DE1047356B - Lubricating oil based on liquid esters - Google Patents

Description

Lubricating oils to be used in aircraft engines and for gas turbines must have a Allow lubrication over a wide temperature range, they should also be used for have sufficient resistance to oxidation and heat at high temperatures and, if possible exhibit a low pour point for working at low temperatures. At the same time they should be little volatile and have a high flash point to avoid evaporation losses and risk to avoid inflammation.

For this special purpose, lubricating oils based on liquid diesters are already included in the formula R'OOC.R.COOR ", in which R is a bivalent saturated aliphatic hydrocarbon radical and R 'and R "are alcyl, aralcyl or cycloalcyl radicals with more than 2 carbon atoms have been used, which are an additional 2 to 30 percent by weight a polymeric acrylic acid or alcylacrylic acid ester and such amounts of a salt an aromatic carboxylic acid or a phenol with a metal from the second group of Periodic Table contain that the metal content of the lubricating oil is 0.01 to 1 percent by weight.

Such lubricating oils behave quite satisfactorily in many practical applications because the polymer acts as a thickener and viscosity index improver, but they also show often the disadvantage of a reduction in viscosity in the course of the lubrication process, which indicates depolymerization the polymer component due to the mechanical stress should. This deficiency has a particularly detrimental effect in hydraulic devices and in such Gas turbines in which the lubricant also serves as a hydraulic fluid.

It is also known that certain complex esters are formed in the complete esterification of a dicarboxylic acid with an ester of a saturated aliphatic hydroxy acid containing at least one ether group are obtained, because of their high viscosity index and low pour point not only per se to use as lubricating oils, but also mineral lubricating oils of the same viscosity for improvement to add.

It has also been recommended to mix esters of dicarboxylic acid and branched-chain alcohols obtained from the oxo synthesis with 10 ⁽ to 36 carbon atoms in the alcohol part) in mineral lubricating oils in order to increase their viscosity index.

It has now been found, surprisingly, that the disadvantages mentioned in the previously known Ester oils can be overcome by removing the liquid diesters from the formula

Liquid ester-based lubricating oil

Applicant:
"Shell" Research Limited, London

Representative: Dr. K. Schwarzhans, patent attorney,
Munich 19, Romanplatz 9

Claimed priority:
Great Britain 14 April 1955

John Owen Cliffe, Whitby, Cheshire,
and Donald Reece, Birkenhead,

Cheshire (UK),
have been named as inventors

R'OOC.R.COOR "with very specific hydrocarbon lubricating oils in amounts of 2 to 50 percent by weight, calculated on the mixture of ester and hydrocarbon oil, and with salts of one aromatic carboxylic acid or a phenol and a metal from group II of the periodic Systems combined. According to the invention, the hydrocarbon lubricating oil should have a viscosity index above 70 and have a viscosity of at least 374 SUS at 38 ° C. The salt of a divalent metal is used in amounts such that the finished lubricating oil is 0.01 to 1 percent by weight Contains metal.

These new lubricating oils are sufficiently resistant to oxidation and have a high flash point and a viscosity index high enough for practical use. Compared to the known compositions but they have the essential advantage of a stable viscosity even with a higher viscosity mechanical stress, which is particularly evident when you use such an oil passes through an injection nozzle several times.

The liquid diesters which come into consideration according to the invention, in the formula of which R 'and R "are alcyl-, Aralcyl or Cyclo alcyl radicals with more than 2 carbon atoms mean and R is a divalent saturated one aliphatic hydrocarbon radical are derived from saturated aliphatic dibasic Acids, such as malonic, ÄÜiylmalon-, amber, methyl amber, 1,1- or 1,2-diethyl amber, glutar, 1- or 2-methylglutar, 1,3-diethylglutar, adipine,

809 700/520

1- or 2-methyladipine, pimeline, 1,2,5-trimethylpimeline, Cork, azelaic, sebacic, nonane, 1,9-dicarboxylic and decane-l, 10-dicarboxylic acid and of Alkanols, such as propanols, butanols, hexanols, Octanols and nonanols or aralkanols, such as benzyl and phenylethyl alcohol, or cycloalkanols, such as cyclopentanone, cyclohexanol and methylcyclohexanol. Typical liquid esters, which Can be used with advantage in the context of the invention are di- (2-methylheptyl) adipic acid esters, Di- (3,5,5-trimethylhexyl) adipic acid ester or the corresponding sebacic acid ester, di- (3-ethylhexyl) adipic acid ester or the corresponding sebacic acid ester, dihexylpimelic acid ester, di- (2-ethylhexyl) sebacic acid ester, di-sec-butyl-sebacic acid ester, di-sec-butylmalonic acid ester, di- (l-ethylpropyl) -azelaic acid ester and di-butylethyl malonic acid ester.

