DE942524C - Additives to lubricants - Google Patents

Description

ISSUED MAY 3, 1956

St 6333IVc j 23 c

Additives to lubricants

The invention relates to the use of metal salts of acyl-p-aminophenols as additives Lubricants.

Acyl-p-aminophenols have an excellent Anti-oxidation effect and have in solid hydrocarbons such as wax, synthetic rubbers, found application as an antioxidant and as a thickener for lubricating greases. In some However, they are practically insoluble in organic liquids, e.g. in mineral lubricating oils. Just that low molecular weight compounds are soluble in synthetic lubricants. This difficulty was observed even when the compound in question was replaced by long-chain acyl or alkyl groups is substituted, which normally make phenols soluble in mineral oil. Therefore these connections can as such, not to be used as additives for lubricating oils, as they have to be dissolved in order to be effective against oxidation exercise. In the form of a finely divided dispersion, acylaminophenols in some solids resistance to oxidation. It has now been found that the metal salt derivatives of acylaminophenols and related compounds in mineral oils and synthetic oils in one are soluble in a wide temperature range. This discovery is surprising. Usually metal

derivatives are considerably less oil-soluble than the parent compounds. The reason for the increased oil solubility of the metal salts is not known, but the solubility is the trunk connections are in most cases increased by several orders of magnitude when one goes to the Metal salt passes over.

It has also been found that the metal salts of acylaminophenols have the valuable antioxidant effect keep the root connection. aside from that

ίο they give the lubricants for internal combustion engines a strong detergent and sludge spreading effect. These properties contribute to Keeping the engine clean. The compounds also act as fat and wax thickeners and still have other valuable properties.

The metal salts of N-acylaminophenol compounds used in the present invention have the general principles Structural formula

- Me *

where R, R 'and R "are hydrogen or hydrocarbon radicals with ι to 25 carbon atoms, which can be the same or different from each other, Me is a metal and χ is the valency of the metal. Examples of suitable hydrocarbon radicals are alkyl, alkenyl , Cycloalkyl, alkaryl and other aliphatic, alicyclic and aromatic radicals. Preferably, R, R 'and R "are aliphatic radicals; Straight- or branched-chain alkyl groups are particularly valuable for achieving salts with good oil solubility. Examples of such alkyl radicals are methyl, isopropyl, tert. Amyl, tert. Octyl, n-decyl, dodecyl, cetyi. Examples of alkenyl radicals are hexenyl, nonenyl and oleyl. Examples of alicyclic radicals are cyclohexyl, ethylcyclohexyl, n-butylcyclohexyl, and the unsaturated cycloaliphatic radicals are also suitable. In some cases the aryl and alkaryl radicals such as phenyl, methylphenyl, butylphenyl, diethylphenyl and the like are useful, although they are less recommended because of their lower oil solubility.

R advantageously contains 6 to 20 carbon atoms in order to produce products of high oil solubility and good antioxidant and to obtain sludge spreading effect. R 'and R "are preferably taken together no more than 30 carbon atoms.

The N-acyl-p-aminophenols are known per se Way prepared by adding an organic acid or an acid chloride with the p-aminophenol or an alkylated derivative thereof. The product can be used in the usual manner, e.g. B. by Distillation, crystallization, solvent extraction, etc., can be purified.

Typical aminophenols that can be used for this reaction are e.g. B, the following: p-aminophenol, 3-hexyl-2 (.- aminophenol, 2-tert-amyl-4-aminophenol, a-tert-octyl- ^ aminophenol, 2,6-di-tert-octyl-4- aminophenol, s-pentadecyl- ^ aminophenol, 2-isohexadecyl-4-aminophenol, C ₁₆ - to C ₂₀ -branched, alkyl-4-aminophenols.

Examples of organic acids that can be brought into reaction with the aminophenols are Fatty acids, strongly branched-chain oxo acids, etc., such as ant, butter, caproic, capric, lauric, Palmitin-, stearin-, undecylene-, oil-, linole-, cyclohexyl-valerian-, 7, 7, 9, 9-tetramethyldecyl-, . 6, 8, 8,10, io-pentamethyl-undecylic acid and naphthenic acids.

The acylaminophenol is then converted to the metal salt by reacting it with a metal, metal oxide / hydroxide, sulfide, alkoxide, hydride or carbide at 80 to 200 ⁰ , basic neutralizing agents being preferred. The reaction proceeds smoothly if the phenol is first dissolved in an inert solvent such as chloroform or isopropyl alcohol, then the metal compound is added and the mixture is refluxed for several hours. The reaction mixture is filtered and the solvent is stripped off.

The product can be made directly in an oil base to make a concentrate. If you add the acylaminophenol to the oil at a sufficiently high temperature, at least it works some of the phenol in solution. The basic reactant is added slowly; the resulting Metal salt remains in solution. The reactants can be stirred to ensure the completeness of the Ensure response. The oil concentrate, which is up to about 15 to 50 percent by weight or more It contains a metal salt derivative, is then filtered and can be stored, shipped and used as a lubricating oil additive in this form sold.

