DE4229848A1 - Amine-free cooling lubricants - Google Patents

Abstract

Amine-free cooling lubricants contain as essential component sets of anticorrosive substances, besides the usual base oils, emulsifiers and solubilizers. These sets of anticorrosive substances consist of a mixture of dimeric fatty acids and one or several carboxylic acids. The latter are selected among the apliphatic and aromatic carboxylic acids. Alkali metal, magnesium and/or calcium salts of said acids may be used in a similar manner. These amine-free cooling lubricants have an anticorrosive effect comparable to that of alkanolamine-containing cooling lubricants.

Description

The invention relates to amine-free cooling lubricants for the Metalworking, containing base oils, emulsifiers, solution ver medium and anti-corrosion additives.

Cooling lubricants are preparations / mixtures that are used in the metal machining and metal forming for cooling and lubricating the Workpieces are used. The main machining processes, which is characterized by the type of movements that the machined part and Execute tool, and by the geometry of the Differentiating parts is called milling, turning, drilling and Grinding as machining operations as well as rolling, deep drawing and cold extrusion as non-cutting deformations.

The common principle of metal machining drive is that the cutting edge engages in the material and thereby lifting a chip off the surface and a new surface arises. Very high pressures are required to break up the material required. By the deformation of the chip and by the opening Friction under pressure creates heat that the workpiece, the tool and especially the chips heats up.

The desired effect of using cooling lubricants is hence the lowering of the temperature that would otherwise occur in the chips z. B. could rise to 1000 ° C, and that in the Tei len influences the dimensional accuracy. Another main task of the cooling lubricants, the service life of the tools is too  improve that quickly ver under the influence of high temperature wear out. By using a cooling lubricant, the Roughness of the surfaces is reduced because the lubricant Ver prevents welding of tool and workpiece surface and prevents particles from sticking. In addition, the Cooling lubricant the task of removing the chips formed animals. This is particularly important for mass production.

Cooling lubricants are usually circulated sets, d. H. in the simplest case, the use of cooling lubricant fabric on a single machine, the machine has a container for the cooling lubricant.

With the new version of DIN 51 385 No. 1, a clear description naming of the cooling lubricants created, with non-water miscible, water-miscible and water-mixed cooling lubricant stuff is talked about. According to DIN 51 385, the terms "water mixed" the final state of the finished medium (mostly as Oil-in-water emulsions), but under "water-miscible" the condition of the concentrate understood.

Water-mixed cooling lubricants are manufactured by the user by mixing a concentrate, the water-miscible cooling lubricant substance, with process water. As a rule, about 5% aqueous Emulsions. The advantage of this type of coolant is good cooling effect, based on the thermal properties of the water is based. Due to the good cooling effect, it is possible to have very high Ar to achieve working speeds and thus the productivity of Increase machines. The lubricating effect of the water-mixed Cooling lubricants are sufficient for most machining processes machining production. Another advantage is that low cost due to the possible mixture of the concentrate  can be achieved with water. Disadvantage of water-mixed cooling Lubricant is that it prevents infestation by microorganisms are sensitive and therefore require more control and care. The Presence of water can and may lead to rust formation attack sensitive metals. Water-mixed cooling lubricants are used today for almost all types of machining. In addition to the Demand for rust protection for machines and machined Parts made of iron alloys are required to include non-ferrous metals talle not be attacked. The cooling lubricants must be good be skin-friendly, as the operators of the machines are often in di come into direct contact with the liquid. It is allowed with the Umwäl cooling lubricant no annoying foam, and the painting and the seals of the machine must not be touched be gripped. Emulsion stability is particularly important, the influence on almost all other properties of cooling lubricants material, at least after a long period of use. Continue is required that residues of the cooling lubricant on the Do not glue the machine so that the cooling lubricants easily stick with it Let water mix so that smell and appearance are pleasant and that the usual filter devices through the cooling lubricant not be affected.

The table shows a summary of the requirements for what miscible and water-mixed cooling lubricants:

• - Cooling and lubricating effects
• - rust protection
• - no attack on non-ferrous metals
• - Toxicological harmlessness, especially skin tolerance
• - no foaming
• - no attack on paints and seals
• - emulsion stability  
• - no sticking or resinification
• - good miscibility
• - pleasant smell
• - clean appearance
• - good filterability
• - easy disposal.

The requirements for the rust protection effect of cooling lubricants are particularly high because after machining with cooling lubricants drying is generally not possible. The parts become norma Usually put wet in boxes and should also be wet don't rust. To check the rust protection effect at Development and also in the control of in practical use solutions are often the test with castings according to DIN 51 360/2 used.

