moment was recorded immediately and after 1 minute.

Tab. 5: Lubrication effect according to the FP & VB method

More examples of corrosion protection emulsions

I. List of substances used

Oil body: di-n-octyl ether

Inhibitors: PSNa (Petronate CR)

Cis / iβ-petroleum sulfonate sodium salt,

62% by weight solution in mineral oil, Witco;

: PSCa (Ca-Petronate HMW) Ciö / ß-petroleum sulfonate calcium salt, 45 wt .-% solution in mineral oil, Witco;

: SRNa Sulforüböl sodium salt, 45 wt .-% aqueous solution;

: SROa » ^■ >

Sulforüböl octyla salt, anhydrous

: SRSa Sulforüböl stearylamine salt, anhydrous

Emulsifier: lauryl alcohol-IOEO

Co-emuloator: lauryl alcohol

The formulations of Examples 11 to 16 each contained

80 to 87% by weight dialkyl ether; 8 to 15% by weight corrosion inhibitor; 4% by weight emulsifier 1% by weight co-emulsifier and were used either anhydrous (100% by weight) or in the form of a 20% by weight aqueous dispersion.

II. Description of the condensation water climate test

In the condensation water climate test, the condensation of the air humidity on sample surfaces, the temperatures of which, due to radiation onto the walls of the test chamber, are lower than those of the saturated test room air, is used to assess corrosion phenomena. The test was carried out in accordance with DIN 50017-KTW under the following conditions:

Temperature: ax. 40 ° C

Test cycle length: 8 h at 40 ° C (door closed)

: 16 h room temperature (door open) Sample material: body steel sheets ST 1405,

Dimensions 10 x 5 cm

The test panels were first degreased with acetone and then immersed in the test formulations. After a draining time of 24 hours, the sheets were weathered in a climatic chamber for 1 to 25 test cycles. After each test cycle, the degree of corrosion (KG) was assessed optically according to the following scheme:

KG = 0: no corrosion

KG = 1: up to 1% corrosion

KG = 2: up to 5% corrosion

KG = 3: up to 25% corrosion

KG = 4:> 25% corrosion

The results of the tests in the climatic chamber are summarized in Table 6. The column "Degree of corrosion after test cycles" shows the number of test cycles for the agents according to the invention (Examples 11 to 16) and for the comparative tests (V7, V8), after which the corresponding degree of corrosion was established. Tab. 6: Corrosion tests; Percentages as wt.

Legend: I = inhibitor c (I) = concentration of the inhibitor on average c (Ö) = concentration of the oil body on average

Conc. = Concentration of the agent

V7 was carried out without anti-corrosion agents; for V8, di-n-octyl ether was exchanged for Pioneer white oil in the recipe from Example 11.

Claims

Patent claims

1. Use of at least largely water-insoluble, at working temperature liquid dialkyl ethers of mono- and / or polyfunctional alcohols of natural and / or synthetic origin as an oil phase in metal surface treatment agents.

2. Use according to claim 1, characterized in that the dialkyl ethers have 6 to 24 carbon atoms per alkyl radical, preferably 8 to 18 carbon atoms, the alkyl radicals being independently of one another straight-chain or branched-chain, saturated or unsaturated.

3. Use according to claim 1 or 2, characterized in that the dialkyl ethers have two identical alkyl radicals, preferably two n-octyl, 2-ethylhexyl, stearyl or isostearyl radicals.

4. Use according to one or more of claims 1 to 3, characterized in that the metal surface treatment agents are present as oil-based concentrates or as water-based O / W emulsions.

5. Use according to one or more of claims 1 to 4, characterized in that the dialkyl ethers in the concentrates in amounts of 1 to 95 wt .-%, preferably 20 to 95 wt .-%, in particular from 30 to 70 wt .-% %, are present in the metal surface treatment agents, these additionally containing active ingredient additives and optionally water.

6. Use according to one or more of claims 1 to 5, characterized in that the metal surface treatment agents are selected from cleaning and corrosion protection emulsions and cooling lubricants.

7. Use according to one or more of claims 1 to 6, characterized in that the active ingredient additives contained in the metal surface treatment agents are selected from emulsifiers, corro- sion inhibitors, biocides, solubilizers, lubricant additives, EP additives, anti-aging agents, anti-fog additives, defoamers and pH regulators.

8. Use according to one or more of claims 1 to 7, characterized in that the metal surface treatment agents are used in the form of water-diluted O / W emulsions.