If the salts are produced in the lubricating oil base, antifoam agents can be added to the reaction mixture, like higher alcohols, e.g. B. stearyl, lauryl or cetyl, wool fatty alcohols in Add amounts of about 3 to 15%, based on the concentration of the additive in the end product. The salts' monovalent metals, e.g. B. of the alkali metals, such as Na, K, Li, are less recommendable as lubricating oil additives than those with higher values Metals, as they are somewhat soluble in water and ~ from the Lubricants can be leached out. The alkali salts are, however, used as thickeners and as oxidation retarders suitable when a sludge distribution effect is not required. The salts of polyvalent metals such as Ba, Ca, Sr, Al, Cu, Co, Sb, Zn, Sn, Fe, Ni and other heavy metals, form valuable soluble additives, salts of divalent metals, z. B. Ca, Sr and especially Ba, are preferred: these salts are easy to prepare and have excellent properties both as

Sludge inhibitors as well as oxidation retarders.

Equimolar amounts of phenol and a monovalent metal compound, such as NaOH, give the normal metal salt of the composition

OMe

■ Λο The normal metal salt of a divalent metal, which by reaction of the phenol with KaUc,

Ba (OH) ₂ · 8H ₂ O

etc., can have the following composition:

O - Me - O

- R "R '

NH

C = O

NH

C = O

OMeOH

R'—. - Around

NH
C = O
R.

OMeOH "

R'-

Me (OH) ₂

where the ratio of metal to acylaminophenol is 0.5: ι.

When the sludge-inhibiting effect of the additive should prevail, one uses the phenolic compound with larger amounts of the metal compound um, whereby basic salts are obtained. So can the metal phenates of divalent metals for proportions of ι or 2 parts of metal to ι part of acylaminophenol be composed as follows:

One can use MetaUphenolate, in which the ratio of metal to acylaminophenol is within the limits from 0.8: ι to 1.5: 1, etc., use. In these Fills are usually mixtures of the types given above. Also mixed metal salts, such as B. the Ca-Ba-SaIz, which can be obtained by neutralizing the acylaminophenol with lime and further reaction with barium hydroxide are valuable for some uses.

According to the invention, the metal salts are mixed with mineral or synthetic lubricating oils or mixtures the same in concentrations of about 0.02 to 15, preferably from about 0.1 to 5 percent by weight mixed. The exact amount depends on the product used, the type of lubricating oil, the working conditions in the engine and other factors away. The metal salts can also be used advantageously in lubricating greases; in this case however, amounts up to about 20 percent by weight may be required.

example 1

Solubility of acyl-p-aminophenols and their metal salt derivatives in oils

The maximum solubility of the various acyl p-aminophenols and their metal salt derivatives in mineral and synthetic lubricating oils was determined at room temperature. As the mineral lubricating oil, a Mid-Continent-oil was used (viscosity: 6.3 cSt at "98.9 °, viscosity index: 50) as a synthetic lubricating oil Mischester of 2 moles of adipic acid, 1 mol of was I ₁ 3-Bütandiol and- 2 moles. C ₈ oxo alcohol is used, the values are given in Table I.

Table I

link

ι. N- » Cg-Oxo-acylüi-4-aminophenol lithium salt

2. N- * C ₁₃ -oxo-acyl «.- 4-aminophenol

Sodium salt

Lithium salt

basic barium salt,

3. N-flCg-Oxo-acyk-s-pentadecyl-

4-aminopbenol

normal barium salt

4. N- ^ C ^ -oxo-acyk-3-pentadecyl-

4-aminophenol

normal barium salt

5. N-Lauroyl-4-aminophenol

normal barium salt

normal calcium salt

normal strontium salt

Maximum

Oil solubility,

Weight percent

mineral oil

2.7

3.4 17.8

0.15 45.0

0.18 50.0

5, o

2.5

44, o

Synthetic oil

0.5 1.5 0.25 0.8

2.2

4.4

12.0

15.0

0.2 2.0

1.5

18.0

Example z corrosion test

The corrosion-preventing effect of the normal barium salt of C ^ -oxoacyc-3-pentadecyl-4-aminophenol determined in oil versus a Cu-Pb alloy. For this purpose, a solution of ι percent by weight of the barium salt in a Test oil SAE 20 as well as a sample of the pure base oil were tested as follows: 500 ecm test oil were in a Oxygenation tube made of glass introduced (33 cm long, 6.7 cm diameter), which at the bottom with a Air inlet tube 6.35 mm in diameter was fitted to facilitate air distribution

was perforated. The Oxydationsrohr was immersed in a heating bath whose temperature was maintained at 163 ⁰ during the experiment. 2 quarter parts of bearing shells of motor vehicle bearings made of Cu-Pb alloy of known weight and a-total-

area of 25 cm ² was attached to the two ends of a stainless steel rod, this was immersed in the test oil and rotated at 600 rpm. Through the oil was. Air blown at a rate of 56.6 l / h. To the test conditions too

tighten, the bearings were washed and weighed, polished and reweighed every 4 hours.