The rust protection effect of the cooling lubricants is influenced by a number of factors. So the quality of the mix used water a great influence. The water hardness, especially al However, things such as chlorides and sulfates worsen rust protective effect of the solution. This is made more difficult by prolonged use of cooling lubricants that the concentration of salts constantly increases as parts of the emulsion evaporate and the losses topped up with saline water.

Non-water-miscible and water-miscible cooling lubricants, as far as when in use, emulsions are often on mineral oil built up. The mineral oil qualities used are predominant Combinations of paraffinic, naphthenic and aromatic Hydrocarbon compounds. In addition to the mineral oils, too so-called synthetic lubricants ("synthetic oils") such as  Polyolefins, polyalkylene glycols and glycol ethers, natural Ester oils as well as synthetic esters and their derivatives meaning.

To be able to meet the requirements of practice, the water-miscible cooling lubricants in addition to the base oil various Components included. The most important groups of substances are Emulsifiers, anti-corrosion additives, biocides, EP additives, polar Additives, anti-fog additives, anti-aging agents, solid lubricants sets and defoamers.

Emulsifiers (e.g. surfactants, petroleum sulfonates, alkali soaps, Al kanolamine soaps) stabilize the fine distribution of oil droplets in the aqueous working fluid, which is an oil-in-water emulsion represents. The emulsifiers represent an important group in terms of quantity of additives in the water-miscible cooling lubricants.

Common anti-corrosion additives (e.g. alkanolamines and their salts, Sulfonates, organic boron compounds, fatty acid amides, aminodicar bonic acids, phosphoric acid esters, thiophosphonic acid esters, dialkyldi thiophosphates, mono- and dialkylarylsulfonates, benzotriazoles, Polyisobutene succinic acid derivatives) are said to rust metal prevent surfaces. Previously used as an anti-corrosion agent commonly used nitrite, but today because of toxicity and Harmful to the environment, especially because of the danger of education carcinogenic nitrosamines is frowned upon. Some corrosion protection sentences have emulsifying properties and find at the same time therefore its use as an emulsifier. Biocides (e.g. phenolic Derivatives, formaldehyde derivatives, Kathon MW) are said to support growth prevent bacteria and fungi. EP additives (e.g. sulfurized Fats and oils, phosphorus-containing compounds, organochlorine ver bonds) are said to be micro-welds between metal surfaces prevent at high pressures and temperatures. Polar additives  (e.g. natural fats and oils, synthetic esters) increase the Lubrication properties. Anti-aging substances (e.g. organic Sulfides, zinc dithiophosphates, aromatic amines) ensure a long service life of cooling lubricants.

The alkanolamines occupy a central position among the additives and alkanolamine derivatives included in a large number of water miscible cooling lubricants used as corrosion protection additives become. They also guarantee in combination with carboxylic acids due to its good buffer capacity, a certain pH constant aqueous use emulsions. The pH-value is important A special one in terms of emulsion stability and rust protection Meaning too. Reaction products of alkanolamines with boric acid have a growth-inhibiting effect on bacteria and mold and ver therefore improve the service life of cooling lubricants.

A disadvantage of the alkanolamines and alkanolamine derivatives is that they during practical use with nitrosating substances, e.g. B. bacterial nitrite or nitrogen oxides in the air, react ren and can be converted into nitrosamines. For example, can in water-mixed cooling lubricants that contain ethanolamines, Nitrosodiethanolamine (NDELA) are formed.

Animal studies have shown that nitrosamines can cause cancer at various sites trigger gans (e.g. stomach, lungs, bladder, liver, esophagus). Therefore some nitrosamines, e.g. B. also NDELA, in German Hazardous substances regulation classified as carcinogenic. To avoid of health hazards for metalworking operators machine must therefore avoid the formation of nitrosamines become.

The object of the present invention is to provide amine-free cooling lubricants, but which are related to the Rust protection effect in the stability and duration of use as well whose properties of use are the usual amine Cooling lubricants are not inferior.

The above-mentioned object is achieved by amine-free cooling lubricants containing base oils, emulsifiers, solubilizers and Corrosion protection additives, characterized in that as corrosion sion protection additive a mixture of

• a) Dimer fatty acids and
• b) one or more carboxylic acids selected from aliphatic Carboxylic acids with 6 to 14 carbon atoms and aromatic Monocarboxylic acids or the alkali metal, magnesium and / or calcium salts below a) and / or b) acids mentioned.

Surprisingly, it was found that the combination of dimer fatty acid and other carboxylic acids selected from aliphatic and aromatic carboxylic acids or their alkali metal, magnesium and / or calcium salts, is suitable, cooling lubricants available to provide the ge in relation to the corrosion protection effect compared to commercially available cooling lubricants based on Alkanolamines have comparable corrosion protection effects.

