DE1271874B - Corrosion inhibitor for lubricants based on polyalkylene glycols - Google Patents

Description

Corrosion inhibitor for lubricants based on polyalkylene glycols Polyether oils known as high temperature lubricating oils show beside a very good temperature stability up to about 200 ° C a very good temperature-viscosity behavior at low viscosity pour points. Unlike mineral oil, these have compounds no anti-rust properties. Due to a low self-hygroscopicity take these compounds as condensates of ethylene oxide, propylene oxide, 1,2-butane epoxide, Tetrahydrofuran or, as corresponding mixed condensates, small amounts of water vapor which reduces the tendency of metals to corrode, especially iron and steel, will be considerably strengthened.

Since, with many possible uses, always with the presence of Condensation or water vapor is to be expected, must for adequate corrosion protection to be taken care of. In many cases, the use of these polyethers fails because Addition of anti-corrosion agents to the other desired properties, such as oxidation stability and resistance to depolymerization. It is for example known that soluble alkali or alkaline earth salts of alkyl or polyalkylbenzene carbon and sulfonic acids, alkylnaphthalene sulfonic acids, fatty acids, alkylphenols or thiophenols the stability of the polyether oils at temperatures above 150 "C deteriorates significantly without obtaining a satisfactory corrosion protection. Corrosion inhibitors, as they often do for mineral oils in the form of fatty amine salts of fatty acids, amine salts of olefins sulphurized or phosphorus sulphurized with P2S5, salts of dialkyldithiophosphates or dialkyldithiocarbonates, alkylsulfamidoacetic acid, alkylthioacetic acid, acoylsarcosines, for example lauroyl sarcosine, which are used, show either no solubility or only an insufficient effect. Better results will be achieved with mono or Dialkanolamides or mono- or dialkylamides of alkylthio-, alkoxy- or alkoylaminoacetic acid or propionic acid, although these amides meet the requirements in in no way suffice.

The use of tertiary alkyl or aryl phosphites as additives for lubricating oils based on mineral oil is already from British patent specification 778 818 known.

It has now been found that lubricating oils based on polyalkylene glycols obtain excellent protection against corrosion if a mixture of 0.1 to 5 percent by weight of a known ashefrelic acid camide of the general formula RX --- (C112) "CO__y in which R is an alkyl radical with 6 up to 18 carbon atoms in the skeleton and / or an alkylphenyl radical or dialkylphenyl radical with a maximum of 18 carbon atoms in the side chains, X can be - CH2 -, - NH -, - N - CH-3 -, - NHCO - -, - NCHiCO -, -CO-NH -, - S02-NH -, - O -, - S - or - CO - N - CHa - group and Y means NH2 and / or an alkanolamino- , Dialkanolamino, alkylalkanolamino group and n = 1 or 2, and 0.1 to 2 percent by weight of a phosphite ester of the general formula which is already known as a lubricating oil additive in which Ri, R2 and / or R "denote an alkyl, phenyl, alkoxyphenyl, alkylphenyl or dialkylphenyl radical with at least 6 carbon atoms in the skeleton, the OH group necessary for esterification with 2 to 5 mol of ethylene oxide and / or propylene oxide can be reacted, optionally used as additives together with other conventional lubricating oil additives.

The additives can also be 0 to 1 percent by weight, preferably 0.02 to 0.05 percent by weight, of an inhibitor for non-ferrous metals, if a special one Protection required for non-ferrous metals is included.

Examples of component a to be used according to the invention are acid amides from lauryloxyacetic acid, laurylthioacetic acid, lauryloxypropionic acid, stearic acid, Oleoyl sarcosine, stearoyl sarcosine, olcoylaminoacetic acid, laurylaminoacetic acid or -propionic acid, ('ogasinsulftmidocssigsiiure, 1) odecylbenzoic acid, Alkylamide acids, by reacting alkylamines with maleic acid or succinic anhydride or alkylated succinic or maleic anhydride, and diethanolamine. Such acid amides can be prepared from the carboxylic acids and by known processes corresponding amines by heating to temperatures up to 200'C and blowing out win the formed water by means of nitrogen. It is also possible that water formed during condensation with the aid of an entrainer such as, for example Xylene, to remove.