The test oil with the barium salt. resulted in a weight loss of the bearing - of only 7 mg after 24 hours

while the pure oil at the same time unites Resulted in a weight loss of 19 mg.

Example 3 Investigation of the Dispersion of Carbon Black

A comparative determination of the soot distribution was carried out in order to determine the effectiveness of the various metal salts according to the invention with regard to the sludge distribution in lubricating oils. In this test were 6 weight percent of activated charcoal mixed with the oil containing the additive and thoroughly dispersed therein, by a snow racket, it was stirred with a mixer type for 15 minutes at 121 ^0th Then were

250 cc of the mixture in a 250 cc graduated cylinder

poured and settle for 24 hours at 93 °

Jassen. If the additive is not a dispersing agent

. Has an effect, the soot settles quickly during this time

and the supernatant oil is clear after 1 to 2 hours. A very good dispersant keeps the carbon black in suspension for so long that no change in the cloudy slurry can be observed even after 24 hours. With most dispersants a layer build-up occurs, with a black layer on the bottom (high soot concentration) and a blue, opaque layer on top (lower soot content). This layer formation can only be seen in reflected light. The base oil used for this test was a Mid-Continent solvent extracted oil (mpas: 6.9 cSt at 98.9 °): The audit found at a level of 0.75% ^er d Ba and Sr salts according to the Invention no sedimenta

tion of soot. The same test showed that the pure base oil had a protruding oil of 40 ecm. The 65, Ca-salt gave an almost perfect dispersion. The Na and Li salts were slightly less effective than the salts of polyvalent metals.

Example 4 Oxidation of Grease

A lubricating grease of the following composition was prepared: 29% rapeseed oil, 5.92% sodium hydroxide, 100% petroleum sulfonate, 1% barium salt of C ₁₃ -oxo-acyl (? - '3-pentadecyl-4 -aminophenol, 63.08% distillate lubricating oil (coastal distillate), viscosity: 7.8 cSt at 98.9 °.

A portion of the lubricating oil was mixed with the fats in a steam jacketed fat kettle. The sodium hydroxide was added with stirring for 8p while the mixture was at about 204 bis 2i6 ° was heated. Now were the remaining lubricating oil and the additive is added, the heating is interrupted and the fat is cooled in a pan.

In addition, the same grease was made without additives. Another fat sample contained 1 percent by weight of N-lauroyl-p-aminophenol

The fats were evaluated by the Norma-Hoffmann oxidation test by placing the fat sample in a bomb under an oxygen ^{pressure of 7.7 kg / cm 2} and observing the pressure drop at 100 °. In this test ze. * t a grease of high oxidation resistance after a certain test duration a lower pressure drop than a grease with low oxidation resistance. The results are given in Table II.

Table II

Additive in fat

none '

N-Lauroyl-p-aminophenol (1 percent by weight)

Barium salt of N- »C ₁₃ -oxoacyl <r-3-pentadecyl-4-aminophenol (1 percent by weight) ..

not determined.

Pressure drop in kg / cm ²

°> 3 I °, 7 I 2

Duration up to

to the specified.

Pressure drop,

hours

46

144

240

52

250

360

78

Although the acylaminophenol is quite effective as an antioxidant, the barium salt was substantial more effective, probably due to its higher solubility.

The lubricating oil bases that can be used in the context of the invention can be directly distilled mineral lubricating oils or distillates of paraffinic, naphthenic, asphaltic or mixed basic Crude oils or various mixed oils, furthermore deasphalted residual oils can be used will. One can use hydrogenated oils or white oils

as well as use synthetic oils, e.g. B. by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by hydrogenation of coal or coal products manufactured products. In certain cases products of the splitting of tar fractions and Distillate fractions of coal tar or shale oil can be used. Vegetable or animal oils can also be used for certain purposes

ίο or their hydrogenated or voltolized products for can be used alone or in a mixture with mineral oils.

Other synthetic lubricants which can be used as a basis according to the invention are e.g. B. long chain Esters of monobasic acids, polybasic acids, monohydric and polyhydric alcohols, polymerized Ester, ether, ether-ester, ester-ether. Of the synthetic lubricants, the synthetic esters, both the simple and the mixed esters are preferred.

In addition to the additives used according to the invention, other additives can also be added to the lubricating oils be added in the usual way.

Claims (3)

PATENT REQUIREMENTS: ι. Use of salts of monovalent or polyvalent metals, preferably of alkaline earth salts, the general formula NH C = O -Me » in which R, R 'and R "represent hydrogen or hydrocarbon radicals with ι to 25 carbon atoms, e.g. alkyl radicals, Me a metal and χ the valency of the metal, in amounts of 0.02 to 20 percent by weight of the total mass as additives on lubricants based on mineral oils and synthetic oils. 2. Embodiment according to claim 1, characterized by the use of a metal salt, in which R is a hydrocarbon radical with 6 to 20 carbon atoms. 3. Embodiment according to claim 1 and 2, characterized by the use of a metal salt, in which at least one of the R 'and R "groups is hydrogen.