The selection of the base oils according to the invention in the cooling lubricants are practically unlimited. So contain emul Sions within the meaning of the present invention often components that are selected from paraffinic, naphthenic and paraffi naphthenic mineral oils. In the same way is the use of ester oils, e.g. B. trimethylolpropane esters, neopentyl or Pentaerythritol esters, of fatty oil derivatives, polyisobutylenes,  hydrogenated polydecenes, polypropylene glycol, silicate esters, coals acid esters, esters of acids containing phosphorus, chain-like Diphenyl ethers and phenoxyphenyl ethers are preferred.

The cooling lubricants according to the invention contain themselves in the state Emulsifiers known in the art, in particular those which are are selected from a) anionic emulsifiers, in particular soaps, Sulfonates and phosphoric acid esters and their salts and b) not ionic emulsifiers, especially fatty alcohol ethoxylates, fat alcohol propoxylates and sugar esters.

Coolants in the sense of the present invention contain in addition to base oils, emulsifiers and the corrosion according to the invention protection additives also solubilizers. In the sense of the present Er water can also be regarded as a solubilizer. Dement speaking are in a preferred embodiment of the present the invention the solubilizers selected from water, alcohols, Glycols and glycol ethers. In a particularly preferred manner the solubilizers in an amount of 1 to 30 wt .-%, in particular 2 to 10% by weight, based on the water-miscible cooling lubricant, used.

Cooling lubricants in the sense of the present invention contain as essential ingredient one or more carboxylic acids that are made up of are selected from aliphatic carboxylic acids and aromatic Carboxylic acids. Aliphatic carboxylic acids are particularly preferred selected from adipic acid, caprylic acid, sebacic acid, 2,2,4- Trimethylhexanoic acid and ethylhexanoic acid. Are in the same way particularly preferred aromatic carboxylic acids selected from Ben zoic acid, substituted benzoic acids and especially salicylic acid. Possible substituents for benzoic acid can be a hydroxy group, a nitro group, and straight-chain or branched alkyl  or alkyloxy groups with up to 4 carbon atoms. Short chain carbon Acids are components of water-soluble corrosion protection well known, e.g. B. from DE 32 23 940, but not as a compo emulsions in the combination according to the invention with Dimer fatty acids, emulsifiers, base oils etc.

Another essential component of the cooling according to the invention Lubricants are dimer fatty acids, which are preferably in one Amount of 2 to 20 wt .-%, in particular 5 to 15 wt .-%, based on the water-miscible cooling lubricants may be included. Usually one understands dimer fatty acids by alumina catalyzed dimerization of unsaturated fatty acids Mixtures of acyclic and cyclic dicarboxylic acids with through 36 C atoms on average (literature reference: Dimer Acids, E. C. Leonard, 1975, Humeo Sheffield). By-products of dimerization are branched C-18 fatty acids and trimer fatty acids or poly Hasic fatty acids, which are often separated by distillation. in the However, dimer fatty acids are also within the meaning of the present invention can be used as minor components monomeric acid, trimer fatty acid and contain polymeric fatty acid. Z can be used well. B. Empol® 1022, from Emery, USA or Pripol® 1040 or Pripol® 1013 from Fa. Unichema, Emmerich.

The dicarboxylic acids used according to the invention differ in structure substantially from the Di mentioned in WO 90/15663 carboxylic acids or dicarboxylic acid anhydrides, which by reaction of Olefins with unsaturated carboxylic acids or their anhydrides be put.

The water-miscible or water-mixed cooling according to the invention Lubricants can contain other functional additives such as polar Additives, EP additives, anti-fog additives, anti-aging substances,  Contain solid lubricants, pigments, defoamers and / or biocides For use in metalworking, the aqueous Emulsions or aqueous solutions of the cooling according to the invention lubricants preferably 1 to 10% by weight, in particular 2 to 5 % By weight of the water-miscible concentrate.

The pH of the cooling lubricants is usually in the range of set about 7 to 10. A setting is particularly preferred of the pH range from 8 to 9.5. In the sense of the present Er In addition, it is particularly preferred, alkaline Adjust pH using alkali metal hydroxide. The usage of magnesium or calcium hydroxide is less preferred because possible Certainly poorly soluble salts could be formed. Dement speaking is the use of potassium and / or sodium hydroxide in Particularly preferred for the purposes of the present invention.

Examples

1/3 of the required amount of mineral oil, solubilizer and tall oil fatty acid were placed in the reactor and stirred. Subsequently the aromatic carboxylic acid (only in Examples 1 and 3) added and stirred for about 15 minutes.