9. Use according to claim 8, characterized in that the Metall¬ surface treatment agents have a pH in the range from 7 to 11, in particular from 8 to 9.5.

10. Use according to one or both of claims 8 and 9, characterized in that the concentration of the metal surface treatment agent in the water-diluted O / W emulsions is in the range from 1 to 10% by weight, preferably of 2 to 6% by weight.

11. Use according to claim 10, characterized in that the oil content of the O / W emulsions is 1 to 3 wt .-%.

12. Use according to one or more of claims 1 to 11 for the shaping cutting and / or non-cutting metal processing.

13. Use according to, one or more of claims 8 to 11 in the cold rolling of metal strips, characterized in that the oil droplets of the O / W emulsion have an average diameter between 2 and 5 μm.

14. A composition comprising a) at least largely water-insoluble dialkyl ethers which are liquid at working temperature and / or polyfunctional alcohols of natural and / or synthetic origin as an oil phase, b) corrosion inhibitors, c) emulsifiers

15. Composition according to claim 14, characterized in that the dialkyl ether 6 to 24 carbon atoms per alkyl radical, preferably 8 to 18 carbon atoms, the alkyl radicals being independently of one another straight-chain or branched-chain, saturated or unsaturated.

16. Composition according to claim 15, characterized in that the dialkyl ethers have two identical alkyl radicals, preferably two n-octyl, 2-ethylhexyl, stearyl or isostearyl radicals.

17. Composition according to one or more of claims 14 to 16, characterized in that they contain carboxylic acids of the formula (I) as corrosion inhibitors,

Ri-COOH (I)

in the R * for an aliphatic, linear or branched hydrocarbon radical with 5 to 23 carbon atoms and 0 or 1 to 5 double bonds or an R2-Ph-C0CH = CH group, where R ² for a linear or branched alkyl radical having 8 to 18 carbon atoms and Ph represents a phenyl group.

18. Composition according to one or more claims 14 to 17, characterized gekenn¬ characterized in that they contain petroleum sulfonates as corrosion inhibitors.

19. Composition according to one or more of claims 14 to 18, characterized in that they contain sulfonation products of unsaturated fatty acid glyceride esters of the formula (II) as corrosion inhibitors,

in the R ^ CO for an unsaturated acyl radical with 16 to 24 carbon atoms and 1 to 5 double bonds and R cθ and R C0 independently of one another for acyl radicals with 6 to 24 carbon atoms and 0 or 1 up to 5 double bonds.

20. Composition according to one or more claims 14 to 19, characterized gekenn¬ characterized in that they are addition products of ethylene and / or propylene oxide to compounds having acidic hydrogen atoms or fatty acid esters, preferably addition products of ethylene and / or propylene oxide to fatty alcohols, alkyphenols as emulsifiers , Fatty acids, fatty amines, fatty acid methyl esters and / or sorbitan esters.

21. Composition according to one or more claims 14 to 20, characterized gekenn¬ characterized in that they contain anionic surfactants, preferably soaps, alkylarylsulfonates, alkanesulfonates, alkylbenzenesulfonates, alkyl sulfates, alkyl ether sulfates and / or alkyl phosphates as emulsifiers.

22. Composition according to one or more of claims 14 to 21, characterized in that they additionally contain co-emulsifiers, preferably fatty alcohols of the general formula (III),

R ⁶ -0H (III)

in which Rδ represents alkyl and / or alkenyl radicals having 6 to 22 carbon atoms.

23. Composition according to one or more claims 14 to 22, characterized gekenn¬ characterized in that they contain solubilizers, preferably C _j - C4 alcohols, glycols or glycol ethers.

24. Composition according to one or more of claims to 23, characterized in that they

20-95% by weight dialkyl ether

1-80% by weight of emulsifiers

1 - 80 wt .-% corrosion inhibitors

0 - 80% by weight of lubricants

0 - 50 wt .-% solubilizer

contain.

25. Composition according to claim 24, characterized in that it

30-70% by weight dialkyl ether

2 - 50 wt .-% emulsifiers

2 - 50 wt .-% corrosion inhibitors

0 - 50% by weight of lubricants

0 - 25 wt .-% solubilizers

contain.

26. Composition according to one or more of claims 14 to 23, characterized in that it

10-95% by weight dialkyl ether 2-15% by weight emulsifiers 2-15% by weight corrosion inhibitors 0-15% by weight co-emulsifiers 0-86% by weight water

contain.