DE1280454B - Aqueous metalworking fluid - Google Patents

Description

Aqueous Metal Working Fluid The present invention relates to an aqueous metalworking fluid for the production of sliding coatings the metals, consisting of an aqueous solution of an amine and an alkali soap of fatty acids, which is characterized in that the aqueous solution is amine soap in an amount of about 25 to 75 percent by weight, based on the total content of soaps, and 30 to 95 percent by weight of water, the fatty acids being a Have a solidification point below about 30 ° C.

Although it is already known for lubricating and cooling in cutting and drilling work to use machining fluids that, among other things, in water It contains insoluble, emulsifiable amine fatty acid esters. For emulsification of the esters in water, fatty soaps can be used. So much for this well-known When the process of forming solid coatings from the machining fluid is used, these are in water not soluble and can therefore - in contrast to those formed according to the invention Coatings - do not wash off with water.

It is also already known to use aqueous solutions of amine and alkali soaps in such processing fluids. In these known agents, the maximum amount of amine soap is 221 / 9.0 / ″, while according to the invention at least 25% amine soap, based on the total content of soap, should be present. The known mixtures also contain relatively large amounts of amine phosphate and polyalkylene glycol with other modifying agents These additives, which can amount to 50 to more than 100% of the total amount of soap, of course modify the properties of these coatings to such an extent that they have completely different properties from the processing agents according to the invention.

So a coating from the known means remains liquid, while the dry new agents to form firm coatings. If the coating hardnesses are measured, then has a coating made from the new lubricant z. B. a hardness value of 110 (ASTM D 1321-55 T), while the coating hardness is that of the known material coatings produced due to the low strength of the liquid coating could not be measured at all. In an attempt to determine the coefficient of friction (see Lubrication Engineering, May / June 1955 edition, "Sliding Friction Test") with a coating of the new agent a value of 0.015 was determined, while means of the known processing means only a flowable coating with a value of 0.15 was retained. So the coefficient of friction is increased by the new means reduced to the tenth part.

It is also already known to produce coating mixtures which consist of an aqueous solution of an alkali soap and a nitrogen-containing soap. However, coating mixtures of alkali and amine soaps are in this reference not described.

The new metalworking fluids have the further advantage that they are easy to apply, dry quickly and already customary for application existing jigs and fixtures along the production line can be used. the The coatings obtained do not settle in the drawing systems and remain through several Stages of drawing and stretching processes preserved and effective. The ones needed for application Devices also do not need to have a large floor area, which is also the case contributes to cost savings. The applied coatings will be from the new funds not so firm, even after prolonged storage, that subsequent processing of the Metal would be more difficult. So it is possible to get a coating from the new funds to apply and to store the coated metal. That can be particularly important be if z. B. shutdowns of the finishing mill are necessary and the corresponding treatment and processing sequence must be interrupted or the Processing is not possible immediately after the coating has been applied.

The new treatment fluids can, as will be described below will be applied to the metal plates; ' whereupon the water from the coating is evaporated.

The soaps used in the present invention can be made using more conventional soap-forming fatty acids with solidification points below about 30 ° C will. The procedure for determining the solidification point is described in "Titter Test" of the American Oil Chemists - Society official method DA 13-42. These Fatty acids can be mixtures of fatty acids derived from different oils, e.g. B. vegetable oils derived. For example, acid mixtures are suitable, those of castor oil, coconut oil, palm kernel oil, linseed oil, olive oil, peanut oil, rapeseed oil, corn and soybean oil. Individuals are also suitable for these purposes Acids such as oleic acid, ricinoleic acid, etc., derived from fatty acid mixtures, e.g. B. the above, were separated. In addition, fatty acids such as tall oil; which as a by-product other reactions arise.

The amines associated with the fatty acids with a low solidification point to produce the amine soaps can be reacted, any water-soluble be organic amines with a boiling point above about 100 ° C, such as ethylenediamine, Monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, monoisopropanolamine, Morpholine and 2-amino-1-butanol. Particularly suitable for application using rollers at high speed are coating mixtures whose amine soaps are such amines such as 2-amino-2-methyl-1-propanol; 2-amino-2-methyl-1,3-propanediol or 2-amino-2-ethyl-1,3-propanediol contain.

The alkali metal soaps used according to the invention can be customary Be sodium and / or potassium derivatives of the corresponding fatty acids.

The choice of the respective machining liquid depends primarily on the type of subsequent processing of the metal, the decisive one being Factor the size of the coefficient of friction between the workpieces and the rollers is. One method of estimating this property of the lubricant coating is described in the aforementioned article in Lubrication Engineering.

As a general rule, it can be applied when cold drawing thick It is important that the lubricant coating provides the greatest possible protection against metals Scratch offers. In such a case, it is advantageous to use a machining liquid to use in which the proportion of alkali soap is relatively large. When the thick of the metal decreases to less than 1.5 mm (16 gauge), there are possible scratches only of secondary importance and softer coatings can be used which contain a large amount of anti-soap. Soft covers will be generally preferred there because of their greater mobility and greater strength, where their use is possible.