A single lubricant base for the compositions according to the invention can be used liquid ester or a mixture of two or more such esters can be used.

The hydrocarbon lubricating oil can be any mineral oil or a synthetic oil, which has the specified properties with regard to the viscosity index and the minimum viscosity. Preferably the viscosity is between 681 and 1364 SUS at 38 ° C and the viscosity index over 85. Mineral lubricating oils are preferred, especially with solvents refined mineral lubricating oils and dewaxed mineral lubricating oils. If such a Oil tends to separate paraffin particularly at low temperatures, so it can be a common one Pour point depressants are incorporated.

The third important component of the lubricating oils of the present invention is a salt of an aromatic Carboxylic acid or a phenol with a metal from Group II of the Periodic Table, which is in the Mixture of liquid ester and hydrocarbon lubricating oil is soluble to the extent required. These salts increase the resistance of the compound lubricant to oxidation and heat under working conditions at high temperature and prevent varnish formation on the Storage of gas turbines, for example.

Of the metals of group II, zinc and calcium are most suitable for the present purpose; but you can also use beryllium, magnesium, strontium, cadmium, barium or mercury salts use. The aromatic carboxylic acid or phenol should have sufficient oleophilic properties, to ensure that the metal salt used is so soluble in the lubricating oil mixture is that the metal content in the total lubricating oil is between 0.01 and 1 percent by weight. Man can use neutral or basic salts or mixtures of normal and basic salts.

Particularly suitable aromatic acids are benzoic acid, naphthoic acid, 4-tert-butylbenzoic acid, 2,4-di-tert-butylbenzoic acid, di-isopropylsalicylic acids, Octylsalicylic acids, pentadecenylsalicylic acids, octadecylsalicylic acids, stearylsalicylic acids and octyl-4-oxybenzoic acids. The salts of the alkylated oxybenzoic acids are preferred. So z. B. Salts of mixtures of alkylated oxybenzoic acids can be used, which can be obtained by reacting salicylic acid or 4-oxybenzoic acid with a mixture obtained from alkenes, as is obtained when breaking solid paraffin, or with a mixture of Alcohols in the presence of a suitable condensing agent such as 90 to 98% sulfuric acid or zinc chloride. The zinc salts of alkyl salicylic acids with 12 to 20 and especially are particularly effective 14 to 18 carbon atoms in the alkyl group.

Suitable phenols are phenol itself, the naphthols, the cresols and the more highly alkylated phenols, such as amyl, octyl, nonyl, decyl, tetradecyl,

ίο Pentadecanyl- and Octadecyl-phenol. It can be salts of mixtures of alkylphenols, as they are, for. B. by alkylating a phenol with alkene mixtures obtained, and these are used because of their low melting points compared to the pure alkylphenols are preferred. So z. B. a mixture of alkylphenols obtained by alkylating Phenol or a cresol or 1- or 2-naphthol with an alkene mixture of 8 to 18 carbon atoms in the molecule can be used. In the phenol, more than one alkyl or alkenyl group and other ring substituents can also be present, provided that they are oil solubility not undesirably lower the phenol. For example, halogens or Alkoxy, alcyl mercapto and alcylamino groups are present.

Salts, which are derived from the condensation products of certain, hydrocarbon-substituted phenols with Deriving formaldehyde or acetaldehyde are particularly effective. Such condensation products come in particular into consideration, which are made from a hydrocarbon-substituted phenol, which contains at least 4 carbon atoms in the substituent and with formaldehyde or acetaldehyde can react with the formation of resinous condensation products. These condensation products can be obtained by reacting with basic compounds of the metals from group II can be converted into salts, or the salts can be converted directly can be prepared by performing the condensation reaction in the presence of a basic compound of a metal of group II, preferably in the presence of an inert diluent.

In order to further improve the behavior of the lubricating oils according to the invention at high temperatures, they can be given 0.05 to 5 percent by weight of phenthiazine or a derivative that is substituted in the nucleus Incorporate phenthiazine. Such additives include, for example, 2,2'-dimethylthiodiphenylamine, 3-fluorothiodiphenylamine, 4-aminothiodiphenylamine, N-benzyl-2-aminothiodiphenylamine, Thiophenylnaphthylamine and thiodinaphthylamine in question.

A practically pure phenthiazine or nuclear substitution products of the same are preferably used, as some of the commercially available products when heated in the presence of lubricants tend to deposit a small amount of black precipitate.