The alkyl radical or alkoyl radical of the acid component can also be a mixture from chains of different lengths. Such mixed alkyls are by-products from animal or vegetable Ulen or fats. Such fatty acids, fatty amines or fatty alcohols are under the name coconut fatty acid, palm kernel fatty acid, Rapeseed oil fatty acid, tallow fatty acid or coconut fatty alcohol or coconut fatty amine are commercially available.

As amine components, instead of the already mentioned diethanolamine also diisopropanolamine, monoethanolamine, monoisopropanolamine, morpholine, alkylated Use morpholine, for example 3-ethylmorpholine. However, suitable amines are also alkylalkanolamines, such as methyl, ethyl, isopropyl, butyl or Amylethanol or isopropanolamine. Also alkylamines or dialkylamines, their alkyl radical Contains up to 6 carbon atoms in the chain, can be converted into effective acid amides. Furthermore, polyamines such as Oxäthylpropandiamine, Dioxäthylpropandiainin, N-Alkylpropandiarhine, N-Alkyläthylendiamine are used.

In principle, in this implementation, instead of 1 Mole of acid to 1 mole of amine also to use higher proportions of amines. So you get for example from 1 mole of coconut fatty acid and 2 moles of diethanolamine are also suitable Products. By further reaction with small amounts of alkyl or aryl glycidyl ethers, for example 5 to 250 (0 hexyl glycidyl ether, lauryl glycidyl ether or phenyl glycidyl ether one obtains products which are clearly soluble in polyether and which are necessary for the production of one component are particularly suitable.

The phosphite ester preferably contains acrylic or alkylaryl groups, since pure alkyl esters have a low stability and under unfavorable conditions suffer a rearrangement.

Preferred phosphite esters are, for example, trinonylphenyl phosphite, Triphenyl phosphite, diphenyl nonyl phenyl phosphite, tricresyl phosphite, trixylenyl phosphite or trilaurylphenyl phosphite. For some purposes it is beneficial to implement phenols used with phosphorus trichloride by known processes with alkylene oxides to condense, with a maximum of 5 moles of ethylene oxide or propylene oxide per mole of phenol be used. By incorporating such hydrophilic groups, it is possible, for example, to achieve be that with water-soluble polyalkylene oxides by adding water none Opacities occur.

The claimed combination already meets the requirements that adequate corrosion protection for iron, cast iron, steel, lead and aluminum be asked. In the presence of water, however, it can affect non-ferrous metals Tarnish colors result. Even by adding small amounts of a well-known inhibitor for non-ferrous metals can also be used for the metals copper, brass, bronze or for Zinc alloys achieve good inhibition. Known inhibitors of this type are for example benzotriazole, methyl, ethyl or butylbenzotriazole; 1,2,3-triazole, Benzimidazole, indazole and / or benzothiazole. Tend at temperatures above 150 ° C but sulfur-containing inhibitors, especially benzothiazole, rely on copper for formation black spots.

Known anti-aging agents can also be used, preferably on Arylamine base, present in amounts from 0.1 to 3, preferably 0.5 to 1 percent by weight be e.g. B. Diphenylamine, alkyl or alkyloxydiphenylamine, phenyl - a - or phenylf-naphthylamine, Phenthiazine or alkyl substituted phenthiazines.

In addition, 0.1 to 5, preferably 0.5 to 1 percent by weight of alkyl, aryl or alkylaryl glycidyl ethers of the formula in which R contains at least 5 carbon atoms, such as hexyl glycidyl ether, lauryl glycidyl ether, stearyl glycidyl ether, phenyl glycidyl ether, nonylphenyl glycidyl ether, are added. In addition, tetrapropylene epoxide, epoxy isomer mixtures from olefins, for example from dodecene or an olefin cut Cio to Cis, or styrene oxide are also suitable.

A suitable phenolic component is, for example, 3,3'-diisobutyl-4,4'-dioxyphenyldimethyl methane.