Runs 1, 2 and 3 below are examples of machining fluids that produce coatings suitable for use on large pieces of metal, while Runs 4, 5, 6 and 7 produce softer coatings that are suitable for thinner metal parts (1) triethanolamine . . . . . . . . . . . . . . 2.6% caustic potash. . . . . . . . . . . . . . . . . . . . . . 3.7 "/ () oleic acid........................ 23.7% water ................ ...... 70.0% (2) monoisopropanolamine ........ 1.5% caustic potash........................ 3 .7% oleic acid....................... 24.8 () / o water............... 70.0 0/0 (3) 2-amino-2-methyl-1-propanol .. 1.80 / 0 caustic potash............. ....... 3.7 () / o castor oil fatty acids ........... 24.50 / 0 water .................. .... 70.00 / 0 (4) triethanolamine................ 5.001, etching nation..................... 1 , 80 / () Tall oil ......................... 23.20 / 0 Water .... ........... ..... 70.00 / a (5) Monoethanolamine............. 2.8% caustic potash. .........: ..... ... ... 2.50 / 0 coconut fatty acid........... 24.70 / 0 water..................... 70, 00/0 (6) Monoisopropanolamine........ 4.70 /, Caustic soda..................... 0, 9% corn fatty acids ............... 24.4% water. . . . . . . . . . . . . . . . . . . . . . 70.00 / 0 (7) 2-amino-2-methyl-1-propanol .. 5.30 / 0 caustic soda. . . . . . . . . . . . . . . . . . . 0.9% soybean fatty acid. . . . . . . . . . 23.80 / () water. . . . . . . . . . . . . . . . . . . . . . 70.0% Although 70% water is contained in each of the above approaches, the water content can also be changed considerably, it can be between 30 and 95 percent by weight, expediently between 50 and 95 percent by weight and 70 and 90 or 95 percent by weight. Changes in the amount of water provide a simple and convenient means of regulating the thickness of the coating in cases where the thickness of the coating is important. To facilitate shipping and storage of the machining fluids of the present invention, concentrated solutions can be prepared containing less than about 50 weight percent water and then diluted prior to use. Surprisingly, even if the water content is reduced to about 30%, there is generally no risk that the mixtures according to the invention will solidify or gel. This property allows greater flexibility in the selection of the respective components and the coating process to be used.

When using certain amine soaps, the amount of water can be a to play an important role. This is e.g. B. the case when triethanolamine soaps in the Machining fluid can be used as the mixture is then at an average Concentration range of about 50111, becomes solid, but does not form a gel and becomes thinner again even at lower concentrations.

The coatings produced from the new means can also be carried out by the addition of other materials to the machining fluids can be modified. For example, softer coatings can be made by adding about 5 to 10 or 15% of a suitable one Plasticizer can be added. Suitable Plasticizers are e.g. B. the water-soluble glycols and polyoxyethylene derivatives as well the sulphonated or sulphated fatty acids.

If the coated panels are to be stored for some time before they are further processed, it may be useful in some cases to add a sticking agent to the processing fluids in order to largely prevent the panels from sticking together. Suitable agents of this type are compounds which are compatible with the processing fluids, but which migrate to the surface of the coating in order to form a non-adhesive coating there after the moisture has been removed. For example, methyl cellulose and / or polyvinyl alcohol, when used in amounts of 5 to 15 % (on a dry basis), reduce the sticking together of the coated metal.

The machining fluids according to the invention can optionally also contain minor amounts of other materials known to be improve the tensile properties of the lubricants, e.g. B. water-insoluble materials, such as chlorinated oils, sulfur flowers, colloidal graphite, etc.

Although the machining fluids according to the invention are particularly suitable for application by means of rollers, they also have certain advantages when applied in other ways, e.g. B. by spraying or dipping. The viscosity of the machining fluid changes according to the coating process used. For example, the viscosity of the machining fluid when applied by roller can be between 20 and 200 centipoise at 21 ° C, while when the mixture is applied by dipping it can be up to 1000 centipoise at 21 ° C and when sprayed it can be up to nearly 5000 centipoise at 21 ° C .

The dry lubricant coatings made using the inventive Machining fluids produced on metal plates are water-soluble, thermoplastic coatings with a waxy structure. In addition, the Coatings practically no inorganic salts, which makes it possible to use the coated To weld metal without removing the coating while doing the previously used dry soap-borax lubricant coatings was necessary Remove coating before welding. The melting points of the invention Lubricant coatings are between about 65 and 150 ° C and were "dropping." Point of Lubricating Grease Test Method, ASTM D 566-42e determined. Your hardness is between 40 and 140 according to the »Test for Needle Penetration of Petroleum Waxes, ASTM D 1321-55 T «.

Another advantage of the mixtures according to the invention, in the case of these are applied by means of rollers, is that the metal plates are not completely must be clean when the machining fluid is applied. This stands in contrast to the previous methods for applying dry lubricant coatings, where it was necessary not only to carefully check the metal plates before plating to clean, but also to ensure that all cleaning products are removed from the panels removed.