With constant stirring, the aqueous potassium hydroxide solution in carefully metered in within 30 minutes (exothermic reaction). The temperature of the solution was kept between 50-70 ° C. The mixture was stirred vigorously for 1 hour until a clear brown Solution was available. After that, the remaining amount (2/3) of mineral oil admitted.

The remaining components:
Petroleum sulfonate (only in formulation example 1), dimer fatty acid, caprylic acid (only in formulation examples 1 and 2) and the fatty alcohol ethoxylates were then metered in in the above order. The mixture was stirred for about 1 hour until a brown, clear solution was obtained.

Tables 1 and 2 below give the invention (Table 1) and not inventive (Table 2) recipe examples of Coolants again.  

Table 1

Table 2

Preparation of Comparative Example 1

Condensed water and diethanolamine were presented and boric acid under Stirred redeemed. After that, the mineral oil and all others Components in the order specified in Table 2 added and stirred until a clear homogeneous concentrate ent was standing.

Preparation of Comparative Example 2

Mixing was carried out in the order given in Table 2 and stirred until a clear, homogeneous concentrate was formed.

The following Table 3 gives a comparison of the invention formulations with the examples not according to the invention regarding corrosion protection effect (test according to DIN 51 360/2) like the.

Table 3

According to DIN 51 360/2, the corrosion protection effect of water Mixed coolants checked by casting chips on filters paper are wetted with the cooling lubricant. After two hours the corrosion marks on the filter paper are assessed according to a comparison scale, with degree of corrosion 0 meaning that no corrosion was observed.

For the examples, the minimum concentration was given, the is required to achieve degree of corrosion 0.

Claims (13)

1. Amine-free cooling lubricants containing base oil, emulsifiers and solubilizers, characterized in that a mixture of corrosion protection additive

• a) Dimer fatty acids and
• b) one or more carboxylic acids selected from aliphatic carboxylic acids having 6 to 14 carbon atoms and aromatic monocarboxylic acids or the alkali metal, magnesium and / or calcium salts of the acids mentioned under a) and / or b) is contained.

2. Cooling lubricants according to claim 1, characterized in that the base oil is selected from paraffinic, naphthenic or paraffinic-naphthenic mineral oils, ester oils, e.g. B. Trimethylolpropane esters, neopentyl or pentaerythritol esters, from fatty oil derivatives, polyisobutylenes, hydrogenated polydecenes, Polypropylene glycol, silicate esters, carbonic acid esters, esters Phosphorous acids, chain-like diphenyl ethers and Phenoxyphenyl ethers. 3. Cooling lubricants according to claim 1 or 2, characterized in that the emulsifiers are selected from

• a) anionic emulsifiers, especially soaps, sulfonates, phosphoric esters and their salts and
• b) nonionic emulsifiers, especially fatty alcohol ethoxylates, fatty alcohol propoxylates and sugar esters.

4. Cooling lubricants according to one or more of claims 1 to 3, characterized in that the solubilizers selected are made of water, alcohols, glycols and / or glycol ethers. 5. Cooling lubricants according to claim 4, characterized in that the amounts of solubilizer 1 to 30% by weight, in particular 2 up to 10% by weight, based on the water-miscible cooling lubricant, be. 6. Cooling lubricants according to one or more of claims 1 to 5, characterized in that the amount of dimer fatty acids 2nd to 20 wt .-%, in particular 5 to 15 wt .-%, based on the water-miscible cooling lubricants. 7. Cooling lubricants according to one or more of claims 1 to 6, characterized in that the aliphatic carboxylic acids are selected from adipic acid, caprylic acid, sebacic acid, 2,2,4-trimethylhexanoic acid and ethylhexanoic acid. 8. Cooling lubricants according to one or more of claims 1 to 6, characterized in that the aromatic carboxylic acids are selected from benzoic acid, substituted benzoic acids, where the substituents can be a hydroxy group, a Nitro group or straight-chain or branched alkyl or Alkyloxy groups, and especially salicylic acid. 9. Cooling lubricants according to one or more of claims 1 to 8, characterized in that the amount of aliphatic and / or aromatic carboxylic acids 1 to 20 wt .-%, in particular 3 to 10% by weight, based on the cooling lubricant gene.   10. Cooling lubricants according to one or more of claims 1 to 9, also containing polar additives, EP additives, anti-fog additives, anti-aging agents, solid lubricants, pigments, Defoamers and / or biocides. 11. Water-miscible cooling lubricants according to one or more of the Claims 1 to 10. 12. Water-mixed cooling lubricants according to one or more of the Claims 1 to 10. 13. Use of the cooling lubricants according to one or more of the Claims 1 to 12 in the form of aqueous solutions or emulsions, containing 1 to 10 wt .-%, in particular 2 to 5 wt .-% of Coolants.