The addition of the components of the anti-corrosion agent according to the invention to the polyglycol or polyglycol ester mixture can be carried out in any order and without prior dissolving of individual components. However, it is advantageous to prepare a concentrate of the components and to mix with such a concentrate. EXAMPLES 1 to 12 A test apparatus as described for testing antifreeze glycol in "Swiss Archives for Applied Science and Technology", 22nd year, 1956, No. 3, p. 3, is used to test the corrosion protection properties of various inhibitors. For this purpose, the metals steel, cast iron, brass, copper, aluminum and lead solder mentioned in this work are tested for corrosion, with a polypropylene glycol moriobutyl ether with the following properties being used as the test substance: viscosity at 20 = 'C = 170 cSt, at 50 - C = 50 cSt, viscosity index = 145, pour point = -42-C, flash point = over 240`C, ash content = below 0.01%. The polyglycol ether is previously purified from the potassium hydroxide catalyst used in the production process by ion exchangers and, after purification, had an acid number of 0.04 mg KOH / g and a pH of about 5.1. The following corrosion inhibitors are then added to the polyglycol ether and tested for 50 hours at a temperature of 70 ° C. with the addition of 5% water. The evaluation is carried out by visual assessment of the sheets after the test. Corrosion inhibitor GuB steel lead solder copper brass 1 base oil without addition strong strong blank low matt Rust attack Rust attack tarnish color 2 111/0 Tetradecylsuccinic acid-strong low matt matt bright laurylimid rust attack rust attack 3 3t1 / 0 tetradecylsuccinic acid - strong, isolated matt blank tarnishing color oxäthylimid rust attack rust spots 4 2 (1 / o lauroyl sarcosine stronger isolated matt slight matt Rust attack Rust spots, tarnish color 5 2 (1/0 Lauryl diethanolamide rusty isolated blank matt matt Start of rust spots 6 2 ° / o lauryloxyacetic acid less isolated blank matt matt Rust attack Rust spots 7 2 ° / t) lauryl aminopropionic acid lower lower bright matt temper colors Rust attack Rust attack 8 2 (1 / o laurylaminopropionic acid strong, isolated matt blank matt diethanolamide rust attack rust stains 9 2 ° / o laurylamido succinic acid - strong touch of rust, matt blank, tarnishing colors diethanolamide rust attack 10 2% coconut fatty acid monoethanol - slight rust appearance, shiny matt tarnish colors amid rust attack 11 2 ° (o reaction product of 1 mole of weak, isolated matt matt annealing colors Coconut fatty acid with 2 moles of rust stains ethanolamine, which with 15 (1 / o hexyl glycidether converted at 180C is 12 1.5 ° j0 reaction product of 1 mole thick rust stains matt matt tempering colors Coconut fatty acid and 1 mole of oxide rust ethyl propane diamine If amounts of 0.3 to 0.5 percent by weight of trinonylphenyl phosphite or tricresyl phosphite are added to Examples 2, 3, 5, 8, 9, 10 and 11, no corrosion is observed on the cast iron or steel. If an additional 0.02 to 0.05 percent by weight of benzotriazole is added, no changes can be seen in lead solder, copper and brass. After completion of the tests, these test metals show neither tarnishing nor matt surfaces. Examples 13 to 18 According to the test conditions ASTM-D 665 A, a polypropylene glycol monobutyl ether is tested which has the following physical data: density dw = 0.995, viscosity at 20 C = 110 cSt, viscosity at 50 C = 30 cSt, viscosity index = 145, pour point = -45-C, flash point = over 240-C. It is cleaned by neutralization with acetic acid, subsequent heating to 150 "C and filtration and has an ash content of 0.0150 / 0. The following additives are added to this lubricant Example 15 percent by weight Phenthiazine ....................... 0.5 Tricresyl phosphite .................. 0.5 1,2,3-triazine ...................... 0.05 Lauryloxyacetic acid-N-butylethanol- amide ........................... 2.0 Example 16 percent by weight 4,4'-Dibutoxydiphenylatin ......... 0.5 Triphenyl phosphite ................. 0.3 1,2,3-triazine ...................... 0.05 Nonylphenoxyacetic acid diisopropanol amide ........................... 2.0 Example 17 percent by weight Phenyl-ji-naphthylamine ............. 0.5 Trioctyl phosphite ................. . . 0.3 Benzothiazole ...................... 0.05 Nonylphenoxypropionic acid diethanol amide ........................... 2.0 Example 18 percent by weight Phenyl-fl-naphthylamine ............. 0.5 Trinonylphenyl phosphite ............ 0.3 Benzotriazole ...................... 0.005 A condensation product from 1 mole of coconut fatty acid and - 2 moles Diethanolamine .................. 1.5 Lauryl glycidyl ether .................. 1.0 According to this test, the polyether oils protected according to Examples 13, 14, 15, 17 and 18 remain without attack on the metal test rod. A polypropylene glycol monobutyl ether inhibited according to Example 16 leaves a small amount. Rust attack. If an unprotected product is used, the test rod shows deeply pitted rust scars.