It is only necessary that from the surface of the metal, if there are large amounts of oil and / or other impurities on it, at least the excess oil and other contaminants are removed before the coating mixture is applied. However, it has been found that if only a proportionate a thin film of oil is present or retained on the metal surface Application of the processing fluid by means of rollers without removing it beforehand Oil film an adhesive lubricant coating is formed on the metal. if the roller applies the machining liquid to the metal surface, so penetrates this passes through the oil film and mixes the oil with the machining liquid. The machining fluid in turn absorbs the oil and makes it part of the coating so that the oil does not affect the adhesion of the coating to the plate.

Any of the usual metal cleaning solutions can be used as the cleaning solution be used, e.g. B. aqueous or emulsion-like detergents.

The processing liquid can be by means of suitable rolling devices applied to the surface of the metal plate; z. B. by means of a preferably used roller applicator according to U.S. Patent No. 2,774,684.

The thickness of the coating applied to the metal plate can be in vary in a wider range and depends on the subsequent drawing operations away. For most machining operations, a coating thickness is between 0.001 and 0.008 mm satisfactory, which is a weight of 1; 1 to 7.7 g / m2 of the surface is equivalent to.

The evaporation of the water from the coating can take place in several ways take place, e.g. B. by drying in the air or passing over heated, if necessary Air. The new treatment fluids dry relatively quickly without that first an impermeable skin forms on the surface. The water must cannot be completely removed from the coating, as it is still at 5 to 10 percent by weight Water, even with 15 percent by weight of water, still has a good lubricating effect Coating is present. In contrast to this, the known coatings usually had to completely dried, which is an additional effort. The metal should however, at the end of the heating process, a temperature below 65, preferably 49'C have.

The technical progress over the USA patent specification 2,625 509 can be seen from the following examples.

Those listed in Table II, Column 2 of U.S. Patent 2,625,509 Ingredients were taken in the relative weight amounts given in the table Use the procedure described (beginning with line 4 in column 3) mixed. A 50% aqueous solution was used as the sodium mercaptobenzothiazole solution used. According to the mixing process described in the paragraph from line 4 column 3 According to the citation, the castor oil was placed in a double-walled kettle while stirring heated with steam to a temperature of 49'C. After adding the prescribed Sodium hydroxide solution while stirring was the temperature of the resulting soap during Gradually increased to 82 ° C. for 20 minutes, after which the mixture was stirred for a further 11/2 hours, then the triethanolamine, then the polyalkylene glycol and finally the phosphoric acid were admitted. After stirring for an additional 30 minutes, the bath became on 49 ° C., after which water is slowly added to the mixture with continued stirring became. Excessive foaming did not and did not occur during the water supply no additional heating necessary.

For comparison with the agent prepared as described above, a simple mixture of sodium soaps and amine soaps from fatty acids with low normality was made from the following soap-forming ingredients: Castor oil fatty acids ..... 17.5 percent by weight Mixed fatty acids ... 21.9 percent by weight sodium hydroxide . ...... 2.3 percent by weight alkanolamine (2-amino-2-ethyl-1,3-propanediol) 7.8 percent by weight water ................ 50.5 Weight percent The ingredients listed above were reacted by dissolving the sodium hydroxide in all of the water, adding the castor oil fatty acids and heating the mixture to 71 ° C. The heated mixture was vigorously stirred for 30 minutes and the mixed fatty acids and the alkanolamine were added. Without further heating, the resulting mixture was stirred vigorously for another 30 minutes to complete the process.

To determine the physical properties of the two as above described means these were on the surface of identical Test strips sprayed from sheet metal to make coating films with practically the to form the same total solids content. The coated test strips were dried for about 21/2 hours at room temperature. During this time it dried the agent according to the invention into a solid, waxy layer, whereas the Film of the known agent was still in such a liquid state that that it flowed slowly at room temperature due to gravity. Then the Films on the two test strips for the “Test for Needle Penetration of Petroleum Waxes ”, ASTM D 1321-55 T, to provide values for the film hardness of the two coatings to obtain. The film from the well-known remedy was so soft and fluid, that it is completely outside the range of film hardnesses that the standard used Penetrometer can measure, so that no hardness value can be obtained for this film could. However, the film from the agent according to the invention brought a hardness value of 110 in the same experiment (the value is therefore within the range specified in the invention documents specified range from 40 to 140).

Then the two coated test strips were subjected to the test procedure that published in the May-June 1955 issue of Lubrication Engineering "Sliding friction test", to which reference was made in the invention documents, subject. The thus determined coefficient of friction of the film from the known means was 0.15, whereas that determined on the film made from the agent according to the invention The coefficient was only 0.015, i.e. one tenth of the known mean.

Claims (1)

Claim: Aqueous metal working fluid for the production of Sliding coatings on metals, consisting of an aqueous solution of an amine and an alkali soap of fatty acids, d u r c h ek ek e n n n e i c h n e t that the aqueous solution of amine soap in an amount of about 25 to 75 percent by weight, based on the total content of soaps, and contains 30 to 95 percent by weight of water, wherein the fatty acids have a solidification point below about 30 ° C. Into consideration Printed publications: German Patent No. 738 461; USA: patents No. 2 238 478, 2 625 509.