The phenthiazine or its core substitution product improves the durability of the lubricating oil as opposed to oxidation at high temperatures, decreases and decreases the amount of varnish formed also the corrosion of metals, which otherwise intensified at high temperatures entry. Above all, however, the oil degradation is reduced at high temperatures and at the same time can also the amount of the metal salt used can be reduced without affecting the stability of the mixture

1 U4 / DOO

against oxidation and lacquer formation is impaired.

The following examples explain the invention in more detail. The parts and percentages mentioned refer to focus on the weight.

Mixture I.

63 parts of a mixture of esters, which 70% di (3,5,5-trimethylhexyl) sebacate, 20% di (2-ethylhexyl) sebacate and contains 10% di (3,5,5-trimethylhexyl) adipate;

34 parts of a solvent refined and dewaxed mineral lubricating oil having a viscosity index of 96 and a viscosity of 650 seconds Redwood I at 60 ° C = 739 SUS (60 ° C);
3 parts of concentrate A.

Mixture II

67.5 parts of the ester mixture according to mixture I;

29.5 parts of a solvent refined and dewaxed mineral lubricating oil having a viscosity index of 95 and a viscosity of 100O ¹ second Redwood I at 60 ° C = 1137 SUS (60 ° C); 3 parts of concentrate A.

Mixture III

69 parts of the ester mixture used in mixture I;

A refined with 28 parts of solvent and dewaxed mineral lubricating oil having a viscosity index of 95 and a viscosity of 1000 seconds Redwood at 60 ° C = 1137 SUS (6O ⁰ C);

3 parts of concentrate A.

Mixture IV

68.75 parts of the ester mixture used in Mixture I; 30 parts of the mineral lubricating oil used in Mixture II;
0.75 parts of Concentrate A;
0.5 parts phenthiazine.

Mixture V

66 parts of the ester mixture used in Mixture I;
30 parts of the mineral lubricating oil used in Mixture II;

3 parts of concentrate A;

1 part of a commercial pour point depressant.

The concentrate A is prepared as follows: 60 parts of paraoctylphenol are in 260 parts of a solution-refined mineral lubricating oil, which contains 1 part water and 9.7 parts calcium hydroxide contains, then 10.1 parts of paraformaldehyde are added. The mixture is brought to 85 ° C heated and the temperature increased in the course of 30 minutes to 95 ° C and during a further Held at 95 ° C for an hour. Then it is filtered hot. A concentrate with a calcium content is obtained from 1.2 "/ o.

In order to demonstrate the advantage of the present invention, the mixture IV was 40 times through a Injection nozzle passed through. Its viscosity before and after this treatment was the same. if but a mixture X of similar viscosity, which parts of the ester mixture used in mixture I, Parts of concentrate A and 14 parts of a polyalkyl methacrylate contained the same treatment was subjected, its viscosity decreased by more than 20 cSt.

Claims (8)

PAT ENTAN'S P R RATES: 1. Lubricating oil based on liquid esters of the general formula R'OOC.R.COOR ", where R is a divalent saturated aliphatic hydrocarbon radical and R 'and R "alkyl, Aralkyl or cycloalkyl radicals with more than 2 carbon atoms are characterized in that that it is a hydrocarbon lubricating oil with a viscosity index above 70 and a viscosity of at least 374 SUS at 38 ° C in an amount of 2 to 50 percent by weight based on the total weight of the ester-hydrocarbon-lubricating oil mixture, as well as 0.01 to 1 weight percent of the total lubricating oil, calculated on the metal, as a lubricant additive known salt of an aromatic carboxylic acid or a phenol with a metal of Group II of the Periodic Table. 2. Lubricating oil according to claim 1, characterized in that it is lubricating oil as a hydrocarbon contains one with a viscosity index above 85. 3. Lubricating oil according to claim 1 or 2, characterized in that it is used as a hydrocarbon lubricating oil contains one with a viscosity between 681 and 1364 SUS at 38 ° C. 4. Lubricating oil according to one of claims 1 to 3, characterized in that it is used as a hydrocarbon lubricating oil contains a mineral lubricating oil. 5. Lubricating oil according to claim 4, characterized in that it is a mineral lubricating oil contains solvent-refined mineral lubricating oil. 6. Lubricating oil according to claim 4 or 5, characterized in that it is used as a mineral lubricating oil contains a dewaxed mineral lubricating oil. 7. Lubricating oil according to claim 4, 5 or 6, characterized in that it is a mineral lubricating oil with a pour point depressant. 8. Lubricating oil according to claim 1 to 7, characterized in that it is also 0.05 to 5 percent by weight Contains phenthiazine or a derivative of phenthiazine which is substituted in the nucleus. Considered publications:
British Patent Nos. 668 663, 668 796;
French Patent No. 1063,912;
Industr. and Eng. Chemistry, (1950), p. 2442.