Example 19 The polyether oils protected according to Examples 13 to 18 are then subjected to the following heat test: A 400 ml beaker is filled with 250 ml of the oil to be tested and a block of the following metals is immersed in the liquid: copper SAE 71, brass SAE 70 c, aluminum SAE 24, cast iron SAE 111, sheet steel SAE 1010, copper SAE 71. The metals used for this test are cut into 0 strips of about 80-15 mm. They have a 4 mm hole about 5 mm from a narrow side. To carry out the test, the metal sheets are screwed using a brass screw and by inserting brass washers in such a way that there is a gap of about 5 mm between the metal sheets, but the strips are electrolytically connected by the screw connection. The test panels are previously sanded with sandpaper, polished with fine steel wool and carefully cleaned of abrasion with acetone.

After an observation time of 120 hours at 180 ° C. in a drying cabinet, the beakers not being covered, the liquid and test metals are assessed visually. Inhibitor combination according to Examples 13 to 18 13 14 15 16 17 18 No inhibitor Appearance of the liquid clear, clear, clear, clear, clear, clear, cloudy, dark brown brown, dark brown, brown precipitation brown less brown, less Soil- strong soil- sentence ground sentence sentence Appearance of metals: Copper ...... blank matt blank matt matt, blank matt, coating rough Brass ..... bright, reddish, matt, reddish, reddish, bright, thick coating Start-up start-up Aluminum .. matt matt matt blank blank blank matt Stole . . . . . . . . blank blank blank blank blank blank red coating Casting ........ blank blank blank blank blank blank black Covering If one compares the results of this test with a heat test carried out only with a polyether oil protected against oxidation and depolymerization; For example, when adding 0.5 ('/ () phenyl-f-naphthylamine or phenyl-a-naphthylamine, no impairment of the stability can be seen by adding corrosion inhibitors according to the present invention. Similar test results are also obtained if such comparative tests according to the conditions of the oxidation test according to ASTM-D 963 or DIN 51587 are carried out.

Claims (1)

Claim: Use of a mixture of 0.1 to 5 percent by weight of an ashless acid amide known as a lubricating oil additive of the general formula RX- (CH, 2) .- CO-Y in which R is an alkyl radical with 6 to 18 carbon atoms and / or an alkylphenyl radical or dialkylphenyl radical with a maximum of 18 carbon atoms in the side chains, X can be - CHs -, - NH -, - N - CHs -, - NHCO - - NCH3C0 -, -CO-NH--, - SO2-NH--, -0--, - S - or - CO - N - CH3 - group and Y = NHz and / or an alkanolamino, dialkanolamino, alkylalkanolamino group and n = 1 or 2 and 0.1 to 2 percent by weight of a phosphite ester of the general formula known as a lubricating oil additive in which Ri, R. and / or R denote an alkyl, phenyl, alkoxyphenyl, alkylphenyl or dialkylphenyl radical with at least 6 carbon atoms, the OH group necessary for esterification with 2 to 5 moles of ethylene oxide and / or propylene oxide can be implemented, optionally together with other conventional lubricating oil additives as additives for lubricating oils based on polyalkylene glycols. References considered: British Patent No. 778,818.